Characterisation of spatial network-like patterns from junctions' geometry

We propose a new method for quantitative characterization of spatial network-like patterns with loops, such as surface fracture patterns, leaf vein networks and patterns of urban streets. Such patterns are not well characterized by purely topological estimators: also patterns that both look different and result from different morphogenetic processes can have similar topology. A local geometric cue -the angles formed by the different branches at junctions- can complement topological information and allow to quantify the large scale spatial coherence of the pattern. For patterns that grow over time, such as fracture lines on the surface of ceramics, the rank assigned by our method to each individual segment of the pattern approximates the order of appearance of that segment. We apply the method to various network-like patterns and we find a continuous but sharp dichotomy between two classes of spatial networks: hierarchical and homogeneous. The first class results from a sequential growth process and presents large scale organization, the latter presents local, but not global organization.Comment: version 2, 14 page

Clostridium difficile infection among veterans health administration patients

OBJECTIVETo report on the prevalence and incidence of Clostridium difficile infection (CDI) from 2009 to 2013 among Veterans Healthcare Administration patientsDESIGNA retrospective descriptive analysis of data extracted from a large electronic medical record (EMR) databaseSETTINGData were acquired from VHA healthcare records from 2009 to 2013 that included outpatient clinical visits, long-term care, and hospitalized care as well as pharmacy and laboratory information.RESULTSIn 2009, there were 10,207 CDI episodes, and in 2013, there were 12,143 CDI episodes, an increase of 19.0%. The overall CDI rate increased by 8.4% from 193 episodes per 100,000 patient years in 2009 to 209 episodes per 100,000 patient years in 2013. Of the CDI episodes identified in 2009, 58% were identified during a hospitalization, and 42% were identified in an outpatient setting. In 2013, 44% of the CDI episodes were identified in an outpatient setting.CONCLUSIONThis is one of the largest studies that has utilized timely EMR data to describe the current CDI epidemiology at the VHA. Despite an aging population with greater burden of comorbidity than the general US population, our data show that VHA CDI rates stabilized between 2011 and 2013 following increases likely attributable to the introduction of the more sensitive nucleic acid amplification tests (NAATs). The findings in this report will help establish an accurate benchmark against which both current and future VA CDI prevention initiatives can be measured.Infect. Control Hosp. Epidemiol. 2015;36(9):1038–1045</jats:sec

An XMM-Newton Observation of the Local Bubble Using a Shadowing Filament in the Southern Galactic Hemisphere

We present an analysis of the X-ray spectrum of the Local Bubble, obtained by simultaneously analyzing spectra from two XMM-Newton pointings on and off an absorbing filament in the Southern galactic hemisphere (b ~ -45 deg). We use the difference in the Galactic column density in these two directions to deduce the contributions of the unabsorbed foreground emission due to the Local Bubble, and the absorbed emission from the Galactic halo and the extragalactic background. We find the Local Bubble emission is consistent with emission from a plasma in collisional ionization equilibrium with a temperature $\log T_{LB} = 6.06^{+0.02}_{-0.04}$ and an emission measure of 0.018 cm^{-6} pc. Our measured temperature is in good agreement with values obtained from ROSAT All-Sky Survey data, but is lower than that measured by other recent XMM-Newton observations of the Local Bubble, which find $\log T_{LB} \approx 6.2$ (although for some of these observations it is possible that the foreground emission is contaminated by non-Local Bubble emission from Loop I). The higher temperature observed towards other directions is inconsistent with our data, when combined with a FUSE measurement of the Galactic halo O VI intensity. This therefore suggests that the Local Bubble is thermally anisotropic. Our data are unable to rule out a non-equilibrium model in which the plasma is underionized. However, an overionized recombining plasma model, while observationally acceptable for certain densities and temperatures, generally gives an implausibly young age for the Local Bubble (\la 6 \times 10^5 yr).Comment: Accepted for publication in the Astrophysical Journal. 16 pages, 9 figure

Correction: Thioredoxin Glutathione Reductase from Schistosoma mansoni: An Essential Parasite Enzyme and a Key Drug Target

Correction: Thioredoxin Glutathione Reductase from Schistosoma mansoni: An Essential Parasite Enzyme and a Key Drug Targe

Thioredoxin Glutathione Reductase from Schistosoma mansoni: An Essential Parasite Enzyme and a Key Drug Target

Using both genetic and biochemical approaches, David Williams and colleagues show that the parasite thioredoxin glutathione reductase meets all the major criteria to be a key target for antischistosomal chemotherapy

Diffuse Thermal X-Ray Emission in the Core of the Young Massive Cluster Westerlund 1

We present an analysis of the diffuse hard X-ray emission in the core of the young massive Galactic cluster Westerlund 1 based on a 48 ks XMM-Newton observation. Chandra results for the diffuse X-ray emission have indicated a soft thermal component together with a hard component that could be either thermal or non-thermal. We seek to resolve this ambiguity regarding the hard component exploiting the higher sensitivity of XMM-Newton to diffuse emission. Our new X-ray spectra from the central (2' radius) diffuse emission are found to exhibit He-like Fe 6.7 keV line emission, demonstrating that the hard emission in the cluster core is predominantly thermal in origin. Potential sources of this hard component are reviewed, namely an unresolved Pre-Main Sequence population, a thermalized cluster wind and Supernova Remnants interacting with stellar winds. We find that the thermalized cluster wind likely contributes the majority of the hard emission with some contribution from the Pre-Main Sequence population. It is unlikely that Supernova Remnants are contributing significantly to the Wd1 diffuse emission at the current epoch

