Some Epidemic models with fractional derivatives were proved to be well-defined, well-posed and more accurate [34, 51, 116], compared to models with the conventional derivative. An Ebola epidemic model with non-linear transmission is fully analyzed. The model is expressed with the conventional time derivative with a new parameter included, which happens to be fractional (that derivative is called the 􀀀derivative). We proved that the model is well-de ned and well-posed. Moreover, conditions for boundedness and dissipativity of the trajectories are established. Exploiting the generalized Routh-Hurwitz Criteria, existence and stability analysis of equilibrium points for the Ebola model are performed to show that they are strongly dependent on the non-linear transmission. In particular, conditions for existence and stability of a unique endemic equilibrium to the Ebola system are given. Numerical simulations are provided for particular expressions of the non-linear transmission, with model's parameters taking di erent values. The resulting simulations are in concordance with the usual threshold behavior. The results obtained here may be signi cant for the ght and prevention against Ebola haemorrhagic fever that has so far exterminated hundreds of families and is still a ecting many people in West-Africa and other parts of the world. The full comprehension and handling of the phenomenon of shattering, sometime happening during the process of polymer chain degradation [129, 142], remains unsolved when using the traditional evolution equations describing the degradation. This traditional model has been proved to be very hard to handle as it involves evolution of two intertwined quantities. Moreover, the explicit form of its solution is, in general, impossible to obtain. We explore the possibility of generalizing evolution equation modeling the polymer chain degradation and analyze the model with the conventional time derivative with a new parameter. We consider the general case where the breakup rate depends on the size of the chain breaking up. In the process, the alternative version of Sumudu integral transform is used to provide an explicit form of the general solution representing the evolution of polymer sizes distribution. In particular, we show that this evolution exhibits existence of complex periodic properties due to the presence of cosine and sine functions governing the solutions. Numerical simulations are performed for some particular cases and prove that the system describing the polymer chain degradation contains complex and simple harmonic poles whose e ects are given by these functions or a combination of them. This result may be crucial in the ongoing research to better handle and explain the phenomenon of shattering. Lastly, it has become a conjecture that power series like Mittag-Le er functions and their variants naturally govern solutions to most of generalized fractional evolution models such as kinetic, di usion or relaxation equations. The question is to say whether or not this is always true! Whence, three generalized evolution equations with an additional fractional parameter are solved analytically with conventional techniques. These are processes related to stationary state system, relaxation and di usion. In the analysis, we exploit the Sumudu transform to show that investigation on the stationary state system leads to results of invariability. However, unlike other models, the generalized di usion and relaxation models are proven not to be governed by Mittag-Le er functions or any of their variants, but rather by a parameterized exponential function, new in the literature, more accurate and easier to handle. Graphical representations are performed and also show how that parameter, called ; can be used to control the stationarity of such generalized models. / Mathematical Sciences / Ph. D. (Applied Mathematics)

A substantial number of employees in South Africa may soon be out of work as the result of their HIV-positive status. The dismissal of an infected employee may be motivated by the fact that he is considered to be incompetent or incapable of doing the work for which he was employed. Customers and fellow employees may refuse to deal with an infected employee, with the result that the employee is dismissed for economic reasons. The nature of the undertaking's activities may be such that the presence of an infected employee constitutes a health risk. For the purposes of carrying out his duty to create and maintain safe working conditions, the employer dismisses the employee. The employer may even force the infected employee to resign. Measures should be taken to improve the situation of infected employees. They include educating employers and employees about the transmission of the human immunodeficiency virus. / Mercentile Law / LL. M.

