6,095 research outputs found
Finite size and finite temperature studies of the spin chain
We study a quantum spin chain invariant by the superalgebra . We
derived non-linear integral equations for the row-to-row transfer matrix
eigenvalue in order to analyze its finite size scaling behaviour and we
determined its central charge. We have also studied the thermodynamical
properties of the obtained spin chain via the non-linear integral equations for
the quantum transfer matrix eigenvalue. We numerically solved these NLIE and
evaluated the specific heat and magnetic susceptibility. The analytical low
temperature analysis was performed providing a different value for the
effective central charge. The computed values are in agreement with the
numerical predictions in the literature.Comment: 26 pages, 2 figure
Tunneling effects on impurity spectral function in coupled asymmetric quantum wires
The impurity spectral function is studied in coupled double quantum wires at
finite temperatures. Simple anisotropy in the confinement direction of the
wires leads to finite non-diagonal elements of the impurity spectral function
matrix. These non-diagonal elements are responsible for tunneling effects and
result in pronounced extra peak in the impurity spectral function up to
temperatures as high as 20 K.Comment: Accepted in Phys. Rev.
A marcha humana: uma abordagem biomecânica
A análise biomecânica da marcha engloba, entre outros, dados cinemáticos, cinéticos e sinais electromiográficos, que, em conjunto, promovem a descrição do fenómeno da marcha.
Neste trabalho é efectuada uma revisão dos estudos existentes que versam sobre os aspectos biomecânicos da marcha, de forma a perceber-se os componentes a ter em consideração na referida análise, bem como os modelos comuns que suportam achados experimentais.
A análise efectuada permitiu verificar que a necessidade de redirecção da velocidade do centro de massa entre passos prediz um forte componente do dispêndio energético na marcha e que este, por sua vez, está associado à velocidade.The biomechanical analysis of gait involves, among others, kinematic, kinetic and electromyographic signals, which, together, allow describing the gait phenomenon.
This paper reviews studies focusing on the biomechanical aspects of gait, in order to understand which components must be considered in that analysis and the models supporting experimental findings.
The analysis performed showed that the need to redirect the center of mass speed between steps predicts a strong component of energy expenditure in gait and that this is associated with speed
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