4,171 research outputs found

    Glucose-targeted niosomes deliver vasoactive intestinal peptide (VIP) to the brain

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    The aim of this study was to evaluate glucose-bearing niosomes as a brain targeted delivery system for the vasoactive intestinal peptide (VIP). To this end, VIP/125I-VIP-loaded glucose-bearing niosomes were intravenously injected to mice. Brain uptake was determined by measuring the radioactivity of 125I-labeled VIP using gamma-counting, after intravenous administration of VIP in solution or encapsulated in glucose-bearing niosomes or in control niosomes. VIP integrity was assessed by reversed-phase HPLC analysis of brain extracts. Distribution of 125I-VIP derived radioactivity was examined from serial brain slices. HPLC analysis confirmed the presence of intact VIP in brain after administration of VIP-loaded niosomes, but not after administration of VIP solution. Encapsulation within glucose-bearing niosomes mainly allowed a significantly higher VIP brain uptake compared to control niosomes (up to 86%, 5min after treatment). Brain distribution of intact VIP after injection of glucose-bearing niosomes, indicated that radioactivity was preferentially located in the posterior and the anterior parts of the brain, whereas it was homogeneously distributed in the whole brain after the administration of control vesicles. In conclusion, this novel vesicular formulation of VIP delivers intact VIP to particular brain regions in mice. Glucose-bearing vesicles might be therefore a novel tool to deliver drugs across the blood-brain barrier (BBB)

    The accumulation of foreign reserves

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    In a number of countries, especially emerging market economies, the public sector has in recent years been accumulating sizeable cross-border financial assets, mainly in the form of official foreign exchange reserves. World reserves have risen from USD 1.2 trillion in January 1995 to above USD 4 trillion in September 2005, growing particularly rapidly since 2002. This paper investigates the features, drivers, risks and costs of such recent reserve accumulation, as well as the other uses that certain countries have been making of their accumulated foreign assets. The main trends in central bank reserve management are also reviewed. Finally, the paper provides some evidence for the impact of reserve accumulation on yields and asset prices. JEL Classification:Foreign exchange reserves, exchange rates, emerging market economies.

    Experimental creep behaviour determination of cladding tube materials under multi-axial loadings

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    Cladding tubes are structural parts of nuclear plants, submitted to complex thermomechanical loadings. Thus, it is necessary to know and predict their behaviour to preserve their integrity and to enhance their lifetime. Therefore, a new experimental device has been developed to control the load path under multi-axial load conditions. The apparatus is designed to determine the thermomechanical behaviour of zirconium alloys used for cladding tubes. First results are presented. Creep tests with different biaxial loadings were performed. Results are analysed in terms of thermal expansion and of creep strain. The anisotropy of the material is revealed and iso-creep strain curves are given

    The Beauty Industry\u27s Influence on Women in Society

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    There has been a significant amount of research done on the effect that advertising in the fashion and beauty industry has on women. By creating advertisements with unrealistic images of beauty, it has resulted in anxiety, low self-esteem, and low self-confidence in many women. Most of these negative emotions stems from unhappiness among body and appearance. Less research has been performed relating to cosmetics and how this can have an influence on women, and how women can use cosmetics to manipulate their appearance. This paper first discusses the existing research that focuses on the cosmetic industry’s influence on women. From this research, a general survey was created in order to gather general information about a group of college student’s cosmetic usage, habits, and beliefs. The results indicate that college women are high users of cosmetics, are very aware of the cosmetic industry, and that some individual differences can have an effect on the choices a woman makes regarding cosmetics

    Envisioning Africa's future: a story of changing perceptions

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    This repository item contains a single issue of Issues in Brief, a series of policy briefs that began publishing in 2008 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future. This paper is part of the Africa 2060 Project, a Pardee Center program of research, publications and symposia exploring African futures in various aspects related to development on continental and regional scales. For more information, visit www.bu.edu/pardee/research/Perceptions about Africa will continue to influence how its future is viewed and thus shaped. The year 2010 marks the 50th anniversary of “The Year of Africa,” and as we anticipate how Africa will develop over the next 50 years, it is important to understand how perceptions of the continent have evolved in the past. This paper explores how the changing image of AFrica has influenced the thinking about its future prospects since the 1960s, and how current perceptions may influence its future development. This paper is part of the Africa 2060 Project, a Pardee Center program of research, publications, and symposia exploring African futures in various aspects related to development on continental and regional scales

    Effect of cadence selection on peak power and time of power production in elite BMX riders; a laboratory based study.

