Self-organization, scaling and collapse in a coupled automaton model of foragers and vegetation resources with seed dispersal

We introduce a model of traveling agents ({\it e.g.} frugivorous animals) who feed on randomly located vegetation patches and disperse their seeds, thus modifying the spatial distribution of resources in the long term. It is assumed that the survival probability of a seed increases with the distance to the parent patch and decreases with the size of the colonized patch. In turn, the foraging agents use a deterministic strategy with memory, that makes them visit the largest possible patches accessible within minimal travelling distances. The combination of these interactions produce complex spatio-temporal patterns. If the patches have a small initial size, the vegetation total mass (biomass) increases with time and reaches a maximum corresponding to a self-organized critical state with power-law distributed patch sizes and L\'evy-like movement patterns for the foragers. However, this state collapses as the biomass sharply decreases to reach a noisy stationary regime characterized by corrections to scaling. In systems with low plant competition, the efficiency of the foraging rules leads to the formation of heterogeneous vegetation patterns with $1/f^{\alpha}$ frequency spectra, and contributes, rather counter-intuitively, to lower the biomass levels.Comment: 11 pages, 5 figure

Communications Biophysics

Contains report on one research project.Joint Services Electronics Program (Contract DA36-039-AMC-03200(E))National Science Foundation (Grant GP-2495)National Institutes of Health (Grant MH-04737-05)National Institutes of Health (Grant 5 RO1 NB-05462-02)National Aeronautics and Space Administration (Grant NsG-496

Moderate Champagne consumption promotes an acute improvement in acute endothelial-independent vascular function in healthy human volunteers

Epidemiological studies have suggested an inverse correlation between red wine consumption and the incidence of CVD. However, Champagne wine has not been fully investigated for its cardioprotective potential. In order to assess whether acute and moderate Champagne wine consumption is capable of modulating vascular function, we performed a randomised, placebo-controlled, cross-over intervention trial. We show that consumption of Champagne wine, but not a control matched for alcohol, carbohydrate and fruit-derived acid content, induced an acute change in endothelium-independent vasodilatation at 4 and 8 h post-consumption. Although both Champagne wine and the control also induced an increase in endothelium-dependent vascular reactivity at 4 h, there was no significant difference between the vascular effects induced by Champagne or the control at any time point. These effects were accompanied by an acute decrease in the concentration of matrix metalloproteinase (MMP-9), a significant decrease in plasma levels of oxidising species and an increase in urinary excretion of a number of phenolic metabolites. In particular, the mean total excretion of hippuric acid, protocatechuic acid and isoferulic acid were all significantly greater following the Champagne wine intervention compared with the control intervention. Our data suggest that a daily moderate consumption of Champagne wine may improve vascular performance via the delivery of phenolic constituents capable of improving NO bioavailability and reducing matrix metalloproteinase activity

Exchange and correlation as a functional of the local density of states

A functional $E_{xc}[\rho(\r,\epsilon)]$ is presented, in which the exchange and correlation energy of an electron gas depends on the local density of occupied states. A simple local parametrization scheme is proposed, entirely from first principles, based on the decomposition of the exchange-correlation hole in scattering states of different relative energies. In its practical Kohn-Sham-like form, the single-electron orbitals become the independent variables, and an explicit formula for the functional derivative is obtained.Comment: 5 pages. Expanded version. Will appear in Phys. Rev.

Advanced Computational Aided Development of Autonomous Inflow Control Device (AICD)

Autonomous inflow control devices (AICDs) represent a successful technology utilized in maximizing reservoir sweep and increased oil recovery. They are an evolutionary enhancement over the passive inflow control device (ICD) such as a nozzle or helix type, which have a choke that is fixed for the lifetime of the well. This paper discusses a technique which accelerated the AICD development from defining the operational parameters to delivering a fully functional product, while considering the various mechanical and hydraulic loads that are critical in providing robustness during operations. Due to limited space availability between the AICD sub-assembly, basepipe dimensions, and complex loading conditions, iterative designs were established to meet the operational parameters. Simulations using finite element analysis (FEA) facilitated the development via performance evaluation of each design under various load conditions. The FEA simulation results provided the direction to refine, optimize and finalize the design. Mechanical loads evaluated in the simulations included: tension, torque, bending, and impact shock, while hydraulic loads included: collapse, burst, and injection pressure. On finalizing the design, the simulation results were validated with prototype testing. The final design met the operational parameters through FEA, that enabled the successful development of the product, saving more than 50% of a typical development cycle time. The FEA simulations provided stress information of each feature, modelling the anticipated loading during the service life, which contributed to the improved robustness and complex features reliability. Prototype test samples were manufactured based on the final design. A full range of validation tests were conducted to validate the final design of the simulation model and to establish appropriate operational limitations of the AICD assembly when subjected to various loads. A leak test was performed before and after the applicable tests to verify that a leak path had not developed. At the conclusion of every test, each AICD element (manufactured from tungsten carbide) was inspected for damage to verify the device had not failed. The test results proved the final design could achieve or exceed the minimum requirements under various load conditions using the simulation technique that accelerated the development process. This design has been used as the basis for various other sizes, with a similar mounting system, which have been successfully deployed in field applications. The use of this technique significantly accelerated the development process. It involved several design iterations and FEA simulations to evaluate various designs throughout the development cycle. FEA has been applied as a value adding tool to guide design optimization, which has been verified by testing, to successfully anticipate the loadings as per operational parameters. In addition to the shortened development process, the validation test development cost was significantly minimized, using FEA, and a robust product was delivered. The validation test results aligned with the FEA predictions

