Search results for "Planetary Science"
showing 10 items of 4367 documents
Biocoenosis and induration of freshwaterRivulariastromatolites in a temperate climate
1997
Freshwater Rivularia haematites (D.C.) Agardh and Rivularia biasolettiana Menegh‐ini stromatolites were collected from the Plateau de Langres and Lac d'Annecy (France) and investigated experimentally. In addition to cyanobacteria, the community of organisms consists of Desmococcus (green algae) and many bacteria including Agrobacterium tumefaciens and Pseudomonas diminuta for Rivularia haematites, and Achromobacter group B and Pseudomonas acidovorans for Rivularia biasolettiana. Stromatolite induration is not confined to calcification and may locally exhibit apatite or gypsum crystals, with the latter appearing only in cultures exposed to light. The effect of certain microorganisms of the b…
Discovery of Ca oxalate crystals associated with fungi in moss travertines (Bryoherms, freshwater heterogeneous stromatolites)
1995
Buffered decalcification of live moss and liverwort (Hepaticae) travertines resulted in the release of a large number of organisms (bacteria, cyanobacteria, fungi, eukaryotic algae, and small animals), which constitute an “organic mat”; (also called an algal mat or biofilm). This mat is calcified and commonly has laminations, allowing moss travertines to be considered as stromatolitic structures. After decalcification of 300 samples of travertines (using dilute acetic acid), only 9 released Ca oxalate crystals in the form of needle bundles, spherulites, and tetragonal bipyramidal prisms. These crystalline forms are identical to those found in some phanerophytes and soils. Mycelian filaments…
Continental Construction in Central Asia (IGCP-592): Scientific Results and Meetings in 2012
2013
IGCP-Project #592 (2012-2015) "Continental construction in Central Asia", funded by UNESCO-IUGS, was launched in April 2012. The Project focuses on tectonic and magmatic aspects of formation of continental crust in the Central Asian Orogenic Belt and their comparison with actualistic examples from the western Pacific. This report summarizes related scientific results and meetings. In total, in 2012 the Project organized, and/or participated in the organization of, six international conferences and workshops, three of which were accompanied by training schools for young scientists and special training courses. At the present time, more than 250 scientists from 27 countries expressed their in…
BART: The Czech Autonomous Observatory
2010
The High Energy Astrophysics group of the stellar department of the Astronomical Institute in Ondřejov operates two small aperture robotic telescopes called BART and D50. Both telescopes are capable of making automatic followup observation of gamma-ray burst optical counterparts. This paper deals with the smaller telescope BART.
Photometric and Spectroscopic Properties of Type Ia Supernova 2018oh with Early Excess Emission from the $Kepler$ 2 Observations
2019
Supernova (SN) 2018oh (ASASSN-18bt) is the first spectroscopically-confirmed type Ia supernova (SN Ia) observed in the $Kepler$ field. The $Kepler$ data revealed an excess emission in its early light curve, allowing to place interesting constraints on its progenitor system (Dimitriadis et al. 2018, Shappee et al. 2018b). Here, we present extensive optical, ultraviolet, and near-infrared photometry, as well as dense sampling of optical spectra, for this object. SN 2018oh is relatively normal in its photometric evolution, with a rise time of 18.3$\pm$0.3 days and $\Delta$m$_{15}(B)=0.96\pm$0.03 mag, but it seems to have bluer $B - V$ colors. We construct the "uvoir" bolometric light curve hav…
Two Remarkably Luminous Galaxy Candidates at z ≈ 10-12 Revealed by JWST
2022
The first few 100 Myr at z > 10 mark the last major uncharted epoch in the history of the universe, where only a single galaxy (GN-z11 at z ≈ 11) is currently spectroscopically confirmed. Here we present a search for luminous z > 10 galaxies with JWST/NIRCam photometry spanning ≈1–5 μm and covering 49 arcmin2 from the public JWST Early Release Science programs (CEERS and GLASS). Our most secure candidates are two MUV ≈ −21 systems: GLASS-z12 and GLASS-z10. These galaxies display abrupt ≳1.8 mag breaks in their spectral energy distributions (SEDs), consistent with complete absorption of flux bluewards of Lyα that is redshifted to =+z12.40.3 0.1and=+z10.40.5 0.4. Lower redshift interlopers su…
Análisis del discurso aplicado al aprendizaje de competencias comunicativas en el dominio del turismo
2017
This paper focuses on possible didactic applications of corpus linguistic analysis results. After having stated the theoretical frame around the concept of specialized discourses within a professional context, it is firstly argued that professional discourses use the same linguistic patterns than « general » discourse; hence, it is not necessary to acquire previous general knowledge before learning language for specific purposes (LSP). Secondly, this paper suggests that corpus linguistic can help to design the contents used for teaching communicative competences what is illustrated through the analysis of the pragmatic patterns present in a corpus made of "short stories". This corpus has be…
Survival in extreme dryness and DNA-single-strand breaks.
1992
A wide variety of organisms (the so-called "anhydrobiotes') is able to survive long periods of time in a state of utmost dehydration and can thus survive in extremely dry environments including artificially imposed or space vacuum. Known strategies of survival include the accumulation of certain polyols, especially disaccharides, which help prevent damage to membranes and proteins. Here we report that DNA in vacuum-dried spores is damaged to a very substantial degree by processes leading to DNA strand breaks. Most of these lesions are obviously repaired during germination, but extensive damage to DNA and enzymes after long exposure times (months to years) finally diminish the chances of sur…
Photobiology in space: An experiment on Spacelab I
1984
The joint European/US Spacelab Mission I, scheduled for October 1983 for a 9 day lasting Earth-orbiting flight, provides a laboratory system for various disciplines of science, including exobiology. On the pallet, in the experiment ES 029 "Microorganisms and Biomolecules in Space Hard Environment" 316 dry samples of Bacillus subtilis spores will be exposed to space vacuum and/or selected wavelenghs of solar UV radiation. After recovery action spectra of inactivation, mutation induction, reparability and photochemical damage in DNA and protein will be determined. The results will contribute to the understanding of the mechanism of the increased UV sensitivity of bacterial spores in vacuo and…
Response ofBacillus subtilis spores to dehydration and UV irradiation at extremely low temperatures
1996
Spores of Bacillus subtilis have been exposed to the conditions of extreme dehydration (argon/silica gel; simulated space vacuum) for up to 12 weeks at 298 K and 80 K in the dark. The inactivation has been correlated with the production of DNA-double strand-breaks. The temperature-dependence of the rate constants for inactivation or production of DNA-double strand-breaks is surprisingly low. Controls kept in the frozen state at 250 K for the same period of time showed no sign of deterioration. In another series of experiments the spores have been UV irradiated (253.7 nm) at 298 K, 200 K and 80 K after exposure to dehydrating conditions for 3 days. Fluence-effect relationships for inactivati…