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    The aims of this study were to analyse the optimal cadence for peak power production and time to peak power in bicycle motocross (BMX) riders. Six male elite BMX riders volunteered for the study. Each rider completed 3 maximal sprints at a cadence of 80, 100, 120 and 140revs·min-1 on a laboratory Schoberer Rad Messtechnik (SRM) cycle ergometer in isokinetic mode. The riders’ mean values for peak power and time of power production in all three tests were recorded. The BMX riders produced peak power (1105±139W) at 100revs·min-1 with lower peak power produced at 80revs:min-1 (1060±69W, (F(2,15)=3.162; p=.266; η2 =0.960), 120revs·min-1 (1077±141W, (F(2,15)=4.348; p=.203; η2 =0.970) and 140revs·min-1 (1046±175W, (F(2,15)=12.350; p=0.077; η2 =0.989). The shortest time to power production was attained at 120revs·min-1 in 2.5±1.07s. Whilst a cadence of 80revs:min-1 (3.5±0.8s, (F(2,15)=2.667; p=.284; η2 =0.800) 100revs:min-1 (3.00±1.13s, (F(2,15)=24.832; p=.039; η2 =0.974) and 140revs:min-1 (3.50±0.88s, (F(2,15)=44.167; p=.006; η2 =0.967)) all recorded a longer time to peak power production. The results indicate that the optimal cadence for producing peak power output and reducing the time to peak power output are attained at comparatively low cadences for sprint cycling events. These findings could potentially inform strength and conditioning training to maximise dynamic force production and enable coaches to select optimal gear ratios

    Exploring the relationship between tychoparthenogenesis and inbreeding depression in the Desert Locust, Schistocerca gregaria

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    Tychoparthenogenesis, a form of asexual reproduction in which a small proportion of unfertilized eggs can hatch spontaneously, could be an intermediate evolutionary link in the transition from sexual to parthenogenetic reproduction. The lower fitness of tychoparthenogenetic offspring could be due to either developmental constraints or to inbreeding depression in more homozygous individuals. We tested the hypothesis that in populations where inbreeding depression has been purged, tychoparthenogenesis may be less costly. To assess this hypothesis, we compared the impact of inbreeding and parthenogenetic treatments on eight life-history traits (five measuring inbreeding depression and three measuring inbreeding avoidance) in four laboratory populations of the desert locust, Schistocerca gregaria, with contrasted demographic histories. Overall, we found no clear relationship between the population history (illustrated by the levels of genetic diversity or inbreeding) and inbreeding depression, or between inbreeding depression and parthenogenetic capacity. First, there was a general lack of inbreeding depression in every population, except in two populations for two traits. This pattern could not be explained by the purging of inbreeding load in the studied populations. Second, we observed large differences between populations in their capacity to reproduce through tychoparthenogenesis. Only the oldest laboratory population successfully produced parthenogenetic offspring. However, the level of inbreeding depression did not explain the differences in parthenogenetic success between all studied populations. Differences in development constraints may arise driven by random and selective processes between populations. (Résumé d'auteur

    Equilibrium Predictions in Wholesale Electricity Markets

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    We review supply function equilibrium models and their predictions on market outcomes in the wholesale electricity auctions. We discuss how observable market characteristics such as capacity constraints, number of power suppliers, load distribution and auction format affect the behavior of suppliers and performance of the market. We specifically focus on the possible market power exerted by pivotal suppliers and the comparison between discriminatory and uniform-price auctions. We also describe capacity investment behavior of electricity producers in the restructured industry.Electricity markets; Supply function equilibrium; Markov perfect equilibrium; electricity auctions; pivotal suppliers; capacity investment.

    Dark cloud chemistry in initially H-rich regions

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    The chemistry in dark regions of dense cores is explored as a function of the initial abundance ratio of H to H 2, on the assumption that some cores form on a timescale and are younger than the time required for the H :H 2 ratio to attain its equilibrium value. Observational diagnostics of non-equilibrium values of the initial H :H 2 ratio are identified. In initially H-rich material, the abundances of OH, NH 3, CN, and HNC are for some time higher than they are in initially H-poor material. In initially H-poor regions, the abundances of CO, species containing multiple carbon atoms in each molecule, and CS are larger for an (observationally significant) period than in initially H-rich material
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