Cryogenic Origin for Mars Analog Carbonates in the Bockfjord Volcanic Complex Svalbard (Norway)

The Sverrefjell and Sigurdfjell eruptive centers in the Bockfjord Volcanic Complex (BVC) on Svalbard (Norway) formed by subglacial eruptions ca. 1 Ma ago. These eruptive centers carry ubiquitous magnesian carbonate deposits including dolomitemagnesite globules similar to those in the Martian meteorite ALH84001. Carbonates in mantle xenoliths are dominated by ALH84001 type carbonate globules that formed during quenching of CO2-rich mantle fluids. Lava hosted carbonates include ALH84001 type carbonate globules occurring throughout lava vesicles and microfractures and massive carbonate deposits associated with vertical volcanic vents. Massive carbonates include < or equal 5 cm thick magnesite deposits protruding downwards into clear blue ice within volcanic vents and carbonate cemented lava breccias associated with volcanic vents. Carbonate cements comprise layered deposits of calcite, dolomite, huntite, magnesite and aragonite associated with ALH84001 type carbonate globules lining lava vesicles. Combined Mossbauer, XRD and VNIR data show that breccia carbonate cements at Sverrefjell are analog to Comanche carbonates at Gusev crater

A Large Outbreak of Hepatitis E Among a Displaced Population in Darfur, Sudan, 2004: The Role of Water Treatment Methods.

BACKGROUND: The conflict in Darfur, Sudan, was responsible for the displacement of 1.8 million civilians. We investigated a large outbreak of hepatitis E virus (HEV) infection in Mornay camp (78,800 inhabitants) in western Darfur. METHODS: To describe the outbreak, we used clinical and demographic information from cases recorded at the camp between 26 July and 31 December 2004. We conducted a case-cohort study and a retrospective cohort study to identify risk factors for clinical and asymptomatic hepatitis E, respectively. We collected stool and serum samples from animals and performed a bacteriological analysis of water samples. Human samples were tested for immunoglobulin G and immunoglobulin M antibody to HEV (for serum samples) and for amplification of the HEV genome (for serum and stool samples). RESULTS: In 6 months, 2621 hepatitis E cases were recorded (attack rate, 3.3%), with a case-fatality rate of 1.7% (45 deaths, 19 of which involved were pregnant women). Risk factors for clinical HEV infection included age of 15-45 years (odds ratio, 2.13; 95% confidence interval, 1.02-4.46) and drinking chlorinated surface water (odds ratio, 2.49; 95% confidence interval, 1.22-5.08). Both factors were also suggestive of increased risk for asymptomatic HEV infection, although this was not found to be statistically significant. HEV RNA was positively identified in serum samples obtained from 2 donkeys. No bacteria were identified from any sample of chlorinated water tested. CONCLUSIONS: Current recommendations to ensure a safe water supply may have been insufficient to inactivate HEV and control this epidemic. This research highlights the need to evaluate current water treatment methods and to identify alternative solutions adapted to complex emergencies

A survey tool for measuring evidence-based decision making capacity in public health agencies

BACKGROUND: While increasing attention is placed on using evidence-based decision making (EBDM) to improve public health, there is little research assessing the current EBDM capacity of the public health workforce. Public health agencies serve a wide range of populations with varying levels of resources. Our survey tool allows an individual agency to collect data that reflects its unique workforce. METHODS: Health department leaders and academic researchers collaboratively developed and conducted cross-sectional surveys in Kansas and Mississippi (USA) to assess EBDM capacity. Surveys were delivered to state- and local-level practitioners and community partners working in chronic disease control and prevention. The core component of the surveys was adopted from a previously tested instrument and measured gaps (importance versus availability) in competencies for EBDM in chronic disease. Other survey questions addressed expectations and incentives for using EBDM, self-efficacy in three EBDM skills, and estimates of EBDM within the agency. RESULTS: In both states, participants identified communication with policymakers, use of economic evaluation, and translation of research to practice as top competency gaps. Self-efficacy in developing evidence-based chronic disease control programs was lower than in finding or using data. Public health practitioners estimated that approximately two-thirds of programs in their agency were evidence-based. Mississippi participants indicated that health department leaders' expectations for the use of EBDM was approximately twice that of co-workers' expectations and that the use of EBDM could be increased with training and leadership prioritization. CONCLUSIONS: The assessment of EBDM capacity in Kansas and Mississippi built upon previous nationwide findings to identify top gaps in core competencies for EBDM in chronic disease and to estimate a percentage of programs in U.S. health departments that are evidence-based. The survey can serve as a valuable tool for other health departments and non-governmental organizations to assess EBDM capacity within their own workforce and to assist in the identification of approaches that will enhance the uptake of EBDM processes in public health programming and policymaking. Localized survey findings can provide direction for focusing workforce training programs and can indicate the types of incentives and policies that could affect the culture of EBDM in the workplace

