850 research outputs found

    Presencia de Rhinospathe albomarginata Chevrolat, 1878 (Coleoptera: Curculionidae) como plaga de Erythrina costaricensis Micheli, 1874 (Fabales: Fabaceae)

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    AbstractIntroduction: Rhinospathe albomarginata Chevrolat, 1878 (Coleoptera: Curculionidae) initially described in 1878, is distributed in Costa Rica and Panama. Objective: To document the presence of Rhinospathe albomarginata as a pest of Erythrina costaricensis Micheli, 1894 (Fabales: Fabaceae) in a recently established silvopastoral system, under intensive-use field conditions. Materials and methods: This emergent observational work was carried out at the Alfredo Volio Mata Experimental Station, Ochomogo, Cartago province, Costa Rica, in a grazing lot between July 27 and August 10 of 2016; measurements were made of the foliar area and number of affected trees, and a natural repellent was applied for its control. Results: The insect's presence as a pest of E. costaricensis, and the damage done to the leaf area were documented, where 40,3 % of the trees showed a mean damage in the range of 5 to 10 % of the leaflet surface, in some samples up to 20 %. Conclusion: This note is the first record of the beetle as a pest in this tree species; the applied organic bioinput (extract of Bocconia frutescens L., 1753. Papaverales: Papaveraceae) showed insect repellent properties. Keywords: Rhinospathe, Erythrina costaricensis, silvopastoral system, forage trees.ResumenIntroducción. Rhinospathe albomarginata Chevrolat, 1878 (Coleoptera: Curculionidae: Entimini) fue descrita originalmente por Chevrolat en 1878) con distribución en Costa Rica y Panamá. Objetivo: documentar la presencia de Rhinospathe albomarginata como plaga de Erythrina costaricensis Micheli (Fabaceae) en un sistema silvopastoril intensivo (SSPi) recientemente establecido, bajo condiciones de campo. Materiales y métodos: Este trabajo observacional emergente se llevó a cabo en la Estación Experimental Alfredo Volio Mata (EEAVM), Ochomogo, provincia de Cartago, Costa Rica. En un lote de pastoreo entre el 27 de Julio (aparición) y el 10 de agosto de 2016, se hicieron mediciones del área foliar y número de árboles afectados y se aplicó un repelente natural para su control. Resultados: Se documentó la presencia del insecto en el follaje de E. costaricensis en 40,3 % de los árboles y el daño medio tuvo un rango del 5 al 10 % del área foliar, en algunas observaciones alcanzaron hasta el 20 % del área del folíolo. Conclusión: Esta nota es el primer registro del escarabajo referido en la especie forrajera arbórea; y muestra que el bioinsumo orgánico aplicado (extracto de Bocconia frutescens) presenta propiedades repelentes de insectos. Palabras clave: Rhinospathe, Erythrina costaricensis, sistema silvopastoril, árboles forrajeros

    Magnetization reversal of an individual exchange biased permalloy nanotube

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    We investigate the magnetization reversal mechanism in an individual permalloy (Py) nanotube (NT) using a hybrid magnetometer consisting of a nanometer-scale SQUID (nanoSQUID) and a cantilever torque sensor. The Py NT is affixed to the tip of a Si cantilever and positioned in order to optimally couple its stray flux into a Nb nanoSQUID. We are thus able to measure both the NT's volume magnetization by dynamic cantilever magnetometry and its stray flux using the nanoSQUID. We observe a training effect and temperature dependence in the magnetic hysteresis, suggesting an exchange bias. We find a low blocking temperature TB=18±2T_B = 18 \pm 2 K, indicating the presence of a thin antiferromagnetic native oxide, as confirmed by X-ray absorption spectroscopy on similar samples. Furthermore, we measure changes in the shape of the magnetic hysteresis as a function of temperature and increased training. These observations show that the presence of a thin exchange-coupled native oxide modifies the magnetization reversal process at low temperatures. Complementary information obtained via cantilever and nanoSQUID magnetometry allows us to conclude that, in the absence of exchange coupling, this reversal process is nucleated at the NT's ends and propagates along its length as predicted by theory.Comment: 8 pages, 4 figure

    The curvature of semidirect product groups associated with two-component Hunter-Saxton systems

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    In this paper, we study two-component versions of the periodic Hunter-Saxton equation and its μ\mu-variant. Considering both equations as a geodesic flow on the semidirect product of the circle diffeomorphism group \Diff(\S) with a space of scalar functions on §\S we show that both equations are locally well-posed. The main result of the paper is that the sectional curvature associated with the 2HS is constant and positive and that 2μ\muHS allows for a large subspace of positive sectional curvature. The issues of this paper are related to some of the results for 2CH and 2DP presented in [J. Escher, M. Kohlmann, and J. Lenells, J. Geom. Phys. 61 (2011), 436-452].Comment: 19 page

