Investigating microbial diversity and UV radiation impact at the high-altitude lake Aguas Calientes, Chile

The High-Lakes Project is funded by the NAI and explores the highest perennial volcanic lakes on Earth in the Bolivian and Chilean Andes, including several lakes ∼6,000 m elevation. These lakes represent an opportunity to study the evolution of microbial organisms in relatively shallow waters not providing substantial protection against UV radiation. Aguas Calientes (5,870 m) was investigated (November 2006) and samples of water and sediment collected at 1, 3, 5, and 10 cm depth. An Eldonet UV dosimeter positioned on the shore records UV radiation and temperature, and is logging data year round. A UV SolarLight sensor allowed acquisition of point measurements in all channels at the time of the sampling. UVA, UVB, and PAR peaks between 11:00 am and 1:00 pm reached 7.7 mW/cm2, 48.5 μW/cm2, and 511 W/m 2, respectively. The chemical composition of the water sample was analyzed. DNA was extracted and DGGE analyses with bacterial and archaeal 16S fragments were performed to describe microbial diversity. Antibiotic resistances were established previously in similar environments in Argentine Andean wetlands. In order to determine these resistances in our samples, they were inoculated onto LB and R2A media and onto R2A medium containing either chloramphenicol, ampicillin or tetracycline. Bacterial was higher than archeal cell number determined by RT-PCR in all the samples, reaching maximum total values of 5×105 cell mL-1. DGGE results from these samples and Licancabur summit lake (5,916 m) samples were also compared. Eight antibiotic-resistant Gram negative strains have been isolated with distinct resistance patterns.Fil: Escudero, Lorena. Centro de Investigación Científica y Tecnológica para la Minería; ArgentinaFil: Chong, Guillermo. Centro de Investigación Científica y Tecnológica para la Minería; ArgentinaFil: Demergasso, Cecilia. Universidad Católica de Chile; ChileFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Cabrol, Nathalie A.. Nasa Ames Research Center; Estados UnidosFil: Grin, Edmond. Nasa Ames Research Center; Estados UnidosFil: Minkley Jr., Edwin. University of Carnegie Mellon; Estados UnidosFil: Yu, Youngeob. University of Carnegie Mellon; Estados Unido

Exploring Gusev Crater with spirit: Review of science objectives and testable hypotheses

Gusev Crater was selected as the landing site for the Mars Exploration Rover (MER) Spirit mission. Located at the outlet of Ma'adim Vallis and 250 km south of the volcano Apollinaris Patera, Gusev is an outstanding site to achieve the goals of the MER mission. The crater could have collected sediments from a variety of sources during its 3.9 Ga history, including fluvial, lacustrine, volcanic, glacial, impact, regional and local aeolian, and global air falls. It is a unique site to investigate the past history of water on Mars, climate and geological changes, and the potential habitability of the planet, which are central science objectives of the MER mission. Because of its complex history and potential diversity, Gusev will allow the testing of a large spectrum of hypotheses with the complete suite of MER instruments. Evidence consistent with long-lived lake episodes exist in the landing ellipse area. They might offer a unique opportunity to study, for the first time, Martian aqueous sediments and minerals formed in situ in their geological context. We review the geological history and diversity of the landing site, the science hypotheses that can be tested during the MER mission, and the relevance of Gusev to the MER mission objectives and payload

Soil sedimentology at Gusev Crater from Columbia Memorial Station to Winter Haven

A total of 3140 individual particles were examined in 31 soils along Spirit’s traverse. Their size, shape, and texture were quantified and classified. They represent a unique record of 3 years of sedimentologic exploration from landing to sol 1085 covering the Plains Unit to Winter Haven where Spirit spent the Martian winter of 2006. Samples in the Plains Unit and Columbia Hills appear as reflecting contrasting textural domains. One is heterogeneous, with a continuum of angular-to-round particles of fine sand to pebble sizes that are generally dust covered and locally cemented in place. The second shows the effect of a dominant and ongoing dynamic aeolian process that redistributes a uniform population of medium-size sand. The texture of particles observed in the samples at Gusev Crater results from volcanic, aeolian, impact, and water-related processes

Acadia National Park, The Bowl

A postcard image of an area known as The Bowl, Acadia National Park, near Bar Harbor, Maine.https://digitalcommons.library.umaine.edu/spec_photos/1459/thumbnail.jp

Henri Reverdin, Les exigences de la vie de l'Esprit. Principes et Développement d'une pensée. Préface de Samuel Gagnebin, 1966

Grin Edmond. Henri Reverdin, Les exigences de la vie de l'Esprit. Principes et Développement d'une pensée. Préface de Samuel Gagnebin, 1966. In: Revue d'histoire et de philosophie religieuses, 51e année n°2,1971. pp. 232-233

Charles Secrétan et la philosophie de Schelling

Grin Edmond. Charles Secrétan et la philosophie de Schelling. In: Revue d'histoire et de philosophie religieuses, 5e année n°2, Mars-avril 1925. pp. 155-182

Henri Reverdin, Les exigences de la vie de l'Esprit. Principes et Développement d'une pensée. Préface de Samuel Gagnebin, 1966

Grin Edmond. Henri Reverdin, Les exigences de la vie de l'Esprit. Principes et Développement d'une pensée. Préface de Samuel Gagnebin, 1966. In: Revue d'histoire et de philosophie religieuses, 51e année n°2,1971. pp. 232-233

F. Subilla : La crise de la foi d'Edmond Scherer. Un problème actuel. Lausanne (La Concorde). 1925

Grin Edmond. F. Subilla : La crise de la foi d'Edmond Scherer. Un problème actuel. Lausanne (La Concorde). 1925. In: Revue d'histoire et de philosophie religieuses, 5e année n°6, Novembre-décembre 1925. pp. 596-598