7,137 research outputs found
Weyl Expansion for Symmetric Potentials
We present a semiclassical expansion of the smooth part of the density of
states in potentials with some form of symmetry. The density of states of each
irreducible representation is separately evaluated using the Wigner transforms
of the projection operators. For discrete symmetries the expansion yields a
formally exact but asymptotic series in , while for the rotational
symmetries the expansion requires averaging over angular momentum as
well as energy. A numerical example is given in two dimensions, in which we
calculate the leading terms of the Weyl expansion as well as the leading
periodic orbit contributions to the symmetry reduced level density.Comment: Four of the five figures are appended as a postscript file. The fifth
figure is available by snail mail
Geometric and Diffractive Orbits in the Scattering from Confocal Hyperbolae
We study the scattering resonances between two confocal hyperbolae and show
that the spectrum is dominated by the effect of a single periodic orbit. There
are two distinct cases depending on whether the orbit is geometric or
diffractive. A generalization of periodic orbit theory allows us to incorporate
the second possibility. In both cases we also perform a WKB analysis. Although
it is found that the semiclassical approximations work best for resonances with
large energies and narrow widths, there is reasonable agreement even for
resonances with large widths - unlike the two disk scatterer. We also find
agreement with the next order correction to periodic orbit theory.Comment: Written in RevTeX. After \end{document} comes a uuencoded .ps file
with two figure
Effect of Photobiomodulation on Vinblastine-Poisoned Murine HERS Cells
Objective: The aim of this study was to investigate the effect of near-infrared (NIR) photobiomodulation on the proliferation and glutathione levels in murine Hertwig\u27s epithelial root sheath (HERS) cells after poisoning with vinblastine. Background: Photobiomodulation has been shown to improve wound healing in a number of animal models. There have been no studies on the effect of photobiomodulation on cancer-related chemotherapy injury to the cells that initiate tooth root growth. Materials and Methods: Control groups consisted of murine HERS cells without vinblastine (VBβ) and cells with vinblastine at 10, 20, and 30βng/mL (VB10, VB20, and VB30). Experimental groups consisted of these same groups with light therapy (VB-L, VB10L, VB20L, and VB30L). The cells were exposed to vinblastine for 1βh. Photobiomodulation consisted of a 75-cm2 gallium-aluminum-arsenide light-emitting diode (LED) array at an energy density of 12.8βJ/cm2, delivered with 50βmW/cm2 power over 256βs. Results: Vinblastine alone significantly decreased HERS cell proliferation and glutathione levels at all concentrations (VB10 [β55%, pβ\u3cβ1.0βΓβ10β8]; VB20 [β72%, pβ\u3cβ1.0βΓβ10β9]; VB30 [β80%, pβ\u3cβ1.0βΓβ10β10]; and VB10 [β36%, pβ\u3cβ0.0001]; VB20 [β49%, pβ\u3cβ1.0βΓβ10β6]; VB30 [β53%, pβ\u3cβ1.0βΓβ10β7] respectively). Photobiomodulation significantly increased cell proliferation at all levels of vinblastine exposure (VB10L [+50%, pβ\u3cβ0.0001]; VB20L [+45%, pβ\u3cβ0.05]; VB30 [+39%, pβ\u3cβ0.05]) but not of the control (+22%, pβ =β0.063). The photobiomodulation significantly increased glutathione production in all concentrations of vinblastine except 20βng/mL (VB10L [+39%, pβ=β0.007]; VB20L [+19%, pβ=β0.087]; VB30 [+14%, pβ=β0.025]) and the control (+12%, pβ=β0.13). Conclusions: Photobiomodulation demonstrated an improvement in proliferation and glutathione levels in vinblastine-poisoned murine HERS cells
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