5,990 research outputs found

    Commutative Schreier semigroup extensions of a group

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    A Management Study of the Cache Elk Herd

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    American elk, by virtue of their distribution, were the most cosmopolitan members of the cervid family at the time of white settlement of North America. At this early date elk were present in every major region of what is now continental United States, as well as in northern Mexico. they likewise were abundant in upper and lower Canada, though records do Lot corroborate their presence too far north on the Atlantic coast. Although generally existent throughout the western states, elk were sparsely distributed in Nevada, southern Utah, and most of Arizona and New Mexico. Paucity of elk was also noted in eastern portions of Washington and Oregon

    Non-invasive single-bunch matching and emittance monitor

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    On-line monitoring of beam quality for high brightness beams is only possible using non-invasive instruments. For matching measurements, very few such instruments are available. One candidate is a quadrupole pick-up. Therefore, a new type of quadrupole pick-up has been developed for the 26 GeV Proton Synchrotron (PS) at CERN, and a measurement system consisting of two such pick-ups is now installed in this accelerator. Using the information from these pick-ups, it is possible to determine both injection matching and emittance in the horizontal and vertical planes, for each bunch separately. This paper presents the measurement method and some of the results from the first year of use, as well as comparisons with other measurement methods.Comment: 10 pages, 10 figures; added figure, minor textual additions; To be resubmitted to Phys. Rev. ST-A

    Teaching While Black and Female: Navigating Mental, Curricular, and Professional Aggression

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    It is evident that many Black women teachers (BWTs) are leaving the teaching profession due to mental and emotional health, professional and collegial relationships, as well as curricular and school culture. In this article, we use the story of Alicia to explore the instructional, professional, and emotional stress that many Black women teachers endure. We also provide highlight theoretical constructs and practical applications that can impact BWTs. In addition, we examine approaches that engage the retention of Black women teachers through a process of personal and professional support systems

    Exploratory studies of the cruise performance of upper surface blown configurations

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    The data and major conclusions obtained from an experimental/analytical study of upper-surface blown (USB) configurations at cruise are summarized. The high-speed (subsonic) experimental work, studying the aerodynamic effects of wing-nacelle geometric variations, was conducted around semi-span model configurations composed of diversified, interchangeable components. Power simulation was provided by high pressure air ducted through closed forebody nacelles. Nozzle geometry was varied across size, exit aspect ratio, exit position and boattail angle. Both 3-D force and 2-D pressure measurements were obtained at cruise Mach numbers from 0.5 to 0.8 and at nozzle pressure ratios up to about 3.0. The experimental investigation was supported by an analytical synthesis of the system using a vortex lattice representation with first-order power effects. Results are also presented from a compatibility study in which a short-haul transport is designed on the basis of the aerodynamic findings in the experimental study as well as acoustical data obtained in a concurrent program. High-lift test data are used to substantiate the projected performance of the selected transport design

    Origin of Middle-Infrared Peaks in Cerium Compounds

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    We have demonstrated that the middle-infrared (mid-IR) peaks in the optical conductivity spectra of CeX3X_3 (XX = Pd, Sn, In) can be explained by first-principle band structure calculation with the spin-orbit interaction. The mid-IR peak shapes in these materials are not identical to one another: CePd3_3, CeSn3_3, and CeIn3_3 have a triple-peak structure, double-peak structure and broad single-peak structure, respectively. These peaks can be theoretically explained by the optical transition from the occupied state to the spin-orbit splitted Ce 4f4f state. This result indicates that the mid-IR peaks originate from the simple band picture with the Ce 4f4f state near the Fermi level, not from the conventional cf hybridization gap based on the periodic Anderson model.Comment: 5 pages, 6 figures. To be published in J. Phys. Soc. Jpn. 78(1) (2009

    Soliton response to transient trap variations

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    The response of bright and dark solitons to rapid variations in an expulsive longitudinal trap is investigated. We concentrate on the effect of transient changes in the trap frequency in the form of temporal delta kicks and the hyperbolic cotangent functions. Exact expressions are obtained for the soliton profiles. This is accomplished using the fact that a suitable linear Schrodinger stationary state solution in time can be effectively combined with the solutions of non-linear Schrodinger equation, for obtaining solutions of the Gross-Pitaevskii equation with time dependent scattering length in a harmonic trap. Interestingly, there is rapid pulse amplification in certain scenarios
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