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Sample records for central sahara algeria

  1. Crustal and upper mantle velocity structure of the Hoggar swell (Central Sahara, Algeria)

    NASA Astrophysics Data System (ADS)

    Ayadi, A.; Dorbath, C.; Lesquer, A.; Bezzeghoud, M.

    2000-02-01

    The Hoggar region is known as one of the most important swells in the African continent. Its altitude culminates at 2908 m in the Tahat hill (Atakor). The Hoggar and other massifs of central Africa (Aı̈r, Eghei, Tibesti, Darfur, Cameroon mount, …) form a system of domal uplifts with similar scale, morphology and volcanic activity. The knowledge of the structure beneath the Hoggar swell will help us to understand the origin of continental swells. In order to get an image of the lithosphere in this region, we have performed a teleseismic field experiment. The 33 short-period seismic stations have been maintained for 2 1/2 month along a 700-km long NNW-SSW profile. This experiment crossed the Central Hoggar and extended northward into the In-Salah Sahara basin which is characterized by high heat flow values of deep origin. The high quality of the data recorded during this experiment allows us to perform a velocity inversion. The Hoggar appears to be characterized by lower mantle velocities. The anomalous zone extends from the upper lithosphere to the mantle. The weak velocity contrast is interpreted in agreement with gravity, geothermal and petrological data as due to extensive mantle modifications inherited from Cenozoic volcanic activity. It confirms that the Hoggar swell is not due to a large-scale uplift of hot asthenospheric materials but corresponds to a now cooled-off modified mantle. On the contrary, local low-velocity zones associated with the Atakor and Tahalra volcanic districts show that hot materials still exist at depths in relation with recent basaltic volcanism.

  2. Quality and management of hot water of intercalary continental, northern Sahara of Algeria

    NASA Astrophysics Data System (ADS)

    Tifrani, Ala Eddine; Nezli, Imed Eddine

    2016-07-01

    The Algerian Sahara is the biggest desert in the world, and it is known by that the main climatic characters which are the high temperature and the low precipitations. The northern Sahara is a part of this big area, located on the south-east of Algeria. Due to the rarely and insufficient precipitations (1 to 180 mm per year) the need for water is a rising problem, so the main source are the ground water. There are three ground water aquifers in the area, the phreatic table, the terminal complex and the intercalary continental, our study is focused on the intercalary continental which is the biggest non recharged aquifer in the world, many studies national and international estimated the reserve of the water around 6 million m3. Existing between 1000 and 2000 m depth, this depth gives the water a lot of characterization which need to be noted and updated for example the temperature (around 50°C), and the high mineralization, because of the vast area and the difference in depths between wells, which is a reason of variety, the main goal is the determination of chemical and physical setting of this water.

  3. Occurrence of fluororichterite and fluorian biotite in the In Tifar trachyte neck (Tazrouk district, Hoggar volcanic province, Sahara, Algeria)

    NASA Astrophysics Data System (ADS)

    Azzouni-Sekkal, Abla; Bonin, Bernard; Ben El Khaznadji, Riad

    2013-09-01

    The unusual occurrence in the In Tifar trachyte neck (Tazrouk district, Hoggar volcanic province, Sahara, Algeria) of the fluorian biotite-fluororichterite association is presented. The two mineral species were previously unknown in the Hoggar and their association is uncommon worldwide. Ti-rich biotite has 28-40% OH sites occupied by fluorine, hence the use of the modifier "fluorian". Sodic-calcic fluororichterite has more than 55% OH sites filled by fluorine, hence the use of the prefix "fluoro". Well-defined F-Mg affinities are documented in both cases, while Cl remains very low. Temperatures are estimated roughly at 775-700 °C at low pressures. The fluorian biotite → fluororichterite sequence of crystallisation implies increasingly high fH2F2/fH2O ratios in metaluminous H2O-dominated evolving to peralkaline F-enriched fluids.

  4. Meso-Cenozoic evolution of the Tuareg Shield (Algeria, Sahara): insights from new thermochronological data

    NASA Astrophysics Data System (ADS)

    Rougier, Sylvain; Missenard, Yves; Gautheron, Cécile; Barbarand, Jocelyn; Zeyen, Hermann; Pinna, Rosella; Liégeois, Jean-Paul; Bonin, Bernard; Ouabadi, Aziouz; El-Messaoud Derder, Mohammed; Frizon de Lamotte, Dominique; Kettouche, Djouher

    2013-04-01

    In North Africa, Meso-Cenozoic large scale topographic swells, such as Hoggar, Tibesti or Darfur domes, are superimposed to a Paleozoic arch and basin morphology which characterizes this region. Although these topographic highs are associated to Cenozoic intraplate volcanism, their development remains poorly constrained, both from temporal and spatial points of view. This study is focused on the Tuareg Shield bulge, a topographic high where Precambrian rocks, exposed over 500000 km², can reach 2400 m above sea level (Atakor district, Hoggar, South Algeria). While presumed Cretaceous sedimentary remnants, resting unconformably over the basement, suggest a possible stage of weak topography during the Mesozoic, current high topography is emphasized by <35 Ma volcanic formations, mostly basaltic in composition. In this context, we present first apatite (U-Th)/He thermochronological data acquired across the whole swell (Rougier et al., Geology, in press). Mean ages range from 78 ± 22 Ma to 13 ± 3 Ma. These results demonstrate the existence of a widespread Eocene exhumation of the shield before volcanic activity began. In the northeastern part of the swell, Cretaceous sedimentary remnants unconformably lying on the basement close to our samples evidence that they were near the surface at that time. We show that basement rocks have thus suffered a subsequent heating stage at 60-80 °C. We also present new apatite fission track ages on same samples. Central ages range from 71 ± 6 to 285 ± 29 Ma. When track length measurements were possible, preliminary modelings of the time-temperature history were performed. As previously deduced from apatite (U-Th)/He analyzes, these modelings show that samples underwent a heating to at least 80°C before their Late Eocene exhumation. Moreover, they also indicate that samples underwent another cooling stage during Lower Cretaceous, prior to Upper Cretaceous/Paleogene heating. We interpret these results as an evidence of a large

  5. Western Sahara Atlas of Algeria: Salt diapirism, orogenic folding and hydrocarbon potential

    SciTech Connect

    Roeder, D. )

    1991-08-01

    The Sahara Atlas has been the Algerian part of the surface trace of the Europe/Africa convergent plate boundary since the early Oligocene. In its western segment, the structure of this detached fold belt is evident in surface mapping, in reflection seismic data, and in a finite plate-tectonic convergence of about 300 km. The northward slope at the Saharan foreland flexure of 5-8{degree} is consistent with northward thinning crust. Very large detached folds with minor thrusts are consistent with an 8 km thick, Triassic to Eocene, marine and nonmarine, polyphase rifted, passive-margin series. The bulk strain in the fold carpet is only 30-40 km, but large folds near the foreland support the theoretical detachment of 130 km. Triassic and Lower Jurassic evaporites occur in nondiapiric anticlinal cores, in Neocomian salt pillows, and in Neogene to Holocene diapirs and fault laminae. The fold trend records the azimuth of plate convergence. The canted mountain-front trend follows an abrupt fault contact (of late Paleozoic or middle Cretaceous age) between Paleozoics on Saharan basement and Hercynian-type basement. The hydrocarbon potential of the Sahara Atlas depends on infolded rifts or aulacogens of early Jurassic age. The northward extension of the Saharan Paleozoic series into the Sahara Atlas is unlikely.

  6. Significance of ground-water chemistry in performance of North Sahara Tube wells in Algeria and Tunisia

    USGS Publications Warehouse

    Clarke, Frank Eldridge; Jones, Blair F.

    1972-01-01

    Nine ground-water samples from the principal shallow and deep North Sahara aquifers of Algeria and Tunisia were examined to determine the relation of their chemical composition to corrosion and mineral encrustation thought to be contributing to observed decline in well capacities within a UNESCO/UNDP Special Fund Project area. Although the shallow and deep waters differ significantly in certain quality factors, all are sulfochloride types with corrosion potentials ranging from moderate to extreme. None appear to be sufficiently supersaturated with troublesome mineral species to cause rapid or severe encrustation of filter pipes or other well parts. However, calcium carbonate encrustation of deep-well cooling towers and related irrigation pipes can be expected because of loss of carbon dioxide and water during evaporative cooling. Corrosion products, particularly iron sulfide, can be expected to deposit in wells producing waters from the deep aquifers. This could reduce filterpipe openings and increase casing roughness sufficiently to cause significant reduction in well capacity. It seems likely, however, that normal pressure reduction due to exploitation of the artesian systems is a more important control of well performance. If troublesome corrosion and related encrustation are confirmed by downhole inspection, use of corrosion-resisting materials, such as fiber-glass casing and saw-slotted filter pipe (shallow wells only), or stainless-steel screen, will minimize the effects of the waters represented by these samples. A combination of corrosion-resisting stainless steel filter pipe electrically insulated from the casing with a nonconductive spacer and cathodic protection will minimize external corrosion of steel casing, if this is found to be a problem. However, such installations are difficult to make in very deep wells and difficult to control in remote areas. Both the shallow waters and the deep waters examined in this study will tend to cause soil

  7. Algeria

    SciTech Connect

    Not Available

    1983-07-01

    Algeria's hydrocarbon industry accounts for 98% of the nation's export earnings, 60-70% of the government's revenues, and 33% of the gross domestic product. Although oil production has declined, it will be replaced by production from Algeria's gas reserves, which rank fourth largest in the world. Official estimates put associated gas reserves at 20 trillion CF and nonassociated reserves at 99.57 TCF. By indexing the price of gas to the price of oil, Algeria plans to receive more realistic revenues for its gas exports. International trade is not the only outlet foreseen for Algerian reserves: by the year 2000, 77% of the gas output will be consumed domestically as the contribution of gas to overall energy requirements grows from 44% in 1979 to 60% in 1990, and the level of energy consumed triples during the same period, rising to 42 million tons/yr of oil equivalent.

  8. Algeria.

    PubMed

    1988-11-01

    The 2nd largest state in Africa, the Democratic and Popular Republic of Algeria is in the Northwest region of Africa along the Mediterranean. 91% of the population of 23 million are situated along the Mediterranean. The government of Algeria parallels the government of the United States in structure containing an executive, legislative and judicial branch and based on a constitution. The roles of the government are discussed as are political conditions and the founding history of the present government. Also discussed is the Algerian defense and foreign relations. The majority of Algerians are Muslim and of Arab, Berber or Arab-Berber stock. The Berbers are the indigenous people of Algeria. European influence, particularly French, is still prevalent however. Natural resources include oil, natural gas, iron ore and uranium, and the most prevalent industries are involved with the production and processing of these resources. While Algeria has made great inroads in the areas of health and education, it still faces a growing problem: housing. Conditions for travel, i.e. transportation, communication, and health, are favorable. PMID:12178069

  9. Effect of the insulation by the mud on the convection in building in the Sahara of Algeria - case of Bechar City

    NASA Astrophysics Data System (ADS)

    Benachour, Elhadj; Draoui, Belkacem; Imine, Baachir; Hasnat, Mohammed; Rahmani, Lakhdar

    2016-03-01

    The thermal behavior of the buildings is a current problem which arouses the interest of many researchers. Indeed, the control of the loads of air conditioning or heating requires a thorough knowledge. Since the thermal quality of the buildings in the Maghreb is there generally very insufficient in particular in the Sahara of Algeria, the insulation proved that it is a very important parameter to minimize the thermal diffusion process inside on all when the insulator is a local material as the Mud which is in our region with a significant amount and almost free quantity. This work presents a study of numerical simulation aiming at the role and the influence of the insulation by the mud Reduced like a local material to the town of Bechar located at the south west of Algeria, or one is interested in a comparative study for pursued these goals. In this context, an analogy was used for the functions which are discretized by the finite difference method and integrated in the Fluent code which is based on the finite volume method. The validation of this procedure was confirmed while comparing some results. The results are presented in the form of distributions of the isotherms, the streamlines, local and average Nusselt of which the goal to study the influence on comfort.

  10. Pre-Islamic Dry-Stone Monuments of the Central and Western Sahara

    NASA Astrophysics Data System (ADS)

    Gauthier, Yves

    Saharan dry-stone monuments are important cultural markers: not only do they highlight the boundaries of the areas occupied by different prehistoric populations, but they also reveal information about the rites and beliefs of Holocene Saharan populations. As climate deteriorated in the Middle Holocene, ways of life changed, with indirect impacts on the architecture of the monuments and on the way they were oriented. Tens of thousands of recorded monuments, of various types, allow us to understand what the orientation rules were and how they changed with location. Data compiled for the eleven types of monuments reveal that many monuments of the central Sahara and Tibesti were probably aligned toward the rising sun or moon, that three types of the Atlantic Sahara show instead a random distribution, and that monuments with a pan-Saharan distribution have a complex orientation pattern. A correlation or orientation with key landscape features is likely for three monument types, coexisting with criteria based on lunisolar alignment.

  11. Dust emission mechanisms in the central Sahara: new insights from remote field observations

    NASA Astrophysics Data System (ADS)

    Allen, C.; Washington, R.; Engelstaedter, S.

    2013-12-01

    North Africa is the world's largest source of mineral aerosol (dust). The Fennec Project, an international consortium led by the University of Oxford, is the first project to systematically instrument the remote central Sahara Desert. These observations have, among others, provided new insights into the atmospheric mechanisms of dust emission. Bordj Badji Mokhtar, in south-west Algeria, is within kilometres of the centre of the global mean summer dust maximum. The site, operated by Fennec partners ONM Algerie, has been heavily instrumented since summer 2011. During the Intensive Observation Period (IOP) in June 2011, four main emission mechanisms were observed and documented: cold pool outflows, low level jets (LLJs), monsoon surges and dry convective plumes. Establishing the relative importance of dust emission mechanisms has been a long-standing research goal. A detailed partitioning exercise of dust events during the IOP shows that 45% of the dust over BBM was generated by local emission in cold pool outflows, 14% by LLJs and only 2% by dry convective plumes. 27% of the dust was advected to the site rather than locally emitted and 12% of the dust was residual or ';background' dust. The work shows the primacy of cold pool outflows for dust emission in the region and also the important contribution of dust advection. In accordance with long-held ideas, the cube of wind speed is strongly correlated with dust emission. Surprisingly however, particles in long-range advection (>500km) were found to be larger than locally emitted dust. Although a clear LLJ wind structure is evident in the mean diurnal cycle during the IOP (12m/s peak winds at 935hPa between 04-05h), LLJs are only responsible for a relatively small amount of dust emission. There is significant daily variability in LLJ strength; the strongest winds are produced by a relatively small number of events. The position and strength of the Saharan Heat Low is strongly associated with the development (or

  12. Tin Bider: A Complex Impact Crater in the Central Saharan Platform (Algeria)

    NASA Astrophysics Data System (ADS)

    Belhai, D. B.; Sahoui, R. S.

    2014-09-01

    The circular structure of Tin Bider is located in the northeast of the Tadmaït (Algeria), This structure about 6000 m in diameter, shows three main concentric rings and a central peak in cretaceous target rocks.

  13. Modeling the synergistic antibacterial effects of honey characteristics of different botanical origins from the Sahara Desert of Algeria

    PubMed Central

    Laallam, Hadda; Boughediri, Larbi; Bissati, Samia; Menasria, Taha; Mouzaoui, Mohamed S.; Hadjadj, Soumia; Hammoudi, Rokia; Chenchouni, Haroun

    2015-01-01

    Background: Honey has multiple therapeutic properties due to its composition with diverse components. Objectives: This study aims to investigate the antimicrobial efficacy of Saharan honeys against bacterial pathogens, the variation of honey floral origins, and its physicochemical characteristics. Materials and Methods: The antimicrobial activity of 32 samples of honey collected from the Algerian Sahara Desert was tested on four bacteria; Bacillus subtilis, Clostridium perfringens, Escherichia coli, and Staphylococcus aureus. The botanical origin of honeys and their physicochemical properties were determined and their combined antibacterial effects were modeled using a generalized linear mixed model (GLMM). Results: Out of the 32 study samples, 14 were monofloral and 18 were multifloral. The pollen density was on average 7.86 × 106 grains/10 g of honey, water content was 14.6%, electrical conductivity (EC) was 0.5 μS/cm, pH was 4.38 ± 0 50, hydroxymethylfurfural (HMF) content was 82 mg/kg of honey, total sugars = 83%, reducing sugars = 71%, and the concentration of proline = 525.5 ± 550.2 mg/kg of honey. GLMM revealed that the antibacterial effect of honey varied significantly between bacteria and floral origins. This effect increased with increasing of water content and reducing sugars in honey, but it significantly decreased with increase of honey EC. E. coli was the most sensitive species with an inhibition zone of 10.1 ± 4.7 mm, while C. perfringens was the less sensitive. Honeys dominated by pollen of Fabaceae sp. were most effective with an overall antimicrobial activity equals to 13.5 ± 4.7 mm. Conclusion: Saharan honeys, of certain botanical origins, have physicochemical and pollinic characteristics with relevant potential for antibacterial purposes. This encourages a more comprehensive characterization of honeys with in vivo and in vitro investigations. PMID:26594206

  14. A 45-year time series of dune mobility indicating constant windiness over the central Sahara

    NASA Astrophysics Data System (ADS)

    Vermeesch, P.; Leprince, S.

    2012-07-01

    Although evidence is mounting that links global warming to changes in atmospheric dynamics over the Atlantic realm, similar studies over the African continent are lacking. And even if such models would exist, it would be difficult to verify their validity due to the paucity of meteorological observations and anemometers in the central Sahara. A pragmatic way around this problem is to monitor barchan dune velocity as a proxy for the windiness of desert areas. Dune migration rates are a measure of the amount of work done by the wind which does not require field measurements but can be observed from space instead. This paper presents a novel application of the remote sensing tool COSI-Corr for the construction of time series of dune mobility from sequences of optical satellite imagery. The technique has been applied to the Bodélé Depression in northern Chad, to demonstrate that dune migration rates in the central Sahara have been remarkably constant for nearly half a century, leading us to conclude that wind velocities have not changed more than 0.2% per year over that period. It is therefore unlikely that the frequency and intensity of dust storms originating from this ‘hot spot’ has significantly changed over the past decades either.

  15. New data on the unresolved paradox of the Tibesti crater paleolakes (Central Sahara, North Chad)

    NASA Astrophysics Data System (ADS)

    Kroepelin, S.; Darius, F.; Deschamps, P.; Dinies, M.; Hoelzmann, P.; Kuper, J.; Oppenheimer, C.; Soulié-Märsche, I.; Sylvestre, F.

    2015-12-01

    Recent field work in the volcanic Tibesti Mountains opens a new chapter in the reconstruction of the last climatic cycles in the central Sahara and their lacustrine environments. For the first time, complete lacustrine sections were sampled in the 900 m deep crater of Trou au Natron at Pic Toussidé (3,315 m a.s.l.), and in 800 m deep Era Kohor, the major sub-caldera of Emi Koussi, the Sahara's 3,445 m high peak (photo). The probed diatomites are located 360 and 125 m above the present-day bottom of the calderas. Studies in the 1960s suggested that lake levels in the Trou au Natron were 300-500 m high at 12,400-14,970 uncal. yrs BP. Such lake depths and resulting water volumes, however, are hardly conceivable in view of the limited intake area and precipitation-evaporation ratios which would have required local rainfall by far surpassing estimates for latitudes 19-21°N from the full-Holocene record of Lake Yoa situated 460 or 220 km southeast, and 1,550 or 2,450 m lower. The presentation will examine whether differences in altitude may explain unparalleled lake depths and postglacial humid conditions 4,000-7,000 years earlier than in the surrounding lowlands, and present alternative hypotheses of lake formation in this Saharan key region.

  16. Inside the “African Cattle Complex”: Animal Burials in the Holocene Central Sahara

    PubMed Central

    di Lernia, Savino; Tafuri, Mary Anne; Gallinaro, Marina; Alhaique, Francesca; Balasse, Marie; Cavorsi, Lucia; Fullagar, Paul D.; Mercuri, Anna Maria; Monaco, Andrea; Perego, Alessandro; Zerboni, Andrea

    2013-01-01

    Cattle pastoralism is an important trait of African cultures. Ethnographic studies describe the central role played by domestic cattle within many societies, highlighting its social and ideological value well beyond its mere function as ‘walking larder’. Historical depth of this African legacy has been repeatedly assessed in an archaeological perspective, mostly emphasizing a continental vision. Nevertheless, in-depth site-specific studies, with a few exceptions, are lacking. Despite the long tradition of a multi-disciplinary approach to the analysis of pastoral systems in Africa, rarely do early and middle Holocene archaeological contexts feature in the same area the combination of settlement, ceremonial and rock art features so as to be multi-dimensionally explored: the Messak plateau in the Libyan central Sahara represents an outstanding exception. Known for its rich Pleistocene occupation and abundant Holocene rock art, the region, through our research, has also shown to preserve the material evidence of a complex ritual dated to the Middle Pastoral (6080–5120 BP or 5200–3800 BC). This was centred on the frequent deposition in stone monuments of disarticulated animal remains, mostly cattle. Animal burials are known also from other African contexts, but regional extent of the phenomenon, state of preservation of monuments, and associated rock art make the Messak case unique. GIS analysis, excavation data, radiocarbon dating, zooarchaeological and isotopic (Sr, C, O) analyses of animal remains, and botanical information are used to explore this highly formalized ritual and the lifeways of a pastoral community in the Holocene Sahara. PMID:23437260

  17. Characterization and evolution of Paleozoic source rock organic matter in Algerian Central Sahara

    SciTech Connect

    Takherist, D.; Arezki, A.; Mouaici, R.

    1995-08-01

    The objective of the proposed poster is to provide a knowledge of the evolution history of organic matter in an intracratonic basin. The Paleozoic source rocks (Ordovician - Silurian - Upper Devonian and Carboniferous) of the Algerian Central Sahara (Ahnet and Timimoun basins) experienced severe conditions of maturation during the geological history, therefore, the source rocks intervals are presently mature to overmature and only dry gas has been descovered throughout this zone. The several geochemical models (Genex, Basimod, Matoil) in addition to Afta and Zafta Data show that regionaly significant heating event occured with maximum palaeo-temperature and maximum gas generation at 300 +/- 30 My. However, high palaeotemperatures can not be explained only by the significant burial. An important anomalous heat flow is needed to explain the geothermal history. In this case, there has been no significant petroleum from the Paleozoic source rocks in this zone since this age; but following some assumptions, a certain hypothesis about a recent generation (-60 to -30 My) is now in discussion.

  18. Crater palaeolakes in the Tibesti mountains (Central Sahara, North Chad) - New insights into past Saharan climates

    NASA Astrophysics Data System (ADS)

    Kröpelin, Stefan; Dinies, Michèle; Sylvestre, Florence; Hoelzmann, Philipp

    2016-04-01

    For the first time continuous lacustrine sections were sampled from the volcanic Tibesti Mountains (Chad): In the 900 m deep crater of Trou au Natron at Pic Toussidé (3,315 m a.s.l.) and from the 800 m deep Era Kohor, the major sub-caldera of Emi Koussi (3,445 m a.s.l.). The remnant diatomites on their slopes are located 360 m (Trou au Natron) and 125 m (Era Kohor) above the present day bottom of the calderas. These sediments from highly continental positions in the central Sahara are keys for the reconstruction of the last climatic cycles (Kröpelin et al. 2015). We report first results from sedimentary-geochemical (total organic and total inorganic carbon contents; total nitrogen; major elements; mineralogy) and palynological analyses for palaeo-environmental interpretations. The diatomites from the Trou au Natron comprise 330 cm of mostly calcitic sediments with relatively low organic carbon (<2.5 %) and strongly varying aragonite and gypsum contents. Major elements (Ca, Fe, K, Mg, Mn, Na, P, S, Sr), elemental ratios (Sr/Ca, Mg/Ca, Fe/Mn) and the mineralogy are used to interpret the lake's salinity, productivity and ecological conditions. Trilete spores are preserved throughout the sequence, probably reflecting local moss/fern stands. Regional pollen rain-e.g. grasses and wormwood-is scarcely represented. Golden algae dominate in the lower section. The results of the first palynological samples suggest a small sedimentation basin. Two 14C-dated charcoals out of the upper part of the section indicate mid-Holocene ages and a linear extrapolation based on a sediment accumulation rate of 1.4mma-1 would lead to tentative dates of ~8650 cal a BP for basal lacustrine sediments and ~4450 cal a BP for the cessation of this lacustrine sequence. The diatomites from the Era Kohor reflect a suite of sections that in total sum up to 145 cm of mostly silica-based sediments with very low carbon contents (< 2% TC). Calcite dominated sediments are only present in the topmost 15

  19. [Malaria in Algerian Sahara].

    PubMed

    Hammadi, D; Boubidi, S C; Chaib, S E; Saber, A; Khechache, Y; Gasmi, M; Harrat, Z

    2009-08-01

    Thanks to the malaria eradication campaign launched in Algeria in 1968, the number of malaria cases fell down significantly from 95,424 cases in 1960 to 30 cases in 1978. At that time the northern part of the country was declared free of Plasmodium falciparum. Only few cases belonging to P. vivax persisted in residual foci in the middle part of the country. In the beginning of the eighties, the south of the country was marked by an increase of imported malaria cases. The resurgence of the disease in the oases coincided with the opening of the Trans-Saharan road and the booming trade with the neighbouring southern countries. Several authors insisted on the risk of introduction of malaria or its exotic potential vectors in Algeria via this new road. Now, the totality of malaria autochthonous cases in Algeria are located in the south of the country where 300 cases were declared during the period (1980-2007). The recent outbreak recorded in 2007 at the borders with Mall and the introduction of Anopheles gambiae into the Algerian territory show the vulnerability of this area to malaria which is probably emphasized by the local environmental changes. The authors assess the evolution of malaria in the Sahara region and draw up the distribution of the anopheles in this area. PMID:19739417

  20. The Sahara's Diverse Landscape

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Vast stretches of uninterrupted sand are only one kind of Saharan landscape. This true-color MODIS image from November 9, 2001, reveals a diversity of land surface features, including ancient lava flows and volcanoes. Beginning at upper left and moving clockwise are the countries of Algeria, Tunisia, Libya, Chad, and Niger. Evidence of previous volcanic activity in the Sahara can be found in northeastern Chad, in particular, in a region known as Tibesti. Reaching up out of the surrounding desert, the dark rock of the Tibesti Plateau stands out in dark brown against the sand. Scattered throughout the region are the circular cones and calderas of several volcanoes. The dark remains of a lava flow mark the location of the Tousside volcano. North of Tibesti, in Libya, more dark-colored lava beds leave their mark on the landscape. Variety exists in Algeria, where the Grand Erg Oriental desert (far upper left) is hemmed in to the south by the Tinrhert Plateau. South of the Plateau, desert resumes briefly, only to give way to a mountainous region traced with impermanent rivers. In northern Niger, a sinuous gray-green line marks the edge of an escarpment that separates the Mangueni Plateau to the north from the rock deserts to the south. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  1. Takarkori rock shelter (SW Libya): an archive of Holocene climate and environmental changes in the central Sahara

    NASA Astrophysics Data System (ADS)

    Cremaschi, Mauro; Zerboni, Andrea; Mercuri, Anna Maria; Olmi, Linda; Biagetti, Stefano; di Lernia, Savino

    2014-10-01

    Rock shelters in the central Saharan massifs preserve anthropogenic stratigraphic sequences that represent both a precious archive for the prehistory of the region and a powerful proxy data for Holocene palaeoenvironments. The geoarchaeological (micromorphology) and archaeobotanical (pollen analysis) approaches were integrated to investigate the anthropogenic sedimentary sequence preserved within the Takarkori rock shelter, a Holocene archaeological site located in the Libyan central Sahara (southern Tadrart Acacus massif). The site was occupied throughout the Early and Middle Holocene (African Humid Period) by groups of hunter-gatherers before and by pastoral communities later. The investigation on the inner part of the sequence allows to recognize the anthropogenic contribution to sedimentation process, and to reconstruct the major changes in the Holocene climate. At the bottom of the stratigraphic sequence, evidence for the earliest frequentation of the site by hunters and gatherers has been recognized; it is dated to c. 10,170 cal yr BP and is characterized by high availability of water, freshwater habitats and sparsely wooded savannah vegetation. A second Early Holocene occupation ended at c. 8180 cal yr BP; this phase is marked by increased aridity: sediments progressively richer in organics, testifying to a more intense occupation of the site, and pollen spectra indicating a decrease of grassland and the spreading of cattails, which followed a general lowering of lake level or widening of shallow-water marginal habitats near the site. After this period, a new occupational phase is dated between c. 8180 and 5610 cal yr BP; this period saw the beginning of the frequentation of pastoral groups and is marked by an important change in the forming processes of the sequence. Sediments and pollen spectra confirm a new increase in water availability, which led to a change in the landscape surrounding the Takarkori rock shelter with the spreading of water bodies. The

  2. A Continuous High-Resolution Climate-Proxy Record of the past 2600 Years from the Central Sahara Desert

    NASA Astrophysics Data System (ADS)

    Verschuren, D.; Schuster, M.; Cocquyt, C.; Russell, J. M.; Engstrom, D. R.; Kroepelin, S.

    2004-12-01

    Persistent lack of high-quality climate-proxy records from the arid-subarid belt of North Africa has hampered analysis of decade-to-century-scale climate tele-connections between warm-temperate southern Europe and the monsoonal climate regimes of sub-Saharan tropical Africa. Here we report recovery of a finely laminated sediment record from Lake Yoa, a stratified hypersaline lake occupying a Pleistocene deflation basin at Ounianga Kebir in northeastern Chad (20.0°N; 20.5°E). It represents a continuous, annual-resolution record of climate and environmental change during the past 2600 14C years from the hyper-arid core of the Sahara desert where rainfall is erratic and annual evaporation exceeds 600 cm. Lake Yoa is one of the very few permanent waters in this region maintained today by sub-surface inflow of fossil groundwater from sandstone aquifers recharged during the early-Holocene humid period. Preliminary sedimentological, chronological and fossil-diatom data suggest that Lake Yoa has been poly- to hyper-saline throughout the sampled period, and with conditions of physical and chemical limnology similar to those prevailing today for at least the past 1000 years. Given that the desert landscape in a large area surrounding Ounianga probably lacked significant ground cover throughout this period, we surmise that variation in aeolian mineral sediment input to the lake, partly reflected in distinct sand layers, could be exploited as a proxy of past changes in the intensity of dry northeasterly trade winds over central North Africa.

  3. The Beni-Ilmane (North-Central Algeria) Earthquake Sequence of May 2010

    NASA Astrophysics Data System (ADS)

    Yelles-Chaouche, A. K.; Abacha, I.; Semmane, F.; Beldjoudi, H.; Djellit, H.

    2014-07-01

    Starting on 14 May 2010 and lasting several months, the village of Beni-Ilmane (Msila District, North-Central Algeria) and its surroundings were struck by an important seismic crisis marked by three successive moderate shocks (5.0 ≤ M d ≤ 5.2). This sequence of events caused severe damage in the Beni-Ilmane village and in the epicentral area. The poor quality of masonry construction and the cumulative effects of the large number of aftershock events played a key role in the destruction. To follow this earthquake sequence, 11 temporary seismic stations, in addition to the permanent stations of the Algerian seismic network, were deployed in the region. A representative set of well located aftershocks in the period of maximum activity (lasting 18 days) were selected. The horizontal distribution of the aftershocks shows two main earthquake clusters located near Beni-Ilmane village, one cluster oriented E-W and the other oriented NNE-SSW, crossing the first cluster at its eastern tip. The aftershocks distribution suggests that the three main shocks ruptured two distinct and adjacent fault segments of about 8 km length. The focal mechanisms of the first and third events, located in the NNE-SSW cluster, show near-vertical left-lateral strike-slip fault planes. In the second cluster, oriented E-W, focal mechanisms show a high-angle reverse fault. A field survey, initiated immediately after the first main shock, identified surface fissures generated by the three largest events in the sequence. The fissures, concentrated in a narrow area at the western termination of the NE-SW Jebel Choukchot anticline (location of Beni-Ilmane village), showed several orientations which were mainly related to gravity instabilities. The 2010 Beni-Ilmane earthquake sequence, located in the Bibans-Hodna Mountains transition zone, demonstrates that the Tellian Atlas-High Plateaus border region is an active seismic zone marked by moderate and possibly strong earthquakes; thus, a reevaluation

  4. Stress change and fault interaction from a two century-long earthquake sequence in the central Tell Atlas (Algeria)

    NASA Astrophysics Data System (ADS)

    Kariche, Jugurtha; Meghraoui, Mustapha; Ayadi, Abdelhakim; Cakir, Ziyadin; Boughacha, Med-Salah

    2016-04-01

    We study the rôle and distribution of stress transfer that may trigger destructive earthquakes in the Central Tell Atlas (Algeria). A sequence of historical events reaching Ms 7.3 and related stress tensor with thrust faulting mechanism illustrates the Coulomb Failure Function (CFF) modeling. We explore here the physical pattern for a stress transfer along the Tell thrust-and-fold belt taking into account an eastward trending earthquake migration from 1891 to 2003. The Computation integrated the seismicity rate in the CFF computation, which is in good agreement with the migration seismicity. The stress transfer progression and increase of 0.1 to 0.8 bar are obtained on fault planes at 7-km-depth with a friction coefficient μ' 0.4 showing stress loading lobes on targeted coseismic fault zone and location of stress shadow across other thrust-and-fold regions. The Coulomb modelling suggest a distinction in earthquake triggering between zones with moderate-sized and large earthquake ruptures. Recent geodetic (InSAR and levelling) studies and aftershocks that document postseismic deformation of major earthquakes are integrated into the static stress change calculations. The presence of fluid and related poroelastic deformation can be considered as open questions on the occurrence of majors earthquakes in the north-central Algeria.

  5. Seismic tomography of the area of the 2010 Beni-Ilmane earthquake sequence, north-central Algeria.

    PubMed

    Abacha, Issam; Koulakov, Ivan; Semmane, Fethi; Yelles-Chaouche, Abd Karim

    2014-01-01

    The region of Beni-Ilmane (District of M'sila, north-central Algeria) was the site of an earthquake sequence that started on 14 May 2010. This sequence, which lasted several months, was triggered by conjugate E-W reverse and N-S dextral faulting. To image the crustal structure of these active faults, we used a set of 1406 well located aftershocks events and applied the local tomography software (LOTOS) algorithm, which includes absolute source location, optimization of the initial 1D velocity model, and iterative tomographic inversion for 3D seismic P- and S-wave velocities (and the Vp/Vs ratio), and source parameters. The patterns of P-wave low-velocity anomalies correspond to the alignments of faults determined from geological evidence, and the P-wave high-velocity anomalies may represent rigid blocks of the upper crust that are not deformed by regional stresses. The S-wave low-velocity anomalies coincide with the aftershock area, where relatively high values of Vp/Vs ratio (1.78) are observed compared with values in the surrounding areas (1.62-1.66). These high values may indicate high fluid contents in the aftershock area. These fluids could have been released from deeper levels by fault movements during earthquakes and migrated rapidly upwards. This hypothesis is supported by vertical sections across the study area show that the major Vp/Vs anomalies are located above the seismicity clusters. PMID:25485193

  6. Seismicity in Central North Africa at low magnitudes: A first look at the TAM event detected data base

    SciTech Connect

    Harben, P.E.,

    1997-01-01

    Teleseismic observations of seismicity in the central North Africa region show that the region is aseismic. This is true for earthquakes with a body wave magnitude greater than about 4 or so. For earthquakes with body wave magnitudes substantially below about 4, the teleseismic observations of seismicity in the central Sahara are incomplete since smaller earthquakes would probably not be detected and located by the current teleseismic monitoring networks. Only one known open seismic station has been operating in the central Sahara. This is the Tamanrasset (TAM) seismic station in southern Algeria. A simple analysis of data records from this station can be used to determine if the central Sahara is also relatively aseismic at magnitudes substantially below 4. That is the primary purpose of this study.

  7. Impact of Climate Change on the Relict Tropical Fish Fauna of Central Sahara: Threat for the Survival of Adrar Mountains Fishes, Mauritania

    PubMed Central

    Trape, Sébastien

    2009-01-01

    Background Four central Sahara mountainous massifs provide habitats for relict populations of fish. In the Adrar of Mauritania all available data on the presence and distribution of fish come from pre-1960 surveys where five fish species were reported: Barbus pobeguini, Barbus macrops, Barbus mirei, Sarotherodon galilaeus, and Clarias anguillaris. Since 1970, drought has had a severe impact in the Adrar where rainfall decreased by 35%. To investigate whether the relict populations of fish have survived the continuing drought, a study was carried out from 2004 to 2008. Methodology/Principal Findings An inventory of perennial bodies of water was drawn up using a literature review and analysis of topographical and hydrological maps. Field surveys were carried out in order to locate the bodies of water described in the literature, identify the presence of fish, determine which species were present and estimate their abundance. The thirteen sites where the presence of fish was observed in the 1950s -Ksar Torchane, Ilij, Molomhar, Agueni, Tachot, Hamdoun, Terjit, Toungad, El Berbera, Timagazine, Dâyet el Mbârek, Dâyet et-Tefla, Nkedeï- were located and surveyed. The Ksar Torchane spring -type locality and the only known locality of B. mirei- has dried up at the height of the drought in 1984, and any fish populations have since become extinct there. The Timagazine, Dâyet el Mbârek and Dâyet et-Tefla pools have become ephemeral. The Hamdoun guelta appears to be highly endangered. The fish populations at the other sites remain unchanged. Four perennial pools which are home to populations of B. pobeguini are newly recorded. Conclusion/Significance The tropical relict fish populations of the Adrar mountains of Mauritania appear to be highly endangered. Of thirteen previously recorded populations, four have become extinct since the beginning of the drought period. New fish population extinctions may occur should low levels of annual rainfall be repeated. PMID:19204792

  8. The Genus Myrtus L. in Algeria: Composition and Biological Aspects of Essential Oils from M. communis and M. nivellei: A Review.

    PubMed

    Bouzabata, Amel; Casanova, Joseph; Bighelli, Ange; Cavaleiro, Carlos; Salgueiro, Ligia; Tomi, Félix

    2016-06-01

    The genus Myrtus L. (Myrtaceae family) comprises two species, Myrtus communis L. (known as common myrtle) growing wild all around the Mediterranean basin and Myrtus nivellei Batt. and Trab. (known as Saharan myrtle), found in central Sahara. Only one country, Algeria, hosts both species, M. communis in the North and M. nivellei in the South. The aim of this review was to collect, summarize, and compare the main results reported relative to the essential oils isolated from aerial parts of both species: botanical aspects, habitat, traditional use, chemical composition, new compounds, antimicrobial activity, antioxidant activity, anti-inflammatory effect, and insecticidal activity. Both essential oils have potential applications in human health. PMID:27159587

  9. Searching for the seafloor signature of the 21 May 2003 Boumerdès earthquake offshore central Algeria

    NASA Astrophysics Data System (ADS)

    Cattaneo, A.; Babonneau, N.; Ratzov, G.; Dan-Unterseh, G.; Yelles, K.; Bracène, R.; Mercier de Lépinay, B.; Boudiaf, A.; Déverchère, J.