Made available in DSpace on 2014-12-17T14:10:19Z (GMT). No. of bitstreams: 1 FredericoLS_DISSERT.pdf: 1177174 bytes, checksum: efe72b5694aaae13f9be30ff705ec1c9 (MD5) Previous issue date: 2010-10-27 / The pair contact process - PCP is a nonequilibrium stochastic model which, like the basic contact process - CP, exhibits a phase transition to an absorbing state. While the absorbing state CP corresponds to a unique configuration (empty lattice), the PCP process infinitely many. Numerical and theoretical studies, nevertheless, indicate that the PCP belongs to the same universality class as the CP (direct percolation class), but with anomalies in the critical spreading dynamics. An infinite number of absorbing configurations arise in the PCP because all process (creation and annihilation) require a nearest-neighbor pair of particles. The diffusive pair contact process - PCPD) was proposed by Grassberger in 1982. But the interest in the problem follows its rediscovery by the Langevin description. On the basis of numerical results and renormalization group arguments, Carlon, Henkel and Schollw?ck (2001), suggested that certain critical exponents in the PCPD had values similar to those of the party-conserving - PC class. On the other hand, Hinrichsen (2001), reported simulation results inconsistent with the PC class, and proposed that the PCPD belongs to a new universality class. The controversy regarding the universality of the PCPD remains unresolved. In the PCPD, a nearest-neighbor pair of particles is necessary for the process of creation and annihilation, but the particles to diffuse individually. In this work we study the PCPD with diffusion of pair, in which isolated particles cannot move; a nearest-neighbor pair diffuses as a unit. Using quasistationary simulation, we determined with good precision the critical point and critical exponents for three values of the diffusive probability: D=0.5 and D=0.1. For D=0.5: PC=0.89007(3), β/v=0.252(9), z=1.573(1), =1.10(2), m=1.1758(24). For D=0.1: PC=0.9172(1), β/v=0.252(9), z=1.579(11), =1.11(4), m=1.173(4) / O processo de contato por par -PCP ? um modelo estoc?stico de n?o equil?brio que se inspira no processo de contato simples -PC e que exibe uma transi??o de fase para um estado absorvente. Embora que o estado absorvente para o PC corresponda a uma ?nica configura??o (estado vazio), o PCP possui infinitas configura??es. No entanto, estudos num?ricos e te?ricos indicam que o PCP pertence a mesma classe de universalidade do PC (classe da percola??o direcionada), mas apresenta uma anomalia na din?mica de propaga??o. Um n?mero infinito de configura??es de estados absorventes surge no PCP, devido a todos os processos de cria??o e aniquila??o que requererem um par de part?culas de vizinhos mais pr?ximos. O processo de contato por par difusivo - PCPD foi proposto por Grassberger em 1982. Por?m, o interesse neste problema segue com a redescoberta por Howard; T?uber (1997), que questionaram a validade da descri??o de Langevin. Com base nos resultados num?ricos e em grupo de renormaliza??o, Carlon; Henkel ; Schollw?ck, (2001), observaram que alguns expoentes cr?ticos no PCPD apresentam valores similares ao da classe PC. Porem, Hinrichsen (2001), mostrou resultados diferentes do caso PCPD, atrav?s da simula??o, para o caso PC, propondo uma nova classe de universalidade. At? hoje existe uma controv?rsia em rela??o a classe de universalidade do PCPD. No PCPD ? necess?rio um par de part?culas vizinhas para os processos de cria??o e aniquila??o, embora as part?culas difundam individualmente. Neste trabalho, estudamos o PCPDP com difus?o de pares, no qual part?culas isoladas n?o podem difundir. Pares vizinhos difundem juntos. Usando simula??o quase-estacion?ria, determinamos com boa precis?o o ponto cr?tico e os expoentes para dois valores da probabilidade de difus?o: D=0.5, e 0.1. Para D=0.5: PC=0.89007(3), β/v=0.252(9), z=1.573(1), =1.10(2), m=1.1758(24). Para D=0.1: PC=0.9172(1), β/v=0.252(9), z=1.579(11), =1.11(4), m=1.173(4)

