Morris-Thorne wormholes with a cosmological constant

First, the ideas introduced in the wormhole research field since the work of Morris and Thorne are briefly reviewed, namely, the issues of energy conditions, wormhole construction, stability, time machines and astrophysical signatures. Then, spherically symmetric and static traversable Morris-Thorne wormholes in the presence of a generic cosmological constant are analyzed. A matching of an interior solution to the unique exterior vacuum solution is done using directly the Einstein equations. The structure as well as several physical properties and characteristics of traversable wormholes due to the effects of the cosmological term are studied. Interesting equations appear in the process of matching. For instance, one finds that for asymptotically flat and anti-de Sitter spacetimes the surface tangential pressure of the thin-shell, at the boundary of the interior and exterior solutions, is always strictly positive, whereas for de Sitter spacetime it can take either sign as one could expect, being negative (tension) for relatively high cosmological constant and high wormhole radius, positive for relatively high mass and small wormhole radius, and zero in-between. Finally, some specific solutions with generic cosmological constant, based on the Morris-Thorne solutions, are provided.Comment: latex, 49 pages, 8 figures. Expanded version of the paper published in Physical Review

Canonical quantization of so-called non-Lagrangian systems

We present an approach to the canonical quantization of systems with equations of motion that are historically called non-Lagrangian equations. Our viewpoint of this problem is the following: despite the fact that a set of differential equations cannot be directly identified with a set of Euler-Lagrange equations, one can reformulate such a set in an equivalent first-order form which can always be treated as the Euler-Lagrange equations of a certain action. We construct such an action explicitly. It turns out that in the general case the hamiltonization and canonical quantization of such an action are non-trivial problems, since the theory involves time-dependent constraints. We adopt the general approach of hamiltonization and canonical quantization for such theories (Gitman, Tyutin, 1990) to the case under consideration. There exists an ambiguity (not reduced to a total time derivative) in associating a Lagrange function with a given set of equations. We present a complete description of this ambiguity. The proposed scheme is applied to the quantization of a general quadratic theory. In addition, we consider the quantization of a damped oscillator and of a radiating point-like charge.Comment: 13 page

Conserved Quasilocal Quantities and General Covariant Theories in Two Dimensions

General matterless--theories in 1+1 dimensions include dilaton gravity, Yang--Mills theory as well as non--Einsteinian gravity with dynamical torsion and higher power gravity, and even models of spherically symmetric d = 4 General Relativity. Their recent identification as special cases of 'Poisson--sigma--models' with simple general solution in an arbitrary gauge, allows a comprehensive discussion of the relation between the known absolutely conserved quantities in all those cases and Noether charges, resp. notions of quasilocal 'energy--momentum'. In contrast to Noether like quantities, quasilocal energy definitions require some sort of 'asymptotics' to allow an interpretation as a (gauge--independent) observable. Dilaton gravitation, although a little different in detail, shares this property with the other cases. We also present a simple generalization of the absolute conservation law for the case of interactions with matter of any type.Comment: 21 pages, LaTeX-fil

Laparoendoscopic Single-Site Surgery na realização de criptorquidectomia laparoscópica em um gato

A afecção congênita mais comum nos animais domésticos é denominada de criptorquidismo, sendo caracterizada pela não migração de um ou ambos os testículos até o escroto. O objetivo deste trabalho é relatar a técnica de criptorquidectomia videoassistida, através de um único acesso (LESS) sem dispositivos específicos, em um gato siamês com dois anos de idade e 3,9kg de massa corporal. Utilizou-se um único portal de 5 mm, inserido na linha média ventral na região pré-púbica. Por esse portal, a cavidade foi insuflada com CO2 medicinal, permitindo a obtenção do pneumoperitônio (8mmHg) a uma velocidade de 1 l/min. Após o inventário da cavidade abdominal, com o auxílio de um endoscópio de 5mm e 25o, identificou-se o testículo ectópico. Com a utilização de uma pinça de apreensão para mini laparoscopia (3mm), introduzida ao lado do trocarte (pelo mesmo acesso), o testículo foi fixado e tracionado para o exterior da cavidade abdominal para realização de hemostasia, não sendo necessária a ampliação da ferida cirúrgica. Após a secção dos vasos testiculares, o testículo foi totalmente liberado e o coto vascular devolvido à cavidade abdominal. O presente relato demonstra que a cirurgia laparoscópica por um único acesso (LESS) pode ser utilizada com sucesso no diagnóstico e tratamento de casos de criptorquidismo em gatos, com as possíveis vantagens que o acesso apresenta em relação à cirurgia convencional

