Optimisation of geometric aspect ratio of thin film transistors for low-cost flexible CMOS inverters and its practical implementation.

A low-cost, flexible processor is essential to realise affordable flexible electronic systems and transform everyday objects into smart-objects. Thin film transistors (TFTs) based on metal-oxides (or organics) are ideal candidates as they can be manufactured at low processing temperatures and low-cost per unit area, unlike traditional silicon devices. The development of complementary metal-oxide-semiconductor (CMOS) technology based on these materials remains challenging due to differences in performance between n- and p-type TFTs. Existing geometric rules typically compensate the lower mobility of the metal-oxide p-type TFT by scaling up the width-to-length (W/L) ratio but fail to take into account the significant off-state leakage current. Here we propose the concept of an optimal geometric aspect ratio which maximises the inverter efficiency represented by the average switching current divided by the static currents. This universal method is especially useful for the design of low-power CMOS inverters based on metal-oxides, where the large off-current of the p-type TFT dominates the static power consumption of the inverter. We model the inverter efficiency and noise margins of metal-oxide CMOS inverters with different geometric aspect ratios and compare the performance to different inverter configurations. The modelling results are verified experimentally by fabricating CMOS inverter configurations consisting of n-type indium-silicon-oxide (ISO) TFTs and p-type tin monoxide (SnO) TFTs. Notably, our results show that reducing W/L of metal-oxide p-type TFTs increases the inverter efficiency while reducing the area compared to simply scaling up W/L inversely with mobility. We anticipate this work provides a straightforward method to geometrically optimise flexible CMOS inverters, which will remain relevant even as the performance of TFTs continues to evolve.

[Prevalence of cardiovascular risk factors in semi-rural area in Senegal]. / Prévalence des facteurs de risque cardio-vasculaire en milieu semi-rural au Sénégal.

OBJECTIVES: We aim to determine the prevalence of cardiovascular risk factors in the semi-rural population of the community of Gueoul in Senegal. PATIENTS AND METHOD: This is a cross-sectional, observational and descriptive study. We conducted an exhaustive survey in 2012 according to the STEPS wise approach of the world health organization against Senegalese aged of 35 years and over who resided for at least 6 months in semi-rural area in the community of Gueoul. Pregnant women were excluded. Classical cardiovascular risk factors were collected and data analyzed using SPSS 18.0 software. The significance level was agreed for a value of P<0.05. RESULTS: We examined 1411 subjects (1052 women) with a mean age of 48.5±12.68 years. The main cardiovascular risk factors were dyslipidemia (61,1%), physical inactivity (56.2%), abdominal obesity according to the International Diabetes Federation (53.9%), hypertension (46.4%), global obesity (13%), diabetes (7.2%) and smoking (2.5%). Hypertension was significantly associated with diabetes (P=0.001), abdominal obesity (P=0.001) and global obesity (P=0.0001). Sedentarity (P=0.001), global obesity (P=0.0001) and hypertension (P=0.001) were more frequent in women. CONCLUSION: Cardiovascular risk factors are frequent and often associated in semi-rural area of Senegal, particularly in women. This condition should lead to develop prevention strategies of cardiovascular complications.

[Left ventricular hypertrophy in black African subjects with artery hypertension: Results of a cross-sectional survey conducted in semi-rural area in Senegal]. / L'hypertrophie ventriculaire gauche chez le sujet noir Africain hypertendu : résultats d'une enquête transversale, réalisée en milieu semi-rural au Sénégal.

OBJECTIVES: To assess the prevalence of left ventricular hypertrophy according to electrocardiographic and echocardiographic criteria among hypertensive patients living in semi-rural Senegalese area. PATIENTS AND METHODS: According to the World Health Organization STEPSwise approach, we conducted, in November 2012, a cross-sectional and exhaustive study in the population aged at least 35 years old and living for at least six months in the semi-rural area of Guéoul. We researched electrocardiographic and echocardiographic left ventricular hypertrophy in hypertensive subjects. Data were analyzed with SPSS 18.0 software version. The significance level was agreed for a value of P<0.05. RESULTS: We examined 1411 subjects aged on average of 48.5±12.7 years. In total, 654 subjects were hypertensive and screening of left ventricular hypertrophy (LVH) was effective in 515 of them. According to Sokolow-Lyon index, 86 subjects (16.7%) presented electrocardiographic LVH, more frequently in men (P=0.002). According to Cornell index and Cornell product, LVH was founded respectively in 66 (12.8%) and 52 subjects (10.1%), more frequently in female (P=0.0001; P=0.004). It was more common in grade 3 of hypertension however criteria. In echocardiography, prevalence of LVH was 2.2% (13 cases) according to the left ventricular mass, 9.3% (48 cases) according to the left ventricular mass indexed to body surface area and 8.2% (42 cases) according to the left ventricular mass indexed to height2.7. LVH was significantly correlated with the electrocardiographic LVH according to Sokolow-Lyon index (P<0.0001) and the grade 3 of hypertension (P=0.003). CONCLUSION: Although rare in hypertensive Senegalese living in semi-rural area, left ventricular hypertrophy is correlated with severity of grade of hypertension. Screening by electrocardiogram will allow better follow-up of these hypertensive subjects.

