318 research outputs found

    Null geodesics in five-dimensional Reissner-Nordstr\"om anti-de Sitter black hole

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    The study of the motion of photons around massive bodies is one of the most useful tools to know the geodesic structure associated with said gravitational source. In the present work, different possible paths projected in an invariant hyperplane are investigated, considering five-dimensional Reissner-Nordstr\"om anti-de Sitter black hole. Also, we study some observational test such as the bending of light and the Shapiro time delay effect. Mainly, we found that the motion of photons follows the hippopede of Proclus geodesic, which is a new type of trajectory of second kind, being the Lima\c{c}on of Pascal their analogue geodesic in four-dimensional Reissner-Nordstr\"om anti-de Sitter black hole.Comment: Version accepted for publication by EPJ

    Two-Dimensional Time-Domain Antenna Arrays for Optimum Steerable Energy Pattern with Low Side Lobes

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    This document presents the synthesis of different two-dimensional time-domain antenna arrays for steerable energy patterns with side lobe levels. The research is focused on the uniform and nonuniform distributions of true-time exciting delays and positions of antenna elements. The uniform square array, random array, uniform concentric ring array, and rotated nonuniform concentric ring array geometries are particularly studied. These geometries are synthesized by using the well-known sequential quadratic programming. The synthesis regards the optimal true-time exciting delays and optimal positions of pulsed antenna elements. The results show the capabilities of the different antenna arrays to steer the beam in their energy pattern in time domain and how their performance is in frequency domain after the synthesis in time domain

    Static circularly symmetric perfect fluid solutions with an exterior BTZ metric

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    In this work we study static perfect fluid stars in 2+1 dimensions with an exterior BTZ spacetime. We found the general expression for the metric coefficients as a function of the density and pressure of the fluid. We found the conditions to have regularity at the origin throughout the analysis of a set of linearly independent invariants. We also obtain an exact solution of the Einstein equations, with the corresponding equation of state p=p(ρ)p=p(\rho), which is regular at the origin.Comment: 10 pages, 1 figure, revtex 4. This paper is in honor of Alberto Garcia's sixtieth birthday. Accepted by Gen. Rel. Gra

    Circular Unit Cell Gratings for X-ray Dark-Field Imaging

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    Dark-field imaging has been demonstrated to provide complementary information about the unresolved microstructure of the investigated sample. The usual implementation of a grating interferometer, which can provide access to the dark-field signal, consists of linear gratings limiting the sensitivity to only one direction (perpendicular to the grating lines). Recently, a novel grating design, composed of circular unit cells, was proposed allowing 2D-omnidirectional dark-field sensitivity in a single shot. In this work we present a further optimisation of the proposed grating by changing the arrangement of the unit cells from a Cartesian to a hexagonal grid. We experimentally compare the two designs and demonstrate that the latter has an improved performance

    The geodesic structure of the Schwarzschild Anti-de Sitter black hole

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    In the present work we found the geodesic structure of an AdS black hole. By means of a detailed analyze of the corresponding effective potentials for particles and photon, we found all the possible motions which are allowed by the energy levels. Radial and non radial trajectories were exactly evaluated for both geodesics. The founded orbits were plotted in order to have a direct visualization of the allowed motions. We show that the geodesic structure of this black hole presents new type of motions not allowed by the Schwarzschild spacetime.Comment: 17 pages, 11 figure

    Building a network of TP53 and IGHV testing reference centers across Spain: the Red53 initiative

