Preliminary criteria for internal acoustic environments of orbiting space stations

Maximum noise levels for manned orbiting space station

Estimate of nuclear technology engine test stand sound power and spectrum

Estimate of nuclear technology engine test stand sound power and spectru

Estimation of <i>Vs</i> profile using its natural frequency and Rayleigh-wave dispersion characteristics

International audienceThe evaluation of the natural frequency of random Vs profiles before analyzing the fundamental Rayleigh-wave dispersion characteristics is proposed in this paper. The inclusion of this parameter optimizes the effectiveness of random inverse searching to estimate Vs profiles. To demonstrate this method, a numerical test was performed using the "experimental" Rayleigh-wave dispersion curve obtained for a fictitious TEST site

Limiting eccentricity of sub-parsec massive black hole binaries surrounded by self-gravitating gas discs

We study the dynamics of supermassive black hole binaries embedded in circumbinary gaseous discs, with the SPH code Gadget-2. The sub-parsec binary (of total mass M and mass ratio q=1/3) has excavated a gap and transfers its angular momentum to the self--gravitating disc (M_disc=0.2 M). We explore the changes of the binary eccentricity e, by simulating a sequence of binary models that differ in the initial eccentricity e_0, only. In initially low-eccentric binaries, the eccentricity increases with time, while in high-eccentric binaries e declines, indicating the existence of a limiting eccentricity e_crit that is found to fall in the interval [0.6,0.8]. We also present an analytical interpretation for this saturation limit. An important consequence of the existence of e_crit is the detectability of a significant residual eccentricity e_LISA} by the proposed gravitational wave detector LISA. It is found that at the moment of entering the LISA frequency domain e_LISA ~ 10^{-3}-10^{-2}; a signature of its earlier coupling with the massive circumbinary disc. We also observe large periodic inflows across the gap, occurring on the binary and disc dynamical time scales rather than on the viscous time. These periodic changes in the accretion rate (with amplitudes up to ~100%, depending on the binary eccentricity) can be considered a fingerprint of eccentric sub-parsec binaries migrating inside a circumbinary disc.Comment: 10 pages, 7 figures, accepted for publication in MNRA

Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx

We present optical and infrared photometry of the unusual Type Ia supernova 2000cx. With the data of Li et al. (2001) and Jha (2002), this comprises the largest dataset ever assembled for a Type Ia SN, more than 600 points in UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B-V colors as SN 2000cx entered the nebular phase. Its I-band secondary hump was extremely weak given its B-band decline rate. The V minus near infrared colors likewise do not match loci based on other slowly declining Type Ia SNe, though V-K is the least ``abnormal''. In several ways SN 2000cx resembles other slow decliners, given its B-band decline rate (Delta m_15(B) = 0.93), the appearance of Fe III lines and weakness of Si II in its pre-maximum spectrum, the V-K colors and post-maximum V-H colors. If the distance modulus derived from Surface Brightness Fluctuations of the host galaxy is correct, we find that the rate of light increase prior to maximum, the characteristics of the bolometric light curve, and the implied absolute magnitude at maximum are all consistent with a sub-luminous object with Delta m_15(B) ~ 1.6-1.7 having a higher than normal kinetic energy.Comment: 46 pages, 17 figures, to be published in Publications of the Astronomical Society of the Pacifi

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

Dermatitis crónica por sensibilización al níquel en un paciente con fractura del astrágalo tratada mediante osteosíntesis

Se presenta un varón de 25 años, con fractura del astrágalo izquierdo tratada mediante osteosíntesis con 2 tornillos de acero inoxidable con un contenido en níquel del 12-14%. A los 4 meses de la intervención, el paciente desarrolló una dermatitis pruriginosa en cara lateral externa del pie, en la zona cutánea supra-adyacente al lugar de la osteosíntesis. La lesión no cedió con el tratamiento tópico convencional a base de corticoides. Las pruebas epicutáneas realizadas con la batería estándar del Grupo Español de Investigación en Dermatitis de Contacto revelaron un parche positivo vesiculoso (+ +) al sulfato de níquel al 2,5% y al cloruro de cobalto al 1%, ambos aplicados en vaselina, en la lectura a las 48 y 96 horas. En vista de que las lesiones permanecían estables al mes de tratamiento con un potente corticoide en cura oclusiva y antihistamínicos sistémicos, se procedió a retirar los tornillos de osteosíntesis. A los pocos días de la intervención comenzó a desaparecer el prurito y, en el curso de 2 semanas, se produjo la curación completa de la dermatitisSe presenta un varón de 25 años, con fractura del astrágalo izquierdo tratada mediante osteosíntesis con 2 tornillos de acero inoxidable con un contenido en níquel del 12-14%. A los 4 meses de la intervención, el paciente desarrolló una dermatitis pruriginosa en cara lateral externa del pie, en la zona cutánea supra-adyacente al lugar de la osteosíntesis. La lesión no cedió con el tratamiento tópico convencional a base de corticoides. Las pruebas epicutáneas realizadas con la batería estándar del Grupo Español de Investigación en Dermatitis de Contacto revelaron un parche positivo vesiculoso (+ +) al sulfato de níquel al 2,5% y al cloruro de cobalto al 1%, ambos aplicados en vaselina, en la lectura a las 48 y 96 horas. En vista de que las lesiones permanecían estables al mes de tratamiento con un potente corticoide en cura oclusiva y antihistamínicos sistémicos, se procedió a retirar los tornillos de osteosíntesis. A los pocos días de la intervención comenzó a desaparecer el prurito y, en el curso de 2 semanas, se produjo la curación completa de la dermatitis

Self-gravitating fragmentation of eccentric accretion disks

We consider the effects of eccentricity on the fragmentation of gravitationally unstable accretion disks, using numerical hydrodynamics. We find that eccentricity does not affect the overall stability of the disk against fragmentation, but significantly alters the manner in which such fragments accrete gas. Variable tidal forces around an eccentric orbit slow the accretion process, and suppress the formation of weakly-bound clumps. The "stellar" mass function resulting from the fragmentation of an eccentric disk is found to have a significantly higher characteristic mass than that from a corresponding circular disk. We discuss our results in terms of the disk(s) of massive stars at ~0.1pc from the Galactic Center, and find that the fragmentation of an eccentric accretion disk, due to gravitational instability, is a viable mechanism for the formation of these systems.Comment: 9 pages, 7 figures. Accepted for publication in Ap