Science.gov

Sample records for central sahara algeria

  1. Sahara Desert, Algeria

    NASA Image and Video Library

    1994-09-30

    STS068-228-081 (30 September-11 October 1994) --- This northwest-looking view shows central Algeria with an unusual amount of cloud cover, responsible for one of the infrequent bouts of rain in the Sahara Desert. The lope-shaped, red sand dunes mass in the center of the view is one of the most prominent features in the Sahara as seen from the Space Shuttle Endeavour. It is known as the Tifernine Dunes. The Atlas Mountains (top) are only apparent in this view because of the clouds, which cap their summits.

  2. Dust Storm, Sahara Desert, Algeria/Niger Border, Africa

    NASA Image and Video Library

    1992-05-16

    STS049-92-071 (13 May 1992) --- The STS-49 crew aboard the Earth-orbiting Space Shuttle Endeavour captured this Saharan dust storm on the Algeria-Niger border. The south-looking, late-afternoon view shows one of the best examples in the Shuttle photo data base of a dust storm. A series of gust fronts, caused by dissipating thunderstorms have picked up dust along the outflow boundaries. Small cumulus clouds have formed over the most vigorously ascending parts of the dust front, enhancing the visual effect of the front. The storm is moving roughly north-northwest, at right angles to the most typical path for dust storms in this part of the Sahara (shown by lines of sand on the desert surface in the foreground). Storms such as this can move out into the Atlantic, bringing dust even as far as the Americas on some occasions. A crewmember used a 70mm handheld Hasselblad camera with a 100mm lens to record the frame.

  3. GEMINI-TITAN (GT-10) - EARTH SKY - SAHARA - MAURITANIA - ALGERIA - MOROCCO - OUTER SPACE

    NASA Image and Video Library

    1966-07-18

    S66-46062 (18-21 July 1966) --- Area of the Spanish Sahara--Mauritania--Algeria--Morocco, looking north into Hamada Du Dra, as seen from the Gemini-10 spacecraft. Taken with a J.A. Maurer 70mm camera, using Eastman Kodak, Ektachrome, MS (S.O. 217) color film. Photo credit: NASA

  4. An example of the relationship between rift and dome: recent geodynamic evolution of the Hoggar swell and of its nearby regions (Central Sahara, Southern Algeria and Eastern Niger)

    NASA Astrophysics Data System (ADS)

    Dautria, J. M.; Lesquer, A.

    1989-06-01

    From essential gravimetrical and petrological data, we propose a new model of geodynamic evolution for the volcanic Hoggar swell and its nearby regions. The Eastern Hoggar, the Tenere troughs, and the North Hoggar troughs correspond to a single distensive structure which developed during the Late Mesozoic, by reactivation of N-S- and NW-SE-trending Pan African faults, in response to the stress field probably associated with the Central Atlantic opening. Contemporaneously, as suggested by the xenoliths entrained by the Cenozoic alkali basaltic eruptions of the Eastern Hoggar, an extensive lower crustal basic magmatism, (of tholeiitic affinity and probably associated with crustal stretching) may have developed beneath the Hoggarian part of this distensive structure. On the other hand, at the Hoggar level, a transverse lineament, oriented NE-SW (Oued Amded), cross-cuts the distensive structure. This lineament subsequently controlled the localization of the Mio-Plio-Quaternary volcanic districts, and possibly upper mantle modifications (through reheating, partial melting, metasomatism and magmatic veining) produced by astenospheric material transfer (gas, fluid, kimberlitic to carbonatitic magmas), resulting in a density reduction. On the other hand, the high deformation of the peridotitic inclusions of the Cenozoic alkali basalts emplaced along the Oued Amded lineament may indicate that this lineament has also controlled the emplacement of small-sized asthenospheric diapirs into the upper mantle. Thus, in the Hoggar, it appears that doming was probably preceded by a rifting phase, and that doming and Cenozoic volcanism were possibly controlled by the intersection of this rift by a transverse wrench fault.

  5. Ordovician ironstone sedimentation in Ougarta Ranges: North Western Sahara (Algeria)

    NASA Astrophysics Data System (ADS)

    Guerrak, S.

    The distribution of oolitic ironstones (OIS) of the Sahara Platform allows the distinction of two types of deposits: "Extensive Ironstone Deposition" type (EXID) and "Local Ironstone Deposition type" (LOID). Within Ordovician Formations of Ougarta ranges (Western Sahara) twelve oolitic ironstone beds of EXID type occur. The nature of ironstones within the sedimentary succession allows the distinction of two degrees of "Relative Oolitic Sedimentation Rates" (ROSR I and ROSR II), linked successively to the thickness and to the duration of the deposition. Markov chain analysis applied to the sedimentological study, suggests that ironstones are located at the bottom of fining-upward sequences and therefore, deposited in shallow shelf environments under transgressive conditions. The ironstones grouped into three facies types: a micro-conglomeratic facies (FMC), a facies with ooliths scattered in a quartz-rich matrix (detrital facies: FOD), and a facies with ooliths scattered in a quartz-poor groundmass (non-detrital facies: FOND). The mineralogy is mainly composed of hematite, chamosite, geothite, siderite and quartz. Sedimentological facts and petrographical features suggest for the oolitization, an intrasedimentary process of accretion developed in a quiet environment. Ordovician oolitic ironstones of the Ougarta region are included in a "Paleozoic North African Ironstone Belt" extending from the Oro to Libya and developed along the margin of Gondwana craton. This belt may be compared to the peri-Atlantic "North american Ironstone Belt" of Ordovician and Silurian age, but developed in a foreland basin bordered by the Taconic Orogen.

  6. 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.

  7. Algeria.

    PubMed

    1985-10-01

    Algeria is the 2nd largest state in Africa with a population of 22 million, 45% of which are urban and 57% under the age of 20. Almost all Algerians are Muslim. Education has become a real priority in Algeria and there are now more than 5 million students. Emphasis has begun to be placed on the establishment of technical institutes for training in skill areas needed to supply the nation's quickly expanding industrial sector. Presently there is a shortage of housing. The government of Algeria is centralized with guidance on fundamental issues coming from the periodic congresses of the FLN party and from its central committee between congresses. Laws remaining from the French colonial system are being amended to meet current Algerian needs. There has been relative political stability since 1965. Principal domestic objectives of the Algerian government are to achieve economic development through industrialization and increased agricultural productivity as well as raising the standard of living. The government basically controls the planning, development, and administration of the Algerian economy. The current 5-year economic development plan is financed heavily by hydrocarbon income. Despite the production of large quantities of food, Algeria must import 1/3 of its food to feed its growing population. However, at the same time, they provide a substantial amount of assistance to many of their neighbors. The armed forces are comprised of about 135,000 members and Algeria is considered a leading military power in the region. Its foreign policy is considered 1 of independence and nonalignment, and Algeria advocates the securing of a greater share of the world's wealth for developing countries by getting higher prices for the raw materials they produce. Relations with the US have improved since 1969 following the diplomatic break in realtions during the 1967 Arab-Israeli war. Most of the major political differences have been resolved.

  8. 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.

  9. 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

  10. 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.

  11. An automated dust detection using SEVIRI: A multiyear climatology of summertime dustiness in the central and western Sahara

    NASA Astrophysics Data System (ADS)

    Ashpole, Ian; Washington, Richard

    2012-04-01

    Here we present an automated dust detection scheme using the Infrared (IR) channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI), carried on board Meteosat Second Generation (MSG) satellites, from which dust scheme images that are now widely used in Saharan dust studies are created. This provides an objective, readily reproducible and quick way to build up climatologies of dust presence which compares well with subjectively identified dust presence in the daytime hours. At nighttime the automated detection scheme is less reliable due to the strong diurnal cycle of surface temperatures. Our SEVIRI Dust Flag (SDF) is compared to Aerosol Optical Depth (AOD) from the surface and found to successfully and consistently identify moderate-heavy dust outbreaks, although success rate is lower in the early morning and late evening. SDF corresponds to Absorbing Aerosol Index (AAI) from the Ozone Monitoring Instrument (OMI) that is also indicative of moderate-heavy dust outbreaks across the central and western Sahara, but there are differences in the spatial patterns of climatologies created over a number of years that are likely to be due to the different sensitivities of the detection schemes. Despite these discrepancies, SDF and AAI both place dust hot spots in southern Algeria and across its southern borders with Mali and Niger, and SDF climatologies for June-August 2004-2010 reveal that there is a substantial degree of interannual variability in dust presence in the central and western Sahara in the boreal summer.

