The deposit of Oklo and its natural nuclear reactors

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.; Weber, F.; Pfiffelmann, J.P.; Chauvet, R.; Michel, B.; Reboul, J.C.

1980-01-01

In the uranium deposit of Oklo (Republic of Gabon), seven zones have been discovered since 1972, in which natural fission reactions took place. Since 1974, a thorough geological study of these zones has been undertaken. It includes field studies, observations of drilled samples and laboratory studies. These studies permit the authors to define the geological environment of the reactors and to point out the influence of nuclear reactions on the surrounding formations. All this work was completed by a geological and metallogenic study of the deposit of Oklo and of the uraniferous basin of Franceville. The deposit of Oklo is situated in a detrital, sandstone-like and pelitic series belonging to the Francevillian. The Francevillian and the mineralization are dated as Middle Precambrian (1800-2000 M.A.). The ore of Oklo is the result of two concentration stages. In the first, uranium seems to have been fixed by hydrocarbons that were concentrated in oil traps. After a tectonic event, circulations of oxidizing solutions generated reconcentrations that are associated with hematite and have contents of UO 2 between 1 and 20%. The fission reactions developed in the high-graded ores which had formed during the last phase of UO 2 concentration. A thorough tectonic analysis of the ore deposit shows that high-graded ores and fission reactors are controlled by fractures. The working of nuclear reactors results in a local increase of temperature which gave a rise to circulation of warm water. The results of this hydrothermal circulation and of the neutron bombardment are seen in a succession of facies surrounding the reactors. At the centre of the reactor all sedimentary structures have been destroyed; within the reaction zone the following clays mineral zones are founded: (1) 1 Md illite and ferrous chlorite corresponding to the common Francevillian sediment; (2) 2 Md illite, (3) magnesium chlorite and (4) 1 Md illite and chlorite-vermiculite in the very rich uraninite ore

Eh-pH diagrams for elements from Z = 40 to Z = 52: application to the Oklo natural reactor, Gabon

Energy Technology Data Exchange (ETDEWEB)

Brookins, D G [New Mexico Univ., Albuquerque (USA). Dept. of Geology

1978-11-01

Eh-pH diagrams for elements from Z = 40 (Zr) to Z = 52 (Te) have been constructed in order to comment on migration/retention of these elements at Oklo. Although data for fissiogenic amounts of some of these elements are lacking, where such data are available to agreement between predicted migration/retention based on the Eh-pH diagrams and actual measurement is excellent. Based on Eh-pH diagrams, migration (to what degree is uncertain) of Mo and Cd is predicted whereas retention of Y, Zr, Tc, Ru, Rh, Pd, Ag and Te is also predicted. An earlier report of Frejacques et al. of Tc migration is in disagreement with Eh-pH prediction, and recent (unpublished) data argue for Tc retention. In view of the agreement between prediction and observation, the possible migration of Sb and retention of In and Sn is proposed. These data again demonstrate the usefulness of Eh-pH diagrams for the Oklo fossil nuclear reactor but, more important, allow constraints to be placed on repositories for nuclear waste now under consideration.

Oklo 2 Billion Years Before Fermi

International Nuclear Information System (INIS)

Barre, B.

2005-02-01

The author aims to present the little-known story of the Oklo natural reactors. He recalls the historical aspects of the Oklo reactors discovery by the CEA in 1972, he explains the scientific phenomenon and the interest, notably as a ''natural analogue'' for the geological disposal of high level radioactive wastes. (A.L.B.)

Geochemical properties and nuclear chemical characteristics of Oklo natural fission reactors

Energy Technology Data Exchange (ETDEWEB)

Hidaka, Hiroshi [Hiroshima Univ., Higashi-Hiroshima (Japan). Faculty of Science

1997-07-01

There are six uranium deposits in the Gabonese Republic in the cnetral Africa. `Fission reactor zone`, the fission chain reactions generated about 200 billion years ago, was existed in a part of them. CEA begun geochemical researches of Oklo deposits etc. in 1991. The geochemical and nuclear chemical properties of Oklo were reviewed from the results of researches. Oklo deposits is consisted of main five sedimentary faces such as sandstone (FA), Black Shale formation (FB), mudstone (FC), tuff (FD) and volcaniclastic sandstone (FE) from the bottom on the base rock of granite in the Precambrian era. Uranium is enriched in the upper part of FA layer and the under part of FB layer. {sup 235}U/{sup 238}U, U content, fission proportion, duration time, neutron fluence, temperature, restitution factor of {sup 235}U and epithermal index ({gamma}) were investigated and compared. The geochemical properties of Oklo are as followed: large enrich of uranium, the abundance ratio of {sup 235}U as same as that of enriched uranium, interaction of natural water and small rear earth elements. These factors made casually Oklo fission reactor. (S.Y.)

Two billion year old natural analogs for nuclear waste disposal: the natural nuclear fission reactors in Gabon (Africa)

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.

2002-01-01

Two billion years ago, the increase of oxygen in atmosphere and the high 235 U/ 238 U uranium ratio (> 3%) made possible the occurrence of natural nuclear reactors on Earth. These reactors are considered to be a good natural analogue for nuclear waste disposal. Their preservation during such a long period of time is mainly due to the geological stability of the site, the occurrence of clays surrounding the reactors and acting as an impermeable shield, and the occurrence of organic matter that maintained the environment in reducing conditions, favourable for the stability of uraninite. Hydrogeochemical studies and modelling have shown the complexity of the geochemical system at Oklo and Bangombe (Gabon) and the lack of precise data about uranium and fission products retention and migration mechanisms in geological environments. (author)

The Oklo phenomenon as an analogue of radioactive waste disposal. A review

International Nuclear Information System (INIS)

Berzero, A.; D'Alessandro, M.

1990-01-01

This work demonstrates the utility of the Oklo uranium ore deposit and natural fission reactors as a long time scale analogue for man-made radioactive waste repositories. Oklo has opened a new horizon representing an unrivalled opportunity to apply isotopic geochemistry to the study of migrations of fission products after an extremely long cooling and storage time and to define the processes involved in the transport of these elements through geological materials. This is the topic of the first section of this report. In the second section the information available on retention or migration at Oklo of the most interesting fission products is presented trying to illustrate how relevant the Oklo experience is in formulating predictions on the destiny of high activity waste disposed of in stable geological formations

Problems posed by the development of the Oklo phenomenon: tentative global interpretation

International Nuclear Information System (INIS)

Naudet, R.

This paper discusses the basic problems posed by the development of the Oklo phenomenon: the conditions in which the reactions are triggered and propagated and how they have been controlled. The reactions were maintained by the destruction of neutron poisons in the ore and were controlled by temperature. Oklo is made up of a large number of contiguous reactors. Geological problems of the origin of the clays, desilification, and uranium concentration are discussed. Oklo is shown to be a very complex phenomenon which developed in space and time. Besides the thermal, neutron, and geochemical coupling, there is also a tectonic coupling

The Oklo natural nuclear reactors: neutron parameters, age and duration of the reactions, uranium and fission products migrations

International Nuclear Information System (INIS)

Ruffenach, J.-C.

1979-09-01

Mass spectrometry and isotopic dilution technique are used in order to carry out, on various samples from the fossil nuclear reactors at Oklo, Gabon, isotopic and chemical analyses of some particular elements involved in the nuclear reactions: uranium, lead, bismuth, thorium, rare gases (krypton, xenon), rare earths (neodymium, samarium, europium, gadolinium, dysprosium), ruthenium and palladium. Interpretations of these analyses lead to the determination of many neutron parameters such as the neutron fluence received by the samples, the spectrum index, the conversion coefficient, and also the percentages of fissions due to uranium-238 and plutonium-239 and the total number of fissions relative to uranium. All these results make it possible to determine the age of the nuclear reactions by measuring the amounts of fission rare earths formed, i.e. 1.97 billion years. This study brings some informations to the general problem of radioactive wastes storage in deep geological formations, the storage of uranium, plutonium and many fission products having been carried out naturally, and for about two billion years [fr

Reconstitution of fluid paleo-circulations and element migrations in the environments of Oklo's natural nuclear reactors (Gabon) and of Tournemire's argillites (France)

International Nuclear Information System (INIS)

Mathieu, Regis

1999-01-01

To better characterize the mobilization and migration process in rocks, a petrological and geochemical study of fluid paleo-circulation through fractures has been made in two different sites: (1) The environment of natural nuclear reactors from Proterozoic Oklo uranium ores (Gabon). The Archean basement typical of TTG series and the sandstones-pelites series of the Franceville basin are affected by a fracturing mainly filled by quartz-daphnite-calcite-sulfides and barren ou mineralized bitumens. Three paragenetic stages has been correlated to three regional structural phases. During the first extensional phase, a low saline (1.7-6.5 wt% NaCl), heated in the basement (190-210 deg. C) and impoverished in 18 O meteoric recharge is injected into the basin, along major N-S faults. It was responsible of silicification. The circulation of diagenetic brines is able to leach U, Pb, Zr, REEs and P resulting from accessory minerals alteration, at the basin-scale between 2104 Ma and 1719 Ma (Pb/Pb isochrone obtained on galena incorporated in zircons). These brines are responsible of anomalous Th/La ratios (1.8) of FA silicified sandstones higher than those (0.25) of most of Archean and Proterozoic metasediments. They are highly chlorine, calco-sodic ([Cl] > 6 m, from 28 wt% NaCl to 30 wt% CaCl 2 ), equilibrated with carbonate and evaporitic layers of FA sandstones, with low temperatures (130 deg. C) and rich in Ca, Li and Br. They are expulsed laterally due to the compaction of FA sandstones, and upwards along sub-vertical fractures. During the second extensional phase, the mineralization stage, mainly controlled by N-S faults corresponds to a mixing (155-220 deg. C) between the brines, the meteoric recharge and hydrocarbons C 9 and C 10 -rich fluids derived from organic matter maturation in the FB pelites. The interaction of the three fluids is responsible of the mineralization in sandstones and in calcites displaying an organic carbon origin (δ 13 C=-10 to -15 0/00 vs. PDB

Geochemical behaviour study of radionuclides and their radiogenic daughters in the vicinity of Oklo 10 and 13 natural nuclear reactors (Gabon) - Application to high-level radioactive waste disposal

International Nuclear Information System (INIS)

Menet-Dressayre, Catherine

1992-01-01

Since 1981, the discovery of new and almost unaltered natural nuclear reactors in the uranium mine of Oklo (Gabon) renewed the interest of scientific community. Indeed, due to their specific features, these reactors could be extensively investigated as natural analogues to better understand the geochemical processes which may occur in a high level nuclear waste repository. The aim of this PhD thesis is to determine the present distribution of a few radionuclides or their radiogenic daughters initially formed within the reaction zones and to infer their geochemical behaviour, subsequently to the stopping of nuclear reactions. Our study was focused on reactors 10 and 13 and their immediate sandstone surroundings in order to decipher the fate of U, Y and light rare earth elements which are assumed to be chemical analogues of actinides and fission products. Mineralogical observations, chemical and isotopic analyses on bulk rocks, led us to conclude that a part of radionuclides, as well as their daughters, remained confined within the reactions zones, in association with secondary mineral phases, whereas another part migrated towards tbe reactor rims. The radionuclides were concentrated at the reactor border or migrated within the first few metres of the surrounding sandstone, according to the intensity of nuclear reactors and the presence of the so-called 'facies argile de pile' which constitutes an intermediate facies between that of reactor cores and that of the surrounding sandstone. In the latter, long range elemental transfers occurred via fissures. Some of them, contemporaneous to the nuclear reactions drained radionuclides-rich fluids at temperatures of about 150-170 deg. C. More recent fissures, observed only in the environment of reactor 13, have allowed the transport of hotter hydrothermal fluids (about 310 deg. C), likely related to the nearby intrusion of dolerite dyke. The principal implications of this work for the disposal of nuclear wastes

OKLO: Fossil nuclear reactors. Physical study

International Nuclear Information System (INIS)

Naudet, R.

1991-04-01

This book presents a study of Oklo reactors, based essentially on physics and particularly neutronics but reviewing also all what is known on this topic, regrouping observations, measurement results and interpretative calculations. A remarkable characteristic of the study is the use of sophisticated reactor calculation methods for analysis of what happened two billion years ago in a uranium deposit. 200 refs [fr

Criticality in a high level waste repository. A review of some important factors and an assessment of the lessons that can be learned from the Oklo reactors

International Nuclear Information System (INIS)

Oversby, V.M.

1996-06-01

The conditions and scenarios that might allow sufficient 239 Pu and/or 235 U to accumulate together with enough water to allow for moderation of neutron energies and thereby achieving a state where neutron-induced fission reactions could be sustained at a rate significantly above the natural rate of spontaneous fission is discussed. The uranium deposit in Oklo, Gabon, which was the site of naturally-occurring neutron-induced fission reactions approximately 2000 My ago is described. The chemistry, mineralogy, and conditions of the nuclear reactor operations are reviewed. Results of modelling the conditions for criticality at Oklo are used to estimate the amounts of spent fuel uranium that must be assembled in a favorable geometry in order to produce a similar reactive situation in a geologic repository. The amounts of uranium that must be transported and redeposited to reach a critical configuration are extremely large in relation to those that could be transported under any reasonably achievable conditions. In addition, transport and redeposition scenarios often require opposite chemical characteristics. It is concluded that the likelihood of achieving a critical condition due to accumulation of a critical mass of uranium outside the canisters after disposal is negligible. Criticality inside the canister is rendered impossible by the use of low-solubility materials inside the canisters that fill space and prevent the entry of enough water to allow moderation of neutron energies. Criticality due to plutonium outside the canister can be ruled out because it requires a series of processes, each of which has a vanishingly small probability. 25 refs, 9 tabs, 8 figs

Gas, benefits and question marks. The Oklo reactors: 100 % natural. The Kyoto protocol: use it or lose it?. Small hydro power: a great leap forward. The energy mix of South Korea

International Nuclear Information System (INIS)

Anon.

2005-01-01

This issue of Alternatives newsletter contains a main press-kit about natural gas economics worldwide and 4 articles dealing with the Oklo natural reactor, the Kyoto protocol, the small hydro-power in China, and the energy mix of South Korea: 1 - 'Gas benefits and question marks': The world's most widely distributed fossil fuel, natural gas is also the fastest-growing energy source of the past thirty years. Its position as the fuel of choice in the global energy mix is due in large part to its many domestic and industrial applications. 2 - 'The Oklo reactors: 100% natural': Another look at this extraordinary 2 billion year-old phenomenon in words and pictures: the nuclear fission reaction that created the natural reactors of Gabon. 3 - 'The Kyoto Protocol: use it or lose it?': Nearly eight years after its signature, the Kyoto Protocol is still hotly debated. Two experts give us their views: Spencer Abraham, former U.S. Secretary for Energy, and Jean-Charles Hourcade of CIRED, the international center for research on the environment and development. 4 - 'Small hydro power: a great leap forward': The Chinese government has responded to the need for rural electrification with an aid program for the country's poorest cantons. Enter the small hydro plant in northern Guangxi province. 5 - 'The energy mix of South Korea': Faced with continuing strong economic growth and energy demand, South Korea has multiplied its projects, from hydropower to tidal power to nuclear and even hydrogen in the longer term

Oklo reactors and implications for nuclear science

OpenAIRE

Davis, E. D.; Gould, C. R.; Sharapov, E. I.

2014-01-01

We summarize the nuclear physics interests in the Oklo natural nuclear reactors, focusing particularly on developments over the past two decades. Modeling of the reactors has become increasingly sophisticated, employing Monte Carlo simulations with realistic geometries and materials that can generate both the thermal and epithermal fractions. The water content and the temperatures of the reactors have been uncertain parameters. We discuss recent work pointing to lower temperatures than earlie...

Could radioactivity have played a major role in the evolution of life?

International Nuclear Information System (INIS)

Vendryes, G.

2010-01-01

A recent discovery shows the presence of the remains of multicellular organisms in rocks dating back 2.1*10 9 years which is far older than acknowledged till now. The discovery took place in Gabon near the Oklo natural reactor. The author raises the hypothesis that the passage from unicellular to multicellular organisms may have been triggered by the radiation released by uranium which was present in water at that time and began to accumulate in the sediment layers that will form the basis of the Oklo reactor millions of years later. (A.C.)

Okelobondo Uranium deposit: Regional context, stratigraphy, sedimentology, tectonic and mineralization

International Nuclear Information System (INIS)

Ango, A.M.

1993-01-01

This paper describes briefly the geology of Okelobondo uranium deposit (Gabon) and gives the study prospects of natural reactor phenomenon which depends of the operating progress state. Oklo phenomenon is considered as the best natural analogue for the study of radionuclide migration. 3 figs

U.S. studies of the Oklo phenomenon

International Nuclear Information System (INIS)

Cowan, G.A.; Bryant, E.A.; Daniels, W.R.; Maeck, W.J.

1975-01-01

Analyses of samples from the Oklo site are in agreement with previous reports by Naudet et al concerning the occurrence of a natural chain reaction in Precambrian times. A preliminary modeling of the reactor suggests that the event took place 1.7 to 1.9 b.y. ago, and that the period of criticality lasted at least 2 x 10 5 years. Uranium may have accreted and, to a lesser extent, migrated during the period of criticality or subsequent to it. (U.S.)

Tectonic analysis of the Oklo deposit

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.; Ruhland, M.; Weber, F.

1975-01-01

A large folded structure with a 40 0 incline and extending 500 m in the north-south direction has been uncovered at the Oklo mine. This structure has been analysed from the geometric and dynamic points of view in order to determine the possible role of tectonic activity in the creation of the uraniferous concentrations. Compression and extension zones which at certain points control the shape and arrangement of the lodes are associated with the structure. The natural reactors are situated in an extension zone where compartmentation and slippage, which explain the arrangement of the reactors, are observed

The Oklo phenomenon and the role of nuclear data in its study

International Nuclear Information System (INIS)

Roth, E.; Hagemann, R.; Ruffenach.

1979-01-01

The study of the OKLO phenomenon requires, but also provides, in some cases better nuclear data than that were available at the time of its discovery. Examples of this situation are given particularly for rare earth's fission yields and neutron capture cross sections

Risques naturels en montagne et analyse spatiale

Directory of Open Access Journals (Sweden)

Yannick Manche

1999-06-01

Full Text Available Le concept de risque repose sur deux notions :l'aléa, qui représente le phénomène physique par son amplitude et sa période retour ;la vulnérabilité, qui représente l'ensemble des biens et des personnes pouvant être touchés par un phénomène naturel.Le risque se définit alors comme le croisement de ces deux notions. Cette vision théorique permet de modéliser indépendamment les aléas et la vulnérabilité.Ce travail s'intéresse essentiellement à la prise en compte de la vulnérabilité dans la gestion des risques naturels. Son évaluation passe obligatoirement par une certaine analyse spatiale qui prend en compte l'occupation humaine et différentes échelles de l'utilisation de l'espace. Mais l'évaluation spatiale, que ce soit des biens et des personnes, ou des effets indirects se heurte à de nombreux problèmes. Il faut estimer l'importance de l'occupation de l'espace. Par ailleurs, le traitement des données implique des changements constants d'échelle pour passer des éléments ponctuels aux surfaces, ce que les systèmes d'information géographique ne gèrent pas parfaitement. La gestion des risques entraîne de fortes contraintes d'urbanisme, la prise en compte de la vulnérabilité permet de mieux comprendre et gérer les contraintes spatiales qu'impliquent les risques naturels. aléa, analyse spatiale, risques naturels, S.I.G., vulnérabilité

Natural fission reactors in the Franceville basin, Gabon: A review of the conditions and results of a open-quotes critical eventclose quotes in a geologic system

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.; Holliger, P.; Blanc, P.L.

1996-01-01

Natural nuclear fission reactors are only known in two uranium deposits in the world, the Oklo and Bangombe deposits of the Franceville basin: Gabon. Since 1982, five new reactor zones have been discovered in these deposits and studied since 1989 in a cooperative European program. New geological, mineralogical, and geochemical studies have been carried out in order to understand the behavior of the actinides and fission products which have been stored in a geological environment for more than 2.0 Ga years. The Franceville basin and the uranium deposits remained geologically stable over a long period of time. Therefore, the sites of Oklo and Bangombe are well preserved. For the reactors, two main periods of actinide and radionuclides migration have been observed: during the criticality, under P-T conditions of 300 bars and 400-500 degrees C, respectively, and during a distention event which affected the Franceville basin 800 to 900 Ma ago and which was responsible for the intrusion of dolerite dikes close to the reactors. New isotopic analyses on uranium dioxides, clays, and phosphates allow us to determine their respective importance for the retention of fission products. The UO 2 matrix appears to be efficient at retaining most actinides and fission products such as REEs, Y, and Zr but not the volatile fission products (Cd, Cs, Xe, and Kr) nor Rb, Sr, and Ba. Some fissiogenic elements such as Mo, Tc, Ru, Rh, Pd, and Te could have formed metallic and oxide inclusion in the UO 2 matrix which are similar to those observed in artificial spent fuel. Clays and phosphate minerals also appear to have played a role in the retention of fissiogenic REEs and also of Pu. 82 refs., 21 figs., 12 tabs

Geological follow-up of the mining of the Oklo natural rectors

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.

1978-01-01

The part of the Oklo natural reactors which was still in place after their discovery was mined between September 1975 and February 1977. In the reaction zones 27 faces and 8 outcrops have been surveyed in detail and sampled, approximately 1700 samples having been taken. In the course of these surveys a large number of sedimentological, petrographic and tectonic observations have been made. (author)

Oklo: The fossil nuclear reactors. Physics study - Translation of chapters 6, 13 and conclusions

Energy Technology Data Exchange (ETDEWEB)

Naudet, R [CEA, Paris (France)

1996-09-01

Three parts of the 1991 book `Oklo: reacteurs nucleaires fossiles. Etude physique` have been translated in this report. The chapters bear the titles `Study of criticality`(45 p.), `Some problems with the overall functioning of the reactor zones`(45 p.) and `Conclusions` (15 p.), respectively.

Oklo: The fossil nuclear reactors. Physics study - Translation of chapters 6, 13 and conclusions

International Nuclear Information System (INIS)

Naudet, R.

1996-09-01

Three parts of the 1991 book 'Oklo: reacteurs nucleaires fossiles. Etude physique' have been translated in this report. The chapters bear the titles 'Study of criticality'(45 p.), 'Some problems with the overall functioning of the reactor zones'(45 p.) and 'Conclusions' (15 p.), respectively

Natural fission reactors from Gabon. Contribution to the study of the conditions of stability of a natural radioactive wastes storage site (2 Ga)

International Nuclear Information System (INIS)

Pourcelot, L.

1997-01-01

The natural fission reactors of Oklo consists of a core of uraninite (60%) with fission products, embedded in a pure clay matrix. Thus, the aim of geological, mineral, and geochemical studies of the Oklo Reactors is to assess the behaviour of fission products in an artificial waste depository. Previous studies have shown that Reactor Zone 10, located in the Oklo mine, represents an example for an exceptional confinement of fission products since 2 Ga. In reactor Zone 9, located in Oklo open pit, migrations are more important. Reactor ZOne 13 was influenced by a thermal event due to a doleritic intrusion, located some twenty meters far away, one Ga years after fission reaction operations. In this study,we characterized temperature and redox conditions of fluids by using stable isotopes of uraninites and clays. Moreover mineralogical and chemical characteristics were defined. (author)

Considering a Lexicographic Plan for Gabon within the Gabonese Language Landscape

Directory of Open Access Journals (Sweden)

Hugues Steve Ndinga-Koumba-Binza

2011-10-01

Full Text Available

ABSTRACT: This article raises a number of questions that should be dealt with in drawing up a lexicographic plan for Gabon. For which of the Gabonese languages should lexicographic units be established? This question entrains the issue of inventorying the Gabonese languages and their standardization as well as the issue of language planning for Gabon. What is the status of those foreign languages widely spoken in Gabon? What about French? Should Gabon keep importing its French dictionaries from France, or should the Gabonese compile their own French dictionaries, including French words and expressions exclusively used in Gabon? Finally, after trying to answer these questions, a number of suggestions are made for the establishment of a lexicographic plan for Gabon.

Keywords: GABONESE LANGUAGE LANDSCAPE (GLL, LEXICOGRAPHIC PLAN FOR GABON, LANGUAGE DIVERSITY, LANGUAGE POLICY, LANGUAGE STANDARDIZATION, GABONESE LEXICOGRAPHY, NATIONAL LANGUAGE, NATIVE LANGUAGES, FOREIGN LANGUAGES

*****

OPSOMMING: Die oorweging van 'n leksikografiese plan vir Gaboen binne die Gaboenese taallandskap. Hierdie artikel bring 'n aantal vrae ter sprake waaraan aan-dag gegee moet word by die opstel van 'n leksikografiese plan vir Gaboen. Vir watter Gaboenese tale moet leksikografiese eenhede gestig word? Hierdie vraag bring die kwessie van die inventari-sering van die Gaboenese tale en hul standaardisering ter sprake, asook die kwessie van taalbe-planning vir Gaboen. Wat is die status van daardie vreemde tale wat algemeen in Gaboen gepraat word? Wat van Frans? Moet Gaboen voortgaan om sy Franse woordeboeke uit Frankryk in te voer, of moet hy sy eie Franse woordeboeke saamstel, met insluiting van Franse woorde en uitdrukkings wat uitsluitlik in Gaboen gebruik word? Ten slotte, nadat geprobeer is om hierdie vrae te beant-woord, word 'n aantal voorstelle gemaak vir die totstandbrenging van 'n leksikografiese plan vir Gaboen.

Sleutelwoorde: GABOENESE

Relevance of the studies of the OKLO natural nuclear reactors to the storage of radioactive wastes

International Nuclear Information System (INIS)

Hagemann, R.; Roth, E.

1978-01-01

The geological environment of the OKLO natural nuclear reactors is described along with the operating caracteristics of the reactors. Data relevant to the stability of most of the fission products and to the transuranium elements in the reaction zones are reviewed. (orig.) [de

Structure of the Gabon Margin from integrated seismic reflection and gravity data

NARCIS (Netherlands)

Dupre, S.; Cloetingh, S.A.P.L.; Bertotti, G.V.

2011-01-01

In the South Gabon Basin, deep multi-channel seismic reflection and gravity modeling analysis have shed light on key features of the structure of the margin. The thinned continental crust beneath the Gabon Margin appears to be composed of two distinct layers, separated by a clear, strong and more or

Natural nuclear reactor at Oklo and variation of fundamental constants: Computation of neutronics of a fresh core

International Nuclear Information System (INIS)

Petrov, Yu. V.; Nazarov, A. I.; Onegin, M. S.; Petrov, V. Yu.; Sakhnovsky, E. G.

2006-01-01

Using modern methods of reactor physics, we performed full-scale calculations of the Oklo natural reactor. For reliability, we used recent versions of two Monte Carlo codes: the Russian code MCU-REA and the well-known international code MCNP. Both codes produced similar results. We constructed a computer model of the Oklo reactor zone RZ2 which takes into account all details of design and composition. The calculations were performed for three fresh cores with different uranium contents. Multiplication factors, reactivities, and neutron fluxes were calculated. We also estimated the temperature and void effects for the fresh core. As would be expected, we found for the fresh core a significant difference between reactor and Maxwell spectra, which had been used before for averaging cross sections in the Oklo reactor. The averaged cross section of 62 149 Sm and its dependence on the shift of a resonance position E r (due to variation of fundamental constants) are significantly different from previous results. Contrary to the results of previous papers, we found no evidence of a change of the samarium cross section: a possible shift of the resonance energy is given by the limits -73≤ΔE r ≤62 meV. Following tradition, we have used formulas of Damour and Dyson to estimate the rate of change of the fine structure constant α. We obtain new, more accurate limits of -4x10 -17 ≤α·/α≤3x10 -17 yr -1 . Further improvement of the accuracy of the limits can be achieved by taking account of the core burn-up. These calculations are in progress

Dissolution and alteration of uraninite under reducing conditions

International Nuclear Information System (INIS)

Janeczek, J.; Ewing, R.C.

1992-01-01

The behavior of uraninite under hydrothermal, reducung conditions is discussed on the basis of data in the literature and the authors' investigation of samples from two natural analogue sites: Oklo, Gabon and Cigar Lake, Canada. Uraninite under reducing conditions, in the presence of saline hydrothermal solutions may be altered through dissolution, preferential loss of lead and/or Y + HREE, and coffinitization. Textural features indicative of dissolution or uraninite include embayed grain boundaries, corroded relicts of uraninite embedded in a clay matrix, and replacement of uraninite by clays and sulfides. The alteration textures and phase chemistries at Oklo and Cigar Lake are remarkably similar. Dissolution of uraninite at Cigar Lake and Oklo was associated with the precipitation or illite and was probably caused by saline, uraninite moderately acidic solutions at approximately 200deg C. Increased oxygen fugacity may have occured locally due to release of excess oxygen from uraninite during dissolution or by α-radiolysis of the solution. The formation of Pb-rich (up to 18 wt% Pb, uraninite-I) and Pb-depleted (approximately 7-8 wt% Pb, uraninite-II) uraninites at both Oklo and Cigar Lake resulted from the loss of Pb due to predominantly episodic volume diffusion related to regional geologic events. Lead loss was not associated with U mobilization. In addition to uraninite dissolution, coffinitization resulted in U, Pb and REE release. (orig.)

La gouvernance des risques naturels et la problematique des ...

African Journals Online (AJOL)

Depuis quelques années, la gouvernance des risques naturels dus aux inondations remet en cause les processus de mise en oeuvre des politiques urbaines et la qualité de la structure des aménagements dans les grandes villes du Golfe de Guinée. La perception de la gouvernance et l'application des politiques de ...

Aedes albopictus mosquito: the main vector of the 2007 Chikungunya outbreak in Gabon.

Directory of Open Access Journals (Sweden)

Frédéric Pagès

Full Text Available The primary vector at the origin of the 2007 outbreak in Libreville, Gabon is identified as Aedes albopictus, trapped around the nearby French military camp. The Chikungunya virus was isolated from mosquitoes and found to be identical to the A226V circulating human strain. This is the first field study showing the role of the recently arrived species Aedes albopictus in Chikungunya virus transmission in Central Africa, and it demonstrates this species' role in modifying the epidemiological presentation of Chikungunya in Gabon.

Postface : La gestion des risques naturels est une dynamique

NARCIS (Netherlands)

Jaboyedoff, M.; Charriere, M.K.M.; Derron, M.H.; Nicolet, P.; Sudmeier-Rieux, K.

2013-01-01

Les risques sont contrôlés par de nombreux facteurs dont, en premier lieu, les dangers, exprimés par leur fréquence (aléa) à une intensité donnée, mais aussi relativement à un fonctionnement de la société. La gestion des risques, liés aux dangers naturels, implique de les évaluer, en premier lieu,

The Oklo reactors: five years of exploration of the site

International Nuclear Information System (INIS)

Naudet, R.

1978-01-01

The main phases of the exploration of the Oklo site since the discovery of the ''reactor'' phenomenon are outlined briefly. Over 180 sampling holes were drilled during the interruption of the mining activities in the sector concerned. Several new zones have been found. Mining was resumed in the second half of 1975, providing an opportunity for highly fruitful geological follow-up work: more precise knowledge was gained of the morphology of the reactors, and very many additional samples were taken. Plant treatment of the ore and the systematic analysis of batches have made it possible to establish a balance of missing uranium-235. A small portion containing sites of intense reaction has been preserved by being anchored to the quarry wall. Mining in this sector has now finished, but new indications of fission have been found, especially in the Okelobondo sector. (author)

Péri-urbanisation et risques naturels

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Laurent Astrade

2009-03-01

d’instabilités multiples. La périurbanisation au sein de bassins montagnards aux versants instables pose des problèmes spécifiques auxquels les acteurs locaux tentent de faire face. Le bassin du Lavanchon (sud-est de Grenoble, qui combine un accroissement urbain très rapide et des versants particulièrement dynamiques est représentatif de ce rapprochement entre les aléas et les activités. L’étude diachronique de l’évolution de l’utilisation du sol entre 1956 et 2001 montre la densification des infrastructures dans la vallée et au bas des versants. Dans ce contexte, une enquête a été réalisée auprès d’un certain nombre de résidents du bassin du Lavanchon dans le but l’évaluer le degré de conscience que les populations ont des risques naturels auxquels ils sont exposés. Les résultats montrent qu’un peu plus de la moitié de la population interrogée a conscience de la problématique des risques naturels sur ce territoire, plutôt marquée selon la plupart des habitants par les risques industriels et de pollution. Les nouveaux résidants ignorent ou occultent la réalité des risques. La faible fréquence d’événements naturels marquants, l’efficacité des ouvrages de protection réalisés, l’absence d’informations de la part des pouvoirs publics et le morcellement du bassin entre plusieurs gestionnaires semble avoir généré un sentiment de sécurité par rapport aux phénomènes naturels. La répartition géographique de cette appréhension du risque montre clairement une distinction entre les habitants de la plaine et ceux des bas de versants, qui correspond assez bien à la localisation historique et actuelle des principaux aléas.

Bacterial contamination of water samples in Gabon, 2013

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Jonas Ehrhardt

2017-10-01

Full Text Available Contamination of water is a major burden in the public health setting of developing countries. We therefore assessed the quality of water samples in Gabon in 2013. The main findings were a contamination rate with coliforms of 13.5% and the detection of a possible environmental reservoir for extended spectrum beta-lactamase-producing bacteria.

Two new Thiratoscirtus species from Gabon (Araneae, Salticidae, Thiratoscirtinae

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Michael Seiter

2015-05-01

Full Text Available Two new species of jumping spiders, Thiratoscirtus oberleuthneri (♂ and Th. lamboji (♀, are described from Gabon, one of the least explored areas of the Afrotropics. Both species live in rainforest, at the forest floor. They are members of a very poorly known subfamily of salticids, the Thiratoscirtinae.

Prevalence of Plasmodium falciparum infection in pregnant women in Gabon

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Kendjo Eric

2003-06-01

Full Text Available Abstract Background In areas where malaria is endemic, pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this risk ends with delivery and decreases with the number of pregnancies. Our study aimed to demonstrate relationships between malarial parasitaemia and age, gravidity and anaemia in pregnant women in Libreville, the capital city of Gabon. Methods Peripheral blood was collected from 311 primigravidae and women in their second pregnancy. Thick blood smears were checked, as were the results of haemoglobin electrophoresis. We also looked for the presence of anaemia, fever, and checked whether the volunteers had had chemoprophylaxis. The study was performed in Gabon where malaria transmission is intense and perennial. Results A total of 177 women (57% had microscopic parasitaemia; 139 (64%of them were primigravidae, 38 (40% in their second pregnancy and 180 (64% were teenagers. The parasites densities were also higher in primigravidae and teenagers. The prevalence of anaemia was 71% and was associated with microscopic Plasmodium falciparum parasitaemia: women with moderate or severe anaemia had higher parasite prevalences and densities. However, the sickle cell trait, fever and the use of chemoprophylaxis did not have a significant association with the presence of P. falciparum. Conclusions These results suggest that the prevalence of malaria and the prevalence of anaemia, whether associated with malaria or not, are higher in pregnant women in Gabon. Primigravidae and young pregnant women are the most susceptible to infection. It is, therefore, urgent to design an effective regimen of malaria prophylaxis for this high risk population.

The contribution of remote sensing to an understanding of the geology of Gabon

International Nuclear Information System (INIS)

Bassot, J.P.

1988-01-01

A major remote-sensing operation involving radar imagery and airbone magnetism and spectrometry has been successfully conducted in Gabon. The three methods used give complementary results. Lateral radar imagery and radiometry (U, K, Th) have supplied much new information on the Upper and Lower Proterozoic, but in areas affected by intense peneplanation and lateritisation they are less effective. Conversely, Airbone magnetism gives a deeper vision into the ground: particularly it revealed that the extent of greenstone belts had been significantly underestimated on existing geological maps. In addition, the trends in these belts have given a new insight into late Archaean tectonics in northern Gabon [fr

Limits on cosmological variation of strong interaction and quark masses from big bang nucleosynthesis, cosmic, laboratory and Oklo data

International Nuclear Information System (INIS)

Flambaum, V.V.; Shuryak, E.V.

2002-01-01

Recent data on the cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of the possible variation of other constants. We discuss the variation of strong scale and quark masses. We derive limits on their relative change from (i) primordial big bang nucleosynthesis, (ii) the Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals

L'élevage d'athérures (Atherurus africanus, Gray 1842 au Gabon

Directory of Open Access Journals (Sweden)

Houben, P.

2000-01-01

Full Text Available The Breeding of Brush-tailed Porcupines (Atherurus africanus, Gray 1842 in Gabon. The brush-tailed porcupine (Atherurus africanus is a much appreciated bush meat in Gabon. On the project "Development of Game Breeding", brush-tailed porcupines are bred in two types of enclosures : an out-door enclosure and an indoor enclosure. They are fed with a diversified diet based on tubers. To obtain a successful reproduction, one male and one female have to stay together for 60 days then the female has to be separated from the male till the birth. The brush-tailed porcupine has a satisfactory growth rate but some of the reproduction features seem to call into question the profitability of its breeding.

Contribution of lead and thorium to the history of the Oklo reactors

International Nuclear Information System (INIS)

Devillers, C.; Menes, J.

1978-01-01

The authors report the results of measuring lead and thorium in a series of representative samples of the superconcentrations of uranium found in the Oklo mineralization. Interpretation of the data reveals the complexity of the history of lead in the deposit, but makes it possible to derive a number of important facts, namely early disturbance and recent, massive remobilization of lead. One is led to conclude that the date of the uranium emplacement may be greater than 1900 million years. The absence of high thorium contents in the ''normal'' rich ore confirms the importance of dating the nuclear reaction on the basis of the Th/U balance. This determination, which draws on the same set of data as for the Nd/U balance, gives a mean value close to 1930 million years. (author)

An overview of anti-diabetic plants used in Gabon: Pharmacology and toxicology.

Science.gov (United States)

Bading Taika, B; Bouckandou, M; Souza, A; Bourobou Bourobou, H P; MacKenzie, L S; Lione, L

2018-04-24

The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including 'Diabetes', 'Gabon', 'Toxicity', 'Constituents', 'hyperglycaemia' were used. A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon. Copyright �

[Epidemiology of upper gastrointestinal bleeding in Gabon].

Science.gov (United States)

Gaudong Mbethe, G L; Mounguengui, D; Ondounda, M; Magne, C; Bignoumbra, R; Ntsoumou, S; Moussavou Kombila, J-B; Nzenze, J R

2014-01-01

The department of internal medicine of the military hospital of Gabon managed 92 cases of upper gastrointestinal bleeding from April 2009 to November 2011. The frequency of these hemorrhages in the department was 8.2%; they occurred most often in adults aged 30-40 years and 50-60 years, and mainly men (74%). Erosive-ulcerative lesions (65.2%) were the leading causes of hemorrhage, followed by esophageal varices (15.2%). These results underline the importance of preventive measures for the control of this bleeding.

Le risque naturel, l'élu et l'ingénieur dans les Pyrénées Ariégeoises

OpenAIRE

Antoine , Jean-Marc; Desailly , Bertrand

1998-01-01

International audience; En France, comme dans la plupart des pays alpins, la gestion des risques naturels est confiée à un service d'Etat spécialisé : le service de Restauration des Terrains en montagne (RTM). De ce fait, ce service est devenu l'interlocuteur privilégié des élus et des collectivités locales en matière de risques naturels spécifiques à la montagne.

Summary of the mineralogical and petrographic studies of the Oklo ores, their gangues and the country rock

International Nuclear Information System (INIS)

Weber, F.; Geffroy, J.; Le Mercier, M.

1975-01-01

Observations on the spot and mineralogical studies (reflection and transmission microscopy, X-ray examination, thermal analyses) have shown that the ore in the reaction zones differs from ''normal'' Oklo ore as regards both the nature of the mineralization and the gangue and the country rock. The relationship between the two ore types on one hand and between them and the country rock on the other is studied. Theories concerning the creation of the uraniferous deposit and the effects of subsequent changes due to diagenesis and recent weathering are discussed

Gestion des risques naturels et prise en compte du développement durable : un lien équivoque. Le cas du sud grenoblois

Directory of Open Access Journals (Sweden)

Lauren Andres

2009-01-01

Full Text Available Cet article questionne la nature du lien envisageable entre risque naturel et développement durable à travers l’étude du territoire du sud grenoblois, soumis notamment à deux aléas naturels majeurs : le mouvement de terrain de grande ampleur dit des « Ruines de Séchilienne » et les probables crues de la Romanche et du Drac. Trois étapes structurent cette réflexion questionnant la transition supposée entre une gestion des risques naturels et une gestion durable des territoires soumis aux risques naturels : une association toute relative, un lien logique mais limité sur le terrain, une relation surtout indirecte. Les interactions identifiées, en termes législatifs mais aussi idéels et opérationnels, entre risque et durabilité se révèlent ainsi complexes et ne sont pas forcément explicites ; elles dépendent en particulier de multiples échelles territoriales (nationales à locales, confrontant alors pour l’essentiel des stratégies d’acteurs – porteurs des décisions ou du savoir technique – distinctes.

Rural emptiness and its influence on subsistence farming in contemporary Gabon : a case study in Loango National Park.

OpenAIRE

Fairet, E.; Bell, S.; Remanda, K.; Setchell, J.M.

2014-01-01

In sub-Saharan Africa, rural exodus leads to increasing unemployment in urban centres and to the disorganisation of farming practice in rural areas. This article draws on data from participant observation and interviews to analyse how rural exodus, combined with a population density that was already low, led to what we refer to as rural emptiness in Gabon, and how this affects farmers’ livelihoods. Farming in Gabon is largely slash and burn agriculture with a gender division of...

Changes in arthropod assemblages along a wide gradient of disturbance in Gabon

Czech Academy of Sciences Publication Activity Database

Basset, Y.; Missa, O.; Alonso, A.; Miller, S. E.; Curletti, G.; De Meyer, M.; Eardley, C.; Lewis, O. T.; Mansell, M. W.; Novotný, Vojtěch; Wagner, T.

2008-01-01

Roč. 22, č. 6 (2008), s. 1552-1563 ISSN 0888-8892 Grant - others:Gabon Biodiversity Program(GA) No. 104 Institutional research plan: CEZ:AV0Z50070508 Keywords : indicator taxa * predictor sets * rainforest Subject RIV: EH - Ecology, Behaviour Impact factor: 4.705, year: 2008

Le Gaz Naturel Véhicule Natural Gas for Vehicles

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De Chauveron S.

2006-11-01

Full Text Available Cet article présente le GNV (Gaz Naturel Véhicule. Le GNV a en effet de sérieux atouts, à la fois comme carburant de substitution et comme carburant propre. Ces atouts sont aussi bien économiques que techniques. La première partie est consacrée aux enjeux du développement du GNV. Les premiers pays utilisateurs ont été ceux qui disposent sur leur sol de ressources de gaz naturel. Aujourd'hui, alors que de nombreux pays doivent faire face à l'inquiétude croissante relative à l'augmentation de la pollution urbaine, le gaz naturel apparaît également comme un carburant propre, permettant de réduire rapidement les émissions de polluants des véhicules. Dans une deuxième partie, nous donnons une description technique sommaire des stations GNV et des véhicules GNV. Il s'agit de familiariser le lecteur avec les quelques spécificités techniques du GNV, par rapport à l'essence et au gazole. On constatera d'ailleurs que les technologies GNV sont très proches des technologies classiques. Enfin, la dernière partie est consacrée aux actions en cours, qui permettront le développement du GNV en France et en Europe : programmes de recherche, réduction des coûts de la filière, actions réglementaires, communication, etc. This article presents compressed natural gas for vehicles (CNG, which can provide considerable advantages both as an alternative fuel and as a clean fuel. These assets are not only economic but also technical. The first part deals with what is at stake in developing natural gas as a motor fuel. The first countries to use CNG were those with natural gas resources in their subsoil. Today, with a large number of countries having to cope with growing concern about increasing urban pollution, natural gas is also seen as a clean fuel that can help cut vehicle pollutant emissions dramatically. In the second part a brief technical description is given of CNG stations and vehicles, with the aim of acquainting the reader with

Emergence of blaNDM-7-Producing Enterobacteriaceae in Gabon, 2016.

Science.gov (United States)

Moussounda, Mesmin; Diene, Seydina M; Dos Santos, Sandra; Goudeau, Alain; François, Patrice; van der Mee-Marquet, Nathalie

2017-02-01

Reports of carbapenemase-producing Enterobacteriaceae in Africa remain rare and assess mostly bla OXA-48 -producing isolates from Mediterranean countries and South Africa. We identified bla NDM-7 -producing Enterobacteriaceae in Gabon in 2016. The isolates contained bla NDM-7 IncX3 plasmids that were unusual and similar to the one described in a colistin-resistant Klebsiella pneumoniae SZ04 isolate from China.

Ecology and life history of Paratomapoderus brachypterus in Gabon (Coleoptera: Attelabidae

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Silvano Biondi

2017-12-01

Full Text Available On the base of data collected during four expeditions in Gabon (West Africa from 2012 to 2016, the authors provide new information on trophic activity and reproductive behaviour of Paratomapoderus brachypterus (Voss, 1926 (Attelabidae: Apoderinae, Hoplapoderini, with emphasis on leaf-roll realisation; host plant, leaf roll, larva and pupa are illustrated for the first time.

An assessment of high carbon stock and high conservation value approaches to sustainable oil palm cultivation in Gabon

Science.gov (United States)

Austin, Kemen G.; Lee, Michelle E.; Clark, Connie; Forester, Brenna R.; Urban, Dean L.; White, Lee; Kasibhatla, Prasad S.; Poulsen, John R.

2017-01-01

Industrial-scale oil palm cultivation is rapidly expanding in Gabon, where it has the potential to drive economic growth, but also threatens forest, biodiversity and carbon resources. The Gabonese government is promoting an ambitious agricultural expansion strategy, while simultaneously committing to minimize negative environmental impacts of oil palm agriculture. This study estimates the extent and location of suitable land for oil palm cultivation in Gabon, based on an analysis of recent trends in plantation permitting. We use the resulting suitability map to evaluate two proposed approaches to minimizing negative environmental impacts: a High Carbon Stock (HCS) approach, which emphasizes forest protection and climate change mitigation, and a High Conservation Value (HCV) approach, which focuses on safeguarding biodiversity and ecosystems. We quantify the forest area, carbon stock, and biodiversity resources protected under each approach, using newly developed maps of priority species distributions and forest biomass for Gabon. We find 2.7-3.9 Mha of suitable or moderately suitable land that avoid HCS areas, 4.4 million hectares (Mha) that avoid HCV areas, and 1.2-1.7 Mha that avoid both. This suggests that Gabon’s oil palm production target could likely be met without compromising important ecosystem services, if appropriate safeguards are put in place. Our analysis improves understanding of suitability for oil palm in Gabon, determines how conservation strategies align with national targets for oil palm production, and informs national land use planning.

99Tc, Pb and Ru migration around the Oklo natural fission reactors

International Nuclear Information System (INIS)

Gancarz, A.; Cowan, G.; Curtis, D.; Maeck, W.

1980-01-01

This work demonstrates the utility of the Oklo uranium ore deposit and natural fission reactors as a long time scale analogue for man-made radioactive waste repositories. It has been shown that the ores and nearby rocks were open to the loss and gain of 99 Tc, ruthenium, and lead relative to uranium. Identified regions of element deficiencies and those which are correspondingly enriched are separated by less than 10 meters. However, more extensive sampling is required to define the overall extent of the element migration. Element fractionation took place on at least two vastly different time scales; 99 Tc was fractionated from ruthenium within one million years of the end of reactor criticality. Lead-uranium fractionation has been ongoing for most of the two billion years since the ores were formed. Diffusion loss of lead from host uraninite appears to be an important process in the fractionation of lead from uranium

Synthesis of the mineralogic and petrographic studies of the ore minerals from Oklo, their gangues and the surrounding rocks

International Nuclear Information System (INIS)

Weber, F.; Geoffroy, J.; Le Mercier, M.

Observations on the spot and mineralogical studies (reflection and transmission microscopy, x-ray examination, thermal analyses) have shown that the ore in the reaction zones differs from ''normal'' Oklo ore as regards both the nature of the mineralization and the gangue and the country rock. The relationship between the two ore types on one and between them and the country rock on the other is studied. Theories concerning the creation of the uraniferous deposit and the effects of subsequent changes due to diagenesis and recent weathering are discussed

Novitates Gabonenses 71. A new species of Uapaca (Phyllanthaceae, formerly Euphorbiaceae) from Gabon

NARCIS (Netherlands)

Breteler, F.J.

2012-01-01

Background and aims - The African genus Uapaca of the Phyllanthaceae (formerly Euphorbiaceae) is revised for the Flore du Gabon. Prior to its publication, the present paper publishes a new species from that country. Methods - Normal practices of herbarium taxonomy have been applied to study all

Oklo reactors: natural analogs to nuclear waste repositories

International Nuclear Information System (INIS)

Curtis, D.B.; Benjamin, T.M.; Gancarz, A.J.

1981-01-01

The 2-billion-year-old fossil reactors at Oklo are ancient natural nuclear waste sites. Isotope dilution mass spectrometric analyses of the fission products in the reactor core uraninite and the peripheral pelitic sandstone provide data for calculating the reactor operating parameters, the quantities of fissiogenic isotopes produced, the fraction of these isotopes retained in the cores, and the location in the peripheral rocks of the fissiogenic fraction lost from the cores. For a duration of criticality of 3 x 10 5 yrs, the thermal plus resonance neutron fluence ranged between 10 20 and 10 21 neutrons/cm 2 . The fraction of technetium (60 to 85%), ruthenium (75 to 90%), and neodymium (85 to 100%) retained is negatively correlated with fluence. The lost fission products are contained within a few tens of meters of their source, the reactor cores. The systematics of the decay of 99 Tc (t/sub 1/2/ = 2.13 x 10 5 yr) to 99 Ru limits the period of fissiogenic element migration to approximately 1 million yr at a time 2 billion yr ago. Thermodynamic calculations of the temperature-dependent solubilities indicate that the loss of fissiogenic elements is diffusion controlled, whereas retention in the surrounding rocks is a result of temperature-dependent deposition from an aqueous solution. These results concerning the geochemistry of technetium, ruthenium, and neodymium at a natural waste site support the concept of geologic burial of man-made radioactive wastes

Petroleum and natural gas economy in Arab countries, Angola, Iran, Gabon and Nigeria

International Nuclear Information System (INIS)

Sarkis, N.

1993-01-01

This paper describes briefly main informations on petroleum production, prices and markets trends, trade and contracts, petroleum and natural gas exploration in Gabon, Tunisia, United Arab Emirates, Egypt and Sudan. Algeria and Portugal have signed a contract for natural gas supply of 2.1 Gm 3

Activite locomotrice de souris isolees, de deux lignees consanguines, dans un environnement semi-naturel ou en cages d'elevage.

Science.gov (United States)

Le Pape, G; Lassalle, J M

1979-10-01

Des enregistrements continus d'activité locomotrice ont été effectués sur des souris mâles isolées des lignées Balb/c et C57bl/6, vivant en cages d'élevage ou en milieu semi- naturel. Les résultats montrent que les différences entre ces deux situations ne sont pas perçues de la même façon par les animaux des deux lign'ees: alors qu'en cages d'élevage les souris des deux lignées experiment la même quantité totale d'activaté, en milieu semi-naturel les souris Balb/c sont plus actives que les C57bl/6. En outre, l≐s différences observées entre les lignées pour la repartition de l'activité au cours du nycthèmere s'inversent lorsque l'on passe d'une situation à l'autre. L'étude de la variabilité fait aparaître une dispersion plus grande des performances dans la lignée C57bl/6 en cages d'élevage, alors qu'en milieu semi-naturel la dispersion est plus chez Bal/c. Copyright © 1979. Published by Elsevier B.V.

Choice of metrics for studying arthropod responses to habitat disturbance: one example from Gabon

Czech Academy of Sciences Publication Activity Database

Basset, Y.; Missa, O.; Alonso, A.; Miller, S. E.; Curletti, G.; De Meyer, M.; Eardley, C.; Lewis, O. T.; Mansell, M. W.; Novotný, Vojtěch; Wagner, T.

2008-01-01

Roč. 1, č. 1 (2008), s. 55-66 ISSN 1752-458X Grant - others:Gabon Biodiversity Program(GA) No. 103 Institutional research plan: CEZ:AV0Z50070508 Keywords : additive diversity partitioning * biodiversity * nestedness Subject RIV: EH - Ecology, Behaviour

Faunal turnover of arthropod assemblages along a wide gradient of disturbance in Gabon

Czech Academy of Sciences Publication Activity Database

Basset, Y.; Missa, O.; Alonso, A.; Miller, S. E.; Curletti, G.; De Meyer, M.; Eardley, C. D.; Mansell, M. W.; Novotný, Vojtěch; Wagner, T.

2008-01-01

Roč. 16, č. 1 (2008), s. 47-59 ISSN 1021-3589 Grant - others:Gabon Biodiversity Program(GA) No. 105 Institutional research plan: CEZ:AV0Z50070508 Keywords : biodiversity * parataxonomy * rainforest Subject RIV: EH - Ecology, Behaviour Impact factor: 0.308, year: 2008 http://journals.sabinet.co.za/essa

Les Burkinabè du Gabon : une migration à l'aune des aléas ...

African Journals Online (AJOL)

24 juin 2015 ... dans le cadre de la politique de recrutement de main-d'œuvre initiée .... dans les entreprises de construction qui tentent de promouvoir la culture ...... Le Gabon peut apparaître dans les stratégies migratoires burkinabè comme.

Tuberculosis patients hospitalized in the Albert Schweitzer Hospital, Lambaréné, Gabon-a retrospective observational study.

Science.gov (United States)

Stolp, S M; Huson, M A M; Janssen, S; Beyeme, J O; Grobusch, M P

2013-11-01

Epidemiological data on tuberculosis in Central Africa are limited. We performed a retrospective observational study on clinical characteristics of 719 hospitalized tuberculosis patients in Lambaréné, Gabon. Human immunodeficiency virus (HIV) co-infection rate was high (34%) and in-hospital mortality was significantly higher in HIV-positive patients (10% versus 2%). Long-term information on patient outcome was limited; however, from 2008 to 2011, loss to follow up was noted in 28% of cases. Our data illustrate the high burden of TB in Gabon, where loss to follow up and emerging drug resistance are important problems for which comprehensive data are still lacking. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

L'imaginaire du Bureau et Les Usages du Fétiche au Gabon

African Journals Online (AJOL)

un objet-souvenir, des pots de fleurs. Les photographies, les souvenirs de voyages et les présents sont les éléments les plus courants de l'appropriation. Toutefois, au Gabon, le bureau est aussi le prolongement de l'individu dans un système de représentations sociales, c'est-à-dire sa vie. Son corps est indissociable de ...

113 Étude de la qualité des eaux épurées par le lagunage naturel ...

