1,980 research outputs found

    The Case For Sequencing The Pacific Oyster Genome

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    An international community of biologists presents the Pacific oyster Crassostrea gigas as a candidate for genome sequencing. This oyster has global distribution and for the past several years the highest annual production of any freshwater or marine organism (4.2 million metric tons, worth $3.5 billion US). Economic and cultural importance of oysters motivates a great deal of biologic research, which provides a compelling rationale for sequencing an oyster genome. Strong rationales for sequencing the oyster genome also come from contrasts to other genomes: membership in the Lophotrochozoa, an understudied branch of the Eukaryotes and high fecundity, with concomitantly high DNA sequence polymorphism and a population biology that is more like plants than any of the model animals whose genomes have been sequenced to date. Finally, oysters play an important, sentinel role in the estuarine and coastal marine habitats, where most humans live, environmental degradation is substantial, and oysters suffer intense fishing pressures and natural mortalities from disease and stress. Consumption of contaminated oysters can pose risks to human health from infectious diseases. The genome of the Pacific oyster, at IC = 0.89 pg or similar to 824 Mb, ranks in the bottom 12% of genome sizes for the Phylum Mollusca. The biologic and genomic resources available for the Pacific oyster are unparalleled by resources for any other bivalve mollusc or marine invertebrate. Inbred lines have been developed for experimental crosses and genetics research. Use of DNA from inbred lines is proposed as a strategy for reducing the high nucleotide polymorphism, which can interfere with shotgun sequencing approaches. We have moderately dense linkage maps and various genomic and expressed DNA libraries. The value of these existing resources for a broad range of evolutionary and environmental sciences will be greatly leveraged by having a draft genome sequence

    Grain Dynamics in a Two-dimensional Granular Flow

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    We have used particle tracking methods to study the dynamics of individual balls comprising a granular flow in a small-angle two-dimensional funnel. We statistically analyze many ball trajectories to examine the mechanisms of shock propagation. In particular, we study the creation of, and interactions between, shock waves. We also investigate the role of granular temperature and draw parallels to traffic flow dynamics.Comment: 17 pages, 24 figures. To appear in Phys.Rev.E. High res./color figures etc. on http://www.nbi.dk/CATS/Granular/GrainDyn.htm

    Clustering, Order, and Collapse in a Driven Granular Monolayer

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    Steady state dynamics of clustering, long range order, and inelastic collapse are experimentally observed in vertically shaken granular monolayers. At large vibration amplitudes, particle correlations show only short range order like equilibrium 2D hard sphere gases. Lowering the amplitude "cools" the system, resulting in a dramatic increase in correlations leading either to clustering or an ordered state. Further cooling forms a collapse: a condensate of motionless balls co-existing with a less dense gas. Measured velocity distributions are non-Gaussian, showing nearly exponential tails.Comment: 9 pages of text in Revtex, 5 figures; references added, minor modifications Paper accepted to Phys Rev Letters. Tentatively scheduled for Nov. 9, 199

    The Importance of Time Congruity in the Organisation.

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    In 1991 Kaufman, Lane, and Lindquist proposed that time congruity in terms of an individual's time preferences and the time use methods of an organisation would lead to satisfactory performance and enhancement of quality of work and general life. The research reported here presents a study which uses commensurate person and job measures of time personality in an organisational setting to assess the effects of time congruity on one aspect of work life, job-related affective well-being. Results show that time personality and time congruity were found to have direct effects on well-being and the influence of time congruity was found to be mediated through time personality, thus contributing to the person–job (P–J) fit literature which suggests that direct effects are often more important than indirect effects. The study also provides some practical examples of ways to address some of the previously cited methodological issues in P–J fit research

    Human resource management–well‐being–performance research revisited:Past, present, and future

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    The authors provide an up‐to‐date theoretically based qualitative review of research dealing with the relationship between HRM, employee well‐being, and individual/organisational performance (HRM‐WB‐IOP research). The review is based on a systematic critical analysis of all HRM‐WB‐IOP studies (N = 46) published in 13 core HRM and management journals in the 2000 to 2018 period. The authors first identify different theoretical models of the HRM‐WB‐IOP relationship, which they then use to map research in the area. The results show that mutual gains conceptualisations play a dominant role in extant HRM‐WB‐IOP research, at the expense of alternative conflicting outcomes and mutual losses models, which are also shown to receive very limited empirical support across the 46 studies. As part of this mapping exercise, the authors identify important knowledge gaps in the area and conclude by setting out a number of key recommendations for future research to address these gaps

    Do divorcing couples become happier by breaking up?

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    Divorce is a leap in the dark. The paper investigates whether people who split up actually become happier. Using the British Household Panel Survey, we can observe an individual's level of psychological well-being in the years before and after divorce. Our results show that divorcing couples reap psychological gains from the dissolution of their marriages. Men and women benefit equally. The paper also studies the effects of bereavement, of having dependant children and of remarriage. We measure well-being by using general health questionnaire and life satisfaction scores

    First identification of large electric monopole strength in well-deformed rare earth nuclei

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    Excited states in the well-deformed rare earth isotopes 154^{154}Sm and 166^{166}Er were populated via ``safe'' Coulomb excitation at the Munich MLL Tandem accelerator. Conversion electrons were registered in a cooled Si(Li) detector in conjunction with a magnetic transport and filter system, the Mini-Orange spectrometer. For the first excited 0+0^+ state in 154^{154}Sm at 1099 keV a large value of the monopole strength for the transition to the ground state of ρ2(E0;02+→0g+)=96(42)⋅10−3\rho^2(\text{E0}; 0^+_2 \to 0^+_\text{g}) = 96(42)\cdot 10^{-3} could be extracted. This confirms the interpretation of the lowest excited 0+0^+ state in 154^{154}Sm as the collective β\beta-vibrational excitation of the ground state. In 166^{166}Er the measured large electric monopole strength of ρ2(E0;04+→01+)=127(60)⋅10−3\rho^2(\text{E0}; 0^+_4 \to 0^+_1) = 127(60)\cdot 10^{-3} clearly identifies the 04+0_4^+ state at 1934 keV to be the β\beta-vibrational excitation of the ground state.Comment: submitted to Physics Letters

    Steady state properties of a driven granular medium

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    We study a two-dimensional granular system where external driving force is applied to each particle in the system in such a way that the system is driven into a steady state by balancing the energy input and the dissipation due to inelastic collision between particles. The velocities of the particles in the steady state satisfy the Maxwellian distribution. We measure the density-density correlation and the velocity-velocity correlation functions in the steady state and find that they are of power-law scaling forms. The locations of collision events are observed to be time-correlated and such a correlation is described by another power-law form. We also find that the dissipated energy obeys a power-law distribution. These results indicate that the system evolves into a critical state where there are neither characteristic spatial nor temporal scales in the correlation functions. A test particle exhibits an anomalous diffusion which is apparently similar to the Richardson law in a three-dimensional turbulent flow.Comment: REVTEX, submitted to Phys. Rev.
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