Geomorphology and spectrophotometry of Philae's landing site on comet 67P/Churyumov-Gerasimenko

Context. On 12 November 2014 the European mission Rosetta succeeded in delivering a lander, named Philae, on the surface of one of the smallest, low-gravity and most primitive bodies of the solar system, the comet 67P/Churyumov-Gerasimenko (67P). Aims. The aim of this paper is to provide a comprehensive geomorphological and spectrophotometric analysis of Philae's landing site (Agilkia) to give an essential framework for the interpretation of its in situ measurements. Methods. OSIRIS images, coupled with gravitational slopes derived from the 3D shape model based on stereo-photogrammetry were used to interpret the geomorphology of the site. We adopted the Hapke model, using previously derived parameters, to photometrically correct the images in orange filter (649.2 nm). The best approximation to the Hapke model, given by the Akimov parameter-less function, was used to correct the reflectance for the effects of viewing and illumination conditions in the other filters. Spectral analyses on coregistered color cubes were used to retrieve spectrophotometric properties. Results. The landing site shows an average normal albedo of 6.7% in the orange filter with variations of similar to 15% and a global featureless spectrum with an average red spectral slope of 15.2%/100 nm between 480.7 nm (blue filter) and 882.1 nm (near-IR filter). The spatial analysis shows a well-established correlation between the geomorphological units and the photometric characteristics of the surface. In particular, smooth deposits have the highest reflectance a bluer spectrum than the outcropping material across the area. Conclusions. The featureless spectrum and the redness of the material are compatible with the results by other instruments that have suggested an organic composition. The observed small spectral variegation could be due to grain size effects. However, the combination of photometric and spectral variegation suggests that a compositional differentiation is more likely. This might be tentatively interpreted as the effect of the efficient dust-transport processes acting on 67P. High-activity regions might be the original sources for smooth fine-grained materials that then covered Agilkia as a consequence of airfall of residual material. More observations performed by OSIRIS as the comet approaches the Sun would help interpreting the processes that work at shaping the landing site and the overall nucleus.

Factors influencing hurricane evacuation among Hispanic population

The recent hurricanes of Katrina, Rita, and Dolly have brought to light the precarious situation populations place themselves in when they are unprepared to face a storm, or do not follow official orders to evacuate when a destructive hurricane is poised to hit the area. Three counties in southern Texas lie within 60 miles of the Gulf of Mexico, and along the Mexican border. Determining the barriers to hurricane evacuation in this distinct and highly impoverished area of the United States would help aid local, state, and federal agencies to respond more effectively to persons living here.^ The aim of this study was to examine intention to comply with mandatory hurricane evacuation orders among persons living in three counties in South Texas by gender, income, education, acculturation and county of residence. A questionnaire was administered to 3,088 households across the three counties using a two-stage cluster sampling strategy, stratified by all three counties. The door-to-door survey was a 73-item instrument that included demographics, reasons for and against evacuation, and preparedness for a hurricane. Weighted data were used for the analyses.^ Chi-square tests were run to determine whether differences between observed and expected frequencies were statistically significant. A logistic regression model was developed based on that univariate analysis. Results from the logistic regression estimated odds ratios and their 95 percent confidence intervals for the independent variables.^ Logistic regression results indicate that females were less likely than men to follow an evacuation order. Having a higher education meant more likelihood of evacuating. Those respondents with a higher affiliation with Spanish than English were more likely to follow the evacuation orders. Hidalgo County residents were less likely to evacuate than Cameron or Willacy Counties' residents. Local officials need to implement communication efforts specifically tailored for females, residents with less of an affiliation with Spanish, and Hidalgo County residents to ensure their successful evacuation prior to a strong hurricane's landfall.^

