A.J. Loeve
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21 records found
1
Forensic Labscan
Examining the Examination: Improving Efficiency in Forensic Laboratories
Crimes involving weapons have increased in the Netherlands by 24 per cent in the past ten years, while the decrease in reported crimes has stabilised since 2018. Given that crimes with weapons are often complex and are often investigated in a multidisciplinary manner, these trends increase the demands for complex investigations within the Dutch justice system and, therefore, on the Netherlands Forensic Institute (NFI) as well. Here, the department of Human Biological Traces (BiS) examines evidentiary pieces ("Stukken Van Overtuiging', SVOs), such as knives, to find human biological traces, a process that is called the preliminary examination. The preliminary examination is labour-intensive, and with the increasing demands, could benefit from an optimised workflow. However, to identify and improve issues with the workflow, the workflow needs to be known.
In this observational study, all actions during the preliminary examination were observed and measured. These data were used to determine the duration of SVO examinations and laboratory sessions, their parts and their occurrences. The median duration of a laboratory session was 69 minutes, and the median duration of a completed SVO examination was 29 minutes. The duration of an SVO examination is affected by the category of the SVO, the difficulty level of the examination and the research question. Issues of the workflow were categorised as solvable in the short and long term. In the short term, the workflow could be improved by better managing materials and electronic devices. Furthermore, Processing sample kits could be less labour-intensive by adding codes to the sample containers and performing the examination on a work surface with ridges. The availability and reachability of experts may be improved by aligning their availability with the examination. By solving the bottlenecks concerning material management and processing sample kits, respectively, 15.9 and 56.7 hours per year could be won based on the examinations performed in 2024. In the long term, administrative tasks and examinations with the Crime-lite need further research to provide insights to save time. ...
In this observational study, all actions during the preliminary examination were observed and measured. These data were used to determine the duration of SVO examinations and laboratory sessions, their parts and their occurrences. The median duration of a laboratory session was 69 minutes, and the median duration of a completed SVO examination was 29 minutes. The duration of an SVO examination is affected by the category of the SVO, the difficulty level of the examination and the research question. Issues of the workflow were categorised as solvable in the short and long term. In the short term, the workflow could be improved by better managing materials and electronic devices. Furthermore, Processing sample kits could be less labour-intensive by adding codes to the sample containers and performing the examination on a work surface with ridges. The availability and reachability of experts may be improved by aligning their availability with the examination. By solving the bottlenecks concerning material management and processing sample kits, respectively, 15.9 and 56.7 hours per year could be won based on the examinations performed in 2024. In the long term, administrative tasks and examinations with the Crime-lite need further research to provide insights to save time. ...
Crimes involving weapons have increased in the Netherlands by 24 per cent in the past ten years, while the decrease in reported crimes has stabilised since 2018. Given that crimes with weapons are often complex and are often investigated in a multidisciplinary manner, these trends increase the demands for complex investigations within the Dutch justice system and, therefore, on the Netherlands Forensic Institute (NFI) as well. Here, the department of Human Biological Traces (BiS) examines evidentiary pieces ("Stukken Van Overtuiging', SVOs), such as knives, to find human biological traces, a process that is called the preliminary examination. The preliminary examination is labour-intensive, and with the increasing demands, could benefit from an optimised workflow. However, to identify and improve issues with the workflow, the workflow needs to be known.
In this observational study, all actions during the preliminary examination were observed and measured. These data were used to determine the duration of SVO examinations and laboratory sessions, their parts and their occurrences. The median duration of a laboratory session was 69 minutes, and the median duration of a completed SVO examination was 29 minutes. The duration of an SVO examination is affected by the category of the SVO, the difficulty level of the examination and the research question. Issues of the workflow were categorised as solvable in the short and long term. In the short term, the workflow could be improved by better managing materials and electronic devices. Furthermore, Processing sample kits could be less labour-intensive by adding codes to the sample containers and performing the examination on a work surface with ridges. The availability and reachability of experts may be improved by aligning their availability with the examination. By solving the bottlenecks concerning material management and processing sample kits, respectively, 15.9 and 56.7 hours per year could be won based on the examinations performed in 2024. In the long term, administrative tasks and examinations with the Crime-lite need further research to provide insights to save time.
In this observational study, all actions during the preliminary examination were observed and measured. These data were used to determine the duration of SVO examinations and laboratory sessions, their parts and their occurrences. The median duration of a laboratory session was 69 minutes, and the median duration of a completed SVO examination was 29 minutes. The duration of an SVO examination is affected by the category of the SVO, the difficulty level of the examination and the research question. Issues of the workflow were categorised as solvable in the short and long term. In the short term, the workflow could be improved by better managing materials and electronic devices. Furthermore, Processing sample kits could be less labour-intensive by adding codes to the sample containers and performing the examination on a work surface with ridges. The availability and reachability of experts may be improved by aligning their availability with the examination. By solving the bottlenecks concerning material management and processing sample kits, respectively, 15.9 and 56.7 hours per year could be won based on the examinations performed in 2024. In the long term, administrative tasks and examinations with the Crime-lite need further research to provide insights to save time.
Every year, 14 to 41 cases per 100,000 infants under 1 year old are diagnosed with inflicted head injury (IHI), primarily resulting from shaking trauma (IHI-ST) or blunt force trauma. Without reliable structural bending stiffness data of the infant’s neck, injury predictions using physical infant surrogates in shaking simulations remain highly uncertain, undermining both forensic and preventive studies. Due to ethical constraints, biomechanical properties of infant necks are scarce, limiting the biofidelity and validation possibilities for existing infant surrogates, such as anthropomorphic test dummies (ATDs). Currently, infant neck surrogates suffer from inadequate biofidelity concerning stiffness and validated range of motion, necessary to accurately simulate shaking trauma simulations.
This thesis aims to address the gap by exploring the design of a durable, adjustable stiffness surrogate neck, improving the accuracy of shaking experiments. Experimental stiffness values obtained from functional spine units (FSU) by Luck et al., extrapolated by Sullivan et al. were used as target values, suggesting stiffness ranges of 0.2 Nm/rad in flexion and 0.4 Nm/rad in extension for a 1.5-month-old infant. The design aims for a 90-degree ROM in flexion and extension, essential for accurate simulation of chin-to-chest and occiput-to-back contacts, both critical for assessing injury mechanisms.
A compliant monolithic hinge mechanism from Fowler et al. was proposed as the core mechanism, able to achieve large angular displacements through flexures. Finite element analysis was performed to optimize material and geometric parameters. Parametric modeling in ABAQUS identified the relationships between stiffness, stress, material properties, and hinge geometry. Based on these relationships, feasible prototype geometries were extracted, varying in flexure thickness, length, and width. Manufacturing was done using 3D printing with polylactic acid (PLA) and carbon fiber-reinforced polyethylene terephthalate glycol (PETG-CF).
Static experimental validation demonstrated achievable stiffness values at the lower boundary of target ranges while the upper bound was not reached, primarily due to anisotropy from 3D printing and material limitations. Despite these limitations, prototypes successfully reached the targeted ROM. Future research should incorporate dynamic testing to validate durability and head kinematics and should consider multi-degree-of-freedom designs to fully replicate infant neck biomechanics. Further challenges remain in replicating infant neck viscoelasticity and obtaining experimental infant data for validation.
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This thesis aims to address the gap by exploring the design of a durable, adjustable stiffness surrogate neck, improving the accuracy of shaking experiments. Experimental stiffness values obtained from functional spine units (FSU) by Luck et al., extrapolated by Sullivan et al. were used as target values, suggesting stiffness ranges of 0.2 Nm/rad in flexion and 0.4 Nm/rad in extension for a 1.5-month-old infant. The design aims for a 90-degree ROM in flexion and extension, essential for accurate simulation of chin-to-chest and occiput-to-back contacts, both critical for assessing injury mechanisms.
A compliant monolithic hinge mechanism from Fowler et al. was proposed as the core mechanism, able to achieve large angular displacements through flexures. Finite element analysis was performed to optimize material and geometric parameters. Parametric modeling in ABAQUS identified the relationships between stiffness, stress, material properties, and hinge geometry. Based on these relationships, feasible prototype geometries were extracted, varying in flexure thickness, length, and width. Manufacturing was done using 3D printing with polylactic acid (PLA) and carbon fiber-reinforced polyethylene terephthalate glycol (PETG-CF).
Static experimental validation demonstrated achievable stiffness values at the lower boundary of target ranges while the upper bound was not reached, primarily due to anisotropy from 3D printing and material limitations. Despite these limitations, prototypes successfully reached the targeted ROM. Future research should incorporate dynamic testing to validate durability and head kinematics and should consider multi-degree-of-freedom designs to fully replicate infant neck biomechanics. Further challenges remain in replicating infant neck viscoelasticity and obtaining experimental infant data for validation.
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Every year, 14 to 41 cases per 100,000 infants under 1 year old are diagnosed with inflicted head injury (IHI), primarily resulting from shaking trauma (IHI-ST) or blunt force trauma. Without reliable structural bending stiffness data of the infant’s neck, injury predictions using physical infant surrogates in shaking simulations remain highly uncertain, undermining both forensic and preventive studies. Due to ethical constraints, biomechanical properties of infant necks are scarce, limiting the biofidelity and validation possibilities for existing infant surrogates, such as anthropomorphic test dummies (ATDs). Currently, infant neck surrogates suffer from inadequate biofidelity concerning stiffness and validated range of motion, necessary to accurately simulate shaking trauma simulations.
This thesis aims to address the gap by exploring the design of a durable, adjustable stiffness surrogate neck, improving the accuracy of shaking experiments. Experimental stiffness values obtained from functional spine units (FSU) by Luck et al., extrapolated by Sullivan et al. were used as target values, suggesting stiffness ranges of 0.2 Nm/rad in flexion and 0.4 Nm/rad in extension for a 1.5-month-old infant. The design aims for a 90-degree ROM in flexion and extension, essential for accurate simulation of chin-to-chest and occiput-to-back contacts, both critical for assessing injury mechanisms.
A compliant monolithic hinge mechanism from Fowler et al. was proposed as the core mechanism, able to achieve large angular displacements through flexures. Finite element analysis was performed to optimize material and geometric parameters. Parametric modeling in ABAQUS identified the relationships between stiffness, stress, material properties, and hinge geometry. Based on these relationships, feasible prototype geometries were extracted, varying in flexure thickness, length, and width. Manufacturing was done using 3D printing with polylactic acid (PLA) and carbon fiber-reinforced polyethylene terephthalate glycol (PETG-CF).
Static experimental validation demonstrated achievable stiffness values at the lower boundary of target ranges while the upper bound was not reached, primarily due to anisotropy from 3D printing and material limitations. Despite these limitations, prototypes successfully reached the targeted ROM. Future research should incorporate dynamic testing to validate durability and head kinematics and should consider multi-degree-of-freedom designs to fully replicate infant neck biomechanics. Further challenges remain in replicating infant neck viscoelasticity and obtaining experimental infant data for validation.
This thesis aims to address the gap by exploring the design of a durable, adjustable stiffness surrogate neck, improving the accuracy of shaking experiments. Experimental stiffness values obtained from functional spine units (FSU) by Luck et al., extrapolated by Sullivan et al. were used as target values, suggesting stiffness ranges of 0.2 Nm/rad in flexion and 0.4 Nm/rad in extension for a 1.5-month-old infant. The design aims for a 90-degree ROM in flexion and extension, essential for accurate simulation of chin-to-chest and occiput-to-back contacts, both critical for assessing injury mechanisms.
A compliant monolithic hinge mechanism from Fowler et al. was proposed as the core mechanism, able to achieve large angular displacements through flexures. Finite element analysis was performed to optimize material and geometric parameters. Parametric modeling in ABAQUS identified the relationships between stiffness, stress, material properties, and hinge geometry. Based on these relationships, feasible prototype geometries were extracted, varying in flexure thickness, length, and width. Manufacturing was done using 3D printing with polylactic acid (PLA) and carbon fiber-reinforced polyethylene terephthalate glycol (PETG-CF).
