3,758 research outputs found
Correlations due to localization in quantum eigenfunctions of disordered microwave cavities
Non-universal correlations due to localization are observed in statistical
properties of experimental eigenfunctions of quantum chaotic and disordered
microwave cavities. Varying energy {E} and mean free path {l} enable us to
experimentally tune from localized to delocalized states. Large level-to-level
Inverse Participation Ratio (IPR I_{2}) fluctuations are observed for the
disordered billiards, whose distribution is strongly asymmetric about .
The density auto-correlations of eigenfunctions are shown to decay
exponentially and the decay lengths are experimentally determined. All the
results are quantitatively consistent with calculations based upon nonlinear
sigma-models.Comment: 4 pages, LaTex, 5 .jpg figures. This paper with 5 embedded postscript
figures available (PS,PDF) at http://sagar.physics.neu.edu/preprints
From chaos to disorder: Statistics of the eigenfunctions of microwave cavities
We study the statistics of the experimental eigenfunctions of chaotic and
disordered microwave billiards in terms of the moments of their spatial
distributions, such as the Inverse Participation Ratio (IPR) and
density-density auto-correlation. A path from chaos to disorder is described in
terms of increasing IPR. In the chaotic, ballistic limit, the data correspond
well with universal results from random matrix theory. Deviations from
universal distributions are observed due to disorder induced localization, and
for the weakly disordered case the data are well-described by including finite
conductance and mean free path contributions in the framework of nonlinear
sigma models of supersymetry.Comment: 5 pages + 2 JPG figure
Matching Multiple Patterns From Right to Left
We address the problem of matching multiple pattern strings against a text string. Just as the Aho-Corasick algorithm generalizes the Knuth-Morris-Pratt single-pattern algorithm to handle multiple patterns, we exhibit two generalizations of the Boyer-Moore algorithm to handle multiple patterns. In order to obtain worst-case time bounds better than quadratic, our algorithms remember some of the previous history of the matching
Comments on "Vortex Glass and Lattice Melting Transitions in a YNi_2B_2C Single Crystal"
Recently, Mun et.al. (Phys. Rev. Lett., 76, 2790 (1996)) have published their
results on single crystal YNi_2B_2C, claiming that their experimental
observations can be explained in terms of formation of Vortex Glass and Lattice
melting. Our experiments, carried out on samples obtained from the SAME source,
reveal a much richer phase diagram and span wider regions of experimental
parameter space than Mun et. al. that encompasses most of their observations.
We speculate that this material has anomalous intrinsic properties and the
results cannot be explained by simple models about the flux lattice.Comment: 1 page, LaTeX type, 1 PostScript figure, Uses PRABIB.STY file, 600
dpi PS file available at http://sagar.physics.neu.edu/preprints.html To
appear in Physical Review Letter
Proper ferroelastic phase transitions in thin epitaxial films with symmetry-conserving and symmetry-breaking misfit strains
We study how the ferroelastic domain structure sets in in an epitaxial film
of a material with second order proper ferroelastic transition. The domain
structures considered are similar to either or
structures in perovskite ferroelectrics. If the "extrinsic" misfit
strain, not associated with the transition, does not break the symmetry of the
high-temperature phase, the phase transition in the film occurs at somewhat
lower temperature compared to the bulk. The loss of stability then occurs with
respect to a sinusoidal strain wave, which evolves into the domain structure
with practically the same geometry and approximately the same period. In the
presence of the symmetry-breaking component of the misfit strain ("extrinsic"
misfit) the character of the phase transition is qualitatively different. In
this case it is a {\em topological} transition between single-domain and
multi-domain states, which starts from a low density of the domain walls.Comment: 7 pages, 2 figures, REVTeX 3.
Kaempferol-Phospholipid Complex: Formulation, and Evaluation of Improved Solubility, In Vivo Bioavailability, and Antioxidant Potential of Kaempferol
The current work describes the formulation and evaluation of a phospholipid complex of kaempferol toenhance the latter’s aqueous solubility, in vitro dissolution rate, in vivo antioxidant and hepatoprotectiveactivities, and oral bioavailability. The kaempferol-phospholipid complex was synthesized using a freeze-drying method with the formulation being optimized using a full factorial design (32) approach. The resultsinclude the validation of the mathematical model in order to ascertain the role of specific formulation andprocess variables that contribute favorably to the formulation’s development. The final product wascharacterized and confirmed by Differential Scanning Calorimetry (DSC), Fourier Transform InfraredSpectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), and Powder X-rayDiffraction (PXRD) analysis. The aqueous solubility and the in vitro dissolution rate were enhanced comparedto that of pure kaempferol. The in vivo antioxidant properties of the kaempferol-phospholipid complex wereevaluated by measuring its impact on carbon tetrachloride (CCl4)-intoxicated rats. The optimizedphospholipid complex improved the liver function test parameters to a significant level by restoration of allelevated liver marker enzymes in CCl4-intoxicated rats. The complex also enhanced the in vivo antioxidantpotential by increasing levels of GSH (reduced glutathione), SOD (superoxide dismutase), catalase anddecreasing lipid peroxidation, compared to that of pure kaempferol. The final optimized phospholipidcomplex also demonstrated a significant improvement in oral bioavailability demonstrated by improvementsto key pharmacokinetic parameters, compared to that of pure kaempferol
Superfluid density in the underdoped YBa_2Cu_3O_{7-x}: Evidence for d-density wave order of pseudogap
The investigation of the penetration depth \lambda_{ab}(T,p) in
YBa_2Cu_3O_{7-x} crystals allowed to observe the following features of the
superfluid density n_s(T,p)\propto \lambda_{ab}^{-2}(T,p) as a function of
temperature T<Tc/2 and carrier concentration 0.078\le p\le 0.16 in CuO_2
planes: (i) n_s(0,p) depends linearly on p, (ii) the derivative
|dn_s(T,p)/dT|_{T\to 0} depends on p slightly in the optimally and moderately
doped regions (0.10<p\le 0.16); however, it rapidly increases with p further
lowering and (iii) the latter finding is accompanied by the linear
low-temperature dependence [-\Delta n_s(T)]\propto T changing to [-\Delta
n_s(T)]\propto \sqrt{T}. All these peculiarities can be treated in the
framework of d-density wave scenario of electronic processes in underdoped
high-Tc materials.Comment: 4 pages, 5 figures. To be published in Phys.Rev.Let
Alternative approach to all-angle negative refraction in two-dimensional photonic crystals
We show that with an appropriate surface modification, a slab of photonic
crystal can be made to allow wave transmission within the band gap.
Furthermore, negative refraction and all-angle-negative-refraction (AANR) can
be achieved by this surface modification in frequency windows that were not
realized before in two-dimensional photonic crystals [C. Luo et al, Phys. Rev.
B 65, 201104 (2002)]. This approach to AANR leads to new applications in flat
lens imaging. Previous flat lens using photonic crystals requires object-image
distance u+v less than or equal to the lens thickness d, u+v d. Our approach
can be used to design flat lens with u+v=sd with s>>1, thus being able to image
large and/or far away objects. Our results are confirmed by FDTD simulations.Comment: 5 pages, 9 eps figs in RevTex forma
- …