Complex Fragment Emission in Coincidence with Angle-Correlated Fission Fragments in the 270 MeV 3-He + 232-Th System

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Emission of Intermediate Mass Fragments Normal to the Fission Axis in Hot Heavy Nuclei

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Nonequilibrium Slope Temperatures for IMF Emission in the E/A = 20-100 MeV 14-N + 197-Au Reactions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

IMF Emission in the 14-N + nat-Ag, Au Reactions at E/A = 60-100 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV

The momentum distribution of electrons from semi-leptonic decays of charm and bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative quantum chromodynamics (pQCD) calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is \sigma_{b\b^bar}= 3.2 ^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.Comment: 432 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

Neutral metallated and meso-substituted porphyrins as antimicrobial agents against Gram-positive pathogens

Staphylococcus aureus is a bacterial pathogen that causes severe infections among humans. The increasing emergence of antibiotic resistance necessitates the development of new strategies to combat the spread of disease. One approach is photodynamic inactivation using porphyrin photosensitizers, which generate superoxide and other radicals in the presence of light, causing cell death via the oxidation of proteins and lipids. In this study, we analyzed a novel library of meso-substituted and metallated porphyrins for activity against multidrug-resistant S. aureus. From a library of 251 compounds, 51 showed antimicrobial activity, in three discrete classes of activity: those that functioned only in light, those that had toxicity only in darkness, and those that displayed activity regardless of illumination. We further demonstrated the broad-spectrum activity of these compounds against a variety of pathogens, including Bacillus anthracis, Enterococcus faecalis, and Escherichia coli. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) analyses of lead compounds (XPZ-263 and XPZ-271) revealed strong activity and killing towards methicillin-resistant S. aureus (MRSA) strains. An analysis of mutation frequencies revealed low incidences of resistance to lead compounds by E. coli and MRSA. Finally, an exploration of the underlying mechanism of action suggests that these compounds do not depend solely upon light-induced radical generation for toxicity, highlighting their potential for clinical applications