Gravitational collapse of Type II fluid in higher dimensional space-times

We find the general solution of the Einstein equation for spherically symmetric collapse of Type II fluid (null strange quark fluid) in higher dimensions. It turns out that the nakedness and curvature strength of the shell focusing singularities carry over to higher dimensions. However, there is shrinkage of the initial data space for a naked singularity of the Vaidya collapse due to the presence of strange quark matter.Comment: RevTex4 style, 4 pages; Accepted in Phys. Rev.

Spherical Dust Collapse in Higher Dimensions

We consider here the question if it is possible to recover cosmic censorship when a transition is made to higher dimensional spacetimes, by studying the spherically symmetric dust collapse in an arbitrary higher spacetime dimension. It is pointed out that if only black holes are to result as end state of a continual gravitational collapse, several conditions must be imposed on the collapsing configuration, some of which may appear to be restrictive, and we need to study carefully if these can be suitably motivated physically in a realistic collapse scenario. It would appear that in a generic higher dimensional dust collapse, both black holes and naked singularities would develop as end states as indicated by the results here. The mathematical approach developed here generalizes and unifies the earlier available results on higher dimensional dust collapse as we point out. Further, the dependence of black hole or naked singularity end states as collapse outcomes, on the nature of the initial data from which the collapse develops, is brought out explicitly and in a transparent manner as we show here. Our method also allows us to consider here in some detail the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse.Comment: Revtex4, Title changed, To appear in Physical Review

Searching for the dual of the Maxwell-Chern-Simons model minimally coupled to dynamical U(1) charged matter

The possibility of dual equivalence between the self-dual and the Maxwell-Chern-Simons (MCS) models when the latter is coupled to dynamical, U(1) fermionic charged matter is examined. The proper coupling in the self-dual model is then disclosed using the iterative gauge embedding approach. We found that the self-dual potential needs to couple directly to the Chern-Kernel of the source in order to establish this equivalence besides the need for a self-interaction term to render the matter sector unchanged.Comment: 4 pages, RevTeX, new references, accepted for publication on Phys. Lett.

On the dual equivalence of the self-dual and topologically massive p-form models

We study the duality symmetry in p-form models containing a generalized $B_q\wedge F_{p+1}$ term in spacetime manifolds of arbitrary dimensions. The equivalence between the $B_q\wedge F_{p+1}$ self-dual ($SD_{B\wedge F}$) and the $B_q\wedge F_{p+1}$ topologically massive ($TM_{B\wedge F}$) models is established using a gauge embedding procedure, including the minimal coupling to conserved charged matter current. The minimal coupling adopted for both tensor fields in the self-dual representation is transformed into a non minimal magnetic like coupling in the topologically massive representation but with the currents swapped. It is known that to establish this equivalence a current-current interaction term is needed to render the matter sector unchanged. We show that both terms arise naturally from the embedding adopted. Comparison with Higgs/Julia-Toulouse duality is established.Comment: Latex file, 13 pages, no figures. Accepted for publication: Physics Letters B; a new paper added to the reference

Dimensionally continued Oppenheimer-Snyder gravitational collapse. I - solutions in even dimensions

The extension of the general relativity theory to higher dimensions, so that the field equations for the metric remain of second order, is done through the Lovelock action. This action can also be interpreted as the dimensionally continued Euler characteristics of lower dimensions. The theory has many constant coefficients apparently without any physical meaning. However, it is possible, in a natural way, to reduce to two (the cosmological and Newton's constant) these several arbitrary coefficients, yielding a restricted Lovelock gravity. In this process one separates theories in even dimensions from theories in odd dimensions. These theories have static black hole solutions. In general relativity, black holes appear as the final state of gravitational collapse. In this work, gravitational collapse of a regular dust fluid in even dimensional restricted Lovelock gravity is studied. It is found that black holes emerge as the final state for these regular initial conditions.Comment: Late

Gravitational collapse to toroidal, cylindrical and planar black holes

Gravitational collapse of non-spherical symmetric matter leads inevitably to non-static external spacetimes. It is shown here that gravitational collapse of matter with toroidal topology in a toroidal anti-de Sitter background proceeds to form a toroidal black hole. According to the analytical model presented, the collapsing matter absorbs energy in the form of radiation (be it scalar, neutrinos, electromagnetic, or gravitational) from the exterior spacetime. Upon decompactification of one or two coordinates of the torus one gets collapsing solutions of cylindrical or planar matter onto black strings or black membranes, respectively. The results have implications on the hoop conjecture.Comment: 6 pages, Revtex, modifications in the title and in the interpretation of some results, to appear in Physical Review

Intratesticular hypertonic sodium chloride solution treatment as a method of chemical castration in cattle

