439 research outputs found

    A Compensating Differential Approach to Valuing the Social Benefit of Minor League Baseball

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    This research utilizes a compensating differential framework to measure the social benefits of minor league baseball teams. Consistent with findings at the major league level, individual housing observations from 138 metropolitan areas between 1993 and 2005 show that affiliated teams are associated with a significant 5.7% increase in rents in mid-sized markets ranging from 0.4 to 1.4 million people. On the other hand, independent teams and stadiums are associated with insignificant effects on rents. The positive effect of affiliated minor league teams suggests they are a valuable urban amenity that can contribute to local quality of life

    Structural plasticity of the selectivity filter in a nonselective ion channel

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    The sodium potassium ion channel (NaK) is a nonselective ion channel that conducts both sodium and potassium across the cellular membrane. A new crystallographic structure of NaK reveals conformational differences in the residues that make up the selectivity filter between the four subunits that form the ion channel and the inner helix of the ion channel. The crystallographic structure also identifies a side-entry, ion-conduction pathway for Na+ permeation that is unique to NaK. NMR studies and molecular dynamics simulations confirmed the dynamical nature of the top part of the selectivity filter and the inner helix in NaK as also observed in the crystal structure. Taken together, these results indicate that the structural plasticity of the selectivity filter combined with the dynamics of the inner helix of NaK are vital for the efficient conduction of different ions through the non-selective ion channel of NaK

    Anaerobic biodegradation of oleic and palmitic acids : evidence of mass transfer limitations caused by long chain fatty acid accumulation onto the anaerobic sludge

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    Palmitic acid was the main long chain fatty acids (LCFA) that accumulated onto the anaerobic sludge when oleic acid was fed to an EGSB reactor. The conversion between oleic and palmitic acid was linked to the biological activity. When palmitic acid was fed to an EGSB reactor it represented also the main LCFA that accumulated onto the sludge. The way of palmitic acid accumulation was different in the oleic and in the palmitic acid fed reactors.Whenoleic acid was fed, the biomass-associated LCFA (83% as palmitic acid) were mainly adsorbed and entrapped in the sludge that became ‘‘encapsulated’’ by an LCFA layer. However, when palmitic acid was fed, the biomass-associated LCFA (the totality as palmitic acid) was mainly precipitated in white spots like precipitates in between the sludge, which remained ‘‘non-encapsulated.’’ The two sludges were compared in terms of the specific methanogenic activity (SMA) in the presence of acetate, propionate, butyrate, and H2CO2, before and after the mineralization of similar amounts of biomassassociated LCFA (4.6 and 5.2 g COD-LCFA/g of volatile suspended solids (VSS), for the oleic and palmitic acid fed sludge, respectively). The ‘‘non-encapsulated,’’ sludge exhibited a considerable initial methanogenic activity on all the tested substrates, with the single exception of butyrate. However, with the ‘‘encapsulated’’ sludge only methane production from ethanol andH2/CO2 was detected, after a lag phase of about 50 h. After mineralization of the biomass-associated LCFA, both sludges exhibited activities of similar order of magnitude in the presence of the same individual substrates and significantly higher than before. The results evidenced that LCFA accumulation onto the sludge can create a physical barrier and hinder the transfer of substrates and products, inducing a delay on the initial methane production. Whatever the mechanism, metabolic or physical, that is behind this inhibition, it is reversible, being eliminated after the depletion of the biomass-associated LCFA.Fundação para a Ciência e Tecnologia (FCT) Fundo Social Europeu (FSE

    Microbial and operational response of an anaerobic fixed bed digester to oleic acid overloads

