Asteroseismological study of massive ZZ Ceti stars with fully evolutionary models

We present the first asteroseismological study for 42 massive ZZ Ceti stars based on a large set of fully evolutionary carbon$-$oxygen core DA white dwarf models characterized by a detailed and consistent chemical inner profile for the core and the envelope. Our sample comprise all the ZZ Ceti stars with spectroscopic stellar masses between 0.72 and $1.05M_{\odot}$ known to date. The asteroseismological analysis of a set of 42 stars gives the possibility to study the ensemble properties of the massive pulsating white dwarf stars with carbon$-$oxygen cores, in particular the thickness of the hydrogen envelope and the stellar mass. A significant fraction of stars in our sample have stellar mass high enough as to crystallize at the effective temperatures of the ZZ Ceti instability strip, which enables us to study the effects of crystallization on the pulsation properties of these stars. Our results show that the phase diagram presented in Horowitz et al. (2010) seems to be a good representation of the crystallization process inside white dwarf stars, in agreement with the results from white dwarf luminosity function in globular clusters.Comment: 58 pages, 11 figures, accepted in Ap

Discovery of a new PG1159 (GW Vir) Pulsator

We report the discovery of pulsations in the spectroscopic PG 1159 type pre-white dwarf SDSS J075415.12+085232.18. Analysis of the spectrum by Werner, Rauch and Kepler (2014) indicated Teff=120 000+/-10 000 K, log g=7.0+/-0.3, mass M=0.52+/-0.02 Msun, C/He=0.33 by number. We obtained time-series images with the SOAR 4.1 m telescope and 2.1 m Otto Struve telescope at McDonald Observatory and show the star is also a variable PG 1159 type star, with dominant period of 525 s.Comment: 5 pages, 3 figure

Hydrodynamic Models for Heavy-Ion Collisions, and beyond

A generic property of a first-order phase transition in equilibrium, and in the limit of large entropy per unit of conserved charge, is the smallness of the isentropic speed of sound in the ``mixed phase''. A specific prediction is that this should lead to a non-isotropic momentum distribution of nucleons in the reaction plane (for energies around 40 AGeV in our model calculation). On the other hand, we show that from present effective theories for low-energy QCD one does not expect the thermal transition rate between various states of the effective potential to be much larger than the expansion rate, questioning the applicability of the idealized Maxwell/Gibbs construction. Experimental data could soon provide essential information on the dynamics of the phase transition.Comment: 10 Pages, 4 Figures. Presented at 241st WE-Heraeus Seminar: Symposium on Fundamental Issues in Elementary Matter: In Honor and Memory of Michael Danos, Bad Honnef, Germany, 25-29 Sep 200

Treatment of bimodality in proficiency test of pH in bioethanol matrix

The pH value in bioethanol is a quality control parameter related to its acidity and to the corrosiveness of vehicle engines when it is used as fuel. In order to verify the comparability and reliability of the measurement of pH in bioethanol matrix among some experienced chemical laboratories, reference material (RM) of bioethanol developed by Inmetro - the Brazilian National Metrology Institute - was used in a proficiency testing (PT) scheme. There was a difference of more than one unit in the value of the pH measured due to the type of internal filling electrolytic solutions (potassium chloride, KCl or lithium chloride, LiCl) from the commercial pH combination electrodes used by the participant laboratories. Therefore, bimodal distribution has occurred from the data of this PT scheme. This work aims to present the possibilities that a PT scheme provider can use to overcome the bimodality problem. Data from the PT of pH in bioethanol were treated by two different statistical approaches: kernel density model and the mixture of distributions. Application of these statistical treatments improved the initial diagnoses of PT provider, by solving bimodality problem and contributing for a better performance evaluation in measuring pH of bioethanol.Comment: 20 pages, 6 figures, Accepted for publication in Accreditation and Quality Assurance (ACQUAL

Silicon Carbide as Base Material for MEMS Sensors of Aerospace Use: An Overview

This paper discusses the use of silicon carbide (SiC), in bulk and thin-film form, in MEMS (Micro-Electro-Mechanical Systems) sensors for extreme environment applications, especially in aerospace. The physical and chemical properties of SiC that make it a suitable material for electronic devices and sensors are described. Concepts, developments and applications of MEMS technology are presented. An overview of the current stage of development of SiC-based MEMS sensors and an analysis of research conducted in this area in Brazil and abroad, both in universities and industries are also presented. The recent progress made, difficulties encountered and the impact of these investigations are discussed as well as the outlook for the near future.Este artigo discute o emprego do carbeto de silício (SiC), na forma de substrato e filme fino, em sensores MEMS (Micro-Electro-Mechanical Systems) para aplicações em ambientes sujeitos a condições extremas, especialmente no setor aeroespacial. As propriedades físicas e químicas do SiC que o tornam um material adequado para dispositivos eletrônicos e sensores são descritas. Os conceitos, evolução e aplicações da tecnologia MEMS são apresentados. Uma visão geral sobre o estágio atual de desenvolvimento de sensores MEMS baseados em SiC e uma análise das pesquisas realizadas nesta área no exterior e no Brasil, tanto nas universidades quanto nas indústrias, são também apresentadas. Os recentes avanços alcançados, as dificuldades encontradas e o impacto dessas pesquisas são discutidos, bem como as perspectivas para um futuro próximo.FATEC CEETEPS Departamento de Ensino GeralUNIVAP Instituto de Pesquisa e DesenvolvimentoUNIFESP Instituto de Ciência e TecnologiaUNIFESP, Instituto de Ciência e TecnologiaSciEL