    2012-07-01

    Shaking by moderate to large earthquakes in the Mediterranean Sea has proved in the past to potentially trigger catastrophic sediment collapse and flow. On 21 May 2003, a magnitude 6.8 earthquake located near Boumerdès (central Algerian coast) triggered large turbidity currents responsible for 29 submarine cable breaks at the foot of the continental slope over ~150 km from west to east. Seafloor bathymetry and backscatter imagery show the potential imprints of the 2003 event and of previous events. Large slope scarps resulting from active deformation may locally enhance sediment instabilities, although faults are not directly visible at the seafloor. Erosion is evident at the foot of the margin and along the paths of the numerous canyons and valleys. Cable breaks are located at the outlets of submarine valleys and in areas of turbiditic levee overspilling and demonstrate the multi-source and multi-path character of the 2003 turbiditic event. Rough estimates of turbidity flow velocity are not straightforward because of the multiple breaks along the same cable, but seem compatible with those measured in other submarine cable break studies elsewhere. While the signature of the turbidity currents is mostly erosional on the continental slope, turbidite beds alternating with hemipelagites accumulate in the distal reaches of sediment dispersal systems. In perspective, more chronological work on distal turbidite successions offshore Algeria offers promising perspectives for paleoseismology reconstructions based on turbidite dating, if synchronous turbidites along independent sedimentary dispersal systems are found to support triggering by major earthquakes. Preliminary results on sediment core PSM-KS23 off Boumerdès typically show a 800-yr interval between turbidites during the Holocene, in accordance with the estimated mean seismic cycle on land, even if at this stage it is not yet possible to prove the earthquake origin of all the turbidites.

  10. Early to Middle Holocene landscape exploitation in a drying environment: Two case studies compared from the central Sahara (SW Fezzan, Libya)

    NASA Astrophysics Data System (ADS)

    Cremaschi, Mauro; Zerboni, Andrea

    2009-08-01

    The erg Uan Kasa and the wadi Tanezzuft (Libyan Sahara) reacted in different ways to Holocene climatic changes. Consequently, the human groups settled there responded with different ways of adaptation to the drying environment. In the erg Uan Kasa, shallow lakes were formed from the Early to the Mid-Holocene, and their shores were densely inhabited from the Epipalaeolithic to the Pastoral-Neolithic periods. The erg dried out at c. 5000 years BP, but the area was not completely abandoned, as indicated by minor Late Pastoral-Neolithic sites composed of scattered fireplaces. During the wet Holocene, the wadi Tanezzuft was a large meandering river, and its banks were densely settled. At c. 5000 years BP, the stream was not completely dried out, but it changed its pattern, originating an alluvial plain. A large oasis was formed between c. 4000 and 2000 years BP, exploited by Late Pastoral-Neolithic pastoral communities, and later by Garamantians, which introduced soil management and agricultural practices. The Tanezzuft oasis suffered a drastic reduction in size during the first centuries AD, at the time of the abandonment of the Garamantian settlements.

  11. Implementation of geodetic networks in northern Algeria

    NASA Astrophysics Data System (ADS)

    Lammali, K. L.

    2009-04-01

    Northern Algeria, located along the Eurasiatic-African boundary plate is characterised by a moderate to strong seismic activity. During History, some violent earthquakes occurred mainly in the Atlas region, particularly in the Tellian area, leading sometimes to destruction of major cities of Algeria (Algiers, 1716; Oran, 1790; Blida, 1825…). In order to improve the knowledge of the deformation pattern of the Atlasic region, and more globally of the African-Eurasiatic plate boundary along the Algerian margin, the Research Center of Astronomy, Astrophysics and Geophysics (CRAAG) started since two year to implement two major projects: - The REGAT (REseau Géodésique de l'Atlas), consists on a set of 20 continuous GPS stations deployed in the Atlas region, from the coastal area to the Sahara Platform. At this time, fourteen stations have been already installed. The first stations (Algiers-Bouzaréah, Tamanrasset…) of this basic network are producing data since 3 years. First time series are analysed. In 2009, it is projected to extend this network by another set of 50 stations. - The second project consisting in deployment semi permanent GPS networks around four seismogenic basins and active fault areas. Many surveys have been already carried out in the following region. 1) Oran region, west Algeria 2) The Chelif basin (El Asnam region) 3) The Mitidja basin (from Tipaza to Dellys) 4) The Ain Smara (Constantine region) and Sigus (Guelma) faulting In other hand, levelling measurements have been made around the El Asnam seismogenic fault responsible of the important earthquake of October 10 th, 1980 (M:7.3)

  12. High-pressure whiteschists from the Ti-N-Eggoleh area (Central Hoggar, Algeria): A record of Pan-African oceanic subduction

    NASA Astrophysics Data System (ADS)

    Adjerid, Zouhir; Godard, Gaston; Ouzegane, Khadidja

    2015-06-01

    The Ti-N-Eggoleh area (Sérouènout Terrane, Central Hoggar, Algeria) comprises mainly a high-pressure Neoproterozoic metamorphic formation consisting of talc-kyanite-quartz whiteschists, chlorite schists, marbles, sulphide ores, partially serpentinized peridotites and partially amphibolitized eclogites, and reminiscent of an ophiolitic mélange that was metamorphosed and strongly deformed under eclogite-facies conditions. Major and trace elements indicate that the whiteschists underwent intense hydrothermal alteration, with Mg enrichment and leaching of alkalis and Ca, prior to high-pressure metamorphism. The main talc-kyanite-quartz paragenesis is stable within a large multivariant P-T field extending from high-P amphibolite to eclogite facies; the Tschermak substitution in talc marginally constrains peak pressure conditions to P > 11 kbar and 600 < T < ~ 800 °C. The subsequent development of cordierite ± sapphirine ± corundum symplectites and coronae at the contact between talc and kyanite was due to isochemical and almost univariant reactions (Tlc + Ky + Qtz → Crd; Tlc + Ky → Crd + Crn; Tlc + Ky → Crd + Spr) which combined together to produce hybrid microstructures. These metamorphic reactions indicate a thermal overprint under granulite-facies conditions (T = 650-860 °C; P < 12 kbar). The peraluminous Mg-rich sapphirine observed in the symplectites reaches one of the highest degrees of Tschermak substitution ever reported for this mineral (with n = 3.6), intermediate between the 13:19:5 (n = 3) and 3:5:1 (n = 4) theoretical compositions. The neighbouring eclogites record a similar P-T evolution: after the eclogite-facies metamorphic peak, they underwent partial amphibolitization and a subsequent high-temperature overprint under granulite-facies conditions that led to partial dehydration. The Ti-N-Eggoleh series is interpreted as the product of the thermal alteration of oceanic rocks that were subducted prior to the continental collision that formed

  13. The Double Burden of Obesity and Malnutrition in a Protracted Emergency Setting: A Cross-Sectional Study of Western Sahara Refugees

    PubMed Central

    Grijalva-Eternod, Carlos S.; Wells, Jonathan C. K.; Cortina-Borja, Mario; Salse-Ubach, Nuria; Tondeur, Mélody C.; Dolan, Carmen; Meziani, Chafik; Wilkinson, Caroline; Spiegel, Paul; Seal, Andrew J.

    2012-01-01

    Background Households from vulnerable groups experiencing epidemiological transitions are known to be affected concomitantly by under-nutrition and obesity. Yet, it is unknown to what extent this double burden affects refugee populations dependent on food assistance. We assessed the double burden of malnutrition among Western Sahara refugees living in a protracted emergency. Methods and Findings We implemented a stratified nutrition survey in October–November 2010 in the four Western Sahara refugee camps in Algeria. We sampled 2,005 households, collecting anthropometric measurements (weight, height, and waist circumference) in 1,608 children (6–59 mo) and 1,781 women (15–49 y). We estimated the prevalence of global acute malnutrition (GAM), stunting, underweight, and overweight in children; and stunting, underweight, overweight, and central obesity in women. To assess the burden of malnutrition within households, households were first classified according to the presence of each type of malnutrition. Households were then classified as undernourished, overweight, or affected by the double burden if they presented members with under-nutrition, overweight, or both, respectively. The prevalence of GAM in children was 9.1%, 29.1% were stunted, 18.6% were underweight, and 2.4% were overweight; among the women, 14.8% were stunted, 53.7% were overweight or obese, and 71.4% had central obesity. Central obesity (47.2%) and overweight (38.8%) in women affected a higher proportion of households than did GAM (7.0%), stunting (19.5%), or underweight (13.3%) in children. Overall, households classified as overweight (31.5%) were most common, followed by undernourished (25.8%), and then double burden–affected (24.7%). Conclusions The double burden of obesity and under-nutrition is highly prevalent in households among Western Sahara refugees. The results highlight the need to focus more attention on non-communicable diseases in this population and balance obesity prevention

  14. Petroleum geology of the major producing basins of Algeria

    SciTech Connect

    Attar, A.; Chaouch, A.

    1988-08-01

    The South Atlas flexure divides Algeria into two contrasting geologic provinces: (1) the Saharan Atlas and offshore region in the north, both of which are part of the Mediterranean basin, and (2) the Saharan platform on the south, part of the North African craton. The limits of the various sedimentary basins on the Saharan platform are tied to late Paleozoic (Hercynian) crustal reactivation. Comparable structurally controlled basins in northern Algeria are the products of Mesozoic-Recent tectonism. The spatial and temporal distribution of hydrocarbons in the Algerian Sahara can be understood in terms of the geologic evolution of the region. Analysis of areas of proven hydrocarbon reserves permits the following generalizations. (1) There is a concentration of oil and gas fields northeast of a northwest-southeast-trending line connecting Hassi R'Mel with In Amenas. Production is also established in the Sbaa basin and in northern Algeria, where recent discoveries have been made in, respectively, upper Paleozoic and Mesozoic reservoirs. (2) Hydrocarbon are present throughout the entire sedimentary column, but major production currently is restricted to the lower Paleozoic (Cambrian-Ordovician and Lower Devonian) and Triassic reservoirs.

  15. Teaching Abroad: Algeria.

    ERIC Educational Resources Information Center

    Agriopoulos, Michel

    1981-01-01

    Describes a program in Algeria which included the construction of a training facility to ease the shortage of semiskilled workers, particularly construction site electricians and instrument installers. Priorities were to define training needs, implement the program, and produce graduates as soon as possible. (JOW)

  16. Enzootic plague foci, Algeria

    PubMed Central

    Malek, M.A.; Hammani, A.; Beneldjouzi, A.; Bitam, I.

    2014-01-01

    In Algeria, PCR sequencing of pla, glpD and rpoB genes found Yersinia pestis in 18/237 (8%) rodents of five species, including Apodemus sylvaticus, previously undescribed as pestiferous; and disclosed three new plague foci. Multiple spacer typing confirmed a new Orientalis variant. Rodent survey should be reinforced in this country hosting reemerging plague. PMID:25834736

  17. Enzootic plague foci, Algeria.

    PubMed

    Malek, M A; Hammani, A; Beneldjouzi, A; Bitam, I

    2015-03-01

    In Algeria, PCR sequencing of pla, glpD and rpoB genes found Yersinia pestis in 18/237 (8%) rodents of five species, including Apodemus sylvaticus, previously undescribed as pestiferous; and disclosed three new plague foci. Multiple spacer typing confirmed a new Orientalis variant. Rodent survey should be reinforced in this country hosting reemerging plague. PMID:25834736

  18. Algeria: country profile.

    PubMed

    Harding, J

    1987-12-01

    Data are presented on the economy, the people, the population's health, and the culture in this country profile of Algeria. The population numbers 21.7 million. The infant mortality rate, used as a health indicator, is 81/1000 live births. Algeria's gross national product per capita is $2410 (US$15,390). Its main imports are machinery, transport equipment, food, tobacco, and consumer goods. The primary exports include oil, petroleum products, liquified natural gas, wine, and tobacco. Algeria's traditional Berber culture has survived occupation by Phoenicians, Romans, Arabs, and Europeans. The country is made up of an assortment of different social groups and ethnicities, and modern Algeria realized its unitary identity from the anti-colonial struggle. Recent laws allow freedom of association, an indication of growing pluralism in a state where opposition traditionally has been proscribed. 1987 marks the 25th anniversary of Algeria's independence, obtained after a long and bitter war with France. The victory of the Front de Liberation Nationale (FLN) was a signal for French settlers to leave in droves, and much of the country's managerial and technical expertise left with them. Yet, the FLN inherited a sound infrastructure on which to build a modern post-colonial society. Additionally, the country also was to benefit from plentiful hydrocarbon reserves, which guaranteed good foreign exchange earnings. One of the country's goals is to feed itself by investing in a long-neglected agricultural sector, yet presently oil and gas revenues continue to be the driving force behind development. The plans for increasing food production include greater scope for private farmers. A widening gap exists between those who espouse the old values forged by the liberation struggle and a younger generation, for whom the FLN's founding precepts and the leadership's old authoritarian style mean considerably less. PMID:12315296

  19. Dendroagricultural Signal in Algeria

    NASA Astrophysics Data System (ADS)

    Touchan, R.; Kherchouche, D.; Anchukaitis, K. J.; Oudjehih, B.; Touchane, H.; Slimani, S.; Meko, D. M.

    2015-12-01

    Dalila Kherchouche2, Kevin J. Anchukaitis3, Bachir Oudjehih2, Hayat Touchan4, Said Slimani5, and David M. Meko1Drought is one of the main natural factors in declining tree-ring growth and the production of agricultural crops in Algeria. Here we will address the variability of growing conditions for wheat in Algeria with climatic data and a tree-ring reconstruction of January-June precipitation from ten Pinus halepensis tree-ring chronologies. A regression-based reconstruction equation explains up to 74% of the variance of precipitation in the 1970-2011 calibration period and cross validates well. Classification of dry years by the 30% percentile of observed precipitation (131 mm) yields a maximum length of drought of five years (1877-1881) and increasing frequency of dry years in the late 20th and early 21stcenturies. A correlation-based sensitivity analysis shows a similar pattern of dependence of tree-growth and wheat production on monthly and seasonal precipitation, but contrasting patterns of dependence on temperature. The patterns are interpreted by reference to phenology, growth phases, and - for wheat agricultural practices. We apply these interpretations to understand possible impacts of climate variability on the agricultural productivity of past civilizations in the Mediterranean. 2Institute of Veterinary and Agronomy Sciences, The University Hadj-Lakhdar, Batna 05000, Algeria, d.kherchouche@yahoo.fr and oudjehihbachir@yahoo.fr3University of Arizona, ENR2 Building, 1064 E Lowell Street, PO Box 210137, Tucson, AZ 85721-0137, kanchukaitis@email.arizona.edu4Faculty of Agriculture, University of Aleppo, Aleppo-Syria, dr.htouchan@gmail.com5Faculty of Biological Sciences and Agronomy, The University Mouloud Mammeri, Tizi Ouzou 15000, Algeria, slimanisaid@yahoo.fr1Laboratory of Tree Ring Research, The University of Arizona, 1215 E. Lowell St. Bldg. 45B, Tucson, AZ 85721, USA, dmeko@ltrr.arizona.edu

  20. Zoonotic Focus of Plague, Algeria

    PubMed Central

    Bitam, Idir; Baziz, Belkacem; Rolain, Jean-Marc; Belkaid, Miloud

    2006-01-01

    After an outbreak of human plague, 95 Xenopsylla cheopis fleas from Algeria were tested for Yersinia pestis with PCR methods. Nine fleas were definitively confirmed to be infected with Y. pestis biovar orientalis. Our results demonstrate the persistence of a zoonotic focus of Y. pestis in Algeria. PMID:17326957

  1. [Spread of Leishmania major to the north of Algeria].

    PubMed

    Boudrissa, A; Cherif, K; Kherrachi, I; Benbetka, S; Bouiba, L; Boubidi, S C; Benikhlef, R; Arrar, L; Hamrioui, B; Harrat, Z

    2012-02-01

    Since a long time, Leishmania major and L. infantum foci in Algeria were geographically separated by the mountains of the Tell Atlas which represent a natural barrier. Recently, a new focus of cutaneous leishmaniasis (CL) has emerged in the village of El M'hir, located on the north side of the chain of the Tell Atlas, in the basin of the Soummam. During the period 2004-2010, 152 CL cases have been registered and 12 isolates were obtained from patients who declared never having been outside the village the last years. The identification of the parasites showed that all strains belonged to L major MON-25. Investigations on the reservoir hosts showed the presence of the sand rat (Psammomys obesus), for the first time, in this locality. Five strains isolated from this rodent belonged to L. major MON-25. The sand rat, which is usually observed around the chotts in the Saharan and steppe areas, acts as the main reservoir of L. major in Algeria. Its presence in the new focus of El M'hir is reported for the first time. Entomological surveys carried out in 2009 showed the predominance of two sandfly species: Phlebotomus papatasi and P. perniciosus. The first one is known as a vector of L major in the Algerian Sahara. This study highlights the spread of L. major from the arid zones towards the semi arid areas, particularly in the Soummam valley. Climate changes and desertification observed in the steppe area northern Sahara could play a role in the extension of the disease. PMID:22170408

  2. Cenozoic stratigraphy of the Sahara, Northern Africa

    USGS Publications Warehouse

    Swezey, Christopher S.

    2009-01-01

    This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the

  3. Mesozoic and Cenozoic vertical movements in the Atlas system (Algeria, Morocco, Tunisia): An overview

    NASA Astrophysics Data System (ADS)

    de Lamotte, Dominique Frizon; Leturmy, Pascale; Missenard, Yves; Khomsi, Sami; Ruiz, Geoffrey; Saddiqi, Omar; Guillocheau, Francois; Michard, André

    2009-09-01

    The E-W trending Atlas System of Maghreb consists of weakly shortened, intra-continental fold belts associated with plateau areas ("Mesetas"), extending between the south-westernmost branch of the Mediterranean Alpine Belt (Rif-Tell) and the Sahara Platform. Although the Atlas system has been erected contemporaneously from Morocco to Algeria and Tunisia during the Middle Eocene to Recent, it displays a conspicuous longitudinal asymmetry, with i) Paleozoic outcrops restricted to its western part; ii) highest elevation occurring in the west, both in the Atlas System and its foreland (Anti-Atlas); iii) low elevation corridors (e.g. Hodna) and depressed foreland (Tunisian Chotts and Sahel area) in the east. We analyse the origin of these striking contrasts in relation with i) the Variscan heritage; ii) crustal vertical movements during the Mesozoic; iii) crustal shortening during the Cenozoic and finally, iv) the occurrence of a Miocene-Quaternary hot mantle anomaly in the west. The Maghreb lithosphere was affected by the Variscan orogeny, and thus thickened only in its western part. During the Late Permian-Triassic, a paleo-high formed in the west between the Central Atlantic and Alpine Tethys rift systems, giving birth to the emergent/poorly subsident West Moroccan Arch. During the late Middle Jurassic-Early Cretaceous, Morocco and western Algeria were dominantly emergent whereas rifting lasted on in eastern Algeria and Tunisia. We ascribe the uplift of the western regions to thermal doming, consistent with the Late Jurassic and Barremian gabbroic magmatism observed there. After the widespread transgression of the high stand Cenomanian-Turonian seas, the inversion of the Atlas System began during the Senonian as a consequence of the Africa-Eurasia convergence. Erosion affected three ENE-trending uplifted areas of NW Africa, which we consider as lithospheric anticlines related to the incipient Africa-Europe convergence. In contrast, in eastern Algeria and Tunisia a NW

  4. Geochemical variations in aeolian mineral particles from the Sahara-Sahel Dust Corridor.

    PubMed

    Moreno, Teresa; Querol, Xavier; Castillo, Sonia; Alastuey, Andrés; Cuevas, Emilio; Herrmann, Ludger; Mounkaila, Mohammed; Elvira, Josep; Gibbons, Wes

    2006-10-01

    The Sahara-Sahel Dust Corridor runs from Chad to Mauritania and expels huge amounts of mineral aerosols into the Atlantic Ocean. Data on samples collected from Algeria, Chad, Niger, and Western Sahara illustrate how corridor dust mineralogy and chemistry relate to geological source and weathering/transport history. Dusts sourced directly from igneous and metamorphic massifs are geochemically immature, retaining soluble cations (e.g., K, Na, Rb, Sr) and accessory minerals containing HFSE (e.g., Zr, Hf, U, Th) and REE. In contrast, silicate dust chemistry in desert basins (e.g., Bodélé Depression) is influenced by a longer history of transport, physical winnowing (e.g., loss of Zr, Hf, Th), chemical leaching (e.g., loss of Na, K, Rb), and mixing with intrabasinal materials such as diatoms and evaporitic salts. Mineral aerosols blown along the corridor by the winter Harmattan winds mix these basinal and basement materials. Dusts blown into the corridor from sub-Saharan Africa during the summer monsoon source from deeply chemically weathered terrains and are therefore likely to be more kaolinitic and stripped of mobile elements (e.g., Na, K, Mg, Ca, LILE), but retain immobile and resistant elements (e.g., Zr, Hf, REE). Finally, dusts blown southwestwards into the corridor from along the Atlantic Coastal Basin will be enriched in carbonate from Mesozoic-Cenozoic marine limestones, depleted in Th, Nb, and Ta, and locally contaminated by uranium-bearing phosphate deposits. PMID:16600327

  5. Sahara: Barrier or corridor? Nonmetric cranial traits and biological affinities of North African late Holocene populations.

    PubMed

    Nikita, Efthymia; Mattingly, David; Lahr, Marta Mirazón

    2012-02-01

    The Garamantes flourished in southwestern Libya, in the core of the Sahara Desert ~3,000 years ago and largely controlled trans-Saharan trade. Their biological affinities to other North African populations, including the Egyptian, Algerian, Tunisian and Sudanese, roughly contemporary to them, are examined by means of cranial nonmetric traits using the Mean Measure of Divergence and Mahalanobis D(2) distance. The aim is to shed light on the extent to which the Sahara Desert inhibited extensive population movements and gene flow. Our results show that the Garamantes possess distant affinities to their neighbors. This relationship may be due to the Central Sahara forming a barrier among groups, despite the archaeological evidence for extended networks of contact. The role of the Sahara as a barrier is further corroborated by the significant correlation between the Mahalanobis D(2) distance and geographic distance between the Garamantes and the other populations under study. In contrast, no clear pattern was observed when all North African populations were examined, indicating that there was no uniform gene flow in the region. PMID:22183688

  6. The megageomorphology of the radar rivers of the eastern Sahara

    NASA Technical Reports Server (NTRS)

    Mccauley, John F.; Breed, Carol S.; Schaber, Gerald G.

    1986-01-01

    The Eastern Sahara is devoid of surface drainage; this unusual characteristic distinguishes its morphology from that of most other desert regions where running water dominates landscape development. A map derived from SIR-A/B and LANDSAT images and the literature, shows the major presently known paleodrainages in the Eastern Sahara. This compilation permits consideration of the key questions: Where did the radar rivers come from and where did they go? Analysis of SIR-A data led McCauley et al. to suggest that the radar rivers, because of their southwestward trends, once flowed into the Chad basin. This key North African feature is a regional structural low formed in the Early Cretaceous in response to initial opening of the South Atlantic. The problem of the origin of headwaters for the radar rivers was less tractable. The idea that the source areas of the radar rivers might originally have been the same as those later captured by the Nile was proposed tentatively. A more extensive review of the Cenozoic tectonic history of North Africa reveals no reason now to suppose that the Central African tributaries of the present Nile were ever connected to the large alluvial valleys in southwestern Egypt and northwestern Sudan. formed in the Early Cretaceous in response to initial opening of the South Atlantic. The problem of the origin of headwaters for the radar rivers was less tractable. The idea that the source areas of the radar rivers might originally have been the same as those (The Ethiopian Highlands) later captured by the Nile was proposed tentatively. A more extensive review of the Cenozoic tectonic history of North Africa reveals no reason now to support that the Central African tributaries of the present Nile were ever connected to the large alluvial valleys in southwestern Egypt and northwestern Sudan.

  7. The role of convectively-generated cold pools on model biases in the Sahara

    NASA Astrophysics Data System (ADS)

    Garcia-Carreras, Luis; Marsham, John H.; Parker, Douglas J.; Bain, Caroline L.; Milton, Sean; Saci, Azzedine; Salah-Ferroudj, Mohammed; Ouchene, Bouziane; Washington, Richard

    2013-04-01

    Radiosonde data from Fennec supersite-1 (Bordj Badji Mokhtar, Algeria) have been used to confront for the first time global model behaviour in the remote Sahara with regular in-situ profile observations. Convectively-generated cold pools are produced by the evaporation of precipitation and can propagate over large distances, particularly at night. These are an important component of mesoscale convective systems, which produce the majority of rainfall in the Sahel, and have been observed to ventilate the Sahara. Cold pools are, however, very poorly captured by parameterisations of convection. We assess how cold pool outflows from moist convection contribute to model biases in the Sahara and evaluate the impact of data assimilation on model analyses. The Saharan heat low is too warm and dry in the forecast and cold pools are shown to contribute to the majority of the mean bias. Although the model does not represent dust and cold pools are an important dust uplift mechanism, the sign of the errors is inconsistent with radiative impacts of dust. These biases can therefore be directly attributed to the missing advective cooling from cold pools. Cold pools cause 29% of the observed meridional humidity flux, but this contribution is absent both in the forecast and analysis, thus affecting the large-scale water cycle of the West African monsoon/Saharan heat low system. Assimilation of the radiosonde data reduces these errors, but significant temperature and meridional humidity-flux biases remain at night, when cold pools are most frequent and intense. This implies that significant errors remain in the analysis, and that these biases have a diurnal cycle which will in turn affect the diurnal cycle in the model. The model biases are consistent with the larger-scale heat-low biases in the operational Unified Model. Furthermore, model analyses show significant differences in the Sahara, hampering efforts to evaluate model performance in such a data-sparse region. These issues

  8. GHYRAF (Gravity and HYdrology in AFrica): a New Experiment Combining Hydrology and Geodesy to Investigate Water Storage Changes from the Sahara to the Equatorial Monsoon Zone.

    NASA Astrophysics Data System (ADS)

    de Linage, C.; Hinderer, J.; Boy, J.; Masson, F.; Gegout, P.; Diament, M.; de Viron, O.; Bayer, R.; Balmino, G.; Biancale, R.; Bonvalot, S.; Genthon, P.

    2007-12-01

    We present a new project using multi-disciplinary data (gravity, geodesy, hydrology, and meteorology) to determine seasonal changes in water storage in Africa. We foresee to concentrate on two areas: the desert zone in the Sahara (Tamanrasset, Algeria) where almost no hydrological change is present, and the equatorial monsoon band (Niger, Benin Republic) that provides on the contrary a large rainfall signal. This project will be a first attempt to do a ground validation of satellite-derived gravity observations such as GRACE or GOCE in Africa. We will pay attention to the various length scales involved in hydrological processes that are differently retrieved whether gravity is measured at the ground or by satellite. Our experience includes two types of ground-based gravity measurements. First we will perform a repeated survey with absolute gravimeters (AG) on a North-South profile during 2-3 years (2008-2010) to assess the large soil moisture changes as predicted by existing hydrological models such as GLDAS or LadWorld. Second we plan to establish a superconducting gravimeter (SG) to act as a continuously monitored base station in a region of large soil moisture changes. In addition, continuous geodetic GPS measurements will be made along the gravity profile to assess the vertical deformation which acts to alter ground gravity but not satellite gravity. In-situ measurements of hydrological parameters at each station will assist us in modelling local gravity effects. The goal is a better characterization of continental water storage, particularly in the critical areas of water management in the north and central parts of the African continent.

  9. Wet phases in the Sahara/Sahel region and human migration patterns in North Africa

    PubMed Central

    Castañeda, Isla S.; Mulitza, Stefan; Schefuß, Enno; Lopes dos Santos, Raquel A.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2009-01-01

    The carbon isotopic composition of individual plant leaf waxes (a proxy for C3 vs. C4 vegetation) in a marine sediment core collected from beneath the plume of Sahara-derived dust in northwest Africa reveals three periods during the past 192,000 years when the central Sahara/Sahel contained C3 plants (likely trees), indicating substantially wetter conditions than at present. Our data suggest that variability in the strength of Atlantic meridional overturning circulation (AMOC) is a main control on vegetation distribution in central North Africa, and we note expansions of C3 vegetation during the African Humid Period (early Holocene) and within Marine Isotope Stage (MIS) 3 (≈50–45 ka) and MIS 5 (≈120–110 ka). The wet periods within MIS 3 and 5 coincide with major human migration events out of sub-Saharan Africa. Our results thus suggest that changes in AMOC influenced North African climate and, at times, contributed to amenable conditions in the central Sahara/Sahel, allowing humans to cross this otherwise inhospitable region. PMID:19910531

  10. Wet phases in the Sahara/Sahel region and human migration patterns in North Africa.

    PubMed

    Castañeda, Isla S; Mulitza, Stefan; Schefuss, Enno; Lopes dos Santos, Raquel A; Sinninghe Damsté, Jaap S; Schouten, Stefan

    2009-12-01

    The carbon isotopic composition of individual plant leaf waxes (a proxy for C(3) vs. C(4) vegetation) in a marine sediment core collected from beneath the plume of Sahara-derived dust in northwest Africa reveals three periods during the past 192,000 years when the central Sahara/Sahel contained C(3) plants (likely trees), indicating substantially wetter conditions than at present. Our data suggest that variability in the strength of Atlantic meridional overturning circulation (AMOC) is a main control on vegetation distribution in central North Africa, and we note expansions of C(3) vegetation during the African Humid Period (early Holocene) and within Marine Isotope Stage (MIS) 3 ( approximately 50-45 ka) and MIS 5 ( approximately 120-110 ka). The wet periods within MIS 3 and 5 coincide with major human migration events out of sub-Saharan Africa. Our results thus suggest that changes in AMOC influenced North African climate and, at times, contributed to amenable conditions in the central Sahara/Sahel, allowing humans to cross this otherwise inhospitable region. PMID:19910531

  11. Geology and petroleum resources of north-central and northeast Africa

    SciTech Connect

    Peterson, J.A.

    1986-05-01

    In north-central and northeast Africa, important petroleum accumulations exist in the Sirte basin of Libya, the western Sahara region of Algeria, the Pelagian platform offshore from eastern Tunisia, and in the Western Desert basin, Suez graben, and Nile delta in Egypt. Approximately 55 major fields (> 100 million BOE), of which 15 are giants (> 1 billion BOE), have been found in these provinces. Total estimated ultimate production from existing fields in 60 billion bbl of oil and 100 tcf of gas; estimated undiscovered petroleum resources are 26 billion bbl of oil and 93 tcf of gas. The post-Precambrian sedimentary basins of north Africa are related to the development of the Sahara platform during at least four main tectonic episodes (the Caledonian, Hercynian, Laramide, and Alpine cycles). The sedimentary cover of the platform, which includes rocks of all geologic systems, ranges from less than 1000 m (3300 ft) in the south to more than 9000 m (30,000 ft) along the Mediterranean coast. Paleozoic rocks are primarily continental and nearshore marine sandstone and shale, which are important reservoir and source rocks for petroleum in the central and western parts of the Sahara platform. Lower Mesozoic rocks were deposited in a continental and restricted marine environment, and contain thick beds of red beds and evaporites, including salt, which are important seals for oil and gas fields. Upper Mesozoic and Tertiary rocks are related to the development of the Mediterranean Tethys geosyncline and are characterized by numerous transgressive-regressive cycles of the Tethyan seaway. Marine carbonate and shale facies are dominant in the Upper Jurassic, Cretaceous, and lower Tertiary section of northern Libya, eastern Tunisia-Pelagian platform, and northern Egypt. Upper Tertiary beds are continental clastics on most of the platform, except near the Mediterranean.

  12. Negotiating an ecological barrier: crossing the Sahara in relation to winds by common swifts.

    PubMed

    Åkesson, Susanne; Bianco, Giuseppe; Hedenström, Anders

    2016-09-26

    The Sahara Desert is one of the largest land-based barriers on the Earth, crossed twice each year by billions of birds on migration. Here we investigate how common swifts migrating between breeding sites in Sweden and wintering areas in sub-Saharan Africa perform the desert crossing with respect to route choice, winds, timing and speed of migration by analysing 72 geolocator tracks recording migration. The swifts cross western Sahara on a broad front in autumn, while in spring they seem to use three alternative routes across the Sahara, a western, a central and an eastern route across the Arabian Peninsula, with most birds using the western route. The swifts show slower migration and travel speeds, and make longer detours with more stops in autumn compared with spring. In spring, the stopover period in West Africa coincided with mostly favourable winds, but birds remained in the area, suggesting fuelling. The western route provided more tailwind assistance compared with the central route for our tracked swifts in spring, but not in autumn. The ultimate explanation for the evolution of a preferred western route is presumably a combination of matching rich foraging conditions (swarming insects) and favourable winds enabling fast spring migration.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'. PMID:27528783

  13. Sandstorms as indicators of Land degradation in Algeria

    NASA Astrophysics Data System (ADS)

    Hirche, azziz; Oukil, youcef; Boughani, madjid; Nedjraoui, dalila; Salamani, mostefa

    2013-04-01

    : Land degradation, is an important environmental issue in arid lands, especially in Algeria's high plateaus. The Algerian steppes, the most widespread rangelands in the North African countries, occupy a pivotal position between the north, hilly and humid (called the tell), with a limited area (approximately 5%) and the south, the Sahara, which represents the largest area of the country (approximately 86%) and the largest desert of the planet .The main vegetation units constituted by Stipa tenacissima a key species , constituted 2/3 of the landscape in 1978 and occupies in 2012 only 1/10. The vegetation cover reached 40% in the seventies and is generally less than 10% nowadays. The increase of both population and livestock leads to a high pressure on this fragile ecosystems aggravated by the huge drought in the eighties (1980-1988). It results a tremendous soil degradation and sand encroachment. This study emphasizes on the correlation between the desertification steps and the occurrence of sandstorms. It appears that a high correlation is observed and reflect perfectly the land degradation . The recent decrease of sand storms, after a decennium, shows a re-greening, that must be distinguished of an absence of desertification. It appears that sandstorms , could be an interesting indicator, to monitor land degradation.

  14. Rights of the Child in Algeria.

    ERIC Educational Resources Information Center

    Mejia, Fernando

    This report to the United Nations Committee on the Rights of the Child contains observations of the World Organisation Against Torture (OMCT) concerning the application of the Convention on the Rights of the Child by Algeria. The report's introduction asserts that although OMCT welcomes legislative and institutional efforts made by Algeria since…

  15. What Future for Berber Languages in Algeria?

    ERIC Educational Resources Information Center

    Houcine, Samira

    2011-01-01

    After Algeria wrenched its independence from France in 1962, the government newly formed decided to achieve Arabization. Standard Arabic became thus the official language of Algeria and the complete Arabization of all public institutions was voted in January 1991. Actually, the Algerian linguistic situation is one of multilingualism where Algerian…

  16. Algeria: Revolution, Army and Political Power

    ERIC Educational Resources Information Center

    Zeraoui, Zidane

    2012-01-01

    Despite the numerous similarities among the Arab countries that explain the rapid popular movements since the end of 2010, the case of Algeria presents particular features. It shares the same inequalities and social challenges as the rest of the countries in the region. However, the revolutionary process in Algeria between 1954 and 1962 and the…

  17. Bacterial Composition and Survival on Sahara Dust Particles Transported to the European Alps

    PubMed Central

    Meola, Marco; Lazzaro, Anna; Zeyer, Josef

    2015-01-01

    Deposition of Sahara dust (SD) particles is a frequent phenomenon in Europe, but little is known about the viability and composition of the bacterial community transported with SD. The goal of this study was to characterize SD-associated bacteria transported to the European Alps, deposited and entrapped in snow. During two distinct events in February and May 2014, SD particles were deposited and promptly covered by falling snow, thus preserving them in distinct ochre layers within the snowpack. In June 2014, we collected samples at different depths from a snow profile at the Jungfraujoch (Swiss Alps; 3621 m a.s.l.). After filtration, we performed various microbiological and physicochemical analyses of the snow and dust particles therein that originated in Algeria. Our results show that bacteria survive and are metabolically active after the transport to the European Alps. Using high throughput sequencing, we observed distinct differences in bacterial community composition and structure in SD-layers as compared to clean snow layers. Sporulating bacteria were not enriched in the SD-layers; however, phyla with low abundance such as Gemmatimonadetes and Deinococcus-Thermus appeared to be specific bio-indicators for SD. Since many members of these phyla are known to be adapted to arid oligotrophic environments and UV radiation, they are well suited to survive the harsh conditions of long-range airborne transport. PMID:26733988

  18. Algeria`s gas resources: A global evaluation and perspectives

    SciTech Connect

    Takherist, D.; Attar, A.; Drid, M.

    1995-08-01

    With more than 3 Tcm of proven recoverable reserves, Algeria is considered to play a major role in the gas market. If the export capacity is now about 20 Bcm , Sonatrach expects to reach, after the renovation of some industrial units, a level of nearly 27 Bcm, starting in 1996. Here we discuss the geological and geographical distribution of the proven gas reserves. Many consistent fields, except the Hassi R`Mel giant field, are not yet been developed the existing infrastructure network and near-futur projects will allow Sonatrach to produce more than 60 Bcm per year, from now until the year 2000. This objective entails a serious effort in exploration and development activities. If we try to estimate ultimate resources by geochemical modeling, considering only the two min source rocks and the volumes of gas generated-expelled after the min period of trap formation, we find about 160 Tcf of dry gas and 16 Tcf of condensate that can be explored. Our experience with the existing discovered fields, our knowledge of well-defined traps, reservoirs and seals, and the success ratio in the 30 past years, basin by basin, shows that about 36 Tcf can be considered as yet to be discovered. These two numbers indicate that Algeria`s gas potential is underexplored at present. The use of new technologies such as high-resolution and 3D seismic in exploration, and stimulation operations and horizontal well drilling in development-production, is an urgent need. Updating the legislative framework, which will extend laws applicable to liquid hydrocarbon to include gas, will constitute an attractive opportunity for more partnership, permitting the introduction of new ideas and technologies.

  19. Evening Pass Over the Sahara Desert and the Middle East

    NASA Video Gallery

    This video over the Sahara Desert and the Middle East was taken by the crew of Expedition 29 aboard the International Space Station. This sequence of shots was taken on Oct. 6, 2011, from 19:46:23 ...

  20. [Epidemiology of bacillary dysentery in Algeria. II. The seasonality of dysentery].

    PubMed

    Shkarin, V V; Ouchfoun, A; Minaev, V I; Naceur, D

    1983-04-01

    Morbidity rises during the period of summer and autumn are characteristic of bacterial dysentery in Algeria. During the last 18 years no essential changes in the seasonal character of bacterial dysentery were observed in the country taken as a whole. However, in different climatic and geographical zones of the country the seasonal character of dysentery greatly varies from one zone to another and essentially differs from the seasonal character of dysentery morbidity, typical of the country as a whole for many years. The most pronounced manifestations of seasonal rises are observed in the Sahara zone. The seasonal character of dysentery is formed mainly by morbidity among patients belonging to 3 age groups. The seasonal rises of dysentery can be probably explained by the complex of social and climatic factors, as well as by the biological features of the causative agents of this disease. PMID:6868889

  1. Depositional systems and stratigraphy of Paleozoic and Lower Mesozoic rocks in outcrop, Tassili region, southwest Algeria

    SciTech Connect

    Hertig, S.P.; Tye, R.S.; Coffield, D.Q.; Howes, J.V.C. ); Ferhati, S. )

    1991-08-01

    Paleozoic to Lower Mesozoic strata of the southeastern Algerian Tassili are traditionally subdivided by regionally extensive unconformities such as the Pan African, Taconic, Caledonian, and Hercynian. Using outcrop data from southeastern Algeria, this classic approach is modified by reinterpreting the genesis of these unconformities and rock sequences. Five prominent sequences, defined within the Paleozoic and lower Mesozoic section, usually consist of a succession of lowstand, transgressive, and highstand system tracts separated by sequence boundaries or transgressive surfaces. The Pan-African, Taconic, Caledonian, and Hercynian unconformities are sequence boundaries. Important sequence boundaries also occur within the Ordovician and Silurian sections. These sequences correlate with subsurface data in the Illizi basin and provide a framework for renewed exploration in the subsurface of the Algerian Sahara, where more than 30 billion bbl of recoverable oil and oil equivalent have been generated and trapped.

  2. Photovoltaic systems sizing for Algeria

    SciTech Connect

    Arab, A.H.; Driss, B.A.; Amimeur, R.; Lorenzo, E.