Made available in DSpace on 2015-03-03T15:15:25Z (GMT). No. of bitstreams: 1 MarceloBS_DISSERT.pdf: 2228867 bytes, checksum: 46ad012b7ecf9d333c9b9a88bbfb0411 (MD5) Previous issue date: 2010-08-12 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The diffusive epidemic process (PED) is a nonequilibrium stochastic model which, exhibits a phase trnasition to an absorbing state. In the model, healthy (A) and sick (B) individuals diffuse on a lattice with diffusion constants DA and DB, respectively. According to a Wilson renormalization calculation, the system presents a first-order phase transition, for the case DA > DB. Several researches performed simulation works for test this is conjecture, but it was not possible to observe this first-order phase transition. The explanation given was that we needed to perform simulation to higher dimensions. In this work had the motivation to investigate the critical behavior of a diffusive epidemic propagation with L?vy interaction(PEDL), in one-dimension. The L?vy distribution has the interaction of diffusion of all sizes taking the one-dimensional system for a higher-dimensional. We try to explain this is controversy that remains unresolved, for the case DA > DB. For this work, we use the Monte Carlo Method with resuscitation. This is method is to add a sick individual in the system when the order parameter (sick density) go to zero. We apply a finite size scalling for estimates the critical point and the exponent critical =, e z, for the case DA > DB / O processo epid?mico difusivo (PED) ? um modelo estoc?stico de n?o equil?brio que se inspira no processo de contato e que exibe uma transi??o de fase para um estado absorvente. No modelo, temos indiv?duos saud?veis (A) e indiv?duos doentes (B) se difundindo numa rede unidimensional com uma difus?o constante DA e DB, respectivamente. De acordo com os c?lculos do grupo de renormaliza??o, o sistema apresentou uma transi??o de fase de primeira ordem, para o caso DA > DB. V?rios pesquisadores realizaram trabalhos de simula??o para testar esta conjectura e n?o conseguiram observar esta transi??o de primeira ordem. A explica??o dada era que precis?vamos realizar simula??o para dimens?es maiores. Por isso, neste trabalho tivemos a motiva??o de investigarmos o comportamento cr?tico de um processo de propaga??o epid?mico difusivo com intera??o de L?vy (PEDL) em uma dimens?o. A distribui??o de L?vy tem intera??o de difus?o de todos os tamanhos levando o sistema unidimensional a um sistema de dimens?es maiores. Com isso, poderemos tentar explicar esta controv?rsia que existe at? hoje, para o caso DA > DB. Para este trabalho utilizamos o M?todo de Monte Carlo com ressuscitamento. Este m?todo consiste em acrescentar um indiv?duo doente no sistema quando o par?metro de ordem (densidade de doente) vai ? zero. Aplicamos a t?cnica de an?lise de escala de tamanho finito para determinarmos com boa precis?o o ponto cr?tico e os expoentes cr?ticos ??/v, v e z, para o caso DA > DB

Il y a de nouveaux défis dans l'administration et dans la conception des systèmes pour optimiser la gestion des ressources des applications basées en nuage Cloud Computing. Certaines applications demandent des performances rigoureuses (par exemple, par rapport aux retards et aux limites de la gigue), tandis que d'autres applications présentent des charges de travail en rafale (volatiles). Cette thèse propose un framework inspiré dans un modèle épidémique (et basé sur des Chaînes de Markov à Temps Continu), qui peut reproduire la volatilité de la charge de travail, à savoir les effets de buzz (quand il y a une augmentation soudaine de la popularité d'un contenu) d'un système de Vidéo à la Demande (VoD). Deux méthodes d'estimation (basés sur des heuristiques et des Chaînes de Markov Monte Carlo - MCMC) ont été également proposées dans ce travail, de façon à ajuster le modèle selon les comportements de la charge de travail. Les paramètres du modèle obtenus à partir des procédures d'étalonnage révèlent des propriétés intéressantes du modèle. Basé sur des simulations numériques, la précision des deux procédures a été analysée, en montrant que les deux présentent des performances raisonnables. Toutefois, la méthode MCMC dépasse la performance de l'approche heuristique. Cette thèse compare également le modèle proposé avec d'autres modèles existants, tout en examinant la qualité de l'ajustement de certaines propriétés statistiques sur des traces réelles de la charge de