Extremal Vanishing Horizon Kerr-AdS Black Holes at Ultraspinning Limit

By utilizing the ultraspinning limit we generate a new class of extremal vanishing horizon (EVH) black holes in odd dimensions ($d\geq5$). Starting from the general multi-spinning Kerr-AdS metrics, we show the EVH limit commutes with the ultraspinning limit, in which the resulting solutions possess a non-compact but finite area manifold for all $(t,r\neq r_+)=const.$ slices. We also demonstrate the near horizon geometries of obtained ultraspinning EVH solutions contain an AdS$_3$ throats, where it would be a BTZ black hole in the near EVH cases. The commutativity of the ultraspinning and near horizon limits for EVH solutions is confirmed as well. Furthermore, we discuss only the five-dimensional case near the EVH point can be viewed as a super-entropic black hole. We also show that the thermodynamics of the obtained solutions agree with the BTZ black hole. Moreover we investigate the EVH/CFT proposal, demonstrating the entropy of $2$d dual CFT and Bekenstein-Hawking entropy are equivalent.Comment: 29 pages, 3 figures, references added, typos corrected, revised version to match published versio

Three Theorems on Near Horizon Extremal Vanishing Horizon Geometries

EVH black holes are Extremal black holes with Vanishing Horizon area, where vanishing of horizon area is a result of having a vanishing one-cycle on the horizon. We prove three theorems regarding near horizon geometry of EVH black hole solutions to generic Einstein gravity theories in diverse dimensions. These generic gravity theories are Einstein-Maxwell-dilaton-Lambda theories, and gauged or ungauged supergravity theories with U(1) Maxwell fields. Our three theorems are: (1) The near horizon geometry of any EVH black hole has a three dimensional maximally symmetric subspace. (2) If the energy momentum tensor of the theory satisfies strong energy condition either this 3d part is an AdS3, or the solution is a direct product of a locally 3d flat space and a d-3 dimensional part. (3) These results extend to the near horizon geometry of near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry.Comment: 5 page

Near Horizon Structure of Extremal Vanishing Horizon Black Holes

We study the near horizon structure of Extremal Vanishing Horizon (EVH) black holes, extremal black holes with vanishing horizon area with a vanishing one-cycle on the horizon. We construct the most general near horizon EVH and near-EVH ansatz for the metric and other fields, like dilaton and gauge fields which may be present in the theory. We prove that (1) the near horizon EVH geometry for generic gravity theory in generic dimension has a three dimensional maximally symmetric subspace; (2) if the matter fields of the theory satisfy strong energy condition either this 3d part is AdS$_3$, or the solution is a direct product of a locally 3d flat space and a $d-3$ dimensional part; (3) these results extend to the near horizon geometry of near-EVH black holes, for which the AdS$_3$ part is replaced with BTZ geometry. We present some specific near horizon EVH geometries in 3, 4 and 5 dimensions for which there is a classification. We also briefly discuss implications of these generic results for generic (gauged) supergravity theories and also for the thermodynamics of near-EVH black holes and the EVH/CFT proposal.Comment: 26 page

Anthropometric indices in individuals infected with ascaris lumbericoids in Iran

Context: Ascaris Lumbericoids infection is more common in children and teenagers and in areas with poor sanitation or crowded living conditions. Largest of all the parasites inhabiting the human intestine it is also the most common of parasitic infections in developing countries. It has been reported to infect about one-fourth of the world population. Chronic ascariasis has been reported to adversely effect the growth rate and anthropometric indices in infected individuals of growing age. Aims: The goal of this research was to evaluate the anthropometric indices in individuals infected with Ascaris in Hamedan province of Iran. Settings and Design: This was a descriptive cross sectional study. Methods and Material: Six hundred fourteen randomly selected individuals who were inhabitants of Hamedan province of Iran were chosen for this study. Stool samples of these individuals were collected and then experimented with Formel-Ether method to determine Ascaris Lumbericoids infection. Height and weight of these individuals were measured and compared with the indices related to NCHS. Demographic information of these individuals was entered into questionnaires and ultimately was analyzed with SPSS software. Results: Out of the total study population, 16.5% of individuals were found to be infected with Ascaris. Out of the individuals infected with Ascaris, 1% were underweight. In the age groups of 6-10, 11-15, 16-20 years, 3.5%, 5.1% and 3.5% were found to be suffering from malnutrition, respectively. Conclusion: Malabsorption in children might result in malnutrition. In this study, few individuals infected with Ascaris had malnutrition, thus Ascaris infection may not be an important cause of malnutrition among children in our area

