Search results for "rate"

Supporting group decision makers to locate temporary relief distribution centres after sudden-onset disasters

2020

International audience; In the humanitarian response, multiple decision-makers (DMs) need to collaborate in various problems, such as locating temporary relief distribution centres (RDCs). Several studies have argued that maximising demand coverage, reducing logistics costs and minimising response time are among the critical objectives when locating RDCs after a sudden-onset disaster. However, these objectives are often conflicting and the trade-offs can considerably complicate the situation for finding a consensus.To address the challenge and support the DMs, we suggest investigating the stability of non-dominated alternatives derived from a multi-objective model based on Monte Carlo Simul…

Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake

2016

Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteri…

Ocean Acidification and the End-Permian Mass Extinction: To What Extent does Evidence Support Hypothesis?

2012

International audience; Ocean acidification in modern oceans is linked to rapid increase in atmospheric CO 2 , raising concern about marine diversity, food security and ecosystem services. Proxy evidence for acidification during past crises may help predict future change, but three issues limit confidence of comparisons between modern and ancient ocean acidification, illustrated from the end-Permian extinction, 252 million years ago: (1) problems with evidence for ocean acidification preserved in sedimentary rocks, where proposed marine dissolution surfaces may be subaerial. Sedimentary evidence that the extinction was partly due to ocean acidification is therefore inconclusive; (2) Fossils…

Downscaling of American National Aeronautics and Space Administration (NASA) daily air temperature in Sicily, Italy, and effects on crop reference ev…

2018

Abstract Air temperature (Ta) is one of the key factors in agro-hydrological studies including estimation of crop reference evapotranspiration (ET0), which is crucial for irrigation water management and sustainability of agro-ecosystem productivity. Because direct measurements of ET0 are difficult, expensive and time consuming, the use of physically based or empirical approaches linked to meteorological information is often preferred. The Prediction of Worldwide Energy Resource project developed by the American National Aeronautics and Space Administration (POWER-NASA) provides daily meteorological information on a 1° latitude by 1° longitude grid. Despite the poor spatial resolution charac…

Magma extrusion during the Ubinas 2013-2014 eruptive crisis based on satellite thermal imaging (MIROVA) and ground-based monitoring

2015

International audience; After 3 years of mild gases emissions, the Ubinas volcano entered in a new eruptive phase on September 2nd, 2013. The MIROVA system (a space-based volcanic hot-spot detection system), allowed us to detect in near real time the thermal emissions associated with the eruption and provided early evidence of magma extrusion within the deep summit crater. By combining IR data with plume height, sulfur emissions, hot spring temperatures and seismic activity, we interpret the thermal output detected over Ubinas in terms of extrusion rates associated to the eruption. We suggest that the 2013–2014 eruptive crisis can be subdivided into three main phases: (i) shallow magma intr…

Diving into exoplanets: Are water seas the most common?

2019

One of the basic tenets of exobiology is the need for a liquid substratum in which life can arise, evolve, and develop. The most common version of this idea involves the necessity of water to act as such a substratum, both because that is the case on Earth and because it seems to be the most viable liquid for chemical reactions that lead to life. Other liquid media that could harbor life, however, have occasionally been put forth. In this work, we investigate the relative probability of finding superficial seas on rocky worlds that could be composed of nine different, potentially abundant, liquids, including water. We study the phase space size of habitable zones defined for those substance…

The oldest granite clast in the Moodies conglomerate, Barberton greenstone belt, South Africa, and its likely origin

2018

Petrographic and geochemical characterization of the Middle‒Upper Jurassic Fe–Mn crusts and mineralizations from Monte Inici (north-western Sicily): …

2021

AbstractFe–Mn concretions and mineralizations, associated with condensed horizons and hardground, are significant archives in ancient carbonate rocks. Their petro-chemical study allows an assessment of the palaeoenvironmental context in which they were formed also connected to their biotic or abiotic origin. At the western side of the Monte Inici (Fornazzo section, north-western Sicily) a well exposed outcrop of condensed pelagic limestones (Rosso Ammonitico facies: Middle‒Upper Jurassic) is well-known and thoroughly studied. In this section, the base of the Rosso Ammonitico facies consists of a very condensed level rich in fossils with a variable thickness deposited from the early Bathonia…

Carbon isotope composition of CO2-rich inclusions in cumulate-forming mantle minerals from Stromboli volcano (Italy)

2017

We report on measurements of concentration and carbon isotope composition (δ13CCO2) of CO2 trapped in fluid inclusions of olivine and clinopyroxene crystals separated from San Bartolo ultramafic cumulate Xenoliths (SBX) formed at mantle depth (i.e., beneath a shallow Moho supposed to be at 14.8 km). These cumulates, erupted about 2 ka ago at Stromboli volcano (Italy), have been already investigated by Martelli et al. (2014) mainly for Sr-Nd isotopes and for their noble gases geochemistry. The concentration of CO2 varies of one order of magnitude from 3.8·10− 8 mol g− 1 to 4.8·10− 7 mol g− 1, with δ13C values between − 2.8‰ and − 1.5‰ vs V-PDB. These values overlap the range of measurements …

Development of branching brittle and ductile shear zones: A numerical study

2017

Continental collision zones are usually associated with large-scale strike-slip shear zones. In most cases these shear zones are complex and consist of multiple strands, varying in width, length, and total displacement. Here we present 2-D numerical models to simulate the formation of such shear zones at different depth levels within the crust, under either brittle (frictional/plastic) or ductile conditions. Localization of shear zones is initiated by a material contrast (heterogeneity) of the material parameters. We systematically test the rate of strain-weakening in brittle and in ductile regimes to understand its influence on the development of shear zone networks. Our simulations sugges…