Mesure statistique de la résistance de contact d’une grille sérigraphiée pour cellules solaires au silicium multicristallin

La métallisation par sérigraphie est une des étapes les plus importantes dans la technologie d’élaboration des cellules solaires pour une production à grande échelle. Néanmoins, elle demeure dépendante de plusieurs paramètres variables. Pour le silicium multi cristallin, tout changement dans le procédé de réalisation des cellules solaires influence directement l’optimisation du profil de recuit de la métallisation par sérigraphie. Les plaquettes de silicium multi cristallin subissent toutes les étapes classiques de réalisation des cellules solaires comme le nettoyage chimique et la décontamination, une diffusion au phosphore et le dépôt du nitrure de silicium SiNx par PECVD (Plasma Enhanced Chemical Vapor Deposition). Il y a juste le dépôt du contact Argent Ag sur la face avant de la plaquette. Nous avons utilisé la pâte de sérigraphie Ag Ferro 3349. La grille métallique comporte six (06) motifs TLM (Transfer Length Method) pour les mesures de la résistance de contact. Le principal but de ce travail est le contrôle de la qualité du contact Ag/SiNx/n+-Si dans les cellules solaires au silicium multicristallin. Les mesures TLM révèlent une cartographie des valeurs de la résistance de contact pour chaque température. Le profil optimal de température de recuit est autour de 750 °C

Prevalence of Self-Medication of Psychoactive Stimulants and Antidepressants among Undergraduate Pharmacy Students in Twelve Pakistani Cities

Purpose: To evaluate the prevalence of self-medication of psychoactive stimulants and antidepressants among pharmacy students of Pakistan.Methods: A cross-sectional survey on self-medication of psychoactive stimulants and antidepressants among pharmacy students was conducted with a structured and validated questionnaire distributed to a total of 2981 final year undergraduate pharmacy students in 12 major Pakistani cities (Karachi, Lahore, Islamabad, Rawalpindi, Sargodha, Dera Ismail Khan, Abbottabad, Bahawalpur, Hyderabad, Faisalabad, Multan and Peshawar) of Pakistan. Out of this, 2516 (718 male and 1798 female) students completed and returned the questionnaire.Results: Prevalence of self-medication of psychoactive stimulants was 1.31 (1.13 – 1.75 for 95% CI) and antidepressants was 8.34 (8.03 – 8.85 for 95% CI). A majority of the students (63 %) identified academic competition as a driving force for indulging in self-medication of psychoactive stimulants while nearly all the students (96 %)admitted using antidepressants to obtain relief from the pressure of studies (p < 0.05).Conclusion: Pakistani pharmacy students, despite being aware of the hazards of psychoactive stimulants, indulge in self-medication. Prevalence of self-medication with antidepressants is very high among the students due to the pressure of studies. Primarily, academic competition is the major driving force for the use of psychoactive stimulants.Keywords: Self-medication, Psychoactive stimulants, Antidepressants, Pharmacy students, Academicpressur

Material flow analysis for identifying rare earth element recycling potentials in the EU-27

International audienceRare earth elements (REEs) are essential for high-techology industrial sectors. This paper presents research on material flow analysis (MFA) applied to REEs in the EU-27. Innovative aspects of this research pertain to (i) considering potential lithospheric stocks of REEs in the EU and (ii) accounting for incomplete and imprecise information in MFA data reconciliation. Results obtained to-date provides a history of EU-27 raw rare earth imports and exports and a methodology for data reconciliation which constitutes an alternative to the classical least-squares method

Hierarchies of Susy Splittings and Invisible Photinos as Dark Matter

We explore how to generate hierarchies in the splittings between superpartners. Some of the consequences are the existence of invisible components of dark matter, new inflaton candidates, invisible monopoles and a number of invisible particles that might dominate during various eras, in particular between BBN and recombination and decay subsequently.Comment: 16 pages. v3: Ref. 27 has been modified. v4: Published versio

Suppression of HBV by Tenofovir in HBV/HIV coinfected patients : a systematic review and meta-analysis

