288 research outputs found

    A Hybrid Sensorless Observer for the Robust Global Asymptotic Flux Reconstruction of Permanent Magnet Synchronous Machines

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    We propose a hybrid sensorless observer for permanent magnet synchronous machines with global asymptotic stability guarantees. Exploiting the constraint of the rotor flux on a circle of unknown radius, we design an integrator system with periodic jumps triggered by a clock to generate a linear regression containing the flux estimation error. Then, a normalized projected gradient descent identifier provides the observer estimates. For the closed-loop system, it is shown that there exists a robustly globally asymptotically stable compact attractor, which, additionally, ensures zero estimation error if appropriate Persistency of Excitation (PE) conditions are satisfied. In this respect, sufficient conditions ensuring PE are provided for the angular speed and the clock period

    Rainfall interpolation analysis on river Kaduna catchment for climate change assessment

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    The Inverse Distance Weighing (IDW) technique for rainfall interpolation considered by researchers as a suitable method for predicting missing rainfall records was used to estimate missing rainfall records in River Kaduna Catchment area from 1979-1990. Distances among respective rainfall stations were used to calculate the weighing factor for stations with missing records and radius of influence of 22.5-201km. The Root Mean Square Error (RMSE) was used to test the accuracy of the assessment and the results were validated using correlation coefficient. From the results of the analysis through optimization of steps of α values and radius of influence, the smaller the optimum parameter value the better the prediction and in most cases the accuracy increases at short optimum search radii, also small amount and long duration rainfall values enhances the prediction potential of the IDW.Keywords: Rainfall data, Inverse Distance Weighing, Interpolation, Optimum parameter

    A strategy to identify housekeeping genes suitable for analysis in breast cancer diseases

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    Standard curve and serial dilutions for nHKGs and tHKGs. The x axis represents the dilution series (1:800, 1:400, 1:200 and 1:100) and the y axis represents the mean of CT for each gene. The correlation coefficient r is given for each gene inside parentheses. (PDF 53 kb

    No confirmed cases of Taenia solium taeniasis in a group of recently arrived Sub-Saharan migrants to Italy

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    One-hundred and sixty-four migrants from Sub-Saharan Africa to Italy were screened with the Taenia solium specific enzyme-linked immunosorbent assay coproantigen (ELISA CoAg) and four (2.4%) were recorded as positive, but with optical density values near to the cut-off. No ELISA CoAg positive samples were confirmed by parasitological methods. Low positivity could be attributed to false positive result or cross-reaction with other Taenia species. Further studies are needed to assess the role of migration on sporadic autochthonous transmission of T. solium taeniasis/cysticercosis in Europe

    Subcutaneously administered dexmedetomidine is efficiently absorbed and is associated with attenuated cardiovascular effects in healthy volunteers

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    Purpose: Palliative care patients often need sedation to alleviate intractable anxiety, stress, and pain. Dexmedetomidine is used for sedation of intensive care patients, but there is no prior information on its subcutaneous (SC) administration, a route that would be favored in palliative care. We compared the pharmacokinetics and cardiovascular, sympatholytic, and sedative effects of SC and intravenously (IV) administered dexmedetomidine in healthy volunteers.Methods: An open two-period, cross-over design with balanced randomization was used. Ten male subjects were randomized to receive 1 μg/kg dexmedetomidine both IV and SC. Concentrations of dexmedetomidine and catecholamines in plasma were measured. Pharmacokinetic variables were calculated with non-compartmental methods. In addition, cardiovascular and sedative drug effects were monitored.Results: Eight subjects completed both treatment periods. Peak concentrations of dexmedetomidine were observed 15 min after SC administration (median; range 15–240). The mean bioavailability of SC dexmedetomidine was 81% (AUC0-∞ ratio × 100%, range 49–97%). The mean (SD) peak concentration of dexmedetomidine in plasma was 0.3 (0.1) ng/ml, and plasma concentrations associated with sedative effects (i.e., > 0.2 ng/ml) were maintained for 4 h after SC dosing. Plasma noradrenaline concentrations were significantly lower (P Conclusions: Dexmedetomidine is relatively rapidly and efficiently absorbed after SC administration. Subcutaneous dexmedetomidine may be a feasible alternative in palliative sedation, and causes attenuated cardiovascular effects compared to IV administration.</p

    Exploring possible selves in a first-year physics foundation class: Engaging students by establishing relevance

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    Students often complain that they cannot see the relevance of what they are being taught in foundation physics classes. While revising and adjusting the curriculum and teaching are important, this study suggests it might also be useful to help students view their learning in relation to their future career aspirations. This paper reports on a study conducted with first-year students enrolled in a compulsory foundation physics unit with a history of low pass rates.Working within a “possible selves” framework, activities were designed to help students position their learning in relation to possible future lives and careers. Two cohorts of students (N ¼ 93) engaged in an intensive workshop comprising multiple activities relating to self and career. Self-reflection worksheets were analyzed using content analysis. The results indicate that students experience immediate benefits from these activities through self-reflection on the current self, future possible professional selves, and the role of current studies in narrowing the gap between the two
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