Around traces and quasitraces

This paper presents a survey of results on traces and quasitraces on C$^*$-algebras, and it provides some new results on traces on ultrapowers and on the existence of faithful traces. As for the former, we exhibit a sequence of traceless simple, separable, unital, nuclear C$^*$-algebras whose ultrapower does admit a quasitrace (and likely also a trace). We characterize in different ways C$^*$-algebras that admit a faithful trace, respectively, where each quotient of the C$^*$-algebra admits a faithful trace.Comment: 21 page

La gestion forestière communautaire dans le sud-ouest de Madagascar:une réussite sans profit économique ?

Des villages du Sud-Ouest malgache connaissent un certain succès dans la gestion forestière communautaire par opposition à des villages où les conflits prévalent. En dépit de l’absence d’avantages économiques directs pour les ménages, la plupart d’entre eux acceptent les contrats de gestion locale. Les villageois avancent que l’amélioration des relations avec les autorités forestières est l’un des avantages importants de la gestion selon la Loi Gelose. Toutefois, nous n’avons pas pu identifier de différences significatives dans les propositions de contrats de gestion plus appropriés. La principale conclusion est que le modèle de transfert de la gestion forestière vers les communautés locales malgaches, du moins dans cette partie du pays, n’a pas significativement modifié l’attitude des villageois vis-à-vis de la conservation de la forêt.Is the local common management of forest in South-West of Madagascar a success despite economic benefits ?We focus on what characterize households in villagers, more successful in protecting the forest compared to those villagers, where conflicts prevail. Selecting the successful compared with the unsuccessful villages was based on criteria from the previous chapters on deforestation rates and forest tenure (Razafy Fara and Ranaivoson). Most households welcome the option of local management contracts, despite the lack of pure direct economic benefits. Improved relations to the forest authorities are highly appreciated by the villagers and one of the defined advantages of the Gelose contacts. However, we could not identify any significant differences in proposals to better local management contracts in the future. All households, regardless of being located in successful or unsuccessful villages, request access to non-managed forest areas, where they can, if needed, encroach on the forest resources without restrictions. The transfer of management model in Madagascar, at least in this part of the country, did not change the attitude of villagers towards conservation of the forest

Temporal aggregation in first order cointegrated vector autoregressive

We study aggregation - or sample frequencies - of time series, e.g. aggregation from weekly to monthly or quarterly time series. Aggregation usually gives shorter time series but spurious phenomena, in e.g. daily observations, can on the other hand be avoided. An important issue is the effect of aggregation on the adjustment coefficient in cointegrated systems. We study only first order vector autoregressive processes for n dimensional time series Xt, and we illustrate the theory by a two dimensional and a four dimensional model for prices of various grades of gasoline