Static experimental validation demonstrated achievable stiffness values at the lower boundary of target ranges while the upper bound was not reached, primarily due to anisotropy from 3D printing and material limitations. Despite these limitations, prototypes successfully reached the targeted ROM. Future research should incorporate dynamic testing to validate durability and head kinematics and should consider multi-degree-of-freedom designs to fully replicate infant neck biomechanics. Further challenges remain in replicating infant neck viscoelasticity and obtaining experimental infant data for validation.
Burnmeister: Analytical Improvements, Calibration, and Workflow Validation for the Pyrotechnic and Explosive Materials Analysis Device
Toward objective combustion characterization and identification of pyrotechnic mixtures
The increasing number of explosive-related incidents highlights the need for objective techniques to characterize and identify pyrotechnic materials, including explosives. Current tech- niques, such as the "hot needle test", rely on subjective human ob- servations of flame color, combustion duration, and intensity, which limits reproducibility and accuracy of the data. In this study, the previously developed Pyrotechnic and Explosive Materials Analysis Device (PEMAD) and its analytical workflow were improved, cali- brated, and validated. Combustions of compositions with varying grain sizes, oxidizer/fuel ratios, color compositions, and sample volumes were recorded under controlled conditions. The camera was calibrated against reference values from a spectrometer and a light-meter. Color calibration reduced the deviations between the camera and the spectrometer measurements from 27-35% to 2- 3%, enabling accurate flame color characterization. Intensity cali- bration allowed pixel values to be expressed in Lux, providing inter- pretable and comparable results across all fibers, although with lim- itations. Validation confirmed that the PEMAD detects differences in combustion duration, flame color, and intensity for compositions with varying properties. Detection limits were established: slower combustions, such as gunpowder, could be reliably measured, while extremely fast combustions, such as flash powder, exceeded the upper limit for accurate peak intensity estimation. The observed sensitivity to small variations in sample volume underscores the need for strict and consistent sample preparation. With larger datasets, the PEMAD could serve as an objective method for the identification and classification of unidentified explosive materials in forensic applications
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The increasing number of explosive-related incidents highlights the need for objective techniques to characterize and identify pyrotechnic materials, including explosives. Current tech- niques, such as the "hot needle test", rely on subjective human ob- servations of flame color, combustion duration, and intensity, which limits reproducibility and accuracy of the data. In this study, the previously developed Pyrotechnic and Explosive Materials Analysis Device (PEMAD) and its analytical workflow were improved, cali- brated, and validated. Combustions of compositions with varying grain sizes, oxidizer/fuel ratios, color compositions, and sample volumes were recorded under controlled conditions. The camera was calibrated against reference values from a spectrometer and a light-meter. Color calibration reduced the deviations between the camera and the spectrometer measurements from 27-35% to 2- 3%, enabling accurate flame color characterization. Intensity cali- bration allowed pixel values to be expressed in Lux, providing inter- pretable and comparable results across all fibers, although with lim- itations. Validation confirmed that the PEMAD detects differences in combustion duration, flame color, and intensity for compositions with varying properties. Detection limits were established: slower combustions, such as gunpowder, could be reliably measured, while extremely fast combustions, such as flash powder, exceeded the upper limit for accurate peak intensity estimation. The observed sensitivity to small variations in sample volume underscores the need for strict and consistent sample preparation. With larger datasets, the PEMAD could serve as an objective method for the identification and classification of unidentified explosive materials in forensic applications
Transporting infants in bicycle trailers
A valid alternative scenario for Inflicted Head Injury by Shaking Trauma?
Inflicted Head Injury by Shaking Trauma (IHI-ST) is a form of abusive trauma caused by violent shaking, which children under the age of one are particularly vulnerable to. Because the exact injury mechanisms of IHI-ST remain unclear and direct evidence such as eyewitnesses is often lacking, legal cases concerning suspected IHI-ST often debate the actual cause of the diagnosed head trauma: Was it shaking, or was it an alternative “accidental” scenario raised by the defendant? One scenario that is sometimes raised is that of a rough trailer ride over bumpy terrain, where the transported infant was exposed to repeated shaking for the duration of minutes to hours. However, the validity of this alternative scenario has not been studied, yet. Therefore, the aim of this study was to evaluate the plausibility of the trailer scenario as a cause for IHI-ST. To get insight in the plausibility of this scenario without performing ethically questionable experiments, we recorded the complete head and torso kinematics of an infant dummy during controlled bicycle trailer rides over bumps with different heights, slopes, and at different trailer speeds. Due to limited biofidelity of the surrogate and the absence of valid thresholds it is currently impossible to know exactly which linear and angular accelerations and which degree of rotational nature of head motion would lead to injury. Therefore, we compared the recorded kinematics of the trailer scenario with recently reported values in the same instrumented dummy under violent shaking circumstances, assuming that the shaking scenario leads to injury. We found that the head motion during rough trailer rides in worst-case conditions (minimized impact damping and the absence of a head rest) was, even at the highest speeds and steepest and largest bumps, less rotational than violent shaking, and while the torso reached similar peak linear accelerations, the head angular accelerations barely reached half of those during violent shaking. However, although the head angular accelerations were lower, a low injury risk for head and neck injuries due to trailer rides can not be concluded yet, because the duration of the infant’s exposure to these accelerations is much longer (minutes to hours) than during violent shaking (a few seconds).
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Inflicted Head Injury by Shaking Trauma (IHI-ST) is a form of abusive trauma caused by violent shaking, which children under the age of one are particularly vulnerable to. Because the exact injury mechanisms of IHI-ST remain unclear and direct evidence such as eyewitnesses is often lacking, legal cases concerning suspected IHI-ST often debate the actual cause of the diagnosed head trauma: Was it shaking, or was it an alternative “accidental” scenario raised by the defendant? One scenario that is sometimes raised is that of a rough trailer ride over bumpy terrain, where the transported infant was exposed to repeated shaking for the duration of minutes to hours. However, the validity of this alternative scenario has not been studied, yet. Therefore, the aim of this study was to evaluate the plausibility of the trailer scenario as a cause for IHI-ST. To get insight in the plausibility of this scenario without performing ethically questionable experiments, we recorded the complete head and torso kinematics of an infant dummy during controlled bicycle trailer rides over bumps with different heights, slopes, and at different trailer speeds. Due to limited biofidelity of the surrogate and the absence of valid thresholds it is currently impossible to know exactly which linear and angular accelerations and which degree of rotational nature of head motion would lead to injury. Therefore, we compared the recorded kinematics of the trailer scenario with recently reported values in the same instrumented dummy under violent shaking circumstances, assuming that the shaking scenario leads to injury. We found that the head motion during rough trailer rides in worst-case conditions (minimized impact damping and the absence of a head rest) was, even at the highest speeds and steepest and largest bumps, less rotational than violent shaking, and while the torso reached similar peak linear accelerations, the head angular accelerations barely reached half of those during violent shaking. However, although the head angular accelerations were lower, a low injury risk for head and neck injuries due to trailer rides can not be concluded yet, because the duration of the infant’s exposure to these accelerations is much longer (minutes to hours) than during violent shaking (a few seconds).
Assessing piglet model suitability for inflicted head injury by shaking trauma in infants
The difference in pressure variations inside the eye between pig and infant eyes of an infant during violent shaking
This study investigates eye pressure variations within the eye between pigs and humans during an IHI-ST event, focusing on anatomical differences in orbital cavities. Eight anatomical differences were identified through literature research, with two deemed most relevant for pressure variation. Four orbits were created to combine eye orientation and orbital closure. Subsequently, handcrafted eye models were tested using a shaking simulator.
This research has led to the creation of a test setup capable of simulating the shaking motion of an IHI-ST event. Initial steps have been taken to investigate pressure buildup in the eye during these movements, yielding preliminary results on the effects of anatomical differences between the eyes of pigs and humans.
The results indicate that closed orbits exhibit higher relative eye pressure compared to open orbits. Additionally, higher eye pressures were observed in humans than in pig, in line with the expectations. This indicates that due to the anatomical differences between the eyes of pigs and humans, higher eye pressure occurs during shaking in humans compared to pigs. The results of this study thus suggest a cautious conclusion that pigs may not be suitable for research material in the context of IHI-ST. The study's limitations include the use of simplified eye models, which affect external validity, and the lack of factors such as neck stiffness.
Overall, this research lays the groundwork for future studies on intraocular pressure during shaking events, emphasizing the need for improved experimental designs and more accurate models to enhance understanding and clinical outcomes related to retinal haemorrhage. ...
This research has led to the creation of a test setup capable of simulating the shaking motion of an IHI-ST event. Initial steps have been taken to investigate pressure buildup in the eye during these movements, yielding preliminary results on the effects of anatomical differences between the eyes of pigs and humans.
The results indicate that closed orbits exhibit higher relative eye pressure compared to open orbits. Additionally, higher eye pressures were observed in humans than in pig, in line with the expectations. This indicates that due to the anatomical differences between the eyes of pigs and humans, higher eye pressure occurs during shaking in humans compared to pigs. The results of this study thus suggest a cautious conclusion that pigs may not be suitable for research material in the context of IHI-ST. The study's limitations include the use of simplified eye models, which affect external validity, and the lack of factors such as neck stiffness.
Overall, this research lays the groundwork for future studies on intraocular pressure during shaking events, emphasizing the need for improved experimental designs and more accurate models to enhance understanding and clinical outcomes related to retinal haemorrhage. ...
This study investigates eye pressure variations within the eye between pigs and humans during an IHI-ST event, focusing on anatomical differences in orbital cavities. Eight anatomical differences were identified through literature research, with two deemed most relevant for pressure variation. Four orbits were created to combine eye orientation and orbital closure. Subsequently, handcrafted eye models were tested using a shaking simulator.
This research has led to the creation of a test setup capable of simulating the shaking motion of an IHI-ST event. Initial steps have been taken to investigate pressure buildup in the eye during these movements, yielding preliminary results on the effects of anatomical differences between the eyes of pigs and humans.
The results indicate that closed orbits exhibit higher relative eye pressure compared to open orbits. Additionally, higher eye pressures were observed in humans than in pig, in line with the expectations. This indicates that due to the anatomical differences between the eyes of pigs and humans, higher eye pressure occurs during shaking in humans compared to pigs. The results of this study thus suggest a cautious conclusion that pigs may not be suitable for research material in the context of IHI-ST. The study's limitations include the use of simplified eye models, which affect external validity, and the lack of factors such as neck stiffness.
Overall, this research lays the groundwork for future studies on intraocular pressure during shaking events, emphasizing the need for improved experimental designs and more accurate models to enhance understanding and clinical outcomes related to retinal haemorrhage.
This research has led to the creation of a test setup capable of simulating the shaking motion of an IHI-ST event. Initial steps have been taken to investigate pressure buildup in the eye during these movements, yielding preliminary results on the effects of anatomical differences between the eyes of pigs and humans.
The results indicate that closed orbits exhibit higher relative eye pressure compared to open orbits. Additionally, higher eye pressures were observed in humans than in pig, in line with the expectations. This indicates that due to the anatomical differences between the eyes of pigs and humans, higher eye pressure occurs during shaking in humans compared to pigs. The results of this study thus suggest a cautious conclusion that pigs may not be suitable for research material in the context of IHI-ST. The study's limitations include the use of simplified eye models, which affect external validity, and the lack of factors such as neck stiffness.
Overall, this research lays the groundwork for future studies on intraocular pressure during shaking events, emphasizing the need for improved experimental designs and more accurate models to enhance understanding and clinical outcomes related to retinal haemorrhage.