travail. Finalement, ce travail propose une approche probabiliste de provisionnement des ressources, basée sur le Principe de Grandes Déviations (LDP). LDP caractérise statistiquement les effets de buzz, qui causent de la volatilité extrême de la charge de travail. Cette analyse exploite les informations obtenues en utilisant le LPD du système VoD pour la définition des politiques de gestion des ressources. Ces politiques peuvent être intéressantes pour toutes les acteurs dans le nouveau contexte de l'informatique en nuage. / There are some new challenges in system administration and design to optimize the resource management for a cloud based application. Some applications demand stringent performance requirements (e.g. delay and jitter bounds), while some applications exhibit bursty (volatile) workloads. This thesis proposes an epidemic model inspired (and continuous time Markov Chain based) framework, which can reproduce workload volatility namely the "buzz effects" (when there is a sudden increase of a content popularity) of a Video on Demand (VoD) system. Two estimation procedures (heuristic and a Markov Chain Monte Carlo (MCMC) based approach) have also been proposed in this work to calibrate the model against workload traces. Obtained model parameters from the calibration procedures reveal some interesting property of the model. Based on numerical simulations, precisions of both procedures have been analyzed, which show that both of them perform reasonably. However, the MCMC procedure outperforms the heuristic approach. This thesis also compares the proposed model with other existing models examining the goodness-of-fit of some statistical properties of real workload traces. Finally this work suggests a probabilistic resource provisioning approach based on a Large Deviation Principle (LDP). LDP statistically characterizes the buzz effects that causeextreme workload volatility. This analysis exploits the information obtained using the LDP of the VoD system for defining resource management policies. These policies may be of some interest to all stakeholders in the emerging context of cloud networking.

Made available in DSpace on 2014-07-29T16:17:38Z (GMT). No. of bitstreams: 1 Leandro Carvalho Damacena Neto.pdf: 5860174 bytes, checksum: d2948cd4bdd56c4fd40f454247f3de60 (MD5) Previous issue date: 2011-03-11 / Research on the Spanish flu in Goiás aimed to understand the impacts and meanings which accounted for the population. We analyze its symptoms Spanish flu, as well as highlight the imprecision of medicine to define and characterize it, the multiple symptoms diagnosed and the variety of treatments and therapeutic measures. For this, the research is anchored in the records of the press Goiás, in the context of 1918/1919 were lodged with the population and called Advice to people: that is, they were indications of health authorities to combat the Spanish flu. More than a biological problem, the Spanish flu became a social problem, and as such has been analyzed here, from its social representation - ie, the disease constituted a problem that requires an explanation by the company attacked, it is imperative that has a social and cultural. Historicize diseases is one of the ways to understand a society. / A pesquisa sobre a gripe espanhola em Goiás teve como principal objetivo compreender os impactos e os significados que representou para a população. Buscamos analisar a sintomatologia da doença de gripe espanhola, bem como ressaltar a imprecisão da medicina ao defini-la e caracterizá-la, os múltiplos sintomas diagnosticados e a variedade de tratamentos e medidas terapêuticas. Para tanto, a pesquisa ancorou-se nos registros da imprensa goiana, que, no contexto de 1918/1919, foram dirigidos à população e denominados Conselhos ao povo;ou seja, eram indicações das autoridades sanitárias para o combate da gripe espanhola. Mais que um problema biológico, a gripe espanhola se tornou um problema social, e como tal foi aqui analisada, a partir da sua representação social ou seja, a doença constituiu-se um problema que exige uma explicação pela sociedade atacada; é imperativo que tenha sentido social e cultural. Historicizar as doenças é um dos caminhos para se compreender uma sociedade.

