M\'ethode de Mahler: relations lin\'eaires, transcendance et applications aux nombres automatiques

This paper is concerned with Mahler's method. We study in detail the structure of linear relations between values of Mahler functions at algebraic points. In particular, given a field ${\bf k}$, a Mahler function $f(z)\in{\bf k}\{z\}$, and an algebraic number $\alpha$, $0<\vert \alpha\vert <1$, that is not a pole for $f$, we show that one can always determined whether the number $f(\alpha)$ is transcendental or not. In the latter case, we obtain that $f(\alpha)$ belong to the number fields ${\bf k}(\alpha)$. We also consider some consequences of such results to a classical number theoretical problem: the study of sequences of digits of algebraic numbers in an integer (or, more generally, algebraic) base. Our results are based on a theorem of Philippon [31] that we refine. We also simplify his proof.Comment: 46 pp, in Frenc

MÉTHODE DE MAHLER : RELATIONS LINÉAIRES, TRANSCENDANCE ET APPLICATIONS AUX NOMBRES AUTOMATIQUES

— Cet article est consacré à la méthode de Mahler. Nous décrivons en détail la structure des relations de dépendance linéaire entre les valeurs aux points algébriques de fonctions mahlériennes. Étant donnés un corps de nombres k, une fonction mahlérienne f (z) ∈ k{z} et α un nombre algébrique, 0 < |α| < 1, qui n'est pas un pôle de f , nous montrons notamment que l'on peut toujours déterminer si le nombre f (α) est transcendant ou non. Dans ce dernier cas, nous obtenons que f (α) appartient nécessairement à l'extension k(α). Nous considérons également les conséquences remarquables de cette théorie concernant un problème arithmétique classique : l'étude de la suite des chiffres des nombres algébriques dans une base entière ou, plus généralement, algébrique. Nos résultats sont obtenus à partir d'un théorème récent de Philippon [31] que nous raffinons et dont nous simplifions la démonstration

Heartwater surveillance in Guadeloupe: a model of partnership between research and surveillance for the Caribbean

Heartwater, a tick-borne disease of ruminants transmitted by Amblyomma ticks is present in 3 Caribbean islands: Guadeloupe, Marie-Galante and Antigua, representing a threat for neighboring islands and North America. Despite the availability of efficient acaricides, no significant improvement has been seen in vector and disease control. The Ticks and tick borne disease working group of the Caribbean animal health network (CaribVET) recommended Guadeloupe the conduct of (1) a sociologic study to understand farmers' reluctance to adopt efficient treatment; and (2) heartwater surveillance. A passive surveillance network monitoring ruminant neurological syndromes, RESPANG, was set up in July 2010. RESPANG objectives are to assess the burden of heartwater and sensitize farmers. Private veterinarians collect blood and ticks after farmer reporting of clinical suspicion. Diagnostic for heartwater, babesiosis and anaplasmosis is performed at CIRAD. An online database displays results on interactive maps allowing the identification of areas where communication campaigns by farmer association can be focused. Leaflets and key messages were developed, based on the recommendations of the sociological survey. Out of 238 suspicions, 30.5% were positive for heartwater all along the year. Analysis of the factors associated with heartwater is currently ongoing. RESPANG shows excellent partner involvement and interaction. Surveillance performance indicators will improve network operation and coordination. Long-term data set will enable to assess the impact of communication campaign and possibly to detect introduction of diseases with similar clinical signs. In parallel, pathogen and vector genetic characterization is being developed using RESPANG samples. This shows the tight link between surveillance network and research activities. CaribVET supports the establishment of similar networks for other diseases in other Caribbean islands. (Texte intégral

Key factors for sustainability of regional animal health networks: CaribVET example

CaribVET is a collaborative network of veterinary services, research institutes and regional/international organizations whose objective is to improve animal and veterinary public health in the Caribbean. Set up on a bottom-up process about 15 years ago, CaribVET progressively achieved recognition and was officially endorsed in 2006 by the CARICOM as the Caribbean Animal Health Network. In 2010, it expanded to 32 countries and territories and 10 regional/international organizations. Its operation relies on a Steering Committee, a Coordination Unit and 6 working groups. Efficient and coordinated set of initiatives, projects and funding from different partners, mutual trust and responsibilities handover are essential for its sustainability. Quality Assurance principles are being implemented including formalized organization, clear rules (trilingual charter), and traceability (members, data) to improve network efficiency and operation. Interaction between professionals working in research, surveillance or control allows the definition of (1) relevant research questions according to needs evidenced in the field; (2) scientifically-based recommendations/tools to improve prediction of emergence (pathogen evolution, population dynamics); disease surveillance (design risk-based surveillance) and control strategies (appropriate treatment, vaccine, vector controls). Such interactions ensure implementation by decisions makers of research outputs, guarantee of sustainable improvement of animal health. These approaches contribute to network long-term operation to be complemented by cost-benefit studies and performance indicators development to gain advocacy of policy makers at the highest level of country members, about the essential role of CaribVET to support national networks and improve their prediction, prevention and control capacities. (Texte intégral

