346 research outputs found

    The structure of triphenylgermanium hydroxide

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    C18H~6GeO, Mr = 320.9, triclinic, Pi, a = 15.408 (6), b = 19.974 (7), c = 23.264 (11) A, a = 107.78 (4), 13 = 1.03.54 (4), y= 101.51 (3) °, V = 6338 (5)/~3, Z = 16, Dx = 1.34 g cm -3, a(Mo Ka) = 0.71073A, /z = 19.1cm-1, F(000)=2624, T= 293 K, R = 0.055 for 6846 observed reflections. The eight independent molecules in the asymmetric unit form two independent O--H...O hydrogen-bonded tetramers with the O atoms in a flattened tetrahedral arrangement [hydrogen-bond distances in the range 2.609 (11) to 2.657 (11)A]. The Ge atoms are tetrahedrally coordinated with mean Gc O 1.791 (7) and Gc C 1.931 (8) A

    College-Readiness Differences by Economic Status of Texas High School Students With a Learning Disability: A Statewide Multiyear Investigation

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    The extent to which differences were present in college-readiness rates in reading mathematics and both subjects by economic status for students who were Learning Disabled in Texas public high schools for 2008-2009 through 2010-2011 school years were analyzed in this study Archival data were obtained from the Texas Education Agency Public Education Information Management System on all high school students who were diagnosed as being Learning Disabled Statistically significant differences in reading mathematics and both subjects college-readiness were present for all three school years Extremely low college-readiness rates were present in reading mathematics and both subjects for students who were Learning Disabled in the 2008-2009 through the 2010-2011 school year

    A Flight Evaluation of an Airborne Physiological Instrumentation System, Including Preliminary Results Under Conditions of Varying Accelerations

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    A physiological instrumentation system capable of recording the electrocardiogram, pulse rate, respiration rate, and systolic and diastolic blood pressures during flight has been developed. This instrumentation system was designed for use during control studies at varied levels of acceleration in order to monitor the well-being of the pilot and at the same time to obtain data for study of the relationships between his various physiological functions and his performance capability. Flights, made in a T-33 aircraft, demonstrated the ability of the system to obtain the desired physiological data in flight. The data obtained in these flights, although limited in nature, indicate a slowing of the pulse rate under the subgravity conditions of brief duration. There appeared to be a proportional nearly in-phase relationship between pulse rate and acceleration. A decrease in diastolic blood pressure together with an increase in pulse pressure was noted during subgravity conditions and an elevation of the diastolic pressure together with a decrease in pulse pressure du-ring increased accelerations. No change worthy of note was seen in the records of the systolic blood pressure, the respiration rate, or the electrocardiogram over the range of acceleration studied (0 to 3 g)

    Exposure of Salmonella biofilms to antibiotic concentrations rapidly selects resistance with collateral tradeoffs

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    Most bacteria in nature exist in biofilms, which are inherently tolerant to antibiotics. There is currently very limited understanding of how biofilms evolve in response to sub-lethal concentrations of antimicrobials. In this study, we use a biofilm evolution model to study the effects of sub-inhibitory concentrations of three antibiotics on Salmonella Typhimurium biofilms. We show that biofilms rapidly evolve resistance to each antibiotic they are exposed to, demonstrating a strong selective pressure on biofilms from low antibiotic concentrations. While all antibiotics tested select for clinical resistance, there is no common mechanism. Adaptation to antimicrobials, however, has a marked cost for other clinically important phenotypes, including biofilm formation and virulence. Cefotaxime selects mutants with the greatest deficit in biofilm formation followed by azithromycin and then ciprofloxacin. Understanding the impacts of exposure of biofilms to antibiotics will help understand evolutionary trajectories and may help guide how best to use antibiotics in a biofilm context. Experimental evolution in combination with whole-genome sequencing is a powerful tool for the prediction of evolution trajectories associated with antibiotic resistance in biofilms

