621 research outputs found
Signs of strong Na and K absorption in the transmission spectrum of WASP-103b
Context: Transmission spectroscopy has become a prominent tool for
characterizing the atmospheric properties on close-in transiting planets.
Recent observations have revealed a remarkable diversity in exoplanet spectra,
which show absorption signatures of Na, K and , in some cases
partially or fully attenuated by atmospheric aerosols. Aerosols (clouds and
hazes) themselves have been detected in the transmission spectra of several
planets thanks to wavelength-dependent slopes caused by the particles'
scattering properties. Aims: We present an optical 550 - 960 nm transmission
spectrum of the extremely irradiated hot Jupiter WASP-103b, one of the hottest
(2500 K) and most massive (1.5 ) planets yet to be studied with this
technique. WASP-103b orbits its star at a separation of less than 1.2 times the
Roche limit and is predicted to be strongly tidally distorted. Methods: We have
used Gemini/GMOS to obtain multi-object spectroscopy hroughout three transits
of WASP-103b. We used relative spectrophotometry and bin sizes between 20 and 2
nm to infer the planet's transmission spectrum. Results: We find that WASP-103b
shows increased absorption in the cores of the alkali (Na, K) line features. We
do not confirm the presence of any strong scattering slope as previously
suggested, pointing towards a clear atmosphere for the highly irradiated,
massive exoplanet WASP-103b. We constrain the upper boundary of any potential
cloud deck to reside at pressure levels above 0.01 bar. This finding is in line
with previous studies on cloud occurrence on exoplanets which find that clouds
dominate the transmission spectra of cool, low surface gravity planets while
hot, high surface gravity planets are either cloud-free, or possess clouds
located below the altitudes probed by transmission spectra.Comment: Accepted for publication in A&
Cryogenic Pressure Calibration Facility Using a Cold Force Reference
Presently various commercial cryogenic pressure sensors are being investigated for installation in the LHC collider, they will eventually be used to assess that the magnets are fully immersed in liquid and to monitor fast pressure transients. In the framework of this selection procedure a cryogenic pressue calibration facility has been designed and built; it is based on a cryogenic primary pressure reference made of a bellows that converts the pressure into a force measurement. For that a shaft transfers this force to a precision force transducer at room temperature. Knowing the liquid bath pessure and the surface area of the bellows the pressure applied to the transducers under calibration is calculated; corrections due to thermal contraction are introduced. To avoid loss of force in the bellows wall its length is maintained constant; a cold capacitive displacement sensor measures this. The calibration temperature covers 1.5 K to 4.2 K and the pressure 0 to 20 bar. In contrast with more classical techniques that refer to a pressure reference at room temperature, the method presented in this paper avoid errors due to the uncertainty on the hydrostatic head calculation, to thermoacoustic oscillations and to pressure variation caused by temperature drift along the sensing capillary
Young planets under extreme UV irradiation. I. Upper atmosphere modelling of the young exoplanet K2-33b
The K2-33 planetary system hosts one transiting ~5 R_E planet orbiting the
young M-type host star. The planet's mass is still unknown, with an estimated
upper limit of 5.4 M_J. The extreme youth of the system (<20 Myr) gives the
unprecedented opportunity to study the earliest phases of planetary evolution,
at a stage when the planet is exposed to an extremely high level of high-energy
radiation emitted by the host star. We perform a series of 1D hydrodynamic
simulations of the planet's upper atmosphere considering a range of possible
planetary masses, from 2 to 40 M_E, and equilibrium temperatures, from 850 to
1300 K, to account for internal heating as a result of contraction. We obtain
temperature profiles mostly controlled by the planet's mass, while the
equilibrium temperature has a secondary effect. For planetary masses below 7-10
M_E, the atmosphere is subject to extremely high escape rates, driven by the
planet's weak gravity and high thermal energy, which increase with decreasing
mass and/or increasing temperature. For higher masses, the escape is instead
driven by the absorption of the high-energy stellar radiation. A rough
comparison of the timescales for complete atmospheric escape and age of the
system indicates that the planet is more massive than 10 M_E.Comment: 11 pages, 7 figure
- A tool for multiband light curve modeling of planetary transits and stellar spots
Several studies have shown that stellar activity features, such as occulted
and non-occulted starspots, can affect the measurement of transit parameters
biasing studies of transit timing variations and transmission spectra. We
