Search results for "mixture"
showing 10 items of 1178 documents
Influence of the drying processes of yeasts on their volatile phenol sorption capacity in model wine.
2009
International audience; Volatile phenols, such as 4-ethylphenol, are responsible for a "horsey" smell in wine. Thus, the study of volatile phenol sorption in yeasts, and their subsequent elimination from wine, helps to optimize eco-friendly wine curative processes. Here, we compared the influences of spray drying, lyophilization and evaporative drying at low water activity on yeast, for improving the 4-ethylphenol sorption capacity in a synthetic model wine. The changes that occur in the physico-chemical characteristics of the yeast surface (surface hydrophobicity, electron-donor character and zeta potential) during these drying processes were determined to assess if any correlation exists …
A DERIVATION OF THE VLASOV-NAVIER-STOKES MODEL FOR AEROSOL FLOWS FROM KINETIC THEORY
2016
This article proposes a derivation of the Vlasov-Navier-Stokes system for spray/aerosol flows. The distribution function of the dispersed phase is governed by a Vlasov-equation, while the velocity field of the propellant satisfies the Navier-Stokes equations for incompressible fluids. The dynamics of the dispersed phase and of the propellant are coupled through the drag force exerted by the propellant on the dispersed phase. We present a formal derivation of this model from a multiphase Boltzmann system for a binary gaseous mixture, involving the droplets/dust particles in the dispersed phase as one species, and the gas molecules as the other species. Under suitable assumptions on the colli…
Evolution of the Global Distribution of Carbon Dioxide: A Finite Mixture Analysis
2015
Economists and environmental policymakers have recently begun advocating a bottom-up approach to climate change mitigation, focusing on reduction targets for groups of nations, rather than large scale global policies. We advance this discussion by taking a quantitative perspective, focusing on econometric identification of groups of countries that have statistically similar distributions of carbon emissions using a broad range of finite mixture models. Nearly all of our results yield a consistent pattern: after 1980, there are two distinct emissions distributions, and that these distributions continue to evolve over time. We provide a rigorous analysis of these distributional differences al…
Cooperative Transition in the Conformation of 24-Mer Tarantula Hemocyanin upon Oxygen Binding
2005
Hemocyanins are large respiratory proteins of arthropods and mollusks, which bind oxygen with very high cooperativity. Here, we investigated the relationship between oxygen binding and structural changes of the 24-mer tarantula hemocyanin. Oxygen binding of the hemocyanin was detected following the fluorescence intensity of the intrinsic tryptophans. Under the same conditions, structural changes were monitored by the non-covalently bound fluorescence probe Prodan (6-propionyl-2-(dimethylamino)-naphthalene), which is very sensitive to its surroundings. Upon oxygen binding of the hemocyanin a red shift of 5 nm in the emission maximum of the label was observed. A comparison of oxygen binding c…
The influence of ants on soil and water losses from an orange orchard in eastern Spain
2008
Herbicide applications have greatly reduced plant cover, and increased soil erosion on a new orange orchard planted on valley slopes in eastern Spain. This has increased the importance of soil fauna, such as ants, in regulating soil erosion processes. Ants increase water infiltration rates by forming soil macropores during nest construction, but new soil brought to the surface by ant activity could increase the sediments available for erosion. Simulated rainfall experiments were conducted on 20 paired plots (20 with ant activity and 20 controls) to study the impact of ants on surface water flow and sediment movement in an intensively managed orange orchard near Valencia, Spain. Simulated ra…
Geostatistical 3-dimensional integration of measurements of soil magnetic susceptibility.
2010
In soil magnetometry, two types of measurements are usually performed. The first type is measurements performed on the soil surface, frequently using an MS2D sensor. The second type includes measurements of magnetic susceptibility carried out in the soil profile, usually to a depth of about 30 cm. Up to now, such measurement results were analyzed separately. However, it is possible and advantageous to integrate these two types of measurements. The goal of the study was to integrate measurements of magnetic susceptibility performed on the soil surface and in the soil profile. More specifically, the goal was to obtain 3-dimensional spatial distributions of magnetic susceptibility of the topso…
Repeated evolution of soldier sub-castes suggests parasitism drives social complexity in stingless bees
2016
The differentiation of workers into morphological castes represents an important evolutionary innovation that is thought to improve division of labor in insect societies. Given the potential benefits of task-related worker differentiation, it is puzzling that physical worker castes, such as soldiers, are extremely rare in social bees and absent in wasps. Following the recent discovery of soldiers in a stingless bee, we studied the occurrence of worker differentiation in 28 stingless bee species from Brazil and found that several species have specialized soldiers for colony defence. Our results reveal that worker differentiation evolved repeatedly during the last ~ 25 million years and coinc…
Successive Invasion-Mediated Interspecific Hybridizations and Population Structure in the Endangered Cichlid Oreochromis mossambicus.
2013
Hybridization between invasive and native species accounts among the major and pernicious threats to biodiversity. The Mozambique tilapia Oreochromis mossambicus, a widely used freshwater aquaculture species, is especially imperiled by this phenomenon since it is recognized by the IUCN as an endangered taxon due to genetic admixture with O. niloticus an invasive congeneric species. The Lower Limpopo and the intermittent Changane River (Mozambique) drain large wetlands of potentially great importance for conservation of O. mossambicus, but their populations have remained unstudied until today. Therefore we aimed (1) to estimate the autochthonous diversity and population structure among genet…
The Greeks in the West: genetic signatures of the Hellenic colonisation in southern Italy and Sicily
2015
Greek colonisation of South Italy and Sicily (Magna Graecia) was a defining event in European cultural history, although the demographic processes and genetic impacts involved have not been systematically investigated. Here, we combine high-resolution surveys of the variability at the uni-parentally inherited Y chromosome and mitochondrial DNA in selected samples of putative source and recipient populations with forward-in-time simulations of alternative demographic models to detect signatures of that impact. Using a subset of haplotypes chosen to represent historical sources, we recover a clear signature of Greek ancestry in East Sicily compatible with the settlement from Euboea during the…
Differential models of twin correlations in skew for body-mass index (BMI)
2018
Background Body Mass Index (BMI), like most human phenotypes, is substantially heritable. However, BMI is not normally distributed; the skew appears to be structural, and increases as a function of age. Moreover, twin correlations for BMI commonly violate the assumptions of the most common variety of the classical twin model, with the MZ twin correlation greater than twice the DZ correlation. This study aimed to decompose twin correlations for BMI using more general skew-t distributions. Methods Same sex MZ and DZ twin pairs (N = 7,086) from the community-based Washington State Twin Registry were included. We used latent profile analysis (LPA) to decompose twin correlations for BMI into mul…