Prediction of lamb body composition using in vivo bioimpedance analysis

The objective of this study was to evaluate the potential of in vivo bioimpedance analysis (BIA) as a method to estimate body composition in lambs. Thirty-one Texel x Ile de France crossbreed ram lambs were slaughtered at pre-determined intervals of average weights of 20, 26, 32, and 38 kg. Before the slaughter of the animals, their body weight (BW) and body length (BL) were measured. The values for resistance (Rs) and reactance (Xc) were collected using a single-frequency BIA equipment (Model RJL Quantum II Bioelectrical Body Composition Analyzer). The BIA main variables such as body bioelectrical volume (V), phase angle (PA), resistive density (RsD), and reactive density (XcD) were then calculated. The soft tissue mass of the right-half cold carcass was analyzed in order to determine its chemical composition. Multiple regression analyses were performed using the lamb body composition as dependent variables and the measurements related to bioimpedance as independent variables. The best regression models were evaluated by cross-validation. The predictive model of moisture mass, which was developed by using XcD and V, accounted for 84% of its variation. Resulting models of percentage moisture (R2 = 0.79), percentage lean mass (R2 = 0.79), percentage fat (R2 = 0.79), and fat mass (R2 = 0.87) were obtained using RsD and V. Furthermore, the values of RsD regarding V, and PA in the prediction models accounted for 91% and 89% of variation in protein mass and lean mass, respectively. Bioimpedance analysis proved to be an efficient method to estimate the body composition of lambs slaughtered at different body mass stages

Repulsive Casimir-Polder forces from cosmic strings

We investigate the Casimir-Polder force acting on a polarizable microparticle in the geometry of a straight cosmic string. In order to develop this analysis we evaluate the electromagnetic field Green tensor on the imaginary frequency axis. The expression for the Casimir-Polder force is derived in the general case of anisotropic polarizability. In dependence of the eigenvalues for the polarizability tensor and of the orientation of its principal axes, the Casimir-Polder force can be either repulsive or attractive. Moreover, there are situations where the force changes the sign with separation. We show that for an isotropic polarizability tensor the force is always repulsive. At large separations between the microparticle and the string, the force varies inversely as the fifth power of the distance. In the non-retarded regime, corresponding to separations smaller than the relevant transition wavelengths, the force decays as the inverse fourth power of the distance. In the case of anisotropic polarizability, the dependence of the Casimir-Polder potential on the orientation of the polarizability tensor principal axes also leads to the moment of force acting on the particle.Comment: 16 pages, 2 figure

Kinin B1 receptor gene ablation affects hypothalamic CART production

A role for the kinin B1 receptor in energy-homeostatic processes was implicated by previous works. Notably the studies where kinin B1 receptor knockout mice (B1-/-) are observed to have impaired adiposity, impaired leptin and insulin production, lower feed efficiency, protection from liver steatosis and diet induced obesity when fed a high fat diet (HFD). More particularly, in a model where the B1 receptor is expressed exclusively in the adipose tissue, it rescues the plasma insulin concentration and the weight gain seen in wild type mice. Taking into consideration that leptin participates in the formation of hypothalamic nuclei, which modulate energy expenditure, and feeding behavior, we hypothesized that these brain regions could also be altered in B1-/- mice. We observed for the first time a difference in the gene expression pattern of CART (cocaine-and-amphetamine related transcript) in the LHA (lateral hypothalamic area) resulting from the deletion of the kinin B1 receptor gene. The correlation between CART expression in the LHA and the thwarting of diet-induced obesity corroborates independent correlations between CART and obesity. Further it seems to indicate that the mechanism underlying the 'lean' phenotype of B1-/- mice is not solely stemming from changes in peripheral tissues but may also receive contributions from changes in the hypothalamic machinery involved in energy homeostasis processes

Vacuum fluctuations and topological Casimir effect in Friedmann-Robertson-Walker cosmologies with compact dimensions