Optimal antiretroviral therapy adherence as evaluated by CASE index score tool is associated with virological suppression in HIV-infected adults in Dakar, Senegal.

OBJECTIVE: To determine the prevalence and factors associated with optimal antiretroviral therapy (ART) adherence and virological failure (VLF) among HIV-infected adults enrolled in the national ART programme at the teaching hospital of Fann, Dakar, Senegal. METHODS: Cross-sectional study from 1 September 2013 to 30 January 2014. OUTCOMES: (1) optimal ART adherence by the Center for Adherence Support Evaluation (CASE) Index Score (>10) and (2) VLF (HIV RNA > 1000 copies/ml). Diagnostic accuracy of CASE Index Score assessed using sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and corresponding 95% confidence intervals (CIs). Multivariate logistic regression analysis was performed to identify independent factors associated with optimal adherence and VLF. RESULTS: Of 98 HIV-infected patients on ART, 68% were female. The median (IQR) age was 42 (20-50) years. A total of 57 of 98 (60%) were on ART more than 3 years, and majority (88%) were on NNRTI-based first-line ART regimen. A total of 79 of 98 (80%) patients reported optimal ART adherence, and only five of 84 (5.9%) had documented VLF. Patients with VLF were significantly more likely to have suboptimal ART adherence (17.7% vs. 2.9%; P = 0.02). CASE Index Score showed the best trade-off in Se (78.9%, 95% CI: 54.4-93.9%), Sp (20.0%, 95% CI: 11.1-31.7), PPV (22.4, 95% CI: 13.1-34.2%) and NPV (76.5%, 95% CI: 50.1-93.2), when used VLF threshold of HIV RNA >50 copies/ml. Factors independently associated with VLF were CASE Index Score <10 ([aOR] = 13.0, 95% CI: 1.1-147.9; P = 0.04) and being a boosted PI-based ART regimen ([aOR] = 27.0, 95% CI: 2.4-309.4; P = 0.008). CONCLUSIONS: Optimal ART adherence is achievable in a high proportion of HIV-infected adults in this study population. CASE Index Score was independently associated with virological outcomes, supporting usefulness of this low-cost ART adherence monitoring tool in this setting.

[Study of the immunization coverage determinants of vaccination campaign against meningococcal A meningitis in Burkina Faso]. / Étude des déterminants de la couverture vaccinale de la campagne de vaccination contre la méningite à méningocoque A au Burkina Faso.

BACKGROUND: Sub-Saharan Africa countries suffer from repeated and explosive epidemics of meningitis mainly due to Neisseria meningitidis A. In December 2010, Burkina Faso organized a vaccination campaign with MenAfriVac® for people aged 1-29 years old. The objective of this study was to analyze the determinants of immunization coverage. METHODS: We used a cross-sectional survey by cluster sampling in two stages, descriptive and analytical, conducted in the region of "Boucle du Mouhoun". Data were collected during a home interview. The dependent variable was vaccination status and the independent variables included individual and household characteristics but also the means of communication used during the campaign. A logistic regression model was used to estimate the risk of being vaccinated using the 'Survey' Package (SVYGLM) of R. RESULTS: Two thousand and twenty-five people were included with a 93.5 % estimated coverage. Factors associated with high vaccination coverage are rural areas (ORa=2.53 [1.53-4.17]) and smaller households (ORa=3.06 [1.36-6.91]). The risk of being vaccinated was lower for persons from salaried heads of household (ORa=0.14 [0.02-0.87]) versus farmers, persons informed by religious and traditional leaders (ORa=0.25 [0.11-0.57]) or family and friends (ORa=0.51 [0.29-0.9]) versus community mobilizers. CONCLUSION: The coverage recorded is sufficient to provide community immunity. However, a part of the target population could not benefit from vaccination due to lack of information. Particular emphasis should be placed on large urban families using community mobilizers.

[Clinical and biological effectiveness of antiretroviral therapy in the ANRS 1215 cohort]. / Efficacité clinique et biologique des traitements antirétroviraux : exemple de la cohorte ANRS 1215.

