"Secular Light Curve of Comet 103P/Hartley 2, Target of the EPOXI Mission"

In support of the EPOXI mission, we have compiled the secular light curve (SLC) of comet 103P/Hartley 2, the next target of EPOXI. a) Of the order of 30 photometric parameters are measured, over 20 of them new. The turn on point of activity is -4.2 +/- 0.1 AU from the Sun, which corresponds to -400 +/- 40 d before perihelion. The total active time is TACTIVE= 1484 +/- 43 d. b) 103P is a young dwarf comet, young because it has a photometric age P-AGE(1,1) = 15 +/- 2 cy (comet years), and dwarf because its diameter is DEFFE = 1.14 +/- 0.16 km. c) The nucleus is very active, and the amplitude of the SLC is ASEC= 10.8 +/- 0.1 mag in 1997. This comet is as active as 1P/Halley, but much smaller. d) After remaining active up to aphelion, the comet spills-over its activity into the next orbit. e) Two linear laws change slope at a break point located at RBP = -1.20 +/- 0.1 AU before perihelion, and magnitude mBP = 9.4 +/- 0.1. Sublimation is not controlled by water ice. The controlling substance may be CO or CO2 ice. CO2 has been detected spectroscopically. f) The water budget of this comet is calculated. The comet expends 1.88 10^10 kg of water per apparition. A new water-budget age is defined and it is found that WB-AGE = 19 cy vs WB-AGE = 0.65 cy for 1P/Halley and 28 cy for 9P. g) The values of Af{\rho} are calculated on two dates and we find dust production rates of 106 and 37 kg/s. h) The thickness of the layer lost per apparition is calculated, and we find {\Delta}r = 39 m where r is the radius. Since the radius of this comet is r = 570 m, it is found that at the present rate the comet may disappear in only 17 revolutions (~109 y). i) All comets visited by spacecraft are young objects. 103P follows the same trend. It is expected that the surface morphology that will be found in future EPOXI images should be very similar to that of previous comets.Comment: Accepted for publication in Planetary and Space Science, 41 pages, 11 figures, 2 tables, set your printer to colo

Numerical simulation of group combustion of pulverized coal

A mathematical model for the group combustion of pulverized coal particles was developed in a previous work. It includes the Lagrangian description of the dehumidification, devolatilization and char gasification reactions of the coal particles in the homogenized gaseous environment resulting from the three fuels, CO, H2 and volatiles, supplied by the gasification of the particles and their simultaneous group combustion by the gas phase oxidation reactions, which are considered to be very fast. This model is complemented here with an analysis of the particle dynamics, determined principally by the effects of aerodynamic drag and gravity, and its dispersion based on a stochastic model. It is also extended to include two other simpler models for the gasification of the particles: the first one for particles small enough to extinguish the surrounding diffusion flames, and a second one for particles with small ash content when the porous shell of ashes remaining after gasification of the char, non structurally stable, is disrupted. As an example of the applicability of the models, they are used in the numerical simulation of an experiment of a non-swirling pulverized coal jet with a nearly stagnant air at ambient temperature, with an initial region of interaction with a small annular methane flame. Computational algorithms for solving the different stages undergone by a coal particle during its combustion are proposed. For the partial differential equations modeling the gas phase, a second order finite element method combined with a semi-Lagrangian characteristics method are used. The results obtained with the three versions of the model are compared among them and show how the first of the simpler models fits better the experimental results

Responses of soil hexapod communities to warming are mediated by microbial carbon and nitrogen in a subarctic grassland

Altres ajuts: acords transformatius de la UABWarming in subarctic ecosystems will be two-fold higher compared to lower latitudes under current climate change projections. While the effects of warming in northern ecosystems on plants and microorganisms have been extensively studied, the responses of soil fauna have received much less attention, despite their important role in regulating key soil processes. We analyzed the response of soil hexapod communities in a subarctic grassland exposed to a natural geothermal gradient in Iceland with increases of +3 and + 6 °C above ambient temperature. We characterized hexapod communities using environmental DNA (eDNA) metabarcoding. We analyzed the amounts of microbial carbon (Cmic), microbial N (Nmic), dissolved organic C (DOC) and dissolved organic N (DON) and then assessed whether these variables could help to account for the compositional dissimilarity of ground hexapod communities across temperatures. The increases in soil temperature did lead to changes in the composition of hexapod communities. The compositional differences caused by +6 °C plots were correlated with a decrease in Cmic and Nmic, soil DOC and DON. Our results highlight the response of soil hexapods to warming, and their interaction with microbial biomass ultimately correlated with changes in the availabilities of soil C and N

