4,739 research outputs found

    High Angular Resolution Observations of the Collimated Jet Source Associated with a Massive Protostar in IRAS 16547-4247

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    A triple radio source recently detected in association with the luminous infrared source IRAS 16547-4247 has been studied with high angular resolution and high sensitivity with the Very Large Array at 3.6 and 2 cm. Our observations confirm the interpretation that the central object is a thermal radio jet, while the two outer lobes are most probably heavily obscured HH objects. The thermal radio jet is resolved angularly for the first time and found to align closely with the outer lobes. The opening angle of the thermal jet is estimated to be 25\sim 25^\circ, confirming that collimated outflows can also be present in massive protostars. The proper motions of the outer lobes should be measurable over timescales of a few years. Several fainter sources detected in the region are most probably associated with other stars in a young cluster.Comment: 9 pages, 2 figure

    Testing Relativity at High Energies Using Spaceborne Detectors

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    (ABRIDGED) The Gamma-ray Large Area Space Telescope (GLAST) will measure the spectra of distant extragalactic sources of high energy gamma-rays. GLAST can look for energy dependent propagation effects from such sources as a signal of Lorentz invariance violation (LIV). Such sources should also exhibit high energy spectral cutoffs from pair production interactions with low energy photons. The properties of such cutoffs can also be used to test LIV. Detectors to measure gamma-ray polarization can look for the depolarizing effect of space-time birefingence predicted by loop quantum gravity. A spaceborne detector array looking down on Earth to study extensive air showers produced by ultrahigh energy cosmic rays can study their spectral properties and look for a possible deviation from the predicted GZK effect as another signal of LIV.Comment: 14 pages, Text of invitated talk presented at the "From Quantum to Cosmos: Fundamental Physics Studies from Space" meeting. More references adde

    The Circumstellar Structure and Excitation Effects around the Massive Protostar Cepheus A HW 2

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    We report SMA 335 GHz continuum observations with angular resolution of ~0.''3, together with VLA ammonia observations with ~1'' resolution toward Cep A HW 2. We find that the flattened disk structure of the dust emission observed by Patel et al. is preserved at the 0.''3 scale, showing an elongated structure of ~$0.''6 size (450 AU) peaking on HW 2. In addition, two ammonia cores are observed, one associated with a hot-core previously reported, and an elongated core with a double peak separated by ~1.''3 and with signs of heating at the inner edges of the gas facing HW 2. The double-peaked ammonia structure, as well as the double-peaked CH3CN structure reported previously (and proposed to be two independent hot-cores), surround both the dust emission as well as the double-peaked SO2 disk structure found by Jimenez-Serra et al. All these results argue against the interpretation of the elongated dust-gas structure as due to a chance-superposition of different cores; instead, they imply that it is physically related to the central massive object within a disk-protostar-jet system.Comment: 12 pages, 3 figures; accepted for publication in the Astrophysical Journa

    Dominant negative phenotype of Bacillus thuringiensis Cry1Ab, Cry11Aa and Cry4Ba mutants suggest hetero-oligomer formation among different Cry toxins.

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    Background - Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix a-4 mutants had a dominant negative (DN) phenotype inhibiting the toxicity of wildtype Cry1Ab when used in equimolar or sub-stoichiometric ratios (1:1, 0.5:1, mutant:wt) indicating that oligomer formation is a key step in toxicity of Cry toxins. Methodology/Principal Findings - The DN Cry1Ab-D136N/T143D mutant that is able to block toxicity of Cry1Ab toxin, was used to analyze its capacity to block the activity against Manduca sexta larvae of other Cry1 toxins, such as Cry1Aa, Cry1Ac, Cry1Ca, Cry1Da, Cry1Ea and Cry1Fa. Cry1Ab-DN mutant inhibited toxicity of Cry1Aa, Cry1Ac and Cry1Fa. In addition, we isolated mutants in helix a-4 of Cry4Ba and Cry11Aa, and demonstrate that Cry4Ba-E159K and Cry11Aa-V142D are inactive and completely block the toxicity against Aedes aegypti of both wildtype toxins, when used at sub-stoichiometric ratios, confirming a DN phenotype. As controls we analyzed Cry1Ab-R99A or Cry11Aa-E97A mutants that are located in helix a-3 and are affected in toxin oligomerization. These mutants do not show a DN phenotype but were able to block toxicity when used in 10:1 or 100:1 ratios (mutant:wt) probably by competition of binding with toxin receptors. Conclusions/Significance - We show that DN phenotype can be observed among different Cry toxins suggesting that may interact in vivo forming hetero-oligomers. The DN phenotype cannot be observed in mutants affected in oligomerization, suggesting that this step is important to inhibit toxicity of other toxin

