Are vectors able to learn about their hosts? A case study with Aedes aegypti mosquitoes

The way in which vectors distribute themselves amongst their hosts has important epidemiological consequences. While the role played by active host choice is largely unquestioned, current knowledge relates mostly to the innate response of vectors towards stimuli signalling the presence or quality of their hosts. Many of those cues, however, can be unpredictable, and therefore prevent the incorporation of the appropriate response into the vector's behavioural repertoire unless some sort of associative learning is possible. We performed a wide range of laboratory experiments to test the learning abilities of the mosquito, Aedes aegypti. Mosquitoes were exposed to choice procedures in (1) an olfactomenter and (2) a 'visual arena'. Our goal was to determine whether the mosquitoes were able to associate unconditional stimuli (blood feeding, human breath, vibration and electrical shock) with particular odours (citral, carvone, citronella oil and eugenol) and visual patterns (horizontal or vertical black bars) to which they had been previously observed to be responsive. We found no evidence supporting the hypothesis that associative learning abilities are present in adult Ae. aegypti. We discuss the possibilities that the assays employed were either inappropriate or insufficient to detect associative learning, or that associative learning is not possible in this species.

Caries prevalence in skeletal series: is it possible to compare?

Because of the relationship with subsistence, dental caries is a central issue in paleopathological research. Usually, comparisons between caries prevalence exhibited in different skeletal series are made. Dietary variation is the most common explanation for cavities prevalence. The aim of this paper is to verify if it is possible to compare caries prevalence reported on papers for archaeological skeletal series. Another goal is to determine if other factors besides diet are implicated in dental cavity prevalence explanation. Twenty six papers about dental health with caries prevalences published from 1999 to 2004 were analyzed for completeness. This assessment includes carious lesion diagnosis and characteristics, age, sex and size characteristics of samples, and prevalence calculation method. The majority of the analyzed papers do not provide adequate information in the topics listed above. Only very few implicated factors other than diet as a contributor to caries lesions development.

Does it pay to be socially responsible? Evidence from spanish retail banking sector

This paper presents a theoretical and empirical analysis of strategic competition in retail banking when some of the financial firms are non-profit organisations that invest in social activities. Banking literature about competition is fairly large, but the strategic interaction between profit maximizing and non profit maximizers has not been extensively analysed except for Purroy and Salas (1999). In this paper, a completely different approach is taken. An adaptation of Hotelling’s two stage model of spatial competition is developed to take into account consumer perceptions respect to the two different types of financial institutions. The empirical analysis confirms that consumers take into account other features different from the price, such as social contribution or closer service to make a deposit or mortgage decision. These conclusions are of interest in the debate about a firm’s social or ethical activities. It is shown that if consumers value social activities, firms can improv

Reduced ejection fraction after myocardial infarction: is it sufficient to justify implantation of a defibrillator ?

Introduction : La diminution de la fraction d'éjection après infarctus du myocarde est-elle suffisante pour justifier l'implantation prophylactique de défibrillateur ? Introduction: La diminution de la fraction d'éjection (FE) est un facteur prédictif majeur de mortalité cardiaque chez les patients avec ancien infarctus du myocarde (IM). Les plus récentes études, pour la plupart conduites à la fin des années 90, montrent une diminution de la mortalité post-hospitalière à 10 à 20% par année. Une amélioration de la survie par implantation prophylactique de défibrillateurs a été démontrée chez les patients avec dysfonction myocardique avancée après ancien IM dans la cadre de l'étude MADIT II (Multicenter Automatic Defibrillator Implantation Trial) et est depuis lors, considérée comme une thérapie recommandée. Le bénéfice de l'implantation prophylactique de défibrillateurs en terme de nombre nécessaire de patients à traiter pour prévenir un évènement est d'un intérêt primordial en raison des complications potentielles liées à la procédure et l'appareillage, des implications psychologiques ainsi qu'en raison de l'analyse coût-efficacité. Le nombre de patients à traiter est corrélé au risque actuel de mortalité rythmique, probablement influencé par les récentes avancées thérapeutiques dans la prise en charge aigue de l'IM (notamment par angioplastie primaire) et de l'insuffisance cardiaque. Or, dans '' l'étude MADIT II, le recrutement des patients était effectué entre 1997 et 2001 et l'intervalle moyen entre l'IM et le recrutement était de plus de 6 ans. Le but de l'étude était donc d'évaluer, dans la pratique générale, la mortalité actuelle de patients ayant survécu à un IM avec diminution consécutive significative de la FE. La stratification du risque sur la base des variables hospitalières a de même été explorée. Méthode: Une analyse de cohorte de patients avec infarctus aigu du myocarde admis de 1999 à 2000 a été effectuée dans 2 centres hospitaliers (un universitaire et un cantonal). Tous les dossiers cliniques des patients sortis d'hôpital avec FE documentée ≤ 0.40 ont été inclus. Les caractéristiques des patients, les procédures diagnostiques et thérapeutiques ainsi que la médication étaient reportées. La période de suivi débutait à la sortie d'hôpital. Les end-points primaires étaient la mortalité globale, la mortalité cardiaque et les morts subites. Une analyse bivariée et multivariée a été effectuée. Résultats: 165 patients ont été inclus. Durant un suivi médian de 30 mois (interquartile range 22-36), 18 patients sont décédés (5 morts classifiées comme cardiaques, 8 comme subites, 5 de causes non cardiaques). Les taux de mortalité à un et deux ans selon analyse de Kaplan-Meier étaient de 6.7 et 8.6%, respectivement. Les variables reflétant l'atteinte coronarienne et sa prise en charge (antécédent d'IM, reperfusion aigue, revascularisation complète) étaient plus significativement associées à la mortalité comparées aux variables reflétant la dysfonction myocardique (FE, classe Killip à l'admission). Conclusion : La mortalité des patients ayant survécu à un IM avec dysfonction myocardique avancée a diminué de façon substantielle depuis la fin des années 90. La diminution de la mortalité rythmique implique une augmentation proportionnelle du nombre de patients à traiter par implantation de défibrillateur pour prévenir un évènement. Par ailleurs, une stratification du risque après IM basée uniquement sur la FE semble être inappropriée au vu de son impact mineur sur la mortalité comparé aux autres facteurs de risque identifiés dans notre étude. Les patients sans antécédents d'infarctus et ceux ayant bénéficié d'une revascularisation aigue ou complète avait une mortalité cumulée à 2 ans de, respectivement, 2.5%, 3.9% et 2.3%. Pour ce type de patients à bas risque le bénéfice de l'implantation prophylactique de défibrillateur doit être remis en question. Au vu de cette étude, une stratification additionnelle du risque avant implantation de défibrillateur est à considérer.