El almuerzo sobre la hierba, un puente hacia la modernidad

El análisis de Almuerzo sobre la hierba de Manet ha evidenciado la importancia de la pintura en la historia del arte contemporáneo, por su influencia directa en las principales corrientes   pictóricas   vanguardistas.   Elementos   como   la disposición de personajes y objetos, el uso del color, la amalgama de formas, la vestimenta de las figuras secundarias, así como la desnudez de la protagonista cuya imagen corriente contrasta con el romanticismo pictórico dominante. El homenaje que hace al cuerpo femenino lo convierten en figura rompedora y uno de los primeros representantes del realismo circundante en una época en declive. La obra muestra la relación pragmática de lo clásico con lo moderno porque simboliza la propia realidad del autor insertada en el medio. El reflejo de su inconformidad con lo establecido lo catapulta como referente de un modelo de arte atrevido, una propuesta pictórica respaldada por las teorías y técnicas del arte renacentista y barroco pero transformada por su identidad y visión futurista. Palabras  clave:  análisis  hermenéutico;  ruptura;  modernismo; impresionismo. Abstract  Analysis  of  lunch  on  the  grass  of  Manet  highlighted  the importance of the painting in the history of contemporary art, for its direct influence on the mainstream avant-garde pictorial. The elements as the disposal of characters and objects, the use of the color, the amalgam of forms, the clothing of them figures secondary, as well as the nudity of the protagonist whose image current contrasts with the romanticism pictorial dominant. They become the homage that makes the female body ground-breaking figure and one of the first representatives of the surrounding realism at a time declining. The work shows the relationship pragmatic of it classic with it modern because symbolizes the own reality of the author inserted in the middle. The reflection of their dissatisfaction with the established catapults him as reference for a model of daring art, a pictorial proposal backed by the theories and techniques of Renaissance and Baroque art but transformed by their identity and futuristic vision.  Keywords:    hermeneutic    analysis;    rupture;    modernism; impressionism

The QUEST RR Lyrae Survey: Confirmation of the Clump at 50 kpc and Other Over-Densities in the Outer Halo

We have measured the periods and light curves of 148 RR Lyrae variables from V=13.5 to 19.7 from the first 100 sq. degrees of the QUEST RR Lyrae survey. Approximately 55% of these stars belong to the clump of stars detected earlier by the Sloan Digital Sky Survey. According to our measurements, this feature has ~10 times the background density of halo stars, spans at least 37.5 deg by 3.5 deg in right ascension and declination (>=30 by >=3 kpc), lies ~50 kpc from the Sun, and has a depth along the line of sight of ~5 kpc (1 sigma). These properties are consistent with the recent models that suggest it is a tidal stream from the Sgr dSph galaxy. The mean period of the type ab variables, 0.58 d, is also consistent. In addition, we have found two smaller over-densities in the halo, one of which may be related to the globular cluster Pal 5.Comment: 12 pages (including 4 figures). Accepted for publication in the ApJ Letter

Aplicación de mezclas asfálticas tibias en la ciudad autónoma de Buenos Aires : Tramos experimentales