African Journals Online (AJOL)

sam

Mots-clés : lagunage naturel, performances, eaux usées, Algérie. Abstract ... domaine de l'irrigation agricole. Le ratio entre les ... traitement biologique : Cette filière est composée de six bassins, qui sont réparties suivant trois étages : • .

Odométrie visuelle en milieu naturel pour les robots mobiles

OpenAIRE

Duperal, B.

2013-01-01

/ Dans le cadre de ce stage, l'objectif est d'étudier les performances de la vision artificielle, pour permettre à un robot mobile de se localiser, en utilisant soit une caméra, soit un système de stéréovision, dans un environnement naturel (arbres, cultures, champs agricoles, bâtiments,...), suite à des pertes de signal GPS. La localisation de robots par vision artificielle nécessite de réaliser des opérations d'appariement de points invariants (détection d'amers, zones particulières sur ...

Uranium redistribution under oxidizing conditions in Oklo natural reactor zone 2, Gabon

International Nuclear Information System (INIS)

Isobe, H.; Ohnuki, T.; Murakami, T.; Gauthier-Lafaye, F.

1995-01-01

This mineralogical study was completed to elucidate the relationships between uranium distribution and alteration products of the host rock of natural reactor zone clays just below the reactor core. Uraninite is preserved without any alteration in the reactor core. Uranium minerals are found to be present in the fractures in the reactor zone clays associated with iron-mineral veins, galena and Ti-bearing minerals. Uranium, for which the phases could not be identified, occurs in iron-mineral veins and the iron-mineral rim of pyrite grains in the reactor zone clays. Uranium is not associated with granular iron minerals occurring in the illite matrix of the reactor zone clays. The degree of crystallinity and uranium content of the three iron-bearing alteration products suggest that they formed under different conditions; the granular iron minerals, under alteration conditions where uranium was not mobilized while the iron-mineral veins and the iron-mineral rim of pyrite, under conditions in which uranium is mobilized after the formation of the granular iron minerals

Effects of post-burial siliceous diagenesis deformations on the microthermometric behaviour of fluid inclusions: an example in the Francevillian uraniferous sandstone reservoir (Gabon)

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.; Weber, F.

1984-01-01

New data about fluid inclusions associated to a siliceous diagenesis show that a deformation phase in the first stage of catagenesis disturbed their microthermometric behaviour. Nevertheless, temperature and pressure of fluids associated to the uraniferous paragenesis and contemporary with the Oklo natural reactors are estimated at 140-160 0 C and 250-500 bar [fr

Rift Valley fever virus seroprevalence in human rural populations of Gabon.

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Xavier Pourrut

Full Text Available BACKGROUND: Rift Valley fever (RVF is a mosquito-borne viral zoonosis caused by a phlebovirus and transmitted by Aedes mosquitoes. Humans can also be infected through direct contact with blood (aerosols or tissues (placenta, stillborn of infected animals. Although severe clinical cases can be observed, infection with RVF virus (RVFV in humans is, in most cases, asymptomatic or causes a febrile illness without serious symptoms. In small ruminants RVFV mainly causes abortion and neonatal death. The distribution of RVFV has been well documented in many African countries, particularly in the north (Egypt, Sudan, east (Kenya, Tanzania, Somalia, west (Senegal, Mauritania and south (South Africa, but also in the Indian Ocean (Madagascar, Mayotte and the Arabian Peninsula. In contrast, the prevalence of RVFV has rarely been investigated in central African countries. METHODOLOGY/PRINCIPAL FINDINGS: We therefore conducted a large serological survey of rural populations in Gabon, involving 4,323 individuals from 212 randomly selected villages (10.3% of all Gabonese villages. RVFV-specific IgG was found in a total of 145 individuals (3.3% suggesting the wide circulation of Rift Valley fever virus in Gabon. The seroprevalence was significantly higher in the lakes region than in forest and savannas zones, with respective rates of 8.3%, 2.9% and 2.2%. In the lakes region, RVFV-specific IgG was significantly more prevalent in males than in females (respectively 12.8% and 3.8% and the seroprevalence increased gradually with age in males but not in females. CONCLUSIONS/SIGNIFICANCE: Although RVFV was suggested to circulate at a relatively high level in Gabon, no outbreaks or even isolated cases have been documented in the country. The higher prevalence in the lakes region is likely to be driven by specific ecologic conditions favorable to certain mosquito vector species. Males may be more at risk of infection than females because they spend more time farming and

Marie-Eugénie Kaufmant, Poétique des espaces naturels dans la «Comedia nueva»

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Alexandre Roquain

2012-12-01

Full Text Available Review of Marie-Eugénie Kaufmant, Poétique des espaces naturels dans la «Comedia nueva», Casa de Velázquez (Bibliothèque de la Casa de Velázquez, 48, Madrid, 2010, 571 pp. ISBN: 978-84-96820-40-1.

Analyse quantitative de la consommation en viande de brousse en vue d'une gestion durable de la faune sauvage au Gabon

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Ngama, S.

2015-01-01

Full Text Available Quantitative Analysis of Bush Meat Consumptions for a Sustainable Wildlife Management in Gabon. In Gabon, like everywhere in the Central Africa region, hunting could lead to serious ecological damages in the near future. Yet, quantifying bush meat contribution to local people diet will help to improve the efficiency when operating necessary hunting regulation. The purpose of this study was to provide more data on wildlife contribution to forest people's diet and the influence of related factors. To do so, 36 households were surveyed during one year time in the Ipassa reserve buffer zone inMakokou, Gabon. This study reveals that 53.1% of meats consumed by surveyed people are from wildlife. Moreover, this consumption was influenced by (i the fact that households' chiefs are salaried, farmers or hunters, (ii the distance from households' residences to the reserve and (iii meat prices on markets. In addition, poultry meat appears to be a potential alternative to bushmeat and even constituted 52.4% of consumptions in one of the survey areas where the greatest number ofhouseholds' chiefs were salaried.

Population structure of Legionella spp. from environmental samples in Gabon, 2013.

Science.gov (United States)

Ehrhardt, Jonas; Alabi, Abraham S; Kuczius, Thorsten; Tsombeng, Francis Foguim; Becker, Karsten; Kremsner, Peter G; Schaumburg, Frieder; Esen, Meral

2015-07-01

Aquatic environments are the most important source for Legionella spp. infections such as Legionnaires' disease and Pontiac fever. The reservoirs of Legionella spp. are mostly unclear in sub-Saharan Africa. The aim of this study, conducted in 2013, was to identify geographical areas of an increased risk for exposure to Legionella spp., and to describe the population structure of Legionella spp. from different water sources in a cross-sectional study in Gabon. Fresh water samples (n = 200) were cultured on Legionella selective agar; species were confirmed by MALDI-TOF, a Legionella pneumophila specific real-time PCR and 16S RNA gene sequencing. Serogroups were identified by agglutination test. The population structure was assessed by multilocus sequence typing (MLST). Legionella spp. isolates (n = 29) were frequently found in the hospital setting particularly in hot water systems. Open water bodies (i.e. rivers, lakes) were not contaminated with Legionella spp. Isolated L. pneumophila mainly belonged to serogroups 2-14 (n = 19) and MLST sequence type ST1, ST75 (and related STs) and ST1911. In conclusion, hospitalized patients might have an increased risk to become infected with Legionella spp. in the studied areas in Gabon, particularly if they have risk factors such as comorbidities. Both broadly extended (ST1, ST75) and local lineages (ST1911) were present in our setting. Copyright © 2015 Elsevier B.V. All rights reserved.

Uraniferous minerals - uraninite and derived or related uraniferous minerals; Mineraux uraniferes - uraninite et mineraux uraniferes derives ou associes

Energy Technology Data Exchange (ETDEWEB)

Lebrun, P.; Cesbron, F.; Le Cleac' h, J.M.; Lebocey, J.

2009-07-01

This special issue of 'Mineraux et Fossiles' journal (no.28) proposes a real trip in the uranium world with the exception of the industrial and military applications. The book comprises 6 chapters fully illustrated with figures and photos of minerals dealing with: 1 - a brief history of uranium (including radioactivity); 2 - crystallo-chemistry of some uranium minerals; 3 - uranium minerals with a presentation of the most important species ('remarkable' species); 4 - classification of uranium deposits; 5 - most famous uranium deposits which played an important role in the development of nuclear industry (Jachymov deposit in Czech Republic, Shinkolobwe in Katanga, Oklo in Gabon etc); 6 - uranium usages, in particular in glass and ceramics coloring and in geochronology. (J.S.)

A precursor to the treatment of Dorstenia for the floras of Cameroun and Gabon

NARCIS (Netherlands)

Berg, C.C.; Hijman, M.E.E.

1977-01-01

The present paper is the result of a study of Dorstenia mainly made on behalf of the Floras of Cameroun and Gabon. It presents, as a precursor to the treatment in those Floras, some general remarks on the genus Dorstenia, a key to the species, a survey of the taxa distinguished, new combinations and

Insect Pests Occurring on Dacryodes edulis (Burseraceae) in Rural Areas in Gabon.

Science.gov (United States)

Poligui, R N; Mouaragadja, I; Vandereycken, A; Haubruge, E; Francis, F

2014-08-01

The inventory of pests occurring on Dacryodes edulis (Burseraceae) was carried out in rural areas in Gabon during 2009 and 2010. Yellow traps and visual observations were used to record weekly pests during the tree flowering stage, in five villages. Catches from yellow traps rose to 7,296 and 1,722 insect pests in 2009 and 2010, respectively, whereas records from visual observations corresponded to 1,812 and 171 insect pests in 2009 and 2010, respectively. During both years, abundance from traps and visual monitoring was significantly different between sampling sites (p pests' diversity between sampling sites was not significant (p > 0.05) according to traps, but significant (p ≤ 0.04) according to visual observations in 2010. Mecocorynus loripes Chevrolat (Coleoptera: Cucurlionidae) attacked the stem of D. edulis, while Oligotrophus sp. (Diptera: Cecidomyiidae), Pseudophacopteron serrifer Malenovsky and Burckhardt (Hemiptera: Phacopteronidae), and Selenothrips rubrocinctus Giard (Thysanopera: Thripidae) attacked leaves. Pseudonoorda edulis Maes and Poligui (Lepidoptera: Crambidae) and Lobesia aeolopa Meyrick (Lepidoptera: Tortricidae) infested fruits and inflorescences, respectively. These insects are specifically linked to plant patterns, and their identification provided the first basic information for developing suitable strategies to control pests of D. edulis in Gabon, as well as in neighboring central African countries.

The decrease of crude prices in Gabon. A magnifying mirror of a structural economic crisis, and of the failure of political policies

International Nuclear Information System (INIS)

Auge, Benjamin

2016-01-01

As Gabon has been producing oil since 1957 and has had one of the highest GDP in Africa (because of this resource and its limited population), it also displays (for the same reasons) a very low diversification of its economy and a hypertrophy of the hydrocarbon sector. After an overview of the oil sector in Gabon which shows that the sector is now damaged, the author outlines that the impoverishment of the population seems unavoidable without a strong diversification policy. In other words, the Gabonese power cannot rely on the oil sector on the long term

Tuberculosis patients hospitalized in the Albert Schweitzer Hospital, Lambaréné, Gabon-a retrospective observational study

NARCIS (Netherlands)

Stolp, S. M.; Huson, M. A. M.; Janssen, S.; Beyeme, J. O.; Grobusch, M. P.

2013-01-01

Epidemiological data on tuberculosis in Central Africa are limited. We performed a retrospective observational study on clinical characteristics of 719 hospitalized tuberculosis patients in Lambaréné, Gabon. Human immunodeficiency virus (HIV) co-infection rate was high (34%) and in-hospital

Oklo natural fission reactor program. Progress report, April 1-August 31, 1980

International Nuclear Information System (INIS)

Curtis, D.B.

1980-12-01

An interim report has been published on the redistribution of uranium, thorium, and lead in samples representing several million cubic meters of sandstone and metamorphosed sediments in the Athabasca Basin which is located in the northwest corner of the Canadian province of Saskatchewan. The region of study includes zones of uranium mineralization at Key Lake. Mineralization occurs at the unconformity between the Athabasca sandstone and the underlying metasediments and in fault zones within the metasediments. Lead isotopes record a radiometric age of 1300 +- 150 m.y. in samples from above and below the unconformity. This age probably reflects the time of deposition of the sandstones and an associated redistribution of uranium and/or lead in the underlying rocks. Many of the samples have been fractionated with respect to radiogenic lead and the actinide parent elements since that time. Sandstones and altered rocks from the region above the unconformity have been a transport path and are a repository for lead. In contrast, mineralized rocks are deficient in radiogenic lead and must be an important source of lead in the local geologic environment. Samples from Oklo reactor zone 9 and nearby host rocks have been prepared for isotopic analyses of ruthenium, molybdenum, uranium and lead

[Epidemiology of pain in Gabon].

Science.gov (United States)

Nzoghe Nguema, Pierre; Ngaka Nsafu, D

2004-01-01

The authors report on a prospective survey which took place from January 1999 to December 2000 - the epidemiology of pain in Gabon - to determine its distribution in the population. Ninety-eight women and eighty-four men aged 17 to 80 years old (mean age: 50) who consulted at the pain clinic were included in the study, a majority of the patients being aged between 21 and 60 years. Lower back pains and gonalgias secondary to osteo-arthritis or arthritis were more common in the North of the country, where the patients represented 57.7% of the sample, these two previous localisations along with cephalagias accounting for 52.7% of the motives for the visits. Thoracic and abdominal pains common in both men and women in the South were psychological. Patients working in the tertiary sector represented 45.3% of the patients, those of the secondary sector 24.4%, and those of the primary 20.3%. The non-steroidal anti-inflammatory analgesics (NSAI) associated with WHO grade 1 and 2 analgesics were effective in 50% of cases, some of whom also needed steroidal articular infiltration. Psychological pains were soothed by amitriptyline. A specific training of doctors and paramedics in pain treatment is necessary to improve care and assistance in this area. Copyright John Libbey Eurotext 2003.

artographie des risques naturels dans les Pyrénées et sur leur piémont

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Jean-Marc ANTOINE

1994-12-01

Full Text Available Les recherches menées par le CIMA URA-366 sur les risques naturels dans les Pyrénées privilégient leur dimension historique et l’étude des contextes socio-écologiques dans lesquels ils s’inscrivent. Cette approche novatrice débouche sur une cartographie historique des phénomènes, conjugant plusieurs niveaux d’analyse spatiotemporels.

Petroleum and natural gas economy in Arab Countries, in Congo, Ethiopia, Gabon and Iran. Economie petroliere et gaziere dans les Pays Arabes, au Congo, en Ethiopie, Gabon et Iran

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-05-16

This paper gives informations on petroleum and natural gas industry, petroleum market and prices, trade and contracts, prospection and investments: Portugal has retained the candidature of ten foreign companies for the introduction of natural gas in 1996 and the first enhanced recovery contract will relate to Rhourde El Baguel natural gas field (Algeria). New contracts have been signed for exploration or development of petroleum or natural gas fields in Gabon, Ethiopia and Libya. Iraq has restarted its petroleum exports and Iranian production has diminished.

Natural scientific strategy for nuclear wastes: Philosophy of Dr. Rodney C. Ewing at Stanford

Energy Technology Data Exchange (ETDEWEB)

Woo, T. H. [The Cyber University of Korea, Seoul (Korea, Republic of)

2016-10-15

In the geological study, the naturally adapted region was discovered in Oklo, a central African area of Gabon seen in Fig. 1. Currently, this naturally operated nuclear fission site has been stabilized where the artificial shielding structure was not equipped. So, it has been studied to be an exemplified high-level nuclear waste repository. This could give a lesson that one should make the nuclear repository construction. The simplified configuration of the Oklo natural nuclear reactor site is described. The important mentions of Dr. Ewing reflected his philosophy in geological repository and there is a biography. It is necessary to understand the very big difference between human’s cognitive timescale and geological timescale where it could be nearly impossible to construct the long-term or even permanent nuclear waste repository. It is important to understand the opposite opinions of the nuclear waste repository. The government made the milestone of the South Korean repository policy in which the final repository completion was decided as 2053, about 40 years later. Until the time, there is enough time to rethink for the long-term waste repository. It is certain the policy-maker of this nuclear waste policy will be out of the nuclear community before 2053. This means the politician will not take any responsibility of the result of this policy.

Natural scientific strategy for nuclear wastes: Philosophy of Dr. Rodney C. Ewing at Stanford

International Nuclear Information System (INIS)

Woo, T. H.

2016-01-01

In the geological study, the naturally adapted region was discovered in Oklo, a central African area of Gabon seen in Fig. 1. Currently, this naturally operated nuclear fission site has been stabilized where the artificial shielding structure was not equipped. So, it has been studied to be an exemplified high-level nuclear waste repository. This could give a lesson that one should make the nuclear repository construction. The simplified configuration of the Oklo natural nuclear reactor site is described. The important mentions of Dr. Ewing reflected his philosophy in geological repository and there is a biography. It is necessary to understand the very big difference between human’s cognitive timescale and geological timescale where it could be nearly impossible to construct the long-term or even permanent nuclear waste repository. It is important to understand the opposite opinions of the nuclear waste repository. The government made the milestone of the South Korean repository policy in which the final repository completion was decided as 2053, about 40 years later. Until the time, there is enough time to rethink for the long-term waste repository. It is certain the policy-maker of this nuclear waste policy will be out of the nuclear community before 2053. This means the politician will not take any responsibility of the result of this policy

Le développement durable du tourisme dans les territoires insulaires français et la valorisation touristique des espaces naturels littoraux métropolitains

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Nadège Lombard

2009-05-01

Full Text Available Cet article aborde la question du développement touristique dans les territoires insulaires, et propose un éclairage plus particulier sur la valorisation touristique des espaces naturels. Il présente, tout d’abord, les enjeux du développement durable du tourisme dans les territoires insulaires français. En fonction de la taille des îles, de leur accessibilité, de l’importance de leur fréquentation touristique on peut distinguer différents types d’îles.  Le défi pour chaque  île réside dans la mise en oeuvre d’un projet en étroite adéquation avec ses propres ressources et les spécificités de son territoire pour assurer un développement durable du tourisme. L’article illustre ensuite l’exemple de la valorisation touristique des espaces naturels, l’ambivalence du rapport entre le tourisme et ces espaces. Il s’attache à montrer en quoi le tourisme qui peut être parfois à l’origine de la  dégradation des espaces naturels peut être source de retombées positives pour l’environnement dès lors que les acteurs du territoire sont en situation de gérer leur développement. L’article s’achève sur un essai d’élaboration de grille d’évaluation des retombées économiques liées à la valorisation touristique des espaces naturels, appliqué à l’exemple du site naturel de la Pointe d’Agon, situé au nord du Mont Saint Michel, dans le département de la Manche.This article tackles with the issue of tourism in islands and focuses on tourist development of natural sites. First it highlights the issue of sustainable tourism for French islands. Several types of islands can be characterized, according to size, accessibility, tourist-going... To guarantee a sustainable development, the challenge is to lead a project based on the characteristics of the island and its own ressources.Then, this article enlarges on the paradox between tourism and conservation. Tourism can damage the environment but, when it

AREVA in Gabon. Inquiry report on the situation of workers of the COMUF, Gabonese subsidy of the AREVA-COGEMA group

International Nuclear Information System (INIS)

2007-01-01

After a recall of the development of uranium mining activities by the COMUF Company which is now a subsidy company of the AREVA-COGEMA group, and a presentation of the inquiry, this document reports the inquiry performed in Gabon about the medical issue (with notably inadequate security measures) and about the environmental issue related to the site rehabilitation. It also reports the analysis of questionnaires sent to ex-workers in Gabon, as well as of testimonies obtained from expatriates who are suffering from health problems. The report discusses the possibilities to take legal actions for different reasons: unintentional injuries and homicide, endangering the life of others, or inexcusable error. In conclusion the report outlines that the risk was known, that there was no information about it, and that people were deliberately maintained in ignorance

The effect of parasitic co-infections on immune responses in Gabon : particular emphasis on malaria and helminths

NARCIS (Netherlands)

Ateba, Ngoa U.

2016-01-01

The work presented in this thesis aimed at increasing our understanding of the effect of helminths on Plasmodium spp. immune response in co-infected individuals living in endemic countries. It presents data from studies conducted in rural and semi urban areas of Lambaréné (Gabon) where the burden of

Radiolysis in nature: Evidence from the Oklo natural reactors

International Nuclear Information System (INIS)

Curtis, D.B.; Gancarz, A.J.

1983-02-01

An examination of the mineralogy of the reactor zones at Oklo shows that they have been significantly altered. The rocks immediately adjacent to these zones are also mineralogically modified with respect to normal uranium bearing rocks. The mineralogic changes appear to be the consequence of radiation damage, changes in the bulk chemistry of the system and increased temperatures. Chemical changes were the consequence of convectively circulating fluids that transported elements in and out of the rocks. There were also changes in the electrochemical conditions in the rocks. These changes can most reasonably be attributed to oxidizing and reducing species produced by the radiolysis of water. We have calculated radiation doses and examined the production of radiolysis products in the fluid phase which lead to the following conclusions: 1) There was a net reduction of iron, probably associated with a net increase in total iron in the rocks of the reactor zones. The reduction of iron was most likely the result of hydrogen produced by the radiolysis of water. 2) Commensurate with the iron reduction, there was an oxidation of uranium and multivalent fission products, resulting in their transport out of the reactor zone. 3) Approximately 10 percent of the uranium and various proportions of these fission products were removed and redeposited in rocks within a few meters of the reactor zones. 4) The calculated radiation doses from alpha radiation and the inferred hydrogen production suggest an effective radiation yield of 0.06 molecules of hydrogen per 100 eV of energy imparted to the fluid phase. Considering radiation from both alpha and beta sources, the G value for hydrogen production is reduced to 0.01 to 0.002 molecules H 2 /100 eV. (author)

History and perspectives of medical research at the Albert Schweitzer Hospital in Lambaréné, Gabon

NARCIS (Netherlands)

Ramharter, Michael; Adegnika, Ayola A.; Agnandji, Selidji T.; Matsiegui, Pierre Blaise; Grobusch, Martin P.; Winkler, Stefan; Graninger, Wolfgang; Krishna, Sanjeev; Yazdanbakhsh, Maria; Mordmüller, Benjamin; Lell, Bertrand; Missinou, Michel A.; Mavoungou, Elie; Issifou, Saadou; Kremsner, Peter G.

2007-01-01

In 1913 Albert Schweitzer founded one of the first modern hospitals in Africa dedicated to the health of the local population. The Albert Schweitzer Hospital is located in Lambaréné, a small town in Gabon. In 1981 a research department--the Medical Research Unit--was established with the aim to

Clinical Ethics in Gabon: The Spectrum of Clinical Ethical Issues Based on Findings from In-Depth Interviews at Three Public Hospitals.

Science.gov (United States)

Sippel, Daniel; Marckmann, Georg; Ndzie Atangana, Etienne; Strech, Daniel

2015-01-01

Unlike issues in biomedical research ethics, ethical challenges arising in daily clinical care in Sub-Saharan African countries have not yet been studied in a systematic manner. However this has to be seen as a distinct entity as we argue in this paper. Our aim was to give an overview of the spectrum of clinical ethical issues and to understand what influences clinical ethics in the Sub-Saharan country of Gabon. In-depth interviews with 18 health care professionals were conducted at three hospital sites in Gabon. Interview transcripts were analyzed using a grounded theory approach (open and axial coding), giving a qualitative spectrum of categories for clinical ethical issues. Validity was checked at a meeting with study participants and other health care experts in Gabon after analysis of the data. Twelve main categories (with 28 further-specified subcategories) for clinical ethical issues were identified and grouped under three core categories: A) micro level: "confidentiality and information", "interpersonal, relational and behavioral issues", "psychological strain of individuals", and "scarce resources"; B) meso level: "structural issues of medical institutions", "issues with private clinics", "challenges connected to the family", and "issues of education, training and competence"; and C) macro level: "influence of society, culture, religion and superstition", "applicability of western medicine", "structural issues on the political level", and "legal issues". Interviewees reported a broad spectrum of clinical ethical issues that go beyond challenges related to scarce financial and human resources. Specific socio-cultural, historical and educational backgrounds also played an important role. In fact these influences are central to an understanding of clinical ethics in the studied local context. Further research in the region is necessary to put our study into perspective. As many participants reported a lack of awareness of ethical issues amongst other health

Cerebro-meningeal infections in HIV-infected patients: a study of 116 cases in Libreville, Gabon.

Science.gov (United States)

Ondounda, Magloire; Ilozue, Chinenye; Magne, Caroline

2016-06-01

Cerebro-meningeal pathology is common in human immunodeficiency virus (HIV) infection and the aetiology is often difficult to ascertain with certainty. To describe the major suspected and identified causes of meningeal or encephalitic syndromes in HIV infection in Libreville, Gabon. A descriptive study using clinical records of patients hospitalised in the Department of Medicine in the Military Hospital of Libreville (Gabon) between January 2006 and May 2010. Clinical features were evaluated using multivariable logistic regression to evaluate association with the outcome of a clinical improvement or death. The most frequent neurological symptoms were reduced level of consciousness (54.3%), headache (55.2%), motor deficit (38.7%), and convulsions (36.2%). Cerebral toxoplasmosis represented 64.7% of diagnoses, followed by cryptococcal neuromeningitis in 12.9% of cases. Tuberculoma was diagnosed in 4 cases and lymphoma in 2 cases. In 9.5% of cases, no aetiology was determined. Toxoplasmosis treatment led to clinical improvement in 69.3% of cases with suspected cerebral toxoplasmosis. Overall mortality was 39.7%. The diagnosis of neurological conditions in HIV positive patients is difficult, particularly in a low-resource setting. A trial of treatment for toxoplasmosis should be initiated first line with all signs of neurological pathology in a patient infected with HIV.

Situation Report--Bahrain, Central African Republic, Gabon, Iraq, Jordan, Kuwait, Lesotho, Libya, Saudi Arabia, Swaziland, Syria, Yemen Arab Republic.

Science.gov (United States)

International Planned Parenthood Federation, London (England).

Data relating to population and family planning in twelve foreign countries are presented in these situation reports. Countries included are Bahrain, Central African Republic, Gabon, Iraq, Jordan, Kuwait, Lesotho, Libya, Saudi Arabia, Swaziland, Syria, and Yemen Arab Republic. Information is provided, where appropriate and available, under two…

Effectiveness of quinine monotherapy for the treatment of Plasmodium falciparum infection in pregnant women in Lambaréné, Gabon

NARCIS (Netherlands)

Adegnika, Ayôla A.; Breitling, Lutz Ph; Agnandji, Selidji T.; Chai, Sanders K.; Schütte, Daniela; Oyakhirome, Sunny; Schwarz, Norbert G.; Grobusch, Martin P.; Missinou, Michel A.; Ramharter, Michael; Issifou, Saadou; Kremsner, Peter G.

2005-01-01

Pregnant women participating in a longitudinal immuno-epidemiologic survey in Lambaréné, Gabon, and presenting with Plasmodium falciparum parasitemia at monthly blood smear examinations were offered treatment with oral 7-day quinine monotherapy according to national health guidelines. A total of 50

Évaluation des politiques publiques avec la méthode d’appariement : le cas des parcs naturels régionaux en Auvergne et Rhône-Alpes

Directory of Open Access Journals (Sweden)

CREMER-SCHULTE, Dominik

2014-07-01

Full Text Available Outils de politique territoriale, les parcs naturels régionaux ont été créés pour protéger le patrimoine naturel et culturel et pour valoriser ces ressources endogènes dans un objectif de développement local et régional. Mais comment évaluer leur contribution au développement socio-économique des territoires concernés ? Les auteurs de cet article ont utilisé la méthode d’appariement comme outil d’évaluation des politiques de sept parcs en Auvergne et Rhône-Alpes, pour étudier leurs effets sur l’économie locale, en particulier par rapport au tourisme et à l’emploi local.

Petroleum and natural gas economy in Arab Countries, in Congo, Ethiopia, Gabon and Iran

International Nuclear Information System (INIS)

Anon.

1993-01-01

This paper gives informations on petroleum and natural gas industry, petroleum market and prices, trade and contracts, prospection and investments: Portugal has retained the candidature of ten foreign companies for the introduction of natural gas in 1996 and the first enhanced recovery contract will relate to Rhourde El Baguel natural gas field (Algeria). New contracts have been signed for exploration or development of petroleum or natural gas fields in Gabon, Ethiopia and Libya. Iraq has restarted its petroleum exports and Iranian production has diminished

Clinical Ethics in Gabon: The Spectrum of Clinical Ethical Issues Based on Findings from In-Depth Interviews at Three Public Hospitals

Science.gov (United States)

Sippel, Daniel; Marckmann, Georg; Ndzie Atangana, Etienne; Strech, Daniel

2015-01-01

Introduction Unlike issues in biomedical research ethics, ethical challenges arising in daily clinical care in Sub-Saharan African countries have not yet been studied in a systematic manner. However this has to be seen as a distinct entity as we argue in this paper. Our aim was to give an overview of the spectrum of clinical ethical issues and to understand what influences clinical ethics in the Sub-Saharan country of Gabon. Materials and Methods In-depth interviews with 18 health care professionals were conducted at three hospital sites in Gabon. Interview transcripts were analyzed using a grounded theory approach (open and axial coding), giving a qualitative spectrum of categories for clinical ethical issues. Validity was checked at a meeting with study participants and other health care experts in Gabon after analysis of the data. Results Twelve main categories (with 28 further-specified subcategories) for clinical ethical issues were identified and grouped under three core categories: A) micro level: “confidentiality and information”, “interpersonal, relational and behavioral issues”, “psychological strain of individuals”, and “scarce resources”; B) meso level: “structural issues of medical institutions”, “issues with private clinics”, “challenges connected to the family”, and “issues of education, training and competence”; and C) macro level: “influence of society, culture, religion and superstition”, “applicability of western medicine”, “structural issues on the political level”, and “legal issues”. Discussion Interviewees reported a broad spectrum of clinical ethical issues that go beyond challenges related to scarce financial and human resources. Specific socio-cultural, historical and educational backgrounds also played an important role. In fact these influences are central to an understanding of clinical ethics in the studied local context. Further research in the region is necessary to put our study into

Dévalaison et survie d'alevins de saumon atlantique (Salmo salar L. en milieu semi-naturel contrôlé

Directory of Open Access Journals (Sweden)

BEALL E.

1983-04-01

Full Text Available Dans un chenal artificiel expérimental, des œufs de saumon atlantique (Salmo salar L. ont été pondus naturellement ou ont été enfouis au stade embryonné. A la fin de la résorption de la vésicule, une fraction importante des alevins survivants dévale de la zone de frayère. La dévalaison semble stimulée par des baisses de niveau ou des hausses de température et ralentie en période de pleine lune. D'autres facteurs pouvant être responsables de cette dévalaison sont discutés. La survie jusqu'à la collecte de tous les alevins est estimée à 74 p. 100 pour les sujets issus de la reproduction naturelle et est égale à 80 p. 100 pour ceux issus d'œufs introduits dans le gravier au stade embryonné. Des comparaisons entre ces résultats et ceux obtenus dans d'autres chenaux de fraie ou en milieu naturel montrent la validité de cette méthode pour la production d'alevins de saumon atlantique destinés au repeuplement.

Hepatitis C virus prevalence and genetic diversity among pregnant women in Gabon, central Africa

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Mahé Antoine

2008-06-01

Full Text Available Abstract Background Hepatitis C virus (HCV infection is a major global public health problem in both developed and developing countries. The prevalence and genetic diversity of HCV in pregnant women in Gabon, central Africa, is not known. We therefore evaluated the prevalence and the circulating genotypes of HCV in a large population cohort of pregnant women. Methods Blood samples (947 were collected from pregnant women in the five main cities of the country. The prevalence was evaluated by two ELISA tests, and the circulating genotypes were characterized by sequencing and phylogenetic analysis. Results Twenty pregnant women (2.1% were infected with HCV. The seroprevalence differed significantly by region (p = 0.004 and increased significantly with age (p = 0.05, being 1.3% at 14–20 years, 1.1% at 21–25 years, 1.9% at 26–30 years, 4.1% at 31–35 years and 6.0% at > 35 years. Sequencing in the 5'-UTR and NS5B regions showed that the circulating strains belonged to genotypes 4 (4e and 4c. Conclusion We found that the HCV seroprevalence in pregnant women in Gabon is almost as high as that in other African countries and increases with age. Furthermore, only genotype 4 (4e and 4c was found. More extensive studies aiming to evaluate the prevalence and heterogeneity of HCV genotypes circulating in the general population of the country are needed.

Uraniferous concentrations in the Francevillian of Gabon: their association with fossil hydrocarbon-bearing ore deposits of the lower Proterozoic

International Nuclear Information System (INIS)

Gauthier-Lafaye, Francois; Weber, Francis

1981-01-01

The Francevillian U deposits of Gabon are located in one of the oldest non metamorphic sedimentary series of the Lower Proterozoic 2150 M.Y. old. The uraniferous mineralization 2050 M.Y. old is strongly related to organic matter concentrated in oil-bearing structures after migration. No geological event remobilized the mineralizations since their settling [fr

Deep-reaching fracture zones in the crystalline basement surrounding the West Congo System and their control of mineralization in Angola and Gabon

NARCIS (Netherlands)

Boorder, H. de

1982-01-01

A framework of major, deep-reaching fracture zones in western Central Africa is inferred from airborne magnetometric and surface geological observations in Central Angola and Gabon. A correlation is proposed between these observations and the continental negative Bouguer anomaly. The minimum

Les conditions du développement des banques d’actifs naturels en FranceAnalyse du régime institutionnel de la première Réserve d’Actifs Naturels française What conditions to enlarge habitat banks in France ?Institutional regime analysis of the first French habitat bank

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Fanny Chabran

2012-05-01

Full Text Available Les marchés d’actifs naturels sont encore rares en Europe, mais les premières expériences permettent de s’interroger sur le dispositif mis en place au regard de l’objectif de conservation des milieux naturels. Nous avons analysé la première expérience française de banque d’actifs naturels, mise en place dans le cadre des dispositifs de compensation des impacts écologiques des aménagements. Ce projet repose sur d’importants travaux de réhabilitation écologique pour faire retourner un verger intensif vers une végétation herbacée méditerranéenne. Les résultats en écologie de la restauration sont encourageants. En revanche, ils sont encore à évaluer dans les champs politiques ou économiques. Une analyse du régime institutionnel régissant les usages du site montre que l’action mercantile entreprise, tout autant que l’incomplétude du dispositif public de régulation, ne confèrent pas d’assurances définitives quant à la pérennité du dispositif de conservation environnementale du site.Habitat banks are not numerous in Europe but the first experiments allow wondering about the device in relation to the conservation purpose. We analyzed the first French experience of habitat banking introduced in the mitigation regulatory framework. This project is based on important ecological rehabilitation of an intensive orchard to Mediterranean herbaceous vegetation. Results in ecological restoration are good ; however, they are still assessing in the political and economic fields. An analysis of the institutional regime of site uses shows that the mercantile action as well as the public device incompleteness does not provide insurance about the site’s conservation sustainability.

Molecular characterization of complete genome of a canine distemper virus associated with fatal infection in dogs in Gabon, Central Africa.

Science.gov (United States)

Maganga, Gael D; Labouba, Ingrid; Ngoubangoye, Barthélémy; Nkili-Meyong, Andriniaina A; Obame Ondo, Daniel; Leroy, Eric M; Berthet, Nicolas

2018-03-02

Canine distemper (CD) is the most deadly disease in dogs with mortality rates reaching 50%. The pathological agent, the CD virus (CDV), generally causes a severe systemic disease, although the nervous form can coexist with the acute catarrhal form in the same individual. In this study, we describe an outbreak of 18 cases of CD that occurred in 2015 in a German Shepherd dog population in northwestern Gabon. In addition, we determined the sequence of the CDV genotype associated with this fatal distemper infection in Gabon and compared it with other published CDV sequences. The CDV was detected using RT-PCR on cDNA from RNA of harvested brains and other organs. The identification was confirmed by sequencing amplicons. Moreover, we obtained the whole genome sequence using high-throughput sequencing. Phylogenetic analysis revealed that Gabonese CDV strain clustered with European strains belonging to the Europe genotype. This study provided the first molecular detection of the CDV strain associated with this fatal distemper infection in Central Africa region. Copyright © 2018 Elsevier B.V. All rights reserved.

Potential effects of prescribed savannah burning on the diet selection of forest buffalo (Syncerus caffer nanus) in Lopé National Park, Gabon

NARCIS (Netherlands)

Hoek, van der Y.; Lustenhouwer, I.; Jeffery, K.J.; Hooft, van W.F.

2013-01-01

Seasonality and management are factors that may affect the diet selection of the forest buffalo (Syncerus caffer nanus). Fire is considered a major driving force in savannah systems and prescribed burning is a commonly applied conservation tool in protected areas such as Lopé National Park, Gabon.

Epidemiology and population structure of Staphylococcus aureus in various population groups from a rural and semi urban area in Gabon, Central Africa.

Science.gov (United States)

Ateba Ngoa, Ulysse; Schaumburg, Frieder; Adegnika, Ayola Akim; Kösters, Katrin; Möller, Tina; Fernandes, Jose Francisco; Alabi, Abraham; Issifou, Saadou; Becker, Karsten; Grobusch, Martin Peter; Kremsner, Peter Gottfried; Lell, Bertrand

2012-10-01

Little data is available on the epidemiology of Staphylococcus aureus in Africa. In the present study we aim at characterizing the population structure of S. aureus in healthy subjects from a rural and a semi-urban area in Lambaréné, Gabon as well as in hospital staff and inpatients. In total, 500 subjects were screened for S. aureus colonization of the nares, axillae and inguinal region. Overall, 146 (29%) were positive. We found 46 different spa types. The most frequent spa types were t084 (35%) and the agr II was the most prevalent subtype of the accessory gene regulator (56%, n=82). Five isolates (3%) were methicillin resistant S. aureus (MRSA). Carriage rates of S. aureus in Gabon are comparable to developed countries. MRSA is for the first time described and could pose a significant health threat in this region with limited access to microbiological laboratory facilities and to adequate antimicrobial agents. Copyright © 2012 Elsevier B.V. All rights reserved.

Using genetic profiles of African forest elephants to infer population structure, movements, and habitat use in a conservation and development landscape in Gabon

NARCIS (Netherlands)

Eggert, L. S.; Buij, R.; Lee, M. E.; Campbell, P.; Dallmeier, F.; Fleischer, R. C.; Alonso, A.; Maldonado, J. E.

Conservation of wide-ranging species, such as the African forest elephant (Loxodonta cyclotis), depends on fully protected areas and multiple-use areas (MUA) that provide habitat connectivity. In the Gamba Complex of Protected Areas in Gabon, which includes 2 national parks separated by a MUA

using genetic profiles of african forest elephants to infer population structure, movements, and habitat use in a conservation and development landscape in gabon

NARCIS (Netherlands)

Eggert, L.S.; Buij, R.; Lee, M.E.; Campbell, P.; Dallmeier, F.; Fleischer, R.C.; Alonso, A.; Maldonado, J.

2014-01-01

Conservation of wide-ranging species, such as the African forest elephant (Loxodonta cyclotis), depends on fully protected areas and multiple-use areas (MUA) that provide habitat connectivity. In the Gamba Complex of Protected Areas in Gabon, which includes 2 national parks separated by a MUA

Petroleum and natural gas economy in Arab countries and in Iran, Angola, Gabon, Nigeria and Chad

International Nuclear Information System (INIS)

1993-01-01

This paper describes briefly main informations on petroleum prices and market trends, trade and contracts, petroleum exploration in Algeria, Chad, Gabon, Libya, Saudi Arabia and Tunisia, new crude oil discoveries in Nigeria. In Iran, a joint venture will be constituted with Gaz de France for natural gas export in Europe. In Egypt, National Bank has financed for the first time a Liquefied Petroleum Gas plant. Statistics on petroleum and natural gas reserves, production, seismic surveys, drilling operations and refining units are also given. 9 tabs

Decrease of microscopic Plasmodium falciparum infection prevalence during pregnancy following IPTp-SP implementation in urban cities of Gabon.

Science.gov (United States)

Bouyou-Akotet, M K; Mawili-Mboumba, D P; Kendjo, E; Moutandou Chiesa, S; Tshibola Mbuyi, M L; Tsoumbou-Bakana, G; Zong, J; Ambounda, N; Kombila, M

2016-06-01

Six years after the implementation of intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) in Gabon, its impact on placental malaria and pregnancy outcomes remains unknown. Age, gestational data, use of IPTp-SP and birth weight were recorded during a hospital-based cross-sectional survey performed in 2011 in 387 women at the end of pregnancy. Malaria prevalence was 6.7 and 5.3% in peripheral and placental blood respectively. Overall, 59.0% women took at least two IPTp-SP doses which was associated with 50% reduction of Plasmodium; (P.) falciparum infection in primigravidae. Previous malaria treatment was a risk factor for peripheral P. falciparum infection, while uptake of IPTp-SP was associated with reduced parasitaemia. Anaemia prevalence was 38.0%, low birth weight and prematurity rates were 6.0 and 12.0% respectively. Young age was associated with a higher frequency of malaria, anaemia, low birth weight and preterm delivery (pprevalence during pregnancy significantly declined between 2005 and 2011, following IPTp-SP implementation in Gabon. Young women and paucigravidae remain the most susceptible to malaria and associated outcomes. © The Author 2016. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Epidemiology and population structure of Staphylococcus aureus in various population groups from a rural and semi urban area in Gabon, Central Africa

NARCIS (Netherlands)

Ateba Ngoa, Ulysse; Schaumburg, Frieder; Adegnika, Ayola Akim; Kösters, Katrin; Möller, Tina; Fernandes, Jose Francisco; Alabi, Abraham; Issifou, Saadou; Becker, Karsten; Grobusch, Martin Peter; Kremsner, Peter Gottfried; Lell, Bertrand

2012-01-01

Little data is available on the epidemiology of Staphylococcus aureus in Africa. In the present study we aim at characterizing the population structure of S. aureus in healthy subjects from a rural and a semi-urban area in Lambarene, Gabon as well as in hospital staff and inpatients. In total, 500

Recent and future developments at the Regie du gaz naturel

International Nuclear Information System (INIS)

Giroux, J.

1995-01-01

The history of the Quebec Regie du gaz naturel, dating back to 1932, and its role in distributing natural gas in Quebec was described. Among more recent developments construction of a natural gas distribution system on the south shore of Quebec City was discussed. Unlinked mini-systems were built in St-Romuald and Levis. Gas was delivered by truck until an underwater crossing was completed. The federal-provincial infrastructures program was also summarized. The most important ruling by the Regie was the D-94-19 decision on GMi's supply policy and the concept of u mbrella buy-sell . Although this policy was originally approved by the Regie, after consideration of all factors, it was decided that this system was not in line with the deregulation trend and that buyers and sellers could do without GMi's intrusion in their contractual agreements. Issues to be addressed by the Regie in the coming months included transportation service, unbundling, cost allocation and rate of return adjustments mechanism in regards to the recent National Energy Board (NEB) decision on the subject, and separation of (LDC) distribution activities from LDC sales

Cartographie de la vulnérabilité globale d'une population citadine face aux risques naturels: le cas de Manizales

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Anne-Catherine CHARDON

1994-12-01

Full Text Available Cette méthode cartographique sert à évaluer la vulnérabilité de la population d’une grande ville andine (Manizales, Colombie, exposée aux séismes et à de fréquents glissements de terrain. Sept facteurs naturels et huit facteurs socio-économiques, mesurés à l’échelle du quartier, sont intégrés, avec d’autre facteurs géographiques, dans une carte de vulnérabilité globale.

Etude, consolidation et protection de caoutchouc naturel

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François Duboisset

2010-11-01

Full Text Available Un exemplaire d’un fauteuil MAA de George Nelson produit en 1958 a été restauré dans l’atelier mobilier du département des restaurateurs de l’Institut National du Patrimoine. Ce fauteuil est un exemple très représentatif du modernisme américain par sa simplicité des formes et  son esthétisme recherché. Les articulations du dossier en caoutchouc naturel sont fortement fissurées suite à une exposition à la lumière couplée à l’utilisation du fauteuil. Un protocole technico-scientifique a permis d’établir une méthode de comblement réversible des fissures à l’aide d’éthylène vinyle acétate, résine thermoplastique souple. Ce procédé a été appliqué sur les caoutchoucs du fauteuil afin de redonner une cohérence mécanique aux pièces.A MAA chair of George Nelson dating of 1958 was restored in the workshop of furniture in the department of restoration at the National institute of heritage. This chair is a very representative example of American modernism by its simplicity of form and its refine style. The articulation of the back is composed with natural rubber. These are highly cracked due to exposure to light and coupled with the use of the chair. A protocol on scientific-technical established a reversible method of filling cracks with ethylene vinyl acetate with anti-oxidant, soft thermoplastic resin. This method has been applied on the rubber chair to give mechanical coherence to the parts and to the chair.

Case-book of all decisions taken by the Regie du gaz naturel from April 1, 1995 - March 31, 1996

International Nuclear Information System (INIS)

Precourt, L.; L'Heureux, L.

1996-01-01

All decisions taken by the Regie du gaz naturel du Quebec during the period of April 1, 1995 to March 31, 1996 were presented. The case-book includes all legal decisions concerning the supply, transmission and storage of natural gas delivered or intended for delivery by pipeline distribution in the Province of Quebec. The text of the Act, amendments and revisions to the Act, and summaries of Board decisions are provided in French and English. Also included are a number of indexes for ease of reference and a glossary of relevant terms

Uranium mining as a factor in Gabon's economic and social development

International Nuclear Information System (INIS)

Tonda, P.; Moine, J.

1989-01-01

The long history of the Compagnie des mines d'Uranium de Franceville (Comuf) is linked to the history of the young Gabonese Republic. The psychological and social role of Comuf in the development of Gabon exceeds its strictly economic impact, which in itself is far from negligible. Over the last thirty years Comuf has produced and delivered almost 20 000 tonnes U. Its proven reserves ensure that its activities can continue at the present level for at least 20 years and may permit it to remain open for over half a century. This means it can continue to work, as it always has done, for the long term: an essential condition for it to make a worthwhile contribution to the development of the country. This paper concentrates on the impact of Comuf's activities on its environment, its contribution to the local communities and its role in the country's economy. (author)

Etude des possibilités de valorisation agricole des écumes et de la bagasse de canne à sucre de SOSUHO (Gabon

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Makita-Ngadi, J.

1993-01-01

Full Text Available Study on the possibilities of agricultural valorisation of sugarcane scums and bagasse of SOSUHO (Gabon. As a first step towards the general use of organic fertilizers in improving poor agricultural yields of soils in the province of Haut-Ogooue, in Gabon, we studied germination and growth of seven different types of plants (maize, Zea mays L. var. 60 ; rice Oryza sativa Var. 1345 ; cacao-tree, Theobroma cacao Var. Forastero ; gombo, Hibiscus esculantus Clenson Spineless var ; culin, Cucurbita pepo Basma var ; aubergine, Solanum melongena, Asgrow var ; soya-bean, Glycine max tropical var. on two six months old sugar cane residues. These residues, froth and bagasse were used by hemselves or mixed with earth or sand. By comparison with commercial compost, we found that froth and bagasse do not inhibit the germination of the seeds studied. However, we found that the growth of all species studied was better in froth than in bagasse. The results of chemical analysis carried out on these residues can explain partially the good growth observed in froth themselves or mixed with earth.

Malaria transmission and insecticide resistance of Anopheles gambiae in Libreville and Port-Gentil, Gabon

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Kombila Maryvonne

2010-11-01

Full Text Available Abstract Background Urban malaria is a major health priority for civilian and militaries populations. A preliminary entomologic study has been conducted in 2006-2007, in the French military camps of the two mains towns of Gabon: Libreville and Port-Gentil. The aim was to assess the malaria transmission risk for troops. Methods Mosquitoes sampled by human landing collection were identified morphologically and by molecular methods. The Plasmodium falciparum circumsporozoïte (CSP indexes were measured by ELISA, and the entomological inoculation rates (EIR were calculated for both areas. Molecular assessments of pyrethroid knock down (kdr resistance and of insensitive acetylcholinesterase resistance were conducted. Results In Libreville, Anopheles gambiae s.s. S form was the only specie of the An. gambiae complex present and was responsible of 9.4 bites per person per night. The circumsporozoïte index was 0.15% and the entomological inoculation rate estimated to be 1.23 infective bites during the four months period. In Port-Gentil, Anopheles melas (75.5% of catches and An. gambiae s.s. S form (24.5% were responsible of 58.7 bites per person per night. The CSP indexes were of 1.67% for An. gambiae s.s and 0.28% for An. melas and the EIRs were respectively of 1.8 infective bites per week and of 0.8 infective bites per week. Both kdr-w and kdr-e mutations in An. gambiae S form were found in Libreville and in Port-Gentil. Insensitive acetylcholinesterase has been detected for the first time in Gabon in Libreville. Conclusion Malaria transmission exists in both town, but with high difference in the level of risk. The co-occurrence of molecular resistances to the main families of insecticide has implications for the effectiveness of the current vector control programmes that are based on pyrethroid-impregnated bed nets.

Phylogeography, risk factors and genetic history of hepatitis C virus in Gabon, central Africa.

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Richard Njouom

Full Text Available BACKGROUND: The epidemiological and molecular characteristics of hepatitis C virus (HCV infection in the general population have been poorly investigated in Africa. The aim of this study was to determine the prevalence, genotype distribution and epidemic history of HCV in the Gabonese general population. METHODS/PRINCIPAL FINDINGS: A total of 4042 sera collected from adults in 220 villages in all nine administrative areas of the country were screened for antibodies to HCV. HCV NS5B region sequencing was performed for molecular characterization and population genetic analyses. Of 4042 tested sera, 455 (11.2% were positive. The seroprevalence of HCV varied significantly by administrative area, with the highest rate in Ogooué-Lolo province (20.4% and the lowest in Ogooué-Maritine province (3.7%. History of parenteral injections, past hospital admission and age over 55 years were independent risk factors for HCV infection (p<0.0001. Phylogenetic analyses showed that 91.9% of the strains were genotype 4 (HCV-4, 5.7% genotype 1 and 2.2% genotype 2. HCV-4 strains were highly heterogeneous, with more than eight subtypes; subtype 4e predominated (57.3%. Coalescence analyses indicated that subtype 4e was the oldest, with an estimated most recent common ancestor of 1702 [95% CI, 1418-1884]. The epidemic profile indicated that it spread exponentially during the first part of the 20th century, probably by iatrogenic transmission. CONCLUSIONS/SIGNIFICANCE: These results confirm the endemicity of HCV subtype 4e in Gabon and show that its spread is due to a cohort effect, with previous, possibly iatrogenic events. More extensive epidemiological studies are needed to better characterize the route of transmission and the dissemination of HCV in Gabon.

Camera traps to study the forest elephant's (Loxodonta cyclotis) response to chilli pepper repellent devices in Gamba, Gabon

OpenAIRE

Steeve Ngama; Lisa Korte; Mireille Johnson; Cédric Vermeulen; Jérôme Bindelle

2018-01-01

In Central Africa, Gabon is a forested country with a rich biodiversity where conflict between wild animals and humans is common and causes innumerable damage to crops. The worst crop raiders are elephants, which can destroy an entire crop in a single night. These raids threaten people's livelihoods as well as elephants because angry farmers often retaliate with killing campaigns against crop raiding elephants. To keep elephants out of farms the use of chilli pepper is recommended as a non-le...

Usage des TIC, qualité de vie, bien-être et santé psychologique au travail: une étude réalisée au ministère de l'économie numérique, de la communication et de la poste au Gabon

OpenAIRE

Medzo-M 'engone , Joseph

2017-01-01

The use of technology in public organizations in some African countries such as Gabon reflects a desire to improve quality of service for users and to make work processes more effective. Literature presents evidences that technological innovations in Western companies bring some advantages on both organizational and socio-professional levels, but also numerous negative impacts. The impact of technological change on occupational and organizational psychology in Public Administration in Gabon h...

Preliminary description of the diet of Hippopotamus amphibius L. in Loango National Park (Gabon

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Michez, A.

2013-01-01

Full Text Available Due to the paucity of suitable habitat, hippos are very rare in the Congo Bassin. Compared to East-African populations, Central African populations of hippos have been less studied. Information found in the literature regarding the animal's basic ecology is limited. This study focuses on the description of the diet of an isolated hippo population in Loango National Park (Gabon, comparing faecal analysis with a reference collection of herbaceous species from the savannas. The effectiveness of using faecal analysis versus using the floristic description of hippos' pastures was demonstrated. The most frequent herbaceous species identified in faeces samples were Paspalum vaginatum, Axonopus compressus, Stenotaphrum secundatum (Poaceae and Desmodium triflorum (Fabaceae. The voluntary consumption of a dicotyledonous species (Desmodium triflorum is novel for this species.

Petroleum and natural gas economy in Arab countries and in Angola, Gabon, Iran, Nigeria

International Nuclear Information System (INIS)

Anon.

1993-01-01

This paper gives informations about petroleum and natural gas industry, petroleum market and prices, trade and contracts, prospection and production. In Saudi Arabia, the debate about the price reduction of butane used to produce methyl tertiary butyl ether (MTBE) is responsible of the cancellation of joint venture project between Mobil and Arabian Chemical Investment Corp. In Algeria, Japan brings its support to the development of Liquefied Petroleum Gases industry and has signed two exports contracts. New petroleum discoveries have been made in Oman, near Suneinah and in Egypt near Belayim offshore oil field. Petroleum production has reached 3.6 millions barrels per day in Iran, 0.35 millions barrels per day in Gabon and 0.177 millions barrels per day in Nigeria

Spatial planning for a green economy: National-level hydrologic ecosystem services priority areas for Gabon.

Science.gov (United States)

Goldstein, Joshua Howard; Tallis, Heather; Cole, Aaron; Schill, Steven; Martin, Erik; Heiner, Michael; Paiz, Marie-Claire; Aldous, Allison; Apse, Colin; Nickel, Barry

2017-01-01

Rapidly developing countries contain both the bulk of intact natural areas and biodiversity, and the greatest untapped natural resource stocks, placing them at the forefront of "green" economic development opportunities. However, most lack scientific tools to create development plans that account for biodiversity and ecosystem services, diminishing the real potential to be sustainable. Existing methods focus on biodiversity and carbon priority areas across large geographies (e.g., countries, states/provinces), leaving out essential services associated with water supplies, among others. These hydrologic ecosystem services (HES) are especially absent from methods applied at large geographies and in data-limited contexts. Here, we present a novel, spatially explicit, and relatively simple methodology to identify countrywide HES priority areas. We applied our methodology to the Gabonese Republic, a country undergoing a major economic transformation under a governmental commitment to balance conservation and development goals. We present the first national-scale maps of HES priority areas across Gabon for erosion control, nutrient retention, and groundwater recharge. Priority sub-watersheds covered 44% of the country's extent. Only 3% of the country was identified as a priority area for all HES simultaneously, highlighting the need to conserve different areas for each different hydrologic service. While spatial tradeoffs occur amongst HES, we identified synergies with two other conservation values, given that 66% of HES priority areas intersect regions of above average area-weighted (by sub-watersheds) total forest carbon stocks and 38% intersect with terrestrial national parks. Considering implications for development, we identified HES priority areas overlapping current or proposed major roads, forestry concessions, and active mining concessions, highlighting the need for proactive planning for avoidance areas and compensatory offsets to mitigate potential conflicts

Spatial planning for a green economy: National-level hydrologic ecosystem services priority areas for Gabon.

