Size of the Vela Pulsar's Radio Emission Region: 500 km

We use interstellar scattering of the Vela pulsar to determine the size of its emission region. From interferometric phase variations on short baselines, we find that radio-wave scattering broadens the source by 3.4+/-0.3 milliarcseconds along the major axis at position angle 81+/-3 degrees. The ratio of minor axis to major axis is 0.51+/-0.03. Comparison of angular and temporal broadening indicates that the scattering material lies in the Vela-X supernova remnant surrounding the pulsar. From the modulation of the pulsar's scintillation on very short baselines, we infer a size of 500 km for the pulsar's emission region. We suggest that radio-wave refraction within the pulsar's magnetosphere may plausibly explain this size.Comment: 14 pages, includes 2 figures. Also available at: http://charm.physics.ucsb.edu:80/people/cgwinn/cgwinn_group/cgwinn_group.htm

HAT-P-44b, HAT-P-45b, and HAT-P-46b: Three Transiting Hot Jupiters in Possible Multi-Planet Systems

We report the discovery by the HATNet survey of three new transiting extrasolar planets orbiting moderately bright (V=13.2, 12.8 and 11.9) stars. The planets have orbital periods of 4.3012, 3.1290, and 4.4631 days, masses of 0.39, 0.89, and 0.49 Mjup, and radii of 1.28, 1.43, and 1.28 Rjup. The stellar hosts have masses of 0.94, 1.26, and 1.28 Msun. Each system shows significant systematic variations in its residual radial velocities indicating the possible presence of additional components. Based on its Bayesian evidence, the preferred model for HAT-P-44 consists of two planets, including the transiting component, with the outer planet having a period of 220 d and a minimum mass of 1.6 Mjup. Due to aliasing we cannot rule out an alternative solution for the outer planet having a period of 438 d and a minimum mass of 3.7 Mjup. For HAT-P-45 at present there is not enough data to justify the additional free parameters included in a multi-planet model, in this case a single-planet solution is preferred, but the required jitter of 22.5 +- 6.3 m/s is relatively high for a star of this type. For HAT-P-46 the preferred solution includes a second planet having a period of 78 d and a minimum mass of 2.0 Mjup, however the preference for this model over a single-planet model is not very strong. While substantial uncertainties remain as to the presence and/or properties of the outer planetary companions in these systems, the inner transiting planets are well characterized with measured properties that are fairly robust against changes in the assumed models for the outer planets. Continued RV monitoring is necessary to fully characterize these three planetary systems, the properties of which may have important implications for understanding the formation of hot Jupiters.Comment: 21 pages, 10 figures, 14 tables, submitted to A

SHORE EROSION BETWEEN ARBOLETES AND PUNTA SAN BERNARDO, CARIBBEAN COAST OF COLOMBIA

  Las morfología actual y el inventario de cambios de la línea de costa (1938-2005) del litoral Arboletes-Punta San Ber­nardo evidencian su carácter fuertemente erosional, caracterizado a lo largo de su mayor longitud (160 de 180km) por la desaparición/retroceso de numerosas playas y la erosión/inundación consecuente de las terrazas litorales y/o pantanos de manglar adyacentes. En términos generales, el litoral Arboletes-Punta San Bernardo retrocedió entre 30 y 100m durante las siete últimas décadas, a tasas entre 0.5 y 1.5 m/año, superadas en varios sectores críticos (Arboletes-Punta Brava) en los cuales las magnitudes de la erosión fueron del orden de los 900-1.500m a velocidades de 70 m/año durante 1960-1975. La erosión litoral en la zona resulta tanto de procesos marinos como subaéreos, y de la combinación de factores geológicos (neotectonismo/diapirismo de lodos, pocos aportes arenosos, ascenso relativo del nivel del mar, características geotécnicas pobres de las rocas) y antrópicos -minería intensiva de arenas de playas y ríos, usos diversos sin manejo de aguas lluvias y residuales, efectos de es polones y obras de defensa. La defnición precisa de estos factores es necesaria para planifcar el desarrollo litoral considerando aspectos como el ascenso futuro del nivel del mar asociado al Cambio Climático Global.   Palabras clave: Colombia, Costa Caribe, erosión de playas, erosión de acantilados, espolones.          The present morphology and the inventory of the historical shoreline changes (1938-2005) between Arboletes and Punta San Bernardo evidenced a strong erosional trend along 160 of its 180km total-length, resulting in the disparition/retreat of numerous beaches, followed by the consequent fooding/erosion of the adjacent littoral terraces and mangrove swamps. In general terms, the littoral Arboletes-Punta San Bernardo retreated 30 to 100m during the last seven decades, at rates between 0.5 and 1.5 m/year; maximum values were found at some critical sectors in the Arboletes-Punta Brava shore segment where magnitudes of coastline retreat were in the order of 900-1.500m at erosion rates up to 70 m/year during the period 1960-1975. Shore erosion in the study area results both from marine and subaerial processes and the combina-tion of geological factors (neotectonism and effects of mud diapirism, minor stocks of sands, relative sea level rise, poor geotechnical characteristics of cliff´s rocks) and human interventions (intensive sand mining from beaches and rivers, land uses with inadequate water management practices, adverse effects of groins and other rigid structures of defense). The precise defnition of each one of these factors is necessary for planning the development of the area considering the future sea level rise associated to the Global Climate Change.   Key words: Colombia, Caribbean Coast, beach erosion, cliff erosion, groins &nbsp

