1,491 research outputs found

    Results of a study of the stability of cointegrating relations comprised of broad monetary aggregates

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    There is strong evidence of a stable “money demand” relationship for MZM and M2 through the 1990s. Though the M2 relationship breaks down somewhere around 1990, evidence has been accumulating that the disturbance is well characterized as a permanent upward shift in M2 velocity that began around 1990 and was largely over by 1994. This paper’s results support the hypothesis that households permanently reallocated a portion of their wealth from time deposits to mutual funds. This reallocation may have been induced by depository restructuring, but it could also be explained by appropriately measured opportunity cost.Demand for money

    Esterification Prevents Induction of the Mitochondrial Permeability Transition by N-Acetyl Perfluorooctane Sulfonamides

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    N-Alkyl perfluorooctane sulfonamides have been widely used as surfactants on fabrics and papers, fire retardants, and anticorrosion agents, among many other commercial applications. The broad use, global distribution, and environmental persistence of these compounds has generated considerable interest regarding potentially toxic effects. We have previously reported that perfluorooctanesulfonamidoacetate (FOSAA) and N-ethylperfluorooctanesulfonamidoacetate (N-EtFOSAA) induce the mitochondrial permeability transition (MPT) in vitro, resulting in cytochrome c release, inhibition of respiration, and generation of reactive oxygen species. By synthesizing the corresponding methyl esters of FOSAA and N-EtFOSAA (methyl perlfuorinated sulfonamide acetates), we tested the hypothesis that the N-acetate moiety of FOSAA and N-EtFOSAA is the functional group responsible for induction of the MPT. Swelling of freshly isolated liver mitochondria from Sprague−Dawley rats was monitored spectrophotometrically and membrane potential (ΔΨ) was measured using a tetraphenylphosphonium-selective (TPP+) electrode. In the presence of calcium, 40 μM FOSAA and 7 μM N-EtFOSAA each induced mitochondrial swelling and a biphasic depolarization of membrane potential. Mitochondrial swelling and the second-phase depolarization were inhibited by cyclosporin-A or the catalyst of K+/H+ exchange nigericin, whereas the first-phase depolarization was not affected by either. In contrast, the methyl esters of FOSAA and N-EtFOSAA exhibited no depolarizing or MPT inducing activity. Results of this investigation demonstrate that the carboxylic acid moiety of the N-acetates is the active functional group, which triggers the MPT by perfluorinated sulfonamides

    On the Inadequacy of Species Distribution Models for Modelling the Spread of SARS-CoV-2: Response to Araújo and Naimi

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    The ongoing pandemic of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing significant damage to public health and economic livelihoods, and is putting significant strains on healthcare services globally. This unfolding emergency has prompted the preparation and dissemination of the article “Spread of SARS-CoV-2 Coronavirus likely to be constrained by climate” by Araújo and Naimi (2020). The authors present the results of an ensemble forecast made from a suite of species distribution models (SDMs), where they attempt to predict the suitability of the climate for the spread of SARS-CoV-2 over the coming months. They argue that climate is likely to be a primary regulator for the spread of the infection and that people in warm-temperate and cold climates are more vulnerable than those in tropical and arid climates. A central finding of their study is that the possibility of a synchronous global pandemic of SARS-CoV-2 is unlikely. Whilst we understand that the motivations behind producing such work are grounded in trying to be helpful, we demonstrate here that there are clear conceptual and methodological deficiencies with their study that render their results and conclusions invalid. What follows is a response to the Araújo and Naimi article centered around three main criticisms: 1) Given the fact that SARS-CoV-2 has a primary infection pathway of direct contact, it is in an active spreading phase, and remains largely underreported in the Global South, it represents an inappropriate system for analysis using the SDM framework. 2) Even if we were to accept that an SDM framework would be applicable here, the methodology presented in the article strays far from best-practice guidelines for the application of SDMs. 3) The dissemination strategy of the authors failed to respect the frameworks of risks adhered to in other academic disciplines pertaining to public health, resulting in erroneous but well-publicised claims with broad policy implications before any scientific oversight could be applied