Directory of Open Access Journals (Sweden)

Joshua Howard Goldstein

Full Text Available Rapidly developing countries contain both the bulk of intact natural areas and biodiversity, and the greatest untapped natural resource stocks, placing them at the forefront of "green" economic development opportunities. However, most lack scientific tools to create development plans that account for biodiversity and ecosystem services, diminishing the real potential to be sustainable. Existing methods focus on biodiversity and carbon priority areas across large geographies (e.g., countries, states/provinces, leaving out essential services associated with water supplies, among others. These hydrologic ecosystem services (HES are especially absent from methods applied at large geographies and in data-limited contexts. Here, we present a novel, spatially explicit, and relatively simple methodology to identify countrywide HES priority areas. We applied our methodology to the Gabonese Republic, a country undergoing a major economic transformation under a governmental commitment to balance conservation and development goals. We present the first national-scale maps of HES priority areas across Gabon for erosion control, nutrient retention, and groundwater recharge. Priority sub-watersheds covered 44% of the country's extent. Only 3% of the country was identified as a priority area for all HES simultaneously, highlighting the need to conserve different areas for each different hydrologic service. While spatial tradeoffs occur amongst HES, we identified synergies with two other conservation values, given that 66% of HES priority areas intersect regions of above average area-weighted (by sub-watersheds total forest carbon stocks and 38% intersect with terrestrial national parks. Considering implications for development, we identified HES priority areas overlapping current or proposed major roads, forestry concessions, and active mining concessions, highlighting the need for proactive planning for avoidance areas and compensatory offsets to mitigate

Formation and evolution of aerosols in filtered air and in natural air. Effect of radioactivity; Formation et evolution des aerosols dans l'air filtre et dans l'air naturel action de la radioactivite

Energy Technology Data Exchange (ETDEWEB)

Madelaine, G J [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-06-01

Results are presented concerning the formation, the evolution, the coagulation and the electrical charge of aerosols which form in natural filtered air containing only gaseous impurities, under the influence of solar light (photolysis) and of radioactive disintegrations (radiolysis). The modifications brought about in the aerosol by an increase in the sulphur dioxide content and in the natural radioactive gas content are studied. The work is then repeated with non-filtered natural atmospheric air. A comparison is also made of the behaviour of non-radioactive and radioactive particles (active thoron deposit). In conclusion, the possible consequences of these phenomena on the origin and the size distribution of particles occurring in the atmosphere is considered. (author) [French] On expose les resultats obtenus sur la formation, l'evolution, la coagulation et la charge electrique des aerosols qui se forment dans l'air naturel filtre, ne contenant que des impuretes gazeuses, sous l'influence de la lumiere solaire (photolyse) et des desintegrations radioactives (radiolyse). On examine les modifications apportees a l'aerosol forme par l'augmentation de la teneur de l'air en anhydride sulfureux et en gaz radioactif naturel. Cette etude est ensuite reprise mais avec de l'air naturel atmospherique non filtre. On compare egalement le comportement des particules non radioactives et radioactives (depot actif du thoron). En conclusion, on examine les consequences que peuvent avoir ces phenomenes sur l'origine et la granulometrie des particules contenues dans l'atmosphere. (auteur)

La formation de l'oxyde azotique dans les flammes de diffusion de gaz naturel Nitrogen. Oxyde Formation in Natural-Gas Diffusion Flams

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Portrait L. M.

2006-11-01

Full Text Available L'étude de la formation de l'oxyde azotique dans des flammes de diffusion de ga naturel est effectuée depuis deux ans sur le four expérimental du Groupe d'Etude des Flammes de Gaz Naturel situé à Toulouse. Un certain nombre de variables ont été explorées : type de flamme, excès d'air, préchauffage de l'air, teneur en oxygène du comburant, puissance calorifique, et débit de moment cinétique. L'étude a mis en évidence une corrélation générale, quelle que soit la variable considérée, entre la quantité maximale d'oxyde d'azote formé et la température maximale de la flamme. Certains des résultats précédents ont été exploités à l'Institut Français du Pétrole, en vue d'établir une équation de vitesse de formation de NO applicable aux flammes axiales de diffusion de gaz naturel. Les calculs s'appuient sur les connaissances obtenues lors de l'étude cinétique de formation de NO effectuée au Laboratoire d'Aérothermique Fondamentale. Les résultats du calcul théorique confirment ceux de l'étude sur le four expérimental en ce qui concerne l'influence prépondérante de la température sur la formation de l'oxyde azotique. Par ailleurs, le calcul théorique retrouve bien les résultats obtenus lors de l'étude fondamentale, selon lesquels la cinétique de formation de NO évolue le long de la flamme depuis le front de flamme jusqu'aux gaz brûlés. La généralisation à un grand nombre de flammes de l'équation cinétique expérimentale obtenue nécessite maintenant de prendre en compte certains phénomènes de diffusion négligés jusqu'à présent. Research on the formation of nitrogen oxide in natural-gas diffusion flammes has been going on for two years in the experimental furnace of the Groupe d'Etude des Flammes de Gaz Naturel located in Toulouse. Different variables have been investigoted such as type of flamme, air excess, air preheating, oxygen content in the oxidant, heating power and kinetic moment output

From foreign to national: a review of the status of the French language in Gabon

Directory of Open Access Journals (Sweden)

H.S. Ndinga-Koumba-Binza

2011-06-01

Full Text Available This article provides a review of the various statuses of the French language in Gabon, a French-speaking country in Central Africa. It reveals a process in which different generations of Gabonese people are increasingly learning, and thus conceptualising, French as a second language rather than a foreign language. Furthermore, some are also learning and conceptualising French as a mother tongue or initial language, rather than a second language. This process of reconceptualisation has somehow been encouraged by the language policy of the colonial administration and the language policy since the attainment of independence, the latter being a continuation of the former. The final stage of this process is that the language has been adopted among the local languages within the Gabonese language landscape.

Bat flies (Diptera: Nycteribiidae and Streblidae) infesting cave-dwelling bats in Gabon: diversity, dynamics and potential role in Polychromophilus melanipherus transmission.

Science.gov (United States)

Obame-Nkoghe, Judicaël; Rahola, Nil; Bourgarel, Mathieu; Yangari, Patrick; Prugnolle, Franck; Maganga, Gael Darren; Leroy, Eric-Maurice; Fontenille, Didier; Ayala, Diego; Paupy, Christophe

2016-06-10

Evidence of haemosporidian infections in bats and bat flies has motivated a growing interest in characterizing their transmission cycles. In Gabon (Central Africa), many caves house massive colonies of bats that are known hosts of Polychromophilus Dionisi parasites, presumably transmitted by blood-sucking bat flies. However, the role of bat flies in bat malaria transmission remains under-documented. An entomological survey was carried out in four caves in Gabon to investigate bat fly diversity, infestation rates and host preferences and to determine their role in Polychromophilus parasite transmission. Bat flies were sampled for 2-4 consecutive nights each month from February to April 2011 (Faucon and Zadie caves) and from May 2012 to April 2013 (Kessipoughou and Djibilong caves). Bat flies isolated from the fur of each captured bat were morphologically identified and screened for infection by haemosporidian parasites using primers targeting the mitochondrial cytochrome b gene. Among the 1,154 bats captured and identified as Miniopterus inflatus Thomas (n = 354), Hipposideros caffer Sundevall complex (n = 285), Hipposideros gigas Wagner (n = 317), Rousettus aegyptiacus Geoffroy (n = 157, and Coleura afra Peters (n = 41), 439 (38.0 %) were infested by bat flies. The 1,063 bat flies recovered from bats belonged to five taxa: Nycteribia schmidlii scotti Falcoz, Eucampsipoda africana Theodor, Penicillidia fulvida Bigot, Brachytarsina allaudi Falcoz and Raymondia huberi Frauenfeld group. The mean infestation rate varied significantly according to the bat species (ANOVA, F (4,75) = 13.15, P bat fly species and host bat species was observed. Polychromophilus melanipherus Dionisi was mainly detected in N. s. scotti and P. fulvida and less frequently in E. africana, R. huberi group and B. allaudi bat flies. These results suggest that N. s. scotti and P. fulvida could potentially be involved in P. melanipherus transmission among cave-dwelling bats

Dissolution studies of natural analogues spent fuel and U(VI)-Silicon phases of and oxidative alteration process; Estudios de disolucion de analogos naturales de combustible nuclear irradiado y de fases de U(VI)-Silicio representativas de un proceso de alteracion oxidativa

Energy Technology Data Exchange (ETDEWEB)

Perez Morales, I

2000-07-01

In order to understand the long-term behavior of the nuclear spent fuel in geological repository conditions, we have performed dissolution studies with natural analogues to UO{sub 2} as well as with solid phases representatives of the oxidative alteration pathway of uranium dioxide, as observed in both natural environment and laboratory studies. In all cases, we have studied the influence of the bicarbonate concentration in the dissolution process, as a first approximation to the groundwater composition of a granitic environment, where carbonate is one of the most important complexing agents. As a natural analogue to the nuclear spent fuel some uraninite samples from the Oklo are deposit in Gabon, where chain fission reactions took place 2000 millions years ago, as well as a pitchblende sample from the mine Fe ore deposit, in Salamanca (spain) have been studied. The studies have been performed at 25 and 60 degree centigree and 60 degree centigree, and they have focussed on the determination of both the thermodynamic and the kinetic properties of the different samples studied, using batch and continuous experimental methodologies, respectively. (Author)

Dissolution studies of natural analogues spent fuel and U(VI)-Silicon phases of and oxidative alteration process

International Nuclear Information System (INIS)

Perez Morales, I.

2000-01-01

In order to understand the long-term behavior of the nuclear spent fuel in geological repository conditions, we have performed dissolution studies with natural analogues to UO 2 as well as with solid phases representatives of the oxidative alteration pathway of uranium dioxide, as observed in both natural environment and laboratory studies. In all cases, we have studied the influence of the bicarbonate concentration in the dissolution process, as a first approximation to the groundwater composition of a granitic environment, where carbonate is one of the most important complexing agents. As a natural analogue to the nuclear spent fuel some uraninite samples from the Oklo are deposit in Gabon, where chain fission reactions took place 2000 millions years ago, as well as a pitchblende sample from the mine Fe ore deposit, in Salamanca (spain) have been studied. The studies have been performed at 25 and 60 deg C and 60 deg C, and they have focussed on the determination of both the thermodynamic and the kinetic properties of the different samples studied, using batch and continuous experimental methodologies, respectively. (Author)

Interaction of uranium and organic matter in unaniferous sediments

Energy Technology Data Exchange (ETDEWEB)

Rouzaud, J N; Oberlin, A; Trichet, J

1980-01-01

Conventional transmission electron microscopy (lattice fringes and dark field techniques) was used for determining the structure and microtexture of some Precambrian organic matter. The samples came from Cluff (Saskatchewan, Canada) and Oklo (Gabon) and contain uranium with organo-metallic bonding (uranium was shown to be present by energy dispersive X-ray analysis carried out in the CTEM). Despite their algal origin, these materials show a high oxygen content. This strong degree of oxidation inhibits the parallel molecular orientation usually produced in carbonaceous products as coalification progresses. Progressive heat-treatment to 3000/sup 0/C produces microporous carbon (50 to 100A). It is, however, partially transformed into graphite in a manner similar to anthracites and non-graphitizable carbons heat-treated under pressure (5 kbars). It is favored by pore flattening, due to pressure, which introduces a long-range, preferred orientation parallel to the flattening plane. Conversely, it is partially prevented by cross-linking due to oxygen. Comparison with materials of higher plant origin (e.g. from Arlit, Niger) suggests a possible mechanism of uranium fixation.

Bacteria, colloids and organic carbon in groundwater at the Bangombe site in the Oklo area

International Nuclear Information System (INIS)

Pedersen, K.

1996-02-01

This report describes how microorganisms, colloids and organic matter were sampled from groundwater from six boreholes at the Bangombe site in the Oklo region and subsequently analyzed. For analysis of microorganisms, DNA was extracted from groundwater, amplified and cloned and information available in the ribosomal 16S rRNA gene was used for mapping diversity and distribution of bacteria. Each borehole was dominated by species that did not dominate in any of the other boreholes, a result that probably reflects documented differences in the geochemical environment. Analyses of sampled colloids included SEM and ICP-MS analysis of colloids on membrane and single particle analysis of samples in bottles. The colloid concentration was rather low in these Na-Mg-Ca-HCO 3 type waters. Trace element results show that transition metals and some heavy metals are associated with the colloid phase. Distribution coefficients of trace elements between the water and colloid phases were estimated. For example for uranium, an average of 200 pg/ml was detected in the water, and 40 pg/ml was detected in the colloid phase. A K p value of 2* 10 6 ml/g was calculated, considering (colloid) = 100 ng/ml. Groundwater samples were collected for analysis of the concentration of organic carbon (TOC), humic substances and metals associated with the humic substances. TOC varied in the range 4-14 mg/l in three boreholes, one borehole had a TOC<1.5 mg/l. The metal speciation study indicated that a large fraction, 8-67% of uranium was bound to the humic matter compared to the fractions of Ca and Fe (<0.4% and 0.02-10%, resp.). 60 refs, 8 figs, 16 tabs

Safety and immunogenicity of rVSVΔG-ZEBOV-GP Ebola vaccine in adults and children in Lambaréné, Gabon: A phase I randomised trial

NARCIS (Netherlands)

Agnandji, Selidji T.; Fernandes, José F.; Bache, Emmanuel B.; Obiang Mba, Régis M.; Brosnahan, Jessica S.; Kabwende, Lumeka; Pitzinger, Paul; Staarink, Pieter; Massinga-Loembe, Marguerite; Krähling, Verena; Biedenkopf, Nadine; Fehling, Sarah Katharina; Strecker, Thomas; Clark, David J.; Staines, Henry M.; Hooper, Jay W.; Silvera, Peter; Moorthy, Vasee; Kieny, Marie-Paule; Adegnika, Akim A.; Grobusch, Martin P.; Becker, Stephan; Ramharter, Michael; Mordmüller, Benjamin; Lell, Bertrand; Krishna, Sanjeev; Kremsner, Peter G.

2017-01-01

The rVSVΔG-ZEBOV-GP vaccine prevented Ebola virus disease when used at 2 × 107 plaque-forming units (PFU) in a trial in Guinea. This study provides further safety and immunogenicity data. A randomised, open-label phase I trial in Lambaréné, Gabon, studied 5 single intramuscular vaccine doses of 3 ×

Quality of antiepileptic drugs in sub-Saharan Africa: A study in Gabon, Kenya, and Madagascar.

Science.gov (United States)

Jost, Jeremy; Ratsimbazafy, Voa; Nguyen, Thu Trang; Nguyen, Thuy Linh; Dufat, Hanh; Dugay, Annabelle; Ba, Alassane; Sivadier, Guilhem; Mafilaza, Yattussia; Jousse, Cyril; Traïkia, Mounir; Leremboure, Martin; Auditeau, Emilie; Raharivelo, Adeline; Ngoungou, Edgard; Kariuki, Symon M; Newton, Charles R; Preux, Pierre-Marie

2018-06-12

Epilepsy is a major public health issue in low- and middle-income countries, where the availability and accessibility of quality treatment remain important issues, the severity of which may be aggravated by poor quality antiepileptic drugs (AEDs). The primary objective of this study was to measure the quality of AEDs in rural and urban areas in 3 African countries. This cross-sectional study was carried out in Gabon, Kenya, and Madagascar. Both official and unofficial supply chains in urban and rural areas were investigated. Samples of oral AEDs were collected in areas where a patient could buy or obtain them. Pharmacological analytical procedures and Medicine Quality Assessment Reporting Guidelines were used to assess quality. In total, 102 batches, representing 3782 units of AEDs, were sampled. Overall, 32.3% of the tablets were of poor quality, but no significant difference was observed across sites: 26.5% in Gabon, 37.0% in Kenya, and 34.1% in Madagascar (P = .7). The highest proportions of substandard medications were found in the carbamazepine (38.7%; 95% confidence interval [CI] 21.8-57.8) and phenytoin (83.3%; 95% CI 35.8-99.5) batches, which were mainly flawed by their failure to dissolve. Sodium valproate was the AED with the poorest quality (32.1%; 95% CI 15.8-42.3). The phenobarbital (94.1%; 95% CI 80.3-99.2) and diazepam (100.0%) batches were of better quality. The prevalence of substandard quality medications increased in samples supplied by public facilities (odds ratio [OR] 9.9; 95% CI 1.2-84.1; P < .04) and manufacturers located in China (OR 119.8; 95% CI 8.7-1651.9; P < .001). The prevalence of AEDs of bad quality increased when they were stored improperly (OR 5.4; 95% CI 1.2-24.1; P < .03). No counterfeiting was observed. However, inadequate AED storage conditions are likely to lead to ineffective and possibly dangerous AEDs, even when good-quality AEDs are initially imported. Wiley Periodicals, Inc. © 2018 International League Against

Bats are rare reservoirs of Staphylococcus aureus complex in Gabon.

Science.gov (United States)

Held, Jana; Gmeiner, Markus; Mordmüller, Benjamin; Matsiégui, Pierre-Blaise; Schaer, Juliane; Eckerle, Isabella; Weber, Natalie; Matuschewski, Kai; Bletz, Stefan; Schaumburg, Frieder

2017-01-01

The colonization of afro-tropical wildlife with Staphylococcus aureus and the derived clade Staphylococcus schweitzeri remains largely unknown. A reservoir in bats could be of importance since bats and humans share overlapping habitats. In addition, bats are food sources in some African regions and can be the cause of zoonotic diseases. Here, we present a cross-sectional survey employing pharyngeal swabs of captured and released bats (n=133) in a forest area of Gabon. We detected low colonization rates of S. aureus (4-6%) and S. schweitzeri (4%) in two out of four species of fruit bats, namely Rousettus aegyptiacus and Micropteropus pusillus, but not in insectivorous bats. Multilocus sequence typing showed that S. aureus from Gabonese bats (ST2984, ST3259, ST3301, ST3302) were distinct from major African human associated clones (ST15, ST121, ST152). S. schweitzeri from bats (ST1697, ST1700) clustered with S. schweitzeri from other species (bats, monkeys) from Nigeria and Côte d'Ivoire. In conclusion, colonization rates of bats with S. aureus and S. schweitzeri were low in our study. Phylogenetic analysis supports an intense geographical dispersal of S. schweitzeri among different mammalian wildlife hosts. Copyright © 2016 Elsevier B.V. All rights reserved.

Fate of the Epsilon Phase in the Oklo Natural Reactors

International Nuclear Information System (INIS)

S. Utsunomiya; R.C. Ewing

2005-01-01

In spent nuclear fuel (SNF), the micron- to submicron-sized epsilon phase (Mo-Ru-Pd-Tc-Rh) is an important host of 99 Tc which has a long half life (2.13 x 10 5 years) and can be an important contributor to dose in safety assessments of nuclear waste repositories. In addition, Tc is predominantly present as TcO 4 - under oxidizing conditions at wide range of pH, weakly adsorbed onto mineral surfaces, and unlikely to be incorporated into alteration uranyl minerals. In the Oklo natural reactor (2.0 Ga), essentially all of the 99 Tc has decayed to 99 Ru. Thus, this study focuses on Ru and the other metals of the epsilon phase in order to investigate the occurrence and the fate of the epsilon phase during the corrosion of this natural SNF. Samples from reactor zone (RZ)-10 (836, 819, 687); from RZ-13 (864, 910); were investigated using TEM (transmission electron microscopy). Within the UO 2 matrix, a Bi-Pd particle (40-60 nm), fioodite, PdBi 2 , was observed with trace amounts of As, Fe, and Te surrounded by an amorphous Pb-rich area. (Pd,Rh) 2 As, palladodymite or rhodarsenide, was observed (400-500 nm in size). Ruthenarsinite, (Ru,Ni)As, was identified in most samples: with a representative composition of As, 59.9: Co, 2.5: Ni, 5.2; Ru, 18.6; Rh, 8.4; Pd, 3.1; Sb, 2.4 in atomic percent. The particles diameters are a few hundred nanometers and, in most cases, surrounded by a Pb-rich phase (400-500 nm). Typically, the ruthenarsenite does not occur as single particle but an aggregate of ∼200 nm-sized particles. Some Ru-particles revealed a complex phase separation within the grain such as a Ru-particle (600-700 nm) with Pb at the core of the particle and enrichment of Ni, Co, and As at the rim. Some ruthenarsenite crystals were embedded in chlorite immediately adjacent to uraninite. A few particles were still coated by Pb. These results suggest a history for the epsilon phases: (1) The original epsilon phase was transformed to, in most cases, ruthenarsenite. (2) All

History and perspectives of medical research at the Albert Schweitzer Hospital in Lambaréné, Gabon.

Science.gov (United States)

Ramharter, Michael; Adegnika, Ayola A; Agnandji, Selidji T; Matsiegui, Pierre Blaise; Grobusch, Martin P; Winkler, Stefan; Graninger, Wolfgang; Krishna, Sanjeev; Yazdanbakhsh, Maria; Mordmüller, Benjamin; Lell, Bertrand; Missinou, Michel A; Mavoungou, Elie; Issifou, Saadou; Kremsner, Peter G

2007-01-01

In 1913 Albert Schweitzer founded one of the first modern hospitals in Africa dedicated to the health of the local population. The Albert Schweitzer Hospital is located in Lambaréné, a small town in Gabon. In 1981 a research department--the Medical Research Unit--was established with the aim to perform research in the field of infectious diseases ( www.lambarene.org ). The main focus lies on clinical research on malaria and other parasitic diseases. Studies on the molecular biology and immunology of parasitic diseases are fostered since the inauguration of a novel building dedicated for basic science. A training program in clinical research in tropical diseases for African scientists has been set up recently.

Indications of uranium transport around the reactor zone at Bagombe (Oklo)

International Nuclear Information System (INIS)

Gurban, I.; Laaksoharju, M.; Ledoux, E.; Made, B.; Salignac, A.L.

1998-08-01

The aim of this study is to use the hydrogeological and hydrochemical data from Oklo Natural Analogue to compare the outcome of two independent modelling approaches (HYTEC-2D and M3) which can be used to model natural conditions surrounding the reactor. HYTEC-2D represents a 2D, deterministic, transport and multi-solutes reactive coupled code developed at Ecole des Mines de Paris. M3 (named Multivariate Mixing and Mass balance) is a mathematical-statistical concept code developed for SKB. The M3 results are visualised using the Voxel Analyst code and the outcome of the uranium transport predictions are made from a performance assessment point of view. This exercise was in the beginning intended to represent a validation for M3, by comparing this statistic approach with the standard hydrodynamic - geochemical coupled code HYTEC-2D. It was realized that the codes complete each other and a better understanding of the geochemical studied system is obtained. Thus, M3 can relatively easily be used to calculate mixing portions and to identify sinks or sources of element concentrations that may exist in a geochemical system. This can help to address the reactions in the coupled code such as HYTEC-2D, to identify the hydrodynamic and hydrochemical system and to reduce the computation time. M3 shows the existence of the buffer around the reactor. No transport of uranium was indicated downstream the reactor. HYTEC-2D gives the same result in the case when we consider the existence of the redox buffer in the model. M3 shows an increase of the alkalinity in the reactor zone. The increase of the alkalinity was indicated by the M3 modelling to be associated with microbial decomposition of organic material which added reducing capacity to the system. The modelling result was supported by new results from the last field campaign, which included in-situ Eh measurements and microbial sampling and identification. The effects from the same process was indicated also by the HYTEC-2D

Bacteria, colloids and organic carbon in groundwater at the Bangombe site in the Oklo area

Energy Technology Data Exchange (ETDEWEB)

Pedersen, K. [ed.

1996-02-01

This report describes how microorganisms, colloids and organic matter were sampled from groundwater from six boreholes at the Bangombe site in the Oklo region and subsequently analyzed. For analysis of microorganisms, DNA was extracted from groundwater, amplified and cloned and information available in the ribosomal 16S rRNA gene was used for mapping diversity and distribution of bacteria. Each borehole was dominated by species that did not dominate in any of the other boreholes, a result that probably reflects documented differences in the geochemical environment. Analyses of sampled colloids included SEM and ICP-MS analysis of colloids on membrane and single particle analysis of samples in bottles. The colloid concentration was rather low in these Na-Mg-Ca-HCO{sub 3} type waters. Trace element results show that transition metals and some heavy metals are associated with the colloid phase. Distribution coefficients of trace elements between the water and colloid phases were estimated. For example for uranium, an average of 200 pg/ml was detected in the water, and 40 pg/ml was detected in the colloid phase. A K{sub p} value of 2* 10{sup 6} ml/g was calculated, considering (colloid) = 100 ng/ml. Groundwater samples were collected for analysis of the concentration of organic carbon (TOC), humic substances and metals associated with the humic substances. TOC varied in the range 4-14 mg/l in three boreholes, one borehole had a TOC<1.5 mg/l. The metal speciation study indicated that a large fraction, 8-67% of uranium was bound to the humic matter compared to the fractions of Ca and Fe (<0.4% and 0.02-10%, resp.). 60 refs, 8 figs, 16 tabs.

Des tubercules pour la mort: analyses préliminaires des relations entre l'ordre naturel et l'ordre culturel dans l'iconographie Mochica

Directory of Open Access Journals (Sweden)

1990-01-01

Full Text Available Le but de cet article est de démontrer que c’est à partir de savantes observations du milieu naturel que les Mochicas ont puisé leur inspiration pour former leur iconographie. Il y aurait donc une corrélation entre les représentations de plantes ou d’animaux et leurs propriétés et comportements naturels. Nous explorons ici les relations entre les représentations de tubercules, d’humains, de certains animaux, et le monde mortuaire. LOS TUBÉRCULOS Y LA MUERTE. Análisis preliminares de las relaciones entre el orden natural y el orden cultural en la iconografía mochica. Se demuestra en este artículo que, para plasmar su iconografía, los Mochicas se inspiraron de sabias observaciones del medio natural. Entonces había un vínculo entre las representaciones de plantas y animales, sus propiedades y comportamientos naturales. Se indica aquí las relaciones entre las representaciones de tubérculos, de humanos, de ciertos animales, y el mundo mortuorio. TUBERS AND DEATH. Preliminary Analysis of the Relations Between the Natural and Cultural Order in Mochica Iconography. The objective of this article is to demonstrate that the Mochicas have designed their iconography system by studying closely their natural environment. Hence, there is a correlation between the natural comportments of the animals or the properties of the plants and their representations in the iconography. We explore the relation between the representations of tubers, human and animals beings, and the mortuary world.

Comprehensive study of proteasome inhibitors against Plasmodium falciparum laboratory strains and field isolates from Gabon

Directory of Open Access Journals (Sweden)

Kremsner Peter G

2008-09-01

Full Text Available Abstract Background The emergence and spread of Plasmodium falciparum resistance to almost all available antimalarial drugs necessitates the search for new chemotherapeutic compounds. The ubiquitin/proteasome system plays a major role in overall protein turnover, especially in fast dividing eukaryotic cells including plasmodia. Previous studies show that the 20S proteasome is expressed and catalytically active in plasmodia and treatment with proteasome inhibitors arrests parasite growth. This is the first comprehensive screening of proteasome inhibitors with different chemical modes of action against laboratory strains of P. falciparum. Subsequently, a selection of inhibitors was tested in field isolates from Lambaréné, Gabon. Methods Epoxomicin, YU101, YU102, MG132, MG115, Z-L3-VS, Ada-Ahx3-L3-VS, lactacystin, bortezomib (Velcade®, gliotoxin, PR11 and PR39 were tested and compared to chloroquine- and artesunate-activities in a standardized in vitro drug susceptibility assay against P. falciparum laboratory strains 3D7, D10 and Dd2. Freshly obtained field isolates from Lambaréné, Gabon, were used to measure the activity of chloroquine, artesunate, epoxomicin, MG132, lactacystin and bortezomib. Parasite growth was detected through histidine-rich protein 2 (HRP2 production. Raw data were fitted by a four-parameter logistic model and individual inhibitory concentrations (50%, 90%, and 99% were calculated. Results Amongst all proteasome inhibitors tested, epoxomicin showed the highest activity in chloroquine-susceptible (IC50: 6.8 nM [3D7], 1.7 nM [D10] and in chloroquine-resistant laboratory strains (IC50: 10.4 nM [Dd2] as well as in field isolates (IC50: 8.5 nM. The comparator drug artesunate was even more active (IC50: 1.0 nM, whereas all strains were chloroquine-resistant (IC50: 113 nM. Conclusion The peptide α',β'-epoxyketone epoxomicin is highly active against P. falciparum regardless the grade of the parasite's chloroquine

Écologie des stomoxes (Diptera : Muscidae au Gabon. I – Premier inventaire dans différentes zones écologiques

Directory of Open Access Journals (Sweden)

Mavoungou J.F.

2008-03-01

Full Text Available Les stomoxes (Stomoxys spp. sont des diptères hématophages, vecteurs potentiels de divers agents pathogènes. Comme ceux de la région afrotropicale en général, les stomoxes du Gabon demeurent mal connus. Pour ces raisons, une enquête entomologique a été conduite de façon transversale dans huit localités représentatives des diverses zones écologiques du Gabon. L’enquête est basée sur l’utilisation de pièges Vavoua. Divers facteurs environnementaux pouvant influer sur les captures ont été relevés et inclus dans une analyse canonique des correspondances. Au total, 15 966 stomoxes, appartenant à sept espèces ou sous-espèces, ont été capturés. Les densités apparentes (DAP, exprimées en nombre de stomoxes par piège et par jour, sont importantes dans les localités de Franceville (41, Bakoumba (40, Makokou (25 et Mouila (21. Les espèces les plus abondantes sont Stomoxys n. niger (33,4 % de l’ensemble des captures, S. transvittatus (33 % puis S. calcitrans (17 %. Les principaux facteurs qui expliquent la variabilité des captures sont le degré d’anthropisation du milieu, le faciès botanique (savane ou forêt, la présence de la faune sauvage et domestique et la nature de la couverture végétale du sol. S. calcitrans et S. n. niger sont abondants dans les zones où la présence humaine est manifeste. S. xanthomelas est inféodé aux zones forestières. S. transvittatus, S. omega, et S. inornatus sont des espèces ubiquistes. S. niger bilineatus se retrouve dans les zones de savane.

'Scrap yard challenge'

International Nuclear Information System (INIS)

Hollick, A.

2000-01-01

'Plutonium'. The word evokes deep reactions outside of the nuclear industry. Although the majority of Plutonium currently in existence is man-made and therefore perceived as being unnatural, plutonium has been found as a product of the Oklo natural reactor in Gabon. This paper seeks to challenge two concepts, that of the Nuclear Control Institute that Plutonium is unnatural, 'fiendishly toxic' and one of the 'substances most hazardous to man' and the second image that a high security Plutonium store is merely a 'scrapyard' containing a material which has little use. The nuclear industry has often been accused of treating Plutonium and its accumulation casually in proportion to the risks perceived by those outside the industry. As a result this paper seeks to demonstrate that the industry is aware of the concerns of the public and is actively seeking viable solutions. The paper looks at Plutonium itself and explores the issues surrounding military and civil Plutonium in adding to the current stockpiles. It also suggests three possible alternatives for dealing with these Plutonium stockpiles and arrives at a conclusion as to which solutions currently appear most viable. (authors)

Les perspectives du gaz naturel dans le Monde World Natural Gas Prospects

Directory of Open Access Journals (Sweden)

Valais M.

2006-11-01

Full Text Available Dans un monde en quête de diversification énergétique, le gaz naturel apparaît comme une source d'énergie particulièrement attrayante. Par son abondance, sa facilité de substitution aux produits pétroliers dans une gamme très large d'usages, il pourrait assurément jouer un rôle beaucoup plus important dans la couverture des besoins énergétiques mondiaux. Toutefois, de nombreux obstacles semblent devoir ralentir sa progression. Cet article dégage les grands paramètres techniques et économiques qui devraient conditionner le développement de l'industrie du gaz dans le monde et présente des perspectives d'évolution de sa production et de son commerce international d'ici à la fin du siècle. For a world in search of energy diversification, natural gas is a particularly attractive source. Its abundance and its facility for being substituted for petroleum products over a wide range of uses should certainly mean that it will play a much more important rote in filling world energy needs. Nonetheless, many obstacles are hindering its progress. This article outlines the leading technical and economic parameters which should influence the development of the world gas industry, and the prospects for its production and international trade evolution between now and the end of the century.

The linguistic and stylistic content in teaching Spanish in Gabon: attitudes and teaching practices

Directory of Open Access Journals (Sweden)

Jeanne Berthe MAKAYA MAVOUNGOU

2016-07-01

Full Text Available Always it has made us perplex, the position thought by the majority of the professorship gabonés as for if we have to or not to be interested to the partial or complete study of the linguistic and semantic aspects during the explanation and comment of a document. The education of the language and of the Spanish literature needs of the teacher the capture in account and the knowledge of the synergy that exists between the different genres, the aesthetic expression, the semantic content and the pragmatic use. It is the reason by which there is expected from the teacher, the capture in account of the contributions of other such connected sciences as the linguistics, the aesthetics, the sociology, the psychology, etc. That do not stop suggesting to the pedagogy and to the didactics other tracks of treatment of the suitable contents in class of Spanish language. The contribution of this investigation places, especially, to level of the analysis of the educational practices and the contributions of these by means of the semantic and linguistic paths.

Natural Gas Storage Seismic Monitoring Suivi sismique des stockages de gaz naturel

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Mari J.L.

2011-02-01

Full Text Available IFP Energies nouvelles, CGGVeritas and GDF Suez have conducted together, since 1980, a series of seismic monitoring experiments in order to detect and follow the movements of the gas plume in natural gas geologic storages. Surface and well seismic surveys were carried out at different stages of the storage life. Permanent receiver arrays have been set down in wells. Permanent sources have been designed. Sources and receivers have been used to follow continuously the storage cycle during several years, providing time measurement accuracy within a tenth of a millisecond. Gas intrusion into an aquifer leads to an increase in the arrival times of reflections beneath the storage reservoir and to a variation of the reflection amplitudes at top and bottom of the reservoirs. Progressive variations of the seismic parameters may be followed during the initial infill period. Further movements of the gas plume with the annual in/out cycles are more difficult to follow, because of the simultaneous presence of gas and water in the pores. Arrival time variations of some tenths of a millisecond may be detected and measured. Saturations, using accurate picking of the arrival times, can be estimated in favourable cases. Because of the higher density of carbon dioxide, when stored in a supercritical phase, sensitivity of the seismic parameters, velocity, density and acoustic impedance to saturation variations will be about twice smaller for CO2 storages than it is for methane. IFP Energies nouvelles, la CGGVeritas et GDF Suez ont mené ensemble, depuis 1980, de nombreuses expériences de monitoring sismique afin de détecter et de suivre les mouvements du gaz dans des stockages géologiques de gaz naturel. Des acquisitions ont été réalisées à différents stades de la vie du stockage tant en sismique de surface qu’en sismique de puits. Des antennes de récepteurs permanentes ont été construites et implantées dans des puits. Des sources permanentes ont �

Malles pédagogiques itinérantes « les grands singes et leur habitat »: parcours et premières évaluations de l’impact du projet en Ouganda et au Gabon Educative kits « great apes and their habitat » : itinerary and impact evaluation of the project in Uganda and in Gabon

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Helena Nambogwe

2009-10-01

Full Text Available Un programme de sensibilisation sur les grands singes et les forêts tropicales a été conçu en partenariat entre le « Projet pour la conservation des Grands Singes », le Muséum National d’Histoire Naturelle, l’UNESCO et la Coopération Française. Il s’appuie sur la circulation de malles pédagogiques d’un volume d’environ 1m3 contenant des outils ludiques et didactiques présentés par des animateurs locaux. Après une année de circulation de la malle dans les écoles à proximité des zones où vivent les grands singes en Ouganda et au Gabon, près de 15 000 enfants ont pris part à ce programme. Reçue dans 52 écoles primaires et secondaires en Ouganda, sur un parcours de 1 500 km organisé par le Wildlife Club of Uganda, la malle pédagogique et les animations associées ont permis selon une première étude d’impact d’accroître la motivation des enfants à protéger les grands singes et leur habitat. Au Gabon, le projet, sous l’impulsion du RAPAC, s’est appuyé sur neuf partenaires impliqués dans l’éducation environnementale et a pu être accueilli dans 66 écoles du pays dont certaines situées dans une concession forestière. Dans certaines localités, des données sur la consommation de viande de grands singes ont été collectées. Les sites atteints étaient répartis sur un circuit de 1 500 km. Les perspectives sont d’élargir le programme à d’autres pays de l’aire de répartition des grands singes en y associant des enquêtes socio-économiques et des études d’impact.  The Association « Projet pour la Conservation des Grands Singes » in partnership with MNHN, UNESCO and France Cooperation designed Great Apes kits. The showcases contain a set of entertaining and educative tools and activities explaining forests, ecosystems and great apes presented by national educators. The two first kits have moved in Uganda and Gabon in areas located where great apes occur. 15,000 kids from remote

Impact of epilepsy on children and parents in Gabon.

Science.gov (United States)

Ibinga, Euloge; Ngoungou, Edgard Brice; Olliac, Bertrand; Hounsossou, Cocou Hubert; Dalmay, François; Mouangue, Gertrude; Ategbo, Simon Jonas; Preux, Pierre-Marie; Druet-Cabanac, Michel

2015-03-01

Children with epilepsy and their parents face many social and psychological difficulties that remain insufficiently studied in sub-Saharan Africa. The aim here was to assess the quality of life of children with epilepsy and their parents. A community-based cross-sectional survey was conducted in two urban areas and four rural areas of Gabon. Children were screened through key informants, medical sources, and a door-to-door survey. They were clinically selected based on their medical history and a clinical exam conducted by the investigating physician. Electroencephalography had not been carried out because of a lack of material and financial resources. The quality of life of children and their parents was assessed by a structured interview of parents using a questionnaire. Of 317 suspected cases on screening, 83 children with epilepsy were identified. Their mean age was 11.9±4.4years. Twelve percent of the children had neurosensory abnormalities on clinical exam. Sixty-three percent of them attended school; factors associated with schooling were higher score on the sociability subscale, specialized medical advice, and antiepileptic drug treatment. Sociability difficulties, anxiety, cognitive impairment, and behavioral disorders were suspected in 39.8%, 45.8%, 49.4%, and 42.2% of children, respectively. A total of 48.2% of parents expressed a poor quality of life related to their children's illness. A higher score on the cognition subscale, urban residence, specialized medical advice, and a stable income in the household were predictive of poor parental quality of life. Epilepsy influences many aspects of a child's life and the life of the child's parents. Care should incorporate a cognitive assessment of the child and emphasize information for patients and their relatives. Copyright © 2015 Elsevier Inc. All rights reserved.

Ethnobotanical survey of medicinal plants used as anthelmintic remedies in Gabon.

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Bajin Ba Ndob, Idensi; Mengome, Line Edwige; Bourobou Bourobou, Henri-Paul; Lossangoye Banfora, Yvon; Bivigou, Francis

2016-09-15

In this article, we report on an ethnobotanical survey realized at the Peyrie market in Libreville on Gabonese medicinal plants used to treat helminthiasis. While several alerts about cases of resistance to conventional anthelmintic treatments are causing to fear a public and animal health issue, the search for new sources of active compounds becomes an urgent issue. In Gabon like in many developing countries, people regularly turn to traditional medicine in case of physical ailments and/or spiritual healing therapies. To determine which medicinal plants are traditionally used by the populations of Libreville to fight against nematodes, medicinal plant traders were interviewed with standardized questionnaires. The surveys were conducted in the main market of Libreville. Ethnobotanical data such as frequency and percentage of families, species, administrations pathways, modes of preparations and parts of plants used were analyzed and summarized. Thirty-four (34) traders were interviewed belonging to five (5) different ethnic groups. Twenty-four 24 plants used to treat intestinal, cutaneous and ocular helminthiasis were listed. The healers mainly turned towards to ligneous species. The parts of the plant used are mostly leaves and trunk bark. Most of the traditional remedies are prepared directly in water and four (4) principal routes were used for administration namely, oral, rectal, ocular and dermal. This study allowed us to list anthelmintic species which will be subjected to a series of chemical and pharmacological assays. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Molecular characterization of Shigella spp. from patients in Gabon 2011-2013.

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Schaumburg, Frieder; Alabi, Abraham S; Kaba, Harry; Lell, Bertrand; Becker, Karsten; Grobusch, Martin P; Kremsner, Peter G; Mellmann, Alexander

2015-04-01

Shigella spp. dysentery is widespread in developing countries; the incidence is particularly high in children between 1-2 years of age. In sub-Saharan Africa, there is a paucity of epidemiological data on Shigella spp., with possible negative consequences for recognition and correct treatment choice for this life-threatening bacterial infection. We therefore characterized Shigella spp. isolates from Gabon. The antimicrobial resistance, virulence factors, genotypes and mobile genetic elements of Shigella isolates (29 S. flexneri; 5 S. boydii; 3 S. sonnei) from a retrospective strain collection were analyzed. High resistance rates were found for gentamicin and tetracycline (100%, 37/37), cotrimoxazole (92%, 34/37) and ampicillin (84%, 31/37). All isolate harbored ial and ipaH; no isolate produced Shiga toxins (stx1/2); enterotoxins (set1A/B) were only found in S. flexneri (n=19). Multilocus sequence types (MLST) clustered with global clones. A high prevalence of atypical class 1 integrons harboring blaOXA30 and aadA1 were detected in S. flexneri, while all S. sonnei carried class 2 integrons. There is a strong link of Gabonese Shigella spp. isolates with pandemic lineages as they cluster with major global clones and frequently carry atypical class 1 integrons which are frequently reported in Shigella spp. from Asia. © The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

New data on the geological environment of the natural reactors

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.; Besnus, Y.; Weber, F.

1978-01-01

Since the Libreville symposium in 1975 knowledge of the geological environment of the reactors has advanced as a result of a more extensive study of the Francevillian uranium deposits. In the Oklo deposit a detailed stratigraphy of the Cl bed (uraniferous mineralized bed) has been established, making it possible to re-establish stratigraphically the position of the natural reactors. A tectonic analysis of the Oklo deposit has revealed the special features of the Oklo structure and the reaction zones situated in the shear troughs. Petrographic studies have revealed the presence of two types of ore with distinct modes of formation. In the first case, the role played by organic materials seems predominant, while in the second case migrations of oxidizing solutions are the main source of the reconcentrations. Finally, a geochemical study made of samples from Oklo and Okelobondo points to the existence of an ''isolated'' geochemical phase containing uranium and a certain number of trace elements. This phase is associated with the organic material. This study also deals with the migration of lead at Oklo and Mounana. (author)

Prevalence of malaria, prevention measures, and main clinical features in febrile children admitted to the Franceville Regional Hospital, Gabon

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Maghendji-Nzondo Sydney

2016-01-01

Full Text Available Recently, major progress has been made in controlling malaria in Africa. However, in Gabon, little information is available on the role of malaria in childhood febrile syndromes, the use and efficacy of preventive measures, and Plasmodium species distribution. Here, we characterized malaria in febrile children in Franceville, Gabon through a cross-sectional study at the pediatric unit of the Franceville Regional Hospital. We registered 940 febrile children. Their general condition was markedly altered in 11.7% of cases (n = 89/760; among them 19 (21.4% had a severely altered condition. Malaria was the second most frequent etiology (22.0%; n = 162/738, after respiratory tract infections (37.3%; n = 275/738. Children with malaria (63 ± 39 months were older than children without malaria (40 ± 37 months (p = 0.0013. Hemoglobin, red blood cell, white blood cell, and platelet values were lower in children with malaria than in those without malaria (p < 0.0001. Anemia was the most common feature of severe malaria (70.6%; n = 12/17, followed by neurological involvement (23.5%; n = 4/17. The prevalence of malaria was significantly higher in children older than 60 months than in younger children (40% vs. 15.5%; p < 0.0001. Plasmodium falciparum accounted for 97.5% of cases (158/162, followed by Plasmodium malariae (2.5%; n = 4/162. Bed net use was high (74.4%; n = 697/936 and contributed to malaria prevention (p = 0.001. Good basic knowledge of malaria also had a preventive effect (p < 0.0001. The prevalence of malaria in children in Franceville did not decrease significantly from 2009 to 2012, remaining at about 20%, highlighting that preventive measures should be reinforced.

World Gas Prospects: Which Role for the Middle East? Perspectives mondiales du gaz naturel : quel rôle pourrait jouer le Moyen-Orient ?

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Chabrelie M. F.

2006-12-01

Full Text Available Since the early 1970s, the policies of energy diversification that have been implemented in the industrialized countries and in many developing countries have enabled natural gas to regularly increase its role in the world energy balance. Thus, during the past twenty years, natural gas recorded the highest growth rate among fossil fuels, and its share in the energy market has gradually risen from 18. 9% in 1975 to 23% in 1997. Today, thanks to favorable economic and environmental factors, natural gas has become the fuel of choice on many markets. Indeed, gas is blessed with a certain number of favorable assets (abundant reserves, flexibility, high-performance uses which give it a major role in all energy demand forecast scenarios. The most spectacular development will indisputably take place in the power generation sector. Endowed with a considerable gas potential, the Middle East will represent an essential source of supply for many industrialized countries and several gas export projects, either by LNG tanker or by pipelines are currently being contemplated. During the past decade, the contribution of natural gas to the energy mix also grew substantially in most Middle Eastern countries. The increase in gas demand should continue at a sustained rate, mainly driven by the power generation sector, petrochemicals and energy consumption by the hydrocarbons industry. These promising prospects for gas demand in most of the markets in the region might lead to the development of an intra-regional network. However, although opportunities exist, the region will have to meet many challenges in order to contribute more largely to the world gas balance in the years to come. de diversification énergétique mises en Suvre dans les pays industrialisés et dans de nombreux pays en voie de développement depuis le début des années 1970 ont permis au gaz naturel d'accroître régulièrement sa présence dans le bilan énergétique mondial. Ainsi, au cours des

Bactériophages et phagothérapie: utilisation de virus naturels pour traiter les infections bactériennes

Science.gov (United States)

Ravat, F.; Jault, P.; Gabard, J.

2015-01-01

Summary L’utilisation des bactériophages, prédateurs naturels des bactéries, est une technique pionnière efficace de lutte contre les infections bactériennes. Tombée dans l’oubli depuis un demi-siècle du coté occidental de l’ex-rideau de fer, elle fait toujours partie de l’arsenal thérapeutique des pays de l’ex-Europe de l’Est, au point de constituer une arme de choix dans la politique de santé publique de ces pays. l’émergence de bactéries multirésistantes et le risque de revenir à l’ère pré-antibiotique ont fait ressortir la phagothérapie de l’oubli injuste auquel elle avait été confinée. la biologie et la place du bactériophage dans la nature sont décrites ici. les tenants et les aboutissants de la phagothérapie et les conditions de son retour sur le devant de la scène sont explicitées. PMID:26668557

Developments in natural uranium - graphite reactors; Developpement des reacteurs a graphite et uranium naturel

Energy Technology Data Exchange (ETDEWEB)

Bourgeois, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Saitcevsky, B [Electricite de France (EDF), 75 - Paris (France)

1964-07-01

in order to show the advantages resulting from such developments in gas-graphite natural metallic uranium reactor systems; these are: a doubling of the specific and volume powers, and a three-fold reduction in the number of channels. The research now under way will make it possible to calculate the reduction in capital costs which will result from these important technical advances. (authors) [French] Le programme francais de centrales a graphite et uranium naturel s'est developpe, d'EDF 1 a EDF 4 - dans la voie d'un accroissement de la puissance unitaire des installations, de la puissance specifique et de la puissance volumique, et d'une amelioration des conditions de securite de fonctionnement. La puissance elevee d'EDF 4 (500 MWe) et l'integration du circuit primaire dans le caisson, lui-meme en beton precontraint, permettent ainsi de tirer le meilleur parti des elements combustibles tubulaires utilises des EDF 1, et d'arriver ainsi a une solution tres satisfaisante. L'emploi d'un element combustible refroidi interieurement (element annulaire) permet de faire un nouveau pas en avant: il devient alors possible d'augmenter la pression du gaz de refroidissement sans craindre le fluage du tube d'uranium. L'emploi d'un caisson en beton precontraint permet une telle augmentation de pression, et l'integration du circuit primaire elimine les risques d'une depressurisation rapide qui aurait presente dans ce cas un risque majeur. On aborde dans ce rapport les principaux problemes poses par ce nouveau type de centrale et on indique les grandes lignes des recherches et etudes effectuees en France: - Les etudes de neutronique et thermique ont permis d'envisager l'emploi d'elements combustibles de grandes dimensions (diametre interne = 77 mm, diametre externe = 95 mm), tout en conservant l'uranium naturel. - Les problemes de fabrication de ces elements, et de leur comportement en pile, font l'objet d'un programme important, tant hors pile que dans les piles de puissance (EDF 2

Dosage du mercure dans le gaz naturel par absorption atomique sans flammes Mercury Titration in Natural Gas by Flameless Atomic Absorption

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La Villa F.

2006-11-01

Full Text Available Cet article présente la méthode mise au point par l'Institut Français du Pétrole pour déterminer par absorption atomique sans flamme, les traces de mercure métallique contenu dans un gaz naturel. La méthode d'analyse nécessite une extraction du mercure soit sous forme d'ion mercurique en faisant passer le gaz dans une solution oxydante, soit sous forme d'amalgame avec de l'or ou de l'argent. Le premier mode opératoire s'applique aux échantillons dont la concentration en mercure est supérieure à I ttg/Nm3, le second pour des concentrations inférieures à 5 pg/Nm3. Les seuils de détection sont respectivement 10 ng (en solution et 0,3 ng (en amalgame. La répétabilité pour 100 ng de mercure (en amalgame est de ± 7% pour une probabilité de.95 %. En conclusion, dans un échantillon de gaz naturel, compte tenu du volume des prélèvements effectués, il est possible de détecter des concentrations de l'ordre du nanogramme de mercure par mètre cube de gaz. This article describes the method developed by IFP using flameless atomic absorption to determine metallic mercury traces in a natural gas. The analyst method requires a mercury extraction either in the form of mercuric ions by making the gas pass through an oxidizing solution or in the form of an amalgam with gold or silver. The former operating method applies ta samples having a mercury concentration greater than I !ag/Nm3, and the latter for concentrations smaller than 5 (-Lg/Nm3. Detection thresholds are respectively 10 ng (in solution and 0.3 ng (in amalgam. The repeatability for 100 ng of mercury (in amalgam is ± 7 % with a probability of 95%. To conclude, in a sample of natural gas, considering the volume of the samples taken, it is possible ta detect concentrations in the vicinity of one nanogrom of mercury per cubic meter of gas.

Précaution et développement régional durable dans le domaine des risques naturels. Quels enseignements tirer des exemples présentes ?

OpenAIRE

Brugnot, Gérard

2013-01-01

Note portant sur l’auteur 1. RISQUES NATURELS : ALEA ET VULNERABILITE Le risque naturel est constitué de l'aléa et de la vulnérabilité. On peut compliquer cette définition en ajoutant, comme Finlay (1997), des niveaux de profondeur d'analyse (phénomènes/aléas vs enjeux/vulnérabilité), ou bien encore en prenant en compte l'aléa et la vulnérabilité perçus, faisant respectivement appel aux probabilités subjectives et aux théories de l'utilité et du risque en économie. R=G(A) ⊗ *U(D)* Dans cette...

[Evaluation of primary health care activities at the Albert Schweitzer hospital in Lambarene, Gabon].

Science.gov (United States)

Diallo, M; Ninteretse, B

2007-06-01

In 1999 the Albert Schweitzer Hospital in Lambrene, Gabon set up a community health care service that provides immunization campaigns and mother/child health care and manages 9 village health care centers in a district with a population of approximately 64000 inhabitants. An evaluation conducted in April 2006 showed that collection of a consultation charge (15 euros) could cover the basic costs of operating these centers and purchasing necessary medicines. Three of the four centers evaluated demonstrated good quality indicators including properly kept records, posting of information bulletins for patients, appropriate referrals, and good relations with village authorities. At the center that performed poorly, the nurse apparently received no pay or lodging. Analysis of data about pediatric activity showed that diagnosis of diarrhea, malnutrition and anemia has fallen while hospitalization for tuberculosis and urinary schistomiasis is now being recorded. At the same time, village health centers are increasingly concerned with problems related to management and prevention of AIDS, malaria and urinary schistomiasis. This service shows that with good supervision it is possible to improve the quality of primary health care with partial but adequate recovery of costs and that basic health care workers are able to provide overall management for complicated patients, facilitate the work of reference hospital, and report new health problems.

Developing information technology at the Medical Research Unit of the Albert Schweitzer Hospital in Lambaréné, Gabon.

Science.gov (United States)

Dibacka, Paterne Lessihuin; Bounda, Yann; Nguema, Davy Ondo; Lell, Bertrand

2010-03-01

Information technology has become a key resource for research institutions, providing services such as hardware, software and network maintenance, as well as data management services. The IT department of the Medical Research Unit (MRU) of the Albert Schweitzer Hospital in Lambaréné, Gabon is a good example of how IT has developed at African Research Centres in recent years and demonstrates the scope of work that a modern research centre needs to offer. It illustrates the development in the past 15 years--from single computers maintained by investigators to the present situation of a group of well-trained local IT personal who are in charge of a variety of hardware and software and who also develop applications for use in a research environment. Open source applications are particularly suited for these needs and various applications are used in data management, data analysis, accounting, administration and quality management.

Gorilla diet in the Lopé Reserve, Gabon: : A nutritional analysis.

