907 research outputs found
Spacetime diffeomorphisms and the geodesic approximation
We present a spacetime diffeomorphism invariant formulation of the geodesic approximation to soliton dynamics
Superradiance by mini black holes with mirror
The superradiant scattering of massive scalar particles by a rotating mini
black hole is investigated. Imposing the mirror boundary condition, the system
becomes the so called black-hole bomb where the rotation energy of the black
hole is transferred to the scattered particle exponentially with time. Bulk
emissions as well as brane emissions are considered altogether. It is found
that the largest effects are expected for the brane emission of lower angular
modes with lighter mass and larger angular momentum of the black hole.
Possibilities of the forming the black-hole bomb at the LHC are discussed.Comment: 20 pages, 2 figures, 7 tables. More discussions. To appear in JHE
Selection of ligand peptides with the ability to detect antibodies in enzootic bovine leukosis
Peptides present in phages were selected using phage display technology and immunoassays to find out the antigenic mimetics of immunodominant epitopes of bovine leukosis virus (BLV). The use of antigenic mimetics may result in the enhancement of the sensitivity and specificity of the serologic diagnosis of enzootic bovine leukosis (EBL), contributing directly to disease control. The selections enabled the choice of clones which can be used as potential antigens in the diagnoses of diseases. The synthetic peptide produced from the selected sequences may be considered as an alternative for antigens in the serologic diagnosis of enzootic bovine leukosis.Key words: Diagnostic, antigens, enzootic bovine leukosis (EBL), phage display
Ultraspinning instability of anti-de Sitter black holes
Myers-Perry black holes with a single spin in d>5 have been shown to be
unstable if rotating sufficiently rapidly. We extend the numerical analysis
which allowed for that result to the asymptotically AdS case. We determine
numerically the stationary perturbations that mark the onset of the
instabilities for the modes that preserve the rotational symmetries of the
background. The parameter space of solutions is thoroughly analysed, and the
onset of the instabilities is obtained as a function of the cosmological
constant. Each of these perturbations has been conjectured to represent a
bifurcation point to a new phase of stationary AdS black holes, and this is
consistent with our results.Comment: 22 pages, 7 figures. v2: Reference added. Matches published versio
Liver Transplantation Prevents Progressive Neurological Impairment in Argininemia
Argininemia is a rare hereditary disease due to a deficiency of hepatic arginase, which is the last enzyme of the urea cycle and hydrolyzes arginine to ornithine and urea.
The onset of the disease is usually in childhood, and clinical manifestations include progressive spastic paraparesis and
mental retardation. Liver involvement is less frequent and usually not as severe as observed in other UCDs. For this reason, and because usually there is a major neurological
disease at diagnosis, patients with argininemia are rarely considered as candidates for OLT despite its capacity to
replace the deficient enzyme by an active one. We report on long-term follow-up of two patients with argininemia.
Patient 1 was diagnosed by the age of 20 months and despite appropriate conventional treatment progressed to spastic paraparesis with marked limp. OLT was performed at
10 years of age with normalization of plasmatic arginine levels and guanidino compounds. Ten years post-OLT, under free diet, there is no progression of neurological
lesions. The second patient (previously reported by our group) was diagnosed at 2 months of age, during a neonatal cholestasis workup study. OLT was performed at the age of
7 years, due to liver cirrhosis with portal hypertension, in the absence of neurological lesions and an almost-normal brain MRI. After OLT, under free diet, there was normalization of plasmatic arginine levels and guanidino compounds. Twelve years post-OLT, she presents a normal neurological examination.
