707 research outputs found
DC Conductivities from Non-Relativistic Scaling Geometries with Momentum Dissipation
We consider a gravitational theory with two Maxwell fields, a dilatonic
scalar and spatially dependent axions. Black brane solutions to this theory are
Lifshitz-like and violate hyperscaling. Working with electrically charged
solutions, we calculate analytically the holographic DC conductivities when
both gauge fields are allowed to fluctuate. We discuss some of the subtleties
associated with relating the horizon to the boundary data, focusing on the role
of Lifshitz asymptotics and the presence of multiple gauge fields. The axionic
scalars lead to momentum dissipation in the dual holographic theory. Finally,
we examine the behavior of the DC conductivities as a function of temperature,
and comment on the cases in which one can obtain a linear resistivity.Comment: 32 pages, 3 figures. Figures and references added. Discussion
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Mass And Force Relations For Einstein-Maxwell-Dilaton Black Holes
We investigate various properties of extremal dyonic static black holes in
Einstein-Maxwell-Dilaton theory. Using the fact that the long-range force
between two identical extremal black holes always vanishes, we obtain a simple
first-order ordinary differential equation for the black hole mass in terms of
its electric and magnetic charges. Although this equation appears not to be
solvable explicitly for general values of the strength a of the dilatonic
coupling to the Maxwell field, it nevertheless provides a powerful way of
characterising the black hole mass and the scalar charge. We make use of these
expressions to derive general results about the long-range force between two
non-identical extremal black holes. In particular, we argue that the force is
repulsive whenever a>1 and attractive whenever a<1 (it vanishes in the
intermediate BPS case a=1). The sign of the force is also correlated with the
sign of the binding energy between extremal black holes, as well as with the
convexity or concavity of the surface characterizing the extremal mass as a
function of the charges. Our work is motivated in part by the Repulsive Force
Conjecture and the question of whether long range forces between non-identical
states can shed new light on the Swampland.Comment: 34 pages, 3 figure
Role of meteorological factors on SARS-CoV-2 infection incidence in Italy and Spain before the vaccination campaign. A multi-city time series study
Numerous studies have been conducted worldwide to investigate if an association exists between meteorological factors and the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection incidence. Although research studies provide conflicting results, which can be partially explained by different methods used, some clear trends emerge on the role of weather conditions and SARS-CoV-2 infection, especially for temperature and humidity. This study sheds more light on the relationship between meteorological factors and SARS-CoV-2 infection incidence in 23 Italian and 52 Spanish cities. For the purposes of this study, daily air temperature, absolute and relative humidity, wind speed, ultraviolet radiation, and rainfall are considered exposure variables. We conducted a two-stage meta-regression. In the first stage, we estimated the exposure-response association through time series regression analysis at the municipal level. In the second stage, we pooled the association parameters using a meta-analytic model. The study demonstrates an association between meteorological factors and SARS-CoV-2 infection incidence. Specifically, low levels of ambient temperatures and absolute humidity were associated with an increased relative risk. On the other hand, low and high levels of relative humidity and ultraviolet radiation were associated with a decreased relative risk. Concerning wind speed and rainfall, higher values contributed to the reduction of the risk of infection. Overall, our results contribute to a better understanding of how the meteorological factors influence the spread of the SARS-CoV-2 and should be considered in a wider context of existing robust literature that highlight the importance of measures such as social distancing, improved hygiene, face masks and vaccination campaign
Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State
Using Suzaku and the Rossi X-ray Timing Explorer, we have conducted a series
of four simultaneous observations of the galactic black hole candidate Cyg X-1
in what were historically faint and spectrally hard low states. Additionally,
all of these observations occurred near superior conjunction with our line of
sight to the X-ray source passing through the dense phases of the focused wind
from the mass donating secondary. One of our observations was also simultaneous
with observations by the Chandra-High Energy Transmission Grating. These latter
spectra are crucial for revealing the ionized absorption due to the secondary's
focused wind. Such absorption is present and must be accounted for in all four
spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV
spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet
models of black hole hard states. Three models fit the spectra well: coronae
with thermal or mixed thermal/non-thermal electron populations, and jets. All
three models require a soft component that we fit with a low temperature disk
spectrum with an inner radius of only a few tens of GM/c^2. All three models
also agree that the known spectral break at 10\,keV is not solely due to the
presence of reflection, but each gives a different underlying explanation for
the augmentation of this break. Thus whereas all three models require that
there is a relativistically broadened Fe line, the strength and inner radius of
such a line is dependent upon the specific model, {thus making premature
line-based estimates of the black hole spin in the Cyg X-1 system. We look at
the relativistic line in detail, accounting for the narrow Fe emission and
ionized absorption detected by HETG. Although the specific relativistic
parameters of the line are continuum-dependent, none of the broad line fits
allow for an inner disk radius that is >40 GM/c^2.Comment: 22 pages, 16 figures. Uses emulateapj style. Final three tables
inserted as a figure to avoid issues with astro-ph's version of latex
mangling the use of lscape. To be published in the Astrophysical Journal,
January, 201
Morphological Changes in the Vestibular Epithelia and Ganglion Induced by Ototoxic Drug
The morphological changes of the vestibular sensory epithelia and the vestibular ganglions induced by Gentamicin (GM) were investigated using scanning electron microscope, transmission electron microscope and light microscope.