present , which we designed to model multiband transit
light curves showing starspot anomalies, inferring both transit and spot
parameters. The code follows a pixellation approach to model the star with its
corresponding limb darkening, spots, and transiting planet on a two dimensional
Cartesian coordinate grid. We combine with an MCMC
framework to study and derive exoplanet transmission spectra, which provides
statistically robust values for the physical properties and uncertainties of a
transiting star-planet system. We validate 's performance
by analyzing eleven synthetic light curves of four different star-planet
systems and 20 transit light curves of the well-studied WASP-41b system. We
also investigate the impact of starspots on transit parameters and derive
wavelength dependent transit depth values for WASP-41b covering a range of
6200-9200 , indicating a flat transmission spectrum.Comment: 17 pages, 22 figures; accepted for publication in Astronomy &
Astrophysic
A grid of upper atmosphere models for 1--40 MEARTH planets: application to CoRoT-7 b and HD219134 b,c
There is growing observational and theoretical evidence suggesting that
atmospheric escape is a key driver of planetary evolution. Commonly, planetary
evolution models employ simple analytic formulae (e.g., energy limited escape)
that are often inaccurate, and more detailed physical models of atmospheric
loss usually only give snapshots of an atmosphere's structure and are difficult
to use for evolutionary studies. To overcome this problem, we upgrade and
employ an already existing upper atmosphere hydrodynamic code to produce a
large grid of about 7000 models covering planets with masses 1 - 39 Earth mass
with hydrogen-dominated atmospheres and orbiting late-type stars. The modeled
planets have equilibrium temperatures ranging between 300 and 2000 K. For each
considered stellar mass, we account for three different values of the
high-energy stellar flux (i.e., low, moderate, and high activity). For each
computed model, we derive the atmospheric temperature, number density, bulk
velocity, X-ray and EUV (XUV) volume heating rates, and abundance of the
considered species as a function of distance from the planetary center. From
these quantities, we estimate the positions of the maximum dissociation and
ionisation, the mass-loss rate, and the effective radius of the XUV absorption.
We show that our results are in good agreement with previously published
studies employing similar codes. We further present an interpolation routine
capable to extract the modelling output parameters for any planet lying within
the grid boundaries. We use the grid to identify the connection between the
system parameters and the resulting atmospheric properties. We finally apply
the grid and the interpolation routine to estimate atmospheric evolutionary
tracks for the close-in, high-density planets CoRoT-7 b and HD219134 b,c...Comment: 21 pages, 4 Tables, 15 Figure
The international right to health: what does it mean in legal practice and how can it affect priority setting for universal health coverage?
The international right to health is enshrined in national and international law. In a growing number of cases, individuals denied access to high-cost medicines and technologies under universal coverage systems have turned to the courts to challenge the denial of access as against their right to health. In some instances, patients seek access to medicines, services, or technologies that they would have access to under universal coverage if not for government, health system, or service delivery shortfalls. In others, patients seek access to medicines, services, or technologies that have not been included or that have been explicitly denied for coverage due to prioritization. In the former, judicialization of the right to health is critical to ensure patients access to the technologies or services to which they are entitled. In the latter, courts may grant patients access to medicines not covered as a result of explicit priority setting to allocate finite resources. By doing so, courts may give priority to those with the means and incentive to turn to the courts, at the expense of the maximization of equity- and population-based health. Evidence-based, informed decision-making processes could ensure that the most clinically and cost-effective products aligning with social value judgments are prioritized. Governments should be equipped to engage in and defend rational priority setting, and the priority setting process and institutions involved should be held accountable through an opportunity for appeal and judicial review. As a result, the courts could place greater reliance on the government's coverage choices, and the population's health could be most equitably distributed
Process Automation of a 600 A HTS Current Lead Cryogenic Test Facility Using a Field Network with Smart Instrumentation
Intervención Psicosocial en el contexto educativo en la unidad educativa Municipal Carlos Lozano y Lozano j.m. “sede Tulipana y Potosí j.m.”
