Simulation d'un réseau de neurones à l'aide de transistors SET

Ce mémoire est le résultat d'une recherche purement exploratoire concernant la définition d'une application de réseaux de neurones à base de transistors monoélectroniques (Single-Electron Transistor, SET). Il dresse un portait de l'état de l'art actuel, et met de l'avant la possibilité d'associer les SET avec la technologie actuelle (Field Electron Transistor, FET). La raison de cette association est que les SET peuvent être perçus comme un moyen de changement de paradigme, c'est-à-dire remplacer une fonction CMOS occupant une grande place par un dispositif alternatif présentant de meilleures performances ou équivalentes. Par l'intermédiaire de leurs caractéristiques électriques peu ordinaires au synonyme de"l'effet de blocage de Coulomb", les SET ont le potentiel d'être exploités intelligemment afin de tirer profit sur la consommation énergétique essentiellement. Cette problématique est présentée comme une des propositions alternatives"Beyond CMOS" aux termes de la diminution géométrique des transistors FET à la lumière de l'ITRS. Cette recherche propose d'exposer des circuits électroniques de technologie MOS complétés à l'aide de SET (circuits hybrides) et de montrer que l'on est capable de les remplacer ou les compléter (partiellement) dans des architectures à réseau de neurones. Pour cela, des simulations sous logiciel Cadence Environnement permettront de valider le comportement des circuits sur plusieurs critères tels que la vitesse de réponse et la consommation énergétique, par exemple. En résultat, seront proposées deux architectures à réseaux de neurones de fonctions différentes : une architecture Winner-Take-All et un générateur de spikes en tension. La première étant inspirée d'une publication provenant de GUIMARAES et al., veut démontrer qu'à partir d'une architecture SET existante, il est envisageable de se l'approprier et de l'appliquer aux paramètres des SET du CRN[indice supérieur 2] augmentant donc nos chances de pouvoir les concevoir dans notre groupe de recherche. Le second axe est la simulation d'un circuit capable de générer des signaux à spikes sans perte d'information, ce qui requerrait un nombre considérable de transistors FET sans l'utilisation de SET, mettant donc en valeur la réduction de composants

Comportement thermo-mécanique et métallurgique des aciers

La détermination des contraintes et déformations résiduelles induites par le soudage ou le trempe des aciers joue un rôle très important pour la prédiction de durée de vie des structures. Le travail présenté dans cet article décrit une loi de comportement anisotherme permettant de modéliser le problème couplé thermo-mécanique et métallurgique des aciers. Dans le modèle proposé, le comportement thermo-mécanique de chaque phase est traité indépendamment et le comportement macroscopique du matériau s'obtient en utilisant l'hypothèse de contrainte homogène (Reuss). Le modèle a été implanté dans le code COMSOL Multiphysics. Nous avons constaté une bonne concordance entre nos résultats de calcul et les résultats expérimentaux issus de littérature, de plus nous avons montré l'influence de la viscosité sur le niveau des contraintes résiduelles induites par les procédés de soudage ou de trempe des aciers

Prevalence, trends, and drivers of the utilization of unskilled birth attendants during democratic governance in Nigeria from 1999 to 2018

Comprehensive epidemiological data on prevalence, trends, and determinants of the use of unskilled birth attendants (traditional birth attendants (TBAs) and other unskilled birth attendants) are essential to policy decision-makers and health practitioners, to guide efforts and resource allocation. This study investigated the prevalence, trends, and drivers of the utilization of unskilled birth attendants during democratic governance in Nigeria from 1999 to 2018. The study used the Nigeria Demographic and Health Surveys data for the years 1999 (n = 3552), 2003 (n = 6029), 2008 (n = 28,647), 2013 (n = 31,482), and 2018 (34,193). Multivariate multinomial logistic regression was used to investigate the association between socioeconomic, demographic, health-service, and community-level factors with the utilization of TBAs and other unskilled birth attendants in Nigeria. Between 1999 and 2018, the study showed that the prevalence of TBA-assisted delivery remained unchanged (20.7%; 95% CI: 18.0–23.7% in 1999 and 20.5%; 95% CI: 18.9–22.1% in 2018). The prevalence of other-unskilled-birth-attendant use declined significantly from 45.5% (95% CI: 41.1–49.7%) in 2003 to 36.2% (95% CI: 34.5–38.0%) in 2018. Higher parental education, maternal employment, belonging to rich households, higher maternal age (35–49 years), frequent antenatal care (ANC) (≥4) visits, the proximity of health facilities, and female autonomy in households were associated with lower odds of unskilled birth attendants’ utilization. Rural residence, geopolitical region, lower maternal age (15–24 years), and higher birth interval (≥2 years) were associated with higher odds of unskilled-birth-attendant-assisted deliveries. Reducing births assisted by unskilled birth attendants in Nigeria would require prioritized and scaled-up maternal health efforts that target all women, especially those from low socioeconomic backgrounds, those who do not attend antenatal care, and/or those who reside in rural areas

