15,601 research outputs found
Strongly misaligned triple system in SR 24 revealed by ALMA
We report the detection of the 1.3 mm continuum and the molecular emission of the disks of the young triple system SR24 by analyzing ALMA (The Atacama Large Millimeter/Submillimter Array) subarcsecond archival observations. We estimate the mass of the disks (0.025 M ⊙ and 4 × 10‑5 M ⊕ for SR24S and SR24N, respectively) and the dynamical mass of the protostars (1.5 M ⊙ and 1.1 M ⊙). A kinematic model of the SR24S disk to fit its C18O (2-1) emission allows us to develop an observational method to determine the tilt of a rotating and accreting disk. We derive the size, inclination, position angle, and sense of rotation of each disk, finding that they are strongly misaligned (108^circ ) and possibly rotate in opposite directions as seen from Earth, in projection. We compare the ALMA observations with 12CO SMA archival observations, which are more sensitive to extended structures. We find three extended structures and estimate their masses: a molecular bridge joining the disks of the system, a molecular gas reservoir associated with SR24N, and a gas streamer associated with SR24S. Finally, we discuss the possible origin of the misaligned SR24 system, concluding that a closer inspection of the northern gas reservoir is needed to better understand it. Fil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zapata, L. A.. Universidad Nacional Autónoma de México; MéxicoFil: Gabbasov, R.. Universidad Autónoma del Estado de Hidalgo; Méxic
Turning waves and breakdown for incompressible flows
We consider the evolution of an interface generated between two immiscible
incompressible and irrotational fluids. Specifically we study the Muskat and
water wave problems. We show that starting with a family of initial data given
by (\al,f_0(\al)), the interface reaches a regime in finite time in which is
no longer a graph. Therefore there exists a time where the solution of
the free boundary problem parameterized as (\al,f(\al,t)) blows-up: \|\da
f\|_{L^\infty}(t^*)=\infty. In particular, for the Muskat problem, this result
allows us to reach an unstable regime, for which the Rayleigh-Taylor condition
changes sign and the solution breaks down.Comment: 15 page
Analysis of Energy Consumption Performance towards Optimal Radioplanning of Wireless Sensor Networks in Heterogeneous Indoor Environments
In this paper the impact of complex indoor environment in the deployment and energy consumption of a wireless sensor network infrastructure is analyzed. The variable nature of the radio channel is analyzed by means of deterministic in-house 3D ray launching simulation of an indoor scenario, in which wireless sensors, based on an in-house CyFi implementation, typically used for environmental monitoring, are located. Received signal power and current consumption measurement results of the in-house designed wireless motes have been obtained, stating that adequate consideration of the network topology and morphology lead to optimal performance and power consumption reduction. The use of radioplanning techniques therefore aid in the deployment of more energy efficient elements, optimizing the overall performance of the variety of deployed wireless systems within the indoor scenario
The abundance of 28Si32S, 29Si32S, 28Si34S, and 30Si32S in the inner layers of the envelope of IRC+10216
We present high spectral resolution mid-IR observations of SiS towards the
C-rich AGB star IRC+10216 carried out with the Texas Echelon-cross-Echelle
Spectrograph mounted on the NASA Infrared Telescope Facility. We have
identified 204 ro-vibrational lines of 28Si32S, 26 of 29Si32S, 20 of 28Si34S,
and 15 of 30Si32S in the frequency range 720-790 cm-1. These lines belong to
bands v=1-0, 2-1, 3-2, 4-3, and 5-4, and involve rotational levels with
Jlow<90. About 30 per cent of these lines are unblended or weakly blended and
can be partially or entirely fitted with a code developed to model the mid-IR
emission of a spherically symmetric circumstellar envelope composed of
expanding gas and dust. The observed lines trace the envelope at distances to
the star <35R* (~0.7 arcsec). The fits are compatible with an expansion
velocity of 1+2.5(r/R*-1) km/s between 1 and 5R*, 11 km/s between 5 and 20R*,
and 14.5 km/s outwards. The derived abundance profile of 28Si32S with respect
to H2 is 4.9e-6 between the stellar photosphere and 5R*, decreasing linearly to
1.6e-6 at 20R* and to 1.3e-6 at 50R*. 28Si32S seems to be rotationally under
LTE in the region of the envelope probed with our observations and
vibrationally out of LTE in most of it. There is a red-shifted emission excess
in the 28Si32S lines of band v=1-0 that cannot be found in the lines of bands
v=2-1, 3-2, 4-3, and 5-4. This excess could be explained by an enhancement of
the vibrational temperature around 20R* behind the star. The derived isotopic
ratios 28Si/29Si, and 32S/34S are 17 and 14, compatible with previous
estimates.Comment: 11 pages, 5 figures, and 4 tables. Accepted for publication in MNRA
Characterization of Nb22O54 microrods grown from niobium oxide powders recovered from mine tailings
In this work, the possibility of using niobium oxide recovered from tailings
from the Penouta Sn-Nb-Ta deposit (located at the North of Spain) as starting
material for growing microstructures is demonstrated. The properties of the
starting material have been studied to understand its crystal structure,
quality and purity. Recovered niobium oxide powders are mainly of TT-Nb2O5.
