Ecological immunology of mosquito-malaria interactions: Of non-natural versus natural model systems and their inferences

There has been a recent shift in the literature on mosquito/Plasmodium interactions with an increasingly large number of theoretical and experimental studies focusing on their population biology and evolutionary processes. Ecological immunology of mosquito-malaria interactions - the study of the mechanisms and function of mosquito immune responses to Plasmodium in their ecological and evolutionary context - is particularly important for our understanding of malaria transmission and how to control it. Indeed, describing the processes that create and maintain variation in mosquito immune responses and parasite virulence in natural populations may be as important to this endeavor as describing the immune responses themselves. For historical reasons, Ecological Immunology still largely relies on studies based on non-natural model systems. There are many reasons why current research should favour studies conducted closer to the field and more realistic experimental systems whenever possible. As a result, a number of researchers have raised concerns over the use of artificial host-parasite associations to generate inferences about population-level processes. Here I discuss and review several lines of evidence that, I believe, best illustrate and summarize the limitations of inferences generated using non-natural model systems

Place de l'hospitalisation dans un programme pour psychose débutante : Etude d'une cohorte prospective lausannoise

Introduction Le programme TIPP, spécialisé dans l'intervention lors de la phase précoce des troubles psychotiques, a pour objectif d'adapter les soins aux besoins des patients afin de faciliter leur engagement et l'accès aux soins et de diminuer la durée de psychose non traitée (DUP). Cette étude remet en perspective l'utilité de l'hospitalisation, ses bienfaits et les potentiels avantages d'y recourir de manière plus systématique. Méthode Les données du programme TIPP analysées rétrospectivement ont été récoltées de manière prospective entre 2004 et 2013. Les patients inclus, au nombre de 240, ont été accompagnés pendant 3 ans par le pôle ambulatoire, le pôle hospitalier et le suivi intensif dans le milieu. Les caractéristiques des patients admis à l'hôpital ont été observées et les caractéristiques ainsi que l'évolution des patients hospitalisés précocement, tardivement et ceux qui n'ont pas nécessité d'hospitalisation ont été comparées. Résultat et Discussion Les symptômes psychotiques positifs sont les plus fréquents lors des admissions. Les comportements auto/hétéroagressifs, la précarité, la toxicomanie et les familles ne parvenant plus à faire face à la situation sont tous des facteurs de risques d'admissions à répétition. Les patients hospitalisés fonctionnent moins bien et sont plus symptomatiques en début de programme. Ceux hospitalisés précocement évoluent mieux que ceux hospitalisés tardivement, leur taux de rémission étant plus important et récupèrent un niveau de fonctionnement similaire à celui des patients non-hospitalisés. Conclusion Lorsqu'elle s'avère nécessaire, l'hospitalisation précoce est de meilleur pronostic que lorsqu'elle survient tardivement. La DUP courte et l'évolution favorable des patients hospitalisés permettent d'émettre l'hypothèse que l'hôpital joue un rôle clé dans la prise en charge. Les patients non-hospitalisés qui ne retrouvent pas leur niveau de fonctionnement prémorbide pourraient en profiter également. Une étude randomisée complémentaire permettrait de mesurer l'impact réel de l'hospitalisation afin de justifier son recours plus systématique

Dynamics of Hen Flea Ceratophyllus gallinae Subpopulations in Blue Tit Nests

The hen flea is a common parasite in bird nests, in particular, in tit species, and imposes considerable fitness costs for the host. These costs are expected to lead to selection for increased host defense, which in turn should select for better-adapted parasites. Our understanding of the coevolution of this host-parasite system is currently limited by the insufficient knowledge of both the timing of flea generations and their reproductive behavior within the nesting period of their hosts. In the present study we (1) followed the demography of experimental flea subpopulations during the host's breeding cycle, (2) assessed the importance of time-temperature effects in the nest by recording temperatures within the nest material, and (3) investigated the influence of variation in host timing and duration of the breeding period on flea development. We found the following. (1) Fleas completed either one or two generations within the birds' nesting cycle, leading to two well-defined periods of cocoon formation. (2) Within-nest temperatures during the warm period of the host breeding cycle—i.e., the incubation and nestling periods—depended on both outdoor temperatures and heat production from the breeding birds. Day-degree availability, a measure of physiological time, during the host incubation was significantly explained by the duration of incubation period and its timing in the season. Similarly, day-degrees during the warmer nestling period were significantly explained by its duration and its timing in the season. (3) The number of flea larvae found in the nests correlated with the host's timing and duration of the warm period available for their development; this was not the case, however, for the number of adult fleas. These results underline the importance of time-temperature effects as determinants of flea demography within the nests. The life-cycle and time-temperature effects are discussed in the light of potential host selection on parasite behavior and life historie