Le continuel développement des outils statistiques permet aujourd’hui la modélisation de nombreux phénomènes, toujours plus complexes. En combinant l’approche offerte par des modèles statistiques spécifiques, dit "multiniveaux", et leurs applications à différentes problématiques médicales, cette thèse s’inscrit à la croisée de divers domaines : celui des statistiques, de par la méthodologie sur laquelle reposent les résultats ; mais aussi, celui de l’économie de la santé et de la santé publique en général, au travers des applications présentées.La première partie de cette thèse s’intéresse aux aspects théoriques, et plus particulièrement à l’évolution des méthodologies, du modèle de régression linéaire simple aux modèles multiniveaux pour des liens non nécessairement linéaires. Le déroulé historique de la modélisation mais également les hypothèses, le principe, la stratégie d'analyse et enfin les limites y sont abordés.La seconde partie s’articule autour de deux applications multiniveaux distinctes. La première concerne les déterminants de l'observance et des interruptions de traitement, chez les personnes infectées par le virus du VIH/Sida suivant un traitement par antirétroviraux, dans le contexte du Cameroun. La seconde, quant à elle, s'intéresse au recours aux soins dentaires chez les personnes âgées de 60 ans et plus et vivant en domicile ordinaire. Ces deux applications sont comparables dans leurs méthodologies puisqu’il s’agit de déterminer les comportements étudiés par des variables individuelles habituellement retenues, mais aussi des variables de "contexte" (caractéristiques de l’offre de soins).La troisième partie est consacrée aux applications sur le panel de médecins généralistes et traite deux études autonomes. La première expose les réticences des médecins, et le rôle de leurs aprioris, face aux Recommandations de Bonnes Pratiques (RBP). Elle nous permet de déboucher sur quelques pistes pour améliorer l’usage des RBP en médecine de ville. La seconde analyse la similarité – ou parfois la dissimilarité – entre le cycle d’activité des médecins généralistes et la saisonnalité des épidémies, dans le but d’identifier les facteurs favorisant l’ajustement des médecins généralistes aux variations saisonnières des besoins des patients. Cette étude pourrait permettre, notamment, d’anticiper et de mieux gérer des situations de crise sanitaire, avec l’appui effectif de la médecine de ville. / The continual development of statistical tools allows the modelling of numerous phenomena, including the complex ones. Using a set of statistical techniques and applications, based on the so-called “multilevel” modelling, this thesis deals with different aspects related to the statistical methodology and applications as per health economics and public health.The first part reconsiders the evolution of methodology, starting from the simple linear regression techniques to the more complex multilevel modelling as applied to both the linear and non-linear relations. It addresses issues related to the historical development, the hypotheses, the strategy of analysis, and the scope of applications. The second part presents two distinct multilevel studies. The first concerns the determinants of observance and interruptions of treatment for persons infected by the HIV/AIDS and treated with antiretroviral in Cameroon. The second one focuses on the use of dental services for the elderly. The two studies are methodologically comparable in that, besides integrating the usually retained individual variables, the analyses examine health seeking behaviours, particularly, the utilisation of health care services, while accounting for contextual determinants such as the characteristics of health supply (clinic, department or region).The third part is dedicated to the applications on GPs' panel and contains two different studies. The first one explains the GPs’ behaviours and the role of their aprioris vis-à-vis Clinical Practice Guidelines (CPG), and suggests solutions to overcome their negative attitudes. The second study analyses the similarity – sometimes the differences – between the cycle of GPs’ activity and the seasonality of epidemics with the aim of better understanding determinants favouring the adjustment of the GP in the seasonal variations of the patients needs. This study helps anticipate and manage situations of sanitary crisis, with the effective support of general practitioners.

