2,196 research outputs found
How Do Nonlinear Voids Affect Light Propagation ?
Propagation of light in a clumpy universe is examined. As an inhomogeneous
matter distribution, we take a spherical void surrounded by a dust shell where
the ``lost mass'' in the void is compensated by the shell. We study how the
angular-diameter distance behaves when such a structure exists. The
angular-diameter distance is calculated by integrating the Raychaudhuri
equation including the shear. An explicit expression for the junction condition
for the massive thin shell is calculated. We apply these results to a dust
shell embedded in a Friedmann universe and determine how the distance-redshift
relation is modified compared with that in the purely Friedmann universe. We
also study the distribution of distances in a universe filled with voids. We
show that the void-filled universe gives a larger distance than the FRW
universe by at if the size of the void is of the
Horizon radius.Comment: To appear in Prog. Theor. Phys. 10
Metal-nonmetal transition in LixCoO2 thin film and thermopower enhancement at high Li concentration
We investigate the transport properties of LixCoO2 thin films whose
resistivities are nearly an order of magnitude lower than those of the bulk
polycrystals. A metal-nonmetal transition occurs at ~0.8 in a biphasic domain,
and the Seebeck coefficient (S) is drastically increased at ~140 K (= T*) with
increasing the Li concentration to show a peak of magnitude ~120 \muV/K in the
S-T curve of x = 0.87. We show that T* corresponds to a crossover temperature
in the conduction, most likely reflecting the correlation-induced temperature
dependence in the low-energy excitations
Effect of abscisic acid and defoliation on anthocyanin accumulation in Kyoho grapes (Vitis vinifera L. x V. labruscana BAILEY)
In Kyoho grapes, ABA treatment at 1000 ppm in the beginning of ripening enhanced anthocyanin accumulation in the skin without any effect on the contents of soluble solids and titratable acids in the juice.By defoliation at veraison, anthocyanin synthesis was completely inhibited, and the soluble solids content in the juice and sugar levels in the skin became much less than those of the control. Furthermore, endogenous ABA levels in the skin and flesh did not increase throughout ripening period.On such defoliated vines, the berries recovered anthocyanin accumulation by ABA application.From these results, it will be assumed that ABA which accumulates in the skin is one of the main factors involved in the anthocyanin synthesis.Der Einfluß von Abscisinsäure und Entblätterung auf die Anthocyanakkumulation in Trauben der Rebsorte Kyoho (Vitis vinifera L. x V. labruscana BAILEY)Wurden Kyoho-Trauben zu Beginn der Beerenreife mit 1 000 ppm ABS behandelt, so war in den Beerenhäuten verstärkt Anthocyan angereichert, ohne daß Mostgewicht und tritierbare Säure des Beerensaftes irgendwie beeinflußt waren. Durch Entblätterung der Reben zur Zeit des Weichwerdens der Beeren wurde die Anthocyansynthese vollkommen unterdrückt, und das Mostgewicht des Beerensaftes wie auch die Zuckerkonzentration der Beerenhaut waren gegenüber der Kontrolle bedeutend verringert. Ferner nahm die Konzentration der endogenen ABS in Beerenhaut und -fleisch während der ganzen Reifeperiode nicht zu.Bei den entblätterten Reben setzte nach der Applikation von ABS die Anthocyanakkumulation in den Beeren wieder ein.Aus den vorliegenden Ergebnissen wird gefolgert, daß die Anreicherung von ABS in der Beerenhaut einer der Hauptfaktoren ist, die an der Anthocyansynthese beteiligt sind
Regular projections of graphs with at most three double points
A generic immersion of a planar graph into the 2-space is said to be knotted
if there does not exist a trivial embedding of the graph into the 3-space
obtained by lifting the immersion with respect to the natural projection from
the 3-space to the 2-space. In this paper we show that if a generic immersion
of a planar graph is knotted then the number of double points of the immersion
is more than or equal to three. To prove this, we also show that an embedding
of a graph obtained from a generic immersion of the graph (does not need to be
planar) with at most three double points is totally free if it contains neither
a Hopf link nor a trefoil knot.Comment: 16 pages, 31 figure
Posterior interosseous nerve palsy secondary to pigmented villonodular synovitis of the elbow: Case report and review of literature
SummaryLocal tumor compression is the main mechanical cause of posterior interosseous nerve (PIN) palsy. The reported cases of these tumors do not include that of pigmented villonodular synovitis (PVNS). Here, we report a case of a 53-year-old male with a 9-year history of painless swelling in his left elbow and a few months of progressive weakness in his left hand. Imaging identified the mass, and histological examination of the biopsy specimens revealed PVNS. The mass was compressing the nerve at the arcade of Frohse, and we performed a complete resection of the mass. Following removal of the mass, the patient regained complete function in his left upper extremity, and no local recurrence has been detected after 2 postoperative years. The possibility of PVNS should be considered in the differential diagnosis of PIN palsy
Metastability in Interacting Nonlinear Stochastic Differential Equations II: Large-N Behaviour
We consider the dynamics of a periodic chain of N coupled overdamped
particles under the influence of noise, in the limit of large N. Each particle
is subjected to a bistable local potential, to a linear coupling with its
nearest neighbours, and to an independent source of white noise. For strong
coupling (of the order N^2), the system synchronises, in the sense that all
oscillators assume almost the same position in their respective local potential
most of the time. In a previous paper, we showed that the transition from
strong to weak coupling involves a sequence of symmetry-breaking bifurcations
of the system's stationary configurations, and analysed in particular the
behaviour for coupling intensities slightly below the synchronisation
threshold, for arbitrary N. Here we describe the behaviour for any positive
coupling intensity \gamma of order N^2, provided the particle number N is
sufficiently large (as a function of \gamma/N^2). In particular, we determine
the transition time between synchronised states, as well as the shape of the
"critical droplet", to leading order in 1/N. Our techniques involve the control
of the exact number of periodic orbits of a near-integrable twist map, allowing
us to give a detailed description of the system's potential landscape, in which
the metastable behaviour is encoded
Fourier Duality as a Quantization Principle
The Weyl-Wigner prescription for quantization on Euclidean phase spaces makes
essential use of Fourier duality. The extension of this property to more
general phase spaces requires the use of Kac algebras, which provide the
necessary background for the implementation of Fourier duality on general
locally compact groups. Kac algebras -- and the duality they incorporate -- are
consequently examined as candidates for a general quantization framework
extending the usual formalism. Using as a test case the simplest non-trivial
phase space, the half-plane, it is shown how the structures present in the
complete-plane case must be modified. Traces, for example, must be replaced by
their noncommutative generalizations - weights - and the correspondence
embodied in the Weyl-Wigner formalism is no more complete. Provided the
underlying algebraic structure is suitably adapted to each case, Fourier
duality is shown to be indeed a very powerful guide to the quantization of
general physical systems.Comment: LaTeX 2.09 with NFSS or AMSLaTeX 1.1. 97Kb, 43 pages, no figures.
requires subeqnarray.sty, amssymb.sty, amsfonts.sty. Final version with (few)
text and (crucial) typos correction
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