1,172 research outputs found

    Identification of Heterorhabditis (Nematoda : Heterorhabditidae) from California with a new species isolated from the larvae of the ghost moth Hepialis californicus (Lepidoptera : Hepialidae) from the Bodega Bay Natural Reserve

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    Les mĂ©thodes de taxonomie classique de mĂȘme que des essais de croisement et l'amplification au hasard de l'ADN polymorphique (RAPD) ont Ă©tĂ© utilisĂ©s pour dĂ©tecter les diffĂ©rences morphologiques et gĂ©nĂ©tiques entre populations d'#Heterorhabditis Pointar, 1975 provenant de Californie. Une nouvelle espĂšce, #Heterorhabditis hepialius sp. n., prĂ©sente dans des chenilles d'#Hepialis californicus provenant de la baie de Bodega (Californie, Etats-Unis d'AmĂ©rique) est dĂ©crite et illustrĂ©e. ReprĂ©sentant la huitiĂšme espĂšce du genre, #H. hepialius sp. n. est caractĂ©risĂ© par la morphologie des spicules, du gubernaculum, et de la queue de la femelle ainsi que les rapports E et F chez les juvĂ©niles infestants. Des donnĂ©es sur sa biologie sont Ă©galement fournies. (RĂ©sumĂ© d'auteur

    PROMPT RADIATION EFFECTS ON CABLES AND LINEAR POWER INSTRUMENTATION CHANNELS

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    Tests were conducted to determine the amount of error introduced in reactor power data by radiation-induced voltages in cables and electrometer preamplifier chassis. The results, obtained near the central exposure facility of the KEWB (Reacter Safety Experiments), showed no observable radiation effects under the conditions of present use. Cable insulation resistance was measured during the radiation bursts. (C.J.G.

    On the local systems Hamiltonian in the weakly nonlocal Poisson brackets

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    We study in this work the important class of nonlocal Poisson Brackets (PB) which we call weakly nonlocal. They appeared recently in some investigations in the Soliton Theory. However there was no theory of such brackets except very special first order case. Even in this case the theory was not developed enough. In particular, we introduce the Physical forms and find Casimirs, Momentum and Canonical forms for the most important Hydrodynamic type PB of that kind and their dependence on the boundary conditions.Comment: 45 pages, late

    Bimodal Expansion of the Lymphatic Vessels Is Regulated by the Sequential Expression of IL-7 and Lymphotoxin α1ÎČ2 in Newly Formed Tertiary Lymphoid Structures.

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    Lymphangiogenesis associated with tertiary lymphoid structure (TLS) has been reported in numerous studies. However, the kinetics and dynamic changes occurring to the lymphatic vascular network during TLS development have not been studied. Using a viral-induced, resolving model of TLS formation in the salivary glands of adult mice we demonstrate that the expansion of the lymphatic vascular network is tightly regulated. Lymphatic vessel expansion occurs in two distinct phases. The first wave of expansion is dependent on IL-7. The second phase, responsible for leukocyte exit from the glands, is regulated by lymphotoxin (LT)ÎČR signaling. These findings, while highlighting the tight regulation of the lymphatic response to inflammation, suggest that targeting the LTα1ÎČ2/LTÎČR pathway in TLS-associated pathologies might impair a natural proresolving mechanism for lymphocyte exit from the tissues and account for the failure of therapeutic strategies that target these molecules in diseases such as rheumatoid arthritis

    Evolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USA

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    This paper is not subject to U.S. copyright. The definitive version was published in Sedimentology 53 (2006): 1211-1228, doi:10.1111/j.1365-3091.2006.00809.x.Episodic, large-volume pulses of volcaniclastic sediment and coseismic subsidence of the coast have influenced the development of a late Holocene delta at southern Puget Sound. Multibeam bathymetry, ground-penetrating radar (GPR) and vibracores were used to investigate the morphologic and stratigraphic evolution of the Nisqually River delta. Two fluvial–deltaic facies are recognized on the basis of GPR data and sedimentary characteristics in cores, which suggest partial emplacement from sediment-rich floods that originated on Mount Rainier. Facies S consists of stacked, sheet-like deposits of andesitic sand up to 4 m thick that are continuous across the entire width of the delta. Flat-lying, highly reflective surfaces separate the sand sheets and comprise important facies boundaries. Beds of massive, pumice- and charcoal-rich sand overlie one of the buried surfaces. Organic-rich material from that surface, beneath the massive sand, yielded a radiocarbon age that is time-correlative with a series of known eruptive events that generated lahars in the upper Nisqually River valley. Facies CF consists of linear sandbodies or palaeochannels incised into facies S on the lower delta plain. Radiocarbon ages of wood fragments in the sandy channel-fill deposits also correlate in time to lahar deposits in upstream areas. Intrusive, sand-filled dikes and sills indicate liquefaction caused by post-depositional ground shaking related to earthquakes. Continued progradation of the delta into Puget Sound is currently balanced by tidal-current reworking, which redistributes sediment into large fields of ebb- and flood-oriented bedforms.This study was supported by the Coastal and Marine Geology Program, and the Earthquake Hazards Program of the U.S. Geological Survey

    Rotational spectroscopy of isotopic vinyl cyanide, H2_2C=CH−-C≡\equivN, in the laboratory and in space

