Regret bounds for Narendra-Shapiro bandit algorithms

Narendra-Shapiro (NS) algorithms are bandit-type algorithms that have been introduced in the sixties (with a view to applications in Psychology or learning automata), whose convergence has been intensively studied in the stochastic algorithm literature. In this paper, we adress the following question: are the Narendra-Shapiro (NS) bandit algorithms competitive from a \textit{regret} point of view? In our main result, we show that some competitive bounds can be obtained for such algorithms in their penalized version (introduced in \cite{Lamberton_Pages}). More precisely, up to an over-penalization modification, the pseudo-regret $\bar{R}_n$ related to the penalized two-armed bandit algorithm is uniformly bounded by $C \sqrt{n}$ (where $C$ is made explicit in the paper). \noindent We also generalize existing convergence and rates of convergence results to the multi-armed case of the over-penalized bandit algorithm, including the convergence toward the invariant measure of a Piecewise Deterministic Markov Process (PDMP) after a suitable renormalization. Finally, ergodic properties of this PDMP are given in the multi-armed case

UWB Indoor Radio Propagation Modelling in Presence of Human Body Shadowing Using Ray Tracing Technique

This paper presents a ray-tracing method for modelingUltra Wide Bandwidth indoor propagation channels. Avalidation of the ray tracing model with our indoor measurementis also presented. Based on the validated model, the multipathchannel parameter like the fading statistics and root mean squarerms delay spread for Ultra Wide bandwidth frequencies aresimply extracted. The proposed ray-tracing method is basedon image method. This is used to predict the propagation ofUWB electromagnetic waves. First, we have obtained that thefading statistics can be well fitted by log normal distributionin static case. Second, as in realistic environment we cannotneglect the significant impact of Human Body Shadowing andother objects in motion on indoor UWB propagation channel.Hence, our proposed model allows a simulation of propagationin a dynamic indoor environment. Results of the simulation showthat this tool gives results in agreement with those reported inthe literature. Specially, the effects of people motion on temporalchannel properties. Other features of this approach also areoutlined

Regret bound for Narendra-Shapiro bandit algorithms

Narendra-Shapiro (NS) algorithms are bandit-type algorithms that were introduced in the 1960s in view of applications to Psychology or clinical trials. The long time behavior of such algorithms has been studied in depth but it seems that few results exist in a non-asymptotic setting, which can be of primary interest for applications. In this paper, we focus on the study of the regret of NS-algorithms and address the following question: are the Narendra-Shapiro (NS) bandit algorithms competitive from this non-asymptotic point of view? In our main result, we show that some competitive bounds can be obtained in their penalized version (introduced in [14]). More precisely, up to a slight modification, the regret of the penalized two-armed bandit algorithm is uniformly bounded by C \sqrt{n} (where C is a positive constant made explicit in the paper). We also generalize existing convergence and rate of convergence results to the multi-armed case of the over-penalized bandit algorithm, including the convergence toward the invariant measure of a Piecewise Deterministic Markov Process (PDMP) after a suitable renormalization. Finally, ergodic properties of this PDMP are given in the multi-armed case

Stochastic Heavy Ball

This paper deals with a natural stochastic optimization procedure derived from the so-called Heavy-ball method differential equation, which was introduced by Polyak in the 1960s with his seminal contribution [Pol64]. The Heavy-ball method is a second-order dynamics that was investigated to minimize convex functions f. The family of second-order methods recently received a large amount of attention, until the famous contribution of Nesterov [Nes83], leading to the explosion of large-scale optimization problems. This work provides an in-depth description of the stochastic heavy-ball method, which is an adaptation of the deterministic one when only unbiased evalutions of the gradient are available and used throughout the iterations of the algorithm. We first describe some almost sure convergence results in the case of general non-convex coercive functions f. We then examine the situation of convex and strongly convex potentials and derive some non-asymptotic results about the stochastic heavy-ball method. We end our study with limit theorems on several rescaled algorithms

Modélisation d’un préchauffeur à cyclones d’une cimenterie et analyse des pertes physico-chimiques d’exergie

Un modèle du préchauffeur à cyclones d’une unité de ciment est développé sur la base de données recueillies sur une installation industrielle comprenant quatre étages de cyclonage avec des alimentations à contre-courant de gaz chaud et de farine crue servant à la fabrication de clinker. La division du préchauffeur est modélisée par une cascade de mélangeurs parfaits avec reflux de solide afin d’évaluer la quantité de poussières quittant chaque étage. Les pertes d’exergie associées au transfert thermique et à la réaction principale liée à la décomposition du CaCO3 sont analysées sous différentes conditions opératoires. Les résultats montrent que la température du gaz à l’entrée du préchauffeur et le nombre d’étages des cyclones ont une influence très significative sur les pertes physico-chimiques d’exergie. L’intensité de l’irréversibilité de la réaction de décarbonatation reste peu significative comparée à celle de l’échange thermique

