Études biologiques et comportementales de deux espèces de moustiques (Aedes albopictus et Anopheles arabiensis) vectrices de maladies en vue du développement de la Technique de l'Insecte Stérile (TIS) contre ces vecteurs à l'île de la Réunion

Les femelles moustiques peuvent être vectrices de nombreux agents infectieux (virus, protozoaires, helminthes) pour l'Homme, qui peuvent être la cause de maladies graves comme le paludisme et la dengue. Ces maladies menacent respectivement 50 et 40% de la population mondiale ; le paludisme étant responsable de près d'un million de décès par an. Les méthodes de lutte anti-vectorielle destinées à limiter les populations vectrices et stopper la transmission de maladies, se heurtent au développement incessant de résistances de la part des moustiques et des agents infectieux vis-à-vis des traitements employés. Bien que certaines régions du monde aient réussi à stopper efficacement la transmission de certaines de ces maladies, une grande partie des régions tropicales reste menacée. De plus l'expansion rapide de certaines espèces vectrices, telles qu'Aedes albopictus, accroît les risques sanitaires dans de nouvelles régions du globe. La technique de l'insecte stérile (TIS), qui a permis l'éradication ou la suppression des populations de nombreux insectes nuisibles aux cultures et à l'Homme, représente un moyen de lutte prometteur contre les moustiques. Cette technique s'appuie sur le lâcher en masse de mâles stérilisés par rayonnements ionisants qui, en transférant un sperme stérile aux femelles sauvages, vont permettre une diminution progressive de la population cible. Suite à l'épidémie de chikungunya à l'île de la Réunion en 2005 et face aux menaces permanentes de recrudescence de la dengue et du paludisme, les services de lutte anti-vectorielle réunionnais mettent en place d'importants moyens de lutte contre les populations de moustiques concernées. Toutefois, ces mesures ne permettant pas une diminution durable des densités de vecteurs, une étude de faisabilité est en cours quant à l'utilisation de la TIS pour diminuer et contrôler les populations d Aedes albopictus, vecteur de la dengue et du chikungunya, et d Anopheles arabiensis, vecteur du paludisme.Ce travail de thèse s'inscrit dans le cadre du projet TIS Réunion, dans le but d'étudier la biologie et le comportement des souches destinées aux lâchers de mâles stériles. Dans un premier temps, cette étude s'intéresse à la comparaison entre les souches d'élevage d Anopheles arabiensis et les souches sauvages, ainsi qu'aux modalités de stérilisation des mâles de la souche à sexage génétique. Une seconde partie est consacrée à l'étude de l'effet de l'irradiation sur les mâles d Aedes albopictus, en étudiant plus particulièrement leur stratégie de reproduction, leur capacité d'insémination en laboratoire, ainsi que leur compétitivité sexuelle et longévité face aux mâles sauvages en conditions semi-contrôlées.Mosquito females are potential vectors of numerous pathogens (viruses, protozoa, helminths), which can cause serious diseases such as malaria and dengue in humans. These two infectious diseases are threatening 50 and 40% of the world population respectively. Malaria is responsible for nearly one million deaths per year, and is considered by many experts as the most important insect-transmitted disease. Antivectorial control methods, intended to limit the vector populations and to stop the disease transmission have to face many challenges such as the development of mosquitoes' and pathogens' resistance to the treatments employed to control them. Although various regions of the world have succeeded in efficiently stopping the transmission of some diseases, most of the tropical regions remain under threat. In addition, the rapid expansion of some vector species, such as Aedes albopictus, increases the risks in previously safe areas of the world. The sterile insect technique (SIT) has allowed the eradication or suppression of various insect pest populations threatening crops, animal, and human health, and could offer a promising control tool against mosquitoes. The classical SIT relies on the mass releases of males sterilized by ionizing radiation;they transfer sterile sperm to wild females, which results in a progressive reduction of the target population.Following the chikungunya outbreak in Reunion Island in 2005 and considering the constant threat of arecrudescence of dengue and malaria, the anti-vectorial services in Reunion Island are deploying important means to control the relevant mosquito populations. However, these measures do not confer a permanent, or long-lasting reduction of vector densities. A feasibility study is ongoing, evaluating the use of the SIT to diminish and control the populations of Ae. albopictus, a vector of dengue and chikungunya, and Anopheles arabiensis, a vector of malaria. This PhD work was developed in the context of the SIT Reunion project, with the aim of studying the biology and the behaviour of some strains intended for the sterile male releases. Firstly, this study endeavours to compare colonized and wild strains of An. arabiensis, and to determine the sterilisation procedures of the genetic sexing strain males. The second part of this work studies the effect of irradiation on male Ae. albopictus, and most notably their reproductive strategy, the insemination capacity in laboratory, and finally their sexual competitiveness and longevity against wild males under semi-field conditions.SAINT DENIS/REUNION-Droit Lettre (974112101) / SudocSudocFranceF

On vortices and rings in extended Abelian models

A numerical search for straight superconducting vortices in a U(1) model with a Ginzburg-Landau potential containing a cubic term, is presented. Such vortices exist in a small numerically determined region. The reasons of their existence in that narrow region of the parameter space, as well as of their instability in the rest of the parameter space, are explained. Then, the results of a numerical search for axially symmetric solitons in a U(1)\times U(1) model with higher derivative terms, which is based on Physica D 228 (2007) 159, are presented and discussed.Comment: 24 pages, 10 figures, minor changes. Revised edition published in Physica

