3,742 research outputs found

    A cultura do arroz de sequeiro no Brasil: problemas e perspectivas.

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    A produção brasileira de arroz esta concentrada, principalmente, nas regiões Centro-Oeste, Sudeste e Sul. Na região Nordeste destaca-se apenas o Maranhão como grande produtor. No ano agrícola de 77/78, a produção brasileira de arroz foi cerca de 7,5 milhões de toneladas, obtidas em aproximadamente 5,6 milhões de hectares, com a produtividade média de 1.340 kg por hectare. Desta produção, aproximadamente 91,2% ou 6.842.000 toneladas foram produzidas nos estados do Rio Grande do Sul, Mato Grosso do Sul, Maranhão, Mato Grosso, Minas Gerais, Goiás, Santa Catarina, São Paulo e Paraná. No Rio Grande do Sul e Santa Catarina, predomina o sistema de cultivo de arroz com irrigação por inundação, enquanto que nos Estados de Mato Grosso, Mato Grosso do Sul, Maranhão, Minas Gerais, Goiás, São Paulo e Paraná, o sistema predominante é o de sequeiro

    Spin-dependent charge transfer at chiral electrodes probed by magnetic resonance

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    Chirality-induced spin selectivity is evidenced by exciting the spin resonance of radicals in an electrochemical cell where the working electrode is covered with a chiral self-assembled monolayer. Because the electron transfer to and from the paramagnetic radical is spin dependent, the electrochemical current changes at resonance. This electrically-detected magnetic resonance (EDMR) is monitored by a lock-in detection based on electrode voltage modulation, at a frequency that optimizes the sensitivity of the differential conductance to the electrode charge transfer process. The method is validated using p-doped GaAs electrodes in which the conduction band electrons are hyperpolarized by a well-known method of optical spin pumping with circularly polarized light. Gold electrodes covered with peptides consisting of 5 alanine groups (Al5) present a relative current change of up to 5 × 10-5 when the resonance condition is met, corresponding to a spin filtering efficiency between 6 and 19%

    Report of the Stripe Analysis of the Off-Campus Activities of the International Agricultural Research Centers

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    Report prepared by three consultants and the TAC Secretariat on off-campus activities of the CGIAR centers. The report classifies these activities, under the headings of international testing programs, national projects, regional programs, off campus core research, collaborative research, collection of information and data, germplasm collection, preservation and utilization, training and consultations. Included in the file is a compendium prepared by the TAC Secretariat of off campus activities at each center, based on center submissions. Agenda document, CGIAR meeting, October 1980. Also considered at TAC 23rd and 24th Meetings in February and July 198

    A mobile data acquisition system

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    A mobile data aquisition (MobiDAQ) was developed for the ATLAS central hadronic calorimeter (TileCal). MobiDAQ has been designed in order to test the functionalities of the TileCal front-end electronics and to acquire calibration data before the final back-end electronics were built and tested. MobiDAQ was also used to record the first cosmic ray events acquired by an ATLAS subdetector in the underground experimental area

    Mitigating Hypothetical Bias Evidence on the Effects of Correctives from a Large Field Study

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    The overestimation of willingness-to-pay (WTP) in hypothetical responses is a wellknown finding in the literature. Various techniques have been proposed to remove or, at least, reduce this bias. Using responses from a panel of about 6,500 German households on their WTP for a variety of power mixes, this article undertakes an analysis that combines two common ex-ante approaches - cheap talk and consequential script - with the ex-post certainty approach to calibrating hypothetical WTP responses. Based on a switching regression model that accounts for the potential endogeneity of respondent certainty, we find that while neither the cheap-talk nor the consequential script corrective bears on the estimates of WTP, there is evidence for a lower WTP among those respondents who classify themselves as definitely certain about their answers.Die Überschätzung von Zahlungsbereitschaften in hypothetischen Befragungssituationen ist ein in der Literatur wohlbekanntes Phänomen. Um diese Verzerrungen zu verhindern oder zumindest zu reduzieren, wurden verschiedene Ansätze vorgeschlagen, darunter die Cheap Talk und Consequential Script genannten Ex-Ante Ansätze sowie ein als Sicherheits-Ansatz bezeichnetes Ex-Post-Korrektiv. Auf Grundlage einer Befragung von etwa 6.500 deutschen Haushalten zu ihrer Zahlungsbereitschaft für verschiedene Strommixe analysiert dieser Artikel die Effektivität dieser Korrektive. Basierend auf einem Switching-Regression-Model, welches die potenzielle Endogenität der Sicherheit der Befragten berücksichtigt, finden wir empirische Evidenz dafür, dass sich weder Cheap Talk noch der Consequential-Script Ansatz auf die geschätzten Zahlungsbereitschaften auswirkt. Es findet sich jedoch eine geringere Zahlungsbereitschaft unter solchen Antwortenden, die sich selbst als ganz sicher in Bezug auf ihre Antworten einstufen

    Interleukin-23-Independent IL-17 Production Regulates Intestinal Epithelial Permeability

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    SummaryWhether interleukin-17A (IL-17A) has pathogenic and/or protective roles in the gut mucosa is controversial and few studies have analyzed specific cell populations for protective functions within the inflamed colonic tissue. Here we have provided evidence for IL-17A-dependent regulation of the tight junction protein occludin during epithelial injury that limits excessive permeability and maintains barrier integrity. Analysis of epithelial cells showed that in the absence of signaling via the IL-17 receptor adaptor protein Act-1, the protective effect of IL-17A was abrogated and inflammation was enhanced. We have demonstrated that after acute intestinal injury, IL-23R+ γδ T cells in the colonic lamina propria were the primary producers of early, gut-protective IL-17A, and this production of IL-17A was IL-23 independent, leaving protective IL-17 intact in the absence of IL-23. These results suggest that IL-17-producing γδ T cells are important for the maintenance and protection of epithelial barriers in the intestinal mucosa

    Study of Zγ events and limits on anomalous ZZγ and Zγγ couplings in pp̄ collisions at s=1.96TeV

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    We present a measurement of the Zγ production cross section and limits on anomalous ZZγ and Zγγ couplings for form-factor scales of Λ=750 and 1000 GeV. The measurement is based on 138 (152) candidates in the eeγ (μμγ) final state using 320(290)pb-1 of pp̄ collisions at s=1.96TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are |h10,30Z|<0.23, |h20,40Z|<0.020, |h10,30γ|<0.23, and |h20,40γ|<0.019 for Λ=1000GeV. © 2005 The American Physical Society

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for the standard model Higgs boson at LEP

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