We investigate the Wightman function, the vacuum expectation values of the field squared and the energy-momentum tensor for a massless scalar field with general curvature coupling parameter in spatially flat Friedmann-Robertson-Walker universes with an arbitrary number of toroidally compactified dimensions. The topological parts in the expectation values are explicitly extracted and in this way the renormalization is reduced to that for the model with trivial topology. In the limit when the comoving lengths of the compact dimensions are very short compared to the Hubble length, the topological parts coincide with those for a conformal coupling and they are related to the corresponding quantities in the flat spacetime by standard conformal transformation. In the opposite limit of large comoving lengths of the compact dimensions, in dependence of the curvature coupling parameter, two regimes are realized with monotonic or oscillatory behavior of the vacuum expectation values. In the monotonic regime and for nonconformally and nonminimally coupled fields the vacuum stresses are isotropic and the equation of state for the topological parts in the energy density and pressures is of barotropic type. In the oscillatory regime, the amplitude of the oscillations for the topological part in the expectation value of the field squared can be either decreasing or increasing with time, whereas for the energy-momentum tensor the oscillations are damping.Comment: 20 pages, 2 figure

Electromagnetic Casimir densities for a wedge with a coaxial cylindrical shell

Vacuum expectation values of the field square and the energy-momentum tensor for the electromagnetic field are investigated for the geometry of a wedge with a coaxal cylindrical boundary. All boundaries are assumed to be perfectly conducting and both regions inside and outside the shell are considered. By using the generalized Abel-Plana formula, the vacuum expectation values are presented in the form of the sum of two terms. The first one corresponds to the geometry of the wedge without the cylindrical shell and the second term is induced by the presence of the shell. The vacuum energy density induced by the shell is negative for the interior region and is positive for the exterior region. The asymptotic behavior of the vacuum expectation values are investigated in various limiting cases. It is shown that the vacuum forces acting on the wedge sides due to the presence of the cylindrical boundary are always attractive.Comment: 21 pages, 7 figure

Lattice dynamics effects on small polaron properties

This study details the conditions under which strong-coupling perturbation theory can be applied to the molecular crystal model, a fundamental theoretical tool for analysis of the polaron properties. I show that lattice dimensionality and intermolecular forces play a key role in imposing constraints on the applicability of the perturbative approach. The polaron effective mass has been computed in different regimes ranging from the fully antiadiabatic to the fully adiabatic. The polaron masses become essentially dimension independent for sufficiently strong intermolecular coupling strengths and converge to much lower values than those tradition-ally obtained in small-polaron theory. I find evidence for a self-trapping transition in a moderately adiabatic regime at an electron-phonon coupling value of .3. Our results point to a substantial independence of the self-trapping event on dimensionality.Comment: 8 pages, 5 figure

Bottom Production

We review the prospects for bottom production physics at the LHC.Comment: 74 pages, Latex, 71 figures, to appear in the Report of the ``1999 CERN Workshop on SM physics (and more) at the LHC'', P. Nason, G. Ridolfi, O. Schneider G.F. Tartarelli, P. Vikas (conveners

Fermionic vacuum densities in higher-dimensional de Sitter spacetime

Fermionic condensate and the vacuum expectation values of the energy-momentum tensor are investigated for twisted and untwisted massive spinor fields in higher-dimensional de Sitter spacetime with toroidally compactified spatial dimensions. The expectation values are presented in the form of the sum of corresponding quantities in the uncompactified de Sitter spacetime and the parts induced by non-trivial topology. The latter are finite and the renormalization is needed for the first parts only. Closed formulae are derived for the renormalized fermionic vacuum densities in uncompactified odd-dimensional de Sitter spacetimes. It is shown that, unlike to the case of 4-dimensional spacetime, for large values of the mass, these densities are suppressed exponentially. Asymptotic behavior of the topological parts in the expectation values is investigated in the early and late stages of the cosmological expansion. When the comoving lengths of compactified dimensions are much smaller than the de Sitter curvature radius, to the leading order the topological parts coincide with the corresponding quantities for a massless fermionic field and are conformally related to the corresponding flat spacetime results. In this limit the topological parts dominate the uncompactified de Sitter part and the back-reaction effects should be taken into account. In the opposite limit, for a massive field the asymptotic behavior of the topological parts is damping oscillatory.Comment: 19 pages, 4 figures, cosmological applications are adde