Collisional properties of cold spin-polarized nitrogen gas: theory, experiment, and prospects as a sympathetic coolant for trapped atoms and molecules

We report a combined experimental and theoretical study of collision-induced dipolar relaxation in a cold spin-polarized gas of atomic nitrogen (N). We use buffer gas cooling to create trapped samples of 14N and 15N atoms with densities 5+/-2 x 10^{12} cm-3 and measure their magnetic relaxation rates at milli-Kelvin temperatures. Rigorous quantum scattering calculations based on accurate ab initio interaction potentials for the 7Sigma_u electronic state of N2 demonstrate that dipolar relaxation in N + N collisions occurs at a slow rate of ~10^{-13} cm3/s over a wide range of temperatures (1 mK to 1 K) and magnetic fields (10 mT to 2 T). The calculated dipolar relaxation rates are insensitive to small variations of the interaction potential and to the magnitude of the spin-exchange interaction, enabling the accurate calibration of the measured N atom density. We find consistency between the calculated and experimentally determined rates. Our results suggest that N atoms are promising candidates for future experiments on sympathetic cooling of molecules.Comment: 48 pages, 17 figures, 3 table

Electric generation of vortices in an exciton-polariton superfluid

We have theoretically demonstrated the on demand electric generation of vortices in an exciton-polariton superfluid. Electric pulses applied to a horseshoe-shaped metallic mesa, deposited on top of the microcavity, generate a non-cylindrically symmetric solitonic wave in the system. Breakdown of its wavefront at focal points leads to the formation of vortex-antivortex pairs which subsequently propagate in the superfluid. The trajectory of these vortex dipoles can be controlled by applying a voltage to additional electrodes. They can be confined within channels formed by metallic stripes and unbound by a wedged mesa giving birth to grey solitons. Finally single static vortices can be generated using a single metallic plate configuration.Comment: 7 pages and 7 figure

A case report: isolation of alysiella filiformis from pig"s lungs

Alysiella filiformis is considered a common resident in the oral cavities of many animals. All reports of Alysiella indicate that it is restricted to the oral cavity of warm-blooded vertebrates, where it apparently is nonpathogenic. However, increased losses of young pigs occured in one farm in Serbia. Spumous content in bronchia and partly clotted blood in blood vesels o f the lungs were present. Characteristic signs of oedema disease were present and E. coli serogroup 0139 was isolated. Furthermore, Alysiella filiformis was the single agent isolated from the lungs of diseased pigs. This is the first isolation of Alysiella filiformis from pig lungs

Reconstructing mass profiles of simulated galaxy clusters by combining Sunyaev-Zeldovich and X-ray images

We present a method to recover mass profiles of galaxy clusters by combining data on thermal Sunyaev-Zeldovich (tSZ) and X-ray imaging, thereby avoiding to use any information on X-ray spectroscopy. This method, which represents a development of the geometrical deprojection technique presented in Ameglio et al. (2007), implements the solution of the hydrostatic equilibrium equation. In order to quantify the efficiency of our mass reconstructions, we apply our technique to a set of hydrodynamical simulations of galaxy clusters. We propose two versions of our method of mass reconstruction. Method 1 is completely model-independent, while Method 2 assumes instead the analytic mass profile proposed by Navarro et al. (1997) (NFW). We find that the main source of bias in recovering the mass profiles is due to deviations from hydrostatic equilibrium, which cause an underestimate of the mass of about 10 per cent at r_500 and up to 20 per cent at the virial radius. Method 1 provides a reconstructed mass which is biased low by about 10 per cent, with a 20 per cent scatter, with respect to the true mass profiles. Method 2 proves to be more stable, reducing the scatter to 10 per cent, but with a larger bias of 20 per cent, mainly induced by the deviations from equilibrium in the outskirts. To better understand the results of Method 2, we check how well it allows to recover the relation between mass and concentration parameter. When analyzing the 3D mass profiles we find that including in the fit the inner 5 per cent of the virial radius biases high the halo concentration. Also, at a fixed mass, hotter clusters tend to have larger concentration. Our procedure recovers the concentration parameter essentially unbiased but with a scatter of about 50 per cent.Comment: 13 pages, 11 figures, submitted to MNRA

Examining associations Between School-Level Determinants and the Implementation of Physical activity Opportunities