Malaria in central Vietnam: analysis of risk factors by multivariate analysis and classification tree models

BACKGROUND: In Central Vietnam, forest malaria remains difficult to control due to the complex interactions between human, vector and environmental factors. METHODS: Prior to a community-based intervention to assess the efficacy of long-lasting insecticidal hammocks, a complete census (18,646 individuals) and a baseline cross-sectional survey for determining malaria prevalence and related risk factors were carried out. Multivariate analysis using survey logistic regression was combined to a classification tree model (CART) to better define the relative importance and inter-relations between the different risk factors. RESULTS: The study population was mostly from the Ra-glai ethnic group (88%), with both low education and socio-economic status and engaged mainly in forest activities (58%). The multivariate analysis confirmed forest activity, bed net use, ethnicity, age and education as risk factors for malaria infections, but could not handle multiple interactions. The CART analysis showed that the most important risk factor for malaria was the wealth category, the wealthiest group being much less infected (8.9%) than the lower and medium wealth category (16.6%). In the former, forest activity and bed net use were the most determinant risk factors for malaria, while in the lower and medium wealth category, insecticide treated nets were most important, although the latter were less protective among Ra-glai people. CONCLUSION: The combination of CART and multivariate analysis constitute a novel analytical approach, providing an accurate and dynamic picture of the main risk factors for malaria infection. Results show that the control of forest malaria remains an extremely complex task that has to address poverty-related risk factors such as education, ethnicity and housing conditions

The association between food environment, diet quality and malnutrition in low‐ and middle‐income adult populations across the rural—Urban gradient in Vietnam

Background: Economic reforms and trade liberalisation in Vaietnm have transformed the food environment, influencing dietary patterns and malnutrition status. The present study focuses on the relationship between food environments (proximity and density of food outlets) and malnutrition (underweight, overweight, obesity) through diet quality in adult populations across urban, periurban and rural areas of Vietnam. Methods: We evaluated food environment by geospatial mapping of food outlets through a transect walk across the “food ecosystem” from rural to urban areas. Diet quality was assessed using the Diet Quality Index – Vietnamese (DQI‐V) comprising Variety, Adequacy, Moderation and Balance components. Malnutrition status was determined using body mass index. We performed a mediation analysis utilising mixed effect models to control for neighbourhood clustering effects. Confounders included age, education, income and nutrition knowledge score. Results: Analysis of data from 595 adult participants (mean ± SD age: 31.2 ± 6.4 years; 50% female) found that longer distance to the nearest food outlet was associated with higher overall DQI‐V (β = 2.0; 95% confidence interval = 0.2–3.8; p = 0.036) and the Moderation component (β = 2.6; 95% confidence interval = 1.2–4.0; p = 0.001). Outlet density shows a negative association with the odds of underweight among women (odds ratio = 0.62; 95% confidence interval = 0.37–0.96). However, we did not observe statistically significant relationships between diet quality and malnutrition. Education and nutrition knowledge scores were positively associated with diet diversity, while income was negatively associated with diet moderation. Conclusions: The findings of the present study have important implications for nutrition and dietetics practice in Vietnam and globally. It emphasises the need to consider various dimensions of sustainable diets, including economic, health and socio‐cultural/political factors. Longer distances to food outlets are associated with higher diet quality, whereas lower food outlet density increases the odds of underweight among women. This poses challenges in balancing modernisation and its adverse effects on sustainable food systems. Socio‐economic status consistently correlated with diet quality and malnutrition, necessitating further research to promote healthy diets across socio‐economic strata

Alterations of lipid-related genes during anti-tuberculosis treatment: insights into host immune responses and potential transcriptional biomarkers