    Strong Lensing Analysis of A1689 from Deep Advanced Camera Images

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    We analyse deep multi-colour Advanced Camera images of the largest known gravitational lens, A1689. Radial and tangential arcs delineate the critical curves in unprecedented detail and many small counter-images are found near the center of mass. We construct a flexible light deflection field to predict the appearance and positions of counter-images. The model is refined as new counter-images are identified and incorporated to improve the model, yielding a total of 106 images of 30 multiply lensed background galaxies, spanning a wide redshift range, 1.0<<z<<5.5. The resulting mass map is more circular in projection than the clumpy distribution of cluster galaxies and the light is more concentrated than the mass within r<50kpc/hr<50kpc/h. The projected mass profile flattens steadily towards the center with a shallow mean slope of dlogΣ/dlogr0.55±0.1d\log\Sigma/d\log r \simeq -0.55\pm0.1, over the observed range, r<250kpc/h<250kpc/h, matching well an NFW profile, but with a relatively high concentration, Cvir=8.21.8+2.1C_{vir}=8.2^{+2.1}_{-1.8}. A softened isothermal profile (rcore=20±2r_{core}=20\pm2\arcs) is not conclusively excluded, illustrating that lensing constrains only projected quantities. Regarding cosmology, we clearly detect the purely geometric increase of bend-angles with redshift. The dependence on the cosmological parameters is weak due to the proximity of A1689, z=0.18z=0.18, constraining the locus, ΩM+ΩΛ1.2\Omega_M+\Omega_{\Lambda} \leq 1.2. This consistency with standard cosmology provides independent support for our model, because the redshift information is not required to derive an accurate mass map. Similarly, the relative fluxes of the multiple images are reproduced well by our best fitting lens model.Comment: Accepted by ApJ. For high quality figures see http://wise-obs.tau.ac.il/~kerens/A168

    A Measurement of the Correlation of Galaxy Surveys with CMB Lensing Convergence Maps from the South Pole Telescope

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    We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, WISE, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 deg^2 of sky, we detect a correlation between the SPT convergence maps and each of the galaxy density maps at >4σ, with zero correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 deg^2 SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe

    The motivations of external whistleblowers and their impact on the intention to blow the whistle again

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    The purpose of this study was to inquire into the relative importance of morality, cost‐benefit, and emotion as motivations for the decision to blow the whistle externally, and the effects of such factors as motivations, perceived negative consequences, and preferences for reform on the intention to blow the whistle again. Based on a literature review, we formulated some hypotheses and, to test them, we used the data collected from a survey of 127 external whistleblowers in South Korea. The results revealed that morality was the most important motivation, followed by emotion, and then cost‐benefit, which thus, seemed to be the least important for the whistleblowers. Morality as a motivation and the perceived negative consequences of whistleblowing had a significant effect on the intention to blow the whistle again. This study helps advance the understanding of the motivations behind whistleblowing and the factors that influence the intention to blow the whistle again

    Reproductive aspects of the oceanic whitetip shark, Carcharhinus longimanus (Elasmobranchii: Carcharhinidae), in the equatorial and southwestern Atlantic Ocean

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    The present study sought to study the reproductive biology of the oceanic whitetip shark, Carcharhinus longimanus, in the equatorial and southwestern Atlantic Ocean. A total of 234 specimens were collected as bycatch during pelagic longline fisheries targeting tunas and swordfish, between December 2003 and December 2010. The fishing area was located between latitudes 10N and 35S and longitudes 3E and 40W. Of the 234 individuals sampled, 118 were females (with sizes ranging from 81 to 227 cm TL, total length) and 116 males (ranging from 80 to 242 cm TL). The reproductive stages of the females were classed as immature, mature, preovulatory and pregnant, while males were divided into immature, maturing and mature. The size at maturity for females was estimated at 170.0 cm TL, while that for males was between 170.0 and 190.0 cm TL. Ovarian fecundity ranged from 1 to 10 follicles and uterine fecundity from 1 to 10 embryos. The reproductive cycle of this species is most likely biennial, with parturition occurring once every two years.info:eu-repo/semantics/publishedVersio
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