Gravitation: Global Formulation and Quantum Effects

A nonintegrable phase-factor global approach to gravitation is developed by using the similarity of teleparallel gravity with electromagnetism. The phase shifts of both the COW and the gravitational Aharonov-Bohm effects are obtained. It is then shown, by considering a simple slit experiment, that in the classical limit the global approach yields the same result as the gravitational Lorentz force equation of teleparallel gravity. It represents, therefore, the quantum mechanical version of the classical description provided by the gravitational Lorentz force equation. As teleparallel gravity can be formulated independently of the equivalence principle, it will consequently require no generalization of this principle at the quantum level.Comment: Latex (IOP style), 14 pages, 3 figures. To appear in Classical and Quantum Gravit

Torsion and the Gravitational Interaction

By using a nonholonomous-frame formulation of the general covariance principle, seen as an active version of the strong equivalence principle, an analysis of the gravitational coupling prescription in the presence of curvature and torsion is made. The coupling prescription implied by this principle is found to be always equivalent with that of general relativity, a result that reinforces the completeness of this theory, as well as the teleparallel point of view according to which torsion does not represent additional degrees of freedom for gravity, but simply an alternative way of representing the gravitational field.Comment: Version 2: minor presentation changes, a reference added, 11 pages (IOP style

The gravitational energy-momentum flux

We present a continuity equation for the gravitational energy-momentum, which is obtained in the framework of the teleparallel equivalent of general relativity. From this equation it follows a general definition for the gravitational energy-momentum flux. This definition is investigated in the context of plane waves and of cylindrical Einstein-Rosen waves. We obtain the well known value for the energy flux of plane gravitational waves, and conclude that the latter exhibit features similar to plane electromagnetic waves.Comment: 20 pages, latex file, no figures, two references added, accepted for publication in Class. Quantum Gravit

UTA versus line emission for EUVL: Studies on xenon emission at the NIST EBIT

Spectra from xenon ions have been recorded at the NIST EBIT and the emission into a 2% bandwidth at 13.5 nm arising from 4d-5p transitions compared with that from 4d-4f and 4p-4d transitions in Xe XI and also with that obtained from the unresolved transition array (UTA) observed to peak just below 11 nm. It was found that an improvement of a factor of five could be gained in photon yield using the UTA rather than the 4d-5p emission. The results are compared with atomic structure calculations and imply that a significant gain in efficiency should be obtained using tin, in which the emission at 13.5 nm comes from a similar UTA, rather than xenon as an EUVL source material

Optimal bounds for the colored Tverberg problem

We prove a "Tverberg type" multiple intersection theorem. It strengthens the prime case of the original Tverberg theorem from 1966, as well as the topological Tverberg theorem of B´ar´any et al. (1980), by adding color constraints. It also provides an improved bound for the (topological) colored Tverberg problem of B´ar´any & Larman (1992) that is tight in the prime case and asymptotically optimal in the general case. The proof is based on relative equivariant obstruction theory

Original scientific paper Far-infrared spectroscopy of PbTe doped with iron

Far infrared reflection spectra, at room and liquid nitrogen temperature, of PbTe single crystals doped with iron are presented. Plasma minima were observed at about 160 cm –1 and 180 cm –1 for room and liquid nitrogen temperature, respectively. Using the reflectivity diagrams and their minima, the values of the hole concentrations and their mobility at both temperatures were calculated and compared with galvanomagnetic measurements. All these results indicated that when PbTe is doped with a small concentration of Fe, the hole concentration is reduced by one order of magnitude and the free carrier mobility is larger when compared to pure PbTe

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Razlike u periodu rehabilitacije kod dve tehnike grafta za rekonstrukciju prednje ukr{tene veze (LCA): tetive semitendinozus / gracilis – ligament patel

Role of oscillatory shear index in predicting the occurrence and development of plaque

The paper presents theoretical basis and results obtained by calculation of blood flow in coronary artery bifurcation, whereby the emphasis is placed on the plaque occurrence analysis based on oscillatory shear index (OSI). OSI is the temporal fluctuation of low and high average shear stress. The endothelial or wall shear stress is a major factor that affects the formation of plaque phenomenon. There are complex hemodynamic conditions in these areas where local fluid flow dictates the occurrence and development of plaque. Favorable conditions for the plaque development occurring in areas characterized by low shear stress, while areas with higher values of OSI index are not susceptible. Arterial bifurcations are the places in vascular tree where atherosclerosis mainly occurs. OSI index response to the appearance of plaques in the common coronary artery and branches are considered on three out of eight possible combinations of plaque locations. Algorithm for the calculation of OSI index are embedded in software PAK-F and the results are written in FEMAP neutral and Paraview VTK file format

Beograd

Rigid-fix pins fiksacija i plastika prednjeg ukr{tenog ligamenta- LCA semitendinozus / gracilis autografto

EQUIPARTITION OF SPHERE MEASURES BY HYPERPLANES

AND MARKO S. MILO ˇ SEVIĆ23 Abstract. Measure partition problems are classical problems of geometric combinatorics ([1], [2], [3], [4]) whose solutions often use tools from the equivariant algebraic topology. The potential of the computational obstruction theory approach is partially demonstrated here. In this paper we reprove a result of V.V. Makeev [9] about a 6-equipartition of a measure on S 2 by three planes. The advantage of our approach is that it can be applied on other more complicated questions of the similar nature. 1. Statement of the main result A measure µ is a proper measure if (A) µ([a, b]) = 0 for any circular arc [a, b] ⊂ S 2, and (B) µ(U)> 0 for each nonempty open set U ⊂ S 2. Three planes H1, H2 and H3 in R 3 through the origin are in a fan position if they intersect along the common line. Planes in the fan position cut the sphere S 2 in six parts σ1,.., σ6 which can be naturally oriented up to a cyclic permutation. We are interested in the following measure partition problem. Problem 1. Find all six-tuples (α1,.., α6) ∈ N 6 that for every proper Borel probability measure µ on the sphere S 2 there exist three planes in the fa