Accuracy Issues for Numerical Waveforms

We study the convergence properties of our implementation of the 'moving punctures' approach at very high resolutions for an equal-mass, non-spinning, black-hole binary. We find convergence of the Hamiltonian constraint on the horizons and the L2 norm of the Hamiltonian constraint in the bulk for sixth and eighth-order finite difference implementations. The momentum constraint is more sensitive, and its L2 norm shows clear convergence for a system with consistent sixth-order finite differencing, while the momentum and BSSN constraints on the horizons show convergence for both sixth and eighth-order systems. We analyze the gravitational waveform error from the late-inspiral, merger, and ringdown. We find that using several lower-order techniques for increasing the speed of numerical relativity simulations actually lead to apparently non-convergent errors. Even when using standard high-accuracy techniques, rather than seeing clean convergence, where the waveform phase is a monotonic function of grid resolution, we find that the phase tends to oscillate with resolution, possibly due to stochastic errors induced by grid refinement boundaries. Our results seem to indicate that one can obtain gravitational waveform phases to within 0.05 rad. (and possibly as small as 0.015 rad.), while the amplitude error can be reduced to 0.1%. We then compare with the waveforms obtained using the cZ4 formalism. We find that the cZ4 waveforms have larger truncation errors for a given resolution, but the Richardson extrapolation phase of the cZ4 and BSSN waveforms agree to within 0.01 rad., even during the ringdown.Comment: version accepted to PR

Local dynamics for fibered holomorphic transformations

Fibered holomorphic dynamics are skew-product transformations over an irrational rotation, whose fibers are holomorphic functions. In this paper we study such a dynamics on a neighborhood of an invariant curve. We obtain some results analogous to the results in the non fibered case

Comparación de fórmulas chilenas e internacionales para valorar el arbolado urbano

Ponce-Donoso, M (reprint author), Univ Talca, Fac Ciencias Forestales, Casilla 747, Talca, Chile.The appraisal of urban trees is a practice adopted in diverse cities of world. This survey compared international formulae: Council of Tree Landscape Appraiser (CTLA), Burnley, Helliwell and Standard Tree Evaluation Method (STEM) and three Chilean methods applied in municipalities of Concepcion, La Pintana, Maip (COPIMA), Nunoa and Penalolen, in 14 different trees located in Talca city (Chile). The objective was to identify the differences and similarities of the monetary result in the application of these formulae, which was realized by a professional. These were analyzed using a non parametric variance test of Kruskal - Wallis and the multiple comparisons Duncan test. It was possible to determine that the Chilean formulae did not present statistically significant differences with the international formulae of Burnley and CTLA; whereas Penalolen and COPIMA formulae did not present any difference when contrasted with Helliwell. In addition, the STEM formula presented differences with all the Chilean analyzed formulae. In the valuation by tree, statistically significant differences were obtained, which showed the independence of the used formula. The exception was when being applied to emblematic species or to species that stand-out in some amenity. Likewise, it was observed that the basic value continues having a high impact in the appraisal final result and the use of the statistical test applied allows extending this type of analyses

A Qualitative Analysis of the Use of Financial Services and Saving Behavior among Older African Americans and Latinos in the Los Angeles Area

For this study, we conducted 7 focus groups in the Los Angeles area with a total of 70 participants (42 Latinos and 28 African Americans) recruited from 3 senior centers and a church. Overall, participants were not well prepared for the future in terms of their health care financing. African Americans in the study tended to participate more in the formal financial sector and show a high level of sophistication when managing their finances than Latinos. African Americans also were more likely to save than Latinos, but their level of saving was not very large. We also find that participants in all groups do not want to ask their children for money, and also do not want to save and accumulate wealth to leave to their children because they do not trust or feel appreciated by them