  12. Quantifying the contribution of individual dust sources to the summertime dust hotspot in the central and western Sahara

    NASA Astrophysics Data System (ADS)

    Ashpole, Ian; Washington, Richard; Engelstaedter, Sebastian

    2014-05-01

    The central and western Sahara (CWS), a huge area encompassing parts of Algeria, Niger, Mali and Mauritania, is the dustiest place on Earth during the northern hemisphere summer. This dust is known to come from a large number of disperse sources across the region, which have been identified predominantly from satellite observations. We utilise an automated scheme that tracks individual dust plumes in data from the spaceborne Spinning Enhanced Visible and Infrared Imager (SEVIRI), available every 15 minutes at ~0.03° spatial resolution, to quantify the contribution of dust plumes from known sources to the overall CWS dust hotspot in terms of 1) frequency of dust detection and 2) total plume Aerosol Optical Depth (also derived from SEVIRI data). Results show that dust sources in the south of the region, whose activation is strongly linked to the dynamics of the West African Monsoon and convective processes, make a significantly greater contribution to the dust hotspot than sources in central Algeria and northwest Mali that, while equally or even more frequently active, give rise to plumes that are much more spatially constricted and short lived.

  13. 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

  14. 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.

  15. [Algeria].

    PubMed

    The capital of Algeria is Algiers. As of 1995, Algeria had a population of 27.9 million governed by a presidential regime. 1994 gross national product and per capita income were, respectively, $40.2 billion and $1470. Per capita income declined by 2.04% per year over the period 1985-94. In 1994, Algeria owed $29.898 billion, then being serviced at $5.4 billion. For the same year, Algeria exported $9.698 billion in goods and services and imported $12.919 billion. As of 1995, the population was growing in size by 2.2% annually. In 1992-93, life expectancy at birth was 67.1 years, the infant mortality rate was 55 per 1000 births, 88% had access to health services, and 68% had access to drinkable water. Other data are presented on the country's topography, climate and vegetation, demographics, principal cities, population distribution, religions, political structure, economics and finances, foreign commerce, and transportation and communications.

  16. 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.

  17. Algeria

    NASA Image and Video Library

    2008-09-04

    The impermanent waterways shown here from NASA EarthKAM are part of Oued Irharrhar, which appear to be carrying sulfur yellow and iron red deposits. The city of Amguid is located on these waterways, and all lie in the Mouydir Mountains in Algeria.

  18. Holocene palaeoenvironmental changes in the central Sahara (NE-Niger)

    NASA Astrophysics Data System (ADS)

    Brauneck, J.; Baumhauer, R.

    2009-04-01

    Although a high number of investigations focussed on the succession of climatological conditions in the Central Sahara, some uncertainties still exist as some of the results show discontinuities and mostly are of low temporal and spatial resolution. Two expeditions in 2005 and 2006 headed to the northeastern parts of Niger to investigate the known remains of palaeolakes and search some new and undetected ones. The sediments found at several sites were investigated in order to receive a complete picture of the Late Quaternary environmental settings and to produce high-resolution proxies for palaeoclimate modelling. The most valuable and best-investigated study site is the sebkha of Seggedim, where a core of 15 meters length could be extracted which revealed a composition of high-resolution sections. Stratigraphical, structural and geochemical investigations as well as the analysis of thin sections allow the characterisation of different environmental conditions throughout the core. Most importantly, a complex age-depth model could be constructed, based on 21 accelerator mass spectrometry (AMS) radiocarbon measurements and reaching from Early to Mid Holocene. Driven by climate and hydrogeological influence, the water body developed from a water pond of several metres depth within a stable, grass and shrub vegetated landscape, to a freshwater lake in a more dynamic environmental setting. Radiocarbon dates set the beginning of the stage at about 10.6 ka cal BP, with an exceptionally stable regime to 6.6 ka cal BP (at 12.6 metres' depth), when a major change in the sedimentation regime of the basin is recorded in the core. Increased erosion, likely due to decreased vegetation cover within the basin, led to the filling of the lake within a few hundred years and the subsequent development of a sebkha due to massive evaporation. Due to the lack of dateable material in the upper core section, the termination of the lake stage and the onset of the subsequent sebkha stage

  19. 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.

  20. Intraseasonal variability and atmospheric controls on daily dust occurrence frequency over the central and western Sahara during the boreal summer

    NASA Astrophysics Data System (ADS)

    Ashpole, Ian; Washington, Richard

    2013-12-01

    classify satellite-derived maps of daily dust occurrence frequency over the central and western Sahara (CWS) during the boreal summer in order to identify typical patterns using the neural network based system of self-organized maps. Resulting dust states vary in terms of the frequency of dust occurrence and its location. The most commonly occurring dust states are those of relatively low dust detection frequency. On days with relatively high dust occurrence, dust tends to favor either a location close to the Algeria-Mali-Niger border triple point (TP) or further to the northwest across the western half of the Mali-Algeria border (MAB). States in which dust is detected at both locations simultaneously are rare. There is a distinct intraseasonal progression in preferred dust location from the TP in the early season to the MAB later in the season. The evolution of dust states reveals a one-way transition from dust at the TP to dust at the MAB and then to reduced daily dust occurrence frequency. There is a distinct degree of interannual variability in the occurrence frequency of the different states, dominated by the extremes of high and low dust detection frequency. Analysis of climatological composites demonstrates that monsoon surges into the Saharan heat low are associated with days of high dust detection frequency, while a strong Harmattan into the CWS is linked to days with less frequent dust presence. The CWS atmospheric dust budget for June-August is thus strongly linked to the dynamics of the West African monsoon.

  1. 78 FR 56767 - Waiver of Restriction on Assistance to the Central Government of Algeria

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Waiver of Restriction on Assistance to the Central Government of Algeria Pursuant to Section 7031(b)(3) of... Section 7031(b)(1) of the Act with respect to Algeria and I hereby waive this restriction. This...

  2. 75 FR 14479 - Waiver of Restriction on Assistance to the Central Government of Algeria

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Waiver of Restriction on Assistance to the Central Government of Algeria Pursuant to section 7086(c)(2) of... section 7086(c)(1) of the Act with respect to the Government of Algeria, and I hereby waive such...

  3. 78 FR 23625 - Waiver of Restriction on Assistance to the Central Government of Algeria

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Waiver of Restriction on Assistance to the Central Government of Algeria Pursuant to Section 7031(b)(3) of... Section 7031(b)(1) of the Act with respect to Algeria and I hereby waive this restriction. This...

  4. Mzab Valley, Algeria

    NASA Image and Video Library

    2011-03-24

    Located 600 km south of Algiers, Algeria in the heart of the Sahara Desert, the five ksour fortified villages of the MZab Valley form an extraordinarily homogenous ensemble in this image captured by NASA Terra spacecraft.

  5. 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.

  6. 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.

  7. 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

  8. Ethnomycological survey of traditional usage and indigenous knowledge on desert truffles among the native Sahara Desert people of Algeria.

    PubMed

    Bradai, Lyès; Neffar, Souad; Amrani, Khaled; Bissati, Samia; Chenchouni, Haroun

    2015-03-13

    Desert truffles are edible hypogeous fungi, highly appreciated by the inhabitants of hot-desert settlements. Native Saharan people use truffles for food, promoting tourism, increasing fertility, and treatment of eye diseases and fatigue. This study consists of a cross-sectional survey focusing on the knowledge, use and ethnomycological practices of desert truffles among the native people of the Algerian Northern Sahara. The study was conducted through direct interviews with 60 truffle-hunters in the regions of Ouargla and Ghardaia. Three species were harvested and consumed by the surveyed subjects: Terfezia claveryi was the most appreciated and most expensive species, followed by Terfezia areanaria moderately preferred, then Tirmania nivea the least appreciated and least expensive. Among the 60 interviewees, 90% rely on the abundance of symbiotic plants (Helianthemum lippii) to harvest truffles, 65% begin harvesting from mid-February to March, after rains of the autumn (38%) and winter (36%), particularly in the Wadi beds (37%) and Daya landscapes (32%). Interviewees harvested truffles mainly for home consumption; however 26.7% sell any harvest surplus, and of those only 15% generate significant revenue from this source, and 73% considered the sale of desert truffles to have low financial value. Desert truffles are used in traditional medicine, especially against eye infections (22%), weakness (19%) and to promote male fertility (19%). In the case of desert truffles for consumption, the surveyed population preferred to prepare the truffles with couscous and meat, or in porridge. Respondents used price as the main criterion for deciding whether to purchase desert truffles. The surveyed trufflers use the knowledge passed from one generation to the next to help ensure a good harvest of truffles during each foray into the desert. Our findings highlight the various uses of truffles in the Sahara Desert, and how these relate to the lifestyle of local people. Copyright

