4,880 research outputs found

    Learning intrinsic excitability in medium spiny neurons

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    We present an unsupervised, local activation-dependent learning rule for intrinsic plasticity (IP) which affects the composition of ion channel conductances for single neurons in a use-dependent way. We use a single-compartment conductance-based model for medium spiny striatal neurons in order to show the effects of parametrization of individual ion channels on the neuronal activation function. We show that parameter changes within the physiological ranges are sufficient to create an ensemble of neurons with significantly different activation functions. We emphasize that the effects of intrinsic neuronal variability on spiking behavior require a distributed mode of synaptic input and can be eliminated by strongly correlated input. We show how variability and adaptivity in ion channel conductances can be utilized to store patterns without an additional contribution by synaptic plasticity (SP). The adaptation of the spike response may result in either "positive" or "negative" pattern learning. However, read-out of stored information depends on a distributed pattern of synaptic activity to let intrinsic variability determine spike response. We briefly discuss the implications of this conditional memory on learning and addiction.Comment: 20 pages, 8 figure

    Highest weight Macdonald and Jack Polynomials

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    Fractional quantum Hall states of particles in the lowest Landau levels are described by multivariate polynomials. The incompressible liquid states when described on a sphere are fully invariant under the rotation group. Excited quasiparticle/quasihole states are member of multiplets under the rotation group and generically there is a nontrivial highest weight member of the multiplet from which all states can be constructed. Some of the trial states proposed in the literature belong to classical families of symmetric polynomials. In this paper we study Macdonald and Jack polynomials that are highest weight states. For Macdonald polynomials it is a (q,t)-deformation of the raising angular momentum operator that defines the highest weight condition. By specialization of the parameters we obtain a classification of the highest weight Jack polynomials. Our results are valid in the case of staircase and rectangular partition indexing the polynomials.Comment: 17 pages, published versio

    One- and two-proton transfer reactions with vibrational Nuclei

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    We extend a semiclassical model of transfer reactions to the case in which one of the collision partners is a vibrational nucleus. The model is applied to one- and two-proton stripping reactions in the 37Cl + 98Mo system, for which a rapid transition from normal to anomalous slope in the two proton transfer reaction at energies around the Coulomb barrier is experimentally observed. This behavior is satisfactorily reproduced by the present extension of the model.Comment: LaTeX, 10 pages, 1 figure (PostScript

    Daily distribution of carbohydrate, protein and fat intake in elite youth academy soccer players over a 7-day training period

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    While traditional approaches to dietary analysis in athletes have focused on total daily energy and macronutrient intake, it is now thought that daily distribution of these parameters can also influence training adaptations. Using seven-day food diaries, we quantified the total daily macronutrient intake and distribution in elite youth soccer players from the English Premier League in U18 (n=13), U15/16 (n=25) and U13/14 squads (n=21). Total energy (43.1±10.3, 32.6±7.9, 28.1±6.8 kcal∙kg-1∙day-1), CHO (6±1.2, 4.7±1.4, 3.2±1.3 g∙kg-1∙day-1) and fat (1.3±0.5, 0.9±0.3, 0.9±0.3 g∙kg-1∙day-1) intake exhibited hierarchical differences (PU15/16>U18. Additionally, CHO intake in U18s was lower (P lunch (~0.5 g∙kg-1) > breakfast (~0.3 g∙kg-1). We conclude elite youth soccer players do not meet current CHO guidelines. Although daily protein targets are achieved, we report a skewed daily distribution in all ages such that dinner>lunch>breakfast. Our data suggest that dietary advice for elite youth players should focus on both total daily macronutrient intake and optimal daily distribution patterns

    From molecules to management: adopting DNA-based methods for monitoring biological invasions in aquatic environments

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    a b s t r a c t Recent technological advances have driven rapid development of DNA-based methods designed to facilitate detection and monitoring of invasive species in aquatic environments. These tools promise to improve on traditional monitoring approaches by enhancing detection sensitivity, reducing analytical turnaround times and monitoring costs, and increasing specificity of target identifications. However, despite the promise of DNA-based monitoring methods, the adoption of these tools in decision-making frameworks remains challenging. Here, rather than explore technical aspects of method development, we examine impediments to effective translation of those methods into management contexts. In addition to surveying current use of DNA-based tools for aquatic invasive species monitoring, we explore potential sources of uncertainty associated with molecular technologies and possibilities for limiting that uncertainty and effectively communicating its implications for decision-making. We pay particular attention to the recent adoption of DNA-based methods for detection of invasive Asian carp species in the United States Great Lakes region, as this example illustrates many of the challenges associated with applying molecular tools to achieve desired management outcomes. Our goal is to provide a useful assessment of the obstacles associated with integrating DNA-based methods into aquatic invasive species management, and to offer recommendations for future efforts aimed at overcoming those obstacles. Published by Elsevier Inc

    The practice of commissioning healthcare from a private provider: learning from an in-depth case study

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    Background: The direction of health service policy in England is for more diversification in the design, commissioning and provision of health care services. The case study which is the subject of this paper was selected specifically because of the partnering with a private sector organisation to manage whole system redesign of primary care and to support the commissioning of services for people with long term conditions at risk of unplanned hospital admissions and associated service provision activities. The case study forms part of a larger Department of Health funded project on the practice of commissioning which aims to find the best means of achieving a balance between monitoring and control on the one hand, and flexibility and innovation on the other, and to find out what modes of commissioning are most effective in different circumstances and for different services. Methods: A single case study method was adopted to explore multiple perspectives of the complexities and uniqueness of a public-private partnership referred to as the “Livewell project”. 10 single depth interviews were carried out with key informants across the GP practices, the PCT and the private provider involved in the initiative. Results: The main themes arising from single depth interviews with the case study participants include a particular understanding about the concept of commissioning in the context of primary care, ambitions for primary care redesign, the importance of key roles and strong relationships, issues around the adoption and spread of innovation, and the impact of the current changes to commissioning arrangements. The findings identified a close and high trust relationship between GPs (the commissioners) and the private commissioning support and provider firm. The antecedents to the contract for the project being signed indicated the importance of leveraging external contacts and influence (resource dependency theory). Conclusions: The study has surfaced issues around innovation adoption in the healthcare context. The case identifies ‘negotiated order’, managerial performance of providers and disciplinary control as three media of power used in combination by commissioners. The case lends support for stewardship and resource dependency governance theories as explanations of the underpinning conditions for effective commissioning in certain circumstances within a quasi marketised healthcare system
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