Inequality and Network Structure

This paper explores the manner in which the structure of a social network constrains the level of inequality that can be sustained among its members. We assume that any distribution of value across the network must be stable with respect to coalitional deviations, and that players can form a deviating coalition only if they constitute a clique in the network. We show that if the network is bipartite, there is a unique stable payoff distribution that is maximally unequal in that it does not Lorenz dominate any other stable distribution. We obtain a complete ordering of the class of bipartite networks and show that those with larger maximum independent sets can sustain greater levels of inequality. The intuition behind this result is that networks with larger maximum independent sets are more sparse and hence offer fewer opportunities for coalitional deviations. We also demonstrate that standard centrality measures do not consistently predict inequality. We extend our framework by allowing a group of players to deviate if they are all within distance k of each other, and show that the ranking of networks by the extent of extremal inequality is not invariant in k.inequality;networks;coalitional deviations;power;centrality

Algebraic-eikonal approach to medium energy proton scattering from odd-mass nuclei

We extend the algebraic-eikonal approach to medium energy proton scattering from odd-mass nuclei by combining the eikonal approximation for the scattering with a description of odd-mass nuclei in terms of the interacting boson-fermion model. We derive closed expressions for the transition matrix elements for one of the dynamical symmetries and discuss the interplay between collective and single-particle degrees of freedom in an application to elastic and inelastic proton scattering from $^{195}$Pt.Comment: latex, 14 pages, 4 figures uuencoded, to be published in Physical Review

SIMULATION OF FLOW AND PARTICLE TRANSPORT AND DEPOSITION IN POROUS MEDIA WITH COMPUTATIONAL FLUID DYNAMICS

The simulation of transport and deposition of colloidal particles in porous media finds important applications in many engineering and environmental problems, such as particle filtration, catalytic processes carried out in filter beds, chromatographic separation and aquifer remediation. This study focuses in particular on remediation of contaminated groundwater via direct injection of nano-sized zerovalent iron particles, which have been shown to be able to efficiently degrade a large variety of contaminants. Application of this technology on full scale applications poses a number of challenges, the most important of which regards the mobility of the particles and their delivery to the contaminated site in the soil. Particles migration is usually quantitatively expressed by a single parameter: the deposition efficiency in the porous bed, whose theoretical reference lies in the classical colloid filtration theory, which moreover further subdivides the process of deposition in the three mechanisms by which particles can reach the solid grain: Brownian diffusion, steric interception, and gravitational sedimentation. This theory, however, has been developed only for very simple geometrical representations of the porous media and a narrow range of fluid conditions. The difficulties in investigating this kind of systems from the experimental point of view have prevented the development of accurate models able to account for the high degree of complexity which characterizes a porous medium, both in the grain arrangement and in their shape. The aim of this study is therefore to simulate the transport of the nanoparticles and their interaction with the porous media (at the microscopic scale), in order to improve the current understanding of these phenomena and obtain predictive models for the deposition efficiency of the colloids on the surface of the grains constituting the porous medium; moreover, eventually, to evaluate the effectiveness of the zerovalent iron technology. Several two and three dimensional microscale (the order of millimiters) representations of grain packings with different degrees of complexity were analyzed. First, two dimensional random arrangements of spheres were considered. Then, the analysis was extended to domains reconstructed from SEM images of a real porous medium. The work was then expanded in three dimensions, first considering simplified domains constituted by irregular packings of spheres, and finally geometries constituted by grains of realistic shapes. These last geometries were created using an algorithm simulating the grain sedimentation process in porous media (Settledyn). Flow field and particle transport was then investigated using finite volume CFD codes (Fluent and OpenFoam), solving the Navier-Stokes equations for the flow and using an Eulerian approach for the colloid transport, eventually obtaining, for each case, an estimate of the colloidal transport efficiency. After having validated the methodology used in this work by comparing our results with proved analytical results available for simplified cases, new predictive equations for each of the individual contributions of the three deposition mechanisms were derived, highlighting the differences from the theoretical model due to the wider range of operating conditions investigated and/or the different geometrical characteristics of the porous media