EROSIÓN LITORAL ENTRE ARBOLETES Y PUNTA SAN BERNARDO, COSTA CARIBE COLOMBIANA

    The present morphology and the inventory of the historical shoreline changes (1938-2005) between Arboletes and Punta San Bernardo evidenced a strong erosional trend along 160 of its 180km total-length, resulting in the disparition/retreat of numerous beaches, followed by the consequent fooding/erosion of the adjacent littoral terraces and mangrove swamps. In general terms, the littoral Arboletes-Punta San Bernardo retreated 30 to 100m during the last seven decades, at rates between 0.5 and 1.5 m/year; maximum values were found at some critical sectors in the Arboletes-Punta Brava shore segment where magnitudes of coastline retreat were in the order of 900-1.500m at erosion rates up to 70 m/year during the period 1960-1975. Shore erosion in the study area results both from marine and subaerial processes and the combina-tion of geological factors (neotectonism and effects of mud diapirism, minor stocks of sands, relative sea level rise, poor geotechnical characteristics of cliff´s rocks) and human interventions (intensive sand mining from beaches and rivers, land uses with inadequate water management practices, adverse effects of groins and other rigid structures of defense). The precise defnition of each one of these factors is necessary for planning the development of the area considering the future sea level rise associated to the Global Climate Change.   Key words: Colombia, Caribbean Coast, beach erosion, cliff erosion, groins    Las morfología actual y el inventario de cambios de la línea de costa (1938-2005) del litoral Arboletes-Punta San Ber­nardo evidencian su carácter fuertemente erosional, caracterizado a lo largo de su mayor longitud (160 de 180km) por la desaparición/retroceso de numerosas playas y la erosión/inundación consecuente de las terrazas litorales y/o pantanos de manglar adyacentes. En términos generales, el litoral Arboletes-Punta San Bernardo retrocedió entre 30 y 100m durante las siete últimas décadas, a tasas entre 0.5 y 1.5 m/año, superadas en varios sectores críticos (Arboletes-Punta Brava) en los cuales las magnitudes de la erosión fueron del orden de los 900-1.500m a velocidades de 70 m/año durante 1960-1975. La erosión litoral en la zona resulta tanto de procesos marinos como subaéreos, y de la combinación de factores geológicos (neotectonismo/diapirismo de lodos, pocos aportes arenosos, ascenso relativo del nivel del mar, características geotécnicas pobres de las rocas) y antrópicos -minería intensiva de arenas de playas y ríos, usos diversos sin manejo de aguas lluvias y residuales, efectos de es polones y obras de defensa. La defnición precisa de estos factores es necesaria para planifcar el desarrollo litoral considerando aspectos como el ascenso futuro del nivel del mar asociado al Cambio Climático Global.   Palabras clave: Colombia, Costa Caribe, erosión de playas, erosión de acantilados, espolones.     &nbsp

