Pour mieux comprendre les déplacements interrégionaux de voyageurs : un modèle multimodal de demande (Première partie : les objectifs retenus et la conception générale du modèle)

The multimodal transport demand model, being developed in France since 1973, aims above all at better taking into account the influence of the level of service of different transport modes on the choice of mode and on mobility. While preceding models of the type "journey cost-journey time-passenger income" dealt essentially with business trips by air or railway in first class, this model has the following extensions:- taking into account all the interregional modes of transport: trains, aircraft, passengers cars,- taking into account private journeys,- simulation of individual travel behaviour on the basis of sample trips.The first applications are encouraging. However, if the problems of a methodological order have been solved in an acceptable way, the estimation of the numerical values of parameters with a sufficient precision will need the realization of important sample surveys.Le modèle multimodal de demande, développé en France à partir de 1973, vise d'abord à mieux prendre en compte l'influence du niveau de service des différents modes de transport sur le choix du mode et la mobilité. Alors que les modèles précédents du type "prix-temps-revenu" portaient principalement sur les voyages professionnels effectués en avion ou par le train en 1ère classe, ce modèle correspond aux extensions suivantes :- prise en compte de l'ensemble des modes de transport interrégionaux : train, avion, voiture,- prise en compte des voyages personnels,- fonctionnement par simulation des comportements individuels, à partir d'échantillons de voyages.Les premières applications effectuées sont encourageantes. Toutefois, si les problèmes d'ordre méthodologique sont résolus de manière acceptable, l'estimation de la valeur numérique des paramètres avec une précision suffisante nécessitera la réalisation d'importantes enquêtes par sondage sur les voyages

Pour mieux comprendre les déplacements interrégionaux de voyageurs : un modèle multimodal de demande. Deuxième partie : description du modèle et premiers résultats

The multimodal transport demand model, being developed in France since 1973, aims above all at better taking into account the influence of the level of service of different transport modes on the choice of mode and on mobility. While preceding models of the type "journey cost-journey time-passenger income" dealt essentially with business trips by air or railway in first class, this model has the following extensions:- taking into account all the interregional modes of transport: trains, aircraft, passengers cars,- taking into account private journeys,- simulation of individual travel behaviour on the basis of sample trips.The aim and general model design ware given in a preceding article. Here the reader will find further details of the operation of the model and the first results obtained.Le modèle multimodal de demande développé en France à partir de 1973, vise d'abord à mieux prendre en compte l'influence du niveau de service des différents modes de transport sur le choix du mode et la mobilité. Alors que les modèles précédents du type "prix-temps-revenu" portaient principalement sur les voyages professionnels effectués en avion ou par le train en 1ère classe, ce modèle correspond aux extensions suivantes :- prise en compte de l'ensemble des modes de transport interrégionaux : train, avion, voiture,- prise en compte des voyages personnels,- fonctionnement par simulation des comportements individuels, à partir d'échantillons de voyages. Les objectifs retenus et la conception générale du modèle ont été décrits dans un précédent article. Le lecteur trouvera ici des compléments sur le fonctionnement du modèle et les premiers résultats obtenus

Evaluation of serological tests for H5N1 avian influenza on field samples from domestic poultry populations in Vietnam: consequences for surveillance

In Vietnam, serological post H5N1 vaccination surveillance using the HI test is applied to assess the efficiency of the vaccination in addition to virological monitoring. In this paper we report on the evaluations of the performances of the haemagglutination inhibition (HI) test and of a H5-ELISA, using chicken and duck field samples. The evaluations were conducted by comparison with a pseudotyped-based virus neutralization test (H5pp VNT) performed in a reference laboratory and considered as a “gold standard” and also by using methods developed for imperfect reference test. Their global accuracy and best cut-offs were also estimated. Results from the HI test for several haemagglutinin subtypes and from a commercial type A influenza competition ELISA were also compared. The results showed that performance of the HI test was very good in comparison with the H5pp VNT. Data also clearly supported the cut-off of ≥4log2 used for the HI test for chickens but, a 3log2 positivity cut-off would be more appropriate for ducks. When compared with the VNT, the H5-ELISA showed poor specificity when using the positivity cut-off specified by the manufacturer but could be used as a screening test if confirmed by the HI test or the H5ppVNT which presents some interests for large scale testing (no need for biosafety level 3 conditions and high performance). A general and highly sensitive pre-screening can also be achieved using the detection of NP-specific antibodies with a competition ELISA. This appears of little interest in a context of high subtypes diversity where only a subtype is targeted for surveillance and control

New T-cell receptor gamma haplotypes in wild mice and evidence for limited Tcrg-V gene polymorphism

Tcrg gene polymorphism was investigated by Southern blot analysis on a panel of laboratory and wild mouse strains using a set of probes which identify all known Tcrg-V and -C genes. Only three haplotypes are found in laboratory mice: gA, gB, and gC which are represented by BALB/c, AKR, and DBA/2 prototypes respectively. gA and gC haplotypes are the most frequent among laboratory mice whereas gB is poorly represented. Seven new haplotypes are described among 23 wild mice corresponding to four Mus musculus subspecies (Mus mus domesticus, castaneus, musculus, and molossinus). However, only a few new alleles of individual genes are observed. Tcrg-V genes located at the 5' end of the Tcrg locus (V7 and V4) appear to be nonpolymorphic whereas two Tcrg-V3, -V5, -V6, -C4 and three Tcrg-V1, -V2, -C1, -C2, and -C3 specific restriction fragment length polymorphisms are detected. These results indicate a relatively high degree of conservation of Tcrg genes as compared to other members of the immunoglogulin (Ig) gene family and might be related to the specifity and function of gamma delta T cells. Several of the new haplotypes described here result from point mutations in noncoding Tcrg-V or -C gene-flanking regions. Recombinations may have also participated in the evolution of the Tcrg locus. Finally, these new Tcrg haplotypes are unequally distributed among the four M. m. subspecies and support the idea that the gA and gC haplotypes found in laboratory mice are inherited from M. m. domesticus whereas gB might originate from asian subspecies (castaneus, musculus or molossinus)

Overcoming immunogenicity issues of HIV p24 antigen by the use of innovative nanostructured lipid carriers as delivery systems: evidences in mice and non-human primates

Optimizing HIV p24 vaccine responses To date, HIV vaccines have resulted in poor or absent protection. A team led by Fabrice P. Navarro at the CEA LETI use the conserved HIV capsid protein p24 vectorized into cationic nanostructured lipid carriers (NLC-p24) along with NLC-delivered CpG. Owing to their small size, NLCs gain access to lymph nodes and deliver antigen directly to antigen presenting cells. Anti-p24 responses have been associated with effective HIV control, making them an attractive vaccine antigen, but they are poorly immunogenic. NLC-p24 shows a good safety profile while at the same time being able to elicit robust humoral and cellular immune responses in both mice and Cynomolgus macaques. NLC-mediated delivery of both p24 and CpG results in more effective immune stimulation than delivery of free antigen and adjuvant. These findings demonstrate the possibility of priming effective responses to a potent but otherwise poorly immunogenic HIV antigen