Science.gov (United States)

Elizabeth Rogers, M; Maisels, Fiona; Williamson, Elizabeth A; Fernandez, Michel; Tutin, Caroline E G

1990-10-01

The results of an analysis of gorilla diet in the Lopé Reserve, Gabon are presented. Samples were assayed for nutrients and plant secondary compounds (total phenols, condensed tannins and alkaloids) in an attempt to explain gorilla food choice. The diet is the most diverse so far analysed for gorillas; it seems to be a balance between sugary fruit, proteinaceous leaves, and relatively fibrous stems. Most fruits and herbaceous stems are succulent, but some drier, fibrous fruit and bark is also consumed. Seeds are another component of the diet, including unripe ones. Fruit, seeds, leaves and bark may all contain very high levels of total phenols and condensed tannins; but all herbaceous stems assayed contain low levels of these compounds. Alkaloids are not apparently a significant component of gorilla foods, and may be avoided. Gorillas at Lopé tend to avoid fatty fruit, and select leaves which are high in protein and low in fibre compared to the general vegetation. When fruit and preferred young leaves are scarce, proteinaceous barks and mature leaves, and sugary pith, are important sources of nutrients. We conclude that gorillas exploit the broad frugivore niche in West African lowland forests, and are part of the frugivore community there. What distinguishes them is their ability to eat large fibrous fruit, mature leaves and stems, and to overcome high levels of phenolics (we use "phenolics" as an umbrella term for both total phenols and condensed tannins). Gorilla diet at Lopé overlaps greatly with that of sympatric, frugivorous, primates, and resembles more closely that of chimpanzees than it does gorilla diet studied elsewhere in Africa.

Evolving hunting practices in Gabon: lessons for community-based conservation interventions

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Gretchen Walters

2015-12-01

Full Text Available Addressing today's environmental challenges is intimately linked to understanding and improving natural resource governance institutions. As a result conservation initiatives are increasingly realizing the importance of integrating local perspectives of land tenure arrangements, natural resource rights, and local beliefs into conservation approaches. However, current work has not sufficiently considered the dynamic nature of natural resource governance institutions over time and the potential implications for current conservation interventions. We therefore explored how and why hunting governance has changed since the precolonial period in two ethnic hunting communities in Gabon, Central Africa, integrating various ethnographic methods with resource-use mapping, and a historic literature review. In both communities, hunting governance has undergone significant changes since the precolonial period. A closed-access, lineage-based system of resource use with strict penalties for trespassing, has evolved into a more open-access system, in which the influence of customary governance systems, including magico-political aspects, has declined. These changes have occurred mainly in response to policies and governance structures put in place by the colonial government and postindependence, early state laws. This included a policy of merging villages, the introduction of more modern hunting techniques such as guns and wire cables, and a shift from community to government ownership of the land. Current governance structures are thus the product of a complex mixture of customary, colonial and state influences. These findings suggest that a historical perspective of resource governance, gained through in-depth and long-term engagement with local communities, can provide important insights for community-based conservation approaches, such as helping to identify potential causes and perceptions of environmental change and to design more suitable conservation

Developments in natural uranium - graphite reactors; Developpement des reacteurs a graphite et uranium naturel

Energy Technology Data Exchange (ETDEWEB)

Bourgeois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Saitcevsky, B. [Electricite de France (EDF), 75 - Paris (France)

1964-07-01

in order to show the advantages resulting from such developments in gas-graphite natural metallic uranium reactor systems; these are: a doubling of the specific and volume powers, and a three-fold reduction in the number of channels. The research now under way will make it possible to calculate the reduction in capital costs which will result from these important technical advances. (authors) [French] Le programme francais de centrales a graphite et uranium naturel s'est developpe, d'EDF 1 a EDF 4 - dans la voie d'un accroissement de la puissance unitaire des installations, de la puissance specifique et de la puissance volumique, et d'une amelioration des conditions de securite de fonctionnement. La puissance elevee d'EDF 4 (500 MWe) et l'integration du circuit primaire dans le caisson, lui-meme en beton precontraint, permettent ainsi de tirer le meilleur parti des elements combustibles tubulaires utilises des EDF 1, et d'arriver ainsi a une solution tres satisfaisante. L'emploi d'un element combustible refroidi interieurement (element annulaire) permet de faire un nouveau pas en avant: il devient alors possible d'augmenter la pression du gaz de refroidissement sans craindre le fluage du tube d'uranium. L'emploi d'un caisson en beton precontraint permet une telle augmentation de pression, et l'integration du circuit primaire elimine les risques d'une depressurisation rapide qui aurait presente dans ce cas un risque majeur. On aborde dans ce rapport les principaux problemes poses par ce nouveau type de centrale et on indique les grandes lignes des recherches et etudes effectuees en France: - Les etudes de neutronique et thermique ont permis d'envisager l'emploi d'elements combustibles de grandes dimensions (diametre interne = 77 mm, diametre externe = 95 mm), tout en conservant l'uranium naturel. - Les problemes de fabrication de ces elements, et de leur comportement en pile

Mansonella, including a Potential New Species, as Common Parasites in Children in Gabon.

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Gaël Mourembou

Full Text Available Like other tropical African countries, Gabon is afflicted by many parasitic diseases, including filariases such as loiasis and mansonellosis. This study aimed to assess the prevalence of these two filarial diseases in febrile and afebrile children using quantitative real-time PCR and standard PCR assays coupled with sequencing.DNA from blood specimens of 1,418 Gabonese children (1,258 febrile and 160 afebrile were analyzed. Overall, filarial DNA was detected in 95 (6.7% children, including 67 positive for M. perstans (4.7%, which was the most common. M. perstans was detected in 61/1,258 febrile children (4.8% and 6/160 afebrile children (3.8%, P = 0.6. Its prevalence increased statistically with age: 3.5%, 7.7% and 10.6% in children aged ≤ 5, 6-10 and 11-15 years, respectively. M. perstans prevalence was significantly higher in Koulamoutou and Lastourville (12% and 10.5%, respectively than in Franceville and Fougamou (2.6% and 2.4%, respectively. Loa loa was detected in seven febrile children including one co-infection with M. perstans. Finally, 21 filarial DNA positive were negative for M. perstans and Loa loa, but ITS sequencing could be performed for 12 and allowed the identification of a potential new species of Mansonella provisionally called "DEUX". Mansonella sp. "DEUX" was detected only in febrile children.Further study should be performed to characterize Mansonella sp. "DEUX" and evaluate the clinical significance of mansonellosis in humans.

How Bees Deter Elephants: Beehive Trials with Forest Elephants (Loxodonta africana cyclotis in Gabon.

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Steeve Ngama

Full Text Available In Gabon, like elsewhere in Africa, crops are often sources of conflict between humans and wildlife. Wildlife damage to crops can drastically reduce income, amplifying poverty and creating a negative perception of wild animal conservation among rural people. In this context, crop-raiding animals like elephants quickly become "problem animals". To deter elephants from raiding crops beehives have been successfully employed in East Africa; however, this method has not yet been tested in Central Africa. We experimentally examined whether the presence of Apis mellifera adansonii, the African honey bee species present in Central Africa, deters forest elephants (Loxodonta Africana cyclotis from feeding on fruit trees. We show for the first time that the effectiveness of beehives as deterrents of elephants is related to bee activity. Empty hives and those housing colonies of low bee activity do not deter elephants all the time; but beehives with high bee activity do. Although elephant disturbance of hives does not impede honey production, there is a tradeoff between deterrence and the quantity of honey produced. To best achieve the dual goals of deterring elephants and producing honey colonies must maintain an optimum activity level of 40 to 60 bee movements per minute. Thus, beehives colonized by Apis mellifera adansonii bees can be effective elephant deterrents, but people must actively manage hives to maintain bee colonies at the optimum activity level.

A Comprehensive Numerical Study on Effects of Natural Gas Composition on the Operation of an HCCI Engine Une étude numérique complète sur les effets de la composition du gaz naturel carburant sur le réglage d’un moteur HCCI

Directory of Open Access Journals (Sweden)

Jahanian O.

2011-11-01

Full Text Available Homogeneous Charge Compression Ignition (HCCI engine is a promising idea to reduce fuel consumption and engine emissions. Natural Gas (NG, usually referred as clean fuel, is an appropriate choice for HCCI engines due to its suitable capability of making homogenous mixture with air. However, varying composition of Natural Gas strongly affects the auto-ignition characteristics of in-cylinder mixture and the performance of the HCCI engine. This paper has focused on the influence of Natural Gas composition on engine operation in HCCI mode. Six different compositions of Natural Gas (including pure methane have been considered to study the engine performance via a thermo-kinetic zero-dimensional model. The simulation code covers the detailed chemical kinetics of Natural Gas combustion, which includes Zeldovich extended mechanism to evaluate NOx emission. Validations have been made using experimental data from other works to ensure the accuracy needed for comparison study. The equivalence ratio and the compression ratio are held constant but the engine speed and mixture initial temperature are changed for comparison study. Results show that the peak value of pressure/temperature of in-cylinder mixture is dependent of fuel Wobbe number. Furthermore, engine gross indicated power is linearly related to fuel Wobbe number. Gross indicated work, gross mean effective pressure, and NOx are the other parameters utilized to compare the performance of engine using different fuel compositions. Le moteur HCCI (Homogeneous Charge Compression Ignition, ou à allumage par compression d’une charge homogène est une idée prometteuse pour réduire la consommation de carburant et les émissions polluantes. Le gaz naturel, considéré généralement comme un carburant propre, est un choix approprié pour les moteurs HCCI en raison de sa capacité à former avec l’air un mélange homogène. Cependant, la composition du gaz naturel influe fortement sur les caract

Oklo natural reactor. Study of uranium and rare earths migration on a core drilled through a reaction zone. Application to determination of the date of the nuclear reaction by measurement of fission products

International Nuclear Information System (INIS)

Ruffenach, J.C.

1977-01-01

Isotopic and chemical analysis of uranium and five rare earths: neodymium, samarium, europium, gadolinium and dysprosium were effected on fourteen samples taken in the same core drilled through a reaction zone of the Oklo uranium deposit. This study points out the general stability of uranium and fission rare earths; spatial distributions of these elements are quite analogous. Migrations have affected about 5% only of fission neodymium in the core of the reaction zone; corresponding values for samarium and gadolinium are slightly higher. These migration phenomena have carried rare earths to no more than 80 cm out of the core. By study of the europium it is shown that nuclear reactions have stayed in the ground since the time of reactions. On the other hand it is shown by analysis of the dysprosium that rare earths have not undergone an important movement. This study allow also the datation of nuclear reactions from the measurement of the quantity of fission neodymium produced. A value of 1.98x10 9 years is obtained slightly higher than the value obtained by geochronology [fr

L’éducation à la gestion des risques naturels dans le manuel de géographie de la 1ère année secondaire en Tunisie : analyse didactique et propositions

OpenAIRE

Harzalli, Fadhel

2016-01-01

L’introduction de l’éducation à la gestion des risques naturels dans les programmes et les manuels est récente dans l’enseignement de la géographie en Tunisie. En effet, l’éducation à la gestion des risques peut être considérée comme un champ éducatif émergeant et un ensemble d’interventions qui vise à informer, motiver et aider les apprenants à adopter volontairement des comportements favorables à la vie, et à se construire une opinion raisonnée sur des questions vives où l’intime et le soci...

Uranium transport around the reactor zone at Okelobondo (Oklo). Data evaluation with M3 and HYTEC

International Nuclear Information System (INIS)

Gurban, I.; Laaksoharju, M.; Made, B.; Ledoux, E.

1999-12-01

The Swedish Nuclear Fuel and Waste Management Company (SKB) is conducting and participating in Natural Analogue activities as part of various studies regarding the final disposal of high level nuclear waste (HLW). The aim of this study is to use the hydrogeological and hydrochemical data from Okelobondo (Oklo Natural Analogue) to compare the outcome of two independent modelling approaches (HYTEC and M3). The modelling helps to evaluate the processes associated with nuclear natural reactors such as redox, adsorption/desorption and dissolution/precipitation of the uranium and to develop more realistic codes which can be used for site investigations and data evaluation. HYTEC (1D and 2D) represents a deterministic, transport and multi-solutes reactive coupled code developed at Ecole des Mines de Paris. M3 (Multivariate Mixing and Mass balance calculations) is a mathematical-statistical concept code developed for SKB. M3 can relatively easily be used to calculate mixing portions and to identify sinks or sources of element concentrations that may exist in a geochemical system. M3 helped to address the reactions in the coupled code HYTEC. Thus, the major flow-paths and reaction paths were identified and used for transport evaluation. The reactive transport results (one-dimensional and two-dimensional simulations) are in good agreement with the statistical approach using the M3 model. M3 and HYTEC show a dissolution of the uranium layer in contact with upwardly oxidising waters. M3 and HYTEC show a gain of manganese rich minerals downstream the reactor. A comparison of the U and Mn plots for M3 deviation and HYTEC results showed an almost mirror behaviour. The U transport stops when the Mn gain increases. Thus, HYTEC and M3 modelling predict that a possible reason for not having U transport up to the surface in Okelobondo is due to an inorganic trap which may hinder the uranium transport. The two independent modelling approaches can be used to complement each other and to

La marque «Parc Naturel Régional» :un dispositif original pour valoriser des stratégies de développement durable fondées sur les ressources agricoles et agroalimentaires des territoires insulaires ultramarins

Directory of Open Access Journals (Sweden)

Armelle Caron

2009-06-01

Full Text Available Les Parcs Naturels Régionaux (PNR français créés en 1967 constituent de véritables laboratoires pour la mise en œuvre d’un développement durable avant la lettre. Ils ont expérimenté diverses initiatives visant à valoriser la conservation des patrimoines naturel et culturel de leur territoire, notamment une politique de marquage de produits et de services territorialement ancrés. Dans cet article, nous nous interrogeons sur la pertinence de ces instruments de développement local pour les territoires insulaires à partir de l'exemple de la politique de marquage mise en œuvre par le PNR de la Martinique. Nous intéressant plus particulièrement aux impacts des démarches de marquage en termes de dynamique d’action collective, nous centrons notre analyse sur la dimension « sociale » de la durabilité.French Regional Nature Parks (RNP, created in 1967, can be considered as precursory sustainable development laboratories. Different initiatives dedicated to promote local development and draw benefits from the improved status of sustainably managed areas have been implemented in the RNP and among them a labelling policy through the development of RNP collective trademarks. In this article, we wonder about the consistency of this RNP labelling policy for the French overseas department of Martinique. According to our analytical references (local governance and collective action, we focus on the social dimension of sustainable development.

Algeria facing the challenges of Europe natural gas supply and the respect of the environment.; L'Algerie face aux defis de l'approvisionnement de l'Europe en gaz naturel et le respect de l'environnement

Energy Technology Data Exchange (ETDEWEB)

Ali, Nadia Nait

2010-09-15

Taking into account the expectations, for the next decades, of a strong increase in the demand for gas in Europe, Algeria has committed to large structuring projects, adding to the two gas pipeline linking Algeria to Spain via Morocco and Algeria to Italy via Tunisia. Two more undertakings are added linking Algeria directly to two European partners. Sonatrach will play an important role in global environment protection, natural gas being less polluting than oil and coal and emitting less co2. Substitution of coal by natural gas will generate socio economical advantages and will preserve the environment. [French] Compte tenu des attentes, pour les decennies prochaines, d'une forte croissance de la demande de gaz en Europe, l'Algerie s'est engagee dans de grands projet structurants s'ajoutant aux deux gazoducs reliant l'Algerie a l'Espagne via le Maroc et l'Algerie a l'Italie via la Tunisie, viennent s'ajouter deux autres ouvrages reliant directement l'Algerie a deux partenaires europeens. Sonatrach Jouera un role important dans la protection de l'environnement a l'echelle mondiale, le gaz naturel est moins polluants que le petrole, le charbon et emet moins de co2. La substitution du charbon par le gaz naturel generera des avantages socio-economiques, preservation de l'environnement.

Long term developments in irradiated natural uranium processing costs. Optimal size and siting of plants; Perspectives a long terme des couts de traitement de l'uranium naturel irradie. Tailles et localisations optimales des usines

Energy Technology Data Exchange (ETDEWEB)

Thiriet, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Oger, C; Vaumas, P de [Saint-Gobain Nucleaire, 92 - Courbevoie (France)

1964-07-01

processing plants are shown, different from those in part two. The indirect effect of these reprocessing programmes on the availability of plutonium, and therefore on the possibility.of undertaking plutonium burning reactor programmes, must be taken into account. (authors) [French] L'objet de cette communication est d'apporter une contribution a la solution du probleme du choix des tailles et des localisations optimales des usines de traitement des combustibles nucleaires irradies, associees a des programmes de puissance electrique installee. Dans une premiere partie, on etudie la structure des couts d'investissements et d'exploitation des usines de traitement de l'uranium naturel irradie, l'influence de la taille des usines sur ces couts et ces structures de couts. Au cout de traitement de l'uranium naturel irradie s'ajoute d'autre part le cout du transport des combustibles irradies des lieux de production aux sites des usines de traitement. La recherche du cout minimum pour la production d'un pays ou d'un ensemble de pays fait donc intervenir a la fois la taille et la localisation des usines. On indique les couts de transport previsibles pour l'uranium naturel irradie et la structure de ces couts (transport, assurance, couts et amortissement des containers). Dans une deuxieme partie, et pour differents echeanciers de combustibles irradies a traiter chaque annee, on determine les tailles et les localisations optimales des usines de traitement et la sensibilite de ces resultats, aux hypotheses de base concernant le cout du traitement, le cout du transport, l'annee de demarrage du programme d'usines, l'horizon choisi. - le probleme de nature combinatoire, assez complexe, est resolu par l'application des methodes de la programmation dynamique. - on montre que les methodes sont egalement applicables au probleme du choix des tailles et des localisations optimales des usines de traitement des elements du type MTR, associees aux programmes de reacteurs de recherche ainsi qu

Bed and bed-site reuse by western lowland gorillas (Gorilla g. gorilla) in Moukalaba-Doudou National Park, Gabon.

Science.gov (United States)

Iwata, Yuji; Ando, Chieko

2007-01-01

In this paper we describe bed (nest) and bed-site reuse by western lowland gorillas (Gorilla g. gorilla) in Moukalaba-Doudou National Park, south-eastern Gabon. During an eight-month study 44 bed sites and 506 beds were found. Among these, 38.6% of bed sites and 4.1% of beds were reused. We analyzed the monthly frequency of bed-site reuse in relation to rainfall, fruit abundance, and fruit consumption by the gorillas. The different frequency of bed-site reuse in the rainy and dry seasons was not significant. More bed-site reuse was observed during the fruiting season than during the non-fruiting season. Results from fecal analysis suggested that gorillas ate more fruit in the fruiting season than in the non-fruiting season. The frugivorous diet of western gorillas may possibly cause gorillas to stay in some areas and, consequently, reuse their bed sites. Reuse of bed sites by gorillas suggests their frequent return to an area where preferred fruit is readily available. A higher percentage of arboreal beds may also affect bed-site reuse, because of the shortage of bed material.

Risky sexual behaviour among women: Does economic empowerment matter? Case of Gabon, Mozambique, Sierra-Leone and Zambia.

Science.gov (United States)

Odimegwu, Clifford O; De Wet, Nicole; Banda, Pamela C

2016-12-01

The link between economic empowerment and high risky sexual behaviour has been debated by different scholars in various settings. However, no consistently clear connection between poverty and lack of education has been found regarding engagement in risky sexual behaviour. Also, not much research has been done to examine the strength of these relationships for adolescents and women. The objectives of this study were to assess the relationship between female economic empowerment and risky sexual behaviour in Africa. Using the latest Demographic and Health Surveys Data (DHS 2011-2014) from Gabon, Mozambique, Sierra Leone and Zambia, univariate, bivariate and multivariate analysis was done on women aged 15 to 49 to examine the patterns of and differences in the association between women's economic empowerment and risky sexual behaviour. The findings both at community and individual level indicate that empowered women (higher education and wealth household) and adolescents aged 15 to 19 are highly significantly associated with engagement in high risky behaviour. The result of this study stresses the need to look further than individual factors in the quest to resolve risky sexual behaviour in Africa. The interrelations between female economic empowerment and engagement in risky sexual behaviour are more complicated and less straightforward than usually presumed.

Malaria, from natural to supernatural: a qualitative study of mothers' reactions to fever (Dienga, Gabon).

Science.gov (United States)

Pilkington, Hugo; Mayombo, Justice; Aubouy, Nicolas; Deloron, Philippe

2004-10-01

Decision making for health care at the household level is a crucial factor for malaria management and control among young children. This study sought to determine exactly how mothers reacted when faced with fever in a child. Qualitative study based on in depth semistructured interviews of mothers and free form discussion with traditional healers (Nganga). Village of Dienga, a rural area of Gabon (Central Africa). 12 mothers and three traditional healers. All mothers thought that fever and malaria were identical. Mothers home treated or went to the village treatment centre, or both, on the last episode of fever, if they judged it to be "natural" fever. However, if fever was thought to be a result of malicious intent, then a Nganga was consulted first. It was believed that strong and above all persistent fever was "supernatural". In this case, traditional treatment was thought to be best. Results indicate that fever is perceived as a dual condition, with two distinct but non-mutually exclusive aetiologies (either "natural" or from witchcraft). In contrast with what is commonly believed, there seems to be no clear cut distinction between diseases suitable for management by western medicine and diseases to be managed solely by traditional health practitioners. Moreover, these data do not support the commonly held notion that the decision to seek western medicine to treat fever is considered a "last resort". Results strongly imply that some severe cases of fever, being initially considered supernatural, may partially or completely escape medical attention.

Identification and molecular characterization of novel primate bocaparvoviruses from wild western lowland gorillas of Moukalaba-Doudou National Park, Gabon.

Science.gov (United States)

Nze-Nkogue, Chimene; Horie, Masayuki; Fujita, Shiho; Inoue, Eiji; Akomo-Okoue, Etienne-François; Ozawa, Makoto; Ngomanda, Alfred; Yamagiwa, Juichi; Tsukiyama-Kohara, Kyoko

2017-09-01

Bocaparvoviruses have been studied extensively owing to their ability to cause respiratory illness or gastroenteritis in humans. Some bocaparvoviruses have been detected in non-human primates (gorillas and chimpanzees), but the diversity and evolution of these viruses are not fully understood. In this study, we collected 107 fecal samples from wild western lowland gorillas in Moukalaba-Doudou National Park in Gabon to investigate the presence of bocaparvoviruses. Using a combination of pan-bocaparvovirus PCR and individual identification by microsatellite genotyping, we found that two samples from two apparently healthy infant gorillas were positive for bocaparvovirus. Sequencing and phylogenetic analyses revealed that the two gorilla bocaparvovirus strains are nearly identical and are closely related to viruses in the species Primate bocaparvovirus 2 (with 86.0% nucleotide identity to a human bocavirus 2 isolate). To our knowledge, this is the first report showing the presence of a non-human primate bocaparovirus within Primate bocaparvovirus 2. Our findings provide novel insights into the diversity and evolution of bocaparvoviruses and highlight the importance of surveying these viruses for the safe management of gorilla-based ecotourism. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasma levels of artesunate and dihydroartemisinin in children with Plasmodium falciparum malaria in Gabon after administration of 50-milligram artesunate suppositories.

Science.gov (United States)

Halpaap, B; Ndjave, M; Paris, M; Benakis, A; Kremsner, P G

1998-03-01

A thermostable suppository of artesunate (artesunic acid) has been developed. In Gabon, 12 children with Plasmodium falciparum malaria received two administrations of this suppository in a 4-hr interval. Parasitemia and fever were then measured and the plasma levels of artesunate and its active metabolite, dihydroartemisinin, were determined by means of a reversed phase high-pressure liquid chromatography method using reductive electrochemical detection. Substantial parasite clearance (97-100%) was noted 24 hr after the beginning of the treatment and body temperature had returned to normal. Absorption, metabolism, and elimination of artesunate were rapid. Mean values of maximum plasma levels (Cmax) and maximum concentration peak times (tmax) were evaluated. The Cmax of dihydroartemisinin (0.18 +/- 0.10 microg/ml [mean +/- SE]) was higher than the Cmax of artesunate (0.09 +/- 0.04 microg/ml) and the tmax of dihydroartemisinin (1.13 +/- 0.58 hr) was higher than the tmax of artesunate (0.58 +/- 0.19 hr). Plasma levels 30 min after the second suppository administration were not consistently higher than those found 30 min after the first administration.

Assessment of LED fluorescence microscopy for the diagnosis of Plasmodium falciparum infections in Gabon

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Biallas Barbara

2011-07-01

Full Text Available Abstract Background Rapid and accurate diagnosis of malaria is central to clinical management and the prevention of drug-overuse, which may lead to resistance development, toxicity and economic losses. So far, light microscopy (LM of Giemsa-stained thick blood smears is the gold standard. Under optimal conditions the procedure is fast and reliable; nevertheless a gain in speed would be a great advantage. Rapid diagnosis tests are an alternative, although they cost more and give qualitative instead of quantitative results. Light-emitting diode (LED fluorescence microscopy (ledFM 400 ×, 1000 × may offer a reliable and cheap alternative, which can be used at the point of care. Methods LedFM and conventional fluorescence microscopy (uvFM were compared to LM in 210 samples from patients with history of fever in the last 24 hours admitted to the Albert Schweitzer Hospital in Lambaréné, Gabon. Results Sensitivities were 99.1% for ledFM and 97.0% for uvFM, specificities 90.7% for ledFM 400 × and 92.6% for ledFM 1000 × and uvFM. High agreement was found in Bland-Altman-plot and Kappa coefficient (ledFM 1000 ×: 0.914, ledFM 400 × and uvFM: 0.895. The time to diagnosis for both FM methods was shorter compared to LM (LM: 43 min, uvFM: 16 min, ledFM 1000 ×: 14 min, ledFM 400 ×: 10 min. Conclusion ledFM is a reliable, accurate, fast and inexpensive tool for daily routine malaria diagnosis and may be used as a point of care diagnostic tool.

Risques naturels: de la géophysique à l'approche institutionnelle

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1996-01-01

Full Text Available Les limites de l’approche physique des risques naturels ont conduit à une collaboration novatrice des sciences sociales, particulièrement en matière de prévention et de gestion des risques. Mais dans l’approche physique, la prise en compte indispensable des comportements humains face aux risques, ne revient-elle pas à juxtaposer une Population plus ou moins sensible aux dangers encourus et une Administration plus ou moins efficace ? Une approche institutionnelle devrait pleinement prendre en compte le facteur spécifique que constituent les pouvoirs publics pour définir une politique de prévention qui soit en phase, non pas avec un idéal technique inaccessible en particulier dans les sociétés en développement, mais avec un optimum social. RIESGOS NATURALES: ENTRE LA GEOFÍSICA Y LA APROXIMACIÓN INSTITUCIONAL. Las limitaciones de la perspectiva física de los riesgos naturales han implicado una colaboración novedosa de las ciencias sociales en particular a nivel de la prevención y del manejo público de los riesgos. Sin embargo, en la perspectiva física, ¿la incorporación de los comportamientos humanos frente a los riesgos no consiste en una yuxtaposición de una Población más o menos sensible a los peligros y una Administración más o menos eficiente? Una aproximación institucional debería considerar totalmente el factor específico que representan los poderes públicos para definir una política de prevención que sea compatible, no con un ideal técnico inalcanzable en particular en las sociedades en desarrollo, sino con un óptimo social. NATURAL HAZARDS: BETWEEN THE GEOPHYSICS AND THE INSTITUTIONAL APPROACH. The limitations of the physical perspective on natural hazards have required the contribution of the social sciences, especially for the mitigation and the management of risks. But in the physical approach, the analysis of human behavior in the event of natural hazards seems to be limited to the addition of a

Methodology of simultaneous analysis of Uranium and Thorium by nuclear and atomic techniques. Application to the Uranium and Thorium dosing in mineralogic samples

International Nuclear Information System (INIS)

Fakhi, S.

1988-01-01

This work concerns essentially the potential applications of 100 kW nuclear reactor of Strasbourg Nuclear Research Centre to neutron activation analysis of Uranium and Thorium. The Uranium dosing has been made using: 239-U, 239-Np, fission products or delayed neutrons. Thorium has been showed up by means of 233-Th or 233-Pa. The 239-U and 233-Th detection leads to a rapid and non-destructive analysis of Uranium and Thorium. The maximum sensitivity is of 78 ng for Uranium and of 160 ng for Thorium. The Uranium and Thorium dosing based on 239-Np and 233-Pa detection needs chemical selective separations for each of these radionuclides. The liquid-liquid extraction has permitted to elaborate rapid and quantitative separation methods. The sensitivities of the analysis after extraction reach 30 ng for Uranium and 50 ng for Thorium. The fission products separation study has allowed to elaborate the La, Ce and Nd extractions and its application to the Uranium dosing gives satisfying results. A rapid dosing method with a sensitivity of 0.35 microgramme has been elaborated with the help of delayed neutrons measurement. These different methods have been applied to the Uranium and Thorium dosing in samples coming from Oklo mine in Gabon. The analyses of these samples by atomic absorption spectroscopy and by the proton induced X-ray emission (PIXE) method confirm that the neutron activation analysis methods are reliable. 37 figs., 14 tabs., 50 refs

Enquête entomologique dans le foyer historique de trypanosomose humaine africaine de Bendjé (Gabon

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Kohagne Tongué L.

2011-11-01

Full Text Available La situation de la maladie du sommeil est très peu connue au Gabon. De nombreux foyers historiques n’ont pas été prospectés depuis plus de 15 ans. Le foyer historique de Bendjé fournit régulièrement quelques cas, dépistés passivement, qui concernent le plus souvent des pêcheurs dont il est a priori difficile de déterminer le lieu probable de contamination du fait de leur grande mobilité au cours de leurs activités. La présence des hommes infectés dans ce foyer historique pourrait favoriser son réveil s’il existe un contact étroit entre les différents éléments potentiellement présents du cycle épidémiologique (homme, vecteur, trypanosome. Afin de vérifier l’existence éventuelle d’un risque trypanosomien dans ce foyer, nous y avons mené une enquête entomologique. Des pièges ont été posés dans des biotopes fréquentés par l’homme et laissés en place pendant quatre jours. Trois espèces de glossines (Glossina palpalis palpalis, G. pallicera newsteadi et G. caliginea ont été capturées et deux espèces de trypanosomes (Trypanosoma vivax et T. brucei s.l. identifiées par PCR. Ces résultats suggèrent l’existence d’un cycle de transmission animal. Le contact entre les hommes et les glossines est particulièrement étroit dans tous les types de site prospectés, à l’exception de la mangrove.

Patch-occupancy models indicate human activity as major determinant of forest elephant Loxodonta cyclotis seasonal distribution in an industrial corridor in Gabon

Science.gov (United States)

Buij, R.; McShea, W.J.; Campbell, P.; Lee, M.E.; Dallmeier, F.; Guimondou, S.; Mackaga, L.; Guisseougou, N.; Mboumba, S.; Hines, J.E.; Nichols, J.D.; Alonso, A.

2007-01-01

The importance of human activity and ecological features in influencing African forest elephant ranging behaviour was investigated in the Rabi-Ndogo corridor of the Gamba Complex of Protected Areas in southwest Gabon. Locations in a wide geographical area with a range of environmental variables were selected for patch-occupancy surveys using elephant dung to assess seasonal presence and absence of elephants. Patch-occupancy procedures allowed for covariate modelling evaluating hypotheses for both occupancy in relation to human activity and ecological features, and detection probability in relation to vegetation density. The best fitting models for old and fresh dung data sets indicate that (1) detection probability for elephant dung is negatively related to the relative density of the vegetation, and (2) human activity, such as presence and infrastructure, are more closely associated with elephant distribution patterns than are ecological features, such as the presence of wetlands and preferred fresh fruit. Our findings emphasize the sensitivity of elephants to human disturbance, in this case infrastructure development associated with gas and oil production. Patch-occupancy methodology offers a viable alternative to current transect protocols for monitoring programs with multiple covariates.

Oligocene to Holocene sediment drifts and bottom currents on the slope of Gabon continental margin (west Africa). Consequences for sedimentation and southeast Atlantic upwelling

Science.gov (United States)

Séranne, Michel; Nzé Abeigne, César-Rostand

1999-10-01

Seismic reflection profiles on the slope of the south Gabon continental margin display furrows 2 km wide and some 200 m deep, that develop normal to the margin in 500-1500 m water depth. Furrows are characterised by an aggradation/progradation pattern which leads to margin-parallel, northwestward migration of their axes through time. These structures, previously interpreted as turbidity current channels, display the distinctive seismic image and internal organisation of sediment drifts, constructed by the activity of bottom currents. Sediment drifts were initiated above a major Oligocene unconformity, and they developed within a Oligocene to Present megasequence of general progradation of the margin, whilst they are markedly absent from the underlying Late Cretaceous-Eocene aggradation megasequence. The presence of upslope migrating sediment waves, and the northwest migration of the sediment drifts indicate deposition by bottom current flowing upslope, under the influence of the Coriolis force. Such landwards-directed bottom currents on the slope probably represent coastal upwelling, which has been active along the west Africa margin throughout the Neogene.

The Goldwyn diary of November and December 1960, at the Albert Schweitzer Hospital, Lambaréné, Gabon.

Science.gov (United States)

Goldwyn, Robert M; Constantian, Mark B

2012-01-01

Through unexpected circumstances, I went to Lambaréné, in Gabon, to be Dr. Albert Schweitzer's surgeon for 2 months, November and December of 1960.This diary I can honestly say I never thought would become public. The years have passed; I am now 77. I realize that not many of those who served in a medical capacity at his hospital are still alive and not everyone will share his or her experiences.I want to make clear that I was with Dr. Schweitzer only 2 months. I would not want anyone to think that I played a strategic role at the hospital. I did not, but I helped as best I could.Although I have traveled throughout the world and have been a surgeon in many out-of-the-way places, I have not returned to Lambaréné. The reason, I confess, is that I wanted it to remain in my mind as it was. For Dr. Schweitzer and those who served there, his hospital was a way of life. It was a world of its own and, though small, it came into being because of the arching ideals and unflagging dedication of a remarkable man. His example should inspire us to enlarge our personal horizons, not just to recognize the less fortunate but to act without delay on their behalf. For each of us, there is an Ogowe waiting to be crossed.

Anopheles moucheti and Anopheles vinckei are candidate vectors of ape Plasmodium parasites, including Plasmodium praefalciparum in Gabon.

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Christophe Paupy

Full Text Available During the last four years, knowledge about the diversity of Plasmodium species in African great apes has considerably increased. Several new species were described in chimpanzees and gorillas, and some species that were previously considered as strictly of human interest were found to be infecting African apes. The description in gorillas of P. praefalciparum, the closest relative of P. falciparum which is the main malignant agent of human malaria, definitively changed the way we understand the evolution and origin of P. falciparum. This parasite is now considered to have appeared recently, following a cross-species transfer from gorillas to humans. However, the Plasmodium vector mosquito species that have served as bridge between these two host species remain unknown. In order to identify the vectors that ensure ape Plasmodium transmission and evaluate the risk of transfer of these parasites to humans, we carried out a field study in Gabon to capture Anopheles in areas where wild and semi-wild ape populations live. We collected 1070 Anopheles females belonging to 15 species, among which An. carnevalei, An. moucheti and An. marshallii were the most common species. Using mtDNA-based PCR tools, we discovered that An. moucheti, a major human malaria vector in Central Africa, could also ensure the natural transmission of P. praefalciparum among great apes. We also showed that, together with An. vinckei, An. moucheti was infected with P. vivax-like parasites. An. moucheti constitutes, therefore, a major candidate for the transfer of Plasmodium parasites from apes to humans.

Idaho Chemical programs annual technical report, fiscal year 1975

International Nuclear Information System (INIS)

Buckham, J.A.; Bower, .R.; Struhs, R.T.

1976-06-01

The operating experience in fuel processing, waste calcining, and other waste management activities at the ICPP for FY 1975 is summarized. A campaign of coprocessing zirconium and aluminum fuels to recover uranium, the second electrolytic processing campaign to convert recovered and purified uranyl nitrate solution to UO 3 , and four operating periods of the Rare Gas Plant to recover 85 Kr and xenon were successfully completed, with all systems functioning well except for minor difficulties. Support activities include laboratory-scale stability studies of various waste blends; particle size distribution studies of the ICPP stack; evaluation of possible remote radiation measuring methods; tests to estimate corrosion; treatment of fuel storage basin water; progress in development of processes for Rover and HTGR fuels; laboratory testing of filters that deteriorated during the sixth waste calcining campaign; visual inspection of the primary calciner vessel; tests to determine what causes ruthenium to volatilize; various studies in support of future fluidized-bed calcining operations; other waste management activities including studies of the collection and long-term storage of 85 Kr, development of a suitable absorbent for 129 I (I 2 ); and continuing studies in support of the proposed INEL facility for treating transuranic wastes. Research programs in other areas include: determining burnup for fast breeder reactor fuels, continued study of the iodine pathway, development of a fluidized-bed heat exchanger for use with geothermal waters, and involvement in the study of the natural fossil fission reactor at the Oklo mine in Gabon, West Africa

The study of neutron propagation in natural uranium; Etude de la propagation des neutrons dans l'uranium naturel

Energy Technology Data Exchange (ETDEWEB)

Campan, J L; Clauzon, P P; Kirchner, B; Ribon, P; Zaleski, C P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

Fast exponential experiment. Experimental facilities are described; the experimental results obtained with the block of natural uranium are then presented. Detectors used were fission chambers, activation detectors and nuclear emulsions. One tries to explain the results, which are, then compared with theoretical values obtained by calculations based on diffusion theory. Measured spectrum (pseudo equilibrium) may be characterised by the following values: diffusion length: 95,25 {+-} 0,5; {sigma}{sub f}U{sub 235}/{sigma}{sub f}U{sub 238} : 230 {+-} 10, {sigma}{sub f}U{sub 235}/{sigma}{sub f}Np{sub 237} : 14 {+-} 0.5, {sigma}{sub f}U{sub 235}/{sigma}{sub f}U{sub 233} : 0.67 {+-} 0.03, {sigma}{sub f}U{sub 235}/{sigma}{sub f}Pu{sub 239} : 0.90 {+-} 0.05, {sigma}{sub f}U{sub 235}/{sigma}(ny) In : 230 {+-}10. (author) [French] Experience exponentielle rapide. Apres une description du dispositif experimental, on presente des resultats de mesures effectuees dans un massif d'uranium naturel. Les detecteurs utilises sont des chambres a fission, des detecteurs d'activation et des emulsions nucleaires. Une interpretation des resultats est donnee; ceux-ci sont compares a des valeurs theoriques obtenues par des calculs utilisant la theorie de la diffusion. Le spectre mesure (pseudo equilibre) peut etre caracterise par les valeurs suivantes: Longueur de diffusion: 95,25 {+-} 0,5; {sigma}{sub f}U{sub 235}/{sigma}{sub f}U{sub 238} : 230 {+-} 10, {sigma}{sub f}U{sub 235}/{sigma}{sub f}Np{sub 237} : 14 {+-} 0.5, {sigma}{sub f}U{sub 235}/{sigma}{sub f}U{sub 233} : 0.67 {+-} 0.03, {sigma}{sub f}U{sub 235}/{sigma}{sub f}Pu{sub 239} : 0.90 {+-} 0.05, {sigma}{sub f}U{sub 235}/{sigma}(ny) In : 230 {+-}10. (auteur)

The Oklo reactor

International Nuclear Information System (INIS)

McNeil, Russell

1986-01-01

The construction of a reactor, capable of producing a controlled nuclear chain reaction, has been one of the most complex achievements of modern science. That a similar reaction might take place in nature did not play a role in the thinking of the nuclear scientists responsible for it. Yet, 14 years ago, French scientists discovered that just such a phenomenon apparently occurred in western Africa almost 2 billion years ago. In this article Russell McNeil describes this fascinating curiosity and a recent attempt to model it mathematically

Certified and uncertified logging concessions compared in Gabon: changes in stand structure, tree species, and biomass.

Science.gov (United States)

Medjibe, V P; Putz, Francis E; Romero, Claudia

2013-03-01

Forest management certification is assumed to promote sustainable forest management, but there is little field-based evidence to support this claim. To help fill this gap, we compared a Forest Stewardship Council (FSC)-certified with an adjacent uncertified, conventionally logged concession (CL) in Gabon on the basis of logging damage, above-ground biomass (AGB), and tree species diversity and composition. Before logging, we marked, mapped, and measured all trees >10 cm dbh in 20 and twelve 1-ha permanent plots in the FSC and CL areas, respectively. Soil and tree damage due to felling, skidding, and road-related activities was then assessed 2-3 months after the 508 ha FSC study area and the 200 ha CL study area were selectively logged at respective intensities of 5.7 m(3)/ha (0.39 trees/ha) and 11.4 m(3)/ha (0.76 trees/ha). For each tree felled, averages of 9.1 and 20.9 other trees were damaged in the FSC and CL plots, respectively; when expressed as the impacts per timber volume extracted, the values did not differ between the two treatments. Skid trails covered 2.9 % more of the CL surface, but skid trail length per unit timber volume extracted was not greater. Logging roads were wider in the CL than FSC site and disturbed 4.7 % more of the surface. Overall, logging caused declines in AGB of 7.1 and 13.4 % at the FSC and CL sites, respectively. Changes in tree species composition were small but greater for the CL site. Based on these findings and in light of the pseudoreplicated study design with less-than perfect counterfactual, we cautiously conclude that certification yields environmental benefits even after accounting for differences in logging intensities.

Nuclear waste criticality analysis. Quarterly progress report, 1 October--31 December 1995

International Nuclear Information System (INIS)

Culbreth, W.G.

1996-01-01

The work to date includes the preparation of a report related to criticality in spent fuel, a report on the Oklo reactors and their relevance to Yucca Mountain, and the creation of a computer program to model the Oklo reactors. The objective of the program includes a computational model of the only known natural analogue to an underground nuclear waste repository and the possible application of the model to predict the long-term behavior of Yucca Mountain. A final summary of all work completed will be presented after the end of the project on February 29, 1996

Natural repository analogue program. Progress report, July 1-September 30, 1981

International Nuclear Information System (INIS)

Curtis, D.B.

1982-03-01

A report on the immobilization of uranium in the earth's crust has been completed. Techniques have been developed to do a comprehensive mass inventory of the Oklo reactor zones. These techniques were applied to a compilation of data from Oklo zones 2 and 3-4. The study shows large deficiencies of neodymium, ruthenium, and mass 99 elements ( 99 Tc or 99 Ru) in the reactor zones. The extent of these deficiencies are correlated with the intensity of the nuclear reactions. Analyses of ores from the Key Lake uranium mineralization show that 60 to 70% of the radiogenic lead is missing from the ores

Therapeutic and prophylactic effect of intermittent preventive anti-malarial treatment in infants (IPTi from Ghana and Gabon

Directory of Open Access Journals (Sweden)

Kreuels Benno

2008-10-01

Full Text Available Abstract Background Intermittent preventive treatment in infants (IPTi with sulphadoxine-pyrimethamine (SP reduces the incidence of malaria episodes in young children. The exact mechanism by which the protective effect is mediated needs to be defined. This study aimed to investigate therapeutic, prophylactic, and possible exceeding effects of SP-based IPTi in two clinical trials. Methods Protective efficacies from two IPTi trials performed in Kumasi, Ghana, and Lambaréné, Gabon, were assessed for overlapping time series of 61 days. For six-months periods after each of three IPTi doses a multivariate Poisson regression model with the respective cohort as co-variate was generated and effect modification of protective efficacy with time strata was evaluated by log-likelihood tests. Results Protective efficacies were not significantly different between the two study cohorts. Study-cohort corrected protective efficacy was highest for the first 61 days after each IPTi application and decreased continuously. For the first 61 days after IPTi-1, IPTi-2, and IPTi-3 the protective efficacy was 71%, 44%, and 43%, respectively. A reduction of the malaria incidence rate was detectable for the first 60, 30 and 40 days after IPTi-1, IPTi-2 and IPTi-3 drug application, respectively. After IPTi-3 a higher risk for malaria could be seen after day 60. This effect was mainly based on the overwhelming influence of the Kumasi cohort. Conclusion The results suggest that SP-based IPTi mainly works through a therapeutic and prophylactic effect over 30 to 60 days after drug application and that a sustained effect beyond post-treatment prophylaxis might be very low. Trial registration Data analysis from clinical trials NCT ID # 00206739 (Kumasi Trial and NCT ID # 00167843 (Lambaréné Trial, http://www.clinicaltrials.gov.

Low prevalence of HCV infection with predominance of genotype 4 among HIV patients living in Libreville, Gabon.

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Angélique Ndjoyi-Mbiguino

Full Text Available Gabon is an endemic area for human immunodeficiency virus (HIV and hepatitis C virus (HCV and the risk of co-infection is high.Between November 2015 and April 2016, we conducted retrospective study on HCV infection among people living with HIV/AIDS (PLHA. A total of 491 PLHA were included in this study and tested for the presence of HCV infection. HIV viral loads were obtained using the Generic HIV viral Load® assay and the CD4+ T cells count was performed using BD FACSCount™ CD4 reagents. HCV screening was performed using the MP Diagnostics HCV ELISA 4.0 kit. HCV genotypes were determined by sequence analysis of NS5B and Core regions. The Mann-Whitney test was used to compare the groups. Chi-2 test and Fisher's Exact Test were used to compare prevalence.HCV seroprevalence was 2.9% (14/491, (95% confidence interval (CI:1.4-4.3%. The percentage of HCV viremic patients, defined by the detection of HCV RNA in plasma, was 57% (8/14, representing 1.6% of the total population. HCV seroprevalence and replicative infection were not statistically differ with gender. The percentage of co-infection increased with age. No correlation with CD4+ T cells count and HIV viral load level was registered in this study. Identified HCV strains were predominantly of genotype 4 (87.5% including 4k, 4e, 4g, 4p, 4f and 4c subtypes. Only one strain belonged to genotype 2 (subtype 2q. Analysis of the NS5B region did not reveal the presence of resistance-associated substitutions for sofosbuvir.A systematic screening of hepatitis C is therefore strongly recommended as well as genotyping of HCV strains in order to adapt treatments for the specific case of people living with HIV/AIDS in Central Africa.

Investigations of subterranean microorganisms and their importance for performance assessment of radioactive waste disposal. Results and conclusions achieved during the period 1995 to 1997

Energy Technology Data Exchange (ETDEWEB)

Pedersen, K [Goeteborg Univ. (Sweden). Dept. of General and Marine Microbiology

1997-11-01

In 1987, microbiology became a part of the Swedish scientific program for the safe disposal of high level nuclear waste (HLW). The goal of the microbiology sub-program is to understand how subterranean microorganisms will interact with the performance of a future HLW repository. The Swedish research program on subterranean microbiology has mainly been performed at two sites in granitic rock aquifers at depths ranging from 70 m down to 1240 m; the Stripa research mine in the middle of Sweden and the Aespoe hard rock laboratory (HRL) situated on the south eastern coast of Sweden. Some work has also been performed in co-operation with other national or international research groups in Sweden, Canada and at the natural analogue sites in Oklo in Gabon and Maqarin in Jordan. The most recent report in the SKB technical report series on microbiology and performance assessment, SKB-TR--95-10, gave the state of the art regarding microorganisms and their importance for performance assessment. That report is recommended as a source of knowledge about basic microbiology, microbial ecology of subterranean environments and the nuclear waste disposal concept in a microbiological perspective. The present report summarises results and conclusions achieved during the period 1995 to 1997 and is a continuation of SKB TR 95-10. The report is structured as summary which explains and analyses the obtained results and conclusions in a performance assessment perspective. The scientific basis for the summary is an enclosed series of eleven papers of which eight have gone through an international peer review process for publication in international scientific journals and reports and papers published earlier. 413 refs, 56 figs, 39 tabs.

Investigations of subterranean microorganisms and their importance for performance assessment of radioactive waste disposal. Results and conclusions achieved during the period 1995 to 1997

International Nuclear Information System (INIS)

Pedersen, K.

1997-11-01

In 1987, microbiology became a part of the Swedish scientific program for the safe disposal of high level nuclear waste (HLW). The goal of the microbiology sub-program is to understand how subterranean microorganisms will interact with the performance of a future HLW repository. The Swedish research program on subterranean microbiology has mainly been performed at two sites in granitic rock aquifers at depths ranging from 70 m down to 1240 m; the Stripa research mine in the middle of Sweden and the Aespoe hard rock laboratory (HRL) situated on the south eastern coast of Sweden. Some work has also been performed in co-operation with other national or international research groups in Sweden, Canada and at the natural analogue sites in Oklo in Gabon and Maqarin in Jordan. The most recent report in the SKB technical report series on microbiology and performance assessment, SKB-TR--95-10, gave the state of the art regarding microorganisms and their importance for performance assessment. That report is recommended as a source of knowledge about basic microbiology, microbial ecology of subterranean environments and the nuclear waste disposal concept in a microbiological perspective. The present report summarises results and conclusions achieved during the period 1995 to 1997 and is a continuation of SKB TR 95-10. The report is structured as summary which explains and analyses the obtained results and conclusions in a performance assessment perspective. The scientific basis for the summary is an enclosed series of eleven papers of which eight have gone through an international peer review process for publication in international scientific journals and reports and papers published earlier

Uraninite alteration in an oxidizing environment and its relevance to the disposal of spent nuclear fuel

International Nuclear Information System (INIS)

Finch, R.; Ewing, R.

1990-12-01

Uraninite is a natural analogue for spent nuclear fuel because of similarities in structure and chemistry. Effective assessment of the long-term behavior of spent fuel in a geologic repository requires a knowledge of the corrosion products produced in that environment. Several important natural analogue sites are reviewed, illustrating a wide variety of environments from oxidizing to reducing, including, among others: Cigar Lake, Canada, a uraninite-bearing ore body at depth within a strictly reducing environment; the ore body has 'seen' extensive groundwater interaction with virtually no significant oxidation or mobilization of U apperent. Koongara, Australia is a highly altered uraninite-bearing ore body partially exposed to meteoric water; alteration at depth has resulted from interaction with groundwater having a somewhat reduced Eh compared to the surface. Uraninite, Pb-uranyl oxide hydrates and uranyl silicates control U solubility at depth; uranyl phosphates and U adsorption onto clays and FeMn-oxides control U solubility near the surface. Pocos de Caldas, Brazil displays a redox from moving through uraninite-bearing rocks near the surface and shows local remobilization of U. Oklo, Gabon, a uraninite- and coffinite-bearing ore body, locally affected by intense hydrothermal alteration during fission reactions, demonstrates restricted radionuclide and fission product transport within a reducing environment. A current study being conducted by the authors at Shinkolbwe, Zaire, a uraninite-bearing ore body exposed to highly oxidizing conditions at the surface, provides over 50 species of uranyl phases for detailed study, and illustrates a complex uranyl phase paragenesis over several million years, from earliest-formed uranyl oxide hydrates and uranyl silicates to later-formed uranyl phosphate. (au) (268 refs.)

Ecological Importance of Small-Diameter Trees to the Structure, Diversity and Biomass of a Tropical Evergreen Forest at Rabi, Gabon.

Science.gov (United States)

Memiaghe, Hervé R; Lutz, James A; Korte, Lisa; Alonso, Alfonso; Kenfack, David

2016-01-01

Tropical forests have long been recognized for their biodiversity and ecosystem services. Despite their importance, tropical forests, and particularly those of central Africa, remain understudied. Until recently, most forest inventories in Central Africa have focused on trees ≥10 cm in diameter, even though several studies have shown that small-diameter tree population may be important to demographic rates and nutrient cycling. To determine the ecological importance of small-diameter trees in central African forests, we used data from a 25-ha permanent plot that we established in the rainforest of Gabon to study the diversity and dynamics of these forests. Within the plot, we censused 175,830 trees ≥1 cm dbh from 54 families, 192 genera, and 345 species. Average tree density was 7,026 trees/ha, basal area 31.64 m2/ha, and above-ground biomass 369.40 Mg/ha. Fabaceae, Ebenaceae and Euphorbiaceae were the most important families by basal area, density and above-ground biomass. Small-diameter trees (1 cm ≥ dbh tree population, 16.5% of basal area, and 4.8% of the above-ground biomass. They also had diversity 18% higher at family level, 34% higher at genus level, and 42% higher at species level than trees ≥10 cm dbh. Although the relative contribution of small-diameter trees to biomass was comparable to other forests globally, their contribution to forest density, and diversity was disproportionately higher. The high levels of diversity within small-diameter classes may give these forests high levels of structural resilience to anthropogenic/natural disturbance and a changing climate.

Using genetic profiles of African forest elephants to infer population structure, movements, and habitat use in a conservation and development landscape in Gabon.

Science.gov (United States)

Eggert, L S; Buij, R; Lee, M E; Campbell, P; Dallmeier, F; Fleischer, R C; Alonso, A; Maldonado, J E

2014-02-01

Conservation of wide-ranging species, such as the African forest elephant (Loxodonta cyclotis), depends on fully protected areas and multiple-use areas (MUA) that provide habitat connectivity. In the Gamba Complex of Protected Areas in Gabon, which includes 2 national parks separated by a MUA containing energy and forestry concessions, we studied forest elephants to evaluate the importance of the MUA to wide-ranging species. We extracted DNA from elephant dung samples and used genetic information to identify over 500 individuals in the MUA and the parks. We then examined patterns of nuclear microsatellites and mitochondrial control-region sequences to infer population structure, movement patterns, and habitat use by age and sex. Population structure was weak but significant, and differentiation was more pronounced during the wet season. Within the MUA, males were more strongly associated with open habitats, such as wetlands and savannas, than females during the dry season. Many of the movements detected within and between seasons involved the wetlands and bordering lagoons. Our results suggest that the MUA provides year-round habitat for some elephants and additional habitat for others whose primary range is in the parks. With the continuing loss of roadless wilderness areas in Central Africa, well-managed MUAs will likely be important to the conservation of wide-ranging species. © 2013 Society for Conservation Biology.

