2,795 research outputs found

    Analysis of debris from Spacelab Space Life Sciences-1

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    Airborne microbiological and particulate contamination generated aboard Spacelab modules is a potential safety hazard. In order to shed light on the characteristics of these contaminants, microbial and chemical/particulate analyses were performed on debris vacuumed from cabin and avionics air filters in the Space Life Sciences-1 (SLS-1) module of the Space Transportation System 40 (STS-40) mission 1 month after landing. The debris was sorted into categories (e.g., metal, nonmetal, hair/fur, synthetic fibers, food particles, insect fragments, etc.). Elemental analysis of particles was done by energy dispersive analysis of x rays (metals) and Fourier transform infrared spectroscopy (nonmetals). Scanning electron micrographs were done of most particles. Microbiological samples were grown on R2A culture medium and identified. Clothing fibers dominated the debris by volume. Other particles, all attributed to the crew, resulted from abrasions and impacts during missions operations (e.g., paint chips, plastic, electronic scraps and clothing fibers). All bacterial species identified are commonly found in the atmosphere or on the human body. Bacillus sp. was the most frequently seen bacterium. One of the bacterial species, Enterobacter agglomerans, could cause illness in crew members with depressed immune systems

    Stretched exponentials and power laws in granular avalanching

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    We introduce a model for granular avalanching which exhibits both stretched exponential and power law avalanching over its parameter range. Two modes of transport are incorporated, a rolling layer consisting of individual particles and the overdamped, sliding motion of particle clusters. The crossover in behaviour observed in experiments on piles of rice is attributed to a change in the dominant mode of transport. We predict that power law avalanching will be observed whenever surface flow is dominated by clustered motion. Comment: 8 pages, more concise and some points clarified

    Improved u′g′r′i′z′u'g'r'i'z' to UBVRCICUBVR_CI_C Transformation Equations for Main Sequence Stars

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    We report improved transformation equations between the u′g′r′i′z′u'g'r'i'z' and UBVRCICUBVR_CI_C photometric systems. Although the details of the transformations depend on luminosity class, we find a typical rms scatter on the order of 0.001 magnitude if the sample is limited to main sequence stars. Furthermore, we find an accurate transformation requires complex, multi-color dependencies for the bluer bandpasses. Results for giant stars will be reported in a subsequent paper.Comment: 7 pages, 8 figure

    Particle detection experiment for Applications Technology Satellite 1 /ATS-1/ Final report

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    Applications technology satellite particle detection experiment for measuring energy spectra of earth magnetic fiel

    A Numerical Study of the Hierarchical Ising Model: High Temperature Versus Epsilon Expansion

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    We study numerically the magnetic susceptibility of the hierarchical model with Ising spins (σ=±1\sigma =\pm 1) above the critical temperature and for two values of the epsilon parameter. The integrations are performed exactly, using recursive methods which exploit the symmetries of the model. Lattices with up to 2182^18 sites have been used. Surprisingly, the numerical data can be fitted very well with a simple power law of the form (1−β/βc)−γ(1- \beta /\beta _c )^{- \gamma} for the {\it whole} temperature range. The numerical values for γ\gamma agree within a few percent with the values calculated with a high-temperature expansion but show significant discrepancies with the epsilon-expansion. We would appreciate comments about these results.Comment: 15 Pages, 12 Figures not included (hard copies available on request), uses phyzzx.te

    Rotationally invariant family of L\'evy like random matrix ensembles

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    We introduce a family of rotationally invariant random matrix ensembles characterized by a parameter λ\lambda. While λ=1\lambda=1 corresponds to well-known critical ensembles, we show that λ≠1\lambda \ne 1 describes "L\'evy like" ensembles, characterized by power law eigenvalue densities. For λ>1\lambda > 1 the density is bounded, as in Gaussian ensembles, but λ<1\lambda <1 describes ensembles characterized by densities with long tails. In particular, the model allows us to evaluate, in terms of a novel family of orthogonal polynomials, the eigenvalue correlations for L\'evy like ensembles. These correlations differ qualitatively from those in either the Gaussian or the critical ensembles.Comment: 9 pages, 5 figure

    Stellar Archaeology in the Galactic halo with the Ultra-Faint Dwarfs: VI. Ursa Major II

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    We present a B, V color-magnitude diagram (CMD) of the Milky Way dwarf satellite Ursa Major II (UMa II), spanning the magnitude range from V ~ 15 to V ~ 23.5 mag and extending over a 18 {\times} 18 arcmin2 area centered on the galaxy. Our photometry goes down to about 2 magnitudes below the galaxy's main sequence turn-off, that we detected at V ~ 21.5 mag. We have discovered a bona-fide RR Lyrae variable star in UMa II, which we use to estimate a conservative dereddened distance modulus for the galaxy of (m-M)0 = 17.70{\pm}0.04{\pm}0.12 mag, where the first error accounts for the uncertainties of the calibrated photometry, and the second reflects our lack of information on the metallicity of the star. The corresponding distance to UMa II is 34.7 {\pm} 0.6 ({\pm} 2.0) kpc. Our photometry shows evidence of a spread in the galaxy subgiant branch, compatible with a spread in metal abundance in the range between Z=0.0001 and Z=0.001. Based on our estimate of the distance, a comparison of the fiducial lines of the Galactic globular clusters (GCs) M68 and M5 ([Fe/H]=-2.27 {\pm} 0.04 dex and -1.33 {\pm} 0.02 dex, respectively), with the position on the CMD of spectroscopically confirmed galaxy members, may suggest the existence of stellar populations of different metal abundance/age in the central region of UMa II.Comment: To appear in Ap

    Procedures for A Comparison of Electronic and Paper Versions of the Montreal Cognitive Assessment

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    Objective: To investigate older adults’ performance on the paper and electronic Montreal Cognitive Assessment (MoCA). We hypothesized the paper MoCA scores would be significantly higher than electronic MoCA (eMoCA) scores. Design: Repeated measures and correlational design. Setting: General community and university clinic. Participants: A convenience sample of 40 adults over 65 years of age living in the community. Interventions: Participants completed the eMoCA and paper MoCA in a randomized order during a single session. Participants reported their touchscreen experience and comfort, and indicated their administration modality preferences. Main Outcome Measures: The primary outcome measures were Paper MoCA and eMoCA total and subscale scores. Secondary outcome measures included participants reported touchscreen experience and comfort, as well as post administration preferences. Results: A moderate statistically significant correlation was found between performance on the eMoCA and the paper MoCA across all participants. Analysis comparing first administration modality only (eMoCA versus paper MoCA) found that there was not a statistically significant difference in total scores, however there was a statistically significant difference for the visuospatial/executive subscale, which required the test taker to physically interact with either the paper or the tablet. Across all subjects, there was a statistically significant correlation between experience with touchscreen devices and performance on the eMoCA, but not between modality preference and performance. Conclusion: Modality of administration can impact performance on assessments of cognition. Clinicians should consider the amount of experience with touchscreens prior to deciding which modality to use with a client
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