299 research outputs found
Superstring in a pp-wave background at finite temperature - TFD approach
A thermodynamical analysis for the type IIB superstring in a pp-wave
background is considered. The thermal Fock space is built and the temperature
SUSY breaking appears naturally by analyzing the thermal vacuum. All the
thermodynamical quantities are derived by evaluating matrix elements of
operators in the thermal Fock space. This approach seems to be suitable to
study thermal effects in the BMN correspondence context.Comment: 15 pages, revtex4, references added, typos correcte
Identification of «Border Disease» in sheep in France
La maladie de Border ou « Border disease » (B.D.) a été diagnostiquée dans un élevage comprenant 150 brebis, en Ardèche (France). Le tableau clinique comprenait des avortements, des anomalies de la toison, des déformations du squelette, des symptômes nerveux et des cas d’hydrocéphalie. Des prélèvements sanguins effectués chez 15 brebis du troupeau ont permis la mise en évidence d’anticorps neutralisant le virus de la maladie des muqueuses chez ces adultes. Enfin, l’antigène viral a été mis en évidence en utilisant la technique d’immunofluorescence directe d’une part, à l’aide d’un sérum anti-BD. sur coupe d’encéphale congelé d’autre part, après isolement du virus sur cultures cellulaires.Border disease was diagnosed in a flock of 150 ewes in Ardeche (France). The clinical signs were abortion, abnormally birthcoat, altered conformation, nervous symptoms, hydrocephalus. Samples were taken from 15 ewes and call contained mucosal disease virus neutralising antibodies. Detection of Border disease antigen in cryostat section of brain and in cell cultures by immunofluorescence with direct anti-B.D. conjugate was positive
Open String Fluctuations in AdS with and without Torsion
The equations of motion and boundary conditions for the fluctuations around a
classical open string, in a curved space-time with torsion, are considered in
compact and world-sheet covariant form. The rigidly rotating open strings in
Anti de Sitter space with and without torsion are investigated in detail. By
carefully analyzing the tangential fluctuations at the boundary, we show
explicitly that the physical fluctuations (which at the boundary are
combinations of normal and tangential fluctuations) are finite, even though the
world-sheet is singular there. The divergent 2-curvature thus seems less
dangerous than expected, in these cases. The general formalism can be
straightforwardly used also to study the (bosonic part of the) fluctuations
around the closed strings, recently considered in connection with the AdS/CFT
duality, on AdS_5 \times S^5 and AdS_3 \times S^3 \times T^4.Comment: 19 pages, Late
Folded Three-Spin String Solutions in AdS_5 x S^5
We construct a spinning closed string solution in AdS_5 x S^5 which is folded
in the radial direction and has two equal spins in AdS_5 and a spin in S^5. The
energy expression of the three-spin solution specified by the folding and
winding numbers for the small S^5 spin shows a logarithmic behavior and a
one-third power behavior of the large total AdS_5 spin, in the long string and
in the short string located near the boundary of AdS_5 respectively. It
exhibits the non-regular expansion in the 't Hooft coupling constant, while it
takes the regular one when the S^5 spin becomes large.Comment: 14 pages, LaTeX, no figures, a reference adde
On the Classical String Solutions and String/Field Theory Duality
We classify almost all classical string configurations, considered in the
framework of the semi-classical limit of the string/gauge theory duality. Then,
we describe a procedure for obtaining the conserved quantities and the exact
classical string solutions in general string theory backgrounds, when the
string embedding coordinates depend non-linearly on the worldsheet time
parameter.Comment: LaTeX, 15 pages, no figures; V2: some typos corrected; V3: no
corrections, to appear in JHE
Spinning Pulsating String Solitons in AdS_5 x S^5
We point out the existence of some simple string solitons in AdS_5 x S^5,
which at the same time are spinning in AdS_5 and pulsating in S^5, or
vice-versa. This introduces an additional arbitrary constant into the scaling
relations between energy and spin or R-charge. The arbitrary constant is not an
angular momentum, but can be related to the amplitude of the pulsation. We
discuss the solutions in detail and consider the scaling relations. Pulsating
multi spin or multi R-charge solutions can also be constructed.Comment: 15 pages, Late
Charge Deficiency, Charge Transport and Comparison of Dimensions
We study the relative index of two orthogonal infinite dimensional
projections which, in the finite dimensional case, is the difference in their
dimensions. We relate the relative index to the Fredholm index of appropriate
operators, discuss its basic properties, and obtain various formulas for it. We
apply the relative index to counting the change in the number of electrons