Parthenolide inhibits ERK and AP-1 which are dysregulated and contribute to excessive IL-8 expression and secretion in cystic fibrosis cells

<p>Abstract</p> <p>Background</p> <p>Excessive secretion of IL-8 characterizes cystic fibrosis (CF). This has been attributed to excessive activation of epithelial cell I-κB Kinase and/or NFκB. Maximum IL-8 production requires 3 cooperative mechanisms: 1) release of the promoter from repression; 2) activation of transcription by NFκB and AP-1; 3) stabilization of mRNA by p38-MAPK. Little is known about regulation of IL-8 by MAPKs or AP-1 in CF.</p> <p>Methods</p> <p>We studied our hypothesis <it>in vitro </it>using 3-cellular models. Two of these models are transformed cell lines with defective versus normal cystic fibrosis transmembrane conductance regulator (CFTR) expression: an antisense/sense transfected cell line and the patient derived IB3-1/S9. In the third series of studies, we studied primary necropsy human tracheal epithelial cells treated with an inhibitor of CFTR function. All cell lines were pretreated with parthenolide and then stimulated with TNFα and/or IL-1β.</p> <p>Results</p> <p>In response to stimulation with TNFα and/or IL-1β, IL-8 production and mRNA expression was greater in CF-type cells than in non-CF controls. This was associated with enhanced phosphorylation of p38, ERK1/2 and JNK and increased activation of AP-1. Since we previously showed that parthenolide inhibits excessive IL-8 production by CF cells, we evaluated its effects on MAPK and AP-1 activation and showed that parthenolide inhibited ERK and AP-1 activation. Using a luciferase promoter assay, our studies showed that parthenolide decreased activation of the IL-8 promoter in CF cells stimulated with TNFα/IL-1β.</p> <p>Conclusions</p> <p>In addition to NFκB MAPKs ERK, JNK and p38 and the transcription factor AP-1 are also dysregulated in CF epithelial cells. Parthenolide inhibited both NFκB and MAPK/AP-1 pathways contributing to the inhibition of IL-8 production.</p

Estudo de prevalência do tratamento endodôntico na clínica universitária Egas Moniz

Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas MonizObjetivo: Determinar a prevalência de tratamentos endodônticos efetuados na Clínica Universitária Egas Moniz no período compreendido entre Setembro de 2018 e Maio de 2019. Materiais e Métodos: Avaliou-se o processo clínico de 199 doentes encaminhados para a consulta de Endodontia no período de tempo estipulado, focando-se apenas na prevalência dos tratamentos endodônticos não cirúrgicos. Estudou-se a história do tratamento (diagnóstico, o tipo de tratamento realizado, o número de sessões) e o tipo da restauração coronária. Outros fatores avaliados incluíram o dente tratado, o género e idade do doente. O estudo dos processos foi realizado por um único operador, o autor desta tese. Resultados : Observou-se que a prevalência de tratamentos endodônticos realizados foi de 6% dos actos clínicos da Clínica Universitaria Egas Moniz entre Setembro de 2018 e Maio de 2019. As pulpites irreversíveis representam 44,2% da origem dos tratamentos endodônticos realizados. Depois temos, com 14,1% dos diagnósticos realizados, as pulpites irreversíveis com lesão periapical. De seguida, a necrose pulpar com lesão periapical e necrose pulpar, respectivamente com 9,0% e 6.5% da amostra em estudo. Os tratamentos mais realizados na consulta, foram as pulpectomias, com uma percentagem de 72,4% da amostra em estudo. Os retratamentos representam 16,1%, e as pulpotomias apenas 4,5% dos tratamentos realizados. Destes tratamentos, 65,4% são realizados em três ou quatro sessões. O dente que mais frequentemente foi sujeito a pulpectomia foi o 1º molar, representando 31,5% das pulpectomias realizadas, seguido do 2º molar e 1º pré-molar. O dente onde mais frequentemente há retratamento é o 1º molar mandibular, correspondendo a 2,6%. Conclusão: Este estudo mostra que o tratamento de eleição em endodontia na Clínica Universitaria Egas Moniz é a pulpectomia.Aim: The aim of this study is to determine the prevalence of endodontic treatments performed at the Egas Moniz University Clinic in the period between September 2018 and May 2019. Materials and Methods: We evaluated the clinical report of 199 patients referred for the endodontic appointment in the stipulated period of time, focusing on the prevalence of non-surgical endodontic treatments. The treatment history (such as diagnosis, type of treatment performed, number of sessions) and type of coronary restoration were studied. Other factors evaluated included the affected tooth and the gender and age of the patient. The study of the clinical reports was carried out by a single operator, the author of this thesis. Results: It was observed that the prevalence of endodontic treatments performed was 6% of University Clinic processes between September 2018 and May 2019. Irreversible Pulpits represent 44.2% of the origin of the treatments performed. Then, with 14.1% of the diagnoses performed, we have irreversible pulpitis with periapical lesion. Pulpal necrosis with periapical lesion and pulpar necrosis followed, with 9.0% and 6.5% of the sample studied, respectively. The most frequently performed treatments were pulpectomies, with a percentage of 72.4% of the study sample. Retreatments represent 16.1%, and pulpotomies only 4.5% of the treatments performed. 65.4% of treatments are performed in three or four visits. The tooth that most frequently underwent pulpectomy was the first molar, representing 31.5% of the performed pulpectomies followed by the 2nd molar and 1st premolar. The most frequently retreated tooth is the first mandibular molar, corresponding to 2.6%. Conclusion: This study shows that the treatment of election in endodontics at the Egas Moniz University Clinic is Pulpectomy