Near Horizon Structure of Extremal Vanishing Horizon Black Holes

We study the near horizon structure of Extremal Vanishing Horizon (EVH) black holes, extremal black holes with vanishing horizon area with a vanishing one-cycle on the horizon. We construct the most general near horizon EVH and near-EVH ansatz for the metric and other fields, like dilaton and gauge fields which may be present in the theory. We prove that (1) the near horizon EVH geometry for generic gravity theory in generic dimension has a three dimensional maximally symmetric subspace; (2) if the matter fields of the theory satisfy strong energy condition either this 3d part is AdS$_3$, or the solution is a direct product of a locally 3d flat space and a $d-3$ dimensional part; (3) these results extend to the near horizon geometry of near-EVH black holes, for which the AdS$_3$ part is replaced with BTZ geometry. We present some specific near horizon EVH geometries in 3, 4 and 5 dimensions for which there is a classification. We also briefly discuss implications of these generic results for generic (gauged) supergravity theories and also for the thermodynamics of near-EVH black holes and the EVH/CFT proposal.Comment: 26 page

New Insights into Variations in Enceladus Plume Particle Launch Velocities from Cassini-VIMS spectral data

Enceladus' plume consists mainly of a mixture of water vapor and solid ice particles that may originate from a subsurface ocean. The physical processes underlying Enceladus' plume particle dynamics are still being debated, and quantifying the particles' size distribution and launch velocities can help constrain these processes. Cassini's Visual and Infrared Mapping Spectrometer (VIMS) observed the Enceladus plume over a wavelength range of 0.9 micron to 5.0 microns for a significant fraction of Enceladus' orbital period on three dates in the summer of 2017. We find that the relative brightness of the plume on these different dates varies with wavelength, implying that the particle size distribution in the plume changes over time. These observations also enable us to study how the particles' launch velocities vary with time and observed wavelength. We find that the typical launch velocity of particles remains between 140 m/s and 148 m/s at wavelengths between 1.2 microns and 3.7 microns. This may not be consistent with prior models where particles are only accelerated by interactions with the vent walls and gas, and could imply that mutual particle collisions close to the vent are more important than previously recognized.Comment: 13 pages, 8 figures, accepted for publication in PS

On black hole temperature in Horndeski gravity

It has been observed that for black holes in certain family of Horndeski gravity theories Wald's entropy formula does not lead to the correct first law for black hole thermodynamics. For this family of Horndeski theories speeds of propagation of gravitons and photons are in general different and gravitons move on an effective metric different than the one seen by photons. We show that the temperature of the black hole should be modified from surface gravity over 2\u3c0 to include effects of this effective metric. The modified temperature, with the entropy unambiguously computed by the solution phase space method, yields the correct first law. Our results have far reaching implications for the Hawking radiation and species problem, going beyond the Horndeski theories

The protective effect of bone marrow mesenchymal stem cells in a rat model of ischemic stroke via reducing the C-Jun N-terminal kinase expression

Ischemic stroke is the main cause of disability and mortality worldwide. Apoptosis and inflammation have an important role in ischemic brain injury. Mesenchymal stem cells (MSCs) have protective effects on stroke treatment due to anti-inflammatory properties. The inhibition of the C-Jun N-terminal kinase (JNK) pathway may be one of the molecular mechanisms of the neuroprotective effect of MSCs in ischemic brain injury. Twenty-eight male Wistar rats were divided randomly into 3 groups. Except the sham group, others subjected to transient middle cerebral artery occlusion (tMCAO). Bone marrow MSCs or saline were injected 3 h after tMCAO. Sensorimotor behavioral tests were performed 24 and 72 h after ischemia and reperfusion (I/R). The rats were sacrificed 72 h after I/R and infarct volume was measured by TTC staining. The number of apoptotic neurons and astrocytes in the peri-infarct area was assessed by TUNEL assay. The morphology of cells was checked by Nissl staining, and the expression of p-JNK was detected by immunohistochemistry and Western blot. Behavioral scores were improved and infarct volume was reduced by MSCs 24 h and 72 h after tMCAO. TUNEL assay showed that neuronal apoptosis and astroglial activity in the penumbra region were reduced by MSCs. Also, Nissl staining showed lower neuronal apoptosis in BMSCs-treated rats compared to controls. JNK phosphorylation which was profoundly induced by ischemia was significantly decreased after MSCs treatment. We concluded that anti-apoptotic and anti-inflammatory effects of MSCs therapy after brain ischemia may be associated with the down-regulation of p-JNK. © 2019 Elsevier Gmb