8,210 research outputs found

    The Production Rate and Employment of Ph.D. Astronomers

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    In an effort to encourage self-regulation of the astronomy job market, I examine the supply of, and demand for, astronomers over time. On the supply side, I document the production rate of Ph.D. astronomers from 1970 to 2006 using the UMI Dissertation Abstracts database, along with data from other independent sources. I compare the long-term trends in Ph.D. production with federal astronomy research funding over the same time period, and I demonstrate that additional funding is correlated with higher subsequent Ph.D. production. On the demand side, I monitor the changing patterns of employment using statistics about the number and types of jobs advertised in the AAS Job Register from 1984 to 2006. Finally, I assess the sustainability of the job market by normalizing this demand by the annual Ph.D. production. The most recent data suggest that there are now annual advertisements for about one postdoctoral job, half a faculty job, and half a research/support position for every new domestic Ph.D. recipient in astronomy and astrophysics. The average new astronomer might expect to hold up to 3 jobs before finding a steady position.Comment: 5 pages, 4 figures, 2 tables, PASP accepte

    Function and dysfunction of fatty acid mobilization: a review

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    Western populations have a growing obesity epidemic due in part to excessive nutrient intake from high-fat diets, which are increasingly common. Overindulgence of nutrients is associated with a greater incidence of metabolic dysfunction and a greater risk for obesity, diabetes, hypertension, and other metabolic disorders that lower quality of life. Research in humans and animal models has improved our understanding of how excess circulating free fatty acids negatively impact the ability of muscle and other tissues to regulate nutrient uptake and utilization. It is generally accepted by the scientific community that excess circulating fatty acids lead to insulin resistance, but there is little clarity regarding the underlying mechanisms. In the present review, we will outline the current understanding of the characteristics associated with fatty acid mobilization and fatty acid utilization within specific tissues. We will also discuss the potential mechanistic role of hyperlipidemia on metabolic dysfunction associated with type 2 diabetes

    Experimental demonstration of stimulated polarization wave in a chain of nuclear spins

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    A stimulated wave of polarization, which implements a simple mechanism of quantum amplification, is experimentally demonstrated in a chain of four J-coupled nuclear spins, irradiated by a weak radio-frequency transverse field. The "quantum domino" dynamics, a wave of flipped spins triggered by a flip of the first spin, has been observed in fully 13^{13}C-labeled sodium butyrate.Comment: 8 pages including 3 figure

    New parametrization method for dissipative particle dynamics

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    We introduce an improved method of parameterizing the Groot-Warren version of Dissipative Particle Dynamics (DPD) by exploiting a correspondence between DPD and Scatchard-Hildebrand regular solution theory. The new parameterization scheme widens the realm of applicability of DPD by first removing the restriction of equal repulsive interactions between like beads, and second, by relating all conservative interactions between beads directly to cohesive energy densities. We establish the correspondence by deriving an expression for the Helmoltz free energy of mixing obtaining a heat of mixing which is exactly the same form as that for a regular mixture (quadratic in the volume fraction) and an entropy of mixing which reduces to the ideal entropy of mixing for equal molar volumes. We equate the conservative interaction parameters in the DPD force law to the cohesive energy densities of the pure fluids providing an alternative method of calculating the self-interaction parameters as well as a route to the cross-interaction parameter. We validate the new parameterization by modelling the binary system: SnI4/SiCl4, which displays liquid-liquid coexistence below an upper critical solution temperature around 140°C. A series of DPD simulations were conducted at a set of temperatures ranging from 0°C to above the experimental upper critical solution temperature using conservative parameters based on extrapolated experimental data. These simulations can be regarded as being equivalent to a quench from a high temperature to a lower one at constant volume. Our simulations recover the expected phase behaviour ranging from solid-liquid coexistence to liquid-liquid co-existence and eventually leading to a homogeneous single phase system. The results yield a binodal curve in close agreement with one predicted using regular solution theory, but, significantly, in closer agreement with actual solubility measurements

    Baptism by Fire: Ireland, The Easter Rising of 1916 and Its Experiment with Radical Republicanism

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    The Easter Uprising of 1916 represents one of the most tumultuous moments in modern Irish history. A relatively small group of revolutionaries sought to throw off the shackles of British rule in favor of Irish independence and self-determination. The uprising, lasting a mere six days, transformed the very nature of relations between Great Britain and the Irish populace. The Rising resulted in wholesale changes in legislation including women gaining the right to vote and run for office. Ireland following the uprising was completely transformed as its populace reeled with its effects. This paper examines the immediate build-up to the uprising all the way through to its conclusion including the ramifications. The paper utilizes numerous sources from contemporary studies as well as two books penned by people who experienced the chaos that was Dublin firsthand

    Cloning, Purification, and Biochemical Characterization of Human Prolyl Endopeptidase

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    Eurygaster integriceps Puton, common name sunn Pest, is one of the primary sources of wheat crop wastes in North Africa, Middle East, and Eastern Europe. It feeds by injecting the wheat grain with an enzyme characterized as prolyl endoprotease (spPEP) that breaks down Gluten, the wheat’s main constitutive protein necessary for bread production (Darkoh et al., 2010). Previously, it has been shown that peptides isolated from Lactobacillus hydrolysates of caseins in bovine milk are able to inhibit mammalian PEP in colon cells, as well as bacterial PEP (Juillerat-Jeanneret et al., 2010). While recombinant versions of these peptides are also potential inhibitors of the spPEP, their specificity must be tested also against hPEP. The primary objective of this study was to clone hPEP into the same expression vector as spPEP in order to compare hPEP to spPEP with regards to substrate binding, recognition, and inhibition. Initially, hPEP was PCR amplified in order to incorporate the 5’ and 3’ ends necessary for ligation independent cloning (LIC) into the expression vector. This was then expressed in BL21(DE3)/pTFs and purified on a nickel column. Future studies will include comparing inhibition between hPEP and spPEP using 16 PCR amplified fragments of varying length that contain the non-allergenic (as demonstrated by Ruiter, 2005) inhibitory sequence LNENLLRFFVAPFPEVFG, isolated from bovine αS1 casein
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