Analysis of the approach to the convection instability point

A spectral analysis is presented of the fluctuations in a horizontal fluid layer subject to a downward directed temperature gradient, which, for a critical value, drives the system in a convective instability state. It is found that the external force resulting from the combination of the temperature gradient and the gravitation force gives rise to a coupling between the heat diffusion mode and a shear mode. As a result of this mode coupling the damping constant of the heat diffusion mode goes to zero when the temperature gradient increases towards its critical value, i.e. the heat diffusion mode behaves like a "soft mode". The implications of the mode coupling and of the ensuing softening of the heat diffusion mode on the light scattering spectrum are discussed

Illustrative components of the geological environment

In this chapter we provide an account of the contribution made by the Geosphere, in particular bedrock geological materials (part of the lithosphere), groundwater and hydrochemistry to the development of a GDF. In order to put this in context we provide a brief account of the general requirements of these attributes, particularly in respect of the post closure safety and, to a lesser extent, the construction phase of the GDF. We also provide a brief summary of the international approach to using bedrock geological materials and go on to describe the summary properties from a range of bedrock geological materials (lithologies and formations) in England, Wales and Northern Ireland, illustrated from well-documented examples

Coupling of thermal and mass diffusion in regular binary thermal lattice-gases

We have constructed a regular binary thermal lattice-gas in which the thermal diffusion and mass diffusion are coupled and form two nonpropagating diffusive modes. The power spectrum is shown to be similar in structure as for the one in real fluids, in which the central peak becomes a combination of coupled entropy and concentration contributions. Our theoretical findings for the power spectra are confirmed by computer simulations performed on this model.Comment: 5 pages including 3 figures in RevTex

BioMiCo:A supervised Bayesian model for inference of microbial community structure

Here, we describe a novel hierarchical model for Bayesian inference of microbial communities (BioMiCo). The model takes abundance data derived from environmental DNA, and models the composition of each sample by a two-level hierarchy of mixture distributions constrained by Dirichlet priors. BioMiCo is supervised, using known features for samples and appropriate prior constraints to overcome the challenges posed by many variables, sparse data, and large numbers of rare species. The model is trained on a portion of the data, where it learns how assemblages of species are mixed to form communities and how assemblages are related to the known features of each sample. Training yields a model that can predict the features of new samples. We used BioMiCo to build models for three serially sampled datasets and tested their predictive accuracy across different time points. The first model was trained to predict both body site (hand, mouth, and gut) and individual human host. It was able to reliably distinguish these features across different time points. The second was trained on vaginal microbiomes to predict both the Nugent score and individual human host. We found that women having normal and elevated Nugent scores had distinct microbiome structures that persisted over time, with additional structure within women having elevated scores. The third was trained for the purpose of assessing seasonal transitions in a coastal bacterial community. Application of this model to a high-resolution time series permitted us to track the rate and time of community succession and accurately predict known ecosystem-level events

In vitro screening of the endocrine disrupting potency of brominated flame retardants and their metabolites

DEVELOPMENTAL AND REPRODUCTIVE TOXICITY vitro screening the endocrine disrupting potency brominated flame retardants and their metabolites Timo Hamers Jorke Kamstra Edwin Sonneveld Albertinka Murk Bart Zegers Jan Boon Abraham Brouwer Institute for Environmental Studies IVM Amsterdam BioDetection Systems BDS Amsterdam Wageningen University Toxicology Group Wageningen Royal Netherlands Institute for Sea Research NIOZ Den Burg Ume University Ume Introduction Substantial evidence recently becoming available that brominated flame retardants BFRs are potential endocrine disruptorsi The toxicological profile BFRs however too incomplete and insufficient perform human and ecological risk assessment fill these gaps the funded research program FIREii was started December This program aims the identification and toxicological characterization the most potent and environmentally relevant BFRs and their possible risk for human and wildlife health part hazard identification approach twentyseven BFRs have been selected within the framework FIRE for pre screening their endocrinedisrupting potencies Selection test compounds was based maximal variation physicochemical characteristics BFRs within the test set allowing the establishment quantitative structure activity relationships QSARs iii addition environmental relevance high production volumes and persistence and availability for testing were used selection criteria BFRs were tested seven different vitro bioassays for their potency interfer

Levels of hexabromocyclododecane in harbor porpoises and common dolphins from Western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome P450

Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which γ-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (Σ)-HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 μg (g of lipid

Diffusion in Stationary Flow from Mesoscopic Non-equilibrium Thermodynamics

We analyze the diffusion of a Brownian particle in a fluid under stationary flow. By using the scheme of non-equilibrium thermodynamics in phase space, we obtain the Fokker-Planck equation which is compared with others derived from kinetic theory and projector operator techniques. That equation exhibits violation of the fluctuation dissipation-theorem. By implementing the hydrodynamic regime described by the first moments of the non-equilibrium distribution, we find relaxation equations for the diffusion current and pressure tensor, allowing us to arrive at a complete description of the system in the inertial and diffusion regimes. The simplicity and generality of the method we propose, makes it applicable to more complex situations, often encountered in problems of soft condensed matter, in which not only one but more degrees of freedom are coupled to a non-equilibrium bath.Comment: 10 pages, accepted in Phys. Rev.