In this thesis we study several resource management problems in two classes of wireless networks. The thesis is in two parts, the first being concerned with game theoretic approaches for cellular networks, and the second with control theoretic approaches for mobile opportunistic networks. In Part I of the thesis, we first investigate optimal association and power control for the uplink of multichannel multicell cellular networks, in which each channel is used by exactly one base station (BS) (i.e., cell). Users have minimum signal to interference ratio(SINR) requirements and associate with BSs where least transmission powers are required. We formulate the problem as a non-cooperative game among users. We propose a distributed association and power update algorithm, and show its convergence to a Nash equilibrium of the game. We consider network models with discrete mobiles(yielding an atomic congestion game),as well as a continuum of mobiles(yielding a population game). We find that the equilibria need not be Pareto efficient, nor need they be system optimal. To address the lack of system optimality, we propose pricing mechanisms. We show that these prices weakly enforce system optimality in general, and strongly enforce it in special settings. We also show that these mechanisms can be implemented in distributed fashions. Next, we consider the hierarchical problems of user association and BS placement, where BSs may belong to the same(or, cooperating) or to competing service providers. Users transmit with constant power, and associate with base stations that yield better SINRs. We formulate the association problem as a game among users; it determines the cell corresponding to each BS. Some intriguing observations we report are:(i)displacing a BS a little in one direction may result in a displacement of the boundary of the corresponding cell to the opposite direction;(ii)A cell corresponding to a BS may be the union of disconnected sub-cells. We then study the problem of the placement of BSs so as to maximize service providers’ revenues. The service providers need to take into account the mobiles’ behavior that will be induced by the placement decisions. We consider the cases of single frequency band and disjoint frequency bands of operation. We also consider the networks in which BSs employ successive interference cancellation(SIC) decoding. We observe that the BS locations are closer to each other in the competitive case than in the cooperative case, in all scenarios considered. Finally, we study cooperation among cellular service providers. We consider networks in which communications involving different BSs do not interfere. If service providers jointly deploy and pool their resources, such as spectrum and BSs, and agree to serve each others’ customers, their aggregate payoff substantially increases. The potential of such cooperation can, however ,be realized only if the service providers intelligently determine who they would cooperate with, how they would deploy and share their resources, and how they would share the aggregate payoff. We first assume that the service providers can arbitrarily share the aggregate payoff. A rational basis for payoff sharing is imperative for the stability of the coalitions. We study cooperation using the theory of transferable payoff coalitional games. We show that the optimum cooperation strategy, which involves the acquisition of channels, and deployment and allocation of BSs to customers, is the solution of a concave or an integer optimization problem. We then show that the grand coalition is stable, i.e., if all the service providers cooperate, there is an operating point offering each service provider a share that eliminates the possibility of a subset of service providers splitting from the grand coalition; this operating point also maximizes the service providers’ aggregate payoff. These stabilizing payoff shares are computed by solving the dual of the above optimization problem. Moreover, the optimal cooperation strategy and the stabilizing payoff shares can be obtained in polynomial time using distributed computations and limited exchange of confidential information among the service providers. We then extend the analysis to the scenario where service providers may not be able to share their payoffs. We now model cooperation as a nontransferable payoff coalitional game. We again show that there exists a cooperation strategy that leaves no incentive for any subset of service providers to split from the grand coalition. To compute this cooperation strategy and the corresponding payoffs, we relate this game and its core to an exchange market and its equilibrium. Finally, we extend the formulations and the results to the case when customers are also decision makers in coalition formation. In Part II of this thesis, we consider the problem of optimal message forwarding in mobile opportunistic wireless networks. A message originates at a node(source), and has to be delivered to another node (destination). In the network, there are several other nodes that can assist in relaying the message at the expense of additional transmission energies. We study the trade-off between delivery delay and energy consumption. First, we consider mobile opportunistic networks employing two-hop relaying. Because of the intermittent connectivity, the source may not have perfect knowledge of the delivery status at every instant. We formulate the problem as a stochastic control problem with partial information, and study structural properties of the optimal policy. We also propose a simple suboptimal policy. We then compare the performance of the suboptimal policy against that of the optimal control with perfect information. These are bounds on the performance of the proposed policy with partial information. We also discuss a few other related open loop policies. Finally, we investigate the case where a message has to be delivered to several destinations, but we are concerned with delay until a certain fraction of them receive the message. The network employs epidemic relaying. We first assume that, at every instant, all the nodes know the number of relays carrying the packet and the number of destinations that have received the packet. We formulate the problem as a controlled continuous time Markov chain, and derive the optimal forwarding policy. As observed earlier, the intermittent connectivity in the network implies that the nodes may not have the required perfect knowledge of the system state. To address this issue, we then obtain an ODE(i.e., a deterministic fluid) approximation for the optimally controlled Markov chain. This fluid approximation also yields an asymptotically optimal deterministic policy. We evaluate the performance of this policy over finite networks, and demonstrate that this policy performs close to the optimal closed loop policy. We also briefly discuss the case where message forwarding is accomplished via two-hop relaying.

