Localization of Energy and Momentum in an Asymptotically Reissner-Nordstr\"om Non-singular Black Hole Space-time Geometry

The space-time geometry exterior to a new four-dimensional, spherically symmetric and charged black hole solution that, through a coupling of general relativity with a non-linear electrodynamics, is everywhere non-singular, for small $r$ it behaves as a de Sitter metric, and asymptotically it behaves as the Reissner-Nordstr\"{o}m metric, is considered in order to study the energy-momentum localization. For the calculation of the energy and momentum distributions, the Einstein, Landau-Lifshitz, Weinberg and M\o ller energy-momentum complexes have been applied. The results obtained show that in all prescriptions the energy depends on the mass $M$ of the black hole, the charge $q$, two parameters $$ and $\gamma\in \mathbb{R}^+$, and on the radial coordinate $r$. The calculations performed in each prescription show that all the momenta vanish. Additionally, some limiting and particular cases for $r$ and $q$ are studied, and a possible connection with strong gravitational lensing and micro lensing is attempted.Comment: To appear in Univers

Controllability of the heat equation with an inverse-square potential localized on the boundary

This article is devoted to analyze control properties for the heat equation with singular potential $-\mu/|x|^2$ arising at the boundary of a smooth domain \Omega\subset \rr^N, $N\geq 1$. This problem was firstly studied by Vancostenoble and Zuazua [20] and then generalized by Ervedoza [10]in the context of interior singularity. Roughly speaking, these results showed that for any value of parameters $\mu\leq \mu(N):=(N-2)^2/4$, the corresponding parabolic system can be controlled to zero with the control distributed in any open subset of the domain. The critical value $\mu(N)$ stands for the best constant in the Hardy inequality with interior singularity. When considering the case of boundary singularity a better critical Hardy constant is obtained, namely $\mu_{N}:=N^2/4$. In this article we extend the previous results in [18],[8], to the case of boundary singularity. More precisely, we show that for any $\mu \leq \mu_N$, we can lead the system to zero state using a distributed control in any open subset. We emphasize that our results cannot be obtained straightforwardly from the previous works [20], [10].Comment: 32 page

On the energy of a non-singular black hole solution satisfying the weak energy condition

The energy-momentum localization for a new four-dimensional and spherically symmetric, charged black hole solution that through a coupling of general relativity with non-linear electrodynamics is everywhere non-singular while it satisfies the weak energy condition is investigated. The Einstein and M\{o} ller energy-momentum complexes have been employed in order to calculate the energy distribution and the momenta for the aforesaid solution. It is found that the energy distribution depends explicitly on the mass and the charge of the black hole, on two parameters arising from the space-time geometry considered, and on the radial coordinate. Further, in both prescriptions all the momenta vanish.In addition, a comparison of the results obtained by the two energy-momentum complexes is made, whereby some limiting and particular cases are pointed out.Comment: 20 pages, 9 figure

The role of tension-compression asymmetry of the plastic flow on ductility and damage accumulation of porous polycrystals

The influence of the tension-compression asymmetry of the plastic flow, due to intrinsic single-crystal deformation mechanisms, on porosity evolution and the overall ductility of voided metallic polycrystals is assessed. To this end, detailed micromechanical finite-element analyses of three-dimensional unit cells containing a single initially spherical cavity are carried out. The plastic flow of the matrix (fully-dense material) is described by a criterion that accounts for strength-differential effects induced by deformation twinning of the constituent grains of the metallic polycrystalline materials. The dilatational response of porous polycrystals are calculated for macroscopic axisymmetric tensile loadings corresponding to a fixed value of the stress triaxiality and the two possible values of the Lode parameter. It is shown that damage accumulation, and ultimately ductility of the porous polycrystals are markedly different as compared to the case when the matrix is governed by von Mises criterion. Most importantly, a direct correlation is established between the macroscopic material parameter k that is intimately related to the particularities of the plastic flow of the matrix and the rate of damage accumulation. (C) 2017 Portuguese Society of Materials (SPM). Published by Elsevier Espana, S.L.U.. All rights reserved.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) via the project PTDC/EMETEC/1805/2012.This work has been supported by FCT (Fundacao para a Ciencia e Tecnologia) in the scope of the project UID/EEA/04436/2013.info:eu-repo/semantics/publishedVersio

Antibiotic therapy in the treatment of acute otitis media

Department of Otorhinolaryngology, District Hospital of Orhei, the Republic of Moldova, Department of Pharmacology, Dunarea de Jos University of Galati, RomaniaBackground: Acute otitis media is an infection of abrupt onset that usually presents with ear pain. Worldwide acute otitis media affects about 8-11% of people a year. In acute otitis media, antibiotics may speed recovery but may result in side effects. Antibiotics are often recommended in those with severe disease or under two years old. Material and methods: Our study included a retrospective analysis of 117 patients with acute otitis media, whose medical records were examined. The information was analyzed statistically. Results: The results demonstrated an increased involvement of older people and women. The use of antibiotics to treat acute otitis media is determined by Cefazolin in 49-50% cases, Ceftriaxone - 49%, Cefotaxime – 48%, Cefoperazone – 14%, Amoxicillini Clavulanic acid in 16% of cases. Antibiogram was released for 53 patients, and according to it: Cefazolin – 23%, Amoxicilini Clavulanic acid – 15% and the rest were treated with cephalosporin third generation. Conclusions: Depending on severity, the treatment requires the use of antibiotics with broad spectrum. Antibacterial therapy according to antibiogram is contemporary and has the advantage of assessing the appropriate antibiotic

