Chiral RKKY interaction in Pr2Ir2O7

Motivated by the potential chiral spin liquid in the metallic spin ice Pr2Ir2O7, we consider how such a chiral state might be selected from the spin ice manifold. We propose that chiral fluctuations of the conducting Ir moments promote ferro-chiral couplings between the local Pr moments, as a chiral analogue of the magnetic RKKY effect. Pr2Ir2O7 provides an ideal setting to explore such a chiral RKKY effect, given the inherent chirality of the spin-ice manifold. We use a slave-rotor calculation on the pyrochlore lattice to estimate the sign and magnitude of the chiral coupling, and find it can easily explain the 1.5K transition to a ferro-chiral state.Comment: 9 pages; 7 figure

An argument for the nationalization of railroad rights-of-way

Transportation is a crucial element in any economy. With such a large portion of the United States\u27 economy centered around transportation, an efficient system of moving goods would be in the nation\u27s best interest. Competitive markets are the most effective mechanism for allocating resources efficiently. An efficient transportation system, therefore, would be one where competition among carriers is the norm. 1 Enormous infrastructure costs prohibit new railroads from entering the market, and prevent existing railroads from competing with trucks for freight transportation revenues. This paper focuses on the lack of competition in the railroad industry and attempts to demonstrate why trains are a superior mode of transportation than trucks. This paper will also show that increasing competition in the railroad industry can reduce freight transportation rates, increase service quality, reduce pollution, and reduce fossil fuel consumption. Nationalizing railroad rights-of-way in the United States would significantly improve competition in the transportation sector. Before discussing nationalization as a socially desirable policy for railroad rights-of-way, it is appropriate to first examine the competitive conditions that exist in the railroad and trucking industries

Diet-induced obesity impairs mammary development and lactogenesis in murine mammary gland

We have developed a mouse model of diet-induced obesity that shows numerous abnormalities relating to mammary gland function. Animals ate 40% more calories when offered a high-fat diet and gained weight at three times the rate of controls. They exhibited reduced conception rates, increased peripartum pup mortality, and impaired lactogenesis. The impairment of lactogenesis involved lipid accumulation in the secretory epithelial cells indicative of an absence of copius milk secretion. Expression of mRNAs for -casein, whey acid protein, and -lactalbumin were all decreased immediately postpartum but recovered as lactation was established over 2–3 days. Expression of acetyl-CoA carboxylase (ACC)- mRNA was also decreased at parturition as was the total enzyme activity, although there was a compensatory increase in the proportion in the active state. By day 10 of lactation, the proportion of ACC in the active state was also decreased in obese animals, indicative of suppression of de novo fatty acid synthesis resulting from the supply of preformed fatty acids in the diet. Although obese animals consumed more calories in the nonpregnant and early pregnant states, they showed a marked depression in fat intake around day 9 of pregnancy before food intake recovered in later pregnancy. Food intake increased dramatically in both lean and obese animals during lactation although total calories consumed were identical in both groups. Thus, despite access to high-energy diets, the obese animals mobilized even more adipose tissue during lactation than their lean counterparts. Obese animals also exhibited marked abnormalities in alveolar development of the mammary gland, which may partially explain the delay in differentiation evident during lactogenesis

Evaluation of children's centres in England (ECCE) : strand 1: first survey of children's centre leaders in the most deprived areas

This report is the first output from the Evaluation of Children's Centres in England (ECCE), a six year study commissioned by the Department for Education and undertaken by NatCen Social Research, the University of Oxford and Frontier Economics. The aim of ECCE is to provide an in-depth understanding of children's centre services, including their effectiveness in relation to different management and delivery approaches and the cost of delivering different types of services. The aim of Strand 1 is to profile children’s centres in the most disadvantaged areas, providing estimates on different aspects of provision with which to select centres for subsequent stages of the evaluation and to explore different models of provision. The findings below relate to 500 children's centres that are representative of all phase 1 and 2 centres (i.e. those in the 30percent most deprived areas).</p

Diverse CD81 proteins support hepatitis C virus infection.

Hepatitis C virus (HCV) entry is dependent on CD81. To investigate whether the CD81 sequence is a determinant of HCV host range, we expressed a panel of diverse CD81 proteins and tested their ability to interact with HCV. CD81 large extracellular loop (LEL) sequences were expressed as recombinant proteins; the human and, to a low level, the African green monkey sequences bound soluble HCV E2 (sE2) and inhibited infection by retrovirus pseudotype particles bearing HCV glycoproteins (HCVpp). In contrast, mouse or rat CD81 proteins failed to bind sE2 or to inhibit HCVpp infection. However, CD81 proteins from all species, when expressed in HepG2 cells, conferred susceptibility to infection by HCVpp and cell culture-grown HCV to various levels, with the rat sequence being the least efficient. Recombinant human CD81 LEL inhibited HCVpp infectivity only if present during the virus-cell incubation, consistent with a role for CD81 after virus attachment. Amino acid changes that abrogate sE2 binding (I182F, N184Y, and F186S, alone or in combination) were introduced into human CD81. All three amino acid changes in human CD81 resulted in a molecule that still supported HCVpp infection, albeit with reduced efficiency. In summary, there is a remarkable plasticity in the range of CD81 sequences that can support HCV entry, suggesting that CD81 polymorphism may contribute to, but alone does not define, the HCV susceptibility of a species. In addition, the capacity to support viral entry is only partially reflected by assays measuring sE2 interaction with recombinant or full-length CD81 proteins

Sex Differences in the Arousal of Need for Affiliation

This study reports that the Pelto Projective Pictures when scored by the Atkinson-Heyns-Veroff procedure is a valid instrument for measuring n affiliation. The hypothesis that an experimental group of junior-high-school students exposed to a stimulus would display a significantly higher mean n affiliation score than a control group was rejected. A sex difference was involved in the failure to reject the null hypothesis. There is strong evidence that n affiliation was aroused in an experimental group of females, but not in an experimental group of males. The Pelto Projective Pictures were successful in discriminating this difference. Moreover, the scoring procedure, developed for use with the TAT, appears to be applicable to other projective techniques

Density waves theory of the capsid structure of small icosahedral viruses

We apply Landau theory of crystallization to explain and to classify the capsid structures of small viruses with spherical topology and icosahedral symmetry. We develop an explicit method which predicts the positions of centers of mass for the proteins constituting viral capsid shell. Corresponding density distribution function which generates the positions has universal form without any fitting parameter. The theory describes in a uniform way both the structures satisfying the well-known Caspar and Klug geometrical model for capsid construction and those violating it. The quasiequivalence of protein environments in viral capsid and peculiarities of the assembly thermodynamics are also discussed.Comment: 8 pages, 3 figur