  9. Traditional medicine in Central Sahara: pharmacopoeia of Tassili N'ajjer.

    PubMed

    Hammiche, Victoria; Maiza, Khadra

    2006-05-24

    Further to the previously reported ethnobotanical surveys of North-Sahara and Ahaggar [Maiza, K., Brac de la Perrière, R.A., Bounaga, N., Hammiche, V., 1990. Usages traditionnels des plantes spontanées d'El Goléa. Actes du Colloque de l'Association. Française pour la Conservation des Espèces Végétales, Mulhouse; Maiza, K., Hammiche, V, Bounaga, N., Brac de la Perrière, R.A., 1992. Inventaire des plantes médicinales de trois régions d'Algérie. Actes du Colloque International hommage à Jean Pernès: Complexes d'espèces, flux de gènes, ressources génétiques des plantes. Paris, pp. 631-633; Maiza, K., Brac de la Perrière, R.A., Hammiche, V., 1993a. Traditional Saharian pharmacopoeia. Acta Horticulturae, I.S.H.S. 332, 37-42; Maiza, K., Brac de la Perrière, R.A., Hammiche, V., 1993b. Récents apports à l'ethnopharmacologie du Sahara algérien: Actes du 2ème Colloque Européen d'Ethnopharmacologie & 11ème Conférence Internationale d'Ethnomédecine. Heidelberg, pp. 169-171; Maiza, K., Brac de la Perrière, R.A., Hammiche, V., 1995. Pharmacopée traditionnelle saharienne. Revue de Médecines et Pharmacopées Africaines, 9 (No. 1), 71-75; Maiza, K., Smati, D., Brac de la Perrière, R.A., et Hammiche, V., 2005. Pharmacopée traditionnelle au Sahara Central: Pharmacopée de l'Ahaggar. Retenu pour publication. Revue de Médecines et Pharmacopées Africaines.], we have now moved our investigations on Tassili N'Ajjer, another distinct region of the Southern Algerian Sahara. Ethnobotanic research has been carried out through interviews with nomad populations and the traditional pratictionners of recognised competence. To date, 80 wild indigenous medicinal plants have been identified and are currently used by the local population for various illnesses. Information on their vernacular Tamahaq and Arabic names, their flowering distribution, the parts used, the modes of preparation and routes of administration are reported and discussed in this paper. This work

  10. 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

  11. Inside the "African cattle complex": animal burials in the holocene central Sahara.

    PubMed

    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.

  12. 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.

  13. 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.

  14. 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

  15. The Butana Region of Central Sudan: Sahara Craton or Arabian-Nubian Shield?

    NASA Astrophysics Data System (ADS)

    Abu-Alam, T.; Stüwe, K.

    2012-04-01

    The Butana region lies 250 km south east of Khartoum and is one of the few exposures of Proterozoic basement in Central Sudan. The area is characterized by a flat surface and isolated basement exposures. Various authors have allocated the region to part of the Arabian-Nubian Shield or to part of the reworked Sahara Craton. Although the area is indeed located in the rough region of this transition, little information exists on the details of the basement geology in Butana. Field work indicates that the geology of the study area is similar to the other parts of the Arabian-Nubian Shield. The area consists of low-grade metavolcanic rocks (arc assemblage), pre- and syn-tectonic granitic intrusions. In particular the presence of serpentinites, ophiolitic metagabbro and high-grade metamorphic rocks may identify it as part of the Arabian-Nubian Shield. The main metamorphic foliation trend in the low-grade rocks is northeast-southwest with steep foliation plains and sub-horizontal lineation. In the high-grade rocks, at least three deformation phases were observed in the field. D1 associates with northeast-southwest foliation planes and D2 associates with high temperature folding mechanism which gave the high-grade rocks domal pattern. While D3 is a faulting phase with brittle features. The peak metamorphism most probably occurred after the D2 as indicated by the migmatic features. Geochronological work is in progress in order to identify uniquely if the region should be allocated to the Arabian-Nubian Shield or the Sahara Craton.

  16. Pertussis in north-central and northwestern regions of Algeria.

    PubMed

    Benamrouche, Nabila; Tali Maamar, Hassiba; Lazri, Malika; Hasnaoui, Sonia; Radoui, Abdelkarim; Lafer, Ourida; Boukari, Rachida; Kaddache, Chawki; Arrada, Zakia; Rahal, Kheira

    2016-11-24

    Pertussis outbreaks continue to occur in many countries despite high vaccination coverage. Under-diagnosed cases in adolescents and adults may result in increased transmission to infants, who are at risk of severe pertussis. Additional measures to protect both groups should be considered. Nasopharyngeal samples and sera were collected from patients and household contacts with clinically suspected pertussis. Diagnoses were confirmed by culture, real-time polymerase chain reaction (PCR), and serology. Bordetella pertussis isolates were characterized by antimicrobial sensitivity and fimbrial serotyping. Of 392 participants, 134/248 patients (54%) and 66/144 contacts (45.8%) had confirmed pertussis infections. B. parapertussis was not detected. All B. pertussis isolates were sensitive to the antibiotics tested, and all expressed the Fim3, not the Fim2, fimbrial serotype. Most patients (81.2%) were <6 months (51.8% of whom were <3 months) of age; 77.6% were unvaccinated, and most positive contacts were mothers 20-40 years of age. Despite high vaccination coverage, pertussis is circulating in Algeria. Most infections occur in unvaccinated infants <6 months of age, with mothers as the main source of infection. An adolescent/adult booster should be considered. Adoption of sensitive and specific laboratory tests would improve pertussis diagnosis and surveillance.

  17. 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

  18. [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.

  19. Geochemistry of the Central Atlantic Magmatic Province (CAMP) in south-western Algeria

    NASA Astrophysics Data System (ADS)

    Chabou, Moulley Charaf; Bertrand, Hervé; Sebaï, Amar

    2010-09-01

    In south-western Algeria, dolerite sills and dykes and scarce basalt lava flows occur in the Tindouf, Reggane, Hank basins and Bechar area, and are part of the large Central Atlantic Magmatic Province (CAMP). They represent the north-easternmost witnesses of this province into the African continent. Here, we report the first geochemical data (major, trace and rare-earth elements) for those rocks. Petrographical and chemical compositions of the studied dolerites and basalts are homogeneous and characteristic of continental tholeiites. They are moderately evolved (Mg# 0.66-0.42) quartz-normative low-Ti tholeiites (TiO 2 = 0.86-1.55 wt.%), displaying slight yet variable enrichment in LILE and LREE [(La/Yb) N = 2.18-5.51] and a negative Nb anomaly. Trace element modelling can reproduce the observed variations by non-modal batch melting of a slightly enriched source via various degrees (4-15%) of melting. A similar evolution is displayed by the neighbouring lava flows from Morocco and Ksour Mountains (North Algeria) and by the dyke swarm from Taoudenni (Mali), arguing for a common source presumed to reside within the sub-continental lithospheric mantle. The magmas were probably generated in response to mantle global warming underneath the Pangea supercontinent, and to edge-driven convection between the thick Reguibat craton and adjacent Pan-African mobile belts.

  20. Payload Bay and Great Western Sand Sea, Algeria, Africa

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Patterns of yellow and orange dunes of the Great Western Sand Sea of Algeria (29.5N, 1.5W) contrast with the black folded sedimentary rocks in the central Sahara Desert. A small dry riverbed, along the line between the thick sands and the black rocks brings in sediment from the Atlas Mountains of Morocco. Southwest winds blow sand from the bed to form a thick sand sheet on the downwind side of the river to contrast with the thin upwind dune strips.