    The Effect of Harvesting on Macrophyte Regrowth and Water Quality in LaDue Reservoir, Ohio

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    Two experiments in a bay of LaDue Reservoir (Geauga Co., northeastern Ohio) during summer, 1985 demonstrated that removal of Eurasian watermilfoil (Myriophyllum spicatum L.) root crowns with an aquatic weed harvester retarded plant regrowth to quantities well below nuisance levels for 28 days. Nearly summer-long control was achieved following a touch-up harvest on day 42. In contrast, the harvester was used in this bay in 1982 to mow milfoil, leaving intact stumps. The mowed plants regrew to preharvest and control area biomass levels within 23 days. The difference in plant regrowth between these two methods strongly suggests that user dissatisfaction with harvesting could be reduced by using the root crown removal technique. Root crown removal was associated with elevated levels of total phosphorus, chlorophyll, blue-green algae, and seston. The implications of milfoil control with root crown removal, and the associated water quality change, are discussed in relation to recreational and water supply uses of lakes and reservoirs

    T-infinity: The Dependency Inversion Principle for Rapid and Sustainable Multidisciplinary Software Development

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    The CFD Vision 2030 Study recommends that, NASA should develop and maintain an integrated simulation and software development infrastructure to enable rapid CFD technology maturation.... [S]oftware standards and interfaces must be emphasized and supported whenever possible, and open source models for noncritical technology components should be adopted. The current paper presents an approach to an open source development architecture, named T-infinity, for accelerated research in CFD leveraging the Dependency Inversion Principle to realize plugins that communicate through collections of functions without exposing internal data structures. Steady state flow visualization, mesh adaptation, fluid-structure interaction, and overset domain capabilities are demonstrated through compositions of plugins via standardized abstract interfaces without the need for source code dependencies between disciplines. Plugins interact through abstract interfaces thereby avoiding N 2 direct code-to-code data structure coupling where N is the number of codes. This plugin architecture enhances sustainable development by controlling the interaction between components to limit software complexity growth. The use of T-infinity abstract interfaces enables multidisciplinary application developers to leverage legacy applications alongside newly-developed capabilities. While rein, a description of interface details is deferred until the are more thoroughly tested and can be closed to modification

    Francisella Tularensis Blue–Gray Phase Variation Involves Structural Modifications of Lipopolysaccharide O-Antigen, Core and Lipid A and Affects Intramacrophage Survival and Vaccine Efficacy

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    Francisella tularensis is a CDC Category A biological agent and a potential bioterrorist threat. There is no licensed vaccine against tularemia in the United States. A long-standing issue with potential Francisella vaccines is strain phase variation to a gray form that lacks protective capability in animal models. Comparisons of the parental strain (LVS) and a gray variant (LVSG) have identified lipopolysaccharide (LPS) alterations as a primary change. The LPS of the F. tularensis variant strain gains reactivity to F. novicida anti-LPS antibodies, suggesting structural alterations to the O-antigen. However, biochemical and structural analysis of the F. tularensis LVSG and LVS LPS demonstrated that LVSG has less O-antigen but no major O-antigen structural alterations. Additionally, LVSG possesses structural differences in both the core and lipid A regions, the latter being decreased galactosamine modification. Recent work has identified two genes important in adding galactosamine (flmF2 and flmK) to the lipid A. Quantitative real-time PCR showed reduced transcripts of both of these genes in the gray variant when compared to LVS. Loss of flmF2 or flmK caused less frequent phase conversion but did not alter intramacrophage survival or colony morphology. The LVSG strain demonstrated an intramacrophage survival defect in human and rat but not mouse macrophages. Consistent with this result, the LVSG variant demonstrated little change in LD50 in the mouse model of infection. Furthermore, the LVSG strain lacks the protective capacity of F. tularensis LVS against virulent Type A challenge. These data suggest that the LPS of the F. tularensis LVSG phase variant is dramatically altered. Understanding the mechanism of blue to gray phase variation may lead to a way to inhibit this variation, thus making future F. tularensis vaccines more stable and efficacious
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