Prediction and understanding of soft proton contamination in XMM-Newton: a machine learning approach

One of the major and unfortunately unforeseen sources of background for the current generation of X-ray telescopes are few tens to hundreds of keV (soft) protons concentrated by the mirrors. One such telescope is the European Space Agency's (ESA) X-ray Multi-Mirror Mission (XMM-Newton). Its observing time lost due to background contamination is about 40\%. This loss of observing time affects all the major broad science goals of this observatory, ranging from cosmology to astrophysics of neutron stars and black holes. The soft proton background could dramatically impact future large X-ray missions such as the ESA planned Athena mission (http://www.the-athena-x-ray-observatory.eu/). Physical processes that trigger this background are still poorly understood. We use a Machine Learning (ML) approach to delineate related important parameters and to develop a model to predict the background contamination using 12 years of XMM observations. As predictors we use the location of satellite, solar and geomagnetic activity parameters. We revealed that the contamination is most strongly related to the distance in southern direction, $Z$, (XMM observations were in the southern hemisphere), the solar wind radial velocity and the location on the magnetospheric magnetic field lines. We derived simple empirical models for the first two individual predictors and an ML model which utilizes an ensemble of the predictors (Extra Trees Regressor) and gives better performance. Based on our analysis, future missions should minimize observations during times associated with high solar wind speed and avoid closed magnetic field lines, especially at the dusk flank region in the southern hemisphere.Comment: 20 pages, 11 figure

Water Dynamics at Protein Interfaces: Ultrafast Optical Kerr Effect Study

The behavior of water molecules surrounding a protein can have an important bearing on its structure and function. Consequently, a great deal of attention has been focused on changes in the relaxation dynamics of water when it is located at the protein surface. Here we use the ultrafast optical Kerr effect to study the H-bond structure and dynamics of aqueous solutions of proteins. Measurements are made for three proteins as a function of concentration. We find that the water dynamics in the first solvation layer of the proteins are slowed by up to a factor of 8 in comparison to those in bulk water. The most marked slowdown was observed for the most hydrophilic protein studied, bovine serum albumin, whereas the most hydrophobic protein, trypsin, had a slightly smaller effect. The terahertz Raman spectra of these protein solutions resemble those of pure water up to 5 wt % of protein, above which a new feature appears at 80 cm–1, which is assigned to a bending of the protein amide chain

A Luminous Be+White Dwarf Supersoft Source in the Wing of the SMC: MAXI J0158-744

We present a multi-wavelength analysis of the very fast X-ray transient MAXI J0158-744, which was detected by MAXI/GSC on 2011 November 11. The subsequent exponential decline of the X-ray flux was followed with Swift observations, all of which revealed spectra with low temperatures (~100eV) indicating that MAXI J0158-744 is a new Supersoft Source (SSS). The Swift X-ray spectra near maximum show features around 0.8 keV that we interpret as possible absorption from OVIII, and emission from O, Fe, and Ne lines. We obtained SAAO and ESO optical spectra of the counterpart early in the outburst and several weeks later. The early spectrum is dominated by strong Balmer and HeI emission, together with weaker HeII emission. The later spectrum reveals absorption features that indicate a B1/2IIIe spectral type, and all spectral features are at velocities consistent with the Small Magellanic Cloud. At this distance, it is a luminous SSS (>10^37 erg/s) but whose brief peak luminosity of >10^39 erg/s in the 2-4 keV band makes it the brightest SSS yet seen at "hard" X-rays. We propose that MAXI J0158-744 is a Be-WD binary, and the first example to possibly enter ULX territory. The brief hard X-ray flash could possibly be a result of the interaction of the ejected nova shell with the B star wind in which the white dwarf (WD) is embedded. This makes MAXI J0158-744 only the third Be/WD system in the Magellanic Clouds, but it is by far the most luminous. The properties of MAXI J0158-744 give weight to previous suggestions that SSS in nearby galaxies are associated with early-type stellar systems.Comment: 15 pages, 8 figures; ApJ accepte

Cellular and humoral immune responses and protection against schistosomes induced by a radiation-attenuated vaccine in chimpanzees

The radiation-attenuated Schistosoma mansoni vaccine is highly effective in rodents and primates but has never been tested in humans, primarily for safety reasons. To strengthen its status as a paradigm for a human recombinant antigen vaccine, we have undertaken a small-scale vaccination and challenge experiment in chimpanzees (Pan troglodytes). Immunological, clinical, and parasitological parameters were measured in three animals after multiple vaccinations, together with three controls, during the acute and chronic stages of challenge infection up to chemotherapeutic cure. Vaccination induced a strong in vitro proliferative response and early gamma interferon production, but type 2 cytokines were dominant by the time of challenge. The controls showed little response to challenge infection before the acute stage of the disease, initiated by egg deposition. In contrast, the responses of vaccinated animals were muted throughout the challenge period. Vaccination also induced parasite-specific immunoglobulin M (IgM) and IgG, which reached high levels at the time of challenge, while in control animals levels did not rise markedly before egg deposition. The protective effects of vaccination were manifested as an amelioration of acute disease and overall morbidity, revealed by differences in gamma-glutamyl transferase level, leukocytosis, eosinophilia, and hematocrit. Moreover, vaccinated chimpanzees had a 46% lower level of circulating cathodic antigen and a 38% reduction in fecal egg output, compared to controls, during the chronic phase of infection