Development of new non-dairy beverages from Mediterranean fruit juices fermented with water kefir microorganisms

The aim of this work was to explore the use of several Mediterranean fruit juices as fermentable substrates to develop new non-dairy fermented beverages. Microbiological, chemical and sensory features of kefir-like beverages obtained after the fermentation of juices extracted from fruits cultivated in Sicily (southern Italy) with water kefir microorganisms were investigated. Results indicated that both lactic acid bacteria and yeasts were able to develop in the fruit juices tested, but the highest levels were registered with prickly pear fruit juice. All fruit juices underwent a lactic fermentation, since a lactic acid content was detected in the resulting kefir-like beverages. Except kiwifruit and quince based kefirs, total titratable acidity increased for the other experimental products. A general decrease of the soluble solid content and an increase of the number of volatile organic compounds (VOCs) was also observed after fermentation. As expected, the fermentation increased the concentration of alcohols. The main fermentation in KLBs resulted to be yeast-based. Kiwifruit and pomegranate juices possessed a high antioxidant activity. Esters compounds were present at higher amount after the fermentation, especially in grape, pomegranate and quince. Aldehydes showed an opposite trend. Changes in colour attributes were registered as noticeable at human perception scale. The overall quality evaluation indicated that, among the Mediterranean fruit juices tested, apple and grape beverages were the products mostly appreciated by the tasters. Therefore, these findings support the possibility to develop fruit-based kefirlike beverages with high added value and functional properties

Fractalkine receptor (CX3CR1) deficiency sensitizes mice to the behavioral changes induced by lipopolysaccharide

<p>Abstract</p> <p>Background</p> <p>Interactions between fractalkine (CX₃CL1) and fractalkine receptor (CX₃CR1) regulate microglial activation in the CNS. Recent findings indicate that age-associated impairments in CX₃CL1 and CX₃CR1 are directly associated with exaggerated microglial activation and an impaired recovery from sickness behavior after peripheral injection of lipopolysaccharide (LPS). Therefore, the purpose of this study was to determine the extent to which an acute LPS injection causes amplified and prolonged microglial activation and behavioral deficits in CX₃CR1-deficient mice (CX₃CR1^-/-).</p> <p>Methods</p> <p>CX₃CR1^-/-mice or control heterozygote mice (CX₃CR1^+/-) were injected with LPS (0.5 mg/kg i.p.) or saline and behavior (i.e., sickness and depression-like behavior), microglial activation, and markers of tryptophan metabolism were determined. All data were analyzed using Statistical Analysis Systems General Linear Model procedures and were subjected to one-, two-, or three-way ANOVA to determine significant main effects and interactions.</p> <p>Results</p> <p>LPS injection caused a prolonged duration of social withdrawal in CX₃CR1^-/-mice compared to control mice. This extended social withdrawal was associated with enhanced mRNA expression of IL-1β, indolamine 2,3-dioxygenase (IDO) and kynurenine monooxygenase (KMO) in microglia 4 h after LPS. Moreover, elevated expression of IL-1β and CD14 was still detected in microglia of CX₃CR1^-/-mice 24 h after LPS. There was also increased turnover of tryptophan, serotonin, and dopamine in the brain 24 h after LPS, but these increases were independent of CX₃CR1 expression. When submitted to the tail suspension test 48 and 72 h after LPS, an increased duration of immobility was evident only in CX₃CR1^-/-mice. This depression-like behavior in CX₃CR1^-/-mice was associated with a persistent activated microglial phenotype in the hippocampus and prefrontal cortex.</p> <p>Conclusions</p> <p>Taken together, these data indicate that a deficiency of CX₃CR1 is permissive to protracted microglial activation and prolonged behavioral alterations in response to transient activation of the innate immune system.</p

Αξιοβίωτη Ολοκληρωμένη Ανάπτυξη. Από την Θεωρία στην Πράξη: Η περίπτωση των αστέγων της Αθήνας

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Περιβάλλον και Ανάπτυξη