4,650 research outputs found

    UBVRIJKL light curves of classical Cepheids

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    Photoelectric observations and light curves of UBVRIJKL system for classical Cepheid variable stars - tables and graph

    Relationship of Circulating Eosinophils, Other Blood Cellular Components and Plasma Corticoids in Dairy Cattle Subjected to Nutritional Stress

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    Twenty-six first lactation dairy cattle were sampled biweekly for four months to determine the effect of five levels of nutrition on blood plasma corticoids, total and differential leucocytes, hemoglobin and packed cell volume. Cows completing their 305 day lactation during the four month sampling interval were removed from the experimental herd, but were sampled twice more. It was hypothesized that cows on ration s below NRC requirements for milk production would demonstrate stress symptoms of elevated plasma corticoids, elevated white blood count, neutrophilia and eosinopenia. It was also hypothesized that measuring the decrease in eosinophils would be a better method of quantifying nutritional stress than by measuring corticoids, since circulating eosinophils are not subject to rapid increases from stresses of sampling, as are the corticoids. Least squares analysis indicated a trend for increased corticoids with decreased level of nutrition, but the trend was not significant (p\u3e . 05). Eosinophil level was significantly (p \u3c . 05) correlated with ration indicating increased stress caused a rise in eosinophils in stead of a decline as was expected. Eosinophils were negatively correlated with corticoids (-.12) as expected but the relation ship was not significant (p\u3e.05). Ration was positively correlated with milk yield, body weight, and number of circulating neutrophils. Ration was negatively correlated with total leucocyte count. No significant change in hemoglobin or packed cell volume was detected. Significant (p \u3c • 01) increases in leucocytes, neutrophils and hemoglobin were observed in the cows after completion of the 305 day lactation. Significant (p\u3c.01) decreases in corticoids and milk production were also observed in these cows

    Phi meson production in near threshold proton-nucleus collisions

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    The cross section for production of Phi mesons in proton-nucleus reactions is calculated as a function of the target mass. The decay width of the Phi meson is affected by the change of the masses of the Phi, K+ and K- mesons in the medium. A strong attractive K- potential leads to a measurable change of the behavior of the cross section as a function of of the target mass. Comparison between the kaon and electron decay modes are made.Comment: 4 pages, 1figure, new figure, new reference

    Relativistic jet models for the BL Lacertae object Mrk 421 during three epochs of observation

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    Coordinated observation of the nearby BL Lacertae object Mrk 421 obtained during May 1980, January 1984, and March 1984 are described. These observations give a time-frozen picture of the continuous spectrum of Mrk 421 at X-ray, ultraviolet, optical, and radio wavelengths. The observed spectra have been fitted to an inhomogeneous relativistic jet model. In general, the models reproduce the data well. Many of the observed differences during the three epochs can be attributed to variations in the opening angle of the jet and in the angle that the jet makes to the line of sight. The jet models obtained here are compared with the homogeneous, spherically symmetric, synchrotron self-Compton models for this source. The models are also compared with the relativistic jet models obtained for other active galactic nuclei

    Spatial Control of Photoemitted Electron Beams using a Micro-Lens-Array Transverse-Shaping Technique

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    A common issue encountered in photoemission electron sources used in electron accelerators is the transverse inhomogeneity of the laser distribution resulting from the laser-amplification process and often use of frequency up conversion in nonlinear crystals. A inhomogeneous laser distribution on the photocathode produces charged beams with lower beam quality. In this paper, we explore the possible use of microlens arrays (fly-eye light condensers) to dramatically improve the transverse uniformity of the drive laser pulse on UV photocathodes. We also demonstrate the use of such microlens arrays to generate transversely-modulated electron beams and present a possible application to diagnose the properties of a magnetized beam.Comment: arXiv admin note: text overlap with arXiv:1609.0166

    Mechanical Faraday effect for orbital angular momentum-carrying beams

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    When linearly polarised light is transmitted through a spinning window, the plane of polarisation is rotated. This rotation arises through a phase change that is applied to the circularly polarised states corresponding to the spin angular momentum (SAM). Here we show an analogous effect for the orbital angular momentum (OAM), where a differential phase between the positive and negative modes (±ℓ) is observed as a rotation of the transmitted image. For normal materials, this rotation is on the order of a micro radian, but by using a slow-light medium, we show a rotation of a few degrees. We also note that, within the bounds of our experimental parameters, this rotation angle does not exceed the scale of the spatial features in the beam profile

    Influence of low-level Pr substitution on the superconducting properties of YBa2Cu3O7-delta single crystals

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    We report on measurements on Y1-xPrxBa2Cu3O7-delta single crystals, with x varying from 0 to 2.4%. The upper and the lower critical fields, Hc2 and Hc1, the Ginzburg-Landau parameter and the critical current density, Jc(B), were determined from magnetization measurements and the effective media approach scaling method. We present the influence of Pr substitution on the pinning force density as well as on the trapped field profiles analyzed by Hall probe scanning.Comment: 4 pages, 5 figures, accepted for publication in J. Phys. Conf. Se

    Measurement of the mass of the Ï„ lepton

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    A data-driven energy scan in the immediate vicinity of the τ pair production threshold has been performed using the Beijing Spectrometer at the Beijing Electron-Positron Collider. Approximately 5 pb^(-1) of data, distributed over 12 scan points, have been collected. A previous mass value for the τ lepton, obtained using only the eμ final state, has been published. In this paper, the final BES result on the mass measurement is presented. The analysis is based on the combined data from the ee, eμ, eh, μμ, μh, and hh final states, where h denotes a charged π or K. A maximum likelihood fit to the τ pair production cross section data yields the value m_τ=1776.96_(-0.21)-0.17^(+0.18+0.25) MeV
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