A Chiral N=1 Type I Vacuum in Four Dimensions and Its Heterotic Dual

In this paper we consider Type I string theory compactified on a Z_7 orbifold. The model has N=1 supersymmetry, a U(4) \otimes U(4) \otimes U(4) \otimes SO(8) gauge group, and chiral matter. There are only D9-branes (for which we discuss tadpole cancellation conditions) in this model corresponding to a perturbative heterotic description in a certain region of the moduli space. We construct the heterotic dual, match the perturbative type I and heterotic tree-level massless spectra via giving certain scalars appropriate vevs, and point out the crucial role of the perturbative superpotential (on the heterotic side) for this matching. The relevant couplings in this superpotential turn out to be non-renormalizable (unlike the Z-orbifold case discussed in Ref [1], where Yukawa couplings sufficed for duality matching). We also discuss the role of the anomalous U(1) gauge symmetry present in both type I and heterotic models. In the perturbative regime we match the (tree-level) moduli spaces of these models. We point out possible generalizations of the Z_3 and Z_7 cases to include D5-branes which would help in understanding non-perturbative five-brane dynamics on the heterotic side.Comment: Revtex 3.0, 23 pages, 1 eps figure (to appear in Phys. Rev. D

Hypolipidemic, Hypoglycemic and Anti-oxidant Activities of Flower Extracts of Allamanda Violacea A. DC (Apocynaceae)

Purpose: To investigate the anti-dyslipidemic, anti-oxidant and anti-diabetic activities of the aqueous extract and solvent fractions of A. violacea flowers.Methods: The aqueous extract was fractionated into petroleum ether, ether, chloroform, chloroformmethanol (4:1) and chloroform-methanol (3:2) fractions. Lipid lowering activity was evaluated in two models, viz, triton WR-1339 - induced hyperlipimea in rats as well as fructose-rich high fat diet. To assess anti-oxidant activity, in-vitro model of non-enzymic superoxide hydroxyl radicals and microsomal lipid peroxidation by non-enzymic inducer was adopted. Hypoglycemic activity was evaluated by sucrose-loaded rat model.Results: Amongst the fractions, ether and chloroform fractions caused marked decrease in the levels of total cholesterol (Tc), triglycerides (Tg), plasma lipids (Pl), and protein by 24, 23, 23 and 22 %, and 24, 22, 23 and 19 %, respectively. In rats fed with high fat diet (HFD), ether and chloroform fractions lowered Tc, Tg and, Pl by 26, 25 and 26 %, and 18, 19 and 20 %, respectively. Significant decrease in superoxide anions, hydroxyl radicals and microsomal lipid peroxidation by ether and chloroform fractions was also observed. Chloroform, chloroform-methanol (4:1) and chloroform-methanol (3:2) fractions showed antihyperglycaemic activity to the extent of 25.2, 21.6 and 23.2 %, respectively.Conclusion: The flowers of this plant, especially the ether and chloroform extracts, may be suitable as an anti-oxidant supplement for lipid management.Keywords: Allamanda violacea flowers, Anti-hyperlipidemic,  Anti-hyperglycemic, Anti-oxidant

ACUTE PORPHYRIA AMONGST PSYCHIATRIC PATIENTS

A total of 519 consecutive patients, admitted to psychiatric wards of two different hospitals, were screened for evidence of increased excretion of porphobilinogen in the urine by original Watson Schwartz test and modified Watson Schwartz test supported with quantitative estimation of porphobilinogen by Remington's method in search of cases of acute porphyria amongst psychiatric patients. An additional 273 normal healthy volunteers were also screened as controls. Two cases (0.38%) were found which could be unequivocally diagnosed to be suffering from acute intermittent porphyria amongst psychiatric patients. These cases belonged to the category of missed diagnosis being labelled as hysterical. Seven more cases were positive by modified Watson Schwartz test but the test was only transiently positive and the Ehrlichaldehyde reactor substance was unstable. In the absence of detailed enzymatic and family studies, these cases have been kept under the category of suspected prophyria. A significant number of psychiatric patients (12.9%) gave positive original Watson-Schwartz test but were negative for modified test. Similar reaction was seen in 2.6% of healthy controls. The significance of this finding needs to be evaluated

Antimagnetic rotation and sudden change of electric quadrupole transition strength in 143Eu

Lifetimes of the states in the quadrupole structure in 143Eu have been measured using the Doppler shift attenuation method as well as parity of the states in the sequence has been firmly identified from polarization measurement using the Indian National Gamma Array. The decreasing trends of the deduced quadrupole transition strength B(E2) with spin, along with increasing J (2) /B(E2) values before band crossing, conclusively establish the origin of these states as arising out of antimagnetic rotation. The abrupt increase in the B(E2) values after the band crossing in the quadrupole band, a novel feature observed in the present experiment, may indicates the crossing of different shears configurations resulting in re-opening of shears structure. The results are well reproduced by numerical calculation within the framework of semi-classical geometric model.Comment: 6 pages, 4 postscript figure