Holographic phase transition from dyons in an AdS black hole background

We construct a dyon solution for a Yang-Mills-Higgs theory in a 4 dimensional Schwarzschild-anti-de Sitter black hole background with temperature T. We then apply the AdS/CFT correspondence to describe the strong coupling regime of a 2+1 quantum field theory which undergoes a phase transition exhibiting the condensation of a composite charge operator below a critical temperature $T_c$.Comment: 19 pages, 7 figures. Minor corrections, references added. Version published in JHEP

SO(3) \times U(1) isometric instantons with non abelian hair in four dimensional string theory

We compute the exact effective string vacuum backgrounds of the level $k = 81/19 SU(2,1)/U(1)$ coset model. A compact SU(2) isometry present in this seven dimensional solution allows to interpreting it after compactification as a four dimensional non-abelian SU(2) charged instanton with a singular submanifold and an $SO(3) \times U(1)$ isometry. The semiclassical backgrounds, solutions of the type II strings, present similar characteristics.Comment: 12 pages, latex fil

Gravitating sphalerons and sphaleron black holes in asymptotically anti-de Sitter spacetime

Numerical arguments are presented for the existence of spherically symmetric regular and black hole solutions of the EYMH equations with a negative cosmological constant. These solutions approach asymptotically the anti-de Sitter spacetime. The main properties of the solutions and the differences with respect to the asymptotically flat case are discussed. The instability of the gravitating sphaleron solutions is also proven.Comment: 30 pages, LaTeX, 8 Encapsulated PostScript figure

Monopoles, Dyons and Black Holes in the Four-Dimensional Einstein-Yang-Mills Theory

A continuum of monopole, dyon and black hole solutions exist in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space. Their structure is studied in detail. The solutions are classified by non-Abelian electric and magnetic charges and the ADM mass. The stability of the solutions which have no node in non-Abelian magnetic fields is established. There exist critical spacetime solutions which terminate at a finite radius, and have universal behavior. The moduli space of the solutions exhibits a fractal structure as the cosmological constant approaches zero.Comment: 36 Pages, 16 Figures. Minor typos corrected and one figure modifie

Gauge invariant perturbation theory and non-critical string models of Yang-Mills theories

We carry out a gauge invariant analysis of certain perturbations of $D-2$-branes solutions of low energy string theories. We get generically a system of second order coupled differential equations, and show that only in very particular cases it is possible to reduce it to just one differential equation. Later, we apply it to a multi-parameter, generically singular family of constant dilaton solutions of non-critical string theories in $D$ dimensions, a generalization of that recently found in arXiv:0709.0471[hep-th]. According to arguments coming from the holographic gauge theory-gravity correspondence, and at least in some region of the parameters space, we obtain glue-ball spectra of Yang-Mills theories in diverse dimensions, putting special emphasis in the scalar metric perturbations not considered previously in the literature in the non critical setup. We compare our numerical results to those studied previously and to lattice results, finding qualitative and in some cases, tuning properly the parameters, quantitative agreement. These results seem to show some kind of universality of the models, as well as an irrelevance of the singular character of the solutions. We also develop the analysis for the T-dual, non trivial dilaton family of solutions, showing perfect agreement between them.Comment: A new reference added

Exact monopole instantons and cosmological solutions in string theory from abelian dimensional reduction

We compute the exact string vacuum backgrounds corresponding to the non-compact coset theory $SU(2,1)/SU(2)$. The conformal field theory defined by the level $k= 4$ results in a five dimensional singular solution that factorizes in an asymptotic region as the linear dilaton solution and a $S^3$ model. It presents two abelian compact isometries that allow to reinterpreting it from a four dimensional point of view as a stationary and magnetically charged space-time resembling in some aspects the Kerr-Newman solution of general relativity. The $k=\frac{13}{7}$ theory on the other hand describes a cosmological solution that interpolates between a singular phase at short times and a $S^1 \times S^2$ universe after some planckian times.Comment: 18 pages, section 5 replaced by 5 and 6, references added; to appear in Phys. Rev.