Gene flow among populations of Anopheles gambiae: a critical review

The success of genetic-control programmes aimed at introducing genes into wild Anopheles gambiae populations depends on our understanding of the genetic structure of these populations. Population-genetic studies are required for identifying discrete population groups across Africa, determining their geographical distribution and evaluating the degree to which they may be reproductively isolated. Population studies are also needed to estimate the rate at which genes may spread within and between populations at various spatial scales and to identify biological and physical features of the environment that may interfere with their movement. Studies of the mechanisms of reproductive isolation between molecular/chromosomal forms of An. gambiae can be used to validate the results of population-genetic approaches and aid in the development of reproductively competitive laboratory strains. In the following, we review past and recent studies that cover these aspects of An. gambiae population genetics and ecology. We critically discuss the validity of the designs and methodologies involved in an attempt to provide a sound basis for future undertakings. We also discuss new directions and priorities in the light of the recent developments toward a genetic-control strategy for An. gambia

Pétrarque, la parole silencieuse

à Arnaldo Pizzorusso Et tacendo dicea (Rime, 123, 13) Les historiens s’accordent en général pour attribuer à Pétrarque une place inaugurale dans la culture dite humaniste, une culture qui sacrifie avant tout aux divinités de la parole. On restitue alors celle des Anciens. On valorise le verbe en lui conférant un pouvoir inédit sur les âmes, la capacité de les convertir au bien, au vrai et au beau. Son œuvre tant latine qu’italienne fournirait presque à l’infini des citations où la puissance b..

Ein Instrument der parlamentarischen Mitwirkung im Bereich der schweizerischen Aussenpolitik : die Information und Konsultation gemäss Art. 152 Parlamentsgesetz

Dass der Weg der parlamentarischen Mitwirkung im Bereich der Aussenpolitik steinig werden sollte, widerspiegelte sich bereits in der Entstehungsgeschichte der Aussenpolitischen Kommissionen (APK). Diese haben zum heutigen Zeitpunkt unter anderem dafür zu sorgen, dass das Parlament seine Mitwirkungsrechte in auswärtigen Angelegenheiten frühzeitig und wirk¬sam wahrnehmen kann. Nebst verschiedensten Instrumenten auf Verfassungs- und Gesetzesebene steht den APK ein wichtiges Mitwirkungsinstrument zur Verfügung: die Information und Konsultation gemäss Art. 152 Parlamentsgesetz (ParlG). Seit Inkrafttreten dieser Bestimmung im Dezember 2003 offenbart sich jedoch, dass sich die praktische Umsetzung des Gesetzesartikels mit den damaligen Vorstellungen des Gesetzgebers anlässlich der Erarbeitung dieses parlamentarischen Instrumentes nicht deckt. Der Gesetzgeber wies seiner¬zeit auf das für die Umsetzung bedeutende Vertrauensverhältnis zwischen Bundesrat und Parlament hin. Allerdings beeinflussen nun Spannungen und Konkurrenz zwischen der Exekutive und der Legislative die Umsetzung von Art. 152 ParlG. Die vorliegende Arbeit versucht, die geschichtlichen Hintergründe, die Entstehung, den Sinn und Zweck sowie die Praxis von Art. 152 ParlG vor dem Hintergrund des erwähnten Spannungsfelds und im Zusammenspiel mit den weiteren Mitwirkungsinstrumenten im Bereich der Aussenpolitik darzulegen. Comme le montre déjà l'historique des Commissions de politique extérieure (CPE), la participation du Parlement à la politique extérieure n'est pas dénuée d'obstacles. A l'heure actuelle, les CPE doivent notamment faire en sorte que le Parlement puisse faire valoir, en amont et avec efficacité, son droit de participation dans le domaine de la politique étrangère de la Suisse. Outre divers instruments figurant dans la Constitution et les lois, les CPE disposent d'un important moyen de participation: l'information et la consultation au sens de l'art. 152 de la loi sur le Parlement (LParl). Depuis l'entrée en vigueur de cette disposition en décembre 2003, il s'avère toutefois que l'application concrète de cet article de loi ne ré¬pond pas entièrement aux attentes du législateur lors de l'élaboration de cet instrument parlementaire. En effet, le législateur s'était alors basé sur la relation de confiance entre le Conseil fédéral et le Parlement, relation essentielle à la mise en oeuvre de cet article. La pratique montre cependant que la mise en oeuvre de l'art. 152 LParl est influencée par des tensions et par une relation de concurrence existant entre l'exécutif et le législatif. Le présent travail entend exposer le contexte historique de l'art. 152 LParl, son élaboration, son but et sa mise en oeuvre, tout en tenant compte des éléments de tension et des autres instruments permettant la participation en matière de politique extérieure