Background: Hepatitis B coinfection is common in HIV-positive individuals and as antiretroviral therapy has made death due to AIDS less common, hepatitis has become increasingly important. Several drugs are available to treat hepatitis B. The most potent and the one with the lowest risk of resistance appears to be tenofovir (TDF). However there are several questions that remain unanswered regarding the use of TDF, including the proportion of patients that achieves suppression of HBV viral load and over what time, whether suppression is durable and whether prior treatment with other HBV-active drugs such as lamivudine, compromises the efficacy of TDF due to possible selection of resistant HBV strains. Methods: A systematic review and meta-analysis following PRISMA guidelines and using multilevel mixed effects logistic regression, stratified by prior and/or concomitant use of lamivudine and/or emtricitabine. Results: Data was available from 23 studies including 550 HBV/HIV coinfected patients treated with TDF. Follow up was for up to seven years but to ensure sufficient power the data analyses were limited to three years. The overall proportion achieving suppression of HBV replication was 57.4%, 79.0% and 85.6% at one, two and three years, respectively. No effect of prior or concomitant 3TC/FTC was shown. Virological rebound on TDF treatment was rare. Interpretation: TDF suppresses HBV to undetectable levels in the majority of HBV/HIV coinfected patients with the proportion fully suppressed continuing to increase during continuous treatment. Prior treatment with 3TC/FTC does not compromise efficacy of TDF treatment. The use of combination treatment with 3TC/FTC offers no significant benefit over TDF alone

The burden of diseases and risk factors in Bangladesh, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background: Bangladesh has made substantial progress in improving socioeconomic and health indicators over the past 50 years, but data on national disease burden are scarce. We used data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to estimate the burden of diseases and risk factors in Bangladesh from 1990 to 2019. / Methods: For this systematic analysis, we analysed data from vital registration systems, surveys, and censuses using multistage modelling processes to estimate life expectancy at birth, mortality rate, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs). Additionally, we compared the health status of Bangladesh with that of the other countries in the GBD south Asia region—Bhutan, India, Nepal, and Pakistan. / Findings: Life expectancy at birth in Bangladesh increased from 58·2 years (95% uncertainty interval 57·1–59·2) in 1990 to 74·6 years (72·4–76·7) in 2019. Between 1990 and 2019, the age-standardised mortality rate decreased from 1509·3 (1428·6–1592·1) to 714·4 (604·9–838·2) deaths per 100 000 population. In 2019, non-communicable diseases represented 14 of the top 20 causes of death; the leading three causes were stroke, ischaemic heart disease, and chronic obstructive pulmonary disease. High blood pressure, high fasting plasma glucose, and smoking were the top three risk factors. From 1990 to 2019, the rate of all-cause DALYs decreased by 54·9% (48·8–60·4). In 2019, the leading causes of DALYs and YLLs were neonatal disorders, stroke, and ischaemic heart disease, whereas musculoskeletal disorders, depressive disorders, and low back pain were the leading causes of YLDs. Bangladesh has the lowest age-standardised rates of mortality, YLDs, and YLLs and the highest life expectancy at birth in south Asia. / Interpretation: Over the past 30 years, mortality rates have reduced by more than half in Bangladesh. Bangladesh must now address the double burden of communicable and non-communicable diseases. Cost-effective, multisectoral efforts are needed to prevent and control non-communicable diseases, promote healthy lifestyles, and prevent premature mortality and disabilities. / Funding: Bill & Melinda Gates Foundation. / Translation: For the Bangla translation of the abstract see Supplementary Materials section

A Search for Dark Higgs Bosons

Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb-1 of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the Standard Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots for b/w printin

Evidence for an excess of B -> D(*) Tau Nu decays

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. We also report the observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.Comment: Expanded section on systematics, text corrections, improved the format of Figure 2 and included the effect of the change of the Tau polarization due to the charged Higg

Search for the decay modes D^0 → e^+e^-, D^0 → μ^+μ^-, and D^0 → e^±μ∓

We present searches for the rare decay modes D^0→e^+e^-, D^0→μ^+μ^-, and D^0→e^±μ^∓ in continuum e^+e^-→cc events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468  fb^(-1). These decays are highly Glashow–Iliopoulos–Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D^0→μ^+μ^- channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman–Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D^0→e^+e^-)<1.7×10^(-7), B(D^0→μ^+μ^-) within [0.6,8.1]×10^(-7), and B(D^0→e^±μ^∓)<3.3×10^(-7)

A search for the decay modes B+/- to h+/- tau l

We present a search for the lepton flavor violating decay modes B+/- to h+/- tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472 million BBbar pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the tau four-momentum. The resulting tau candidate mass is our main discriminant against combinatorial background. We see no evidence for B+/- to h+/- tau l decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10^-5.Comment: 15 pages, 7 figures, submitted to Phys. Rev.