Fate of non O157 Shigatoxigenic Escherichia coli in ovine manure composting

Livestock manure may contain pathogenic microorganisms which pose a risk to thehealth of animal or humans if the manure is not adequately treated or disposed of. Todetermine the fate of Shiga toxigenic Escherichia coli (STEC) nonO157 in composted manure from naturally colonized sheep, fresh manure was obtainedfrom animals carrying bacterial cells with stx1/ stx2 genes. Two composting systems were used, aerated andnon-aerated, and the experiments were done in Dracena city, São Paulo State. Everyweek, for seven weeks, one manure sample from six different points in both systemwas collected and cultured to determine the presence of E. coli, thepresence of the virulence genes in the cells, and also the susceptibility to 10antimicrobial drugs. The temperature was verified at each sampling. STEC non-O157survived for 49 days in both composting systems. E. coli non-STECshowing a high degree of antibiotic resistance was recovered all long the compostingperiod. No relationship was established between the presence of virulence genes andantibiotic resistance. The presence of virulence genes and multiple antibioticresistances in E. coli implicates a potential risk for these genespread in the human food chain, which is a reason for concern.Esterco de animais de criação pode conter microrganismos patogênicos, o querepresenta um risco para a saúde animal e a humana se o esterco não for adequadamentetratado ou descartado. Determinou-se o tempo necessário para a eliminação de Escherichia coli Shiga toxigenica (STEC) não O157 em estercoovino composto, obtido de fezes frescas de ovelhas naturalmente colonizadas com cepaSTEC não O157 que apresentavam os genes stx1/ stx2. Foram utilizados dois sistemas decompostagem, aerado e não aerado, em experimentos realizados na cidade de Dracena,estado de São Paulo. Todas as semanas, durante sete semanas, uma amostra decompostagem proveniente de seis pontos diferentes na leira, nos dois sistemas, foicoletada e semeada para a determinação da presença de E. coli, dapresença de genes de virulência nas células, bem como da sensibilidade dessas célulaa 10 drogas antimicrobianas. Em cada amostragem, a temperatura da leira foianalisada. Células de STEC não O157 sobreviveram por 49 dias nos dois sistemas decompostagem. E. coli não STEC com um alto grau de resistência aantibióticos foi recuperada ao longo de todo o período de compostagem. Não foipossível estabelecer relação entre a presença de genes de virulência e a resistênciaa antibióticos. A presença de genes de virulência e a resistência a múltiploantibióticos em E. coli representam um risco potencial para oespalhamento desses genes na cadeia alimentar humana, o que é motivo de grandepreocupação.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade de São Paulo - FORPUniversidade Estadual Paulista-Unesp FCAVUnespFCAV-UnespUniversidade Estadual Paulista-Unesp FCAVUnespFCAV-UnespFAPESP: 2008/00434-

Constraining the electric charges of some astronomical bodies in Reissner-Nordstrom spacetimes and generic r^-2-type power-law potentials from orbital motions

We put model-independent, dynamical constraints on the net electric charge Q of some astronomical and astrophysical objects by assuming that their exterior spacetimes are described by the Reissner-Nordstroem metric, which induces an additional potential U_RN \propto Q^2 r^-2. Our results extend to other hypothetical power-law interactions inducing extra-potentials U_pert = r^-2 as well (abridged).Comment: LaTex2e, 16 pages, 3 figures, no tables, 128 references. Version matching the one at press in General Relativity and Gravitation (GRG). arXiv admin note: substantial text overlap with arXiv:1112.351