Accurately determining the early Post-Mortem Interval (PMI), the period shortly after death, is critical for reconstructing the timeline of suspected crimes. The PHOEBE model, a new thermodynamic finite-difference model that simulates body cooling, significantly improves PMI estimations but is highly sensitive to the thermal conductivity of the deceased’s clothing. This study introduces the Therminus-K3 prototype, an affordable and portable Guarded Hot Plate apparatus, designed specifically to support the PHOEBE model by providing rapid, non- destructive thermal conductivity measurements of clothing garments. The Therminus-K3 features a compact Hot Stage with resistive PCB heaters, a Cold Stage with thermoelectric coolers, and a Compression Stage that replicates real-world fabric compression conditions. This design allows for rapid attainment of steady-state conditions and thermal conductivity measurements within 25 minutes, essential for time-sensitive forensic investigations. Preliminary results suggest that the Therminus-K3 prototype measures with a precision of less than ±1% and a measurement uncertainty below ±1.5%, but further testing is required to confirm its overall accuracy. With a material cost of just €404.39, the Therminus-K3 offers forensic practitioners a more affordable option to accurately measure the thermal conductivity of clothing, thereby enhancing the accuracy of PMI estimations. Initial tests suggest that integrating the Therminus-K3 with the PHOEBE model could improve PMI estimations by over 30 minutes. Its ongoing development holds significant potential to further impact and improve the determination of time of death in forensic scenarios in a more efficient and reliable manner.
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Accurately determining the early Post-Mortem Interval (PMI), the period shortly after death, is critical for reconstructing the timeline of suspected crimes. The PHOEBE model, a new thermodynamic finite-difference model that simulates body cooling, significantly improves PMI estimations but is highly sensitive to the thermal conductivity of the deceased’s clothing. This study introduces the Therminus-K3 prototype, an affordable and portable Guarded Hot Plate apparatus, designed specifically to support the PHOEBE model by providing rapid, non- destructive thermal conductivity measurements of clothing garments. The Therminus-K3 features a compact Hot Stage with resistive PCB heaters, a Cold Stage with thermoelectric coolers, and a Compression Stage that replicates real-world fabric compression conditions. This design allows for rapid attainment of steady-state conditions and thermal conductivity measurements within 25 minutes, essential for time-sensitive forensic investigations. Preliminary results suggest that the Therminus-K3 prototype measures with a precision of less than ±1% and a measurement uncertainty below ±1.5%, but further testing is required to confirm its overall accuracy. With a material cost of just €404.39, the Therminus-K3 offers forensic practitioners a more affordable option to accurately measure the thermal conductivity of clothing, thereby enhancing the accuracy of PMI estimations. Initial tests suggest that integrating the Therminus-K3 with the PHOEBE model could improve PMI estimations by over 30 minutes. Its ongoing development holds significant potential to further impact and improve the determination of time of death in forensic scenarios in a more efficient and reliable manner.
Ensuring reliable and safe performance of medical devices in healthcare institutions is crucial for the wellbeing of patients. For this, physiological simulators may be used, which provide reference signals to compare against. The usage of physiological simulators, such as ECG simulators, as medical device testers is widely extended in high-income countries. However, their high cost and need for frequent calibration by the manufacturer make their availability and usage in low-resource settings (LRs) unfeasible. Remote healthcare facilities, low- and middle-income countries (LMICs), and hospitals in general would highly benefit from new designs of simulators that can be produced, repaired and maintained locally. Therefore, we present the design of an affordable, portable Arduino UNO-based prototype ECG simulator with the novel feature of visual indicators for self-calibration checks. The ECG simulator was built with affordable and broadly available components and tools, retrieved from an educational electronics workshop. The current prototype can be used to test 3-lead ECG meters. It reproduces a lead II waveform extracted from MIT-BIH database, with 1.3 mV peak-to-peak and 0.1 mV negative offset. Heart rage simulation ranges from 35 to 130 bpm, in steps of 5 bpm. Signal data points defining a desired waveform and heart rate can be uploaded into the simulator via the user-friendly and open-source Arduino software. The simulator could also be modified to generate 10- or 12-leads by upscaling the electronics and adding more storage space. Analog signal generation is based on a pulse-width modulation signal, which is smoothened by a low-pass filter and decreased in amplitude with operational amplifiers, which also add a negative voltage offset. Visual indicators enable simulated frequency and amplitude checks without the need of external tools, while amplitude can be calibrated manually. Additionally, rechargeable batteries facilitate on-site testing of medical equipment. Evaluation of the prototype included performance and functionality tests. HR and amplitude accuracy of the simulated signal were quantified and compared to those from a commercial simulator. Lastly, the performance of the simulator in a real scenario was tested at the Green Pastures Hospital of Pokhara, Nepal. Functionality tests proved the correct detection of the simulated signal by 6 patient monitors of different models, manufacturers and purchase year.
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Ensuring reliable and safe performance of medical devices in healthcare institutions is crucial for the wellbeing of patients. For this, physiological simulators may be used, which provide reference signals to compare against. The usage of physiological simulators, such as ECG simulators, as medical device testers is widely extended in high-income countries. However, their high cost and need for frequent calibration by the manufacturer make their availability and usage in low-resource settings (LRs) unfeasible. Remote healthcare facilities, low- and middle-income countries (LMICs), and hospitals in general would highly benefit from new designs of simulators that can be produced, repaired and maintained locally. Therefore, we present the design of an affordable, portable Arduino UNO-based prototype ECG simulator with the novel feature of visual indicators for self-calibration checks. The ECG simulator was built with affordable and broadly available components and tools, retrieved from an educational electronics workshop. The current prototype can be used to test 3-lead ECG meters. It reproduces a lead II waveform extracted from MIT-BIH database, with 1.3 mV peak-to-peak and 0.1 mV negative offset. Heart rage simulation ranges from 35 to 130 bpm, in steps of 5 bpm. Signal data points defining a desired waveform and heart rate can be uploaded into the simulator via the user-friendly and open-source Arduino software. The simulator could also be modified to generate 10- or 12-leads by upscaling the electronics and adding more storage space. Analog signal generation is based on a pulse-width modulation signal, which is smoothened by a low-pass filter and decreased in amplitude with operational amplifiers, which also add a negative voltage offset. Visual indicators enable simulated frequency and amplitude checks without the need of external tools, while amplitude can be calibrated manually. Additionally, rechargeable batteries facilitate on-site testing of medical equipment. Evaluation of the prototype included performance and functionality tests. HR and amplitude accuracy of the simulated signal were quantified and compared to those from a commercial simulator. Lastly, the performance of the simulator in a real scenario was tested at the Green Pastures Hospital of Pokhara, Nepal. Functionality tests proved the correct detection of the simulated signal by 6 patient monitors of different models, manufacturers and purchase year.
Aerosol production via electro and plasma devices
In-vitro PlasmaJet and ERBE tissue effects and aerosol production affecting factors evaluation
Surgical aerosols in other words plumes are produced during thermal tissue destruction in medical operations. The cellular debris in the form of particulate matter may contain viruses and harmful chemical compounds which can lead to an infectious transmission in case of inhalation.
The goal of this study was to design and produce an experimental setup to simulate Plasmajet (PJ) and ERBE experiments with minimal airflow disturbances. Such setup can lead to defining the lowest aerosol production conditions, investigating the production-affecting factors, and evaluating tissue effects to promote a safer and healthier surgical environment for both healthcare workers and patients. A clear correlation between the aerosol production affecting factors and particle counts was established for particle sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10.0 µm.
The results of the experiments showed that among all experimental conditions, the PJ coagulation mode with fast operation yielded the lowest aerosol counts. In cutting mode, the lowest aerosol counts were also produced by PJ with fast operation speed. However, between speed and aerosol counts, no statistically significant correlation was found.
Upon analyzing the correlation between aerosol counts and tissue effects, it was determined that, for ERBE device, higher aerosol counts were associated with darker tissue effects. In the case of the PJ device, this relationship persisted in the cutting mode, whereas no connection between tissue effect and particle counts was observed in the coagulation mode.
Further investigation on the toxicity of the produced particulate matter and establishment of a clear minimal aerosol intake is recommended. Until then, preventive measures such as implementing local exhaust ventilation and using surgical N95 masks are strongly advised to minimize aerosol inhalation.
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The goal of this study was to design and produce an experimental setup to simulate Plasmajet (PJ) and ERBE experiments with minimal airflow disturbances. Such setup can lead to defining the lowest aerosol production conditions, investigating the production-affecting factors, and evaluating tissue effects to promote a safer and healthier surgical environment for both healthcare workers and patients. A clear correlation between the aerosol production affecting factors and particle counts was established for particle sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10.0 µm.
The results of the experiments showed that among all experimental conditions, the PJ coagulation mode with fast operation yielded the lowest aerosol counts. In cutting mode, the lowest aerosol counts were also produced by PJ with fast operation speed. However, between speed and aerosol counts, no statistically significant correlation was found.
Upon analyzing the correlation between aerosol counts and tissue effects, it was determined that, for ERBE device, higher aerosol counts were associated with darker tissue effects. In the case of the PJ device, this relationship persisted in the cutting mode, whereas no connection between tissue effect and particle counts was observed in the coagulation mode.
Further investigation on the toxicity of the produced particulate matter and establishment of a clear minimal aerosol intake is recommended. Until then, preventive measures such as implementing local exhaust ventilation and using surgical N95 masks are strongly advised to minimize aerosol inhalation.
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Surgical aerosols in other words plumes are produced during thermal tissue destruction in medical operations. The cellular debris in the form of particulate matter may contain viruses and harmful chemical compounds which can lead to an infectious transmission in case of inhalation.
The goal of this study was to design and produce an experimental setup to simulate Plasmajet (PJ) and ERBE experiments with minimal airflow disturbances. Such setup can lead to defining the lowest aerosol production conditions, investigating the production-affecting factors, and evaluating tissue effects to promote a safer and healthier surgical environment for both healthcare workers and patients. A clear correlation between the aerosol production affecting factors and particle counts was established for particle sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10.0 µm.
The results of the experiments showed that among all experimental conditions, the PJ coagulation mode with fast operation yielded the lowest aerosol counts. In cutting mode, the lowest aerosol counts were also produced by PJ with fast operation speed. However, between speed and aerosol counts, no statistically significant correlation was found.
Upon analyzing the correlation between aerosol counts and tissue effects, it was determined that, for ERBE device, higher aerosol counts were associated with darker tissue effects. In the case of the PJ device, this relationship persisted in the cutting mode, whereas no connection between tissue effect and particle counts was observed in the coagulation mode.
Further investigation on the toxicity of the produced particulate matter and establishment of a clear minimal aerosol intake is recommended. Until then, preventive measures such as implementing local exhaust ventilation and using surgical N95 masks are strongly advised to minimize aerosol inhalation.
The goal of this study was to design and produce an experimental setup to simulate Plasmajet (PJ) and ERBE experiments with minimal airflow disturbances. Such setup can lead to defining the lowest aerosol production conditions, investigating the production-affecting factors, and evaluating tissue effects to promote a safer and healthier surgical environment for both healthcare workers and patients. A clear correlation between the aerosol production affecting factors and particle counts was established for particle sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10.0 µm.
The results of the experiments showed that among all experimental conditions, the PJ coagulation mode with fast operation yielded the lowest aerosol counts. In cutting mode, the lowest aerosol counts were also produced by PJ with fast operation speed. However, between speed and aerosol counts, no statistically significant correlation was found.
Upon analyzing the correlation between aerosol counts and tissue effects, it was determined that, for ERBE device, higher aerosol counts were associated with darker tissue effects. In the case of the PJ device, this relationship persisted in the cutting mode, whereas no connection between tissue effect and particle counts was observed in the coagulation mode.
Further investigation on the toxicity of the produced particulate matter and establishment of a clear minimal aerosol intake is recommended. Until then, preventive measures such as implementing local exhaust ventilation and using surgical N95 masks are strongly advised to minimize aerosol inhalation.
