4,517 research outputs found

    Protective activity of aromatic amines and imines against oxidative nerve cell death

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    Oxidative stress is a widespread phenomenon in the pathology of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Neuronal cell death due to oxidative stress may causally contribute to the pathogeneses of these diseases. Therefore, neuroprotective antioxidants are considered to be a promising approach to slow down disease progression. We have investigated different aromatic amine and imine compounds for neuroprotective antioxidant functions in cell culture, and found that these compounds possess excellent cytoprotective potential in diverse paradigms of oxidative neuronal cell death, including clonal cell lines, primary cerebellar neurons, and organotypic hippocampal slice cultures. Aromatic amines and imines are effective against oxidative glutamate toxicity, glutathione depletion, and hydrogen peroxide toxicity. Their mode of action as direct antioxidants; was experimentally confirmed by electron spin resonance spectroscopy, cell-free brain lipid peroxidation assays, and intracellular peroxide measurements. With half-maximal effective concentrations of 20-75 nm in different neuroprotection experiments, the aromatic imines phenothiazine, phenoxazine, and iminostilbene proved to be about two orders of magnitude more effective than common phenolic antioxidants. This remarkable efficacy could be directly correlated to calculated properties of the compounds by means of a novel, quantitative structure-activity relationship model. We conclude that bridged bisarylimines with a single free NH-bond, such as iminostilbene, are superior neuroprotective antioxidants, and may be promising lead structures for rational drug development

    Speed-dependent collision effects on radar back-scattering from the ionosphere

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    The question whether the differences between fluctuation spectra for linearly speed-dependent and speed-independent collision frequencies could account for disagreements between rocket and incoherent scatter estimate was addressed. The basic theory used for computing the fluctuation spectrum is outlined. The speed-dependence of the charge-neutral collision frequency is discussed, with special emphasis on its derivation from the mobility measurements. Various developments of the computer code used for the computation of the fluctuation spectrum are described. The range of values of input parameters typical to the collision-dominated ionosphere are briefly described. The computational results are presented, and the significance and limitation of these results and the future scope of the research are discussed

    In-Stent Restenosis after Carotid Stenting

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    Carotid artery stenosis is a major risk factor for ischemic stroke. Currently, carotid endarterectomy (CEA) is the surgical treatment of choice for carotid artery stenosis. Carotid artery stenting (CAS) increases the risk of carotid artery stenosis. CAS is one of the treatment options available, particularly for high-risk CEA patients. Although CAS has the advantages of being less invasive, causing less patient discomfort, and requiring a shorter hospital stay, some patients may develop in-stent restenosis (ISR). ISR is closely related to clinical events such as transient ischemic attacks and ischemic stroke recurrence. The author examines the mechanism, influencing factors, and research progress of ISR following CAS, as well as its prevention and treatment, in order to provide clinical insights for clinicians

    Alpha MAML: Adaptive Model-Agnostic Meta-Learning

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    Model-agnostic meta-learning (MAML) is a meta-learning technique to train a model on a multitude of learning tasks in a way that primes the model for few-shot learning of new tasks. The MAML algorithm performs well on few-shot learning problems in classification, regression, and fine-tuning of policy gradients in reinforcement learning, but comes with the need for costly hyperparameter tuning for training stability. We address this shortcoming by introducing an extension to MAML, called Alpha MAML, to incorporate an online hyperparameter adaptation scheme that eliminates the need to tune meta-learning and learning rates. Our results with the Omniglot database demonstrate a substantial reduction in the need to tune MAML training hyperparameters and improvement to training stability with less sensitivity to hyperparameter choice.Comment: 6th ICML Workshop on Automated Machine Learning (2019

    Being Focused: When the Purpose of Inference Matters for Model Selection

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    In contrast to conventional model selection criteria, the Focused Information Criterion (FIC) allows for purpose-specifi c choice of models. This accommodates the idea that one kind of model might be highly appropriate for inferences on a particular parameter, but not for another. Ever since its development, the FIC has been increasingly applied in the realm of statistics, but this concept appears to be virtually unknown in the economic literature. Using a classical example and data for 35 U.S. industry sectors (1960–2005), this paper provides for an illustration of the FIC and a demonstration of its usefulness in empirical applications.Information Criteria; translog cost function; cross-price elasticities

    Diversity effects on ecosystem processes

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    Surgical Treatment of Severe Carotid Artery Stenosis in Conjunction with Coronary Artery Stenosis

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    Patients who suffer from atherosclerosis disease frequently experience coronary heart disease in addition to carotid atherosclerotic stenosis as a complication of their condition. It is of the utmost importance to identify a course of treatment that will optimize the benefits for patients who are suffering from both diseases at the same time and need to undergo surgical intervention. In this review, surgical treatments and perspectives on carotid artery stenosis and coronary artery stenosis were discussed in conjunction with one another

    Choice is Suffering: A Focused Information Criterion for Model Selection Activation Program for Disadvantaged Youths

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    In contrast to conventional measures, the Focused Information Criterion (FIC) allows the purpose-specific selection of models, thereby reflecting the idea that one kind of model might be appropriate for inferences on a parameter of interest, but not for another. Ever since its invention, the FIC has been increasingly applied in the realm of statistics, but this concept appears to be virtually unknown in the economic literature. Using a straightforward analytical example, this paper provides for a didactic illustration of the FIC and shows its usefulness in economic applications.AKAIKE Information Criterion; SCHWARZ Information Criterion; Translog Cost Function

    SUPERMARKET CHARACTERISTICS AND OPERATING COSTS IN LOW-INCOME AREAS

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    Whether the poor pay more for food than other income groups is an important question in food price policy research. Stores serving low-income shoppers differ in important ways from stores that receive less of their revenues from Food Stamp redemptions. Stores with more revenues from Food Stamps are generally smaller and older, and offer relatively fewer convenience services for shoppers. They also offer a different mix of products, with a relatively high portion of sales coming from meat and private-label products. Metro stores with high Food Stamp redemption rates lag behind other stores in the adoption of progressive supply chain and human resource practices. Finally, stores with the highest Food Stamp redemption rates have lower sales margins relative to other stores, but have significantly lower payroll costs as a percentage of sales. Overall, operating costs for stores with high Food Stamp redemption rates are not significantly different from those for stores with moderate Food Stamp redemption rates. If the poor do pay more, factors other than operating costs are likely to be the reason.Food prices, supermarkets, low-income consumers, Food Stamps, metro, nonmetro, Marketing,
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