    Superconducting quantum interference devices with submicron Nb/HfTi/Nb junctions for investigation of small magnetic particles

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    We investigated, at temperature 4.2K4.2\,\mathrm{K}, electric transport, flux noise and resulting spin sensitivity of miniaturized Nb direct current superconducting quantum interference devices (SQUIDs) based on submicron Josephson junctions with HfTi barriers. The SQUIDs are either of the magnetometer-type or gradiometric in layout. In the white noise regime, for the best magnetometer we obtain a flux noise SΦ1/2=250nΦ0/Hz1/2S_{\Phi}^{1/2}=250\,\mathrm{n}\Phi_0/\mathrm{Hz}^{1/2}, corresponding to a spin sensitivity Sμ1/229μB/Hz1/2S^{1/2}_\mu\,\ge\,29\,\mu_B/\mathrm{Hz}^{1/2}. For the gradiometer we find SΦ1/2=300nΦ0/Hz1/2S_{\Phi}^{1/2}=300\,\mathrm{n}\Phi_0/\mathrm{Hz}^{1/2} and Sμ1/244μB/Hz1/2S^{1/2}_\mu\,\ge\,44\,\mu_B/\mathrm{Hz}^{1/2}. The devices can still be optimized with respect to flux noise and coupling between a magnetic particle and the SQUID, leaving room for further improvement towards single spin resolution.Comment: 4 pages, 3 figure

    Hand antisepsis without decreasing efficacy by shortening the rub-in time of alcohol-based handrubs to 15 seconds

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    BackgroundA previous study among neonatal intensive care unit (NICU) nurses showed that the antibacterial efficacy of alcohol-based handrubs (ABHR) can be achieved in 15 s instead of 30 s with a significant increase in the frequency of hand antisepsis. This study aimed to examine 15-s vs 30-s antisepsis performance by measuring microbial load on fingertips and compliance among nurses in a low-risk gynaecological ward.MethodsAn independent trained observer monitored the frequency and compliance with hand antisepsis during shifts in a crossover design. Fingertips including thumbs were rinsed in soy broth before hand rubbing at the beginning of a shift and then hourly to determine the bacterial load. Performance activity was assigned to the contamination class of the Fulkerson scale. Immediately before the lunch break, volunteers cleaned their hands for a randomly determined application time of 15 or 30 s.ResultsExamination of bacterial load on fingertips revealed no difference between 15 vs 30 s application time. Controlled hand antisepsis before the lunch break also showed no difference in efficacy for either test series. Participants rubbing for 15 s were more likely to perform hand antisepsis compared with those rubbing for 30 s ( P=0.2). The compliance increased from 54.7% to 69.5% in the 15-s trial.DiscussionShortening the duration for hand antisepsis did not decrease efficacy. Shortening the application time to 15 s should be considered within the critical components of a successful multimodal intervention strategy to improve hand-hygiene compliance in clinical practice

    Assessing a risk tailored intervention to prevent disabling low back pain - protocol of a cluster randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>Although most patients with low back pain (LBP) recover within a few weeks a significant proportion has recurrent episodes or will develop chronic low back pain. Several mainly psychosocial risk factors for developing chronic LBP have been identified. However, effects of preventive interventions aiming at behavioural risk factors and unfavourable cognitions have yielded inconsistent results. Risk tailored interventions may provide a cost efficient and effective means to take systematic account of the individual risk factors but evidence is lacking.</p> <p>Methods/Design</p> <p>This study will be a cluster-randomised controlled trial comparing screening and a subsequent risk tailored intervention for patients with low back pain to prevent chronic low back pain compared to treatment as usual in primary care. A total of 600 patients from 20 practices in each study arm will be recruited in Berlin and Goettingen. The intervention comprises the following elements: Patients will be assigned to one of four risk groups based on a screening questionnaire. Subsequently they receive an educational intervention including information and counselling tailored to the risk group. A telephone/email consulting service for back pain related problems are offered independent of risk group assignment. The primary outcomes will be functional capacity and sick leave.</p> <p>Discussion</p> <p>This trial will evaluate the effectiveness of screening for risk factors for chronic low back pain followed by a risk tailored intervention to prevent chronic low back pain. This trial will contribute new evidence regarding the flexible use of individual physical and psychosocial risk factors in general practice.</p> <p>Trial registration</p> <p>ISRCTN 68205910</p

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

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    The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +c¯¯)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−s¯¯¯ quark asymmetry
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