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Multi-access networks may exhibit severe unfairness in throughput,in the sense that some nodes receive structurally higher throughputthan others. Recent studies show that this unfairness is due tolocal differences in the neighborhood structure: Nodes with fewerneighbors receive better access. We study the unfairness in satura-ted linear networks,and adapt the multi-access CSMA protocol toremove the unfairness completely,by choosing the activation ratesof nodes as a specific function of the number of neighbors. We theninvestigate the consequences of this choice of activation rates onthe network-average saturated throughput, and we show that theserates perform well in non-saturated settings.

The integration of therapeutic interventions with diagnostic imaginghas been recognized as one of the next technological developments that will have a major impact on medical treatments. Therapeutic applications using ultrasound, for example thermal ablation, hyperthermia or ultrasound induced drug delivery, are examples for image-guidedinterventions that are currently investigated. While thermal ablation using MR-HIFU is entering the clinic, ultrasound mediated drug delivery is still in a research phase, but holds promise to enable newapplications in localized treatments. The use of ultrasound for thedelivery of drugs has been demonstrated in particular the field ofcardiology and oncology for a variety of therapeutics ranging from small drug molecules to biologics and nucleic acids exploiting temperature or pressure mediated delivery schemes.

Recent developments in the spectrum policy and regulatory domains allow more flexible and efficient use of spectrum, notably the releaseof National Broadband Plan, the publication of final rules for TV white spaces, and the ongoing proceeding for secondary use of the 2360–2400 MHz band for Medical Body Area Networks (MBANS). These important changes open up great opportunities for cognitive radio (CR) toenable and support a variety of emerging applications, ranging fromsmart grid, public safety, broadband cellular, to medical applications. This article presents a high-level view on how cognitive radio (primarily from a dynamic spectrum access perspective) would supportsuch applications, the benefits that cognitive radio would bring, and also some challenges that are yet to be resolved. We also highlight related standardization that uses cognitive radio technologies tosupport such emerging applications.

There is a growing interest in multi-modal signal processing: sets of related signals are jointly processed to extract information that is otherwise hidden when considering the different modalities independently. One popular problem in crossmodal processing is the localization of visual sources synchronous with audio stimuli. Audiovisual source localization allows to pinpoint and extract salient audio-video information from a scene, enabling innovative applications in communication, interaction and gaming. In this paper we aim to achieve cross-modal localization in real-time using single camera, single microphone data. Existing works use complex statistical data models or complex representations of audio and video features, limiting their applicability in realtime systems. In this paper we propose a simple yet effective algorithm that allows to detect and localize in real-time synchronous audio-video sources. The proposed approach obtains the best speaker localization performances reported to date on the popular CUAVE database, while running in real-time and without requiring any training.

Um die mobile Geräte wie z.B. Mobiltelefone, Music-Player, Digitalkameras Kommunikationsmittel mit Energie zu versorgen, wird gerade fürMassenanwendungen in letzter Zeit häufig induktive kontaktlose Energieübertragung vorgeschlagen. In diesem Artikel werden nun Limitierungen in Hinblick auf die Energie-Effizienz solcher Systeme untersucht. Als Schlussfolgerung ist festzuhalten, dass induktive Energieübertragung in einen größeren Raum (z.B. in einem ganzen Zimmer) sehr ineffizient ist. Hingegen kann induktive Energieübertragung an einer Oberfläche so effizient wie konventionelle Stromversorgungen sein. Darauf basierend wurde ein Pad zur induktiven Energieübertragung entworfen und gebaut, mit dem Ziel, die Batterien von Mobilgeräten aufzuladen. Es kann eine beliebige Anzahl von Geräten aufladen und erlaubteine freie Positionierung auf dem Pad. Um eine genügende kommerzielle Basis für ein solches Produkt zu schaffen, wurde das „Wireless Power Consortium“ gegründet mit Ziel, einen internationalen Industriestandard zum kontaktlosen Laden von Mobilgeräten zu schaffen.

