Navegação Ciências Exatas e da Terra por Título
Resultados 784-803 de 5955
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Co-cubstitution effects on the Fe valence in the BaFe2As2 superconducting compound : a study of hard x-ray absorption spectroscopy
(2011) [Artigo de periódico]The Fe K x-ray absorption near edge structure of BaFe₂-xCoxAs₂ superconductors was investigated. No appreciable alteration in shape or energy position of this edge was observed with Co substitution. This result provides ... -
Coeficiente de fidedignidade de um instrumento de medida
(1992) [Artigo de periódico] -
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Coexistence and crossover phenomena in a Fermi-like model of particles in counterflowing streams
(2020) [Artigo de periódico]In this work, we propose a two-dimensional extension of a previously defined one-dimensional version of a model of particles in counterflowing streams, which considers an adapted Fermi-Dirac distribution to describe the ... -
Coexistence of halloysite and kaolinite: a study on the genesis of kaolin clays of Campo Alegre basin, Santa Catarina State, Brazil
(2007) [Artigo de periódico]O caolim da Bacia de Campo Alegre, Estado de Santa Catarina, Brasil, formou-se da alteração de rochas vulcânicas ácidas. A haloisita predomina na fração argila da matriz do corpo de caolim, enquanto a caolinita, de baixa ... -
Coherence and incoherence in extended broadband triplet interaction
(2008) [Artigo de periódico]We study the transition from coherent to incoherent dynamics in a nonlinear triplet of broadband combs of waves. Expanding the analysis of previous works, we investigate what happens when the band of available modes is ... -
Coherence–incoherence transition in nonlinear wave interactions
(2005) [Artigo de periódico]In this paper we analyze the transition from coherent to incoherent wave dynamics in a broad-band triplet interaction, where, in contrast to previous models, wave vector selection rules are imposed on the nonlinear terms ... -
Coherence in scale-free networks of chaotic maps
(2004) [Artigo de periódico]We study fully synchronized states in scale-free networks of chaotic logistic maps as a function of both dynamical and topological parameters. Three different network topologies are considered: (i) a random scalefree ... -
Coherent and incoherent production of vector mesons in ultraperipheral collisions of xenon ions within the QCD parton saturation approach
(2018) [Artigo de periódico]In this paper, we analyze the exclusive vector meson photoproduction in the recent run using xenon ions at energy of 5.44 TeV performed by the Large Hadron Collider. We focus on the ultraperipheral collisions and provide ... -
Coherent and incoherent radiation from free-electron lasers with an axial guide field
(1981) [Artigo de periódico]The spontaneous and induced emission from a free-electron laser is treated for the case in which an axial magnetic field is imposed in addition to the helical, axially periodic wiggler magnetic field. The classes of possible ... -
Coherent and incoherent Upsilon production in ultraperipheral collisions at the Large Hadron Collider
(2017) [Artigo de periódico]The exclusive photoproduction of ϒðnSÞ states was calculated in ultraperipheral collisions for coherent and incoherent process in PbPb at sNN p ¼ 5.5 TeV. Different dipole models were compared in the theoretical framework ... -
Coherent J/ψ and ψ' photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at √sNN = 5.02 TeV
(2021) [Artigo de periódico]The coherent photoproduction of J/ψ and ψ' mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy √sNN = 5.02 TeV with the ALICE detector. Charmonia are detected in the central rapid ity region ... -
Coherent J/ψ photoproduction at forward rapidity in ultra-peripheral Pb–Pb collisions at √sNN=5.02 TeV
(2019) [Artigo de periódico]The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy √sNN=5.02 TeV. The J/ψ is detected via its dimuon ... -
Coherent photon-hadron interactions in pA collisions : small-x physics after HERA
(2006) [Artigo de periódico]In this paper we study the photoproduction of heavy quarks and vector mesons in the coherent proton-nucleus (pA) interactions for RHIC and LHC energies and analyze if these processes can be used to determine the QCD dynamics ... -
Coherent photoproduction of ρ0 vector mesons in ultra-peripheral Pb-Pb collisions at √sNN = 5.02 TeV
(2020) [Artigo de periódico]Cross sections for the coherent photoproduction of ρ0 vector mesons in ultra-peripheral Pb-Pb collisions at sNN√ = 5.02 TeV are reported. The measurements, which rely on the π+π− decay channel, are presented in three regions ... -
Cohort study protocol of the Brazilian collaborative research network on COVID-19 : strengthening WHO global data
(2022) [Artigo de periódico]Introduction: with the COVID-19 pandemic, hospitals in low-income countries were faced with a triple challenge. First, a large number of patients required hospitalisation because of the infection’s more severe symptoms. ... -
Cold-fluid equilibrium for a corkscrewing elliptic beam in a variably focusing channel
(2000) [Artigo de periódico]It is shown that there exists a new class of cold-fluid corkscrewing elliptic beam equilibria for ultrahigh-brightness, space-charge-dominated beam propagation through a linear focusing channel consisting of uniform ... -
Cold molecular gas outflow encasing the ionized one in the Seyfert galaxy NGC 3281
(2023) [Artigo de periódico]We present ALMA CO (2-1) observations of the Seyfert 2 galaxy NGC 3281 at ∼100 pc spatial resolution. This galaxy was previously known to present a bi-conical ionized gas outflow extending to 2 kpc from the nucleus. The ... -
Colisão com o 'efeito estilingue'
(2010) [Artigo de periódico]Abordamos teoricamente a colisão com o 'efeito estilingue' onde um corpo transfere momento linear e energia cinética para um segundo corpo de massa menor, fazendo com que a energia mecânica desse segundo corpo cresça de ... -
Collective effects on the operation of free-eletron lasers with an axial guide field
(1982) [Artigo de periódico]The collective interaction in a free-electroii laser with combined helical wiggler and uniform axial guide fields is presented in the linearized regime. The analysis involves a perturbation of the Vlasov-Maxwell equations ...