Search results for "Niger"

Form factor approach to dynamical correlation functions in critical models

2012

We develop a form factor approach to the study of dynamical correlation functions of quantum integrable models in the critical regime. As an example, we consider the quantum non-linear Schr\"odinger model. We derive long-distance/long-time asymptotic behavior of various two-point functions of this model. We also compute edge exponents and amplitudes characterizing the power-law behavior of dynamical response functions on the particle/hole excitation thresholds. These last results confirm predictions based on the non-linear Luttinger liquid method. Our results rely on a first principles derivation, based on the microscopic analysis of the model, without invoking, at any stage, some correspon…

Three New Triterpene Saponins from Two Species of Carpolobia

2002

Three new acetylated triterpene saponins 1-3 were isolated from the roots of Carpolobia alba and C. lutea. Their structures were established mainly by 2D NMR techniques as 3-O-beta-D-glucopyranosylpresenegenin-28-O-beta-D-galactopyranosyl-(1-->4)-[beta-D-xylopyranosyl-(1-->3)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-(3,4-di-O-acetyl)-beta-D-fucopyranosyl ester, 3-O-beta-D-glucopyranosylpresenegenin-28-O-beta-D-galactopyranosyl-(1-->4)-[alpha-L-arabinopyranosyl-(1-->3)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-(3,4-di-O-acetyl)-beta-D-fucopyranosyl ester, and 3-O-beta-D-glucopyranosylpresenegenin-28-O-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl…

Broadening Access to Primary Education: Contract Teacher Programs and Their Impact on Education Outcomes in Africa – An Econometric Evaluation for Ni…

2006

06004; For Sub-Saharan Africa as a whole, but particularly for countries in the Sahel zone, full primary enrolment and completion at acceptable quality as codified in the Millennium Development Goals and the Education for All objectives still remains a major challenge. In order to enhance education supply, many of these countries have launched large scale teacher recruitment programs in recent years, whereby the teachers are no longer engaged in civil servant positions, but on the basis of fixed-term contracts typically implying considerably lower salaries and a sharply reduced duration of professional training. While this policy has led to a boost of primary enrolment, stakeholders in the …

Multiple chromosome polymorphism in the gobiid fish Gobius niger jozo L. 1758 (Pisces, Gobiidae).

1989

By analysing chromosome preparation from 42 Gobius niger jozo specimens from the Gulf of Palermo (Sicily), four different karyotypes were observed: A (2n=52; NF=60), B (2n=51; NF=60), C (2n=50; NF=60) and D (2n=49; NF=60). A chromosome polymorphism due to Robertsonian fusion is present in this species.

The Air-Ténéré National Natural Reserve (RNNAT) Observatory: Territorial Intelligence for Sustainable Development

2007

International audience; The Aïr-Ténéré National Natural Reserve is a protected area in which conservation and development principles tempt to be combined (co-management). To follow-up environmental changes which determine people's life, and to support decisions to manage the Reserve, the first steps of a territorial observatory are introduced. Beyond the technical build up of the Geographical Information System (GIS), the prototype proposed here is a concrete expression of a part of a territorial intelligent tool. It embraces all territorial dimensions from spatial to actors ones, and try in the context of the reserve, to revisit the definition of local governance. This work is based on a m…

Evaluation of wood-polyethylene composites biodegradability caused by filamentous fungi

2017

Abstract This study describes the impact of filamentous fungi on wood-polymer composites (WPCs) containing various types of fillers (coniferous, deciduous, cellulose) in the amount of 30 wt.% to 50 wt.%. The selection of fungal strain of filamentous fungi was performed prior to the study on the impact of the wood type on the progress of WPCs biodegradability. The changes associated with various water absorption of the examined WPCs, were observed using scanning electron microscopy (SEM). The impact of fungal mycelium, which had affected the changes in WPCs material, was examined using thermogravimetric analysis (TG). The results showed, that the growth of mycelium on WPCs, influenced mainly…

Wole Soyinka: Due Poesie

2008

Durante l'undicesima edizione del Festivaletteratura di Mantova, nel settembre 2007, Wole Soyinka, insieme alla studiosa e traduttrice Alessandra Di Maio, ha ripercorso la sua carriera poetica, spiegandone svolte e sviluppi. In questa sede si riportano due delle sue poesie più note in traduzione -- "Conversazione telefonica" e "I figli di questa terra" -- che coprono idealmente l'arco della sua produzione poetica, dalla gioventù all'eta matura.

Nouveaux enjeux pour l'école moyenne en Afrique

2005

05113; On constate aujourd'hui une augmentation massive de la scolarité des 12-16 ans dans les pays africains en développement. Ce phénomène est lié au développement voulu et obtenu des scolarités primaires.Pour diverses raisons, l'école moyenneconstitue un cycle terminal pour la grande majorité des enfants qui la fréquentent. Son organisation actuelle, telle qu'on peut l'observer dans différents pays, est cependant très proche du collège secondaire français et donc inapte à fournir le cadre adéquat pour un cycle terminal générateur de progrès économiques et sociaux.Bâti sur cette problématique de l'articulation entre les flux d'élèves, les contenus pédagogiques et les modalités d'organisat…

Kuka on Judith Schalansky?

2020

Impact of very low crop residues cover on wind erosion in the Sahel

2011

International audience; In the Sahel, with average annual precipitation in the order of 500 mm yr− 1, wind erosion occurs mainly on cultivated millet fields whose surfaces are only partially covered by crop residues. The impact of these residues on wind erosion was not clearly established. The objective of this study is thus to quantify the actual amount of crop residues in traditional Sahelian fields and to determine their impacts on wind erosion by reference to a bare surface throughout the seasonal cycle over several years. At the beginning of the year during dry season, Sahelian farmers use to "clean" their fields, i.e. cut and lay flat on the soil surface any millet stalks still standi…