Large- N expansion for unitary superfluid Fermi gases

We analyze strongly interacting Fermi gases in the unitary regime by considering the generalization to an arbitrary number N of spin- 1 2 fermion flavors with Sp (2N) symmetry. For N→ this problem is exactly solved by the Bardeen-Cooper-Schrieffer-Bose-Einstein condensate mean-field theory, with corrections small in the parameter 1 N. The large- N expansion provides a systematic way to determine corrections to mean-field predictions, allowing the calculation of a variety of thermodynamic quantities at (and in proximity to) unitarity, including the energy, the pairing gap, and the upper-critical polarization (in the case of a polarized gas) for the normal to superfluid instability. For the physical case of N=1, among other quantities, we predict in the unitarity regime, the energy of the gas to be ξ=0.28 times that for the noninteracting gas and the pairing gap to be 0.52 times the Fermi energy. © 2007 The American Physical Society

Detection of streptococcus suis in bioaerosols of swine confinement buildings

Streptococcus suis is an important swine pathogen that can cause septicemia, meningitis, and pneumonia. Also recognized as an emerging zoonotic agent, it is responsible for outbreaks of human infections in Asian countries. Serotype 2 is the predominant isolate from diseased animals and humans. The aerosolization of S. suis in the air of swine confinement buildings (SCB) was studied. The presence of S. suis in bioaerosols was monitored in SCB where cases of infection had been reported and in healthy SCB without reported infections. Using a quantitative-PCR (qPCR) method, we determined the total number of bacteria (1 × 108 to 2 × 108 airborne/m3), total number of S. suis bacteria (4 × 105 to 10 × 105 airborne/m3), and number of S. suis serotype 2 and 1/2 bacteria (1 × 103 to 30 × 103 airborne/m3) present in the air. S. suis serotypes 2 and 1/2 were detected in the air of all growing/finishing SCB that had documented cases of S. suis infection and in 50% of healthy SCB. The total number of bacteria and total numbers of S. suis and S. suis serotype 2 and 1/2 bacteria were monitored in one positive SCB during a 5-week period, and it was shown that the aerosolized S. suis serotypes 2 and 1/2 remain airborne for a prolonged period. When the effect of aerosolization on S. suis was observed, the percentage of intact S. suis bacteria (showing cell membrane integrity) in the air might have been up to 13%. Finally S. suis was found in nasal swabs from 14 out of 21 healthy finishing-SCB workers, suggesting significant exposure to the pathogen. This report provides a better understanding of the aerosolization, prevalence, and persistence of S. suis in SCB

Superfluid transition in a rotating fermi gas with resonant interactions

We study a rotating atomic Fermi gas near a narrow s-wave Feshbach resonance in a uniaxial trap with frequencies Ω⊥, Ωz. We predict the upper-critical angular velocity, ωc2(δ,T), as a function of temperature T and detuning δ across the BEC-BCS crossover. The suppression of superfluidity at ωc2 is distinct in the BCS and BEC regimes, with the former controlled by depairing and the latter by the dilution of bosonic molecules. At low T and Ωz 〉 Ω⊥, in the BCS and crossover regimes of 0 δ δc, ωc2 is implicitly given by ωc22+Ω2 ≈ 2Δ Ω/F, vanishing as ωc2∼Ω (1-δ/δc)1/2 near δc 2F+γ2Fln(F/Ω) (with Δ the BCS gap and γ the resonance width), and extending the bulk result ωc2 2Δ2/ F to a trap. In the BEC regime of δωc2→Ω-, where molecular superfluidity is destroyed only by large quantum fluctuations associated with comparable boson and vortex densities. © 2006 The American Physical Society

Flow cytometry analysis of germinating Bacillus spores, using membrane potential dye