The guinea pigs were injected with a single application of 4 mg (0.1ml) of GM into the middle ear through the tympanic membrane. The vestibular organs and the ganglions were observed up to 6 months after the treatment. Four days after the injection, fused, ballooned and missing cilia were observed in the vestibular sensory epithelia. These changes progressed and extended toward the periphery of the crista and the macula. The changes of the vestibular ganglions were first observed one month after the treatment.
The degenerative process started from destruction of the mitochondrial cristae and vacuolization of the cytoplasm in the Schwann cell. The next step of the change was dissociation of the myelin sheath around the ganglion cell. The cytoplasmic organelles in the ganglion cell gradually deteriorated. At the later stage, the myelin sheath around the ganglion cell disappeared and the number of the cell reduced. Furthermore, the myelin sheath of the nerve fiber was dissociated.
In this study the signs of the vestibular ganglion damage were later than that of the vestibular organ. However, we thought the changes in the ganglion are probably due to direct influence of GM, since the degeneration was found to develop in a relatively short period
Efficacy and safety of electrochemotherapy combined with peritumoral IL-12 gene electrotransfer of canine mast cell tumours
Electrochemotherapy combined with peritumoral interleukin-12 (IL-12) gene electrotransfer was used for treatment of mast cell tumours in 18 client-owned dogs. Local tumour control, recurrence rate, as well as safety of combined therapy were evaluated. One month after the therapy, no side effects were recorded and good local tumour control was observed with high complete responses rate which even increased during the observation period to 72%. IL-12 gene electrotransfer resulted in 78% of patients with detectable serum IFN- and/or IL-12 levels. In the treated tumours vascular changes as well as minimal T-lymphocytes infiltration was observed. After 1week, the plasmid DNA was not detected intra- or peritumorally and no horizontal gene transfer was observed. In summary, our study demonstrates high antitumour efficacy of electrochemotherapy combined with IL-12
electrotransfer, which also prevented recurrences or distant metastases, as well as its safety and feasibility in treatment of canine mast cell tumours
Charge Dynamics in Cuprate Superconductors
In this lecture we present some interesting issues that arise when the
dynamics of the charge carriers in the CuO planes of the high temperature
superconductors is considered. Based on the qualitative picture of doping, set
by experiments and some previous calculations, we consider the strength of
various inter and intra-cell charge transfer susceptibilities, the question of
Coulomb screening and charge collective modes. The starting point is the usual
p-d model extended by the long range Coulomb (LRC) interaction. Within this
model it is possible to examine the case in which the LRC forces frustrate the
electronic phase separation, the instability which is present in the model
without an LRC interaction. While the static dielectric function in such
systems is negative down to arbitrarily small wavevectors, the system is not
unstable. We consider the dominant electronic charge susceptibilities and
possible consequences for the lattice properties.Comment: 14 pages, 15 figures, latex, to be published in "From Quantum
Mechanics to Technology", Lecture Notes in Physics, Springe
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