POTENCIAL ALIMENTICIO DE LOS TOMATES DE CÁSCARA (Physalis spp.) DE MÉXICO

Physalis L. (Solanaceae) is an American genus that produces edible fruits recognized commonly as green tomato, husk tomato and tomatillo among other names; they have a dietary use rooted in the daily diet of many geographical areas in México, where the species P. philadelphica and P. angulate are cultivated, in addition to the collection of fruits of at least a dozen wild species. Evidences of the nutritional and functional value of the fruits are reviewed, citing the comparative contents of four principal species in terms of fiber, minerals, proteins, lipids and soluble sugars, as well as vitamins A and C, and some bioactive phytochemical principles with antioxidant, anticancer, anti-inflammatory and antibiotic properties, among others. These properties make husk tomatoes biological models of great interest for the agricultural and pharmaceutical industries.Physalis L. (Solanaceae) es un género americano que produce frutos comestibles reconocidos comúnmente como tomate verde, tomate de cáscara y miltomate, entre otros nombres. Tienen uso alimenticio arraigado en la dieta diaria de muchas áreas geográficas de México, donde se cultivan las especies P. philadelphica y P. angulata, además de la recolección de frutos de al menos una docena de especies silvestres. Se revisan evidencias del valor nutrimental y funcional de los frutos, citando los contenidos comparativos de cuatro especies principales en cuanto a fibra, minerales, proteína, lípidos y azúcares solubles, así como de vitaminas A y C, algunos principios fitoquímicos bioactivos con propiedades antioxidantes, anticancerígenas, antiinflamatorias y antibióticas, entre otras. Estas propiedades hacen de los tomates de cáscara modelos biológicos de gran interés para la industria agrícola y la farmacéutica

Preparation of low cost SERS-substrates for virus characterization

Raman spectroscopy is a technique that allows the characterization and detection of a wide range of molecules. The characterization of biomolecules and viruses has been a novel application in the last decades. A relevant problem for applying this technique is the low intensity of the Raman signal and the low concentration of the analyte, which makes the identification of molecules and viruses quite difficult. An alternative to overcome this problem is the use of surface- enhanced Raman spectroscopy (SERS). This involves the use of SERS-substrates that generally are very expensive and can only be used once. In this work, we report the preliminary results of virus detection by SERS using low-cost homemade substrates and commercially available substrates. Characteristic Raman peaks associated with the influenza virus were detected. The results obtained with the homemade SERS-substrates are comparable to the obtained by using the comercial ones.Preparación de sustratos SERS de bajo coste para caracterización de virus La espectroscopia Raman es una técnica que permite la caracterización y detección de una amplia gama de moléculas. La caracterización de biomoléculas y virus ha sido una aplicación novedosa en las últimas décadas. Un problema relevante para aplicar esta técnica es la baja intensidad de la señal de Raman y la baja concentración de analito, lo que dificulta bastante la identificación de moléculas y virus. Una alternativa para superar este problema es el uso de SERS (surface-enhanced Raman spectroscopy). Esto implica el uso de sustratos SERS que generalmente cuestan una cantidad considerable de dinero y solo se pueden usar una vez. En este trabajo, reportamos resultados preliminares de la detección de virus por SERS utilizando sustratos caseros de bajo costo y sustratos disponibles comercialmente. Se detectaron picos característicos Raman asociados a virus de la influenza. Los resultados obtenidos con los sustratos SERS caseros son comparables a los obtenidos utilizando los comerciales

Induced inflation from a 5D purely kinetic scalar field formalism on warped product spaces

Considering a separable and purely kinetic 5D scalar field on a warped product metric background we propose a new and more general approach for inducing 4D scalar potentials on a 4D constant foliation of the 5D space-time. We obtain an induced potential for a true 4D scalar field instead of a potential for an effective 4D scalar field. In this formalism we can recover the usual 4D inflationary formalism with a geometrically induced inflationary potential. In addition the quantum confinement of the inflaton modes is obtained naturally from the model for at least a class of warping factors. Besides the 4D inflationary physics that results of this formalism is independent of the 4D-hypersurface chosen.Comment: 8 pages Accepted for publication in European Physical Journal