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    © The Author(s) 2021.Among the different biomarkers predicting response in chronic lymphocytic leukemia (CLL), the most influential parameters are the mutational status of the IGHV genes and the presence of TP53 gene disruptions. Nevertheless, these important assessments are not readily available in most centers dealing with CLL patients. To provide this molecular testing across the country, the Spanish Cooperative Group on CLL (GELLC) established a network of four analytical reference centers. A total of 2153 samples from 256 centers were analyzed over a period of 30 months. In 9% of the patients, we found pathological mutations in the TP53 gene, whereas 48.96% were classified as IGHV unmutated. Results of the satisfaction survey of the program showed a Net Promoter Score of 85.15. Building a national network for molecular testing in CLL allowed the CLL population a broad access to complex biomarkers analysis that should translate into a more accurate and informed therapeutic decision-making.This work was supported in part by Janssen Pharmaceutical Companies of Johnson & Johnson. MC holds a contract from Ministerio de Ciencia, Innovación y Universidades (RYC-2012-12018)

    The Antioxidant Capacity of Rosemary and Green Tea Extracts to Replace the Carcinogenic Antioxidant (BHA) in Chicken Burgers

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    The present study aimed to evaluate the effect of natural extracts (rosemary and green tea extracts) in frozen storage of chicken burgers. Chicken burger treatments were prepared as follows: control (CON), 20 mg BHA/kg (BHA20), 10 mg green tea extract/kg (GT10), 38 mg green tea extract/kg (GT38), 18.6 mg rosemary extract/kg (RO18), and 480 mg rosemary extract/kg (RO480). Analysis of physicochemical parameters, color, TBAR index, and sensory acceptance were performed at 0, 30, 60, and 120 days of storage at −18°C in burgers packaged in LDPE plastic bags. The addition of natural antioxidants did not affect (p>0.05) the color and physicochemical parameters of the chicken burgers. After 120 days at −18°C, the RO480 sample showed a TBAR index similar (p>0.05) to BHA20 (0.423 and 0.369 mg, resp.). Sensory acceptance did not differ (p>0.05) among the treatments throughout the storage period (p>0.05)

    What’s in the Pool? A Comprehensive Identification of Disinfection By-products and Assessment of Mutagenicity of Chlorinated and Brominated Swimming Pool Water

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    38 páginas, 2 figuras, 4 tablas.-- PDF con material suplementario.[BACKGROUND]: Swimming pool disinfectants and disinfection by-products (DBPs) have been linked to human health effects, including asthma and bladder cancer, but no studies have provided a comprehensive identification of DBPs in the water and related that to mutagenicity.[OBJECTIVES]: We performed a comprehensive identification of DBPs and disinfectant species in waters from public swimming pools in Barcelona, Catalonia, Spain, that disinfect with either chlorine or bromine, and we determined the mutagenicity of the waters to compare to the analytical results.[METHODS]: We used gas chromatography (GC)/mass spectrometry (MS) to measure THMs in water and GC with electron capture detection (ECD) for air, low and high resolution GC/MS to comprehensively identify DBPs, photometry to measure disinfectant species (free chlorine, monochloroamine, dichloramine, and trichloramine) in the waters, and an ion chromatography method to measure trichloramine in air. We assessed mutagenicity in the Salmonella mutagenicity assay.[RESULTS]: We identified more than 100 DBPs, including many nitrogen-containing DBPs that were likely formed from nitrogen-containing precursors from human inputs, such as urine, sweat, and skin cells. Many DBPs were new and have not been reported previously in either swimming pool or drinking waters. Bromoform levels were greater in the brominated vs. chlorinated pool waters, but many brominated DBPs were also identified in the chlorinated waters. The pool waters were mutagenic at levels similar to that of drinking water (~1200 revertants/L-eq in strain TA100 –S9 mix).[CONCLUSIONS]: This study identified many new DBPs not identified previously in swimming pool or drinking water and found that swimming pool waters are as mutagenic as typical drinking waters.This research was supported by EPA’s intramural research program and the Spanish grants SAF2005-07643-C03-01 (Plan Nacional) and CP06/00341 (Fondo de Investigación Sanitaria). CMV and LFR have, respectively, a contract and a predoctoral fellowship by the Instituto de Salud Carlos III (CP06/00341, FI06/00651). CL acknowledges a grant from the Agreement between Santander-Central Hispano and CSIC.Peer reviewe
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