Some economic aspects of natural uranium graphite gas reactor types. Present status and trends of costs in France; Quelques aspects economiques de la filiere uranium naturel - Graphite - gaz. Etat actuel et tendance des couts en France

Energy Technology Data Exchange (ETDEWEB)

Gaussens, J; Tanguy, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Leo, B [Electricite de France (EDF), 75 - Paris (France)

1964-07-01

reduction in investment costs can be obtained without relying on fuel enrichment, and that this development is accompanied moreover by improvements in the operational safety of the reactor. The economic aspects of the main technical problems entailed by these developments are discussed: loading and unloading machines, blowers etc... (authors) [French] Dans une premiere partie, on situe l'interet economique de l'utilisation de l'uranium naturel comme combustible. Cet interet reside a la fois dans le nombre limite et la simplicite relative des operations de mise en forme des elements combustibles, dans le faible cout du produit fini par kwh et dans les immobilisations modestes en capital qu'implique ce cycle par rapport ou cycle de l'uranium enrichi. Tous ces elements permettent de reduire le caractere aleatoire des evaluations des couts, particulierement marque dans le cas de l'uranium enrichi, en raison de la complexite de son cycle et des incertitudes concernant le prix du plutonium. Enfin, la diversite des sources d'approvisionnement en concentre d'uranium naturel opposee au quasi monopole actuel de la separation isotopique, et le faible cout du stockage de ce concentre, offrent des garanties en matiere de securite d'approvisionnement et d'independance economique et politique appreciables par rapport a l'uranium enrichi. En ce qui concerne l'ensemble des capitaux immobilises, on montre que si le cout des centrales au graphite-gaz est plus eleve que celui des centrales eau legere pour certaines gammes de puissance, ce resultat est fortement nuance des que l'on fait intervenir dans un souci d'independance nationale le cout de l'equipement de production des combustibles de l'une et l'autre filiere. Enfin, le cout marginal de la puissance du reacteur au graphite est faible, ses limitations technologiques ont considerablement recule (grace en particulier a l'utilisation du beton precontraint). On sait que la tendance actuelle est a l'accroissement de la puissance unitaire des

Des risques « naturels » aux politiques urbaines à Mexico

Directory of Open Access Journals (Sweden)

François Mancebo

2009-07-01

Full Text Available L’agglomération de Mexico, à plus de 2 000 mètres d’altitude, adossée à la Sierra Madre et la Cordillère Volcanique est assise sur un site accueillant mais redoutable. Il s’agit d’un des endroits les plus exposés du globe, soumis à une combinaison de risques naturels, de risques technologiques souvent mal maîtrisés dus à des industries lourdes, de nuisances, de cumul des polluants et d’un épuisement des ressources locales utilisables, tout particulièrement les ressources en eau. Après le séisme dévastateur de 1985, les acteurs de l’aménagement de Mexico tentent d’intégrer risques et durabilité dans la définition de nouvelles politiques urbaines. Mais, si les risques sont bien identifiés et des réponses sont données, leur applicabilité est quasi-nulle. Une approche normative et n’incluant pas l’ensemble de l’agglomération, mais utilisant les périphéries pour améliorer la durabilité des centres (sorte de durabilité importée à l’échelle de la métropole explique cette situation. Comme dans le mythe de Sisyphe, acteurs locaux et nationaux tentent de faire remonter la pente au rocher du risque mais ce dernier finit toujours par redescendre ? C’est qu’en réalité le problème n’est pas le rocher. Le problème, c’est la pente, c’est-à-dire le substrat fait de représentations territoriales et d’usages de l’espace qui fondent la société mexicaine, sur laquelle roule le rocher.Mexico City is located at an altitude of over 2 000 metres where it occupies an attractive but hazardous site hemmed in by the Sierra Madre and volcanic mountain ranges.The site is one of the most disaster-prone locations in the world, threatened by a combination of natural hazards, poorly controlled technological hazards created by the city’s heavy industry, pollution – particularly air pollution and diminishing local resources, the most seriously threatened being water. Since the devastating earthquake

Capital and operating costs of irradiated natural uranium reprocessing plants; Couts d'investissement et d'exploitation des usines de retraitement de l'uranium naturel irradie

Energy Technology Data Exchange (ETDEWEB)

Thiriet, L; Jouannaud, C; Couture, J; Duboz, J [Commissariat a l' Energie Atomique (France). Centre d' Etudes Nucleaires; Oger, C [Saint Gobain Nucleaire (France)

1966-07-01

This paper presents first a method of analysing natural uranium reprocessing plants investment costs (method similar to LANG and BACH well known in the fuel oil industry) and their operating costs (analysed according to their economic type). This method helps establishing standard cost structures for these plants, allowing thus comparisons between existing or planned industrial facilities. It also helps evaluating the foreseeable consequences of technical progress. Some results obtained are given, concerning: the investment costs sensitivity to the various technical parameters defining the fuel and their comparison according to the country or the economic area taken into account. Finally, the influence of the plants size on their investment costs is shown. (author) [French] La communication expose d'abord une methode d'analyse des couts d'investissement des usines de retraitement de l'uranium naturel irradie (inspiree de celles de LANG et de BACH, bien connues dans l'industrie petroliere) et de leurs couts d'exploitation (selon leur nature economique). Cette methode permet d'etablir des structures types de couts de ces usines et de comparer les realisations industrielles et les projets. Elle facilite l'exploration des consequences previsibles du progres technique. On indique un certain nombre de resultats obtenus, concernant la sensibilite des couts d'investissement de ces usines aux differents parametres techniques definissant le combustible et leur confrontation selon les pays ou aires economiques envisages. On montre enfin comment doit pouvoir s'exprimer l'influence de la taille des usines sur leur cout d'investissement. (auteur)

Radiobiological study of the radioprotective activity of a natural Iranian compound, ''Shir-Khecht''; Etude radiobiologique de l'activite radioprotectrice d'un compose naturel Iranien: le ''Shir-Khecht''

Energy Technology Data Exchange (ETDEWEB)

Rouhanizadeh, N [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-01-01

After reviewing the primary mechanisms of the action of ionizing radiation, the possible mechanisms of the action of radioprotective substances, the various chemical structures having a protective effect and the methods for studying chemical radioprotection, the author presents the results he has obtained with natural Iranian product: ''Shir-Khecht''. Tests with this product at lethal and sublethal doses have been carried out on the rat using various means of introduction. The effect of radiation, both with and without protection, has been studied using histological and biochemical methods. The product examined has, in effect, a protective action; it is, furthermore, non-toxic and active when taken orally. (author) [French] Apres avoir rappele les mecanismes primaires de l'action des rayonnements ionisants, les mecanismes possibles de l'action des substances radioprotectrices, les diverses structures chimiques possedant un effet protecteur et les methodes d'etude de la radioprotection chimique, l'auteur presente les resultats qu'il a obtenus en utilisant un compose naturel iranien: le ''Shir-Khecht''. Des essais de ce produit, chez le rat, par diverses voies d'introduction, a dose letale et subletale ont ete effectues. L'effet des radiations, avec et sans protection, a ete etudie a l'aide de methodes histologiques et biochimiques. Le compose essaye possede un pouvoir protecteur; il est, de plus, non toxique et actif par voie orale. (auteur)

Reconsideration of Methane Isotope Signature As a Criterion for the Genesis of Natural Gas: Influence of Migration on Isotopic Signatures Reconsidération de la signature isotopique du méthane comme critère pour la genèse du gaz naturel : influence de la migration sur les signatures isotopiques

Directory of Open Access Journals (Sweden)

Pernaton E.

2006-11-01

Full Text Available Experiments were performed in the purpose of studying the isotopic consequences of the diffusional transport of hydrocarbon gases through sediment rocks. Linked to a numerical model, these gas diffusion experiments through a shale porous plug allowed us to correlate porosity and diffusivity of the migration medium. Significant isotopic fractionations (carbon and hydrogen of methane, and ethane at a lesser degree were observed. This is in contradiction with the actual dogma of isotope geochemistry of natural gases which claims that no fractionation occurs during gas migration. The genetic characterization of natural gases by using the isotopic signature of methane appears as an ambiguous method. Plusieurs expériences ont été réalisées dans le but d'étudier les conséquences isotopiques du transport par diffusion des gaz hydrocarbures au travers des roches sédimentaires. Associées à un modèle numérique, ces expériences de diffusion au travers d'une membrane d'argile reconstituée nous ont permis de corréler deux paramètres pétrophysiques du milieu de migration : la porosité et la diffusivité. D'importants fractionnements isotopiques ont été observés au cours de la diffusion du méthane et, à plus petite échelle, lors de la diffusion de l'éthane. Ces résultats remettent en cause le dogme actuel de la géochimie isotopique des gaz naturels qui stipule que la migration des gaz ne peut induire de fractionnements isotopiques. En conséquence, les méthodes de caractérisation génétique des gaz naturels utilisant la signature isotopique du méthane apparaissent comme insuffisantes.

New insights into prevalence, genetic diversity, and proviral load of human T-cell leukemia virus types 1 and 2 in pregnant women in Gabon in equatorial central Africa.

Science.gov (United States)

Etenna, Sonia Lekana-Douki; Caron, Mélanie; Besson, Guillaume; Makuwa, Maria; Gessain, Antoine; Mahé, Antoine; Kazanji, Mirdad

2008-11-01

Human T-cell leukemia virus type 1 (HTLV-1) is highly endemic in areas of central Africa; mother-to-child transmission and sexual transmission are considered to be the predominant routes. To determine the prevalence and subtypes of HTLV-1/2 in pregnant women in Gabon, we conducted an epidemiological survey in the five main cities of the country. In 907 samples, the HTLV-1 seroprevalence was 2.1%, which is lower than that previously reported. Only one case of HTLV-2 infection was found. The HTLV-1 seroprevalence increased with age and differed between regions (P cosmopolitan subtype A. The new strains of subtype B exhibited wide genetic diversity, but there was no evidence of clustering of specific genomes within geographical regions of the country. Some strains were closely related to simian T-cell leukemia virus type 1 strains of great apes, suggesting that in these areas some HTLV-1 strains could arise from relatively recent interspecies transmission. The sole HTLV-2 strain belonged to subtype B. In this study we showed that the prevalence of HTLV-1 in the southeast is one of the highest in the world for pregnant women.

Preparation and properties of carbonaceous products prepared by the cracking of natural gas; Fabrication et proprietes de corps carbones prepares par craquage de gaz naturel

Energy Technology Data Exchange (ETDEWEB)

Blum, P L; Bochirol, L; Rappeneau, J; Cornuault, P; Blanchard, R; Moreau, C [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1964-07-01

Complete results are presented of tests recently carried out at the Grenoble Nuclear Research Centre in an attempt to transform natural gas (gas from Lacq), used as a source of pyrolytic carbon, into carbonaceous products with improved properties. Several methods have been studied: 1 - By using normal grade industrial graphite as support (density of about 1.50) products having densities of about 1.80 are obtained. Their open porosity (6 to 7 per cent) is lower than that of conventional graphites, and several of their characteristics are more or less equal to, or better than those obtained from a double impregnation witch pitch. 2 - The use as supporting material of the semi-products ('cooked') usually used for graphite production does not lead to satisfactory results. The main reasons for this are given. 3 - A new process, called 'BB5', has been developed. The starting materials here are powdered products (petrol coke or graphite) which are put into shape with the use of a binder which can be dispersed in water. The supports thus produced make it possible, because of their porous structure, to make the most of the densification produced by cracking natural gas below 1000 deg. C. The products obtained, which are made up of equal amounts approximately of the supporting material and of pyrocarbon can attain densities of over 1.90. Their very low open porosity can be reduced almost to zero and their impermeability is then excellent (k=10{sup -8} cm{sup 2}sec{sup -1}). They have also a remarkably high resistance to compression, values of 15 to 20 kg/mm{sup 2} being obtained for those carbons which have not undergone a final graphitization treatment. Some examples are given of possible nuclear applications of the materials produced in this manner. (authors) [French] On expose l'ensemble des essais effectues recemment au CEN-G pour preparer, a partir de gaz naturel (gaz de Lacq) comme source de carbone pyrolytique, des corps carbones de caracteristiques ameliorees

In Vitro Proliferation and Production of Cytokine and IgG by Human PBMCs Stimulated with Polysaccharide Extract from Plants Endemic to Gabon

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Line Edwige Mengome

2014-11-01

Full Text Available Polysaccharides were extracted from seven plants endemic to Gabon to study their potential immunological activities. Peripheral blood mononuclear cell (PBMC (5 × 105 cells/mL proliferation, cytokine and immunoglobulin G (IgG assays were performed after stimulation with different concentrations of polysaccharide fractions compared with lipopolysaccharides (LPS and concanavalin A (ConA from healthy volunteers. The culture supernatants were used for cytokine and IgG detection by enzyme-linked immunosorbent assay (ELISA. The results show that pectin and hemicellulose extracts from Uvaria klainei, Petersianthus macrocarpus, Trichoscypha addonii, Aphanocalyx microphyllus, Librevillea klaineana, Neochevalierodendron stephanii and Scorodophloeus zenkeri induced production levels that were variable from one individual to another for IL-12 (3–40 pg/mL, IL-10 (6–443 pg/mL, IL-6 (7–370 pg/mL, GM-CSF (3–170 pg/mL and IFN-γ (5–80 pg/mL. Only hemicelluloses from Aphanocalyx microphyllus produce a small amount of IgG (OD = 0.034, while the proliferation of cells stimulated with these polysaccharides increased up to 318% above the proliferation of unstimulated cells. However, this proliferation of PBMCs was abolished when the pectin of some of these plants was treated with endopolygalacturonase (p < 0.05, but the trend of cytokine synthesis remained the same, both before and after enzymatic treatment or saponification. This study suggests that these polysaccharides stimulate cells in a structure-dependent manner. The rhamnogalacturonan-I (RGI fragment alone was not able to induce the proliferation of PBMC.

Trichospirura aethiopica n. sp. (Nematoda: Rhabdochonidae from Malacomys longipes (Rodentia: Muridae in Gabon, first record of the genus in the Ethiopian Realm

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Bain Odile

2013-01-01

Full Text Available Trichospirura aethiopica n. sp. is described from unidentified tubular structures (pancreatic ducts? near the stomach of the murid Malacomys longipes Milne-Edwards, 1877 in Gabon. The extremely long and narrow buccal capsule, posterior position of the vulva, unequal spicules and absence of caudal alae readily identified the specimens as belonging to Trichospirura Smith & Chitwood, 1967, but a combination of several characters distinguished them from the described species in this genus. Males of the new species are characterized by the absence of precloacal papillae, the presence of four pairs of postcloacal papillae and a left spicule length of 165–200 μm. With only five nominal and one unnamed species, the host range of Trichospirura extends into the Neotropical, Indo-Malayan and Ethiopian Realms and comprises three classes of vertebrates, Amphibia, Reptilia and Mammalia, suggesting a larger species diversity than that currently recorded. Detection is difficult as predilection sites are often outside the gut lumen. It was noted that, irrespective of their geographic origin, species from mammals share certain characters (shorter left spicule and absence of precloacal papillae that oppose them to those from amphibians and reptiles. A hypothesis for the origin of Trichospirura in mammals through a remote host-switching event in tupaiids in southern Asia, likely facilitated by the intermediate hosts, and for their subsequent migration to the Ethiopian and finally Neotropical Realm is proposed. Regarding the two species from anurans and saurians in the Antilles, one or two host-switching events are considered equally possible, based on morphological characters.

Gabon education system, from independence to our days (1960-2010 El sistema educativo de Gabón, de la independencia a nuestros días (1960-2010

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Eugénie EYEANG

2012-08-01

Full Text Available The implementation of the education system in Gabon, as in other African countries, born of the school intervention of the missionaries, with religiously oriented educational projects and assimilation into Western culture of the colonial power itself. France is the dominant reference for this West Central African country. Since independence in 1960 Gabon’s educational model is still adopting the French in all its structures, from primary school to university, despite the different adaptations undertaken, especially since they Généraux États de l’Éducation, 1983.La implantación del sistema educativo de Gabón, como en otros países de África, parte de la intervención escolar de los misioneros, con proyectos educativos de orientación religiosa y de asimilación en la cultura occidental propia de la potencia colonial. Francia es el referente dominador para este país del África Central Occidental. Desde la independencia de Gabón en 1960 el modelo educativo que se adopta continúa siendo el francés en todas sus estructuras, desde la escuela primaria hasta la universidad, y a pesar de las diferentes adaptaciones emprendidas, sobre todo desde les États Généraux de l’Éducation de 1983.

La palmeraie des Îles Kerkennah (Tunisie, un paysage d'oasis maritime en dégradation : déterminisme naturel ou responsabilité anthropique ?

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Noômène Fehri

2011-09-01

Full Text Available L'archipel des Kerkennah, situé dans le Golfe de Gabès à environ 18 kilomètres au large de la ville de Sfax, se caractérise par la fragilité de son "milieu naturel". Une fragilité qui peut être résumée en trois points :- un climat semi-aride caractérisé par la longue durée de la saison estivale sèche avec un déficit hydrique moyen qui dépasse 1000 mm/an ; - une prépondérance des formations meubles, en particulier les limons rouges würmiens favorables à l'érosion marine, aggravée par une ancienne subsidence qui remonterait au Tyrrhénien ;- une prédominance des sols salés qui couvrent près de la moitié de la superficie totale.Cette fragilité se traduit par deux problèmes majeurs, à savoir : un rapide recul du trait de la côte et une extension continue des sebkhas au détriment de la palmeraie dont les arbres sont en train de mourir par centaines.Cet article met l'accent sur les interventions humaines ayant accéléré la dégradation de ces milieux naturellement fragiles.Une activité salinière en net accroissement, un déclin de l'intérêt porté par la population locale au palmier, certains aménagements entrepris sans étude d'impact, l'ouverture de carrières et l'extraction illicite des sables pour les besoins de la construction, le surpâturage, tels sont les principaux facteurs anthropiques de cette dégradation accélérée.La prise en compte de l'ensemble des particularités environnementales des Kerkennah s'impose donc comme étant une condition indispensable pour toute action de développement qui se veut rationnelle et durable.The archipelago of Kerkennah, located in the Gulf of Gabes at about 18 kilometers off the town of Sfax, is characterized by the fragility of its “natural environment”. This fragility could be summarized in three points:- a semi-arid climate characterized by a long dry summer with an annual hydric deficit greater than 1000 mm/year;- a preponderance of soft formations

Geochemistry of actinides. Application to the storage of high level radioactive wastes. Under the supervision of Mr Michel Treuil

International Nuclear Information System (INIS)

Bouabdallah, Noureddine; Cunault, Jean-Baptiste; Houtin, Gwenaelle; Leborgne, Francois; Lemaire, Celine; Lemarchand, Damien; Quitte, Ghylaine

1997-06-01

This collective research report first addresses the chemistry of actinides with a description of their atomic orbitals and the study of their behaviour in solution. The author addresses several aspects: historical overview on actinides, radioactivity, chemical reactions in aqueous solution, redox chemistry, speciation in solution with respect to water characteristics in deep storage conditions. The second part gathers several studies performed on a natural laboratory (the Oklo site in which nuclear reactions occurred about 2 billions years ago) and reports the modelling of radionuclide transfer within a geological system (the model is applied to the Oklo site). The third part addresses issues related to the nuclear fuel cycle, and the storage modes and materials envisaged and involved regarding the storage of high level radioactive wastes, notably in France

New STLV-3 strains and a divergent SIVmus strain identified in non-human primate bushmeat in Gabon

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Liégeois Florian

2012-03-01

Full Text Available Abstract Background Human retroviral infections such as Human Immunodeficiency Virus (HIV or Human T-cell Lymphotropic Virus (HTLV are the result of simian zoonotic transmissions through handling and butchering of Non-Human Primates (NHP or by close contact with pet animals. Recent studies on retroviral infections in NHP bushmeat allowed for the identification of numerous Simian Immunodeficiency Viruses (SIV and Simian T-cell Lymphotropic Viruses (STLV to which humans are exposed. Nevertheless, today, data on simian retroviruses at the primate/hunter interface remain scarce. We conducted a pilot study on 63 blood and/or tissues samples derived from NHP bushmeat seized by the competent authorities in different locations across the country. Results SIV and STLV were detected by antibodies to HIV and HTLV antigens, and PCRs were performed on samples with an HIV or/and HTLV-like or indeterminate profile. Fourteen percent of the samples cross-reacted with HIV antigens and 44% with HTLV antigens. We reported STLV-1 infections in five of the seven species tested. STLV-3 infections, including a new STLV-3 subtype, STLV-1 and -3 co-infections, and triple SIV, STLV-1, STLV-3 infections were observed in red-capped mangabeys (C.torquatus. We confirmed SIV infections by PCR and sequence analyses in mandrills, red-capped mangabeys and showed that mustached monkeys in Gabon are infected with a new SIV strain basal to the SIVgsn/mus/mon lineage that did not fall into the previously described SIVmus lineages reported from the corresponding species in Cameroon. The same monkey (subspecies can thus be carrier of, at least, three distinct SIVs. Overall, the minimal prevalence observed for both STLV and SIV natural infections were 26.9% and 11.1% respectively. Conclusions Overall, these data, obtained from a restricted sampling, highlight the need for further studies on simian retroviruses in sub-Saharan Africa to better understand their evolutionary history and to

[Mixed connective tissue disease: prevalence and clinical characteristics in African black, study of 7 cases in Gabon and review of the literature].

Science.gov (United States)

Missounga, Landry; Ba, Josaphat Iba; Nseng Nseng Ondo, Ingrid Rosalie; Nziengui Madjinou, Maria Ines Carine; Malekou, Doris; Mouendou Mouloungui, Emeline Gracia; Nzengue, Emmanuel Ecke; Boguikouma, Jean Bruno; Kombila, Moussavou

2017-01-01

The literature reports that mixed connective tissue disease seems more frequent in the black population and among Asians. This study aims to determine the prevalence of mixed connective tissue disease (MCTD) among connective tissue disorders and all rheumatologic pathologies in a hospital population in Gabon as well as to describe the clinical features of this disease. We conducted a retrospective study by reviewing the medical records of patients treated for mixed connective tissue disease (Kasukawa criteria) and other entities of connective tissue disorders (ACR criteria) in the Division of Rheumatology at the University Hospital in Libreville between January 2010 and December 2015. For each case of MCTD the parameters studied were articular and extra-articular manifestations, anti-U1RNP antibodies levels, patient's evolution. Over a period of 6 years, data were collected by medical records of 7 patients out of 6050 patients and 67 cases of connective tissue disorders, reflecting a prevalence of 0.11% and 10.44% respectively. the 7 patients were women (100%), with an average age of 39.5 years. Articular manifestations included: polyarthritis, myalgias, chubby fingers and Raynaud's phenomenon in 87.5%, 87.5%, 28.6% and 14% respectively. The 7 patients had high anti-U1RNP antibodies levels, ranging between 5 and 35N (N≤ 7 IU). A case of death due to pulmonary arterial hypertension (PAH) was certified. This is the largest case series of MCTD reported in Black Africa. The disease seems to be rare among the black Africans; the reason could be genetic. The demographic and clinical aspects appear similar to those in Caucasians, Asians and Blacks except for a low frequency of Raynaud?s phenomenon among Blacks.

Source-to-Sink: An implicit and O(n) landscape evolution model and its application to the Ogooue Delta, Gabon

Science.gov (United States)

Yuan, X.; Braun, J.; Guerit, L.; Simon, B.

2017-12-01

Limited attention has been given to linking continental erosion to transport and deposition of sediments in the marine environment in large-scale landscape evolution models. Although both environments have been thoroughly investigated, the details of how erosional or climatic events are recorded in the sedimentary and stratigraphic records have not been studied in a consistent quantitative manner. Here we propose a new numerical model for marine multi-lithology (sand and silt) coupling transport and deposition that is directly coupled to FastScape, a landscape evolution model that solves the continental stream power law and hillslope diffusion equation using implicit and O(n) algorithms. Marine transport and deposition is simulated by a nonlinear 2D diffusion model that incorporates a dual lithology (sand and slit) and where source terms represent the sediment flux from continental river erosion. Sediment compaction effects are also incorporated, taking into account the dual lithology, and are important to properly compute the details of the synthetic stratigraphic record. The algorithm used to represent marine transport and deposition is also implicit and O(n). The main purpose of our work is to invert stratigraphic data from offshore marginal basins to provide constraints on the tectonic, climatic and sea-level conditions that have affected the adjacent continental areas. In order to do so, we have incorporated the new model into a Bayesian inversion and optimisation scheme and tested and validated the approach with synthetic data. This is made possible due to the high efficient of the forward model. We are in the process of applying the inversion scheme to stratigraphic data from the Ogooue Delta (Gabon). By comparing real and synthetic stratigraphic geometries along cross-section of the delta, the shape and slope of seismic/time markers, and the sand to silt fraction in wells, we hope to obtain good constraints, not only of the value of the transport

Ethnopharmacological surveys and pharmacological studies of plants used in traditional medicine in the treatment of HIV/AIDS opportunistic diseases in Gabon.

Science.gov (United States)

Tchouya, Guy Raymond Feuya; Souza, Alain; Tchouankeu, Jean Claude; Yala, Jean-Fabrice; Boukandou, Marlaine; Foundikou, Hibrahim; Obiang, Giresse Delphang Nguema; Boyom, Fabrice Fekam; Mabika, Rolande Mabika; Menkem, Elisabeth Zeuko'o; Ndinteh, Derek Tantoh; Lebibi, Jacques

2015-03-13

Ethnopharmacological surveys were conducted in two regions of Gabon. This led to highlighting some of the medicinal plants used by local populations in the management of HIV/AIDS opportunistic diseases. Two regions with the highest occurrence of HIV/AIDS cases were visited and ethnopharmarcological data was gathered. These regions were the Estuaire Province (Libreville and its neighborhood) and the Haut-Ogooué Province (Franceville and its neighborhood). The opportunistic diseases and symptomatic conditions considered during this study were: diarrhea, respiratory tract infections, cough, tuberculosis, abscesses, stomach ache, skin rashes, venereal diseases, typhoid fever, anemia, general tiredness, hepatitis and vomiting. The reported species were evaluated through three parameters: specificity, reliability and frequency. Plant parts of relevant species were harvested and extracted with an aqueous alcohol solution (ethanol/water: 1/1). The extracts obtained were submitted to phytochemical screening and in vitro microbiological assays on some clinical isolates and ATCC strains, involved in HIV/AIDS opportunistic diseases through the Agar well diffusion and Microbroth dilution methods. Among the 52 species identified during this survey, Coelocaryon klainei Pierre ex Heckel (Myristicaceae), Dacryodes klaineana (Pierre) H.J. Lam (Bursecaceae), Phyllanthus diandrus Pax (Euphorbiaceae), Saccoglotys gabonensis (Baill.) Urb. (Humiriaceae) and Tetrorchidium didymostemon (Baill.) Pax & K. Hoffm. (Euphorbiaceae) were submitted to in vitro microbiological assays. Phyllanthus diandrus bark and leaves show best antibacterial activities against Pseudomonas aeruginosa and Klebsiella pneumoniae with MIC value of 0.25 respectively. Phytochemical screening revealed the presence in all the plant parts extracts of potentially bioactive molecules, including polyphenols, especially flavonoids and tannins. It is concluded that some of these plants might be submitted to further scientific

2.9-1.9 Ga paleoalterations of Archean granitic basement of the Franceville basin (Gabon)

Science.gov (United States)

Mouélé, Idalina Moubiya; Dudoignon, Patrick; El Albani, Abderrazak; Meunier, Alain; Boulvais, Philippe; Gauthier-Lafaye, François; Paquette, Jean-Louis; Martin, Hervé; Cuney, Michel

2014-09-01

The Archean granitoids in the Kiéné area, Gabon, are overlained by the Paleoproterozoic sediments of the Franceville basin (2.1 Ga). The basin is known for its high-grade uranium deposits among which some have been forming natural nuclear fission reactors. Most of the studies were dedicated to the FA-FB Paleoproterozoic sediments hosting these uranium deposits. Little is known on the Archean basement itself and specifically on the hydrous alteration events it experienced before and after the sediment deposition. The present work is focused on their petrographical, mineralogical and geochemical characterization. Dating the successive alteration events has been attempted on altered monazite crystals. Rocks in different alteration states have been sampled from eight drill cores crosscutting the Archean - Paleoproterozoic unconformity. The Archean granitoids observed in the deepest levels exhibit typical petrographical features of a propylitic alteration while they are intensely illitized up to the unconformity. The propylitic alteration is mainly pervasive but the original texture of the granitoïds is conserved in spite of the formation of new minerals: Mg-chlorite, allanite and epidote forming a typical paragenesis. The illitic alteration is much more invasive near the unconformity. The illitization process leads to the replacement of feldspars and the corrosion of quartz crysals by an illitic matrix while the ferromagnesian minerals are pseudomorphosed by a Fe-chlorite + phengite + hematite assemblage. The final fluid-rock interaction step is marked by fissural deposits of calcite and anhydrite. The δ13C isotopic data show that the fissural carbonates precipitated from diagenetic fluids enriched carbon products deriving from the maturation of organic matter. The U-Pb isotopic analyzes performed on monazite crystals have dated three distinct events: 3.0-2.9 Ga (magmatic), 2.6 Ga (propylitic alteration) and 1.9 Ga (diagenetic illitization). The calculation of

Distribution des Glossines vecteurs de la Trypanosomose humaine ...

African Journals Online (AJOL)

Objective: In order to know the apparent density and specific composition of the flies in a former home of human African trypanosomes in Gabon, an entomological investigation was conducted in primary forest and Doussala village in the National Park of Moukalaba Doudou (Gabon South). Methodology and Results:The ...

The foreign policy of the Gabonese Republic: new priorities and challenges

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F Ch Ndakissa Onkassa

2016-12-01

Full Text Available The article considers the features of formation and realization of foreign policy and the basic characteristics of the international image of modern Gabon are considered. It is shown, that the foreign policy is the important direction in the state activity of Gabon and is intended to offer the General public all over the world complete and reliable information on the situation in the country on key international issues, activities and initiatives of Gabon in the field of political space and the processes and projects of socio-economic development, its cultural and scientific achievements. Foreign policy activity is aimed at creating favorable conditions for the realization of the historic choice of the Gabonese people to strengthen the rule of law, market economy and democratic society, to focus on the social dimension. Нerewith this article analyzes the main provisions of the foreign policy of the Gabonese Republic, considered in conjunction with the country's development objectives defined in the strategic plan “A prosperous Gabon”. Particular attention is paid to the role of the President in making foreign policy decisions and ideas about the prospects for the development of Gabon's foreign policy. Key value of principles of maintenance of the sovereignty and the international inclusiveness, influence of the factor of the French language and policy of multilateral diplomacy is underlined at definition of objectives and priorities of foreign policy of Gabon during an epoch of new international realities. It is noted, that foreign policy activity of Gabon is aimed at creation a wide range of the international partnership in interests of national development in in the context of globalization.

Natural uranium toxicology - evaluation of internal contamination in man; Toxicologie de l'uranium naturel - essai d'evaluation de la contamination interne chez l'homme

Energy Technology Data Exchange (ETDEWEB)

Chalabreysse, J [Commissariat a l' Energie Atomique, Pierrelatte (France). Centre d' Etudes Nucleaires

1968-07-01

After reminding the physical and chemical properties of natural uranium which might affect its toxicology, a comprehensive investigation upon natural uranium metabolism and toxicity and after applying occupational exposure standards to this particular poison, it has been determined, from accident reports and human experience reported in the related literature, a series of formulae obtained by theoretical mathematical development giving principles for internal contamination monitoring and disclosure by determining uranium in the urine of occupationally exposed individuals. An assay is performed to determine individual internal contamination according to the various contamination cases. The outlined purposes, mainly practical, required some options and extrapolations. The proposed formula allows a preliminary approach and also to determine shortly a contamination extent or to discuss the systematical urinalysis results as compared with individual radio-toxicology monitoring professional standards. (author) [French] Apres le rappel des caracteristiques physiques et des proprietes chimiques de l'uranium naturel pouvant avoir une influence sur sa toxicologie, l'etude detaillee de son metabolisme et de sa toxicite, puis l'application des normes professionnelles d'exposition au cas particulier de ce toxique, il est etabli, a partir des comptes rendus d'accidents et de l'experimentation humaine rapportes dans la litterature, une serie de formules obtenues par developpement mathematique theorique qui posent les principes de la surveillance et de la mise en evidence de la contamination interne par la recherche et le dosage de l'uranium dans les urines d'individus professionnellement exposes. Un essai d'evaluation de la contamination interne individuelle suivant les differents cas de contamination est effectue. Le formulaire propose permet de faire une premiere approximation et d'apprecier rapidement l'importance d'une contamination ou bien d'interpreter les resultats d

Molecular evidence for deep phylogenetic divergence in Mandrillus sphinx.

Science.gov (United States)

Telfer, P T; Souquière, S; Clifford, S L; Abernethy, K A; Bruford, M W; Disotell, T R; Sterner, K N; Roques, P; Marx, P A; Wickings, E J

2003-07-01

Mandrills (Mandrillus sphinx) are forest primates indigenous to western central Africa. Phylogenetic analysis of 267 base pairs (bp) of the cytochrome b gene from 53 mandrills of known and 17 of unknown provenance revealed two phylogeographical groups, with haplotypes differentiated by 2.6% comprising seven synonymous transitions. The distribution of the haplotypes suggests that the Ogooué River, Gabon, which bisects their range, separates mandrill populations in Cameroon and northern Gabon from those in southern Gabon. The haplotype distribution is also concordant with that of two known mandrill simian immunodeficiency viruses, suggesting that these two mandrill phylogroups have followed different evolutionary trajectories since separation.

à l'encoche sèche

African Journals Online (AJOL)

naturel est une matière première importante en industrie. Il intervient à 70% dans la ... caoutchouc naturel de cette région est en constante progression, due au .... L'analyse a été effectuée avec le test statistique de Duncan au risque alpha = 5 % avec les valeurs de LEM transformées en Arc Sinus. Racine carrée de LEM ...

Proposition d'explication de la formation d'hydrogène sulfuré dans les stockages souterrains de gaz naturel par réduction des sulfures minéraux de la roche magasin Proposed Explanation of Hydrogen-Sulfide Formation in Underground Natural-Gas Storage Structures by Reduction of Mineral Sulfides in the Reservoir Rock.

Directory of Open Access Journals (Sweden)

Bourgeois J. P.

2006-11-01

Full Text Available La formation d'hydrogène sulfuré dans les structures de stockage peu expliquer autrement que par l'action de bactéries sulfato-réductrices. La contenue dans la roche magasin constitue une source de sulfures capable d'alimenter en H2S le gaz naturel. La réduction de la pyrite en sulfures du type Fe 1-x S et l'équilibre de dissolution précipitation, lié principalement à la pression de CO2, dans les structures stockages, constituent un processus de formation d'H2S capable d'expliquer tativement et quantitativement les phénomènes observés sur le terrain. Un modèle simplifié de stockage reprend ce schéma et teste la sensibililté de la teneur en H2S à la valeur des paramètres physiques et chimiques définissant le stockage. Cette étude permet de proposer un certain nombre d'actions susceptibles de limiter la formation d'H2S et d'orienter les choix futurs du couple gaz naturel - structures de stockage. The formation of hydrogen sulfide in storage structures can be explained otherwise thon by the action of sulfate-reducing bacteria. The pyrite contained in the reservoir rock makes up a source of sulfides capable of supplying the natural gas with H2S.Reduction of pyrite ta sulfides of the Fe,-,S type and the dissolution precipitation equilibrium, linked mainly ta C02 pressure in storage structures, make up an H2S for-mation process capable of qualitatively and quantitatively explained phenomena observed in the field.A simplified storage model reflects this scheme and can be used ta test the sensi-tivity of the H2S content ta the value of the physical and chemical parameters defining the storage structure.This investigation can be used to propose various means of action (sable ta "mit H2S formation and ta guide future choices of natural gas/storage-structure pairs.

L’environnement naturel et le changement climatique pendant les années Bush : la pertinence d’une différenciation des échelles territoriales Climate Change and the Natural Environment in the Bush Years: The Relevance of Territorial Scale Differentiation

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Cynthia Ghorra-Gobin

2010-03-01

Full Text Available L’attitude de l’administration fédérale au cours des huit années de l’administration Bush contraste avec celle du contexte des années 1960-1970 pour ce qui concerne la prise en compte de l’environnement naturel dans les décisions économiques. Toutefois, cet engagement limité du président Bush sur la question du changement climatique dans les débats internationaux n’a pas pour autant réduit les capacités de mobilisation des États et des villes sur ce thème.On the issue of whether climate change should be taken into account in economic decisions, the federal administration’s attitude during the Bush Presidency sharply contrasted with the attitudes of earlier administrations, particularly in the 1960’s and 1970’s. The limited concern for climate change which the federal government exhibited in the international arena did not reduce, however, the mobilization of states and local communities on this issue.

Natural repository analouge program. Progress report, January 1-March 31, 1981

International Nuclear Information System (INIS)

Curtis, D.B.

1981-05-01

Samples from Oklo Reactor zone-9 (ORZ-9) have been analyzed for the isotopic abundances of Nd, Ce, Ru, and Mo. Interpretation of the Nd data has begun as part of the effort to reconstruct the operating parameters of the reactor. The study of ORZ-9 and the peripheral rocks is being enhanced by additional analytical capabilities. A procedure was developed to measure uranium isotopic ratios with high precision. This new method was used for the analysis of rocks peripheral to ORZ-9. Two rocks containing relatively small quantities of uranium were depleted in 235 U. The result demonstrates that small quantities of uranium were removed from the reactor zone and redistributed over distances of several tens of meters. Procedures are being designed to make high precision measurements of the relative abundances of barium isotopes. They will be used as part of a study of the transport of alkali and alkaline earth elements at Oklo. Samples from distances up to 300 meters from the known mineralized area at Oklo have been selected and prepared in an effort to identify element transport paths over longer distances. A sample from the Athabasca sandstone, overlying the uranium ores at Key Lake, and another from the transition zone at the unconfromity between the sandstone and the basement were subjected to sequential leaches designed to preferentially dissolve specific minerals. Lead isotopic analyses on the leachs yielded two sets of data, which indicate the loss of uranium or the addition of lead from a radiogenic source early in the geologic history of the rocks

Distribution des Glossines vecteurs de la Trypanosomose humaine ...

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SARAH

28 févr. 2015 ... RESUME. Objectifs : Dans le but de connaitre la densité apparente et la composition spécifique des glossines dans un ancien foyer de la Trypanosome humaine africaine au Gabon, une enquête entomologique a été menée dans deux biotopes du Parc National de Moukalaba Doudou (Sud Gabon) : le ...

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politique de bas prix exercée par la Russie et le Qatar vient confirmer ce constat ; s'ajoute à cela l'entrée éventuelle du gaz non conven- tionnel, dont son prix actuel de 3/4 $US, offre aux USA l'opportunité d'être exportateur de ..... les compagnies à produire en matière du gaz naturel, tels le prix du gaz naturel, le prix des ...

Natural uranium lattice in heavy water; Reseaux uranium naturel-eau lourde

Energy Technology Data Exchange (ETDEWEB)

Girard, Y; Koechlin, J C; Moreau, J; Naudet, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-01

'ajustements sont necessaires, or ceux-ci ne peuvent donner d'efficacite dans la prevision que s'ils recouvrent un nombre suffisant de resultats experimentaux. On a donc cherche a la fois a rattacher etroitement les mesures entre elles et a les recouper par des formules se deduisant logiquement les unes des autres. Le principal souci a ete celui de la coherence. On donne les regles de calcul qui ont ete utilisees pour ce travail interpretatif. Dans un premier temps, on emploie des formules simples; on s'attache en premier lieu aux barres pleines et on ajuste {eta} et les integrales effectives; on cherche ensuite a transposer les calculs au cas des barreaux plus complexes. Dans un deuxieme temps, on s'efforce d'ameliorer l'ensemble en etudiant plus en detail chaque facteur du calcul de reseau. Une interpretation satisfaisante des resultats conduit en definitive a des methodes de calcul applicables aux reseaux uranium naturel-eau lourde les plus varies. On a tenu compte des resultats obtenus dans d'autres pays, notamment au Canada. (auteur)

Natural uranium lattice in heavy water; Reseaux uranium naturel-eau lourde

Energy Technology Data Exchange (ETDEWEB)

Girard, Y.; Koechlin, J.C.; Moreau, J.; Naudet, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-01

calcul, on estime qu'un certain nombre d'ajustements sont necessaires, or ceux-ci ne peuvent donner d'efficacite dans la prevision que s'ils recouvrent un nombre suffisant de resultats experimentaux. On a donc cherche a la fois a rattacher etroitement les mesures entre elles et a les recouper par des formules se deduisant logiquement les unes des autres. Le principal souci a ete celui de la coherence. On donne les regles de calcul qui ont ete utilisees pour ce travail interpretatif. Dans un premier temps, on emploie des formules simples; on s'attache en premier lieu aux barres pleines et on ajuste {eta} et les integrales effectives; on cherche ensuite a transposer les calculs au cas des barreaux plus complexes. Dans un deuxieme temps, on s'efforce d'ameliorer l'ensemble en etudiant plus en detail chaque facteur du calcul de reseau. Une interpretation satisfaisante des resultats conduit en definitive a des methodes de calcul applicables aux reseaux uranium naturel-eau lourde les plus varies. On a tenu compte des resultats obtenus dans d'autres pays, notamment au Canada. (auteur)

CZO perspective in Central Africa : The Lopé watershed, Lopé National Park, Ogooué River basin, Gabon.

Science.gov (United States)

Braun, J. J.; Jeffery, K.; Koumba Pambo, A. F.; Paiz, M. C.; Richter, D., Jr.; John, P.; Jerome, G.

2015-12-01

Critical Zone Observatories (CZO) in equatorial regions are seldom (see e. g. http://www.czen.org/, USA and http://rnbv.ipgp.fr/, France). The equatorial zone of Central Africa is almost free of them with the exception of the CZO of the Upper Nyong river basin (organic-rich river on the lateritic plateau of South Cameroon; SO BVET, http://bvet.omp.obs-mip.fr/). On both sides of the Equator line, the Ogooué River Basin (215,000 km2) stretches on about 80% of the total area of Gabon and drains various geological and morpho-pedological contexts and feeds the sedimentation areas of the Central African passive margin (Guillochaux et al., 2014). The Upper Ogooué (up to Lambaréné) drains the stepped planation surface of the Congo craton while the Lower Ogooué drains Mesozoic and Cenozoic sedimentary terrains. The climate is equatorial (Pmean = 2500 mm/yr; Tmean = 26 °; %humidity > 80%). Continuous hydro-climatic chronicles exist for the period 1953-1974 (managed by ORSTOM, now IRD). The runoff at Lambaréné (92% of the basin area) is very high (714 mm/yr). With a rural density of 1 inhabitant/km2, it is one of the last largely pristine tropical forested ecosystems on the Planet. In addition, the basin will be, in the coming decades, the theatre of important anthropogenic changes (dams, agriculture, mining, urbanisation, …). However, a conservation plan with an ambitious sustainable development policy is set up. This plan articulates the environmental issues related to the emergence of the country. Because of these characteristics, the basin offers ideal conditions for studying the changes in equatorial region of hydro-climate, weathering/erosion regimes and regolith production based on morpho-pedological contexts and associated physical, chemical and biological processes. It is thus germane to launch an integrated CZO initiative at both regional scale and local scale. At the regional scale, we plan to reactivate some of the hydro-climatic stations located on the

Chroniques d'habitat et dynamique de populations de truite

Directory of Open Access Journals (Sweden)

CAPRA H.

1995-04-01

Full Text Available Une nouvelle méthode a permis de quantifier des Durées Continues d'Habitat Limitant (méthode DCHL à partir de chroniques d'habitat potentiel, pour la truite fario (Salmo trutta fario, L.. Cette méthode a été appliquée sur deux cours d'eau naturels et sur une station soumise à éclusée. Elle a été validée sur les deux cours d'eau naturels en ce qui concerne l'habitat limitant pour les jeunes truites de l'année (0+. Elle offre un outil pratique d'analyse des périodes d'habitat limitant en régime naturel. En situation d'éclusées, l'interprétation des résultats est différente et nécessite encore un effort important de suivi biologique.

Natural uranium toxicology - evaluation of internal contamination in man; Toxicologie de l'uranium naturel - essai d'evaluation de la contamination interne chez l'homme

Energy Technology Data Exchange (ETDEWEB)

Chalabreysse, J. [Commissariat a l' Energie Atomique, Pierrelatte (France). Centre d' Etudes Nucleaires

1968-07-01

After reminding the physical and chemical properties of natural uranium which might affect its toxicology, a comprehensive investigation upon natural uranium metabolism and toxicity and after applying occupational exposure standards to this particular poison, it has been determined, from accident reports and human experience reported in the related literature, a series of formulae obtained by theoretical mathematical development giving principles for internal contamination monitoring and disclosure by determining uranium in the urine of occupationally exposed individuals. An assay is performed to determine individual internal contamination according to the various contamination cases. The outlined purposes, mainly practical, required some options and extrapolations. The proposed formula allows a preliminary approach and also to determine shortly a contamination extent or to discuss the systematical urinalysis results as compared with individual radio-toxicology monitoring professional standards. (author) [French] Apres le rappel des caracteristiques physiques et des proprietes chimiques de l'uranium naturel pouvant avoir une influence sur sa toxicologie, l'etude detaillee de son metabolisme et de sa toxicite, puis l'application des normes professionnelles d'exposition au cas particulier de ce toxique, il est etabli, a partir des comptes rendus d'accidents et de l'experimentation humaine rapportes dans la litterature, une serie de formules obtenues par developpement mathematique theorique qui posent les principes de la surveillance et de la mise en evidence de la contamination interne par la recherche et le dosage de l'uranium dans les urines d'individus professionnellement exposes. Un essai d'evaluation de la contamination interne individuelle suivant les differents cas de contamination est effectue. Le formulaire propose permet de faire une premiere approximation et d'apprecier rapidement l'importance d

Natural fission reactors - the Oklo phenomenon

International Nuclear Information System (INIS)

Anon.

1989-01-01

Overview describes the discovery of the site, location of the reactors and site geology and discusses the permanence of fission products, nuclear reaction control mechanisms and trace concentrations of elements that act as poisons. (Author)

The War Powers Resolution: After Thirty-Six Years

Science.gov (United States)

2010-04-22

integrity of the Panama Canal treaties, and apprehend General Manuel Noriega, who had been accused of massive electoral fraud in the Panamanian elections...that city. (59) Congo and Gabon. On March 27, 1997, President Clinton notified Congress “consistent with the War Powers Resolution,” that on March 25...1997, a standby evacuation force of U.S. military personnel had been deployed to Congo and Gabon to provide enhanced security for American private

Radio-vulcanization of natural rubber in the latex phase. Study of an experimental 1 tonne per hour production; Radio-vulcanisation du caoutchouc naturel en phase latex. Etude d'une production experimentale de 1 tonne par heure

Energy Technology Data Exchange (ETDEWEB)

Leveque, P; Puig, J R; Roudeix, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

After briefly reviewing the main research carried out on the radio-vulcanization of latex and elastomers, a description is given of 4 types of cell which have been used successively with a view to industrial irradiation. They have made it possible to acquire the information necessary for resolving the main problem arising during irradiation - the formation of coagulum. The first two cell are designed for irradiation by a horizontal beam ('Dynamitron'), the two others use a vertical beam ('Circe'). The study of the properties of the rubber obtained shows it to compare favorably with 'Revultex'. In the appendix are given some characteristics of natural latex and information about its processing. (authors) [French] Apres un rappel des principales etudes sur la radio-vulcanisation du latex et des elastomeres, on decrit les quatre types de cellules successivement essayes en vue de l'irradiation industrielle. Ils ont permis d'acquerir les informations necessaires a la resolution du probleme principal pose par l'irradiation, la formation de coagulum au cours de celle,-ci. Les deux premiers sont concus pour l'irradiation par un faisceau horizontal ('Dynamitron'), les derniers par un faisceau vertical ('Circe'). L'etude des proprietes du caoutchouc obtenu montre qu'il se compare favorablement au 'Revultex'. Un apercu est donne en annexe des caracteristiques du latex naturel et de sa mise en oeuvre. (auteurs)

Investigations of the natural fission reactor program. Progress report, October 1977--September 1978

International Nuclear Information System (INIS)

Cowan, G.A.; Norris, A.E.

1978-10-01

The U.S. study of the Oklo natural reactor began in 1973 with the principal objectives of understanding the processes that produced the reactor and that led to the retention of many of its products. Major facets of the program have been the chemical separation and mass spectrometric analysis of the reactor components and products, the petrological and mineralogical examination of samples taken from the reactor zones, and an interdisciplinary modeling of possible processes consistent with reactor physics, geophysics, and geochemistry. Most of the past work has been on samples taken within the reactor zones. Presently, these studies give greater emphasis to the measurement of mobile products in additional suites of samples collected peripherally and ''downstream'' from the reactor zones. This report summarizes the current status of research and the views of U.S. investigators, with particular reference to the extensive work of the French scientists, concerning the main features of the Oklo natural fission reactor. Also mentioned briefly is the U.S. search for natural fission reactors at other locations

Parasismique, oser éprouver l’acceptabilité sociale

OpenAIRE

Cartier, Stéphane; Vallette, Cloé

2016-01-01

La confrontation aux risques naturels provoque une réorganisation sociale constante. L’acceptation de la menace et l’acceptabilité des solutions pour réduire la vulnérabilité évoluent avec les connaissances des phénomènes et le consentement collectif à la contrainte. En France, l’importance de l’engagement étatique face aux risques naturels dissuade d’en interroger l’acceptabilité collective. La protection parasismique de l’habitat impose un zonage de l’aléa sismique pour graduer les contrain...

Computer processing of {gamma} spectra. Application to the dosage of mixed natural or artificial radioelements; Traitement par ordinateur des spectres {gamma}. Application au dosage de melanges de radioelements naturels ou artificiels

Energy Technology Data Exchange (ETDEWEB)

Coulomb, R; Goldsztein, M; Schiltz, J C [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1965-07-01

A program, written in Fortran II for IBM 7034 II, permitting resolution by means of least squares of a mixture of natural or artificial radioelements, is described. The spectra are processed in measurement batches, making up a homogeneous study, which comprise standards and samples. This highly versatile program may either ensure the processing of a great number of daily analyses, or be used pending development of radiochemical methods. The feeding of data has been simplified as much as possible. On the contrary, at the outlet, the numerical or graphical controls, error computations, and the printing of results in clear and legible form have been multiplied. In spite of this, the calculation times are exceedingly short. Several independent studies which include about sixty spectra may be processed in less than five minutes. (authors) [French] On decrit un programme, redige en Fortran H, pour IBM 7094 H, permettant la resolution par les moindres carres d'un melange de radioelements naturels ou artificiels. Les spectres sont traites par groupe de mesures, constituant une etude homogene, comprenant etalons et echantillons. Ce programme, extremement souple, peut, soit repondre a une production journaliere importante d'analyses, soit etre utilise en periode de mise au point de methodes radiochimiques. L'introduction des donnees a ete simplifiee au maximum. Au contraire, a la 'sortie', on a multiplie les controles numeriques ou graphiques, les calculs d'erreur, les impressions de resultats sous une forme aussi claire et lisible que possible. Malgre cela, les temps de calculs sont extremement brefs, plusieurs etudes independantes comportant une soixantaine de spectres peuvent etre traitees en moins de 5 minutes. (auteurs)

Prevalence of and risk factors for malaria, filariasis, and intestinal parasites as single infections or co-infections in different settlements of Gabon, Central Africa.

Science.gov (United States)

M'bondoukwé, Noé Patrick; Kendjo, Eric; Mawili-Mboumba, Denise Patricia; Koumba Lengongo, Jeanne Vanessa; Offouga Mbouoronde, Christelle; Nkoghe, Dieudonné; Touré, Fousseyni; Bouyou-Akotet, Marielle Karine

2018-01-30

Malaria, filariasis, and intestinal parasitic infections (IPIs) are common and frequently overlap in developing countries. The prevalence and predictors of these infections were investigated in three different settlements (rural, semi-urban, and urban) of Gabon. During cross-sectional surveys performed from September 2013 to June 2014, 451 individuals were interviewed. In addition, blood and stool samples were analysed for the presence of Plasmodium, filarial roundworm, intestinal protozoan, and helminth infections. Intestinal parasitic infections (61.1%), including intestinal protozoa (56.7%) and soil-transmitted helminths (STHs) (22.2%), predominated, whereas Plasmodium falciparum (18.8%), Loa loa (4.7%), and Mansonella perstans (1.1%) were less prevalent. Filariasis and STHs were mainly found in rural settlements, whereas a higher plasmodial infection prevalence rate was observed in the periurban area. The most common IPI was blastocystosis (48.6%), followed by ascaridiasis (13.7%), trichuriasis (11.8%), amoebiasis (9.3%), giardiasis (4.8%), and strongyloidiasis (3.7%). Hookworm was detected in one adult from rural Dienga. Adults had a higher prevalence of Blastocystis hominis and STHs, whereas Giardia duodenalis was more frequently observed among children aged below 5 years (P < 0.01). The polyparasitism rate was 41.5%, with 7.0% Plasmodium-IPIs and 1.8% Plasmodium-STH co-infections. The multivariate analysis showed that living in a suburban area, belonging to the age group of 5-15 years, having none or a secondary education, or having an open body water close to home were significant risk factors for malaria (P ≤ 0.01). For STH infections, identified risk factors were drinking untreated water and living in a rural area (P ≤ 0.04). No significant predictors were identified for IPIs and malaria-IPI co-infection. This study reports a high prevalence of IPIs and intestinal protozoa, but a low rate of malaria-IPI co-infections in the study sites

ERDA waste management program

International Nuclear Information System (INIS)

Kuhlman, C.W.

1976-01-01

The ERDA commercial waste program is summarized. It consists of three parts: terminal storage, processing, and preparation of the Generic Environmental Impact Statement. Emplacement in geologic formations is the best disposal method for high-level waste; migration would be essentially zero, as it was in the Oklo event. Solidification processes are needed. Relations with the states, etc. are touched upon

Using camera traps and digital video to investigate the impact of Aethina tumida pest on honey bee (Apis mellifera adansonii reproduction and ability to keep away elephants (Loxodonta africana cyclotis in Gamba, Gabon

Directory of Open Access Journals (Sweden)

Steeve Ngama

2018-06-01

Full Text Available Bees and elephant interactions are the core of a conservation curiosity since it has been demonstrated that bees, one of the smallest domesticated animals, can keep away elephants, the largest terrestrial animals. Yet, insects' parasites can impact the fitness and activity of the bees. Since their activity is critical to the repellent ability against elephants, this study assessed the impact of small hive beetles (Aethina tumida on bee (Apis mellifera adansonii reproduction and ability to keep forest elephants (Loxodonta africana cyclotis away. Because interspecies interactions are not easy to investigate, we have used camera traps and digital video to observe the activity of bees and their interactions with wild forest elephants under varying conditions of hive infestation with the small hive beetle, a common bee pest. Our results show that queen cells are good visual indicators of colony efficiency on keeping away forest elephants. We give evidences that small hive beetles are equivalently present in large and small bee colonies. Yet, results show no worries about the use of bees as elephant deterrents because of parasitism due to small hive beetles. Apis mellifera adansonii bees seem to effectively cope with small hive beetles showing no significant influence on its reproduction and ability to keep elephants away. This study also reports for the first time the presence of Aethina tumida as a constant beekeeping pest that needs to be addressed in Gabon.