QuickScale 2.0
The development of a user-oriented interface for a weighing tool utilized in on-site weight measurement. Aiding in forensic early post-mortem interval estimation
Post-mortem interval estimation (PMI) is a key part of forensic investigation. Accurately obtaining a PMI early in the investigative process improves the reconstruction of events, directs follow-up research and narrows down suspects in case of homicide. Currently, PMI is determined using Henssge’s nomogram requiring ambient temperature, rectal temperature, an estimated body weight and an estimated correcting factor to account for the clothing of the deceased. These body weight and correcting factor estimates are subjective and can lead to errors of up to 14 hours from the actual PMI.
To improve the accuracy of the PMI Academic Medical Centre (AMC) in Amsterdam, TU Delft, the Dutch Forensic Institute and the Dutch police initiated the Therminus project. Using the Wilks Model [1]with specialised equipment can increase the accuracy of the PMI by up to a 15-minute margin of error under ideal circumstances and up to 3.2 hours under non-ideal circumstances.
For the Wilks model, the weight of the deceased remains an important input and the QuickScale was developed as a specialised tool to provide this information to forensic investigators at the crime scene. This report contains the development of the second iteration of the QuickScale, the QuickScale 2.0. Objectives of this development were:
1. To Finish the QuickScale prototype, design the modules needed for building in the electronics and for adding user-friendly, intuitive controls.
2. To design and conduct usability studies with forensic investigators and use the obtained information to further improve the QuickScale construction, electronics and usability.
Using a design analysis and usability engineering approach for the QuickScale design and user interface respectively. The QuickScale design was calibrated, and validated and possible improvements were identified. Three different user interfaces were developed and usability studies were conducted for groups of students and forensic investigators. New design requirements were derived from both the design analysis and usability studies.
The resulting QuickScale 2.0 design incorporated the user interface that resulted in the least user errors. It met 27 out of the total 30 design criteria and contains:
• An ambidextrous user interface.
• Correcting springs for the non-linearity of the load cell when measuring weights below 20kg.
• Handlebars with improved grip which can easily be extended to accommodate more users.
• Safety labels with an abbreviated guide on the field use and stickers indicating the controls
The un-met design criteria were an indicator of remaining battery life and the possibility that both units can display a difference in weight larger than 0.5 kgs, especially at the start of weight measurements. As this design still needs to be produced, it needs to be tested and evaluated. Special care should be taken when calibrating the QuickScale 2.0 and altering the calibrating method might be necessary. Furthermore, it is recommended to integrate the QuickScale 2.0 with other Therminus equipment in future evaluations.
All in all the QuickScale 2.0 is a user-oriented step toward more accurate post-mortem interval estimation.
...
To improve the accuracy of the PMI Academic Medical Centre (AMC) in Amsterdam, TU Delft, the Dutch Forensic Institute and the Dutch police initiated the Therminus project. Using the Wilks Model [1]with specialised equipment can increase the accuracy of the PMI by up to a 15-minute margin of error under ideal circumstances and up to 3.2 hours under non-ideal circumstances.
For the Wilks model, the weight of the deceased remains an important input and the QuickScale was developed as a specialised tool to provide this information to forensic investigators at the crime scene. This report contains the development of the second iteration of the QuickScale, the QuickScale 2.0. Objectives of this development were:
1. To Finish the QuickScale prototype, design the modules needed for building in the electronics and for adding user-friendly, intuitive controls.
2. To design and conduct usability studies with forensic investigators and use the obtained information to further improve the QuickScale construction, electronics and usability.
Using a design analysis and usability engineering approach for the QuickScale design and user interface respectively. The QuickScale design was calibrated, and validated and possible improvements were identified. Three different user interfaces were developed and usability studies were conducted for groups of students and forensic investigators. New design requirements were derived from both the design analysis and usability studies.
The resulting QuickScale 2.0 design incorporated the user interface that resulted in the least user errors. It met 27 out of the total 30 design criteria and contains:
• An ambidextrous user interface.
• Correcting springs for the non-linearity of the load cell when measuring weights below 20kg.
• Handlebars with improved grip which can easily be extended to accommodate more users.
• Safety labels with an abbreviated guide on the field use and stickers indicating the controls
The un-met design criteria were an indicator of remaining battery life and the possibility that both units can display a difference in weight larger than 0.5 kgs, especially at the start of weight measurements. As this design still needs to be produced, it needs to be tested and evaluated. Special care should be taken when calibrating the QuickScale 2.0 and altering the calibrating method might be necessary. Furthermore, it is recommended to integrate the QuickScale 2.0 with other Therminus equipment in future evaluations.
All in all the QuickScale 2.0 is a user-oriented step toward more accurate post-mortem interval estimation.
...
Post-mortem interval estimation (PMI) is a key part of forensic investigation. Accurately obtaining a PMI early in the investigative process improves the reconstruction of events, directs follow-up research and narrows down suspects in case of homicide. Currently, PMI is determined using Henssge’s nomogram requiring ambient temperature, rectal temperature, an estimated body weight and an estimated correcting factor to account for the clothing of the deceased. These body weight and correcting factor estimates are subjective and can lead to errors of up to 14 hours from the actual PMI.
To improve the accuracy of the PMI Academic Medical Centre (AMC) in Amsterdam, TU Delft, the Dutch Forensic Institute and the Dutch police initiated the Therminus project. Using the Wilks Model [1]with specialised equipment can increase the accuracy of the PMI by up to a 15-minute margin of error under ideal circumstances and up to 3.2 hours under non-ideal circumstances.
For the Wilks model, the weight of the deceased remains an important input and the QuickScale was developed as a specialised tool to provide this information to forensic investigators at the crime scene. This report contains the development of the second iteration of the QuickScale, the QuickScale 2.0. Objectives of this development were:
1. To Finish the QuickScale prototype, design the modules needed for building in the electronics and for adding user-friendly, intuitive controls.
2. To design and conduct usability studies with forensic investigators and use the obtained information to further improve the QuickScale construction, electronics and usability.
Using a design analysis and usability engineering approach for the QuickScale design and user interface respectively. The QuickScale design was calibrated, and validated and possible improvements were identified. Three different user interfaces were developed and usability studies were conducted for groups of students and forensic investigators. New design requirements were derived from both the design analysis and usability studies.
The resulting QuickScale 2.0 design incorporated the user interface that resulted in the least user errors. It met 27 out of the total 30 design criteria and contains:
• An ambidextrous user interface.
• Correcting springs for the non-linearity of the load cell when measuring weights below 20kg.
• Handlebars with improved grip which can easily be extended to accommodate more users.
• Safety labels with an abbreviated guide on the field use and stickers indicating the controls
The un-met design criteria were an indicator of remaining battery life and the possibility that both units can display a difference in weight larger than 0.5 kgs, especially at the start of weight measurements. As this design still needs to be produced, it needs to be tested and evaluated. Special care should be taken when calibrating the QuickScale 2.0 and altering the calibrating method might be necessary. Furthermore, it is recommended to integrate the QuickScale 2.0 with other Therminus equipment in future evaluations.
All in all the QuickScale 2.0 is a user-oriented step toward more accurate post-mortem interval estimation.
To improve the accuracy of the PMI Academic Medical Centre (AMC) in Amsterdam, TU Delft, the Dutch Forensic Institute and the Dutch police initiated the Therminus project. Using the Wilks Model [1]with specialised equipment can increase the accuracy of the PMI by up to a 15-minute margin of error under ideal circumstances and up to 3.2 hours under non-ideal circumstances.
For the Wilks model, the weight of the deceased remains an important input and the QuickScale was developed as a specialised tool to provide this information to forensic investigators at the crime scene. This report contains the development of the second iteration of the QuickScale, the QuickScale 2.0. Objectives of this development were:
1. To Finish the QuickScale prototype, design the modules needed for building in the electronics and for adding user-friendly, intuitive controls.
2. To design and conduct usability studies with forensic investigators and use the obtained information to further improve the QuickScale construction, electronics and usability.
Using a design analysis and usability engineering approach for the QuickScale design and user interface respectively. The QuickScale design was calibrated, and validated and possible improvements were identified. Three different user interfaces were developed and usability studies were conducted for groups of students and forensic investigators. New design requirements were derived from both the design analysis and usability studies.
The resulting QuickScale 2.0 design incorporated the user interface that resulted in the least user errors. It met 27 out of the total 30 design criteria and contains:
• An ambidextrous user interface.
• Correcting springs for the non-linearity of the load cell when measuring weights below 20kg.
• Handlebars with improved grip which can easily be extended to accommodate more users.
• Safety labels with an abbreviated guide on the field use and stickers indicating the controls
The un-met design criteria were an indicator of remaining battery life and the possibility that both units can display a difference in weight larger than 0.5 kgs, especially at the start of weight measurements. As this design still needs to be produced, it needs to be tested and evaluated. Special care should be taken when calibrating the QuickScale 2.0 and altering the calibrating method might be necessary. Furthermore, it is recommended to integrate the QuickScale 2.0 with other Therminus equipment in future evaluations.
All in all the QuickScale 2.0 is a user-oriented step toward more accurate post-mortem interval estimation.
The vital role of surgery in healthcare requires constant attention for improvement. Surgical process modelling is an innovative and rather recently introduced approach for tackling the issues in complex surgeries. The goal of this thesis is to structure the strategies in surgical process modelling and to seek the applications of surgical process models (SPMs) with computer-based technologies to address various challenges in different surgeries. These challenges include surgical training, introduction of new technology and tools, surgery planning, prediction of surgical activities and surgery outcome, and intra-operative guidance of surgeons.
This thesis is composed of two main parts. The first concerns the strategies for establishment of the process models. The second focuses on the application of the surgical process modelling techniques on surgery improvement..... ...
This thesis is composed of two main parts. The first concerns the strategies for establishment of the process models. The second focuses on the application of the surgical process modelling techniques on surgery improvement..... ...
The vital role of surgery in healthcare requires constant attention for improvement. Surgical process modelling is an innovative and rather recently introduced approach for tackling the issues in complex surgeries. The goal of this thesis is to structure the strategies in surgical process modelling and to seek the applications of surgical process models (SPMs) with computer-based technologies to address various challenges in different surgeries. These challenges include surgical training, introduction of new technology and tools, surgery planning, prediction of surgical activities and surgery outcome, and intra-operative guidance of surgeons.
This thesis is composed of two main parts. The first concerns the strategies for establishment of the process models. The second focuses on the application of the surgical process modelling techniques on surgery improvement.....
This thesis is composed of two main parts. The first concerns the strategies for establishment of the process models. The second focuses on the application of the surgical process modelling techniques on surgery improvement.....
Sustainable device selection for flexible intubation scopes
Comparative environmental impact assessment of disposable and reusable flexible intubation scopes and concept design for sustainable flexible intubation scopes
Master thesis
(2022)
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J.M. Duijndam, A.J. Loeve, A.C. van der Eijk, J.C. Diehl, J. Dankelman, L.F.C.M. van Oers
Medical device selection is currently based on criteria including clinical performance, usability, safety and procurement costs. Growing awareness of the negative contribution of the healthcare sector to the total greenhouse gas (GHG) emissions demands environmental sustainability to be taken into account as well. Reusable and disposable flexible intubation scopes are of current interest to anesthesiologists because disposables are often utilized due to their presumed superior sterility, cheaper purchasing price and convenience. Knowledge about the life cycle environmental impact of flexible intubation scopes is limited, so research is required to aid in sustainable device selection. Therefore, the goal of this study is to compare the environmental impact of disposable and reusable flexible intubation scopes and design a sustainable concept to enable data-driven selection of sustainable flexible intubation scopes. A cradle-to-grave comparative life cycle assessment (LCA) was made to quantify the environmental impact of reusable fiberoptic bronchoscopes (FOB) and disposable flexible video endoscopes (FVS) at 450 patient intubations. The largest contributors to the life cycle impact of the flexible intubation scopes were identified and used to generate a sustainable concept. The LCA results suggest that the reusable FOB has a lower life cycle impact in comparison to the disposable FVS, so selecting a reusable FOB is preferable from environmental perspective. Most life cycle emissions of the disposable FVS are caused by the material production of the device and manufacturing of the printed circuit board, while the disinfection process contributes most to the life cycle of the reusable FOB. The final concept of the sustainable flexible intubation scope contains plastic optical fibers and a thicker sleeve around the bending section of the insertion tube to make the device more durable and thus extend its lifetime. In order to minimize the environmental impact of flexible intubation scopes, it is recommended to develop flexible intubation scopes with plastic optical fibers, select low-impact materials for the device and revise the products’ life cycle at the product system level (e.g. disinfection process). Every small contribution towards a more sustainable healthcare system counts.
