Ensemble Prediction of a Halo Coronal Mass Ejection Using Heliospheric Imagers.

The Solar TErrestrial RElations Observatory (STEREO) and its heliospheric imagers (HIs) have provided us the possibility to enhance our understanding of the interplanetary propagation of coronal mass ejections (CMEs). HI-based methods are able to forecast arrival times and speeds at any target and use the advantage of tracing a CME's path of propagation up to 1 AU and beyond. In our study, we use the ELEvoHI model for CME arrival prediction together with an ensemble approach to derive uncertainties in the modeled arrival time and impact speed. The CME from 3 November 2010 is analyzed by performing 339 model runs that are compared to in situ measurements from lined-up spacecraft MErcury Surface, Space ENvironment, GEochemistry, and Ranging and STEREO-B. Remote data from STEREO-B showed the CME as halo event, which is comparable to an HI observer situated at L1 and observing an Earth-directed CME. A promising and easy approach is found by using the frequency distributions of four ELEvoHI output parameters, drag parameter, background solar wind speed, initial distance, and speed. In this case study, the most frequent values of these outputs lead to the predictions with the smallest errors. Restricting the ensemble to those runs, we are able to reduce the mean absolute arrival time error from 3.5 ± 2.6 to 1.6 ± 1.1 hr at 1 AU. Our study suggests that L1 may provide a sufficient vantage point for an Earth-directed CME, when observed by HI, and that ensemble modeling could be a feasible approach to use ELEvoHI operationally.

[Leptospirosis and environment. Study of 2 major foci in New Caledonia]. / Leptospiroses et environment. Etude des deux foyers majeurs de Nouvelle-Calédonie.

A study of human and animal leptospirosis was carried out in new Caledonia's two most important focuses. This survey showed an annual incidence in the human population of 8.8 p. thousand in the Nera basin and 0.88 p. thousand in the Coulée basin. Male adults with agricultural and livestock occupations are the most exposed, especially from March to May, the end of the hot season. Frequent contacts with fresh water and animals, and the failure to use of gloves and boots, significantly increase the risk of contamination. Two factors of severity are important: serotype and age. Leptospira icterohaemorrhagiae is responsible for serious and fatal clinical forms and patients over 50 years of age have a maximum vital risk. In order to reduce the incidence and the severity of this disease, it appears desirable to vaccinate the farmers and the cattle breeders against L. icterohaemorrhagiae and to institute mass media information campaigns to warn against the risks of contamination.

[Epidemiological study of leptospirosis in New Caledonia]. / Etude épidémiologique de la leptospirose en Nouvelle-Calédonie.

This epidemiological survey includes the study of human and animal leptospirosis in New Caledonia from clinical cases as well as a systematic serological study about exposed human and animal populations. The results show that this disease is endemic on the whole territory with a few important focuses in agricultural area, especially on the Western coast. Leptospira icterohemorrhagiae is the main serotype and is responsible for serious human leptospirosis. The male farmers constitute the most exposed population, especially from March to May, end of the host season. In order to reduce the importance of this disease, it is desirable that the farmers are vaccinated and mass media campaigns are necessary to improve the prevention.