  1. Snow In the Sahara

    NASA Image and Video Library

    2017-09-28

    In December 2016, snow fell in the Sahara for the first time since 1979. In 1984, the charitable supergroup Band Aid sang: “There won’t be snow in Africa this Christmas time.” In fact, it does snow in Africa at high elevations. Kilimanjaro has long had a cap of snow and ice, though it has been shrinking. Skiiers travel for natural and manufactured snow in the Atlas Mountains of Morocco and Algeria, as well as a few spots in South Africa and Lesotho. Nonetheless, snow on the edge of the Sahara Desert is rare. On December 19, 2016, snow fell on the Algerian town of Ain Sefra, which is sometimes referred to as the “gateway to the desert.” The town of roughly 35,000 people sits between the Atlas Mountains and the northern edge of the Sahara. The last recorded snowfall in Ain Sefra occurred in February 1979. The Enhanced Thematic Mapper Plus (ETM+) on the Landsat 7 satellite acquired this natural-color image of snow in North Africa on December 19, 2016. This scene shows an area near the border of Morocco and Algeria, south of the city of Bouarfa and southwest of Ain Sefra. Though the news has been dominated by snow in the Saharan city, a review of several years of satellite data suggests that snow is also pretty rare in this section of the Atlas range. Read more: go.nasa.gov/2hIH4Xe NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Caption by Mike Carlowicz. b>NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  2. Recent trends of temperature change under hot and cold desert climates: Comparing the Sahara (Libya) and Central Asia (Xinjiang, China)

    NASA Astrophysics Data System (ADS)

    Mamtimin, B.; Et-Tantawi, A. M. M.; Schäfer, D.; Meixner, F. X.; Domroes, M.

    2012-04-01

    According to trend computations at three stations each in Sahara desert (Libya), characterized by a "hot" desert type ("BWh", according to the Koeppen climate classification), and in Central Asia (Xinjiang, China) identified as a "cold" desert type ("BWk", after Koeppen), increasing annual temperatures were detected over the period 1955-2005 corresponding with global temperature warming. From 1955-1978, negative (decreasing) temperature trends were, however, observed at all three hot desert stations and at two of the three cold desert stations. From 1979-2005, strikingly positive temperature trends were seen at all six stations. In seasonal respects, winter (December to February) and summer (June to August) show different temperature trends over the period 1955-2005: the hot desert experienced an increasing temperature trend at a greater extent in summer than in winter; vice-versa, in the cold desert positive trends were computed for winter and negative for summer. It can also be observed that mostly hot desert warming occurred in summer, opposite to cold desert warming in winter.

  3. 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

  4. A new species of the rare buthid scorpion genus Lissothus Vachon, 1948 from Central Algeria (Scorpiones, Buthidae).

    PubMed

    Lourenço, Wilson Roberto; Sadine, Salah Eddine

    2014-06-01

    Taxonomic considerations are given for the genus Lissothus Vachon, 1948 (Scorpiones, Buthidae). Two species are currently known, Lissothus bernardi Vachon, 1948 from Libya and Lissothus occidentalis Vachon, 1950 from Mauritania. In this contribution, a new species, Lissothus chaambi sp. n., is described from the desert of Central Algeria. The new species is most closely related to L. bernardi. The geographical distribution of the genus is discussed. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Kariche, Jughurta; Meghraoui, Mustapha; Ayadi, Abdelhakim; Salah Boughacha, Mohamed

    2017-04-01

    We study the role 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 tensors with thrust faulting mechanisms allows the modeling of the Coulomb Failure Function (deltaCFF). We explore here the physical parameters 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 deltaCFF 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 modeling suggests a distinction in earthquake triggering between zones with moderate-sized and large earthquake ruptures. Recent 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 an open question with regards to their contribution to major earthquakes and their implications in the seismic hazard assessment of northern Algeria.

  7. Sahara honey shows higher potency against Pseudomonas aeruginosa compared to north Algerian types of honey.

    PubMed

    Boukraa, Laid; Niar, Abdellatif

    2007-12-01

    Six varieties of honey from different regions in Algeria were used to determine their potency against Pseudomonas aeruginosa. Four varieties originated from northern Algeria, and two from the Sahara. Three types of media were used. On nutrient agar the minimum inhibitory concentration (MIC) of the four northern varieties ranged between 30% (vol/vol) and 31% (vol/vol), while the MIC of the Sahara varieties was 11% (vol/vol) and 14% (vol/vol). On King A agar the MIC of the four northern varieties ranged from 25% (vol/vol) to 31% (vol/vol), whereas the MIC of the two varieties of Sahara honey was 12% (vol/vol) and 15% (vol/vol). On nutrient broth the MIC of the northern varieties ranged from 10% (vol/vol) to 21% (vol/vol), whereas the MIC of the two varieties of Sahara honey was 9% (vol/vol). The botanic flora of Sahara is known in Algeria for its medicinal uses, and thus the higher potency of the Sahara honey is most probably due to antibacterial substances in its plant derivates. These findings suggest that Sahara honey could be used for managing wounds and burns, which are mostly infected by P. aeruginosa.

  8. 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.

  9. 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.

  10. Dust mobilization and transport in the northern Sahara during SAMUM 2006 - a meteorological overview

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter; Ansmann, Albert; Althausen, Dietrich; Müller, Detlef; Tesche, Matthias; Bierwirth, Eike; Dinter, Tilman; Müller, Thomas; von Hoyningen-Huene, Wolfgang; Schepanski, Kerstin; Wendisch, Manfred; Heinold, Bernd; Kandler, Konrad; Petzold, Andreas; Schütz, Lothar; Tegen, Ina

    2009-02-01

    ABSTRACT The SAMUM field campaign in southern Morocco in May/June 2006 provides valuable data to study the emission, and the horizontal and vertical transports of mineral dust in the Northern Sahara. Radiosonde and lidar observations show differential advection of air masses with different characteristics during stable nighttime conditions and up to 5-km deep vertical mixing in the strongly convective boundary layer during the day. Lagrangian and synoptic analyses of selected dust periods point to a topographic channel from western Tunisia to central Algeria as a dust source region. Significant emission events are related to cold surges from the Mediterranean in association with eastward passing upper-level waves and lee cyclogeneses south of the Atlas Mountains. Other relevant events are local emissions under a distinct cut-off low over northwestern Africa and gust fronts associated with dry thunderstorms over the Malian and Algerian Sahara. The latter are badly represented in analyses from the European Centre for Medium-Range Weather Forecasts and in a regional dust model, most likely due to problems with moist convective dynamics and a lack of observations in this region. This aspect needs further study. The meteorological source identification is consistent with estimates of optical and mineralogical properties of dust samples.

  11. Murzuk Sand Sea, Sahara Desert, Libya, Africa

    NASA Image and Video Library

    1993-01-19

    STS054-152-189 (13-19 Jan. 1993) --- This near-vertical color photograph shows the very diverse landscape that is part of the great Sahara Desert of north Africa. Specifically, the vast expanse of sand dunes, located in the extreme southwestern corner of Libya, is known as the Murzuk Sand Sea. Close inspection of this photograph shows the agricultural village of Murzuk as evidenced by the numerous center pivot irrigation patterns at the edge of the Murzuk Sand Sea. The very rugged, dissected terrain to the west of this sand sea is the eastern tip of the Tassili N'ajjer Mountains and the Tadrart Plateau that are in neighboring Algeria. Several smaller areas of sand dunes are interspersed between the major areas of rock outcrops. The photograph was taken with a Linhof camera.

  12. Impact of climate change on the relict tropical fish fauna of central sahara: threat for the survival of adrar mountains fishes, mauritania.

    PubMed

    Trape, Sébastien

    2009-01-01

    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. 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. 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.

  13. Granulitic metamorphism in the Laouni terrane (Central Hoggar, Tuareg Shield, Algeria)

    NASA Astrophysics Data System (ADS)

    Bendaoud, Abderrahmane; Derridj, Amel; Ouzegane, Khadidja; Kienast, Jean-Robert

    2004-06-01

    In the Laouni terrane, which belongs to the polycyclic Central Hoggar domain, various areas contain outcrops of formations showing granulite-facies parageneses. This high-temperature metamorphism was accompanied by migmatization and the emplacement of two types of magmatic suite, one of continental affinity (garnet pyroxenites and granulites with orthoferrossilite-fayalite-quartz), and the other of arc affinity (layered metanorites). Paragenetic, thermobarometric and fluid-inclusion studies of the migmatitic metapelites and metabasites make it possible to reconstruct the P- T- aH 2O path undergone by these formations. This path is clockwise in the three studied areas, being characterized by a major decompression (Tamanrasset: 10.5 kbar at 825 °C to 6 kbar at 700 °C; Tidjenouine: 7.5 kbar at 875 °C; to 3.5 kbar at 700 °C; Tin Begane: 13.5 kbar at 850 °C; to 5 kbar at 720 °C), followed by amphibolitization that corresponds to a fall of temperature (from 700 to 600 °C) and an increase in water activity (from 0.2-0.4 to almost 1). The main observed features are in favour of petrogenesis and exhumation related to the Eburnean orogeny. However, the lacks of good-quality dating work and a comparison with juvenile Pan-African formations having undergone high-pressure metamorphism, in some cases reaching the eclogite facies, do not rule out the possibility that high-temperature parageneses are locally due to Pan-African events.

