Acoustic Black Holes from Abelian Higgs Model with Lorentz Symmetry Breaking

In this paper we derive acoustic black hole metrics in the (3+1) and (2+1)-dimensional Abelian Higgs model with Lorentz symmetry breaking. In this set up the sound waves lose the Lorentz boost invariance and suffer a 'birefringence' effect. We have found acoustic black holes and respective Hawking temperatures depending on the Lorentz violating parameter. Furthermore, we obtain an acoustic Kerr-like black hole metric with the Lorentz violating term affecting its rate of loss of mass. We also have shown that for suitable values of the Lorentz violating parameter a wider spectrum of particle wave function can be scattered with increased amplitude by the acoustic black hole.Comment: 12 pages, Latex, no figures, version accepted to Phys. Lett.

Characteristics of nodule bacteria from Mimosa spp grown in soils of the Brazilian semiarid region.

The Brazilian Northeastern dry forest (Caatinga) is one of the diversification centers of Mimosa species. We determined the characteristics of native rhizobia isolates from nodules of Mimosa tenuiflora and Mimosa paraibana grown in pots with soils collected under Caatinga vegetation and compared the restriction ribosomal DNA profiles of the isolates with those of 16 reference strains. All plants formed abundant indeterminate nodules and all nodule isolates formed fast growing colonies. No colony altered the medium to an alkaline reaction and most of them produced low or medium amounts of extracellular polysaccharides. White and creamy colonies predominated among the isolates but orange and green colonies were present. Differences among the isolates from the Mimosa species tested are indicated by the greater phenotypic diversity of those obtained from M. tenuiflora. The analysis of the 16S rDNA gene suggests that the isolates from M. tenuiflora and M. paraibana are closely related and closer to B-rhizobia than to α-rhizobia. However, the similarity with all the tested B-rhizobia reference strains was relatively low suggesting that the isolates may belong to different bacteria species

On Aharonov-Casher bound states

In this work bound states for the Aharonov-Casher problem are considered. According to Hagen's work on the exact equivalence between spin-1/2 Aharonov-Bohm and Aharonov-Casher effects, is known that the $\boldsymbol{\nabla}\cdot\mathbf{E}$ term cannot be neglected in the Hamiltonian if the spin of particle is considered. This term leads to the existence of a singular potential at the origin. By modeling the problem by boundary conditions at the origin which arises by the self-adjoint extension of the Hamiltonian, we derive for the first time an expression for the bound state energy of the Aharonov-Casher problem. As an application, we consider the Aharonov-Casher plus a two-dimensional harmonic oscillator. We derive the expression for the harmonic oscillator energies and compare it with the expression obtained in the case without singularity. At the end, an approach for determination of the self-adjoint extension parameter is given. In our approach, the parameter is obtained essentially in terms of physics of the problem.Comment: 11 pages, matches published versio

Desenvolvimento inicial de pomeleiro Flame sobre diferentes porta-enxertos e espaçamento adensado no Semiárido do Ceará.

O trabalho teve como objetivo avaliar o desenvolvimento vegetativo inicial de pomeleiros "Flame" sobre diferentes porta-enxertos cítricos em condições de Semiárido Cearense

Superresonance effect from a rotating acoustic black hole and Lorentz symmetry breaking

We investigate the possibility of the acoustic superresonance phenomenon (analog to the superradiance in black hole physics), i.e., the amplification of a sound wave by reflection from the ergoregion of a rotating acoustic black hole with Lorentz symmetry breaking. For rotating black holes the effect of superradiance corresponds to the situation where the incident waves has reflection coefficient greater than one, and energy is extracted from them. For an acoustic Kerr-like black hole its rate of loss of mass is affected by the Lorentz symmetry breaking. We also have shown that for suitable values of the Lorentz violating parameter a wider spectrum of particle wave function can be scattered with increased amplitude by the acoustic black hole.Comment: 9 pages, version to appear in PL

Atividade física na reabilitação de idosos com sarcopenia: uma revisão de literatura

Introdução: O envelhecimento populacional impõe desafios às políticas sociais, sobretudo na saúde, entre elas à sarcopenia, caracterizada pela perda de massa muscular e força. A prática regular de exercícios físicos é crucial para prevenir e mitigar esses efeitos, promovendo funcionalidade e independência. Objetivo: Analisar a eficácia da atividade física na reabilitação de idosos com sarcopenia. Metodologia: Revisão de literatura que utilizou a base de dados Pubmed, artigos publicados entre 2019-2023 e descritores: "Exercise", "Sarcopenia", "Rehabilitation" e "Aged", aplicando o operador booleano "AND". Os critérios de inclusão contemplaram artigos completos e gratuitos publicados nos últimos 5 anos. Foram excluídos artigos que abordavam outras doenças além de sarcopenia e obesidade sarcopênica, bem como nutrição/suplementação. Desenvolvimento: A fisiopatologia da sarcopenia está relacionada à desregulação hormonal, inflamação crônica, alterações na composição das fibras musculares, entre outros fatores como a resistência insulínica do idoso, sendo que esses processos contribuem para a degradação da qualidade e força muscular. Com relação ao tratamento e controle da doença, a atividade física aparece como forma mais eficaz de propedêutica, sendo que a realização de treinos resistidos por idosos tem a capacidade de melhorar exponencialmente a musculatura. Conclusão: A importância do exercício na abordagem da sarcopenia destaca-se, impactando positivamente a qualidade de vida e prevenindo a deterioração que aumenta o risco de mortalidade. Observa-se, por fim, a necessidade de estratégias de promoção da saúde para essa população vulnerável