Tratamentul unor sindroame algice de origine neurologică prin metoda de electrostimulare transcraniană (ESTC)

Catedra Anesteziologie şi Reanimatologie Nr.2 USMF “N.Testemițanu”, Congresul II Internaţional al Societăţii Anesteziologie Reanimatologie din Republica Moldova 27-30 august 2009Electrostimularea transcraniană cu aplicarea fronto-occipitală a electrozilor şi utilizarea pachetelor de curenţi impulsiformi cu frecvenţa 77,5 Hz şi valoarea sumară a curentului 4,5 ma, s-a dovedit a fi eficientă în tratamentul bolnavilor suferinzi de migrenă şi nevralgia nervului trigemin după 6-10 proceduri, contribuind şi la ameliorarea parametrilor hemodinamicii intracerebrale şi centrale. Studii aprofundate a savanţilor din ultimile decenii au demonstrat eficacitatea experimentală şi clinică a electrostimulării transcraniene cu curenţi impulsiformi rectangulari, având parametri cu valori critice. Metoda constă în influenţa transcutană, transcraniană a curentului electric impulsiform, care stimulează sistemul antinociceptiv cu actizarea structurilor endorfinice, serotoninergice ale creerului cu dezvoltarea efectelor analgezice, antistresorii, imunomodulatorii etc. Scopul acestui studiu a fost de a evalua eficacitatea metodei ESTC în tratamentul pacienţilor cu migrenă şi nevralgia nervului trigemin, care cu greu se supun tratamentului tradiţonal medicamentos. Cu ajutorul ESTC noi am tratat 25 pacienţi, inclusiv 20 femei şi 5 bărbaţi cu vârsta medie 43±6 ani, cu sindrom algic localizat central şi periferic, având durata medie 9±4 ani, care s-au tratat cu diverse remedii medicamentoase, dar fără rezultate importante. Bolnavi cu migrenă au fost 18, iar cu nevralgia nervului trigemin 7. Pentru ESTC am folosit aparatul DES produs de Î.S.CESID. Pacienţii au primit câte o cură de tratament care includea 7-10 şedinţe cu durata de 30-40 min. fiecare. În cadrul studiului s-a cercetat reoencefalografia, parametrii hemodinamicii şi evoluţia clinică. S-a constatat micşorarea esenţială sau chiar dispariţia durerii din prima şedinţă ESTC. Analgezia apare peste 15-17 min. de la iniţierea procedurii şi durează timp de 3-24 ore. Cu fiecare şedinţă durata efectului analgezic creşte şi ajunge la maximum după 4-5 şedinţe. Trebuie de menţionat că la bolnavii cu migrenă eficacitatea tratamentului se observă de la primele proceduri în proporţie de 85% iar remisia durează 3-7 luni după o cură de tratament. La bolnavii cu nevragia trigeminului efectul apare din prima procedură, iar după 4-6 proceduri durerile dispar definitiv. Hemodinamica intracerebrală şi centrală sa caracterizat prin ameliorare esenţială şi stabilizare. Astfel metoda ESTC s-a dovedit a fi eficientă în tratamentul migrenei şi nevralgiei nervului trigemin în cadrul monoterapiei. Este necesară continuarea aprofundată a studiului

Uptake and metabolism of sulphated steroids by the blood-brain barrier in the adult male rat

Little is known about the origin of the neuroactive steroids dehydroepiandrosterone sulphate (DHEAS) and pregnenolone sulphate (PregS) in the brain or of their subsequent metabolism. Using rat brain perfusion in situ, we have found (3) H-PregS to enter more rapidly than (3) H-DHEAS and both to undergo extensive (>50%) desulphation within 0.5 min of uptake. Enzyme activity for the steroid sulphatase catalysing this deconjugation was enriched in the capillary fraction of the blood-brain barrier and its mRNA expressed in cultures of rat brain endothelial cells and astrocytes. Although permeability measurements suggested a net efflux, addition of the efflux inhibitors GF120918 and/or MK571 to the perfusate reduced rather than enhanced the uptake of (3) H-DHEAS and (3) H-PregS; a further reduction was seen upon the addition of unlabelled steroid sulphate, suggesting a saturable uptake transporter. Analysis of brain fractions after 0.5 min perfusion with the (3) H-steroid sulphates showed no further metabolism of PregS beyond the liberation of free steroid pregnenolone. By contrast, DHEAS underwent 17-hydroxylation to form androstenediol in both the steroid sulphate and the free steroid fractions, with some additional formation of androstenedione in the latter. Our results indicate a gain of free steroid from circulating steroid sulphates as hormone precursors at the blood-brain barrier, with implications for ageing, neurogenesis, neuronal survival, learning and memory. This article is protected by copyright. All rights reserved