4,756 research outputs found
SLaMA-URM method for the seismic vulnerability assessment of UnReinforced Masonry structures: Formulation and validation for a substructure
An analytical procedure based on the SLaMA (Simplified Lateral Mechanism Analysis) method is proposed for the seismic vulnerability assessment of UnReinforced Masonry (URM) structures. The procedure considers an equivalent frame discretization for the structure (pier, spandrel, and joint elements) and includes: (i) the evaluation of moment‒rotation capacity curves at each pier-spandrel subassembly; (ii) the assessment of the hierarchy of strength in each subassembly; and (iii) the calculation of the structure capacity curve according to the expected failure mechanism. Validation of the proposed SLaMA-URM procedure is achieved in a one-story URM substructure tested under lateral cyclic loading. The analytical predictions are compared with numerical ones from a 2D continuous finite element (FE) model based on a macro-modelling strategy. The flexural capacity of the components is estimated using a monolithic beam analogy, and the results compared with those from traditional sectional analysis. The influence of the substructure geometry on the hierarchy of strength at the subassembly and global levels is investigated. An analytical formulation of the pier-spandrel joint strength is also proposed to be considered in the assessment of the hierarchy of strength. The method is validated for a one-story substructure subjected to lateral in-plane loading. Results, in terms of crack patterns and capacity curves, are in relatively good agreement with the experimental and FE results, even when a bilinear curve approximation is used. The potential of the SLaMA-URM method for the seismic assessment of URM buildings is demonstrated, whose application to a larger URM structure is planned as a subsequent study
Charmonium Suppression by Comover Scattering in Pb+Pb Collisions
The first reports of and production from experiment NA50 at
the CERN SPS are compared to predictions based on a hadronic model of
charmonium suppression. Data on centrality dependence and total cross sections
are in good accord with these predictions.Comment: 9 pages, latex, 6 figures, epsf, figure added and text modified to
clarify result
Caracterização de agroecossistemas baseados na cana de açúcar na comunidade do Caburi, Parintins - Amazonas.
O objetivo deste estudo foi realizar levantamento e sistematizar experiências de agriculturas de base ecológica na comunidade do Caburi, Parintins-AM. Foram selecionadas famílias de forma aleatória cuja amostra fosse representativa da comunidade
Recommended from our members
J/psi production and absorption in p + A and d+Au collisions
The level of 'anomalous' charmonium suppression in high-energy heavy-ion collisions and its interpretation as a signal of quark-gluon plasma formation requires a robust understanding of charmonium production and absorption in proton-nucleus collisions. In a previous study we have shown that, contrary to common belief, the so-called J/{psi} 'absorption cross section', {sigma}{sub abs}{sup J/{psi}}, is not a 'universal constant' but, rather, an effective parameter that depends very significantly on the charmonium rapidity and on the collision energy. Here we present ugraded Glauber calculations with the EPS09 parameterization of nuclear modifications of the parton densities. We confirm that the effective 'absorption cross section' depends on the J/{psi} kinematics and the collision energy. We also make further steps towards understanding the physics of the mechanisms behind the observed 'cold nuclear matter' effects
Temperature dependence of the electron spin g factor in GaAs
The temperature dependence of the electron spin factor in GaAs is
investigated experimentally and theoretically. Experimentally, the factor
was measured using time-resolved Faraday rotation due to Larmor precession of
electron spins in the temperature range between 4.5 K and 190 K. The experiment
shows an almost linear increase of the value with the temperature. This
result is in good agreement with other measurements based on photoluminescence
quantum beats and time-resolved Kerr rotation up to room temperature. The
experimental data are described theoretically taking into account a diminishing
fundamental energy gap in GaAs due to lattice thermal dilatation and
nonparabolicity of the conduction band calculated using a five-level kp model.
At higher temperatures electrons populate higher Landau levels and the average
factor is obtained from a summation over many levels. A very good
description of the experimental data is obtained indicating that the observed
increase of the spin factor with the temperature is predominantly due to
band's nonparabolicity.Comment: 6 pages 4 figure
A microscopic calculation of secondary Drell-Yan production in heavy ion collisions
A study of secondary Drell-Yan production in nuclear collisions is presented
for SPS energies. In addition to the lepton pairs produced in the initial
collisions of the projectile and target nucleons, we consider the potentially
high dilepton yield from hard valence antiquarks in produced mesons and
antibaryons. We calculate the secondary Drell-Yan contributions taking the
collision spectrum of hadrons from the microscopic model URQMD. The
contributions from meson-baryon interactions, small in hadron-nucleus
interactions, are found to be substantial in nucleus-nucleus collisions at low
dilepton masses. Preresonance collisions of partons may further increase the
yields.Comment: 22 pages including 7 figures, submitted to Z. Phys.
Fenologia reprodutiva da andirobeira (Carapa guianensis Aublet.), na região de Parintins - AM.
O estudo da fenologia da espécie Carapa guianensis Aublet foi realizado na comunidade N. S. do Rosário, município de Parintins - AM
J/\Psi production, polarization and Color Fluctuations
The hard contributions to the heavy quarkonium-nucleon cross sections are
calculated based on the QCD factorization theorem and the nonrelativistic
quarkonium model. We evaluate the nonperturbative part of these cross sections
which dominates at GeV at the Cern Super Proton
Synchrotron (SPS) and becomes a correction at TeV at
the CERN Large Hadron Collider (LHC). \J production at the CERN SPS is well
described by hard QCD, when the larger absorption cross sections of the
states predicted by QCD are taken into account. We predict an -dependent
polarization of the states. The expansion of small wave packets is
discussed.Comment: 13 pages REVTEX, 1 table, 2 PostScript, corrected some typo
Reflexões sobre agricultura familiar, inovação e desenvolvimento na Amazônia.
O texto apresenta algumas reflexões sobre o ecossistema amazônico no seu aspecto físico, de exploração e da fragilidade desse ambiente quando se trata de uso dos recursos naturais. Traz para a discussão aspectos da diversidade biológica e sociocultural, bem como os efeitos das políticas governamentais sobre esse ambiente. Enfatiza e caracteriza a agricultura familiar amazônica e suas relações com o ambiente. Analisa a importância dos saberes locais no processo de geração e transferência de tecnologias e a importância de se juntar esses saberes com os conhecimentos científicos. A conjunção dos conhecimentos gera tecnologias adequadas ao ambiente, as quais, por sua vez, geram inovação e desenvolvimento. A participação das pessoas é importante para que ocorra a inovação. Neste aspecto, buscam-se, cada vez mais, metodologias que permitam analisar e inserir as pessoas nos processos de desenvolvimento
Photoproduction at collider energies: from RHIC and HERA to the LHC
We present the mini-proceedings of the workshop on ``Photoproduction at
collider energies: from RHIC and HERA to the LHC'' held at the European Centre
for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento)
from January 15 to 19, 2007. The workshop gathered both theorists and
experimentalists to discuss the current status of investigations of high-energy
photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as
well as preparations for extension of these studies at the LHC. The main
physics topics covered were: (i) small- QCD in photoproduction studies with
protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus
collisions, (ii) hard diffraction physics at hadron colliders, and (iii)
photon-photon collisions at very high energies: electroweak and beyond the
Standard Model processes. These mini-proceedings consist of an introduction and
short summaries of the talks presented at the meeting
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