    1995-02-01

    The purpose of this work is to develop an optimization method applicable to stand-alone photovoltaic systems as a function of its reliability. For a given loss-of-load probability (LLP), there are many combinations of battery capacity and photovoltaic array peak power. The problem consists in determining the couple which corresponds to a minimum total system cost. The method has been applied to various areas all over Algeria taking into account various climatic zones. The parameter used to define the different climatic zones is the clearness index KT for all the considered sites. The period of the simulation system is 10 years. 5 refs., 4 figs., 5 tabs.

  3. Petroleum potential of the Reggane Basin, Algeria

    SciTech Connect

    Boudjema, A.; Hamel, M.; Mohamedi, A.; Lounissi, R. )

    1990-05-01

    The intracratonic Reggane basin is located on the Saharan platform, southwest of Algeria. The basin covers an area of approximately 140,000 km{sup 2}, extending between the Eglab shield in the south and the Ougarta ranges in the north. Although exploration started in the early 1950s, only a few wells were drilled in this basin. Gas was discovered with a number of oil shows. The sedimentary fill, mainly Paleozoic shales and sandstones, has a thickness exceeding 5,000 m in the central part of the basin. The reservoirs are Cambrian-Ordovician, Siegenian, Emsian, Tournaisian, and Visean sandstones with prospective petrophysical characteristics. Silurian Upper Devonian and, to a lesser extent Carboniferous shales are the main source rocks. An integrated study was done to assess the hydrocarbon potential of this basin. Tectonic evolution source rocks and reservoirs distribution maturation analyses followed by kinetic modeling, and hydrogeological conditions were studied. Results indicate that gas accumulations could be expected in the central and deeper part of the basin, and oil reservoirs could be discovered on the basin edge.

  4. Cerescope: Algeria Seeks Better Training in Agriculture.

    ERIC Educational Resources Information Center

    Ceres, 1979

    1979-01-01

    Recent changes and developments in Algeria's agricultural education program to meet the future needs for expertise at all levels in the rural sector are described. Training targets established in the national plan are detailed. (BT)

  5. Geology and hydrocarbon potential of the Oued Mya basin, Algeria

    SciTech Connect

    Benamrane, O.; Messaoudi, M.; Messelles, H. )

    1993-09-01

    The Oued Mya hydrocarbon system is located in the Sahara basin. It is one of the best producing basins in Algeria, along with the Ghadames and Illizi basins. The stratigraphic section consists of Paleozoic and Mesozoic, and is about 5000 m thick. This intracratonic basin is limited to the north by the Toughourt saddle, and to the west and east it is flanked by regional arches, Allal-Tilghemt and Amguid-Hassi Messaoud, which culminate in the super giant Hassi Messaoud and Hassi R'mel hydrocarbon accumulations, respectively, producing oil from the Cambrian sands and gas from the Trissic sands. The primary source rock in this basin is lower Silurian shale, with an average thickness of 50 m and a total organic carbon of 6% (14% in some cases). Results of maturation modeling indicate that the lower Silurian source is in the oil window. The Ordovician shales are also source rocks, but in a second order. Clastic reservoirs are in the Trissic sequence, which is mainly fluvial deposits with complex alluvial channels, and the main target in the basin. Clastic reservoirs in the lower Devonian section have a good hydrocarbon potential east of the basin through a southwest-northwest orientation. The Late Trissic-Early Jurassic evaporites that overlie the Triassic clastic interval and extend over the entire Oued Mya basin, are considered to be a super-seal evaporite package, which consists predominantly of anhydrite and halite. For paleozoic targets, a large number of potential seals exist within the stratigraphic column. This super seal does not present oil dismigration possibilities. We can infer that a large amount of the oil generated by the Silurian source rock from the beginning of Cretaceous until now still is not discovered and significantly greater volumes could be trapped within structure closures and mixed or stratigraphic traps related to the fluvial Triassic sandstones, marine Devonian sands, and Cambrian-Ordovician reservoirs.

  6. Greening of the Sahara - a paleo perspective on the history of water in the Middle East and North Africa

    NASA Astrophysics Data System (ADS)

    Bar-Matthews, M.

    2012-04-01

    The Middle-East, mostly at its southern edge together with North Africa, the northern edge of the Sahara Desert, are located at the boundary between high- to-mid latitude and tropical-subtropical climate systems. The geographical duality of desert adjacent to Mediterranean-type climate regions played and still plays a major role on the water availability. Thanks to the number of important paleoclimate studies that been made on accurate dating of cave speleothems in Southern Arabia and Oman (Fleitmann et al., 2011) and in the northeast Sahara, the Negev Desert Israel (Vaks et al., 2010) and the study of sapropels in Eastern and central Mediterranean (Almogi-Labin et al., 2009; Osborne et al, 2008), it is clear that the region was graced with water during peak interglacials when the African monsoon and westerly storm/rainfall systems intensified. Northward penetration of the Inter Tropical Convergence Zone over the Arabian and African continents resulted in increased discharge of the Nile River and rivers that emerged from central Sahara into the Eastern Mediterranean Sea. Correspondingly, enhanced westerly wind activity led to an increase in rainfall from Atlantic-Mediterranean sources over the entire Mediterranean basin, which even penetrated south into the north-east corner of the Sahara Desert. The Saharo-Arabian Desert became narrower and climatic "windows" opened for the dispersal of hominids and animals out of the African continent at 250-239, 210-193, 138-120, 108-98, 87-84 and 10-6.5 ka BP, with severe dry conditions in between. Greening of the Sahara Desert at these intervals is supported also by various marine and terrestrial records, such as corals, lakes, tufa deposits and archeological findings. Dry conditions prevailed in the Sahara desert during glacials. This is in contrast to the climatic conditions in the Eastern Mediterranean coastal region and the Jordan Rift Valley (Bar-Matthews et al., 2003; Lisker et al., 2010), where water was available for

  7. Dust aerosol emission over the Sahara during summertime from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations

    NASA Astrophysics Data System (ADS)

    Todd, Martin C.; Cavazos-Guerra, Carolina

    2016-03-01

    Dust aerosols are an important component of the climate system and a challenge to incorporate into weather and climate models. Information on the location and magnitude of dust emission remains a key information gap to inform model development. Inadequate surface observations ensure that satellite data remain the primary source of this information over extensive and remote desert regions. Here, we develop estimates of the relative magnitude of active dust emission over the Sahara desert based on data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Utilising the unique vertical profile of aerosol characteristics provided by CALIOP our algorithm identifies emission from aerosol extinction and lidar backscatter in the near surface layers. From the long-term CALIOP archive of day and night-time orbits over 2006-13 we construct coarse resolution maps of a new dust emission index (DEI) for the Sahara desert during the peak summer dust season (June to September). The spatial structure of DEI indicates highest emission over a broad zone focused on the border regions of Southern Algeria, Northern Mali and northwest Niger, displaced substantially (∼7°) to the east of the mean maximum in satellite-derived aerosol optical depth. In this region night-time emission exceeds that during the day. The DEI maps substantially corroborate recently derived dust source frequency count maps based on back-tracking plumes in high temporal resolution SEVIRI imagery. As such, a convergence of evidence from multiple satellite data sources using independent methods provides an increasingly robust picture of Saharan dust emission sources. Various caveats are considered. As such, quantitative estimates of dust emission may require a synergistic combined multi-sensor analysis.

  8. Drought in the Sahara - A biogeophysical feedback mechanism

    NASA Technical Reports Server (NTRS)

    Charney, J.; Stone, P. H.; Quirk, W. J.

    1975-01-01

    Two integrations of a global general circulation model, differing only in the prescribed surface albedo in the Sahara, show that an increase in albedo resulting from a decrease in plant cover causes a decrease in rainfall. Thus any tendency for plant cover to decrease would be reinforced by a decrease in rainfall, and could initiate or perpetuate a drought.

  9. Africa South of the Sahara: A Guide to Reference Sources.

    ERIC Educational Resources Information Center

    Mason, Mary, Comp.

    This annotated bibliography has been compiled as an introduction to reference resources for college-level African studies and to suggest useful tools for literature searches. It is a guide to materials in the library of McGill University. Call numbers are included. The titles cited refer to Africa South of the Sahara as a whole or to large…

  10. Cultural Astronomy in Africa South of the Sahara

    NASA Astrophysics Data System (ADS)

    Holbrook, Jarita

    This chapter examines two foci of cultural astronomy found in Africa south of the Sahara: creation myths and celestial art. The examples highlighted are from the Akan, the Bahima, the Boshongo, the Fon, the Igbo, the Mambila, the Yoruba, and the Zulu people.

  11. Biogeochemical inferences of mobility of early Holocene fisher-foragers from the Southern Sahara Desert.

    PubMed

    Stojanowski, Christopher M; Knudson, Kelly J

    2011-09-01

    North Africa is increasingly seen as an important context for understanding modern human evolution and reconstructing biocultural adaptations. The Sahara, in particular, witnessed a fluorescence of hunter-gatherer settlement at the onset of the Holocene after an extended occupational hiatus. Subsequent subsistence changes through the Holocene are contrary to those documented in other areas where mobile foraging gave way to settled agricultural village life. In North Africa, extractive fishing and hunting was supplanted by cattle and caprine pastoralism under deteriorating climatic conditions. Therefore, the initial stage of food production in North Africa witnessed a likely increase in mobility. However, there are few studies of paleomobility in Early Holocene hunter-gatherer Saharan populations and the degree of mobility is generally assumed. Here, we present radiogenic strontium isotope ratios from Early Holocene fisher-forager peoples from the site of Gobero, central Niger, southern Sahara Desert. Data indicate a relatively homogeneous radiogenic strontium isotope signature for this hunter-gather population with limited variability exhibited throughout the life course or among different individuals. Although the overall signature was local, some variation in the radiogenic strontium isotope data likely reflects transhumance into the nearby Aïr Massif. Data from Gobero were significantly less variable than in other worldwide hunter-gatherer populations, including those thought to be fairly sedentary. Strontium data from Gobero were also significantly different from contemporaneous sites in southwestern Libya. These patterns are discussed with respect to archaeological models of community organization and technological evolution. PMID:21766285

  12. Waulsortian-type buildups in the lower carboniferous of the Bechar basin, northwestern Sahara of Algeria, North Africa

    SciTech Connect

    Setra, A. )

    1994-03-01

    The carboniferous strata in the Bechar basin can be subdivided into three major groups. The lower group is composed of bioclastic and perireefal carbonates. The middle group is exemplified by carbonate platform deposits that were eroded during episodes of emergence by channels of continental derived sediments. The upper group is represented by terrigenous deposits composed mainly of deltaic, fluvial, and lacustrine deposits, with the sporadic presence of coal seams. The carboniferous Waulsortian-type buildups within the Bechar basin occur in the lower group. They are exposed above the desert floor along a south to north-northwest-trending axis, with the younger buildups located to the south and the older ones to the north. These bioherms are apparently younger than those recognized in Europe and North America. These Algerian bioherms were initiated and persisted during the time interval represented by the conodont gnathodus bilineatus zone (lower Visean-upper Visean boundary). Although they are younger than their European and North American counterparts that are of Tournaisian-lower Visean age, these mounds appear to have formed in similar environmental and tectono-sedimentary conditions. Their areal extent, geometry, and facies relationships suggest that they were limited to a shelf edge. Their deposition environments range from shallow marine to deep sea.

  13. Intraspecific variation in Schistosoma haematobium from Algeria.

    PubMed

    Kechemir, N; Théron, A

    1997-03-01

    A comparative analysis has been carried out between two populations of Schistosoma haematobium using the same intermediate snail host, Bulinus truncatus, but originating from two distinct ecological areas of Algeria: Khemis-El-Khechna in a sub-humid mediterranean zone and Djanet in a saharan bioclimatic zone. Four parameters have been studied: the growth rate of adult worms, size and shape of the eggs, chronobiology of cercarial emergence and the compatibility with the intermediate host. Results showing divergences for all the characters studied are discussed for the origin of this intraspecific polymorphism of S. haematobium in Algeria. PMID:9166441

  14. Animal Diseases Caused by Orbiviruses, Algeria

    PubMed Central

    Madani, Hafsa; Casal, Jordi; Alba, Anna; Allepuz, Alberto; Cêtre-Sossah, Catherine; Hafsi, Leila; Kount-Chareb, Houria; Bouayed-Chaouach, Nadera; Saadaoui, Hassiba

    2011-01-01

    Antibodies against bluetongue virus were detected in cattle, sheep, goats, and camels in Algeria in 2008. Antibodies against epizootic hemorrhagic disease virus were detected in cattle, but antibodies against African horse sickness virus were not detected in horses and mules. Epizootic hemorrhagic disease in northern Africa poses a major risk for the European Union. PMID:22172371

  15. Documentation and Development. Experience in Algeria

    ERIC Educational Resources Information Center

    Tchuigoua, J. Founou

    1972-01-01

    A description of the activities of the Documentation, Library and Archives Department of the Algiers Chamber of Commerce and Industry, which is run by a small staff on a modest budget, provides documentation services for the staff of the Chamber of Commerce and also assists other centers in Algeria. (Author)

  16. The qanat of Algerian Sahara: an evolutionary hydraulic system

    NASA Astrophysics Data System (ADS)

    Remini, Boualem; Achour, Bachir; Albergel, Jean

    2015-12-01

    This article discusses for the first time a study on the connection and interconnection of qanats located in the Algerian Sahara. During the missions in the oases of Touat and Gourara in 2009, 2010 and 2011, we have been impressed by the complexity of the network of water distribution. The seguias of differents sections take all the senses. Connections are made between qanats to ensure water supply to each owner. In this study, we identified nine models for connecting qanats.

  17. Fennec dust forecast intercomparison over the Sahara in June 2011

    NASA Astrophysics Data System (ADS)

    Chaboureau, Jean-Pierre; Flamant, Cyrille; Dauhut, Thibaut; Kocha, Cécile; Lafore, Jean-Philippe; Lavaysse, Chistophe; Marnas, Fabien; Mokhtari, Mohamed; Pelon, Jacques; Reinares Martínez, Irene; Schepanski, Kerstin; Tulet, Pierre

    2016-06-01

    In the framework of the Fennec international programme, a field campaign was conducted in June 2011 over the western Sahara. It led to the first observational data set ever obtained that documents the dynamics, thermodynamics and composition of the Saharan atmospheric boundary layer (SABL) under the influence of the heat low. In support to the aircraft operation, four dust forecasts were run daily at low and high resolutions with convection-parameterizing and convection-permitting models, respectively. The unique airborne and ground-based data sets allowed the first ever intercomparison of dust forecasts over the western Sahara. At monthly scale, large aerosol optical depths (AODs) were forecast over the Sahara, a feature observed by satellite retrievals but with different magnitudes. The AOD intensity was correctly predicted by the high-resolution models, while it was underestimated by the low-resolution models. This was partly because of the generation of strong near-surface wind associated with thunderstorm-related density currents that could only be reproduced by models representing convection explicitly. Such models yield emissions mainly in the afternoon that dominate the total emission over the western fringes of the Adrar des Iforas and the Aïr Mountains in the high-resolution forecasts. Over the western Sahara, where the harmattan contributes up to 80 % of dust emission, all the models were successful in forecasting the deep well-mixed SABL. Some of them, however, missed the large near-surface dust concentration generated by density currents and low-level winds. This feature, observed repeatedly by the airborne lidar, was partly forecast by one high-resolution model only.

  18. The Green Sahara: Climate Change, Hydrologic History and Human Occupation

    NASA Technical Reports Server (NTRS)

    Blom, Ronald G.; Farr, Tom G.; Feynmann, Joan; Ruzmaikin, Alexander; Paillou, Philippe

    2009-01-01

    Archaeology can provide insight into interactions of climate change and human activities in sensitive areas such as the Sahara, to the benefit of both disciplines. Such analyses can help set bounds on climate change projections, perhaps identify elements of tipping points, and provide constraints on models. The opportunity exists to more precisely constrain the relationship of natural solar and climate interactions, improving understanding of present and future anthropogenic forcing. We are beginning to explore the relationship of human occupation of the Sahara and long-term solar irradiance variations synergetic with changes in atmospheric-ocean circulation patterns. Archaeological and climate records for the last 12 K years are gaining adequate precision to make such comparisons possible. We employ a range of climate records taken over the globe (e.g. Antarctica, Greenland, Cariaco Basin, West African Ocean cores, records from caves) to identify the timing and spatial patterns affecting Saharan climate to compare with archaeological records. We see correlation in changing ocean temperature patterns approx. contemporaneous with drying of the Sahara approx. 6K years BP. The role of radar images and other remote sensing in this work includes providing a geographically comprehensive geomorphic overview of this key area. Such coverage is becoming available from the Japanese PALSAR radar system, which can guide field work to collect archaeological and climatic data to further constrain the climate change chronology and link to models. Our initial remote sensing efforts concentrate on the Gilf Kebir area of Egypt.

  19. The first true deserticolous species of Buthus Leach, 1815 from Algeria (Scorpiones: Buthidae); Ecological and biogeographic considerations.

    PubMed

    Sadine, Salah Eddine; Bissati, Samia; Lourenço, Wilson R

    2016-01-01

    Since the early 2000s, the genus Buthus Leach, 1815 (family Buthidae) has been the subject of an important number of studies. These concerned particularly the species belonging to the 'Buthus occitanus' complex. A number of populations previously considered as subspecies or varieties of B. occitanus Leach were raised to the rank of species, but also many new species have been described. Most of the species considered in these studies come from North Africa, in particular from Morocco, Mauritania, Chad, Sudan and Egypt, but only two new species were recorded from Algeria. At present, one more new species of Buthus is described from the Algerian Saharan Desert, raising the number of confirmed Buthus in Algeria to five. Since most Buthus species from North Africa, and in particular those from Algeria, inhabit more mesic environments than the Saharan Central compartment, the new species appears as the first true deserticolous species found in this country. PMID:26632450

  20. The Sahara Troposphere - Simultaneous Aircraft Observations from Fennec

    NASA Astrophysics Data System (ADS)

    Engelstaedter, Sebastian; Washington, Richard; Flamant, Cyrille; Allen, Chris J. T.

    2013-04-01

    The Saharan heat low (SHL) that develops over western Africa in Boreal summer has been recognised for its important role in the regional and continental scale climate system. It is co-located with the highest atmospheric dust loading and the deepest dry convective boundary layer in the world. As part of the Fennec 2011 Intensive Observation Period, two aircraft surveyed the SHL region in the morning and afternoon on 22 June 2011 along different tracks employing LIDAR instruments and dropsondes allowing the first characterisation of the structure and daytime evolution of atmospheric features in the central western Sahara including the SHL, the Saharan atmospheric boundary layer (SABL), the monsoon and atmospheric dust distributions within the system. The observations show a system that is more complex than previously thought. Characteristics include a) a NE-SW orientated SHL, b) a monsoon re-circulation around the SHL associated with dampened Convective Boundary Layer (CBL) growth and Saharan Residual Layer (SRL) top minimum, c) Harmattan winds associated with increased near-surface temperatures and enhanced CBL growth rate and CBL depth, d) near-surface inversions limiting CBL growth and vertical mixing of emitted dust, e) above SRL inversion strength linked to SRL top altitude, f) an aged dust layer close to the SABL top that shows a complex wave-like structure, and g) a potential tropospheric ventilation reducing SRL height and reducing dust concentration. The NE-SW elongated SHL is located over northern Mauritania close to the Mali border in the morning and moves west by about 0.5 to 1.0° in the afternoon corresponding well with the ERA-Interim reanalysis. The CBL depth ranges from 0.45 to 2.01 km above mean sea level (aMSL) in the morning and from 1.75 to 6.02 km in the afternoon. Low-level inversions in the morning between 0.5 and 0.9 km aMSL are strongest (up to 0.83°C) where the CBL is most shallow and weakening with increasing CBL depth. Above SRL

  1. Satellite measurement of mass of Sahara dust in the atmosphere

    NASA Technical Reports Server (NTRS)

    Fraser, R. S.

    1976-01-01

    Landsat 1 measurements of nadir radiance are used to obtain the mass of particulates in a vertical column of dust from the Sahara Desert. A radiative transfer model, constructed with knowledge of a few values of optical parameters measured from a ship, is developed to account for the measured radiance values. Measurement and model accuracies are discussed. It is found that the mass of particulates with smaller than a 10 micron radius in a vertical column is 1.6 g/sq m.

  2. Interaction between the North-West Sahara Aquifer and the seismically active intraplate Hun Graben Fault system, Libya

    NASA Astrophysics Data System (ADS)

    Hamling, I. J.; Aoudia, A.

    2011-12-01

    The North-West Sahara Aquifer System (NWSAS) covers an area of ~1 million km2 spanning the countries of Algeria, Tunisia and Libya. The system is composed of two main aquifers, the Complexe Terminal (CT) and the deeper Continental Intercalaire (CI). Over the last ~40 years these aquifers have been increasingly exploited in order to provide water to these countries. There are estimated to be ~7000 drill sites across the aquifer, 4000 in Algeria, 2000 in Tunisia and a further ~1000 in Libya. Land subsidence, caused by anthropogenic activities such as groundwater pumping, is a global problem and has been observed in a number of places around the world. Here we investigate fault controlled subsidence related to the extraction of water in North Western Libya. Located ~600 km south east of Tripoli, the Hun Graben separates the Sirte Basin to the east from the Hamada al Hamra Platform to the west and lies on the eastern boundary of the North-West Sahara Aquifer System (NWSAS). The graben is composed of two border faults extending for ~130 km from the town of Hun to the north west. These faults, bounding the eastern and western margins of the graben, are known to be seismically active and were responsible for the magnitude 7.1 earthquake in 1935. Due to the lack of ground based instrumentation, there are currently no estimates of slip along these structures. Here we use ERS and Envisat SAR images acquired over the last 20 years and form a number of interferograms to study interseismic strain accumulation along these structures. Satellite Radar Interferometry (InSAR) is a widely used technique for monitoring deformation of the Earth's surface. By differencing the phase from two radar images acquired at different times, maps of range change between the radar and ground can be obtained with millimetre precision. Our analysis over the graben suggests that neither of the two border faults are actively deforming and therefore the causes of intraplate large earthquakes such as

  3. Eastern Sahara Geology from Orbital Radar: Potential Analog to Mars

    NASA Technical Reports Server (NTRS)

    Farr, T. G.; Paillou, P.; Heggy, E.

    2004-01-01

    Much of the surface of Mars has been intensely reworked by aeolian processes and key evidence about the history of the Martian environment seems to be hidden beneath a widespread layer of debris (paleo lakes and rivers, faults, impact craters). In the same way, the recent geological and hydrological history of the eastern Sahara is still mainly hidden under large regions of wind-blown sand which represent a possible terrestrial analog to Mars. The subsurface geology there is generally invisible to optical remote sensing techniques, but radar images obtained from the Shuttle Imaging Radar (SIR) missions were able to penetrate the superficial sand layer to reveal parts of paleohydrological networks in southern Egypt.

  4. An integrated remote sensing and GIS analysis of the Kufrah Paleoriver, Eastern Sahara

    NASA Astrophysics Data System (ADS)

    Ghoneim, Eman; Benedetti, Michael; El-Baz, Farouk

    2012-02-01

    A combined remote sensing (optical and radar imagery) and GIS (hydrologic network delineation) analysis allows mapping of the Kufrah Paleoriver of Libya and sheds light on its geomorphic evolution during the Neogene. The Kufrah system, which is now largely buried beneath the windblown sands of the Eastern Sahara, drained an area of about 236,000 km 2 in central and southern Libya. The river discharged across a large inland delta to the Al-Jaghbub depression in northern Libya, and ultimately through the Sirt Basin to the Mediterranean Sea. Radar imagery reveals buried features of the landscape including drainage divides, locations of possible stream capture, deeply-incised valleys, and the distal margins of the inland delta. Previous studies have shown that the Kufrah Paleoriver is the successor of the Sahabi River, which drained most of central Libya during the late Tertiary. Satellite imagery supports the concept of large-scale drainage rearrangement in the Quaternary, driven by tectonic subsidence that diverted streamflow and sediment discharge away from the Sahabi basin toward the inland delta of the lower Kufrah basin. Paleochannels crossing the delta suggest that at various times during the Quaternary, the Kufrah Paleoriver either drained externally through the deeply-incised Sahabi Paleochannel to the Mediterranean Sea, or drained internally to paleolakes in the Al-Jaghbub depression. Thick alluvial deposits on the delta and lake margins likely provided a major sediment source to build the Great Sand Sea, which covers the region today. The southwestern branch of the Kufrah drainage is aligned with an elongated trough that connects to the Amatinga River system in Chad. Thus the Kufrah watershed may have served as an outlet from Megalake Chad to the Mediterranean Sea during humid phases of the Neogene. If so, the combined Amatinga/Kufrah system may have served as one of the proposed natural corridors used by human and animal populations to cross the Sahara

  5. Subsidence history in basins of northern Algeria

    NASA Astrophysics Data System (ADS)

    Bracene, Rabah; Patriat, Martin; Ellouz, Nadine; Gaulier, Jean-Michel

    2003-02-01

    The Tellian foreland in Algeria represents a part of the southern Tethyan margin during the Mesozoic. Its tectonic evolution includes a rifting stage during the Triassic and Liassic times characterised by tilted blocks and early diapiric events during the Liassic, a post-rift regime from Middle Jurassic up to the Late Cretaceous and basin inversion during the Tertiary related to the African and European plates convergence. The subsidence modelling supported by surface and subsurface data integration emphasises different subsidence phases. Liassic subsidence phase under Tethyan and Atlantic control related to crustal thinning. Late Jurassic, Cretaceous and Tertiary subsidence phases, where the first one is linked to diapiric events and the second in eastern Algeria to the effects of the rifting event developed more easterly in the Gulf of Gabès and Sirte. The last one is flexural and occurs in foreland basins during the Tertiary. Taking into account the subsidence record of each structural domain, a correlation between tectonic events and the subsidence phases can be established.

  6. Surviving in Mountain Climate Refugia: New Insights from the Genetic Diversity and Structure of the Relict Shrub Myrtus nivellei (Myrtaceae) in the Sahara Desert

    PubMed Central

    Migliore, Jérémy; Baumel, Alex; Juin, Marianick; Fady, Bruno; Roig, Anne; Duong, Nathalie; Médail, Frédéric

    2013-01-01

    The identification of past glacial refugia has become a key topic for conservation under environmental change, since they contribute importantly to shaping current patterns of biodiversity. However, little attention has been paid so far to interglacial refugia despite their key role for the survival of relict species currently occurring in climate refugia. Here, we focus on the genetic consequences of range contraction on the relict populations of the evergreen shrub Myrtus nivellei, endemic in the Saharan mountains since at least the end of the last Green Sahara period, around 5.5 ka B.P. Multilocus genotypes (nuclear microsatellites and AFLP) were obtained from 215 individuals collected from 23 wadis (temporary rivers) in the three main mountain ranges in southern Algeria (the Hoggar, Tassili n’Ajjer and Tassili n’Immidir ranges). Identical genotypes were found in several plants growing far apart within the same wadis, a pattern taken as evidence of clonality. Multivariate analyses and Bayesian clustering revealed that genetic diversity was mainly structured among the mountain ranges, while low isolation by distance was observed within each mountain range. The range contraction induced by the last episode of aridification has likely increased the genetic isolation of the populations of M. nivellei, without greatly affecting the genetic diversity of the species as a whole. The pattern of genetic diversity observed here suggests that high connectivity may have prevailed during humid periods, which is consistent with recent paleoenvironmental reconstructions. PMID:24058489

  7. Alternate non-stop migration strategies of pied flycatchers to cross the Sahara desert.

    PubMed

    Ouwehand, Janne; Both, Christiaan

    2016-04-01

    Each year more than two billion songbirds cross the Sahara, but how they perform this formidable task is largely unknown. Using geolocation tracks from 27 pied flycatchers, a nocturnally migrating passerine, we show that most birds made diurnal flights in both autumn and spring. These diurnal flights were estimated to be part of non-stop flights of mostly 40-60 h. In spring, birds flew across the Sahara, while autumn migration probably circumpassed part of the desert, through a long oversea flight. Our data contradict claims that passerines cross the Sahara by intermittent flight and daytime resting. The frequent occurrence of long non-stop flights to cross the desert shows migrants' physiological abilities and poses the question why this would not be the general migration strategy to cross the Sahara. PMID:27072404

  8. The Palaeoclimate of Wadi Shati, Libyan Sahara: the last 130 ka

    NASA Astrophysics Data System (ADS)

    Drake, Nick A.; Lem, Rachel E.; Armitage, Simon J.; White, Kevin H.; El-Hawat, Ahmed; Salem, Mustafa J.; Hounslow, Mark; Franke, Jan

    2014-05-01

    The Fezzan region of Libya forms a large closed basin that contains a wealth of ancient palaeolake and riverine sediments indicative of past humidity in the central Sahara. We have used remote sensing, DEM analysis and Ultra Ground Penetrating Radar to map these features and have dated them using OSL and radiocarbon methods. Results suggest humid conditions during both MIS 5 and the Holocene with larger lakes and more extensive river systems being present during MIS 5 suggestive of greater humidity at this time. A 4m core was collected from Holocene sediments of the largest lake found in the region (1200 km2 during MIS5 and 660 km2 during the Holocene). Core sediments were dated using OSL and analysed using XRF, Ion Chromatography, Laser Granulometry and chemical extractions for ostracods, diatoms, pollen and phytoliths. The base of the core is dominated by clays deposited in a perennial lake environment from 7.75 ka to 6.6 ka. Gypsum deposition started at about 6.5 ka indicating a more arid environment. Four clay layers are found amongst the gypsum from 6.3 to 6.25 ka, 6.2 to 6.1, 6.0 to 5.8 and 5.7-5.6 ka suggests that aridification was not a sudden event, but consisted of a series of arid/humid oscillations before the lake finally desiccated just before 5 ka. No pollen, diatoms or ostracods are preserved in the sediments but phytoliths were present. Both tree and grass phytoliths were found in lower parts of the core, suggesting a wooded savannah environment from 7.75 to about 7 ka. Trees decline and grass increases up the core, signifying an increasingly arid environment. By the time the first gypsum bed is deposited at about 6.5 ka trees have disappeared and grass dominates. These results do not support the hypothesis of a sudden aridification of the Sahara at 4.9 ka and instead suggest that in the Fezzan region a gradual aridification had started by 7.75 ka and that the climate oscillated during the lake desiccation that started at 6.5 ka and was complete by

  9. A Unique Type 4 Chondrite from the Sahara-Acfer 217

    NASA Astrophysics Data System (ADS)

    Bland, P.; Hutchison, R.; Pillinger, C. T.; Bischoff, A.

    1992-07-01

    In 1991 a single stone weighing 174 g was recovered from the Sahara desert, Algeria (27 degrees 36'N, 3 degrees 53'E). From this a 36.83-g fragment was obtained that has 2 sawn surfaces and adjacent surface of partially weathered fusion crust. The sawn surface shows "brownish" weathering products that have generally produced alteration of the matrix in which a few relict chondrules and inclusions are set. One 4 by 5 mm triangular area bordering the fusion crust is dark grey in colour with small inclusions set in it. This may be an area of local shock melt glass. Mineralogy and petrography: In a polished thin section, area 20 mm^2, we found few chondrules, mainly olivine clasts in a weathered olivine-rich matrix, with minor pyroxene. The largest relict chondrule was type "I" (McSween, 1977) with a diameter of 350 micrometers; a 200-micrometer-diameter type "II" (McSween, 1977) barred olivine chondrule showed devitrified glass in the interstices of the olivine. The sample is highly brecciated with fractures cutting the section and offsetting chondrule fragments, but in PTS is only very weakly shocked: olivine shows occasional undulatory extinction, i.e., stage "S2" in the classification of Stoffler et al. (1991). Mineral Chemistry: 95% of olivine is close to Fa(sub)39 but a few grains lie in the range Fa(sub)17 to Fa(sub)43 and one is zoned from a Fa(sub)17 core to a Fa(sub)43 rim. The majority of pyroxene is Ca-rich at a mean composition of Fs(sub)21 Wo(sub)45. Low-Ca pyroxene is also unequilibrated with a mean close to Fs(sub)31 and one has a composition of Fs(sub)10 Wo(sub)2. Plagioclase is a common interstitial phase in the matrix and is variable in composition, but high-Na oligoclase or albite. Minor opaque phases are dominated by Cr-rich (32-38 wt% Cr2O3) spinel, which also contains significant Ti (5.3 wt% TiO2). For charge balance substantial Fe^3+ is required indicating that Fe is partitioned between approximately 13-21 wt% Fe2O3 and 35 wt% FeO. The spinel

  10. Prevalence of equine viral arteritis in Algeria.

    PubMed

    Laabassi, F; Amelot, G; Laugier, C; Zientara, S; Nasri, A M; Hans, A

    2014-12-01

    In order to determine the prevalence of equine viral arteritis in Algeria, 268 sera from non-vaccinated horses were collected from the western and eastern regions. Serological analysis of the sera, which were collected from 2009 to 2011, was performed using the virus neutralisation test, as described by the World Organisation for Animal Health. Overall, 20 sera (7.46%) were seropositive, 152 (56.71%) were negative and 96 sera (35.82%) were cytotoxic. Equine arteritis virus (EAV) seroprevalence was significantly higher in the western region (Tiaret) than in the eastern region (Barika and El-Eulma). Interestingly, more than 20% of the tested horses over 16 years old were seropositive for EAV. However, EAV prevalence did not depend on either horse breed or horse gender. This study is the first to describe the circulation of EAV in the Algerian horse population. PMID:25812220

  11. Hepatitis C virus genotypes in north eastern Algeria: A retrospective study

    PubMed Central

    Rouabhia, Samir; Sadelaoud, Mourad; Chaabna-Mokrane, Karima; Toumi, Wided; Abenavoli, Ludovico

    2013-01-01

    AIM: To determine the frequency of various hepatitis C virus (HCV) genotypes present in patients from north eastern Algeria. METHODS: This is a retrospective cross-sectional study of 435 HCV infected patients from northeast Algeria, detected in the Sadelaoud laboratory and diagnosed between January 2010 and December 2012. The patients were diagnosed with HCV infection in their local hospitals and referred to be assessed for HCV genotype before the antiviral treatment. Demographic information (sex, age and address), genotype, subtype and viral load were retrieved from the patient medical records. The serum samples were tested by the type-specific genotyping assay. RESULTS: The majority of the patients (82.5%) were from the central part of the examined region (P = 0.002). The mean age of the patients studied was 53.6 ± 11.5 years. HCV genotype 1 was the most frequent (88.7%), followed by genotypes 2 (8.5%), 4 (1.1%), 3 (0.9%) and 5 (0.2%). Genotype 6 was not detected in these patients. Mixed infection across the HCV subtypes was detected in twenty patients (4.6%). The genotype distribution was related to age and region. Genotype 1 was significantly less frequent in the ≥ 60 age group than in the younger age group (OR = 0.2; 95%CI: 0.1-0.5, P < 0.001). Furthermore, genotype 1 was more frequent in the central part of the examined region than elsewhere (P < 0.01). CONCLUSION: The HCV genotype (type 1b was dominant) distribution in Algeria is different from those in other northern countries of Africa. PMID:23898373

  12. Paired Renazzo-type (CR) carbonaceous chondrites from the Sahara

    NASA Astrophysics Data System (ADS)

    Bischoff, A.; Palme, H.; Ash, R. D.; Clayton, R. N.; Schultz, L.; Herpers, U.; Stoffler, D.; Grady, M. M.; Pillinger, C. T.; Spettel, B.; Weber, H.; Grund, T.; Endress, M.; Weber, D.

    1993-04-01

    Data on the chemical composition, mineralogy, abundance, and isotopic composition of recently found Sahara meteorites are presented. The nine Acfer samples and the El Djouf 001 meteorite are considered to belong to the same parent meteoroid and are classified as a CR chondrite. The Acfer-El Djouf meteorite has a CI-chondritic composition of nonvolatile elements, in particular CI ratios of refractory elements to Mg. The presence of metal with chondritic Fe/Ni ratios, olivine with relatively low FeO contents and with high Cr is attributed to the primitive, unequilibrated nature of Acfer-El Djouf and other CR chondrites. The carbon and nitrogen stable isotropic composition of the Acfer-El Djouf chondrite lies within the range of other members of the CR group. Rare gases of the Acfer-El Djouf meteorite contain a comparatively large solar wind component, in excess of that in Renazzo. The cosmic-ray exposure age of the Acfer-El Djouf meteorite is about 6 million years.

  13. The demographic response to Holocene climate change in the Sahara

    NASA Astrophysics Data System (ADS)

    Manning, Katie; Timpson, Adrian

    2014-10-01

    The timing and development of Holocene human occupation in the now hyperarid Sahara has major implications for understanding links between climate change, demography and cultural adaptation. Here we use summed probability distributions from 3287 calibrated 14C dates from 1011 archaeological sites to demonstrate a major and rapid demographic shift between 10,500 and 5500 years BP. This event corresponds with the African Humid Period (AHP) and is sub-continental in scale, indicating climate as the prime factor driving broad-scale population dynamics in northern Africa. Furthermore, by providing a high temporal resolution proxy for effective carrying capacity our population curve offers an independent estimate of environmental change in northern Africa, indicating a temporal delay in the terrestrial response to atmospheric climate change. These results highlight the degree to which human demography is a function of environment at the appropriate scale of observation in both time and space and sheds important new light on the social response to global environmental change.

  14. First report of natural infection in hedgehogs with Leishmania major, a possible reservoir of zoonotic cutaneous leishmaniasis in Algeria.

    PubMed

    Tomás-Pérez, Míriam; Khaldi, Mourad; Riera, Cristina; Mozo-León, Denis; Ribas, Alexis; Hide, Mallorie; Barech, Ghania; Benyettou, Meryam; Seghiri, Kamel; Doudou, Souad; Fisa, Roser

    2014-07-01

    We report here the first known cases of natural infection of hedgehogs with Leishmania major. Cutaneous leishmaniasis is an important public health problem in the area of M'sila, a semi-arid province in Algeria's northern Sahara, where two species of hedgehog live, Atelerix algirus and Paraechinus aethiopicus. The aim of this research was to survey Leishmania infection in these hedgehogs and evaluate whether they were reservoir hosts of Leishmania in an endemic zoonotic focus of leishmaniasis. Serological and molecular methods were used to determine the presence of Leishmania in 24 hedgehogs caught directly by hand and identified at species level as 19 A. algirus and 5 P. aethiopicus. Specific anti-Leishmania antibodies were detected in 29.2% of individuals by Western blot and in 26.3% by ELISA. The real-time PCR performed in spleen, ear and blood samples detected Leishmania spp. DNA in 12.5% of the individuals, one A. algirus and two P. aethiopicus. Three skin and two spleen samples of these animals were found to be parasitized and were identified by molecular test as L. major. Considering our results, it is suggested that hedgehogs have a potential epidemiological role as reservoir hosts of L. major. PMID:24699087

  15. Bloc tectonic rotations recorded in the Neogene and Quaternary magmatic rocks from Northwestern Algeria: preliminary paleomagnetic results.

