Towards a novel wave-extraction method for numerical relativity

We present the recent results of a research project aimed at constructing a robust wave extraction technique for numerical relativity. Our procedure makes use of Weyl scalars to achieve wave extraction. It is well known that, with a correct choice of null tetrad, Weyl scalars are directly associated to physical properties of the space-time under analysis in some well understood way. In particular it is possible to associate $\Psi_4$ with the outgoing gravitational radiation degrees of freedom, thus making it a promising tool for numerical wave--extraction. The right choice of the tetrad is, however, the problem to be addressed. We have made progress towards identifying a general procedure for choosing this tetrad, by looking at transverse tetrads where $\Psi_1=\Psi_3=0$. As a direct application of these concepts, we present a numerical study of the evolution of a non-linearly disturbed black hole described by the Bondi--Sachs metric. This particular scenario allows us to compare the results coming from Weyl scalars with the results coming from the news function which, in this particular case, is directly associated with the radiative degrees of freedom. We show that, if we did not take particular care in choosing the right tetrad, we would end up with incorrect results.Comment: 6 pages, 1 figure, to appear in the Proceedings of the Albert Einstein Century International Conference, Paris, France, 200

Regression of Environmental Noise in LIGO Data

We address the problem of noise regression in the output of gravitational-wave (GW) interferometers, using data from the physical environmental monitors (PEM). The objective of the regression analysis is to predict environmental noise in the gravitational-wave channel from the PEM measurements. One of the most promising regression method is based on the construction of Wiener-Kolmogorov filters. Using this method, the seismic noise cancellation from the LIGO GW channel has already been performed. In the presented approach the Wiener-Kolmogorov method has been extended, incorporating banks of Wiener filters in the time-frequency domain, multi-channel analysis and regulation schemes, which greatly enhance the versatility of the regression analysis. Also we presents the first results on regression of the bi-coherent noise in the LIGO data

Transverse frames for Petrov type I spacetimes: a general algebraic procedure

We develop an algebraic procedure to rotate a general Newman-Penrose tetrad in a Petrov type I spacetime into a frame with Weyl scalars $\Psi_{1}$ and $\Psi_{3}$ equal to zero, assuming that initially all the Weyl scalars are non vanishing. The new frame highlights the physical properties of the spacetime. In particular, in a Petrov Type I spacetime, setting $\Psi_{1}$ and $\Psi_{3}$ to zero makes apparent the superposition of a Coulomb-type effect $\Psi_{2}$ with transverse degrees of freedom $\Psi_{0}$ and $\Psi_{4}$.Comment: 10 pages, submitted to Classical Quantum Gravit

Higher order corrections to lensing parameters for extended gravitational lenses

We discuss the contribution to the characteristic lensing quantities, i.e. the deflection angle and Einstein radius, due to the higher order terms (e.g. the gravitomagnetic terms) considered in the lens potential. The cases we analyze are the singular isothermal sphere and the disk of spiral galaxies. It is possible to see that the perturbative effects could be of the order 10^{-3} with respect to the ordinary terms of weak field and thin lens approximations, so that it is not a far hypothesis to obtain evidences of them in a next future by suitable experiments.Comment: 7 pages, LaTex file, to appear on Phys. Lett.

Towards a wave-extraction method for numerical relativity: IV. Testing the quasi-Kinnersley method in the Bondi-Sachs framework

We present a numerical study of the evolution of a non-linearly disturbed black hole described by the Bondi--Sachs metric, for which the outgoing gravitational waves can readily be found using the news function. We compare the gravitational wave output obtained with the use of the news function in the Bondi--Sachs framework, with that obtained from the Weyl scalars, where the latter are evaluated in a quasi-Kinnersley tetrad. The latter method has the advantage of being applicable to any formulation of Einstein's equations---including the ADM formulation and its various descendants---in addition to being robust. Using the non-linearly disturbed Bondi--Sachs black hole as a test-bed, we show that the two approaches give wave-extraction results which are in very good agreement. When wave extraction through the Weyl scalars is done in a non quasi-Kinnersley tetrad, the results are markedly different from those obtained using the news function.Comment: 12 pages, 11 figure

