2,207 research outputs found

    Stochastic Real-time Optimal Control for Bearing-only Trajectory Planning

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    A method is presented to simultaneously solve the optimal control problem and the optimal estimation problem for a bearing-only sensor. For bearing-only systems that require a minimum level of certainty in position relative to a source for mission accomplishment, some amount of maneuver is required to measure range. Traditional methods of trajectory optimization and optimal estimation minimize an information metric. This paper proposes constraining the final value of the information states with known time propagation dynamics relative to a given trajectory which allows for attainment of the required level of information with minimal deviation from a general performance index that can be tailored to a specific vehicle. The proposed method does not suffer from compression of the information metric into a scalar, and provides a route that will attain a particular target estimate quality while maneuvering to a desired relative point or set. An algorithm is created to apply the method in real-time, iteratively estimating target position with an Unscented Kalman Filter and updating the trajectory with an efficient pseudospectral method. Methods and tools required for hardware implementation are presented that apply to any real-time optimal control (RTOC) system. The algorithm is validated with both simulation and flight test, autonomously landing a quadrotor on a wire

    Preserving professional credibility: grounded theory study of medical traineesā€™ requests for clinical support

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    Objective To develop a conceptual framework of the influences on medical traineesā€™ decisions regarding requests for clinical support from a supervisor

    Combining Integration of Care and a Population Health Approach: A Scoping Review of Redesign Strategies and Interventions, and their Impact

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    Background and aim: Many health systems attempt to develop integrated and population health-oriented systems of care, but knowledge of strategies and interventions to support this effort is lacking. We aimed to identify specific redesign strategies and interventions, and to present evidence of their effectiveness. Method: A modified scoping review process was carried out. Fifteen relevant examples of integrated care organizations that incorporated a broad population health approach in countries of the Organization for Economic Cooperation and Development described in 57 articles and reports were included in analysis. Results: Seven key redesign strategies and multiple redesign interventions have been identified and are described. Most commonly used redesign strategies included focusing on health and wellness, embracing intersectoral action and partnerships, addressing health in vulnerable groups, and addressing a wide range of determinants of health, including making improvements in health services. Redesign interventions included creative and innovative ways of addressing clinical and non-clinical issues such as establishing housing surgeries in primary care, establlishing vast social and provider networks to support patients with complex needs and also broadening of the scope of services, workforce redesign and other. Potential reductions in the utilization of care and costs could be derived by the wider adoption of these strategies and interventions. Conclusion: Development of integrated and population health-oriented systems of care requires the redesign of how services are organized and delivered, and how organizations and care systems operate. Combining integration of care with the population health approach can be supported by a set of cohesive strategies and interventions aimed at preventing disease, addressing social determinants of health and improving health equity at both population- and individual-level

    Big conductance calcium-activated potassium channel openers control spasticity without sedation.

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    BACKGROUND AND PURPOSE: Our initial aim was to generate cannabinoid agents that control spasticity, occurring as a consequence of multiple sclerosis (MS), whilst avoiding the sedative side effects associated with cannabis. VSN16R was synthesized as an anandamide (endocannabinoid) analogue in an anti-metabolite approach to identify drugs that target spasticity. EXPERIMENTAL APPROACH: Following the initial chemistry, a variety of biochemical, pharmacological and electrophysiological approaches, using isolated cells, tissue-based assays and in vivo animal models, were used to demonstrate the activity, efficacy, pharmacokinetics and mechanism of action of VSN16R. Toxicological and safety studies were performed in animals and humans. KEY RESULTS: VSN16R had nanomolar activity in tissue-based, functional assays and dose-dependently inhibited spasticity in a mouse experimental encephalomyelitis model of MS. This effect occurred with over 1000-fold therapeutic window, without affecting normal muscle tone. Efficacy was achieved at plasma levels that are feasible and safe in humans. VSN16R did not bind to known CB1 /CB2 /GPPR55 cannabinoid-related receptors in receptor-based assays but acted on a vascular cannabinoid target. This was identified as the major neuronal form of the big conductance, calcium-activated potassium (BKCa ) channel. Drug-induced opening of neuronal BKCa channels induced membrane hyperpolarization, limiting excessive neural-excitability and controlling spasticity. CONCLUSIONS AND IMPLICATIONS: We identified the neuronal form of the BKCa channel as the target for VSN16R and demonstrated that its activation alleviates neuronal excitability and spasticity in an experimental model of MS, revealing a novel mechanism to control spasticity. VSN16R is a potential, safe and selective ligand for controlling neural hyper-excitability in spasticity

    The Herschel Stripe 82 Survey (HerS): maps and early catalog

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    We present the first set of maps and band-merged catalog from the Herschel Stripe 82 Survey (HerS). Observations at 250, 350, and 500Ī¼m were taken with the Spectral and Photometric Imaging Receiver instrument aboard the Herschel Space Observatory. HerS covers 79deg 2 along the SDSS Stripe 82 to an average depth of 13.0, 12.9, and 14.8mJybeam āˆ’1 (including confusion) at 250, 350, and 500Ī¼m, respectively. HerS was designed to measure correlations with external tracers of the dark matter density fieldā€”either point-like (i.e., galaxies selected from radio to X-ray) or extended (i.e., clusters and gravitational lensing)ā€”in order to measure the bias and redshift distribution of intensities of infrared-emitting dusty star-forming galaxies and active galactic nuclei. By locating HerS in Stripe 82, we maximize the overlap with available and upcoming cosmological surveys. The band-merged catalog contains 3.3 Ɨ 10 4 sources detected at a significance of ?3Ļƒ (including confusion noise). The maps and catalog are available at http://www.astro.caltech.edu/hers/

    Markers of Inflammation, Coagulation, and Renal Function Are Elevated in Adults with HIV Infection

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    (See the article by Kalayjian et al, on pages 1796-1805, and the editorial commentary by DubĆ© and Sattler, on pages 1783-1785.) Background. Human immunodeficiency virus (HIV) replication and immune activation may increase inflammation and coagulation biomarkers. Limited data exist comparing such biomarkers in persons with and without HIV infection. Methods. For persons 45-76 years of age, levels of high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, D-dimer, and cystatin C were compared in 494 HIV-infected individuals in the Strategies for Management of Anti-Retroviral Therapy (SMART) study and 5386 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) study. For persons 33-44 years of age, hsCRP and IL-6 levels were compared in 287 participants in the SMART study and 3231 participants in the Coronary Artery Development in Young Adults (CARDIA) study. Results. hsCRP and IL-6 levels were 55% (P<.001) and 62% (P<.001) higher among HIV-infected participants than among CARDIA study participants. Compared with levels noted in MESA study participants, hsCRP, IL-6, D-dimer, and cystatin C levels were 50%, 152%, 94%, and 27% higher, respectively (P<.001 , for each), among HIV-infected participants. HIV-infected participants receiving antiretroviral therapy who had HIV RNA levels ā‰¤400 copies/mL had levels higher (by 21% to 60%) (P<.001) than those in the general population, for all biomarkers. Conclusions. hsCRP, IL-6, D-dimer, and cystatin C levels are elevated in persons with HIV infection and remain so even after HIV RNA levels are suppressed with antiretroviral therapy. Additional research is needed on the pathophysiology of HIV-induced activation of inflammatory and coagulation pathways, to guide potential intervention
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