Gravitational Waves from Coalescing Binary Sources

Coalescing binary systems (eg pulsars, neutron stars and black holes) are the most likely sources of gravitational radiation, yet to be detected on or near Earth, where the local gravitational field is negligible and the Poincar\'e symmetry rules. On the other hand, the general theory of gravitational waves emitted by axially symmetric rotating sources predicts the existence of a non-vanishing news function. The existence of such function implies that, for a distant observer, the asymptotic group of isometries, the BMS group, has a translational symmetry that depends on the orbit periodicity of the source, thus breaking the isotropy o the Poincar\'e translations. These results suggest the application of the asymptotic BMS-covariant wave equation to obtain a proper theoretical basis for the gravitational waves observations.Comment: 4 pages, awarded a honorable mention from the Gravity Research Foundation 201

Axial dependence of optical weak measurements in the critical region

The interference between optical beams of different polarizations plays a fundamental role in reproducing the optical analog of the electron spin weak measurement. The extraordinary point in optical weak measurements is represented by the possibility to estimate with great accuracy the Goos-Haenchen (GH) shift by measuring the distance between the peak of the outgoing beams for two opposite rotation angles of the polarizers located before and after the dielectric block. Starting from the numerical calculation of the GH shift, which clearly shows a frequency crossover for incidence near to the critical angle, we present a detailed study of the interference between s and p polarized waves in the critical region. This allows to determine in which conditions it is possible to avoid axial deformations and reproduce the GH curves. In view of a possible experimental implementation, we give the expected weak measurement curves for Gaussian lasers of different beam waist sizes propagating through borosilicate (BK7) and fused silica dielectric blocks.Comment: 16 pages, 7 figure

An alternative theoretical approach to describe planetary systems through a Schrodinger-type diffusion equation

In the present work we show that planetary mean distances can be calculated with the help of a Schrodinger-type diffusion equation. The obtained results are shown to agree with the observed orbits of all the planets and of the asteroid belt in the solar system, with only three empty states. Furthermore, the equation solutions predict a fundamental orbit at 0.05 AU from solar-type stars, a result confirmed by recent discoveries. In contrast to other similar approaches previously presented in the literature, we take into account the flatness of the solar system, by considering the flat solutions of the Schrodinger-type equation. The model has just one input parameter, given by the mean distance of Mercury.Comment: 6 pages. Version accepted for publication in Chaos, Solitons & Fractal

Nanobody mediated inhibition of attachment of F18 fimbriae expressing Escherichia coli

Post-weaning diarrhea and edema disease caused by F18 fimbriated E. coli are important diseases in newly weaned piglets and lead to severe production losses in farming industry. Protective treatments against these infections have thus far limited efficacy. In this study we generated nanobodies directed against the lectin domain of the F18 fimbrial adhesin FedF and showed in an in vitro adherence assay that four unique nanobodies inhibit the attachment of F18 fimbriated E. coli bacteria to piglet enterocytes. Crystallization of the FedF lectin domain with the most potent inhibitory nanobodies revealed their mechanism of action. These either competed with the binding of the blood group antigen receptor on the FedF surface or induced a conformational change in which the CDR3 region of the nanobody displaces the D ''-E loop adjacent to the binding site. This D ''-E loop was previously shown to be required for the interaction between F18 fimbriated bacteria and blood group antigen receptors in a membrane context. This work demonstrates the feasibility of inhibiting the attachment of fimbriated pathogens by employing nanobodies directed against the adhesin domain

A floresta tropical seca, caatinga: As certezas e incertezas das águas

The brazilian semi-arid is not characterized by a small rainfall depth, but by how uncertain the events are, the frequency of extreme events (droughts and floods), annual evaporation rate (1,500 mm – 3,000 mm) and crystaline base. The rainfall depth of 750 mm/year characterizes it as one of the rainiest semi-arids in the world. Due to the proximity to the equator, altitude and geology, its drainage is almost composed by ephemerous or intermitent rivers. The soil-climate interaction in the evolution process and adaptation to the natural conditions of the place resulted in the appearance of the Caatinga Biome, which has an area of 844000 km2, corresponding to 86% of the Brazillian semi-arid. The caatinga presents high biodiversity and endogenous species adapted to the climactic conditions of the tropical semi-arid. Of the more than 1700 vegetation species (trees and brush) catalogued to the present day, 19% of them are endogenous. The uncertainties of the hydrological regime, together with its geological base, are the reason for the formation of an intense network of artificial reservoirs (2,660 lakes with surface area > 20 ha) for supplying the water needed for multiple uses. This network of reservoirs is what contributed to make this region one of the dry regions with highest demographic density in the world, approximately 27 million inhabitants, which exerts a high pressure on the natural resources. Such a fact leads to the need for studies which focus on understanding the uncertainties of the hydrological processes in the tropical dry forest, the caatingaO semiárido brasileiro não se caracteriza por baixas alturas pluviométricas mas pelas incertezas dos eventos, frequente de eventos extremos (secas e cheias), taxa anual de evaporação da superfície líquida variando de 1500 mm a 3000 mm e uma base geológica cristalina. A precipitação de 750 mm ano-1, o que o caracteriza como um dos semiáridos mais chuvoso do planeta. Devido a sua proximidade ao equador, baixas altitudes e geologia, a sua rede de drenagem é composta em quase sua totalidade por rios efêmeros ou intermitentes. As interações solo-clima ocorridas no processo de evolução e adaptação às condições ambientais resultou no surgimento do Bioma Caatinga, o qual apresenta uma área de 844000 km2 correspondendo a 86% do semiárido brasileiro. A caatinga apresenta elevada biodiversidade e endogenia adaptadas às condições climáticas do semiárido tropical. Das de 1700 espécies vegetais (árvores e arbustos) forma catalogadas até os dias atuais, 19% são endógenas. As incertezas do regime hidrológico da região juntamente com a sua base geológica levaram a construção de uma intensa rede de reservatórios artificiais (2660 lagos artificiais com área superficial > 20 ha) para suprimento de água dos mais diferentes usos. Esta extensa rede de corpos hídricos, contribuiu para que a mesma se tornasse a região seca do globo de maior densidade demográfica, aproximadamente 27 milhões de habitantes, o que exerce uma elevada pressão sobre os recursos naturais.Tal fato conduz a necessidade de estudos voltados para o entendimento das incertezas dos processos hidrológicos na floresta tropical seca – caating