Leibniz dans l’Encyclopédie

En étudiant la liste des articles de l’Encyclopédie relatifs à Leibniz, l’on distingue trois contributions majeures : celles des deux éditeurs Diderot et D’Alembert, et celle de Formey. L’oeuvre de Leibniz disponible au XVIIIe siècle restant très partielle, la question des sources et de leur utilisation par les Encyclopédistes se pose d’abord : si Diderot effectue un travail de traduction et de lecture active des concepts philosophiques leibniziens, les Institutions de Physique de la marquise du Châtelet figurent comme source principale de Formey. Enfin, D’Alembert fait référence à l’oeuvre physique et mathématique de Leibniz tout en étendant ses sources à l’ensemble des travaux scientifiques majeurs du XVIIIe siècle. Trois démarches qui nourrissent trois ambitions différentes : pour Diderot, celle de s’approprier les concepts leibniziens selon l’éclectisme philosophique, celle d’une diffusion de la métaphysique wolffienne chez Formey, et enfin pour D’Alembert l’inclusion de Leibniz dans une Histoire des Mathématiques, guidée par son modèle épistémologiqueLeibniz in the EncyclopédieA study of the list of Encyclopédie articles about Leibniz reveals three major contributions, by the two editors, Diderot and D’Alembert, and Formey. Our very partial knowledge of Leibniz’s works available in the 18th Century poses first of all the question of the sources and their use in these articles. While Diderot undertook the translation and active reading of Leibniz’s philosophical concepts, Formey’s main source was the marquise du Châtelet’s Institutions de physique, and D’Alembert referred to Leibniz’s physical and mathematical works while also using all the main 18th-century scientific works. These three different approaches implied three different aims: Diderot wished to appropriate Leibniz’s concepts in the context of his philosophical eclecticism; Formey’s aim was the diffusion of Wolff’s metaphysics; and D’Alembert wanted to include Leibniz in a history of mathematics, guided by his epistemological mode

Orthogonal outlier detection and dimension estimation for improved MDS embedding of biological datasets

Conventional dimensionality reduction methods like Multidimensional Scaling (MDS) are sensitive to the presence of orthogonal outliers, leading to significant defects in the embedding. We introduce a robust MDS method, called DeCOr-MDS (Detection and Correction of Orthogonal outliers using MDS), based on the geometry and statistics of simplices formed by data points, that allows to detect orthogonal outliers and subsequently reduce dimensionality. We validate our methods using synthetic datasets, and further show how it can be applied to a variety of large real biological datasets, including cancer image cell data, human microbiome project data and single cell RNA sequencing data, to address the task of data cleaning and visualization

The key parameters that govern translation efficiency

Translation of mRNA into protein is a fundamental yet complex biological process with multiple factors that can potentially affect its efficiency. Here, we study a stochastic model describing the traffic flow of ribosomes along the mRNA (namely, the inhomogeneous $\ell$-TASEP), and identify the key parameters that govern the overall rate of protein synthesis, sensitivity to initiation rate changes, and efficiency of ribosome usage. By analyzing a continuum limit of the model, we obtain closed-form expressions for stationary currents and ribosomal densities, which agree well with Monte Carlo simulations. Furthermore, we completely characterize the phase transitions in the system, and by applying our theoretical results, we formulate design principles that detail how to tune the key parameters we identified to optimize translation efficiency. Using ribosome profiling data from S. cerevisiae, we shows that its translation system is generally consistent with these principles. Our theoretical results have implications for evolutionary biology, as well as synthetic biology.Comment: To appear in Cell Systems. 32 pages, 10 figures, 1 tabl

PSSA- INTERNATIONAL SOLUTION TO PROTECT THE BIODIVERSITY IN HA LONG BAY - CAT BA MARINE AREA

A Particularly Sensitive Sea Area (PSSA) is an important management tool for biodiversity protection of a marine area. At the time of designation of a Particularly Sensitive Sea Area, an associated protective measure, which meets the requirements of the appropriate legal instrument establishing such measure, must have been approved or adopted by IMO to prevent, reduce, or eliminate the threat or identified vulnerability. Information on each of the Particularly Sensitive Sea Areas (PSSAs) that has been designated by IMO is available on the nautical chart. The Vietnam’s coastal zones and islands are the isolated oceanic habitat of extremely rich marine life in very good condition which is important to the maintenance and dispersal of the marine life of the western tropical Pacific. Vietnam coastal areas are very high risk areas affected by maritime activities, particularly international shipping, therefore in the future identification of some Particularly Sensitive Sea Areas (PSSAs) is necessary. The first Particularly Sensitive Sea Area for Vietnam in Ha Long - Cat Ba was initially proposed in this paper