Building capacities in Caribbean animal health in the : The VEP (Veterinary Epidemiologist / Para-Epidemiologist) Project

Disease surveillance and control within the Caribbean has historically been difficult. The region is made up of over 31 countries, territories, and protectorates, with concomitant differences in language, culture, and historical experiences. Given the diversity of challenges the region faces in terms of disease introduction and spread, there is a need for longer-term, sustainable training in epidemiology, surveillance, and emergency response. The Veterinary Epidemiology/Para-epidemiology Project (VEP) was a four-year, capacity-building project conducted in 9 countries in the Caribbean region: Antigua and Barbuda, Barbados, Dominica, Dominican Republic, Grenada, Haiti, St. Lucia, St. Kitts and Nevis, and St. Vincent and the Grenadines. Project participants (10) received training in 7 key domains: epidemiologic methods, disease surveillance, diagnostic tests and sample handling, emergency preparedness and response, data management, communication and coordination, and management and leadership. Both didactic and hands-on trainings were emphasized, and all participants were required to complete an epidemiologic study in their respective countries. Project participants were mentored by experienced epidemiologists in the design and implementation of their studies. Lessons learned were identified which contributed to the success of the project overall. Coordination of the technical component of the project through the regional network for animal health, CaribVET, ensured that the project had both national and regional relevancy. Although costly, the VEP brought the participants together frequently and provided opportunities to build relationships, which strengthened cross-border communication and collaboration in the region overall. (Texte intégral

Prediction of the intramembranous tissue formation during perisprosthetic healing with uncertainties. Part 1. Effect of the variability of each biochemical factor

A stochastic model is proposed to predict the intramembranous process in periprosthetic healing in the early post-operative period. The methodology was validated by a canine experimental model. In this first part, the effects of each individual uncertain biochemical factor on the bone-implant healing are examined, including the coefficient of osteoid synthesis, the coefficients of haptotactic and chemotactic migration of osteoblastic population and the radius of the drill hole. A multi-phase reactive model solved by an explicit finite difference scheme is combined with the polynomial chaos expansion to solve the stochastic system. In the second part, combined biochemical factors are considered to study a real configuration of clinical acts

Prediction of the intramembranous tissue formation during perisprosthetic healing with uncertainties. Part 2. Global clinical healing due to combination of random sources

This work proposes to examine the variability of the bone tissue healing process in the early period after the implantation surgery. The first part took into account the effect of variability of individual biochemical factors on the solid phase fraction, which is an indicator of the quality of the primary fixation and condition of its long-term behaviour. The next issue, addressed in this second part, is the effect of cumulative sources of uncertainties on the same problem of a canine implant. This paper is concerned with the ability to increase the number of random parameters to assess the coupled influence of those variabilities on the tissue healing. To avoid an excessive increase in the complexity of the numerical modelling and further, to maintain efficiency in computational cost, a collocation-based polynomial chaos expansion approach is implemented. A progressive set of simulations with an increasing number of sources of uncertainty is performed. This information is helpful for future implant design and decision process for the implantation surgical act

Evaluation of a multivariate syndromic surveillance system for West Nile virus.

Background: Various methods are currently used for the early detection of West Nile virus (WNV) but their output is either not quantitative or does not take into account all available information. Our study aimed to test a multivariate syndromic surveillance system in order to improve early detection of WNV. Method: Weekly time series data on nervous syndromes in horses and mortality in both horses and wild birds were used. Baselines were fitted to the three time series and used to simulate 100 years of surveillance data. WNV outbreaks were simulated and inserted into the baselines based on historical data and expert opinion. Univariate and multivariate syndromic surveillance systems were tested in order to gauge how well they detected the outbreaks; detection was based on an empirical Bayesian approach. The systems’ performances were compared using measures of sensitivity, specificity, and area-under-ROC-curve (AUC). Result: When data sources were considered separately (i.e. univariate systems), the best detection performance was obtained using the dataset of nervous symptoms in horses compared to those of bird and horse mortality (AUCs respectively equal to 0.80, 0.75, and 0.50). A multivariate outbreak detection system that used nervous symptoms in horses and bird mortality generated the best performance (AUC = 0.87). Conclusion: The proposed approach is suitable for performing multivariate syndromic surveillance of WNV outbreaks. This is particularly relevant given that a multivariate surveillance system performed better than a univariate approach. Such a surveillance system could be especially useful in serving as an alert for the possibility of human viral infections. This approach can be also used for other diseases for which multiple sources of evidence are available