Generation of Magnetic Field in the Pre-recombination Era

We study the possibility of generating magnetic fields during the evolution of electron, proton, and photon plasma in the pre-recombination era. We show that a small magnetic field can be generated in the second order of perturbation theory for scalar modes with adiabatic initial conditions. The amplitude of the field is \la 10^{-30} \rm G at the present epoch for scales from sub-kpc to \ga 100 \rm Mpc.Comment: 8 page

Geometries, Non-Geometries, and Fluxes

Using F-theory/heterotic duality, we describe a framework for analyzing non-geometric T2-fibered heterotic compactifications to six- and four-dimensions. Our results suggest that among T2-fibered heterotic string vacua, the non-geometric compactifications are just as typical as the geometric ones. We also construct four-dimensional solutions which have novel type IIB and M-theory dual descriptions. These duals are non-geometric with three- and four-form fluxes not of (2,1) or (2,2) Hodge type, respectively, and yet preserve at least N=1 supersymmetry.Comment: 68 pages, 1 figure. v2: added references, minor changes. v3: minor change

Galactic dust polarized emission at high latitudes and CMB polarization

We estimate the dust polarized emission in our galaxy at high galactic latitudes, which is the dominant foreground for measuring CMB polarization using the high frequency instrument (HFI) aboard Planck surveyor. We compare it with the level of CMB polarization and conclude that, for angular scales $\le 1^{\circ}$, the scalar-induced CMB polarization and temperature-polarization cross-correlation are much larger than the foreground level at $\nu \simeq 100 GHz$. The tensor-induced signals seem to be at best comparable to the foreground level.}Comment: Latex document, 4 pages, 2 figures, to appear in "Fundamental parameters in Cosmology", Rencontres de Moriond, 199

Transport of ferrihydrite nanoparticles in saturated porous media: role of ionic strength and flow rate

The use of nanoscale ferrihydrite particles, which are known to effectively enhance microbial degradation of a wide range of contaminants, represents a promising technology for in situ remediation of contaminated aquifers. Thanks to their small size, ferrihydrite nanoparticles can be dispersed in water and directly injected into the subsurface to create reactive zones where contaminant biodegradation is promoted. Field applications would require a detailed knowledge of ferrihydrite transport mechanisms in the subsurface, but such studies are lacking in the literature. The present study is intended to fill this gap, focusing in particular on the influence of flow rate and ionic strength on particle mobility. Column tests were performed under constant or transient ionic strength, including injection of ferrihydrite colloidal dispersions, followed by flushing with particle-free electrolyte solutions. Particle mobility was greatly affected by the salt concentration, and particle retention was almost irreversible under typical salt content in groundwater. Experimental results indicate that, for usual ionic strength in European aquifers (2 to 5 mM), under natural flow condition ferrihydrite nanoparticles are likely to be transported for 5 to 30 m. For higher ionic strength, corresponding to contaminated aquifers, (e.g., 10 mM) the travel distance decreases to few meters. A simple relationship is proposed for the estimation of travel distance with changing flow rate and ionic strength. For future applications to aquifer remediation, ionic strength and injection rate can be used as tuning parameters to control ferrihydrite mobility in the subsurface and therefore the radius of influence during field injection

Use of adaptive methods to improve degraded document images

An adaptive method for enhancing and binarizing the images of degraded documents has been presented here. This method does not need any feature handling by the user and it handles all kinds of degradations, removes noise, ensures connectivity of stroke and improves low-contrast. The project briefly includes following steps: a pre-processing procedure using a low-pass Wiener filter to produce a smoothened image, an approximate estimation of foreground regions,a background surface calculation by interpolating neighboring background intensities, a thresholding by combining the calculated background surface with the original image followed by a post-processing step which is carried out to enhance the quality of foreground regions and preserve line connectivity of texts

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

Exploring Postsecondary Market and Discipline Influences on Faculty Role Performance

Prior research has shown that the type of institution, disciplines, and characteristics of the faculty influence the structure and character of academic work. Zemsky and Shaman (1997) and others have suggested that differentiation among institutions, which has historically been structured along level of degree offerings and size/complexity, is now becoming increasingly structured along the lines of market segments – with many non-selective four-year institutions increasingly resembling two-year “convenience” institutions in terms of their academic organization. The purpose of this study was to test the extent to which academic work is increasingly organized by institutional market segment rather than traditional categories of institutional types and whether the shaping influences of discipline, gender, and type of appointment persist within these newly-defined institutional market segment categories. A comparison of the triumvirate of faculty work at the institutional market segments was done using data from the Changing Academic Profession (CAP) Survey 2007-2008. The results of the multivariate analysis of variance determined that some of the measures of faculty work in teaching, research, and service are affected by institutional type (Carnegie Basic Classification), market segment, discipline, gender, and appointment type