Germination of Bacillus anthracis spores is necessary for the transcription of plasmidic genes essential to the infection. Assessing germination potential is crucial to predict the risk associated with pathogenic Bacillus exposure. The aim of this study was to set up a viability assay based on membrane potential in order to predict the earliest germination event of spores. B. cereus and two strains of B. subtilis were used. The spores were isolated with a sodium bromide gradient. Approximately 107 spores were incubated at 37°C in tryptic soy broth (TSB). Aliquots were harvested at predetermined times and stained with 3,3'-dihexyloxacarbocyanine iodide [DiOC6(3)] or with bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)]. Fluorescence characteristics were obtained using flow cytometry. The earliest detectable activation of membrane potential occurred after 15 min of incubation in TSB using DiOC6(3). Using DiBAC4(3), the earliest detectable signal was after 4 h of incubation. Control experiments using carbonyl cyanide m-chlorophenylhydrazone (CCCP)-treated spores did not show any change in the fluorescence intensity over time. Since no membrane potential and no germination were detected in CCCP-treated spores, the activation of membrane potential seems to be associated with germination. DiOC6(3) can be used as an early membrane potential indicator for spores. DiBAC4(3), by contrast, is not a early membrane potential marker

Prenatal exposure to maternal cigarette smoking, amygdala volume, and fat intake in adolescence

Context : Prenatal exposure to maternal cigarette smoking is a well-established risk factor for obesity, but the underlying mechanisms are not known. Preference for fatty foods, regulated in part by the brain reward system, may contribute to the development of obesity. Objective : To examine whether prenatal exposure to maternal cigarette smoking is associated with enhanced fat intake and risk for obesity, and whether these associations may be related to subtle structural variations in brain regions involved in reward processing. Design : Cross-sectional study of a population-based cohort. Setting : The Saguenay Youth Study, Quebec, Canada. Participants : A total of 378 adolescents (aged 13 to 19 years; Tanner stage 4 and 5 of sexual maturation), half of whom were exposed prenatally to maternal cigarette smoking (mean [SD], 11.1 [6.8] cigarettes/d). Main Outcome Measures : Fat intake was assessed with a 24-hour food recall (percentage of energy intake consumed as fat). Body adiposity was measured with anthropometry and multifrequency bioimpedance. Volumes of key brain structures involved in reward processing, namely the amygdala, nucleus accumbens, and orbitofrontal cortex, were measured with magnetic resonance imaging. Results : Exposed vs nonexposed subjects exhibited a higher total body fat (by approximately 1.7 kg; P = .009) and fat intake (by 2.7%; P = .001). They also exhibited a lower volume of the amygdala (by 95 mm3; P < .001) but not of the other 2 brain structures. Consistent with its possible role in limiting fat intake, amygdala volume correlated inversely with fat intake (r = −0.15; P = .006). Conclusions : Prenatal exposure to maternal cigarette smoking may promote obesity by enhancing dietary preference for fat, and this effect may be mediated in part through subtle structural variations in the amygdala

The Worst Distortions of Astrometric Instruments and Orthonormal Models for Rectangular Fields of View

The non-orthogonality of algebraic polynomials of field coordinates traditionally used to model field-dependent corrections to astrometric measurements, gives rise to subtle adverse effects. In particular, certain field dependent perturbations in the observational data propagate into the adjusted coefficients with considerable magnification. We explain how the worst perturbation, resulting in the largest solution error, can be computed for a given non-orthogonal distortion model. An algebraic distortion model of full rank can be converted into a fully orthonormal model based on the Zernike polynomials for a circular field of view, or a basis of functions constructed from the original model by a variant of the Gram-Schmidt orthogonalization process for a rectangular field of view. The relative significance of orthonormal distortion terms is assessed simply by the numerical values of the corresponding coefficients. Orthonormal distortion models are easily extendable when the distribution of residuals indicate the presence of higher order terms.Comment: 1 figure; submitted in PAS

Mechanism-of-Action Determination of GMP Synthase Inhibitors and Target Validation in Candida albicans and Aspergillus fumigatus

SummaryMechanism-of-action (MOA) studies of bioactive compounds are fundamental to drug discovery. However, in vitro studies alone may not recapitulate a compound's MOA in whole cells. Here, we apply a chemogenomics approach in Candida albicans to evaluate compounds affecting purine metabolism. They include the IMP dehydrogenase inhibitors mycophenolic acid and mizoribine and the previously reported GMP synthase inhibitors acivicin and 6-diazo-5-oxo-L-norleucine (DON). We report important aspects of their whole-cell activity, including their primary target, off-target activity, and drug metabolism. Further, we describe ECC1385, an inhibitor of GMP synthase, and provide biochemical and genetic evidence supporting its MOA to be distinct from acivicin or DON. Importantly, GMP synthase activity is conditionally essential in C. albicans and Aspergillus fumigatus and is required for virulence of both pathogens, thus constituting an unexpected antifungal target