    NASA Astrophysics Data System (ADS)

    El Messaoud Derder, Mohamed; Robion, Philippe; Maouche, Said; Bayou, Boualem; Amenna, Mohamed; Henry, Bernard; Missenard, Yves; Ouabadi, Aziouz; Bestandji, Rafik; Ayache, Mohamed

    2016-04-01

    The seismic activity of the Western Mediterranean area is partly concentrated in northern Africa, particularly in northern Algeria, as it was shown by the strong earthquakes of Zemmouri 21 May 2003 Mw=6.9 and the El Asnam 10 October 1980 Ms= 7.3. This seismicity is due to the convergence between Africa and Eurasia plates since the Oligocene. This convergence involves a tectonic transpression with N-S to NNW-SSE shortening direction, which is expressed by active deformation along the plate boundary. Along the Tellian Atlas (Northern Algeria), active structures define NE-SW trending folds and NE-SW sinistral transpressive faults affecting the intermountain and coastal Neogene to Quaternary sedimentary basins (e.g. Cheliff and Mitidja Plioquaternary intramontaneous basins, …). The NE-SW reverse active faults are coupled with NW-SE to E-W trending strike-slip deep faults. The active deformation in northern Algeria can be explained by a kinematics model of blocks rotation: the transpressive tectonics with NNW-SSE direction of convergence defines NE-SW oriented blocks, which have been subjected to clockwise rotation. In north Algeria, paleomagnetic studies were carried out in the central area, on Neogene sedimentary and magmatic formations (Derder et al, 2009, 2011; 2013). They pointed out tectonic rotation of large blocks, in agreement with the kinematic model. Narrow zones represent important shear zone with strong rotation of smaller blocks (Derder et al., 2013). A new paleomagnetic study was conducted on the recent magmatic rocks outcropping in the Northwestern Algeria, in order to validate this model on a regional scale. The study is still in progress and the preliminary results show presence of systematic clockwise blocks rotation. These results confirm that the Africa-Europe convergence is partly accommodated in northern Africa by blocks rotations. They highlight that rotations are not homogeneous in north Algeria and thus the importance of future works in this

  16. [Urolithiasis in children in West Algeria].

    PubMed

    Harrache, D; Mesri, A; Addou, A; Semmoud, A; Lacour, B; Daudon, M

    1997-01-01

    We analyzed a series of 61 stones from children aged 3 to 14 years old using Fourier transform infrared spectroscopy. The calculi were collected from urology departments of the University Hospitals of Oran, Sidi-Bel-Abbès and Mostaganem in West Algeria. This series is the first investigation concerning the composition of stones in children based on infrared analysis. Calculi were more frequent in males (75.4%) and mainly localized in the bladder (55.8%). Upper urinary tract calculi were more frequent in children over the age of 10 years, and the sex ratio was about 1. Calcium oxalate monohydrate was present in 70.5% of stones and was the main component in 50.8% of cases both in whole stones and nuclei. In contrast, calcium oxalate dihydrate was the main component in only 9.8% of calculi although it was present in 75.4% of stones. Ammonium urate was detected in 29.5% of stones and was always the main component of nuclei. Uric acid, observed in 31.1% of calculi, was the major constituent in 14.7% of stones and 19.7% of nuclei. Magnesium ammonium phosphate was observed in 24.6% of stones as a consequence of urinary tract infection by urea-splitting bacteria. Our observations emphasized that the anatomical location of stone and their composition were in accordance with those previously reported in other countries. PMID:9245253

  17. [Factitious lithiasis: Case report from Western Algeria].

    PubMed

    Chettouh-Harrache, Djamila; Amar, A; Taleb, S; Bouhacina, N; Auberthie, R

    2004-01-01

    A 19-year-old woman with recurrent lithiasis was admitted to the urology department for renal colic. Although radiologic examinations and laboratory tests were negative, the patient regularly brought into consultations small "stones", resembling gravel, that she said had been spontaneously expelled. These 42 samples were the object of a preliminary morphological analysis under a binocular magnifier to detect their particulate components. A non-metabolic origin was suspected from the organoleptic characteristics of their surfaces and sections. In view of the diversity of the materials of these apparently false calculi, methods of precise physical analysis were necessary to ascertain their exact origin and thereby confirm the diagnosis of factitious lithiasis. The use of two methods of physical analysis, infrared spectrophotometry and x-ray diffraction, enabled us to determine their exact chemical and mineralogical composition. The samples claimed to be of urinary origin actually consisted of exogenous products of various compositions. Some samples were made of pure calcite, others of mixed calcite and silicates. Moreover several samples of the patient's first morning urine showed no correlation between the nature of the crystalluria and the composition of these stones. These tests made it possible to direct the clinician towards useful complementary investigations. This strange case represents 0.1% of the urinary calculi analysed in Western Algeria. PMID:15745877

  18. Active sand dunes are largest dust source in the Sahara Desert

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-09-01

    Dried up lakebeds and playas in the Sahara Desert of North Africa are large sources of dust in the atmosphere. The Bodélé Depression at the southern edge of the Sahara Desert, for example, is the single largest source of dust in the world; on average, 100 dust storms a year originate from the Bodélé Depression. A new study by Crouvi et al., however, finds that active sand dunes could be even bigger sources of desert dust in the atmosphere. Atmospheric dust plays active roles in climate and biological processes in the ocean: It regulates heating at the surface of the Earth; modifies cloud properties that affect rainfall; and acts as the only source of iron, a critical nutrient for microorganisms in the ocean. Little is known about types of dust sources in the Sahara Desert, which alone accounts for more than 50% of the dust in the atmosphere.

  19. African humid periods triggered the reactivation of a large river system in Western Sahara

    PubMed Central

    Skonieczny, C.; Paillou, P.; Bory, A.; Bayon, G.; Biscara, L.; Crosta, X.; Eynaud, F.; Malaizé, B.; Revel, M.; Aleman, N.; Barusseau, J. -P.; Vernet, R.; Lopez, S.; Grousset, F.

    2015-01-01

    The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver during past humid periods contributed to the delivery of sediments to the Tropical Atlantic margin. This finding provides new insights for the interpretation of terrigenous sediment records off Western Africa, with important implications for our understanding of the paleohydrological history of the Sahara. PMID:26556052

  20. African humid periods triggered the reactivation of a large river system in Western Sahara.

    PubMed

    Skonieczny, C; Paillou, P; Bory, A; Bayon, G; Biscara, L; Crosta, X; Eynaud, F; Malaizé, B; Revel, M; Aleman, N; Barusseau, J-P; Vernet, R; Lopez, S; Grousset, F

    2015-01-01

    The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver during past humid periods contributed to the delivery of sediments to the Tropical Atlantic margin. This finding provides new insights for the interpretation of terrigenous sediment records off Western Africa, with important implications for our understanding of the paleohydrological history of the Sahara. PMID:26556052

  1. Economic development, mobility and traffic accidents in Algeria.

    PubMed

    Bougueroua, M; Carnis, L

    2016-07-01

    The aim of this contribution is to estimate the impact of road economic conditions and mobility on traffic accidents for the case of Algeria. Using the cointegration approach and vector error correction model (VECM), we will examine simultaneously short term and long-term impacts between the number of traffic accidents, fuel consumption and gross domestic product (GDP) per capital, over the period 1970-2013. The main results of the estimation show that the number of traffic accidents in Algeria is positively influenced by the GDP per capita in the short and long term. It implies that a higher economic development worsens the road safety situation. However, the new traffic rules adopted in 2009 have an impact on the forecast trend of traffic accidents, meaning efficient public policy could improve the situation. This result calls for a strong political commitment with effective countermeasures for avoiding the further deterioration of road safety record in Algeria. PMID:27070081

  2. Ancient watercourses and biogeography of the Sahara explain the peopling of the desert

    PubMed Central

    Drake, Nick A.; Blench, Roger M.; Armitage, Simon J.; Bristow, Charlie S.; White, Kevin H.

    2011-01-01

    Evidence increasingly suggests that sub-Saharan Africa is at the center of human evolution and understanding routes of dispersal “out of Africa” is thus becoming increasingly important. The Sahara Desert is considered by many to be an obstacle to these dispersals and a Nile corridor route has been proposed to cross it. Here we provide evidence that the Sahara was not an effective barrier and indicate how both animals and humans populated it during past humid phases. Analysis of the zoogeography of the Sahara shows that more animals crossed via this route than used the Nile corridor. Furthermore, many of these species are aquatic. This dispersal was possible because during the Holocene humid period the region contained a series of linked lakes, rivers, and inland deltas comprising a large interlinked waterway, channeling water and animals into and across the Sahara, thus facilitating these dispersals. This system was last active in the early Holocene when many species appear to have occupied the entire Sahara. However, species that require deep water did not reach northern regions because of weak hydrological connections. Human dispersals were influenced by this distribution; Nilo-Saharan speakers hunting aquatic fauna with barbed bone points occupied the southern Sahara, while people hunting Savannah fauna with the bow and arrow spread southward. The dating of lacustrine sediments show that the “green Sahara” also existed during the last interglacial (∼125 ka) and provided green corridors that could have formed dispersal routes at a likely time for the migration of modern humans out of Africa. PMID:21187416

  3. Teaching About Africa South of the Sahara; A Guide and Resource Packet for Ninth Grade Social Studies.

    ERIC Educational Resources Information Center

    Coburn, Barbara; And Others

    This guide provides a sampling of reference materials which are pertinent for two ninth grade units: Africa South of the Sahara: Land and People, and Africa South of the Sahara: Historic Trends. The effect of urbanization upon traditional tribalistic cultures is the focus. A case study is used to encourage an inductive approach to the learning…

  4. Expansion and contraction of the sahara desert from 1980 to 1990.

    PubMed

    Tucker, C J; Dregne, H E; Newcomb, W W

    1991-07-19

    Data from polar-orbiting meteorological satellites have been used to determine the extent of the Sahara Desert and to document its interannual variation from 1980 to 1990. The Sahara Desert ranged from 8,633,000 square kilometers in 1980 to 9,982,000 square kilometers in 1984. The greatest annual north-south latitudinal movement of the southern Saharan boundary was 110 kilometers from 1984 to 1985 and resulted in a decrease in desert area of 724,000 square kilometers. PMID:17794695

  5. Preliminary Examination of Sahara 99555: Mineralogy and Experimental Studies of a New Angrite

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; McKay, G.; Le, L.; Mittlefehldt, D. W.

    2000-01-01

    A 2710 g meteorite, Sahara 99555 (Sah99), was recently recovered from the Sahara and reported to be the 5th angrite. It is the largest angrite ever found and may offer useful information to better understand the unusual petrogeneses of this rare achondrite group. It may also allow us to examine the chronological record of igneous activity in the very early solar system. We obtained a 2.6 g chip of Sah99 and here present a preliminary report of its petrology and mineralogy in conjunction with a crystallization experiment on an analogue composition.

  6. Investigating the role of the land surface in explaining the interannual variation of the net radiation balance over the Western Sahara and sub-Sahara

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Nicholson, Sharon

    1987-01-01

    The status of the data sets is discussed. Progress was made in both data analysis and modeling areas. The atmospheric and land surface contributions to the net radiation budget over the Sahara-Sahel region is being decoupled. The interannual variability of these two processes was investigated and this variability related to seasonal rainfall fluctuations. A modified Barnes objective analysis scheme was developed which uses an eliptic scan pattern and a 3-pass iteration of the difference fields.

  7. Abdominal Burkitt-type lymphomas in Algeria.

    PubMed Central

    Ladjadj, Y.; Philip, T.; Lenoir, G. M.; Tazerout, F. Z.; Bendisari, K.; Boukheloua, R.; Biron, P.; Brunat-Mentigny, M.; Aboulola, M.

    1984-01-01

    In a previous retrospective analysis from the principal paediatric centres of Algeria, Burkitt-type lymphomas (BL) were shown to account for around 46.5% of the total childhood non-Hodgkin's malignant lymphomas in that country. In the present study, a series of 49 abdominal BL from the Paediatric Clinic of Surgery, Mustapha Hospital, Algiers, has been studied. The age distribution shows a peak between 4 and 5 years of age, and the sex ratio is (M:F) 2.26:1. The disease is characterized by a rapid evolution in the absence of therapy. The major problem is an explosive form of the disease, which at present seems difficult to control in this country. Fifteen of the 49 patients (30.6%) died before completion of the first course of chemotherapy; however, complete remission (CR) was obtained for 30 patients (61%). Overall survival was 42.85% (21/49), whereas survival of patients who reached CR is 70% (21/30). When CR was obtained, deaths were related to cerebrospinal fluid involvement, local recurrence, secondary bone marrow involvement or therapeutic accidents. All patients alive with no evidence of disease (NED) 8-months after CR can be considered definitively cured. Epstein-Barr virus (EBV) serology performed on 31 BL patients and on a control group of 25 children with other malignant tumours showed that most Algerian BL have elevated EBV titres. A search for viral markers within malignant cells in 17 patients indicated that 88% (15/17) of the BL cases were EBV-associated. Analysis of the immunological and cytogenetic data showed that, as in the rest of the world, these BL cases involve proliferation of B-cell-type lymphocytes, with characteristic cytogenetic translocations involving chromosome 8. This report represents the most detailed description so far of BL from an area in non-equatorial Africa and the first report of a large series from North Africa. PMID:6324843

  8. Pre-School Education in Morocco and Algeria

    ERIC Educational Resources Information Center

    Bouzoubaa, Khadija; Benghabrit-Remaoun, Nouria

    2004-01-01

    This article is an analysis of the current state of early childhood care in the Maghreb, in particular in Morocco and Algeria, where the pre-schooling rate for 5-year-olds is on the increase. Extending pre-school infrastructures and the need to create unified curricula have been among the most urgent questions to be tackled over the last decade in…

  9. What Do Mobiles Speak in Algeria? Evidence from SMS Language

    ERIC Educational Resources Information Center

    Mostari, Hind Amel

    2009-01-01

    When Algeria opened its markets to foreign investment starting from the early 2000s, a technological boom occurred, including the expansion of mobile phone use. New technologies have had a considerable impact on the Algerian diglossic situation, in recent decades, and have contributed in the democratisation of the local dialects, which are being…

  10. Hibiscus plant named `Sahara Sunset` U.S. Plant Patent 21,765

    Technology Transfer Automated Retrieval System (TEKTRAN)

    'Sahara Sunset' is a new and distinct cultivar of Hibiscus, botanically known as Hibiscus acetosella. The new Hibiscus was originated in Poplarville, Miss. and is a product of a mutation induction program. The parent of the present new cultivar is an unknown Hibiscus acetosella Wels. Ex Hiern seedli...

  11. Songbird migration across the Sahara: the non-stop hypothesis rejected!

    PubMed

    Schmaljohann, Heiko; Liechti, Felix; Bruderer, Bruno

    2007-03-01

    Billions of songbirds breeding in the Western Palaearctic cross the largest desert of the world, the Sahara, twice a year. While crossing Europe, the vast majority use an intermittent flight strategy, i.e. fly at night and rest or feed during the day. However, it was long assumed that they overcome the Sahara in a 40 h non-stop flight. In this study, we observed bird migration with radar in the plain sand desert of the Western Sahara (Mauritania) during autumn and spring migration and revealed a clear prevalence of intermittent migration. Massive departures of songbirds just after sunset independent of site and season suggests strongly that songbirds spent the day in the plain desert. Thus, most songbirds cross the Sahara predominantely by the intermittent flight strategy. Autumn migration took place mainly at low altitudes with high temperatures, its density decreased abruptly before sunrise, followed by very little daytime migration. Migration was highly restricted to night-time and matched perfectly the intermittent flight strategy. However, in spring, when migratory flights occurred at much higher altitudes than in autumn, in cool air, about 17% of the songbird migration occurred during the day. This suggests that flying in high temperatures and turbulent air, as is the case in autumn, may lead to an increase in water and/or energy loss and may prevent songbirds from prolonged flights into the day. PMID:17254999

  12. Application of the loss estimation tool QLARM in Algeria

    NASA Astrophysics Data System (ADS)

    Rosset, P.; Trendafiloski, G.; Yelles, K.; Semmane, F.; Wyss, M.

    2009-04-01

    During the last six years, WAPMERR has used Quakeloss for real-time loss estimation for more than 440 earthquakes worldwide. Loss reports, posted with an average delay of 30 minutes, include a map showing the average degree of damage in settlements near the epicenter, the total number of fatalities, the total number of injured, and a detailed list of casualties and damage rates in these settlements. After the M6.7 Boumerdes earthquake in 2003, we reported 1690-3660 fatalities. The official death toll was around 2270. Since the El Asnam earthquake, seismic events in Algeria have killed about 6,000 people, injured more than 20,000 and left more than 300,000 homeless. On average, one earthquake with the potential to kill people (M>5.4) happens every three years in Algeria. In the frame of a collaborative project between WAPMERR and CRAAG, we propose to calibrate our new loss estimation tool QLARM (qlarm.ethz.ch) and estimate human losses for future likely earthquakes in Algeria. The parameters needed for this calculation are the following. (1) Ground motion relation and soil amplification factors (2) distribution of building stock and population into vulnerability classes of the European Macroseismic Scale (EMS-98) as given in the PAGER database and (3) population by settlement. Considering the resolution of the available data, we construct 1) point city models for cases where only summary data for the city are available and, 2) discrete city models when data regarding city districts are available. Damage and losses are calculated using: (a) vulnerability models pertinent to EMS-98 vulnerability classes previously validated with the existing ones in Algeria (Tipaza and Chlef) (b) building collapse models pertinent to Algeria as given in the World Housing Encyclopedia and, (c) casualty matrices pertinent to EMS-98 vulnerability classes assembled from HAZUS casualty rates. As a first trial, we simulated the 2003 Boumerdes earthquake to check the validity of the proposed

  13. Lakeside Cemeteries in the Sahara: 5000 Years of Holocene Population and Environmental Change

    PubMed Central

    Sereno, Paul C.; Garcea, Elena A. A.; Jousse, Hélène; Stojanowski, Christopher M.; Saliège, Jean-François; Maga, Abdoulaye; Ide, Oumarou A.; Knudson, Kelly J.; Mercuri, Anna Maria; Stafford, Thomas W.; Kaye, Thomas G.; Giraudi, Carlo; N'siala, Isabella Massamba; Cocca, Enzo; Moots, Hannah M.; Dutheil, Didier B.; Stivers, Jeffrey P.

    2008-01-01

    Background Approximately two hundred human burials were discovered on the edge of a paleolake in Niger that provide a uniquely preserved record of human occupation in the Sahara during the Holocene (∼8000 B.C.E. to the present). Called Gobero, this suite of closely spaced sites chronicles the rapid pace of biosocial change in the southern Sahara in response to severe climatic fluctuation. Methodology/Principal Findings Two main occupational phases are identified that correspond with humid intervals in the early and mid-Holocene, based on 78 direct AMS radiocarbon dates on human remains, fauna and artifacts, as well as 9 OSL dates on paleodune sand. The older occupants have craniofacial dimensions that demonstrate similarities with mid-Holocene occupants of the southern Sahara and Late Pleistocene to early Holocene inhabitants of the Maghreb. Their hyperflexed burials compose the earliest cemetery in the Sahara dating to ∼7500 B.C.E. These early occupants abandon the area under arid conditions and, when humid conditions return ∼4600 B.C.E., are replaced by a more gracile people with elaborated grave goods including animal bone and ivory ornaments. Conclusions/Significance The principal significance of Gobero lies in its extraordinary human, faunal, and archaeological record, from which we conclude the following: The early Holocene occupants at Gobero (7700–6200 B.C.E.) were largely sedentary hunter-fisher-gatherers with lakeside funerary sites that include the earliest recorded cemetery in the Sahara.Principal components analysis of craniometric variables closely allies the early Holocene occupants at Gobero with a skeletally robust, trans-Saharan assemblage of Late Pleistocene to mid-Holocene human populations from the Maghreb and southern Sahara.Gobero was abandoned during a period of severe aridification possibly as long as one millennium (6200–5200 B.C.E).More gracile humans arrived in the mid-Holocene (5200–2500 B.C.E.) employing a diversified

  14. Unravelling biodiversity, evolution and threats to conservation in the Sahara-Sahel.

    PubMed

    Brito, José C; Godinho, Raquel; Martínez-Freiría, Fernando; Pleguezuelos, Juan M; Rebelo, Hugo; Santos, Xavier; Vale, Cândida G; Velo-Antón, Guillermo; Boratyński, Zbyszek; Carvalho, Sílvia B; Ferreira, Sónia; Gonçalves, Duarte V; Silva, Teresa L; Tarroso, Pedro; Campos, João C; Leite, João V; Nogueira, Joana; Alvares, Francisco; Sillero, Neftalí; Sow, Andack S; Fahd, Soumia; Crochet, Pierre-André; Carranza, Salvador

    2014-02-01

    Deserts and arid regions are generally perceived as bare and rather homogeneous areas of low diversity. The Sahara is the largest warm desert in the world and together with the arid Sahel displays high topographical and climatic heterogeneity, and has experienced recent and strong climatic oscillations that have greatly shifted biodiversity distribution and community composition. The large size, remoteness and long-term political instability of the Sahara-Sahel, have limited knowledge on its biodiversity. However, over the last decade, there have been an increasing number of published scientific studies based on modern geomatic and molecular tools, and broad sampling of taxa of these regions. This review tracks trends in knowledge about biodiversity patterns, processes and threats across the Sahara-Sahel, and anticipates needs for biodiversity research and conservation. Recent studies are changing completely the perception of regional biodiversity patterns. Instead of relatively low species diversity with distribution covering most of the region, studies now suggest a high rate of endemism and larger number of species, with much narrower and fragmented ranges, frequently limited to micro-hotspots of biodiversity. Molecular-based studies are also unravelling cryptic diversity associated with mountains, which together with recent distribution atlases, allows identifying integrative biogeographic patterns in biodiversity distribution. Mapping of multivariate environmental variation (at 1 km × 1 km resolution) of the region illustrates main biogeographical features of the Sahara-Sahel and supports recently hypothesised dispersal corridors and refugia. Micro-scale water-features present mostly in mountains have been associated with local biodiversity hotspots. However, the distribution of available data on vertebrates highlights current knowledge gaps that still apply to a large proportion of the Sahara-Sahel. Current research is providing insights into key

  15. First GNSS results in the Oran area (northwestern Algeria)

    NASA Astrophysics Data System (ADS)

    bougrine, amina; Nocquet, Jean-Mathieu; Yelles-Chaouche, Abdelkarim; Lammali, Kamel; Bacha, Wahab; Terki, Toufik

    2016-04-01

    Sparse results along northern Algeria are so far available to better understand how Nubia/Eurasia convergence is accommodated in the western Mediterranean and quantitatively assess seismic potential in that area. In this study, we show new GNSS results in the Tellian atlas in western Algeria. The studied area encompasses the Mleta basin bordered in the north by the Murdjadjo range, which is thought to be the locus of the large 1790 earthquake (estimated magnitude 7.5 Bouhadad, 2001). This area includes the city of Oran, the second most populated city of Algeria. The GNSS network includes 18 sites, spanning 180km East-West along the coast of Algeria and 40 km inland, with inter-site distance of 15 km. It has been observed in 2008, 2012 and 2013 for enabling velocity to be estimated at the 1 mm/yr. GNSS Data have been processed using GAMIT/GLOBK software, together with 04 permanent sites in Algeria and 87 IGS sites surrounding the area of study. Uncertainties on campaign results have been rescaled according to the analysis of the nearby CGPS time series. The recorded seismicity and the obtained GNSS velocity field from the three campaigns with a five years span, indicate that this region is tectonically active and subjected to significant horizontal motions. A regional NW displacement of 2-4mm/yr in the Eurasia stable reference frame is consistent with the expected Nubia-Eurasia motion. The obtained velocity field in the Nubian fixed reference frame gives a slow strain rate less than 2mm/yr representing the strain rate accommodated across the Murdjadjo range and the different features around the Mlena basin.

  16. Evidence that clade A and clade B head lice live in sympatry and recombine in Algeria.

    PubMed

    Boutellis, A; Bitam, I; Fekir, K; Mana, N; Raoult, D

    2015-03-01

    Pediculus humanus L. (Psocodea: Pediculidae) can be characterized into three deeply divergent lineages (clades) based on mitochondrial DNA. Clade A consists of both head lice and clothing lice and is distributed worldwide. Clade B consists of head lice only and is mainly found in North and Central America, and in western Europe and Australia. Clade C, which consists only of head lice, is found in Ethiopia, Nepal and Senegal. Twenty-six head lice collected from pupils at different elementary schools in two localities in Algiers (Algeria) were analysed using molecular methods for genotyping lice (cytochrome b and the multi-spacer typing (MST) method. For the first time, we found clade B head lice in Africa living in sympatry with clade A head lice. The phylogenetic analysis of the concatenated sequences of these populations of head lice showed that clade A and clade B head lice had recombined, suggesting that interbreeding occurs when lice live in sympatry. PMID:25346378

  17. Weathering of Ordinary Chondrites from Algeria and Australia as a Climatic Indicator

    NASA Astrophysics Data System (ADS)

    Bland, P. A.; Berry, F. J.; Pillinger, C. T.

    1995-09-01

    Introduction: Recently it has been recognized that ordinary chondrite meteorites resident in desert regions may preserve information about the climate at the time of their arrival on Earth in the degree to which they are weathered [1], providing that a stable surface has existed at the accumulation site. We present here a comparison of ^57Fe Mossbauer spectroscopy data for additional meteorites for which terrestrial ages exist, recovered from Reg el Acfer, Algeria and the Nullarbor Region, Australia. Results and Discussion: The data presented in Fig. 1 compare abundance of ferric iron oxide/oxyhydroxide species against terrestrial age [2, 3] for ordinary chondrites from Australia (a) and Algeria (b). Even with an increased dataset for Australian meteorites (compared to that already presented [1]) the initial hypothesis remains intact i.e. meteorite weathering over time is sensitive to changes in climate. Peaks in oxidation at around 2,000, 7,000 and 23,000 years correspond to periods of speleothem formation [4] and high lake level status [5]. Similarly, a period of low oxidation between 12,000-20,000 years is mirrored in low lake level status [5] and aridity in the Nullarbor [6]. The mechanism by which meteorites may record palaeoclimatic information is given in [1]. A correlation that strengthens our case is that where data from both H and L(LL) chondrites are available (i.e. around 7,000-8,000 years) the two plots are similar, indicating a broadscale environmental effect. In contrast, the distribution for meteorites from the Acfer region appears to be more random, with no correlation between H and L(LL) data. The difference may be related to the stability of the respective accumulation surfaces. The surface of the Nullarbor appears to have been stable over the last 30,000 years [7]. The Algerian and Libyan Sahara, however, has experienced several episodes of active fluvial processes over the last 10,000 years [8] which may have profoundly effected the meteorites

  18. Mineralogy of Carbonaceous Chondrites and ACFER 217 from the Sahara

    NASA Astrophysics Data System (ADS)

    Geiger, T.; Bischoff, A.

    1992-07-01

    Among the approximately 400 meteorites recovered in the past three years in the Sahara at least 19 carbonaceous chondrites exist. Ten paired samples belong to the CR- chondrite Acfer 059/El Djouf 001 which has been recently described (Bischoff et al., 1992a). Three samples (Acfer 182, 207, 214) represent a unique (carbonaceous) chondrite (Bischoff et al., 1992b) that has similarities to ALH 85085 (e.g. Scott, 1988). Here, we describe six unpaired carbonaceous chondrites and Acfer 217, an unusual chondritic breccia. Three chondrites probably belong to the CV- chondrites (Acfer 082, 086, 272) and two to the CO- chondrites (Acfer 202, 243). Acfer 094 has trace element characteristics of a CM-chondrite, but has oxygen isotope ratios different from CM-chondrites (Bischoff et al., 1991). CV-chondrites: Based on the petrography and mineral chemistry Acfer 082 and 086 are typical CV3 chondrites. Large coarse-grained CAIs (especially in Acfer 082), fine- grained spinel-rich and large olivine-rich aggregates, chondrules and fragments are embedded in a fine-grained groundmass mainly consisting of small Fe-rich olivine laths. In Acfer 082 and Acfer 086 the average compositions of matrix olivine are Fa 55 and Fa 40, respectively. Acfer 082 is quite fresh concerning the degree of weathering, whereas Acfer 086 is severely weathered as indicated by the occurrence of abundant calcite filling fractures and pores between the olivine laths of the matrix. Acfer 272 has a mineral chemistry similar to Acfer 082, but is in texture, trace element chemistry (Spettel et al., 1992), and oxygen isotopes (Mayeda and Clayton, pers. communication) different to Acfer 082. Acfer 272 has a densely compacted matrix without individual euhedral to subhedral olivine laths. CO-chondrites: Acfer 202 and 243 consist of abundant porphyritic chondrules, CAIs, olivine-rich inclusions, and fragments embedded in abundant fine-grained matrix. The main component of the matrix is Fe-rich olivine. Matrix olivines

  19. Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database

    NASA Astrophysics Data System (ADS)

    Laurent, B.; Marticorena, B.; Bergametti, G.; LéOn, J. F.; Mahowald, N. M.

    2008-07-01

    The present study investigates the mineral dust emissions and the occurrence of dust emission events over the Sahara desert from 1996 to 2001. Mineral dust emissions are simulated over a region extending from 16°N to 38°N and from 19°W to 40°E with a ?° × ?° spatial resolution. The input parameters required by the dust emission model are surface features data (aerodynamic roughness length, dry soil size distribution and texture for erodible soils), and meteorological surface data (mainly surface wind velocity and soil moisture). A map of the aerodynamic roughness lengths is established based on a composition of protrusion coefficients derived from the POLDER-1 surface products. Soil dry size distribution and texture are derived from measurements performed on soil samples from desert areas, and from a soil map derived from a geomorphologic analysis of desert landscapes. Surface re-analyzed meteorological databases (ERA-40) of the European Centre for Medium range Weather Forecasts (ECMWF) are used. The influence of soil moisture on simulated dust emissions is quantified. The main Saharan dust sources identified during the 6-year simulated period are in agreement with the previous studies based on in situ or satellite observations. The relevance of the simulated large dust sources and point sources ("hot spots") is tested using aerosol indexes derived from satellite observations (TOMS Absorbing Aerosol Index and Infrared Dust Difference Index Meteosat). The Saharan dust emissions simulated from 1996 to 2001 range from 585 to 759 Tg a-1. The simulations show marked seasonal cycles with a maximum in summer for the western Sahara and in spring for the eastern Sahara. The interannual variability of dust emissions is pronounced in the eastern part of the Sahara while the emissions from the western Sahara are more regular over the studied period. The soil moisture does not noticeably affect the Saharan dust emissions, their seasonal cycle or their interannual

  20. Equine cryptosporidial infection associated with Cryptosporidium hedgehog genotype in Algeria.

    PubMed

    Laatamna, Abd Elkarim; Wagnerová, Pavla; Sak, Bohumil; Květoňová, Dana; Aissi, Miriem; Rost, Michael; Kváč, Martin

    2013-10-18

    Faecal samples from two horse farms in Algeria keeping Arabian, Thoroughbred, and Barb horses were examined for the presence of Cryptosporidium in 2010-2011. A total of 138 faecal samples (16 from a farm keeping 50 animals and 122 from a farm with 267 horses) were screened for Cryptosporidium spp. infection using molecular tools. DNA was extracted from all samples. Nested PCR was performed to amplify fragments of the SSU rDNA and gp60 genes to determine the presence of Cryptosporidium species and genotypes. Sequence analyses of SSU and gp60 genes revealed four animals positive for the presence of subtype XIIIa A22R9 of the Cryptosporidium hedgehog genotype. The infections were not associated with diarrhoea. This study reports, for the first time, the occurrence of Cryptosporidium in Algeria and the first occurrence of the hedgehog genotype in horses. These findings support the potential role of infected horses in sylvatic-domestic transmission of Cryptosporidium. PMID:23731858

  1. Plague Reappearance in Algeria after 50 Years, 2003

    PubMed Central

    Bekhoucha, Souad; Chougrani, Saada; Razik, Fathia; Duchemin, Jean B.; Houti, Leila; Deharib, Larbi; Fayolle, Corinne; Makrerougrass, Banaouda; Dali-Yahia, Radia; Bellal, Ramdan; Belhabri, Leila; Chaieb, Amina; Tikhomirov, Evgueni; Carniel, Elisabeth

    2007-01-01

    An outbreak of plague occurred in the region of Oran, Algeria, from June to July 2003. Algeria had not reported this disease for >50 years. Eighteen bubonic cases were identified, and Yersinia pestis was isolated from 6 patients. Except for the index case-patient, all patients recovered. Targeted chemoprophylaxis, sanitation, and vector control played a crucial role in controlling the outbreak. Epidemiologic and biomolecular findings strongly suggested the existence of a local animal reservoir during this period, but its origin (resurgence or re-importation) could not be determined. This sudden and unexpected reemergence of plague, close to an important commercial seaport, is a textbook illustration of a public health event of international importance. It also demonstrates that the danger of plague reoccurrence is not limited to the currently indexed natural foci. PMID:18257987

  2. Plague reappearance in Algeria after 50 years, 2003.

    PubMed

    Bertherat, Eric; Bekhoucha, Souad; Chougrani, Saada; Razik, Fathia; Duchemin, Jean B; Houti, Leila; Deharib, Larbi; Fayolle, Corinne; Makrerougrass, Banaouda; Dali-Yahia, Radia; Bellal, Ramdan; Belhabri, Leila; Chaieb, Amina; Tikhomirov, Evgueni; Carniel, Elisabeth

    2007-10-01

    An outbreak of plague occurred in the region of Oran, Algeria, from June to July 2003. Algeria had not reported this disease for >50 years. Eighteen bubonic cases were identified, and Yersinia pestis was isolated from 6 patients. Except for the index case-patient, all patients recovered. Targeted chemoprophylaxis, sanitation, and vector control played a crucial role in controlling the outbreak. Epidemiologic and biomolecular findings strongly suggested the existence of a local animal reservoir during this period, but its origin (resurgence or re-importation) could not be determined. This sudden and unexpected reemergence of plague, close to an important commercial seaport, is a textbook illustration of a public health event of international importance. It also demonstrates that the danger of plague reoccurrence is not limited to the currently indexed natural foci. PMID:18257987

  3. Active tectonics of the Oran (Algeria) Quaternary plain

    NASA Astrophysics Data System (ADS)

    youcef, Bouhadad; rabah, Bensalem; e-hadi, oubaiche

    2016-04-01

    The Oran region, in north-western Algeria, has been hit several times in the past by destructive moderate-sized and strong earthquakes. The Oran October 9th , 1790 (I0= X) was among the strongest seismic events in the western Mediterranean area comparable, if we consider the described effects, to the El- Asnam (1980, Ms=7.3) and Zemmouri (2003, Mw=6.8) earthquakes. Such strong seismic events requires the presence of major active geological structures that are re-activated several times in the past. In this work we present results of a multi- disciplinary study combining geomorphic analysis, field earthquake geological investigations and geophysical methods, undertaken to study the southern border of the Oran Quaternary plain. A 50 km long, SW-dipping and NE-SW trending active fault has been identified that showing clear quaternary deformation. Keywords: earthquake geology, active fault, geomorphic, geophysics, Algeria.

  4. Viruses in the desert: a metagenomic survey of viral communities in four perennial ponds of the Mauritanian Sahara

    PubMed Central

    Fancello, Laura; Trape, Sébatien; Robert, Catherine; Boyer, Mickaël; Popgeorgiev, Nikolay; Raoult, Didier; Desnues, Christelle

    2013-01-01

    Here, we present the first metagenomic study of viral communities from four perennial ponds (gueltas) located in the central Sahara (Mauritania). Three of the four gueltas (Ilij, Molomhar and Hamdoun) are located at the source of three different wadis belonging to the same hydrologic basin, whereas the fourth (El Berbera) belongs to a different basin. Overall, sequences belonging to tailed bacteriophages were the most abundant in all four metagenomes although electron microscopy and sequencing confirmed the presence of other viral groups, such as large DNA viruses. We observed a decrease in the local viral biodiversity in El Berbera, a guelta with sustained human activities, compared with the pristine Ilij and Molomhar, and sequences related to viruses infecting crop pests were also detected as a probable consequence of the agricultural use of the soil. However, the structure of the El Berbera viral community shared the common global characteristics of the pristine gueltas, that is, it was dominated by Myoviridae and, more particularly, by virulent phages infecting photosynthetic cyanobacteria, such as Prochlorococcus and Synechococcus spp. In contrast, the Hamdoun viral community was characterized by a larger proportion of phages with the potential for a temperate lifestyle and by dominant species related to phages infecting heterotrophic bacteria commonly found in terrestrial environments. We hypothesized that the differences observed in the structural and functional composition of the Hamdoun viral community resulted from the critically low water level experienced by the guelta. PMID:23038177

  5. Multiple dust sources in the Sahara Desert: The importance of sand dunes

    NASA Astrophysics Data System (ADS)

    Crouvi, Onn; Schepanski, Kerstin; Amit, Rivka; Gillespie, Alan R.; Enzel, Yehouda

    2012-07-01

    We determine the current sources of dust in the Sahara Desert using quantitative correlation between the number of days with dust storms (NDS), derived from remote-sensing data of high temporal resolution, with the distribution of the soil types and geomorphic units. During 2006-8 the source of over 90% of the NDS was found to be sand dunes, leptosols, calcisols, arenosols, and rock debris. In contrast to previous studies, only few dust storms originated from playas and dry lake beds. Land erodibility was estimated by regressing the NDS to the number of days with high-speed wind events, and was found to be high for sand dunes. Clay and fine-silt grains and aggregates are scarce in sand dunes, which most likely produce dust particles through aeolian abrasion of sand grains. Thus, saltating sand grains impacting clay aggregates on playa surfaces cannot be the sole process for generating dust in the Sahara.

  6. Were Rivers Flowing across the Sahara During the Last Interglacial? Implications for Human Migration through Africa

    PubMed Central

    Coulthard, Tom J.; Ramirez, Jorge A.; Barton, Nick; Rogerson, Mike; Brücher, Tim

    2013-01-01

    Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times. PMID:24040347

  7. Resource Geopolitics: Cold War Technologies, Global Fertilizers, and the Fate of Western Sahara.

    PubMed

    Camprubí, Lino

    2015-07-01

    When, after years of geological and geophysical exploration, a phosphate mine was discovered at Bu-Craa in 1964, Western Sahara received renewed geopolitical attention. Several countries competing for the control of the world fertilizer market, including Morocco, Spain, France, and the United States, developed diverging strategies to gain control of the mineral. After intense negotiations revolving around the materiality of mining technologies and involving reserve estimations, sabotage, and flexing of diplomatic muscles, Morocco took over the Spanish colony in 1975. While this secured Morocco's place in the world market, it condemned the local population to exile and domination. This article explores three technological stages of the exploitation of phosphate in Western Sahara that underpin the geopolitical history. This perspective yields new visions of cold war technology and postcolonial markets. PMID:26387526

  8. Molecular basis of alpha-thalassemia in Algeria.

    PubMed

    Mesbah-Amroun, Hamida; Rouabhi, Fatiha; Ducrocq, Rolande; Elion, Jacques

    2008-01-01

    An epidemiological molecular study was carried out to evaluate the spectrum and allelic frequency of alpha-thalassemia (alpha-thal) defects in Algeria. A series of 153 randomly selected blood donors was screened for 10 alpha-thal alleles described in the Mediterranean area. In addition, six unrelated cases with hematological and biochemical data suggestive of Hb H disease were investigated. Our data revealed an allele frequency of 4.6%. The presence of alpha(0)-thal determinants (-alpha(20.5) and --MED I) was observed both in Hb H patients and in the randomly collected samples. Overall, the -alpha(3.7) deletion was the most prevalent allele (2.9%), followed by the alpha(Nco I)alpha (HBA2:c.1A>G) allele (0.6%) and by the alpha(Hph I)alpha (HBA2:c.95 + 2_95 + 6delTGAGG), -alpha(20.5), --(MED I) alleles (0.3% each). The -alpha(4.2) deletion was observed in only one Hb H patient. These results outline the heterogeneity of the alpha-thal alleles in Algeria which reflects the anthropological history of the country. Because of their frequency, alpha-thal alleles are probably frequent modulators of prevalent beta-globin gene-related hemoglobinopathies in Algeria. PMID:18473243

  9. Epidemiology of Visceral Leishmaniasis in Algeria: An Update

    PubMed Central

    Adel, Amel; Boughoufalah, Amel; Saegerman, Claude; De Deken, Redgi; Bouchene, Zahida; Soukehal, Abdelkrim; Berkvens, Dirk; Boelaert, Marleen

    2014-01-01

    Visceral leishmaniasis (VL), a zoonotic disease caused by Leishmania infantum, is endemic in Algeria. This report describes a retrospective epidemiological study conducted on human VL to document the epidemiological profile at national level. All human VL cases notified by the National Institute of Public Health between 1998 and 2008 were investigated. In parallel all VL cases admitted to the university hospitals of Algiers were surveyed to estimate the underreporting ratio. Fifteen hundred and sixty-two human VL cases were reported in Algeria between 1998–2008 with an average annual reported incidence rate of 0.45 cases per 100,000 inhabitants, of which 81.42% were in the age range of 0–4 years. Cases were detected year-round, with a peak notification in May and June. One hundred and seventy patients were admitted to the university hospitals in Algiers in the same period, of which less than one in ten had been officially notified. Splenomegaly, fever, pallor and pancytopenia were the main clinical and laboratory features. Meglumine antimoniate was the first-line therapy for paediatric VL whereas the conventional amphotericin B was used for adult patients. Visceral leishmaniasis in Algeria shows the epidemiological profile of a paediatric disease with a decrease of the annual reported incidence rate. However, vigilance is required because of huge underreporting and an apparent propagation towards the south. PMID:24949958

  10. Aridification of the Sahara desert caused by Tethys Sea shrinkage during the Late Miocene.

    PubMed

    Zhang, Zhongshi; Ramstein, Gilles; Schuster, Mathieu; Li, Camille; Contoux, Camille; Yan, Qing

    2014-09-18

    It is widely believed that the Sahara desert is no more than ∼2-3 million years (Myr) old, with geological evidence showing a remarkable aridification of north Africa at the onset of the Quaternary ice ages. Before that time, north African aridity was mainly controlled by the African summer monsoon (ASM), which oscillated with Earth's orbital precession cycles. Afterwards, the Northern Hemisphere glaciation added an ice volume forcing on the ASM, which additionally oscillated with glacial-interglacial cycles. These findings led to the idea that the Sahara desert came into existence when the Northern Hemisphere glaciated ∼2-3 Myr ago. The later discovery, however, of aeolian dune deposits ∼7 Myr old suggested a much older age, although this interpretation is hotly challenged and there is no clear mechanism for aridification around this time. Here we use climate model simulations to identify the Tortonian stage (∼7-11 Myr ago) of the Late Miocene epoch as the pivotal period for triggering north African aridity and creating the Sahara desert. Through a set of experiments with the Norwegian Earth System Model and the Community Atmosphere Model, we demonstrate that the African summer monsoon was drastically weakened by the Tethys Sea shrinkage during the Tortonian, allowing arid, desert conditions to expand across north Africa. Not only did the Tethys shrinkage alter the mean climate of the region, it also enhanced the sensitivity of the African monsoon to orbital forcing, which subsequently became the major driver of Sahara extent fluctuations. These important climatic changes probably caused the shifts in Asian and African flora and fauna observed during the same period, with possible links to the emergence of early hominins in north Africa. PMID:25230661

  11. Palaeohydrology of the Fazzan Basin, Libyan Sahara: Evidence for multiple phases of North African humidity.

    NASA Astrophysics Data System (ADS)

    Armitage, S. J.; White, K.; Drake, N.