La transfixión percutánea cúbito-carpiana en las fracturas inestables de la extremidad distal del radio

Se expone una alternativa terapéutica para las fracturas inestables de la extremidad distal del radio, consistente en estabilizar la reducción mediante una aguja de Kirschner que atravesando oblícuamente la extremidad distal del cúbito se ancla en el carpo. Se precisan los detalles de la técnica que, en una valoración inicial sobre más de cien casos, aporta resultados constantemente satisfactorios. Se hace énfasis en la sencillez del procedimiento, que al propiciar una ejecución muy rápida, cobra ventaja frente a otras modalidades (fijador externo, osteosíntesis abierta, etc.) y especialmente ante traumatismos asociados del mismo miembro.A therapeutic alternative for the unstable fractures of the distal extremity of the radius is presented. The technique consists in stabilizing the fracture reduction by means of one Kirschner's wire that crosses obliquely the distal extremity of the ulnar and anchors in the carpus. The details of this technique are described. This technique has constantly provided satisfactory results in an initial evaluation on more than one hundred cases. Emphasis is made upon the simplicity of the procedure which surpasses other technical procedures (external fixation, open osteosynthesis, etc.) due to the fact that it propitiates a quicker execution, and it surpasses other technical procedures specially with associated injuries in the same limb

Zero-mode analysis of quantum statistical physics

We present a unified formulation for quantum statistical physics based on the representation of the density matrix as a functional integral. We identify the stochastic variable of the effective statistical theory that we derive as a boundary configuration and a zero mode relevant to the discussion of infrared physics. We illustrate our formulation by computing the partition function of an interacting one-dimensional quantum mechanical system at finite temperature from the path-integral representation for the density matrix. The method of calculation provides an alternative to the usual sum over periodic trajectories: it sums over paths with coincident endpoints, and includes non-vanishing boundary terms. An appropriately modified expansion into Matsubara modes provides a natural separation of the zero-mode physics. This feature may be useful in the treatment of infrared divergences that plague the perturbative approach in thermal field theory.Comment: 9 pages, 5 figure

Seismology Of A Massive Pulsating Hydrogen Atmosphere White Dwarf

We report our observations of the new pulsating hydrogen atmosphere white dwarf SDSS J132350.28+010304.22. We discovered periodic photometric variations in frequency and amplitude that are commensurate with nonradial g-mode pulsations in ZZ Ceti stars. This, along with estimates for the star's temperature and gravity, establishes it as a massive ZZ Ceti star. We used time-series photometric observations with the 4.1 m SOAR Telescope, complemented by contemporary McDonald Observatory 2.1 m data, to discover the photometric variability. The light curve of SDSS J132350.28+010304.22 shows at least nine detectable frequencies. We used these frequencies to make an asteroseismic determination of the total mass and effective temperature of the star: M-star = 0.88 +/- 0.02 M-circle dot and T-eff = 12,100 +/- 140 K. These values are consistent with those derived from the the optical spectra and photometric colors.CNPqFAPERGS/PronexUS National Science Foundation AST-0909107Norman Hackerman Advanced Research Program 003658-0252-2009MICINN grant AYA08-1839/ESPESF EUROCORES Program EuroGENESIS (MICINN grant) EUI2009-04170Generalitat de Catalunya 2009SGR315EU-FEDER fundsAGENCIA through the Programa de Modernizacion Tecnologica BID 1728/OC-ARCONICET PIP 112-200801-00940Astronom

Quiste óseo aneurismático poliostótico

Se presenta un caso de quiste óseo aneurismático de localización bifocal, correspondiente a una niña de 12 años de edad. La primera lesión diagnosticada se localizó en la metáfisis proximal de la tibia izquierda y dos años más tarde, se descubrió una lesión similar en el calcáneo derecho. El estudio individualizado de estas lesiones no demuestra diferencias significativas respecto a las clásicamente descritas para los quistes óseos aneurismáticos genuinos, monostó- ticos. En una amplia revisión bibliográfica sólo hemos podido encontrar un caso de localización plurifocal.A bifocal aneurysmatic bone cyst presenting in a 12-year-old is reported. The first lesion detected was situated in the proximal metaphysis of the left tibia; the second lesion was diagnosed two years later in the right calcaneus. Individual evaluation of these lesions discovered no significant differences with respect to classical monostotic, true aneurysmatic bone cysts. An exhaustive review of the literature yielded only one case exhibiting plurifocal location