567 research outputs found

    Investigations into the paralysis-inducing ability of Rhipicephalus evertsi mimeticus and that of hybrids between this subspecies and Rhipicephalus evertsi evertsi

    Get PDF
    Studies performed on sheep showed that Rhipicephalus evertsi mimeticus is a paralysis-competent tick species whose toxicity is either the same as, or only slightly less than that of R. e. evertsi. It was also proved that the paresis or paralysis induced by the mimeticus females is characterized by a constant incubation period which is independent of the tick infestation rate and body mass of the host and consequently of its age. This period is entirely determined by the state of repletion of the ticks and is regulated by the date of mating. It was further proved that a precise relationship exists between an increase of engorgement or salivation activity and the intensity as well as the persistence of clinical symptoms. Thus only female ticks in the mass range of 15-21 mg are toxic. Strain-dependent differences could not be demonstrated. The infestation rates of subspecific hybrid female ticks, and of their descendants, that are necessary to produce the respective symptoms showed no differences in toxicity. When infestations were limited to a small skin area minimum paresis could frequently not be induced, even though the actual number of ticks applied was sufficient to cause lethal paralysis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

    Hard Exclusive Pion Electroproduction at Backward Angles With CLAS

    Get PDF
    We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, ep → e\u27nπ+, above the resonance region at backward pion center-of-mass angles. The ϕ∗ π-dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs). These non-perturbative objects are defined as matrix elements of threequark-light-cone-operators and characterize partonic correlations with a particular emphasis on baryon charge distribution inside a nucleon

    First Results on Nucleon Resonance Photocouplings from the γp → π+π−p Reaction

    Get PDF
    We report the first experimental measurements of the nine 1-fold differential cross sections for the γ p → π+π−p reaction, obtained with the CLAS detector at Jefferson Laboratory. The measurements cover the invariant mass range of the final state hadrons from 1.6 GeV \u3c W \u3c 2.0 GeV. For the first time the photocouplings of all prominent nucleon resonances in this mass range have been extracted from this exclusive channel. Photoproduction of two charged pions is of particular importance for the evaluation of the photocouplings for the Δ (1620)1/2−, Δ (1700)3/2−, N(1720)3/2+, and Δ (1905)5/2+ resonances, which have dominant decays into the π π N final states rather than the more extensively studied single meson decay channels

    Measurements of the γv p → p\u27π+π− Cross Section with the CLAS Detector for 0.4 GeV\u3csup\u3e2\u3c/sup\u3e \u3c Q\u3csup\u3e2\u3c/sup\u3e \u3c 1.0 GeV\u3csup\u3e2\u3c/sup\u3e and 1.3 GeV \u3c W \u3c 1.825 GeV

    Get PDF
    New results on the single-differential and fully integrated cross sections for the process γvp → p\u27π+π− are presented. The experimental data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the kinematic region of the reaction invariant mass W from 1.3 to 1.825 GeV and the photon virtuality Q2 from 0.4 to 1.0 GeV2. The cross sections were obtained in narrow Q2 bins (0.05 GeV2) with the smallest statistical uncertainties achieved in double-pion electroproduction experiments to date. The results were found to be in agreement with previously available data where they overlap. A preliminary interpretation of the extracted cross sections, which was based on a phenomenological meson-baryon reaction model, revealed substantial relative contributions from nucleon resonances. The data offer promising prospects to improve knowledge on the Q2 evolution of the electrocouplings of most resonances with masses up to ∼1.8 GeV

    Measurements of ep → e′π+π-p′ Cross Sections with CLAS at 1.40 GeV \u3c W \u3c 2.0 GeV and 2.0 GeV² \u3c Q² \u3c 5.0 GeV²

    Get PDF
    This paper reports new exclusive cross sections for ep → e′π+π-p′ using the CLAS detector at Jefferson Laboratory. These results are presented for the first time at photon virtualities 2.0GeV2 2 \u3c 5.0GeV2 in the center-of-mass energy range 1.4 GeV \u3c W \u3c 2.0 GeV, which covers a large part of the nucleon resonance region. Using a model developed for the phenomenological analysis of electroproduction data, we see strong indications that the relative contributions from the resonant cross sections at W \u3c 1.74 GeV increase with Q2. These data considerably extend the kinematic reach of previous measurements. Exclusive ep → e′π+π-p′ cross section measurements are of particular importance for the extraction of resonance electrocouplings in the mass range above 1.6 GeV

    State sampling dependence of the Hopfield network inference

    Get PDF
    The fully connected Hopfield network is inferred based on observed magnetizations and pairwise correlations. We present the system in the glassy phase with low temperature and high memory load. We find that the inference error is very sensitive to the form of state sampling. When a single state is sampled to compute magnetizations and correlations, the inference error is almost indistinguishable irrespective of the sampled state. However, the error can be greatly reduced if the data is collected with state transitions. Our result holds for different disorder samples and accounts for the previously observed large fluctuations of inference error at low temperatures.Comment: 4 pages, 1 figure, further discussions added and relevant references adde

    In-medium ω\omega mass from the γ+Nbπ0γ+X\gamma + Nb \to \pi^{0}\gamma + X reaction

    Full text link
    Data on the photoproduction of ω\omega mesons on nuclei have been re-analyzed in a search for in-medium modifications. The data were taken with the Crystal Barrel(CB)/TAPS detector system at the ELSA accelerator facility in Bonn. First results from the analysis of the data set were published by D. Trnka et al. in Phys. Rev. Lett 94 (2005) 192303 \cite{david}, claiming a lowering of the ω\omega mass in the nuclear medium by 14% at normal nuclear matter density. The extracted ω\omega line shape was found to be sensitive to the background subtraction. For this reason a re-analysis of the same data set has been initiated and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the re-analysis and of the background determination are described. The ω\omega signal on the NbNb target, extracted in the re-analysis, does not show a deviation from the corresponding line shape on a LH2LH_2 target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the ω\omega line shape to different in-medium modification scenarios is discussed.Comment: 13 pages and 11 figures, submitted for publicatio
    corecore