346 research outputs found
The structure of triphenylgermanium hydroxide
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
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
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)
Instrumentation and Calibration Technique for Flight Calibration of Angle-of-attack Systems on Aircraft
Exposure of Salmonella biofilms to antibiotic concentrations rapidly selects resistance with collateral tradeoffs
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
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, 1.0z5.5. 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 . The projected mass profile
flattens steadily towards the center with a shallow mean slope of
, over the observed range,
r, matching well an NFW profile, but with a relatively high
concentration, . A softened isothermal profile
(\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, , constraining the locus, .
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
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
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
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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