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    The effect of oleic acid overloads on biomass accumulation and activity in an anaerobic filter was investigated. An anaerobic fixed-bed reactor specially designed to allow the regular withdrawal of accumulated biomass was used for that purpose. Organic and hydraulic shocks were performed during four days, by stepwise increasing the substrate concentration from 4000 to 20 000 mg COD/l or by reducing the hydraulic retention time from 16 to 3.2 h. During the organic shock, operational performance was more affected than in the hydraulic one, which was the result of the higher degree of inhibition detected in the acetoclastic, hydrogenophilic and syntrophic activities. The ratio adhered/total biomass remained between 17 and 32% during the hydraulic shock, and between 13 and 60% during the organic shock, suggesting a more stable biofilm during the hydraulic shock. A long time (900 h) after the hydraulic shock, hydrogenophilic and syntrophic activities recovered to higher values than before the shock, but after the organic shock only acetoclastic activity recovered pre-shock values. Hydraulic shock induced an increase in tolerance to oleic acid toxicity, evidenced by an increase in the toxicity limit (IC50) from 140+/-30 to 215+/-25 mg/l.Fundação de Ciência e Tecnologia

    Tensions of colonial punishment: perspectives on recent developments in the study of coercive networks in Asia, Africa and the Caribbean

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    The study of penal practices in colonised parts of Asia, Africa, Latin America, the Indian Ocean and the Caribbean has recently witnessed a significant shift. The first generation of research into the coercive measures of colonial states tended to focus rather narrowly on imprisonment. The second generation, which has emerged only in the last five years, has significantly widened their field of vision to incorporate much more than the prison. The most recent literature considers capital and corporal punishment, as well as the larger functioning of police and courts. It also explores in more depth the ways in which indigenous peoples experienced and interpreted their punishments. Finally, this new research is sensitive to the paradoxes and tensions of colonial punishment, which often frustrated its purposes. This article reflects upon these historiographical shifts, and argues that, in light of these developments, a new framework for the study of colonial punishment is now called for. It suggests that an approach which views colonial coercive techniques as part of imperial ‘coercive networks’ encapsulates this new thinking

    Recombinant Fibrinogen Vlissingen/Frankfurt IV: THE DELETION OF RESIDUES 319 AND 320 FROM THE γ CHAIN OF FIBRINOGEN ALTERS CALCIUM BINDING, FIBRIN POLYMERIZATION, CROSS-LINKING, AND PLATELET AGGREGATION

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    We synthesized a variant, recombinant fibrinogen modeled after the heterozygous dysfibrinogen Vlissingen/Frankfurt IV, a deletion of two residues, gammaAsn-319 and gammaAsp-320, located within the high affinity calcium-binding pocket. Turbidity studies showed no evidence of fibrin polymerization, although size exclusion chromatography, transmission electron microscopy, and dynamic light scattering studies showed small aggregates. These aggregates did not resemble normal protofibrils nor did they clot. Fibrinopeptide A release was normal, whereas fibrinopeptide B release was delayed approximately 3-fold. Plasmin cleavage of this fibrinogen was not changed by the presence of calcium or Gly-Pro-Arg-Pro, indicating that both the calcium-binding site and the "a" polymerization site were non-functional. We conclude that the loss of normal polymerization was due to the lack of "A-a" interactions. Moreover, functions associated with the C-terminal end of the gamma chain, such as platelet aggregation and factor XIII cross-linking, were also disrupted, suggesting that this deletion of two residues affected the overall structure of the C-terminal domain of the gamma chain

    Selective Extraction and in Situ Reduction of Precious Metal Salts from Model Waste to Generate Hybrid Gels with Embedded Electrocatalytic Nanoparticles

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    A hydrogel based on 1,3:2,4-dibenzylidenesorbitol (DBS), modified with acyl hydrazides which extracts gold/silver salts from model waste is reported, with preferential uptake of precious heavy metals over other common metals. Reduction of gold/silver salts occurs spontaneously in the gel to yield metal nanoparticles located on the gel nanofibers. High nanoparticle loadings can be achieved, endowing the gel with electrochemical activity. These hybrid gels exhibit higher conductances than gels doped with carbon nanotubes, and can be used to modify electrode surfaces, enhancing electrocatalysis. We reason this simple, industrially and environmentally relevant approach to conducting materials is of considerable significance
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