Radiobiological study of the radioprotective activity of a natural Iranian compound, ''Shir-Khecht''; Etude radiobiologique de l'activite radioprotectrice d'un compose naturel Iranien: le ''Shir-Khecht''

Energy Technology Data Exchange (ETDEWEB)

Rouhanizadeh, N. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-01-01

After reviewing the primary mechanisms of the action of ionizing radiation, the possible mechanisms of the action of radioprotective substances, the various chemical structures having a protective effect and the methods for studying chemical radioprotection, the author presents the results he has obtained with natural Iranian product: ''Shir-Khecht''. Tests with this product at lethal and sublethal doses have been carried out on the rat using various means of introduction. The effect of radiation, both with and without protection, has been studied using histological and biochemical methods. The product examined has, in effect, a protective action; it is, furthermore, non-toxic and active when taken orally. (author) [French] Apres avoir rappele les mecanismes primaires de l'action des rayonnements ionisants, les mecanismes possibles de l'action des substances radioprotectrices, les diverses structures chimiques possedant un effet protecteur et les methodes d'etude de la radioprotection chimique, l'auteur presente les resultats qu'il a obtenus en utilisant un compose naturel iranien: le ''Shir-Khecht''. Des essais de ce produit, chez le rat, par diverses voies d'introduction, a dose letale et subletale ont ete effectues. L'effet des radiations, avec et sans protection, a ete etudie a l'aide de methodes histologiques et biochimiques. Le compose essaye possede un pouvoir protecteur; il est, de plus, non toxique et actif par voie orale. (auteur)

Using geological information to develop new exploration project for uranium deposits in Southern Africa

International Nuclear Information System (INIS)

Takahashi, Osamu

1992-01-01

Unconformity related uranium deposits which contain a large amount of resources with higher grades will be economically superior to other types of deposits. This paper presents the integrated use of geological information, which includes compilation data for the Precambrian geology in southern Africa and selected structural geologic data for some analogues of unconformity related uranium deposit in Canada (e.g. Key Lake deposit in Athabasca Basin) and the Precambrian rock hosted uranium deposit in Africa (e.g. Oklo-Munana, Rossing, Shinkolobwe and Dome deposits). Finally, some favourable geological terrains for unconformity related uranium deposit and the Precambrian rock hosted uranium deposit were selected on the basis of geological information. Further significant discoveries are likely in the following geological terrains. 1. Both the unconformity related and Oklo-Munana type deposits are favourable at (a) and (b). (a) the Lower Proterozoic Eburnian belts which are unconformably overlain by sequences of Kibaran and also the unmetamorphosed sequences in Pan-African. The age and paleoenvironment of the unmetamorphosed sequences in Pan-African is comparable to Kibaran. (b) the unmetamorphosed sequences in Eburnian. 2. The Rossing, Shinkolobwe and Dome type deposits are favourable at the Upper Proterozoic Pan-African Belts. (author)

Circadian long call distribution in wild orangutans Distribution circadienne des cris longs (long calls chez l’orang-outan en milieu naturel

Directory of Open Access Journals (Sweden)

Thomas Geissmann

2009-10-01

Full Text Available We present first data on circadian long call distribution of wild orangutans in Northwest Borneo. Data were collected during two months in Batang Ai National Park. A total of 151 male long calls were heard, exhibiting a bimodal distribution pattern with peaks at 05:00-06:00 hours and 18:00-19:00 hours. An earlier study found pronounced differences between the calling rates of Bornean orangutans, which showed an almost unimodal call distribution with its peak at mid-morning, and those of Sumatran orangutans, which showed a bimodal call distribution with a distinct calling peak at predawn and a more moderate peak near dusk (MacKinnon 1974. Our findings from Batang Ai resemble more closely the pattern reported for Sumatra than those reported for other Bornean localities and, therefore, contradict earlier reports suggesting a Sumatra-Borneo dichotomy in orangutan call distribution. In addition, orangutans in Batang Ai were heard to regularly emit long calls throughout the night. This behaviour is unusual for a diurnal species.Nous présentons les premières données sur la distribution circadienne des cris longs (long calls chez les mâles orangs-outans vivant en milieu naturel au nord-ouest de Bornéo. Les données ont été récoltées lors d’une étude de terrain de deux mois au Parc National de Batang Ai. Les 151 cris longs entendus montraient une distribution bimodale, caractérisée par des pics à 05:00-06:00 et 18:00-19:00 heures. Une étude précédente avait révélé des différences profondes entre les taux de cris longs des orangs-outans de Bornéo et de Sumatra. Alors que la distribution des cris longs à Bornéo était presque unimodale et montrait un pic en milieu d’avant-midi, la distribution à Sumatra était bimodale et montrait un pic distinct avant l’aube et un second pic plus modéré au crépuscule (MacKinnon 1974. Nos résultats à Batang Ai ressemblent davantage au schéma rapporté précédemment à Sumatra qu�

Pb migration in the OKLO uranium deposit

International Nuclear Information System (INIS)

Gancarz, A.J.; Curtis, D.B.

1979-01-01

U-Pb and Pb isotopic data are presented which indicate that Pb is lost from host uraninite by diffusion, and that not only in situ uranogenic Pb but also the initial Pb is lost by diffusion. The conglomerate underlying the U deposit contains excess Pb and is both a transport zone and the repository for the Pb. 2 figures

Principes et application de la digestion anaérobie pour la production d'énergie

OpenAIRE

Bernet, Nicolas

2015-01-01

La digestion anaérobie est un processus naturel par lequel la matière organique est transformée en un biogaz qui contient environ 2/3 de méthane et 1/3 de dioxyde de carbone. Elle résulte de l’activité d’un écosystème microbien anaérobie complexe. Le biogaz est une source d’énergie qui peut être utilisée directement en remplacement du gaz naturel, pour produire de la chaleur et de l’électricité par cogénération ou encore comme carburant pour véhicules. Ainsi, la domestication par l’homme de c...

The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

International Nuclear Information System (INIS)

Ovaskainen, R.

1999-01-01

facilities (Australia, Canada, Gabon, Namibia, Czech Republic, France), were determined. These signatures form the basic register. The isotopic signatures are feasible in identifying the sample origin and in separating naturally occurring or background contributions from local anthropogenic sources. With the comparison of fingerprints of unknown samples to the isotopic fingerprints of samples of known origin, it is possible to trace back unknown samples to their origin or at least to exclude suspected origins in the case of non-identity of fingerprints. This was successfully demonstrated with a number of samples of unknown origin, which were measured during the study. Generally, no significant variability was observed in the n( 235 U)/n( 238 U) ratios except in the well known case of samples originating from Oklo (Gabon). Small variations in the n( 234 U)/n( 238 U) amount ratios were understood from the radiochemical mother-daughter relationship of the two isotopes involved. The detection limit for the n( 236 U)/n( 235 U) amount ratio (DL = 0.000001) was derived from blank measurements. The limit of quantitation 0.000003 was calculated as LQ=3DL. When the measured ratio exceeded the quantitation limit, the presence of 236 U is explained. (orig.)

[Immunization coverage of children aged 0 to 5 years in Libreville (Gabon)].

Science.gov (United States)

Ategbo, Simon; Ngoungou, Edgard Brice; Koko, Jean; Vierin, Yolande; Zang Ndong, Carine Eyi; Moussavou Mouyama, André

2010-01-01

The strategies recently implemented in Gabon have been effective in improving immunization coverage. These include, in particular, the integration of the Expanded Programme on Immunization (EPI) in primary health care centers, the integration of immunization outside of EPI, immunization by peripheral health centers according to pre-set advanced strategies, and awareness and catch-up campaigns. This descriptive, cross-sectional survey was conducted from 1 October 2007 through 30 January 2008, throughout public- and private-sector health care centers in the town of Libreville. In the public sector, where health care is free, the study took place at the largest health facility in the country, the Hospital Center of Libreville (HCL), at Estuary Mélen Hospital (on the outskirts of Libreville), at Nkembo Hospital, which houses the EPI offices, and the 5 Maternal and Child Health centers (MCH) where vaccine monitoring is done. Monitoring in the private sector covered only the three largest clinics, where vaccine monitoring is done, all of which agreed to participate. After obtaining informed consent from the parents or guardian accompanying the child, a semi-structured interview according to a standardised questionnaire was conducted to collect socioeconomic and demographic data, including age, sex, recruitment site, place of residence, number of siblings, parental origin, ethnicity of head of household, type of family (couple or single parent), mother's age, level of education, employment and socio-economic status, as determined by the head of household's monthly income (in three categories: 1) low income, at or below the minimum wage, set at 80 000 FCFA (120 euros); 2) average income, from more than 80 000 FCFA to 300 000 FCFA (458 euros); and 3) high income over 300 000 FCFA. After the interview, the child's vaccination booklet was carefully examined to identify the types of antigen, number of doses administered, age at vaccination, and the regularity of the

Emballage naturel de produits biologiques

NARCIS (Netherlands)

Thoden van Velzen, E.U.

2011-01-01

Les emballages en plastique, renouvelables et biodégradables, sont-ils vraiment écologiques? Pour les entreprises d’emballage, il est difficile d’y trouver la réponse et donc de faire des choix réfléchis. Dans l’analyse ‘Emballage naturel’ le maximum de données a été collectionné et résumé.

Double protection passive pour les equipages de l'helicoptere d'attaque "Tigre" : Concept et etude experimentale (Design and Experimental Study of the Passive Double Hearing Protection for the Crew of the Attack Helicopter "Tiger")

National Research Council Canada - National Science Library

Baudou, J; Reynaud, G; Poussin, G; Leger, A

2005-01-01

... naturellement imposee comme axe de travail. Prealablement evalues de facon empirique, des bouchons de type "mousses Quies" ont ete selectionnes pour leur port confortable et leur forte attenuation...

Etching of fission tracks in silicate glasses by means of deionized water

International Nuclear Information System (INIS)

Dran, J.C.; Petit, J.C.

1985-09-01

Fission tracks have been revealed in silicate glasses with deionized water. Their sharp conical shape implies a marked enhancement of the dissolution rate along their core and consequently a cone angle and an etching efficiency (close to 100%) much higher than previously reported for glasses. We show that etching of fission tracks in natural environments has generally very limited geochemical implications except in specific cases such as that found in the Oklo uranium ores

Focus - Les établissements publics fonciers, des outils pour la biodiversité des zones humides : le cas de l’EPF Nord-Pas de Calais

Directory of Open Access Journals (Sweden)

LEMOINE, Guillaume

2017-09-01

Full Text Available Les établissements publics fonciers (EPF ont pour mission recycler le foncier dégradé pour favoriser, dans le cadre du développement durable, le renouvellement urbain, notamment pour aider la construction de logements tout en luttant contre l’étalement urbain. Devenus propriétaires de nombreux terrains, dont des zones humides, ils sont également concernés par la protection et la valorisation de ces espaces naturels. À travers l'exemple des actions menées par l’EPF Nord-Pas de Calais pour préserver ces zones humides, ce focus s'intéresse au rôle que peuvent jouer les EPF dans la préservation des espaces agricoles et naturels.

Author Details

African Journals Online (AJOL)

... un nouvel ennemi naturel Pour le controle de megalurothrips sjostedti (trybom) ... Perceptions paysannes et protection de l'environnement : gestion integree ... la dynamique des populations de maruca vitrata fabricius en culture du niebe, ...

Starting up a programme of atomic piles using compressed gas; Le demarrage d'un programme de piles atomiques a gaz comprime

Energy Technology Data Exchange (ETDEWEB)

Horowitz, J; Yvon, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-01

1) An examination of the intellectual and material resources which have directed the French programme towards: a) the natural uranium and plutonium system, b) the use of compressed gas as heat transfer fluid (primary fluid). 2) The parts played in exploring the field by the pile EL2 and G1, EL2 a natural uranium, heavy water and compressed gas pile, G1 a natural uranium, graphite and atmospheric air pile. 3) Development of the neutronics of graphite piles: physical study of G1. 4) The examination of certain problem posed by centres equipped with natural uranium, graphite and compressed carbon dioxide piles: structure, special materials, fluid circuits, maximum efficiency. Economic aspects. 5) Aids to progress: a) piles for testing materials and for tests on canned fuel elements, b) laboratory and calculation facilities. 6) Possible new orientations of compressed gas piles: a) raising of the pressure, b) enriched fuel, c) higher temperatures, d) use of heavy water. (author) [French] 1) Examen des ressources - intellectuelles et materielles - qui ont oriente le programme fran is vers: a) la voie de l'uranium naturel et du plutonium; b) l'emploi comme fluide pour le transfert de la chaleur (fluide primaire) d'un gaz comprime. 2) Le role d'exploration des piles EL2 et G1, EL2 pile a uranium naturel, eau lourde et gaz comprime, G1 pile a uranium naturel, graphite et air atmospherique. 3) Developpement de la neutronique des piles a graphite: l'etude physique de G1. 4) Examen de certains problemes poses par les centrales equipees de piles a uranium naturel, graphite et gaz carbonique comprime: structure, materiaux speciaux, circuits de fluides, optimisation. Aspects economiques. 5) Les auxiliaires du progres: a) piles pour essai de materiaux et pour essais de cartouches, b) moyens de laboratoire et moyens de calcul. 6) Orientations nouvelles possibles des piles a gaz comprime: a) elevation de la pression, b) combustible enrichi, c) temperatures elevees, d) emploi de l

Demography, maternal health and the epidemiology of malaria and other major infectious diseases in the rural department Tsamba-Magotsi, Ngounie Province, in central African Gabon

Directory of Open Access Journals (Sweden)

R. Zoleko Manego

2017-01-01

Full Text Available Abstract Background Sub-Saharan Africa is undergoing an epidemiological transition from a predominance of infectious diseases to non-communicable and lifestyle related conditions. However, the pace of this transition and the pattern of disease epidemiology are uneven between affluent urban and rural poor populations. To address this question for a remote rural region located in the central African rainforest region of Gabon, this study was conducted to assess reasons for health care attendance and to characterize the epidemiology of malaria and other major infectious diseases for the department of Tsamba Magotsi. Methods Major causes for health care attendance were collected from local hospital records. Cross sectional population based surveys were performed for the assessment of local malaria epidemiology. Pregnant women attending antenatal care services were surveyed as a sentinel population for the characterization of chronic viral and parasitic infections in the community. Results Infectious diseases were responsible for 71% (7469 of a total of 10,580 consultations at the formal health care sector in 2010. Overall, malaria – defined by clinical syndrome – remained the most frequent cause for health care attendance. A cross sectional malaria survey in 840 asymptomatic individuals residing in Tsamba Magotsi resulted in a Plasmodium spp. infection prevalence of 37%. The infection rate in 2–10 year old asymptomatic children – a standard measure for malaria endemicity – was 46% (100 of 217 with P. falciparum as predominant species (79%. Infection with other plasmodial species (P. ovale and P. malariae presented most commonly as coinfections (23.2%. Prevalence of HIV, HBV, and syphilis were 6.2, 7.3, and 2.5%, respectively, in cross-sectional assessments of antenatal care visits of pregnant women. Urogenital schistosomiasis and the filarial pathogens Loa loa and Mansonella perstans are highly prevalent chronic parasitic infections

The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

Energy Technology Data Exchange (ETDEWEB)

Ovaskainen, R

1999-11-01

Atomic Energy Agency (IAEA) from uranium milling and mining facilities (Australia, Canada, Gabon, Namibia, Czech Republic, France), were determined. These signatures form the basic register. The isotopic signatures are feasible in identifying the sample origin and in separating naturally occurring or background contributions from local anthropogenic sources. With the comparison of fingerprints of unknown samples to the isotopic fingerprints of samples of known origin, it is possible to trace back unknown samples to their origin or at least to exclude suspected origins in the case of non-identity of fingerprints. This was successfully demonstrated with a number of samples of unknown origin, which were measured during the study. Generally, no significant variability was observed in the n({sup 235}U)/n({sup 238}U) ratios except in the well known case of samples originating from Oklo (Gabon). Small variations in the n({sup 234}U)/n({sup 238}U) amount ratios were understood from the radiochemical mother-daughter relationship of the two isotopes involved. The detection limit for the n({sup 236}U)/n({sup 235}U) amount ratio (DL = 0.000001) was derived from blank measurements. The limit of quantitation 0.000003 was calculated as LQ=3DL. When the measured ratio exceeded the quantitation limit, the presence of {sup 236}U is explained. (orig.) 99 refs.

Maroc

African Journals Online (AJOL)

hadji

... en eaux abondantes, font de la province de Sidi Slimane, une zone agricole de première importance. Cette province constitue un collecteur naturel des eaux de surface. ..... cycles biologiques des moustiques (Diptera, Culicidae) au Maroc.

extractive resources, global volatility and africa's growth prospects1

African Journals Online (AJOL)

RAYAN_

3 International Monetary Fund, How to Manage the Commodity Call Coaster by. Vito Gasper ... countries such as Angola, Algeria, Egypt, Nigeria, Zambia, Gabon, ..... With currency depreciation, goods domestically produced become less.

9 CFR 93.505 - Certificate for swine.

Science.gov (United States)

2010-01-01

... certificate shall show that the entire region of origin is free of classical swine fever. (b) Swine from..., Equatorial Guinea, French Guiana, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Guyana, Haiti, India...

Liquefied natural gas; Gaz naturel liquefie

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-07-01

Total has interests in five of the world's largest liquefaction plants, which together account for roughly 40% of global LNG production capacity. This presentation illustrates the activities of the Group in the LNG sector. It discusses the advantages of the LNG as a clean energy, the LNG market, the liquefaction process and plants, the LNG trading marketing and shipping, the re-gasification and TOTAL promoting innovation. (A.L.B.)

LE CONCEPT DE RISQUE NATUREL URBAIN

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FLORINA GRECU

2011-11-01

Full Text Available The rapid development of the cities and growth of urban population have determined an inadequate use of some terms and concepts, in order to include in the research field specific phenomena and apply appropriate preventive measures. One such concept is about the hazards occurring inside the urban territory – urban hazards. The term urban can sometimes be associated to anthropogenic/industrial hazards or social hazards, and less to natural hazards.Natural hazards in urban areas are generally common for that geographical region. There is no such thing like special urban hazards. What is specific to urban area is the anthropogenic factor, which brings to risk various risk elements, including population, through his activities, density, or buildings. As a consequence, transition from hazard to risk is faster in time and space. Another feature is the multi- and interdisciplinary character of the genetic type of hazards. The so-called natural hazards are often caused by an anthropogenic factor. In the special literature urban risk is simply defined as the risk bounded by the urban territory or area, and is classified into: natural risk; industrial and technology risk; diffused risk.

Mer partagée, part maudite. La fabrique rituelle d’un horizon maritime : mer et sacré chez les pêcheurs Imrâgen (Mauritanie

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Hélène Artaud

2012-02-01

Full Text Available La mer a longtemps été perçue pour la société maure comme un monde en marge, étranger et étrange. Seule exception notable : la relation liant les communautés imrâgen à l’espace maritime. Dans la perception imrâgen de la mer se présentent d’emblée comme enchevêtrés les mondes naturels et surnaturels. Les modalités de leur articulation procèdent toutefois de logiques que seuls distinguent et maîtrisent certains initiés, dépositaires du « secret de la mer ». Quelques familles, issues des groupes maraboutiques Bârikalla et Buhubbayni, ont ainsi réussi à asseoir leur légitimité sur la côte par l’exercice de pouvoirs supposés influencer le cours des phénomènes naturels (vents, intensité des courants, cycle de la lune ou le comportement d’espèces marines (dauphins et tortues, dont ils ont fait leurs principaux émissaires. Quelles sont la nature, l’efficacité et les limites de ce pouvoir sur la mer? Comment inscrit-il le marabout au cœur de l’écologie imrâgen, le sacré au principe de l’équilibre naturel ? C’est à ces questionnements que nous nous proposons d’apporter quelques éléments d’analyse.

CERVICAL SPONDYLOTIC MYELOPATHY WITH FUNCTIONAL ...

African Journals Online (AJOL)

CERVICAL SPONDYLOTIC MYELOPATHY WITH FUNCTIONAL DISABILITY. LONG TERM RESULTS CONCERNING 18 PATIENTS OPERATED ON BY ANTERIOR APPROACH IN GABON MYELOPATHIES CERVICARTHROSIQUES INVALIDANTES. RESULTATS A LONG TERME DE 18 PATIENTS OPERES PAR VOIE ...

15 CFR 2013.1 - Designations.

Science.gov (United States)

2010-01-01

... LAW § 2013.1 Designations. In accordance with section 771(36) of the Tariff Act of 1930, as amended... Salvador Fiji Gabon Grenada Guatemala Honduras Jamaica Malaysia Malta Mauritius Morocco Namibia Panama...

Simulation of Naturally Fractured Reservoirs. State of the Art Simulation des réservoirs naturellement fracturés. État de l’art

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Lemonnier P.

2010-04-01

Full Text Available Naturally fractured reservoirs contain a significant amount of the world oil reserves. The production of this type of reservoirs constitutes a challenge for reservoir engineers. Use of reservoir simulators can help reservoir engineers in the understanding of the main physical mechanisms and in the choice of the best recovery process and its optimization. Significant progress has been made since the first publications on the dual-porosity concept in the sixties. This paper and the preceding one (Part 1 present the current techniques of modeling used in industrial simulators. The optimal way to predict matrix-fracture transfers at the simulator cell scale has no definite answer and various methods are implemented in industrial simulators. This paper focuses on the modeling of physical mechanisms driving flows and interactions/ exchanges within and between fracture and matrix media for a better understanding of proposed flow formula and simulation methods. Typical features of fractured reservoir numerical simulations are also described with an overview of the implementation of geomechanics effects, an application of uncertainty assessment methodology to a fractured gas reservoir and finally a presentation of a history matching methodology for fractured reservoirs. Les réservoirs naturellement fracturés contiennent une partie significative des réserves en huile mondiales. La production de ce type de réservoirs constitue un défi pour les ingénieurs de réservoir. L’utilisation des simulateurs de réservoir peut aider l’ingénieur de réservoir à mieux comprendre les principaux mécanismes physiques, à choisir le procédé de récupération le mieux adapté et à l’optimiser. Des progrès sensibles ont été réalisés depuis les premières publications sur le concept double-milieu dans les années soixante. Cet article et le précédent (Partie 1 présentent les techniques actuelles de modélisation utilisées dans les simulateurs

Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

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A. Ngomanda

2009-10-01

Full Text Available Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, Elaeis guineensis, and the shrub, Alchornea cordifolia (Euphorbiaceae. A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed were driven by human impact.

50 CFR Appendix A to Chapter I - Codes for the Representation of Names of Countries (Established by the International Organization...

Science.gov (United States)

2010-10-01

.... Finland FI. France FR. Gabon GA. Gambia GM. German Democratic Republic DD. Germany, Federal Republic of DE.... Liechtenstein LI. Luxembourg LU. Madagascar MG. Malawi MW. Malaysia MY. Maldives MV. Mali ML. Malta MT...

2387-IJBCS-Article- Momar Talla

African Journals Online (AJOL)

hp

mesure de satisfaire leurs besoins énergétiques alimentaires .... (2008) les moyens naturels de contrôle constituent des .... dernier auteur. Substances végétales dans la gestion des .... quoique les performances du spinosad ne soient pas ...

Physique ou leçons sur les principes généraux de la nature II

CERN Document Server

Aristote

2015-01-01

Extrait : ""Définition de la nature : elle est dans les êtres, le principe du mouvement et du repos. Des êtres naturels. L'existence de la nature est évidente ; il n'est pas nécessaire de la démontrer.""

Natural hazard management and sustainable development: a questionable link

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Lauren Andres

2009-03-01

Full Text Available This article examines the nature of the possible link between natural hazards and sustainable development through a study of the area to the south of Grenoble in the French Alps, a zone subject to two major natural hazards: the extensive landslide known as the "Séchilienne Ruins" and flooding from the Romanche and Drac rivers. More specifically, the study analyzes the assumed transition from the management of natural hazards to the sustainable management of an area subject to natural hazards and is divided into three stages. Thus the link between natural hazards and sustainability is considered as: 1 an association that is entirely relative, 2 one that is logical but limited in the field, 3 one that is above all indirect. The interactions identified between risk and sustainability, in legislative as well as ideal and operational terms, are found to be complex and not necessarily explicit. They depend in particular on the juxtaposition of multiple territorial scales or spatial boundaries (national to local that bring into conflict the different strategies of the actors involved – from decision-makers to technical specialists.Cet article questionne la nature du lien envisageable entre risque naturel et développement durable à travers l’étude du territoire du sud grenoblois, soumis notamment à deux aléas naturels majeurs : le mouvement de terrain de grande ampleur dit des « Ruines de Séchilienne » et les probables crues de la Romanche et du Drac. Trois étapes structurent cette réflexion questionnant la transition supposée entre une gestion des risques naturels et une gestion durable des territoires soumis aux risques naturels : une association toute relative, un lien logique mais limité sur le terrain, une relation surtout indirecte. Les interactions identifiées, en termes législatifs mais aussi idéels et opérationnels, entre risque et durabilité se révèlent ainsi complexes et ne sont pas forcément explicites ; elles d

à l'encoche sèche

African Journals Online (AJOL)

Chez Hevea brasiliensis, la production de latex est affectée par l'encoche sèche qui se manifeste par l'arrêt de l'écoulement de ... coagulation pour donner le caoutchouc naturel. ..... relationship between latex sugar content, the metabolic ...

Evaluation des conditions de germination des noyaux de Grewia ...

African Journals Online (AJOL)

personnel

31 janv. 2014 ... graines de G.coriacea afin de parvenir à un meilleur taux de germination naturellement médiocre. ... fourchettes) et comme matériau de ...... contre, les chocs thermiques par l'eau .... stockage et de la durée de chauffage.

The neutron balance of the natural reactors at Oklo

International Nuclear Information System (INIS)

Naudet, R.; Filip, A.

1975-01-01

The authors discuss the main parameters determining criticality: the concentration of fissionable nuclei in the uranium; concentration of neutron-capturing nuclei in the gangue; concentration of uranium in the ore and rearrangement of the uranium to form ''critical masses''; amount of water present. Moderation was caused partly by the water of constitution of the clays in the gangue. Examination of the available data indicates that criticality could quite well have been achieved. A computer code (BINOCLE) was written for handling the neutron physics problems raised by the natural reactors. This very simple code, which can nevertheless handle the important points in sufficient detail, is well suited for describing the ores, providing a clear breakdown of the neutron balance and the quantities necessary for interpreting the analyses. It is designed to serve as a subprogram to a series of other codes: one-dimensional criticality; point evolution; spatial evolution; consideration of thermal transfers. Results showing the role of the main parameters are presented. The physical quantities measured by fission-product analysis are also found: proportions of fast fissions; conversion coefficient; spectral indices

Squares of the natural numbers in radiation protection

International Nuclear Information System (INIS)

Parker, H.M.

1977-01-01

An informal history of radiation protection is given. The following topics are included: the discovery of x rays and their effects, the formation of the International Committee on X-ray and Radium Protection, the Manhattan Project and its plutonium aspects, dose limits and their origin, the increase in antinuclear writings, the publication of reports on radiation levels and effects, the role of the EPA in medical radiation, and the Oklo phenomenon. Recommendations for NCRP and ICRP actions are given. The publication also contains brief biographies of Lauriston S. Taylor and Herbert M. Parker

African Journals Online: Suriname

African Journals Online (AJOL)

El Salvador, Equatorial Guinea, Eritrea, Estonia, Ethiopia, Faeroe Islands, Falkland Islands (Malvinas), Fiji, Finland, France, France, MEtropolitan, French Guiana, French Polynesia, French Southern Territories, Gabon, Gambia, The, Georgia, Germany, Ghana, Gibraltar, Greece, Greenland, Grenada, Guam, Guatemala ...

African Journals Online: Argentina

African Journals Online (AJOL)

El Salvador, Equatorial Guinea, Eritrea, Estonia, Ethiopia, Faeroe Islands, Falkland Islands (Malvinas), Fiji, Finland, France, France, MEtropolitan, French Guiana, French Polynesia, French Southern Territories, Gabon, Gambia, The, Georgia, Germany, Ghana, Gibraltar, Greece, Greenland, Grenada, Guam, Guatemala ...

African Journals Online: Angola

African Journals Online (AJOL)

El Salvador, Equatorial Guinea, Eritrea, Estonia, Ethiopia, Faeroe Islands, Falkland Islands (Malvinas), Fiji, Finland, France, France, MEtropolitan, French Guiana, French Polynesia, French Southern Territories, Gabon, Gambia, The, Georgia, Germany, Ghana, Gibraltar, Greece, Greenland, Grenada, Guam, Guatemala ...

African Journals Online: Netherlands

African Journals Online (AJOL)

El Salvador, Equatorial Guinea, Eritrea, Estonia, Ethiopia, Faeroe Islands, Falkland Islands (Malvinas), Fiji, Finland, France, France, MEtropolitan, French Guiana, French Polynesia, French Southern Territories, Gabon, Gambia, The, Georgia, Germany, Ghana, Gibraltar, Greece, Greenland, Grenada, Guam, Guatemala ...

African Journals Online: Mongolia

African Journals Online (AJOL)

... Faeroe Islands, Falkland Islands (Malvinas), Fiji, Finland, France, France, MEtropolitan, French Guiana, French Polynesia, French Southern Territories, Gabon, Gambia, The, Georgia, Germany, Ghana, Gibraltar, Greece, Greenland, Grenada, Guam, Guatemala, Guernsey, Guinea, Guinea-Bissau, Guyana, Haiti, Honduras ...

The ancient tropical rainforest tree Symphonia globulifera L. f. (Clusiaceae) was not restricted to postulated Pleistocene refugia in Atlantic Equatorial Africa.

Science.gov (United States)

Budde, K B; González-Martínez, S C; Hardy, O J; Heuertz, M

2013-07-01

Understanding the history of forests and their species' demographic responses to past disturbances is important for predicting impacts of future environmental changes. Tropical rainforests of the Guineo-Congolian region in Central Africa are believed to have survived the Pleistocene glacial periods in a few major refugia, essentially centred on mountainous regions close to the Atlantic Ocean. We tested this hypothesis by investigating the phylogeographic structure of a widespread, ancient rainforest tree species, Symphonia globulifera L. f. (Clusiaceae), using plastid DNA sequences (chloroplast DNA [cpDNA], psbA-trnH intergenic spacer) and nuclear microsatellites (simple sequence repeats, SSRs). SSRs identified four gene pools located in Benin, West Cameroon, South Cameroon and Gabon, and São Tomé. This structure was also apparent at cpDNA. Approximate Bayesian Computation detected recent bottlenecks approximately dated to the last glacial maximum in Benin, West Cameroon and São Tomé, and an older bottleneck in South Cameroon and Gabon, suggesting a genetic effect of Pleistocene cycles of forest contraction. CpDNA haplotype distribution indicated wide-ranging long-term persistence of S. globulifera both inside and outside of postulated forest refugia. Pollen flow was four times greater than that of seed in South Cameroon and Gabon, which probably enabled rapid population recovery after bottlenecks. Furthermore, our study suggested ecotypic differentiation-coastal or swamp vs terra firme-in S. globulifera. Comparison with other tree phylogeographic studies in Central Africa highlighted the relevance of species-specific responses to environmental change in forest trees.

Premarital fertility and HIV/AIDS in sub- Saharan Africa

African Journals Online (AJOL)

Administrator

relatively low HIV prevalence (Liberia, Madagascar, Gabon, Congo), or high levels of HIV ... impact on premarital fertility and HIV infection among women. ... fécondité avant le mariage et le VIH/SIDA dans les pays africains sub-sahariens.

The casting of western sculpture during the XIXth century: sand casting versus lost wax casting

NARCIS (Netherlands)

Beentjes, T.P.C.

2014-01-01

This paper will discuss research into bronze casting techniques as practiced during the XIXth and early XXth century. Both natural sand casting (fonte au sable naturel) and lost wax casting (fonte à la cire perdue) were employed during this period and sometimes rivalled for commissions. Before the

12 Mwepu 03.pmd

African Journals Online (AJOL)

Owner

23 juil. 2008 ... Une lecture attentive de l'œuvre d'Henri Lopes conduirait maints lecteurs .... kou qui estime que « les femmes ne doivent jamais faire des .... d'ordinaire personne ne s'attarde parce qu'ils semblent « naturels » et aller de soi ».

La traversée de l'Atlantique ou la mort ? Une réflexion critique sur la ...

African Journals Online (AJOL)

19 mars 2018 ... physique et naturel, trouvera une interprétation figurative dans cet article. Il s'agit ... Il va de soi que dans certaines ... soi dans la vision du monde d'un sujet. ..... Cependant en terme de créolisation, Glissant estime que: “La ...

Exploitation Agricole des Berges : Une Strategie D'Adaptation aux ...

African Journals Online (AJOL)

et socio-économique. ... dynamique des paysages agraires et son impact sur le capital naturel surtout sur les .... favoriser leur germination et amorcer leur croissance. ..... similaires ont été relevées au Bénin où l'impact humain se traduit par le ...

Distribution of a Community of Mammals in Relation to Roads and Other Human Disturbances in Gabon, Central Africa

Science.gov (United States)

Vanthomme, Hadrien; Kolowski, Joseph; Korte, Lisa; Alonso, Alfonso

2013-01-01

Abstract We present the first community-level study of the associations of both roads and other human disturbances with the distribution of mammals in Gabon (central Africa). Our study site was in an oil concession within a littoral mosaic landscape. We conducted surveys along 199 line transects and installed camera traps on 99 of these transects to document mammal presence and abundance. We used generalized linear mixed-effect models to document associations between variables related to the ecosystem (land cover, topography, and hydrology), roads (coating, width of rights of way, condition, type of vehicle used on the road, traffic level, affiliation of users, and general type of road), and other human disturbances (urbanization, agriculture, hunting, logging, gathering, and industrial activities) and the abundance or presence of 17 species or groups of mammals including elephant (Loxodonta cyclotis), buffalo (Syncerus caffer), sitatunga (Tragelaphus spekei), red river hog (Potamochoerus porcus), smaller ungulates, gorilla (Gorilla gorilla), chimpanzee (Pan troglodytes), side-striped jackal (Canis adustus), carnivores, monkeys, and large rodents. Some types of roads and other human disturbances were negatively associated with the abundance or presence of elephants, buffalos, gorillas, sitatungas, some monkeys, and duikers. The pattern of associations of mammals with roads and other human disturbances was diverse and included positive associations with road presence (red river hog, some monkeys, and duikers), agriculture (sitatunga, small carnivores, and large rodents) and industrial activities (sitatunga, red river hog, red duikers, and side-striped jackal). Our results suggest that the community of mammals we studied was mostly affected by hunting, agriculture, and urbanization, which are facilitated by road presence. We recommend increased regulation of agriculture, hunting, and road building in the area. Distribución de una Comunidad de Mamíferos en Relaci

Browse Title Index

African Journals Online (AJOL)

Items 501 - 550 of 683 ... Ground cavity nest temperatures and their relevance to Blue Swallow ... Nests and eggs of the Black-headed Bee-eater (Merops breweri) in Gabon, with ... Notes on the breeding biology of the African Broadbill Smithornis ...

Classification of Rhinoentomophthoromycosis into Atypical, Early, Intermediate, and Late Disease: A Proposal

NARCIS (Netherlands)

Blumentrath, Christian G.; Grobusch, Martin P.; Matsiégui, Pierre-Blaise; Pahlke, Friedrich; Zoleko-Manego, Rella; Nzenze-Aféne, Solange; Mabicka, Barthélemy; Sanguinetti, Maurizio; Kremsner, Peter G.; Schaumburg, Frieder

2015-01-01

Rhinoentomophthoromycosis, or rhino-facial conidiobolomycosis, is a rare, grossly disfiguring disease due to an infection with entomophthoralean fungi. We report a case of rhinoentomophthoromycosis from Gabon and suggest a staging system, which provides information on the prognosis and duration of

2755-IJBCS-Article-Zinga Koumba Christophe R

African Journals Online (AJOL)

hp

3College of Bioresource Science, Nihon University, Fugisawa City, Kanagawa 252-0880, Japan. 4Primate .... mode d'interaction sociale (Tutin et al., 1997 ;. Furuichi et al. ... littérature de la flore du Gabon (Raponda- ..... Revue d'Élevage et.

Caractéristiques sociodémographiques associées au risque de ...

African Journals Online (AJOL)

Caractéristiques sociodémographiques associées au risque de transmission du VIH, du VHC et de Treponema pallidum par les donneurs de sang de premier don de Libreville (Gabon) : dynamique trisannuelle des infections de 2009 à 2015.

L'algue alimentaire Spirulina sp. Découverte de lacs naturels à Wadi el Natroun en République Arabe d'Egypte Spirulina Sp. Food Alga. Discovery of Natural Lakes At Wadi El Natrun in the Arab Republic of Egypt

Directory of Open Access Journals (Sweden)

Abdin El Sherif S. A.

2006-11-01

Full Text Available Bien que connue depuis les temps les plus anciens, la dépression de Wadi el Natroun n'avait jamais été prospectée autrement que pour sa richesse en sels minéraux. C'est en 1977 que les auteurs, cherchant à savoir s'il existait des lacs naturels à Spirulines en République Arabe d'Égypte, découvrirent dans la dépression de Wadi el Natroun certains lacs comme Abou Gobara et El Khadra où croissaient spontanément les algues spirulines. Le climat du site, l'origine et la composition des eaux, ainsi que la concentration en algues, ont été étudiés afin d'estimer la productivité du site en vue d'une éventuelle exploitation industrielle. L'exploitation de ces lacs permettrait de mettre en valeur le site de Wadi el Natroun par la production d'une substance très riche en protéine pour l'alimentation humaine dont à tant besoin la République Arabe d'Égypte. Even though it has been known from olden days, the depression of Wadi el Natrun had never been prospected other than for its wealth of mineral salts. It was in 1977 that the authors began searching for natural lakes with Spirulina algae in the Arab Republic of Egypt and, in the depression of Wadi el Natrun, discovered varions lakes such as Abu Gobara and El Khadra where Spirulina algae grew in a natural state. The climate of the site, the original and composition of the water as well as the algae concentration were analyzed to evaluate the productivity of the site for eventual industrial exploitation. The exploitation of these lakes would give value to the Wadi el Natrun site by producing a very protein-rich substance for human nourishment which the Arab Republic of Egypt needs so badly.

Evaluation des potentiels nutritionnels et technologiques de ...

African Journals Online (AJOL)

Par ailleurs, le bissap avec des teneurs en anthocyanes de 767 et 967 mg/100 g respectivement pour les varietes THAI et CLT 92, constitue une bonne source de colorant naturel. The physico-chemical, biochemical and nutritional characterization of the baobab fruit (Adansonia digitata), Ditax (Detarium senegalensis) fruit, ...

IDRA 2016 Call for Applications Word doc_EN

International Development Research Centre (IDRC) Digital Library (Canada)

Carole Labrie

2016-05-18

May 18, 2016 ... Gabon, Guinea, Guinea Bissau, Liberia, Maldives, Mauritania, Monserrat, Papua New Guinea, Small. Island States [including Comoros, Mauritius, São Tomé and Principe, Seychelles, Timor-Leste and. Oceania (Cook Islands, Fiji, Nauru, Kiribati, Palau, Marshall Islands, Niue, Samoa, Solomon Islands,.

Antioxydants naturels végétaux

Directory of Open Access Journals (Sweden)

Rolland Yohan

2004-11-01

Full Text Available Oxidation of lipids corresponds to the degradation of fatty acids by a continuation of sequential reactions : the decomposition of peroxides formed on the fatty chains after the attack by radicalaires compounds ends in the production of aldéhydes, cétones, acids, alcohols and go to a loss of the organoleptic and nutritional qualities (characteristic rancy smell and taste, thus a significant loss of economic value. The synthetic antioxidants (BHT, BHA are effective, but their use is of pleased in more controversial. It is thus advisable to study with attention the plant natural antioxidants. The antioxidizing properties of the plant products are given by a certain number of tests as the test to the DPPH or the test ORAC in aqueous environment, and the measure of the index of peroxides or the Rancimat for the lipophilic phases. Certain tests are above all models of study, and few are really recognized, however certain standards are outlined, and the standardization arrives finally (cf the test ORAC, reference USDA. Among the compound vegetables which stand out very sharply at the level of their antioxidizing property, polyphénols are the most represented in the vegetal reign. It is a very wide family, but the extracts of grape seeds or tea are now well identified, and present results in the fight against the oxidation completely surprising.

Natural repository analogue program. Progress report, January 1-March 30, 1982

International Nuclear Information System (INIS)

Curtis, D.B.

1982-06-01

Lead and uranium isotopic abundances in rocks from the Oklo mine show large deficiencies of radiogenic lead in the mineralized regions and enormous excesses of this element outside the uraniferous zones. A fracture lined with secondary minerals and its host rock from distances as far as approx. 13 meters away contain lead that was deposited contemporaneously. The isotopic composition of lead in these samples varies systematically as a function of distance from the fracture. This regularity may reflect the nature of the processes that transported lead from the ores and deposited it in the surrounding rocks

Development and Design of Sludge Freezing Beds

Science.gov (United States)

1988-12-01

Wastewater Treatment/Disposal/Reuse. New York: McGraw Hill, 2nd ed. Morin, W., R. Lewandowski and R. Zaloum (1986) Le traitement des boues a l’aide du gel...degel naturel et epandage des boues en foret. Draft report for Environment Canada, Mon- treal. National Oceanic and Atmospheric Administration (1984

2299-IJBCS-Article-Roger Niebié

African Journals Online (AJOL)

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1Département Substances Naturelles/IRSAT/CNRST, 03 BP 7047 Ouagadougou 03, Burkina Faso. 2 Laboratoire de Chimie Organique et de ... 2000) ainsi que les risques de maladies cardio- vasculaires (Riccioni, 2009). La production ... obtenus par séchage naturel à l'ombre au laboratoire pendant sept (07) jours, soit à.

Cerebro-meningeal infections in HIV-infected patients: a study of ...

African Journals Online (AJOL)

Background: Cerebro-meningeal pathology is common in human immunodeficiency virus (HIV) infection and the aetiology is often difficult to ascertain with certainty. Objective: To describe the major suspected and identified causes of meningeal or encephalitic syndromes in HIV infection in Libreville, Gabon. Methods: A ...

from spices to oil: sea power and the sea routes around the cape

African Journals Online (AJOL)

"He who is master of the sea is master of world trade. And he who is master of ... the USA emerged as the leading naval power.g) ..... fered a trade deficit in 1986 in trading with in- dustrialized ... Ecuador, Gabon, Indonesia and Nigeria), are.

List of Higher Risk Countries and Territories (IDRC, July 2013 ...

International Development Research Centre (IDRC) Digital Library (Canada)

IDRC CRDI

List of Higher Risk Countries and Territories (IDRC, July 2013). Afghanistan. Central African Republic. Congo, Brazzaville. Congo, Democratic Republic of. Chad. Cuba. Eastern Europe, countries of. Equatorial Guinea. Eritrea. Former Soviet Union, countries of. Gabon. Guinea-Bissau. Iran. Iraq. Korea, Democratic People's ...

Effects of oil pollution on aquatic macroinvertebrate assemblages in ...

African Journals Online (AJOL)

Macroinvertebrate assemblages from uncontaminated and contaminated sites in the Gamba Complex (Gabon) were compared, the latter sites having been subjected to ongoing oil spills since the 1970s. Vegetation communities surrounding the sites included savannah, shrub–scrub, palm forest, gallery forest and thick ...

Shared breastfeeding in central Africa

NARCIS (Netherlands)

Ramharter, Michael; Chai, Sanders K.; Adegnika, Ayola A.; Klöpfer, Anna; Längin, Matthias; Agnandji, Selidji T.; Oyakhirome, Sunny; Schwarz, Norbert G.; Grobusch, Martin P.; Issifou, Saadon; Kremsner, Peter G.

2004-01-01

In this study, shared breastfeeding is described asa novel risk factor for vertical HIV transmission. This cross-sectional survey conducted in the central African country Gabon found that 40% of lactating mothers also breastfed other children than their own, and as many children were additionally

Minority representation in a semi-democratic regime: the Georgian case

DEFF Research Database (Denmark)

Zollinger, Daniel; Bochsler, Daniel

2012-01-01

Guinea, Tanzania, Gabon, Kenya, Mauritania, and Congo (Brazzaville). This article highlights the impact of the electoral system and the importance of political plurality and electoral district design in such contexts. The article argues that the interests of minorities are best protected if they can...

Lexicography in Gabon: A Survey1

African Journals Online (AJOL)

Gabonese lexicography were missionaries or colonial administrators. ... Furthermore, in those contributions, the theory of lexicography is largely unknown and ..... model developed by the French structuralists in the field of semantics which is.

Lexicography in Gabon: A Survey1

African Journals Online (AJOL)

graphic works are hardly ever based on authentic data corpora of the ... la matière de l'instruction, la langue de l'administration et celle des médias. ... GUISTIQUE, BESOINS LEXICOGRAPHIQUES, TRAVAUX LEXICOGRAPHIQUES, BASE ...

INTERCOMPARISON ON THE MEASUREMENT OF THE QUANTITY PERSONAL DOSE EQUIVALENT HP(10) IN PHOTON FIELDS. LINEARITY DEPENDENCE, LOWER LIMIT OF DETECTION AND UNCERTAINTY IN MEASUREMENT OF DOSIMETRY SYSTEMS OF INDIVIDUAL MONITORING SERVICES IN GABON AND GHANA.

Science.gov (United States)

Ondo Meye, P; Schandorf, C; Amoako, J K; Manteaw, P O; Amoatey, E A; Adjei, D N

2017-12-01

An inter-comparison study was conducted to assess the capability of dosimetry systems of individual monitoring services (IMSs) in Gabon and Ghana to measure personal dose equivalent Hp(10) in photon fields. The performance indicators assessed were the lower limit of detection, linearity and uncertainty in measurement. Monthly and quarterly recording levels were proposed with corresponding values of 0.08 and 0.025 mSv, and 0.05 and 0.15 mSv for the TLD and OSL systems, respectively. The linearity dependence of the dosimetry systems was performed following the requirement given in the Standard IEC 62387 of the International Electrotechnical Commission (IEC). The results obtained for the two systems were satisfactory. The procedure followed for the uncertainty assessment is the one given in the IEC technical report TR62461. The maximum relative overall uncertainties, in absolute value, expressed in terms of Hp(10), for the TL dosimetry system Harshaw 6600, are 44. 35% for true doses below 0.40 mSv and 36.33% for true doses ≥0.40 mSv. For the OSL dosimetry system microStar, the maximum relative overall uncertainties, in absolute value, are 52.17% for true doses below 0.40 mSv and 37.43% for true doses ≥0.40 mSv. These results are in good agreement with the requirements for accuracy of the International Commission on Radiological protection. When expressing the uncertainties in terms of response, comparison with the IAEA requirements for overall accuracy showed that the uncertainty results were also acceptable. The values of Hp(10) directly measured by the two dosimetry systems showed a significant underestimation for the Harshaw 6600 system, and a slight overestimation for the microStar system. After correction for linearity of the measured doses, the two dosimetry systems gave better and comparable results. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Is Apartheid ook op ekonomiese grond geregverdig?

Directory of Open Access Journals (Sweden)

B. van Deventer

1956-03-01

Full Text Available Die mening word vandag dikwels uitgespreek (ook deur Nasionaliste dat apartheid nie op ekonomiese gronde geregverdig kan word nie; of anders gestel, dat apartheid van die blankes te groot offers sal verg; of nog sterker gestel, dat die blankes op ekonomiese gebied nie sonder die naturel sal kan klaarkom nie.

2068-IJBCS-Article-Saidou Ousseina

African Journals Online (AJOL)

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A la Station Sahélienne Expérimentale de Toukounous, le bétail est nourri essentiellement sur pâturage naturel. ... Dans cette zone, les variations climatiques actuelles et passées ... L'étude s'est déroulée à la Station .... La densité globale des.

Activité antioxydante et antiseptique de l'huile essentielle et des ...

African Journals Online (AJOL)

Samah

piégeage des radicaux libres DPPH en comparaison avec le BHT ainsi ... qui ont une importance croissante grâce à leur rôle d'antioxydants naturels [4]. Pendant des siècles, les espèces du genre Thymus ont été utilisées couramment dans ...

Résultats de recherche | Page 427 | CRDI - Centre de recherches ...

International Development Research Centre (IDRC) Digital Library (Canada)

Migratory Fishes of South America : Biology, Fisheries, and Conservation Status. Les espèces de poissons qui migrent dans les grandes rivières d'Amérique du Sud alimentent d'importantes pêcheries locales mais sont peut connues en dehors de leur parcours naturel. Publication Date. 1 janvier 2004. Livres ...

Résultats de recherche | Page 426 | CRDI - Centre de recherches ...

International Development Research Centre (IDRC) Digital Library (Canada)

Migratory Fishes of South America : Biology, Fisheries, and Conservation Status. Les espèces de poissons qui migrent dans les grandes rivières d'Amérique du Sud alimentent d'importantes pêcheries locales mais sont peut connues en dehors de leur parcours naturel. Publication Date. 1 janvier 2004 ...

Détermination des radionucléides dans le repas. Application aux ...

African Journals Online (AJOL)

40 sont des radionucléides naturels présents dans les riz, les tubercules, les bouillons et les friandises. Dans les quatre échantillons des repas du Riz analysés, les activités spécifiques en potassium-40 sont différentes. Cette différence est ...

Untitled

African Journals Online (AJOL)

Jane Goodall Insitute/Université de Yaoundé1. RESUME. L'introduction des plantes dans un nouvel environnement a toujours comporté des risques. Le texte ci-dessous est la résultante des investigations d'ordre bibliographique et des observations faites dans le milieu naturel camerounais. Les informations provenant de ...

Exploration des scenarios d'adaptation : leishmaniose cutanée et ...

International Development Research Centre (IDRC) Digital Library (Canada)

... des écosystèmes naturels contrastés, semi-aride et sub-humide respectivement. Les chercheurs se proposent de renforcer les capacités des acteurs (chercheurs, professionnels et citoyens) de réduire la vulnérabilité des populations aux conditions environnementales, conduisant à une meilleure gestion du risque.

Clonal structure of Staphylococcus aureus colonizing children with sickle cell anaemia and healthy controls

NARCIS (Netherlands)

Schaumburg, F.; Biallas, B.; Alabi, A. S.; Grobusch, M. P.; Feugap, E. N.; Lell, B.; Mellmann, A.; Peters, G.; Kremsner, P. G.; Becker, K.; Adegnika, A. A.

2013-01-01

Children with sickle cell anaemia (SCA) might carry hospital-associated bacterial lineages due to frequent hospital stays and antibiotic treatments. In this study we compared Staphylococcus aureus from SCA patients (n=73) and healthy children (n=143) in a cross-sectional study in Gabon. S. aureus

78 FR 78159 - Delegation of Authority Under Section 506(a)(1) of the Foreign Assistance Act of 1961, as Amended

Science.gov (United States)

2013-12-24

... assistance to France, the African Union, the Republic of the Congo, Chad, Cameroon, Gabon, Burundi, Uganda, Rwanda, and other countries that contribute forces to the African Union-led International Support Mission in the Central African Republic and to make the determinations required under such section to direct...

Taxonomic novelties in African Dracaena (Dracaenaceae)

NARCIS (Netherlands)

Damen, T.H.J.; Burg, van der W.J.; Wiland-Szymańska, J.; Sosef, M.S.M.

2018-01-01

In preparing the treatment of Dracaena for Flore du Gabon and Flore d’Afrique centrale, a relatively high number of taxonomic and nomenclatural novelties were discovered; these are presented here. Within Dracaena five species and one forma are described as new, D. bushii, D. haemanthoides, D.

Salacia hallei, a name for a rare Celastraceae species from western central Africa

NARCIS (Netherlands)

Jongkind, C.C.H.

2006-01-01

A new species, Salaria hallei (Celastraceae), from Gabon and Angola is described and illustrated. The species is unique by the combination of glabrous leaves with a transverse tertiary venation, a conspicuous pedunculate inflorescence and glabrous flowers with 3-4 mm wide, almost round, petals and 4

Séroprévalence du virus de l'immunodéficience humaine, des virus ...

African Journals Online (AJOL)

SARAH

28 févr. 2017 ... 3 Centre de Traitement Ambulatoire VIH/SIDA de Koula-Moutou, Koula-Moutou, Gabon ... déterminée par les tests rapides d'orientation diagnostic. Sur un total de 614 .... recherchés par le test non treponémique RPR (Rapide.

Évaluation in vitro de l'activité antimicrobienne de l'extrait aqueux d ...

African Journals Online (AJOL)

SARAH

31 juil. 2016 ... Agrobiologie, Université des Sciences et Techniques de Masuku (USTM), BP 067 Franceville, Gabon. 2 Laboratoire ... 4 Institut de Recherche en Écologie Tropicale, Herbier National, BP 13354 Libreville. ..... VIH. Médecine et Maladies Infectieuses 32. (12):696-703 ... Diagnostic Microbiology and Infectious.

Population dynamics of Garcinia lucida (Clusiaceae) in Cameroonian Atlantic forests.

NARCIS (Netherlands)

Guedje, N.M.; Lejoly, J.; Nkongmeneck, B.A.; Jonkers, W.B.J.

2003-01-01

Garcinia lucida Vesque (Clusiaceae) is a highly valued non-timber forest tree. The bark and the seeds are exploited and commercialised for medicinal purposes and palm wine processing in Cameroon, Gabon and Equatorial Guinea. The bark is often removed over almost the entire circumference of the stem,

2736-IJBCS-Article-Ernest Amoussou

African Journals Online (AJOL)

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² Laboratoire Pierre PAGNEY, Climat, Eau, Ecosystème et Développement ... 3 Institut National de Recherches Agronomiques du Bénin (INRAB), Direction ... Les processus naturels et humains ont des conséquences sur les capacités ..... Ces communes sont situées à la limite du .... l'ensemble des initiatives prises par les.

Analysis of Cameroon newspaper coverage of cross border conflicts

African Journals Online (AJOL)

Nexus of conflict reporting: Analysis of Cameroon newspaper coverage of cross ... The conflicts taking place in the Central African Republic, Chad, Nigeria and Gabon have raised ... Consequently, it is in the interest of the public .... of Humanitarian Affairs (OCHA, 2014), ... As what concerns the case of Nigeria, UNHCR.

Author Details

African Journals Online (AJOL)

Nguelet, Fred Loique Mindonga. Vol 10, No 6 (2016) - Articles Vegetarian diet in Guenon and Mangabey monkeys of Moukalaba-Doudou National Park, Gabon: similarities and differences. Abstract PDF. ISSN: 1997-342X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors ...

What French for Gabonese French Lexicography

African Journals Online (AJOL)

user

administration, international relations, teaching, the media, trade, transport, tourism, .... The present study refutes such as reductive definition of what Gabonese .... language than French limits itself to public speeches and support to linguistics ...... sité Omar Bongo du Gabon: Série Lettres, Droit, Sciences et Médecine: 55-63.

Les plantes tinctoriales d'Afrique Centrale : enquête ethnobotanique ...

African Journals Online (AJOL)

SARAH

30 juil. 2013 ... naturels n'a pas été suffisamment exploré. Le domaine reste encore non valorisé, malgré l'utilisation traditionnelle de nombreuses plantes pour leurs propriétés colorantes : Curcuma longa pour la cuisine, Lawsonia inermis (Henné) ou. Pterocarpus soyauxii pour la cosmétique,. Indigofera tinctoria pour les ...

Les Tinamous. Tinami

NARCIS (Netherlands)

Schlegel, H.

1880-01-01

Les Tinamous forment une tribu d’oiseaux parfaitement isolée et circonscrite, et bornée à la partie de l’Amérique comprise entre le Mexico méridional et la Patagonie. Ils se rattachent, toutefois, naturellement à l’ordre des Gallinae, tout en offrant certaines affinités avec l’ordre des Autruches.

