15,872 research outputs found

    Radio observations of evaporating objects in the Cygnus OB2 region

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    We present observations of the Cygnus OB2 region obtained with the Giant Metrewave Radio Telescope (GMRT) at frequencies of 325 and 610 MHz. In this contribution we focus on the study of proplyd-like objects (also known as free-floating evaporating gas globules or frEGGs) that typically show an extended cometary morphology. We identify eight objects previously studied at other wavelengths and derive their physical properties by obtaining their optical depth at radio-wavelengths. Using their geometry and the photoionization rate needed to produce their radio-continuum emission, we find that these sources are possibly ionized by a contribution of the stars Cyg OB2 #9 and Cyg OB2 #22. Spectral index maps of the eight frEGGs were constructed, showing a flat spectrum in radio frequencies in general. We interpret these as produced by optically thin ionized gas, although it is possible that a combination of thermal emission, not necessarily optically thin, produced by a diffuse gas component and the instrument response (which detects more diffuse emission at low frequencies) can artificially generate negative spectral indices. In particular, for the case of the Tadpole we suggest that the observed emission is not of non-thermal origin despite the presence of regions with negative spectral indices in our maps.Fil: Isequilla, Natacha Laura. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: 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; ArgentinaFil: Benaglia, Paula. 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; ArgentinaFil: Ishwara Chandra, C. H.. National Center For Radio Astrophysics; IndiaFil: del Palacio, Santiago. 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. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

    The abundance of 28Si32S, 29Si32S, 28Si34S, and 30Si32S in the inner layers of the envelope of IRC+10216

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    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

    Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution

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    The chemical composition of the gas in galaxies versus cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required link between local and high redshift universe. In this work we focus on the metallicity of the gas of star-forming galaxies at low redshift, looking for signs of chemical evolution. To analyze the metallicity contents star-forming galaxies of similar luminosities and masses at different redshifts. With this purpose, we present a study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5), using different redshift intervals from 0.04 to 0.4. We used data processed with the STARLIGHT spectral synthesis code, correcting the fluxes for dust extinction, estimating metallicities using the R_23 method, and segregating the samples with respect to the value of the [NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting the upper branch. We analyze the luminosity and mass-metallicity relations, and the effect of the Sloan fiber diameter looking for possible biases. By dividing our redshift samples in intervals of similar magnitude and comparing them, significant signs of metallicity evolution are found. Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&

    Experimental evaluation of IEEE 802.15.4/ZigBee for multi-patient ECG monitoring

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    IEEE 802.15.4/ZigBee wireless sensor networks (WSNs) are a promising alternative to cabled systems for patient monitoring in hospitals. Some areas where monitoring systems based on WSNs can be successfuly used are ambulatory, waiting and triage rooms, post-op, and emergency rooms. The low power and small size ZigBee devices have the ability to form self-configuring networks that can extend themselves through a hospital wing or floor. Using spatially distributed networks, it is possible to cover an extended area and serve several patients. However, the low data rate protocols provided by IEEE 802.15.4 poses several challenges, mainly because its protocols were primarily designed to operate in low traffic load scenarios but some vital signs sensors generate a large volume of data. This work presents an experimental evaluation of the performance of multi-hop ZigBee networks comprised of several nodes that carry the traffic of wearable electrocardiogram (ECG) sensors. The results indicate that star networks can relay 100% of the traffic generated by at least 12 ECG nodes. In tree topologies, the increase of the network traffic load reduces the performance but even these networks can reliably relay the traffic of a considerable number of ECG nodes.Fundação para a Ciência e a Tecnologia (FCT)Grupo AMI – Assistência Médica Integral (Casa de Saúde Guimarães, SA

    Lista de los peces de la provincia de Santiago del Estero

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    …los censos de la fauna de un país o región cualquiera, constituyen una suerte de codificación de la Naturaleza, como paso previo e indispensable para un ensayo racional de aprovechamiento de las riquezas naturales y de su adecuada conservación. Desde fines del siglo XVIII se ha dicho, y lo han repetido en nuestro medio, Cosme Argerich, Alberto Palcos y otros estudiosos y cientistas, que un Código de la Naturaleza es indispensable para la libertad de una nación. [R. A. Ringuelet & R. H. Arámburu. Enumeración sistemática de los vertebrados de la Provincia de Buenos Aires. La Plata, MAA, Publ. 119, 1957].Fil: Fernandez, Luis Alfredo. Fundación Miguel Lillo; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nadalin, D.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Lopez, H. L.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Andreoli Bize, M. J.. Universidad Nacional de Catamarca. Facultad de Ciencias Exactas y Naturales; Argentin

