Metal-saturated sulfide assemblages in NWA 2737: Evidence for impact-related sulfur devolatilization in Martian meteorites

International audienceNWA 2737, a Martian meteorite from the Chassignite subclass, contains minute amounts (0.010 ± 0.005 vol%) of metal-saturated Fe-Ni sulfides. These latter bear evidence of the strong shock effects documented by abundant Fe nanoparticles and planar defects in Northwest Africa (NWA) 2737 olivine. A Ni-poor troilite (Fe/S = 1.0 ± 0.01), sometimes Cr-bearing (up to 1 wt%), coexists with micrometer-sized taenite/tetrataenite-type native Ni-Fe alloys (Ni/Fe = 1) and Fe-Os-Ir-(Ru) alloys a few hundreds of nanometers across. The troilite has exsolved flame-like pentlandite (Fe/Fe + Ni = 0.5-0.6). Chalcopyrite is almost lacking, and no pyrite has been found. As a hot desert find, NWA 2737 shows astonishingly fresh sulfides. The composition of troilite coexisting with Ni-Fe alloys is completely at odds with Chassigny and Nahkla sulfides (pyrite + metal-deficient monoclinic-type pyrrhotite). It indicates strongly reducing crystallization conditions (close to IW), several log units below the fO2 conditions inferred from chromites compositions and accepted for Chassignites (FMQ-1 log unit). It is proposed that reduction in sulfides into base and precious metal alloys is operated via sulfur degassing, which is supported by the highly resorbed and denticulated shape of sulfide blebs and their spongy textures. Shock-related S degassing may be responsible for considerable damages in magmatic sulfide structures and sulfide assemblages, with concomitant loss of magnetic properties as documented in some other Martian meteorites

Thirty-five common variants for coronary artery disease: the fruits of much collaborative labour

Coronary artery disease (CAD) is the leading cause of death worldwide. Affected individuals cluster in families in patterns that reflect the sharing of numerous susceptibility genes. Genome-wide and large-scale gene-centric genotyping studies that involve tens of thousands of cases and controls have now mapped common disease variants to 34 distinct loci. Some coronary disease common variants show allelic heterogeneity or copy number variation. Some of the loci include candidate genes that imply conventional or emerging risk factor-mediated mechanisms of disease pathogenesis. Quantitative trait loci associations with risk factors have been informative in Mendelian randomization studies as well as fine-mapping of causative variants. But, for most loci, plausible mechanistic links are uncertain or obscure at present but provide potentially novel directions for research into this disease's pathogenesis. The common variants explain ∼4% of inter-individual variation in disease risk and no more than 13% of the total heritability of coronary disease. Although many CAD genes are presently undiscovered, it is likely that larger collaborative genome-wide association studies will map further common/low-penetrance variants and hoped that low-frequency or rare high-penetrance variants will also be identified in medical resequencing experiments

Seismic and geodetic evidence for grounding-line control of Whillans Ice Stream stick-slip events

The tidally modulated, stick‐slip events of Whillans Ice Stream in West Antarctica produce seismic energy from three locations near the grounding line. Using ice velocity records obtained by combining time series from colocated broadband seismometers and GPS receivers installed on the ice stream during the 2010–2011 and 2011–2012 austral summers, along with far‐field seismic recordings of elastic waves, we locate regions of high rupture velocity and stress drop. These regions, which are analogous to “asperities” in traditional seismic fault studies, are areas of elevated friction at the base of the ice stream. Slip events consistently initiate at one of two locations: near the center of the ice stream, where events associated with the Ross Sea high tide originate, or a grounding‐line spot, where events associated with the Ross Sea low tide initiate, as well as occasional high‐tide events following a skipped low‐tide event. The grounding‐line site, but not the central site, produces Rayleigh waves observable up to 1000 km away, through fast expansion of the slip area. Grounding‐line initiation events also show strong directivity in the downstream direction, indicating initial rupture propagation at 1.5 km/s, compared to an average of 0.150 km/s for the entire slip event. Following slip initiation, additional seismic energy is produced from two sources located near the grounding line: first at the downstream end of Subglacial Lake Engelhardt and second toward the farthest downstream extent of the ice stream. This evidence suggests that the stronger, higher‐friction material along the grounding line controls motion throughout the stick‐slip region