Las mezclas asfálticas tibias son elaboradas, colocadas y compactadas a temperaturas inferiores a las convencionales. La irrupción de las mismas en el escenario vial responde a una necesidad de dar respuesta a reclamos ambientales, y a la búsqueda de procesos de pavimentación eficientes desde todo punto de vista. En efecto, las mezclas tibias reducen considerablemente la emisión de CO2 en el proceso de producción con los beneficios que esta medida representa. Los principales avances, corresponden a experiencias llevadas a cabo en Europa y EEUU. En la Argentina y sobre la base de los trabajos que se han efectuado en el presente año, este tipo de mezcla seguramente empezará a utilizarse rápidamente en diferentes obras viales en el país. La importante disminución en las temperaturas de elaboración y colocación de estas mezclas, permite reducir los costos de energía y paralelamente las emisiones a la atmósfera. Asimismo existen otras interesantes ventajas, entre las que se destacan: la disminución del envejecimiento o rigidización prematura del asfalto por la planta asfáltica, la reducción del riesgo de segregación térmica, la disminución de las temporadas de veda en climas fríos, la mejora en los tiempos para la compactación del material, el mayor empleo de RAP en mezclas recicladas, la mejora de las condiciones de trabajo, etc. A través del Laboratorio de Pavimentos e Ingeniería Vial-LaPIV-, la Facultad de Ingeniería realizó un acuerdo de servicio técnico con la empresa YPF, siendo el objetivo del mismo: Diseñar un plan de trabajo para llevar adelante las etapas de desarrollo, ejecución (controles sobre los materiales y sobre las emisiones: CO, NOx, SO2, CO2) y el seguimiento de tramos experimentales de mezclas asfálticas de bajas emisiones. Identificar y definir la ejecución de tramos experimentales en lugares representativos del país. Seguimiento sistemático del comportamiento de los tramos. Elaboración de los reportes correspondientes y difusión de los mismos en foros técnicos de la especialidad. A la fecha se ha ejecutado el primer tramo de prueba con mezclas tibias en la Ciudad Autónoma de Buenos Aires, cuyas características y resultados alcanzados se describen el presente trabajo.Facultad de Ingenierí

Shelves of the Iberian Peninsula and the Balearic Islands (I): Morphology and sediment types

Here we present a synthesis of bedforms and sediment types on the shelves surrounding the Iberian Peninsula and the Balearic Islands, after the integration several pieces of bathymetric, morphological and sedimentological datasets. The Iberian and Balearic shelves are divided into segments according to the largescale margin configuration, fluvial sediment supply and hydrodynamic regime. Their geological settings and large-scale sedimentation patterns place the investigated shelves into two broad categories: abrupt, steep and narrow sediment-starved shelves, illustrated by the Cantabrian shelf, and gentle, smooth and wide sediment- fed shelves, such as the shelves off some major flivial systems. An in-depth classification was subsequently attempted, based on morpho-sedimentary types. Under this approach, the Iberian and Balearic shelves can be classified as: (1) storm-dominated shelves, with erosional rocky floors, frequent abrasion surfaces and coarse-grained sediments; (2) current-dominated shelves, showing a good equilibriumbetween sediment fluxes and coastal and shallow ocean circulation, with laterally extensive muddy belts; (3) sediment supply-dominated shelves, where extensive subaqueous deltas develop off river mouths; and (4) wave-dominated shelves that occur off coastal stretches with minor and/or multiple fluvial sediment sources and enhanced littoral current

The quest RR lyrae survey. I. The first catalog

With the 1 m Schmidt telescope of the Llano del Hato Observatory and the QUEST CCD camera, 380 deg 2 of the sky have been surveyed for RR Lyrae variables in a band 2.°3 wide in declination (centered at δ = -1°) and covering right ascensions from 4. h1 to 6. h1 and from 8. h0 to 17. h0. The bright limit (due to CCD saturation) and the faint limit are V∼13.5 and ∼19.7, respectively, which correspond to ∼4 and ∼60 kpc from the Sun. We present a catalog of the positions, amplitudes, mean magnitudes, periods, and light curves of the 498 RR Lyrae variables that have been identified in this region of the sky. The majority of these stars (86%) are new discoveries. The completeness of the survey has been estimated from simulations that model the periods and light curves of real RR Lyrae variables and take into account the pattern of epochs of observation. While the completeness of the survey varies with apparent magnitude and with position, almost everywhere in the surveyed region it is quite high (\u3e80%) for the type ab RR Lyrae variables and between 30% and 90% for the low-amplitude type c variables