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This work investigates three penalized-likelihood expectation maximization (EM) algorithms for image reconstruction with Poisson data where the images are known a priori to be sparse in the space domain. The penalty functions considered are the 1 norm, the 0 " norm, " and a penalty function based on the sum of logarithms of pixel values, R(x) = np j=1 log(More)
—Three-dimensional (3-D) position-sensitive CdZnTe (CZT) gamma-ray spectrometers employing new VAS3.1/TAT3 ASIC readouts were developed and tested. Each spectrometer is a 1 5 1 5 1 cm 3 CdZnTe crystal with 11 11 pixellated anodes wire-bonded to the readout electronics using an intermediate ceramic substrate with plated-through-via. The signals from the(More)
The persistence of central memory CD4(+) T cells (T(CM) cells) is a major correlate of immunological protection in HIV/AIDS, as the rate of T(CM) cell decline predicts HIV disease progression. In this study, we show that T(CM) cells and effector memory CD4(+) T cells (T(EM) cells) from HIV(+) elite controller (EC) subjects are less susceptible to(More)
Chronic viral infections lead to persistent CD8 T cell activation and functional exhaustion. Expression of programmed cell death-1 (PD-1) has been associated to CD8 T cell dysfunction in HIV infection. Herein we report that another negative regulator of T cell activation, CD160, was also upregulated on HIV-specific CD8 T lymphocytes mostly during the(More)
Dengue virus (DENV) is a re-emerging arthropod borne flavivirus that infects more than 300 million people worldwide, leading to 50,000 deaths annually. Because dendritic cells (DC) in the skin and blood are the first target cells for DENV, we sought to investigate the early molecular events involved in the host response to the virus in primary human(More)
A 3D CdZnTe detector can provide 3D position information as well as energy information of each individual interaction when a gamma ray is scattered or absorbed in the detector. This unique feature provides the 3D CdZnTe detector the capability to do Compton imaging with a single detector. After detector calibration, real-time data acquisition and imaging(More)
HgI 2 gamma-ray spectrometers having small pixel anodes and a thickness of 4–5 mm have been investigated. An energy resolution of 2.9% FWHM was obtained on a 4 mm thick detector using the three-dimensional position sensitive single polarity charge sensing technique. Typical phenomena observed on two detectors are reported and their characteristics are(More)
Owing to the harmfulness and seriousness of Schistosomiasis japonica in China, the control and prevention of S. japonica transmission are imperative. As the unique intermediate host of this disease, Oncomelania hupensis plays an important role in the transmission. It has been reported that the snail population in Qiangliang Lake district, Dongting Lake(More)
Cs source. The average of both detectors were measured to be cm /V. The detection efficiency of the two detectors was evaluated at several different energies up to 1.3 MeV by comparing with simulated data. It was found that the total counts agree well between the measured data and the simulated data over the studied energy range. However, the measured(More)