New, Highly Accurate Propagator for the Linear and Nonlinear Schr\"odinger Equation

A propagation method for the time dependent Schr\"odinger equation was studied leading to a general scheme of solving ode type equations. Standard space discretization of time-dependent pde's usually results in system of ode's of the form u_t -Gu = s where G is a operator (matrix) and u is a time-dependent solution vector. Highly accurate methods, based on polynomial approximation of a modified exponential evolution operator, had been developed already for this type of problems where G is a linear, time independent matrix and s is a constant vector. In this paper we will describe a new algorithm for the more general case where s is a time-dependent r.h.s vector. An iterative version of the new algorithm can be applied to the general case where G depends on t or u. Numerical results for Schr\"odinger equation with time-dependent potential and to non-linear Schr\"odinger equation will be presented.Comment: 14 page

Trypanosoma brucei gambiense in domestic livestock of Kogo and Mbini foci (Equatorial Guinea).

OBJECTIVE: To evaluate Trypanosoma brucei gambiense infection in peri-domestic livestock from Kogo and Mbini foci (Equatorial Guinea) in order to investigate its possible implication in the sleeping sickness transmission cycle in these hypoendemic foci. METHODS: Samples from 698 domestic animals (goats, sheep and pigs) from trypanosomiasis-endemic localities of Kogo and Mbini foci were tested for animal trypanosomes and T. b. gambiense (group I) by species-specific polymerase chain reaction. RESULTS: Trypanosoma brucei s.l., the predominant trypanosome species, was detected in 182 (52.6%) samples from Mbini and in 127 (36.1%) samples from Kogo. T. b. gambiense was only identified in seven (2%) of the Mbini samples and one co-infection (with T. vivax) was observed. CONCLUSION: The occurrence of T. b. gambiense in peri-domestic livestock in Mbini and its absence in Kogo could explain the epidemiological differences between the two foci and could have significant implications for sleeping sickness control in Equatorial Guinea

Biodiversity offsets: opportunities and challenges for managing cumulative impacts of large-scale land-based investments on Africa's forest landscapes and their biodiversity

In the Western Congo Basin, the Tri-National Dja Odzala Minkebe (TRIDOM) Landscape covers 178000 km² in south-east Cameroon, north-east Gabon, and north-west Republic of Congo. Almost 97% is covered by tropical rainforest and is globally important for the conservation of large mammals (elephants, gorillas, chimpanzees). TRIDOM is also an emerging iron ore province with 9 iron ore deposits currently being explored. Mining and associated infrastructure will, under a business as usual scenario, lead to the widespread fragmentation of this forest landscape. Developing these projects with no-net loss or net gain biodiversity objectives as a condition for access to finance offers opportunities but a landscape-level approach is needed to take into account, and mitigate, indirect and cumulative impacts. There are numerous technical challenges and policy implications to this as the development and implementation of a landscape-scale vision for conservation and development in the TRIDOM requires coordinated efforts by various sectors of government and mining companies, and legal and financial tools to secure long-term land-use rights across the various interacting sectors. In this context, there are lessons to be learned from the TRIDOM for other biodiversity-rich landscapes faced with large-scale land-based investments in mining, oil & gas or agro-industrial sectors. (Résumé d'auteur

Errors in quantum optimal control and strategy for the search of easily implementable control pulses

We introduce a new approach to assess the error of control problems we aim to optimize. The method offers a strategy to define new control pulses that are not necessarily optimal but still able to yield an error not larger than some fixed a priori threshold, and therefore provide control pulses that might be more amenable for an experimental implementation. The formalism is applied to an exactly solvable model and to the Landau-Zener model, whose optimal control problem is solvable only numerically. The presented method is of importance for applications where a high degree of controllability of the dynamics of quantum systems is required.Comment: 13 pages, 3 figure

Elaboration et évaluation d'algorithmes de dépistage des MST chez la femme enceinte à Libreville, Gabon

La lutte contre les MST constitue une priorité de santé publique des pays en développement de par leurs complications propres, en particulier chez la femme, et de par leur rôle facilitant la transmission du VIH. Une des stratégies de lutte contre les MST est le diagnostic et le traitement précoces de ces infections. Les MST, en particulier les infections à gonocoques et à #Chlamydiae trachomatis$sont d'un diagnostic difficile chez la femme en l'absence d'examens complémentaires, ceux-ci faisant souvent défaut au niveau des structures de soins de santé primaire. Dans ce contexte, l'approche syndromique, basée sur la prise en compte de signes et symptômes, peut permettre de standardiser et d'améliorer la prise en charge des patientes. Une étude de prévalence et de facteurs de risque des MST, effectuées chez 192 femmes enceintes consultant en PMI à Libreville (Gabon), en septembre 1993, a confirmé la prévalence des MST dans cette population (13,5$). L'évaluation de différentes stratégies diagnostiques et d'algorithmes montre que, quel que soit le niveau d'examen (données d'interrogatoire, examen clinique simple, examen au spéculum), l'utilisation de scores intégrant des facteurs de risque, des symptômes et des signes cliniques est plus performante que les algorithmes hiérarchiques. Ces scores présentent des sensibilités et des spécificités élevées et sont d'une mise en oeuvre facile. Leur application pourrait donc permettre le dépistage efficace des MST et éviter, ainsi, une grande partie des complications maternelles et infantiles. (Résumé d'auteur

Universities and community-based research in developing countries: community voice and educational provision in rural Tanzania

The main focus of recent research on the community engagement role of universities has been in developed countries, generally in towns and cities and usually conducted from the perspectives of universities rather than the communities with which they engage. The purpose of this paper is to investigate the community engagement role of universities in the rural areas of developing countries, and its potential for strengthening the voice of rural communities. The particular focus is on the provision of primary and secondary education. The paper is based on the assumption that in order for community members to have both the capacity and the confidence to engage in political discourse for improving educational capacity and quality, they need the opportunity to become involved and well-versed in the options available, beyond their own experience. Particular attention is given in the paper to community-based research (CBR). CBR is explored from the perspectives of community members and local leaders in the government-community partnerships which have responsibility for the provision of primary and secondary education in rural Tanzania. The historical and policy background of the partnerships, together with findings from two case studies, provide the context for the paper

Efficient Algorithms for Optimal Control of Quantum Dynamics: The "Krotov'' Method unencumbered

Efficient algorithms for the discovery of optimal control designs for coherent control of quantum processes are of fundamental importance. One important class of algorithms are sequential update algorithms generally attributed to Krotov. Although widely and often successfully used, the associated theory is often involved and leaves many crucial questions unanswered, from the monotonicity and convergence of the algorithm to discretization effects, leading to the introduction of ad-hoc penalty terms and suboptimal update schemes detrimental to the performance of the algorithm. We present a general framework for sequential update algorithms including specific prescriptions for efficient update rules with inexpensive dynamic search length control, taking into account discretization effects and eliminating the need for ad-hoc penalty terms. The latter, while necessary to regularize the problem in the limit of infinite time resolution, i.e., the continuum limit, are shown to be undesirable and unnecessary in the practically relevant case of finite time resolution. Numerical examples show that the ideas underlying many of these results extend even beyond what can be rigorously proved.Comment: 19 pages, many figure

A long-lasting measles epidemic in Maroua, Cameroon 2008-2009: mass vaccination as response to the epidemic.

A measles outbreak occurred in Maroua, Cameroon, from January 2008 to April 2009. In accordance with recent World Health Organization guidelines, an outbreak-response immunization (ORI) was conducted in January 2009. The aim of this study was to investigate the causes of the epidemic in order to guide vaccination strategies