Orbital Ordering in ferromagnetic Lu2V2O7

We have observed the orbital ordering in the ferromagnetic Mott-insulator Lu2V2O7 by the polarized neutron diffraction technique. The orbital ordering pattern determined from the observed magnetic form factors can be explained in terms of a linear combination of wave functions |yz>, |zx> and |xy>; |0> = (1/3)^(1/2) |xy> + (1/3)^(1/2)|yz> + (1/3)^(1/2) |zx> which is proportional to |(x + y + z)^2 - r^2>; where each orbital is extended toward the center-of-mass of the V tetrahedron. We discuss the stability of the ferromagnetic Lu2V2O7, using a Hubbard Hamiltonian with these three orbitals.Comment: 17pages. to be published in J. Phys. Soc. Jpn. 74 (2005

Intrinsic double-peak structure of the specific heat in low-dimensional quantum ferrimagnets

Motivated by recent magnetic measurements on A3Cu3(PO4)4 (A=Ca,Sr) and Cu(3-Clpy)2(N3)2 (3-Clpy=3-Chloropyridine), both of which behave like one-dimensional ferrimagnets, we extensively investigate the ferrimagnetic specific heat with particular emphasis on its double-peak structure. Developing a modified spin-wave theory, we reveal that ferromagnetic and antiferromagnetic dual features of ferrimagnets may potentially induce an extra low-temperature peak as well as a Schottky-type peak at mid temperatures in the specific heat.Comment: 5 pages, 6 figures embedded, Phys. Rev. B 65, 214418 (2002

Valores econômicos para características produtivas de ovinos: desenvolvimento de objetivos e critérios de seleção em sistemas de produção baseados em pastagem nativa no bioma Pampa do Brasil.

Resumo: O presente estudo visa contribuir para o desenvolvimento de programas de melhoramento genético estimando ponderadores econômicos para características produtivas em ovinos criados no sul do Brasil. Foi desenvolvido modelo bio-econômico baseado nos sistemas de produção, por meio de entrevistas com produtores, revisão bibliográfica e análises do mercado atual. Foram calculados os valores econômicos para as características características reprodutivas, de sobrevivência, crescimento, lã, sanidade e de carcaça. As características de maior importância econômica foram Taxa de Parição, Prolificidade, Mortalidade dos cordeiros e Número de partos por ano, com ponderadores econômicos estimados de 0,85 e -0,85. Embora as características reprodutivas tenham baixa herdabilidade, dada à importância econômica, justifica-se o investimento na seleção de animais geneticamente superiores nas mesmas, uma vez que estas características representaram uma importância de 25, 82, 76, 99 e 49% a mais que o grupo das características de sobrevivência, crescimento, lã e sanidade, respectivamente. Economic values for traits of sheep: Influence on the objectives and criteria for selection in production systems based on native pasture in the Pampa biome of Brazil. Abstract: The present study aims to contribute to the development of breeding programs estimate economic weights for traits in sheep reared in southern Brazil. Model bio-economic was developed based on the production systems, trough interviews with producers, literature review and analysis of the current market. Values were calculated for the economic characteristics reproductive traits, survival, growth, wool, health and carcass. The major characters of economic importance were calving rate, litter size, mortality of lambs and number of births per year, with estimated economic weights of 0,85 and -0,85. Although reproductive traits have low heritability, given the economic importance justified the investment in the selection of genetically superior animals in them, since these characteristics represented an amount of 25, 82, 76, 99 and 49% more than the characteristics of survival, growth, wool and health, respectively

Editorial: ultrasound surveillance of hepatocellular carcinoma in the 21st century – authors’ reply

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/136042/1/apt13910.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136042/2/apt13910_am.pd

Radiative corrections to the cross section of e−+p→ν+ne^-+p\to \nu+n and the crossed processes

Born cross section and the radiative corrections to its lowest order are considered in the frame work of QED with structureless nucleons including the emission of virtual and real photons. Result is generalized to take into account radiative corrections in higher orders of perturbation theory in the leading and next-to leading logarithmic approximation. Crossing processes are considered in the leading approximation.Comment: 11 pages, 1 figur

Predictors of adequate ultrasound quality for hepatocellular carcinoma surveillance in patients with cirrhosis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135189/1/apt13841_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135189/2/apt13841.pd

Radiative corrections to low energy neutrino reactions

We show that the radiative corrections to charged current (CC) nuclear reactions with an electron(positron) in the final state are described by a universal function. The consistency of our treatment of the radiative corrections with the procedure used to extract the value of the axial coupling constant $g_A$ is discussed. To illustrate we apply our results to (anti)neutrino deuterium disintegration and to $pp$ fusion in the sun. The limit of vanishing electron mass is considered, and a simple formula valid for E_{obs}\gsim 1 MeV is obtained. The size of the nuclear structure-dependent effects is also discussed. Finally, we consider CC transitions with an electron(positron) in the initial state and discuss some applications to electron capture reactions.Comment: 23 pages, 5 figure

Magnetic excitations and structural change in the S=1/2 quasi-one-dimensional magnet Sr_{14-x}Y_{x}Cu_{24}O_{41} (0<x<1)

Neutron scattering measurements have been performed on the S=1/2 quasi-one-dimensional system Sr_{14-x}Y_{x}Cu_{24}O_{41}, which has both simple chains and two-leg ladders of copper ions. We observed that when a small amount of yttrium is substituted for strontium, which is expected to reduce the number of holes, the dimerized state and the structure in the chain are changed drastically. The inelastic peaks originating from the dimerized state of the chain becomes broader in energy but not in momentum space. This implies that the dimerized state becomes unstable but the spin correlations are unchanged with yttrium substitution. Furthermore, it was observed that nuclear Bragg peak intensities originating from the chain show strong temperature and x dependence, which suggests that the chains slide along the c axis as temperature and x are varied.Comment: 5 pages, 6 figures, to appear in Phys. Rev.

Derivação de valores econômicos para critérios de seleção em sistemas de produção de cria.

CONGREGA