    2008-12-01

    The Fazzan is a large closed basin with an area of 450,000 km2, located in south-western Libya. The present-day climate is hyper-arid. Modern human occupation is restricted to oases, notably at the foot of the Messak Sattafat, a Nubian Sandstone escarpment which divides the Fazzan into two sub-basins. However widespread lithic scatters with varying inferred ages, and numerous Holocene hearth fields, indicate that the Fazzan has a long history of human occupation. In addition, regionally extensive lake deposits attest to the presence of a large palaeolake, here termed Lake Mega-Fazzan, at various periods in the past. Although the Sahara contains evidence for several other large palaeolakes, Lake Mega-Fazzan is the only one fed exclusively by rivers draining the Sahara proper. Thus, the Lake Mega-Fazzan sediments and archaeological remains provide an important resource for advancing our understanding of climate change in this part of the Sahara. Optically stimulated luminescence (OSL) dating techniques have been applied to a range of lacustrine deposits, and more experimentally to the Holocene hearth fields, to provide an internally consistent chronology for the Fazzan record. Results indicate that sediments within the Fazzan Basin record a very long history of palaeohydrological change. The oldest lacustrine sediments are beyond the range of conventional OSL dating techniques, but younger humid periods during oxygen isotope stages 11, 5 and 1 are recognised. Initial results from one hearth field also indicate that OSL has the potential to reveal human responses to changes in hydrology during the Holocene. These results, when compared with similar studies of adjacent closed basins, indicate that the Sahara may not always have provided as formidable a barrier to faunal migration as it does at present. The implications of this finding for our understanding of North African palaeoclimate and biogeography will be discussed.

  12. Ambient measurements of selected VOCs in populated and remote sites of the Sahara desert

    NASA Astrophysics Data System (ADS)

    Yassaa, Noureddine; Ciccioli, Paolo; Brancaleoni, Enzo; Frattoni, Massimiliano; Meklati, Brahim Youcef

    2011-04-01

    For the first time, ambient levels of benzene, toluene, carbon tetrachloride and selected oxygenated organic compounds have been measured in both populated and remote sites in the Sahara desert. The levels of these species were generally found to be high in the industrialized regions of the North Sahara, progressively decreasing with latitude so that lowest levels were reached in remote desert sites close to the Equator. The emissions from traffic, and the oil production and its transformation, together with the solvent use were the main anthropogenic sources determining the levels of aromatic, aliphatic and chlorinated organic compounds in desert sites near two Algerian cities. Substantial levels of acetone and some semi-volatile compounds, emitted or formed by photochemical reactions, were also found. Although some of these compounds were below the detection limits in the most remote sites of the Sahara desert located in Mauritania and Niger, measurable levels of benzene and toluene were still found together with significant amounts of acetone. Data seem to indicate that forest fires occurring in the tropical regions of the North African continent were the most likely sources for the background levels measured during most of our measurements. The data presented here did not differ too much from those measured in the most isolated sites of the northern hemisphere.

  13. AISAT-1: the First Step into Space for Algeria

    NASA Astrophysics Data System (ADS)

    Oussedik, A.; Bekhti, M.; Sun, W.; Sweeting, M. N., , Sir

    2002-01-01

    AlSat-1, the first Algerian national satellite of seven microsatellites in the Disaster Monitoring Constellation (DMC), will be launched in September 2002. Micro satellites for Nigeria, United Kingdom, Turkey and Thailand will be launched into the same orbit by the second DMC launch in April 2003, whilst microsatellites for China and Vietnam will be launched into the same orbit by the third DMC launch in January 2004. In a constellation with six other satellites, Algeria will be able to access global images for daily global disaster mitigation, national remote sensing applications, commercial space exploitation and international co-operation with both developed and developing countries. A team of eleven (11) Algerian engineers has been trained at Surrey through the AlSat-1 project. They have covered the following disciplines: System Engineering, ADCS, Power, RF, OBDH, Mechanical and Launch Interface, Earth Observation Payload, GPS, Operation, TTC and Propulsion. AlSat-1, the first space asset of the country, provides indigenous national space capability, unique independent Earth observation and international co-operation opportunities. The country has received this first step into space very well. Following the success of the AlSat-1 programme, a National Space Agency is under construction in Algeria with all the necessary facilities, and the government has approved the budget for a second earth observation microsatellite, AlSat-2. This 2.5m high-resolution remote sensing satellite will be used essentially for mapping and environmental applications. The team trained at Surrey will build the majority of AlSat-2 in the National Space Centre in Algeria using the technologies acquired from Surrey. A further technology transfer and training programme will be carried out through this more demanding mission. The paper will present the AlSat-1 programme and its benefits to Algeria. The proposed AlSat-2 project and the establishment of a national space agency, based on the

  14. Comparing environmental changes and habitability settings in the geological history of Sahara and Mars

    NASA Astrophysics Data System (ADS)

    Ori, G. G.; Sabbadini, R.; Komatsu, G.

    2014-12-01

    Sahara has experienced during its long geological history a large number of climatic changes from humid conditions (with savanna-type environments) to dry conditions (with hot desert environments). Therefore, since the late Miocene (?), Sahara experienced periods with rivers, lakes, deltas, and swamps alternated with dry periods with strong aeolian activity and the formation of deflation surface and sand seas. The fluvio-lacustrine deposits formed during humid periods have been strongly reworked by wind processes during the dry periods leaving only the coarse-grained portion of the sediments (conglomerate to rudite). This highly efficient reworking eeolian mechanism affected both of the fluvial and deltaic channel deposits and the large inland lakes, flood plains and other waterlogged areas. The former occurs, at present day, as morphological features and coarse-grained remnants of large fluvial systems whereas the latter are mostly buried below sand seas such as Grand Erg Oriental, Erg Chech, and Azawad. While the sand to silt material accumulated (mostly by saltation) in the sand seas and sand sheets, the finer portion (able to enter the wind as suspended material) was probably swallowed in the large- scale atmospheric circulation redistributed in Sahara itself, in adjacent continents (mostly Europe and South America), and oceans. This geological setting is similar to the one of Mars where fluvial deposits and morphologies abound as largely eroded discontinuous remains. Large-scale alluvial basins and terminal lakes or waterlogged areas (such as the allucial plain in Zephyria) have been largely present in the Martian Noachian-Hesperian time (and possibly even later) but relatively scanty sedimentary deposits testify their existence. When deposits are present they are basically coarse-grained (e.g. the meandering channels of the Eberswalde deltaic plain) due to the long lasting aeolian erosion similarly than the Sahara example. The wind, that dominated the long

  15. Teaching Morality and Religion in Nineteenth-Century Colonial Algeria: Gender and the Civilising Mission

    ERIC Educational Resources Information Center

    Rogers, Rebecca

    2011-01-01

    Historians have long presented France's "civilizing mission" within its colonies in secular terms ignoring women's presence as both actors and subjects. This is particularly true in Algeria where the colonial government's explicitly prohibited proselytism. This article emphasizes women's roles pursuing both secular and religious goals in Algeria.…

  16. Geomorphologic approach for modelling the surface features of arid environments in a model of dust emissions: application to the Sahara desert

    NASA Astrophysics Data System (ADS)

    Callot, Yann; Marticorena, Béatrice; Bergametti, Gilles

    elaborated. The data provided by the modelling of the surface have been used to simulate dust emissions for 1990, 1991 and 1992 over the central and western Sahara. Over these three years, the mean annual dust emission is about 760 Mt·year- 1 Although a significant interannual variability exists (mainly due to changes in the wind pattern), the most intensive emissions remain quite constant in terms of location. The percentage of agreement with satellite observations higher than 0.7 is 74 %, but only 32 % when using a model having a single threshold function for dust emission (i.e. the same surface feature for the whole Sahara) (cf. later Marticorena et al., 1997).

  17. Coseismic deformation of the May 21st, 2003, Mw = 6.8 Boumerdes earthquake, Algeria, from GPS measurements

    NASA Astrophysics Data System (ADS)

    Yelles, K.; Lammali, K.; Mahsas, A.; Calais, E.; Briole, P.

    2004-07-01

    On May 21st, 2003, a Mw = 6.8 earthquake struck the central part of northern Algeria causing extensive damage in the Boumerdes area, 40 km east of Algiers. It is among the largest events to occur in the western Mediterranean over the past 25 years. We present GPS measurements of horizontal coseismic displacements that provide new constraints on the rupture geometry. Modeling the data with a uniform dislocation on a rectangular fault in an elastic half-space, we find that the rupture occurred on a reverse fault dipping 42°S, with its upper edge 6 km offshore and lower edge 4 km inland. The amplitude distribution of the coseismic displacements indicates that the rupture did not reach the surface, at least in its western part, and ended to the west around 3.4°E. Offshore faults like that of the Boumerdes earthquake could account for part of the Africa-Eurasia relative plate motion in the western Mediterranean and represent a significant seismic threat for Algeria.

  18. Characteristics of rheumatoid arthritis in Algeria: a multicenter study.

    PubMed

    Slimani, Samy; Abbas, Abdelmalek; Ben Ammar, Amina; Kebaili, Djemaa; Ali, El Hadi; Rahal, Fadia; Khamari, Mohamed Choukri; Baltache, Ayada; Khider, Imene; Chiheub, Riad; Khelif, Khireddine; Akbi, Sabrina; Rahmani, Salima; Dahou-Makhloufi, Chafia; Brahimi-Mazouni, Nadjia; Abtroun-Benmadi, Sabira; Ladjouze-Rezig, Aicha

    2014-09-01

    The aim of this study was to compare the epidemiology of rheumatoid arthritis (RA) in North Africa to that of Western countries. We have enrolled in a cross-sectional study all consecutive patients presenting with the diagnosis of RA according to the 1987 ACR criteria, and during a 5-month period, patients were included in 11 centers across northern Algeria. Demographics, clinical data, and health assessment questionnaires (HAQ) were collected for each patient. We have estimated means, standard deviations, and 95 % confidence intervals for all parameters. Of the 249 patients (213 females and 36 males) enrolled in the study, 10 (4 %) had juvenile onset of the disease. The mean age was 50.1 ± 14.5 years, and the mean duration of RA was 8.4 ± 7.8 years. In terms of comorbidities, 18.9 % of patients reported hypertension and 5.2 % had diabetes. The mean DAS28 at inclusion was 4.3 (95 % CI 4.1-4.5); 14.0 % were in remission (DAS28 ≤ 2.6). The mean HAQ score was 0.81 ± 0.82. Rheumatoid factor was positive in 78.5 % of cases, and anti-citrullinated protein/peptide antibodies, when measured, was positive in 69.0 % of cases. Seronegative patients were older and had a relatively less severe disease. For treatment, 89.7 % of patients were taking disease-modifying anti-rheumatic drugs and only 4 % were taking biologics (rituximab); 90.8 % of patients were taking glucocorticoids, and none of the patients satisfied the recommended calcium intake guidelines. RA in Algeria is more common in women. Compared to reports from Western countries, RA in Algeria appears to be less aggressive, with more dominant seronegative oligoarthritis forms. The remission rate is comparable to that of Western populations. PMID:24633899

  19. Neotectonic deformation model of the Northern Algeria from Paleomagnetic data

    NASA Astrophysics Data System (ADS)

    Derder, M. E. M.; Henry, B.; Maouche, S.; Amenna, M.; Bayou, B.; Djellit, H.; Ymel, H.; Gharbi, S.; Abtout, A.; Ayache, M.

    2012-04-01

    The seismic activity of the Western Mediterranean area is partly concentrated in northern Africa, particularly in northern Algeria, as it is shown by the strongest recent earthquakes of "Zemmouri" 21 May 2003 Mw=6.9 and the "El Asnam" 10 October 1980 Ms= 7.3. This seismicity is due to the tectonic activity related to the convergence between Africa and Eurasia plates since at least the Oligocene. The deformation is mostly compressional with associated folds, strike-slip faults and thrusts, and a direction of shortening between N-S and NNW-SSE. This convergence involves a tectonic transpression which is expressed by active deformation along the plate boundary. In northern Algeria, the seismicity is concentrated in a coastal E-W thin band zone (the Tell Atlas). Active structures define there NE-SW trending folds and NE-SW sinistral transpressive faults, which affect the intermountain and coastal Neogene to Quaternary sedimentary basins (e.g. " Cheliff "basin, " Mitidja "basin, …). These reverse faults are associated with NW-SE to E-W strike-slips deep faults. The active tectonics could be explained by a simple blocks rotation kinematics model. In order to test the validity of this kinematic model, three different paleomagnetic studies have been conducted. The first one concerned the "Cheliff" basin where sedimentary Neogene formations were extensively sampled (66 sites). The second study was carried out on Miocene andesite and dacite rocks cropping out along the northern coastal zone of the "Cheliff" basin ("Beni Haoua" area, 19 sites). The third study has been carried out on the Miocene magmatic rocks (rhyolites and basalts) cropping out north-eastern part of the "Mitidja" basin ("Cap Djinet" - "Boumerdes" area, 23 sites). The obtained results show existence of paleomagnetic clockwise rotations in all the studied areas and then validates the kinematics block rotation model. Accordingly, the deformation related to the convergence between the Africa and Eurasia

  20. How much rainfall sustained a Green Sahara during the mid-Holocene?

    NASA Astrophysics Data System (ADS)

    Hopcroft, Peter; Valdes, Paul; Harper, Anna

    2016-04-01

    The present-day Sahara desert has periodically transformed to an area of lakes and vegetation during the Quaternary in response to orbitally-induced changes in the monsoon circulation. Coupled atmosphere-ocean general circulation model simulations of the mid-Holocene generally underestimate the required monsoon shift, casting doubt on the fidelity of these models. However, the climatic regime that characterised this period remains unclear. To address this, we applied an ensemble of dynamic vegetation model simulations using two different models: JULES (Joint UK Land Environment Simulator) a comprehensive land surface model, and LPJ (Lund-Potsdam-Jena model) a widely used dynamic vegetation model. The simulations are forced with a number of idealized climate scenarios, in which an observational climatology is progressively altered with imposed anomalies of precipitation and other related variables, including cloud cover and humidity. The applied anomalies are based on an ensemble of general circulation model simulations, and include seasonal variations but are spatially uniform across the region. When perturbing precipitation alone, a significant increase of at least 700mm/year is required to produce model simulations with non-negligible vegetation coverage in the Sahara region. Changes in related variables including cloud cover, surface radiation fluxes and humidity are found to be important in the models, as they modify the water balance and so affect plant growth. Including anomalies in all of these variables together reduces the precipitation change required for a Green Sahara compared to the case of increasing precipitation alone. We assess whether the precipitation changes implied by these vegetation model simulations are consistent with reconstructions for the mid-Holocene from pollen samples. Further, Earth System models predict precipitation increases that are significantly smaller than that inferred from these vegetation model simulations. Understanding

  1. Sahara Slide: Age, initiation, and processes of a giant submarine slide

    NASA Astrophysics Data System (ADS)

    Georgiopoulou, Aggeliki; Masson, Douglas G.; Wynn, Russell B.; Krastel, Sebastian

    2010-07-01

    The Sahara Slide is a giant submarine landslide on the northwest African continental margin. The landslide is located on the open continental slope offshore arid Western Sahara, with a headwall at a water depth of ˜2000 m. High primary productivity in surface waters drives accumulation of thick fine-grained pelagic/hemipelagic sediment sequences in the slide source area. Rare but large-scale slope failures, such as the Sahara Slide that remobilized approximately 600 km3 of sediment, are characteristic of this sedimentological setting. Seismic profiles collected from the slide scar reveal a stepped profile with two 100 m high headwalls, suggesting that the slide occurred retrogressively as a slab-type failure. Sediment cores recovered from the slide deposit provide new insights into the process by which the slide eroded and entrained a volcaniclastic sand layer. When this layer was entrained at the base of the slide it became fluidized and resulted in low apparent friction, facilitating the exceptionally long runout of ˜900 km. The slide location appears to be controlled by the buried headwall of an older slope failure, and we suggest that the cause of the slide relates to differential sedimentation rates and compaction across these scarps, leading to local increases of pore pressure. Sediment cores yield a date of 50-60 ka for the main slide event, a period of global sea level rise which may have contributed to pore pressure buildup. The link with sea level rising is consistent with other submarine landslides on this margin, drawing attention to this potential hazard during global warming.

  2. How well do analyses capture dust-generating winds in the Sahara and Sahel?

    NASA Astrophysics Data System (ADS)

    Roberts, Alexander; Marsham, John; Knippertz, Peter; Parker, Douglas

    2016-04-01

    Airborne mineral dust is important for weather, climate and earth-system prediction. Uncertainty in winds, as well as the land-surface, are known to be key to model uncertainties for dust uplift. Recent research has shown that during the summer wet season in the Sahel strong winds generated by the cold outflow from organized convective systems are an important dust storm mechanism (so called haboobs), while over the inner Sahara nocturnal low-level jets forming on the pressure gradient around the heat low dominate. Together the Sahel and Sahara are the world's largest dust source. Until now there has been a severe shortage of data for evaluating models for this region. Here, we bring together new observations from the remote Sahara, made during the Fennec project, with Sahelian data from the African Monsoon Multidisciplinary Analysis (AMMA), to provide an unprecedented evaluation of dust-generating winds in the European Centre for Medium-Range Weather Forecasts ERA-Interim (ERA-I) reanalysis. Differences between observations and ERA-I are explored with specific attention to monsoon and non-monsoon influenced regions. The main results are: (1) High speed winds in instantaneous ERA-I grid-box mean winds are lacking compared to time-averaged wind speed observations; (2) agreement between ERA-I and observations is lower during the monsoon season, even in parts of the Sahara not directly affected by the monsoon; and (3) both the seasonal and diurnal variability is under-represented in ERA-I. ERA-I fails to capture the summertime maximum for monsoon-affected stations and seasonally, correlations between daily-mean ERA-I and observed winds vary from 0.8 to 0.4, with lower correlations for 3-hourly data. These differences demonstrate that the model used in the production of the ERA-I reanalysis is unable to represent some important dust uplift processes, especially during the monsoon season when moist convection plays a key role, and that the product is not sufficiently

  3. Sahara 99555 and D'Orbigny: Possible Pristine Parent Magma of Quenched Angrites

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; McKay, G. A.; Jones, J. H.

    2004-01-01

    Angrites constitute a small, but important group of basaltic achondrites showing unusual mineralogy and old crystallization ages. The currently known angrites are divided into two subgroups. Angra dos Reis (ADOR) and LEW86010 show slow cooling histories ("slowly-cooled" angrites) and differ from the later found angrites (LEW87051, Asuka 881371, Sahara 99555, D Orbigny, NWA1670, NWA1298). This second group has textures that suggest rapid cooling histories ("quenched" angrites). The petrogenesis of angrites has been controversial, partly due to the small number of available samples. In this abstract, we suggest a possible parent melt composition for the quenched angrites and its relationship to the partial melts of carbonaceous chondrites.

  4. [Targeting abattoirs to control cystic echinococcosis in Algeria].

    PubMed

    Benchikh ElFegoun, M C; Kohil, K; L'Ollivier, C; Lleu, M; Babelhadj, B; Piarroux, M; Gharbi, M; Piarroux, R

    2016-08-01

    Cystic echinococcosis (CE) is an important anthropozoonotic parasitic common in Algeria. The predominant life cycle of E. granulosus is a synanthropic cycle with domestic dogs as definitive hosts and livestock animals as intermediate hosts. Slaughter activity represents a potential source for dogs to access infected offal. The aim of the present study was to determine if the contact between dogs and potentially infected offal was possible in licensed abattoirs. Eighty-one private and public abattoirs located in eastern Algeria were assessed with respect to their level of protection against the intrusion of dogs.We have demonstrated that in 42 % of these abattoirs, dogs could easily come in contact with potentially parasitized offal. The most common incorrect practices were the dumping of offal freely into the environment, the feeding of dogs with offal, and the leaving of unattended offal in an unsealed chamber. Overall, some hazardous practices remained common customs of workers, and enough abattoirs remain non-compliant that the cattledog domestic cycle of CE is unlikely to be broken. Hence, some recommended measures to interrupt parasite transmission include the following: recognition of the importance of abattoirs in the maintenance of canine echinococcosis, the controlled and proper disposal of offal, the abolishment of the custom of feeding dogs with infected offal and improvements in the level of health education of abattoir staff. PMID:27251548

  5. CO2-storage assessment and effective capacity in Algeria.

    PubMed

    Aktouf, Abdelouahab; Bentellis, Abdelhakim

    2016-01-01

    Deep saline aquifers widely distributed deep in the earth offer the greatest CO2 storage potential in all current geological CO2 storage approaches. The western region of the Saharan platform in Algeria includes several sedimentary basins characterized by a large production of dry gas with high CO2 rates sometimes exceeding 9 %. To reduce CO2 emissions, these basins were analyzed to identify those with the largest potential for the geological sequestration of CO2 (GSC). The evaluation methodology applied to determine the basin potential is based on qualitative geological and practical criteria to which we have assigned normalized numerical values. This evaluation method allows us to quantitatively compare and evaluate the basins in Algeria. Estimations of the CO2 storage capacities of several structures in the sedimentary Ahnet-Gourara Basin, which has the greatest potential for GSC, vary from 1 Gt to over 5 Gt. Based on cautious estimations, these geologic structures should be able to contain the entire volume of the CO2 emitted over the next three decades at least. PMID:27462486

  6. Ionizing radiations, underground world and nuclear tests in Algeria

    NASA Astrophysics Data System (ADS)

    Chama, Allel

    2010-05-01

    Today, the exposure to ionizing radiations, is still a real great physical hazard in the world at various levels until the nuclear tests which led to a rich and lawful debate, and needs the installation of preventive rules through technical and medical aspects during the use of the radioactive sources, (theradioprotection). Concerning the occupational health, the pathology of the ionizing radiations is repaired under occupational disease. Our interest is to highlight this physical hazard, which represents an important chapter of the occupational pathology in its effects and prevention of the workers exposed in Algeria. The second aim of the paper is to highlight the historical aspect of the risk of ionizing radiations and consequences causes by the French nuclear tests in In Eker (underground galleries of the mountain of Hoggar in the south of Algeria in 1961), whose effects present a great damage on the health of the Algerian captive, and "workers", indigenous population and environment until now. This event deserves its place as much as that of Hiroshima and Nagasaki (1945).

  7. Setting in evidence of the new climatic tendency in Algeria by the analysis of the main variables of the climate : Survey of the chronological sets on more of 50 years.

    NASA Astrophysics Data System (ADS)

    Zeineddine, N.

    2009-09-01

    Setting in evidence of the new climatic tendency in Algeria by the analysis of the main variables of the climate : Survey of the chronological sets on more of 50 years. In the present conditions of the global climatic changes, North Africa and Maghreb, observe these last years of the distresses without precedent. This new tendency expresses itself by a rise of the temperatures confirmed in several countries. In the same way to this rise, one also notes an intensification of the climatic cycles (more and more humid humid periods, more and more dry dry periods). So, after the long droughts observed in the years four - twenty and ninety, the a lot more humid period bootjack is noted in the whole region. These phases are punctuated however sometimes of stern droughts, that been the case in 2000 to Morocco and in Algeria. The humid phases are as for them more and more frequent and are characterized henceforth by very intense rainy episodes. Repeatedly, serious floodings touched these countries. In 2002 in Algeria, it is the capital that has been touched, the districts of Bab - El Wadi was heavily damaged. In the valley of the Soummam, the town of Bejaïa was the theater of important phenomena of urban flooding in 2007. In the Algerian Sahara, heavy rains provoked the rise in the water level of the wadi M' Zab and the submersion of the city of Ghardaïa. All as Algeria, Tunisia has also been touched by these phenomena. The city of Tunis knew a tragic episode thus in 2007. To the west extreme of North Africa in 2002, Morocco has been hit by important floodings that made 35 deaths.. Progressively, the climatic conditions become unusual. The signs of the changes prove to be even more meaningful with the records of rain for the agricultural year 2008 / 2009 in the under region from the Maghreb (Morocco - Algeria). Qualified of exceptional and historic, rains have generously supplied the watertables, carrying the water security margin to close to two years in drinking water

  8. Mossbauer Spectra of Weathered H5 Ordinary Chondrites from Reg EL Acfer, Algeria

    NASA Astrophysics Data System (ADS)

    Berry, F.; Oates, G.; Bland, P.; Pillinger, C. T.

    1992-07-01

    Approximately 380 meteorite specimens have been retrieved from the Acfer region of the Sahara desert, Algeria. To date, 26 of these have been classified H5 (Bischoff et al., 1990, 1991, 1992). Being the most common meteorite type and having a tightly constrained mineralogy (Mason, 1965), H5 chondrites are ideal candidates for investigating terrestrial weathering products in meteorites. Arid climate, uniform topography, and lack of a concentration/movement mechanism makes it likely that meteorites throughout Reg el Acfer were weathered by a common mechanism. Jull et al. (1991) showed a correlation in meteorites from Roosevelt County between terrestrial ^14C ages and a qualitative weathering scale. An aim of the present study is to provide a quantitative measure of weathering for the Acfer region that might allow an estimate of terrestrial age, as well as information on pairing. Meteorite Specimens: Approximately 1 g of sample was used, prepared by grinding under acetone to prevent oxidation during crushing, until a homogenized powder was produced. Mossbauer spectra were recorded at 298 degrees K with a microprocessor controlled Mossbauer spectrometer using a ^57Co/Rh source. Drive velocity was calibrated with the same source and a metallic iron foil. Results: The H5 chondrite Acfer 146 (Bischoff, forthcoming Meteoritical Bulletin) was found on 19/11/90 at coordinates 27 degrees 38'N, 4 degrees 05'E. This meteorite gave a spectrum dominated by quadrupole split absorption characteristics of Fe^2+ in a forsteritic olivine structure. A sample of the outer crust showed the additional presence of Fe^3+. XRD was insensitive to the unequivocal identification of the phases present in the two samples and given that the Mossbauer parameters of the hydrolyzed Fe^3+ species and ferric oxyhydroxides are very similar it is not possible at this stage to identify the oxidized phase. Clearly, however, the results demonstrate the sensitivity of Mossbauer spectroscopy to the products

  9. Impact of Sahara dust transport on Cape Verde atmospheric element particles.

    PubMed

    Almeida-Silva, M; Almeida, S M; Freitas, M C; Pio, C A; Nunes, T; Cardoso, J

    2013-01-01

    The objectives of this study were to (1) conduct an elemental characterization of airborne particles sampled in Cape Verde and (2) assess the influence of Sahara desert on local suspended particles. Particulate matter (PM(10)) was collected in Praia city (14°94'N; 23°49'W) with a low-volume sampler in order to characterize its chemical composition by k0-INAA. The filter samples were first weighed and subsequently irradiated at the Portuguese Research Reactor. Results showed that PM(10) concentrations in Cape Verde markedly exceeded the health-based air quality standards defined by the European Union (EU), World Health Organization (WHO), and U.S. Environmental Protection Agency (EPA), in part due to the influence of Sahara dust transport. The PM(10) composition was characterized essentially by high concentrations of elements originating from the soil (K, Sm, Co, Fe, Sc, Rb, Cr, Ce, and Ba) and sea (Na), and low concentrations of anthropogenic elements (As, Zn, and Sb). In addition, the high concentrations of PM measured in Cape Verde suggest that health of the population may be less affected compared with other sites where PM(10) concentrations are lower but more enriched with toxic elements. PMID:23514066

  10. Eolian sediment responses to late Quaternary climate changes: Temporal and spatial patterns in the Sahara

    USGS Publications Warehouse

    Swezey, C.

    2001-01-01

    This paper presents a compilation of eolian-based records of late Quaternary climate changes in the Sahara. Although the data are relatively sparse, when viewed as a whole, they reveal a general pattern of widespread eolian sediment mobilization prior to 11,000 cal. years BP, eolian sediment stabilization from 11,000 to 5000 cal. years BP, and a return to widespread eolian sediment mobilization after 5000 cal. years BP. Furthermore, an eolian-based record from southern Tunisia reveals the existence of millennial-scale changes in eolian sediment behavior. These millennial-scale variations provide examples of eolian sediment responses to climate changes at a scale intermediate between seasonal and orbital ('Milankovitch') changes, and they are also coincident with abrupt atmospheric and oceanic changes. The general synchroneity of the eolian stratigraphic records and their coincidence with various oceanic and atmospheric changes suggest that global forcing mechanisms have influenced late Quaternary eolian sediment behavior in the Sahara. ?? 2001 Elsevier Science B.V.

  11. Remote monitoring of aerosol layers over Sofia during Sahara dust transport episode (April, 2012)

    NASA Astrophysics Data System (ADS)

    Stoyanov, Dimitar; Grigorov, Ivan; Deleva, Atanaska; Kolev, Nikolay; Peshev, Zahari; Kolarov, Georgi; Donev, Evgeni; Ivanov, Danko

    2013-03-01

    In this work we present results of lidar remote sensing of aerosol layers in the atmosphere above Sofia during an episode of Sahara dust transport, 02-07 April, 2012. The investigations were made using two lidar systems, one equipped with a CuBr-vapor laser, emitting at wavelength 510.6 nm, and a second one - with Nd:YAG laser, at wavelengths 1064 nm and 532 nm. The results of lidar measurements are presented in terms of vertical atmospheric backscatter coefficient profiles and color maps of the aerosol stratification evolution. The involved into discussions ceilometer data (CHM 15k ceilometer) and satellite data from CALIPSO lidar, enhance the synergy of observations. Conclusion about atmospheric aerosol's origin was made upon analyses of the information of weather-forecast maps provided by the Forecast system of Barcelona Supercomputing Centre, which are accessible via Internet. Additional information was provided by calculations of the backward air mass trajectories, using online software of NOAA about HYSPLIT model. The comparison between the data from the two lidars and the ceilometer showed similar behavior of aerosol layers development in the atmosphere above Sofia. All information about aerosol layers origin, their altitude above ground, persistence during lidar observations, confirmed the conclusion of observation of a long-distance Sahara dust transport beyond Balkans and Sofia. An interesting completion of CALIPSO lidar and ground based lidars results of measurement is presented in case of thick opaque cloud layer in the atmosphere, which slices the path of lidar sensing in both directions.

  12. Activity patterns in the Sahara Desert: an interpretation based on cross-sectional geometric properties.

    PubMed

    Nikita, Efthymia; Siew, Yun Ysi; Stock, Jay; Mattingly, David; Lahr, Marta Mirazón

    2011-11-01

    The Garamantian civilization flourished in modern Fezzan, Libya, between 900 BC and 500 AD, during which the aridification of the Sahara was well established. Study of the archaeological remains suggests a population successful at coping with a harsh environment of high and fluctuating temperatures and reduced water and food resources. This study explores the activity patterns of the Garamantes by means of cross-sectional geometric properties. Long bone diaphyseal shape and rigidity are compared between the Garamantes and populations from Egypt and Sudan, namely from the sites of Kerma, el-Badari, and Jebel Moya, to determine whether the Garamantian daily activities were more strenuous than those of other North African populations. Moreover, sexual dimorphism and bilateral asymmetry are assessed at an intra- and inter-population level. The inter-population comparisons showed the Garamantes not to be more robust than the comparative populations, suggesting that the daily Garamantian activities necessary for survival in the Sahara Desert did not generally impose greater loads than those of other North African populations. Sexual dimorphism and bilateral asymmetry in almost all geometric properties of the long limbs were comparatively low among the Garamantes. Only the lower limbs were significantly stronger among males than females, possibly due to higher levels of mobility associated with herding. The lack of systematic bilateral asymmetry in cross-sectional geometric properties may relate to the involvement of the population in bilaterally intensive activities or the lack of regular repetition of unilateral activities. PMID:21953517

  13. Composition and chemical variability of Eucalyptus bosistoana essential oil from Algerian Sahara.

    PubMed

    Bouzabata, Amel; Bighelli, Ange; Abed, Lahouari; Casanova, Joseph; Tomi, Félix

    2014-05-01

    The composition of eight oil samples isolated from leaves of Eucalyptus bosistoana F. Muell., acclimatized in Tamanrasset (southern Algeria, Saharan climate), has been investigated by GC (retention indices), GC-MS and 13C NMR spectroscopy. T wo groups may be distinguished. The five samples of group I have their composition dominated by p-cymene (32.0-39.5%), cryptone (11.5-15.6%), 1,8-cineole (7.8-10.5%) and spathulenol (6.8-16.5%). The three oil samples of group II contained mainly 1,8-cineole (55.3-63.9%) and alpha-pinene (11.6-12.1%). PMID:25026726

  14. Sahara Dust

    Atmospheric Science Data Center

    2013-04-15

    article title:  Casting Light and Shadows on a Saharan Dust Storm     ... (nadir) camera. High-altitude cirrus clouds cast shadows on the underlying ocean and dust layer, which are visible in shades of ... was unable to retrieve elevation data. However, the edges of shadows cast by the cirrus clouds onto the dust (indicated by blue and cyan ...

  15. Patterns of Benign and Malignant Lesions of the Thyroid in Two Wilayahs of Northeastern Algeria

    PubMed Central

    Guidoum, Mona; Kherfi-Kadi, Hind; Benharkat-Boughaba, Ouahiba; Djemaa-Bendjazia, Aicha; Keghouche, Sihem; Abedi-Ardekani, Behnoush; Azzouz, Amina; Kadi, Yacine; Hainaut, Pierre; Bouslama, Zihad

    2015-01-01

    The aim of this study is to compare histological patterns and to estimate the burden of thyroid cancers in the two Wilayahs (departments) of El-Taref and Guelma in northeast of Algeria (total population 0.9 million), locally reputed as having different rates of endemic thyroid diseases and cancer. A retrospective analysis of central pathology registers and clinical records of patients with thyroid diseases, covering the period 2008–2012, was conducted. A total of 145 cases of thyroid cancers with histological confirmation were registered in the two Wilayahs during the period, with a female to male ratio of 5.9 : 1. Estimates of crude incidence rates suggested that thyroid cancers were twice as frequent in the Wilayah of Guelma compared to El-Taref (p < 0.05) with a tendency to occur at a younger age in resident of the Wilayah of El-Taref. Diagnoses of thyroid adenoma were more frequent in the Wilayah of Guelma, whereas the prevalence of other thyroid lesions, including goitre, was similar in the two Wilayahs. This first descriptive study on geographic variations in thyroid cancer in Northern Africa suggests that significant differences may occur in relation with environmental and lifestyle exposures. PMID:26681943

  16. Paleomagnetic and magnetostructural study of the Gara Djebilet Jurassic magmatic formations (Tindouf Basin, Southwest Algeria)

    NASA Astrophysics Data System (ADS)

    Amira Boussada, Mejda; Merabet, Nacer-eddine; Mahdjoub, Yamina; Maouche, Said; Charaf Chabou, Moulay; Aifa, Tahar; Ayache, Mohamed

    2015-04-01

    Recent geochemical analyses and 40Ar/39Ar dating of dolerite sills and dykes and basalt lava flows in southwestern Algeria (Tindouf, Reggane, Bechar area and Hank basins) showed that these rocks are linked to the Central Atlantic Magmatic Province (CAMP). The later is one of the largest identified Mesozoic basalt provinces formed approximately 200 Ma ago as a preamble to the Pangea dismemberment. These data were strong arguments to undertake geological field observations and a sampling for paleomagnetic and magnetic fabric study in CAMP province formations. Three long doleritic dykes (198.9 ± 1.8 Ma) in the Tindouf basin were targeted in order to point out the structural context of their emplacement (magnetic fabric) and to determine a new reliable Mesozoic pole. The magnetic fabric, in almost the whole sampled sections, is defined mainly by clustering of k1 and k2 axes on the dyke plane whereas the k3 axis is nearly perpendicular to it. This fabric is therefore interpreted as due to magma flow. The new Jurassic paleomagnetic pole, of excellent quality, is very close to those obtained from coeval detrital Algerian Saharan formations and also close to those recently determined from coeval Morrocan igneous formations. It is very close to the 200 Ma mean NW African pole too. These results represent a considerable contribution of to a better knowledge of the geodynamical context during this period.

  17. Trans-Sahara pipe line would deliver Nigeria gas to Europe

    SciTech Connect

    Muenzler, M.H.

    1983-11-01

    Bechtel has made an in-house study of a natural gas transmission line extending from Nigeria to the Mediterranean and then on into Europe. Based upon the analysis, the pipeline project appears sufficiently viable to warrant further study. Perhaps the single most important element in design of pipelines crossing international borders is the political aspects involved in constructing, owning, and operating the line. These considerations not only effect the location of the pipeline, the manner of financing and ownership, but also whether the line will be constructed. The line crosses several international boundaries, depending upon the route selected. Each route crosses Niger. Case A crosses Algeria and into Tunisia where it ultimately would cross the Strait of Sicily into Italy. Case B crosses the Niger- Algerian border and then traverses Algeria to the Mediterranean where it is planned to connect to the Segamo pipeline and to link with the pipeline network in Spain. Case C crosses the countries of Niger, Mali, Mauritania, and into Morocco, and ultimately crosses the Mediterranean Sea close to the Strait of Gibraltar. Nigeria has proven natural gas reserves estimated to range from 2.5 to 4 trillion cu m (38 to 140 tcf).

