Search results for "Mite"
showing 10 items of 795 documents
Textural features and isotope geochemistry of the Scillato travertine (north-central Sicily): genetic implications.
2015
The travertine deposit, outcropping near the Scillato town (north-central Sicily), was originated by precipitation of calcium carbonate from the Scillato springs, documented as bicarbonate-enriched waters due to dissolution of the Madonie mountains carbonate rocks. This deposit is today well represented by the Travertine Cave, essentially constituted by stalactites and stalagmites in which travertine typically appears laminated with alternation of light and dark laminae. Mineralogical analysis have revealed the almost exclusive presence of calcite and observation under the polarized-light microscope showed different textural features, like presence of debris and porous portions, micritic po…
Geochemistry and mineralogy of travertine deposits of the SW flank of Mt. Etna (Italy): Relationships with past volcanic and degassing activity
2007
Abstract Travertine deposits outcropping in the lower SW flank of Mt. Etna were studied for their mapping, as well as for their chemical, mineralogical and isotopic compositions. These deposits are dated to about 24 to 5 ka in the Adrano area, located at the western limit of the study area. In this area travertines show high Mg contents and are composed mostly of dolomite, thus apparently ruling out any primary deposition in favour of a diagenetic origin. Travertines outcropping near Paterno, in the east part of the study area, should be younger than 18 ka. Those located to the SSW of Paterno (Paterno–Diga) show high Sr contents and aragonite as dominant mineralogical phase, thus suggesting…
Disequilibrium carbon and oxygen isotope fractionation in recent cave calcite: Comparison of cave precipitates and model data
2013
Abstract Speleothem proxy data provide important information in continental palaeo-climate research due to their precise chronology and wide geographic distribution. Despite a continuously growing number of field and numerical studies designed to study stable isotope fractionation effects, many aspects remain a matter of debate. Here, carbon and oxygen isotope ratios from cave drip water and calcite precipitates sampled on watch glasses in the Bunker Cave (Western Germany) are compared with the values expected for isotopic equilibrium. Furthermore, the field data are compared with the results of a numerical model simulating stalagmite growth and stable isotope ratios. Two drip sites with di…
Are oxygen isotope fractionation factors between calcite and water derived from speleothems systematically biased due to prior calcite precipitation …
2021
Abstract The equilibrium oxygen isotope fractionation factor between calcite and water (18αcalcite/H2O) is an important quantity in stable isotope geochemistry and allows in principle to infer temperature variations from carbonate δ18O if carbonate formation occurred in thermodynamic equilibrium. For this reason, many studies intended to determine the value of the oxygen isotope fractionation factor between calcite and water (18αcalcite/H2O) for a wide range of temperatures using modern cave calcite and the corresponding cave drip water or ancient speleothem carbonate and fluid inclusion samples. However, the picture that emerges from all of these studies indicates that speleothem calcite i…
The origin and timing of multiphase cementation in carbonates: Impact of regional scale geodynamic events on the Middle Jurassic Limestones diagenesi…
2009
The Middle Jurassic carbonates of the eastern part of the Paris Basin display surprisingly low values of porosity and permeability (Φ < 15‰ and K < 0.5 mD). The main objective of this study is to determine the causes and timing of the cementation that altered the petrophysical properties of these carbonates thereby destroying their potential as oil reservoirs; a fate that did not befall their equivalents in deeper, central parts of the Paris Basin. Using petrographic and geochemical analyses (stable O and C isotopes, Sr isotopes, major elements), we identify six calcitic spar stages, two dolomite stages, and several episodes of fracturing and stylolitization ordered in paragenetic sequence.…
Fluid geochemistry in a low-enthalpy geothermal field along a sector of southern Apennines chain (Italy)
2020
Abstract The chemical and isotopic features of the fluids (water and gases) in the Lucane thermal area (southern Italy) have been investigated in order to verify their origin, water temperature in the geothermal reservoir, and to recognize the main natural processes concerning the water composition during ascent towards the surface. The Lucane geothermal system is placed in the southern sector of the Apennines chains, a seismically active area, close to the southern base of the Mt. Alpi carbonate massif. Along the study area, two main sets of high-angle faults form an almost orthogonal fault system that, as suggested by local structural geology, acts as a preferential pathway for uprising d…
Diagnostic yield of a one sample immunochemical test at different cut-off values in an organised screening programme for colorectal cancer
2013
Abstract Background Quantitative immunochemical faecal occult blood tests have become the recommended tests for colorectal cancer screening. The aim of this study was to complete our knowledge on the performance of one of the quantitative immunochemical tests available, FOB-Gold, and to propose a possible strategy for an organised screening programme. Patients and methods Within the French organised screening programme, 23,231 average-risk individuals, aged 50–74 performed both a 3-day Hemoccult test and a 1-day FOB-Gold test. Performances of the immunochemical test were evaluated at different cut-off levels. Results The positivity rate for the Hemoccult was 2.1% and for the FOB-Gold varied…
Nullité facultative d'une saisie-attribution diligentée en période suspecte par un créancier social sur la fraction non libérée du capital social. Fa…
2017
International audience; (Civ. 2e, 12 mai 2016, n° 15-13.833, F-P+B, Sté Yara c/ Fondation Institut du Monde Arabe, D. 2016. 1088 ; Rev. sociétés 2016. 673, note A. Lecourt ; Bull. Joly 2016. 588, note F. Danos ; Act. proc. coll. 2016, comm. 158, obs. J.-M. Moulin)
Carcinoma epidermoide cutáneo: relación con los trastornos respiratorios del sueño y definición de la variante alto riesgo
2015
Introducción: Recientes publicaciones han mostrado que la hipoxia intermitente similar a la que encontramos en el síndrome de apnea e hipopnea del sueño (SAHS) parece estar implicada en el desarrollo, progresión y crecimiento de tumores en modelos animales, a través de la sobreproducción de factores de crecimiento (entre ellos el factor de crecimiento vascular endotelial o VEGF) y la interacción con la vía supresora del gen p53. EL carcinoma epidermoide cutáneo (CEC) es un tumor procedente de los queratinocitos del estrato espinoso de la epidermis, muy prevalente en la población general y cuya incidencia está en aumento. Su lesión precursora más frecuente es la queratosis actínica. Existe u…
Analysis of health communication texts: UK press coverage of debates about assisted dying
2015
Conventionally, social researchers analyse media messages by reading text and coding it. This is time consuming and restricts many studies to small samples. Nowadays very large amounts of text are available in electronic form, offering potential insights into the health messages they contain, but which appear daunting to the analyst with limited resources using conventional methods. I explain and illustrate methods for the computer-assisted analysis of media texts, using specialised software (Wordsmith Tools and Wordstat). These allow the analyst to provide a statistical overview of the key features of texts, to compare them (looking at change over time, for example) and to select illustrat…