Prevalence and factors associated with difficulty and intention to quit smoking in Switzerland.

BACKGROUND: Recent data indicate a slight decrease in the prevalence of smoking in Switzerland, but little is known regarding the intention and difficulty to quit smoking among current smokers. Hence, we aimed to quantify the difficulty and intention to quit smoking among current smokers in Switzerland. METHODS: Cross-sectional study including 607 female and 658 male smokers. Difficulty, intention and motivation to quit smoking were assessed by questionnaire. RESULTS: 90% of women and 85% of men reported being "very difficult" or "difficult" to quit smoking. Almost three quarters of smokers (73% of women and 71% of men) intended to quit; however, less than 20% of them were in the preparation stage and 40% were in the precontemplation stage. On multivariate analysis, difficulty to quit was lower among men (Odds ratio and 95% [confidence interval]: 0.51 [0.35-0.74]) and increased with nicotine dependence and number of previous quitting attempts (OR=3.14 [1.75-5.63] for 6+ attempts compared to none). Intention to quit decreased with increasing age (OR=0.48 [0.30-0.75] for ≥65 years compared to <45 years) and increased with nicotine dependence, the number of previous quitting attempts (OR=4.35 [2.76-6.83] for 6+ attempts compared to none) and among non-cigarette smokers (OR=0.51 [0.28-0.92]). Motivation to quit was inversely associated with nicotine dependence and positively associated with the number of previous quitting attempts and personal history of lung disease. CONCLUSION: Over two thirds of Swiss smokers want to quit. However, only a small fraction wishes to do so in the short term. Nicotine dependence, previous attempts to quit or previous history of lung disease are independently associated with difficulty and intention to quit.

Is it Time to Change Your Hat?, 2003

A one page informational sheet about skin cancer and the hat you wear. Sun Safety

Illusory correlation in the remuneration of chief executive officers: It pays to play golf, and well

Illusory correlation refers to the use of information in decisions that is uncorrelated with the relevantcriterion. We document illusory correlation in CEO compensation decisions by demonstrating thatinformation, that is uncorrelated with corporate performance, is related to CEO compensation. We usepublicly available data from the USA for the years 1998, 2000, 2002, and 2004 to examine the relationsbetween golf handicaps of CEOs and corporate performance, on the one hand, and CEO compensationand golf handicaps, on the other hand. Although we find no relation between handicap and corporateperformance, we do find a relation between handicap and CEO compensation. In short, golfers earnmore than non-golfers and pay increases with golfing ability. We relate these findings to the difficultiesof judging compensation for CEOs. To overcome this and possibly other illusory correlations inthese kinds of decisions, we recommend the use of explicit, mechanical decision rules.

Does it cost to be virtuous? The macroeconomic effects of fiscal constraints

We study whether and how fiscal restrictions alter the business cycle features of macrovariables for a sample of 48 US states. We also examine the typical transmission properties of fiscal disturbances and the implied fiscal rules of states with different fiscal restrictions. Fiscal constraints are characterized with a number of indicators. There are similarities in second moments of macrovariables and in the transmission properties of fiscal shocks across states with different fiscal constraints. The cyclical response of expenditure differs in size and sometimes in sign, but heterogeneity within groups makes point estimates statistically insignificant. Creative budget accounting is responsible for the pattern. Implications for the design of fiscal rules and the reform of the Stability and Growth Pact are discussed.

IEEE LOM is not an option. Lessons to learn

Although some projects and most LMS still rely on IEEE LOM, this standard is not yet an option. We suggest some lessons to learn.