  14. M’zab Valley, Algeria

    NASA Image and Video Library

    2017-09-27

    NASA image acquired Feb. 9, 2011 Less than 5 percent of Algeria’s land surface is suitable for growing crops, and most precipitation falls on the Atlas Mountains along the coast. Inland, dust-laden winds blow over rocky plains and sand seas. However, in north central Algeria—off the tip of Grand Erg Occidental and about 450 kilometers (280 miles) south of Algiers—lies a serpentine stretch of vegetation. It is the M’zab Valley, filled with palm groves and dotted with centuries-old settlements. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite captured this image of M’zab Valley on February 9, 2011. ASTER combines infrared, red, and green wavelengths of light. Bare rock ranges in color from beige to peach. Buildings and paved surfaces appear gray. Vegetation is red, and brighter shades of red indicate more robust vegetation. This oasis results from water that is otherwise in short supply in the Sahara Desert, thanks to the valley’s approximately 3,000 wells. Chemical analysis of Algerian aquifers, as well studies of topography in Algeria and Tunisia, suggest this region experienced a cooler climate in the late Pleistocene, and potentially heavy monsoon rains earlier in the Holocene. The M’zab region shows evidence of meandering rivers and pinnate drainage patterns. The vegetation lining M’zab Valley highlights this old river valley’s contours. Cool summer temperatures and monsoon rains had long since retreated from the region by eleventh century, but this valley nevertheless supported the establishment of multiple fortified settlements, or ksours. Between 1012 A.D. and 1350 A.D., locals established the ksours of El-Atteuf, Bounoura, Melika, Ghardaïa, and Beni-Isguen. Collectively these cities are now a United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage site. NASA Earth Observatory image by Robert Simmon and Jesse Allen, using data from the GSFC

  15. Hibiscus acetosella 'Sahara Sunset'

    USDA-ARS?s Scientific Manuscript database

    The Agricultural Research Service, United States Department of Agriculture, hereby release to nurserymen a new African Hibiscus, Hibiscus acetosella Welw. ex Hiern., named ‘Sahara Sunset’. This cultivar, tested as HAC06-11 was selected from a group seedlings grown at the Thad Cochran Southern Horti...

  16. The Late Miocene climate response to a modern Sahara desert

    NASA Astrophysics Data System (ADS)

    Micheels, Arne; Eronen, Jussi; Mosbrugger, Volker

    2009-06-01

    The climate cooling and vegetation changes in the Miocene/Pliocene are generally well documented by various proxy data. Some important ecosystem changes occurred at that time. Palaeobotanical evidence suggests that the Sahara desert first appeared in the Pliocene, whereas in the Miocene North Africa was green. In the present study, we investigate the Late Miocene climate response to the appearance of the Sahara desert from a climate modelling sensitivity experiment. We compare a model experiment, which includes a full set of Late Miocene boundary conditions, with another one using the same boundary conditions except that the North African vegetation refers to the present-day situation. Our sensitivity study demonstrates that the introduction of the Sahara desert leads to a cooling and an aridification in Africa. In addition, we observe teleconnection patterns related to the North African desertification at around the Miocene/Pliocene boundary. From our sensitivity experiment, we observe that the Sahara contributes to a cooling in Central Asia and in North America. As compared to hypsodonty data for Central Asia, an increased aridity is underestimated in the Sahara experiment. Finally, we observe that the introduction of the Sahara leads to a cooling in the northern high latitudes. Hence, our sensitivity experiment indicates that the appearance of the Sahara desert is one piece to better understand Late Cenozoic climate cooling being most pronounced in the high latitudes.

  17. Sahara Desert Sand Storm, Mali, Africa

    NASA Technical Reports Server (NTRS)

    1990-01-01

    In this view of the southern Sahara Desert in Mali, Africa (16.5N, 3.0W), unusually strong surface winds accompanied by an unstable atmosphere produced a large area of blowing sand over western Africa. Between 26 and 29 April, observers in the area noted a dense cloud of sand appeared from out of central Mali and migrated offshore of the African coast near Guinea. Satellite measurements of the extent of the storm was 270, 000 square miles.

  18. Sahara Dust Cloud

    NASA Image and Video Library

    2005-07-15

    In July of 2005, a continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean, captured by the Atmospheric Infrared Sounder onboard NASA Aqua satellite. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean. These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward. http://photojournal.jpl.nasa.gov/catalog/PIA00448

  19. Sahara Desert, Niger

    NASA Image and Video Library

    1996-01-20

    STS072-709-063 (11-20 Jan. 1996) --- The astronauts aboard the Space Shuttle Endeavour exposed this 70mm frame of the Air Mountains, located in the country of Niger. These Sahara Desert structures are granitic intrusions. They are resistant to erosion and are very prominent in the lighter colored sands of the area. According to NASA geologists studying the photo collection, the ring-like structure on the lower left-hand edge of the photograph is probably a Quaternary volcanic feature. The highest peaks in the range approach 1,800 meters (6,000 feet). Deep valleys in the range are used by the Tuaregs for pasturage. Uranium and other minerals are being mined in the massif.

  20. English Teaching Profile: Algeria.

    ERIC Educational Resources Information Center

    British Council, London (England). English Language and Literature Div.

    A survey of the status and use of the English language in Algeria is presented. The following topics are outlined: (1) the role of English as a third language, (2) its place within the educational system at all levels and in each graduate institution, (3) the status of British expatriates teaching English in Algeria and of Algerian teachers of…

  1. English Teaching Profile: Algeria.

    ERIC Educational Resources Information Center

    British Council, London (England). English Language and Literature Div.

    A survey of the status and use of the English language in Algeria is presented. The following topics are outlined: (1) the role of English as a third language, (2) its place within the educational system at all levels and in each graduate institution, (3) the status of British expatriates teaching English in Algeria and of Algerian teachers of…

  2. 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. © 2016 Verlag Helvetica Chimica Acta AG, Zürich.

  3. Sahara Dust Cloud

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24

    A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean.

    These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward.

    In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005.

    In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie

    The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the

  4. Sahara Dust Cloud

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24

    A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean.

    These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward.

    In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005.

    In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie

    The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the

  5. New compounds, chemical composition, antifungal activity and cytotoxicity of the essential oil from Myrtus nivellei Batt. & Trab., an endemic species of Central Sahara.

    PubMed

    Bouzabata, Amel; Bazzali, Ophélie; Cabral, Célia; Gonçalves, Maria José; Cruz, Maria Teresa; Bighelli, Ange; Cavaleiro, Carlos; Casanova, Joseph; Salgueiro, Ligia; Tomi, Félix

    2013-10-07

    Myrtus nivellei Batt. & Trab. (Myrtaceae) known as Sahara myrtle is appreciated by the Touaregs as medicinal plant. Infusion of leaves is employed against diarrhea and blennorrhea. Crushed leaves added to oil or to butter ointment have been traditionally used for the treatment of dermatosis. Aim of the study is to consider the traditional medicinal uses and the lack of scientific studies on their biological activities, the present study was designed to elucidate the chemical composition, the antifungal activity of its essential oils against fungi responsible for human infections, as well as, its cytotoxicity in the mammalian keratinocytes. Chemical analysis of Myrtus nivellei essential oil isolated by hydrodistillation of aerial parts (leaves and flowers), was carried out using a combination of chromatographic (CC, GC with retention indices) and spectroscopic techniques (MS, (13)C NMR, 2D NMR). The antifungal activity was evaluated by using broth macrodilution methods for yeasts and filamentous fungi. Cytotoxicity was tested in HaCaT keratinocytes through the MTT assay. Ten samples coming from two localities of harvest were investigated. The chemical composition was largely dominated by 1,8-cineole (33.6-50.4%) and limonene (17.5-25.0%). The structure of two new compounds bearing the isoamylcyclopentane skeleton has been elucidated. The oil was more active against Cryptococcus neoformans with MIC of 0.16μL/mL followed by dermatophytes, with MICs of 0.64 and 1.25μL/mL. Furthermore, evaluation of cell viability showed no cytotoxicity in HaCaT keratinocytes at concentrations up to 1.25µL/mL. The composition of Myrtus nivellei oil differed from that of Myrtus communis. The structure of two di-nor-sesquiterpenoids has been elucidated. It was possible to find appropriate doses of Myrtus nivellei oil with both antifungal activity and very low detrimental effect on keratinocytes. These findings add significant information to the pharmacological activity of Myrtus

  6. The M w 5.0 Hammam Melouane Earthquake (North Central Algeria) of 17 July 2013 in the Context of the Tellian Atlas Seismicity

    NASA Astrophysics Data System (ADS)

    Yelles-Chaouche, A. K.; Haned, A.; Aidi, C.; Beldjoudi, H.; Kherroubi, A.; Semmane, F.; Benabdeloued, B. Y. N.; Larbes, Y.; Alili, A.; Khelif, M. F.; Belheouane, A.