SimAlba: A Spatial Microsimulation Approach to the Analysis of Health Inequalities

This paper presents applied geographical research based on a spatial microsimulation model, SimAlba, aimed at estimating geographically sensitive health variables in Scotland. SimAlba has been developed in order to answer a variety of “what-if” policy questions pertaining to health policy in Scotland. Using the SimAlba model, it is possible to simulate the distributions of previously unknown variables at the small area level such as smoking, alcohol consumption, mental well-being, and obesity. The SimAlba microdataset has been created by combining Scottish Health Survey and Census data using a deterministic reweighting spatial microsimulation algorithm developed for this purpose. The paper presents SimAlba outputs for Scotland’s largest city, Glasgow, and examines the spatial distribution of the simulated variables for small geographical areas in Glasgow as well as the effects on individuals of different policy scenario outcomes. In simulating previously unknown spatial data, a wealth of new perspectives can be examined and explored. This paper explores a small set of those potential avenues of research and shows the power of spatial microsimulation modeling in an urban context

"I try and smile, I try and be cheery, I try not to be pushy. I try to say ‘I’m here for help’ but I leave feeling… worried’’: A qualitative study of perceptions of interactions with health professionals by community-based older adults with chronic pain

Background: Over 50% of community-dwelling older adults experience chronic pain, which threatens their quality of life. Of importance to their pain management is older people’s interaction with health professionals that, if unsatisfactory, may impair the outcome. Aims: To add to the limited research specific to older people living with chronic pain in the community, we explored how they perceive their experiences of interacting with health professionals, seeking factors that might optimise these interactions. Methods: Purposive sampling was used to recruit men and women .65 years with self-reported musculoskeletal chronic pain. Qualitative individual interviews and one group interview were undertaken with 23 participants. Data were transcribed verbatim and underwent Framework Analysis. Results: Three themes were identified. Seeking help illustrates issues around why older people in the community may or may not seek help for chronic pain, and highlights the potential involvement of social comparison. Importance of diagnosis illustrates the desire for professional validation of their condition and an aversion to vague explanations based on the person’s age. Being listened to and being heard illustrates the importance of empathic communication and understanding expectations, with due respect for the person’s age. Conclusions: In common with people of all ages, an effective partnership between an older person in pain and health professionals is essential if pain is to be reported, appropriately assessed and managed, because of the subjective nature of pain and its treatment responses. For older people with pain, perception about their age, by both parties in the partnership, is an additional factor that can unnecessarily interfere with the effectiveness of this partnership. Health professionals should engage with older adults to clarify their expectations about pain and its management, which may be influenced by perceptions about age; and to encourage expression of their concerns, which may also be affected by perceptions about age

Effect of the overflows on the circulation in the Subpolar North Atlantic: A regional model study

An ocean circulation model for process studies of the Subpolar North Atlantic is developed based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model (MOM) code. The basic model configuration is identical with that of the high-resolution model (with a grid size of 1/3° × 2/5°) of the World Ocean Circulation Experiment (WOCE) Community Modeling Effort (CME), except that the domain of integration is confined to the area from 43° to 65°N. Open boundary conditions are used for the inflows and outflows across the northern and southern boundaries. A comparison with the CME model covering the whole North Atlantic (from 15°S to 65°N) shows that the regional model, with inflow conditions at 43°N from a CME solution, is able to reproduce the CME results for the subpolar area. Thus the potential of a regional model lies in its use as an efficient tool for numerical experiments aiming at an identification of the key physical processes that determine the circulation and water mass transformations in the subpolar gyre. This study deals primarily with the representation and role of the overflow waters that enter the domain at the northern boundary. Sensitivity experiments show the effect of closed versus open boundaries, of different hydrographic conditions at inflow points, and of the representation of the narrow Faeroe Bank Channel. The representation of overflow processes in the Denmark Strait is the main controlling mechanism for the net transport of the deep boundary current along the Greenland continental slope and further downstream. Changes in the Faeroe Bank Channel throughflow conditions have a comparatively smaller effect on the deep transport in the western basin but strongly affect the water mass characteristics in the eastern North Atlantic. The deep water transport at Cape Farewell and further downstream is enhanced compared to the combined Denmark Strait and Iceland-Scotland overflows. This enhancement can be attributed to a barotropic recirculation in the Irminger Basin which is very sensitive to the outflow conditions in the Denmark Strait. The representation of both overflow regions determine the upper layer circulation in the Irminger and Iceland Basins, in particular the path of the North Atlantic Current