CAUSAS DE EXCLUSÃO DE DOADORES VIVOS DE RIM NO SERVIÇO DE TRANSPLANTE DE UM HOSPITAL DE TERCEIRO NÍVEL NO NOROESTE DO MÉXICO

Objective: To identify the causes for exclusion of living kidney donors at a third-level hospital in northwestern Mexico. Materials and methods: An observational, cross-sectional, descriptive and retrospective study, in which the medicalrecords of candidates for living kidney donation were evaluated from January 1, 2019 to December 31, 2021. Results: Out of the 30 selected records, only 6.6 % (2) were chosen as donors, i.e., the rejection rate of the potential candidates was 93.3 % (28). The average age was 40.7 years; when divided into age groups, it was observed that 7.44 % were ≤ 39 years, 5.31 % were ≥ 50 years and 4.25 % were in the 40–49 age range. The main pathologies that caused therejection of living donors were chronic diseases such as unknown renal disease, obesity, diabetes mellitus, systemic hypertension and heart diseases, which accounted for 60.7 %. The desire to donate was more frequent among blood relatives than non-blood relatives. In the case of blood relatives, i.e., siblings, parents, children, uncles, aunts, etc., 64.2 % were rejected, while 34.7 % of non-blood relatives, including spouses and friends, were rejected.Conclusions: Based on the body mass index (BMI), the results showed that overweight and obesity were the main causes of exclusion, a situation that is consistent with the Mexican epidemiological profile. The number of living donors at ourcenter has been reduced because most of the population is not healthy and has obesity, which affects the willingness to be a candidate for living kidney donation.Objetivo: Identificar las causas de exclusión de los donantes renales vivos en un centro hospitalario de tercer nivel en el noroeste de México.Materiales y métodos: Estudio de tipo observacional, transversal, descriptivo, retrospectivo. Se realizó la evaluación de los expedientes clínicos de los candidatos vivos para donación renal, que abarcó el periodo comprendido entre el 1 de enero de 2019 y el 31 de diciembre de 2021. Resultados: De los 30 expedientes seleccionados, solo se eligieron 2 (6,6 %) donadores, es decir, existió un índice de rechazo de 28 (93,3 %) de los potenciales candidatos. La edad promedio fue de 40,7 años; al dividirlos en grupos de edad, se observó que el 7,44 % fueron ≤39 años; el 5,31 %, ≥50 años; y el 4,25 %, de 40 a 49 años. Dentro de las principales patologías que originaron el rechazo del donador vivo se encuentran las enfermedades crónicas, como afección renal desconocida, obesidad, diabetes mellitus, hipertensión arterial sistémica y cardiopatías, que representaron el 60,7 %. El deseo de donares más frecuente entre consanguíneos que en no consanguíneos. En el caso de los consanguíneos, es decir, hermanos, padres, hijos, tíos, etc., el 64,2 % fue rechazado; en los no consanguíneos, el 34,7 %, que incluía a esposos y amigos. Conclusiones: Los resultados obtenidos sobre el índice de masa corporal (IMC) mostraron que el sobrepeso y laobesidad fueron las principales causas de exclusión, circunstancia que es particular en nuestro país respecto a su perfil epidemiológico. La cantidad de donantes vivos en nuestro centro se redujo porque la mayor parte de la población no es sana, padece obesidad y ello repercute al momento de presentarse como candidato a donante.Resumo Objetivo: Identificar as causas de exclusão de doadores vivos de rim. Material e métodos: Estudo observacional, transversal, descritivo, retrospectivo, no qual é realizada a análise dos prontuários de possíveis doadores de rim no período de 1º de janeiro de 2019 a 31 de dezembro de 2021. Identificar diagnósticos que excluam uma pessoa como doador. Resultados: Dos 30 arquivos selecionados, apenas 2 (6,6%) foram escolhidos como doadores, ou seja, houve uma taxa de rejeição de 28 (93,3%). Os principais motivos de rejeição foram doenças crônicas, indicando 60,7% em que se encontraram doença renal desconhecida, obesidade, diabetes mellitus, hipertensão arterial sistêmica e cardiopatia. Conclusão: Os resultados obtidos no índice de massa corporal (IMC) mostraram o sobrepeso e a obesidade como uma das principais causas de exclusão com 21,4%, informação semelhante à de Lapasia et al., que descreve a obesidade como a principal causa de rejeição representando quase 40% dos doadores. Ezzaki et al, também a descrevem como causa de exclusão

