4,050 research outputs found
Intersecting branes and Supersymmetry
We consider intersecting M-brane solutions of supergravity in eleven
dimensions. Supersymmetry turns out to be a powerful tool in obtaining such
solutions and their generalizations.Comment: 6 pages, Latex, Presented at Supersymmetry and Quantum Field Theory,
International Seminar dedicated to the memory of D. V. Volkov, Kharkov, 199
Q7-branes and their coupling to IIB supergravity
We show how, by making use of a new basis of the IIB supergravity
axion-dilaton coset, SL(2,R)/SO(2), 7-branes that belong to different conjugacy
classes of the duality group SL(2,R) naturally couple to IIB supergravity with
appropriate source terms characterized by an SL(2,R) charge matrix Q. The
conjugacy classes are determined by the value of the determinant of Q. The
(p,q) 7-branes are the branes in the conjugacy class detQ = 0. The 7-branes in
the conjugacy class detQ > 0 are labelled by three numbers (p,q,r) which
parameterize the matrix Q and will be called Q7-branes. We construct the full
bosonic Wess--Zumino term for the Q7-branes. In order to realize a gauge
invariant coupling of the Q7-brane to the gauge fields of IIB supergravity it
is necessary to introduce an SL(2,R) doublet of two distinct Born--Infeld
fields on the Q7-brane world-volume.Comment: 31 pages, Latex fil
Soliton absorption spectroscopy
We analyze optical soliton propagation in the presence of weak absorption
lines with much narrower linewidths as compared to the soliton spectrum width
using the novel perturbation analysis technique based on an integral
representation in the spectral domain. The stable soliton acquires spectral
modulation that follows the associated index of refraction of the absorber. The
model can be applied to ordinary soliton propagation and to an absorber inside
a passively modelocked laser. In the latter case, a comparison with water vapor
absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with
experiment. Compared to the conventional absorption measurement in a cell of
the same length, the signal is increased by an order of magnitude. The obtained
analytical expressions allow further improving of the sensitivity and
spectroscopic accuracy making the soliton absorption spectroscopy a promising
novel measurement technique.Comment: 9 pages, 7 figures
Natronoflexus pectinivorans gen. nov. sp. nov., an obligately anaerobic and alkaliphilic fermentative member of Bacteroidetes from soda lakes
Anaerobic enrichment with pectin at pH 10 and moderate salinity inoculated with sediments from soda lakes of the Kulunda Steppe (Altai, Russia) resulted in the isolation of a novel member of the Bacteroidetes, strain AP1T. The cells are long, flexible, Gram-negative rods forming pink carotenoids. The isolate is an obligate anaerobe, fermenting various carbohydrates to acetate and succinate. It can hydrolyze and utilize pectin, xylan, starch, laminarin and pullulan as growth substrates. Growth is possible in a pH range from 8 to 10.5, with an optimum at pH 9.5, and at a salinity range from 0.1 to 2 M Na+. Phylogenetic analysis based on 16S rRNA sequences placed the isolate into the phylum Bacteroidetes as a separate lineage within the family Marinilabilaceae. On the basis of distinct phenotype and phylogeny, the soda lake isolate AP1T is proposed to be assigned in a new genus and species Natronoflexus pectinivorans (=DSM24179T = UNIQEM U807T)
Resonant spin-dependent electron coupling in a III-V/II-VI heterovalent double quantum well
We report on design, fabrication, and magnetooptical studies of a III-V/II-VI
hybrid structure containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well
(QW). The structure design allows one to tune the QW levels into the resonance,
thus facilitating penetration of the electron wave function from the diluted
magnetic semiconductor ZnCdMnSe QW into the nonmagnetic GaAs QW and vice versa.
Magneto-photoluminescence studies demonstrate level anticrossing and strong
intermixing resulting in a drastic renormalization of the electron effective g
factor, in perfect agreement with the energy level calculations.Comment: 4 pages, 5 Postscript figures, uses revtex
Off-diagonal correlations of the Calogero-Sutherland model
We study correlation functions of the Calogero-Sutherland model in the whole
range of the interaction parameter. Using the replica method we obtain
analytical expressions for the long-distance asymptotics of the one-body
density matrix in addition to the previously derived asymptotics of the
pair-distribution function [D.M. Gangardt and A. Kamenev, Nucl. Phys. B, 610,
578 (2001)]. The leading analytic and non-analytic terms in the short-distance
expansion of the one-body density matrix are discussed. Exact numerical results
for these correlation functions are obtained using Monte Carlo techniques for
all distances. The momentum distribution and static structure factor are
calculated. The potential and kinetic energies are obtained using the
Hellmann-Feynman theorem. Perfect agreement is found between the analytical
expressions and numerical data. These results allow for the description of
physical regimes of the Calogero-Sutherland model. The zero temperature phase
diagram is found to be of a crossover type and includes quasi-condensation,
quasi-crystallization and quasi-supersolid regimes.Comment: 17 pages, 7 figure
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