Re-Scaling of Energy in the Stringy Charged Black Hole Solutions using Approximate Symmetries

This paper is devoted to study the energy problem in general relativity using approximate Lie symmetry methods for differential equations. We evaluate second-order approximate symmetries of the geodesic equations for the stringy charged black hole solutions. It is concluded that energy must be re-scaled by some factor in the second-order approximation.Comment: 18 pages, accepted for publication in Canadian J. Physic

Phantom Energy Accretion by Stringy Charged Black Hole

We investigate the dynamical behavior of phantom energy near stringy magnetically charged black hole. For this purpose, we derive equations of motion for steady-state spherically symmetric flow of phantom energy onto the stringy magnetically charged black hole. It is found that phantom energy accreting onto black hole decreases its mass. Further, the location of critical points of accretion is explored, which yields mass to charge ratio. This ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity, hence cosmic censorship hypothesis remains valid here.Comment: 7 pages, no figur

The Energy of Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics

According to the Einstein, Weinberg, and M{\o}ller energy-momentum complexes, we evaluate the energy distribution of the singularity-free solution of the Einstein field equations coupled to a suitable nonlinear electrodynamics suggested by Ay\'{o}n-Beato and Garc\'{i}a. The results show that the energy associated with the definitions of Einstein and Weinberg are the same, but M{\o}ller not. Using the power series expansion, we find out that the first two terms in the expression are the same as the energy distributions of the Reissner-Nordstr\"{o}m solution, and the third term could be used to survey the factualness between numerous solutions of the Einstein field eqautions coupled to a nonlinear electrodynamics.Comment: 11 page

A Spot of Bother – Orthodontic Associated White Spot Lesions

White spot lesions (WSL) are a commonly reported risk of fixed appliance orthodontic treatment. This article reviews the incidence, aetiology and effectiveness of prevention and management of WSLs with a relevant case report. An adolescent male had fixed-appliance treatment and developed WSLs, despite prevention advice and careful monitoring, the WSLs progressed and ultimately led to the need for early removal of his orthodontic appliances. Removal of appliances prevented further damage and allowed partial resolution of the WSLs. CPD/Clinical Relevance: Careful monitoring of a patient's dental health during orthodontic treatment is essential; however, if oral health deteriorates, and demineralization occurs, rapid decisive action is necessary to limit irreversible damage

Gravitational Collapse: Expanding and Collapsing Regions

We investigate the expanding and collapsing regions by taking two well-known spherically symmetric spacetimes. For this purpose, the general formalism is developed by using Israel junction conditions for arbitrary spacetimes. This has been used to obtain the surface energy density and the tangential pressure. The minimal pressure provides the gateway to explore the expanding and collapsing regions. We take Minkowski and Kantowski-Sachs spacetimes and use the general formulation to investigate the expanding and collapsing regions of the shell.Comment: 12 pages, 4 figures, accepted for publication in Gen. Relativ. Gra

Energy Contents of Some Well-Known Solutions in Teleparallel Gravity

In the context of teleparallel equivalent to General Relativity, we study energy and its relevant quantities for some well-known black hole solutions. For this purpose, we use the Hamiltonian approach which gives reasonable and interesting results. We find that our results of energy exactly coincide with several prescriptions in General Relativity. This supports the claim that different energy-momentum prescriptions can give identical results for a given spacetime. We also evaluate energy-momentum flux of these solutions.Comment: 16 pages, accepted for publication in Astrophys. Space Sc

Energy and Momentum of a Class of Rotating Gravitational Waves

We calculate energy and momentum for a class of cylindrical rotating gravitational waves using Einstein and Papapetrou's prescriptions. It is shown that the results obtained are reduced to the special case of the cylindrical gravitational waves already available in the literature.Comment: 11 pages, no figure, Late

Classification of Spherically Symmetric Static Spacetimes according to their Matter Collineations

The spherically symmetric static spacetimes are classified according to their matter collineations. These are studied when the energy-momentum tensor is degenerate and also when it is non-degenerate. We have found a case where the energy-momentum tensor is degenerate but the group of matter collineations is finite. For the non-degenerate case, we obtain either {\it four}, {\it five}, {\it six} or {\it ten} independent matter collineations in which four are isometries and the rest are proper. We conclude that the matter collineations coincide with the Ricci collineations but the constraint equations are different which on solving can provide physically interesting cosmological solutions.Comment: 15 pages, no figure, Late

Energy Content of Colliding Plane Waves using Approximate Noether Symmetries

This paper is devoted to study the energy content of colliding plane waves using approximate Noether symmetries. For this purpose, we use approximate Lie symmetry method of Lagrangian for differential equations. We formulate the first-order perturbed Lagrangian for colliding plane electromagnetic and gravitational waves. It is shown that in both cases, there does not existComment: 18 pages, accepted for publication in Brazilian J Physic

The effect of oregano (Origanum vulgare) extract on prevention of S. ineae experimental infection in rainbow trout (Oncorhynchus mykiss)

This study was performed in order to determine the effect of Oregano (Origanum vulgare) extract on Streptococcus ineae infection in rainbow trout. 063 rainbow trout weighing 15±1 gr were randomly allocated into three treatment groups with three repetition, including: 1) Control group, 2) Oregano extract treated group (1% of diet), 3) Felorfenicol treated group (10mg/kg fish), all feed one time a day for two weeks. At the end of the second week, 5 fish of each repetition collected and sampled from their blood and tissue of spleen and kidney. After the bleeding, all the samples injected with streptococcus ineae. After two weeks mortality rate calculated and after the bleeding, sampled from the spleen and kidney of the samples. Total cunt analysis conducted on the spleen samples in 4 logarithmic concentrations. in the second phase all the samples primarily injected with S.ineae and then treated with Oregano concentration and Felorfenicol for two weeks. After the two steps of bleeding, in sterile qualifications, the spleen of the fishes sampled for total cunt analysis. Blood cells counting and lisosym activity indicated in all blood samples. The results shown that total mortality in both of the phases of experiment in Oregano extract (OE) treatment was significantly lower comparing to control group (p<0.05). Furthermore the results of blood cells counting shown that WBC and monocyts percents were significantly higher in Oe and Felorfenicol treatment groups (p<0.05). This phenomenon was because of the effects of Oe and Felorfenicol. Nevertheless the lysozym activity degreased comparing to control group (p<0.05). But total count analysis shown that bacterial audience in spleen degreased treating Oe and felorfenicol. It was concluded that supplementation of Oe registered lower mortality and bacterial audience, and better hematological parameters in fishes, compared with control group. Therefore supplementation of Oe in fish diet would be effective in prevention and treatment of S.iniae in rainbow trout