AbstractCastration of male calves is necessary for trading to facilitate handling and prevent reproduction. However, some methods of castration are traumatic and lead to economic losses because of infection and myiasis. The objective of the present study was to evaluate the efficiency of intratesticular injection (ITI) of hypertonic sodium chloride (NaCl; 20%) solution in male calf castration during the first weeks of life. Forty male calves were allocated to one of the following experimental groups: negative control—surgically castrated immediately after birth; positive control —intact males; G1—ITI from 1- to 5-day old; G2—ITI from 15- to 20-day old; and G3—ITI from 25- to 30-day old. Intratesticular injection induced coagulative necrosis of Leydig cells and seminiferous tubules leading to extensive fibrosis. Testosterone secretion and testicular development were severely impaired in 12-month-old animals from G1 and G2 groups (P < 0.05), in which no testicular structure and sperm cells were observed during breeding soundness evaluation. Rectal and scrotal temperatures were not affected by different procedures. In conclusion, ITI of hypertonic NaCl solution induces sterility and completely suppresses testosterone secretion when performed during the first 20 days of life

Naked singularities in Tolman-Bondi-de Sitter collapse

We study the formation of central naked singularities in spherical dust collapse with a cosmological constant. We find that the central curvature singularity is locally naked, Tipler strong, and generic, in the sense that it forms from a non-zero-measure set of regular initial data. We also find that the Weyl and Ricci curvature scalars diverge at the singularity, with the former dominating over the latter, thereby signaling the non-local origin of the singularity.Comment: 8 pages, RevTeX, 1 eps figure; accepted for publication in Phys. Rev.

Dual embedding of the Lorentz-violating electrodinamics and Batalin-Vilkovisky quantization

Modifications of the electromagnetic Maxwell Lagrangian in four dimensions have been considered by some authors. One may include an explicit massive term (Proca) and a topological but not Lorentz-invariant term within certain observational limits. We find the dual-corresponding gauge invariant version of this theory by using the recently suggested gauge embedding method. We enforce this dualisation procedure by showing that, in many cases, this is actually a constructive method to find a sort of parent action, which manifestly establishes duality. We also use the gauge invariant version of this theory to formulate a Batalin-Vilkovisky quantization and present a detailed discussion on the excitation spectrum.Comment: 8 page

Transjugular liver biopsy: experiencewith the trucut needle

OBJECTIVES: We describe the use of transjugular liver biopsy with the automated trucut needle and emphasize the benefits of this procedure in patients with cirrhosis and fibrosis.METHODS: Puncture of the right or left internal jugular vein was performed. A needle was advanced into the right hepatic vein through guides and catheters. Biopsies were obtained from the right liver lobe. Thirty-six transjugular biopsies were performed in 35 patients with clinical diagnosis of hepatopathy; all patients presented contraindication to the standard percutaneous liver biopsy.RESULTS: Out of 36 transjugular liver biopsies, one patient had to repeat the procedure because the initial specimen did not allow diagnosis. In two patients, it was not possible to complete the biopsy due to inability to advance the needle into the right hepatic vein and due to the occurrence of extrasystole; in these cases, the procedure was discontinued. Biopsy was successfully performed in 34 patients (94%), and a conclusive diagnosis was obtained in 32 (89%). There were no relevant complications.CONCLUSIONS: Transjugular liver biopsy allowed histopathological diagnosis in a group of patients presenting contraindications to the standard percutaneous technique. With the trucut needle, it was possible to obtain large, nonfragmented specimens, even in patients with cirrhosis and fibrosis.OBJETIVOS: O estudo descreve o uso de biópsia hepática transjugular com a agulha trucut automatizada e salienta os benefícios deste procedimento em pacientes com cirrose e fibrose hepática.MÉTODOS: Foi realizada punção da veia jugular interna direita ou esquerda. Através de fio guia e cateteres, uma agulha foi introduzida na veia hepática direita. As biópsias foram realizadas no lobo direito do fígado. Trinta e seis biópsias hepáticas transjugulares foram realizadas em 35 pacientes com diagnóstico clínico de hepatopatia; todos os pacientes apresentavam contra-indicação à biópsia hepática percutânea.RESULTADOS: Das 36 biópsias hepáticas transjugulares, um paciente precisou repetir o procedimento porque a amostra inicial não permitiu um diagnóstico conclusivo. Em dois pacientes, não foi possível completar a biópsia devido à impossibilidade de passar&nbsp; a agulha para a veia hepática direita e devido à ocorrência de extra-sístole; os procedimentos foram suspensos em ambos os casos. A biópsia foi efetuada com sucesso em 34 pacientes (94%), e um diagnóstico conclusivo foi obtido em 32 (89%). Não tivemos nenhuma complicação relevante.CONCLUSÕES: A biópsia hepática transjugular permitiu o diagnóstico histopatológico em um grupo de pacientes que apresentava contra-indicação à biópsia hepática percutânea. Com a agulha trucut, foi possível obter amostras maiores, não fragmentadas, mesmo em pacientes com cirrose e fibrose