Semiclassical dynamics of domain walls in the one-dimensional Ising ferromagnet in a transverse field

We investigate analytically and numerically the dynamics of domain walls in a spin chain with ferromagnetic Ising interaction and subject to an external magnetic field perpendicular to the easy magnetization axis (transverse field Ising model). The analytical results obtained within the continuum approximation and numerical simulations performed for discrete classical model are used to analyze the quantum properties of domain walls using the semiclassical approximation. We show that the domain wall spectrum shows a band structure consisting of 2$S$ non-intersecting zones.Comment: 15 pages, 9 figure

Comportamento ingestivo de cordeiros alimentados com dietas contendo a inclusão de farelo de castanha de caju.

O presente estudo foi conduzido com o objetivo de avaliar a influência de dietas contendo ou não a inclusão de farelo de castanha de caju (FCC) fornecido a cordeiros de diferentes grupos genéticos (½ sangue Dorper x SRD, ½ sangue Somalis x SRD e ½ sangue Santa Inês x SRD) sobre o comportamento ingestivo de dietas experimentais isoenergéticas e isoprotéicas contendo o referido subproduto. 18 ovinos machos inteiros foram alojados em gaiolas de metabolismo onde permaneceram durante todo o período experimental recebendo duas dietas experimentais. A dieta controle, constituída de feno de capim Aruana (Panicum maximum cv. Aruana), milho e farelo de soja. A dieta teste, constituída dos mesmos ingredientes da dieta controle mais a adição do FCC como substituto parcial do milho e do farelo de soja. As avaliações de comportamento foram feitas em um intervalo de 24 horas em medições realizadas a cada cinco minutos. O delineamento utilizado foi o inteiramente casualisado, com três repetições por ratamento. As análises estatísticas foram realizadas mediante o uso do software SAEG 8.0 e as médias foram comparadas pelo teste SNK em nível de 5% de significância. Houve interação (P<0,05) entre grupos genéticos e dietas experimentais para os tempos de ruminação. Os tempos de ruminação siferiram entre os grupos genéticos (P<0,05), sendo verificados menores tempos de ruminação para os animais ½ sangue Santa Inês x SRD nas dietas com a inclusão de FCC. Para as dietas sem a inclusão de FCC os animais ½ sangue Dorper x SRD obtiveram os menores tempos de ruminação em relação aos animais ½ sangue Somalis x SRD, sendo ambos semelhantes aos animais ½ Santa Inês x SRD. Verificou-se também, que os animais ½ sangue Somalis x SRD e ½ sangue Santa Inês x SRD foram menos eficientes ao realizarem ruminação (%MS). A redução de consumo nas dietas com a inclusão de FCC reduziu o tempo de ruminação notadamente nos animais ½ sangue Santa Inês x SRD. Os animais ½ sangue Dorper x SRD foram mais eficientes na ruminação do que os animais ½ sangue Somalis x SRD e ½ sangue Santa Inês x SRD. Ingestive behavior of lambs fed diets containing the inclusion of cashew nuts meal. This study aimed to evaluate the influence of diets with or without cashew nuts meal (CNM) offered to the lambs of different genetic groups (½ Dorper x ½ native sheep, ½ Somalis x ½ native sheep and ½ Santa Inês x ½ native sheep) on the ingestive behavior of diets isoenergetics and isoproteics. Eighteen male sheep, had been allocated in metalic cages where remained during every experimental period receiving two experimental diets. The control diet consisted of hay of Aruana grass (Panicum maximum cv. Aruana), corn and soybean meal. The test diet was constituted for the same ingredients of control diet plus cashew nuts meal (CNM) that was included in partial substitution to the corn and soybean meal. Evaluations of behavior were made at an interval of 24 hours of measurements taken every five minutes. The experimental design was completely randomized with three replicates per treatment. Statistical analysis was done by using the software SAEG 8.0 and means were compared by SNK test at 5% level of significance. There was interaction (P<0.05) between genotypes and diets for the rumination time. The rumination time differ between the genetic groups (P<0.05), where less times was observed for ruminating animals ½ Santa Inês x ½ native sheep in diets with FCC. For diets without FCC, the animal ½ Dorper x ½ native sheep had the lower rumination time that animals ½ Somalis x ½ native sheep, both similar the ½ Santa Inês x ½ native sheep. It was verified also for the genetic groups ½ Somalis x ½ native sheep and ½ Santa Inês x ½ native sheep lower feeding and rumination efficiencies (DM). The reducing intake in the diets with CNM reduced the time of rumination especially in ½ Santa Inês lambs. The ½ Dorper x ½ native sheep lambs were more efficient than ½ Somalis and ½ Santa Inês lambs in rumination