A Journey to Understanding: Developing Computational Fluency in Multi-digit Multiplication

This thesis presents a domain-specific instructional theory for multi-digit multiplication, focused on building students’ conceptual understanding and computational fluency. Multiplicative thinking is crucial to students’ mathematical development. Without a sound understanding of multiplicative structure students’ capacity to develop deep understanding and fluency in fractions, decimals, proportional reasoning and ratios is severely limited. Understanding multiplicative structure enables students to move beyond additive strategies such as skip counting and repeated addition, to efficient and sophisticated strategies that grow from their ability to think simultaneously about composite units. While there has been substantial research into early stages of students’ understanding in multiplication, there has been limited work exploring the more complex domain of multi-digit multiplication. The domain-specific instructional theory developed through the research described in this thesis includes a number of key features that build on and expand existing research. It draws on social constructivist perspectives to document the social and cognitive development of learners by uncovering, examining and analysing the mathematical practices that emerge through the collective learning in the classroom. Students’ invented strategies for multi-digit multiplication problems are connected to key developmental understandings of commutativity, associativity and distributivity. The crucial role of the array is explored in the process of students’ sense-making and reasoning. The theory developed in the research proposes an instructional sequence from a model of specific, contextualised situations, through to a model for more generalised mathematical reasoning in the domain of multi-digit multiplication. Design Research methods were used to inform the development of the domain-specific instructional theory. A hypothetical learning trajectory was constructed based on a review of relevant research-based literature into students’ use of the array and on curriculum documentation guiding teachers’ practices. The learning trajectory was tested in two separate teaching experiments, each involving ten teaching episodes conducted over a two-week period. Work samples, video and interview responses from a total of 55 Year 5 students from two classes were analysed and used to inform evidence-based refinement and modification of the learning trajectory. Ways in which learning could be supported through the implementation of the learning trajectory were also documented. Several key findings emerged through the design research. Students used a variety of invented strategies that drew on additive and multiplicative thinking, in some cases exclusively and in others, in combination. Students’ reasoning and justification relied predominately on the array, enabling them to make sense of the multiplicative structure in a way that symbolic recording alone did not. A number of different forms of the array were used in the study, with students electing to use different forms of the array based on the function they needed the array to serve. As students’ appreciation of and confidence with the multiplicative structure increased, their reliance on the array decreased, allowing them to move to more numerical notation underpinned by the sense-making developed through use of the array. Four mathematical practices relating to the social development of students’ understanding of the multiplicative structure were identified. Two of these: partitioning based on place value, and; using factors to manipulate the array, were based on students’ use of the array as a tool for sense-making. The other two, thinking multiplicatively, and; looking for friendly numbers, were based on ways that the students worked mathematically. Additionally, a set of five mathematical norms was identified as central to each students’ development of these mathematical practices. These were: looking for similarity and difference; making inferences; using representations; justification, and: forming generalisations. The research highlights some crucial aspects of teaching practice that are essential if students are to develop a sound understanding of multi-digit multiplication. First, instruction needs to focus on multiplicative structure built on representations that highlight fundamental mathematical properties. Second, computational fluency grows from an understanding of structure but needs to be explicitly developed through focused discussion of the mathematical features of particular strategies and representations. Third, mathematics classrooms must be focused on sense-making through carefully orchestrated discussion of students’ invented strategies and representations. Finally, the affordances and constraints of different forms of representation must be recognised in order to make clear the function that each of the possible forms might perform. The research therefore adds to the existing literature relating to multi-digit multiplication and to that relating to the development of sociomathematical norms. It brings cognitive and social perspectives of learning together in a new way, proposing a focus on form and function in multiplicative thinking and a set of transcendent mathematical norms that underpin students’ reasoning in mathematics