    2017-04-01

    On 17 July 2013 (03:00 GMT) a new moderate earthquake of magnitude 5.0 happened in the Tell belts of northern Algeria, more precisely near the village of Hammam Melouane (Algeria), 30 km south of Algiers, the Capital of Algeria. The main shock parameters and aftershocks activity analysis, reveal that the earthquake occurred on a 5 km long dextral strike-slip fault oriented N114°E, a conjugate strike-slip fault of the major NE-SW reverse fault system of the neogene Mitidja basin. This event caused damage to houses and social infrastructures but no fatalities were reported. Onland the earthquake triggered rock falls and minor landslides along the Hammam Melouane river. The occurrence of the Hammam Melouane in the northern limit of the Tell belts is representative of the African-Eurasiatic interplate seismicity of northern Algeria where major seismic events could occurred as the previous Boumerdes event of May 21st, 2003 ( M w 6.8).

  7. The M w 5.0 Hammam Melouane Earthquake (North Central Algeria) of 17 July 2013 in the Context of the Tellian Atlas Seismicity

    NASA Astrophysics Data System (ADS)

    Yelles-Chaouche, A. K.; Haned, A.; Aidi, C.; Beldjoudi, H.; Kherroubi, A.; Semmane, F.; Benabdeloued, B. Y. N.; Larbes, Y.; Alili, A.; Khelif, M. F.; Belheouane, A.

    2017-02-01

    On 17 July 2013 (03:00 GMT) a new moderate earthquake of magnitude 5.0 happened in the Tell belts of northern Algeria, more precisely near the village of Hammam Melouane (Algeria), 30 km south of Algiers, the Capital of Algeria. The main shock parameters and aftershocks activity analysis, reveal that the earthquake occurred on a 5 km long dextral strike-slip fault oriented N114°E, a conjugate strike-slip fault of the major NE-SW reverse fault system of the neogene Mitidja basin. This event caused damage to houses and social infrastructures but no fatalities were reported. Onland the earthquake triggered rock falls and minor landslides along the Hammam Melouane river. The occurrence of the Hammam Melouane in the northern limit of the Tell belts is representative of the African-Eurasiatic interplate seismicity of northern Algeria where major seismic events could occurred as the previous Boumerdes event of May 21st, 2003 (M w 6.8).

  8. Algeria’s Counter-Terrorism Strategy to Protect the State from New Threats

    DTIC Science & Technology

    2013-03-01

    staff , and intelligence chiefs to discuss coordinating an appropriate response to the threat of terrorism in the trans-Sahara region. Algeria, Mali...as the French company " Areva ” in some sites in northern Niger. The foreign interests were secured by Niger’s security forces.47 In addition to the...Department, (E.U Parliament 2012), 15. 50 Comité d’état-major operational conjoint/ a joint operational staff committee for Sahelian counter terrorist

  9. [The population of Algeria].

    PubMed

    Cote, M

    1983-01-01

    Using data from the 1977 census for Algeria, demographic developments over the preceding 10 years are analyzed. Findings are presented concerning age distribution, economic activity, spatial distribution, urbanization, and internal migration. (summary in ENG)

  10. The Pasteurization of Algeria?

    PubMed

    Strachan, John

    2006-01-01

    This essay focuses on the anti-malarial campaigns of Edmond and Etienne Sergent in colonial Algeria during the period from 1900 to 1930. This Pasteur Institute of Algeria was part of an elaborate, global network of men and institutions that constituted the scientific empire of Third Republic France. It was deeply indebted to the methods pioneered by Pasteur and to the shared foundational myth that connected the overseas Pasteur Institutes to Paris. But the Sergent brothers' work operated within a dynamic context of international public health too. Algeria's European settlers had also worked out a creolized identity that was both dependent upon and distinct from metropolitan practices. Ultimately, the Pasteur Institute of Algeria bore the mark of the settler colonialism that had given rise to it.

  11. Algeria Country Analysis Brief

    EIA Publications

    2016-01-01

    Algeria is the leading natural gas producer in Africa, the second-largest natural gas supplier to Europe, and is one of the top three oil producers in Africa. Algeria is estimated to hold the third-largest amount of shale gas resources in the world. However, gross natural gas and crude oil production have gradually declined over the past decade, mainly because new production and infrastructure projects have repeatedly been delayed.

  12. The LATEA metacraton (Central Hoggar, Tuareg shield, Algeria): behaviour of an old passive margin during the Pan-African orogeny

    NASA Astrophysics Data System (ADS)

    Liégeois, Jean Paul; Latouche, Louis; Boughrara, Mustapha; Navez, Jacques; Guiraud, Michel

    2003-10-01

    Historically, the Tuareg shield is divided into three parts bordered by mega-shear zones with the centre, the Central Polycyclic Hoggar, characterized by Archaean and Palaeoproterozoic lithologies. Nearly 10 years ago, the Tuareg shield was shown to be composed of 23 displaced terranes [Geology 22 (1994) 641] whose relationships were deciphered in Aı̈r to the SE [Precambr. Res. 67 (1994) 59]. The Polycyclic Central Hoggar terranes were characterized by the presence of well preserved Archaean/Palaeoproterozoic and Neoproterozoic lithologies. We show here that the terranes from Central Hoggar (Laouni, Azrou-n-Fad, Tefedest, Egéré-Aleksod) belonged to a single old passive margin, to which we gave the acronym name LATEA, which behaved as a craton during the Mesoproterozoic and the Early-Middle Neoproterozoic but was partly destabilized and dissected during the Late Neoproterozoic as a consequence of its involvement as a passive margin in the Pan-African orogen. An early Pan-African phase consisted of thrust sheets including garnet-bearing lithologies (eclogite, amphibolite, gneiss) that can be mapped and correlated in three LATEA terranes. In the Tin Begane area, P- T- t paths have been established from >15 kbar--790 °C (eclogite) to 4 kbar--500 °C (greenschist retrogression) through 12 kbar--830 °C (garnet amphibolite) and 8 kbar--700 °C (garnet gneiss), corresponding to the retrograde path of a Franciscan-type loop. Sm-Nd geochronology on minerals and laser ablation ICP-MS on garnet show the mobility of REE, particularly LREE, during the retrograde greenschist facies that affects, although slightly, some of these rocks. The amphibolite-facies metamorphism has been dated at 685 ± 19 Ma and the greenschist facies at 522 ± 27 Ma. During the thrust phase, the Archaean-Palaeoproterozoic basement was only locally affected by the Pan-African tectonics. LATEA behaved as a craton. Other juvenile terranes were also thrust early onto LATEA: the Iskel island arc at

  13. 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

  14. Comment on "Climate-driven ecosystem succession in the Sahara: the past 6000 years".

    PubMed

    Brovkin, Victor; Claussen, Martin

    2008-11-28

    Kröpelin et al. (Research Articles, 9 May 2008, p. 765) interpreted a sediment record from Lake Yoa in the east-central part of North Africa as support for a weak biogeophysical climate-vegetation feedback in the Sahara during the mid-Holocene. We argue that the new data do not invalidate earlier modeling results on strong land-atmosphere coupling in the Western Sahara for which the Lake Yoa record is far less representative.

