Asymptotics for models of non-stationary diffusion in domains with a surface distribution of obstacles

We consider a time-dependent model for the diffusion of a substance through an incompressible fluid in a perforated domain ??, urn:x-wiley:mma:media:mma5323:mma5323-math-0001 with n?=?3,4. The fluid flows in a domain containing a periodical set of ?obstacles? (?\??) placed along an inner (n???1)?dimensional manifold urn:x-wiley:mma:media:mma5323:mma5323-math-0002. The size of the obstacles is much smaller than the size of the characteristic period ?. An advection term appears in the partial differential equation linking the fluid velocity with the concentration, while we assume a nonlinear adsorption law on the boundary of the obstacles. This law involves a monotone nonlinear function ? of the concentration and a large adsorption parameter. The ?critical adsorption parameter? depends on the size of the obstacles , and, for different sizes, we derive the time?dependent homogenized models. These models contain a ?strange term? in the transmission conditions on ?, which is a nonlinear function and inherits the properties of ?. The case in which the fluid velocity and the concentration do not interact is also considered for n???3.The authors would like to thank the anonymous referees for their careful reading of the manupscript and useful comments. The work has been partially supported by MINECO, MTM2013-44883-P

The environmental security debate and its significance for climate change

Policymakers, military strategists and academics all increasingly hail climate change as a security issue. This article revisits the (comparatively) long-standing “environmental security debate” and asks what lessons that earlier debate holds for the push towards making climate change a security issue. Two important claims are made. First, the emerging climate security debate is in many ways a re-run of the earlier dispute. It features many of the same proponents and many of the same disagreements. These disagreements concern, amongst other things, the nature of the threat, the referent object of security and the appropriate policy responses. Second, given its many different interpretations, from an environmentalist perspective, securitisation of the climate is not necessarily a positive development

Meta-Review of Metanalytic Studies with Repetitive Transcranial Magnetic Stimulation (rTMS) for the Treatment of Major Depression

BACKGROUND: Major Depression (MD) and treatment-resistant depression (TRD) are worldwide leading causes of disability and therapeutic strategies for these impairing and prevalent conditions include pharmacological augmentation strategies and brain stimulation techniques. In this perspective, repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique with a favorable profile of tolerability which, despite being recently approved by the Food and Drug Administration (FDA) for the treatment of patients with medication-refractory unipolar depression, still raises some doubts about most effective parameters of stimulation.METHODS: A literature search was performed using PubMed for the years 2001 through February 2011 in order to review meta-analytic studies assessing efficacy and safety issues for rTMS in depressive disorders. Fifteen meta-analyses were identified and critically discussed in order to provide an updated and comprehensive overview of the topic with specific emphasis on potentially optimal parameters of stimulation.RESULTS: First meta-analyses on the efficacy of rTMS for the treatment of MD and TRD have shown mixed results. On the other hand, more recent meta-analytic studies seem to support the antidepressant efficacy of the technique to a greater extent, also in light of longer periods of stimulation (e.g. > 2 weeks).CONCLUSION: rTMS seems to be an effective and safe brain stimulation technique for the treatment of medication refractory depression. Nevertheless, further studies are needed to better define specific stimulation-related issues, such as duration of treatment as well as durability of effects and predictors of response

The catatonic dilemma expanded

Catatonia is a common syndrome that was first described in the literature by Karl Kahlbaum in 1874. The literature is still developing and remains unclear on many issues, especially classification, diagnosis, and pathophysiology. Clinicians caring for psychiatric patients with catatonic syndromes continue to face many dilemmas in diagnosis and treatment. We discuss many of the common problems encountered in the care of a catatonic patient, and discuss each problem with a review of the literature. Focus is on practical aspects of classification, epidemiology, differential diagnosis, treatment, medical comorbidity, cognition, emotion, prognosis, and areas for future research in catatonic syndromes

Artificial boundaries and formulations for the incompressible Navier-Stokes equations. Applications to air and blood flows.

International audienceWe deal with numerical simulations of incompressible Navier-Stokes equations in truncated domain. In this context, the formulation of these equations has to be selected carefully in order to guarantee that their associated artificial boundary conditions are relevant for the considered problem. In this paper, we review some of the formulations proposed in the literature, and their associated boundary conditions. Some numerical results linked to each formulation are also presented. We compare different schemes, giving successful computations as well as problematic ones, in order to better understand the difference between these schemes and their behaviours dealing with systems involving Neumann boundary conditions. We also review two stabilization methods which aim at suppressing the instabilities linked to these natural boundary conditions

Prediction of the weathering properties of minerals based on the ion-ion interaction potential

Selection of solid matrix for immobilization of nuclear waste and of geological sites for its disposal represents a complex and consuming task. Previously, we demonstrated that the ion-ion interaction potential (HIP), representing the main term of the cohesive energy, can be used for estimation of stability of solid matrix/impurity systems. Here we demonstrated a strong correlation between the weathering properties of minerals and their IIIP. Based on these results we proposed a simple theoretical criterion which can be used for assessment of the long term stability of solid matrix for immobilization of radioactive and toxic metals. This criterion was applied in analysis of stability of autunites and some possible practical consequences of results obtained for immobilization of uranium by apatite are discussed.28th Symposium on the Scientific Basis for Nuclear Waste Management held at the 2004 MRS Spring Meeting, Apr 13-16, 2004, San Francisco, C

Theoretical stability assessment of uranyl phosphates and apatites: Selection of amendments for in situ remediation of uranium

Addition of an amendment or reagent to soil/sediment is a technique that can decrease mobility and reduce bioavailability of uranium (U) and other heavy metals in the contaminated site. According to data from literature and results obtained in field studies, the general mineral class of apatites was selected as a most promising amendment for in situ immobilization/ remediation of U. In this work we presented theoretical assessment of stability of U(VI) in four apatite systems (hydroxyapatite (HAP), North Carolina Apatite (NCA), Lisina Apatite (LA), and Apatite H) in order to determine an optimal apatite soil amendment which could be used for in situ remediation of uranium. In this analysis we used a theoretical criterion which is based on calculation of the ion-ion interaction potential, representing the main term of the cohesive energy of the matrix/ pollutant system. The presented results of this analysis indicate (i) that the mechanism of immobilization of U by natural apatites depends on their chemical composition and (ii) that all analyzed apatites represent, from the point of view of stability, promising materials which could be used in field remediation of U-contaminated sites. (c) 2005 Elsevier B.V. All rights reserved

Prediction of the weathering properties of minerals based on the ion-ion interaction potential

Selection of solid matrix for immobilization of nuclear waste and of geological sites for its disposal represents a complex and consuming task. Previously, we demonstrated that the ion-ion interaction potential (HIP), representing the main term of the cohesive energy, can be used for estimation of stability of solid matrix/impurity systems. Here we demonstrated a strong correlation between the weathering properties of minerals and their IIIP. Based on these results we proposed a simple theoretical criterion which can be used for assessment of the long term stability of solid matrix for immobilization of radioactive and toxic metals. This criterion was applied in analysis of stability of autunites and some possible practical consequences of results obtained for immobilization of uranium by apatite are discussed.28th Symposium on the Scientific Basis for Nuclear Waste Management held at the 2004 MRS Spring Meeting, Apr 13-16, 2004, San Francisco, C