2,729 research outputs found

    Cellular mechanisms underlying burst firing in substantia nigra dopamine neurons

    Get PDF
    Burst firing of substantia nigra dopamine (SN DA) neurons is believed to represent an important teaching signal that instructs synaptic plasticity and associative learning. However, the mechanisms through which synaptic excitation overcomes the limiting effects of somatic Ca2+-dependent K+ current to generate burst firing are controversial. Modeling studies suggest that synaptic excitation sufficiently amplifies oscillatory dendritic Ca2+ and Na+ channel currents to lead to the initiation of high-frequency firing in SN DA neuron dendrites. To test this model, visually guided compartment-specific patch-clamp recording and ion channel manipulation were applied to rodent SN DA neurons in vitro. As suggested previously, the axon of SN DA neurons was typically found to originate from a large-diameter dendrite that was proximal to the soma. However, in contrast to the predictions of the model, (1) somatic current injection generated firing that was similar in frequency and form to burst firing in vivo, (2) the efficacy of glutamatergic excitation was inversely related to the distance of excitation from the axon, (3) pharmacological blockade or genetic deletion of Ca2+ channels did not prevent high-frequency firing, (4) action potential bursts were invariably detected first at sites that were proximal to the axon, and (5) pharmacological blockade of Na+ channels in the vicinity of the axon/soma but not dendritic excitation impaired burst firing. Together, these data suggest that SN DA neurons integrate their synaptic input in a more conventional manner than was hypothesized previously

    Job Satisfaction and Compassion Satisfaction Among Orthotic and Prosthetic Practitioners: A Descriptive-Multiple Case Study

    Get PDF
    Orthotic and prosthetic practitioners are faced with heavy caseloads of patients that impact symptoms of burnout, which is another word for stress. This qualitative, descriptive-multiple case study investigated Orthotic and Prosthetic (O&P) practitioners in the United States and their views on whether job satisfaction influences compassion satisfaction, while working with patients who have lost one or more limb(s). The research study also included whether burnout or depression have a significant effect on job satisfaction and compassion satisfaction. This research study was conducted using a three-phased data collection process that included in-depth interview sessions, along with researcher’s notes, a prepared open-ended questionnaire, and an online questionnaire. The participants in this study were selected using purposive sampling through a professional network and O&P professional groups. Nine participants completed the telephone interview sessions, the prepared open-ended questionnaire, and the online questionnaire. The O&P practitioners in this research study believed that job satisfaction and compassion satisfaction are complementary when working with individuals who have lost one or more limbs—both needs must be met in the workplace

    Stationary and non-stationary fluid flow of a Bose-Einstein condensate through a penetrable barrier

    Full text link
    We experimentally study the fluid flow induced by a broad, penetrable barrier moving through an elongated dilute gaseous Bose-Einstein condensate. The barrier is created by a laser beam swept through the condensate, and the resulting dipole potential can be either attractive or repulsive. We examine both cases and find regimes of stable and unstable fluid flow: At slow speeds of the barrier, the fluid flow is stationary due to the superfluidity of the condensate. At intermediate speeds, we observe a non-stationary regime in which the condensate gets filled with dark solitons. At faster speeds, soliton formation completely ceases and a remarkable absence of excitation in the condensate is seen again.Comment: 4 pages, 4 figure

    UTS Environmental Sustainability Initiative: Case Study

    Full text link
    Implementing environmental sustainability programs across university campuses presents both opportunities and challenges. The University of Technology Sydney (UTS) launched a coordinated approach to sustainability in 2008. This paper presents a case study of UTS’s Environmental Sustainability Initiative (ESI). It begins by outlining the aims and governance structures for the initiative which consists of a Sustainability Steering Committee; Committee of Working Group Heads and then working groups across six focus areas of energy, transport, procurement, water, waste, planning and design, and also reporting and communications. The paper then describes the development and consultation processes, and final outcomes, for three strategy documents in the areas of climate change (energy), transport and paper use (procurement). We discuss the role that such working groups, together with other support structures, can play in creating a more sustainable university, and offer practical guidance for other universities and organisations undergoing organisational change for sustainability. We also discuss some of the challenges that emerged such as: how to engage with staff and students to develop shared aspirations and reflect these in tangible objectives, targets and actions; and how to evolve organisational structures to implement strategies and create a sustainable higher education institution

    Cognitive modelling of language acquisition with complex networks

    Get PDF
    ABSTRACT Cognitive modelling is a well-established computational intelligence tool, which is very useful for studying cognitive phenomena, such as young children's first language acquisition. Specifically, linguistic modelling has recently benefited greatly from complex network theory by modelling large sets of empirical linguistic data as complex networks, thereby illuminating interesting new patterns and trends. In this chapter, we show how simple network analysis techniques can be applied to the study of language acquisition, and we argue that they reveal otherwise hidden information. We also note that a key network parameter -the ranked frequency distribution of the links -provides useful knowledge about the data, even though it had been previously neglected in this domain

    Cancer immunology and canine malignant melanoma: a comparative review

    Get PDF
    Oral canine malignant melanoma (CMM) is a spontaneously occurring aggressive tumour with relatively few medical treatment options, which provides a suitable model for the disease in humans. Historically, multiple immunotherapeutic strategies aimed at provoking both innate and adaptive anti-tumour immune responses have been published with varying levels of activity against CMM. Recently, a plasmid DNA vaccine expressing human tyrosinase has been licensed for the adjunct treatment of oral CMM. This article reviews the immunological similarities between CMM and the human counterpart; mechanisms by which tumours evade the immune system; reasons why melanoma is an attractive target for immunotherapy; the premise of whole cell, dendritic cell (DC), viral and DNA vaccination strategies alongside preliminary clinical results in dogs. Current “gold standard” treatments for advanced human malignant melanoma are evolving quickly with remarkable results being achieved following the introduction of immune checkpoint blockade and adoptively transferred cell therapies. The rapidly expanding field of cancer immunology and immunotherapeutics means that rational targeting of this disease in both species should enhance treatment outcomes in veterinary and human clinics

    An Energy-Minimization Finite-Element Approach for the Frank-Oseen Model of Nematic Liquid Crystals: Continuum and Discrete Analysis

    Full text link
    This paper outlines an energy-minimization finite-element approach to the computational modeling of equilibrium configurations for nematic liquid crystals under free elastic effects. The method targets minimization of the system free energy based on the Frank-Oseen free-energy model. Solutions to the intermediate discretized free elastic linearizations are shown to exist generally and are unique under certain assumptions. This requires proving continuity, coercivity, and weak coercivity for the accompanying appropriate bilinear forms within a mixed finite-element framework. Error analysis demonstrates that the method constitutes a convergent scheme. Numerical experiments are performed for problems with a range of physical parameters as well as simple and patterned boundary conditions. The resulting algorithm accurately handles heterogeneous constant coefficients and effectively resolves configurations resulting from complicated boundary conditions relevant in ongoing research.Comment: 31 pages, 3 figures, 3 table
    • …
    corecore