CHẾ TẠO VÀ TÍNH CHẤT CỦA VẬT LIỆU TỔ HỢP GRAPHENE – ỐNG NANO CÁCBON – HẠT NANO VÀNG

In this work, a composite nanomaterial consisting of graphene (Gr), double-wall carbon nanotube (DWCNTs) and gold nanoparticles (AuNPs), designated as DWCNTs-AuNPs-Gr was synthesized via the thermal chemical vapour deposition technique. The morphology and electrical and electrochemical properties of the material were characteried by using field emission scanning electron microscopy, Raman spectroscopy, four-probe sheet resistance measurement, and cyclic voltammetry (CV). The average sheet resistance value of DWCNTs-AuNPs-Gr is 549 W/sq, 2.3 times lower than that of graphene. The current response of a DWCNTs-AuNPs-Gr-modified electrode in a 2 mM K3[Fe(CN)6]/K4[Fe(CN)6] solution with 0.1 M PBS is 15.79 µA, 1.48 times higher than that of a graphene-modified electrode and 2.57 times higher than that of a bare electrode. The DWCNTs-AuNPs-Gr material can be used for electrochemical biosensors to detect various bioelements.Trong công trình này, màng tổ hợp của vật liệu graphene (Gr) – ống nano cácbon hai tường (DWCNT) và hạt nano kim loại vàng (AuNPs) (DWCNT-AuNPs-Gr) đã được chế tạo bằng phương pháp lắng đọng pha hơi nhiệt hóa học (CVD). Hình thái học bề mặt và các tính chất điện, điện hóa của vật liệu tổ hợp đã được khảo sát thông qua kính hiển vi điện tử quét phát xạ trường, phổ Raman, điện trở bốn mũi dò và kỹ thuật quét thế vòng (CV). Với nồng độ DWCNTs 0,3 g/L và tốc độ quay phủ 4000 vòng/phút, vật liệu DWCNTs-AuNPs-Gr có điện trở bề mặt giảm 2,3 lần so với màng Gr và đạt khoảng 549 W/sq; dòng đỉnh đáp ứng trong dung dịch 2 mM K3[Fe(CN)6]/K4[Fe(CN)6] trong 0,1 M PBS đạt 15,79 µA tại 50 mV/s, cao gấp 1,48 lần so với điện cực biến tính màng Gr và gấp 2,57 lần so với điện cực trần. Vật liệu DWCNTs-AuNPs-Gr có tiềm năng ứng dụng trong cảm biến điện hóa để phát hiện các phần tử sinh học khác nhau

Evaluation of Ursolic Acid as the Main Component Isolated from Catharanthus Roseus against Hyperglycemia

ABSTRACT. Ursolic acid with large amount (0.67% of dried plant weight) along with 7 compounds, namely as spatozoate (1), kaurenoic acid (2), ursonic acid (3), 3-hydroxy-11-ursen-28,13-olide (4), ursolic acid (5), vindoline (6) and mixture of β-sitosterol and stigmasterol were isolated from dichloromethane and ethyl acetate extracts which have shown anti-glucosidase activity of the whole plant of C.roseus. Some isolated compounds and their derivatives were also tested for anti-glucosidase and cytotoxicity.Ursolic acid was examined for hypoglycemic activity in alloxan-induced diabetic mice with dose of 200 and 300 mg/kg/day, respectively. The results have shown that the blood glucose level were reduced by 45.75% and 51.31% to compare with the control group. This study has confirmed that the main component of Vietnamese C. roseus has had significant anti-hyperglycemia activity

COVID-19 outbreak after 100 days without community transmission: Epidemiological analysis of factors associated with death

