9,340 research outputs found
Loose mechanochemical coupling of molecular motors
In living cells, molecular motors convert chemical energy into mechanical
work. Its thermodynamic energy efficiency, i.e. the ratio of output mechanical
work to input chemical energy, is usually high. However, using two-state
models, we found the motion of molecular motors is loosely coupled to the
chemical cycle. Only part of the input energy can be converted into mechanical
work. Others is dissipated into environment during substeps without
contributions to the macro scale unidirectional movement
Multi-critical point in a diluted bilayer Heisenberg quantum antiferromagnet
The S=1/2 Heisenberg bilayer antiferromagnet with randomly removed
inter-layer dimers is studied using quantum Monte Carlo simulations. A
zero-temperature multi-critical point (p*,g*) at the classical percolation
density p=p* and inter-layer coupling g* approximately 0.16 is demonstrated.
The quantum critical exponents of the percolating cluster are determined using
finite-size scaling. It is argued that the associated finite-temperature
quantum critical regime extends to zero inter-layer coupling and could be
relevant for antiferromagnetic cuprates doped with non-magnetic impurities.Comment: 4 pages, 6 figures. v2: only minor changes; accepted for publication
in Phys. Rev. Let
Spontaneous alloying in binary metal microclusters - A molecular dynamics study -
Microcanonical molecular dynamics study of the spontaneous alloying(SA),
which is a manifestation of fast atomic diffusion in a nano-sized metal
cluster, is done in terms of a simple two dimensional binary Morse model.
Important features observed by Yasuda and Mori are well reproduced in our
simulation. The temperature dependence and size dependence of the SA phenomena
are extensively explored by examining long time dynamics. The dominant role of
negative heat of solution in completing the SA is also discussed. We point out
that a presence of melting surface induces the diffusion of core atoms even if
they are solid-like. In other words, the {\it surface melting} at substantially
low temperature plays a key role in attaining the SA.Comment: 15 pages, 12 fgures, Submitted to Phys.Rev.
Mineração de textos aplicada à análise de dados de expressão gênica por microarranjos.
Este trabalho se insere no projeto "Rede Genômica Animal" e tem por objetivo construir uma ferramenta que utilize técnicas de mineração de textos para apoiar a interpretação biológica de dados de experimentos de expressão gênica. Por isso, os dados de expressão gênica a serem utilizados para validação da ferramenta são aqueles gerados no escopo do projeto "Rede Genômica Animal", referente ao organismo Bos taurus
Eutils-search - manual do usuário.
O software Eutils-search tem por objetivo trazer do banco de dados PubMed informações sobre artigos relacionados a genes de um organismo especĂfico, de acordo com as regras referentes Ă taxa de acesso impostas pelo site. As informações trazidas sĂŁo, entĂŁo, armazenadas localmente em um banco de dados para acesso rápido. AlĂ©m disso, o software tambĂ©m gera documentos XML correspondentes Ă s informações do organismo requisitado. O eutils-search Ă© uma ferramenta de apoio ao desenvolvimento de aplicações de mineração de textos voltadas para os domĂnios de biotecnologia e biologia molecular, baseada em informações textuais obtidas do banco de dados PubMed. Este documento apresenta os prĂ©-requisitos e a descrição dos parâmetros necessários para utilização do software, bem como uma descrição de alguns aspectos internos do software, para melhor entendimento do processo que ele automatiza, alĂ©m de alguns exemplos e uso.bitstream/item/31573/1/doc106-10.pd
Lifetime measurement of the ^3P_2 metastable state of strontium atoms
We have measured the lifetime of the 5s5p ^3P_2 metastable state of strontium
atoms by magneto-optically trapping the decayed atoms to the ground state,
which allowed sensitive detection of the rare decay events. We found that the
blackbody radiation-induced decay was the dominant decay channel for the state
at T = 300 K. The lifetime was determined to be 500^{+280}_{-130} s in the
limit of zero temperature.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
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