251 research outputs found

    Factors affecting the growth and survival of Matebele goat kids in a semi-arid environment under smallholder management

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    A research article on factors affecting effective goat rearing in Zimbabwe's rural areas.Performance of 631 kids belonging to seven smallholder farmers in southern Zimbabwe was monitored over a two-year period. Least square mean live weights at 14,150 and 360 days (d) of growth were 4.3 + 0.04,11.5 + 0.11 and 19.9 + 0.19 kg, respectively. Exit rate between birth and 150 days was 35 percent. Live weight at all the three stages of growth and pre-weaning exit rates varied significantly (p<0.001) between birth months and between flocks (p<0.001). Pre-weaning growth rates tended to be relatively faster for kids born between September and January (dry to early wet seasons) but were depressed post-weaning as a result of dry season feed shortages. Consequently, kids born in September-January tended to weigh less at 360 days compared to kids born in February-July. Male kids and singles were significantly heavier (p<0.001) at all ages than female kids and twins, respectively. Age of the doe significantly affected kid weight at 150 d, with kids born to does of 1 to 2 years of age being 13-25 percent lighter (p<0.01) than kids born to older does. Exit rates were highest (33 percent) in July, the month where maximum births occur. Exit rates were significantly higher (p<0.001) in year 1 (52 + 0.22 percent) than in year 2 (48 + 0.31 percent). Kid survival was not influenced by age of the doe, sex or birth type of the kids. It is concluded that growth and survival of Matebele kids could be improved through strategic management of seasonal effects and better understanding of local management

    Vacuum-UV negative photoion spectroscopy of CH4

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    Using synchrotron radiation in the range 12-35 eV, negative ions are detected by mass spectrometry following vacuum-UV photoexcitation of methane. Ion yields for H^-, CH^- and CH2_2^- are recorded, the spectra of CH^- and CH2_2^- for the first time. All ions display a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation. Cross sections for ion-pair formation are put onto an absolute scale by calibrating the signal strengths with those of F^- from SF6_6 and CF4_4. Following normalisation to total vacuum-UV absorption cross sections, quantum yields for anion production are reported. There is a major discrepancy in the H^- cross section with an earlier measurement, which remains unresolved. The anions arise from both direct and indirect ion-pair mechanisms. For a generic polyatomic molecule AB, the former is defined as AB \rightarrow A^- + B+^+ (+ neutrals), the latter as the predissociative crossing of an initially-excited Rydberg state of AB by an ion-pair state. In a separate experiment, the threshold photoelectron spectrum of the second valence band of CH4_4, ionisation to CH4+_4^+ A 2^2A1_1 at 22.4 eV, is recorded with an instrumental resolution of 0.004 eV; many of the Rydberg states observed in indirect ion-pair formation converge to this state. The widths of the peaks are lifetime limited, increasing with increasing vv in the v1v_1 (a1_1) vibrational ladder. They are the first direct measurement of an upper value to the dissociation rate of these levels into fragment ions

    Withdrawal of antiepileptic drugs in patients with low grade and anaplastic glioma after long-term seizure freedom: a prospective observational study

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    Background When glioma patients experience long-term seizure freedom the question arises whether antiepileptic drugs (AEDs) should be continued. As no prospective studies exist on seizure recurrence in glioma patients after AED withdrawal, we evaluated the decision-making process to withdraw AEDs in glioma patients, and seizure outcome after withdrawal. Methods Patients with a histologically confirmed low grade or anaplastic glioma were included. Eligible patients were seizure free ≥ 1 year from the date of last antitumor treatment, or ≥ 2 years since the last seizure when seizures occurred after the end of the last antitumor treatment. Patients and neuro-oncologists made a shared decision on the preferred AED treatment (i.e. AED withdrawal or continuation). Primary outcomes were: (1) outcome of the shared decision-making process and (2) rate of seizure recurrence. Results Eighty-three patients fulfilled all eligibility criteria. However, in 12/83 (14%) patients, the neuro-oncologist had serious objections to AED withdrawal. Therefore, 71/83 (86%) patients were analyzed; In 46/71 (65%) patients it was decided to withdraw AED treatment. In the withdrawal group, 26% (12/46) had seizure recurrence during follow-up. Seven of these 12 patients (58%) had tumor progression, of which three within 3 months after seizure recurrence. In the AED continuation group, 8% (2/25) of patients had seizure recurrence of which one had tumor progression. Conclusion In 65% of patients a shared decision was made to withdraw AEDs, of which 26% had seizure recurrence. AED withdrawal should only be considered in carefully selected patients with a presumed low risk of tumor progression

    Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

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    We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

    Search for strong gravity in multijet final states produced in pp collisions at √s=13 TeV using the ATLAS detector at the LHC

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    A search is conducted for new physics in multijet final states using 3.6 inverse femtobarns of data from proton-proton collisions at √s = 13TeV taken at the CERN Large Hadron Collider with the ATLAS detector. Events are selected containing at least three jets with scalar sum of jet transverse momenta (HT) greater than 1TeV. No excess is seen at large HT and limits are presented on new physics: models which produce final states containing at least three jets and having cross sections larger than 1.6 fb with HT > 5.8 TeV are excluded. Limits are also given in terms of new physics models of strong gravity that hypothesize additional space-time dimensions

    Measurement of jet charge in dijet events from √s = 8  TeV pp collisions with the ATLAS detector

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    The momentum-weighted sum of the charges of tracks associated to a jet is sensitive to the charge of the initiating quark or gluon. This paper presents a measurement of the distribution of momentum-weighted sums, called jet charge, in dijet events using 20.3 fb−¹ of data recorded with the ATLAS detector at √s = 8 TeV in pp collisions at the LHC. The jet charge distribution is unfolded to remove distortions from detector effects and the resulting particle-level distribution is compared with several models. The pT dependence of the jet charge distribution average and standard deviation are compared to predictions obtained with several leading-order and next-to-leading-order parton distribution functions. The data are also compared to different Monte Carlo simulations of QCD dijet production using various settings of the free parameters within these models. The chosen value of the strong coupling constant used to calculate gluon radiation is found to have a significant impact on the predicted jet charge. There is evidence for a pT dependence of the jet charge distribution for a given jet flavor. In agreement with perturbative QCD predictions, the data show that the average jet charge of quark-initiated jets decreases in magnitude as the energy of the jet increases
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