  15. Dusty Gust Fronts at Synoptic Scale, Initiated and Maintained by Moist Convection over the Sahara Desert

    NASA Astrophysics Data System (ADS)

    Bou Karam, D.; Williams, E.; McGraw-Herdeg, M.; Janiga, M.; Cuesta, J.; Flamant, C.; Pelon, J.; Thorncroft, C.

    2009-12-01

    So-called ‘dry’ microburst outflows are well known phenomena in desert environments when rain from moist convection aloft evaporates into deep, dry-adiabatic boundary layers. Extreme synoptic scale versions of this convective scale phenomenon have been documented in this study, in which the collective episodes of convective downdraft feed a common cold pool that expands as a gust front density current, raising large amount of dust in the boundary layer, and initiating new moist convection over the Sahara. Satellite observations from the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) combined with selected West African surface station observations have been integrated to study the gust front and its associated dust activity in the period of August 3-6, 2006. The meteorological conditions accompanying this event have been described using the European Centre for Medium-range Weather Forecasts (ECMWF) analyses. The gust front was initiated by a cluster of isolated cumulonimbus clouds over central Niger at 1400 UT on August 3 that lengthened to MCS size over Mali by the end of the day. At maximum expansion on August 5, the extending gust front exceeded 1500 km in length, with a transited area of lofted dust reaching a million square kilometers, mostly over southern Algeria and northern Mali. The northward gust front speed, estimated with SEVERI imagery, is rapid in initial stages but declines with time as the cold air absorbs heat from the hot desert surface and the gust front density contrast is diluted. The synoptic character of this event (both the length and the duration) allows for four intersections with CALIPSO orbits, thereby providing information on the evolution of the characteristics of the dusty gust front during its lifetime. Young dusty gust fronts (i.e. during the first 24 hours of the event) were characterized by lidar reflectivity at 532 nm in excess of 3 x

  16. 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

  17. 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.

  18. Algeria: Country Status Report.

    ERIC Educational Resources Information Center

    McFerren, Margaret

    A survey of the status of language usage in Algeria begins with an overview of the usage patterns of Arabic, the Berber languages, and French. The country's return to Arabic as its official language after independence from France in 1962 is discussed along with the resultant language planning, issues of language of instruction at the elementary,…

  19. Algeria: Current Issues

    DTIC Science & Technology

    2011-04-13

    fiscal policies (including investment in public infrastructure) had nonetheless enabled Algeria to weather the crisis well. At the same time, the IMF... Policy , coordinated by John Rollins. President Bouteflika’s tenure has produced an energized foreign policy . Strains in ties with neighboring Morocco...Issues for U.S. Policy ............................................................................................................3 Background

  20. 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

  1. 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)

  2. Country Education Profiles: Algeria.

    ERIC Educational Resources Information Center

    International Bureau of Education, Geneva (Switzerland).

    One of a series of profiles prepared by the Cooperative Educational Abstracting Service, this brief outline provides basic background information on educational principles, system of administration, structure and organization, curricula, and teacher training in Algeria. Statistics provided by the Unesco Office of Statistics show enrollment at all…

  3. Algeria: Country Status Report.

    ERIC Educational Resources Information Center

    McFerren, Margaret

    A survey of the status of language usage in Algeria begins with an overview of the usage patterns of Arabic, the Berber languages, and French. The country's return to Arabic as its official language after independence from France in 1962 is discussed along with the resultant language planning, issues of language of instruction at the elementary,…

  4. 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)

  5. 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.

  6. Do Sahara dunes make dust? Some dunes do and some dunes don't

    NASA Astrophysics Data System (ADS)

    Bristow, Charlie

    2017-04-01

    The Sahara desert is responsible for producing around half of the atmospheric mineral dust on Earth. While most of the Sahara has the potential to produce dust some areas have been identified using remote sensing as especially prolific dust sources such as the Bodélé Depression in Chad which is described as the dustiest place on Earth. Geomorphological analysis indicates that these areas are usually topographic lows, such as the Bodélé, as well as regions on the flanks of topographic highs. This view was challenged by Crouvi et al. (2012) who suggest that active sand dunes are the most frequent dust sources. In this paper we use an experimental dust chamber to generate dust from dune sediments collected from the crest of active sand dunes across the Sahara including samples from the Bodélé depression, as well as dune sands from Algeria, Egypt, Libya, Morocco and Tunisia. The experiments produced a wide range of results indicating that some dune sands, including those from the Bodélé produce much more dust than others.

  7. 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

  8. A new high-resolution central and western Saharan summertime dust source map from automated satellite dust plume tracking

    NASA Astrophysics Data System (ADS)

    Ashpole, Ian; Washington, Richard

    2013-07-01

    In this paper, we outline a new objective dust source detection method for the central and western Sahara (CWS), based on the automated tracking of individual dust plumes in data from the Spinning Enhanced Visible and Infrared Imager, available every 15 mins. at ~0.03° spatial resolution. The method is used to map the origin of summertime dust storms in the CWS for June - August 2004 - 2010. It reveals the sources of these events in unprecedented detail, allowing for the identification of specific, highly active source areas. The study of collocated surface features reveals that many of the dominant sources are likely associated with paleolakes and outwash plains, many in close proximity to the Saharan mountains. Extensive nonsource areas are associated with low albedo and elevated terrain, pointing to the mountainous regions of the Sahara. Additionally, sand seas are not identified as important source areas, but their margins sometimes are. The automated tracking method also facilitates analysis of the transport direction of dust plumes from key source regions and the inference of emission mechanisms. It is found that there are two broad domains within the CWS: one in southwest Algeria and northwest Mali, characterized primarily by transport toward the southwest and very likely dominated by low-level jets embedded in the northeasterly Harmattan winds; and a second in southern Algeria, northwest Niger, and northeast Mali where there is no preferred transport direction and a strong potential association between dust events and deep convection, pointing toward cold pool outflows as the likely deflation mechanism.

  9. Sandfly Fever Sicilian Virus, Algeria

    PubMed Central

    Izri, Arezki; Temmam, Sarah; Moureau, Grégory; Hamrioui, Boussad; de Lamballerie, Xavier

    2008-01-01

    To determine whether sandfly fever Sicilian virus (SFSV) is present in Algeria, we tested sandflies for phlebovirus RNA. A sequence closely related to that of SFSV was detected in a Phlebotomus ariasi sandfly. Of 60 human serum samples, 3 contained immunoglobulin G against SFSV. These data suggest SFSV is present in Algeria. PMID:18439364

  10. 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

  11. Sbaa basin: A new oil-producing regino in Algeria

    SciTech Connect

    Baghdadli, S.M.

    1988-08-01

    Discovery of a paraffinic oil in 1980 in the Adrar area, the west part of the Algerian Sahara within the Sbaa half-graben depression, opens a new oil- and gas-bearing region in Algeria. The oil and gas fields are located on highly faulted structures generated by differential movements of basement blocks. Oil deposits are connected with tidal sandy sediments of Strunian and Tournaisian age and occur at depths of 500 to 1,000 m (1,640 to 3,280 ft). Gas and wet gas deposits are related to sandstone reservoirs of Cambrian-Ordovician age at depths of 1,500 to 2,000 m (4,920 to 6,562 ft).

  12. Rainfall regimes of the Green Sahara.

    PubMed

    Tierney, Jessica E; Pausata, Francesco S R; deMenocal, Peter B

    2017-01-01

    During the "Green Sahara" period (11,000 to 5000 years before the present), the Sahara desert received high amounts of rainfall, supporting diverse vegetation, permanent lakes, and human populations. Our knowledge of rainfall rates and the spatiotemporal extent of wet conditions has suffered from a lack of continuous sedimentary records. We present a quantitative reconstruction of western Saharan precipitation derived from leaf wax isotopes in marine sediments. Our data indicate that the Green Sahara extended to 31°N and likely ended abruptly. We find evidence for a prolonged "pause" in Green Sahara conditions 8000 years ago, coincident with a temporary abandonment of occupational sites by Neolithic humans. The rainfall rates inferred from our data are best explained by strong vegetation and dust feedbacks; without these mechanisms, climate models systematically fail to reproduce the Green Sahara. This study suggests that accurate simulations of future climate change in the Sahara and Sahel will require improvements in our ability to simulate vegetation and dust feedbacks.