...
Medical device selection is currently based on criteria including clinical performance, usability, safety and procurement costs. Growing awareness of the negative contribution of the healthcare sector to the total greenhouse gas (GHG) emissions demands environmental sustainability to be taken into account as well. Reusable and disposable flexible intubation scopes are of current interest to anesthesiologists because disposables are often utilized due to their presumed superior sterility, cheaper purchasing price and convenience. Knowledge about the life cycle environmental impact of flexible intubation scopes is limited, so research is required to aid in sustainable device selection. Therefore, the goal of this study is to compare the environmental impact of disposable and reusable flexible intubation scopes and design a sustainable concept to enable data-driven selection of sustainable flexible intubation scopes. A cradle-to-grave comparative life cycle assessment (LCA) was made to quantify the environmental impact of reusable fiberoptic bronchoscopes (FOB) and disposable flexible video endoscopes (FVS) at 450 patient intubations. The largest contributors to the life cycle impact of the flexible intubation scopes were identified and used to generate a sustainable concept. The LCA results suggest that the reusable FOB has a lower life cycle impact in comparison to the disposable FVS, so selecting a reusable FOB is preferable from environmental perspective. Most life cycle emissions of the disposable FVS are caused by the material production of the device and manufacturing of the printed circuit board, while the disinfection process contributes most to the life cycle of the reusable FOB. The final concept of the sustainable flexible intubation scope contains plastic optical fibers and a thicker sleeve around the bending section of the insertion tube to make the device more durable and thus extend its lifetime. In order to minimize the environmental impact of flexible intubation scopes, it is recommended to develop flexible intubation scopes with plastic optical fibers, select low-impact materials for the device and revise the products’ life cycle at the product system level (e.g. disinfection process). Every small contribution towards a more sustainable healthcare system counts.
Falls are a significant cause of injury-associated deaths. In cases where the events leading up to a fall are unclear, a forensic investigation may be required to uncover the cause. During the forensic reconstruction process, tools for objective scenario evaluation are needed. Computer simulations appear to be a promising tool for reconstructing falls, being cheaper in terms of both money and time than the alternative of physical scenario reconstruction. Although software packages intended for modelling the kinetics and kinematics of the human body exist, none were found that were validated specifically for fall reconstruction. The aim of the current study was to validate the performance of human body modelling software Madymo, intended for use in car-crash simulations, in reconstructing human falling movements. This was achieved by first performing experiments in which the kinematics and kinetics of participants were recorded during falls from a short height. Next, the initial conditions taken from the experimentally recorded falls were used as input to run corresponding simulations using Madymo. Finally, the results from the simulated falls were compared to those from the real falls, based on the posture just before landing. The results indicate that Madymo is currently not yet suited for use in reconstructing real human falls across multiple types of falls, and is therefore not yet fit for application in forensic investigations into falls.
...
Falls are a significant cause of injury-associated deaths. In cases where the events leading up to a fall are unclear, a forensic investigation may be required to uncover the cause. During the forensic reconstruction process, tools for objective scenario evaluation are needed. Computer simulations appear to be a promising tool for reconstructing falls, being cheaper in terms of both money and time than the alternative of physical scenario reconstruction. Although software packages intended for modelling the kinetics and kinematics of the human body exist, none were found that were validated specifically for fall reconstruction. The aim of the current study was to validate the performance of human body modelling software Madymo, intended for use in car-crash simulations, in reconstructing human falling movements. This was achieved by first performing experiments in which the kinematics and kinetics of participants were recorded during falls from a short height. Next, the initial conditions taken from the experimentally recorded falls were used as input to run corresponding simulations using Madymo. Finally, the results from the simulated falls were compared to those from the real falls, based on the posture just before landing. The results indicate that Madymo is currently not yet suited for use in reconstructing real human falls across multiple types of falls, and is therefore not yet fit for application in forensic investigations into falls.
Each year, many people die due to non-natural causes of death, such as accidents, suicide, and murder and manslaughter. In these cases it is often necessary to investigate the cause, manner and time of death, which are investigated by forensic pathologists and the Police. To determine the time of death, the post mortem interval (PMI), the time passed shortly after death, should then be determined.
Wilk et al. (2020) developed a new method to determine the early PMI (3 – 72 hours). An input parameter in this method is the Thermal Conductivity Coefficient (k-value) of the textile layers surrounding the deceased. A method to determine the k-value of textile layers at, or around, a crime scene is needed. Therefore, this study aimed to design and develop a Thermal Conductivity (TC) measurement device for textile layers at a crime scene.
A functional decomposition chart of the device and a morphologic overview were created to design a suitable concept which was used for further development of the final prototype. SolidWorks was used to perform heat transfer simulations that were required to make the right design decisions and subsequently a final design and prototype were developed. Tests were performed to assess the performance of the prototype in terms of device configuration, accuracy, precision and measurement time. Furthermore, the effects of moisture content of the sample and sample compression during measurement on the calculated k-value were investigated.
A Guarded Hot Plate (GHP) based prototype was developed: Therminus-K2. This prototype was equipped with a back heater and four guard heaters to ensure one dimensional heat flow from the main heater through the sample towards the cold plate to eliminate other heat flows. Therminus-K2 obtains a precision of < 5% in TC measurements within 30 minutes. A steady-state measurement is achieved within a maximum of 7 minutes. Increasing the moisture content (2 states: dried and wetted) in the sample resulted in an increase in determined k-value (205 – 415 %). However, the uncertainty in sample thickness measurement was high (up to 16.7%) and complicated measurement of the sample compression effect on k-values.
Therminus-K2 delivers precise and fast TC measurements of textile samples: impressive results considering the simple components that were used. The future development of Therminus-K2 should focus on improving sample thickness measurement and improve user friendliness in order to make the device suitable to use in PMI estimation at actual crime scenes.
...
Wilk et al. (2020) developed a new method to determine the early PMI (3 – 72 hours). An input parameter in this method is the Thermal Conductivity Coefficient (k-value) of the textile layers surrounding the deceased. A method to determine the k-value of textile layers at, or around, a crime scene is needed. Therefore, this study aimed to design and develop a Thermal Conductivity (TC) measurement device for textile layers at a crime scene.
A functional decomposition chart of the device and a morphologic overview were created to design a suitable concept which was used for further development of the final prototype. SolidWorks was used to perform heat transfer simulations that were required to make the right design decisions and subsequently a final design and prototype were developed. Tests were performed to assess the performance of the prototype in terms of device configuration, accuracy, precision and measurement time. Furthermore, the effects of moisture content of the sample and sample compression during measurement on the calculated k-value were investigated.
A Guarded Hot Plate (GHP) based prototype was developed: Therminus-K2. This prototype was equipped with a back heater and four guard heaters to ensure one dimensional heat flow from the main heater through the sample towards the cold plate to eliminate other heat flows. Therminus-K2 obtains a precision of < 5% in TC measurements within 30 minutes. A steady-state measurement is achieved within a maximum of 7 minutes. Increasing the moisture content (2 states: dried and wetted) in the sample resulted in an increase in determined k-value (205 – 415 %). However, the uncertainty in sample thickness measurement was high (up to 16.7%) and complicated measurement of the sample compression effect on k-values.
Therminus-K2 delivers precise and fast TC measurements of textile samples: impressive results considering the simple components that were used. The future development of Therminus-K2 should focus on improving sample thickness measurement and improve user friendliness in order to make the device suitable to use in PMI estimation at actual crime scenes.
...
Each year, many people die due to non-natural causes of death, such as accidents, suicide, and murder and manslaughter. In these cases it is often necessary to investigate the cause, manner and time of death, which are investigated by forensic pathologists and the Police. To determine the time of death, the post mortem interval (PMI), the time passed shortly after death, should then be determined.
Wilk et al. (2020) developed a new method to determine the early PMI (3 – 72 hours). An input parameter in this method is the Thermal Conductivity Coefficient (k-value) of the textile layers surrounding the deceased. A method to determine the k-value of textile layers at, or around, a crime scene is needed. Therefore, this study aimed to design and develop a Thermal Conductivity (TC) measurement device for textile layers at a crime scene.
A functional decomposition chart of the device and a morphologic overview were created to design a suitable concept which was used for further development of the final prototype. SolidWorks was used to perform heat transfer simulations that were required to make the right design decisions and subsequently a final design and prototype were developed. Tests were performed to assess the performance of the prototype in terms of device configuration, accuracy, precision and measurement time. Furthermore, the effects of moisture content of the sample and sample compression during measurement on the calculated k-value were investigated.
A Guarded Hot Plate (GHP) based prototype was developed: Therminus-K2. This prototype was equipped with a back heater and four guard heaters to ensure one dimensional heat flow from the main heater through the sample towards the cold plate to eliminate other heat flows. Therminus-K2 obtains a precision of < 5% in TC measurements within 30 minutes. A steady-state measurement is achieved within a maximum of 7 minutes. Increasing the moisture content (2 states: dried and wetted) in the sample resulted in an increase in determined k-value (205 – 415 %). However, the uncertainty in sample thickness measurement was high (up to 16.7%) and complicated measurement of the sample compression effect on k-values.
Therminus-K2 delivers precise and fast TC measurements of textile samples: impressive results considering the simple components that were used. The future development of Therminus-K2 should focus on improving sample thickness measurement and improve user friendliness in order to make the device suitable to use in PMI estimation at actual crime scenes.
Wilk et al. (2020) developed a new method to determine the early PMI (3 – 72 hours). An input parameter in this method is the Thermal Conductivity Coefficient (k-value) of the textile layers surrounding the deceased. A method to determine the k-value of textile layers at, or around, a crime scene is needed. Therefore, this study aimed to design and develop a Thermal Conductivity (TC) measurement device for textile layers at a crime scene.
A functional decomposition chart of the device and a morphologic overview were created to design a suitable concept which was used for further development of the final prototype. SolidWorks was used to perform heat transfer simulations that were required to make the right design decisions and subsequently a final design and prototype were developed. Tests were performed to assess the performance of the prototype in terms of device configuration, accuracy, precision and measurement time. Furthermore, the effects of moisture content of the sample and sample compression during measurement on the calculated k-value were investigated.
A Guarded Hot Plate (GHP) based prototype was developed: Therminus-K2. This prototype was equipped with a back heater and four guard heaters to ensure one dimensional heat flow from the main heater through the sample towards the cold plate to eliminate other heat flows. Therminus-K2 obtains a precision of < 5% in TC measurements within 30 minutes. A steady-state measurement is achieved within a maximum of 7 minutes. Increasing the moisture content (2 states: dried and wetted) in the sample resulted in an increase in determined k-value (205 – 415 %). However, the uncertainty in sample thickness measurement was high (up to 16.7%) and complicated measurement of the sample compression effect on k-values.
Therminus-K2 delivers precise and fast TC measurements of textile samples: impressive results considering the simple components that were used. The future development of Therminus-K2 should focus on improving sample thickness measurement and improve user friendliness in order to make the device suitable to use in PMI estimation at actual crime scenes.