Ex vivo antibacterial activity of levofloxacin against Escherichia coli and its pharmacokinetic profile following intravenous and oral administrations in broilers

The use of antibiotics is common for prevention and treatment of diseases. However, determination of optimal dosage in the target animal is necessary for success of a treatment. This study aimed to evaluate the pharmacokinetics/pharmacodynamics (PK/PD) of levofloxacin, a third generation fluoroquinolone, in broilers. Parallel study design was used and each group of animals (n=20) received levofloxacin intravenously (IV) and orally (PO) at a dose of 5 mg/kg. Plasma and serum and tissues were collected for PK and PD studies. Plasma concentrations of levofloxacin were determined by HPLC with fluorescence detector. As a PD study, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined against E. coli which was isolated in clinical broilers. Ex vivo antibacterial activity of levofloxacin against E. coli was evaluated using the time killing method. Mean values of terminal half-life for IV and PO groups were 6.93 and 8.09 h, respectively. Following oral administration, the peak plasma concentration was achieved at 0.88 h (Tmax). Mean value of oral bioavailability was 123.25%. Levofloxacin residues were found in all the tissues tested (muscle, liver, kidney and lung). The highest concentration was found in the liver. Plasma concentration above 8 x MIC lead to eradication of E. coli over an incubation period of 24h. The results of ex vivo growth inhibition curves were consistent with the in vitro time-kill study. Levofloxacin showed plasma concentration dependent antibacterial activity against a clinical isolate of E. coli. According to the assessment of PK/PD relationship, administration of levofloxacin at a dose of 5 mg/kg seems to be effective in killing E. coli. Also, simulated optimal dose based on the ex vivo PK/PD approach was up 2.9 mg/kg/day (bactericidal) to 4.3 mg/kg/day (eradication) PO against E. coli (MIC = 0.125 µg/ml)

The combination of crop diversification and no tillage enhances key soil quality parameters related to soil functioning without compromising crop yields in a low-input rainfed almond orchard under semiarid Mediterranean conditions

Soils provide key ecosystem services and are crucial to combat climate change. Agriculture provides important ecosystem services but also causes negative environmental effects depending on agricultural management. In this regard, crop diversification is a promising sustainable land management strategy to combat soil erosion and degradation, mitigate climate change and ensure food security. Here, we assess the combined short-term effects of crop diversification and no tillage on several key soil physico-chemical parameters related to soil functioning as well as on crop yields in a rainfed almond (Prunus dulcis Mill.) orchard under semiarid Mediterranean conditions. Almond trees were inter-cropped with Capparis spinosa L. (caper) or Thymus hyemalis Lange (winter thyme) and compared with the almond monocrop system. The experimental design consisted of three plots in a randomized-block design, with three replicates for each crop management treatment (almond monocrop, almond inter-cropped with caper, and almond inter-cropped with winter thyme). Along with crop yields, the combined effects of crop diversification and no tillage on a range of soil quality and health indicators including soil physical (bulk density, aggregate stability, water retention and availability) and chemical (total and particulate organic carbon and nitrogen, ammonium and nitrate content, available macro- and micro-nutrients) properties were monitored in the topsoil and subsoil (at 0–10 and 10–30 cm depth, respectively) one and three years from establishment.EEA Delta del ParanáFil: Almagro, María. Consejo Superior de Investigaciones Científicas (CSIC). Centro de Edafología y Biología Aplicada del Segura; EspañaFil: Díaz-Pereira, Elvira. Consejo Superior de Investigaciones Científicas (CSIC). Centro de Edafología y Biología Aplicada del Segura; EspañaFil: Boix-Fayos, Carolina. Consejo Superior de Investigaciones Científicas (CSIC). Centro de Edafología y Biología Aplicada del Segura; EspañaFil: Zornoza, Raúl. Universidad Politécnica de Cartagena. Departamento de Ingeniería Agronómica; EspañaFil: Sánchez-Navarro, Virginia. Universidad Politécnica de Cartagena. Departamento de Ingeniería Agronómica; EspañaFil: Re, Paula. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Re, Paula. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Fernández, Cristina. Consejo Superior de Investigaciones Científicas (CSIC). Centro de Edafología y Biología Aplicada del Segura; EspañaFil: Martínez-Mena, María. Consejo Superior de Investigaciones Científicas (CSIC). Centro de Edafología y Biología Aplicada del Segura; Españ