BackgroundThe optimal diagnosis and treatment of tuberculosis (TB) are challenging due to underdiagnosis and inadequate treatment monitoring. Lipid-related genes are crucial components of the host immune response in TB. However, their dynamic expression and potential usefulness for monitoring response to anti-TB treatment are unclear. MethodologyIn the present study, we used a targeted, knowledge-based approach to investigate the expression of lipid-related genes during anti-TB treatment and their potential use as biomarkers of treatment response. Results and discussionThe expression levels of 10 genes (ARPC5, ACSL4, PLD4, LIPA, CHMP2B, RAB5A, GABARAPL2, PLA2G4A, MBOAT2, and MBOAT1) were significantly altered during standard anti-TB treatment. We evaluated the potential usefulness of this 10-lipid-gene signature for TB diagnosis and treatment monitoring in various clinical scenarios across multiple populations. We also compared this signature with other transcriptomic signatures. The 10-lipid-gene signature could distinguish patients with TB from those with latent tuberculosis infection and non-TB controls (area under the receiver operating characteristic curve > 0.7 for most cases); it could also be useful for monitoring response to anti-TB treatment. Although the performance of the new signature was not better than that of previous signatures (i.e., RISK6, Sambarey10, Long10), our results suggest the usefulness of metabolism-centric biomarkersConclusionsLipid-related genes play significant roles in TB pathophysiology and host immune responses. Furthermore, transcriptomic signatures related to the immune response and lipid-related gene may be useful for TB diagnosis and treatment monitoring

The prevalence and correlates of physical inactivity among adults in Ho Chi Minh City

<p>Abstract</p> <p>Background</p> <p>Socioeconomic changes have led to profound changes in individuals' lifestyles, including the adoption of unhealthy food consumption patterns, prevalent tobacco use, alcohol abuse and physical inactivity, especially in large cities like Ho Chi Minh City (HCMC). The Stepwise Approach to Surveillance of Non-communicable Disease Risk Factors survey was conducted to identify physical activity patterns and factors associated with 'insufficient' levels of physical activity for health in adults in HCMC.</p> <p>Methods</p> <p>A cross-sectional survey was conducted in 2005 among 1906 adults aged 25–64 years using a probability proportional to size cluster sampling method to estimate the prevalence of non-communicable disease risk factors including physical inactivity. Data on socioeconomic status, health behaviours, and time spent in physical activity during work, commuting and leisure time were collected. Physical activity was measured using the validated Global Physical Activity Questionnaire (GPAQ). Responders were classified as 'sufficiently active' or 'insufficiently active' using the GPAQ protocol. Correlates of insufficient physical activity were identified using multivariable logistic regression.</p> <p>Results</p> <p>A high proportion of adults were physically inactive, with only 56.2% (95% CI = 52.1–60.4) aged 25–64 years in HCMC achieving the minimum recommendation of 'doing 30 minutes moderate-intensity physical activity for at least 5 days per week'. The main contributors to total physical activity among adults were from working and active commuting. Leisure-time physical activity represented a very small proportion (9.4%) of individuals' total activity level. Some differences in the pattern of physical activity between men and women were noted, with insufficient activity levels decreasing with age among women, but not among men. Physical inactivity was positively associated with high income (OR = 1.77, 95% CI = 1.05–2.97) and high household wealth index (OR = 1.86, 95% CI = 1.29–2.66) amongst men.</p> <p>Conclusion</p> <p>Public health policies and programs to preserve active commuting in HCMC and to promote time spent in recreational physical activity in both genders and across all age groups, but especially among young adults, will be critical in any comprehensive national plan to tackle inactivity. Clear and consistent national recommendations about how much physical activity Vietnamese people need for preventing and managing non-communicable diseases should also be part of this population-wide promotional effort.</p

Surgeon volume and 30 day mortality for brain tumours in England.

BACKGROUND: There is evidence that surgeons who perform more operations have better outcomes. However, in patients with brain tumours, all of the evidence comes from the USA. METHODS: We examined all English patients with an intracranial neoplasm who had an intracranial resection in 2008-2010. We included surgeons who performed at least six operations over 3 years, and at least one operation in the first and last 6 months of the period. RESULTS: The analysis data set comprised 9194 operations, 163 consultant neurosurgeons and 30 centres. Individual surgeon volumes varied widely (7-272; median=46). 72% of operations were on the brain, and 30 day mortality was 3%. A doubling of surgeon load was associated with a 20% relative reduction in mortality. Thirty day mortality varied between centres (0·95-8·62%) but was not related to centre workload. CONCLUSIONS: Individual surgeon volumes correlated with patient 30 day mortality. Centres and surgeons in England are busier than surgeons and centres in the USA. There is no relationship between centre volume and 30 day mortality in England. Services in the UK appear to be adequately arranged at a centre level, but would benefit from further surgeon sub-specialisation

Helicobacter pylori infection and gastroduodenal diseases in Vietnam: a cross-sectional, hospital-based study