Membrane nanoclusters of FcγRI segregate from inhibitory SIRPα upon activation of human macrophages

Signal integration between activating Fc receptors and inhibitory signal regulatory protein α (SIRPα) controls macrophage phagocytosis. Here, using dual-color direct stochastic optical reconstruction microscopy, we report that Fcγ receptor I (FcγRI), FcγRII, and SIRPα are not homogeneously distributed at macrophage surfaces but are organized in discrete nanoclusters, with a mean radius of 71 ± 11 nm, 60 ± 6 nm, and 48 ± 3 nm, respectively. Nanoclusters of FcγRI, but not FcγRII, are constitutively associated with nanoclusters of SIRPα, within 62 ± 5 nm, mediated by the actin cytoskeleton. Upon Fc receptor activation, Src-family kinase signaling leads to segregation of FcγRI and SIRPα nanoclusters to be 197 ± 3 nm apart. Co-ligation of SIRPα with CD47 abrogates nanocluster segregation. If the balance of signals favors activation, FcγRI nanoclusters reorganize into periodically spaced concentric rings. Thus, a nanometer- and micron-scale reorganization of activating and inhibitory receptors occurs at the surface of human macrophages concurrent with signal integration

B7-H4 Treatment of T Cells Inhibits ERK, JNK, p38, and AKT Activation

B7-H4 is a newly identified B7 homolog that plays an important role in maintaining T-cell homeostasis by inhibiting T-cell proliferation and lymphokine-secretion. In this study, we investigated the signal transduction pathways inhibited by B7-H4 engagement in mouse T cells. We found that treatment of CD3+ T cells with a B7-H4.Ig fusion protein inhibits anti-CD3 elicited T-cell receptor (TCR)/CD28 signaling events, including phosphorylation of the MAP kinases, ERK, p38, and JNK. B7-H4.Ig treatment also inhibited the phosphorylation of AKT kinase and impaired its kinase activity as assessed by the phosphorylation of its endogenous substrate GSK-3. Expression of IL-2 is also reduced by B7-H4. In contrast, the phosphorylation state of the TCR proximal tyrosine kinases ZAP70 and lymphocyte-specific protein tyrosine kinase (LCK) are not affected by B7-H4 ligation. These results indicate that B7-H4 inhibits T-cell proliferation and IL-2 production through interfering with activation of ERK, JNK, and AKT, but not of ZAP70 or LCK

Resilience of benthic deep-sea fauna to mining activities

With increasing demand for mineral resources, extraction of polymetallic sulphides at hydrothermal vents, cobalt-rich ferromanganese crusts at seamounts, and polymetallic nodules on abyssal plains may be imminent. Here, we shortly introduce ecosystem characteristics of mining areas, report on recent mining developments, and identify potential stress and disturbances created by mining. We analyze species' potential resistance to future mining and perform meta-analyses on population density and diversity recovery after disturbances most similar to mining: volcanic eruptions at vents, fisheries on seamounts, and experiments that mimic nodule mining on abyssal plains. We report wide variation in recovery rates among taxa, size, and mobility of fauna. While densities and diversities of some taxa can recover to or even exceed pre-disturbance levels, community composition remains affected after decades. The loss of hard substrata or alteration of substrata composition may cause substantial community shifts that persist over geological timescales at mined sites. (C) 2017 Elsevier Ltd. All rights reserved.European Union Seventh Framework Programme (FP7) under the MIDAS project; FCT [IF/00029/2014/CP1230/CT0002, SFRH/ BPD/110278/2015]; Spanish RTD project NUREIEV [CTM2013-44598-R]; Ministry of Economy and Competitiveness [SGR 1068]; Generalitat de Catalunya autonomous government; European Union Horizon research and innovation programme [689518]; Fundacao para a Ciencia e a Tecnologia [UID/MAR/04292/2013]; German Ministry of Research (BMBF) [03F0707A-G]; Program Investigador FCT [IF/01194/2013/CP1199/CT0002]info:eu-repo/semantics/publishedVersio