4,913 research outputs found

    Perhaps Psychology’s Replication Crisis is a Theoretical Crisis that is Only Masquerading as a Statistical One

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    The “replication crisis” may well be the single most important challenge facing empirical psychological research today. It appears that highly trained scientists, often without understanding the potentially dire long-term implications, have been mishandling standard statistical procedures in the service of attaining statistical “significance.” Exacerbating the problem, most academic journals do not publish research that has not produced a “significant” result. This toxic combination has resulted in journals apparently publishing many Type I errors and declining to publish many true failures to reject H0. In response, there has been an urgent call from some psychologists that studies be registered in advance so that their rationales, hypotheses, variables, sample sizes, and statistical analyses are recorded in advance, leaving less room for post hoc manipulation. In this chapter, I argue that this “open science” approach, though laudable, will prove insufficient because the null hypothesis significance test (NHST) is a poor criterion for scientific truth, even when it is handled correctly. The root of the problem is that, whatever statistical problems psychology may have, the discipline never developed the theoretical maturity required. For decades it has been satisfied testing weak theories that predict, at best, only the direction of the effect, rather than the size of effect. Indeed, uncritical acceptance of NHST by the discipline may have served to stunt psychology’s theoretical growth by giving researchers a way of building a successful career without having to develop models that make precise predictions. Improving our statistical “hygiene” would be a good thing, to be sure, but it is unlikely to resolve psychology’s growing credibility problem until our theoretical practices mature considerably

    Placental alkaline phosphatase activity is inversely related to cell growth rate in HeLaS3 cervical cancer cells

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    AbstractPlacental alkaline phosphatase is an inducible enzyme, expressed in HeLaS3 cells, which has been shown to possess protein phosphotyrosine phosphatase activity. Since phosphotyrosine levels are known to increase in actively dividing cells we sought an inverse correlation between PLAP activity and growth rate in HeLaS3 cells. We found that PLAP inducers, Na-butyrate, dexamethasone, bromodeoxyuridine and dibutyryl cAMP caused a dose-dependent reduction in growth rate. Mimosine, an agent that blocks the cell cycle in Gl, caused an increase in PLAP activity whilst the mitogen EGF caused a corresponding decrease in PLAP activity. PLAP activity may therefore be related to cell proliferation rate

    Southern expansion of the brown alga Colpomenia peregrina Sauvageau (Scytosiphonales) in the Northwest Atlantic Ocean

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    Blackler first recorded Colpomenia peregrina in the Northwest Atlantic based on collections from Nova Scotia, Canada. Five decades later we found large quantities of C. peregrina in Maine, USA, even though it was absent during earlier floristic studies in this region. Thus, C. peregrina has undergone a rapid southern expansion along the Northwest Atlantic coast. While the causes of such an expansion are unknown, it could have a major effect on both shellfish cultivation and native seaweeds within New England because of competitive interactions and increased drag

    U(2) Flavor Physics without U(2) Symmetry

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    We present a model of fermion masses based on a minimal, non-Abelian discrete symmetry that reproduces the Yukawa matrices usually associated with U(2) theories of flavor. Mass and mixing angle relations that follow from the simple form of the quark and charged lepton Yukawa textures are therefore common to both theories. We show that the differing representation structure of our horizontal symmetry allows for new solutions to the solar and atmospheric neutrino problems that do not involve modification of the original charged fermion Yukawa textures, or the introduction of sterile neutrinos.Comment: 12 pages RevTeX, 1 eps figure. A few typos correcte

    System Modeling of Lunar Oxygen Production: Mass and Power Requirements

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    A systems analysis tool for estimating the mass and power requirements for a lunar oxygen production facility is introduced. The individual modeling components involve the chemical processing and cryogenic storage subsystems needed to process a beneficiated regolith stream into liquid oxygen via ilmenite reduction. The power can be supplied from one of six different fission reactor-converter systems. A baseline system analysis, capable of producing 15 metric tons of oxygen per annum, is presented. The influence of reactor-converter choice was seen to have a small but measurable impact on the system configuration and performance. Finally, the mission concept of operations can have a substantial impact upon individual component size and power requirements

    Numerical parameter survey of non-radiative black hole accretion: flow structure and variability of the rotation measure

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    We conduct a survey of numerical simulations to probe the structure and appearance of non-radiative black hole accretion flows like the supermassive black hole at the Galactic Centre. We find a generic set of solutions, and make specific predictions for currently feasible rotation measure (RM) observations, which are accessible to current instruments including the Expanded Very Large Array (EVLA), Giant Metrewave Radio Telescope (GMRT) and Atacama Large Millimeter Array (ALMA). The slow time variability of the RM is a key quantitative signature of this accretion flow. The time variability of RM can be used to quantitatively measure the nature of the accretion flow, and to differentiate models. Sensitive measurements of RM can be achieved using RM synthesis or using pulsars. Our energy conserving ideal magnetohydrodynamical simulations, which achieve high dynamical range by means of a deformed-mesh algorithm, stretch from several Bondi radii to about one-thousandth of that radius, and continue for tens of Bondi times. Magnetized flows which lack outward convection possess density slopes around −1, almost independent of physical parameters, and are more consistent with observational constraints than are strongly convective flows. We observe no tendency for the flows to become rotationally supported in their centres, or to develop steady outflow. We support these conclusions with formulae which encapsulate our findings in terms of physical and numerical parameters. We discuss the relation of these solutions to other approaches. The main potential uncertainties are the validity of ideal magnetohydrodynamic and the absence of a fully relativistic inner boundary condition. The RM variability predictions are testable with current and future telescope

    Evaluating diabetes and hypertension disease causality using mouse phenotypes

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    <p>Abstract</p> <p>Background</p> <p>Genome-wide association studies (GWAS) have found hundreds of single nucleotide polymorphisms (SNPs) associated with common diseases. However, it is largely unknown what genes linked with the SNPs actually implicate disease causality. A definitive proof for disease causality can be demonstration of disease-like phenotypes through genetic perturbation of the genes or alleles, which is obviously a daunting task for complex diseases where only mammalian models can be used.</p> <p>Results</p> <p>Here we tapped the rich resource of mouse phenotype data and developed a method to quantify the probability that a gene perturbation causes the phenotypes of a disease. Using type II diabetes (T2D) and hypertension (HT) as study cases, we found that the genes, when perturbed, having high probability to cause T2D and HT phenotypes tend to be hubs in the interactome networks and are enriched for signaling pathways regulating metabolism but not metabolic pathways, even though the genes in these metabolic pathways are often the most significantly changed in expression levels in these diseases.</p> <p>Conclusions</p> <p>Compared to human genetic disease-based predictions, our mouse phenotype based predictors greatly increased the coverage while keeping a similarly high specificity. The disease phenotype probabilities given by our approach can be used to evaluate the likelihood of disease causality of disease-associated genes and genes surrounding disease-associated SNPs.</p

    Tissue Distribution and Maternal Transfer of Mercury in Diamondback Terrapins with Implications for Human Health

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    2010 S.C. Water Resources Conferences - Science and Policy Challenges for a Sustainable Futur
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