Chemistry of sediment profile GeoB4906

Mineralization of organic matter and the subsequent dissolution of calcite were simulated for surface sediments of the upper continental slope off Gabon by using microsensors to measure O2, pH, pCO2 and Ca2+ (in situ), pore-water concentration profiles of NO3-, NH4+, Fe2+, and Mn2+ and SO42- (ex situ), as well as sulfate reduction rates derived from incubation experiments. The transport and reaction model CoTReM was used to simulate the degradation of organic matter by O2, [NO3]-, Fe(OH)3 and [SO4]2-, reoxidation reactions involving Fe2+ and Mn2+, and precipitation of FeS. Model application revealed an overall rate of organic matter mineralization amounting to 50 µmol C cm**-2 yr**-1, of which 77% were due to O2, 17% to [NO3]- and 3% to Fe(OH)3 and 3% to [SO4]2-. The best fit for the pH profile was achieved by adapting three different dissolution rate constants of calcite ranging between 0.01 and 0.5% d-1 and accounting for different calcite phases in the sediment. A reaction order of 4.5 was assumed in the kinetic rate law. A CaCO3 flux to the sediment was estimated to occur at a rate of 42 g m**-2 yr**-1 in the area of equatorial upwelling. The model predicts a redissolution flux of calcite amounting to 36 g m**-2 yr**-1, thus indicating that ~90% of the calcite flux to the sediment is redissolved.

La seducción del continente americano. Simbolismo e ideología en La piedra que crece, de Albert Camus

En el cuento "La piedra que crece" Albert Camus textualiza de manera sugerente, la seducción que el continente americano, en su porción más agreste y natural, adquiere para este pensador de mediados del siglo pasado. Continente y cultura que parecen ofrecer al escritor francés una posible salida a ese universo cerrado, sin horizontes, que postula el Existencialismo. Este cuento se erige como símbolo contenedor de ideas tangenciales a las manifestadas por Camus en el resto de sus escritos. Aquí se advierte una mirada esperanzada acerca del porvenir de la cultura y, en definitiva, de la humanidad que le da sentido, que se contrapone diametralmente con la postura existencialista. Por ello en este trabajo me propongo, por una parte transmitir una impresión de lectura, y por otra, demostrar de qué manera la captación de un espacio-otro, adquiere una dimensión simbólica e ideológica que socava los postulados existenciales en sus raíces más profundas

Los espacios en la literatura

Fil: Castellino, Marta Elena.

Diagnosis del hombre moderno en Minotauroamor de Abelardo Arias

El análisis del discurso en Minotauroamor de Abelardo Arias, permite al lector acceder a una serie de conceptos acerca del hombre y de las realidades que le conciernen: el amor, la amistad, la belleza, el arte, el poder, entre otros. Si bien estos planteos alcanzan a todos los personajes, los mismos son focalizados, especialmente, en relación con los dos protagonistas: el Minotauro y Teseo. De hecho, Abelardo Arias ha declarado que lo que le impulsó a escribir esta novela fue, precisamente, un interrogante vital que lo asediaba: cuál era la verdadera condición del hombre moderno. El escritor mendocino parecía advertir, ya en ese entonces, una marcada degradación de los valores que han sido sostén de nuestra cultura e intenta despertar la conciencia de sus coetáneos a través de estas magníficas páginas. Es por ello que, en el presente trabajo, no sólo nos proponemos demostrar el enorme valor literario de la novela abelardariana y la riqueza de su contenido sino también señalar el vínculo que se establece entre los personajes con el concepto subyacente de “hombre normal". De este modo tratamos de dilucidar de qué modo, en este espacio literario, se proyectan las ideas sustentadas por el reconocido escritor mendocino. Con tal finalidad, se señalan, sucintamente, las coincidencias y modulaciones que se dan entre el mito original y la recreación que de él hace el autor mendocino para centrarnos en el análisis de los fragmentos que tienen como tema sustancial la “diagnosis" del hombre. Para este enfoque tomo en consideración un estudio de Alfonso López Quintás -Diagnosis del hombre actual-, publicado el mismo año de la obra que nos ocupa, y que plantea -desde otro lenguaje-, las mismas inquietudes que advertimos en el autor mendocino.

Los siete locos de Roberto Arlt : un existencialismo avant la lettre

El uso frecuente del discurso abstracto en Los siete locos de Roberto Arlt nos remite a ideas generales que se vinculan con postulados existencialistas. Este trabajo se propone señalar la relación que se establece entre los planteos de Erdosain y algunos conceptos que posteriormente elaborarán filósofos existencialistas como Albert Camus.