Edge Currents in Non-commutative Chern-Simons Theory from a New Matrix Model

This paper discusses the formulation of the non-commutative Chern-Simons (CS) theory where the spatial slice, an infinite strip, is a manifold with boundaries. As standard star products are not correct for such manifolds, the standard non-commutative CS theory is not also appropriate here. Instead we formulate a new finite-dimensional matrix CS model as an approximation to the CS theory on the strip. A work which has points of contact with ours is due to Lizzi, Vitale and Zampini where the authors obtain a description for the fuzzy disc. The gauge fields in our approach are operators supported on a subspace of finite dimension N+\eta of the Hilbert space of eigenstates of a simple harmonic oscillator with N, \eta \in Z^+ and N \neq 0. This oscillator is associated with the underlying Moyal plane. The resultant matrix CS theory has a fuzzy edge. It becomes the required sharp edge when N and \eta goes to infinity in a suitable sense. The non-commutative CS theory on the strip is defined by this limiting procedure. After performing the canonical constraint analysis of the matrix theory, we find that there are edge observables in the theory generating a Lie algebra with properties similar to that of a non-abelian Kac-Moody algebra. Our study shows that there are (\eta+1)^2 abelian charges (observables) given by the matrix elements (\cal A_i)_{N-1 N-1} and (\cal A_i)_{nm} (where n or m \geq N) of the gauge fields, that obey certain standard canonical commutation relations. In addition, the theory contains three unique non-abelian charges, localized near the N^th level. We show that all non-abelian edge observables except these three can be constructed from the abelian charges above. Using the results of this analysis we discuss the large N and \eta limit.Comment: LaTeX, 16 pages and 2 figures. Comments added in sections 4 and 5. A minor error corrected in section 4. Figures replaced for clarity. Typos correcte

Transfer Hydrogenation of Azo Compounds with Ammonia Borane Using a Simple Acyclic Phosphite Precatalyst

Tris(quinolin-8-yl)phosphite, P(Oquin)(3), promotes the dehydrogenation of H3N center dot BH3 (AB) and the transfer hydrogenation of azoarenes using ammonia borane (AB) as H-2 source. The metal-free reduction of azoarenes proceeds under mild reaction conditions upon which several diphenylhydrazine derivatives are obtained in high yields. The reactivity of P(Oquin)(3) toward AB was evaluated through NMR in situ tests. The rate of the reaction, activation parameters, deuterium kinetic isotope effect (DKIE) and linear-free energy relationship were investigated. Such mechanistic and kinetic studies suggest that P(Oquin)(3) is a precatalyst and that AB is likely involved in more than one stage of the reaction pathway. Furthermore, the kinetic data indicate that the reaction proceeds through an ordered transition state, possibly associative

Gravitating Instantons In 3 Dimensions

We study the Einstein-Chern-Simons gravity coupled to Yang-Mills-Higgs theory in three dimensional Euclidean space with cosmological constant. The classical equations reduce to Bogomol'nyi type first order equations in curved space. There are BPS type gauge theory instanton (monopole) solutions of finite action in a gravitational instanton which itself has a finite action. We also discuss gauge theory instantons in the vacuum (zero action) AdS space. In addition we point out to some exact solutions which are singular.Comment: 17 pages, 4 figures, title has changed, gravitational instanton actions are adde