Dimensionality reduction is often recommended to handle high dimensional data before performing the tasks of visualization and classification. So far, large families of dimensionality reduction methods besides the supervised or the unsupervised, the linear or the nonlinear, the global or the local have been developed. In this paper, a maximum nonparametric margin projection (MNMP) method is put...

The dark flux correction step of the Faint Object Spectrograph calibration pipeline was investigated with the joint aims of applying a more physical model and improving the performance of the pipeline. After processing with the original calfos pipeline, dark calibration data shows a large scatter in count rates. We were able to reduce this scatter to some extent by scaling the correction accord...

A Monte Carlo simulation, based on GEANT4, has been developed to compute the contribution of first-order, second-order, and higher order scattering in a Computed Tomography (CT) system equipped with an industrial 450 kV X-ray tube and an area detector. The validation of simulation against the experimental data showed a good agreement. The amount of scattering produced by several hollow aluminum...

Multiple research directions in the past have emphasized the beneets of multidesti-nation message passing to support eecient non-personalized communication like broadcast and multicast. In this paper, we investigate whether personalized communications like scatter can beneet by using multidestination message-passing support, if available in a system. In order to use such support, we propose a n...

Data decomposition is probably the most successful method for generating parallel programs. In this paper a general framework is described for the automatic generation of parallel programs based on a separately specified decomposition of the data. To this purpose, programs and data decompositions are expressed in a calculus, called Vcal. It is shown that by rewriting calculus expressions, Singl...

We are developing an accelerated Monte Carlo simulation of PET that can be uscd for scatter correction of 3D PET datn. Our Monte Carlo technique accurately accounts for single, multiple, and dual Compton scatter events, attenuation through the patient bed, activity from outside the field of view, and the true energy response of the scanner. We have incorporated innovative sampling techniques th...

The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG–galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocit...

Based on Kunyansky’s and our previous work, an efficient, analytical solution to the reconstruction problem of myocardial perfusion SPECT has been developed that allows simultaneous compensation for non-uniform attenuation, scatter, and system-dependent resolution variation, as well as suppression of signal-dependent Poisson noise. To avoid reconstructed images being corrupted by the presence o...

Introduction: In nuclear medicine imaging, detection of the scattered photons along with the primary photons is one of the major problems that can lead to a decrease in ddiagnostic accuracy. Therefore, use of a suitable scatter correction method can help to improve of the image quality and increase of diagnostic accuracy. The aim of this study is evaluation of five energy wind...