On axially symmetrical solitons in Abelian-Higgs models

A numerical search for bosonic superconducting static vortex rings in a $U(1)_{A}\times U(1)_{W}$ model is presented. The fate of these rings without current, is to shrink due to their tension until extinction. The superconductivity of the loop does not seem to prevent shrinking. Current quenching takes place before stabilization.Comment: 15 pages, 8 figures, Accepted for publication in Physica

Drum vortons in high density QCD

Recently it was shown that high density QCD supports of number of topological defects. In particular, there are U(1)_Y strings that arise due to K^0 condensation that occurs when the strange quark mass is relatively large. The unique feature of these strings is that they possess a nonzero K^+ condensate that is trapped on the core. In the following we will show that these strings (with nontrivial core structure) can form closed loops with conserved charge and currents trapped on the string worldsheet. The presence of conserved charges allows these topological defects, called vortons, to carry angular momentum, which makes them classically stable objects. We also give arguments demonstrating that vortons carry angular momentum very efficiently (in terms of energy per unit angular momentum) such that they might be the important degrees of freedom in the cores of neutron stars.Comment: 11 pages, accepted for publication in Physical Review

On the Behaviour and Stability of Superconducting Currents

We present analytic and numerical results for the evolution of currents on superconducting strings in the classical $U(1) \times U(1)$ model. We derive an energy functional for the currents and charges on these strings, establishing rigorously that minima should exist in this model for loops of finite size (vortons) if both charge and current are present on the worldsheet. We then study the stability of the currents on these strings, and we find an analytic criterion for the onset of instability (in the neutral limit). This limit specifies a lower maximal current than previous heuristic estimates. We conclude with a discussion of the evolution of loops towards their final vorton state in the model under consideration.Comment: 18 pages, 6 figures. To be submitted to Nuclear Physics

Interannual population dynamics of the green spruce aphid Elatobium abietinum (Walker) in France

The hypothesis that similar processes govern interannual dynamics of green spruce aphid in the UK and France, is generally supported by the application of a general discrete model. A simple model based on relatively few parameters was able to closely characterise interannual population dynamics from completely independent aerial and arboreal samples of aphids. Long term field population estimates of the green spruce aphid Elatobium abietinum (Walker) in France have provided the opportunity to select and evaluate the generality of a model which was developed in the UK to explain the year‐to‐year variations in peak abundance of the aphid. Aims The objective was to observe the influence of the local climates and disturbing climate factors on the population densities of the insect in two regions of France. Methods The model uses climate variables and aphid population data from regular samples in the two regions that were investigated. A general discrete model was used to predict aphid population densities. Results The model performed well in tracking the interannual patterns of population but was less likely to predict absolute population density. Conclusion To improve predictions, further account would need to be taken of additional site‐specific climate variables and the strength of overcompensating density dependence. Nevertheless it is clear that broadly similar processes are at work in the population dynamics of this insect across its biogeographical range

Lifestyle gambling, indebtedness and anxiety: A deviant leisure perspective

While once subject to wide-ranging state control, gambling has successfully culturally embedded itself within the normalised and legitimised forms of leisure such as the night-time economy, sports fandom and online forums of socialisation. Consequently, this article argues that existing research which conceptualises gambling as separate from everyday life is largely obsolete in the contemporary context. We argue here that gambling has become an integral feature of the wider masculine weekend leisure experience, intimately connected to an infantilised consumer identity that is peculiar to late-capitalism. This article, drawing upon ongoing ethnographic research among what we term ‘lifestyle gamblers’, utilises a deviant leisure perspective to problematise the myriad harms that emerge from this relationship, situated within a broader critique of consumerism and global capitalism. While social gambling is defended fiercely by the industry, this article argues that an identity-based culture of sports-betting that attaches fragile social and cultural capital to the allure of the gambling win encourages the chasing of losses and impulsive betting. Underscored by a culture of readily available and high-interest credit, we explore how gamblers in a technologically accelerated culture develop a pathological relationship to money as it becomes desublimated and loses its symbolic value. Such processes, exacerbated by the promise of consumer culture, have the potential to cast these young adults into a paralysing reality of indebtedness that is fraught with depression, stress, domestic instability and destructive behaviours of consumption

Stationary ring solitons in field theory - knots and vortons

We review the current status of the problem of constructing classical field theory solutions describing stationary vortex rings in Minkowski space in 3+1 dimensions. We describe the known up to date solutions of this type, such as the static knot solitons stabilized by the topological Hopf charge, the attempts to gauge them, the anomalous solitons stabilized by the Chern-Simons number, as well as the non-Abelian monopole and sphaleron rings. Passing to the rotating solutions, we first discuss the conditions insuring that they do not radiate, and then describe the spinning $Q$-balls, their twisted and gauged generalizations reported here for the first time, spinning skyrmions, and rotating monopole-antimonopole pairs. We then present the first explicit construction of global vortons as solutions of the elliptic boundary value problem, which demonstrates their non-radiating character. Finally, we describe the analogs of vortons in the Bose-Einstein condensates, analogs of spinning $Q$-balls in the non-linear optics, and also moving vortex rings in superfluid helium and in ferromagnetics.Comment: 103 pages, 31 figures. Numerous modifications in the text, a strongly expanded description of Faddeev-Skyrme knots, a new section on spinning Q-balls as light bullets, many new references. To appear in Physics Report