32,949 research outputs found
Probing Solar Convection
In the solar convection zone acoustic waves are scattered by turbulent sound
speed fluctuations. In this paper the scattering of waves by convective cells
is treated using Rytov's technique. Particular care is taken to include
diffraction effects which are important especially for high-degree modes that
are confined to the surface layers of the Sun. The scattering leads to damping
of the waves and causes a phase shift. Damping manifests itself in the width of
the spectral peak of p-mode eigenfrequencies. The contribution of scattering to
the line widths is estimated and the sensitivity of the results on the assumed
spectrum of the turbulence is studied. Finally the theoretical predictions are
compared with recently measured line widths of high-degree modes.Comment: 26 pages, 7 figures, accepted by MNRA
Radiation from the non-extremal fuzzball
The fuzzball proposal says that the information of the black hole state is
distributed throughout the interior of the horizon in a `quantum fuzz'. There
are special microstates where in the dual CFT we have `many excitations in the
same state'; these are described by regular classical geometries without
horizons. Jejjala et.al constructed non-extremal regular geometries of this
type. Cardoso et. al then found that these geometries had a classical
instability. In this paper we show that the energy radiated through the
unstable modes is exactly the Hawking radiation for these microstates. We do
this by (i) starting with the semiclassical Hawking radiation rate (ii) using
it to find the emission vertex in the CFT (iii) replacing the Boltzman
distributions of the generic CFT state with the ones describing the microstate
of interest (iv) observing that the emission now reproduces the classical
instability. Because the CFT has `many excitations in the same state' we get
the physics of a Bose-Einstein condensate rather than a thermal gas, and the
usually slow Hawking emission increases, by Bose enhancement, to a classically
radiated field. This system therefore provides a complete gravity description
of information-carrying radiation from a special microstate of the nonextremal
hole.Comment: corrected typo
The Relationship between the UniProt Knowledgebase (UniProtKB) and the IntAct Molecular Interaction Databases
IntAct provides a freely available, open source database system and analysis tools for protein interaction data. All interactions are derived from literature curation or direct user submission and all experimental information relating to binary protein-protein
interactions is entered into the IntAct database by curators, via a web-based editor. Interaction information is added to the SUBUNIT comment and the RP line of the relevant publication within the UniProtKB entry. There may be a single INTERACTION comment present within a UniProtKB entry, which conveys information relevant to binary protein-protein interactions. This is automatically derived from the IntAct database and is updated on a triweekly basis. Interactions can be derived by any appropriate experimental method but must be confirmed by a second interaction if resulting from a single yeast2hybrid experiment. For large-scale experiments, interactions are considered if a high confidence score is assigned by the authors. The INTERACTION line contains a direct link to IntAct that provides detailed information for the experimental support. These lines are not changed manually and any discrepancy is reported to IntAct for updates. There is also a database crossreference line within the UniProtKB entry i.e.: DR IntAct _UniProtKB AC, which directs the user to additional interaction data for that molecule. 
UniProt is supported by grants from the National Institutes of Health, European Commission, Swiss Federal Government and PATRIC BRC.
IntAct is funded by the European Commission under FELICS, contract number 021902 (RII3) within the Research Infrastructure Action of the FP6 "Structuring the European Research Area" Programme
de Haas-van Alphen effect investigation of the electronic structure of Al substituted MgB_2
We report a de Haas-van Alphen (dHvA) study of the electronic structure of Al
doped crystals of MgB. We have measured crystals with % Al which
have a of 33.6 K, (% lower than pure MgB). dHvA frequencies
for the tube orbits in the doped samples are lower than in pure
MgB, implying a reduction in the number of holes in this sheet of
Fermi surface. The mass of the quasiparticles on the larger orbit is
lighter than the pure case indicating a reduction in electron-phonon coupling
constant . These observations are compared with band structure
calculations, and found to be in excellent agreement.Comment: 4 pages with figure
Non-uniqueness in conformal formulations of the Einstein constraints
Standard methods in non-linear analysis are used to show that there exists a
parabolic branching of solutions of the Lichnerowicz-York equation with an
unscaled source. We also apply these methods to the extended conformal thin
sandwich formulation and show that if the linearised system develops a kernel
solution for sufficiently large initial data then we obtain parabolic solution
curves for the conformal factor, lapse and shift identical to those found
numerically by Pfeiffer and York. The implications of these results for
constrained evolutions are discussed.Comment: Arguments clarified and typos corrected. Matches published versio
Quasiparticle Relaxation Across a Spin Gap in the Itinerant Antiferromagnet UNiGa5
Ultrafast time-resolved photoinduced reflectivity is measured for the
itinerant antiferromagnet UNiGa (85 K) from room
temperature to 10 K. The relaxation time shows a sharp increase at
consistent with the opening of a spin gap. In addition, the temperature
dependence of below is consistent with the opening of a spin gap
leading to a quasiparticle recombination bottleneck as revealed by the
Rothwarf-Taylor model. This contrasts with canonical heavy fermions such as
CeCoIn where the recombination bottleneck arises from the hybridization
gap.Comment: 5 pages, 5 figure
Supergravity, Supermembrane and M(atrix) model on PP-Waves
In the first part of this paper, we study the back-reaction of large-N light
cone momentum on the maximally supersymmetric anti-pp-wave background. This
gives the type IIA geometry of large-N D0-branes on curved space with fluxes.
By taking an appropriate decoupling limit, we conjecture a new duality between
string theory on that background and dual field theory on D0-branes which we
derive by calculating linear coupling terms. Agreement of decoupling
quantities, SO(3) \times SO(6) isometry and Higgs branch on both theories are
shown. Also we find whenever dual field theory is weakly coupled, the curvature
of the geometry is large. In the second part of this paper, we derive the
supermembrane action on a general pp-wave background only through the
properties of null Killing vector and through this, derive the Matrix model.Comment: 19 pages, LaTeX. v2: corrected interpretation of supergravity
solutio
An interferometric complementarity experiment in a bulk Nuclear Magnetic Resonance ensemble
We have experimentally demonstrated the interferometric complementarity,
which relates the distinguishability quantifying the amount of which-way
(WW) information to the fringe visibility characterizing the wave feature
of a quantum entity, in a bulk ensemble by Nuclear Magnetic Resonance (NMR)
techniques. We primarily concern on the intermediate cases: partial fringe
visibility and incomplete WW information. We propose a quantitative measure of
by an alternative geometric strategy and investigate the relation between
and entanglement. By measuring and independently, it turns out that
the duality relation holds for pure quantum states of the
markers.Comment: 13 page, 5 PS figure
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