Magnetic particle imaging (MPI) is a new medical imaging technique that performs a direct measurement of the magnetization of ferromagnetic nanoparticles to quantify their local concentration. These particles are usually called SPIOs, i.e. superparamagnetic iron oxides. Specific formulations of these nanoparticles have been clinically approved as contrast agents for magnetic resonance imaging (MRI). As MPI does not image anatomical background, it is similar to methods from nuclear medicine, e.g. PET or SPECT, and consequently, the contrast agent is called a tracer in the context of MPI.

An execution view is an important asset for developing large and complex systems. An execution view helps practitioners to describe, analyze, and communicate what a software system does at runtime and how it does it. In this paper, we present an approach to define viewpoints to guide the construction and use of execution views for an existing large and complex software-intensive system. This approach hasenabled the customization and extension of a set of predefined viewpoints identifying and addressing the requirements for execution views of a specific development organization. The validation and application of the defined viewpoints in practice has helped us to document and transfer them to practitioners to support the construction anduse of execution views of an MRI system, a large software-intensivesystem in the healthcare domain.

Loudspeakers are often modelled as a rigid piston in an infinite baffle. This model is for real loudspeakers somewhat limited in two ways. One issue is that a loudspeaker is not rigid and a second issue is that a loudspeaker is mostly used in a cabinet. Both issues are addressed here by developing the velocity of the radiator in terms oforthogonal polynomials known from optical diffraction theory as Zernike circle polynomials. Using these polynomials we develop semi-analytic expressions for the sound pressure from the radiator in two different cases: as a flexible flat radiator mounted in an infinite baffle, and as the cap of a rigid sphere. In the latter case the comparison is done not only for the pressure but also for other quantitiesviz. the baffle-step response, sound power and directivity, and theacoustic center of the radiator. These quantities are compared withthose from a real loudspeaker.

Objectives: For diagnosis or treatment assessment of knee joint osteoarthritis it is required to measure bone morphometry from radiographic images. We propose a method for automatic measurement of joint alignment from pre-operative as well as post-operative radiographs.Methods: In a two step approach we first detect and segment any implants or other artificial objects within the image. We exploit physical characteristics and avoid prior shape information to cope with the vast amount of implant types. Subsequently, we exploit the implantdelineations to adapt the initialization and adaptation phase of adedicated bone segmentation scheme using deformable template models.Implant and bone contours are fused to derive the final joint segmentation and thus the alignment measurements. Results: We evaluatedour method on clinical long leg radiographs and compared both the initialization rate, corresponding to the number of images successfully processed by the proposed algorithm, and the accuracy of the alignment measurement. Ground truth has been generated by an experiencedorthopedic surgeon. For comparison a second reader reevaluated the measurements. Experiments show that 92% of the joints could be processed automatically and the derived measurements of the automatic method are comparable to a human reader for pre-operative as well as post-operative images with a typical error of 0.7° and correlations ofr=0.82 to r=0.99 with the ground truth. Conclusions: The proposed method allows deriving objective measures of joint alignment from clinical radiographs. Its precision is on par with a human reader for all evaluated measurements. Keywords: Radiography, Bone, Lower Extremity, Replacement Arthroplasty, Orthopedics

A fabric substrate is described for electronic textile with robust interwoven connections between the conductive yarns in it. The fabric's robustness, as a function of the electrical reliability of its conductive yarn connections, is shown to hold over large deformations.This fabric is then used to create an LED based photonic textile display. Finally, we show an example of an application that could make use of such a photonic textile system.

Wireless power transfer allows a convenient, easy to use battery charging of mobile phones and other mobile devices. No hassle with cables and plugs, just place the device on a pad and that’s it. Such asystem even has the potential to become a standard charging solution. Where are the limits for such a solution and which are the side conditions to consider? What are the possibilities to realize such a system? To make the whole idea a success, it is definitely necessaryto come to widely accepted standard. Therefore, in 2009 the WirelessPower Consortium was founded with meanwhile more than 60 internationalcompanies as members. The consortium recently released the first worldwide standard on wireless power for mobile devices of to 5W. The contribution presents details of this standard and the rationale behind.

