14,330 research outputs found

    Differential Input from the Amygdaloid Body to the Ventromedial Hypothalamic Nucleus in the Rat

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    Differential amygdaloid afferents to anterior dorsal, anterior ventral, posterior dorsal and posterior ventral subdivisions of the ventromedial hypothalamic nucleus (VMH) were studied by means of retrograde transport of horseradish peroxidase (HRP). Injections of tracer confined to the VMH subdivisions mentioned, and enhancement of tracer uptake and transport were achieved by iontophoretic delivery of an HRP solution containing poly-L-α-ornithine. It was shown that the medial, central, basolateral, basomedial, lateroposterior and intercalated nuclei of the amygdala constitute afferent input sources to the ventromedial nucleus in a topographic pattern related to the various subdivisions of the VMH. This topographically organized amygdala-VMH projection is discussed against the background of the functional role that both amygdala and VMH play in the control of feeding, apart from various other autonomous functions that both brain centers are known to be concerned with.

    Biquadratic antisymmetric exchange and the magnetic phase diagram of magnetoelectric CuFeO2_2

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    Biquadratic {\it antisymmetric} exchange terms of the form −[Cijeijα(si×sj)z]2 - [C_{ij} e^{\alpha}_{ij}({\bf s}_i\times{\bf s}_j)_z]^2, where eij{\bf e}_{ij} is the unit vector connecting sites ii and jj and α=x,y\alpha = x,y, due partially to magnetoelectric coupling effects, are shown to be responsible for the spin-flop helical phase in CuFeO2_2 at low magnetic field and temperature. Usual biquadratic {\it symmetric} exchange, likely due to magnetoelastic coupling, is found to support the stability of axial magnetic states at higher fields in this nearly-Heisenberg like stacked triangular antiferromagnet. A model Hamiltonian which also includes substantial interplane and higher-neighbor intraplane exchange interactions, reproduces the unique series of observed commensurate and incommensurate periodicity phases with increasing applied magnetic field in this highly frustrated system. The magnetic field-temperature phase diagram is discussed in terms of a Landau-type free energy.Comment: 7 pages, 9 figure

    Leptogenesis with Almost Degenerate Majorana Neutrinos

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    We investigate the leptogenesis with almost degenerate neutrinos, in the framework of democratic mass matrix, which naturally explains the large mixing angles for neutrino oscillations as well as quark masses and mixing matrix. We find that the baryon asymmetry in the present universe is explained via the decays of right-handed neutrinos produced nonthermally by the inflaton decay. The model predicts neutrinoless double beta decays accessible in near future experiments.Comment: 17 pages, LaTeX, 2 figure

    Lepton Flavor Violation in Supersymmetric SO(10) Grand Unified Models

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    The study for lepton flavor violation combined with the neutrino oscillation may provide more information about the lepton flavor structure of the grand unified theory. In this paper, we study two lepton flavor violation processes, τ→μγ\tau\to \mu\gamma and Z→τμZ\to \tau\mu, in the context of supersymmetric SO(10) grand unified models. We find the two processes are both of phenomenological interest. In particular the latter may be important in some supersymmetric parameter space where the former is suppressed. Thus, Z-dacay may offer another chance for looking for lepton flavor violation.Comment: 26 pages, 10 figure

    Lepton-nucleus scattering in the impulse approximation regime

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    We discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out using realistic nuclear spectral functions and including the effect of final state interactions. Comparison between electron scattering data and the calculated inclusive cross sections off oxygen shows that the Fermi gas model fails to provide a satisfactory description of the measured cross sections, and inclusion of nuclear dynamics is needed. The role of Pauli blocking in charged-current neutrino induced reactions at low Q2Q^2 is also analyzed.Comment: To be published in the Proceedings of NUFACT05 (Nucl. Phys. B, Proceedings Supplements

    Dynamical mass generation by source inversion: Calculating the mass gap of the Gross-Neveu model

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    We probe the U(N) Gross-Neveu model with a source-term JΨˉΨJ\bar{\Psi}\Psi. We find an expression for the renormalization scheme and scale invariant source J^\hat{J}, as a function of the generated mass gap. The expansion of this function is organized in such a way that all scheme and scale dependence is reduced to one single parameter d. We get a non-perturbative mass gap as the solution of J^=0\hat{J}=0. In one loop we find that any physical choice for d gives good results for high values of N. In two loops we can determine d self-consistently by the principle of minimal sensitivity and find remarkably accurate results for N>2.Comment: 13 pages, 3 figures, added referenc

    Validation of enzyme-linked immunosorbent assays for the detection of licit and illicit drugs in human breast milk.

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    Human breast milk contains essential nutrients and immunological factors that are critical for the health and development of infants. The benefits of breast-feeding have been studied extensively, and research has shown that breastfed infants have a decreased risk of infections and illnesses. There are many instances when mothers are unable to provide their own milk, which is the case with many prematurely born infants. Breast milk banks and facilities that process human milk provide an alternative solution to synthetic or animal derived infant formula, allowing babies to receive the benefits of human breast milk. There are many drugs that can pass into a woman's breast milk and cause possible harm to an infant. It is important that donor milk be screened for drugs-of-abuse in order to prevent this from occurring. The purpose of this study was to optimize and validate enzyme-linked immunosorbent assays (ELISA) for the detection of a seven-drug panel in human breast milk. The following Neogen Corporation kits were utilized: Amphetamine Ultra, Benzodiazepine Group, Cocaine/Benzoylecgonine (BZE), Cotinine, Opiate Group, Oxycodone/Oxymorphone, and THC. Sample dilutions that minimized breast milk matrix interference were determined, and cutoff levels for each assay were proposed based on the linear range of the assay. The seven-drug panel was validated through the assessment of drift, precision, and accuracy. The Cocaine/BZE and Opiate Group cutoffs were increased from 30 to 50 ng/mL after several false negative results were obtained during the accuracy portion of the validation. The ELISA assays were validated at two different sites, and the robustness of the method was demonstrated.--Abstract
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