Background: Outbreak of SARS-CoV-2 pandemic has caused millions of deaths and lifelong consequences since December 2019. We attempted to evaluate the incidence, distribution, and risk factors associated with death after applying the social distance strategy to the second wave of SARS-CoV-2 in the Danang outbreak in Vietnam.Methods: We retrospectively reviewed the online the Danang Hospital reports, gathering the epidemiological history of confirmed SARS-CoV-2 patients. We then conducted a descriptive analysis of Fisher’s Phi Coefficient and Cramer’s, along with multiple logistic regression models to test the effects of symptomatology and control measures performed by Vietnamese government. The last report we examined on August 29, 2020.Results: A total of 389 SARS-CoV-2 confirmed cases were related to the Danang outbreak are included in our analysis with a mean age of 47.1 (SD = 18.4), involving 154 men and 235 women, with 34 cases of death and 355 were alive. The study showed significant results related to age, quarantine measures, previous negative SARS-CoV-2 test, and a range of symptoms, including shortness of breath and myalgia (p-value <0.05). Our multiple-variable analysis suggested the significant risk of death was related to age, severe symptomology, undetected SARS-CoV-2 test results, and prior quarantined SARS-CoV-2 history.Conclusions: Vietnamese authorities had implemented successful quarantine practices to control the SARS-CoV-2 outbreaks. However, this virus has shown dynamic spread beyond the ability of the country to control its transmission. Adequate screening, social distancing, and adequate care of elderly and healthcare workers can lower the risk of future outbreaks

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Modeling and analysis of neuronal networks, stochastic chemical reactions in cellular micro-domains and telomere dynamics

In this PhD, we model specific stochastic events occurring in different biological contexts. In the first part, we study three different properties of neural networks. Using a mean field facilitation-depression synaptic model, we unravel the synchronous long lasting bursting observed at various scales of neural populations. Next, we study the neuronal noise induced transition between Up& Down states. To study the oscillatory peaks of the time spent in Up state, we consider the exit problem for a class of stochastic processes in a domain with an attractor located close to a limit cycle. We construct a class of systems conjugate to the Hopf bifurcation system that we study using WKB approximation and boundary layer analysis. We finally focus on neuroglial interactions and more specifically on astrocytic potassium. Using a tri-compartment model, we simulate the potassium dynamics for different stimulation protocols and we determine how astrocytic channels can influence neurotransmission. In the second part, we focus on the threshold activation for stochastic chemical reactions in cellular micro-domains. We compute the probability and the mean first time to reach a threshold for different reactions. The methods are applied to study the mitotic spindle checkpoint and the problem of gene expression and post-transcriptional regulation. The third part is finally dedicated to the stochastic dynamics of telomere length across cell divisions. We model the dynamics of telomere length as a drift and jump process, which allows predicting the distribution of telomere length and the length of the shortest telomere.Nous modélisons différents évènements aléatoires intervenant en biologie. Dans une première partie, on étudie certaines propriétés de populations de neurones. En utilisant un modèle de facilitation dépression synaptique, on étudie le phénomène de bursts synchrones observés à différentes échelles de populations. On étudie ensuite la transition entre état haut et bas de neurones induite par le bruit.Afin de comprendre le phénomène d oscillations du temps de séjour dans l état haut, onétudie le problème de premier temps de passage pour une classe de processus stochastiquesdans un domaine avec un attracteur situé près d un cycle limite. On construit une classede systèmes conjugués à celui de Hopf que l on étudie via les méthodes d approximations WKB et couche limite. On s intéresse enfin aux interactions entre neurones et astrocytes, et plus spécifiquement à l intégration du potassium. En introduisant un modèle à trois compartiments, on simule les dynamiques du potassium pour différents protocoles de stimulations pour déterminer comment les canaux astrocytaires influencent la neurotransmission. Dans une deuxième partie, on s intéresse au temps d atteinte d un seuil pour des réactions. Les méthodes introduites sont ensuite utilisées pour étudier le contrôle du fuseau mitotique et la régulation posttranscriptionnellede l expression génétique dans le noyau et le cytoplasme. Dans la troisième partie, on modélise la dynamique stochastique des longueurs de télomères après chaque division cellulaire. En étudiant le processus de drift et saut associé, on prédit la distribution stationnaire ainsi que la longueur du télomère le plus court d une cellulePARIS-BIUSJ-Mathématiques rech (751052111) / SudocSudocFranceF