    Chironomidae (Diptera) in water courses of the Puna and Chaco Serrano of Catamarca (Argentina): first records and distribution of genus and species

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    La distribución en América del Sur (Region Neotropical) de Stictocladius prati Saether & Cranston, Podonomus. regalis Brundin y P. setosus Brundin 1966 es ampliada a partir de primeros registros de la Argentina. Podonomus fastigians Brundin, y Allocladius quadrus Andersen et al. se citan por primera vez de Catamarca Se describe el morfotipo pupal de Barbadocladius sp. "Chaco"(cerca de B. andinus Cranston & Krosh). Se incorporan las variables ambientales de los cursos de agua donde se registraron las especies. Los ríos de Puna presentan aguas muy alcalinas, pH (8.12-8.8), alta conductividad y alto contenido en MO, mientras que el arroyo de Chaco Serrano es de aguas débilmente alcalinas, pH (7), baja conductividad y bajo contenido en materia orgánica (MO). Las especies Stictocladius prati, Allocladius quadrus, Podonomus fastigians, P. setosus y P. regalis estuvieron presentes en ríos de altura con aguas alcalinas y alta conductividad, mientras Barbadocladius sp. "Chaco"se registró en un arroyo de menor altura, con aguas de baja alcalinidad y conductividad.The distribution in South America (Neotropical Region) of Stictocladius prati Saether & Cranston, Podonomus regalis Brundin, and P. setosus Brundin is enlarged as a result of new records from Argentina. Podonomus fastigians Brundin and Allocladius quadrus Andersen et al. are first recorded from Catamarca. The pupal type of Barbadocladius sp. "Chaco"(near B. andinus Cranston & Krosh) is described. Environmental variables in the sites where the species were collected are incorporated. Punean rivers presented alkaline waters and pH (8.12-8.8), high conductivity and organic matter (OM) content. The Chaco Serrano stream presented slightly alkaline waters, pH (7), low conductivity and OM content. The species Stictocladius prati, Allocladius quadrus, Podonomus fastigians P. setosus and P.regalis were present at high altitude rivers, alkaline waters and high conductivity while Barbadocladius sp. "Chaco"was sampled at a low altitude stream, with less alkaline and low conductivity waters.Fil: Rodriguez Garay, Gretel Narda Cecilia. Universidad Nacional de Catamarca. Facultad de Tecnología y Ciencias Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paggi, Analia Constancia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

    An H2CO 6cm Maser Pinpointing a Possible Circumstellar Torus in IRAS18566+0408

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    We report observations of 6cm, 3.6cm, 1.3cm, and 7mm radio continuum, conducted with the Very Large Array towards IRAS18566+0408, one of the few sources known to harbor H2CO 6cm maser emission. Our observations reveal that the emission is dominated by an ionized jet at cm wavelengths. Spitzer/IRAC images from GLIMPSE support this interpretation, given the presence of 4.5um excess emission at approximately the same orientation as the cm continuum. The 7mm emission is dominated by thermal dust from a flattened structure almost perpendicular to the ionized jet, thus, the 7mm emission appears to trace a torus associated with a young massive stellar object. The H2CO 6cm maser is coincident with the center of the torus-like structure. Our observations rule out radiative pumping via radio continuum as the excitation mechanism for the H2CO 6cm maser in IRAS18566+0408.Comment: 20 pages, 4 figures, ApJ (in press

    Aptitud anaerobia en deportistas de combate del sexo femenino

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    Se estudia en nivel de preparación anaerobia en tres selecciones femeninas de deportes de combate de alta calificación: 15 judocas, 7 esgrimistas de la modalidad sable y 16 taekwondoistas. Fueron medidos indicadores neuromusculares, al final de la preparación especial, utilizando los tests de ergosalto y de saltabilidad de Bosco, Se determinan las estadísticas descriptivas, significación de las diferencias entre deportes y la correlación entre indicadores. Se obtienen los resultados: Pala (15,7 ± 2,1-19,2 ± 1,5 W/Kg), Pana (14,5 ± 1,9-17,7 ± 1,2 W/Kg), Los SCAB, SSAB, SCPD, SCPCD y SDPC mas altos fueron los de las esgrimistas y la mejor coordinación se encontró en las competidoras de esgrima, mientras que los mayores valores de CELAS fueron los de las judocas. Los resultados obtenidos se corresponden con las características del gesto deportivo que prevalece en cada uno de los deportes estudiados