We conclude that OLT prevents progressive neurological impairment in argininemia and should be considered when appropriate conventional treatment fails
Universal thermal and electrical conductivity from holography
It is known from earlier work of Iqbal, Liu (arXiv:0809.3808) that the
boundary transport coefficients such as electrical conductivity (at vanishing
chemical potential), shear viscosity etc. at low frequency and finite
temperature can be expressed in terms of geometrical quantities evaluated at
the horizon. In the case of electrical conductivity, at zero chemical potential
gauge field fluctuation and metric fluctuation decouples, resulting in a
trivial flow from horizon to boundary. In the presence of chemical potential,
the story becomes complicated due to the fact that gauge field and metric
fluctuation can no longer be decoupled. This results in a nontrivial flow from
horizon to boundary. Though horizon conductivity can be expressed in terms of
geometrical quantities evaluated at the horizon, there exist no such neat
result for electrical conductivity at the boundary. In this paper we propose an
expression for boundary conductivity expressed in terms of geometrical
quantities evaluated at the horizon and thermodynamical quantities. We also
consider the theory at finite cutoff outside the horizon (arXiv:1006.1902) and
give an expression for cutoff dependent electrical conductivity, which
interpolates smoothly between horizon conductivity and boundary conductivity .
Using the results about the electrical conductivity we gain much insight into
the universality of thermal conductivity to viscosity ratio proposed in
arXiv:0912.2719.Comment: An appendix added discussing relation between boundary conductivity
and universal conductivity of stretched horizon, version to be published in
JHE
Distributions of charged massive scalars and fermions from evaporating higher-dimensional black holes
A detailed numerical analysis is performed to obtain the Hawking spectrum for
charged, massive brane scalars and fermions on the approximate background of a
brane charged rotating higher-dimensional black hole constructed in
arXiv:0907.5107. We formulate the problem in terms of a "spinor-like" first
order system of differential wave equations not only for fermions, but for
scalars as well and integrate it numerically. Flux spectra are presented for
non-zero mass, charge and rotation, confirming and extending previous results
based on analytic approximations. In particular we describe an inverted charge
splitting at low energies, which is not present in four or five dimensions and
increases with the number of extra dimensions. This provides another signature
of the evaporation of higher-dimensional black holes in TeV scale gravity
scenarios.Comment: 19 pages, 6 figures, minor typos corrected, 1 page added with a
discussion on higher spins, added reference
The Eyes Have It: Sex and Sexual Orientation Differences in Pupil Dilation Patterns
Recent research suggests profound sex and sexual orientation differences in sexual response. These results, however, are based on measures of genital arousal, which have potential limitations such as volunteer bias and differential measures for the sexes. The present study introduces a measure less affected by these limitations. We assessed the pupil dilation of 325 men and women of various sexual orientations to male and female erotic stimuli. Results supported hypotheses. In general, self-reported sexual orientation corresponded with pupil dilation to men and women. Among men, substantial dilation to both sexes was most common in bisexual-identified men. In contrast, among women, substantial dilation to both sexes was most common in heterosexual-identified women. Possible reasons for these differences are discussed. Because the measure of pupil dilation is less invasive than previous measures of sexual response, it allows for studying diverse age and cultural populations, usually not included in sexuality research
Modulated Instability in Five-Dimensional U(1) Charged AdS Black Hole with R**2-term
We study the effect of R**2 term to the modulated instability in the U(1)
charged black hole in five-dimensional Anti-de Sitter space-time. We consider
the first-order corrections of R**2 term to the background and the linear order
perturbations in the equations of motion. From the analysis, we clarify the
effect of R**2 term in the modulated instability, and conclude that
fluctuations are stable in the whole bulk in the range of values the
coefficient of R**2 term can take.Comment: 19 pages, 1 figures; (v4) Published version in JHE
An instability of higher-dimensional rotating black holes
We present the first example of a linearized gravitational instability of an
asymptotically flat vacuum black hole. We study perturbations of a Myers-Perry
black hole with equal angular momenta in an odd number of dimensions. We find
no evidence of any instability in five or seven dimensions, but in nine
dimensions, for sufficiently rapid rotation, we find perturbations that grow
exponentially in time. The onset of instability is associated with the
appearance of time-independent perturbations which generically break all but
one of the rotational symmetries. This is interpreted as evidence for the
existence of a new 70-parameter family of black hole solutions with only a
single rotational symmetry. We also present results for the Gregory-Laflamme
instability of rotating black strings, demonstrating that rotation makes black
strings more unstable.Comment: 38 pages, 13 figure
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