Identifying territory-building processes in the peri-urban area of the cluster of Villa María – Villa Nueva, Córdoba, Argentina

Los procesos que configuran el espacio periurbano en lasciudades son importantes ya que de ellos se pueden conocer lasvariables performativas de la realidad. En la actualidad, la implementación de políticas de ordenamiento territorial basadas en elconocimiento científico y que contemplen una construcción participativa constituyen una asignatura pendiente. El presente trabajo buscó identificar los múltiples procesos territoriales que dieronlugar a la conformación espacial del periurbano del conglomeradoVilla María-Villa Nueva, Córdoba. A tales fines se apeló al desarrollo de metodologías cuantitativas referidas a las espacialidades locales, y cualitativas como la historización, el relevamiento normativo y el desarrollo de entrevistas y talleres en los que predominóel carácter participativo de dichas actividades. Los resultados obtenidos posibilitaron vislumbrardiferencias significativas respecto de la distribución de las actividades, el uso del suelo y su regulación. Lo anterior evidencia que el rol de los actores expresa pautas de apropiación socioterritoriales y de conformación de espacialidades disímiles.Fil: Guzmán, Leticia Ana. Universidad Nacional de Villa María. Instituto Académico Pedagógico de Ciencias Básicas y Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mizdraje, Dafne Aylén. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto Multidisciplinario de Investigacion y Transferencia Agroalimentaria y Biotecnologica. - Universidad Nacional de Villa Maria. Instituto Multidisciplinario de Investigacion y Transferencia Agroalimentaria y Biotecnologica.; ArgentinaFil: Re, Virginia Liz. Universidad Nacional de Villa María. Instituto Académico Pedagógico de Ciencias Básicas y Aplicadas; ArgentinaFil: Pierotti, Luciana. Universidad Nacional de Villa María; ArgentinaFil: Álvarez, Marcelo. Universidad Nacional de Villa María. Instituto Académico Pedagógico de Ciencias Sociales; Argentin

Competencias de adaptabilidad y expectativas del alumnado en proceso de transición a la educación superior: un estudio transnacional en España, Uruguay e Italia

El problema que está en la base de esta investigación es que muchos estudiantes llegan a la educación superior sin una idea clara acerca del por qué y para qué de los estudios que han elegido y sin expectativas académico/profesionales claras y realistas, lo que alimenta el riesgo del fracaso en los estudios. Los estudiantes que acceden a la universidad con malos resultados académicos previos, con escasa información sobre la enseñanza universitaria y el modelo formativo, con bajo dominio de las competencias genéricas, sin expectativas claras y sin un proyecto personal definido, tienen muchas posibilidades de que su adaptación a la educación superior sea compleja y de que se vean implicados en situaciones de fracaso y abandono de los estudios. Esto ha hecho que uno de los problemas que más preocupe en la actualidad a la institución universitaria sea los altos índices de fracaso y abandono escolar, lo que ha venido a destacar la necesidad de analizar qué variables intervienen y provocan estas situaciones, de modo que una vez identificadas y conocido su efecto, se pueda poner en práctica programas de orientación y tutoría desde las etapas previas, que tengan un carácter preventivo y continuo, a través de los cuales se dé una respuesta efectiva a las necesidades de estos estudiantes, para que puedan integrarse de forma satisfactoria a la universidad. En relación a esta problemática, se ha emprendido un estudio transnacional en tres países (España, Uruguay e Italia) con la finalidad de profundizar en las competencias y expectativas académicas y profesionales que tienen los estudiantes de secundaria respecto a la educación superior. Los resultados confirman que el desarrollo de competencias transversales, el rendimiento académico previo y la definición del proyecto académico y profesional, son factores determinantes en los procesos de transición y adaptación a la universidad

Gravitational waves: search results, data analysis and parameter estimation

The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity