Local Order in Liquid Gallium-Indium Alloys

Liquid metals such as eutectic Ga–In alloys have low melting points and low toxicity and are used in catalysis and micro-robotics. This study investigates the local atomic structure of liquid gallium-indium alloys by a combination of density measurements, diffraction data, and Monte-Carlo simulation via the empirical potential structure refinement approach. A high-Q shoulder observed in liquid Ga is related to structural rearrangements in the second coordination shell. Structure analysis found coordination environments close to a random distribution for eutectic Ga–In alloy, while electronic effects appear to dominate the mixing enthalpy

muSR and Magnetometry Study of the Type-I Superconductor BeAu

We present muon spin rotation and relaxation (muSR) measurements as well as demagnetising field corrected magnetisation measurements on polycrystalline samples of the noncentrosymmetric superconductor BeAu. From muSR measurements in a transverse field, we determine that BeAu is a type-I superconductor with Hc = 256 Oe, amending the previous understanding of the compound as a type-II superconductor. To account for demagnetising effects in magnetisation measurements, we produce an ellipsoidal sample, for which a demagnetisation factor can be calculated. After correcting for demagnetising effects, our magnetisation results are in agreement with our muSR measurements. Using both types of measurements we construct a phase diagram from T = 30 mK to Tc = 3.25 K. We then study the effect of hydrostatic pressure and find that 450 MPa decreases Tc by 34 mK, comparable to the change seen in type-I elemental superconductors Sn, In and Ta, suggesting BeAu is far from a quantum critical point accessible by the application of pressure.Comment: 10 pages, 8 figure

Medium-density amorphous ice

Amorphous ices govern a range of cosmological processes and are potentially key materials for explaining the anomalies of liquid water. A substantial density gap between low-density and high-density amorphous ice with liquid water in the middle is a cornerstone of our current understanding of water. However, we show that ball milling "ordinary" ice Ih at low temperature gives a structurally distinct medium-density amorphous ice (MDA) within this density gap. These results raise the possibility that MDA is the true glassy state of liquid water or alternatively a heavily sheared crystalline state. Notably, the compression of MDA at low temperature leads to a sharp increase of its recrystallization enthalpy, highlighting that H2O can be a high-energy geophysical material

Antiretroviral Therapy in the Malawi Defence Force: Access, Treatment Outcomes and Impact on Mortality

BACKGROUND: HIV/AIDS affects all sectors of the population and the defence forces are not exempt. A national survey was conducted in all public and private sectors in Malawi that provide antiretroviral therapy (ART) to determine the uptake of ART by army personnel, their outcomes while on treatment, and the impact of ART on mortality in the Malawi Defence Force. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective cohort analysis was carried out, collecting data on access and retention on treatment from all 103 public and 38 private sector ART clinics in Malawi, using standardised patient master cards and clinic registers. Observations were censored on December 31(st) 2006. Independent data on mortality trends in army personnel from all causes between 2002 and 2006 were available from army records. By December 31(st) 2006, there were 85,168 patients ever started on ART in both public and private sectors, of whom 547 (0.7%) were army personnel. Of these, 22% started ART in WHO clinical stage 1 or 2 with a CD4-lymphocyte count of <or=250/mm(3) and 78% started in stage 3 or 4. Treatment outcomes of army personnel by December 31(st) 2006 were:-365 (67%) alive and on ART at their registration facility, 98 (18%) transferred out to another facility, 71 (13%) dead, 9 (2%) lost to follow-up, and 4 (<1%) stopped treatment. The probability of being alive on ART at 6-, 12- and 18-months was 89.8%, 83.4% and 78.8% respectively. All-cause mortality in army personnel declined dramatically over the five year period from 2002-2006. CONCLUSION/SIGNIFICANCE: There has been a good access of army personnel to ART during the last five years with excellent outcomes, and this should serve as an example for other defence forces and large companies in the region

Image Frequency Analysis For Testing Of Fire Service Thermal Imaging Cameras

A growing number of first responders are purchasing infrared cameras (thermal imagers). Thermal imagers provide critical information for many firefighting operations: size up, tracking of fire growth, location of victims and egress routes, overhaul, etc ... Although thermal imagers have proven to be useful tools for the fire service over the past 10-15 years, there is no existing comprehensive performance standard for thermal imagers used in fire service applications. A suite of thermal imager performance metrics and test methods is being developed for possible inclusion in a proposed standard on thermal imagers for the fire service. The following goals apply to two of the imaging performance metrics in this suite: to explore the feasibility of a new spatial resolution metric and test method, the Random Modulation Transfer Function (MTF); and to transfer the essential characteristics of complex fire scene images to a thermal target for the effective temperature range test using image frequency content analysis. Images of humans standing in an upright position at varying distances from the thermal imager under test and wearing either street clothes or turnout gear were analyzed for frequency content. These data were then used to determine the frequency of a bar target for the bench-scale effective temperature range test. © Springer Science+Business Media, LLC 2008

Deep-glassy ice VI revealed with a combination of neutron spectroscopy and diffraction

The recent discovery of a low-temperature endotherm upon heating hydrochloric-acid-doped ice VI has sparked a vivid controversy. The two competing explanations aiming to explain its origin range from a new distinct crystalline phase of ice to deep-glassy states of the well-known ice VI. Problems with the slow kinetics of deuterated phases have been raised, which we circumvent here entirely by simultaneously measuring the inelastic neutron spectra and neutron diffraction data of H2O samples. These measurements support the deep-glassy ice VI scenario and rule out alternative explanations. Additionally, we show that the crystallographic model of D2O ice XV, the ordered counterpart of ice VI, also applies to the corresponding H2O phase. The discovery of deep-glassy ice VI now provides a fascinating new example of ultrastable glasses that are encountered across a wide range of other materials.We thank the Royal Society for a University Research Fellowship (CGS, UF150665), the Austrian Science Fund for a Schrödinger fellowship (AA, J4325), and ISIS for granting access to the TOSCA instrument. Furthermore, this project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 725271).Peer reviewe

Medium-density amorphous ice

The amorphous ices govern a wide range of cosmological processes and are potentially key materials for explaining the anomalies of liquid water. A substantial density gap between low-density amorphous (LDA) and the high-density amorphous ices (HDA) with liquid water in the middle is a cornerstone of our current understanding of water. However, here we show that ball milling ‘ordinary’ ice Ih at low temperature gives a structurally distinct medium-density amorphous ice (MDA) within this density gap. These results raise the possibility that MDA is the true glassy state of liquid water or alternatively a heavily sheared crystalline state. Remarkably, the compression of MDA at low temperature leads to a sharp increase of its recrystallization enthalpy highlighting that H2O can be a high-energy geophysical material