<p>Abstract</p> <p>Background</p> <p>The rate of <it>H. pylori </it>infection in Vietnam is reportedly high, but the spectrum of <it>H. pylori</it>-associated gastroduodenal diseases has not been systematically investigated. Moreover, despite the similarities of ethnicity and diet, the age-standardized incidence rate of gastric cancer in the northern city of Hanoi is higher than that in the southern city of Ho Chi Minh, but the reason for this phenomenon is unknown. The virulence of Vietnamese <it>H. pylori </it>has also not been investigated in detail.</p> <p>Methods</p> <p>Individuals undergoing esophagogastroduodenoscopy were randomly recruited. <it>H. pylori </it>infection status was determined based on the combined results of culture, histology, immunohistochemistry, rapid urine test and serum ELISA. Peptic ulcer (PU) and gastroesophageal reflux disease was diagnosed by endoscopy, and chronic gastritis was determined histologically. <it>H. pylori </it>virulence factors were investigated by PCR and sequencing.</p> <p>Results</p> <p>Among the examined patients, 65.6% were infected with <it>H. pylori</it>. The prevalence of infection was significantly higher in those over 40 years of age than in those aged ≤40. Chronic gastritis was present in all <it>H. pylori</it>-infected individuals, 83.1% of whom had active gastritis, and 85.3% and 14.7% had atrophy and intestinal metaplasia, respectively. PU was present in 21% of infected patients, whereas its incidence was very low in non-infected individuals. The prevalence of PU was significantly higher in Hanoi than in Ho Chi Minh. The prevalence of <it>vacA m1</it>, which has been identified as an independent risk factor for PU in Vietnam, was significantly higher among <it>H. pylori </it>isolates from Hanoi than among those from Ho Chi Minh.</p> <p>Conclusions</p> <p><it>H. pylori </it>infection is common in Vietnam and is strongly associated with PU, active gastritis, atrophy and intestinal metaplasia. <it>vacA m1 </it>is associated with an increased risk for PU and might contribute to the difference in the prevalence of PU and gastric cancer between Hanoi and Ho Chi Minh.</p

Lifestyle physical activity among urban Palestinians and Israelis: a cross-sectional comparison in the Palestinian-Israeli Jerusalem risk factor study

<p>Abstract</p> <p>Background</p> <p>Urban Palestinians have a high incidence of coronary heart disease, and alarming prevalences of obesity (particularly among women) and diabetes. An active lifestyle can help prevent these conditions. Little is known about the physical activity (PA) behavior of Palestinians. This study aimed to determine the prevalence of insufficient PA and its socio-demographic correlates among urban Palestinians in comparison with Israelis.</p> <p>Methods</p> <p>An age-sex stratified random sample of Palestinians and Israelis aged 25-74 years living in east and west Jerusalem was drawn from the Israel National Population Registry: 970 Palestinians and 712 Israelis participated. PA in a typical week was assessed by the Multi-Ethnic Study of Atherosclerosis (MESA) questionnaire. Energy expenditure (EE), calculated in metabolic equivalents (METs), was compared between groups for moderate to vigorous-intensity physical activity (MVPA), using the Wilcoxon rank-sum test, and for domain-specific prevalence rates of meeting public health guidelines and all-domain insufficient PA. Correlates of insufficient PA were assessed by multivariable logistic modeling.</p> <p>Results</p> <p>Palestinian men had the highest median of MVPA (4740 METs-min_*wk^-1) compared to Israeli men (2,205 METs-min_*wk^-1<it>p </it>< 0.0001), or to Palestinian and Israeli women, who had similar medians (2776 METs-min_*wk^-1). Two thirds (65%) of the total MVPA reported by Palestinian women were derived from domestic chores compared to 36% in Israeli women and 25% among Palestinian and Israeli men. A high proportion (63%) of Palestinian men met the PA recommendations by occupation/domestic activity, compared to 39% of Palestinian women and 37% of the Israelis. No leisure time PA was reported by 42% and 39% of Palestinian and Israeli men (<it>p </it>= 0.337) and 53% and 28% of Palestinian and Israeli women (<it>p </it>< 0.0001). Palestinian women reported the lowest level of walking. Considering all domains, 26% of Palestinian women were classified as insufficiently active versus 13% of Palestinian men (<it>p </it>< 0.0001) who did not differ from the Israeli sample (14%). Middle-aged and elderly and less educated Palestinian women, and unemployed and pensioned Palestinian men were at particularly high risk of inactivity. Socio-economic indicators only partially explained the ethnic disparity.</p> <p>Conclusions</p> <p>Substantial proportions of Palestinian women, and subgroups of Palestinian men, are insufficiently active. Culturally appropriate intervention strategies are warranted, particularly for this vulnerable population.</p