International Coercion, Emulation and Policy Diffusion: Market-Oriented Infrastructure Reforms, 1977-1999

Why do some countries adopt market-oriented reforms such as deregulation, privatization and liberalization of competition in their infrastructure industries while others do not? Why did the pace of adoption accelerate in the 1990s? Building on neo-institutional theory in sociology, we argue that the domestic adoption of market-oriented reforms is strongly influenced by international pressures of coercion and emulation. We find robust support for these arguments with an event-history analysis of the determinants of reform in the telecommunications and electricity sectors of as many as 205 countries and territories between 1977 and 1999. Our results also suggest that the coercive effect of multilateral lending from the IMF, the World Bank or Regional Development Banks is increasing over time, a finding that is consistent with anecdotal evidence that multilateral organizations have broadened the scope of the “conditionality” terms specifying market-oriented reforms imposed on borrowing countries. We discuss the possibility that, by pressuring countries into policy reform, cross-national coercion and emulation may not produce ideal outcomes.http://deepblue.lib.umich.edu/bitstream/2027.42/40099/3/wp713.pd

Cytokine profile and induction of T helper type 17 and regulatory T cells by human peripheral mononuclear cells after microbial exposure

The immunomodulatory effects of probiotics were assessed following exposure of normal peripheral blood mononuclear cells (PBMC), cord blood cells and the spleen-derived monocyte/macrophage cell line CRL-9850 to Lactobacillus acidophilus LAVRI-A1, Lb. rhamnosus GG, exopolysaccharides (EPS)-producing Streptococcus thermophilus St1275, Bifidobacteriun longum BL536, B. lactis B94 and Escherichia coli TG1 strains. The production of a panel of pro- and anti-inflammatory cytokines by PBMC following bacterial stimulation was measured, using live, heat-killed or mock gastrointestinal tract (GIT)-exposed bacteria, and results show that (i) all bacterial strains investigated induced significant secretion of pro- and anti-inflammatory cytokines from PBMC-derived monocytes/macrophages; and (ii) cytokine levels increased relative to the expansion of bacterial cell numbers over time for cells exposed to live cultures. Bifidobacteria and S. thermophilus stimulated significant concentrations of transforming growth factor (TGF)-β, an interleukin necessary for the differentiation of regulatory T cells (Treg)/T helper type 17 (Th17) cells and, as such, the study further examined the induction of Th17 and Treg cells after PBMC exposure to selected bacteria for 96 h. Data show a significant increase in the numbers of both cell types in the exposed populations, measured by cell surface marker expression and by cytokine production. Probiotics have been shown to induce cytokines from a range of immune cells following ingestion of these organisms. These studies suggest that probiotics' interaction with immune-competent cells produces a cytokine milieu, exerting immunomodulatory effects on local effector cells, as well as potently inducing differentiation of Th17 and Treg cells

Quantum superpositions of clockwise and counterclockwise supercurrent states in the dynamics of a rf-SQUID exposed to a quantized electromagnetic field

The dynamical behavior of a superconducting quantum interference device (a rf-SQUID) irradiated by a single mode quantized electromagnetic field is theoretically investigated. Treating the SQUID as a flux qubit, we analyze the dynamics of the combined system within the low lying energy Hilbert subspace both in the asymmetric and in the symmetric SQUID potential configurations. We show that the temporal evolution of the system is dominated by an oscillatory behavior characterized by more than one, generally speaking, incommensurable Rabi frequencies whose expressions are explicitly given. We find that the external parameters may fixed in such a way to realize a control on the dynamical replay of the total system which, for instance, may be forced to exhibit a periodic evolution accompanied by the occurrence of an oscillatory disappearance of entanglement between the two subsystems. We demonstrate the possibility of generating quantum maximally entangled superpositions of the two macroscopically distinguishable states describing clockwise and counterclockwise supercurrents in the loop. The experimental feasibility of our proposal is briefly discussed.Comment: 16 pages, 7 figures, submitted to PR