  18. Predominance of CRF06_cpx and Transmitted HIV Resistance in Algeria: Update 2013-2014.

    PubMed

    Abdellaziz, Akila; Papuchon, Jennifer; Khaled, Safia; Ouerdane, Dalila; Fleury, Hervé; Recordon-Pinson, Patricia

    2016-04-01

    Since 2008, no data on HIV diversity or the transmission rate of HIV resistance mutations in naive patients have been presented for Algeria, a country of MENA region. Between 2013 and 2014, we studied 152 samples including 89 naive patients. The current study describes the change in HIV diversity in Algeria with the predominance of CRF06_cpx and the huge increase of transmitted HIV resistance, which now reaches 15%. PMID:26529365

  19. A Senior High School Social Studies Unit on Africa South of the Sahara. World History Series, Bulletin No. 252.

    ERIC Educational Resources Information Center

    Kelly, Harry; And Others

    This secondary level curriculum guide provides a program and identifies materials for the study of the history and culture of Africa south of the Sahara. The primary purpose of this course is to stimulate thought and to encourage students to make valid generalizations and intelligent assessments of the forces and events that have and are shaping…

  20. Dune ages in the sand deserts of the southern Sahara and Sahel

    NASA Astrophysics Data System (ADS)

    Bristow, Charlie; Armitage, Simon

    2015-04-01

    In this paper we aim to document the history of aeolian processes within the southern Sahara as part of the INQUA Dune Atlas. We review available luminescence ages for sand dunes across the southern Sahara and attempt to correlate periods of sand accumulation and to develop an improved understanding of the dune chronology on a regional basis. This was achieved by analysing dune age by country, as well as by latitude and longitude. The results show a very patchy spatial distribution of dune ages with large gaps that encompass some of the largest sand seas. Despite these gaps, some related patterns in dune morphology and stratigraphy appear to be consistent between northern Nigeria and southern Mali where older linear dunes are distinct from younger Late Holocene transverse and barchanoid dunes. Elsewhere in Mauretania linear dunes with different orientations appear to have accumulated at different times, most likely in response to changes in atmospheric circulation. Regional climatic changes are identified where dunes are transgressed by lake deposits within endorehic basins. We identify four locations where dune accumulation is terminated by lacustrine transgressions, two of which, in Lake Chad and the Bodélé Depression, occur shortly after the last glacial maximum (LGM). The third example at Gobiero in Niger occurred later, in the early Holocene, around 8.4 ka and a fourth marks a later transgression of Palaeolake MegaChad after 4.7 ka. Larger-scale latitudinal and longitudinal distributions in dune ages across the southern Sahara do not show any consistent patterns, though this may due to the small sample size relative to the study area. In addition, local variations in external controls such as wind regime, rainfall, vegetation and sand supply need to be considered, sometimes on a site by site basis. Limiting the analysis to dune ages determined using the single-aliquot regenerative-dose (SAR) protocol indicates a lack of dune preservation during the LGM and

  1. New species of Pseudachorutes (Collembola: Neanuridae) from Northeastern Algeria.

    PubMed

    Zoughailech, Abdelmalek; Hamra-Kroua, Salah; Deharveng, Louis

    2016-01-01

    Three new species of Pseudachorutes are described from the Collo massif in northeastern Algeria, all three with morphological features unique or rare in the genus. P. deficiens sp. nov. lacks chaeta E on the labium, a character only retrieved in P. ouatilouensis Najt & Weiner, 1997 from New Caledonia, from which it differs by the presence of chaeta a2 on Th. II and of chaeta M on tibiotarsus. P. octosensillatus sp. nov. is the only species of the genus that have 8 S-chaetae on Ant IV. P. labiatus sp. nov. has 3 x-papillae on the labium, like P. cf. indiana Christiansen & Bellinger, 1980 from Alaska, from which it differs by the presence of chaeta a2 on Th. II and a lower number of vesicles in PAO (5-6 vs 10-14). PMID:27615903

  2. Adapting to climate change: water distribution in BBA City, Algeria

    NASA Astrophysics Data System (ADS)

    Zeroual, A.; Meddi, M.; Assani, A. A.

    2015-04-01

    For over 20 years, the eastern Algeria region has had significant rainfall deficits that resulted in severe droughts, which seriously affected the availability of water for drinking. Owing to considerations of affordability, drinking water is systematically underpriced because water is essential for life. Such a low price results in water being used inefficiently. This research presents the impact that a high leakage level in the water distribution network has on the water service price in BBA (Bordj Bou Arréridj) city and expected future water resources management scenarios in BBA watersheds by taking into account to the river flow simulated by GR2M using the outputs of climate models with emissions scenarios A1 and A1B. The analysis of the results shows a large economy can be made with regard to water losses, reaching up to 47% saving of the produced water volume; also, BBA city is expected to experience water stress before 2030.

  3. Level of natural and artificial radioactivity in Algeria.

    PubMed

    Baggoura, B; Noureddine, A; Benkrid, M

    1998-07-01

    A national environmental sampling program was carried out during 1993 to determine natural and artificial radionuclides contents in the (0-15 cm) upper layer of the soil. The main objective was to establish a radioactive reference level in the whole territory, since 131I, 134Cs and 137Cs were detected in most of the analysed samples collected right after the Chernobyl accident (May 1986). Soil samples were analysed by direct counting by gamma-ray spectrometry. In addition, terrestrial gamma-ray dose rates in air have been measured out of doors throughout Algeria. In each of the 48 administrative divisions of the country selected sites were chosen to collect soil samples and measure gamma-ray dose rates. The gamma-emitting radionuclides resulting from the radioactive decay of 238U and 232Th, 40K and 137Cs were detected in most of the analysed samples. Radioactivity concentrations in Bq kg-1 dry mass in soil samples of 226Ra, 214Pb, 214Bi, 212Pb, 228Ac, 40K and 137Cs range between (5-176), (2-107), (3-65), (2-97), (3-144), (36-1405) and (0.3-41) respectively. In addition, six selected soil samples were analysed to determine plutonium isotopes contents. Radioactivity concentrations in Bq kg-1 dry mass of 238Pu and 239 + 240Pu vary between (0.012-0.013) and (0.24-0.61) respectively. The dose rates in air measured over the whole country were found to range between 20 and 133 nGy h-1. Presence of 137Cs has been clearly observed. An approach has been made to determine its origin, considering the global fallout, the Chernobyl accident and the French nuclear bomb tests in the 60s as the main potential sources. It is concluded that Algeria has indeed been affected by the Chernobyl accident. PMID:9570102

  4. Initiation and early development of barchan dunes: A case study of the Moroccan Atlantic Sahara desert

    NASA Astrophysics Data System (ADS)

    Elbelrhiti, Hicham

    2012-02-01

    This paper describes field measurements that document the formation of barchan dunes in the Moroccan Atlantic Sahara desert. The first mechanism described is the transformation of patches and proto-dunes at Cap Juby beach to barchan dunes of elementary size. This transformation is discussed in relation to the wind speed and saturation length. The second mechanism is the ejection of small barchans of elementary size by other small barchans in response to the perturbation of the target barchan by two other impacting small barchans. This remote initiation is discussed in relation to the bulk flux transported by the barchan dunes involved in this interaction and to their morphology. Other modes of barchan initiation observed in the field are also presented.

  5. Dust and Biological Aerosols from the Sahara and Asia Influence Precipitation in the Western US

    SciTech Connect

    Creamean, Jessie; Suski, Kaitlyn; Rosenfeld, Daniel; Cazorla, Alberto; DeMott, Paul J.; Sullivan, Ryan C.; White, Allen B.; Ralph, F. M.; Minnis, Patrick; Comstock, Jennifer M.; Tomlinson, Jason M.; Prather, Kimberly

    2013-03-29

    Winter storms in California’s Sierra Nevada increase seasonal snowpack and provide critical water resources for the state. Thus, the mechanisms influencing precipitation in this region have been the subject of research for decades. Previous studies suggest Asian dust enhances cloud ice and precipitation (1), while few studies consider biological aerosols as an important global source of ice nuclei (IN). Here, we show that dust and biological aerosols transported from as far as the Sahara were present in glaciated high-altitude clouds coincident with elevated IN concentrations and ice-induced precipitation. This study presents the first direct cloud and precipitation measurements showing that Saharan and Asian dust and biological aerosols likely serve as IN and play an important role in orographic precipitation processes over the western United States.

  6. Subsurface valleys and geoarcheology of the eastern Sahara revealed by Shuttle radar

    NASA Technical Reports Server (NTRS)

    Mccauley, J. F.; Schaber, G. G.; Breed, C. S.; Grolier, M. J.; Haynes, C. V.; Issawi, B.; Elachi, C.; Blom, R.

    1982-01-01

    Previously unknown buried valleys, geologic structures, and possible Stone Age occupation sites have been revealed through the Shuttle Imaging Radar (SIR-A) penetration of the extremely dry Selima Sand Sheet, dunes and drift sand of the eastern Sahara. Radar penetration of dry sand and soils varies with the wavelength of the incident signals, which is 24 cm for the SIR-A system, as well as incidence angle and electrical properties of the material which are largely determined by moisture content. The calculated depth of radar penetration of dry sand and granules has been established to be 5 m on the basis of laboratory measurements of Selima Sand Sheet sample electrical properties. September 1982 field studies in Egypt have verified SIR-A signal penetration depths of at least 1 m in the Selima Sand Sheet and drift sand, and 2 m or more in sand dunes.

  7. Characterization of potential zones of dust generation at eleven stations in the southern Sahara

    NASA Astrophysics Data System (ADS)

    Clark, I.; Assamoi, P.; Bertrand, J.; Giorgi, F.

    Synoptic wind data for multi-decadal periods at eleven stations located in the southern Sahara region (Agadez, Atar, Bilma, Dori, Gao, Kayes, Nema, Niamey, Nouadhibou, Ouagadougou and Tessalit) are used to study the monthly dust deflation power over the region. We found that, regardless of the conditions of the soil, the deflation power (or wind efficiency) is not sufficient to generate significant amounts of aerosols south of 15°N. North of this latitude, the deflation power is much larger, with potential zones of either very strong deflation (Nouadhibou and Bilma) or severe deflation (Gao, Tessalit, Nema, Atar, Agadez). Stations in the Sahel region such as Gao, Agadez and Tessalit are characterized by a gradual reinforcement of the deflation power between 1970 and 1984 in correspondence of increasing desertification over the region. During this same period, Bilma, a well know region of dust source, experienced a major reduction in deflation power due to shifts in large scale wind patterns.

  8. Dating lacustrine episodes in the eastern Sahara by the epimerization of isoleucine in ostrich eggshells

    USGS Publications Warehouse

    Miller, G.H.; Wendorf, F.; Ernst, R.; Schild, R.; Close, A.E.; Friedman, I.; Schwarcz, H.P.

    1991-01-01

    The eggshell of the African ostrich, Struthio camelus, closely approximates a closed system for the retention of indigenous proteinaceous residues. Epimerization of the protein amino acid isoleucine follows linear first-order kinetics in laboratory simulations nearly to racemic equilibrium, and the variation in D/L ratio within a single fragment, or between fragments of the same age, is significantly less than in other carbonate systems. These observations suggest that the extent of isoleucine epimerization (aIle/Ile ratio) in ostrich eggshell offers the potential for high-resolution geochronology of Quaternary deposits. From the simulation experiments, and dated early Holocene samples for which we have in situ mean annual sediment temperature measurements, Arrhenius parameters have been calculated; the activation energy is 30.33 kcal mol-1, similar to that of other carbonate systems. We have measured the aIle/Ile ratio in ostrich eggshell associated with lacustrine episodes at Bir Tarfawi and Bir Sahara East, two depressions in what is currently the hyperarid eastern Sahara. The ratios can be used directly to indicate qualitatively the time represented by each series of lake sediment, and to correlate disjunct lacustrine deposits within and between the basins. Uranium-series disequilibrium dating of algal mats contained within some of the lake beds indicate that a major wet interval occurred about 130 ka ago. Using the U-series date for calibration, the amino acid ratios are used to date the most recent lacustrine interval to about 100 ka B.P., and two older intervals, one about 200 ?? 25 ka B.P., and an older interval that occurred prior to 250 ka ago. ?? 1991.

  9. Shorelines in the Sahara desert: Archives of the hydrodynamics of Megalake Chad

    NASA Astrophysics Data System (ADS)

    Schuster, Mathieu; Roquin, Claude; Moussa, Abderamane; Duringer, Philippe; Bouchette, Frédéric; Ghienne, Jean-François; Allenbach, Bernard

    2014-05-01

    The African Humid Period corresponds to a major climate change event paced by the orbital parameters of Earth (precession of the equinoxes) with enhanced monsoon regime which has strongly modified the Holocene paleoenvironments of Africa. In sub-tropical north-Africa related reactivation of ancient river networks and the development of numerous lakes, have in turn temporarily favored human occupation of the Sahara. Megalake Chad, which extended over an area swept by the latitudinal fluctuations of the Intertropical convergence zone (ITCZ), represents one of the most emblematic case study of these climate-controlled environmental changes. This very large paleolake had a water-surface of more than 350000 sqkm (10°N-18°N, 12°E-19°E) and maximum depths of ~150 m to the North and of ~40 m in the area of the present-day Lake Chad. Satellite imagery (SRTM, Landsat, Pleiades) over the Chad basin reveals conspicuous clastic morphosedimentary structures which do not correspond to eolian or terrestrial landforms but that clearly correspond to typical coastal features. They include isolated ridges, Azov-type spits, beach ridges, wave-ravinement surface and wave-dominated deltas. These paleoshorelines provide firm outlines of the maximal extension of Megalake Chad and allow to track its size evolution which in turn informs about the precipitation/evaporation budget at basin-scale (~2000000 sqkm). Moreover, the particular shape and distribution of coastal landforms are mostly controlled by the alongshore drift induced by the prevailing winds. Wind-driven hydrodynamics was the major process for clastic sediments redistribution at basin-scale in the nearshore zone and resulted in the building of prominent sedimentary bodies (up to hundreds of kilometer long and few tens of meter thick). As a consequence, paleoshorelines of Megalake Chad represent a record of the paleo-wind regime over the Sahara-Sahel zone which was apparently dominated by an Harmattan-like wind.

  10. Chloroquine retinopathy: pattern of presentation in Ibadan, Sub-Sahara Africa.

    PubMed

    Oluleye, T S; Babalola, Y; Ijaduola, M

    2016-01-01

    BackgroundSelf-medication with chloroquine is common in Ibadan, Sub-Sahara Africa. Retinopathy from chloroquine is not uncommon. The aim was to determine the pattern of presentation.MethodologyCases of Chloroquine retinopathy seen at the Retina and Vitreous Unit of the University College Hospital, Ibadan between 2008 and 2014 were reviewed. Information on age, sex, duration of chloroquine use, and visual loss were retrieved. Visual acuity at presentation, anterior, and posterior segment findings were documented. The results were analyzed using proportions and percentages.ResultsFourteen cases were seen during the study period. Mean age was 50.7 years. Male to female ratio was 3.5 : 1. Average duration of visual loss before presentation was 2.7 years. Average duration of self-medication with chloroquine was 5.3 years. Presenting visual acuity showed 2(14%) cases of bilateral blindness(VA<3/60 in both eyes); 5(35.7%) cases of uniocular blindness; three cases of bilateral low vision(VA worse than 6/18 but better than 3/60). Anterior segment examination showed abnormal sluggish pupillary reaction in those with severe affectation. Dilated fundoscopy showed features ranging from mild macular pigmentary changes and bulls eye maculopathy to overt extensive retinal degeneration involving the posterior pole, attenuation of retinal vessels, optic atrophy, and beaten bronze appearance of atrophic maculopathy.ConclusionChloroquine retinopathy is not uncommon in Ibadan, Sub-Sahara Africa. Bulls eye maculopathy, extensive retinal, and macular degeneration with optic atrophy are the main presentations. Public health education is imperative. PMID:26427986

  11. Petrology and Geochemistry of D'Orbigny, Geochemistry of Sahara 99555, and the Origin of Angrites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Killgore, Marvin; Lee, Michael T.

    2001-01-01

    We have done detailed petrologic study of the angrite, D'Orbigny, and geochemical study of it and Sahara 99555. D'Orbigny is an igneous-textured rock composed of Ca-rich olivine, Al-Ti-diopside-hedenbergite, subcalcic kirschsteinite, two generations of hercynitic spinel and anorthite, with the mesostasis phases ulv6spinel, Ca-phosphate, a silicophosphate phase and Fe-sulfide. We report an unknown Fe-Ca-Al-Ti-silicate phase in the mesostasis not previously found in angrites. One hercynitic spinel is a large, rounded homogeneous grain of a different composition than the euhedral and zoned grains. We believe the former is a xenocryst, the first such described from angrites. The mafic phases are highly zoned; mg# of cores for olivine are approx.64, and for clinopyroxene approx.58, and both are zoned to Mg-free rims. The Ca content of olivine increases with decreasing mg#, until olivine with approx.20 mole% Ca is overgrown by subcalcic kirschsteinite with Ca approx.30-35 mole%. Detailed zoning sequences in olivine-subcalcic kirschsteinite and clinopyroxene show slight compositional reversals. There is no mineralogic control that can explain these reversals, and we believe they were likely caused by local additions of more primitive melt during crystallization of D'Orbigny. D'Orbigny is the most ferroan angrite with a bulk rock mg# of 32. Compositionally, it is virtually identical to Sahara 99555; the first set of compositionally identical angrites. Comparison with the other angrites shows that there is no simple petrogenetic sequence, partial melting with or without fractional crystallization, that can explain the angrite suite. Angra dos Reis remains a very anomalous angrite. Angrites show no evidence for the brecciation, shock, or impact or thermal metamorphism that affected the HED suite and ordinary chondrites. This suggests the angrite parent body may have followed a fundamentally different evolutionary path than did these other parent bodies.

  12. Microbial diversity and organic matter fractions under two arid soils in Algerian Sahara

    NASA Astrophysics Data System (ADS)

    Karabi, Mokhtar; Hamdi, Aissa Baelhadj; Zenkhri, Salah

    2016-07-01

    The Algerian Sahara is characterized by a heterogeneity of edaphic conditions and climatic dissimilarities; however, information on biological indicators of arid soils is weakly documented in this area. The researchers who have studied the biological activities of the soils of the arid regions have underlined their low organic matter content, particularly their very low rates of organic nitrogen; a low humification because seriously inhibited by a significant mineralization. The objective of the current work is to study the microbial biomass densities and organic matter fractions for different types of soil, under two arid soil in Algerian Sahara. The experiment was conducted in an alluvial soil in traditional palm grove of Guerrara, and in a saline soil in experimental field of university of Ouargla. Composite soil samples (10 subsamples each) were collected aseptically at 0-20 cm depth on two diagonal transects drawn over an area of 12 ha. The following germs densities were determined: Bacteria, Fungi and Actinomycetes. The soil organic matter fractions, the textural fractions, chemical attributes (organic C, total N, total limestone and gypsum) were also determined. The microbial groups count on both soils reveals that the bacterianmicroflora present a numerical superiority followed by the actinomycetes and finally fungi. The micro-organisms densities except fungal density, showed a prevalence of the bacterianmicroflora, and actinomycetes in alluvial soil compared to saline soil. Fractionation of soil organic matter show that all fractions are better represented in alluvial soil except non-extractable organic carbon (NEOC) which are better represented in saline soil. This confirms that alluvial soil has a relatively large biological activity than saline soil and that humification process is relatively pronounced by comparing it with the saline soil, which tends to contain little polycondenseshumic compounds.

  13. Gradual aridification of the Sahara during the last 11,000 years revealed by plant wax δD analyses of Lake Yoa (Chad)

    NASA Astrophysics Data System (ADS)

    Rethemeyer, Janet; Kröpelin, Stefan; Karls, Jens; Thienemann, Matthias; Melles, Martin; Schefuß, Enno

    2014-05-01

    It is still an ongoing debate whether the transition of the last 'green Sahara' period to today's large desert during the Holocene, the African Humid Period (AHP), was a progressive or an abrupt change in hydrological conditions. Several climate records mainly from East Africa suggest a rapid decline of moisture availability at the end of the AHP including new data from a marine sequence off the Horn of Africa (Tierney & deMenocal, 2013). Other archives including sedimentological, geochemical and palynological data from the central North African Lakes Chad and Lake Yoa point to a gradual rather than an abrupt transition near 5,000 years ago (Amaral et al., 2013; Kröpelin et al., 2008). The discrepancy of the available paleo-hydrological reconstructions underline the importance of proxy parameters directly related to hydrological conditions for accurate assessment of continental rainfall changes. Here, we present the first molecular-isotopic data from Lake Yoa documenting the hydrologic evolution over the entire Holocene. Compound-specific carbon and hydrogen isotope analyses were performed on long-chain n-alkanes. Our data indicate relative high but variable contributions of plant-derived long-chain n-alkanes carrying a distinct leaf-wax signature, i.e., a high Carbon Preference Index (CPI). A trend towards higher CPI values since 7,300 years ago suggests declining soil degradation and vegetation cover under increasingly drier conditions. In parallel, the average-chain-length of the long-chain n-alkanes increases gradually towards the present implying higher relative contributions from grasses. Compound-specific carbon isotope data confirm this finding, indicating a mixed C3/C4 contribution in the early and mid-Holocene changing towards a C4-grass dominated vegetation in the late Holocene. Most importantly, compound-specific hydrogen isotope data reveal a continuous increase from 8,100 years ago towards the present, reflecting a gradual aridification. The large

  14. Forsterite and Olivine in Sahara-97210 (LL3.2) and Chainpur (LL3.4) Chondrules: Compositional Evolution and the Influence of Melting

    NASA Technical Reports Server (NTRS)

    Ruzicka, A.; Floss, C.

    2004-01-01

    It is generally accepted that chondrules contain relict grains that did not crystallize in situ, and that forsterite is one type of relict grain which is a likely precursor for chondrules. Chemically and morphologically similar forsterite is also found as "isolated grains", especially in carbonaceous chondrites. Using SIMS, we analyzed forsterite, ferrous overgrowths around forsterite, and coexisting normal olivine in 5 chondrules and 2 isolated grains in the Sahara-97210 ('Sahara") LL3.2 chondrite. We earlier used the same methods to study olivine in 3 Chainpur chondrules that contain relict forsterite. Our new data for Sahara provide additional insight into the processes affecting chondrules and their precursors.

  15. The Sahara from the Middle Jurassic to the Middle Cretaceous: Data on environments and climates based on outcrops in the Algerian Sahara

    NASA Astrophysics Data System (ADS)

    Busson, G.; Cornée, A.

    The period investigated, succeeded the Upper Triassic and Liassic-Lower Dogger arid sedimentation which was characterized by the development of large evaporitic deposits. The north-eastern part of the Algerian Sahara is specially interesting as it constitutes part of the few dated continental Jurassic outcrops in North Africa (except in the Maghreb). Continental Lower-Middle Cretaceous is also well developed in the same region. The grading of these continental series into marine series particularly in the north-eastern part of the Maghreb has been investigated from an adequate number of well spaced wells. The Middle-Upper Jurassic (Lower Taouratine) consists of an argillaceous-sandy-ferruginous series, often grey coloured and rich in filicean wood and vertebrate remains in some levels. The ferralitic alteration products denote a more humid climate than that which prevailed during the Liassic-Lower-Dogger times. These products alternate with sandy conglomeratic events confirming the influences of alternating important run-off and aeolian winnowing. The large continental Lower and Middle Cretaceous detrital nappes are discussed. They constitute the uppermost part of the series, south of the Tinrhert Hamada (Alba-Vraconian series with the more detrital lateral equivalent), west of Tademait (Gara Samani). Data on lithology and paleobiology (fishes, Dinosaurs, other vertebrates, pelecypods, gastropods, wood debris, palynoflora) permit the reconstruction of the palaeo-environment and the conditions of deposition. This is similar to the sub-desertic terrestrial sedimentation by violent and ephemeral hydrodynamism model based on the modern Darfour example. The desertic conditions which prevailed in these Saharan areas during the Cretaceous are reflected as well as their possible consequences on the sedimentation of nearby oceanic areas (Atlantic and Tethys). This detrital sedimentation is finally reviewed in the context of its tectonic origins and an attempt is made to

  16. Triticale development in Algeria: genetic gains through decades.

    PubMed

    Abdelkader, Benbelkacem; Fatiha, Sadli

    2014-01-01

    Algeria started working on triticale since the late seventies, it was first as a scientific curiosity (1974-1980), the production of this crop began in the early eighties and expanded well for a decade (10.000ha) then decreased for another decade due to lack of subsidies and serious interest from decision makers putting all their effort in wheat production which is the predominant crop in the country. Since the 1990s up to date, it is developing again mainly based on feed market requirements (20.500ha in 2001) and a better consideration by stakeholders. Triticale is now developed by the informal seed system. Triticale is grown in Algeria under a wide range of soil and climatic conditions, including dryland and marginal soils. Under high input and rainfall environments, the best triticale cultivars have comparable grain yield with wheat but slightly lower to barley. This advantage is larger under dry conditions. Our study was dealing with an evaluation of the progress made in time since their introduction and selection of triticale varieties. The study was conducted on twenty five varieties and advanced lines, selected in the different phases of triticale development, during the three last seasons (2009 - 2012) in two contrasting regions (semi arid and high input environment) showed very interesting results and a linear improvement in grain yield and its components, and also in the feeding quality traits. The improvement was apparent in both sites; although result data was higher in number in the high input environment, the increase rate was larger in the semi arid area of study. In the favorable area, grain yield increased from 2.94t/ha for the varieties developed in the early phase (late 1970s), to 3.98t/ha for the varieties released in the second phase (1990s) up to 5.45t/ha for the latest varieties developed in the 2000s. Grain yield increased in the dry area from 2.42t/ha to 4.92t/ha. The trend is almost the same for all yield components and even for forage

  17. An Exploration of Foreign Language Teachers' Beliefs about Curriculum Innovation in Algeria: A Socio-Political Perspective

    ERIC Educational Resources Information Center

    Bellalem, Fouzi

    2008-01-01

    Recent political and economic developments in Algeria have brought about reforms of the educational system. A new curriculum was introduced as part of these reforms. This study explores the beliefs of French and English school teachers about curriculum innovation in Algeria. The study is positioned in the qualitative research tradition and looks…

  18. Partaking in the global movement for occupational mental health: what challenges and ways forward for sub-Sahara Africa?

    PubMed Central

    2012-01-01

    There is an ongoing global movement for the entrenchment of occupational mental health as an integral part of occupational health and safety schemes. Aside from being a fundamental human right issue, this move has been demonstrated to be of cost-benefit in terms of workplace productivity and general economic growth. Despite being among the regions most prone to the human and economic repercussions of work-related mental health problems by reason of her socio-economic circumstance; sub-Sahara Africa is yet to fully plug into this movement. With a view to make recommendations on the ways forward for sub-Sahara Africa, this paper examines the current state of and the barriers to effective occupational mental health policy and practice in the region. PMID:22958579

  19. Geochemical and mineralogical evidence for Sahara and Sahel dust additions to Quaternary soils on Lanzarote, eastern Canary Islands, Spain

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.; Skipp, G.; Prospero, J.M.; Patterson, D.; Bettis, E. Arthur, III

    2010-01-01

    Africa is the most important source of dust in the world today, and dust storms are frequent on the nearby Canary Islands. Previous workers have inferred that the Sahara is the most important source of dust to Canary Islands soils, with little contribution from the Sahel region. Soils overlying a late Quaternary basalt flow on Lanzarote, Canary Islands, contain, in addition to volcanic minerals, quartz and mica, exotic to the island's bedrock. Kaolinite in the soils also likely has an exotic origin. Trace-element geochemistry shows that the soils are derived from varying proportions of locally derived basalt and African dust. Major-element geochemistry, clay mineralogy and interpretation of satellite imagery suggest that dust additions to the Canary Islands come not only from the Sahara Desert, but also from the Sahel region. ?? Published 2010. This article is a US Government work and is in the public domain in the USA.

  20. Raman spectroscopic studies of the skins of the Sahara sand viper, the carpet python and the American black rat snake

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Farwell, D. W.; Williams, A. C.; Barry, B. W.

    1993-07-01

    Vibrational Raman spectra of the skins of the snakes Cerastes vipera (Sahara sand viper) and Morelia argus (carpet python) have been recorded for the first time using visible and IR laser excitation. Full vibrational assignments are proposed and comparisons made with vibrational Raman spectra of the snake Elaphe obsoleta (American black rat snake); such studies may be important in correlating the permeabilities of human and snake skins to drugs and contaminants.

  1. Trypanosomiasis of camels (Camelus dromedarius) in Algeria: First report.

    PubMed

    Bennoune, Omar; Adili, Nezar; Amri, Khaled; Bennecib, Lakhdar; Ayachi, Ammar

    2013-01-01

    Camel trypanosomosis is a life-threatening disease in the camel species and responsible for severe economic losses either in milk or meat productions. This study was carried out on the south-east area of Algeria on 100 camels of various ages and either sex from two herds. Microscopic examination of blood smears revealed higher levels of trypanosomosis caused by Trypanosoma evansi, an elongated parasite with a kinetoplast and a single nucleus located in its half-length and one flagellum with great heterogeneity. This first investigation reveals higher infection rate than those observed in other countries using blood smears, the trypanosomosis attack has reached an alarming level and the occurrence of trypanosomosis at this high level on blood smears is like "the tree that hides the forest" and make up a serious and potential danger both on animal and public health. Therefore, radical preventive and offensive drastic measures must be taken against this menacing disease at the critical points to prevent the economic losses and to avoid possible human transmission. PMID:25568684

  2. Trypanosomiasis of camels (Camelus dromedarius) in Algeria: First report

    PubMed Central

    Bennoune, Omar; Adili, Nezar; Amri, Khaled; Bennecib, Lakhdar; Ayachi, Ammar

    2013-01-01

    Camel trypanosomosis is a life-threatening disease in the camel species and responsible for severe economic losses either in milk or meat productions. This study was carried out on the south-east area of Algeria on 100 camels of various ages and either sex from two herds. Microscopic examination of blood smears revealed higher levels of trypanosomosis caused by Trypanosoma evansi, an elongated parasite with a kinetoplast and a single nucleus located in its half-length and one flagellum with great heterogeneity. This first investigation reveals higher infection rate than those observed in other countries using blood smears, the trypanosomosis attack has reached an alarming level and the occurrence of trypanosomosis at this high level on blood smears is like "the tree that hides the forest" and make up a serious and potential danger both on animal and public health. Therefore, radical preventive and offensive drastic measures must be taken against this menacing disease at the critical points to prevent the economic losses and to avoid possible human transmission. PMID:25568684

  3. The 2003 Boumerdes, Algeria earthquake: Regional moment tensor analysis

    NASA Astrophysics Data System (ADS)

    Braunmiller, Jochen; Bernardi, Fabrizio

    2005-03-01

    We used regional broadband seismograms to determine seismic moment tensors for the destructive May 21, 2003 Boumerdes (Algeria) Mw = 7.0 earthquake and its larger aftershocks. Fully automatic inversions using near-real time data provided solutions for seven Mw >= 4.7 events within 90 minutes after event occurrence. After adding off-line data, we manually obtained 30 solutions (Mw >= 3.8) from May 2003 to January 2004. All have shallow source depths (6-21 km). The median P-axis orientation (338°) of 24 thrust and four strike-slip events is consistent with Africa-Eurasia plate motion (330°). The main shock hypocenter at 8-10 km depth at the coastline and its shallow southward dip (25° +/- 5°) puts the fault surface trace 15-20 km offshore, consistent with documented seafloor deformation at the base of the continental slope. A main shock rupture length of about 50 km is deduced from first day aftershocks and location of strike-slip events. The strike-slip events probably define the western rupture end and indicate a left-step of main convergence. Fault strike variability of thrust events suggests fault orientation changes and possibly fault segmentation.

  4. Sahara dust, ocean spray, volcanoes, biomass burning: pathways of nutrients into Andean rainforests

    NASA Astrophysics Data System (ADS)

    Fabian, P.; Rollenbeck, R.; Spichtinger, N.; Brothers, L.; Dominguez, G.; Thiemens, M.

    2009-10-01

    Regular rain and fogwater sampling in the Podocarpus National Park, on the humid eastern slopes of the Ecuadorian Andes, along an altitude profile between 1960 and 3180 m, has been carried out since 2002. The samples, accumulated over about 1-week intervals, were analysed for pH, conductivity and major ions (K+, Na+, NH4+, Ca2+, Mg2+, Cl-, SO42-, NO3-, PO43-). About 35% of the weekly samples had very low ion contents, with pH mostly above 5 and conductivity below 10 μS/cm. 10-days back trajectories (FLEXTRA) showed that respective air masses originated in pristine continental areas, with little or no obvious pollution sources. About 65%, however, were significantly loaded with cations and anions, with pH as low as 3.5 to 4.0 and conductivity up to 50 μS/cm. The corresponding back trajectories clearly showed that air masses had passed over areas of intense biomass burning, active volcanoes, and the ocean, with episodic Sahara and/or Namib desert dust interference. Enhanced SO42- and NO3+ were identified, by combining satellite-based fire pixel observations with back trajectories, as predominantly resulting from biomass burning. Analyses of oxygen isotopes 16O, 17O, and 18O in nitrate show that nitrate in the samples is indeed a product of atmospheric conversion of precursors. Some SO42-, about 10% of the total input, could be identified to originate from active volcanoes, whose plumes were encountered by about 10% of all trajectories. Enhanced Na+, K+, and Cl- were found to originate from ocean spray sources. They were associated with winds providing Atlantic air masses to the receptor site within less than 5 days. Episodes of enhanced Ca2+ and Mg2+ were found to be associated with air masses from African deserts. Satellite aerosol data confirm desert sources both on the Northern (Sahara) as on the Southern Hemisphere (Namib), depending on the season. A few significant PO43- peaks are related with air masses originating from North African phosphate mining fields.

  5. Streptomonospora algeriensis sp. nov., a halophilic actinomycete isolated from soil in Algeria.

    PubMed

    Meklat, Atika; Bouras, Noureddine; Riba, Amar; Zitouni, Abdelghani; Mathieu, Florence; Rohde, Manfred; Schumann, Peter; Spröer, Cathrin; Klenk, Hans-Peter; Sabaou, Nasserdine

    2014-08-01

    A halophilic actinomycete strain, designated H27(T), was isolated from a soil sample collected from a hypersaline habitat in Djelfa Province (North-Central Algeria), and then investigated using a polyphasic taxonomic approach. The strain was observed to produce poor aerial mycelium, which formed short chains of oval to cylindrical-shaped spores at maturity, and non fragmented substrate mycelium. The optimum NaCl concentration for growth was found to be 10-15 % (w/v) and the optimum growth temperature and pH were found to be 28-37 °C and 6-7, respectively. The diagnostic diamino acid in the cell-wall peptidoglycan was identified as meso-diaminopimelic acid. The predominant menaquinones of strain H27(T) were identified as MK-11 (H4) and MK-10 (H6). The major fatty acids were found to be iso-C16:0, anteiso-C17:0, 10 methyl C17:0 and 10 methyl C16:0. The diagnostic phospholipids detected were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and phosphatidylinositol. The chemotaxonomic properties of strain H27(T) are consistent with those shared by members of the genus Streptomonospora. 16S rRNA gene sequence analysis indicated that strain H27(T) is most closely related to Streptomonospora alba DSM 44588(T) (98.8 %) and Streptomonospora flavalba DSM 45155(T) (98.7 %) whereas the DNA-DNA relatedness values between strain H27(T) and the two type strains were 17.1 and 57.9 %, respectively. Based on the combined genotypic and phenotypic evidence, it is proposed that strain H27(T) should be classified as representative of a novel species, for which the name Streptomonospora algeriensis sp. nov. is proposed. The type strain is H27(T) (=DSM 45604(T) =CCUG 63369(T) =MTCC 11563(T)). PMID:24858572

  6. Ecological Analysis of Deserti Fication Processes in Semi Arid Land in Algeria Using Satellite Data

    NASA Astrophysics Data System (ADS)

    Zegrar, Ahmed

    2016-07-01

    Desertification, a phenomenon of loss of productivity of the land is both a matter of Environment and Development (Cornet, 2002). It is linked to the anthropogenic action and to climate variability but also to changes in biodiversity, in particular the Maghreb (Hobbs et al., 1995). The desertification of the steppe areas of North Africa (Algeria, Morocco and Tunisia) is considered of special concern by the specialists in these regions. Desertification, Climate Change and the erosion of biodiversity are the central issues for the development of arid, semi-­arid. In this region, the combination of two factors, climatic and anthropogenic, has fostered a deterioration of the vegetation cover, soil erosion and the scarcity of water resources. The climate of this region is characterized by periods of recurring droughts since the 1970s. The anthropogenic pressure is the result of a combination of factors among which the strong demographic growth, the intensification and extension of production systems agro-­pastoral or still further the concentration of a growing livestock on smaller spaces. In this study, the criteria for classification and identification of physical parameters for spatial ecological analysis of vegetation in the steppe region to determine the degradation and vulnerability vegetation formations and how to conduct to phenomenon of desertification. So we use some satellite data in different dates (LANDSAT) in order to determine the ecological of steppe formation and changes in land cover, sand moving and forest deterioration. The application of classification and some arithmetic combination with NDVI and MSAVI2 through specific processes was used to characterize the main steppe formations. An ecological analysis of plant communities and impact of sand move describe the nature of the desertification phenomenon and allow us to determine the impact of factors of climate and entropic activity in the Algerian steppe.

  7. Heat shock protein synthesis and thermotolerance in Cataglyphis, an ant from the Sahara desert.

    PubMed Central

    Gehring, W J; Wehner, R

    1995-01-01

    The ant Cataglyphis lives in the Sahara desert and is one of the most thermotolerant land animals known. It forages at body temperatures above 50 degrees C, and the critical thermal maxima are at 53.6 +/- 0.8 degrees C for Cataglyphis bombycina and 55.1 +/- 1.1 degrees C for Cataglyphis bicolor. The synthesis and accumulation of heat shock proteins (HSPs) were analyzed in Cataglyphis and compared to Formica, an ant living in more moderate climates, and to two Drosophila species. In Cataglyphis, protein synthesis continues at temperatures up to 45 degrees C as compared to 39 degrees C for Formica and Drosophila. The two Drosophila species, Drosophila melanogaster and Drosophila ambigua, differ with respect to their maximal induction of HSP synthesis and accumulation by 3-4 degrees C. In contrast, the two ant species accumulate HSPs prior to their exposure to heat, and in Cataglyphis the temperature of maximal HSP induction by de novo protein synthesis is only 2 degrees C higher than in Formica. These findings are interpreted as preadaption of the ants prior to exposure to high temperatures. Images Fig. 1 Fig. 2 Fig. 3 PMID:7708762

  8. TL and ESR of quartz from the astrobleme of Aorounga (Sahara of Chad)

    NASA Astrophysics Data System (ADS)

    Miallier, D.; Sanzelle, S.; Falguères, C.; Faïn, J.; Pilleyre, Th.; Vincent, P. M.

    The present work was intended to evaluate the time that elapsed since the meteorite fall that produced the giant astrobleme of Aorounga (Sahara of Chad). For this purpose the TL and ESR dating techniques using the additive dose method were applied to quartz grains extracted from an impactite and from a sandstone shocked and baked during the impact. The ESR Al centre was measured and resulted in an age of about 800 ka. The red TL and the blue TL showed unusual TL features: the additive dose response curves were marked by an initial saturated part followed by a second rise at around +0.5 kGy; the peaks showed erratic temperature shifts with dose; fading was observed for high temperature peaks. By comparison with previous work using samples baked by lava flows more than 1 Ma ago and presenting some of those features, it was assumed that the minimum age of the astrobleme was of the same order of magnitude. This is in agreement with other observations. A preliminary explanation for those ageing features is proposed. It is suspected that radiation induced traps contribute to the TL of the studied quartz grains. Most probably the 'malign-behaviour' of the quartz grains is also connected with shock effects.