Land Use and Urban Sprawl in the Case of the City of Rabat in Morocco: An Integrated Approach Using Remote Sensing, Geospatial Modeling, and Machine Learning

This document is produced as part of a project of mapping, monitoring and prediction of urban sprawl in the city of Rabat, using algorithms of machine Learning, remote sensing and geographic information system. It therefore aims to determine and monitor the urban sprawl of the city of Rabat, using new Geo-spatial technologies, this socio-economic mechanism is theoretically based on the increase in the horizontal area of the city, and a decrease in population density. On the contrary, the city of Rabat is characterized by a negative growth rate between the years 2004-2014 at about -0.79% different from 1.2% at the national level, and defined by a higher population density of 255 inhabitants per km2, these statistics were directed to a hypothesis that indicates a horizontal confinement of the city of Rabat and reverse immigration to per-urban territories. In addition, this project is mainly aimed at the implementation of a computerized simulation model for the characterization and prediction of the urban expansion of the city of Rabat for 40 years (1990, 2000, 2010, 2020, 2030). To conclude, the city of Rabat has experienced a very slow urban sprawl, thanks to the green belt put in 1971, and the modernization strategy that has been adapted in recent years to eliminate informal housing, in addition to the development of roads and the new TGV railway line, and also to the lack of land use, of which many large villas of several hectares were built. Although this mechanism is moving very slowly, the city of Rabat has had negative consequences on the territory and the environment. So, local authorities need a creative, innovative and intelligent urban planning programme to both eliminate the effects of this mechanism, and build the pillars of the functional city (smart city)

Analyse théorique de l’effet du télétravail sur la performance des ressources humaines dans les multinationales : proposition d’un modèle conceptuel

Telework has become the mainstay of companies in recent years, both nationally and internationally. This notion has become the focus of interest and the mobilization of practices in this direction raises our curiosity to study its impact on the performance of individuals within organizations. From there, this paper attempts to mobilize the conceptual frameworks of telework and human resource performance to study and explore how the use of telework has created a specific work context, through the mediating effect of autonomy and work-life balance satisfaction. The mediation analysis showed that the pathways from telecommuting to performance through autonomy and balance satisfaction were significant for home-based work. Indeed, we proposed a theoretical model by combining previous studies to investigate how these factors interact with each other through a literature review. This paper presents the theoretical foundation for future empirical research on issues related to the relationship between telecommuting and employee performance. &nbsp; Keywords: Telecommuting; autonomy; work-life balance; performance; work isolation.&nbsp; JEL Classification: M12 Type of article: theoretical ResearchLe télétravail a constitué ces dernières années le pilier des entreprises au niveau national et international. Cette notion a pris de l’ampleur pour constituer le centre d’intérêt et mobiliser&nbsp;&nbsp; toutes les pratiques dans ce sens elle suscite notre curiosité pour étudier son impact sur la performance des individus au sein des organisations. À partir de là, le présent article tente de mobiliser les cadres conceptuels du télétravail et de la performance des ressources humaines pour étudier et éplucher comment le recours au télétravail a pu créer un contexte du travail spécifique, à travers l’effet médiateur de l’autonomie et la satisfaction en matière d’équilibre entre la vie professionnelle et la vie personnelle. L'analyse de médiation a montré que les chemins du télétravail vers la performance à travers l'autonomie et la satisfaction de l'équilibre étaient significatifs pour le travail à domicile. En effet, nous mettons en avant un modèle théorique en combinant des études antérieures pour étudier comment ces facteurs interagissent les uns avec les autres, à travers une revue de la littérature. Cet article présente des soubassements théoriques pour de futures recherches empiriques, sur les questions liées à la relation entre le télétravail et la performance des employés. &nbsp; Mots-clés : Le télétravail ; l’autonomie ; l’équilibre entre vie professionnelle et vie privée ; la performance ; l’isolement professionnel. Classification JEL&nbsp;: M12 Le type de papier&nbsp;: article théoriqu