Glass transition in models with controlled frustration

A class of models with self-generated disorder and controlled frustration is studied. Between the trivial case, where frustration is not present at all, and the limit case, where frustration is present over every length scale, a region with local frustration is found where glassy dynamics appears. We suggest that in this region, the mean field model might undergo a p-spin like transition, and increasing the range of frustration, a crossover from a 1-step replica symmetry breaking to a continuous one might be observed.Comment: 4 pages, 6 figure

Lincoln: Inconsistencies in Racial Perspectives

This paper explores the inconsistencies in Abraham Lincoln’s views on slavery and race derived from speeches using his own words and from those of contemporary writers commenting on his ideas. Most of the volumes written about the sixteenth president have extolled his virtues and overlooked or excused his failings. Even when his own words showed racist tones, it was said that his prejudice mellowed as he aged during the war years. The research shows a man willing to do anything to preserve the union even to the point of allowing the institution of slavery to continue. The second section of this thesis discusses some of the local people who, by their actions and words, had a lasting effect on Lincoln’s ideas on slavery and race. William Seward, an advisor to the president had significant input on presidential decisions and Union activities. Frederick Douglass, a former slave whose abolitionist activities and eloquent writings made a tremendous case for equality. Also examined in this paper are the local effects of President Lincoln’s policies such as the New York City Draft riots and the Elmira Prison Camp. These people and events have been largely ignored by the educational system. Included is a link to a website that provides an avenue for teachers and students to explore the many events and individuals that are generally disregarded in the curriculum but played a significant role in social movements and the Civil War. Civil War Circle Website: http://caprice73.wix.com/lincolns-circl

Glass transition in granular media

In the framework of schematic hard spheres lattice models for granular media we investigate the phenomenon of the ``jamming transition''. In particular, using Edwards' approach, by analytical calculations at a mean field level, we derive the system phase diagram and show that ``jamming'' corresponds to a phase transition from a ``fluid'' to a ``glassy'' phase, observed when crystallization is avoided. Interestingly, the nature of such a ``glassy'' phase turns out to be the same found in mean field models for glass formers.Comment: 7 pages, 4 figure

Interfacial chemistry of a perfluoropolyether lubricant studied by XPS and TDS

The interfacial chemistry of Fomblin Z25, a commercial perfluoropolyether used as lubricant for space applications, with different metallic surfaces: 440C steel, gold and aluminum was studied. Thin layers of Fomblin Z25 were evaporated onto the oxide-free substrates and the interfacial chemistry studied using XPS and TDS. The reactions were induced by heating the substrate and by rubbing the substrate with a steel ball. Gold was found to be completely unreactive towards Fomblin at any temperature. Reaction at room temperature was observed only in the case of the aluminum substrate, the most reactive towards Fomblin Z25 of the substrates studied. It was necessary to heat the 440C steel substrate to 190 degree C to induce decomposition of the fluid. The degradation of the fluid was indicated by the formation of a debris layer at the interface. This debris layer, composed of inorganic and organic reaction products, when completely formed, passivated the surface from further attack to the Fromblin on top. The tribologically induced reactions on 440C steel formed a debris layer of similar chemical characteristics to the thermally induced layer. In all cases, the degradation reaction resulted in preferential consumption of the difluoroformyl carbon (-OCF2O-)

Perovskite oxides: Oxygen electrocatalysis and bulk structure

Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations

Calcium-dependent binding between calmodulin and lysozyme

AbstractCalmodulin, an acidic protein that binds calcium with high affinity, has multiple roles in the activation of many enzymes involved in cellular regulation of eukaryotes. In this study we show that calmodulin binding to hen egg-white lysozyme, in a Ca2+-dependent way, was observed using electroblots incubated with biotinylated calmodulin and detected with avidin-alkaline phosphatase or for affinity chromatography on a gel calmodulin column. Antimicrobial activity of lysozyme was not modified in the presence of Ca2+-calmodulin

Effects of Ocean Acidification on Chlorophyll Content

Airborne pollutants contribute to ocean acidification and hence to the associated chlorophyll content level. Previous work showed that falling aerosols causing ocean acidification would in turn result in bleaching and productivity loss in coral reef builders. Chlorophyll content has been used as a measure of the concentration of the photosynthetic pigment chlorophyll a (the most common green chlorophyll) in the ocean. In our work we have monitored the change in chlorophyll content obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on board Terra/Aqua satellites from 2000-2009 over selected pilot areas. Moreover, we have used the Goddard Chemistry Aerosol Radiation and Transport (GOCART) NASA chemical model to simulate sulfate, dust, black carbon (BC), organic carbon (OC), and sea-salt aerosols content over the urban centers close to the areas where chlorophyll content is showing a significant decline. These parameters would reflect the natural versus anthropogenic origin of the aerosols falling over ocean waters. We expect to observe an overall decrease in chlorophyll content on the surface of the ocean. Hence, our findings may suggest that the effects of falling air pollutants in the ocean will be so detrimental as to gradually cause a decrease in photosynthetic producing material over several years

Simple predictive model for early childhood caries of chilean children.

Introduction: Early Childhood Caries (ECC), in both industrialized and developing countries, is the most prevalent chronic disease in childhood and it is still a health public problem, affecting mainly populations considered as vulnerable, despite being preventable. Objective The purpose of this study was to obtain a simple predictive model based on risk factors for improving public health strategies for ECC prevention for 3-5 year-old children. Methods - Clinical, environmental and psycho-socio-cultural data of children (n=250) aged 3-5 years, of both genders, from the Health Centers, were recorded in a Clinical History and Behavioral Survey. Results-24% of children presented behavioral problems (bizarre behavior was the main feature observed as behavioral problems). The variables associated to dmf ≥4 were: bad children temperament (OR=2.43 [1.34, 4.40]) and home stress (OR=3.14 [1.54, 6.41]). It was observed that the model for male gender has higher accuracy for ECC (AUC= 78%, p-value=0.000) than others. Conclusions- Based on the results, we proposed a model where oral hygiene, sugar intake, male gender, and difficult temperament are main factors for predicting ECC. This model could be a promising tool for cost-effective early childhood caries control.publishedVersio