  9. SHUTTLE IMAGING RADAR: PHYSICAL CONTROLS ON SIGNAL PENETRATION AND SUBSURFACE SCATTERING IN THE EASTERN SAHARA.

    USGS Publications Warehouse

    Schaber, Gerald G.; McCauley, John F.; Breed, Carol S.; Olhoeft, Gary R.

    1986-01-01

    It is found that the Shuttle Imaging Radar A (SIR-A) signal penetration and subsurface backscatter within the upper meter or so of the sediment blanket in the Eastern Sahara of southern Egypt and northern Sudan are enhanced both by radar sensor parameters and by the physical and chemical characteristics of eolian and alluvial materials. The near-surface stratigraphy, the electrical properties of materials, and the types of radar interfaces found to be responsible for different classes of SIR-A tonal response are summarized. The dominant factors related to efficient microwave signal penetration into the sediment blanket include 1) favorable distribution of particle sizes, 2) extremely low moisture content and 3) reduced geometric scattering at the SIR-A frequency (1. 3 GHz). The depth of signal penetration that results in a recorded backscatter, called radar imaging depth, was documented in the field to be a maximum of 1. 5 m, or 0. 25 times the calculated skin depth, for the sediment blanket. The radar imaging depth is estimated to be between 2 and 3 m for active sand dune materials.

  10. Microbial Diversity of the Hypersaline Sidi Ameur and Himalatt Salt Lakes of the Algerian Sahara

    PubMed Central

    Boutaiba, Saad; Hacene, Hocine; Bidle, Kelly A.; Maupin-Furlow, Julie A.

    2011-01-01

    Microbial populations within hypersaline lakes often exhibit high activities of photosynthesis, dissimilatory sulphate reduction and other processes and, thus, can have profound impacts on biogeochemical cycles of carbon, nitrogen, sulphur and other important elements within arid lands. To further understand these types of ecosystems, the physicochemical and biological properties of Sidi Ameur and Himalatt Salt Lakes in the Algerian Sahara were examined and compared. Both lakes were relatively neutral in pH (7.2 to 7.4) and high in salt, at 12% and 20 % (w/v) salinity for Himalatt and Sidi Ameur Lakes, respectively, with dominant ions of sodium and chloride. The community compositions of microbes from all three domains (Bacteria, Archaea and Eukarya) were surveyed through the use of 16S and 18S ribosomal gene amplification and clone library clustering using amplified ribosomal DNA restriction analysis (ARDRA) in conjunction with DNA sequencing and analysis. A high level of microbial diversity, particularly among the bacteria of the Himalatt Salt Lake and archaea of Sidi Ameur Lake, was found within these environments. Representatives from all known halophilic bacterial phyla as well as 6 different genera of halophilic archaea were identified. Moreover, several apparently novel phylotypes among both archaea and bacteria were revealed. PMID:21909172

  11. Ecoclimate Teleconnections: Remote Control of the Mid-Holocene Green Sahara

    NASA Astrophysics Data System (ADS)

    Swann, A. L.; Fung, I.; Chiang, J. C.

    2011-12-01

    The mid-Holocene climate of Northern Africa was characterized by wetter conditions than present, as evidenced by higher paleo lake-levels and pollen assemblages of savannah vegetation suggesting a wetter, greener Sahara. Differences in orbital forcing and local vegetation have been proposed to explain the existence of savannah vegetation as far north as 23 N but climate model simulations have had difficultly reproducing sufficient precipitation over Northern Africa. We propose that remote forcing from forest cover in the mid latitudes is capable of pulling the Intertropical Convergence Zone northward, and, in conjunction with orbital forcing and forcing from local vegetation, explains the enhanced precipitation over Northern Africa ~6000 years ago. We use climate model simulations to show the relative importance of local and remote vegetation and discuss the mechanisms by which mid latitude vegetation influences sub tropical precipitation and productivity. The forcing of North African precipitation and therefore local productivity by mid latitude vegetation highlights a bi-directional interaction between ecosystems and climate.

  12. Airborne Fungi in Sahara Dust Aerosols Reaching the Eastern Caribbean: II. Species Identification Using Molecular Techniques

    NASA Astrophysics Data System (ADS)

    de La Mota, A.; Betancourt, C.; Detres, Y.; Armstrong, R.

    2003-12-01

    Fungi samples from filters collected in Castle Bruce, Dominica from March through July 2002, were previously purified and identified to genus level using classic macroscopic and microscopic techniques. A total of 105 isolated colonies were cultured in liquid media and the mycelial mats used for DNA extraction. PCR was used to amplify the ITS region of the rDNA using the ITS1 and ITS4 primers. Both strands of the amplified products were sequenced and the final identification to species level was completed by a GenBank search. Fourteen different species and one fungal endophyte were identified from genders Aspergillus,Penicillium, Fusarium, Cladosporium, Curvularia and Phanerochaete. Some of these species such as A. fumigatus, A. japonicus, P. citrinum and C. cladosporoides are known to cause respiratory disorders in humans. A. fumigatus causes an aggressive pulmonary allergic response that might result in allergic bronchopulmonary aspergillosis. Other species such as F. equiseti and C. brachyspora are plant pathogens affecting economically important crops. Sahara dust is an important source of fungal spores of species that are not common in the Caribbean region.

  13. Dynamics of Green Sahara Periods and Their Role in Hominin Evolution

    PubMed Central

    Larrasoaña, Juan C.; Roberts, Andrew P.; Rohling, Eelco J.

    2013-01-01

    Astronomically forced insolation changes have driven monsoon dynamics and recurrent humid episodes in North Africa, resulting in green Sahara Periods (GSPs) with savannah expansion throughout most of the desert. Despite their potential for expanding the area of prime hominin habitats and favouring out-of-Africa dispersals, GSPs have not been incorporated into the narrative of hominin evolution due to poor knowledge of their timing, dynamics and landscape composition at evolutionary timescales. We present a compilation of continental and marine paleoenvironmental records from within and around North Africa, which enables identification of over 230 GSPs within the last 8 million years. By combining the main climatological determinants of woody cover in tropical Africa with paleoenvironmental and paleoclimatic data for representative (Holocene and Eemian) GSPs, we estimate precipitation regimes and habitat distributions during GSPs. Their chronology is consistent with the ages of Saharan archeological and fossil hominin sites. Each GSP took 2–3 kyr to develop, peaked over 4–8 kyr, biogeographically connected the African tropics to African and Eurasian mid latitudes, and ended within 2–3 kyr, which resulted in rapid habitat fragmentation. We argue that the well-dated succession of GSPs presented here may have played an important role in migration and evolution of hominins. PMID:24146882

  14. Dynamics of green Sahara periods and their role in hominin evolution.

    PubMed

    Larrasoaña, Juan C; Roberts, Andrew P; Rohling, Eelco J

    2013-01-01

    Astronomically forced insolation changes have driven monsoon dynamics and recurrent humid episodes in North Africa, resulting in green Sahara Periods (GSPs) with savannah expansion throughout most of the desert. Despite their potential for expanding the area of prime hominin habitats and favouring out-of-Africa dispersals, GSPs have not been incorporated into the narrative of hominin evolution due to poor knowledge of their timing, dynamics and landscape composition at evolutionary timescales. We present a compilation of continental and marine paleoenvironmental records from within and around North Africa, which enables identification of over 230 GSPs within the last 8 million years. By combining the main climatological determinants of woody cover in tropical Africa with paleoenvironmental and paleoclimatic data for representative (Holocene and Eemian) GSPs, we estimate precipitation regimes and habitat distributions during GSPs. Their chronology is consistent with the ages of Saharan archeological and fossil hominin sites. Each GSP took 2-3 kyr to develop, peaked over 4-8 kyr, biogeographically connected the African tropics to African and Eurasian mid latitudes, and ended within 2-3 kyr, which resulted in rapid habitat fragmentation. We argue that the well-dated succession of GSPs presented here may have played an important role in migration and evolution of hominins. PMID:24146882

  15. Characterization and antimicrobial potential of extremely halophilic archaea isolated from hypersaline environments of the Algerian Sahara.

    PubMed

    Quadri, Inès; Hassani, Imene Ikrame; l'Haridon, Stéphane; Chalopin, Morgane; Hacène, Hocine; Jebbar, Mohamed

    2016-01-01

    Halophilic archaea were isolated from different chotts and sebkha, dry salt lakes and salt flat respectively, of the Algerian Sahara and characterized using phenotypic and phylogenetic approaches. From 102 extremely halophilic strains isolated, forty three were selected and studied. These strains were also screened for their antagonistic potential and the production of hydrolytic enzymes. Sequencing of the 16S rRNA genes and phylogenetic analysis allowed the identification of 10 archaeal genera within the class Halobacteria: Natrinema (13 strains), Natrialba (12 strains), Haloarcula (4 strains), Halopiger (4 strains), Haloterrigena (3 strains), Halorubrum (2 strains), Halostagnicola (2 strains), Natronococcus, Halogeometricum and Haloferax (1 strain each). The most common producers of antimicrobial compounds belong to the genus Natrinema while the most hydrolytic isolates, with combined production of several enzymes, belong to the genus Natrialba. The strain affiliated to Halopiger djelfamassilliensis was found to produce some substances of interest (halocins, anti-Candida, enzymes). After partial purification and characterization of one of the strains Natrinema gari QI1, we found similarities between the antimicrobial compound and the halocin C8. Therefore, the gene encoding halocin C8 was amplified and sequenced. PMID:27242149

  16. Satellite imagery and airborne geophysics for geologic mapping of the Edembo area, Eastern Hoggar (Algerian Sahara)

    NASA Astrophysics Data System (ADS)

    Lamri, Takfarinas; Djemaï, Safouane; Hamoudi, Mohamed; Zoheir, Basem; Bendaoud, Abderrahmane; Ouzegane, Khadidja; Amara, Massinissa

    2016-03-01

    Satellite imagery combined with airborne geophysical data and field observations were employed for new geologic mapping of the Edembo area in the Eastern Hoggar (Tuareg Shield, Sahara). Multi-spectral band fusion, filtering, and transformation techniques, i.e., band combination, band-rationing and principal component analysis of ETM+ and ASTER data are used for better spectral discrimination of the different rocks units. A thematic map assessed by field data and available geologic information is compiled by supervised classification of satellite data with high overall accuracy (>90%). The automated extraction technique efficiently aided the detection of the structural lineaments, i.e., faults, shear zones, and joints. Airborne magnetic and Gamma-ray spectrometry data showed the pervasiveness of the large structures beneath the Paleozoic sedimentary cover and aeolian sands. The aeroradiometric K-range is used for discrimination of the high-K granitoids of Djanet from the peralumineous granites of Edembo, and to verify the Silurian sediments with their high K-bearing minerals. The new geological map is considered to be a high resolution improvement on all pre-existing maps of this hardly accessible area in the Tuareg Shield. Integration of the airborne geophysical and space-borne imagery data can hence provide a rapid means of geologically mapping areas hitherto poorly known or difficult to access.

  17. Diatom-inferred salinity and carbonate oxygen isotopes in Holocene waterbodies of the western Sahara and Sahel (Africa)

    NASA Astrophysics Data System (ADS)

    Gasse, Françoise

    2002-03-01

    Thirteen Holocene palaeolakes in the western Sahara and Sahel have provided diatom records, with carbonate oxygen isotope profiles available from eight of them. Most of these palaeolakes were groundwater-fed. Lake water chemistry is reconstructed using diatom transfer functions. Lake water salinity and 18O records are assembled with some isotopic and chemical groundwater data to better understand the response of the hydrological systems to climate changes over the past 15,000 yr. Data are in general agreement with climate simulations using coupled atmosphere-ocean-vegetation models which show a mid-Holocene wetting over the whole of northwest Africa, and a rapid drying by 6-4 ka. The lake record also shows that at many sites the major lake infilling lags the end of the Younger Dryas by 1-2 ka. Regional differences also appear in the timing of the lake hydrological optimum: ca. 10.5-8.5 and 7.5-4.5 ka in the northern Sahara, 10-8.5 ka in the Aı̈r-Ténéré, 10-5.7 or 4.5 in the Sahel, and 7.5 ka in Lake Chad. The whole of the Holocene is punctuated by short-term drying events. Changes in water isotopic composition through time are partly explained by changes in rainfall amount and air humidity. During the wet Holocene period however, the very low δ values in the southern Sahara also imply changes in the moisture transport pattern or rainfall mechanisms. Data suggest an apparent decrease in 18O content of precipitation along the monsoon flow, in contrast with modern patterns. Changes in water availability and quality have driven population migrations in and out of the Sahara-Sahel, but relationships between climate and cultures are complex. Short-term dry events might have driven inventive adaptations. In the Sahara, drying at 5-4.5 ka coincides with both the collapse of the classical Neolithic civilization and the settlement of new cultures.

  18. Kamikazes: youth serving youth in a dangerous climate. Algeria.

    PubMed

    Gataa, R

    1995-01-01

    The Algerian Family Planning Association (FPA) launched its youth project in July 1993 in Oran. The first project of its kind in the Arab world, members call themselves Kamikazes in recognition of the hostile climate they face. The project's goal was to deal with social, cultural, and health problems. They also designed the project's logo, a cartoon booklet on the dangers of AIDS, and a T-shirt for members to wear. They based their activities in the local government-run information center. Between 15 and 25 years old, from a wide variety of social backgrounds, the young people drew up a list of common problems: drugs, alcohol, smoking, relationships with the opposite sex, abortion, contraception, sex education, AIDS, homosexuality, unemployment, the lack of clubs for young people, delinquency, lack of communication between parents and children, the repression of women, the lack of popular entertainment for young people, and the shortage of books. This project now is to be extended to Algiers and other cities. Over an 8-month period, the committee received instruction in contraception and combatting drug addition, participated in a workshop on empowerment and self esteem, and were trained in role-playing techniques. In their first 18 months of existence, the Kamikazes in Oran have succeeded in involving over 1000 of their peers. They have had particular success in reaching teenagers in secondary schools. One of the most valuable aspects of the project has been the sessions held with gynecologists and psychologists on sexual development, relationships between the sexes, and the avoidance of unwanted pregnancies, abortion, and sexually transmitted diseases. The success of the Oran Kamikaze project bodes well for the extension of the project to other parts of Algeria and indeed to some other countries of the Arab world. PMID:12319368

  19. Palaeozoic gas charging in the Ahnet-Timimoun basin, Algeria

    SciTech Connect

    Cawley, S.J.; Wilson, N.P.; Primmer, T.

    1995-08-01

    The Ahnet-Timimoun Basin, Southern Algeria, contains significant gas reserves expelled from originally oil prone Silurian and Frasnian shales. The gas is reservoired in Devonian and Carboniferous clastics in inversion anticlines formed, primarily, during the Hercynian orogeny. Integration of organic and inorganic geochemical techniques, such as AFTA, ZFTA, fluid inclusion analysis, vitrinite and chitinizoan reflectance, is entirely consistent with gas generation 300 +/- 30MY, immediately prior to or synchronous with the Hercynian orogeny. Data from gas fields has shown the remobilisation of gas during post Hercynian tectonics. A {open_quotes}two-event{close_quotes} heating/cooling history is proposed: (1) Maximum burial and palaeotemperature at ca. 300 +/- 30MY prior to or synchronous with Hercynian uplift and cooling. (2) Cooling from a secondary peak (lower than maximum) palaeotemperature at ca. 30-60My following Creataceous burial. Calibrated thermal modelling indicates that Palaeozoic source rocks were heated above 200{degrees}C in the Late Carboniferous. Such high temperatures are consistent with the widespread occurrence of pyrophyllite in Silurian shales. Two end-member thermal models can account for the observed maturities. The first is a constant high Pre-Hercynian heat flow which rapidly decreases during Hercynian uplift to remain at Present day values of 50-75mW/m{sup 2}. Gas expulsion in this case commences much earlier than trap formation. The second is {open_quotes}normal{close_quotes} heat flow of ca. 50mW/m{sup 2} until ca. 310My with a rapid increase at ca. 290My followed by an equally rapid drop to constant present day values - in this model, petroleum generation and expulsion is late in relation to structuring.

  20. Natural radionuclide concentrations in two phosphate ores of east Algeria.

    PubMed

    Lakehal, Ch; Ramdhane, M; Boucenna, A

    2010-05-01

    Ore is considered as an important source of many elements such as the iron, phosphorus, and uranium. Concerning the natural radionuclides, their concentrations vary from an ore to other depending on the chemical composition of each site. In this work, two phosphate ores found in East of Algeria have been chosen to assess the activity concentration of natural radionuclides represented mainly by three natural radioactive series (238)U, (235)U and (232)Th, and the primordial radionuclide (40)K where they were determined using ultra-low background, high-resolution gamma-ray spectroscopy. The measured activity concentrations of radioactive series ranged from 6.2 +/- 0.4 to 733 +/- 33 Bq.kg(-1) for the (232)Th series, from 249 +/- 16 to 547 +/- 39 Bq.kg(-1) for the (238)U series, around 24.2 +/- 2.5 Bq.kg(-1) for the (235)U series, and from 1.4 +/- 0.2 to 6.7 +/- 0.7 Bq.kg(-1) for (40)K. To assess exposure to gamma radiation in the two ores, from specific activities of (232)Th, (40)K and (226)Ra, three indexes were determined: Radium equivalent (Ra(eq)), external and internal hazard indexes (H(ex) and H(in)), their values ranged from 831 +/- 8 to 1298 +/- 14 Bq.kg(-1) for Ra(eq), from 2.2 +/- 0.4 to 3.5 +/- 0.7 Bq.kg(-1) for H(ex), and from 4.2 +/- 0.7 to 4.5 +/- 0.7 Bq.kg(-1) for H(in). PMID:20303630

  1. Gender discrimination for women with diabetes mellitus in Algeria

    PubMed Central

    Chentli, Farida; Azzoug, Said; Meskine, Djamila; El Gradechi, Aldjia

    2014-01-01

    Background: Nowadays diabetes mellitus (DM) is one of the greatest global challenges. Its expansion varies from an area to another according to genetic, traditions, socio-economic conditions, and stress. In Algeria, as in other emerging countries undergoing an epidemiological transition, noncommunicable diseases are sharply increasing. After high blood pressure, DM is now the second metabolic disease. But are women more concerned by DM since obesity frequency is higher in females? Can we assert that there is a sort of sex discrimination for DM complications? Materials and Methods: To answer these questions we took into account published documents carried in Algerian population. But, as those were very scarce, we also considered newspapers articles, some documents published by health minister department, posters and oral communications of the Algerian Society of Endocrinology and Diabetology, and our clinical experience. We also have done a small survey to get our patients’ opinions. Results and Conclusion: At the first sight, it seems gender discrimination between men and women cannot exist since most epidemiological studies showed that both sexes are broadly and equally affected by DM, except for old aged females who are the most affected. When we reconsidered the problem, and when we compared past results to those obtained after the terrorism period, many studies showed a sort of gender difference. Apart from gestational DM, which is increasing sharply, some complications and death related to DM are prevailing in women. Coronary diseases and cerebral vascular accidents are more frequent in women too, especially the young ones and those suffering from DM. These complications are probably due to the recent and rapid modification in women's lifestyle with a strong reduction in physical activity, eating disorders, hormonal contraception, and high sensitivity to perceived stress secondary to the near past stressing life and/or to numerous responsibilities taken by

  2. Libya, Algeria and Egypt: crude oil potential from known deposits

    SciTech Connect

    Dietzman, W.D.; Rafidi, N.R.; Ross, T.A.

    1982-04-01

    An analysis is presented of the discovered crude oil resources, reserves, and estimated annual production from known fields of the Republics of Libya, Algeria, and Egypt. Proved reserves are defined as the remaining producible oil as of a specified date under operating practice in effect at that time and include estimated recoverable oil in undrilled portions of a given structure or structures. Also included in the proved reserve category are the estimated indicated additional volumes of recoverable oil from the entire oil reservoir where fluid injection programs have been started in a portion, or portions, of the reservoir. The indicated additional reserves (probable reserves) reported herein are the volumes of crude oil that might be obtained with the installation of secondary recovery or pressure maintenance operations in reservoirs where none have been previously installed. The sum of cumulative production, proved reserves, and probable reserves is defined as the ultimate oil recovery from known deposits; and resources are defined as the original oil in place (OOIP). An assessment was made of the availability of crude oil under three assumed sustained production rates for each country; an assessment was also made of each country's capability of sustaining production at, or near, the 1980 rates assuming different limiting reserve to production ratios. Also included is an estimate of the potential maximum producing capability from known deposits that might be obtained from known accumulations under certain assumptions, using a simple time series approach. The theoretical maximum oil production capability from known fields at any time is the maximum deliverability rate assuming there are no equipment, investment, market, or political constraints.

  3. Seroprevalence, distribution and risk factor for peste des petits ruminants (PPR) in Algeria.

    PubMed

    Kardjadj, Moustafa; Kouidri, Brahim; Metref, Djamil; Luka, Pam Dachung; Ben-Mahdi, Meriem Hind

    2015-11-01

    Peste des petit ruminants (PPR) is a highly contagious and infectious viral disease of small ruminants with severe socio-economic implications. The disease was first reported in the Southern part of Algeria in 2011 and by February 2012 it has reached the central part of the country. Estimating national prevalence, distribution and identification of risk factors remains a key component in understanding the epidemiology and control of the disease. The present study was carried out between January and June 2014, to include a detailed description of flock and within-flock seroprevalence and risk association between PPR seropositivity and various flock management factors in Algeria. A total of 150 flocks randomly sampled across the country were investigated and 4552 serum samples were collected from 3336 sheep and 1216 goats, respectively. C-ELISA was used to detect the presence of antibodies in small ruminant animals as an indicator of PPRV exposure. The results showed an overall true flock seroprevalence of 30.45% [95% CI 23.76-37.14] with a mean of the true within-flock prevalence as 29.87%±2.11. The mean of the true within-flock prevalence in mixed flocks (12.93%±1.85) was however found to be significantly higher than sheep flocks (5.74%±1.06). Also the mean of the true within-flock prevalence was found to be significantly higher in adult (35.36%±3.13) compared to young animals (21.83%±2.47) and in females (33.11%±2.87) compared to males (22.14%±2.31). The univariate analysis revealed that PPR overall flock seroprevalence was significantly higher (P<0.20) in large flock (50.61%) than in small flock (33.33%), in mixed flock (56.7%) than in sheep flock (35.35%) and in the flocks that had contact with other flocks (46.5%) compared to those who had not (30.6%). However the differences among studied regions and grazing system were not statistically significant. For the risk factor analysis, univariate analysis of variables followed by a multiple logistic

  4. Oil in the Sahara: mapping anthropogenic threats to Saharan biodiversity from space.

    PubMed

    Duncan, Clare; Kretz, Daniela; Wegmann, Martin; Rabeil, Thomas; Pettorelli, Nathalie

    2014-01-01

    Deserts are among the most poorly monitored and understood biomes in the world, with evidence suggesting that their biodiversity is declining fast. Oil exploration and exploitation can constitute an important threat to fragmented and remnant desert biodiversity, yet little is known about where and how intensively such developments are taking place. This lack of information hinders local efforts to adequately buffer and protect desert wildlife against encroachment from anthropogenic activity. Here, we investigate the use of freely available satellite imagery for the detection of features associated with oil exploration in the African Sahelo-Saharan region. We demonstrate how texture analyses combined with Landsat data can be employed to detect ground-validated exploration sites in Algeria and Niger. Our results show that site detection via supervised image classification and prediction is generally accurate. One surprising outcome of our analyses is the relatively high level of site omission errors in Niger (43%), which appears to be due to non-detection of potentially small-scale, temporary exploration activity: we believe the repeated implementation of our framework could reduce the severity of potential methodological limitations. Overall, our study provides a methodological basis for the mapping of anthropogenic threats associated with oil exploitation that can be conducted across desert regions. PMID:24733946

  5. Oil in the Sahara: mapping anthropogenic threats to Saharan biodiversity from space

    PubMed Central

    Duncan, Clare; Kretz, Daniela; Wegmann, Martin; Rabeil, Thomas; Pettorelli, Nathalie

    2014-01-01

    Deserts are among the most poorly monitored and understood biomes in the world, with evidence suggesting that their biodiversity is declining fast. Oil exploration and exploitation can constitute an important threat to fragmented and remnant desert biodiversity, yet little is known about where and how intensively such developments are taking place. This lack of information hinders local efforts to adequately buffer and protect desert wildlife against encroachment from anthropogenic activity. Here, we investigate the use of freely available satellite imagery for the detection of features associated with oil exploration in the African Sahelo-Saharan region. We demonstrate how texture analyses combined with Landsat data can be employed to detect ground-validated exploration sites in Algeria and Niger. Our results show that site detection via supervised image classification and prediction is generally accurate. One surprising outcome of our analyses is the relatively high level of site omission errors in Niger (43%), which appears to be due to non-detection of potentially small-scale, temporary exploration activity: we believe the repeated implementation of our framework could reduce the severity of potential methodological limitations. Overall, our study provides a methodological basis for the mapping of anthropogenic threats associated with oil exploitation that can be conducted across desert regions. PMID:24733946

  6. Uranium isotopes in groundwater from the continental intercalaire aquifer in Algerian Tunisian Sahara (Northern Africa).

    PubMed

    Chkir, N; Guendouz, A; Zouari, K; Hadj Ammar, F; Moulla, A S

    2009-08-01

    The disequilibrium between (234)U and (238)U is commonly used as a tracer of groundwater flow. This paper aims to identify uranium contents and uranium isotopic disequilibria variation in groundwater sampled from deep Continental Intercalaire aquifer (southern Algeria and Tunisia). Large variations in both U contents (0.006-3.39ppb) and (234)U/(238)U activity ratios (0.4-15.38) are observed. We conduct a first assessment in order to verify whether the results of our investigation support and complete previous hydrogeological and isotopic studies. The dissolved U content and (234)U/(238)U activity ratio data were plotted on a two-dimensional diagram that was successfully utilized on sharing the CI aquifer into different compartments submitted to different oxidising/reducing conditions and leads also to distinguished two preferential flow paths in the Nefzaoua/Chott Fejej discharge area. Uranium isotopes disequilibrium indicate that ranium chemistry is mainly controlled by water-rock interaction enhanced by long residence time recognised for this aquifer. PMID:19559509

  7. Orthodontic treatment need in a 12-year-old population in the Western Sahara.

    PubMed

    Puertes-Fernández, Neus; Montiel-Company, José María; Almerich-Silla, José Manuel; Manzanera, David

    2011-08-01

    The aim of this study was to establish orthodontic treatment need according to the Dental Aesthetic Index (DAI) and Aesthetic Component (AC) and Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN) and to determine its association with gender among Saharan schoolchildren. The study was carried out in accordance with World Health Organization (WHO) recommendations for oral health surveys at 12 years of age. The sample comprised 248 Sahrawi children (135 girls and 113 boys) living in refugee camps in Tindouf, Algeria. None of the children had previously received any orthodontic treatment. A chi-square test was used to analyse the IOTN results by gender, and a Student's t-test was employed for the DAI results. The mean DAI was 23.32 with a standard deviation of 6.05, 4 percent with a very severe and 9.2 per cent with severe malocclusion. Orthodontic treatment need was 16.1 and 2.0 percent, respectively, according to grades 4 and 5 of the IOTN DHC, 13.7 percent according to the IOTN AC, and 28.6 percent according to the modified IOTN (IOTN DHC grades 4-5 and/or IOTN AC grades 8-10). There were no statistically significant differences by gender. The orthodontic treatment need of Western Saharan schoolchildren is similar to that reported by many recent studies in European and in Sub-Saharan countries. PMID:20926555

  8. Cost-effectiveness of pre-participation screening of athletes with ECG in Europe and Algeria.

    PubMed

    Assanelli, Deodato; Levaggi, Rosella; Carré, François; Sharma, Sanjay; Deligiannis, Asterios; Mellwig, Klaus Peter; Tahmi, Mohamed; Vinetti, Giovanni; Aliverti, Paola

    2015-03-01

    The aim of this study is to evaluate the cost-effectiveness of ECG in combination with family and personal history and physical examination in order to detect cardiovascular diseases that might cause sudden death in athletes. The study was conducted on a cohort of 6,634, mainly young professional and recreational athletes, 1,071 from Algeria and 5,563 from Europe (France, Germany and Greece). Each athlete underwent medical history, physical examination, and resting 12-lead ECG. 293 athletes (4.4 %), 149 in Europe (2.7 %) and 144 in Algeria (13.4 %) required further tests, and 56 were diagnosed with cardiovascular disease and thus disqualified. The cost-effectiveness ratio (CER) was calculated as the ratio between the cost of screening and the number of statistical life-years saved by the intervention. The estimated reduced risk of death deriving from treatment or disqualification resulted in the saving of 79.1 statistical life-years in Europe and 136.3 in Algeria. CER of screening was 4,071 purchasing-power-parity-adjusted US dollars ($PPP) in Europe and 582 $PPP in Algeria. The results of this study strongly support the utilisation of 12-lead ECG in the pre-participation screening of young athletes, especially in countries where secondary preventive care is not highly developed. PMID:25164412

  9. Helping to Meet Today's Energy Demands: Natural Gas Technician Training in Algeria

    ERIC Educational Resources Information Center

    Dutton, Bernard

    1976-01-01

    The training program, located in Arzew, Algeria, is designed to train technicians in all phases of gas technology. The program provides classroom instruction, on-the-job training, and language instruction. The different phases involved in the training program are described. (EC)

  10. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 6, Number 2, 1972.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    Annotations of articles, written in English, provide the content for an annotated bibliography of educational materials written in French useful to those with an interest in North Africa. Sections on Algeria, Libya, Morocco, and Tunisia cover topics such as the philosophy and theory of education, educational organization, adult education, teacher…

  11. Selected Bibliography of Educational Materials: Maghreb, Algeria, Libya, Morocco, Tunisia. Vol. 10, No. 4, 1976.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    Ninety-one English language annotations are presented of newspaper articles and government publications about education in Algeria, Libya, Morocco, and Tunisia. Most of the entries were published during the period October-December 1976. Organized by country, the references cover topics of philosophy and theory of education, teacher training,…

  12. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 8, Number 1, 1974.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    This annotated bibliography contains 100 English-language annotations of newspapers and government publications covering educational topics of interest to North Africans. The majority of the items cited were published in 1974. Citations are categorized by country: Algeria, Libya, Morocco, and Tunisia. Within these major categories are subtopics…

  13. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Vol. 4 No. 3, 1970.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine, Comp.; And Others

    This report, part of a series of educational bibliographies from the Maghreb countries (Algeria, Morocco, and Tunisia) and Libya, consists of excerpts from periodicals published in those countries. Each entry is marked to indicate the particular country. The articles are organized under 13 major subjects that include: the structure of educational…

  14. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Vol. 1 No. 3 1967.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    This annotated compilation of 108 educational publications in Arabic, French, and English includes texts and data on elementary and secondary school curricula in the Maghreb countries (Tunisia, Morroco, Algeria, and Libya). Categories in this bibliography include--(1) Philosophy and Theory of Education, (2) Administration of the Educational…

  15. Selected Bibliography of Educational Materials: Maghreb, Algeria, Libya, Morocco, Tunisia. Vol. 9, No. 3, 1975.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine, Comp.; And Others

    The bibliography presents 91 English language annotations of newspaper articles, journals, and government publications about education in Algeria, Libya, Morocco, and Tunisia. Although the title also includes Maghreb, this issue does not contain any annotations for that country. All articles were published during the period July-September 1975.…

  16. Selected Bibliography of Materials; Algeria, Libya, Morocco, Tunisia. Volume 1, Number 2, 1967.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A bibliography with abstracts of 106 items from books and articles covers materials on education in the Maghreb countries of Tunisia, Libya, Algeria, and Morocco. Special emphasis is given to the two problems besetting the area's educational system: illiteracy and multilingualism. The entries cover philosophy and theory of education,…

  17. Classification of non-Hodgkin lymphoma in Algeria according to the World Health Organization classification.

    PubMed

    Boudjerra, Nadia; Perry, Anamarija M; Audouin, Josée; Diebold, Jacques; Nathwani, Bharat N; MacLennan, Kenneth A; Müller-Hermelink, Hans K; Bast, Martin; Boilesen, Eugene; Armitage, James O; Weisenburger, Dennis D

    2015-04-01

    The relative distribution of non-Hodgkin lymphoma (NHL) subtypes differs markedly around the world. The aim of this study was to report this distribution in Algeria. A panel of four hematopathologists classified 197 consecutive cases according to the World Health Organization classification, including 87.3% B-cell and 12.7% T- or natural killer (NK)-cell NHLs. This series was compared with similar cohorts from Western Europe (WEU) and North America (NA). Algeria had a significantly higher frequency of diffuse large B-cell lymphoma (DLBCL: 52.8%) and a lower frequency of follicular lymphoma (FL: 13.2%) compared with WEU (DLBCL: 32.2%; FL: 20.0%) and NA (DLBCL: 29.3%; FL: 33.6%). The frequency of mantle cell lymphoma was lower in Algeria (2.5%) compared with WEU (8.3%). Smaller differences were also found among the NK/T-cell lymphomas. In conclusion, we found important differences between Algeria and Western countries, and further epidemiologic studies are needed to explain these differences. PMID:25012941

  18. Evidence of rift valley fever seroprevalence in the Sahrawi semi-nomadic pastoralist system, Western Sahara

    PubMed Central

    2014-01-01

    Background The increasing global importance of Rift Valley fever (RVF) is clearly demonstrated by its geographical expansion. The presence of a wide range of host and vector species, and the epidemiological characteristics of RVF, have led to concerns that epidemics will continue to occur in previously unaffected regions of Africa. The proximity of the Sahrawi territories of Western Sahara to endemic countries, such as Mauritania, Senegal, and Mali with periodic isolation of virus and serological evidence of RVF, and the intensive livestock trade in the region results in a serious risk of RVF spread in the Sahrawi territories, and potentially from there to the Maghreb and beyond. A sero-epidemiological survey was conducted in the Saharawi territories between March and April 2008 to investigate the possible presence of the RVF virus (RVFV) and associated risk factors. A two-stage cluster sampling design was used, incorporating 23 sampling sites. Results A total of 982 serum samples was collected from 461 sheep, 463 goats and 58 camels. Eleven samples (0.97%) tested positive for IgG against the RVFV. There were clusters of high seroprevalence located mostly in the Tifariti (7.69%) and Mehaires (7.14%) regions, with the Tifariti event having been found in one single flock (4/26 positive animals). Goats and older animals were at a significantly increased risk being seropositive (p = 0.007 and p = 0.007, respectively). Conclusion The results suggest potential RVF activity in the study area, where intense livestock movement and trade with neighbouring countries might be considered as a primary determinant in the spread of the disease. The importance of a continuous field investigation is reinforced, in light of the risk of RVF expansion to historically unaffected regions of Africa. PMID:24758592

  19. Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations

    NASA Astrophysics Data System (ADS)

    Ryder, C. L.; McQuaid, J. B.; Flamant, C.; Washington, R.; Brindley, H. E.; Highwood, E. J.; Marsham, J. H.; Parker, D. J.; Todd, M. C.; Banks, J. R.; Brooke, J. K.; Engelstaedter, S.; Estellés, V.; Formenti, P.; Garcia-Carreras, L.; Kocha, C.; Marenco, F.; Rosenberg, P.; Sodemann, H.; Allen, C. J. T.; Bourdon, A.; Bart, M.; Cavazos-Guerra, C.; Chevaillier, S.; Crosier, J.; Darbyshire, E.; Dean, A. R.; Dorsey, J. R.; Kent, J.; O'Sullivan, D.; Schepanski, K.; Szpek, K.; Woolley, A.

    2015-01-01

    The Fennec climate program aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE Falcon 20 is described, with specific focus on instrumentation specially developed and relevant to Saharan meteorology and dust. Flight locations, aims and associated meteorology are described. Examples and applications of aircraft measurements from the Fennec flights are presented, highlighting new scientific results delivered using a synergy of different instruments and aircraft. These include: (1) the first airborne measurement of dust particles sized up to 300 microns and associated dust fluxes in the Saharan atmospheric boundary layer (SABL), (2) dust uplift from the breakdown of the nocturnal low-level jet before becoming visible in SEVIRI satellite imagery, (3) vertical profiles of the unique vertical structure of turbulent fluxes in the SABL, (4) in-situ observations of processes in SABL clouds showing dust acting as CCN and IN at -15 °C, (5) dual-aircraft observations of the SABL dynamics, thermodynamics and composition in the Saharan heat low region (SHL), (6) airborne observations of a dust storm associated with a cold-pool (haboob) issued from deep convection over the Atlas, (7) the first airborne chemical composition measurements of dust in the SHL region with differing composition, sources (determined using Lagrangian backward trajectory calculations) and absorption properties between 2011 and 2012, (8) coincident ozone and dust surface area measurements suggest coarser particles provide a route for ozone depletion, (9) discrepancies between airborne coarse mode size distributions and AERONET sunphotometer retrievals under

  20. Crop drying by indirect active hybrid solar - Electrical dryer in the eastern Algerian Septentrional Sahara

    SciTech Connect

    Boughali, S.; Bouchekima, B.; Mennouche, D.; Bouguettaia, H.; Bechki, D.; Benmoussa, H.

