Image reconstruction in low-field MRI: A super-resolution approach

The quality of magnetic resonance images produced by conventional MRI scanners is guaranteed by the strength and homogeneity of the magnetic field. However, the superconducting magnets required to produce such a field make MRI scanners large and expensive and hence inaccessible to a large number of people in developing countries. Our partners...

How to optimize the personalization vector to combat link spamming

Google uses the PageRank algorithm to rank the web. The algorithm models the behavior of a random surfer. It follows an outlink or it goes to any page by entering a URL into an address bar. This is also called teleportation. The probability that a surfer teleports to a page is given in the personalization vector. The PageRank algorithm returns a...

Met Markov ketens op zoek naar de Zero Variance Importance Sampling verdeling

Standaard Monte Carlo is niet geschikt voor het analyseren van Rare Events. We laten zien dat we bij dit soort problemen Importance Sampling kunnen toepassen en hoe we de Zero Variance verdeling kunnen vinden. Deze verdeling hangt echter af van constanten waar we de waarde niet van weten, maar door deze constanten te benaderen krijgen we een...

Saddlepoint Approximations for Expectations and an Application to CDO Pricing

We derive two types of saddlepoint approximations for expectations in the form of E[(X - K)+], where X is the sum of n independent random variables and K is a known constant. We establish error convergence rates for both types of approximations in the independently and identically distributed case. The approximations are further extended to...

Spectra of Two-Dimensional Models for Thin Plates with Sharp Edges

We investigate the spectrum of the two-dimensional model for a thin plate with a sharp edge. The model yields an elliptic $3\times3$ Agmon–Douglis–Nirenberg system on a planar domain with coefficients degenerating at the boundary. We prove that in the case of a degeneration rate $\alpha<2$, the spectrum is discrete, but, for $\alpha\geq2$, there...