Electromagnetic navigation in mandible reconstruction surgery
Introduction and assessment of a noninvasive method for patient registration
Master thesis
(2022)
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A.F. de Geer, A.J. Loeve, M.B. Karakullukcu, M.J.A. van Alphen, R.P.J. van Veen, F.W. Jansen, L. van Erven
In patients with oral cavity cancer invading the mandible, a segmental bone resection is performed and the original contour of the mandible is reconstructed with a free fibula flap. Virtual surgical planning is performed prior to surgery to determine the locations and orientations of the osteotomy planes on the mandible and fibula. Currently, patient-specific cutting guides are designed and three-dimensional printed to translate the virtual surgical plan to the patient in the operating room. However, these cutting guides are not ideal; they lack adaptability when the intraoperative situation is different than expected, e.g. due to tumor progression. Alternatively, surgical navigation could be used to translate the virtual surgical plan to the patient. To enable surgical navigation, accurate alignment of the preoperative imaging data, including the virtual surgical plan, and the patient is required, i.e. image-to-patient registration. In this thesis, a simple, accurate, and noninvasive registration method for electromagnetic navigation of the mandible is introduced and assessed.
Chapter 1 gives an introduction to the clinical background of mandible reconstruction surgery and the technical background of surgical navigation. The clinical problem, a potential solution and the thesis objectives are also discussed.
The systematic review in Chapter 2 gives an overview of currently used registration methods in navigated mandibular surgery: point registration, surface registration, hybrid registration, and computer vision based registration. The main conclusion of the review was that there is always a tradeoff between the usability, registration time, accuracy, and invasiveness of a registration method.
Chapter 3 introduces a simple and noninvasive registration method for mandible navigation: hybrid registration. This method consists of two steps: 1) point registration; performed for initialization using three anatomic landmarks on the mandible, and 2) surface registration; performed for optimization using the surgically exposed mandibular bone surface after removal of soft tissue.
In previous research in the NKI-AvL, an applicator was used to fixate an electromagnetic sensor to the mandible to track its movements during navigated surgery. The design of this applicator, however, enabled movement of the sensor in the applicator, which resulted in inaccurate navigation. Therefore, in Chapter 4, a renewed design for the sensor applicator is proposed.
In Chapter 5, the optimal approach for hybrid registration of the mandible is determined in phantom experiments. Different registration configurations, i.e. different surface point areas and number and configuration of surface points, were evaluated as well as registration with different patient anatomies. In all experiments, the target registration error (TRE) was below 2.0 mm, which meets the practical clinical requirements for mandible reconstruction surgery. The results suggest that only a small surface area of the mandible, marked by limited surface points, is required to obtain accurate registration.
Chapter 6 describes the preliminary results of hybrid registration of the mandible in four patients during surgery. Registration could be performed within on average 4.5 minutes. Mean TRE values of 3.4 mm for anatomic landmarks and 2.3 mm for cutting guide landmarks were obtained, indicating that the registration procedure should be further optimized to achieve clinically acceptable registration accuracy.
Chapter 7 provides an overall conclusion and future perspectives. Although the preliminary results of the patient study for mandible navigation are promising, the registration method should be further optimized and evaluated in more patients before implementation into clinical practice is possible. Ultimately, we want to use electromagnetic navigation to position a universal cutting guide during mandible reconstruction surgery. Multiple challenges still lie ahead before this can become reality in the NKI-AvL.
...
Chapter 1 gives an introduction to the clinical background of mandible reconstruction surgery and the technical background of surgical navigation. The clinical problem, a potential solution and the thesis objectives are also discussed.
The systematic review in Chapter 2 gives an overview of currently used registration methods in navigated mandibular surgery: point registration, surface registration, hybrid registration, and computer vision based registration. The main conclusion of the review was that there is always a tradeoff between the usability, registration time, accuracy, and invasiveness of a registration method.
Chapter 3 introduces a simple and noninvasive registration method for mandible navigation: hybrid registration. This method consists of two steps: 1) point registration; performed for initialization using three anatomic landmarks on the mandible, and 2) surface registration; performed for optimization using the surgically exposed mandibular bone surface after removal of soft tissue.
In previous research in the NKI-AvL, an applicator was used to fixate an electromagnetic sensor to the mandible to track its movements during navigated surgery. The design of this applicator, however, enabled movement of the sensor in the applicator, which resulted in inaccurate navigation. Therefore, in Chapter 4, a renewed design for the sensor applicator is proposed.
In Chapter 5, the optimal approach for hybrid registration of the mandible is determined in phantom experiments. Different registration configurations, i.e. different surface point areas and number and configuration of surface points, were evaluated as well as registration with different patient anatomies. In all experiments, the target registration error (TRE) was below 2.0 mm, which meets the practical clinical requirements for mandible reconstruction surgery. The results suggest that only a small surface area of the mandible, marked by limited surface points, is required to obtain accurate registration.
Chapter 6 describes the preliminary results of hybrid registration of the mandible in four patients during surgery. Registration could be performed within on average 4.5 minutes. Mean TRE values of 3.4 mm for anatomic landmarks and 2.3 mm for cutting guide landmarks were obtained, indicating that the registration procedure should be further optimized to achieve clinically acceptable registration accuracy.
Chapter 7 provides an overall conclusion and future perspectives. Although the preliminary results of the patient study for mandible navigation are promising, the registration method should be further optimized and evaluated in more patients before implementation into clinical practice is possible. Ultimately, we want to use electromagnetic navigation to position a universal cutting guide during mandible reconstruction surgery. Multiple challenges still lie ahead before this can become reality in the NKI-AvL.
...
In patients with oral cavity cancer invading the mandible, a segmental bone resection is performed and the original contour of the mandible is reconstructed with a free fibula flap. Virtual surgical planning is performed prior to surgery to determine the locations and orientations of the osteotomy planes on the mandible and fibula. Currently, patient-specific cutting guides are designed and three-dimensional printed to translate the virtual surgical plan to the patient in the operating room. However, these cutting guides are not ideal; they lack adaptability when the intraoperative situation is different than expected, e.g. due to tumor progression. Alternatively, surgical navigation could be used to translate the virtual surgical plan to the patient. To enable surgical navigation, accurate alignment of the preoperative imaging data, including the virtual surgical plan, and the patient is required, i.e. image-to-patient registration. In this thesis, a simple, accurate, and noninvasive registration method for electromagnetic navigation of the mandible is introduced and assessed.
Chapter 1 gives an introduction to the clinical background of mandible reconstruction surgery and the technical background of surgical navigation. The clinical problem, a potential solution and the thesis objectives are also discussed.
The systematic review in Chapter 2 gives an overview of currently used registration methods in navigated mandibular surgery: point registration, surface registration, hybrid registration, and computer vision based registration. The main conclusion of the review was that there is always a tradeoff between the usability, registration time, accuracy, and invasiveness of a registration method.
Chapter 3 introduces a simple and noninvasive registration method for mandible navigation: hybrid registration. This method consists of two steps: 1) point registration; performed for initialization using three anatomic landmarks on the mandible, and 2) surface registration; performed for optimization using the surgically exposed mandibular bone surface after removal of soft tissue.
In previous research in the NKI-AvL, an applicator was used to fixate an electromagnetic sensor to the mandible to track its movements during navigated surgery. The design of this applicator, however, enabled movement of the sensor in the applicator, which resulted in inaccurate navigation. Therefore, in Chapter 4, a renewed design for the sensor applicator is proposed.
In Chapter 5, the optimal approach for hybrid registration of the mandible is determined in phantom experiments. Different registration configurations, i.e. different surface point areas and number and configuration of surface points, were evaluated as well as registration with different patient anatomies. In all experiments, the target registration error (TRE) was below 2.0 mm, which meets the practical clinical requirements for mandible reconstruction surgery. The results suggest that only a small surface area of the mandible, marked by limited surface points, is required to obtain accurate registration.
Chapter 6 describes the preliminary results of hybrid registration of the mandible in four patients during surgery. Registration could be performed within on average 4.5 minutes. Mean TRE values of 3.4 mm for anatomic landmarks and 2.3 mm for cutting guide landmarks were obtained, indicating that the registration procedure should be further optimized to achieve clinically acceptable registration accuracy.
Chapter 7 provides an overall conclusion and future perspectives. Although the preliminary results of the patient study for mandible navigation are promising, the registration method should be further optimized and evaluated in more patients before implementation into clinical practice is possible. Ultimately, we want to use electromagnetic navigation to position a universal cutting guide during mandible reconstruction surgery. Multiple challenges still lie ahead before this can become reality in the NKI-AvL.
Chapter 1 gives an introduction to the clinical background of mandible reconstruction surgery and the technical background of surgical navigation. The clinical problem, a potential solution and the thesis objectives are also discussed.
The systematic review in Chapter 2 gives an overview of currently used registration methods in navigated mandibular surgery: point registration, surface registration, hybrid registration, and computer vision based registration. The main conclusion of the review was that there is always a tradeoff between the usability, registration time, accuracy, and invasiveness of a registration method.
Chapter 3 introduces a simple and noninvasive registration method for mandible navigation: hybrid registration. This method consists of two steps: 1) point registration; performed for initialization using three anatomic landmarks on the mandible, and 2) surface registration; performed for optimization using the surgically exposed mandibular bone surface after removal of soft tissue.
In previous research in the NKI-AvL, an applicator was used to fixate an electromagnetic sensor to the mandible to track its movements during navigated surgery. The design of this applicator, however, enabled movement of the sensor in the applicator, which resulted in inaccurate navigation. Therefore, in Chapter 4, a renewed design for the sensor applicator is proposed.
In Chapter 5, the optimal approach for hybrid registration of the mandible is determined in phantom experiments. Different registration configurations, i.e. different surface point areas and number and configuration of surface points, were evaluated as well as registration with different patient anatomies. In all experiments, the target registration error (TRE) was below 2.0 mm, which meets the practical clinical requirements for mandible reconstruction surgery. The results suggest that only a small surface area of the mandible, marked by limited surface points, is required to obtain accurate registration.
Chapter 6 describes the preliminary results of hybrid registration of the mandible in four patients during surgery. Registration could be performed within on average 4.5 minutes. Mean TRE values of 3.4 mm for anatomic landmarks and 2.3 mm for cutting guide landmarks were obtained, indicating that the registration procedure should be further optimized to achieve clinically acceptable registration accuracy.
Chapter 7 provides an overall conclusion and future perspectives. Although the preliminary results of the patient study for mandible navigation are promising, the registration method should be further optimized and evaluated in more patients before implementation into clinical practice is possible. Ultimately, we want to use electromagnetic navigation to position a universal cutting guide during mandible reconstruction surgery. Multiple challenges still lie ahead before this can become reality in the NKI-AvL.
DropAdjust: infusion flow regulator
Design and development of a precise and accurate manually controlled over-line flow regulator for gravity-driven infusion
Worldwide 70-90% of hospitalised patients receive intravenous infusion at some stage during their stay. In many situations, a high degree of infusion accuracy is essential as deviation from the intended dose can quickly become dangerous and moreover costly. Electronic infusion pumps provide the most accurate way of infusion, but they require programming and frequent maintenance. Furthermore, they are unsuitable for austere environments, costly, and could even become scarce in times of a pandemic. Gravity infusion combined with a drop counter could pose an interesting alternative. However, this method appears to be inaccurate over time and setting an accurate flow rate is challenging. The typically used flow regulator, a roller clamp, is the cause of these complications. This study aimed to design and develop a precise and accurate manually controlled over-line flow regulator for gravity-driven infusion. The design process consisted out of three design phases: analysis, synthesis and evaluation. During the analysis, the design requirements were set up. The synthesis phase consisted of generating a morphological overview and several pincher experiments. A pincher is used to clamp the tubing to regulate the flow rate. Then, promising partial solutions were selected, and through rapid prototyping, a final design and prototype were developed. In the evaluation phase, the flow regulator prototype was evaluated based on the set requirements. The developed DropAdjust prototype demonstrated a major performance increase in terms of mean flow rate accuracy and regulation control compared to the roller clamp. In conclusion, the DropAdjust satisfies all tested design criteria and outperformed the roller clamp in terms of accuracy and precision. Moreover, it even showed a mean flow rate accuracy error comparable to the infusion pumps. Thus, the DropAdjust combined with a drop counter provides a more affordable and accessible alternative to the infusion pumps. The prototype is already practice-ready, but several steps are still needed to realise a market-ready device. For instance, conducting endurance tests and acquiring injection moulding advice from an experienced specialist are advised. Also, additional tests are necessary to verify its safety and functionality to qualify for a CE marking.
