274 research outputs found
Employee Satisfaction And Shareholder Returns
We hypothesize that satisfied employees lead to higher returns for shareholders. In particular, we investigate whether inclusion on Fortune magazine’s list of “100 Best Companies to Work For” leads to increases in wealth for shareholders. We find no announcement effect associated with the list release date. Although we do find that a subset of firms named to the list in one year generate higher returns (than a matched sample) the following year, we conclude that, ex ante, investors would be unable to consistently profit from any information provided by inclusion on the list. Tests of returns of companies that are dropped from the Fortune list indicate no abnormal performance
A Comparison of Solar Wind and Estimated Solar System Xenon Abundances: A Test for Solid/ Gas Fractionation in the Solar Nebula
Significant fractionation of dust/gas from the original interstellar cloud during the formation of the solar system is a distinct possibility. Identification of such an effect would provide important clues to nebular processes. Fractionation of volatiles is not constrained by CI abundances and only for the most abundant ones by photospheric observations. The solar Xe elemental abundance is determined here via solar wind measurements from lunar ilmenites and normalized to Si by spacecraft data. The results are compared with estimated abundances assuming no fractionation, which are relatively well constrained
for Xe by s-process calculations, odd-mass abundance interpolations, and odd-even abundance systematics.
When corrected for solar wind/photospheric fractionation, the ^(130)Xe abundance given by surface layer oxidation of ilmenite from soil 71501, exposed within the last - 200 m.y., is 0.24 ± 0.09 normalized to Si = 10^6. This is indistinguishable from the estimates made assuming no solid/gas fractionation. A similar result was obtained for Kr by Wiens et al (1991). Results from breccia 79035 ilmenite, exposed at least ~1 Gy ago, indicate that the solar wind Xe flux may have been significantly higher relative to other noble gases, perhaps due to more efficient Xe ionization. If this is true, fluxes of C and S, which have similar first ionization potentials to Xe, should also be higher in the ancient solar wind from the
same time period, though such variations have not been observed
Genesis capsule yields solar wind samples
NASA's Genesis capsule, carrying the first samples ever returned from beyond the Moon, took a hard landing in the western Utah desert on 8 September after its parachutes failed to deploy Despite the impact, estimated at 310 km per hour, some valuable solar wind collector materials have been recovered. With these samples, the Genesis team members are hopeful that nearly all of the primary science goals may be met.
The Genesis spacecraft was launched in August 2001 to collect and return samples of solar wind for precise isotopic and elemental analysis. The spacecraft orbited the Earth-Sun Lagrangian point (LI), ˜1.5 million km sunward of Earth, for 2.3 years. It exposed ultrapure materials—including wafers of silicon, silicon carbide, germanium, chemically deposited diamond, gold, aluminum, and metallic glass— to solar wind ions, which become embedded within the substrates' top 100 nm of these materials
Bipolar risk and mental imagery susceptibility in a representative sample of Chinese adults residing in the community
BACKGROUND: We need to better understand the cognitive factors associated with risk for bipolar disorders. Recent research suggests that increased susceptibility to mental imagery may be one such factor. However, since this research was primarily conducted with Western students and at a single time-point, it is not known whether the relationship between imagery susceptibility and bipolar symptoms exists across cultures or within the general community, or whether this relationship remains stable over time. AIM: This study evaluated whether Chinese adults identified as being at high (HR) versus low (LR) risk of developing bipolar disorders showed greater mental imagery susceptibility. We aimed to test whether such a relationship was stable over time by measuring imagery characteristics at baseline and at the 7-week follow-up. METHOD: This prospective study recruited a community sample of N = 80 Chinese adults screened for the absence of neurotic and psychotic disorders. The sample was split into HR (n = 18) and LR (n = 62) groups at baseline based on a criterion cut-off score on a measure of hypomania, the Mood Disorder Questionnaire (MDQ). Participants completed measures of imagery susceptibility and its impact: the Spontaneous Use of Imagery Scale (SUIS) and the Impact of Future Events Scale (IFES), at baseline and 7 weeks later. RESULTS: HR group reported greater tendency to use imagery in daily life (SUIS) and greater emotional impact of prospective imagery (IFES) than LR group at baseline. These results remained stable at follow-up. CONCLUSION: This study provides preliminary evidence for increased susceptibility to mental imagery in individuals at high risk of bipolar disorders recruited from a community sample of Chinese adults. This extends previous research in Western student samples suggesting that imagery (both levels of use and its emotional impact) may be a cognitive factor with cross-cultural relevance that is stable over time