Etiology of chronic urticaria: the Ecuadorian experience

Background: The purpose of this study was to identify chronic urticaria (CU) etiologies and treatment modalities in Ecuador. We propose that the sample distribution fits the expected one, and that there is an association between the etiology and its treatment. Methods: We performed a retrospective study involving 112 patients diagnosed with CU using a Checklist for a complete chronic urticaria medical history. Demographic and clinical variables were collected. The etiology of CU was classified using the EAACI/GA2LEN/EDF/WAO guideline. Descriptive analyses were performed for demographical and clinical variables. Chi square tests were applied to analyze the fit of distribution and the independence of variables. P values less than 0.05 were considered significant. Results: Among all the patients, 76.8% were diagnosed with chronic spontaneous urticaria (CSU), of which 22.3% had a known etiology or possible exacerbating condition. Food allergy was identified as the most common accompanying condition in patients with CSU (10.7%) (p < 0.01).. On the other hand, 23.2% inducible urticarias (CIndU) were indentified; dermographism was the most common (10.7%) (p < 0.01). Regarding treatment regimens, sg-H1-antihistamines alone represented the highest proportion (44.6%). The combination of any H1-antihistamine plus other drug was a close second (42.0%) (p < 0.01). Almost 48% of CSUs of unknown etiology were treated with any antihistamine plus another drug. In patients with known etiology, sg-antihistamines alone (44.0%) was the most common management. In addition, 53.8% of CIndUs were treated with sg-antihistamines alone. Though, these associations were not statistically significant. Conclusion: CSU is the most frequent subtype of CU. Modern non-sedating antihistamines in licensed doses are the drug of choice. Nevertheless, a great proportion of patients require the addition of another type of medication

The K2-ESPRINT Project. I. Discovery of the Disintegrating Rocky Planet K2-22b with a Cometary Head and Leading Tail

We present the discovery of a transiting exoplanet candidate in the K2 Field-1 with an orbital period of 9.1457 hr: K2-22b. The highly variable transit depths, ranging from $\sim$0\% to 1.3\%, are suggestive of a planet that is disintegrating via the emission of dusty effluents. We characterize the host star as an M-dwarf with $T_{\rm eff} \simeq 3800$ K. We have obtained ground-based transit measurements with several 1-m class telescopes and with the GTC. These observations (1) improve the transit ephemeris; (2) confirm the variable nature of the transit depths; (3) indicate variations in the transit shapes; and (4) demonstrate clearly that at least on one occasion the transit depths were significantly wavelength dependent. The latter three effects tend to indicate extinction of starlight by dust rather than by any combination of solid bodies. The K2 observations yield a folded light curve with lower time resolution but with substantially better statistical precision compared with the ground-based observations. We detect a significant "bump" just after the transit egress, and a less significant bump just prior to transit ingress. We interpret these bumps in the context of a planet that is not only likely streaming a dust tail behind it, but also has a more prominent leading dust trail that precedes it. This effect is modeled in terms of dust grains that can escape to beyond the planet's Hill sphere and effectively undergo `Roche lobe overflow,' even though the planet's surface is likely underfilling its Roche lobe by a factor of 2.Comment: 22 pages, 16 figures. Final version accepted to Ap

Accretion of Planetary Material onto Host Stars

Accretion of planetary material onto host stars may occur throughout a star's life. Especially prone to accretion, extrasolar planets in short-period orbits, while relatively rare, constitute a significant fraction of the known population, and these planets are subject to dynamical and atmospheric influences that can drive significant mass loss. Theoretical models frame expectations regarding the rates and extent of this planetary accretion. For instance, tidal interactions between planets and stars may drive complete orbital decay during the main sequence. Many planets that survive their stars' main sequence lifetime will still be engulfed when the host stars become red giant stars. There is some observational evidence supporting these predictions, such as a dearth of close-in planets around fast stellar rotators, which is consistent with tidal spin-up and planet accretion. There remains no clear chemical evidence for pollution of the atmospheres of main sequence or red giant stars by planetary materials, but a wealth of evidence points to active accretion by white dwarfs. In this article, we review the current understanding of accretion of planetary material, from the pre- to the post-main sequence and beyond. The review begins with the astrophysical framework for that process and then considers accretion during various phases of a host star's life, during which the details of accretion vary, and the observational evidence for accretion during these phases.Comment: 18 pages, 5 figures (with some redacted), invited revie

Individual differences in puberty onset in girls: Bayesian estimation of heritabilities and genetic correlations

We report heritabilities for individual differences in female pubertal development at the age of 12. Tanner data on breast and pubic hair development in girls and data on menarche were obtained from a total of 184 pairs of monozygotic and dizygotic twins. Genetic correlations were estimated to determine to what extent the same genes are involved in different aspects of physical development in puberty. A Bayesian estimation approach was taken, using Markovchain Monte Carlo simulation to estimate model parameters. All three phenotypes were to a significant extent heritable and showed high genetic correlations, suggesting that a common set of genes is involved in the timing of puberty in general. However, gonadarche (menarche and breast development) and adrenarche (pubic hair) are affected by different environmental factors, which does not support the three phenotypes to be regarded as indicators of a unitary physiological factor. © 2006 Springer Science+Business Media, Inc