These powders have been used to grow Nb22O54 microrods by an evaporation method
in an argon atmosphere. Different characterization techniques (X-Ray
diffraction, scanning electron microscopy, micro-Raman spectroscopy,
luminescence) have been used to determine the properties of Nb22O54 microrods,
mainly focusing on the crystal quality and refractive index. The present study
opens the way to the transformation of waste (mine tailings) into a material of
high technological value as niobium oxide, and its reintroduction into the
value chain for a wide range of applications, from coatings to batteries and
supercapacitors
Status report of the baseline collimation system of CLIC. Part II
Important efforts have recently been dedicated to the characterisation and
improvement of the design of the post-linac collimation system of the Compact
Linear Collider (CLIC). This system consists of two sections: one dedicated to
the collimation of off-energy particles and another one for betatron
collimation. The energy collimation system is further conceived as protection
system against damage by errant beams. In this respect, special attention is
paid to the optimisation of the energy collimator design. The material and the
physical parameters of the energy collimators are selected to withstand the
impact of an entire bunch train. Concerning the betatron collimation section,
different aspects of the design have been optimised: the transverse collimation
depths have been recalculated in order to reduce the collimator wakefield
effects while maintaining a good efficiency in cleaning the undesired beam
halo; the geometric design of the spoilers has been reviewed to minimise
wakefields; in addition, the optics design has been optimised to improve the
collimation efficiency. This report presents the current status of the the
post-linac collimation system of CLIC. Part II is mainly dedicated to the study
of the betatron collimation system and collimator wakefield effects.Comment: 25 pages, 13 figure
1.3 mm Polarized emission in the circumstellar disk of a massive protostar
We present the first resolved observations of the 1.3 mm polarized emission from the disk-like structure surrounding the high-mass protostar Cepheus A HW2. These CARMA data partially resolve the dust polarization, suggesting a uniform morphology of polarization vectors with an average position angle of 57° ± 6° and an average polarization fraction of 2.0% ± 0.4%. The distribution of the polarization vectors can be attributed to (1) the direct emission of magnetically aligned grains of dust by a uniform magnetic field, or (2) the pattern produced by the scattering of an inclined disk. We show that both models can explain the observations, and perhaps a combination of the two mechanisms produces the polarized emission. A third model including a toroidal magnetic field does not match the observations. Assuming scattering is the polarization mechanism, these observations suggest that during the first few 104 years of high-mass star formation, grain sizes can grow from1 mm to several 10s μm.Fil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; ArgentinaFil: Stephens, I. W.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Boston University; Estados Unidos. University of Illinois; Estados UnidosFil: Girart, J. M.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Institut de Ciències de l’Espai; EspañaFil: Looney, L.. University of Illinois; Estados UnidosFil: Curiel, S.. Universidad Nacional Autónoma de México; MéxicoFil: Segura Cox, D.. University of Illinois; Estados UnidosFil: Eswaraiah, C.. National Tsing Hua University; República de ChinaFil: Lai, S. P.. National Tsing Hua University; República de Chin
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Validation in clinical population of the Problematic Internet Entertainment Use Scale for Adults (PIEUSAd)
Addiction to technologies has been a widely debated scientific and clinically, being a condition for further study as potential psychiatric disorder. Some Spanish scales measure Internet addiction, but no one has been validated clinically. The aims were to describe a clinical sample of patients in treatment for a technology addiction, and to validate clinically the “Problematic Internet Entertainment Use Scale for Adults” (PIEUSAd). Little-scale clinical adult sample (N=31; 71 % men, and an age mean of 33.31) was selected, collecting socio-demographic and clinical data, technological usages, and the PIEUSAd and Compulsive Internet Use Scale in a survey. The setting was a public health center in Barcelona (Spain). The patients in treatment for a technological addiction as primary diagnosis were usually young males, which suffer from a genuine e-addiction (above all, internet addiction, gaming and cybersex); only the middle seems to have a dual pathology (usually another addiction). They are usually referred by other clinician and the majority don’t have previous psychiatric care. The PIEUSAd showed large variability in item scored, and high factor and construct validity, and excellent reliability (a=0.98). In conclusion, the heterogeneity in the characteristics of patients is evidenced. Moreover, the PIEUSAd has been clinical validated to do a better screen in technological addictions, where “loss of control” and “evasion” seems to be the prevalent addictive symptoms in these types of patients.
Spanish abstract: La adicción a las tecnologías ha sido debatida ampliamente tanto científica como clínicamente, siendo una condición a estudiar como potencial trastorno psiquiátrico. Algunas escalas españolas miden la adicción al internet, pero ninguna ha sido validada clínicamente. Los objetivos son describir la muestra clínica de pacientes en tratamiento por una adicción tecnológica, así como validar clínicamente la “Problematic Internet Entertainment Use Scale for Adults” (PIEUSAd). Una muestra clínica a pequeña escala (N=31; 71 % hombres, con una edad media de 33,31) fue seleccionada, se recogieron datos socio-demográficos, clínicos y de uso de tecnologías, así como la PIEUSAd y la “Compulsive Internet Use Scale” a través de una encuesta. El contexto fue un centro de salud pública de Barcelona (España). Los pacientes en tratamiento por una adicción tecnológica como primer diagnóstico eran usualmente hombres jóvenes que sufrían de una e-adicción genuina (sobre todo, adicción a internet, videojuegos o cibersexo); solo la mitad parecía sufrir una patología dual (normalmente otra adicción). Eran normalmente derivados por otros profesionales de la salud y la mayor parte no habían sido tratados psiquiá- tricamente con anterioridad. La PIEUSAd mostró gran variabilidad en sus puntuaciones, alta validez factorial y de constructo, y excelente fiabilidad (a=0,98). En conclusión, la heterogeneidad de las características de los pacientes fue evidenciada. Además, la PIEUSAd ha sido validada clínicamente para poder hacer un mejor cribado en las adicciones tecnológicas, donde la “pérdida de control” y la “evasión” parecen ser los síntomas prevalentes en estos tipos de pacientes
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