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    The rotational spectra of singly substituted 13^{13}C and 15^{15}N isotopic species of vinyl cyanide have been studied in natural abundances between 64 and 351 GHz. In combination with previous results, greatly improved spectroscopic parameters have been obtained which in turn helped to identify transitions of the 13^{13}C species for the first time in space through a molecular line survey of the extremely line-rich interstellar source Sagittarius B2(N) in the 3 mm region with some additional observations at 2 mm. The 13^{13}C species are detected in two compact (∌2.3â€Čâ€Č\sim 2.3''), hot (170 K) cores with a column density of ∌3.8×1016\sim 3.8 \times 10^{16} and 1.1×10161.1 \times 10^{16} cm−2^{-2}, respectively. In the main source, the so-called ``Large Molecule Heimat'', we derive an abundance of 2.9×10−92.9 \times 10^{-9} for each 13^{13}C species relative to H2_2. An isotopic ratio 12^{12}C/13^{13}C of 21 has been measured. Based on a comparison to the column densities measured for the 13^{13}C species of ethyl cyanide also detected in this survey, it is suggested that the two hot cores of Sgr B2(N) are in different evolutionary stages. Supplementary laboratory data for the main isotopic species recorded between 92 and 342 GHz permitted an improvement of its spectroscopic parameters as well.Comment: 18 pages, including 2 tables, 3 figures; plus one supplementary text file plus one supplementary pdf file; J. Mol. Spectrosc., in press (to appear in the July or August issue of 2008

    Dynamical stability of infinite homogeneous self-gravitating systems: application of the Nyquist method

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    We complete classical investigations concerning the dynamical stability of an infinite homogeneous gaseous medium described by the Euler-Poisson system or an infinite homogeneous stellar system described by the Vlasov-Poisson system (Jeans problem). To determine the stability of an infinite homogeneous stellar system with respect to a perturbation of wavenumber k, we apply the Nyquist method. We first consider the case of single-humped distributions and show that, for infinite homogeneous systems, the onset of instability is the same in a stellar system and in the corresponding barotropic gas, contrary to the case of inhomogeneous systems. We show that this result is true for any symmetric single-humped velocity distribution, not only for the Maxwellian. If we specialize on isothermal and polytropic distributions, analytical expressions for the growth rate, damping rate and pulsation period of the perturbation can be given. Then, we consider the Vlasov stability of symmetric and asymmetric double-humped distributions (two-stream stellar systems) and determine the stability diagrams depending on the degree of asymmetry. We compare these results with the Euler stability of two self-gravitating gaseous streams. Finally, we determine the corresponding stability diagrams in the case of plasmas and compare the results with self-gravitating systems

    Search for Λc+→pK+π−\Lambda_c^+ \to p K^+ \pi^- and Ds+→K+K+π−D_s^+ \to K^+ K^+ \pi^- Using Genetic Programming Event Selection

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    We apply a genetic programming technique to search for the double Cabibbo suppressed decays Λc+→pK+π−\Lambda_c^+ \to p K^+ \pi^- and Ds+→K+K+π−D_s^+ \to K^+ K^+ \pi^-. We normalize these decays to their Cabibbo favored partners and find BR(\text{BR}(\Lambda_c^+ \to p K^+ \pi^-)/BR()/\text{BR}(\Lambda_c^+ \to p K^- \pi^+)=(0.05±0.26±0.02)) = (0.05 \pm 0.26 \pm 0.02)% and BR(\text{BR}(D_s^+ \to K^+ K^+ \pi^-)/BR()/\text{BR}(D_s^+ \to K^+ K^- \pi^+)=(0.52±0.17±0.11)) = (0.52\pm 0.17\pm 0.11)% where the first errors are statistical and the second are systematic. Expressed as 90% confidence levels (CL), we find <0.46< 0.46 % and <0.78 < 0.78% respectively. This is the first successful use of genetic programming in a high energy physics data analysis.Comment: 10 page

    Measurement of the D+ and Ds+ decays into K+K-K+

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    We present the first clear observation of the doubly Cabibbo suppressed decay D+ --> K-K+K+ and the first observation of the singly Cabibbo suppressed decay Ds+ --> K-K+K+. These signals have been obtained by analyzing the high statistics sample of photoproduced charm particles of the FOCUS(E831) experiment at Fermilab. We measure the following relative branching ratios: Gamma(D+ --> K-K+K+)/Gamma(D+ --> K-pi+pi+) = (9.49 +/- 2.17(statistical) +/- 0.22(systematic))x10^-4 and Gamma(Ds+ --> K-K+K+)/Gamma(Ds+ --> K-K+pi+) = (8.95 +/- 2.12(statistical) +2.24(syst.) -2.31(syst.))x10^-3.Comment: 10 pages, 8 figure

    A Non-parametric Approach to the D+ to K*0bar mu+ nu Form Factors

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    Using a large sample of D+ -> K- pi+ mu+ nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present the first measurements of the helicity basis form factors free from the assumption of spectroscopic pole dominance. We also present the first information on the form factor that controls the s-wave interference discussed in a previous paper by the FOCUS collaboration. We find reasonable agreement with the usual assumption of spectroscopic pole dominance and measured form factor ratios.Comment: 14 pages, 5 figures, and 2 tables. We updated the previous version by changing some words, removing one plot, and adding two tables. These changes are mostly stylisti
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