Aging and PBX 9502

Components made from PBX 9502, an insensitive high explosive formulated with triaminotrinitrobenzene (TATB) and Kel-F 800 binder, have been in service for nearly two decades. Since that time, samples have been destructively evaluated to determine if potential changes that might affect safety, reliability, or performance have occurred in the high explosive with time. Data from routine, historical testing is reported elsewhere. This paper focuses on specific tests conducted to evaluate the effects of natural aging on handling sensitivity (through the small-scale tests of Human Electrostatic Discharge, friction, and Drop Weight Impact), compressive strength, and thermal ignition. Also reported are the effects of a radiation environment on TATB. Small-scale sensitivity tests show no differences between aged and unaged material. Observed differences in compressive strength behavior are attributed to conditions of original material rather than aging effects. Thermal ignition by flame and laser methods showed no changes between aged and unaged material. Extreme levels of radiation are shown to have only minimal effects in explosive response tests. PBX 9502 is concluded, once again, to be a very stable material, aging gracefully

Some Observations on the Structure of TATB

The recent discovery of second-harmonic light generation (SHG) from 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) has renewed interest in both the crystallography and the identification of defect structures in this material. The accepted crystal structure is triclinic but centrosymmetric (P-1); SHG is not expected from materials of this symmetry. A wide variety of syntheses have been shown to produce SHG-positive materials, including an emulsion technique, two different recrystallization methods, and a variety of combined reaction - precipitation processes. In addition, two standard commercial powders have shown the property after annealing in the 300 C range. We have examined the structures of several of these powders using polarized light microscopy (PLM), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD). We find that SHG-positive materials typically contain crystals both more transparent and more strongly faceted (i.e. ''more perfect'') than weak-SHG ones and that the positive samples show stronger texture in their powder diffraction patterns. These results are compared with predictions from Cady's structure

High temperature dielectric ceramics: a review of temperature-stable high-permittivity perovskites

Recent developments are reviewed in the search for dielectric ceramics which can operate at temperatures >200 °C, well above the limit of existing high volumetric efficiency capacitor materials. Compositional systems based on lead-free relaxor dielectrics with mixed cation site occupancy on the perovskite lattice are summarised, and properties compared. As a consequence of increased dielectric peak broadening and shifts to peak temperatures, properties can be engineered such that a plateau in relative permittivity–temperature response (εr–T) is obtained, giving a ±15 %, or better, consistency in εr over a wide temperature range. Materials with extended upper temperature limits of 300, 400 and indeed 500 °C are grouped in this article according to the parent component of the solid solution, for example BaTiO3 and Na0.5Bi0.5TiO3. Challenges are highlighted in achieving a lower working temperature of −55 °C, whilst also extending the upper temperature limit of stable εr to ≥300 °C, and achieving high-permittivity and low values of dielectric loss tangent, tan δ. Summary tables and diagrams are used to help compare values of εr, tan δ, and temperature ranges of stability for different material

BOW SHOCK FRAGMENTATION DRIVEN BY A THERMAL INSTABILITY IN LABORATORY ASTROPHYSICS EXPERIMENTS

The role of radiative cooling during the evolution of a bow shock was studied in laboratory-astrophysics experiments that are scalable to bow shocks present in jets from young stellar objects. The laboratory bow shock is formed during the collision of two counter-streaming, supersonic plasma jets produced by an opposing pair of radial foil Z-pinches driven by the current pulse from the MAGPIE pulsed-power generator. The jets have different flow velocities in the laboratory frame and the experiments are driven over many times the characteristic cooling time-scale. The initially smooth bow shock rapidly develops small-scale non-uniformities over temporal and spatial scales that are consistent with a thermal instability triggered by strong radiative cooling in the shock. The growth of these perturbations eventually results in a global fragmentation of the bow shock front. The formation of a thermal instability is supported by analysis of the plasma cooling function calculated for the experimental conditions with the radiative packages ABAKO/RAPCAL.Comment: 9 pages, 5 figures, Accepted for publication in The Astrophysical Journal on 5th November 201