...
Worldwide 70-90% of hospitalised patients receive intravenous infusion at some stage during their stay. In many situations, a high degree of infusion accuracy is essential as deviation from the intended dose can quickly become dangerous and moreover costly. Electronic infusion pumps provide the most accurate way of infusion, but they require programming and frequent maintenance. Furthermore, they are unsuitable for austere environments, costly, and could even become scarce in times of a pandemic. Gravity infusion combined with a drop counter could pose an interesting alternative. However, this method appears to be inaccurate over time and setting an accurate flow rate is challenging. The typically used flow regulator, a roller clamp, is the cause of these complications. This study aimed to design and develop a precise and accurate manually controlled over-line flow regulator for gravity-driven infusion. The design process consisted out of three design phases: analysis, synthesis and evaluation. During the analysis, the design requirements were set up. The synthesis phase consisted of generating a morphological overview and several pincher experiments. A pincher is used to clamp the tubing to regulate the flow rate. Then, promising partial solutions were selected, and through rapid prototyping, a final design and prototype were developed. In the evaluation phase, the flow regulator prototype was evaluated based on the set requirements. The developed DropAdjust prototype demonstrated a major performance increase in terms of mean flow rate accuracy and regulation control compared to the roller clamp. In conclusion, the DropAdjust satisfies all tested design criteria and outperformed the roller clamp in terms of accuracy and precision. Moreover, it even showed a mean flow rate accuracy error comparable to the infusion pumps. Thus, the DropAdjust combined with a drop counter provides a more affordable and accessible alternative to the infusion pumps. The prototype is already practice-ready, but several steps are still needed to realise a market-ready device. For instance, conducting endurance tests and acquiring injection moulding advice from an experienced specialist are advised. Also, additional tests are necessary to verify its safety and functionality to qualify for a CE marking.
Conceptual design of an anthropomorphic shake doll
Development of requirements for an anthropomorphic shake doll and design of an artificial joint for investigating the infant’s body kinematics during shaking
Infant shaking can cause serious damage (inflicted head injury by shaking trauma), it’s occurrence indicates the necessity for infant protection. To ensure reliable jurisprudence, it is important to know the exact consequences of shaking on an infant’s body. These consequences can be researched by the use of an anthropomorphic shake doll. With this doll, shake experiments can be performed in order to better understand the kinematics of the body and body parts during shaking. This study aims to establish design criteria for this doll as well as designing, producing and testing the joints for this model. A requirement list is presented, as well as a design for a joint that can be used for the limbs of the doll. To ensure structural integrity of this design, a representation of the joint was created and an indicative mechanical shake test was performed. Building further on this, real life prototypes have been made.
...
Infant shaking can cause serious damage (inflicted head injury by shaking trauma), it’s occurrence indicates the necessity for infant protection. To ensure reliable jurisprudence, it is important to know the exact consequences of shaking on an infant’s body. These consequences can be researched by the use of an anthropomorphic shake doll. With this doll, shake experiments can be performed in order to better understand the kinematics of the body and body parts during shaking. This study aims to establish design criteria for this doll as well as designing, producing and testing the joints for this model. A requirement list is presented, as well as a design for a joint that can be used for the limbs of the doll. To ensure structural integrity of this design, a representation of the joint was created and an indicative mechanical shake test was performed. Building further on this, real life prototypes have been made.
The forensic investigation is one of the first steps in the criminal investigation process concerning home invasion robberies. The forensic investigation consists of objectively capturing the crime scene as it is when starting the investigation. Regarding home invasion robberies, the most important traces are fingerprints and DNA which are used for identification of individual suspects. Currently, there is little knowledge about the process of a secured trace to a result used in court.
Crime scene investigators are confronted with multiple decisions during the investigation and it is important to know with what goal in mind an investigator acts on the crime scene, as this influences the decision-making. The forensic data obtained from the forensic investigation is shared within a forensic data infrastructure. This infrastructure consists of the following criminal justice system partners involved in the process from crime scene investigation to conviction: crime scene investigators, detectives, experts at forensic laboratories, prosecutors, defense attorneys and judges. These partners are all contributing in different ways and at different times.
The forensic data infrastructure comes with sensibilities and tensions, such as tunnel vision, incomplete crime scene investigation reports, misunderstandings and one-way communication. Solving these sensibilities and tensions is crucial to the functioning of the infrastructure.
By use of a questionnaire, insights are provided into the goals and aspects of the forensic investigation that are important to the involved partners. The goals important to crime scene investigators differ little from the goals of other involved partners. The questionnaire results are reflected on in an expert reflection session. This session is part of the participatory design, which contributes in creating a mutual understanding of needs between partners. A second expert session is developed to fulfill these needs and implement solutions to solve sensibilities and tensions in an optimized forensic investigation.
The optimization process includes the optimization of the forensic investigation itself and the optimization of the forensic data infrastructure by proposing a structured forensic investigation scheme. A new experiment is presented to analyze the optimized forensic investigation. ...
Crime scene investigators are confronted with multiple decisions during the investigation and it is important to know with what goal in mind an investigator acts on the crime scene, as this influences the decision-making. The forensic data obtained from the forensic investigation is shared within a forensic data infrastructure. This infrastructure consists of the following criminal justice system partners involved in the process from crime scene investigation to conviction: crime scene investigators, detectives, experts at forensic laboratories, prosecutors, defense attorneys and judges. These partners are all contributing in different ways and at different times.
The forensic data infrastructure comes with sensibilities and tensions, such as tunnel vision, incomplete crime scene investigation reports, misunderstandings and one-way communication. Solving these sensibilities and tensions is crucial to the functioning of the infrastructure.
By use of a questionnaire, insights are provided into the goals and aspects of the forensic investigation that are important to the involved partners. The goals important to crime scene investigators differ little from the goals of other involved partners. The questionnaire results are reflected on in an expert reflection session. This session is part of the participatory design, which contributes in creating a mutual understanding of needs between partners. A second expert session is developed to fulfill these needs and implement solutions to solve sensibilities and tensions in an optimized forensic investigation.
The optimization process includes the optimization of the forensic investigation itself and the optimization of the forensic data infrastructure by proposing a structured forensic investigation scheme. A new experiment is presented to analyze the optimized forensic investigation. ...
The forensic investigation is one of the first steps in the criminal investigation process concerning home invasion robberies. The forensic investigation consists of objectively capturing the crime scene as it is when starting the investigation. Regarding home invasion robberies, the most important traces are fingerprints and DNA which are used for identification of individual suspects. Currently, there is little knowledge about the process of a secured trace to a result used in court.
Crime scene investigators are confronted with multiple decisions during the investigation and it is important to know with what goal in mind an investigator acts on the crime scene, as this influences the decision-making. The forensic data obtained from the forensic investigation is shared within a forensic data infrastructure. This infrastructure consists of the following criminal justice system partners involved in the process from crime scene investigation to conviction: crime scene investigators, detectives, experts at forensic laboratories, prosecutors, defense attorneys and judges. These partners are all contributing in different ways and at different times.
The forensic data infrastructure comes with sensibilities and tensions, such as tunnel vision, incomplete crime scene investigation reports, misunderstandings and one-way communication. Solving these sensibilities and tensions is crucial to the functioning of the infrastructure.
By use of a questionnaire, insights are provided into the goals and aspects of the forensic investigation that are important to the involved partners. The goals important to crime scene investigators differ little from the goals of other involved partners. The questionnaire results are reflected on in an expert reflection session. This session is part of the participatory design, which contributes in creating a mutual understanding of needs between partners. A second expert session is developed to fulfill these needs and implement solutions to solve sensibilities and tensions in an optimized forensic investigation.
The optimization process includes the optimization of the forensic investigation itself and the optimization of the forensic data infrastructure by proposing a structured forensic investigation scheme. A new experiment is presented to analyze the optimized forensic investigation.
Crime scene investigators are confronted with multiple decisions during the investigation and it is important to know with what goal in mind an investigator acts on the crime scene, as this influences the decision-making. The forensic data obtained from the forensic investigation is shared within a forensic data infrastructure. This infrastructure consists of the following criminal justice system partners involved in the process from crime scene investigation to conviction: crime scene investigators, detectives, experts at forensic laboratories, prosecutors, defense attorneys and judges. These partners are all contributing in different ways and at different times.
The forensic data infrastructure comes with sensibilities and tensions, such as tunnel vision, incomplete crime scene investigation reports, misunderstandings and one-way communication. Solving these sensibilities and tensions is crucial to the functioning of the infrastructure.
By use of a questionnaire, insights are provided into the goals and aspects of the forensic investigation that are important to the involved partners. The goals important to crime scene investigators differ little from the goals of other involved partners. The questionnaire results are reflected on in an expert reflection session. This session is part of the participatory design, which contributes in creating a mutual understanding of needs between partners. A second expert session is developed to fulfill these needs and implement solutions to solve sensibilities and tensions in an optimized forensic investigation.
The optimization process includes the optimization of the forensic investigation itself and the optimization of the forensic data infrastructure by proposing a structured forensic investigation scheme. A new experiment is presented to analyze the optimized forensic investigation.
Inflicted Head Injury by Shaking Trauma in Infants
Part I: The potential effect of spatiotemporal variation of the rotation center on injury mechanisms. Part II:The importance of spatiotemporal variation of the rotation center when modeling external head-dynamics
Part I:
Inflicted head injury by shaking trauma (IHI-ST) is often simulated to better understand the injury mechanisms and to analyze whether violent shaking can cause head injury in infants. Computational models are usually subjected to linear and rotational inputs to simulate shaking scenarios. In existing studies, the head’s rotation center is kept fixed over time during shaking. However, the infant’s head is unlikely to rotate around a fixed pivoting point in real life due to the flexibility of the infant’s neck and the external imposed shaking motion by the perpetrator. It is currently unknown how the location of the rotation center changes over time and how this manifests itself in the expression of the injury mechanisms associated with IHI-ST.
In this study, the variation of the rotation center of an infant’s head during shaking and its potential effect on injury mechanisms were analyzed. First, dynamics of the infant’s head were obtained in shaking experiments with an infant surrogate. Next, the variation of the rotation center was calculated and relations between characteristics of the participants and shaking variables were analyzed.
Key findings: during shaking the location of the head’s rotation center varied in both anterior-posterior and vertical direction with respect to the head, causing the head’s radius of curvature to vary six orders of magnitude. Therefore, head-dynamics and injury mechanisms underlying IHI-ST are possibly simulated incorrectly when using a fixed rotation center. It remains unclear how this affects the validity of IHI-ST injury risk assessments and the injury thresholds on which these assessments are based. Future research should therefore evaluate the performance of head-dynamic simulations regarding IHI-ST.
Part II:
Computational model simulations are extensively used to analyze inflicted head injury by shaking trauma in infants (IHI-ST). Infant head models are usually excited by dynamic inputs, which are applied to a specific point with respect to the head. In existing studies the load application point is assumed to be fixed over time; thereby neglecting spatiotemporal variation of the rotation center during shaking. Therefore, this assumption may be inappropriate, because the location of the heads’ rotation center is in fact not constant over time during shaking. It is unknown to what extent head dynamics are correctly simulated when using a fixed rotation center, hence simulation results regarding injury thresholds and shaking trauma assessment could be invalid.
In this study, loading-methods used in IHI-ST simulations were evaluated for their temporal accuracy in replicating external head-dynamics. First, a mathematical model incorporating spatiotemporal variation of the head’s rotation center was proposed. Secondly, head dynamics were calculated using the proposed mathematical model and existing model-loading methods. Finally, the calculated head dynamics were compared to a reference dataset.