    Studying the non-thermal lobes of IRAS 16547-4247 through a multi-wavelength approach

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    In recent years, massive protostars have turned out to be a possible population of high-energy emitters. Among the best candidates is IRAS 16547-4247, a protostar that presents a powerful outflow with clear signatures of interaction with its environment. This source has been revealed to be a potential high-energy source because it displays non-thermal radio emission of synchrotron origin, which is evidence of relativistic particles. To improve our understanding of IRAS 16547-4247 as a high-energy source, we analyzed XMM-Newton archival data and found that IRAS 16547-4247 is a hard X-ray source. We discuss these results in the context of a refined one-zone model and previous radio observations. From our study we find that it may be difficult to explain the X-ray emission as non-thermal radiation coming from the interaction region, but it might be produced by thermal Bremsstrahlung (plus photo-electric absorption) by a fast shock at the jet end. In the high-energy range, the source might be detectable by the present generation of Cherenkov telescopes, and may eventually be detected by Fermi in the GeV range

    Implications of global pricing policies on access to innovative drugs: : the case of trastuzumab in seven Latin American countries

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    Background: Differential pricing, based on countries’ purchasing power, is recommended by the WHO to secure affordable medicines. However, in developing countries innovative drugs often have similar or even higher prices than in high-income countries. We evaluated the potential implications of trastuzumab global pricing policies in terms of cost-effectiveness (CE), coverage and accessibility for patients with breast cancer in Latin America (LA). Methods: A Markov model was designed to estimate life years (LYs), quality-adjusted life years (QALYs) and costs from a health care perspective. To better fit local cancer prognosis, a base case scenario using transition probabilities from clinical trials was complemented with two alternative scenarios with transition probabilities adjusted to reflect breast cancer epidemiology in each country. Findings: Incremental discounted benefits ranged from 0.87 to 1.00 LY and 0.51 to 0.60 QALY and incremental CE ratios from USD 42,104 to USD 110,283 per QALY (2012 US dollars), equivalent to 3.6 gross domestic product per capita (GDPPC) per QALY in Uruguay and to 35.5 GDPPC in Bolivia. Probabilistic sensitivity analysis showed 0% probability that trastuzumab is CE if the willingness-to-pay (WTP) threshold is one GDPPC per QALY, and remained so at three GDPPC threshold except for Chile and Uruguay (4.3% and 26.6% respectively). Trastuzumab price would need to decrease between 69.6% to 94.9% to became CE in LA. Interpretation: Although CE in other settings, trastuzumab was not CE in LA. The use of health technology assessment to prioritize resource allocation and support price negotiations is critical to making innovative drugs available and affordable in developing countries

    Methanol maps of low-mass protostellar systems: the Serpens Molecular Core

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    Observations of Serpens have been performed at the JCMT using Harp-B. Maps over a 4.5'x5.4' region were made in a frequency window around 338 GHz, covering the 7-6 transitions of methanol. Emission is extended over each source, following the column density of H2 but showing up also particularly strongly around outflows. The rotational temperature is low, 15-20 K, and does not vary with position within each source. The abundance is typically 10^-9 - 10^-8 with respect to H2 in the outer envelope, whereas "jumps" by factors of up to 10^2 -10^3 inside the region where the dust temperature exceeds 100 K are not excluded. A factor of up to ~ 10^3 enhancement is seen in outflow gas. In one object, SMM4, the ice abundance has been measured to be ~ 3x10^-5 with respect to H2 in the outer envelope, i.e., a factor of 10^3 larger than the gas-phase abundance. Comparison with C18O J=3-2 emission shows that strong CO depletion leads to a high gas-phase abundance of CH3OH not just for the Serpens sources, but for a larger sample of protostars. The observations illustrate the large-scale, low-level desorption of CH3OH from dust grains, extending out to and beyond 7500 AU from each source, a scenario which is consistent with non-thermal (photo-)desorption from the ice. The observations also illustrate the usefulness of CH3OH as a tracer of energetic input in the form of outflows, where methanol is sputtered from the grain surfaces. Finally, the observations provide further evidence of CH3OH formation through CO hydrogenation proceeding on grain surfaces in low-mass envelopes.Comment: Accepted for publication in A&A
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