    ALMA CN Zeeman Observations of AS 209: Limits on Magnetic Field Strength and Magnetically Driven Accretion Rate

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    While magnetic fields likely play an important role in driving the evolution of protoplanetary disks through angular momentum transport, observational evidence of magnetic fields has only been found in a small number of disks. Although dust continuum linear polarization has been detected in an increasing number of disks, its pattern is more consistent with that from dust scattering than from magnetically aligned grains in the vast majority of cases. Continuum linear polarization from dust grains aligned to a magnetic field can reveal information about the magnetic field´s direction, but not its strength. On the other hand, observations of circular polarization in molecular lines produced by Zeeman splitting offer a direct measure of the line-of-sight magnetic field strength in disks. We present upper limits on the net toroidal and vertical magnetic field strengths in the protoplanetary disk AS 209 derived from Zeeman splitting observations of the CN 2-1 line. The 3σ upper limit on the net line-of-sight magnetic field strength in AS 209 is 5.0 mG on the redshifted side of the disk and 4.2 mG on the blueshifted side of the disk. Given the disk´s inclination angle, we set a 3σ upper limit on the net toroidal magnetic field strength of 8.7 and 7.3 mG for the red and blue sides of the disk, respectively, and 6.2 and 5.2 mG on the net vertical magnetic field on the red and blue sides of the disk. If magnetic disk winds are a significant mechanism of angular momentum transport in the disk, magnetic fields of a strength close to the upper limits would be sufficient to drive accretion at the rate previously inferred for regions near the protostar.Fil: Harrison, Rachel. University of Illinois at Urbana; Estados UnidosFil: Looney, L. W.. University of Illinois at Urbana; Estados UnidosFil: Stephens, I. W.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Li, Z.-Y.. University of Virginia; Estados UnidosFil: Teague, Richard. Department Of Astronomy; Estados UnidosFil: Crutcher, Richard. University of Illinois at Urbana; Estados UnidosFil: Yang, H.. Tsinghua University; ChinaFil: Cox, E. G.. Northwestern University; Estados UnidosFil: 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; ArgentinaFil: Shinnaga, H.. Kagoshima University; Japó

    PileLineGUI: a desktop environment for handling genome position files in next-generation sequencing studies

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    Next-generation sequencing (NGS) technologies are making sequence data available on an unprecedented scale. In this context, new catalogs of Single Nucleotide Polymorphism and mutations generated by resequencing studies are usually stored in genome position files (e.g. Variant Call Format, SAMTools pileup, BED, GFF) comprising of large lists of genomic positions, which are difficult to handle by researchers. Here, we present PileLineGUI, a novel desktop application primarily designed for manipulating, browsing and analysing genome position files (GPF), with specific support to somatic mutation finding studies. The developed tool also integrates a new genome browser module specially designed for inspecting GPFs. PileLineGUI is free, multiplatform and designed to be intuitively used by biomedical researchers. PileLineGUI is available at: http://sing.ei.uvigo.es/pileline/pilelinegui.html

    Calcium Homeostasis in Myogenic Differentiation Factor 1 (MyoD)-Transformed, Virally-Transduced, Skin-Derived Equine Myotubes

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    Dysfunctional skeletal muscle calcium homeostasis plays a central role in the pathophysiology of several human and animal skeletal muscle disorders, in particular, genetic disorders associated with ryanodine receptor 1 (RYR1) mutations, such as malignant hyperthermia, central core disease, multiminicore disease and certain centronuclear myopathies. In addition, aberrant skeletal muscle calcium handling is believed to play a pivotal role in the highly prevalent disorder of Thoroughbred racehorses, known as Recurrent Exertional Rhabdomyolysis. Traditionally, such defects were studied in human and equine subjects by examining the contractile responses of biopsied muscle strips exposed to caffeine, a potent RYR1 agonist. However, this test is not widely available and, due to its invasive nature, is potentially less suitable for valuable animals in training or in the human paediatric setting. Furthermore, increasingly, RYR1 gene polymorphisms (of unknown pathogenicity and significance) are being identified through next generation sequencing projects. Consequently, we have investigated a less invasive test that can be used to study calcium homeostasis in cultured, skin-derived fibroblasts that are converted to the muscle lineage by viral transduction with a MyoD (myogenic differentiation 1) transgene. Similar models have been utilised to examine calcium homeostasis in human patient cells, however, to date, there has been no detailed assessment of the cells’ calcium homeostasis, and in particular, the responses to agonists and antagonists of RYR1. Here we describe experiments conducted to assess calcium handling of the cells and examine responses to treatment with dantrolene, a drug commonly used for prophylaxis of recurrent exertional rhabdomyolysis in horses and malignant hyperthermia in humans
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