19,454 research outputs found

    Taxonomy of \u3cem\u3eStreptanthus\u3c/em\u3e sect. \u3cem\u3eBiennes\u3c/em\u3e, the \u3cem\u3eStreptanthus morrisonii\u3c/em\u3e complex (Brassicaceae)

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    The Streptanthus morrisonii complex is a six-taxon group of closely related serpentine rock outcrop endemics from Lake, Napa, and Sonoma counties of California, USA. Two new subspecies (S. morrisonii subsp. kruckebergii and S. brachiatus subsp. hoffmanii) from Lake County, California, are described. The relationship of these taxa to others in the section is reviewed and descriptions and a key are provided

    Computer program for parameterization of nucleus-nucleus electromagnetic dissociation cross sections

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    A computer subroutine parameterization of electromagnetic dissociation cross sections for nucleus-nucleus collisions is presented that is suitable for implementation in a heavy ion transport code. The only inputs required are the projectile kinetic energy and the projectile and target charge and mass numbers

    A Comparison of Changes in the Structure of Wages

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    This paper compares changes in the structure of wages in France, Great Britain, Japan. and the United States over the last twenty years. Wage differentials by education and occupation (skill differentials) narrowed substantially in all four countries in the 1970s. Overall wage inequality and skill differentials expanded dramatically in Great Britain and the United States and moderately in Japan during the 1980s. In contrast, wage inequality did not increase much in France through the mid-1980s. Industrial and occupational shifts favored more-educated workers in all four countries throughout the last twenty years. Reductions in the rate of the growth of the relative supply of college-educated workers in the face of persistent increases in the relative demand for more-skilled labor can explain a substantial portion of the increase in educational wage differentials in the United States, Britain, and Japan in the 1980s. Sharp increases in the national minimum wage (the SM1C) and the ability of French unions to extend contracts even in the face of declining membership helped prevent wage differentials from expanding in France through the mid-1980s.

    A Microeconomic Study of Commercial Real Estate Brokerage Firms

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    While residential brokerage has been widely studied, the operating characteristics on income property brokerage firms have received little attention in the literature. In this paper, we analyze results from a survey of income property brokers to measure profitability scale effects, and expenditures at the firm level. We find that while scale economies exist for expenses, net income per producer falls as firms grow; the optimally sized firm is comparatively small. Although inconsistencies with results from recent residential brokerage studies may relate to the survey period, they may also support a view that residential and income brokerage firms are structurally different.

    An optical model description of momentum transfer in heavy ion collisions

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    An optical model description of momentum transfer in relativistic heavy ion collisions, based upon composite particle multiple scattering theory, is presented. The imaginary component of the complex momentum transfer, which comes from the absorptive part of the optical potential, is identified as the longitudinal momentum downshift of the projectile. Predictions of fragment momentum distribution observables are made and compared with experimental data. Use of the model as a tool for estimating collision impact parameters is discussed

    High Field Studies of Superconducting Fluctuations in High-T_c Cuprates: Evidence for a Small Gap distinct from the Large Pseudogap

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    We have used pulsed magnetic fields up to 60Tesla to suppress the contribution of superconducting fluctuations(SCF)to the conductivity above Tc in a series of YBa2Cu3O6+x from the deep pseudogapped state to slight overdoping. Accurate determinations of the SCF conductivity versus temperature and magnetic field have been achieved. Their joint quantitative analyses with respect to Nernst data allow us to establish that thermal fluctuations following the Ginzburg-Landau(GL) scheme are dominant for nearly optimally doped samples. The deduced coherence length xi(T) is in perfect agreement with a gaussian (Aslamazov-Larkin) contribution for 1.01Tc<T<1.2Tc. A phase fluctuation contribution might be invoked for the most underdoped samples in a T range which increases when controlled disorder is introduced by electron irradiation. For all dopings we evidence that the fluctuations are highly damped when increasing T or H. The data permits us to define a field Hc^prime and a temperature Tc^prime above which the SCF are fully suppressed. The analysis of the fluctuation magnetoconductance in the GL approach allows us to determine the critical field Hc2(0). The actual values of Hc^prime(0) and Hc2(0) are found quite similar and both increase with hole doping. These depairing fields, which are directly connected to the magnitude of the SC gap, do therefore follow the Tc variation which is at odds with the sharp decrease of the pseudogap T* with increasing hole doping. This is on line with our previous evidence that T* is not the onset of pairing. We finally propose a three dimensional phase diagram including a disorder axis, which allows to explain most peculiar observations done so far on the diverse cuprate families.Comment: revised version, to be published in Physical Review B. Small modifications have been done in paragraphs VI.A and VI

    HZETRN: A heavy ion/nucleon transport code for space radiations

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    The galactic heavy ion transport code (GCRTRN) and the nucleon transport code (BRYNTRN) are integrated into a code package (HZETRN). The code package is computer efficient and capable of operating in an engineering design environment for manned deep space mission studies. The nuclear data set used by the code is discussed including current limitations. Although the heavy ion nuclear cross sections are assumed constant, the nucleon-nuclear cross sections of BRYNTRN with full energy dependence are used. The relation of the final code to the Boltzmann equation is discussed in the context of simplifying assumptions. Error generation and propagation is discussed, and comparison is made with simplified analytic solutions to test numerical accuracy of the final results. A brief discussion of biological issues and their impact on fundamental developments in shielding technology is given

    The UPC Addresses the Class-Gift and Intestacy Rights of Children of Assisted Reproduction Technologies

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    Editor\u27s Synopsis: Recent years\u27 advances in assisted reproduction technology have enabled the conception of children in ways in addition to the traditional way. The Uniform Probate Code was amended last year to address the status of children born from assisted reproductive technologies for intestacy and class-gift purposes. This article discusses the relevant UPC provisions and offers several hypothetical cases to show how they operate. The article concludes expressing the hope that states will consider the new UPC approach
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