Acute Effects of Ambient Particulate Matter on Mortality in Europe and North America: Results from the APHENA Study
Structure of the semiquinone form of flavodoxin from Clostridium MP : Extension of 1.8 A resolution and some comparisons with the oxidized state
As part of a series of comparisons of the structures of the three oxidation states of flavodoxin from Clostridium MP, phases for the semiquinono form were determined to 2.0 A resolution by isomorphous replacement (m > = 0.725). Subsequently, the structure was refined at 1.8 A resolution by a combination of difference Fourier, real space and reciprocal space methods. After refining to an R of 0.194, we explored the conformation of the FMN binding site by real space refinement versus maps with Fourier coefficients of the form (2|Fo|- |Fc|) exp (i[alpha]c). To minimize bias in the fitting, groups of atoms were systematically omitted from the structure factors used in computation of the (2|Fo - |Fc|) maps.One-electron reduction of oxidized flavodoxin is accompanied by several changes at the FMN binding site: the conformation of residues in the reverse bend formed by Met56-Gly57-Asp58-Glu59 differs in the crystal structures of the oxidized and semiquinone species; further, backbone atoms in residues 55 and 89 shift by more than 0.5 A and the indole ring of Trp90 undergoes a significant displacement. The orientation of the peptide unit connecting Gly57 and Asp58 is consistent with the presence of a hydrogen bond between the carbonyl oxygen of Gly57 and the flavin N(5) in flavodoxin semiquinone. No equivalent bond is found in oxidized flavodoxin. In both the oxidized and semiquinone species of clostridial flavodoxin, the isoalloxazine ring is essentially planar : the bending angles about N(5)---N(10) are ~2.5 [deg] for the semiquinone structure and ~0 [deg] in oxidized flavodoxin.The intensity changes resulting from the oxidized agsemiquinone conversion (RI = 0.33) arise in part from changes in molecular packing. Intermolecular contacts, including neighbors of the prosthetic group, are altered in the repacking. Maps or models of the two oxidation states can be brought into approximate coincidence by a rigid body motion. The required transformation, determined for the isomorphous replacement maps by the method of Cox (1967), is equivalent to a screw motion with a rotation of 1.18 [deg] and a translation of -0.34 A. The molecular structures of oxidized and semiquinone flavodoxins have been compared after superposition of models with idealized co-ordinates and discrepancy indices Rox = 0.213 and Rsq = 0.200. The root-mean-square distance between 523 backbone atoms (excluding sequences 56 to 59 and 89 to 91) is 0.308 A.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22809/1/0000366.pd
Constraints on Neon and Argon Isotopic Fractionation in Solar Wind
To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in ^(20)Ne/^(22)Ne or ^(36)Ar/^(38)Ar values. For ^(20)Ne/^(22)Ne, the difference between low- and high-speed wind components is 0.24 ± 0.37%; for ^(36)Ar/^(38)Ar, it is 0.11 ± 0.26%. Our measured ^(36)Ar/^(38)Ar ratio in the solar wind of 5.501 ± 0.005 is 3.42 ± 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history
Genesis Mission to Return Solar Wind Samples to Earth
The Genesis spacecraft, launched on 8 August 2001 from Cape Canaveral, Florida, will be the first spacecraft ever to return from interplanetary space. The fifth in NASAs line of low-cost, Discovery-class missions, its goal is to collect samples of solar wind and return them to Earth for detailed isotopic and elemental analysis. The spacecraft is to collect solar wind for over 2 years, while circling the L1 point 1.5 million km Sunward of the Earth, before heading back for a capsule-style re-entry in September 2004. After parachute deployments mid-air helicopter recovery will be used to avoid a hard landing. The mission has been in development over 10 years, and its cost, including development, mission operations, and initial sample analysis, is approximately $209 million
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