School-based physical activity (PA) opportunities can help students engage in greater amounts of daily PA, meet PA guidelines, and lead to improved health and educational outcomes. However, we do not completely understand the organizational challenges to implementing these opportunities successfully. This exploratory study examined associations between school-level determinants and the implementation of school-based PA opportunities. We analyzed cross-sectional survey data from schools (n = 46) participating in the Healthy Zone School Program (HZSP) (Dallas, Texas, USA) during 2019-2020. Respondents completed an electronic survey that included measures of school-level determinants (e.g. culture, leadership, priority) and the implementation of school-based PA opportunities. We used linear regression models to examine associations between determinants and implementation outcomes (number of PA opportunities delivered, perceived overall success of each PA program/activity used). After adjusting for campus type (i.e. elementary, middle, high, K-12), student race/ethnicity, and percentage of economically disadvantaged students, no constructs were associated with the number of PA opportunities implemented. Linear regression models suggest access to knowledge and information (β = 0.39, P = .012, 95% CI = 0.24-1.44) and implementation climate (β = 0.34, P = .045, 95% CI = 0.02-1.59) were positively associated with the success of school-based PA opportunities. Our findings provide suggestive evidence that access to knowledge and information and a supportive school climate may improve the overall success of PA opportunities provided to students. Future research should examine additional school-level determinants to understand their importance to implementation and inform the development of strategies to improve schools\u27 capacity for implementing PA opportunities successfully

Bacterial Porin Disrupts Mitochondrial Membrane Potential and Sensitizes Host Cells to Apoptosis

The bacterial PorB porin, an ATP-binding beta-barrel protein of pathogenic Neisseria gonorrhoeae, triggers host cell apoptosis by an unknown mechanism. PorB is targeted to and imported by host cell mitochondria, causing the breakdown of the mitochondrial membrane potential (Delta psi(m)). Here, we show that PorB induces the condensation of the mitochondrial matrix and the loss of cristae structures, sensitizing cells to the induction of apoptosis via signaling pathways activated by BH3-only proteins. PorB is imported into mitochondria through the general translocase TOM but, unexpectedly, is not recognized by the SAM sorting machinery, usually required for the assembly of beta-barrel proteins in the mitochondrial outer membrane. PorB integrates into the mitochondrial inner membrane, leading to the breakdown of Delta psi(m). The PorB channel is regulated by nucleotides and an isogenic PorB mutant defective in ATP-binding failed to induce Delta psi(m) loss and apoptosis, demonstrating that dissipation of Delta psi(m) is a requirement for cell death caused by neisserial infection

Vibration and buckling of thin-walled composite I-beams with arbitrary lay-ups under axial loads and end moments

A finite element model with seven degrees of freedom per node is developed to study vibration and buckling of thin-walled composite I-beams with arbitrary lay-ups under constant axial loads and equal end moments. This model is based on the classical lamination theory, and accounts for all the structural coupling coming from material anisotropy. The governing differential equations are derived from the Hamilton’s principle. Numerical results are obtained for thin-walled composite I-beams to investigate the effects of axial force, bending moment and fiber orientation on the buckling moments, natural frequencies, and corresponding vibration mode shapes as well as axial-moment-frequency interaction curves

Bacterial porin disrupts mitochondrial membrane potential and sensitizes host cells to apoptosis

The bacterial PorB porin, an ATP-binding beta-barrel protein of pathogenic Neisseria gonorrhoeae, triggers host cell apoptosis by an unknown mechanism. PorB is targeted to and imported by host cell mitochondria, causing the breakdown of the mitochondrial membrane potential (delta psi m). Here, we show that PorB induces the condensation of the mitochondrial matrix and the loss of cristae structures, sensitizing cells to the induction of apoptosis via signaling pathways activated by BH3-only proteins. PorB is imported into mitochondria through the general translocase TOM but, unexpectedly, is not recognized by the SAM sorting machinery, usually required for the assembly of beta-barrel proteins in the mitochondrial outer membrane. PorB integrates into the mitochondrial inner membrane, leading to the breakdown of delta psi m. The PorB channel is regulated by nucleotides and an isogenic PorB mutant defective in ATP-binding failed to induce delta psi m loss and apoptosis, demonstrating that dissipation of delta psi m is a requirement for cell death caused by neisserial infection

A Search for Electron Antineutrino Appearance at the Δm2∼\Delta m^2 \sim 1 eV2\mathrm{eV}^{2} Scale

The MiniBooNE Collaboration reports initial results from a search for $\bar{\nu}_{\mu}\to\bar{\nu}_e$ oscillations. A signal-blind analysis was performed using a data sample corresponding to $3.39 \times 10^{20}$ protons on target. The data are consistent with background prediction across the full range of neutrino energy reconstructed assuming quasielastic scattering, $200 < E_{\nu}^{QE} < 3000$ MeV: 144 electron-like events have been observed in this energy range, compared to an expectation of $139.2 \pm 17.6$ events. No significant excess of events has been observed, both at low energy, 200-475 MeV, and at high energy, 475-1250 MeV. The data are inconclusive with respect to antineutrino oscillations suggested by data from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.Comment: 5 pages, 3 figures, 2 table