In 1998, the cohort ANRS 1215 was launched in Senegal with one of the first African antiretroviral treatment programs. Four hundred forty four HIV-infected adults started on ART were included between 1998 and 2004, and followed up to 2010. Mortality before 6 months was 15.6/100 person-year (PY) and associated to the initial disease severity. It decreased to 3.36/100 PY thereafter. The cumulative risks of virologic failure at 60 months and of drug resistance at 48 months were 25% and 16%, respectively.

[Study of determinants of unprotected sex in sailors of the Senegalese merchant navy]. / Étude des déterminants des rapports sexuels non protégés chez les marins de la marine marchande sénégalaise.

Sailors are a mobile population travelling a lot and therefore being often exposed to casual sex. The aim of this study is to analyze the determinants of unprotected sex among sailors in Senegal. A descriptive and analytical study was conducted among sailors of the merchant navy. Data on knowledge, attitudes and practices were collected during a personal interview. A multivariate analysis was performed using a multiple logistic regression. A total of 400 sailors were interviewed, 57.9% had casual sex of whom 23.7% were not protected. Sexual intercourse without protection was more common among the uneducated (OR = 2.29 [1.23 to 5.99]) and married (OR = 2.29 [1.23-5.99]). Sailors who thought that using condom reduces pleasure during sexual intercourse (OR = 2.5 [1.2-5.1]) and those who consumed alcohol (OR = 5.4 [2.07-14.2]) were less protected during casual sex. Sexual contact is one of the main modes of transmission of HIV / AIDS. Sailors often have unprotected sex. Interventions using specific ways must be performed taking into account the mobility of these men who are often uneducated.

[Economic impact of skin-lightening products on household income in sub-Saharan Africa: the case of Senegal]. / Poids économique de la dépigmentation artificielle sur le revenu des ménages d'Afrique subsaharienne : cas du Sénégal.

INTRODUCTION: As throughout sub-Saharan Africa, the use of skin-lightening (or brightening or bleaching) products is widespread in Senegal (67%). Although the medical and social determinants of this phenomenon have been documented, its cost is poorly defined. Thus, this work aims to evaluate the economic effects of skin bleaching on women's income. METHODOLOGY: A cross-sectional, quantitative, and descriptive survey was conducted in 2010 (October 7 to November 8) among women consulting for outpatient care at a reference dermatology clinic for complications related to use of skin-lightening products. We calculated the direct costs (products) and indirect costs (transportation costs, medical fees, dermatological treatment of complications). The social damage (pain and suffering and esthetics) was assessed. RESULTS: This study included 65 women; their mean age was 33 years and 26% had not attended school. In all, 52% were merchants, 29% housewives, 9% civil servants, and 5% students. The average duration of product use was 9 years, and the mean age at onset of use, 23 years. Most (80%) had a low income (<100,000 FCFA or US $204). The total monthly income of the 65 women in the study was 5,675,000 CFA (US $ 11,582). The total monthly cost of skin lightening for them was 1081,658 CFA (US $ 2207), that is, 19% of their total income. The esthetic harm was categorized as moderate by 20% and high by 22%. CONCLUSION: This study opens perspectives for further studies of the intangible costs of skin bleaching and for increasing awareness of the complications and social damage induced.

[Prevalence survey of cardiovascular risk factors in the general population in St. Louis (Senegal)]. / Enquête de prévalence des facteurs de risque cardiovasculaire en population générale à Saint-Louis (Sénégal).

BACKGROUND: Cardiovascular diseases are becoming with their risk factors a real health problem in Africa. The objectives of this study were to assess the prevalence of risk factors for cardiovascular diseases in the general population in Saint-Louis, Senegal. METHODOLOGY: This is a cross-sectional, descriptive and analytical made in May 2010, in the Senegalese aged 15, residing in the city of Saint-Louis, Senegal. A systematic random sampling and stratified cluster has been achieved. Cardiovascular risk factors for research were: hypertension, diabetes, dyslipidemia, smoking, obesity, physical inactivity and metabolic syndrome. RESULTS: The survey involved 1424 individuals with 983 women (69%). The average age was 43.4±17.8years. The prevalence of risk factors was: hypertension (46%), diabetes (10.4%), total cholesterol (36.3%), hyperLDLcholesterol (20.6%), obesity (body mass index≥30kg/m(2)) (23%), abdominal obesity (48.7% according to International Diabetes Federation and 33.2% according to National Cholesterol Education Program) physical inactivity (64.7%), smoking (5.8%) and metabolic syndrome (15.7%). There was predominance in women of risk factors except for smoking and diabetes. The overall cardiovascular risk was high in 24.9% according to the Framingham model, 28.8% (European Society of Hypertension) and 6.1% (SCORE). CONCLUSION: This survey found a high prevalence of cardiovascular risk factors in a general population in Senegal, predominant in women. This should lead to better develop a strategy to prevent cardiovascular diseases.

