Control of brain blood flow by capillaries: a simulation study in an anatomically accurate large human vascular network

In this paper, the variations in cerebral blood flow induced by global or localised capillary vasodilations are studied. The results demonstrate that pericyte-mediated regulation of blood flowat capillary level would be efficient for neuro-vascular coupling. By contrast to a regulation situated at the level of arterioles (Lorthois et al. 2011b), the changes in blood volume can be highly localised in space, with the potential to be as close as possible of areas of neuronal activation. However, the changes in blood flow are much more diffuse. This imposes limits on the ultimate spatial resolution of hemodynamically based brain functional imaging techniques

A microscopic model for Josephson currents

A microscopic model of a Josephson junction between two superconducting plates is proposed and analysed. For this model, the nonequilibrium steady state of the total system is explicitly constructed and its properties are analysed. In particular, the Josephson current is rigorously computed as a function of the phase difference of the two plates and the typical properties of the Josephson current are recovered

Self-consistent equation for an interacting Bose gas

We consider interacting Bose gas in thermal equilibrium assuming a positive and bounded pair potential $V(r)$ such that 0<\int d\br V(r) = a<\infty. Expressing the partition function by the Feynman-Kac functional integral yields a classical-like polymer representation of the quantum gas. With Mayer graph summation techniques, we demonstrate the existence of a self-consistent relation $\rho (\mu)=F(\mu-a\rho(\mu))$ between the density $\rho$ and the chemical potential $\mu$, valid in the range of convergence of Mayer series. The function $F$ is equal to the sum of all rooted multiply connected graphs. Using Kac's scaling V_{\gamma}(\br)=\gamma^{3}V(\gamma r) we prove that in the mean-field limit $\gamma\to 0$ only tree diagrams contribute and function $F$ reduces to the free gas density. We also investigate how to extend the validity of the self-consistent relation beyond the convergence radius of Mayer series (vicinity of Bose-Einstein condensation) and study dominant corrections to mean field. At lowest order, the form of function $F$ is shown to depend on single polymer partition function for which we derive lower and upper bounds and on the resummation of ring diagrams which can be analytically performed.Comment: 33 pages, 6 figures, submitted to Phys.Rev.

Miami Classification for Probe-Based Confocal Laser Endomicroscopy

An essential element for any new advanced imaging technology is standardization of indications, terminology, categorization of images, and research priorities. In this review, we propose a state-of-the-art classification system for normal and pathological states in gastrointestinal disease using probe-based confocal laser endomicroscopy (pCLE). The Miami classification system is based on a consensus of pCLE users reached during a meeting held in Miami, Florida, in February 2009

Cost-benefit analysis of abatement measures for nutrient emission from agriculture

In intensive animal husbandry areas surface water N and P concentrations often remain too high. The Water Framework Directive calls for additional nutrient emission abatement measures. Therefore, costs and benefits for possible agricultural measures in Flanders were first analysed in terms of soil balance surplus. Finally, abatement measures for agriculture, households and industry were set off against each other and ranked according to their cost-efficiency by the Environmental Costing Model. Increased dairy cattle efficiency, winter cover crops and increased pig feed efficiency turn out very cost efficient. Other agricultural measures are less cost efficient than for instance collective treatment for households and industry.nitrogen and phosphorus abatement, surface water, cost efficiency, Environmental Economics and Policy, Livestock Production/Industries,

Achtergrondstudie bij de subsidies voor de biologische land- en tuinbouw in Vlaanderen

In opdracht van de Vlaamse overheid heeft het Louis Bolk Instituut, samen met het Instituut voor landbouw- en visserijonderzoek (ILVO), een studie uitgevoerd naar de bedrijfseconomische gevolgen van de omschakeling van gangbare naar biologische landbouw. Aanleiding voor de studie waren een mogelijke herziening van de hoogte van de overheidssubsidie die biologische landbouwers in Vlaanderen hiervoor ontvangen en het geringe aantal omschakelende agrariërs. Conclusie van de studie is dat voor veel bedrijven omschakeling naar biologische landbouw een rendabel alternatief kan vormen. De studie bevestigt tevens een aantal fundamentele kwetsbaarheden en obstakels. Transitiekosten (het vergaren van nieuwe kennis en marktcontacten, de afzet van de producten en voor sommige bedrijven desinvesteringen tijdens de overgangsperiode) kunnen een groot obstakel vormen voor omschakeling omdat deze transitiekosten pas na vele jaren worden terugverdiend. Daarnaast kan het risico op marktfalen goed bedrijfsresultaat in de weg staan. Deze kwetsbaarheden en obstakels manifesteren zich vooral op bedrijfsniveau waardoor ze moeilijker toewijsbaar worden naar teeltniveau. Een van de aanbevelingen is daarom om (ook) instrumenten te ontwikkelen die de overgangskosten en het risico op marktfalen verminderen. Doordat omschakeling voor veel bedrijven een aantrekkelijke optie lijkt en belangrijke kostencomponenten zich vooral op bedrijfsniveau manifesteren is een blijvende en op hectarebasis teruggebrachte ondersteuningspremie voor biologische landbouw nog slechts beperkt te verantwoorden. Aangezien prijzen continue wisselen en de beschikbaarheid van betrouwbare gegevens beperkt is, is ook een ‘beslissingsondersteunend rekenmodel’ opgeleverd waarmee berekeningen gemakkelijk later opnieuw gedaan kunnen worden

Equilibrium states for the Bose gas

The generating functional of the cyclic representation of the CCR (Canonical Commutation Relations) representation for the thermodynamic limit of the grand canonical ensemble of the free Bose gas with attractive boundary conditions is rigorously computed. We use it to study the condensate localization as a function of the homothety point for the thermodynamic limit using a sequence of growing convex containers. The Kac function is explicitly obtained proving non-equivalence of ensembles in the condensate region in spite of the condensate density being zero locally.Comment: 21 pages, no figure

Correlation Functions in the Two-dimensional Ising Model in a Magnetic Field at T=TcT=T_c

The one and two-particle form factors of the energy operator in the two-dimensional Ising model in a magnetic field at $T=T_c$ are exactly computed within the form factor bootstrap approach. Together with the matrix elements of the magnetisation operator already computed in ref.\,\cite{immf}, they are used to write down the large distance expansion for the correlators of the two relevant fields of the model.Comment: 18 pages, latex, 7 table

Topological aggregation, the twin paradox and the No Show paradox

International audienceConsider the framework of topological aggregation introduced by Chichilnisky (1980). We prove that in this framework the Twin Paradox and the No Show Paradox cannot be avoided. Anonymity and unanimity are not needed to obtain these results