Imágenes, tablas, anexosLa psicología social tiene como objeto el estudio del individuo con diferentes grupos siendo esta una ciencia interdisciplinaria y emocional. A raíz de esto nace el interés de realizar un trabajo conjunto, de la psicología social con el contexto educativo ya que permite involucrar al estudiante, padres y docentes en un trabajo individual y grupal con el objetivo de mejorar la calidad educativa de cada estudiante. Como hemos venido señalando, el hecho de que consideremos que el desarrollo de los niños es un proceso socialmente y culturalmente mediatizado, nos obliga a considerar la importancia de los contextos, fundamentalmente de la familia y la escuela, donde este crecimiento personal se hace una realidad. En estos contextos, tal como lo hemos puesto de manifiesto, los niños asumen el rol, establecen interacciones y participan de patrones de conductas cada vez más complejas, de manera que van incorporando poco a poco los elementos propios de su cultura.
En la medida en que ambos contextos comparten funciones educativas (la socialización de determinados valores; la promoción de las capacidades cognitivas, motrices, de equilibrio personal, de relación interpersonal y de inserción social; el cuidado y bienestar físico y psíquico) en la medida que cada uno puede potenciar la actuación del otro, corresponde en buscar aquello en que se pueda colaborar mas que enfatizar en los aspectos en que se discrepa. Es tan compleja la tarea, que lo que conviene es no complicarla más, sino hacerla más sencilla y gratificante.
Desde una perspectiva de colaboración mutua, que pasa por la confianza y el conocimiento, es posible realizar lo que es necesario hacer: asegurar que los dos contextos de desarrollo más importantes en los primeros años de vida de una persona puedan compartir criterios educativos que facilitan el crecimiento armónico de los niños.
De acuerdo con esto se tiene como propuesta realizar una intervención psicosocial en el contexto educativo en la UNIDAD EDUCATIVA MUNICIPAL CARLOS LOZANO Y LOZANO jornada mañana con el fin de identificar los aspectos que generan déficit de atención, agresividad y bajo rendimiento académico. Para lograr esto se hará un seguimiento de cada caso identificado y se trabajara en el mejoramiento del mismo.
Esto se realizara a través de una orientación y asesoramiento de forma preventiva en cada caso. Sin olvidar que se trabajara con niños de diferentes edades, que oscilan entre los cinco (5) años y doce (12) años de edad, las intervenciones y los respectivos talleres se harán de gran variedad y entendimiento sin perder su importancia y verdadero objetivo de lograr que cada estudiante con dificultad o bajo rendimiento académico logre tener una mejor adquisición de su conocimiento. Para que así nuestra sociedad tenga cada día nuevos talentos y una excelente educación.No Abstrac
Oxidación catalítica heterogénea de R-(+)-limoneno sobre catalizadores tipo Jacobsen
The development of heterogeneous catalytic processes is highly desirable in order to overcome somedrawbacks of homogeneous catalysts, such as the separation and recycling of these catalysts. In this work,we report that Jacobsen type catalysts are efficient and selective for the oxidation of R-(+)-limonene to itscorresponding diepoxides using in situ generated dimethyldioxirane (DMD) as oxidant. It was demonstratedthat the solid NaHCO3 addition to the initial reaction mixture, improves the catalytic activity. Additionally,catalyst samples can be recovered and reused at least twice without significant loss of its initial catalyticactivity.El desarrollo de procesos catalíticos heterogéneos es muy deseable dado que se pueden superar las dificultades que presentan los catalizadores homogéneos, tales como la separación y el reciclado de estos catalizadores. En este trabajo, reportamos que los catalizadores tipo Jacobsen son eficientes y selectivos
para la oxidación de R-(+)-limoneno a sus correspondientes diepóxidos cuando dimetildioxirano generado in situ es utilizado como agente oxidante. Se demostró que la adición de NaHCO3 sólido, al inicio de la reacción, mejora la actividad catalítica. Además, el catalizador puede ser recuperado y reutilizado al menos
dos veces sin pérdida significativa de su actividad catalítica inicial.Fil: Cubillos Lobo, Jairo Antonio. Universidad Pedagogica y Tecnologica de Colombia. Facultad de Ciencias. Escuela de Quimica; ColombiaFil: Romanelli, Gustavo Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas; ArgentinaFil: Paez Guevara, L. A.. Universidad Pedagogica y Tecnologica de Colombia. Facultad de Ciencias. Escuela de Quimica; Colombi
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