La nanotechnologie prolonge la durée de conservation des fruits frais

International Development Research Centre (IDRC) Digital Library (Canada)

9 oct. 2015 ... Une équipe de recherche internationale met au point des applications fondées sur la nanotechnologie d'hexanal, un extrait végétal naturel qui permet de ... Des chercheurs de l'Université de Guelph, de la Tamil Nadu Agricultural University en Inde et de l'Industrial Technology Institute au Sri Lanka ...

Flore vasculaire rare et endemique de la peninsule de l'Edough ...

African Journals Online (AJOL)

sous le nom de« biodiversity hotspots» [2]. La flore du bassin mediterraneen est aujourd'hui tres serieusement menacee, en raison de la forte regression des milieux naturels sous l' action de l 'homme, mais aussi parce que cette region serait l'une des plus exposees aux changements climatiques globaux [3-5]. Cette flore ...

Analyse de la croissance de Gymnogongrus patens Agardh de la ...

African Journals Online (AJOL)

AKA Boko

Le suivi de la croissance in situ de cette espèce est indispensable pour son exploitation industrielle au Maroc. Dans le cadre d'un programme de recherche pour la valorisation des carraghénophytes marocains, notre travail a eu pour objectif d'étudier la biologie en milieu naturel de l'espèce Gymnogongrus patens.

: tous les projets | Page 301 | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

Programme: Alimentation, environnement et santé. Financement total : CA$ 642,600.00. Prévision et prévention de zoonoses émergentes chez les animaux sauvages. Projet. Les zoonoses émergentes et résurgentes au Brésil à l'heure actuelle sont le fait d'interactions complexes entre les systèmes naturels et humains.

DOI: 10.18697/ajfand.79.15930 12455 AGRODIVERSITE, GESTION ...

African Journals Online (AJOL)

documenter les valeurs socioculturelles, économiques, alimentaires et les pratiques paysannes de ... bien-être humain et l'amélioration de la santé. ..... naturel), les ignames disposent de leurs conditions optimales de croissance et de .... dynamique de son capital de diversité répond donc à deux modèles : un modèle en.

Les changements climatiques brouillent les prédictions des faiseurs ...

International Development Research Centre (IDRC) Digital Library (Canada)

8 oct. 2010 ... Les faiseurs de pluie fondent leurs prédictions sur l'observation attentive des phénomènes naturels, notamment le bourgeonnement et la floraison des ... intègre le savoir autochtone, désormais mieux compris, à son programme sur la gestion des risques liés aux catastrophes, en cours d'élaboration.

Évaluation de la contamination parasitologique des eaux usées ...

African Journals Online (AJOL)

SARAH

30 sept. 2013 ... l'équilibre écologique du milieu naturel, surtout par la pollution des eaux de surface et des nappes phréatiques et un risque sanitaire par contamination microbiologique ou parasitaire (Diop, 1994 ;. Khallaayoune, 2005 ; Sawadogo et al., 2005). Pour atténuer ces impacts négatifs des eaux usées brutes sur ...

40 ans de linguistique textuelle et didactisation du français langue étrangère

DEFF Research Database (Denmark)

Lundquist, Lita

2016-01-01

particulièrement l’apprentissage de la lecture de textes académiques en français. En même temps, on montrera comment l’analyse et la compréhension de textes ne s’arrêtent pas au linguistique et au textuel ; bien au contraire, la linguistique textuelle enchainera naturellement sur le cognitif et sur le culturel. En...

983-IJBCS-Article-Charababil Mohamed M

African Journals Online (AJOL)

hp

Qualitatives. DAF, SEF: Mayotte; 90 p. Pascal O. 2002. Plantes et forêts de Mayotte. Patrimoines Naturels 53, MNHN, IEGB,. 108p. Rajemison AH. 2010. Typologie de la végétation rémanente en vue d'une restauration écologique. Cas du site d'Ankafobe – Tampoketsa d'Ankazobe -. Hautes terres centrales de Madagascar.

Safety and immunogenicity of rVSVΔG-ZEBOV-GP Ebola vaccine in adults and children in Lambaréné, Gabon: A phase I randomised trial.

Science.gov (United States)

Agnandji, Selidji T; Fernandes, José F; Bache, Emmanuel B; Obiang Mba, Régis M; Brosnahan, Jessica S; Kabwende, Lumeka; Pitzinger, Paul; Staarink, Pieter; Massinga-Loembe, Marguerite; Krähling, Verena; Biedenkopf, Nadine; Fehling, Sarah Katharina; Strecker, Thomas; Clark, David J; Staines, Henry M; Hooper, Jay W; Silvera, Peter; Moorthy, Vasee; Kieny, Marie-Paule; Adegnika, Akim A; Grobusch, Martin P; Becker, Stephan; Ramharter, Michael; Mordmüller, Benjamin; Lell, Bertrand; Krishna, Sanjeev; Kremsner, Peter G

2017-10-01

The rVSVΔG-ZEBOV-GP vaccine prevented Ebola virus disease when used at 2 × 107 plaque-forming units (PFU) in a trial in Guinea. This study provides further safety and immunogenicity data. A randomised, open-label phase I trial in Lambaréné, Gabon, studied 5 single intramuscular vaccine doses of 3 × 103, 3 × 104, 3 × 105, 3 × 106, or 2 × 107 PFU in 115 adults and a dose of 2 × 107 PFU in 20 adolescents and 20 children. The primary objective was safety and tolerability 28 days post-injection. Immunogenicity, viraemia, and shedding post-vaccination were evaluated as secondary objectives. In adults, mild-to-moderate adverse events were frequent, but there were no serious or severe adverse events related to vaccination. Before vaccination, Zaire Ebola virus (ZEBOV)-glycoprotein (GP)-specific and ZEBOV antibodies were detected in 11% and 27% of adults, respectively. In adults, 74%-100% of individuals who received a dose 3 × 104, 3 × 105, 3 × 106, or 2 × 107 PFU had a ≥4.0-fold increase in geometric mean titres (GMTs) of ZEBOV-GP-specific antibodies at day 28, reaching GMTs of 489 (95% CI: 264-908), 556 (95% CI: 280-1,101), 1,245 (95% CI: 899-1,724), and 1,503 (95% CI: 931-2,426), respectively. Twenty-two percent of adults had a ≥4-fold increase of ZEBOV antibodies, with GMTs at day 28 of 1,015 (647-1,591), 1,887 (1,154-3,085), 1,445 (1,013-2,062), and 3,958 (2,249-6,967) for the same doses, respectively. These antibodies persisted up to day 180 for doses ≥3 × 105 PFU. Adults with antibodies before vaccination had higher GMTs throughout. Neutralising antibodies were detected in more than 50% of participants at doses ≥3 × 105 PFU. As in adults, no serious or severe adverse events related to vaccine occurred in adolescents or children. At day 2, vaccine RNA titres were higher for adolescents and children than adults. At day 7, 78% of adolescents and 35% of children had recombinant vesicular stomatitis virus RNA detectable in saliva. The vaccine

Safety and immunogenicity of rVSVΔG-ZEBOV-GP Ebola vaccine in adults and children in Lambaréné, Gabon: A phase I randomised trial.

Directory of Open Access Journals (Sweden)

Selidji T Agnandji

2017-10-01

Full Text Available The rVSVΔG-ZEBOV-GP vaccine prevented Ebola virus disease when used at 2 × 107 plaque-forming units (PFU in a trial in Guinea. This study provides further safety and immunogenicity data.A randomised, open-label phase I trial in Lambaréné, Gabon, studied 5 single intramuscular vaccine doses of 3 × 103, 3 × 104, 3 × 105, 3 × 106, or 2 × 107 PFU in 115 adults and a dose of 2 × 107 PFU in 20 adolescents and 20 children. The primary objective was safety and tolerability 28 days post-injection. Immunogenicity, viraemia, and shedding post-vaccination were evaluated as secondary objectives. In adults, mild-to-moderate adverse events were frequent, but there were no serious or severe adverse events related to vaccination. Before vaccination, Zaire Ebola virus (ZEBOV-glycoprotein (GP-specific and ZEBOV antibodies were detected in 11% and 27% of adults, respectively. In adults, 74%-100% of individuals who received a dose 3 × 104, 3 × 105, 3 × 106, or 2 × 107 PFU had a ≥4.0-fold increase in geometric mean titres (GMTs of ZEBOV-GP-specific antibodies at day 28, reaching GMTs of 489 (95% CI: 264-908, 556 (95% CI: 280-1,101, 1,245 (95% CI: 899-1,724, and 1,503 (95% CI: 931-2,426, respectively. Twenty-two percent of adults had a ≥4-fold increase of ZEBOV antibodies, with GMTs at day 28 of 1,015 (647-1,591, 1,887 (1,154-3,085, 1,445 (1,013-2,062, and 3,958 (2,249-6,967 for the same doses, respectively. These antibodies persisted up to day 180 for doses ≥3 × 105 PFU. Adults with antibodies before vaccination had higher GMTs throughout. Neutralising antibodies were detected in more than 50% of participants at doses ≥3 × 105 PFU. As in adults, no serious or severe adverse events related to vaccine occurred in adolescents or children. At day 2, vaccine RNA titres were higher for adolescents and children than adults. At day 7, 78% of adolescents and 35% of children had recombinant vesicular stomatitis virus RNA detectable in saliva. The

Accurate isotope ratio mass spectrometry. Some problems and possibilities

International Nuclear Information System (INIS)

Bievre, P. de

1978-01-01

The review includes reference to 190 papers, mainly published during the last 10 years. It covers the following: important factors in accurate isotope ratio measurements (precision and accuracy of isotope ratio measurements -exemplified by determinations of 235 U/ 238 U and of other elements including 239 Pu/ 240 Pu; isotope fractionation -exemplified by curves for Rb, U); applications (atomic weights); the Oklo natural nuclear reactor (discovered by UF 6 mass spectrometry at Pierrelatte); nuclear and other constants; isotope ratio measurements in nuclear geology and isotope cosmology - accurate age determination; isotope ratio measurements on very small samples - archaeometry; isotope dilution; miscellaneous applications; and future prospects. (U.K.)

Browse Title Index

African Journals Online (AJOL)

Items 251 - 300 of 1463 ... Vol 16, No 2 (2016), Cerebro-meningeal infections in HIV-infected patients: a study of 116 cases in Libreville, Gabon, Abstract PDF. Magloire Ondounda, Chinenye Ilozue, Caroline Magne. Vol 12, No 3 (2012), Cervical spondylitic myeloradiculopathy due to chronic brucellosis in a Ugandan teenager ...

Sweet Little Gabonese Palm Wine: A Neglected Alcohol | Mavioga ...

African Journals Online (AJOL)

BACKGROUND: During the last ten years, consumption of palm wine, a popular traditional alcoholic beverage, seriously increases in Gabon. This sweet beverage seems to be the main alcohol and the most drunken in low socioeconomic population. OBJECTIVE: To have an idea of it composition and toxicity, 21 samples of ...

Research Article Special Issue

African Journals Online (AJOL)

pc

2017-11-24

Nov 24, 2017 ... Gabon to 30.6 cases per 100,000 population in Peru for women. In general, the highest .... history of gastroduodenal surgery entered the study, and those who could not tolerate endoscopy or ... In patients with drinking history, the percentage of patients with precancerous lesions (0%) was lower than.

The African rain forest during the Last Glacial Maximum an archipelago of forests in a sea of grass

NARCIS (Netherlands)

Leal, M.E.

2004-01-01

In centralGabonElimination of Cu (II) and Zn (II) ions in mono-element and the bi ...

African Journals Online (AJOL)

Elimination of Cu (II) and Zn (II) ions in mono-element and the bi-element aqueous solutions by adsorption on natural clay of Bikougou (Gabon) ... The modeling of the experimental results is better achieved by application of. Freundlich adsorption isotherm and Langmuir adsorption isotherm concerning the adsorption of Cu ...

Vegetarian diet in Guenon and Mangabey monkeys of Moukalaba ...

African Journals Online (AJOL)

To order to know any differences and similarities between Mangabeys and Guenons study of their vegetarian diet was conducted for 10 months between 2013 and 2014 in Moukalaba-Doudou National Park, Gabon. By using the direct observation method, we identified 84 plant species integral to the vegetarian diet of these ...

Research Article Special Issue

African Journals Online (AJOL)

pc

2017-11-24

Nov 24, 2017 ... Journal of Fundamental and Applied Sciences is licensed under a Creative Commons ... The frequencies of patients with lower than normal pepsinogen ... Gabon to 30.6 cases per 100,000 population in Peru for women. In general .... not performed because the number of smokers in this research was low.

The Audio-Visual Services in Fifteen African Countries. Comparative Study on the Administration of Audio-Visual Services in Advanced and Developing Countries. Part Four. First Edition.

Science.gov (United States)

Jongbloed, Harry J. L.

As the fourth part of a comparative study on the administration of audiovisual services in advanced and developing countries, this UNESCO-funded study reports on the African countries of Cameroun, Republic of Central Africa, Dahomey, Gabon, Ghana, Kenya, Libya, Mali, Nigeria, Rwanda, Senegal, Swaziland, Tunisia, Upper Volta and Zambia. Information…

ABO, rhesus blood groups and transfusion-transmitted infections ...

African Journals Online (AJOL)

Background: Few studies focused on the study of blood groups in Gabon. This study aimed to determine the phenotypic frequency of ABO and Rhesus antigens in blood donors of Libreville and to assess the association between ABO blood groups and transfusion-transmitted infections. Materials and Methods: The study of ...

Evolution des composés polyphénoliques du bois de chêne au cours de son séchage. Premiers résultats

Directory of Open Access Journals (Sweden)

Pascal Chatonnet

1994-12-01

Full Text Available Pendant le séchage naturel à l'air libre du bois de chêne, on assiste à une diminution régulière de la teneur du bois en composés extractibles et notamment en composés phénoliques du type ellagitanins. La diminution de la teneur en ellagitanins provient essentiellement de la disparition des formes oligomères solubles dans l'eau; les tanins polymérisés non extractibles car liés aux parois, évoluent peu au çours du séchage naturel à l'air libre. Les bois séchés rapidement à l'étuve possèdent toujours des quantités plus importantes de polyphénols. Dans le même temps et quel que soit le mode de séchage, on obselVe une diminution des coumarines glucosilées et une augmentation non proportionnelle des formes aglycones. D'un point de vue organoleptique, la diminution de l'ensemble des polyphénols pendant le séchage peut être interprétée comme favorable à l'évolution de la qualité du merrain. En effet, les fractions amères et astringentes du bois de chêne correspondent respectivement .sr certains tanins ellagiques et catéchiques. L'intelVention des micro-organismes isolés de bois de chêne en cours de séchage naturel dans la disparition des composés phénoliques du bois est discutée. La grande majorité des moisissures étudiées est capable de dégrader enzymatiquement les tanins hydrolysables du chêne. Cependant, ces mêmes composés s'hydrolysent et s'oxydent spontanément en présence d'eau et d'oxygène. En conséquence, considérant le profil de colonisation du bois par les micro-organismes et celui des composés phénoliques extractibles, on peut supposer que l'on assiste vraisemblablement pendant le séchage naturel du bois à une dégradation biochimique et chimique des polyphénols dans les couches superficielles du merrain (0 à 4 mm de profondeur et à une dégradation presque' exclusivement chimique au coeur du merrain. La présence d'eau et d'oxygène apparaÎt par conséquent comme un facteur

WHO 2006 child growth standards: implications for the prevalence of stunting and underweight-for-age in a birth cohort of Gabonese children in comparison to the Centers for Disease Control and Prevention 2000 growth charts and the National Center for Health Statistics 1978 growth references

NARCIS (Netherlands)

Schwarz, Norbert G.; Grobusch, Martin P.; Decker, Marie-Luise; Goesch, Julia; Poetschke, Marc; Oyakhirome, Sunny; Kombila, Davy; Fortin, Julien; Lell, Bertrand; Issifou, Saadou; Kremsner, Peter G.; Klipstein-Grobusch, Kerstin

2008-01-01

OBJECTIVES: To assess the proportion of children being stunted and underweight-for-age at 3, 9 and 15 months in Lambaréné, Gabon, using the WHO child growth standards released in 2006 as compared with the Centers for Disease Control and Prevention (CDC) 2000 and the National Center for Health

East African Medical Journal - Vol 78, No 9 (2001)

African Journals Online (AJOL)

Incidence and characteristics of Myasthenia gravis in Dar es Salaam, Tanzania · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. W. B. P. Matuja, E. A. Aris, J. Gabone, E. M. Mgaya, 473-477. http://dx.doi.org/10.4314/eamj.v78i9.8978 ...

New development is targeted at the future nuclear generating market

Energy Technology Data Exchange (ETDEWEB)

1974-01-01

The results are given of a survey of the reserves, exploitation and processing of uranium ore in the USA, Australia, Canada, France (including Gabon and Niger), and South Africa indicating estimated development up to 1990 and the estimated impact of the development of mining on the world natural uranium and enriched fuel market.

Sepsis in HIV-infected patients; epidemiology and host response

NARCIS (Netherlands)

Huson, M.A.M.

2016-01-01

In this thesis, we examined the impact of HIV infection on the epidemiology (Part I) of sepsis, and host response (Part II) to sepsis. We studied sepsis patients in Gabon, a setting with a high prevalence of HIV, and in Dutch intensive care units (ICUs). In Part I, we found that HIV positive

La préservation de la forêt, source de prospérité pour les ...

International Development Research Centre (IDRC) Digital Library (Canada)

17 nov. 2010 ... Lorsque nous avons commencé à examiner la connaissance qu'ils possèdent de leur milieu naturel, nous nous sommes rendu compte qu'en incitant les Nagas à renouer avec ce savoir, nous les aiderions à prendre conscience de la valeur de la biodiversité. Si vous limitez votre rôle à celui de facilitateur ...

La cacaoculture hybride à l'ère du retour des employés deflatés au ...

African Journals Online (AJOL)

Car, obligés de développer de petites activités agricoles pour survivre dans leur nouvel univers social qu'est la campagne, ils se concentrent naturellement sur la cacaoculture en souvenir de l'unique et ancienne source de revenus du monde rural. Mais, parallèlement, d'autres nouvelles cultures se développent et tentent ...

2241-IJBCS-Article-Rabiou Habou Garba

African Journals Online (AJOL)

hp

Pterocarpus erinaceus de la famille des Fabaceae, est un arbre éminemment utile pour les populations. C'est une espèce endémique multi-usage des zones guinéo-soudaniennes et soudano-sahéliennes. La présente étude analyse les paramètres structuraux du peuplement naturel de P. erinaceus, détermine la.

2638-IJBCS-Article-Zongo Paul

African Journals Online (AJOL)

hp

semences avec pour conséquences les risques d'introduction de maladies, de variabilité interannuelle de la production et la présence d'espèces parasites ou ..... en milieu naturel, également inférieures à. 140440 ± 82168 ovocytes et 47.30 ± 17.94 ovocytes / g ♀ chez Heterobranchus bidorsalis (Alla et al., 2010) et à ...

The natural gas vehicles; Le gaz naturel vehicules

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-07-01

The NGV (Natural Gas Vehicles) is a new ''clean'' fuel used for the urban public transports which can be adapted to the vehicles. It is the same gas as those for the cooking and the heating, but compressed at 200 bars. this document presents this abundant energy sources, the bound emissions standards, the technical and economical aspects, the environmental advantages, the today implementation and compare the french policy towards the NGV to other countries. (A.L.B.)

Le pompage optique naturel dans le milieu astrophysique

Science.gov (United States)

Pecker, J.-C.

The title of this lecture abstracts only a part of it : the importance in astrophysics of the study of non-LTE situations has become considerable, as well in the stellar atmospheres as, still more, in the study of fortuitous coincidences as a mechanism of formation of emission line nebular spectra, or of molecular interstellar « masers ». Another part of this talk underlines the role of Kastler in his time, and describes his warm personality through his public reactions in front of the nuclear armement, of the Viet-Nam and Algerian wars, of the problems of political refugees... Kastler was a great scientist ; he was also a courageous humanist. 1976 : Les accords nucléaires du Brésil : allocution d'ouverture (19 mars). Colloque sur le sujet ci-dessus. 1976 : La promotion de la culture dans le nouvel ordre économique international, allocution à l'occasion d'une table ronde sur ce thème par l'UNESCO (23-27 juin 1976) ; « Sciences et Techniques », octobre 1976. 1979 : La bête immonde (avec J.-C. Pecker), « Le Matin », 20 mars. 1979 : Appel à nos ministres (avec J.-C. Pecker), « Le Monde », 13 décembre. 1979 : Le flou, le ténébreux, l'irrationnel (avec J.-C. Pecker), « Le Monde », 14 septembre. 1980 : Education à la paix, Préface, in : Publ. UNESCO. 1981 : Le vrai danger, « Le Monde », 6 août 1981. 1982 : Nucléaire civil et militaire, « Le Monde », 1er juin 1982. 1982 : Les scientifiques face à la perspective d'holocauste nucléaire (texte inédit). Le titre de cette communication en résume seulement une partie : l'importance prise en astrophysique par l'analyse des situations hors ETL est devenue considérable, qu'il s'agisse des atmosphères stellaires, ou plus encore, des coïncidences fortuites de la formation des spectres d'émission nébulaires, ou des « masers » moléculaires interstellaires. Une autre partie de cet exposé souligne le rôle de Kastler dans son époque, et décrit sa personnalité généreuse à travers ses réactions publiques face à l'armement nucléaire, aux guerres de Viet-Nam et d'Algérie, aux problèmes des réfugiés politiques... Kastler était un grand savant, mais aussi un homme courageux.

Rickettsia Species in African Anopheles Mosquitoes

Science.gov (United States)

Socolovschi, Cristina; Pages, Frédéric; Ndiath, Mamadou O.; Ratmanov, Pavel; Raoult, Didier

2012-01-01

Background There is higher rate of R. felis infection among febrile patients than in healthy people in Sub-Saharan Africa, predominantly in the rainy season. Mosquitoes possess a high vectorial capacity and, because of their abundance and aggressiveness, likely play a role in rickettsial epidemiology. Methodology/Principal Findings Quantitative and traditional PCR assays specific for Rickettsia genes detected rickettsial DNA in 13 of 848 (1.5%) Anopheles mosquitoes collected from Côte d’Ivoire, Gabon, and Senegal. R. felis was detected in one An. gambiae molecular form S mosquito collected from Kahin, Côte d’Ivoire (1/77, 1.3%). Additionally, a new Rickettsia genotype was detected in five An. gambiae molecular form S mosquitoes collected from Côte d’Ivoire (5/77, 6.5%) and one mosquito from Libreville, Gabon (1/88, 1.1%), as well as six An. melas (6/67, 9%) mosquitoes collected from Port Gentil, Gabon. A sequence analysis of the gltA, ompB, ompA and sca4 genes indicated that this new Rickettsia sp. is closely related to R. felis. No rickettsial DNA was detected from An. funestus, An. arabiensis, or An. gambiae molecular form M mosquitoes. Additionally, a BLAST analysis of the gltA sequence from the new Rickettsia sp. resulted in a 99.71% sequence similarity to a species (JQ674485) previously detected in a blood sample of a Senegalese patient with a fever from the Bandafassi village, Kedougou region. Conclusion R. felis was detected for the first time in An. gambiae molecular form S, which represents the major African malaria vector. The discovery of R. felis, as well as a new Rickettsia species, in mosquitoes raises new issues with respect to African rickettsial epidemiology that need to be investigated, such as bacterial isolation, the degree of the vectorial capacity of mosquitoes, the animal reservoirs, and human pathogenicity. PMID:23118963

Author Details

African Journals Online (AJOL)

Ondounda, Magloire. Vol 16, No 2 (2016) - Articles Cerebro-meningeal infections in HIV-infected patients: a study of 116 cases in Libreville, Gabon Abstract PDF. ISSN: 1680-6905. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners ...

First record of a white rough-toothed dolphin (Steno bredanensis) off West Africa including notes on rough-toothed dolphin surface behaviour

NARCIS (Netherlands)

Boer, de M.N.

2010-01-01

In June 2009, a white rough-toothed dolphin (Steno bredanensis) calf was photographed in a group of at least 50 dolphins in the southern Gulf of Guinea, 95 nauticol miles off the Gabon coast (01°45'S 007°29'E), West Africa. Reports of unusually pigmented cetaceans are infrequent and this record

Microfinance and reducing poverty in Central Africa | CRDI - Centre ...

International Development Research Centre (IDRC) Digital Library (Canada)

In spite of an abundance of natural resources, including oil and minerals, poverty is increasing in Central Africa. About 40% of the people in Cameroon live below the poverty threshold, 55% in Chad, 50% in Congo and 43% in Gabon. A considerable amount of research has attempted to generate insight into the factors that ...

Anatomical variability of the trunk wood and root tissues of ...

African Journals Online (AJOL)

The aim of this study was to investigate the anatomical structure of the trunk wood and the roots of A. nitida and R. racemosa, two mangrove trees from Gabon. The anatomical differences between the trunks and the roots were used to understand their bio-remediating differences through heavy metals. It was found that the ...

Anomalous deuteron to hydrogen ratio in naturally occuring fission reactions and the possibility of deuteron disintegration

International Nuclear Information System (INIS)

Shaheen, M.; Ragheb, M.

1992-01-01

A hypothesis is presented for explaining the experimentally determined anomalous D/H ratio observed in the samples from the naturally occuring fission reaction in the Oklo phenomenon. No other explanation has been given, to the best knowledge, for the large difference between the measured D/H ratio in the Oklo samples and the expected values in a fission neutron spectrum. A multicomponent system consisting of hydrogen, deuterium, tritium and helium nuclei is considered. An analytical solution is derived and solved using as boundary conditions the experimentally determined value of the D/H ratio. The solution of the rate equations for hydrogen and deuteron concentrations, assuming a pure fission process without a deuteron sink term, yields a D/H ratio of 445 ppm for a reaction in which the fluence of neutrons is 10 21 n/cm 2 . This exceeds the experimentally observed value of 127 ppm, and the naturally occuring value of 150 ppm. Solving the same rate equations accounting for a deuterium sink term using a hypothesis of deuteron disintegration, and the experimentally observed value of 127 ppm yields a deuteron disintegration constant of 7.47*10 -14 s -1 . Deuteron disintegration would provide a neutron source, in addition to the fission neutrons, driving a subcritical chain reaction over an extended period of time. Relationship of the presented hypothesis to the Vlasov theory of an annihilation meteorite impact explosion explaining the experimentally observed anomalous 235 U/ 238 U ratio, and to the suggestion of deuteron disintegration as a possible explanation of some observations of deuterium dissociation in palladium and titanium electrodes is discussed. The tritium andhelium-3 rate equations are further solved under the deuteron disintegration hypothesis and the relationship of the present work to the work by JONES et al. is discussed. (author) 16 refs.; 7 figs.; 2 tabs

Schistosoma mansoni in Gabon: Emerging or Ignored?

Czech Academy of Sciences Publication Activity Database

Červená, B.; Brant, S. V.; Fairet, E.; Shirley, M.H.; Petrželková, Klára Judita; Modrý, David

2016-01-01

Roč. 95, č. 4 (2016), s. 849-851 ISSN 0002-9637 Institutional support: RVO:60077344 Keywords : schistosomiasis * humans * Africa Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 2.549, year: 2016

Schistosoma mansoni in Gabon: Emerging or ignored?

Czech Academy of Sciences Publication Activity Database

Červená, B.; Brant, S. V.; Fairet, E.; Shirley, M.H.; Petrželková, Klára Judita; Modrý, D.

2016-01-01

Roč. 95, č. 4 (2016), s. 849-851 ISSN 0002-9637 Institutional support: RVO:68081766 Keywords : schistosomiasis * humans * Africa Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 2.549, year: 2016

Mineralogical and petrographic investigations at Strasbourg on the Oklo natural reactors

International Nuclear Information System (INIS)

Gauthier-Lafaye, F.; Weber, F.

1978-01-01

Petrographic and mineralogical investigations have revealed the presence around the reaction zones of aureoles characterized by the nature of the phyllitic minerals which they enclose. Running from the outside towards the core, these are: illite 1Md and ferriferous chlorite (normal sediment), illite 2M 1 , magnesium chlorite and kaolinite, illite 1M and vermiculite chlorite. Detritic quartz dissolution figures are observed which disappear in the illite 2M aureole or in the magnesium chlorite aureole, depending on the degree of sandiness of the country rock. This zonal stucture could be attributable to the combined effect of neutron bombardment and hydrothermal alteration due to the action of a thermal syphon triggered off by the nuclear reactions. (author)

Structures et dynamiques de l'espace gabonais

Directory of Open Access Journals (Sweden)

Stéphane LEROY

1995-06-01

Full Text Available L’organisation spatiale du Gabon peut être envisagée comme le résultat de l’arrangement particulier de structures spatiales générales, communes à la grande majorité des pays côtiers de l’Afrique occidentale et équatoriale. La modélisation graphique permet de le vérifier.

Dynamique de croissance et taux de mortalité de Rhizophora spp ...

African Journals Online (AJOL)

SARAH

30 janv. 2015 ... Dynamique des paysages végétaux du littoral centre-ouest du Gabon autour de. Port-Gentil : Approche spatiale et analyse des données de terrain. Thèse de doctorat. Univ. Paul-Valery Montpellier 3, France. 302 p. Spalding MD, Blasco F, Field CD, 1997. World. Mangrove Atlas. ISME, Okinawa, Japan. 251.

De la problématique des articles synopsis dans la compilation des ...

African Journals Online (AJOL)

Autrement dit, au Gabon l'attention doit porter sur l'utilisation des articles synopsis dans la compilation des dictionnaires, en vue de refléter dans ses ouvrages la diversité linguistique et culturelle de ce pays. Ceci est d'autant plus vrai que l'utilisation des articles synopsis ne dépend aucunement de la typologie du ...

What French for Gabonese French lexicography? | Assam | Lexikos

African Journals Online (AJOL)

This paper is a response to Mavoungou (2013a) who has pleaded for the production of a dictionary of Gabonese French as variant B of the French language. The paper intends to com-prehend the concept of "Gabonese French". It gives an outline of the situation of French within the language diversity of Gabon as a ...

Evaluation des caractéristiques ethnobotaniques et structurales de ...

African Journals Online (AJOL)

La dégradation des habitats naturels des espèces forestière évolue de façon croissance avec l'augmentation de la taille de la population du Bénin. L'objectif de cette étude est de contribuer à la conservation de Nesogordonia kabingaensis qui est l'une des espèces à habitat unique dans le pays. Des enquêtes ...

Théorie de jauge et groupoïdes

OpenAIRE

Hausmann, Jean-Claude

2002-01-01

Les résultats de cet article concernent le problème de l'existence de représentations d'un groupoïde topologique sur un fibre principal et leur classification à transformation de jauge près. De telles représentations interviennent naturellement dans divers contextes (théories de jauge classiques ou sur graphe, fibrés équivariants, etc).

INSP : initiatives et partenariats | CRDI - Centre de recherches pour ...

International Development Research Centre (IDRC) Digital Library (Canada)

10 mai 2011 ... L'Institut Nacional de Salud Pública (INSP) du Mexique a accueilli le Forum international écosanté 2008 (FIE 2008) à Mérida. C'était un rôle tout à fait naturel à bien des égards pour l'INSP.La démarche écosanté est le modus operandi que l'institut aimerait adopter, selon Mario-Henry Rodriguez, directeur ...

Le traitement macrostructural de l'emprunt au français dans les ...

African Journals Online (AJOL)

«ciment, brique, … surfer (Internet), s'abonner, affecter. (être), nommer (être), etc. Nous allons nous intéresser précisément aux mots locaux qui ont été créés pour remplacer les mots empruntés. Les emprunts sont souvent spontanément et naturellement remplacés à long terme par les termes locaux lorsque les choses et ...

756-IJBCS-Article-Richard Priso

African Journals Online (AJOL)

DR GATSING

s'établir dans les marécages et même à y cultiver nonobstant les risques. Par ailleurs, les marécages naturels jouent un rôle important dans le traitement des déchets liquides. Ils interceptent l'eau et éliminent les polluants par biodégradation, absorption et échanges ioniques entre les sédiments (Odum, 1996) et jouent un ...

Les enjeux écologiques de Palo Verde (Costa Rica

Directory of Open Access Journals (Sweden)

Bertrand LÉVY

1992-09-01

Full Text Available Près de Palo Verde a été créé un parc naturel. Un projet d’irrigation risque de perturber l’écologie de la région. Une carte de son écosystème a été établie par télédétection, pour évaluer l’impact d’un tel projet.

Défense d'y voir : la politisation de la protection de la nature

NARCIS (Netherlands)

Ellis, S.

1992-01-01

Certains éléments des forces de sécurité sud-africaines ont mis en exploitation les ressources naturelles au profit de leurs stratégies de déstabilisation politique et d'enrichissement. Ils ont ainsi réussi à établir des réseaux très développés de contrebande de produits naturels de valeur (ivoire,

Intercomparison of performance characteristics of OSLDs and TLDs used for individual monitoring

International Nuclear Information System (INIS)

Meye, Phillipe Ondo

2016-07-01

This research work performed an intercomparison on some important performance characteristics of optically stimulated luminescence (OSL) and thermoluminescence (TL) dosimetry systems used by dosimetry services in Gabon and Ghana, respectively. The study verified the status of the selected performance indicators and propose ways to improve the performances of individual monitoring services of Ghana and Gabon if found necessary. The performance indicators assessed included the zero - dose, the minimum detectability and some important reader performance characteristics. These tests were performed using statistical and experimental methods. The overall uncertainty in measurement of the dosimetry systems of Ghana and Gabon for Hp(10) was determined using the IEC technical report TR 62461, and comparisons were carried out with IAEA 99, PTB 99, IEC 1066 and IEC1283 series performance standards. The IEC 62387 standard was used to assess the linearity dependence of the response and the coefficient of variation of the two dosimetry systems. For the Harshaw TLD 6600 system of the dosimetry service of Ghana, the Reference light QC test meets the requirement given in the user manual. For the OSL system microStar of the dosimetry system of Gabon, the three QC tests, DRK count, CAL count and LED count, meet the user manual requirements. However all these tests failed the statistical test that is part of counting statistics. This led to the conclusion that there may be some abnormalities in the counting system, and that the statistical abnormalities suspected have apparently no impact on the results of the reading. It was also concluded that since the DRK count and the CAL count failed the Chi - squared test by very small margin, a Gaussian distribution could still be considered as an approximation of the experimental data distributions of these two QC measurements. The zero dose for the Harshaw 6600 and the microStar system were found to be 0.026 mSv and 0.08 mSv respectively

WAJM 28 (5).pmd

African Journals Online (AJOL)

user

palm wine, a popular traditional alcoholic beverage, seriously increases in Gabon. This sweet beverage seems to be ... limits for alcoholic beverages with less than 2 µg.L-1 for cadmium, less than 10 µg.L-1 for arsenic and for .... then put in a larger plastic tube for safety transport at room temperature. It took about ten days to ...

Report of Secretary of Defense, Harold Brown, to the Congress on the FY 1982 Budget, FY 1983 Authorization Request and FY 1982-1986 Defense Programs

Science.gov (United States)

1981-01-19

installation compliance with environmental and OSHA standards, and NATO infrastructure facilities funds. 1. Military Construction Program a. European...investment effort (research and development, procurement, and military construction ) and the pattern of increases. The former trend is important because it...SPAIN MANGANESE U GABON, BRAZI SOUR AFICA TANTAIAU 97 THAILAND, CANADA. MALAYSIA . BRAI COBALT 97 ZAIJRE, B LG.-UX.. ZAMBIA. FINIANO SAM~T & ALUIMINA

diversité botanique dans le sud du parc national de taï, côte d

African Journals Online (AJOL)

AKA Boko Mathieu

Résumé. L'analyse globale de la croissance de trois espèces d'algues rouges ; Hypnea musciformis, Gracilaria multipartita et Gelidium sesquipedale a été entreprise dans le but de déterminer la variabilité interspécifique au sein du même milieu naturel. Le site étudié est la plage de Mehdia située au nord de la côte ...

109 Composition chimique et propriétés antibactériennes des huiles ...

African Journals Online (AJOL)

NGOM

2Laboratoire des Produits Naturels (LPN), Département de chimie, Faculté des sciences et techniques, .... analytique, la technique a été améliorée par la mise en ligne deux colonnes capillaires de polarité différente ... couplage CPG/SM a été réalisé sur colonne capillaire en silice fondue (25 m x 0,23 x 0,25 µm) avec de.

Substances inertes et plantes à effet insecticide utilisées dans la ...

African Journals Online (AJOL)

Les insecticides naturels tels que les plantes à effet insecticide et les substances inertes (sable, cendre, terres à diatomées,…) méritent d'être valorisées afin de réduire l'utilisation des insecticides chimiques et protéger l'environnement. Ce travail basé sur une revue documentaire fouillée et actualisée vise à faire la genèse ...

Les gens, et non les choses, calment les eaux de la lagune de Tam ...

International Development Research Centre (IDRC) Digital Library (Canada)

Cathy Egan

La lagune de Tam Giang au Viet Nam est un habitat naturel presque parfait pour la pêche et l'aquaculture. Longue de plus de 70 km et d'une profondeur moyenne d'à peine deux mètres, la lagune est un milieu des plus productifs, tant pour les espèces d'eau douce que pour les espèces marines. Au cours des dernières ...

Étude des impacts écologiques du dynamisme spatio-temporel des ...

African Journals Online (AJOL)

Cette recherche menée dans le Complexe Zones Humides Mahavavy - Kinkony a pour but d'évaluer les impacts écologiques du changement des habitats naturels sur les espèces menacées de sa faune. Des outils tels que le SIG, la télédétection ainsi que Marxan ont été combinés avec les études bibliographiques et les ...

ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

African Journals Online (AJOL)

SEI Joseph

Sa valorisation passe par l'étude de sa biologie en milieu naturel, puis en conditions contrôlées. Les variations saisonnières de la croissance et de la capacité reproductive de l'algue rouge Hypnea musciformis ont été suivies durant deux années dans deux localités différentes au niveau de la côte atlantique marocaine.

Measurements for uranium-light water subcritical assembly; Mesures pour ensemble sous-critique uranium-eau legere d'enseignement

Energy Technology Data Exchange (ETDEWEB)

Barre, J Y [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1964-07-01

The aim of this report is to determine the matter Laplacian of a subcritical assembly, done for educational purposes, using natural uranium combustible and light water for the moderator and the reflector. (M.B.) [French] L'objet de ce rapport est la determination du Laplacien matiere d'un reseau sous-critique, destine a l'enseignement, utilisant comme combustible l'uranium naturel et comme moderateur et reflecteur l'eau naturelle. (M.B.)

Les éléments traces métalliques dans la lagune Ebrié : distribution ...

African Journals Online (AJOL)

Il ressort de cette évaluation que les sédiments de ces baies présentent un risque de toxicité important pour les organismes vivants dans ce système aquatique. Ce risque augmente lors de la remise en suspension des sédiments par les phénomènes naturels et/ou par les activités anthropiques avec les opérations de ...

Étude de la compétitivité de complexation des métaux issus des ...

African Journals Online (AJOL)

Les analyses chimiques effectuées sur le phosphate naturel révèlent la présence des métaux lourds. Pour étudier les risques de rétrogradation de ces engrais phosphatés, notre étude s'est portée sur la complexation des substances humiques naturelles extraites des sols sur des ions métalliques tels que le calcium, ...

Relance de l'aquaculture au Sri Lanka

International Development Research Centre (IDRC) Digital Library (Canada)

cas de risque et de mettre au point des systèmes de dépuration (c'est-à-dire de purification au moyen d'eau de mer stérilisée). Un élément primordial du projet de recherche consiste à protéger la population contre les contaminants (aussi bien naturels que d'origine anthropique). Pour que les collectivités puissent exploiter ...

Cette étrange matière

CERN Document Server

Kastler, Alfred

1976-01-01

La matière nous est connue et jusque dans sa structure intime : l'aspect qu'offre le monde industrialisé en est une preuve suffisante, la bombe atomique ou à hydrogène, un signe spectaculaire. Pourtant, selon Alfred Kastler, dont le témoignage en pareil domaine fait naturellement autorité, la matière mérite plus encore d'être appelée "étrange".

Nuclides and isotopes. Twelfth edition

International Nuclear Information System (INIS)

Anon.

1977-01-01

This explanatory booklet was designed to be used with the Chart of the Nuclides. It contains a brief history of the atomic theory of matter: ancient speculations, periodic properties of elements (Mendeleev table), radioactivity, early models of atomic structure, the Bohr atom, quantum numbers, nature of isotopes, artificial radioactivity, and neutron fission. Information on the pre-Fermi (natural) nuclear reactor at Oklo and the search for superheavy elements is given. The booklet also discusses information presented on the Chart and its coding: stable nuclides, metastable states, data display and color, isotopic abundances, neutron cross sections, spins and parities, fission yields, half-life variability, radioisotope power and production data, radioactive decay chains, and elements without names. The Periodic Table of the Elements is appended. 3 figures, 3 tables

Parametric study of the criticality of natural reactors

International Nuclear Information System (INIS)

Naudet, R.

1978-01-01

Conditions for the criticality of natural reactors are investigated from a general point of view; a parametric study is presented, which expresses the possibility of chain reactions as functions of five parameters: the age of the deposit, the ore's uranium content, the volume of high-grade ore, the neutron capture of the vein of ore and the amount of water associated with the uranium. It is demonstrated that although criticality could theoretically be attained for ages that are not in excess of 1000 to 1200 MA, conditions would have to be exceptionally favorable for it since the deposits are clearly much younger than those at Oklo. The study offers a much better appreciation of the probability for discovery of other natural fissionable reactors

China’s Incomplete Military Transformation: Assessing the Weaknesses of the People’s Liberation Army (PLA)

Science.gov (United States)

2015-02-01

priorities. Additionally, if domestic prob- lems, such as pollution and its associated health costs, continue to 13 For a brief overview, see...The Philippines has met with some success in resupplying its marines stationed in the shoal aboard an intentionally beached amphibious landing ship...militaries of Peru and Gabon in multilateral medical exercises. The PLA has been directly involved in international disaster relief over a dozen times

Natural and archaeological analogues: a review

International Nuclear Information System (INIS)

Brookins, D.G.

1987-01-01

In this chapter natural analogues in the geomedia for various aspects of radioactive waste disposal are discussed. Particular reference is made to the Okla Natural Reactor in Gabon. Igneous contact zones are discussed and natural analogues of waste-form materials. The importance of archaeological remains and anthropogenic materials left by man, in assessing weathering conditions and serving as radioactive waste analogues, is also emphasised. (UK)

1217-IJBCS-Article-Nicaise Lepengue

African Journals Online (AJOL)

KODJIO NORBERT

Les quantités de roselle (Hibiscus sabdariffa L. var. sabdariffa) produites au Gabon ne sont pas suffisantes pour satisfaire la demande locale. Pour augmenter les productions de cette plante, un essai d'intensification des rendements a été réalisé en utilisant de l'eau oxygénée (H2O2). Les graines de roselle ont pour cela ...

LEPENGUE AN et al...xps

African Journals Online (AJOL)

HP Pro 2000

Heller R., Esnault R. et C. Lance. 2006. Physiologie végétale. Développement. 6e édition de l'abrégé, Editions Dunod, Paris, 366 p. Lépengué A.N., M'batchi B. et S. Aké. 2007. Impact de Phoma sabdariffae Sacc. sur la croissance et la valeur marchande de la roselle (Hibiscus sabdariffa L. var. sabdariffa) au Gabon. Rev.

National Food Strategy: Kenya’s Approach to the Problem of Feeding the Nation

Science.gov (United States)

1990-02-01

UK Malawi Unilever , UK Nigeria *This may only indicate basic processing necessary to preserve the crop. OILS, FATS, MARGARINE, COOKING OILS: East...Asiatic Co., Denmark N/A Lesieur, France Senegal Lonrho, UK Nigeria Unilever , UK/Nld Cameroon, Ghana, Gabon, Kenya, Malawi, Nigeria, Zaire, Zimbabwe FRUIT...Senegal Unilever , UK/Nid Kenya, Zimbabwe SUGAR: Tate & Lyle, UK Nigeria, Zambia, Zimbabwe Lonrho, UK** Malawi, Mauritius, Swaziland Booker McConnell, UK

A hopeful Quebec gets ready to produce gaz naturel

International Nuclear Information System (INIS)

Harrison, L.

2010-01-01

Quebec's natural gas industry is poised to expand as a result of a breakthrough well drilled in the Utica shale gas play in February 2010. The well has produced more than 12 million cubic feet per day. The Quebec Oil and Gas Association (QOGA) was formed in 2009, and has lobbied the provincial government to keep royalty rates at between 10 to 12.5 per cent. A task force has also been deployed to ensure the development of a prompt regulatory process. It is hoped that increased investment will encourage more drilling activity in the province. Quebec consumes approximately 200 billion cubic feet of natural gas per year. Increased sales are expected to come from new residential construction, where 1 in 5 homes are now being equipped with gas-fired heating. The QOGA is currently designing a training program for potential rig workers. Studies have indicated that gas royalties collected by the provincial government could exceed $1 billion per year in the future. 1 fig.

Fabrication of naturel pumice/hydroxyapatite composite for biomedical engineering.

Science.gov (United States)

Komur, Baran; Lohse, Tim; Can, Hatice Merve; Khalilova, Gulnar; Geçimli, Zeynep Nur; Aydoğdu, Mehmet Onur; Kalkandelen, Cevriye; Stan, George E; Sahin, Yesim Muge; Sengil, Ahmed Zeki; Suleymanoglu, Mediha; Kuruca, Serap Erdem; Oktar, Faik Nuzhet; Salman, Serdar; Ekren, Nazmi; Ficai, Anton; Gunduz, Oguzhan

2016-07-07

We evaluated the Bovine hydroxyapatite (BHA) structure. BHA powder was admixed with 5 and 10 wt% natural pumice (NP). Compression strength, Vickers micro hardness, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction studies were performed on the final NP-BHA composite products. The cells proliferation was investigated by MTT assay and SEM. Furthermore, the antimicrobial activity of NP-BHA samples was interrogated. Variances in the sintering temperature (for 5 wt% NP composites) between 1000 and 1300 °C, reveal about 700 % increase in the microhardness (~100 and 775 HV, respectively). Composites prepared at 1300 °C demonstrate the greatest compression strength with comparable result for 5 wt% NP content (87 MPa), which are significantly better than those for 10 wt% and those that do not include any NP (below 60 MPa, respectively). The results suggested the optimal parameters for the preparation of NP-BHA composites with increased mechanical properties and biocompatibility. Changes in micro-hardness and compression strength can be tailored by the tuning the NP concentration and sintering temperature. NP-BHA composites have demonstrated a remarkable potential for biomedical engineering applications such as bone graft and implant.

Réflexions sur une difficulté proposée contre la manière dont les newtoniens expliquent la cohésion

CERN Document Server

Diderot, Denis

2015-01-01

Extrait : ""On a lieu de croire que l'attraction qui fait circuler les planètes, et qui précipite les corps pesants vers le centre de la terre, produit encore plusieurs autres effets naturels, tels que la dureté, l'adhérence des parties fluides, les fermentations et généralement tous les phénomènes qui naissent de la cohésion ou qui s'y rapportent.""

Paramètres influençant la distribution des éléments traces ...

African Journals Online (AJOL)

Auteur correspondant ; E-mail : nguessym@yahoo.fr. RESUME. Les affluents de ... colonne d'eau, diminue lorsque le pH et l'alcalinité augmentent conformément aux processus géochimiques naturels. ..... SO1 SO2 SO3 TO1 TO2 TO3 TO4 SA1 SA2 SA3 Bou Mar Nar Gez Bad Ced Vem Sim Red Tpl Aur Hay. µg.l. -1. 0,0. 0,5.

Controle qualite de l'eau de baignade de la Cascade de Man en ...

African Journals Online (AJOL)

La cascade Ypou du mont Tonkoui appelée couramment « cascade de Man » est un joyau naturel qui attire de nombreux touristes. Elle est très fréquentée pour sa beauté mais aussi pour la baignade. En amont de cette cascade, le paysage se compose de champs de café et selon la période, de maïs et de manioc. Il nous ...

Extériorisation sonore avec des indices auditifs et visuels discordants

DEFF Research Database (Denmark)

Santurette, Sébastien; Carvajal, Juan Camilo Gil; Cubick, Jens

2016-01-01

Dans les environnements d’écoute naturels, les sons sont généralement perçus en dehors de la tête (extériorisés). En revanche, les sons présentés par l’intermédiaire d’un casque sont souvent perçus à l’intérieur de la tête (intériorisés). Les techniques de reproduction d’espaces sonores virtuels...

Asie du sud | Page 197 | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

Il situe en outre le développement de l'aquaculture en Asie dans un contexte mondial plus vaste et il décrit ses liens avec les systèmes naturels, les conditions sociales et l'économie. Read more ... Que ce soit au travail, à la maison, à l'école ou ailleurs, les TIC ont un réel impact sur la vie quotidienne des gens. Read more ...

Caractérisation des microorganismes thermotrophes impliqués dans ...

African Journals Online (AJOL)

collection de l'herbier Mark-UCAM de la. Faculté des Sciences Semlalia sous le numéro. 8242, le choix du substrat de fermentation est basé sur son abondance, en tant que déchets verts collectés sur la pelouse de l'université. Le Phosphate naturel PNY. Les échantillons du PNY utilisés ont été collectés de la région de ...

Les peptides antimicrobiens d'origine microbienne: cas des ...

African Journals Online (AJOL)

Les bactéries à Gram positif et à Gram négatif et les archées produisent respectivement des bactériocines et des archéocines. Les bactériocines et les archéocines sont des peptides antimicrobiens. Au fil des ans leur rôle dans la sûreté des produits alimentaires n'a cessé d'être démontré, faisant de ces peptides naturels ...

LESIONS INFRA CLINIQUES DU SEIN A LIBREVILLE (GABON ...

African Journals Online (AJOL)

de foyer de micro calcifications d'allure évolutive et suspecte (11%). Une reprise chirurgicale a été jugée nécessaire pour 17 cas de carcinomes canalaires invasifs du fait des marges d'exérèse insuffisantes : 5 mastectomies selon Patey et 12 mastectomies partielles associées, à chaque fois, à un curage ganglionnaire.

The Effect of Defense R&D Expenditures on Military Capability and Technological Spillover

Science.gov (United States)

2013-03-01

as France, divide the expenditure between the civilian (power plants ) and the defense (weapons) sectors (Brzoska, 2005). Finally, enterprise...0.007092 0.008992092 114 Cuba 0.00617 0.007823069 115 Montenegro 0.005834 0.007397048 116 Rwanda 0.005678 0.007199252 117 Jamaica 0.005405 0.00685311...0.0001794 126 1043716034 121 Gabon 0.0001527 127 9138902194 81 Brunei Darussalam 0.0001447 128 14141361533 75 Montenegro 0.0001332 129 1292862098

Caractéristiques sociodémographiques associées au risque de ...

African Journals Online (AJOL)

premier don de Libreville (Gabon). Le diagnostic des agents infectieux a été réalisé par des tests immunoenzymatiques commerciaux de quatrième génération. Les séroréactivités globales du VIH, du VHC, et de la syphilis étaient respectivement de 3,4%, 1,2% et 3,2%. Les donneurs de sang de sexe féminin et ceux.

Evolution de certains composés volatils du bois de chêne au cours de son séchage premiers résultats

Directory of Open Access Journals (Sweden)

Pascal Chatonnet

1994-12-01

Full Text Available Pendant le séchage des merrains sur parc à l'air libre, on assiste à une profonde modification de la composition chimique et du profil aromatique du bois de chêne. La teneur en eugénol, en aldéhydes phénols et en Β-méthyl-y-octalactone augmente régulièrement pendant le vieillissement du bois. Principalement sous forme trans au début du séchage, la Β-méthyl-y-octalactone s'accumule finalement sous la forme cis plus aromatique. Dans le même temps, on observe également une accumulation importante du précurseur inodore de Β-méthyl-y-octalactone. L'intervention des micro-organismes fréquemment isolés sur le bois en cours de séchage naturel sur la formation de composés aromatiques a été étudiée. La culture de diverses moisissures isolées de bois en cours de séchage naturel sur extraits de bois et directement sur sciure de chêne aboutit dans tous les cas à une forte diminution des teneurs en aldéhydes phénols, notamment de la vanilline. En effet, tous les micro-organismes étudiés (Penicilium sp., Trichoderma sp., Aureobasidium sp. sont incapables de dégrader la lignine car ils ne possèdent pas d'activité ligninase. En revanche, ces champignons possèdent une forte activité oxydo-réductase capable de réduire la vanilline en alcool vanillique inodore. En conséquence, les aldéhydes phénols apparaissant au cours du séchage naturel du merrain ne dérivent pas d'une attaque enzymatique mais plus vraisemblablementde l'acidolyse et de l'oxydation chimique de la lignine du bois. Le stockage du bois à l'air libre en présence d'eau et d'oxygène doit permettre une évolution favorable de son potentiel aromatique tant que la vanilline et la cis Β-méthyly-octalactone s'accumulent.

Moroccan Coastal Management : Building Capacity to Adapt to ...

International Development Research Centre (IDRC) Digital Library (Canada)

Études. Vulnérabilité des écosystèmes naturels à l'élévation du niveau de la mer (cas de la lagune de Nador et des communes de Boudinar et Beni Chiker). Téléchargez le PDF. Études. Étude de la vulnérabilité socioéconomique aux changements climatiques et à l'élévation du niveau de la mer (cas de la frange littorale ...

Nouvelles fonctions de l'agriculture et dynamiques des exploitations: une analyse chorématique dans les monts d'Ardèche

Directory of Open Access Journals (Sweden)

Muriel Bonin

2001-06-01

Full Text Available Les modèles spatiaux sont utilisés pour l'analyse des trajectoires d'exploitations agricoles pour mettre en évidence les liens entre les transformations socio-économiques et les dynamiques de territoires. Les traits de dynamiques spatiales sont identifiés et utilisés pour analyser l'impact de l'introduction de l'agritourisme dans les exploitations dans le Parc naturel régional des monts d'Ardèche.

La théorie du chaos vers une nouvelle science

CERN Document Server

Gleick, James

1989-01-01

Là où commence le chaos s'arrêtait jusqu'ici la science. Or, dans les années 70, quelques scientifiques français et américains ont commencé à explorer le chaos. A la surprise générale celui-ci s'est révélé gouverné par un ordre dynamique qui a permis d'expliquer bien des phénomènes naturels jusqu'ici totalement incompréhensibles.

Le projet SIGMIP: vers un serveur régional d'information géographique en Midi-Pyrénées

Directory of Open Access Journals (Sweden)

Christian CRÉPEAU

1993-12-01

Full Text Available Le projet SIGMIP étudie la faisabilité technique et économique d’une base de données géographiques régionale. Une maquette opérationnelle a été mise en place à des fins de démonstration. Des applications concernant la gestion de l’environnement industriel, de l’eau, du milieu naturel, de l’urbanisme et des projets d’infrastructures ont été développées.