Social inequality and antenatal care: impact of economic welfare on pregnancy monitoring in Senegal.

AIM: To explore the links between antenatal care (ANC) non-attendance and economic welfare. METHOD AND SUBJECT: This was a cross-sectional, descriptive and analytical study of women aged 15 to 49 years living in Senegal in 2005. Data were from the Demography and Health Survey using a two-stage random sampling procedure. Participants were classed by quintile using an economic well-being score based on housing characteristics and ownership of sustainable goods. The quality of ANC was determined from the number of visits, the qualification of the person delivering care, and content (counseling, weight, height and blood pressure measurements). Logistic regression was used for data analysis. RESULTS: A total of 6927 women were surveyed. Mean age was 28.15 years (±2.6); 20.3% were primiparous; 61.2% resided in rural areas; 70.0% had received no education. Each of the first four economic quintiles included about 20% (19.2% to 21.5%) of the participants while 16.9% were in the fifth (richest) quintile. A total of 457 women (6.6%) did not undergo any ANC visit. ANC non-attendance increased with parity, decreased with education level and was higher in rural areas than in urban areas, OR=7.2 (95% CI [5.1-10.1]). It decreased with increasing economic well-being: OR=0.6 [0.47-0.75] 2nd quintile vs. 1st, OR=0.02 [0.01-0.05] 5th quintile vs. 1st, p<0.05 overall. CONCLUSION: Economic welfare plays a major role in determining use of ANC. The only way to solve health problems is to reduce inequalities. The solution to this problem is beyond the scope of health but concerns an overall economic program involving the entire community, including policy-makers.

[Screening for asymptomatic peripheral arterial occlusive disease of the lower limbs by measuring the ankle-brachial index in the general population (Senegal)]. / Dépistage de l'artériopathie oblitérante asymptomatique des membres inférieurs par la mesure de l'index de pression systolique dans la population générale de Saint-Louis (Sénégal).

OBJECTIVES: The purpose of this study was to investigate the prevalence of peripheral arterial disease (PAOD) and cardiovascular risk factors associated with the ankle-brachial index (ABI) in Senegalese patients aged 40 years and over. METHODOLOGY: We prospectively studied a random sample of Senegalese aged 40 years and older, residing in the city of St.-Louis, Senegal. The ABI was measured with a portable doppler (DIADOP 50) using 4 and 8Hz dual frequency probes. The standards were: normal ABI 0.9 to 1.3; peripheral artery obstructive disease (PAOD) ABI less than 0.9; incompressible artery ABI greater than 1.3. Cardiovascular risk factors were also studied. RESULTS: Seven hundred and seventy-one subjects (mean age 57 ± 11.2 years, 559 women) were examined. Cardiovascular risk factors were: sedentary lifestyle (76.4%), hypertension (68%), obesity (32.1%), elevated LDL-cholesterolemia (27.8%), diabetes (18.3%) and tobacco smoking (6.9%). Ninety-three subjects (12.1%) had PAOD and 37 subjects (4.8%) had an incompressible artery. PAOD was significantly more common in sedentary subjects (P=0.008), in the elderly (P=0.0006) and in patients with a history of coronary artery disease (P=0.04). Smoking was not strongly associated with PAOD. CONCLUSION: PAOD is common in Senegalese and is associated with high prevalence of cardiovascular risk factors.

[Access to intermittent preventive treatment (IPt) in a situation of abolition of user's fee: role of economic welfare]. / Accès au traitement préventif intermittent (TPI) dans une situation de gratuité : rôle du bien-être économique.

In Senegal, the free distribution of sulfadoxine pyrimethamine during antenatal care is recommended to remove the disparity in the context of intermittent preventive treatment against malaria. The objective of this study was thus to identify factors influencing access to treatment in a situation of abolition of user fees. It was a cross-sectional and analytical study. It covered a sample of 1906 women aged 15-49 years randomly selected during the national survey on malaria in Senegal. Data were collected during a personal interview. The economic well-being was measured from the characteristics of housing and durable goods. The multivariate analysis was performed using logistic regression. The average age was 27.94 ± 5.34, 64.27% resided in rural area and 71.8% had received no schooling. Among the surveyed women, 23% were in the poorest quintile, while 16.3% were in the richest. Intermittent preventive treatment was performed in 49.3%. IPt were made more in urban areas (OR 1.45 95% [1.17 to 1.72]). It increased with the level of education with an OR of 1.5 and 1.68 in primary and secondary. The completion of the IPt increased with economic welfare. The OR ranged from 1.44 to 2.95 in the second quintile to the richest. Free medication does not necessarily benefit poor people. Other accompanying measures must be developed to facilitate the distribution of drugs particularly at community level with the involvement of people.