Conservation laws for self-adjoint first order evolution equations

In this work we consider the problem on group classification and conservation laws of the general first order evolution equations. We obtain the subclasses of these general equations which are quasi-self-adjoint and self-adjoint. By using the recent Ibragimov's Theorem on conservation laws, we establish the conservation laws of the equations admiting self-adjoint equations. We illustrate our results applying them to the inviscid Burgers' equation. In particular an infinite number of new symmetries of these equations are found and their corresponding conservation laws are established.Comment: This manuscript has been accepted for publication in Journal of Nonlinear Mathematical Physic

Running coupling in Yang-Mills theory - a flow equation study -

The effective average action of Yang-Mills theory is analyzed in the framework of exact renormalization group flow equations. Employing the background-field method and using a cutoff that is adjusted to the spectral flow, the running of the gauge coupling is obtained on all scales. In four dimensions and for the gauge groups SU(2) and SU(3), the coupling approaches a fixed point in the infrared.Comment: 35 pages, 3 figures, v2: References added, minor improvements, version to appear in PR

The geodesic structure of the Schwarzschild Anti-de Sitter black hole

In the present work we found the geodesic structure of an AdS black hole. By means of a detailed analyze of the corresponding effective potentials for particles and photon, we found all the possible motions which are allowed by the energy levels. Radial and non radial trajectories were exactly evaluated for both geodesics. The founded orbits were plotted in order to have a direct visualization of the allowed motions. We show that the geodesic structure of this black hole presents new type of motions not allowed by the Schwarzschild spacetime.Comment: 17 pages, 11 figure

Deppining of a Superfluid Vortex Inside a Circular Defect

In this work we study the process of depinning of a quantum of circulation trapped inside a disk by an applied two dimensional superflow. We use the Gross-Pitaevskii model to describe the neutral superfluid. The collective coordinate dynamics is derived directly from the condensate equation of motion, the nonlinear Schroedinger equation, and it is used to obtain an expression for the critical velocity as a function of the defect radius. This expression is compared with a numerical result obtained from the time independent nonlinear Schroedinger equation. Below the critical velocity, we obtain the dependence of the semiclassical nucleation rate with the flow velocity at infinity. Above the critical velocity, the classical vortex depinning is illustrated with a numerical simulation of the time dependent nonlinear Schroedinger equation.Comment: 8 pages, 5 figures, uses revtex and epsf.st

Arecibo Pulsar Survey Using ALFA. I. Survey Strategy and First Discoveries

We report results from the initial stage of a long-term pulsar survey of the Galactic plane using the Arecibo L-band Feed Array (ALFA), a seven-beam receiver operating at 1.4 GHz with 0.3 GHz bandwidth. The search targets Galactic latitudes |b| < 5 deg in the longitude ranges 32 deg < l < 77 deg and 168 deg < l < 77 deg. Data discussed here were collected over a 100 MHz passband centered on 1.42 GHz using a spectrometer that recorded 256 channels every 64 microsec. In a preliminary, standard period-DM analysis, we have detected 29 previously known pulsars and discovered 11 new ones. One of these, with a period of 69 ms and a low characteristic age of 82 kyr, is a plausible candidate for association with the unidentified EGRET source 3EG J1928+1733. Another is a non-recycled pulsar in a relativistic binary with orbital period of 3.98 hr. We also search the data for isolated dispersed pulses, a technique that yielded discovery of an extremely sporadic radio emitter with a spin period of 1.2 s. Simulations we have carried out indicate that about 1000 new pulsars will be found in the ALFA survey. In addition to providing a large sample for use in population analyses and for probing the magnetoionic interstellar medium, the survey maximizes the chances of finding rapidly spinning millisecond pulsars and pulsars in compact binary systems. Our search algorithms will exploit the multiple data streams from ALFA to discriminate between radio frequency interference and celestial signals, including pulsars and possibly new classes of transient radio sources.Comment: 10 pp, 9 figures, accepted by the Astrophysical Journa

Plantações com espécies florestais/clones em monocultivos e sistema iLPF no bioma Cerrado.

1. Apresentação. 2. Experiências de cultivo com espécies florestais/clones em monocultivos e sistemas iLPF no Bioma Cerrado. 3. Considerações Finais

Importância em se conhecer o tipo de solo e as particularidades da adubação em áreas de cerrado.

1. Características dos solos do Bioma Cerrado. 2. Adubação para cultivos em áreas do Bioma Cerrado. 3. Considerações finais

Escolha de espécies/clones para plantações florestais com finalidades econômicas no Bioma Cerrado.

1. Considerações iniciais. 2. Fatores a serem considerados na escolha de espécies/clones para estabelecimento de plantações florestais com finalidades econômicas. 2.1 Adaptação das espécies/clones ao novo ambiente de plantio. 2.2. Mercado para a madeira a ser produzida. 2.3 Disponibilidade de sementes e/ou mudas para plantio. 2.4 Conhecimento da silvicultura da espécie. 2.5 Rentabilidade da plantação florestal. 3. Considerações finais