Semiclassical Tunneling of Wavepackets with Real Trajectories

Semiclassical approximations for tunneling processes usually involve complex trajectories or complex times. In this paper we use a previously derived approximation involving only real trajectories propagating in real time to describe the scattering of a Gaussian wavepacket by a finite square potential barrier. We show that the approximation describes both tunneling and interferences very accurately in the limit of small Plank's constant. We use these results to estimate the tunneling time of the wavepacket and find that, for high energies, the barrier slows down the wavepacket but that it speeds it up at energies comparable to the barrier height.Comment: 23 pages, 7 figures Revised text and figure

Utilização da mandioca na indústria de compensados de madeira.

bitstream/item/28293/1/ComTec80.pd

Semiclassical coherent state propagator for systems with spin

We derive the semiclassical limit of the coherent state propagator for systems with two degrees of freedom of which one degree of freedom is canonical and the other a spin. Systems in this category include those involving spin-orbit interactions and the Jaynes-Cummings model in which a single electromagnetic mode interacts with many independent two-level atoms. We construct a path integral representation for the propagator of such systems and derive its semiclassical limit. As special cases we consider separable systems, the limit of very large spins and the case of spin 1/2.Comment: 19 pages, no figure

A conjugate for the Bargmann representation

In the Bargmann representation of quantum mechanics, physical states are mapped into entire functions of a complex variable z*, whereas the creation and annihilation operators $\hat{a}^\dagger$ and $\hat{a}$ play the role of multiplication and differentiation with respect to z*, respectively. In this paper we propose an alternative representation of quantum states, conjugate to the Bargmann representation, where the roles of $\hat{a}^\dagger$ and $\hat{a}$ are reversed, much like the roles of the position and momentum operators in their respective representations. We derive expressions for the inner product that maintain the usual notion of distance between states in the Hilbert space. Applications to simple systems and to the calculation of semiclassical propagators are presented.Comment: 15 page

Impactos do estresse sobre a produção animal.

No presente trabalho são destacadas as respostas endocrinológicas ao estresse, como o aumento da secreção de cortisol, que prepara o indivíduo para enfrentar situações adversas. São também abordados aspectos inerentes ao estresse sobre as funções produtivas, reprodutivas e imunológicas.bitstream/CNPC/20752/1/doc70.pd

Variação genética e ganho esperado na seleção de progênies de Pinus caribaea var. caribaea em Selvíria, MS.

No presente trabalho propôs-se quantificar a variação genética para caracteres de crescimento e estimar possíveis ganhos na seleção, a partir da utilização do índice multi-efeitos (IME), visando a transformação do teste de progênies P. caribaea var. caribaea em um pomar de sementes. O teste de progênies de Pinus caribaea var. caribaea foi implantado no município de Selvíria-MS. O delineamento experimental utilizado foi látice 10x10 triplo, com 99 progênies e uma testemunha comercial, em parcelas lineares com dez plantas, no espaçamento 3 m x 3 m. Os caracteres quantitativos altura total de plantas, diâmetro à altura do peito (DAP), volume, forma do fuste das árvores e sobrevivência das progênies foram avaliados aos 14, 15 e 16 anos de idade, sendo que aos 14 anos foi realizado um desbaste de 50% de intensidade. As variáveis foram analisadas pela metodologia do modelo linear misto. A variação genética encontrada para os caracteres analisados não foi significativa. As estimativas de herdabilidade apresentaram baixa magnitude e pouca variação para as diferentes idades. Aplicação do IME ao caráter DAP, dois anos após desbaste, proporcionou maiores ganhos do que a seleção entre e dentro de progênies. A melhor estratégia de seleção visando maiores ganhos e manter a diversidade genética é selecionar no máximo cinco indivíduos por progênies

A framework for natural animation of digitized models

We present a novel versatile, fast and simple framework to generate highquality animations of scanned human characters from input motion data. Our method is purely mesh-based and, in contrast to skeleton-based animation, requires only a minimum of manual interaction. The only manual step that is required to create moving virtual people is the placement of a sparse set of correspondences between triangles of an input mesh and triangles of the mesh to be animated. The proposed algorithm implicitly generates realistic body deformations, and can easily transfer motions between human erent shape and proportions. erent types of input data, e.g. other animated meshes and motion capture les, in just the same way. Finally, and most importantly, it creates animations at interactive frame rates. We feature two working prototype systems that demonstrate that our method can generate lifelike character animations from both marker-based and marker-less optical motion capture data

Coherent State Path Integrals in the Weyl Representation

We construct a representation of the coherent state path integral using the Weyl symbol of the Hamiltonian operator. This representation is very different from the usual path integral forms suggested by Klauder and Skagerstan in \cite{Klau85}, which involve the normal or the antinormal ordering of the Hamiltonian. These different representations, although equivalent quantum mechanically, lead to different semiclassical limits. We show that the semiclassical limit of the coherent state propagator in Weyl representation is involves classical trajectories that are independent on the coherent states width. This propagator is also free from the phase corrections found in \cite{Bar01} for the two Klauder forms and provides an explicit connection between the Wigner and the Husimi representations of the evolution operator.Comment: 23 page

Semiclassical Propagation of Wavepackets with Real and Complex Trajectories

We consider a semiclassical approximation for the time evolution of an originally gaussian wave packet in terms of complex trajectories. We also derive additional approximations replacing the complex trajectories by real ones. These yield three different semiclassical formulae involving different real trajectories. One of these formulae is Heller's thawed gaussian approximation. The other approximations are non-gaussian and may involve several trajectories determined by mixed initial-final conditions. These different formulae are tested for the cases of scattering by a hard wall, scattering by an attractive gaussian potential, and bound motion in a quartic oscillator. The formula with complex trajectories gives good results in all cases. The non-gaussian approximations with real trajectories work well in some cases, whereas the thawed gaussian works only in very simple situations.Comment: revised text, 24 pages, 6 figure