1,495 research outputs found

    Antiproton annihilation on light nuclei at very low energies

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    The recent experimental data obtained by the OBELIX group on pˉ\bar{p}D and pˉ4\bar{p}^4He total annihilation cross sections are analyzed. The combined analysis of these data with existing antiprotonic atom data allows, for the first time, the imaginary parts of the S-wave scattering lengths for the two nuclei to be extracted. The obtained values are: Ima0sc=[−0.62±0.02(stat)±0.04(sys)]fmIm a^{sc}_0 = [- 0.62 \pm 0.02 ({stat}) \pm 0.04 ({sys})] fm for pˉ\bar{p}D and Ima0sc=[−0.36±0.03(stat)−0.11+0.19(sys)]fmIm a^{sc}_0 = [- 0.36\pm 0.03({stat})^{+0.19}_{-0.11}({sys})] fm for pˉ4\bar{p}^4He. This analysis indicates an unexpected behaviour of the imaginary part of the pˉ\bar{p}-nucleus S-wave scattering length as a function of the atomic weight A: ∣Ima0sc∣|Im a^{sc}_0| (pˉ\bar{p}p) > ∣Ima0sc∣|Im a^{sc}_0| (pˉ\bar{p}D) > ∣Ima0sc∣|Im a^{sc}_0| (pˉ4\bar{p}^4He).Comment: 13 pages, 5 figure

    Duo: a general program for calculating spectra of diatomic molecules

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    Duo is a general, user-friendly program for computing rotational, rovibrational and rovibronic spectra of diatomic molecules. Duo solves the Schr\"{o}dinger equation for the motion of the nuclei not only for the simple case of uncoupled, isolated electronic states (typical for the ground state of closed-shell diatomics) but also for the general case of an arbitrary number and type of couplings between electronic states (typical for open-shell diatomics and excited states). Possible couplings include spin-orbit, angular momenta, spin-rotational and spin-spin. Corrections due to non-adiabatic effects can be accounted for by introducing the relevant couplings using so-called Born-Oppenheimer breakdown curves. Duo requires user-specified potential energy curves and, if relevant, dipole moment, coupling and correction curves. From these it computes energy levels, line positions and line intensities. Several analytic forms plus interpolation and extrapolation options are available for representation of the curves. Duo can refine potential energy and coupling curves to best reproduce reference data such as experimental energy levels or line positions. Duo is provided as a Fortran 2003 program and has been tested under a variety of operating systems

    Avaliação de genótipos de milho no município de Brasiléia-Acre.

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    A cultura do milho no município de Brasiléia, assume significa tiva relevância sócio-econômica, contribuindo com 20,65% na produção global do Estado (CEPA/1988). Além de ser utilizado na alimentação humana e ração animal, o excedente da produção tem sido comercializado no mercado local, em Rio Branco e Cobija, cidade frobteiriça (Bolivia). A cultura apresenta problemas diversos: cultivares pouco produtivas, cultivo em consorcio, grandes espaçamentos entre plantas, cultivares de grande porte, índices elevados de acamamento, doenças, ocorrência de baixa produtividade. Estes problemas têm constituído em fatores limitantes a oferta de milho ao mercado, além de resultar no baixo retorno econômico da pequena produção. Com o objetivo de selecionar cultivares mais produtivas e resistentes aos principais problemas da região, a UEPAE de Rio Branco vem desenvolvendo trabalhos no Núcleo de Pesquisa -Quixadá, localizado em Brasiléia.bitstream/item/117388/1/1158.pd

    Distance measurement by delayed optical feedback in a ring laser

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    We numerically study the behavior of a semiconductor ring laser subject to bidirectional delayed optical feedback, when the isolated laser is in the quasi-unidirectional regime. The optical feedback, provided by two external refectors located in front of the ring output waveguides, can modify the laser regime produced by the cross-saturation between the clockwise and the counter-clockwise mode. Thus, the system exhibits new diferent regimes, most of which are asymmetric and bidirectional, with alternating dominant mode. Two of these regimes are of special interest in view of applications, because the laser switching period, between the clockwise and the counter-clockwise mode, is linearly related to the time of fight from the laser to one or both refectors. In these operating conditions, the laser is thus suitable to implement a telemeter. A convenient electrical output signal is obtained by a photodiode located behind one (partially refecting) fxed mirror, or by measuring the voltage drop across the laser junction. Simulations are performed by mathematical models based on rate-equations, assuming typical literature parameters for a 1 mW ring laser

    World Workshop on Oral Medicine VII : What participants perceive as important

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    Our objective was to identify which aspects of World Workshop on Oral Medicine (WWOM) participation were perceived as significant for participants\u2019 professional development. Online survey was sent to previous WWOM participants. Qualitative analysis of participants\u2019 responses to an open-ended question was performed. Fifty-two WWOM participants responded. Nearly three quarters of respondents (72.3%) felt that participation in the WWOM helped their career. A high percentage of respondents (67.3%) provided answers that fell under the domains of international collaboration, followed by personal academic benefits (48%). Overall, the results indicate that WWOM participation played an important role in individual's professional development. We identified aspects of WWOM involvement that the participants perceived as important. This information will be used for the development of an objective instrument for measuring impact of WWOM on participant's professional path

    ArCo: the Italian Cultural Heritage Knowledge Graph

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    ArCo is the Italian Cultural Heritage knowledge graph, consisting of a network of seven vocabularies and 169 million triples about 820 thousand cultural entities. It is distributed jointly with a SPARQL endpoint, a software for converting catalogue records to RDF, and a rich suite of documentation material (testing, evaluation, how-to, examples, etc.). ArCo is based on the official General Catalogue of the Italian Ministry of Cultural Heritage and Activities (MiBAC) - and its associated encoding regulations - which collects and validates the catalogue records of (ideally) all Italian Cultural Heritage properties (excluding libraries and archives), contributed by CH administrators from all over Italy. We present its structure, design methods and tools, its growing community, and delineate its importance, quality, and impact
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