    2009-12-15

    In the present work, a new specific prototype of an indirect active hybrid solar-electrical dryer for agricultural products was constructed and investigated at LENREZA Laboratory, University of Ouargla (Algerian Sahara). In the new configuration of air drying passage; the study was done in a somewhat high range of mass flow rate between 0.04 and 0.08 kg/m{sup 2} s a range not properly investigated by most researchers. Experimental tests with and without load were performed in winter season in order to study the thermal behavior of the dryer and the effect of high air masse flow on the collector and system drying efficiency. The fraction of electrical and solar energy contribution versus air mass flow rate was investigated. Slice tomato was studied with different temperatures and velocities of drying air in order to study the influence of these parameters on the removal moisture content from the product and on the kinetics drying and also to determine their suitable values. Many different thin layer mathematical drying models were compared according to their coefficient of determination (R{sup 2}) and reduced chi square ({chi}{sup 2}) to estimate experimental drying curves. The Middli model in this condition proved to be the best for predicting drying behavior of tomato slice with (R{sup 2} = 0.9995, {chi}{sup 2} = 0.0001). Finally an economic evaluation was calculated using the criterion of payback period which is found very small 1.27 years compared to the life of the dryer 15 years. (author)

  1. Analysis of available measures for malaria control in Africa south of the Sahara.

    PubMed

    Goriup, S

    1989-01-01

    Africa south of the Sahara is not homogeneous and presents several extreme conditions where malaria persistence is ensured by a complex and highly adaptable vector system. Plasmodium falciparum is the most widespread and life threatening of the malaria parasites of man, particularly for young children and pregnant women. Large-scale residual spraying was not totally effective and was very costly, and mass chemoprophylaxis was not feasible. The spread of chloroquine resistance added arguments against uncontrolled use of drugs. Chemoprophylaxis is now recommended only for pregnant women, especially in their first pregnancy, whilst chloroquine 25 mg base/kg over 3 days is recommended for curative treatment in villages. Second line treatment regimens should be available, together with the possibility of referring severe malaria cases quickly to appropriate clinical facilities. Other control measures include self-protection against mosquito bites by bednets (especially those impregnated with synthetic pyrethroids), mosquito coils, repellents, window and door screening; other measures to prevent man-mosquito contact, such as careful siting of settlements and zooprophylaxis; anti-larval measures, i.e. source reduction, protection of wells and water reservoirs, larviciding, introduction of larvivorous fish; and sprays against adult mosquitoes. The elaboration of strategies for control and their application requires a study of the existing situation. A core of specialists is required in each country, to help with decentralized planning and evaluation of malaria control and to ensure quality control of services, training and applied field research. Additional measures may become available in the future, especially anti-malaria vaccines, and countries should be ready to study their application. PMID:2696165

  2. A forest butterfly in sahara desert oases: isolation does not matter.

    PubMed

    Habel, Jan Christian; Husemann, Martin; Schmitt, Thomas; Dapporto, Leonardo; Rödder, Dennis; Vandewoestijne, Sofie

    2013-03-01

    Numerous studies addressing the impact of habitat fragmentation on genetic diversity have been performed. In this study, we analyze the effects of a seemingly nonpermeable matrix on the population structure of the forest-dwelling butterfly Pararge aegeria in geographically isolated oases at the northern margin of the Sahara desert using microsatellites, morphological characters, and species distribution modeling. Results from all analyses are mostly congruent and reveal 1) a split between European and North African populations, 2) rather low divergence between populations from the eastern and western part of North Africa (Morocco vs. Tunisia), 3) a lack of differentiation between the oasis and Atlas Mountain populations, 4) as well as among the oasis populations, and 5) no reduction of genetic variability in oasis populations. However, one exception to this general trend resulted from the analyses of wing shape; wings of butterflies from oases are more elongated compared with those from the other habitats. This pattern of phenotypic divergence may suggest a recent colonization of the oasis habitats by individuals, which might be accompanied by a rather dispersive behavior. Species distribution modeling suggests a fairly recent reexpansion of the species' climatic niche starting in the Holocene at about 6000 before present. The combined results indicate a rather recent colonization of the oases by highly mobile individuals from genetically diverse founder populations. The colonization was likely followed by the expansion and persistence of these founder populations under relatively stable environmental conditions. This, together with low rates of gene flow, likely prevented differentiation of populations via drift and led to the maintenance of high genetic diversity. PMID:23132908

  3. The Sahara-East Mediterranean dust and climate connection revealed by strontium and uranium isotopes in a Jerusalem speleothem

    NASA Astrophysics Data System (ADS)

    Frumkin, Amos; Stein, Mordechai

    2004-01-01

    This paper explores the potential of Sr and U isotope systems in speleothems as tracers of eolian dust transport and hydrological conditions. The study focuses on a speleothem from Jerusalem spanning the past 220 kyr. This speleothem provides a precisely dated record of dust flux from the Sahara to the East Mediterranean. Enhanced dust flux and Terra Rossa soil development are reflected by elevated 87Sr/ 86Sr ratios in the speleothem (0.7082-0.7086), while lower 87Sr/ 86Sr ratios (˜0.7078) indicate higher contribution of the local bedrock due to low dust flux and low soil accumulation. The strontium isotope system in the speleothem is a robust monitor of the Sahara monsoon-modulated climate, since dust uptake is related to development or reduction in vegetation cover of Sahara soil. The [ 234U/ 238U] activity ratios in the speleothem range between 1.12 and 1.0. The high activity values may indicate selective removal of 234U from the soil while the low values converge to the bedrock. The migration of 234U to the cave reflects mainly the regional hydrological conditions that are modulated by the North Atlantic-Mediterranean climate system. Thus, the speleothem provides a combined record of the monsoon-North Atlantic climatic systems. Long-term stability in glacial 87Sr/ 86Sr ratios (0.7083±0.0001 over the past 220 kyr) suggests an overall similarity in eolian dust sources, and uniformity in the synoptic conditions that dominate the dust storm tracks during glacial periods.

  4. Revision of the genus Thyreocephalus and description of Afrus gen. nov. of Africa south of the Sahara (Coleoptera: Staphylinidae: Staphylininae).

    PubMed

    Janák, Jiří; Bordoni, Arnaldo

    2015-01-01

    A revision of the genus Thyreocephalus Guérin-Méneville, 1844 of Africa south of the Sahara is presented. A new genus Afrus gen. nov. was described with the type species Thyreocephalus spegazzinii Bernhauer, 1915, which resulted in following new combination: Afrus spegazzinii (Bernhauer, 1915), comb. nov. Eulissus collarti (Cameron, 1932) was transferred to Afrus. Based on a revision of types and of additional material, 32 species of the genus Thyreocephalus and two species of the genus Afrus are recognized in Africa south of the Sahara. All species are described or redescribed and illustrated, seven of them for the first time: Thyreocephalus camerunensis sp. nov., T. manfredi sp. nov., T. marginipennis sp. nov., T. meridioafricanus sp. nov., T. pseudoafricanus sp. nov., T. subcorticalis sp. nov. and T. tsingidianus sp. nov. Neotypes are designated for Eulissus ater Laporte, 1835, Xantholinus coeruleipennis Quedenfeldt, 1881, and X. interocularis Eppelsheim, 1895. Lectotypes are designated for Eulissus atlanticus Bernhauer, 1915, E. burgeoni Bernhauer, 1929, E. mokaensis Bernhauer, 1915, E. secretus Bernhauer, 1935, E. turneri Bernhauer, 1937, Xantholinus alluaudi Fauvel, 1907, X. mocquerysi Fauvel, 1903, X. pilosus Roth, 1851, Thyreocephalus diversiceps Bernhauer, 1936, and T. spegazzinii Bernhauer, 1915. Eulissus africanus Bernhauer, 1913, E. alluaudi (Fauvel, 1907) (originally described in Xantholinus Dejean, 1821), E. atlanticus Bernhauer, 1915, E. brunneiventris Tottenham, 1956, E. burgeoni Bernhauer, 1929, E. guineensis Bernhauer, 1912, E. mokaensis Bernhauer, 1915, E. secretus Bernhauer, 1935, E. strinatii Scheerpeltz, 1958, and Xantholinus nairobiensis Fauvel, 1907 were transferred to Thyreocephalus. Following synonymies are proposed: Thyreocephalus nairobiensis (Fauvel, 1907) = Eulissus turneri Bernhauer, 1937, syn. nov., Thyreocephalus interocularis (Eppelsheim, 1895) = Thyreocephalus diversiceps Bernhauer, 1936, syn. nov., Thyreocephalus mokaensis

  5. Lagrangian dust model simulations for a case of moist convective dust emission and transport in the western Sahara region during Fennec/LADUNEX

    NASA Astrophysics Data System (ADS)

    Sodemann, H.; Lai, T. M.; Marenco, F.; Ryder, C. L.; Flamant, C.; Knippertz, P.; Rosenberg, P.; Bart, M.; McQuaid, J. B.

    2015-06-01

    Due to the harshness and inaccessibility of desert regions, the uncertainties concerning the processes of dust mobilization at the surface, airborne transport, and sedimentation are still considerable, limiting the ability to perform model simulations. In June 2011, a comprehensive data set of ground-based and airborne in situ measurements and remote sensing observations was acquired within the Fennec/Lagrangian Dust Source Inversion Experiment (LADUNEX) field campaign in the western Sahara region. Here we evaluate the ability of the state-of-the-art Lagrangian particle dispersion model FLEXPART, newly fitted with a dust mobilization capability, to simulate dust transport in this region. We investigate a case where a large mesoscale convective system (MCS) triggered dust emissions in central Mali, which subsequently moved as a large cold pool dust front toward northern Mauritania. Specifying dust mobilization for this case is shown to be an important obstacle to simulating dust transport during this event, since neither the MCS nor the associated cold pool-causing dust emission is represented in the meteorological analysis. Obtaining a realistic dust transport simulation for this case therefore requires an inversion approach using a manual specification of the dust sources supported by satellite imagery. When compared to in situ and remote sensing data from two aircraft, the Lagrangian dust transport simulations represent the overall shape and evolution of the dust plume well. While accumulation and coarse mode dust are well represented in the simulation, giant mode particles are considerably underestimated. Our results re-emphasize that dust emission associated with deep moist convection remains a key issue for reliable dust model simulations in northern Africa.

  6. Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations

    NASA Astrophysics Data System (ADS)

    Ryder, C. L.; McQuaid, J. B.; Flamant, C.; Rosenberg, P. D.; Washington, R.; Brindley, H. E.; Highwood, E. J.; Marsham, J. H.; Parker, D. J.; Todd, M. C.; Banks, J. R.; Brooke, J. K.; Engelstaedter, S.; Estelles, V.; Formenti, P.; Garcia-Carreras, L.; Kocha, C.; Marenco, F.; Sodemann, H.; Allen, C. J. T.; Bourdon, A.; Bart, M.; Cavazos-Guerra, C.; Chevaillier, S.; Crosier, J.; Darbyshire, E.; Dean, A. R.; Dorsey, J. R.; Kent, J.; O'Sullivan, D.; Schepanski, K.; Szpek, K.; Trembath, J.; Woolley, A.

    2015-07-01

    The Fennec climate programme aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE (Service des Avions Français Instrumentés pour la Recherche en Environnement) Falcon 20 is described, with specific focus on instrumentation specially developed for and relevant to Saharan meteorology and dust. Flight locations, aims and associated meteorology are described. Examples and applications of aircraft measurements from the Fennec flights are presented, highlighting new scientific results delivered using a synergy of different instruments and aircraft. These include (1) the first airborne measurement of dust particles sizes of up to 300 microns and associated dust fluxes in the Saharan atmospheric boundary layer (SABL), (2) dust uplift from the breakdown of the nocturnal low-level jet before becoming visible in SEVIRI (Spinning Enhanced Visible Infra-Red Imager) satellite imagery, (3) vertical profiles of the unique vertical structure of turbulent fluxes in the SABL, (4) in situ observations of processes in SABL clouds showing dust acting as cloud condensation nuclei (CCN) and ice nuclei (IN) at -15 °C, (5) dual-aircraft observations of the SABL dynamics, thermodynamics and composition in the Saharan heat low region (SHL), (6) airborne observations of a dust storm associated with a cold pool (haboob) issued from deep convection over the Atlas Mountains, (7) the first airborne chemical composition measurements of dust in the SHL region with differing composition, sources (determined using Lagrangian backward trajectory calculations) and absorption properties between 2011 and 2012, (8) coincident ozone and dust surface area

  7. Hydrochemical and isotopic characterisation of deep groundwater reservoirs in the Sahara desert

    NASA Astrophysics Data System (ADS)

    Abdalla, R.; Leis, A.; Dietzel, M.; Köhler, S. J.; Böttcher, M. E.; Savarino, J.; Morin, S.

    2009-04-01

    Large sedimentary basins are extended over hundreds of square kilometres cross the Libyan Sahara. These basins consist of several aquifer systems, which belong to various geological ages. Most common are Quaternary, Mesozoic and Palaeozoic aquifers. The Jabal Hasouna well fields are located about 700 km south of Tripoli and are part of the Great Man-Made River Project for water supply to the coastal areas. The well field area extends over 4000 km2 with 440 production and 44 standby wells. In this region the main Cambro-Ordovician Sandstone aquifer is overlain by a shallow carbonate aquifer with a basal aquitard, predominantly composed of marly limestone, clay and shale. Hydrochemical investigations involving collection and analysis of numerous deep groundwater samples from Hasouna well fields have been carried out to evaluate the regional groundwater quality and origin. Therefore, the groundwater samples were analyzed for major ions, trace elements, and environmental isotopes. Additionally, soil and rock samples were collected and characterized using XRD and XRF for mineralogical and chemical composition, respectively. The groundwater can be classified in Na-Ca-Cl-SO4, Na-Ca-Cl-SO4-HCO3, Ca-Na-Cl-SO4-HCO3 and Na-Ca-Mg-Cl-SO4 types with moderate to high salinity. Most solutions indicate elevated ion concentrations of chloride, sodium, sulphate and nitrate. In some parts of the investigation area the respective ion concentrations in the groundwater exceed the WHO quality limits. Stable hydrogen and oxygen isotopic composition of the H2O show that the groundwater composition typically falls below the Global Meteoric Water Line and are far away from the Mediterranean Meteoric Water Line. Accordingly, the groundwaters were recharged in a climate different from that of the recent Mediterranean. The relationship between stable hydrogen and oxygen isotope ratios indicate that the ancient groundwater was recharged under cooler climate conditions. In order to verify the

  8. Sahara Heat Low Perturbations and Water Vapor in the Sahel: A Positive Feedback System

    NASA Astrophysics Data System (ADS)

    Caughman, L.; Evan, A. T.

    2013-12-01

    It is necessary to understand the drivers and feedbacks of global desertification, motivated by the increasing need to improve global food production and to sustainably manage ecosystems in the context of climate change. Climate change and land dynamics are the perturbations that are major drivers of an ecosystem shift to a ';';desertified'' state. This shift is typically sustained by positive feedbacks, which stabilize the system in the new state. This research focuses on changes in precipitation resulting from land-atmosphere interactions and changes in vegetation cover. We concentrate on the Sahel region of Africa (a strip of land that is a transitional area between the Sahara desert to the North and the rain forest to the South). It is a dry land, semi arid environment and is a bistable ecosystem that can either be in the state of 'dry' or 'wet'. After an abnormally wet/high precipitation period in the 1950s the Sahel experienced terrible droughts and desertification which peaked in the 1980s. Since then, precipitation has gradually increased and a sinusoidal model has been shown run on a multi decadal cycle. Discrepancies in the data exist, however, and although the overall cycle has been modeled well, the large inter-annual fluctuations in precipitation have yet to be sufficiently modeled or explained. This research offers new evidence as to why such a phenomenon exists and attempts to attribute this behavior to a coupled land-atmosphere feedback system, linking together changes in vegetation cover and precipitation in the Sahel. Using the model output data from a high resolution Weather Research and Forecasting (WRF) model to look at Africa and compare the difference between perturbations and the mean, this research asserts that when the surface of the Saharan Heat Low (SHL) becomes extremely hot the pressure drops substantially. Subsequently, due to the West African Monsoon system, air rushes in from high-pressure areas, and pulls monsoon precipitation

  9. Subcontinental lithosphere reactivation beneath the Hoggar swell (Algeria): Localized deformation, melt channeling and heat advection

    NASA Astrophysics Data System (ADS)

    Kourim, Fatna; Vauchez, Alain; Bodinier, Jean-Louis; Alard, Olivier; Bendaoud, Abderrahmane

    2015-05-01

    In the Tahalgha district (southwestern Hoggar, Algeria), the Cenozoic volcanism has sampled subcontinental mantle beneath two crustal terranes that collided during the Pan-African orogeny: the "Polycyclic Central Hoggar" to the east and the "Western Hoggar" to the west. Two major lithospheric shear zones separate these terranes: the "4°35" and the "4°50" faults. Mantle xenoliths were collected between the two faults and across the 4°35 fault. In addition to a range in equilibrium temperatures and chemical compositions reported elsewhere, the samples show variations in their microstructures and crystallographic preferred orientations. Equilibrium temperatures and geochemical characteristics allow dividing them into low - (LT; 700-900 °C), intermediate - (IT; 900-1000 °C), and high-temperature (HT; 1000-1100 °C) xenoliths. The LT and IT peridotites occur on both sides of the 4°35 fault; they are usually coarse-grained. HT xenoliths are present only east of the 4°35 fault, in the narrow domain stuck between the two faults; they are fine-grained and extensively affected by annealing and melt-rock reactions. Microstructures and crystallographic textures indicate that deformation in the LT- and IT-xenoliths occurred through dislocation creep under relatively high-temperature, low-pressure conditions, followed by post-kinematic cooling. The fine-grained HT-xenoliths were deformed under relatively high-stress conditions before being annealed. Combining microstructural and CPO data with petrological and geochemical informations suggests that: (1) the LT xenoliths are remnants of the Neoproterozoic lithospheric mantle that preserved microstructural and chemical characteristics inherited from the Pan-African orogeny, and (2) the HT xenoliths record localized Cenozoic deformation associated with melt channeling through feed-back processes that culminated in the formation of high-permeability porous-flow conduits. Limited grain-growth in HT xenoliths suggests that

  10. Patterns of seasonal variation in lagoonal macrozoobenthic assemblages (Mellah lagoon, Algeria).

    PubMed

    Magni, Paolo; Draredja, Brahim; Melouah, Khalil; Como, Serena

    2015-08-01

    In coastal lagoons, many studies indicated that macrozoobenthic assemblages undergo marked temporal fluctuations as related to the strong environmental variability of these systems. However, most of these studies have not assessed the seasonal patterns of these fluctuations and none of them has investigated the consistency of this variation in different areas within the same lagoon system. In this study, we assessed patterns of variation at multiple temporal (date, season and year) scales in two different areas in the coastal lagoon of Mellah (northeast Algeria). These areas (hereafter Shore and Center) are representative of two different environments typically found in coastal lagoons. The Shore (water depth of about 1.5-2 m) is characterized by relatively higher hydrodynamics, sand to silty-sand sediments and the presence of vegetation (Ruppia maritima), the Center (water depth of about 3-3.5 m) is characterized by mud to sandy-mud, organic-enriched sediments due to fine particle accumulation. Results showed two distinct patterns of seasonal variation in Shore and Center assemblages for two consecutive years. In Shore, species richness (S), total abundance (N) and the abundance of several dominant taxa were highest in summer and/or autumn. This pattern can be related to the local environmental conditions maintaining relatively well oxidized conditions, while increasing food availability, and favoring the recruitment of species and individuals in summer/autumn. On the contrary in Center, S was lowest in summer and autumn, and N and the abundance of fewer dominant taxa were lowest in summer. In Center, the bivalve Loripes lucinalis showed a 10-fold increase from summer to autumn in both years, likely related to the lagoon's hydrodynamics favoring larval transport and settlement in the central sector of the lagoon. Overall, the seasonal variation found in Center followed a regression/recovery pattern typical of opportunistic assemblages occurring in confined

  11. Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Messori, Gabriele; Zhang, Qiong

    2016-01-01

    The West African Monsoon (WAM) is crucial for the socio-economic stability of millions of people living in the Sahel. Severe droughts have ravaged the region in the last three decades of the 20th century, highlighting the need for a better understanding of the WAM dynamics. One of the most dramatic changes in the West African Monsoon (WAM) occurred between 15000-5000 yr BP, when increased summer rainfall led to the so-called "Green Sahara" and to a reduction in dust emissions from the region. However, model experiments are unable to fully reproduce the intensification and geographical expansion of the WAM during this period, even when vegetation over the Sahara is considered. Here, we use a fully coupled simulation for 6000 yr BP (Mid-Holocene) in which prescribed Saharan vegetation and dust concentrations are changed in turn. A closer agreement with proxy records is obtained only when both the Saharan vegetation changes and dust decrease are taken into account. The dust reduction strengthens the vegetation-albedo feedback, extending the monsoon's northern limit approximately 500 km further than the vegetation-change case only. We therefore conclude that accounting for changes in Saharan dust loadings is essential for improving model simulations of the WAM during the Mid-Holocene.

  12. Constraining the Sahara freshwater discharge during sapropel S5 time by a stable isotope record from the Greater Sirte

    NASA Astrophysics Data System (ADS)

    Zirks, Eleen; Kucera, Michal; Bachem, Paul; Schulz, Hartmut

    2016-04-01

    The Nile River and the Black Sea were long considered as the only significant eastern Mediterranean freshwater sources and therefore inferred as the primary agents promoting surface stratification associated with sapropel formation. Sapropel S5, deposited during the last interglacial, marks a time of possible movement of Homo sapiens out of Africa. Satellite images revealed the existence of ancient rivers that once ran through the Sahara desert and drained into the Gulf of Sirte. Anomalous Nd isotope records from sapropel S5 deposits indicate that these rivers may have been active during MIS 5e, implying another freshwater source into the eastern Mediterranean Sea during that period. To constrain the extent of freshwater discharge into the Mediterranean from the Kufrah River during MIS 5e, a new δ18O record of five planktonic foraminifera species was generated from sediment core GeoTü SL 96, located proximal to the assumed outflow of the Kufrah River. The record from core GeoTü SL 96 compared with seven other records from the eastern Mediterranean Sea reveal a pattern of oxygen isotope anomalies which implies that the Kufrah River delivered detectable amount of freshwater during the second part of sapropel S5. These results reinforce the hypothesis that Sahara river systems were active during MIS 5e, which has ramifications for the understanding of sapropel events, reconstruction of coastal landscape, and the better understanding of migration routes of early humans.

  13. First geophysical observations in Sahara by ground-based Lidar and CALIPSO

    NASA Astrophysics Data System (ADS)

    Cuesta, J.; Edouart, D.; Flamant, P. H.; Flamant, C.

    2006-12-01

    Saharan dust 3D spatial distribution and optical/microphysical properties are essential in understanding of Saharan desert radiative budget. Dust properties influence Saharan heat low deepening which, in turn, is believed to affect climate, particularly the West African Monsoon. Moreover, the Saharan desert regroups the world largest dust sources. In order to improve our current knowledge on Saharan dust as well as Saharan heat low dynamics, a new synergetic approach of a ground-based platform TReSS (Transportable Remote Sensing Station) and CALIPSO satellite has been implemented. TReSS has been deployed in Tamanrasset (Algeria) from February to November 2006, in the framework of the AMMA experience. TReSS is an autonomous and high-performance system designed to observe radiative and structural properties of aerosol layers and clouds, as well as atmospheric boundary layer (ABL) dynamics. The TReSS payload includes a multi-wavelength elastic/Raman backscatter Mini-Lidar, a sun-photometer and two IR radiometers. Retrieval of aerosol extinction and backscatter coefficient profiles includes several new techniques. Firstly, a new "Two-stream" lidar inversion method has been developed which independently retrieves aerosol extinction and backscatter coefficients profiles, therefore providing the proportionality coefficient or "lidar ratio" with altitude. Observations of two opposite-aiming backscatter lidar systems are combined: CALIOP (CALIPSO) and the Mini-Lidar (TReSS). This presentation provides a comparison between Two-stream inverted CALIPSO level 1 data and climatological data. Secondly, nexus between aerosol vertical distribution and optical/microphysical properties is investigated through a new "Lidar & Almucantar synergy" method. It combines vertical information contained in backscatter Lidar soundings and column-integrated aerosol optical/microphysical properties retrieved by sun photometer "Almucantar" inversion. This new algorithm provides a unique

  14. Common occurrence of zoonotic pathogen Cryptosporidium meleagridis in broiler chickens and turkeys in Algeria.

    PubMed

    Baroudi, Djamel; Khelef, Djamel; Goucem, Rachid; Adjou, Karim T; Adamu, Haileeyesus; Zhang, Hongwei; Xiao, Lihua

    2013-09-23

    Only a small number of birds have been identified by molecular techniques as having Cryptosporidium meleagridis, the third most important species for human cryptosporidiosis. In this study, using PCR-RFLP analysis of the small subunit (SSU) rRNA gene, we examined the ileum of 90 dead chickens from 23 farms and 57 dead turkeys from 16 farms in Algeria for Cryptosporidium spp. C. meleagridis-positive specimens were subtyped by sequence analysis of the 60 kDa glycoprotein gene. Cryptosporidium infection rates were 34% and 44% in chickens and turkeys, respectively, with all positive turkeys (25) and most positive chickens (26/31) having C. meleagridis. All C. meleagridis specimens belonged to a new subtype family. The frequent occurrence of C. meleagridis in chickens and turkeys illustrates the potential for zoonotic transmission of cryptosporidiosis in Algeria. PMID:23498647

  15. Decision support for sustainable urban drainage system management: a case study of Jijel, Algeria.

    PubMed

    Benzerra, Abbas; Cherrared, Marzouk; Chocat, Bernard; Cherqui, Frédéric; Zekiouk, Tarik

    2012-06-30

    This paper aims to develop a methodology to support the sustainable management of Urban Drainage Systems (UDSs) in Algeria. This research is motivated by the various difficulties that the National Sanitation Office (ONA) has in managing this complex infrastructure. The method mainly consists of two approaches: the top-down approach and the bottom-up approach. The former facilitates the identification of factors related to a sustainable UDS, the development priorities and the criteria available to managers. The latter assesses UDS performance using the weighted sum method to aggregate indicators or criteria weighted using the Analytical Hierarchy Process (AHP). The method is demonstrated through its application to the UDS in the city of Jijel, Algeria. PMID:22387329

  16. Nematodes parasitizing Trachurus trachurus (L.) and Boops boops (L.) from Algeria.

    PubMed

    Ichalal, Keltoum; Ramdane, Zouhir; Ider, Djamila; Kacher, Mohammed; Iguerouada, Mokrane; Trilles, Jean-Paul; Courcot, Luci; Amara, Rachid

    2015-11-01

    A total of 455 Boops boops (Linnaeus, 1758) and 953 Trachurus trachurus Linnaeus, 1758 from the east coast of Algeria were examined for their parasitic Nematoda. Two hundred ninety-five specimens of larval stages L3 and L4 were collected from the peritoneal cavity of these two examined fishes. Photonic and scanning electronic microscopy (SEM) studies were performed on these larvae specimens in order to characterize their morphology. Two different species of Nematoda (Anisikidae) were identified: Anisakis simplex (Rudolphi, 1809) and Hysterothylacium aduncum (Rudolphi, 1802). These two parasitic species were reported for the first time on T. trachurus and B. boops from the eastern coast of Algeria. These parasites were attached on different organs in the abdominal cavity (particularly on ovaries and testes). The infestation rate changed according to the month and the host size. The parasitism did not show a significant negative impact on the condition of the examined fishes. PMID:26220559

  17. Meningoencephalitis due to the amoeboflagellate Naegleria fowleri in ruminants in Algeria.

    PubMed

    Benterki, Mohamed Seghir; Ayachi, Ammar; Bennoune, Omar; Régoudis, Estelle; Pélandakis, Michel

    2016-01-01

    Primary amoebic meningoencephalitis (PAM) is a fatal infection in most cases, caused by the amoeba flagellate Naegleria fowleri. This report describes the first cases of PAM in Algeria, in a cow and a ewe from Batna, north-eastern Algeria. The death of both ruminants occurred a week after the first clinical manifestations. The cerebrospinal fluid, after staining with May-Grünwald-Giemsa, showed the presence of amoebae cells. Histological sections revealed numerous amoebae in all parts of the brain. The presence of N. fowleri was confirmed using a species-specific real-time PCR in histological tissue sections. The two PAM cases were reported during the hot season, and the source of infection is very likely the water where the cattle came to drink. Particular attention should be focused on this type of infection in aquatic environments when the temperature is high and preventive measures must be taken to avoid the proliferation of N. fowleri. PMID:26979770

  18. Meningoencephalitis due to the amoeboflagellate Naegleria fowleri in ruminants in Algeria

    PubMed Central

    Benterki, Mohamed Seghir; Ayachi, Ammar; Bennoune, Omar; Régoudis, Estelle; Pélandakis, Michel

    2016-01-01

    Primary amoebic meningoencephalitis (PAM) is a fatal infection in most cases, caused by the amoeba flagellate Naegleria fowleri. This report describes the first cases of PAM in Algeria, in a cow and a ewe from Batna, north-eastern Algeria. The death of both ruminants occurred a week after the first clinical manifestations. The cerebrospinal fluid, after staining with May-Grünwald-Giemsa, showed the presence of amoebae cells. Histological sections revealed numerous amoebae in all parts of the brain. The presence of N. fowleri was confirmed using a species-specific real-time PCR in histological tissue sections. The two PAM cases were reported during the hot season, and the source of infection is very likely the water where the cattle came to drink. Particular attention should be focused on this type of infection in aquatic environments when the temperature is high and preventive measures must be taken to avoid the proliferation of N. fowleri. PMID:26979770

  19. [The population explosion in Algeria: the causes, the effects, and the solutions].

    PubMed

    Muller, H

    1990-01-01

    "For decades Algeria has had one of the highest population growth rates in the world, arising directly from a steady gap between deathrates and birthrates. The reasons are of a complex social, economic and cultural kind, such as high infant mortality, traditionally early marriage, family models largely determined by religion, the common practice of child labour and other factors. As a consequence of the mismatch between economic and demographic growth the society is confronted by growing mass unemployment, underemployment, food supply problems, housing shortages and ecological crises. The critical economic situation in the eighties reduced the prospects for constraining the population explosion by quickly conquering socioeconomic underdevelopment. Nowadays Algeria is deliberately following a programme for family planning, which is also supported to a certain extent by the Islamic clergy." (SUMMARY IN ENG) PMID:12343404

  20. Impact of urban and industrial effluents on the coastal marine environment in Oran, Algeria.

    PubMed

    Tayeb, A; Chellali, M R; Hamou, A; Debbah, S

    2015-09-15

    In Algeria most of the urban waste water is dumped without treatment into the Sea. It is tremendously important to assess the consequences of organic matter rich sewage on marine ecosystem. In this study we investigated the effects of industrial and urban sewage on the dissolved oxygen (O2), chemical oxygen demand (COD), biochemical oxygen demands (BOD5), pH, salinity, electrical conductivity (EC), Metal element (Hg, Pb, Cu, Ni, Cr, Cd), petroleum hydrocarbons (HC), oil and grease (OG) in Bay of Oran, Algeria. A ten-year follow-up research showed that the concentrations of oil and grease released into the bionetwork are of higher ecological impact and this needs to be given the desired consideration. Information on bathing water quality revealed that the most beaches in Oran are under the national environmental standard limit. PMID:26164780

  1. Performances and failure of field-aged PV modules operating in Saharan region of Algeria

    NASA Astrophysics Data System (ADS)

    Sadok, M.; Benyoucef, B.; Othmani, M.; Mehdaoui, A.

    2016-07-01

    This article deals with behaviour of PV modules, of different technologies and manufacturers, exposed for long periods in Saharan region of Algeria. These modules are exposed in Adrar in the south-western part of Algeria. The study uses experimental I-V curves of PV modules for determining their performances. The datasheet information of modules will be useful in determination of degradation rates of the modules. Three types of modules have been tested: Photowatt (PWX 500), UDTS-50 and Isofoton (I-75 and I-100 serials). Results showed that Isofoton I-100 modules present the highest degradation rate while the lowest degradation rate was reached with I-75 serial. However, these rates tallies with other studies. The visual inspection of the modules has revealed various kinds of failures and defects responsible of performances drop (EVA browning, delamination, burn marks,…).

  2. Recovery process of the mineral sphalerite of Chaabet El Hamra's deposit (Algeria)

    NASA Astrophysics Data System (ADS)

    Begar, A.; Djeghlal, M.

    2012-06-01

    The present study rests on the treatment's process optimization by flotation of the Chaabet El Hamra's zinc ore (Algeria), for the optimization parameters relating to the production. The choice of parameter to optimize for flotation, and the arrangements and the scheme's initial flotation, while considering the studies already undertaken, all this has enabled us to better focus our work, while minimizing the consumption of reagents in different tests, This has resulted in successful outcomes.

  3. Uranium-series disequilibrium data for tooth fragments from the fossil hominid site at Ternifine, Algeria.

    USGS Publications Warehouse

    Szabo, B. J.

    1982-01-01

    I report here analyses of elephant molar-tooth fragments that were submitted by the late K.P.Oakley for uranium-series dating. The tooth fragments were collected by the late C. Arambourg from Pleistocene sand in association with the hominid fossils of Ternifine Man, Algeria. Of the results reported the minimum age of over 360 000 yr BP for the enamel appears to be the most reliable. -Authors

  4. Molecular characterization of Echinococcus granulosus sensu stricto and Echinococcus canadensis in humans and livestock from Algeria.

    PubMed

    Zait, Houria; Kouidri, Mokhtaria; Grenouillet, Florence Elisabeth; Umhang, Gérald; Millon, Laurence; Hamrioui, Boussad; Grenouillet, Frédéric

    2016-06-01

    In Algeria, previous studies investigated genotypes of Echinococcus granulosus sensu lato in animals and identified E. granulosus sensu stricto (s.s.) genotypes G1 and G3 whereas Echinococcus canadensis genotype G6 was only reported from dromedary cysts. Molecular data on human cystic echinococcosis (CE) were limited. We implemented a large genotyping study of hydatid cysts from humans and livestock animals to specify CE's molecular epidemiology and the genetic diversity in Algeria. Fifty-four human CE cysts from patients predominantly admitted in surgical units from Mustapha Hospital, Algiers, and 16 cysts from livestock animals gathered in two geographically distinct slaughterhouses, Tiaret and Tamanrasset, were collected. Molecular characterization was performed using sequencing of two mitochondrial genes, cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit I (NDI). In humans, G1 of E. granulosus s.s. was the main genotype (90.7 %); four samples (7.4 %) were characterized as E. granulosus s.s. G3 and one cyst as E. canadensis G6 (1.8 %). This molecular confirmation of E. canadensis G6 human infection in Algeria was observed in a Tuareg female living in a desertic area in Tamanrasset. All cysts from sheep, cattle, and goat were identified as E. granulosus s.s. G1 and the two cysts originating from dromedary as E. canadensis G6. Twenty concatenated haplotypes (COI + NDI) were characterized. Among E. granulosus s.s., one haplotype (HL1) was highly predominant in both humans and animals cysts (71.6 %). This study revealed main occurrence of E. granulosus s.s. in humans and livestock animals, with description of a predominant shared haplotype corresponding to the main worldwide observed haplotype E.granulosus s.s. G1. E. canadensis G6 was limited to South Algeria, in dromedary as well as in human. PMID:27021186

  5. Estimation of Seismic Hazard Parameters in the Northern Part of Algeria

    NASA Astrophysics Data System (ADS)

    Hamdache, M.; Bezzeghoud, M.; Mokrane, A.

    -In this study, the procedure of the earthquake hazard evaluation recently developed by Kijko and Sellevoll (1992) is used to estimate seismic hazard parameters in the northern part of Algeria. The new method differs from the conventional one because it incorporates the uncertainty of earthquake magnitude, and accepts mixed data containing large historical events and recent complete catalogue. The importance of the method lies in its ability to estimate from incomplete and uncertain data files the parameter b of the Gutenberg-Richter relationship, the annual activity rate λ of event and the maximum possible magnitude mmax . In this method, the earthquake process is considered to be of the Poisson type with an annual activity rate λ, and with a doubly truncated exponential distribution of earthquake magnitude with parameter β.The northern part of Algeria is subdivided into three zones. For each zone, estimation of b-value, the annual activity rate λ and the expected maximum magnitude are obtained. The mean return period and the probability of non-exceedence of some magnitude during a time period T = 50 and 100 years are computed.The results obtained in this study using this methodology, give a prior picture of seismic hazard in the northern part of Algeria. In some regions (Mitidja and Chelif basins) these results corroborate not only with the observation, but also with seismotectonic results.

  6. The Sergent brothers and the antimalarial campaigns in Algeria (1902-1948).

    PubMed

    Dedet, J-P

    2008-12-01

    Edmond and Etienne Sergent, "the Sergent brothers", were both born in Algeria. They both studied medicine at the Algiers Medical School and then followed the Course of Microbiology of Emile Roux at the Institut Pasteur in Paris (1899-1900). From 1900, they were put in charge of a permanent mission aimed at antimalarial control in Algeria, which was supervised by the Institut Pasteur. The first campaign was carried out during the summer of 1902 at a station of the East Algerian Railway Company. The success of this mission lead to the creation of the Antimalaric Department of Algeria in 1904, which was directed by Etienne Sergent for the duration his life. This antimalarial programme was progressively extended to many other locations. The programme was optimized between 1927 and 1947, in the experimental field study of the Ouled Mendil Marsh, where global environmental measures and drainage lead to settlement of farms, the families of which did not suffered from malaria. At a time when neither insecticides nor synthetic antimalarial drug existed, antimalarial control measures that were developed tended to target human reservoirs and the mosquito vectors. The extension of the programme across the Algerian territory lead to a decrease of both malaria endemicity and extension of affected areas. PMID:20055231

  7. Technico-economic assessment of hybrid diesel-photovoltaic power plant in the south of Algeria

    NASA Astrophysics Data System (ADS)

    Kadri, A. Y.; Hamidat, A.

    2016-07-01

    In Algeria, Electrical energy demand has knew a significant growth in recent years. The important increase in demand is due to the development of industrial and commercial sectors, and the comfort of residents customers by using multiple equipment of household such as the TV, ventilator, especially air-conditioners in the south of Algeria. To address the problem of imbalance between supply and demand, it is compulsory to add other units of productions of electricity. These units can be use conventional sources or renewable energy sources. This study focuses on the feasibility of hybridizing diesel power plants supplying the isolated villages in southern Algeria by the introduction of PV systems. The town of Djanet was taken as a case study. The comparison between the different technical and economic parameters allows determining the contribution of the hybridization of conventional resources of production. However, the cost-effectiveness based on the net present cost (NPC) is estimated at 176, 054.208 for the hybrid system and 194, 965.280 for all Diesel system. In terms of the cost per kWh produced by the two systems, the kWh produced by the hybrid system is less expensive than the kWh produced by any conventional diesel system is 0.551 / kWh against 0.610 / kWh. The results also show that the hybrid system provides coverage of the expected load in the future.

  8. Emergence of Carbapenemase-Producing Escherichia coli Isolated from Companion Animals in Algeria.

    PubMed

    Yousfi, Massilia; Touati, Abdelaziz; Mairi, Assia; Brasme, Lucien; Gharout-Sait, Alima; Guillard, Thomas; De Champs, Christophe

    2016-06-01

    The emergence and worldwide spread of carbapenemase-producing Enterobacteriaceae is of great concern to public health. The aim of this study was to investigate the occurrence of carbapenemase-producing Escherichia coli in companion animals in Algeria. Two hundred fecal samples were obtained from healthy and diseased dogs and cats in one veterinary office and private owners in Bejaia city, Algeria, during November 2014 to March 2015. Isolates were screened by polymerase chain reaction for the presence of carbapenemase, acquired plasmidic AmpC (pAmpC) and extended-spectrum beta-lactamase genes. Five carbapenemase-producing E. coli isolates were detected including four OXA-48-producing isolates and one isolate producing NDM-5. Coexpression of ESBL and pAmpC genes was observed in these isolates. Phylogenetic grouping revealed that these isolates belonged to A and D phylogroups. The results of this study show that carbapenemase-producing E. coli spread to the companion animals in Algeria. PMID:26741510

  9. A humid corridor across the Sahara for the migration of early modern humans out of Africa 120,000 years ago

    PubMed Central

    Osborne, Anne H.; Vance, Derek; Rohling, Eelco J.; Barton, Nick; Rogerson, Mike; Fello, Nuri

    2008-01-01

    It is widely accepted that modern humans originated in sub-Saharan Africa ≈150–200 thousand years ago (ka), but their route of dispersal across the currently hyperarid Sahara remains controversial. Given that the first modern humans north of the Sahara are found in the Levant ≈120–90 ka, northward dispersal likely occurred during a humid episode in the Sahara within Marine Isotope Stage (MIS) 5e (130–117 ka). The obvious dispersal route, the Nile, may be ruled out by notable differences between archaeological finds in the Nile Valley and the Levant at the critical time. Further west, space-born radar images reveal networks of—now buried—fossil river channels that extend across the desert to the Mediterranean coast, which represent alternative dispersal corridors. These corridors would explain scattered findings at desert oases of Middle Stone Age Aterian lithic industries with bifacial and tanged points that can be linked with industries further to the east and as far north as the Mediterranean coast. Here we present geochemical data that demonstrate that water in these fossil systems derived from the south during wet episodes in general, and penetrated all of the way to the Mediterranean during MIS 5e in particular. This proves the existence of an uninterrupted freshwater corridor across a currently hyperarid region of the Sahara at a key time for early modern human migrations to the north and out of Africa. PMID:18936490

  10. Peoples of Africa, Topic 1. Africa South of the Sahara: A Program of Study for Secondary School Social Studies Students. (Teaching and Student Guides).

    ERIC Educational Resources Information Center

    Carnegie-Mellon Univ., Pittsburgh, PA. Project Africa.

    This teaching guide and student text for Project Africa's curriculum program, "Africa South of the Sahara," deal with how four typical contemporary African peoples acquired their present way of life: (1) the Hausa of Northern Nigeria, (2) the Kung Bushmen of the Kalahari Desert, (3) the Mech'a Galla of Ethiopa, and (4) the Kikuyu of Kenya.…