Climate-Based Models for Understanding and Forecasting Dengue Epidemics

Dengue fever is a major public health problem in the tropics and subtropics. Since no vaccine exists, understanding and predicting outbreaks remain of crucial interest. Climate influences the mosquito-vector biology and the viral transmission cycle. Its impact on dengue dynamics is of growing interest. We analyzed the epidemiology of dengue in Noumea (New Caledonia) from 1971 to 2010 and its relationships with local and remote climate conditions using an original approach combining a comparison of epidemic and non epidemic years, bivariate and multivariate analyses. We found that the occurrence of outbreaks in Noumea was strongly influenced by climate during the last forty years. Efficient models were developed to estimate the yearly risk of outbreak as a function of two meteorological variables that were contemporaneous (explicative model) or prior (predictive model) to the outbreak onset. Local threshold values of maximal temperature and relative humidity were identified. Our results provide new insights to understand the link between climate and dengue outbreaks, and have a substantial impact on dengue management in New Caledonia since the health authorities have integrated these models into their decision making process and vector control policies. This raises the possibility to provide similar early warning systems in other countries

Investissement corporel et coût du financement externe : identification de différents régimes et rôle du crédit-bail

The aim of this article is to test the assumption of complementarity between leasing and “ traditional” borrowing on the basis of the estimation of an Euler equation for investment incorporating an agency premium, measured for firms using leasing in two consecutive years and for firms not using leasing. The breakdown of the sample into two groups of firms according to the internal financing criterion makes it possible to distinguish between firms potentially subject to rationing on the credit market and firms facing an agency cost. For the first group, characterised by a low internal financing ratio, the assumption of absence of credit rationing is accepted, as is the hypothesis of complementarity of leasing. For the second group, the situation is the reverse : agency costs are not significantly different from zero (whether the firms use leasing or not), while the assumption of absence of credit rationing is strongly rejected.L’objet de cet article est de tester l’hypothèse de complémentarité du crédit-bail au crédit «classique » à partir de l’estimation d’une équation d’Euler de l’investissement incorporant une prime d’agence, mesurée pour des entreprises faisant usage du crédit-bail deux années consécutives et pour celles n’en faisant pas usage. La segmentation de l’échantillon en deux groupes d’entreprises, suivant le critère d’autofinancement, permet de discriminer entre les firmes potentiellement rationnées sur le marché du crédit et celles faisant face à un coût d’agence. Pour le premier groupe, caractérisé par un faible ratio d’autofinancement, l’hypothèse d’absence de rationnement du crédit est acceptée, de même que l’hypothèse de complémentarité du crédit-bail. Pour l’autre groupe, la situation est inverse : les coûts d’agence sont non significativement différents de zéro (que les entreprises fassent ou non usage du crédit-bail), alors que l’hypothèse d’absence de rationnement du crédit est fortement rejetée.Teurlai Jean-Christophe. Investissement corporel et coût du financement externe : identification de différents régimes et rôle du crédit-bail. In: Économie & prévision, n°157, 2003-1. pp. 51-70

Les déterminants de la demande en crédit-bail

Teurlai Jean-Christophe. Les déterminants de la demande en crédit-bail . In: Revue d'économie financière, n°54, 1999. Le financement des PME, sous la direction de Dominique Vallet. pp. 151-162

Pitfalls in Investment Euler Equations

International audienceThis paper investigates three pitfalls concerning the test of the Euler equation facing quadratic adjustment costs and perfect capital markets on a large balanced panel data of 4025 French firms. First, the quadratic parameterization of adjustment costs is too restrictive, and power series approximations of adjustment costs are tested. Second, we isolate firms whose optimal Euler condition is not altered even in the presence of fixed adjustment costs. Third, we identify instruments which contribute to model failure via standard GMM tests. These methods point out that financial instruments contribute to reject strongly the standard model, which shows that it is misspecified

Euler investment equation, leverage and cash flow misspecification: An empirical analysis on a panel of French manufacturing firms

Using a large panel of French manufacturing firms, this paper first reports tests for cash flow misspecification in structural Euler equation including or not leverage. If those tests are not rejected for both Euler equations, in a second step, a direct test on the omission of leverage in the Euler equation is reported. Three groups of "financially healthy" firms (high dividend payout, rising debt, high cash flow with respect to investment) exhibit (in some cases, small) risk premia which significantly increases with leverage. The neo-classical Euler equation is rejected on all groups of firms that have been investigated

Le recours au crédit-bail permet-il d'identifier des entreprises à l'origine du canal du crédit ?

This paper analyzes the effect of financial constraints on the investment behaviour of French industrial firms testing Euler equations on various sub-samples over the period 1993-1996. More precisely, we test the model with an increasing cost of borrowing as leverage increases including an agency premium parameter. First of all, the agency premium parameter is not significant for the full sample and for subsamples by sizes of firms and by the extent of use of leasing as a means of finance. But when splitting the sample by leasing and the increase of debt, it turns out that the agency premium parameter is significant for firms with a relatively high increase of debt and a high level of leasing.Classification JEL : C23, D21, D92

Socio-economic and Climate Factors Associated with Dengue Fever Spatial Heterogeneity: A Worked Example in New Caledonia

International audienceUnderstanding the factors underlying the spatio-temporal distribution of infectious diseases provides useful information regarding their prevention and control. Dengue fever spatio-temporal patterns result from complex interactions between the virus, the host, and the vector. These interactions can be influenced by environmental conditions. Our objectives were to analyse dengue fever spatial distribution over New Caledonia during epidemic years, to identify some of the main underlying factors, and to predict the spatial evolution of dengue fever under changing climatic conditions, at the 2100 horizon. We used principal component analysis and support vector machines to analyse and model the influence of climate and socio-economic variables on the mean spatial distribution of 24,272 dengue cases reported from 1995 to 2012 in thirty-three communes of New Caledonia. We then modelled and estimated the future evolution of dengue incidence rates using a regional downscaling of future climate projections. The spatial distribution of dengue fever cases is highly heterogeneous. The variables most associated with this observed heterogeneity are the mean temperature, the mean number of people per premise, and the mean percentage of unemployed people, a variable highly correlated with people's way of life. Rainfall does not seem to play an important role in the spatial distribution of dengue cases during epidemics. By the end of the 21st century, if temperature increases by approximately 3°C, mean incidence rates during epidemics could double. In New Caledonia, a subtropical insular environment, both temperature and socio-economic conditions are influencing the spatial spread of dengue fever. Extension of this study to other countries worldwide should improve the knowledge about climate influence on dengue burden and about the complex interplay between different factors. This study presents a methodology that can be used as a step by step guide to model dengue spatial heterogeneity in other countries