Prolonged sitting is a potential health risk, not only for people with an inactive lifestyle, but also for those who do meet the recommended amount of physical activity. In this paper, we present two waysto promote the reduction of sedentary behavior. First, we report onan experiment in which office workers (n = 40) received timely persuasive messages on their smartphones, advising them to take an active break whenever 30 minutes of almost uninterrupted computer activity was recorded. The messages resulted in a significant decrease in computer activity and a peak in physical activity, indicating that participants complied to the given advice and took short breaks upon receiving a message. Second, we developed SitCoach, a mobile application to nudge office workers from their seats. SitCoach monitors physical activity and sedentary behavior to provide timely feedback by means of suggested sitting breaks. The results of a user test showedthat the general awareness of the importance of sitting breaks is low. In addition, the ability to take sitting breaks was considered to be highly dependent on external factors. This suggests that raising awareness and increasing self-efficacy are important prerequisitesfor a successful intervention to reduce sedentary behavior.

Recent research on ballistocardiography (BCG) or seismocardiography(SCG) has focused on two major application areas for these technologies: non-invasive diagnostics of hemodynamic parameters and unobtrusive, long-term monitoring of cardiac (and respiratory) rhythms. Forthe former application, an electrocardiogram (ECG) is usually recorded simultaneously to delineate individual heart beats in the cardiacvibration signals and to derive the relevant hemodynamic parameters. Our work, however, covers improvements in sensors and signal processing for the latter application, where only the cardiac vibration signals are available in order to determine the patient’s cardio-pulmonary rhythms. Specifically, we describe a system for the unobtrusive measurement of vital signs by means of an array of novel opticalBCG sensors placed underneath a regular bed mattress. Furthermore, we discuss a signal processing algorithm which exploits the availability of multiple BCG channels in order to provide improved beat-to-beat heart rate and breath-to-breath respiratory rate estimation performance. Our proposed system is also compared to a more conventionalBCG system based on a single EMFi foil. We show that our optical multi-channel system reduces beat-to-beat heart rate estimation errorswhile also increasing the estimation coverage.

Chemical exchange saturation transfer (CEST) based in vivo detectionand quantification of endogenous macro-molecules (i.e., amide proton transfer, APT) or exogenous contrast agents is a highly sensitivemolecular MRI technique bearing a substantial clinical potential forexample in oncology or for cerebro-vascular applications. Techniques for APT/CEST MRI on clinical MRI scanners are reviewed. Typical limitations arise from hardware specifications of the radio-frequency(RF) source(s) regarding maximum pulse length or RF duty-cycle as well as limits imposed by regulations on specific absorption rates (SAR). Clinical APT/CEST techniques described in the literature are compared to two novel approaches: (i) sequences based on operating thescanner in a mode provided for MRS proton-decoupling, and (ii), sequences based on the alternated use of the independent RF amplifiers within an MR system equipped with parallel RF transmission. In emerging applications in the area of whole-body MRI, sensitivity of the APT/CEST techniques to physiological motion is of particular concern.A respiratory triggered sequence is presented and feasibility is shown in the healthy human kidney (in collaboration with Sherry AD et al., UTSW, USA) in the context of CEST-pH mapping using Iopamidol (Bracco Inc., Italy) as contrast agent and ratiometric CEST signal analysis for an absolute pH measurement.

Luminescent concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We present new phosphors and filters that facilitate this. Another type of lightguide-based concentrators, diffraction-based, is discussed as well.

Usually a communication link is secured by means of a symmetric-keyalgorithm. For that, a method is required to securely establish a symmetric-key for that algorithm.This old problem is still relevant and of paramount importance both in existing computernetworks and newlarge-scale ubiquitous systems comprising resource-constrained devices. Identity-based pairwise key agreement allows for the generationof a common key betweentwo parties given secret keying material owned by the first party and the identity of thesecond one. However, existing methods are prone to collusion attacks. In this paper we discuss a new class of key establishment scheme aiming at full collusionresistant identity-based symmetric-key agreement and propose a specific scheme, the HIMMO lgorithm, relying on two design concepts: Hiding Information and Mixing Modular Operations. Collusion attacks on schemes from literature cannot readily be applied to HIMMO. Also, thesimple logic of the HIMMO algorithm allows for very efficient implementations in terms of both speed and memory. Finally, being an identity-based symmetric-key establishment scheme, HIMMO allows for efficient real-world key-exchange protocols.