Le facteur humain et la sûreté de fonctionnement dans le ...

African Journals Online (AJOL)

Notre contribution porte sur le rôle fondamental du facteur humain dans le management intégré des risques d'une part et du rôle déterminant qu'il peut avoir à jouer pour que la sûreté de fonctionnement réponde à sa propriété d'autre part. Un rôle illustré à travers une analyse de risque dans un complexe de Gaz Naturel ...

Natural occurring radioactive substances. Vol. 1

Energy Technology Data Exchange (ETDEWEB)

Emara, A E [National Center for radiation Research and Technology Atomic Energy Authority, Cairo (Egypt)

1996-03-01

Naturally occurring radioactive substances produced by cosmic rays of those of terrestrial origin are surveyed. The different radioactive decay series are discussed. Special emphasis is given to the element radium as regards its properties and distribution in different environmental samples. The properties of naturally occurring k-40 and its distribution in different natural media are also outlined. Induced radionuclides which are formed as a result of the interaction of cosmic rays with the constituents of the atmosphere are mentioned. In this respect the intensity of natural background radiation and the dose at different locations and levels is surveyed. Some regions of exceptionally high radioactivity which result in high exposure rates are mentioned. Monazite deposits and water springs are mentioned in some detail. The Oklo phenomenon as a natural reactor is also discussed. 8 tabs.

Natural occurring radioactive substances. Vol. 1

International Nuclear Information System (INIS)

Emara, A.E.

1996-01-01

Naturally occurring radioactive substances produced by cosmic rays of those of terrestrial origin are surveyed. The different radioactive decay series are discussed. Special emphasis is given to the element radium as regards its properties and distribution in different environmental samples. The properties of naturally occurring k-40 and its distribution in different natural media are also outlined. Induced radionuclides which are formed as a result of the interaction of cosmic rays with the constituents of the atmosphere are mentioned. In this respect the intensity of natural background radiation and the dose at different locations and levels is surveyed. Some regions of exceptionally high radioactivity which result in high exposure rates are mentioned. Monazite deposits and water springs are mentioned in some detail. The Oklo phenomenon as a natural reactor is also discussed. 8 tabs

Time variation of the fine structure constant driven by quintessence

International Nuclear Information System (INIS)

Anchordoqui, Luis; Goldberg, Haim

2003-01-01

There are indications from the study of quasar absorption spectra that the fine structure constant α may have been measurably smaller for redshifts z>2. Analyses of other data ( 149 Sm fission rate for the Oklo natural reactor, variation of 187 Re β-decay rate in meteorite studies, atomic clock measurements) which probe variations of α in the more recent past imply much smaller deviations from its present value. In this work we tie the variation of α to the evolution of the quintessence field proposed by Albrecht and Skordis, and show that agreement with all these data, as well as consistency with Wilkinson Microwave Anisotropy Probe observations, can be achieved for a range of parameters. Some definite predictions follow for upcoming space missions searching for violations of the equivalence principle

Getting ready for REDD+: Recognition and Donor-country Project Development Dynamics in Central Africa

Directory of Open Access Journals (Sweden)

Gretchen M Walters

2017-01-01

Full Text Available REDD+ (Reducing Emissions, Deforestation and forest Degradation+ is a United Nations Framework Convention for Climate Change (UNFCCC process through which governments reduce the impacts of climate change through forest conservation in a results-based payments scheme. Distinct from international negotiations about the REDD+ framework under the UNFCCC, there are also REDD+ projects that help governments to set up the institutional architecture, plans and strategies to implement REDD+. These capacity-building projects, in the first phase of 'REDD+ readiness', involve negotiations among national and international actors in which recognition and authority claims are used by participants to influence project-level negotiations. This study analyses the project development negotiations in a World Bank-led REDD+ capacity building regional project, involving six Central African countries between 2008 and 2011. It explores how the project created a 'negotiation table' constituted of national and regional institutions recognised by the donors and governments, and how this political space, influenced by global, regional and national political agendas led to 'instances' of recognition and misrecognition – in which some negotiating parties' claims of representation were acknowledge and affirmed, while others' claims were not. Focusing on Cameroon and Gabon, this article analyses how negotiations shaped full participation by Cameroon and only partial engagement by Gabon.

Integral measurements of lattice properties in the natural uranium-graphite critical facility Marius; Mesures globales de reseaux a graphite dans l'empilement critique marius

Energy Technology Data Exchange (ETDEWEB)

Cogne, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

A systematic study of natural uranium-graphite lattices has been undertaken in the critical facility MARIUS, which was built in 1959 in Marcoule. Integral measurement of lattice properties are carried out by the progressive replacement method. This report describes the experimental methods, the analysis of the experiments and the results obtained for lattices with pitches ranging from 192 to 317 mm and fuel elements with cross sections ranging from 6 to 20 cm{sup 2}. The principles of correlation of the results are also outlined. Additional experimental results are also given, pertaining to the determination of the anisotropy, of both the axial and the radial migration areas, and of the age in graphite. (author) [French] L'empilement critique MARIUS, construit en 1959 a Marcoule, a ete utilise pour l'etude systematique des reseaux a graphite-uranium naturel. Les mesures globales de reseaux sont faites par la methode de remplacement progressif. On decrit ici les methodes experimentales utilisees pour ces mesures globales, les principes du depouillement et les resultats obtenus pour des pas de 192 a 317 mm et des combustibles de 6 a 20 cm{sup 2} d'uranium naturel. On donne d'autre part le principe de correlation des mesures. Un certain nombre de resultats experimentaux complementaires sont donnes, en permettant de determiner l'anisotropie, les aires de migration axiale et radiale, l'age dans le graphite. (auteur)

Modelo geoecosistémico para la prospección, uso y manejo del medio y los recursos naturales

Directory of Open Access Journals (Sweden)

Jorge F. Cervantes Borja

1988-06-01

Full Text Available La connaissance fonctionnelle de la relation "puissance–efficience" dans l´utilisation et la conservation des éléments du milieu naturel, indépendamment de sa fonction intrinseque dans le com­plexe géoecosystemique, est une prémisse fondamentale pour que l´homme acquiere la capacité" de gérer, utiliser et conserver les ressources de la nature. Pour arriver à concevoir et comprendre le complexe universel d´interactions qui interviennent dans le fonctionement et l´évo­lution des milieux naturels, la "théorie génerale des systemes" semble etre l´approche la plus appropriée. Dans cet essai il est proposé" une méthode intégrant, par niveaux, une série d´éléments dans lesquels le "géoecotope" répresente l´unité fondamentale de la synthese géoecologique et le "géoecosysteme" l´unité" de base de la régionalisation naturelle. On peut espérer appliquer les résultats obtenus à d´telles que la prospection des resources na­turelles, la gestion de l´environnement, l´aménagement du terri­toire, etc.

Attractivité économique des investissements directs étrangers en zone CEMAC : harmonisation des instruments juridiques aux règles internationales

OpenAIRE

Memphil Ndi , Evelyne Patience

2015-01-01

The currents of the globalization of the markets, marked by the free movement of capital and the phenomenon of free trade supported the implementation of Community policies of economic revival and attractivity of the territories. It is in this impetus that geographical regroupings with economic aiming like the Economic community and Monetarist of Central Africa (CEMAC) appeared. Six countries of Central Africa of which Cameroon, Congo, Gabon, Equatorial Guinea, the Central African Republic an...

Dynamique de fréquentation des grands mammifères dans une ...

African Journals Online (AJOL)

SARAH

31 juil. 2016 ... RÉSUMÉ. Objectifs : Dans le but de connaitre les animaux fréquentant les clairières (ou Baï) forestières au Gabon, une étude sur la fréquentation du Baï de Momba par les grands mammifères a été conduite durant la petite saison des pluies pendant deux mois du 19 février au 13 mars 2012. Méthodologie ...

Research

African Journals Online (AJOL)

ebutamanya

21 oct. 2015 ... Des tests IVA/IVL et FCV ont été effectués chez 309 femmes gabonaises âgées de 18 à ... Au Gabon, ce cancer est généralement diagnostiqué à un stade clinique avancé où ..... prévalences des IST, incluant notamment le VIH, ont été calculées sur la base ... la recherche bibliographique et à la rédaction.

COGEMA's employment and training policy for its foreign subsidiaries

International Nuclear Information System (INIS)

Hamani, A.

2002-01-01

COGEMA has actively pursued a policy of employing country nationals for its foreign subsidiaries in Niger, Gabon, Canada and Kazakhstan. The process of replacing foreign staff by nationals in Niger is first described, detailing the personnel management objectives and procedures, the main difficulties encountered, the current situation and the lessons to take from this experience. COGEMA's policies and ways applied in other countries to increase the proportions of nationals are then presented. (author)

1693-IJBCS-Article-Houndji Bidossessi Victor

African Journals Online (AJOL)

hp

Les feuilles sont triées, lavées et essuyées. Elles sont ensuite séchées à l'ombre dans une pièce bien aérée et naturellement ventilée. Après séchage, les feuilles sont broyées et tamisées. La poudre ainsi obtenue est immédiatement conditionnée dans différents emballages tels que des seaux plastiques opaques de 15 kg ...

Seasonal dynamics of 60Co uptake by freshwater algae under natural conditions

International Nuclear Information System (INIS)

Koulikov, N.V.; Trapeznikov, A.V.

1988-08-01

The data presented in the present report show that the values of 60 Co uptake coefficient in freshwater algae under naturel conditions can change 5-6 times depending on seasons, reaching maximum values in summer. Specific activity of the radionuclide in water can be essentially changed depending on the nuclear power plant operation mode. In such a nonequilibrium system it is rather questionable to use the uptake coefficient as a constant parameter for the determination of the radionuclide specific activity in water [fr

Deux approches du risque d'inondation en France

Directory of Open Access Journals (Sweden)

Bruno LEDOUX

1994-12-01

Full Text Available En France, les sources d’informations centralisées sur les risques naturels sont rares. Pourtant, une politique de prévention engagée par l’État nécessite de disposer d’une information à l’échelle nationale, d’évaluer les enjeux et de mobiliser les acteurs. Deux sources d’informations sont décrites et exploitées, qui permettent, par une représentation cartographique nationale, d’amorcer analyses et débats.

The natural gas for vehicles; Le gaz naturel pour vehicules

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-11-15

This document aims to present the trumps of the natural gas for vehicle (NGV). It discusses the particularities, the actions of the government in favor of the NGV by the creation of financial and legal incentives and the challenges. A detail description of the financial and fiscal assistances and the regulation references are given. (A.L.B.)

288 Géomorphologie structurale et risque naturel dans une portion ...

African Journals Online (AJOL)

Tandus

montrent que cette région a été affectée par trois phases de déformation .... par une répartition inégale des contraintes sur des matériaux à rhéologie .... de la faible charge solide transportée et libérée brutalement sous l'effet du changement ...

Generating daily weather data for ecosystem modelling in the Congo River Basin

Science.gov (United States)

Petritsch, Richard; Pietsch, Stephan A.

2010-05-01

Daily weather data are an important constraint for diverse applications in ecosystem research. In particular, temperature and precipitation are the main drivers for forest ecosystem productivity. Mechanistic modelling theory heavily relies on daily values for minimum and maximum temperatures, precipitation, incident solar radiation and vapour pressure deficit. Although the number of climate measurement stations increased during the last centuries, there are still regions with limited climate data. For example, in the WMO database there are only 16 stations located in Gabon with daily weather measurements. Additionally, the available time series are heavily affected by measurement errors or missing values. In the WMO record for Gabon, on average every second day is missing. Monthly means are more robust and may be estimated over larger areas. Therefore, a good alternative is to interpolate monthly mean values using a sparse network of measurement stations, and based on these monthly data generate daily weather data with defined characteristics. The weather generator MarkSim was developed to produce climatological time series for crop modelling in the tropics. It provides daily values for maximum and minimum temperature, precipitation and solar radiation. The monthly means can either be derived from the internal climate surfaces or prescribed as additional inputs. We compared the generated outputs observations from three climate stations in Gabon (Lastourville, Moanda and Mouilla) and found that maximum temperature and solar radiation were heavily overestimated during the long dry season. This is due to the internal dependency of the solar radiation estimates to precipitation. With no precipitation a cloudless sky is assumed and thus high incident solar radiation and a large diurnal temperature range. However, in reality it is cloudy in the Congo River Basin during the long dry season. Therefore, we applied a correction factor to solar radiation and temperature range

The Dutch disease effect in a high versus low oil dependent countries

OpenAIRE

Allegret , Jean-Pierre; Benkhodja , Mohamed Tahar

2014-01-01

To investigate the main impacts of the recent increase of oil price on oil exporting economies, we estimate a DSGE model for a sample of 16 oil exporting countries (Algeria, Argentina, Ecuador, Gabon, Indonesia, Kuwait, Libya, Malaysia, Mexico, Nigeria, Oman, Russia, Saudi Arabia, United Arab Emirates, and Venezuela) over the period from 1980 to 2010, except for Russia where our sample begins in 1992. In order to distinguish between high-dependent and low-dependent countries, we use two indic...

Gilbertiodendron grandistipulatum (Leguminosae-Caesalpinioideae), a singular species from West Central Africa and new record for Congo (Brazzaville)

OpenAIRE

De La Estrella, Manuel; Devesa, Juan Antonio

2014-01-01

Gilbertiodendron (Leguminosae-Caesalpinioideae) is an endemic tropical African genus of ca. 30 species, most of which are trees of primary forest. The highest concentration of species and morphological variation is found in the Guineo-Congolian region, particularly in Gabon. One of those species is G. grandistipulatum, which is easily recognized by its stipules (up to 18 cm long) and flowers (adaxial petal up to 12.5 × 14 cm). The taxonomy, habitat and distribution of G. grandistipultaum are ...

The ineluctable growing control of OPEC

International Nuclear Information System (INIS)

Anon.

1993-01-01

This paper describes world petroleum supply, petroleum policy and production of OPEC. The great countries of OPEC such Kuwait, Iraq, Iran, Saudi Arabia and United Arab Emirates own 65 percent of world petroleum resources and ensure 25 percent of the world production. Venezuela, Nigeria and Libya dispose of considerable resources which require an important maintenance and heavy investments for using advanced technologies. Algeria, Qatar, Indonesia and Gabon dispose of petroleum resources below twenty years. 1 fig., 1 tab

Meteoritics, Number 19

Science.gov (United States)

1964-06-01

266, 1958. 131. Houziaux, L., Spectres d’absorption infra-rouge de quelques verres naturels entr 2 et 24 microns (Infrared Absorption Spectra of...Taking Pb20L’ 1), Given as a Function of Time. reteorites was made in a work by M. M. Shats (Ref. 10). M. M. Shats de - termined the uranium and lead...billion years. Table 6. Age, l09 Type of Data of Published Meteorite Years Meteorite Source, Investi- gator Kashin 3.00 Chondrite 1951 (Ref. 14), E.K

Fonction et signe de l'arbre dans l'espace urbain de Lomé

OpenAIRE

Tchamie, T.T.K.; Badameli, M.K.

1998-01-01

Le monde végétal est inscrit naturellement dans la conscience des population africaines. Il n'est donc pas étonnant que l'arbre soit omniprésent dans les champs et les agglomérations. Cette présence de l'arbre s'explique par son importance dans la vie des hommes : rôle alimentaire aussi bien pour les hommes que pour les animaux, rôle réligieux, rôle écologique, rôle énergétique...

Les compétences évaluatives des formateurs d'enseignants

OpenAIRE

Jorro , Anne

2005-01-01

Dans cette communication, je présenterai une recherche exploratoire conduite auprès de formateurs d'enseignants dont les missions d'accompagnement des professeurs - stagiaires supposent des compétences évaluatives. Or, les formateurs d'enseignants entrevoient quasi naturellement la nécessité de gagner des compétences analytiques sur l'activité observée. Ces professionnels recourent plus volontiers à des moments d'analyse de pratiques et déclarent éprouver des difficultés à investir l'évaluati...

Consideration of criticality in a nuclear waste repository

International Nuclear Information System (INIS)

Rechard, R.P.; Sanchez, L.C.; Stockman, C.T.; Ramsey, J.L. Jr.; Martell, M.

1995-01-01

The preliminary criticality analysis that was done suggests that the possibility of achieving critical conditions cannot be easily ruled out without looking at the geochemical process of assembly or the dynamics of the operation of a critical assembly. The evaluation of a critical assembly requires an integrated, consistent approach that includes evaluating the following: (1) the alteration rates of the layers of the container and spent fuel, (2) the transport of fissile material or neutron absorbers, and (3) the assembly mechanisms that can achieve critical conditions. The above is a non-trivial analysis and preliminary work suggests that with the loading assumed, enough fissile mass will leach from the HEU multi-purpose canisters to support a criticality. In addition, the consequences of an unpressurized Oklo type criticality would be insignificant to the performance of an unsaturated, tuff repository

Chronological constraints on the Paleoproterozoic Francevillian Group in Gabon

Directory of Open Access Journals (Sweden)

Yusuke Sawaki

2017-03-01

Full Text Available The Francevillian Group in Gabonese Republic was recently established as a typical sedimentary sequence for the Paleoproterozoic. However, its age is rather poorly constrained, mainly based on Rb-Sr and Nd-Sm datings. This study reports new zircon data obtained from Chaillu massif and N'goutou complex, which constrain the protolith age of the basement orthogneisses and the igneous age of an intrusive granite, respectively. Most zircons from the orthogneisses are blue and exhibit oscillatory zoning in cathode-luminescence images. Zircons with lower common lead abundances tend to be distributed close to the concordia curve. Two age clusters around 2860 Ma and 2910 Ma are found in zircons plotted on the concordia curve. Based on the Th/U ratios of zircons, these ages correspond to the protolith ages of the orthogneisses, and the zircons are not metamorphic in origin. Syenites and granites were collected from the N'goutou complex that intrudes into the FA and FB units of the Francevillian Group. The granitoids exhibit chemical composition of A-type granite affinity. Half of zircons separated from the granite are non-luminous, and the remaining half exhibit obscure internal textures under cathode-luminescence observation. All zircon grains contain significant amounts of common lead; the lead isotopic variability is probably attributed to the mixing of two components in the zircons. The zircon radiogenic 207Pb/206Pb ratio is 0.13707 ± 0.0010, corresponding to a 207Pb/206Pb age of 2191 ± 13 Ma. This constrains the minimum depositional age of the FA and FB units. Furthermore, the FB unit consists of manganese-rich carbonate rocks and organic carbon-rich black shales with macroscopic fossils. Based on our age constraints, these organisms appeared in the study area just after the last Paleoproterozoic Snowball Earth event, in concert with global scale oxidation event encompassing the Snowball Earth.

Analyse De La Consultation Prenatale A Libreville, Gabon | Mayi ...

African Journals Online (AJOL)

The aim of this study was to identify deficiencies in antenatal care (ANC) in Libreville and propose correctives measures. This is a cross sectional prospective survey carried out from 1st September 2005 to 31st January 2006, in two public maternities in Libreville. Included in this study were pregnant women with gestational ...

Learning English in Gabon: The Question of Cultural Content.

Science.gov (United States)

Victor, Mbodouma

1999-01-01

Gabonese students who speak French as a second language and are educated through French, learn English using textbooks designed for students in France. Article discusses pedagogical issues, goals that Gabonese students have in learning English, and the linguistic and sociolinguistic context in which learning of English takes place. Materials used…

Microbial processes in radioactive waste disposal

International Nuclear Information System (INIS)

Pedersen, Karsten

2000-04-01

subterranean biosphere in the aquifers of the Fennoscandian Shield. Microbial processes at repository depths will have several important influences on repository performance. Some identified processes are the production of sulphide, carbon dioxide, organic carbon and methane, and the reduction of oxygen. The repository performance must be predicted for very long times. Natural analogues therefore become invaluable. Time-related processes of radionuclide migration have been studied at analogue sites that have been evolving over very long time periods. High pH conditions occur in Maqarin, Jordan; fuel-related processes have evolved at the natural reactors in Oklo, Gabon, and uranium migration processes have developed around the uranium body of Palmottu, in Finland. The majority of the radionuclides are metals. The transport, chemical speciation, and ultimate fate of dissolved metals in aqueous systems are controlled to a large extent by reactions that occur at solid surfaces. Bacteria are at least as widely distributed and probably as reactive as many inorganic solids in aqueous systems. The behaviour of bacteria as geochemically reactive solids can be inferred from extensive research documenting their performance as sorbents of dissolved metals, and as nucleation templates for a wide range of authigenic minerals. They may consequently play a significant role in radionuclide retention and transport processes

Microbial processes in radioactive waste disposal

Energy Technology Data Exchange (ETDEWEB)

Pedersen, Karsten [Goeteborg Univ. (Sweden). Dept. of Cell and Molecular Biology, Microbiology

2000-04-15

subterranean biosphere in the aquifers of the Fennoscandian Shield. Microbial processes at repository depths will have several important influences on repository performance. Some identified processes are the production of sulphide, carbon dioxide, organic carbon and methane, and the reduction of oxygen. The repository performance must be predicted for very long times. Natural analogues therefore become invaluable. Time-related processes of radionuclide migration have been studied at analogue sites that have been evolving over very long time periods. High pH conditions occur in Maqarin, Jordan; fuel-related processes have evolved at the natural reactors in Oklo, Gabon, and uranium migration processes have developed around the uranium body of Palmottu, in Finland. The majority of the radionuclides are metals. The transport, chemical speciation, and ultimate fate of dissolved metals in aqueous systems are controlled to a large extent by reactions that occur at solid surfaces. Bacteria are at least as widely distributed and probably as reactive as many inorganic solids in aqueous systems. The behaviour of bacteria as geochemically reactive solids can be inferred from extensive research documenting their performance as sorbents of dissolved metals, and as nucleation templates for a wide range of authigenic minerals. They may consequently play a significant role in radionuclide retention and transport processes.

Low Prevalence of Pfcrt Resistance Alleles among Patients with Uncomplicated Falciparum Malaria in Niger Six Years after Chloroquine Withdrawal

Directory of Open Access Journals (Sweden)

Adamou Salissou

2014-01-01

Full Text Available Chloroquine (CQ resistance is widespread in Africa, but few data are available for Niger. Pfcrt haplotypes (aa 56–118 and ex vivo responses to CQ and amodiaquine were characterized for 26 isolates collected in South Niger from children under 15 years of age suffering from uncomplicated falciparum malaria, six years after the introduction of artemisinin-based combinations and the withdrawal of CQ. The wild-type Pfcrt haplotype CVMNK was found in 22 of the 26 isolates, with CVIET sequences observed in only three of the samples. We also describe for the first time a new CVINT haplotype. The ex vivo responses were better for CVMNK than for CVIET parasites. Pfcrt sequence data were compared with those obtained for 26 additional parasitized blood samples collected in Gabon, from an area of CQ resistance used as a control. Our findings suggest that there has been a significant decline in CQ-resistant genotypes since the previous estimates for Niger were obtained. No such decline in molecular resistance to CQ was observed in the subset of samples collected in similar conditions from Gabon. These results have important implications for public health and support the policy implemented in Niger since 2005, which aims to increase the efficacy and availability of antimalarial drugs whilst controlling the spread of resistance.

Radio-toxicological analysis of urine; Analyses radiotoxicologiques urinaires

Energy Technology Data Exchange (ETDEWEB)

Jeanmaire, L.; Jammet, H. [Commissariat a l' energie atomique et aux energies alternatives - CEA (France)

1959-07-01

The article is divided into two parts: general and technical. In the general part, a study of the behaviour of radioisotopes in the organism shows the hazards of internal contamination. In addition, the principle of the different methods for the estimation of this contamination is indicated. The second part, which is purely technical, describes some of the methods for urine analysis used in the S.H.A.R.P. radiotoxicology laboratory at the Saclay Nuclear Research Centre. The techniques relate to {sup 239}Pu, {sup 226}Ra, {sup 90}Sr, natural Th, natural U and {sup 233}U. Reprint of a paper published in Annales de Radiologie, Vol. 2, no. 9-10, p. 703-722, 1959 [French] L'article est divise en deux parties: generalites et techniques. Dans les generalites, l'etude du comportement des radioelements dans l'organisme met en evidence les dangers de la contamination interne. De plus le principe des differents moyens permettant d'apprecier cette contamination est indique. La seconde partie, purement technique, expose un certain nombre de methodes d'analyse urinaire utilisees au laboratoire de radiotoxicologie du S.H.A.R.P. au Centre d'Etudes nucleaires de Saclay. Les techniques concernent {sup 239}Pu, {sup 226}Ra, {sup 90}Sr, Th naturel, U naturel et {sup 233}U. Reproduction d'un article publie dans les Annales de Radiologie, Vol. 2, no. 9-10, p. 703-722, 1959.

Analyses comparatives de productions écrites d'apprenants de français et de locuteurs francophones, à l'aide d'outils d'extraction automatique du langage

Directory of Open Access Journals (Sweden)

Jean-Gabriel Ganascia

2005-11-01

Full Text Available De nouveaux logiciels d'analyse textuelle tirent parti des progrès récents effectués en apprentissage symbolique et dans le traitement automatique des langues naturelles. Conçu au LIP6 par Jean-Gabriel Ganascia, le Littératron est l'un d'entre eux ; il extrait automatiquement des motifs syntaxiques à partir de textes écrits en langage naturel. Plus exactement, le Littératron prend comme entrée un arbre d'analyse syntaxique et donne en sortie un certain nombre de motifs syntaxiques récurrents. Associé à un analyseur de textes, qui engendre l'arbre d'analyse syntaxique à partir de textes écrits en langage naturel, il révèle les singularités stylistiques de ces textes. Nous allons voir qu'utilisé en sciences du langage, dans le domaine de l'acquisition du français écrit, le Littératron effectue un diagnostic linguistique de l'apprenant, que celui-ci provienne d'une classe de langue hétérogène (différentes langues maternelles ou homogène (une seule langue maternelle, en l'occurrence ici l'arabe. L'intérêt de cette approche concerne trois domaines : d'une part la didactique des langues, à titre éducatif ; d'autre part, la linguistique computationnelle, et enfin l'enseignement assisté par ordinateur.

Study of a method of detection for natural carbon-14 using a liquid scintillator, recent variations in the natural radio-activity due to artificial carbon-14 (1963); Etude d'une methode de detection du carrons 14 naturel, utilisant un scintillateur liquide - variations recentes de l'activite naturelle dues au carbone 14 artificiel (1963)

Energy Technology Data Exchange (ETDEWEB)

Leger, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-06-15

Among the various natural isotopes of carbon, a radioactive isotope, carbon-14, is formed by the action of secondary neutrons from cosmic rays on nitrogen in the air. Until 1950, the concentration of this isotope in ordinary carbon underwent weak fluctuations of about 2-3 per cent. The exact measurement of this concentration 6 X 10{sup 12} Ci/gm of carbon, and of its fluctuations, are difficult and in the first part of this report a highly sensitive method is given using a liquid scintillator. Since 1950 this natural activity has shown large fluctuations because of the carbon-14 formed during nuclear explosions, and in the second part, the evolution in France of this specific activity of carbon in the atmosphere and biosphere is examined. In the last part is studied the local increase in carbon activity in the atmosphere around the Saclay site, an increase caused by the carbon-14 given off as C{sup 14}O{sub 2}, by the reactors cooled partially with exterior air. (author) [French] Parmi les differents isotopes naturels du carbone, un isotope radioactif, le carbone 14, est forme par l'action de neutrons secondaires due aux rayons cosmiques sir l'azote de l'air. Jusqu'en 1950, la concentration de cet isotope dans le carbone ordinaire est soumise a des fluctuations de faible amplitude, de l'ordre de 2 a 3 pour cent. Les mesures precises de cette concentration, 6. 10{sup -12} Ci/g de carbone, et de ses fluctuations sont delicates, et dans la premiere partie de ce rapport, on decrit une methode de detection a grande sensibilite utilisant un scintillateur liquide. Depuis 1950, cette activite naturelle subit des fluctuations importantes dues au carbone 14 forme lors des explosions nucleaires, et dans la seconde partie, on examine l'evolution en France de l'activite specifique du carbone de l'atmosphere et ce la biosphere. Dans la derniere partie, on etudie l'accroissement local de l'activite du carbone de l'air aux environs du site de Saclay, accroissement provoque par le

Innovative technology for a cost-effective land rig

Energy Technology Data Exchange (ETDEWEB)

Mehra, S.; Bryce, T.

1996-05-01

Sedco Forex has recently completed a new land drilling rig, currently deployed in Gabon, that integrates well construction activities with multiskilling to create cost savings across the board in drilling operations. Historically, operators have produced a comprehensive tender package specifying strictly the type and size of individual rig components and the number of personnel required to drill. In this case, the drilling contractor provides a fit-for-purpose rig, consistent with field location, well profile, operator`s priorities, and local constraints.

Turmoil doesn't dampen enthusiasm

International Nuclear Information System (INIS)

Anon.

1997-01-01

The paper discusses the outlook for the African gas and oil industries. Though Africa remains politically and economically volatile, its vast energy potential is becoming increasingly attractive to foreign oil and gas companies. Separate evaluations are given for Algeria, Egypt, Nigeria, Angola, Libya, Congo, Gabon, Tunisia, Cameroon, Cote D'Ivoire, and briefly for South Africa, Sudan, Equatorial Guinea, Ghana, Zaire, Benin, Mozambique, Chad, Namibia, Tanzania, Eritrea, Guinea-Bissau, Senegal, Morocco, Sao Tome and Principe, Ethiopia, Niger, Madagascar, Rwanda, Mauritania, Seychelles, Uganda, and Liberia

Molecular markers of anti-malarial drug resistance in Central, West and East African children with severe malaria

OpenAIRE

Nguetse, Christian N.; Adegnika, Ayola Akim; Agbenyega, Tsiri; Ogutu, Bernhards R.; Krishna, Sanjeev; Kremsner, Peter G.; Velavan, Thirumalaisamy P.

2017-01-01

BACKGROUND: The Plasmodium falciparum multidrug resistance 1 (PfMDR1), P. falciparum Ca(2+)-ATPase (PfATP6) and Kelch-13 propeller domain (PfK13) loci are molecular markers of parasite susceptibility to anti-malarial drugs. Their frequency distributions were determined in the isolates collected from children with severe malaria originating from three African countries. METHODS: Samples from 287 children with severe malaria [(Gabon: n = 114); (Ghana: n = 89); (Kenya: n = 84)] were genotyped fo...

Innovative technology for a cost-effective land rig

International Nuclear Information System (INIS)

Mehra, S.; Bryce, T.

1996-01-01

Sedco Forex has recently completed a new land drilling rig, currently deployed in Gabon, that integrates well construction activities with multiskilling to create cost savings across the board in drilling operations. Historically, operators have produced a comprehensive tender package specifying strictly the type and size of individual rig components and the number of personnel required to drill. In this case, the drilling contractor provides a fit-for-purpose rig, consistent with field location, well profile, operator's priorities, and local constraints

Production of animal protein in the Congo Basin, a challenge for the future of people and wildlife

OpenAIRE

Moula, Nassim; Hornick, Jean-Luc; Ruppol, Patrick; Antoine-Moussiaux, Nicolas; Leroy, Pascal

2014-01-01

Protein needs are considerable in the Congo Basin, a vast territory dominated by forest and inhabited by tens of millions of people. Whereas over 85% of the DRC’s population of the Basin live in the forest, the situation is different in other countries where the majority is urban (Cameroon, Central African Republic, Congo and Gabon). This paper presents several achievements of the Centre for Tropical Agriculture and Veterinary Medicine in Kinshasa (CAVTK), which aims since 2001 to conduct pil...

Political economy of African uranium and its role in international markets. Final report. International energy studies program

International Nuclear Information System (INIS)

Lynch, M.C.; Neff, T.L.

1982-03-01

The history of uranium development in Africa is briefly summarized. Today there are 4 major uranium producing countries in Africa: Gabon, Niger, Namibia, and South Africa. These nations have the possibility of political instability. In addition, the uranium market has undergone a series of radical changes over the past decade. How these African nations have responded to this changing market, and how their roles in the international market relate to domestic political and economic factors are the topics of this report

Par les fruits et légumes, l’interprétation de différents patrimoines

OpenAIRE

Grison, Pauline

2011-01-01

À partir de l’analyse d’un programme muséographique organisé autour d’un patrimoine naturel, culturel, technique et industriel lié aux fruits et légumes et qui a choisi l’activité d’interprétation comme forme de médiation, l’auteur montre comment cette démarche spécifique permet de concilier l’exigence de fiabilité attachée à l’institution muséale et le respect des intérêts économiques des acteurs de la filière porteurs du projet.

Processus de construction de la confiance et configuration de contrôle de gestion

OpenAIRE

Wafa Khlif

2000-01-01

International audience; L'enrichissement de la compréhension du contrôle de gestion par une dimension plus “humaine” a conduit naturellement à l'émergence de concepts “qualitatifs”. La confiance fait partie de ces concepts ignorés dans un contexte instrumental. L'objectif de cette recherche est d'analyser le processus de construction de la confiance relativement aux éléments de contrôle de gestion. En premier lieu, ce travail discute le lien entre le contrôle de gestion et la confiance dans l...

Analyse spatiale, évaluation et cartographie du risque glissement de terrain

OpenAIRE

Malet , Jean-Philippe; Thiery , Yannick; Maquaire , Olivier; Puissant , Anne

2006-01-01

International audience; RÉSUMÉ : Pour évaluer et cartographier le risque « glissement de terrain », les techniques d'analyse spatiale et les technologies SIG sont rarement utilisées. En particulier, aucune étude concerne la cartographie automatique du risque « glissement de terrain » à grande échelle (1:10,000 è), échelle de travail correspondant à la cartographie règlementaire du risque naturel en France. Cet article présente une procédure en trois étapes pour évaluer et cartographier le ris...

La confrontation entre les ressources en eau et les besoins en eau en moyenne montagne cristalline. Quelles contraintes, quels acteurs et quelles politiques de gestion ?

OpenAIRE

Benmalek , Yohann

2009-01-01

Terrain d'étude : Parc Naturel Régional du Pilat, Syndicat du Pays du Gier, SICALA Antenne de Tence.; The objective of this Doctorate was to put in adequacy water resources and water requirements on average crystalline mountain through the example of the Country of Gier, the Regional Natural reserve of Pilat and S.I.C.A.L.A. "Antenna of Tence ". This work was realized in a space of low mountain range. It corresponds so in the middle geographical in the strict sense as in a space lived by a so...

Measurement of radioactivity in building materials: The case of Portland cement used in Kinshasa

International Nuclear Information System (INIS)

Tshiashala, M.D.; Karisa, N.; Solo, K.; Poloto, I.C.; Bashike, K.M.F.

2005-01-01

The study deals with the measurement of radioactivity in some cement samples from the national manufacture of cement of the west area of the Democratic Republic of Congo. The geological materials used in the cement manufacture process may contain some naturel radioactive elements such as U, Th and K. To do so, direct gamma spectrometry using HPGe detector has been performed. Detected radioisotopes from the three main radioactive families have been quantitatively determined. The U, Th and K contents are of the same order of magnitude as in terrestrial crust

Les estimations du capital humain au Canada : approche fondee sur le revenu de la vie entiere

OpenAIRE

Gu, Wulong; Wong, Ambrose

2010-01-01

Dans le present document, nous produisons une estimation de l'investissement en capital humain fonde sur le marche et du stock de ce capital au Canada au cours de la periode s'etendant de 1970 a 2007 selon l'approche fondee sur le revenu de la vie entiere. Nous comparons cette estimation a celle de l'investissement en capital physique et naturel et du stock de ce capital. En suivant la methode elaboree par Jorgenson et Fraumeni, nous estimons le stock de capital humain sous forme du revenu de...

Le discours amoureux du Colloque sentimental de Verlaine

Directory of Open Access Journals (Sweden)

Cristina Ilinca

2007-05-01

Full Text Available L’univers de Paul Verlaine n’est pas vaste, mais il est assez contradictoire. L’originalité de la poésie verlainienne consiste en la manière dont les tons contrastés de gaieté, de mélancolie, d’innocence et de sensualisme se combinent. Les états d’âme -plaisirs, joie, remords, mélancolie- se mêlent aux paysages naturels - clairs de lune, soleils couchants- et donnent naissance aux « tableaux d’âme » si caractéristiques du symbolisme.

Study of a method of detection for natural carbon-14 using a liquid scintillator, recent variations in the natural radio-activity due to artificial carbon-14 (1963); Etude d'une methode de detection du carrons 14 naturel, utilisant un scintillateur liquide - variations recentes de l'activite naturelle dues au carbone 14 artificiel (1963)

Energy Technology Data Exchange (ETDEWEB)

Leger, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-06-15

Among the various natural isotopes of carbon, a radioactive isotope, carbon-14, is formed by the action of secondary neutrons from cosmic rays on nitrogen in the air. Until 1950, the concentration of this isotope in ordinary carbon underwent weak fluctuations of about 2-3 per cent. The exact measurement of this concentration 6 X 10{sup 12} Ci/gm of carbon, and of its fluctuations, are difficult and in the first part of this report a highly sensitive method is given using a liquid scintillator. Since 1950 this natural activity has shown large fluctuations because of the carbon-14 formed during nuclear explosions, and in the second part, the evolution in France of this specific activity of carbon in the atmosphere and biosphere is examined. In the last part is studied the local increase in carbon activity in the atmosphere around the Saclay site, an increase caused by the carbon-14 given off as C{sup 14}O{sub 2}, by the reactors cooled partially with exterior air. (author) [French] Parmi les differents isotopes naturels du carbone, un isotope radioactif, le carbone 14, est forme par l'action de neutrons secondaires due aux rayons cosmiques sir l'azote de l'air. Jusqu'en 1950, la concentration de cet isotope dans le carbone ordinaire est soumise a des fluctuations de faible amplitude, de l'ordre de 2 a 3 pour cent. Les mesures precises de cette concentration, 6. 10{sup -12} Ci/g de carbone, et de ses fluctuations sont delicates, et dans la premiere partie de ce rapport, on decrit une methode de detection a grande sensibilite utilisant un scintillateur liquide. Depuis 1950, cette activite naturelle subit des fluctuations importantes dues au carbone 14 forme lors des explosions nucleaires, et dans la seconde partie, on examine l'evolution en France de l'activite specifique du carbone de l'atmosphere et ce la biosphere. Dans la derniere partie, on etudie l'accroissement local de l'activite du carbone de l'air aux

Paleocorrosion studies in deep sea sediments and the geological disposal of nuclear wastes

International Nuclear Information System (INIS)

Fehrenbach, L.; Maurette, M.; Guichard, F.; Havette, A.; Monaco, A.

1984-01-01

Uncertainties still surround assessment of the safety of disposal of nuclear wastes incorporated into 'radwaste' matrices. This is mostly due to the long time required for radioactive decay of 237 Np. The present work explores the usefulness of an experimental approach in 'paleocorrosion', which should help in minimizing such uncertainties. In this approach, polished sections of sediments containing high concentrations of natural analogues of radwaste matrices are subjected to element micromapping. Thus it is possible to characterize the long-term interactions of such analogues in their geological repositories, and to identify which generate reaction aureoles and protective and/or unprotective coatings. These analogues include grains incorporated in deep sea sediments (uraninite and quartz from the Oklo uranium ore deposit; volcanic ash particles; magnetic cosmic spherules). The present results indicate that uraninite should be a much more durable radwaste matrix than any type of glass in deep sea sediments. (orig./TWO)

OPEC production: Capital limitations, environmental movements may interfere with expansion plans

International Nuclear Information System (INIS)

Ismail, I.A.H.

1994-01-01

Obtaining capital is a critical element in the production expansion plans of OPEC member countries. Another issue that may impact the plans is the environmental taxes that may reduce the call on OPEC oil by 5 million b/d in 2000 and about 16 million b/d in the year 2010. This concluding part of a two-part series discusses the expansion possibilities of non-Middle East OPEC members, OPEC's capital requirements, and environmental concerns. Non-Middle East OPEC includes Algeria, Gabon, Indonesia, Libya, Nigeria, and Venezuela

Analysis of IgG with specificity for variant surface antigens expressed by placental Plasmodium falciparum isolates

DEFF Research Database (Denmark)

Khattab, Ayman; Reinhardt, Christina; Staalsoe, Trine

2004-01-01

isolates of Gabonese and Senegalese origin tested on plasma samples from Gabon showed parity dependency and gender specificity patterns. There was a significant correlation of plasma reactivity as measured by flow cytometry between different placental isolates. In the plasma of infected primiparous women......, VSAPAM-specific IgG measured by flow cytometry could be correlated with anti-adhesion antibodies measured by the inhibition of CSA binding. CONCLUSION: Recognition of placental parasites shows a parity- and sex- dependent pattern, like that previously observed in laboratory strains selected to bind...

Elementary migration around the Oklo nuclear reactors. Implications for high level radioactive wastes storage

International Nuclear Information System (INIS)

Menet-Dressayre, C.; Menager, M.T.

1993-01-01

The study of Uranium and rare earths near the reactors has displayed the radioelements transfer in the reactors neighbourhood. The main implications for high level radioactive wastes disposal in geological formations are discussed. 12 refs

Optimisation énergétique des procédés de séparation en raffinage et en traitement de gaz naturel Optimal Use of Energy in Separation Processes for Refining and Natural Gas Treatment

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Rojey A.

2006-11-01

Full Text Available Cet article présente une méthode d'optimisation des procédés de séparation basée sur une analyse thermodynamique. Cette analyse s'appuie sur un bilan exergétique qui est établi dans le cas général d'un système quelconque opérant en régime permanent. Les facteurs qui conditionnent le rendement exergétique d'un procédé de séparation sont ensuite examinés. Il en résulte une méthode d'optimisation basée sur une réduction des irréversibilités thermodynamiques. Des exemples concrets d'application en raffinage et en traitement de gaz naturel sont présentés, et on montre comment cette analyse peut déboucher sur la conception de procédés innovants. The optimization of separation units in refining and natural-gas processing must take into consideration new needs and constraints that may seem incompatible. New installations must be designed not only on the basis of energy optimization but also by seeking to minimize investments and to respect new rules concerning environmental protection. The optimization described in this article is based on a thermodynamic analysis of different material and energy exchanges, The energybalance provides a suitable basis for making this analysis. It leads to the defining of an exergy efficiency that is all the higher as the thermodynamic irreversibilities are reduced, and that tends toward one for an ideal reversible system. For a separation process, a separation exergyterm is defined that correspond to the minimum separation work . Distillation is the basic separation operation. The exergy efficiency of this operation is low, and we show that, even in a relatively favorable cas, it is no greater than a value of about 6%. For an atmospheric distillation operation of crude oil, the exergy efficiency is about 4%. This overall exergy efficiency is the product of an external exergy efficiency and an internal exergy efficiency. The external exergy efficiency can be improved by better thermal

Hispanophone culture. Meeting point between Latin America and Africa

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Veronique Solange Okome Beka

2014-08-01

Full Text Available Gabon since its independence in 1960, adopted the teaching of Spanish as second foreign language. Since then, three major objectives were pursued: the linguistic, communicative and cultural, being the later the most prominent one. The (IPN National Pedagogical Institute recommends in its 1996 Guidance Letter, the cultural grounding of the Gabonese student, in order to contribute to their balanced development and their social and cultural integration, making them thoughtful citizens. For this aim, the teacher has the role of transmitting and developing students intercultural values. However, in Gabon, teaching of Spanish as second foreign language is done through manuals conceived in Spain or France. The contents are based on the European cultural view of the world, hiding other realities like Latin American or African ones. Even, when these are shown they are in a  very stereotypical way: drugs, misery, poverty, illegal immigration to the United States or Europe. Very few media offer further background on Afromerican or latinamerican indigenous contexts, even if there are quite noticeable similarities between Africa and America, as regards their cultures and beliefs. Students must know both the history and daily present of Latin America and Africa. Therefore, the latest gabonese educational reforms advocate towards introducing the intercultural perspective in teaching. Nevertheless, without promoting real contact and knowledge between the peoples of these areas, it will be totally unrealistic. Therefore, we favor a pedagogy in which the teaching of Spanish could be a meeting point between America and Africa.

Two decades of temporal change of Earth's inner core boundary

Science.gov (United States)

Yao, Jiayuan; Sun, Li; Wen, Lianxing

2015-09-01

We report two decades of changing behavior of the Earth's inner core boundary (ICB), which provides the simplest explanation for the observed temporal change of the compressional seismic waves that are reflected from the ICB (PKiKP) and refracted in the inner core (PKIKP), from earthquake doublets occurring in South Sandwich Islands between 1993 and 2013. In the early period (before 2003), the ICB is enlarged beneath the western coast of Gabon, Republic of Congo, and southwest Tanzania in the reflected points of the PKiKP observed at seismic stations OBN, AAK, and ARU, while it experiences little change beneath Zimbabwe or/and Kenya, and beneath west Angola or/and north Central African Republic, in the PKIKP entry or/and exit points of AAK and ARU observations, respectively. In the later period (after 1998), the ICB regions beneath the western coast of Gabon, Republic of Congo, and southwest Tanzania either shrink or remain unchanged, and the temporal change migrates to beneath Zimbabwe or/and Kenya, and beneath west Angola or/and north Central African Republic, with a decrease of inner core surface by 5.59 km between 1998 and 2009 beneath Zimbabwe or Kenya and by 1.73 km beneath west Angola or north Central African Republic between 1998 and 2013. These results indicate that ICB temporal change occurs in localized regions and is episodic, rapidly migrating, and alternately enlarged and shrunk.

Microscopie par rayons X dans la fenêtre de l'eau : faisabilité et intérêt pour la biologie d'un instrument de laboratoire

Science.gov (United States)

Adam, J. F.; Moy, J. P.

2005-06-01

La biologie étudie des structures ou des phénomènes sub-cellulaires. Pour cela la microscopie est la technique d'observation privilégiée. La résolution spatiale de la microscopie optique s'avère bien souvent insuffisante pour de telles observations. Les techniques plus résolvantes, comme la microscopie électronique par transmission sont souvent destructrices et d'une complexité peu adaptée aux besoins des biologistes. La microscopie par rayons X dans la fenêtre de l'eau permet l'imagerie rapide de cellules dans leur milieu naturel, nécessite peu de préparation et offre des résolutions de quelques dizaines de nanomètres. De plus, il existe un bon contraste naturel entre les structures carbonées (protéines, lipides) et l'eau. Actuellement cette technique est limitée aux centres de rayonnement synchrotron, ce qui impose une planification et des déplacements incompatibles avec les besoins de la biologie. Un tel microscope fonctionnant avec uns source de laboratoire serait d'une grande utilité. Ce document présente un état de l'art de la microscopie par rayons X dans la fenêtre de l'eau. Un cahier des charges détaillé pour un appareil de laboratoire ayant les performances optiques requises par les biologistes est présenté et confronté aux microscopes X de laboratoire déjà existants. Des solutions concernant la source et les optiques sont également discutées.

Colonial Networks of Power: The Far Reaches of Systems

International Nuclear Information System (INIS)

Hecht, Gabrielle

2004-01-01

Thomas Hughes has shown the links which existed between politics and technological and economic changes. From this point of view, the relationship between colonialism and the development of nuclear systems is interesting. There is a significant continuity from the colonial Empires to the uranium supply networks. Americans and the British worked together to prospect and to exploit uranium deposits, in particular in South Africa. On their side, the French had similar activities in Madagascar, Gabon and Niger. In both cases, important post-colonial ties have been maintained based on techno-politics

Acquisitions de la Bibliothèque de l’Institut de Géographie

Directory of Open Access Journals (Sweden)

2009-10-01

Full Text Available AfriqueAMBOULOU, Zéphirin Sédar, La marche difficile du Congo vers un développement socioéconomique harmonieux et durable, Paris, Publibook, [2009], G 19-3478 AVENOT, Aimé Félix, La décentralisation territoriale au Gabon : entre mimétisme et mystification, Paris, L’Harmattan, DL 2008, G 19-3464 BÂ, Boubacar, Agriculture et sécurité alimentaire au Sénégal, Paris, L’Harmattan, DL 2008, G 19-3463 BANGASSARO COULIBALY, Nguessé Joachim, Le  mal ivoirien : cas symptomatique du mal africain, Paris, ...

[Ebola hemorrhagic fever: its extension reflects the African sanitary disaster].

Science.gov (United States)

Bourée, Patrice

2014-09-01

Ebola virus, described in 1976 in Zaire, causes severe hemorrhagic fever with a high mortality rate in humans and nonhuman primates. Epidemics occurred since this time to nowadays in Sudan, Gabon, Congo and currently in Guinea, Liberia, Sierra-Leone, Nigeria and Senegal. Specific treatment and vaccine are not available. So, to prevent the virus transmission with live and dead patients, we must use strict individual and collective measures which are not always understood by local populations and make contact tracing; it is the only way to curb the epidemic.

Acquisitions de la Bibliothèque Géographie

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Bernadette Joseph

2008-03-01

Full Text Available AfriqueAngola : oil, broad-based growth, and equity, Washington, D.C., World Bank, cop. 2007, G 19-3337BATTISTINI, René, Géographie de l’Afrique orientale, Kenya, Uganda et Tanzanie, Paris, Centre de documentation universitaire, 1969, BCOURS 314BEN YAHMED, Gabon , un pari d’avenir, Paris, les Éd. du Jaguar, DL 2007, G 19-3336BEN YAHMED, HOUSTIN, NDIAYE, WADE, Atlas du Sénégal, Paris, les Éd. J.A., impr. 2007, G 19-3353CHARTON, H., L’Afrique orientale : annuaire 2005, G 19-3289IOP, NIANG DIENE...

Théorie mathématique des catégories en biologie et notion d'équivalence naturelle chez Robert Rosen

OpenAIRE

Varenne , Franck

2011-01-01

L'objectif de cet article est de rendre compte de la justification épistémologique de la proposition faite, dès 1958, par le biomathématicien Robert Rosen d'introduire le concept mathématique de " catégorie " et celui - corrélatif - d'" équivalence naturelle " dans la modélisation mathématique appliquée au vivant. Nos questions sont les suivantes : en quoi la notion mathématique de catégorie permet-elle, selon Rosen, de donner accès à des formalismes plus " naturels " pour la modélisation du ...

CLUNY, Note sur le Recueil des chartes de l’abbaye de Cluny d’Auguste Bernard et Alexandre Bruel.

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Sébastien Barret

2009-06-01

Full Text Available Les six volumes issus des efforts conjugués d’Auguste Bernard (1811-1868 et Alexandre Bruel (1841-1920 forment la base des actes clunisiens intégrés aux CBMA ; ils ont aussi été le fondement de nombreuses études historiques clunisiennes et bourguignonnes. Œuvre collective entamée par Bernard et poursuivie par Bruel qui n’a pu en venir à bout, le Recueil a tout naturellement fait l’objet de compléments et de travaux d’ampleurs variables destinés à le parfaire ; ainsi, le chanoine Maurice Cha...

Analysis of pathogen-induced glutathione S-transferases in Arabidopsis thaliana and a gene related to systemic acquired resistance in cucumber (Cucumis sativus L.)

OpenAIRE

Lieberherr, Damien; Métraux, Jean-Pierre

2005-01-01

Dans leur environnement naturel, les plantes sont exposées en permanence à une grande variété de microorganismes dont certains sont pathogènes. Ainsi, les plantes ont développé au cours de l’évolution des mécanismes de défense multiples et complexes, qui leur permettent de résister à la plupart des microbes pathogènes. La résistance peut s’exprimer localement au site d’infection et systémiquement selon la nature des agents infectieux. Par exemple, suite à une infection par un agent pathogène ...

Télécoms pour l’ingénierie du risque, Tullio Tanzi, Patrick Perrot

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Jean-Baptiste Morin

2013-04-01

Full Text Available "Télécoms pour l’ingénierie du risque" est un ouvrage de 234 pages qui convoque la rencontre entre les Technologies de l’Information de la Communication (TIC et le risque. Les risques naturels, les risques industriels et technologiques ou encore les nouveaux risques générés par des usages déviants dans le domaine du numérique (cybercriminalité sont devenus monnaie courante. Les auteurs Tullio Tanzi (Professeur à Télécom ParisTech, département Traitement du Signal et des Images en télécommun...

Risques sanitaires en Arctique russe

OpenAIRE

Vaguet, Yvette

2013-01-01

La grande diversité géographique de l’Arctique complique l’approche globale. Néanmoins, ses habitants partagent l’expérience d’un milieu naturel extrême inscrit dans un environnement socio-économique récemment entré dans la modernité. À ce titre, l’Arctique russe présente l’originalité d’être la région circumpolaire la plus peuplée et la plus industrielle de toutes. L’article aborde dans une vision dynamique, l’équilibre homme/milieu en interrogeant trois concepts clefs autour du risque : le ...

Valorisation des algues et autres végétaux aquatiques

OpenAIRE

Delepine, René; Gaillard, René; Morand, Philippe

1988-01-01

Cet ouvrage, relatif à la "Valorisation des algues et autres végétaux aquatiques", est publié à un moment où la réflexion menée sur la protection du milieu naturel rejoint les préoccupations économiques de gestion de l'eau et des ressources aquatiques. Il devrait collaborer à la mise en place de stratégies de développement, tant dans le domaine de l'exploitation des algues marines que dans celui de l'utilisation des végétaux d'eau douce. Cet ouvrage s'adresse certes aux acteurs directement...

La Grande Guerre des préfets de Maine-et-Loire

OpenAIRE

Jacobzone, Alain

2015-01-01

La première guerre mondiale est un conflit de type nouveau qui implique la mise en œuvre totale et permanente pendant plus de quatre années de toutes les énergies nationales. Dans cette mobilisation tous azimuts les préfets sont naturellement appelés à jouer un rôle essentiel qui les entraîne, avec une bonne part d’improvisation tant la situation présente des caractères inédits, à intervenir dans tous les domaines de la vie politique, économique et sociale, plus systématiquement et surtout pl...

Des (bio)nano-composites utilisés dans le traitement d'eaux contaminées par de l'arsenic/gentamicine ou pour des applications médicales

OpenAIRE

HE, Jing

2013-01-01

Les composés dits 'bionano' (bionanocomposites) apparaissent comme un nouveau groupe de matériaux hybrides nano-structurés. Ils sont issus de la combinaison de polymères naturels et de solides inorganiques et sont de l'ordre du nanomètre dans au moins une direction. Ces matériaux hybrides conservent les structures et les propriétés fonctionnelles des polymères et matériaux inorganiques dont ils sont composés. Parallèlement, la présence de biopolymères permet de diminuer les risques environnem...

Optique quantique en environnement solide

OpenAIRE

Auffèves , Alexia

2014-01-01

Mon objectif premier a été de revisiter l’optique quantique (initialement explorée avec des atomes et des cavités naturels) avec des atomes et des cavités artificiels, tels que des boîtes quantiques semi-conductrices, ou des qubits en électrodynamique quantique des circuits. Contrairement aux systèmes de physique atomique, les atomes et les cavités de la matière condensée sont couplés à des environnements natifs, qui conduisent à des divergences fon- damentales par rapport à l’...