below the Fermi energy of certain quantum systems and interpret it as the
charge deficiency. We study the relation of the charge deficiency with the
notion of adiabatic charge transport that arises from the consideration of the
adiabatic curvature. It is shown that, under a certain covariance,
(homogeneity), condition the two are related. The relative index is related to
Bellissard's theory of the Integer Hall effect. For Landau Hamiltonians the
relative index is computed explicitly for all Landau levels.Comment: 23 pages, no figure
Population differentiation and historical demography of the threatened snowy plover Charadrius nivosus (Cassin, 1858)
Delineating conservation units is a complex and often controversial process that is particularly challenging for highly vagile species. Here, we reassess population genetic structure and identify those populations of highest conservation value in the threatened snowy plover (Charadrius nivosus, Cassin, 1858), a partial migrant shorebird endemic to the Americas. We use four categories of genetic data—mitochondrial DNA (mtDNA), microsatellites, Z-linked and autosomal single nucleotide polymorphisms (SNPs)—to: (1) assess subspecies delineation and examine population structure (2) compare the sensitivity of the different types of genetic data to detect spatial genetic patterns, and (3) reconstruct demographic history of the populations analysed. Delineation of two traditionally recognised subspecies was broadly supported by all data. In addition, microsatellite and SNPs but not mtDNA supported the recognition of Caribbean snowy plovers (C. n. tenuirostris) and Floridian populations (eastern C. n. nivosus) as distinct genetic lineage and deme, respectively. Low migration rates estimated from autosomal SNPs (m < 0.03) reflect a general paucity of exchange between genetic lineages. In contrast, we detected strong unidirectional migration (m = 0.26) from the western into the eastern nivosus deme. Within western nivosus, we found no genetic differentiation between coastal Pacific and inland populations. The correlation between geographic and genetic distances was weak but significant for all genetic data sets. All demes showed signatures of bottlenecks occurring during the past 1000 years. We conclude that at least four snowy plover conservation units are warranted: in addition to subspecies nivosus and occidentalis, a third unit comprises the Caribbean tenuirostris lineage and a fourth unit the distinct eastern nivosus deme
The composition of the protosolar disk and the formation conditions for comets
Conditions in the protosolar nebula have left their mark in the composition
of cometary volatiles, thought to be some of the most pristine material in the
solar system. Cometary compositions represent the end point of processing that
began in the parent molecular cloud core and continued through the collapse of
that core to form the protosun and the solar nebula, and finally during the
evolution of the solar nebula itself as the cometary bodies were accreting.
Disentangling the effects of the various epochs on the final composition of a
comet is complicated. But comets are not the only source of information about
the solar nebula. Protostellar disks around young stars similar to the protosun
provide a way of investigating the evolution of disks similar to the solar
nebula while they are in the process of evolving to form their own solar
systems. In this way we can learn about the physical and chemical conditions
under which comets formed, and about the types of dynamical processing that
shaped the solar system we see today.
This paper summarizes some recent contributions to our understanding of both
cometary volatiles and the composition, structure and evolution of protostellar
disks.Comment: To appear in Space Science Reviews. The final publication is
available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-
Screening effects on meson masses from holography
We study the spectra of scalar and vector mesons in four dimensional strongly
coupled SQCD-like theories in the Veneziano limit. The gauge theories describe
the low energy dynamics of intersecting D3 and D7-branes on the singular and
deformed conifold and their strong coupling regime can be explored by means of
dual fully backreacted supergravity backgrounds. The mesons we focus on are
dual to fluctuations of the worldvolume gauge field on a probe D7-brane in
these backgrounds. As we will comment in detail, the general occurrence of
various UV pathologies in the D3-D7 set-ups under study, forces us to adapt the
standard holographic recipes to theories with intrinsic cutoffs. Just as for
QED, the low energy spectra for mesonic-like bound states will be consistent
and largely independent of the UV cutoffs. We will study in detail how these
spectra vary with the number of the fundamental sea flavors and their mass.Comment: 30 pages + appendices, 10 figures; v2: subsection 3.3.3 and some
comments adde
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