Traditional Public Health decision-support can benefit from the Web and social media revolution. This dissertation presents approaches to mining social media benefiting public health epidemiology. Through discovery and analysis of trends in Influenza related blogs, a correlation to Centers for Disease Control and Prevention (CDC) influenza-like-illness patient reporting at sentinel health-care providers is verified. A second approach considers personal beliefs of vaccination in social media. A vaccine for human papillomavirus (HPV) was approved by the Food and Drug Administration in May 2006. The virus is present in nearly all cervical cancers and implicated in many throat and oral cancers. Results from automatic sentiment classification of HPV vaccination beliefs are presented which will enable more accurate prediction of the vaccine's population-level impact. Two epidemic models are introduced that embody the intimate social networks related to HPV transmission. Ultimately, aggregating these methodologies with epidemic and social network modeling facilitate effective development of strategies for targeted interventions.

L’« enfant perturbateur » dérange et déçoit un espoir de réussite par de mauvaises notes, ou perturbe ses parents, sa famille, ses enseignants par son agitation. Dans un tel contexte, l’adulte, qui l’accompagne dans un lieu de soin, évoque à son propos une « hyperactivité », un « trouble de la concentration », ou un « trouble du comportement ». En quelques décennies, ces motifs de consultation sont devenus majoritaires au Centre Médico-Psychopédagogique de Montpellier. Sans remettre en cause les apports de la neurobiologie, nous constatons que l’« instabilité infantile psychogène transitoire » est devenue une épidémie. A partir de notre expérience clinique, de la métapsychologie freudienne, des études de sociologie, et de celles des sciences politiques, nous soutenons la thèse suivante : l’ « enfant perturbateur » souffre d’un « complexe de déprivation » (Winnicott) qu’il traduit en termes de « peur de mourir », et si la turbulence s’exprime, c’est en tant qu’elle attire l’attention d’un adulte potentiellement secourable et que les systèmes sociaux contemporains la rendent facilement repérable. L’approche psychanalytique individuelle de l’ « enfant perturbateur » est pertinente mais peut parfois rester en suspens pendant de longues périodes, cédant le pas à l’attitude de « management » décrite par Winnicott. Ceci rend possible un mouvement de régression permettant à l’enfant de renouer avec la continuité du sentiment d’exister. Dans le transfert, l’analyste occupe alors la place de « médium malléable » (Milner, Roussillon) soumis à l’omnipotence de son patient. / The agitation of “disruptive children” disturbs or upsets their parents, family and teachers, and bad marks at school lead to disappointment in terms of hope for success. In such a context, the adults who take them for treatment mention terms such as “hyperactivity”, “concentration disorder”, or “behaviour disorder”. In just a few decades, these reasons for consulting have started to dominate at the Centre Médico-Psychopédagogique (Psychoeducational Health Centre) in Montpellier.Although we do not question the contribution of neurobiology, we have observed that“transitory psychogenic infantile instability” has become an epidemic. On the basis of our clinical experience, Freudian metapsychology, sociology and political science studies, we support the following thesis: “disruptive children” suffer from a what Winnicot calls a “deprived complex” and which he translates in terms of “fear of dying”. If there is manifest unruliness, it is to attract the attention of a potentially helpful adult and because the contemporary social systems make it easily detectable.The individual psychoanalytic approach to “disruptive children” is relevant but canremain suspended over long periods of time, giving way to the “management” attitude described by Winnicott. This makes regression possible, allowing the child to return to the continuity of a sense of being. In the transference, the psychoanalyst then plays the role of the “pliable medium” (Milner, Roussillon) subject to his patient’s omnipotence.