Search results for "RAS"
showing 10 items of 26429 documents
Analysis of drought and vulnerability in the North Darfur region of Sudan
2018
North Darfur of Sudan is located on the edge of the Sahara Desert and endures frequent droughts due to water shortages and high summer temperatures. Monitoring and understanding drought characteristics are essential for integrated drought risk mitigation and prevetion of land degradation. This study evaluates drought conditions in North Darfur by analyzing the spatiotemporal distribution of drought using three drought indices (Standardized Precipitation Index, Vegetation Condition Index, and Soil Moisture Content Index) and their combined drought index (CDI) from 2004 to 2013. Biophysical and socioeconomic indicators are further used to measure vulnerability to drought risk and its three co…
Long-term annual burning of grassland increases CO2 emissions from soils.
2016
7 pages; International audience; Grasslands have potential to mitigate against climate change because of their large capacity to store soil organic carbon (SOC). However, the long-term impact of grassland management such as burning, which is still common in many areas of the world, on SOC is still a matter of debate. The objective of this study was to quantify the long-term effects of annual burning on CO2 output from soils and SOC stocks. The study was performed on a 62 years old field trial comparing annual burning (AB) to no burning associated with tree encroachment (NB), and to annual mowing (AM) with all treatments laid out in randomized block design with three replicates per treatment…
Volcanic plume and bomb field masses from thermal infrared camera imagery
2013
International audience; Masses erupted during normal explosions at Stromboli volcano (Italy) are notoriously difficult to measure. We present a method that uses thermal infrared video for cooling bomb fields to obtain the total power emitted by all hot particles emitted during an explosion. A given mass of magma (M) will emit a finite amount of thermal power, defined by M cp(Te−T0), cp and Te being magma specific heat capacity and temperature, and T0 being ambient temperature. We use this relation to convert the total power emitted by the bomb field to the mass required to generate that power. To do this we extract power flux curves for the field and integrate this through time to obtain to…
The first 40Ar-39Ar date from Oxfordian ammonite-calibrated volcanic layers (bentonites) as a tie-point for the Late Jurassic.
2013
AbstractEight volcanic ash layers, linked to large explosive events caused by subduction-related volcanism from the Vardar Ocean back-arc, interbedded with marine limestones and cherts, have been identified in the Rosso Ammonitico Veronese Formation (northeastern Italy). The thickest ash layer, attributed to the Gregoryceras transversarium ammonite Biozone (Oxfordian Stage), yields a precise and reliable 40Ar–39Ar date of 156.1 ± 0.89 Ma, which is in better agreement with GTS2004 boundaries than with the current GTS2012. This first biostratigraphically well-constrained Oxfordian date is proposed as a new radiometric tie-point to improve the Geologic Time Scale for the Late Jurassic, where a…
Search without rescue? Evaluating the international search and rescue response to earthquake disasters
2020
Earthquakes around the world are unnecessarily lethal and destructive, adversely affecting the health and well-being of affected populations. Most immediate deaths and injuries are caused by building collapse, making search and rescue (SAR) an early priority. In this review, we assess the SAR response to earthquake disasters. First, we review the evidence for the majority of individuals being rescued locally, often by relatives and neighbours. We then summarise evidence for successful live rescues by international SAR (ISAR) teams, along with the costs, ethics and other considerations of deployment. Finally, we propose an alternative approach to postdisaster ISAR, with the goal of reducing …
Dental wear at macro- and microscopic scale in rabbits fed diets of different abrasiveness: A pilot investigation
2020
To differentiate the effects of internal and external abrasives on tooth wear, we performed a controlled feeding experiment in rabbits fed diets of varying phytolith content as an internal abrasive and with addition of sand as an external abrasive. 13 rabbits were each fed one of the following four pelleted diets with different abrasive characteristics (no phytoliths: lucerne L; phytoliths: grass G; more phytoliths: grass and rice hulls GR; phytoliths plus external abrasives: grass, rice hulls and sand GRS) for two weeks. At the end the feeding period, three tooth wear proxies were applied to quantify wear on the cheek teeth at macroscopic and microscopic wear scales: CT scans were obtained…
Environmental and climatic controls of the clay mineralogy of Albian deposits in the Paris and Vocontian basins (France)
2020
18 pages; International audience; High-resolution clay mineral analyses were performed on lower and middle Albian deposits from the Paris and Vocontian basins in order to specify the weathering conditions that prevailed at that time. The clay mineral assemblages are composed of small proportions of chlorite and vermiculitic clays associated with abundant illite, R0 type illite-smectite mixed-layers (smectite) and kaolinite. Clay minerals originated from the physical alteration and chemical weathering of rocks and soils outcropping on the Variscan massifs bordering the studied areas. In the Paris Basin, the covariation of illite and kaolinite suggests the reworking of these latter minerals f…
New results in ancient Maya rituals researches: The study of human painted bones fragments from Calakmul archaeological site (Mexico)
2020
Abstract The funeral chambers of the ancient city of Calakmul (Mexico) and the individuals who were buried in them have brought in recent decades new knowledge about the beliefs and funeral customs of the pre-Hispanic Maya. Tombs and bodies were prepared as part of the rituals that should favor the return of ch'ulel to the Underworld, known as Xibalba by the ancient Maya. The ch'ulel is one of the two anemic entities that inhabit the individual, equivalent to our concept of the soul. Bodies preparation included coloured scented body ointments application, with a deep symbolic connotation and probably also a conservative purpose. The aim of this research was to characterize pigments and bind…
The global bio-events at the Cenomanian-Turonian transition in the reduced Bahloul Formation of Bou Ghanem (central Tunisia).
2010
In central Tunisia, the thickness of the Bahloul Formation varies generally between 20 to 40 m such as for example, respectively, at wadi Smara near Kalaat Senan and at wadi Bahloul near Maktar. The thickness is also of several tens metres at Koudiat el Azreg near Jerissa and at Tajerouine. In these sites where the thickness of the Bahloul Formation is dilated, in addition to five geochemical events (d13C), nine bio-events were defined near the Cenomanian-Turonian transition, successively in ascending order: 1. LO Rotalipora cushmani, 2. Heterohelix bio-event, 3. FO Pseudaspidoceras pseudonodosoides, 4. LO P. pseudonodosoides, 5. LO Thalmanninella multiloculata, 6. “filaments” bio-event, Ce…
Changes of shell microstructural characteristics of Cerastoderma edule (Bivalvia) — A novel proxy for water temperature
2017
Abstract Shells of bivalves potentially provide an excellent archive for high-resolution paleoclimate studies. However, quantification of environmental variables, specifically water temperature remains a very challenging task. Here, we explore the possibility to infer water temperature from changes of microstructural characteristics of shells of the common cockle, Cerastoderma edule . The size and elongation of individual microstructural units, i.e., prisms, in the outer shell layer of seven three to five year-old, specimens collected alive from the intertidal zone of the North Sea near Texel, The Netherlands, and Schillig, Germany, were measured by means of automatic image processing. Grow…