1,248 research outputs found

    Toward a better understanding of the doping mechanism involved in Mo(tfd-COCF3)3_3)_3 doped PBDTTT-c

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    In this study, we aim to improve our understanding of the doping mechanism involved in the polymer PBDTTT-c doped with(Mo(tfd-COCF3)3. We follow the evolution of the hole density with dopant concentration to highlight the limits of organic semiconductor doping. To enable the use of doping to enhance the performance of organic electronic devices, doping efficiency must be understood and improved. We report here a study using complementary optical and electrical characterization techniques, which sheds some light on the origin of this limited doping efficiency at high dopant concentration. Two doping mechanisms are considered, the direct charge transfer (DCT) and the charge transfer complex (CTC). We discuss the validity of the model involved as well as its impact on the doping efficiency.Comment: Accepted manuscript, J. Appl. Phy

    How accurately do routinely reported HIV viral load suppression proportions reflect progress towards the 90-90-90 target in the population on ART in Khayelitsha, South Africa?

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    Background: In 2016, Khayelitsha reported almost 89% viral load (VL) suppression but less than 56% completion on routine quarterly reports, casting doubt on the validity of reported suppression. Objectives: To assess the validity of reported VL suppression as a measure of progress towards the 90-90-90 target and identify barriers to routine VL completion. Methods: A retrospective cohort study including all patients on antiretroviral treatment (ART) in Khayelitsha with a routine VL expected between 1 July 2015 and 30 June 2016 was conducted. ART programme and laboratory data were obtained and a sample of 1 035 patient folders were reviewed. Suppression was calculated using laboratory data and compared to reported suppression. A VL cascade from “expected” to “done”, “filed”, “noted” and “captured” was constructed to reflect the steps a VL must complete to be included in reported suppression and successful progression to each step was estimated. Logistic regression models were used to calculate adjusted odds ratios (aOR) with 95% confidence intervals (95%CI) for completion among different patient groups. Results: Using laboratory data, VL suppression was estimated to be 82%, 87%, 89% and 91% at the 50, 200, 400 and 1 000 copies/mL thresholds respectively, but reported suppression would have been 80%, 86%, 88% and 89% at those thresholds. Of 22 991 patients with a routine VL due in the study period, 84% were done, 79% filed, 76% noted, and 55% captured. Routine VL were more likely to be done among children< 15 years old (aOR 1.89, 95%CI 1.45–2.48) and pregnant women (aOR 1.90, 95%CI 1.28–2.81) compared to adult men, adjusted for facility. Conclusion: Despite low reported completion, actual completion was high and reported suppression was similar to suppression calculated using laboratory data, thus providing an accurate measure of progress towards the 90-90-90 target. More work is needed to reach the 16% of patients missed by routine testing. Most of the VL done were available to the clinician at the next assessment, and further research is needed to assess how effectively these VL results are used in clinical decision-making

    Sur la séparation des caractÚres par les Frobenius

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    In this paper, we are interested in the question of separating two characters of the absolute Galois group of a number field K, by the Frobenius of a prime ideal p of OK. We first recall an upper bound for the norm N(p) of the smallest such prime p, depending on the conductors and on the degrees. Then we give two applications: (i) find a prime number p for which P (mod p) has a certain type of factorization in Fp[X], where P ∈ Z[X] is a monic, irreducible polynomial of squarefree discriminant; (ii) on the estimation of the maximal number of tamely ramified extensions of Galois group An over a fixed number field K. To finish, we discuss some statistics in the quadratic number fields case (real and imaginary) concerning the separation of two irreducible unramified characters of the alterning group An,for n = 5, 7, 13.In this paper, we are interested in the question of separating two characters of the absolute Galois group of a number field K, by the Frobenius of a prime ideal p of OK. We first recall an upper bound for the norm N(p) of the smallest such prime p, depending on the conductors and on the degrees. Then we give two applications: (i) find a prime number p for which P (mod p) has a certain type of factorization in Fp[X], where P ∈ Z[X] is a monic, irreducible polynomial of squarefree discriminant; (ii) on the estimation of the maximal number of tamely ramified extensions of Galois group An over a fixed number field K. To finish, we discuss some statistics in the quadratic number fields case (real and imaginary) concerning the separation of two irreducible unramified characters of the alterning group An,for n = 5, 7, 13.In this paper, we are interested in the question of separating two characters of the absolute Galois group of a number field K, by the Frobenius of a prime ideal p of OK. We first recall an upper bound for the norm N(p) of the smallest such prime p, depending on the conductors and on the degrees. Then we give two applications: (i) find a prime number p for which P (mod p) has a certain type of factorization in Fp[X], where P ∈ Z[X] is a monic, irreducible polynomial of squarefree discriminant; (ii) on the estimation of the maximal number of tamely ramified extensions of Galois group An over a fixed number field K. To finish, we discuss some statistics in the quadratic number fields case (real and imaginary) concerning the separation of two irreducible unramified characters of the alterning group An,for n = 5, 7, 13

    A Bayesian method with empirically fitted priors for the evaluation of environmental radioactivity: application to low-level radioxenon measurements

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    International audienceThe decision that a given detection level corresponds to the effective presence of a radionuclide is still widely made on the basis of a classic hypothesis test. However, the classic framework suffers several drawbacks, such as the conceptual and practical impossibility to provide a probability of zero radioactivity, and confidence intervals for the true activity level that are likely to contain negative and hence meaningless values. The Bayesian framework being potentially able to overcome these drawbacks, several attempts have recently been made to apply it to this decision problem. Here, we present a new Bayesian method that, unlike the previous ones, presents two major advantages together. First, it provides an estimate of the probability of no radioactivity, as well as physically meaningful point and interval estimates for the true radioactivity level. Second, whereas Bayesian approaches are often controversial because of the arbitrary choice of the priors they use, the proposed method permits to estimate the parameters of the prior density of radioactivity by fitting its marginal distribution to previously recorded activity data. The new scheme is first mathematically developed. Then, it is applied to the detection of radioxenon isotopes in noble gas measurement stations of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty
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