Key findings: in all of the 29 cases from the reference dataset, implementation of a time-varying load application point resulted in an improved temporal replication of shaking dynamics compared to existing model-loading methods. Accelerations of the head in x- and z-direction had a two and four times smaller absolute error over a typical shake cycle than any previously existing finite element model (FEM) for IHI-ST. It remains unclear how implementation of a time-varying load application point affects the dynamics of fluids and tissues inside the skull. Future research should therefore focus on re-evaluating the results of IHI-ST assessment studies and injury threshold studies employing FEM head-models.
...
Inflicted head injury by shaking trauma (IHI-ST) is often simulated to better understand the injury mechanisms and to analyze whether violent shaking can cause head injury in infants. Computational models are usually subjected to linear and rotational inputs to simulate shaking scenarios. In existing studies, the head’s rotation center is kept fixed over time during shaking. However, the infant’s head is unlikely to rotate around a fixed pivoting point in real life due to the flexibility of the infant’s neck and the external imposed shaking motion by the perpetrator. It is currently unknown how the location of the rotation center changes over time and how this manifests itself in the expression of the injury mechanisms associated with IHI-ST.
In this study, the variation of the rotation center of an infant’s head during shaking and its potential effect on injury mechanisms were analyzed. First, dynamics of the infant’s head were obtained in shaking experiments with an infant surrogate. Next, the variation of the rotation center was calculated and relations between characteristics of the participants and shaking variables were analyzed.
Key findings: during shaking the location of the head’s rotation center varied in both anterior-posterior and vertical direction with respect to the head, causing the head’s radius of curvature to vary six orders of magnitude. Therefore, head-dynamics and injury mechanisms underlying IHI-ST are possibly simulated incorrectly when using a fixed rotation center. It remains unclear how this affects the validity of IHI-ST injury risk assessments and the injury thresholds on which these assessments are based. Future research should therefore evaluate the performance of head-dynamic simulations regarding IHI-ST.
Part II:
Computational model simulations are extensively used to analyze inflicted head injury by shaking trauma in infants (IHI-ST). Infant head models are usually excited by dynamic inputs, which are applied to a specific point with respect to the head. In existing studies the load application point is assumed to be fixed over time; thereby neglecting spatiotemporal variation of the rotation center during shaking. Therefore, this assumption may be inappropriate, because the location of the heads’ rotation center is in fact not constant over time during shaking. It is unknown to what extent head dynamics are correctly simulated when using a fixed rotation center, hence simulation results regarding injury thresholds and shaking trauma assessment could be invalid.
In this study, loading-methods used in IHI-ST simulations were evaluated for their temporal accuracy in replicating external head-dynamics. First, a mathematical model incorporating spatiotemporal variation of the head’s rotation center was proposed. Secondly, head dynamics were calculated using the proposed mathematical model and existing model-loading methods. Finally, the calculated head dynamics were compared to a reference dataset.
Key findings: in all of the 29 cases from the reference dataset, implementation of a time-varying load application point resulted in an improved temporal replication of shaking dynamics compared to existing model-loading methods. Accelerations of the head in x- and z-direction had a two and four times smaller absolute error over a typical shake cycle than any previously existing finite element model (FEM) for IHI-ST. It remains unclear how implementation of a time-varying load application point affects the dynamics of fluids and tissues inside the skull. Future research should therefore focus on re-evaluating the results of IHI-ST assessment studies and injury threshold studies employing FEM head-models.
...
Part I:
Inflicted head injury by shaking trauma (IHI-ST) is often simulated to better understand the injury mechanisms and to analyze whether violent shaking can cause head injury in infants. Computational models are usually subjected to linear and rotational inputs to simulate shaking scenarios. In existing studies, the head’s rotation center is kept fixed over time during shaking. However, the infant’s head is unlikely to rotate around a fixed pivoting point in real life due to the flexibility of the infant’s neck and the external imposed shaking motion by the perpetrator. It is currently unknown how the location of the rotation center changes over time and how this manifests itself in the expression of the injury mechanisms associated with IHI-ST.
In this study, the variation of the rotation center of an infant’s head during shaking and its potential effect on injury mechanisms were analyzed. First, dynamics of the infant’s head were obtained in shaking experiments with an infant surrogate. Next, the variation of the rotation center was calculated and relations between characteristics of the participants and shaking variables were analyzed.
Key findings: during shaking the location of the head’s rotation center varied in both anterior-posterior and vertical direction with respect to the head, causing the head’s radius of curvature to vary six orders of magnitude. Therefore, head-dynamics and injury mechanisms underlying IHI-ST are possibly simulated incorrectly when using a fixed rotation center. It remains unclear how this affects the validity of IHI-ST injury risk assessments and the injury thresholds on which these assessments are based. Future research should therefore evaluate the performance of head-dynamic simulations regarding IHI-ST.
Part II:
Computational model simulations are extensively used to analyze inflicted head injury by shaking trauma in infants (IHI-ST). Infant head models are usually excited by dynamic inputs, which are applied to a specific point with respect to the head. In existing studies the load application point is assumed to be fixed over time; thereby neglecting spatiotemporal variation of the rotation center during shaking. Therefore, this assumption may be inappropriate, because the location of the heads’ rotation center is in fact not constant over time during shaking. It is unknown to what extent head dynamics are correctly simulated when using a fixed rotation center, hence simulation results regarding injury thresholds and shaking trauma assessment could be invalid.
In this study, loading-methods used in IHI-ST simulations were evaluated for their temporal accuracy in replicating external head-dynamics. First, a mathematical model incorporating spatiotemporal variation of the head’s rotation center was proposed. Secondly, head dynamics were calculated using the proposed mathematical model and existing model-loading methods. Finally, the calculated head dynamics were compared to a reference dataset.
Key findings: in all of the 29 cases from the reference dataset, implementation of a time-varying load application point resulted in an improved temporal replication of shaking dynamics compared to existing model-loading methods. Accelerations of the head in x- and z-direction had a two and four times smaller absolute error over a typical shake cycle than any previously existing finite element model (FEM) for IHI-ST. It remains unclear how implementation of a time-varying load application point affects the dynamics of fluids and tissues inside the skull. Future research should therefore focus on re-evaluating the results of IHI-ST assessment studies and injury threshold studies employing FEM head-models.
Inflicted head injury by shaking trauma (IHI-ST) is often simulated to better understand the injury mechanisms and to analyze whether violent shaking can cause head injury in infants. Computational models are usually subjected to linear and rotational inputs to simulate shaking scenarios. In existing studies, the head’s rotation center is kept fixed over time during shaking. However, the infant’s head is unlikely to rotate around a fixed pivoting point in real life due to the flexibility of the infant’s neck and the external imposed shaking motion by the perpetrator. It is currently unknown how the location of the rotation center changes over time and how this manifests itself in the expression of the injury mechanisms associated with IHI-ST.
In this study, the variation of the rotation center of an infant’s head during shaking and its potential effect on injury mechanisms were analyzed. First, dynamics of the infant’s head were obtained in shaking experiments with an infant surrogate. Next, the variation of the rotation center was calculated and relations between characteristics of the participants and shaking variables were analyzed.
Key findings: during shaking the location of the head’s rotation center varied in both anterior-posterior and vertical direction with respect to the head, causing the head’s radius of curvature to vary six orders of magnitude. Therefore, head-dynamics and injury mechanisms underlying IHI-ST are possibly simulated incorrectly when using a fixed rotation center. It remains unclear how this affects the validity of IHI-ST injury risk assessments and the injury thresholds on which these assessments are based. Future research should therefore evaluate the performance of head-dynamic simulations regarding IHI-ST.
Part II:
Computational model simulations are extensively used to analyze inflicted head injury by shaking trauma in infants (IHI-ST). Infant head models are usually excited by dynamic inputs, which are applied to a specific point with respect to the head. In existing studies the load application point is assumed to be fixed over time; thereby neglecting spatiotemporal variation of the rotation center during shaking. Therefore, this assumption may be inappropriate, because the location of the heads’ rotation center is in fact not constant over time during shaking. It is unknown to what extent head dynamics are correctly simulated when using a fixed rotation center, hence simulation results regarding injury thresholds and shaking trauma assessment could be invalid.
In this study, loading-methods used in IHI-ST simulations were evaluated for their temporal accuracy in replicating external head-dynamics. First, a mathematical model incorporating spatiotemporal variation of the head’s rotation center was proposed. Secondly, head dynamics were calculated using the proposed mathematical model and existing model-loading methods. Finally, the calculated head dynamics were compared to a reference dataset.
Key findings: in all of the 29 cases from the reference dataset, implementation of a time-varying load application point resulted in an improved temporal replication of shaking dynamics compared to existing model-loading methods. Accelerations of the head in x- and z-direction had a two and four times smaller absolute error over a typical shake cycle than any previously existing finite element model (FEM) for IHI-ST. It remains unclear how implementation of a time-varying load application point affects the dynamics of fluids and tissues inside the skull. Future research should therefore focus on re-evaluating the results of IHI-ST assessment studies and injury threshold studies employing FEM head-models.
A new photoplethysmography-based device called the Multiphotodiode Array (MPA) was validated to successfully measure the PWV in the vasculature of the distal phalanx of healthy subjects. It comprises an array of photodiodes and an array of opposing LEDs to detect blood volume changes due to the passing pressure pulse wave in the vasculature of the distal phalanx of the index finger. This study aimed to discern how the signal robustness of a novel modular sensor based on the technology of the MPA is dependent on the contact force between the vascularized tissue and the sensor surface. PWV data was collected as the distal phalanx of the left index finger from 26 subjects was placed on the Force Alterable- MPA (FA-MPA). Contact force was altered by placing differing weights (0-300g, 50g increments) on top of the phalanx using a linear stage. Contact force was determined as weight measured by a scale underneath the FA-MPA. PWV and weight data was collected from a total of 182 measurements. Measurements were pooled in 8 weight groups between 0 and 400g at increments of 50g according to the weight that was measured during that measurement. PWV data per weight group was analyzed for three characteristics: 1. Pulse Wave Quality Ratio (PWQR); 2. PWV variance; 3. Realistic and non-negative values for PWV. ANOVA of PWQR resulted in a significant effect between weight groups (p = 6.91E-7). Further qualitative judging of data resulted in the recommendation to thoroughly redesign the FA-MPA for structural and electrical integrity and measurement protocol for elimination of movement and placement artifacts and to reiterate the experiment for the contact force range of 1.96 to 4.43N.
...
A new photoplethysmography-based device called the Multiphotodiode Array (MPA) was validated to successfully measure the PWV in the vasculature of the distal phalanx of healthy subjects. It comprises an array of photodiodes and an array of opposing LEDs to detect blood volume changes due to the passing pressure pulse wave in the vasculature of the distal phalanx of the index finger. This study aimed to discern how the signal robustness of a novel modular sensor based on the technology of the MPA is dependent on the contact force between the vascularized tissue and the sensor surface. PWV data was collected as the distal phalanx of the left index finger from 26 subjects was placed on the Force Alterable- MPA (FA-MPA). Contact force was altered by placing differing weights (0-300g, 50g increments) on top of the phalanx using a linear stage. Contact force was determined as weight measured by a scale underneath the FA-MPA. PWV and weight data was collected from a total of 182 measurements. Measurements were pooled in 8 weight groups between 0 and 400g at increments of 50g according to the weight that was measured during that measurement. PWV data per weight group was analyzed for three characteristics: 1. Pulse Wave Quality Ratio (PWQR); 2. PWV variance; 3. Realistic and non-negative values for PWV. ANOVA of PWQR resulted in a significant effect between weight groups (p = 6.91E-7). Further qualitative judging of data resulted in the recommendation to thoroughly redesign the FA-MPA for structural and electrical integrity and measurement protocol for elimination of movement and placement artifacts and to reiterate the experiment for the contact force range of 1.96 to 4.43N.
Master thesis
(2019)
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Olaf Dessing, Arjo Loeve, Jenny Dankelman, Dick Plettenburg, Marcel van Beest
embargo
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embargo