40,684 research outputs found

    A biologically active peptide in the skin of lampreys (Eudontomyzon danfordi vladykovi). [Translation from: Z.Naturforsch. (B), 26(10), 1021-1023, 1971. ]

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    In recent years interest in the production and description of kinin-type substances has been greatly intensified. So, for example, bradykinin, phyllokinin, physalaemin, ranatensin and caerulein could be extracted from the skin of amphibians as well as. eledoisin out of the salivary glands of Eledon moschata. An examination of lampreys seemed to us particularly profitable in the search for the incidence of further kinins. Ammocoetes of different sizes and also adults of both sexes of the species Eudontomyzon danfordi vladykovi were studied in this research. This species is found in many tributaries of the Danube. Skin extracts were tested on on isolated rat uterus, rat duodenum, guinea pig ileum and rabbit jejunum, further tests were done in order to determine a peptide character of the biologically active substance

    Long-range beam-beam experiments in the relativistic heavy ion collider

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    Long-range beam-beam effects are a potential limit to the LHC performance with the nominal design parameters, and certain upgrade scenarios under discussion. To mitigate long-range effects, current carrying wires parallel to the beam were proposed and space is reserved in the LHC for such wires. Two current carrying wires were installed in RHIC to study the effect of strong long-range beam-beam effects in a collider, as well as test the compensation of a single long-range interaction. The experimental data were used to benchmark simulations. We summarize this work.Comment: 12 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201

    Observations on background in PHOBOS and related electron cloud simulations

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    Radiant heat exchange in a space environment Scientific technical report, 1 Feb. - 31 Jul. 1970

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    Spectral and directional surface property effects on radiant heat transfer in space environmen

    Radiant heat exchange in a space environment Scientific technical report, 1 Aug. 1969 - 31 Jan. 1970

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    Spectral surface property effects on radiant heat transfer in aerospace environmen

    Rare events in population genetics: Stochastic tunneling in a two-locus model with recombination

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    We study the evolution of a population in a two-locus genotype space, in which the negative effects of two single mutations are overcompensated in a high fitness double mutant. We discuss how the interplay of finite population size, NN, and sexual recombination at rate rr affects the escape times tesct_\mathrm{esc} to the double mutant. For small populations demographic noise generates massive fluctuations in tesct_\mathrm{esc}. The mean escape time varies non-monotonically with rr, and grows exponentially as lntescN(rr)3/2\ln t_{\mathrm{esc}} \sim N(r - r^\ast)^{3/2} beyond a critical value rr^\ast.Comment: 4 pages, 3 figure

    Gibbons-Hawking Effect in the Sonic de Sitter Space-Time of an Expanding Bose-Einstein-Condensed Gas

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    We propose an experimental scheme to observe the Gibbons-Hawking effect in the acoustic analog of a 1+1-dimensional de Sitter universe, produced in an expanding, cigar-shaped Bose-Einstein condensate. It is shown that a two-level system created at the center of the trap, an atomic quantum dot interacting with phonons, observes a thermal Bose distribution at the de Sitter temperature.Comment: 4 pages, 2 figures, RevTex4; as publishe

    High-Precision Optical Measurement of the 2S Hyperfine Interval in Atomic Hydrogen

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    We have applied an optical method to the measurement of the 2S hyperfine interval in atomic hydrogen. The interval has been measured by means of two-photon spectroscopy of the 1S-2S transition on a hydrogen atomic beam shielded from external magnetic fields. The measured value of the 2S hyperfine interval is equal to 177 556 860(15) Hz and represents the most precise measurement of this interval to date. The theoretical evaluation of the specific combination of 1S and 2S hyperfine intervals D_21 is in moderately good agreement with the value for D_21 deduced from our measurement
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