  13. 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

  14. Widespread geographical disparities in chronic hepatitis B virus infection in Algeria.

    PubMed

    Bensalem, Aïcha; Selmani, Karima; Narjes, Hihi; Bencherifa, Nesrine; Soltani, Mahdia; Mostefaoui, Fatma; Kerioui, Cherif; Pineau, Pascal; Berkane, Saadi; Debzi, Nabil

    2017-06-01

    Algeria is the largest country of Africa, with a population of 40 million inhabitants living in disparate environments from the Sahara to the large cities of the Mediterranean coast. The molecular epidemiology of hepatitis B virus (HBV) variants has been partially described, but variations in the seroprevalence of HBV surface antigen (HBsAg) throughout the Algerian territories are still poorly described. We analyzed demographic features of new cases of chronic infection collected in 41 administrative regions (covering 92% of the population) in 2013. The mean age of the 1876 HBsAg(+) patients was 36.8 ± 14.2 years, with a slight excess of males (54%). The seroprevalence of HBV early antigen (HBeAg) was 9.3%, and the mean virus load was 3.2 ± 1.8 log IU/ml. A subset of 15.2% of patients was already cirrhotic at disease discovery. An important heterogeneity was observed throughout the country, with nine regions displaying a significant excess of cases. These regions formed four distinct foci located in distant parts of the country: Adrar-Bechar (southwest), El-Oued-Tebessa (east), M'Sila-Sétif (north central) and Oran-Aïn Temouchent (northwest). An excess of cases was found as well in the national capital Algiers. Patients from southern regions with an excess of cases (Bechar, Adrar, El Oued) were significantly younger (32.0 ± 10.7 years), as were patients from the regions of Bejaia and Bouira (32.1 ± 10.6). The southwestern regions were also marked by a significant imbalance of the sex ratio (58 vs 39% of female cases, P = 4.5 E-5). The highest HBeAg seroprevalence was observed in Setif (26.4 vs. 7.6%, OR = 4.3, 95% CI 2.6-6.5, P = 1.1 × 10(-11)) in accordance with the higher virus loads observed in the patients (3.9 ± 2.3 vs. 3.1 ± 1.6, P = 0.0002). In conclusion, we observed heterogeneity in HBsAg seroprevalence, demographic traits, and disease evolution in Algeria. Further studies are now warranted to shed light on these

  15. Rainfall regimes of the Green Sahara

    PubMed Central

    Tierney, Jessica E.; Pausata, Francesco S. R.; deMenocal, Peter B.

    2017-01-01

    During the “Green Sahara” period (11,000 to 5000 years before the present), the Sahara desert received high amounts of rainfall, supporting diverse vegetation, permanent lakes, and human populations. Our knowledge of rainfall rates and the spatiotemporal extent of wet conditions has suffered from a lack of continuous sedimentary records. We present a quantitative reconstruction of western Saharan precipitation derived from leaf wax isotopes in marine sediments. Our data indicate that the Green Sahara extended to 31°N and likely ended abruptly. We find evidence for a prolonged “pause” in Green Sahara conditions 8000 years ago, coincident with a temporary abandonment of occupational sites by Neolithic humans. The rainfall rates inferred from our data are best explained by strong vegetation and dust feedbacks; without these mechanisms, climate models systematically fail to reproduce the Green Sahara. This study suggests that accurate simulations of future climate change in the Sahara and Sahel will require improvements in our ability to simulate vegetation and dust feedbacks. PMID:28116352

  16. Induction of canthaxanthin production in a Dactylococcus microalga isolated from the Algerian Sahara.

    PubMed

    Grama, Borhane Samir; Chader, Samira; Khelifi, Douadi; Agathos, Spiros N; Jeffryes, Clayton

    2014-01-01

    Secondary carotenoids are high-valued anti-oxidants which can be produced by some algae when exposed to an environmental stress (e.g. nutrient deprivation, high light intensities). To this end, we characterized the stress-induced carotenoid production of a new microalgal strain, Dactylococcus dissociatus MT1, which was isolated from the Sahara Desert of Algeria. Nitrate starvation, oxidative stress and varying light intensities were applied to determine the effect of illumination on carotenogenesis. Canthaxanthin was the main secondary carotenoid and light intensity had an important influence on the rate of its accumulation. The addition of NaCl also enhanced canthaxanthin production while nitrate depletion had more of an effect on lipid production. However, these two stresses in combination synergistically increased the production of both. Our results represent a step toward the development of strains suitable for secondary carotenoid production at the industrial scale.

  17. LL and E awarded E and D contract area in eastern Algeria

    SciTech Connect

    Not Available

    1992-12-07

    This paper reports that a Louisiana Land and Exploration Co. unit has been awarded on exploration and production contract in Algeria by state oil company Enterprise Nationale Sonatrach. LL and E Algeria Ltd.'s contract covers two blocks in the central Ghadames oil basin of eastern Algeria. LL and E said the contract, yet to be submitted for government approval, calls for a minimum investment of $33 million during a 5 year work program that includes seismic acquisition and drilling a minimum of three wildcats.

  18. 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

  19. Plasmodium falciparum Malaria, Southern Algeria, 2007

    PubMed Central

    Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

    2010-01-01

    An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria. PMID:20113565

  20. The War in the Western Sahara.

    DTIC Science & Technology

    1984-05-08

    confirmed in her position as Morocco’s protector. The murder of a French citizen in Marrakech gave France the pretext to occupy Oujda in 1907. On similar... Marrakech and Essaouira. After the prayer, they would talk apprehensively about the French colonial swift penetration in Algeria, Senegal and Niger

  1. 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.

  2. 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.

  3. Epidemic typhus imported from Algeria.

    PubMed

    Niang, M; Brouqui, P; Raoult, D

    1999-01-01

    We report epidemic typhus in a French patient returning from Algeria. The diagnosis was confirmed by serologic testing and the isolation of Rickettsia prowazekii in blood. Initially the patient was thought to have typhoid fever. Because body lice are prevalent in industrialized regions, the introduction of typhus to pediculosis-endemic areas poses a serious public health risk.

  4. Epidemic typhus imported from Algeria.

    PubMed Central

    Niang, M.; Brouqui, P.; Raoult, D.

    1999-01-01

    We report epidemic typhus in a French patient returning from Algeria. The diagnosis was confirmed by serologic testing and the isolation of Rickettsia prowazekii in blood. Initially the patient was thought to have typhoid fever. Because body lice are prevalent in industrialized regions, the introduction of typhus to pediculosis-endemic areas poses a serious public health risk. PMID:10511530

  5. Adsorption of dyes on Sahara desert sand.

    PubMed

    Varlikli, Canan; Bekiari, Vlasoula; Kus, Mahmut; Boduroglu, Numan; Oner, Ilker; Lianos, Panagiotis; Lyberatos, Gerasimos; Icli, Siddik

    2009-10-15

    Sahara desert sand (SaDeS) was employed as a mineral sorbent for retaining organic dyes from aqueous solutions. Natural sand has demonstrated a strong affinity for organic dyes but significantly lost its adsorption capacity when it was washed with water. Therefore, characterization of both natural and water washed sand was performed by XRD, BET, SEM and FTIR techniques. It was found that water-soluble kyanite, which is detected in natural sand, is the dominant factor affecting adsorbance of cationic dyes. The sand adsorbs over 75% of cationic dyes but less than 21% for anionic ones. Among the dyes studied, Methylene Blue (MB) demonstrated the strongest affinity for Sahara desert sand (Q(e)=11.98 mg/g, for initial dye solution concentration 3.5 x 10(-5)mol/L). The effects of initial dye concentration, the amount of the adsorbent, the temperature and the pH of the solution on adsorption capacity were tested by using Methylene Blue as model dye. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied. It was concluded that adsorption of Methylene Blue on Sahara desert sand followed pseudo-second order kinetics. Gibbs free energy, enthalpy change and entropy change were calculated and found -6411 J/mol, -30360 J/mol and -76.58 J/mol K, respectively. These values indicate that the adsorption is an exothermic process and has a spontaneous nature at low temperatures.

  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. 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.

  8. 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.

  9. Airborne bacteria transported with Sahara dust particles from Northern Africa to the European Alps

    NASA Astrophysics Data System (ADS)

    Lazzaro, A.; Meola, M.

    2015-12-01

    The Sahara Desert is the most important source of aerosols transported across the Mediterranean towards Europe. Airborne microorganisms associated with aerosols may be transported over long distances and act as colonizers of distant habitats. However, little is known on the composition and viability of such microorganisms, due to difficulties related to their detection, collection and isolation. Here we describe an in-depth assessment of the bacterial communities associated with Sahara dust (SD) particles deposited on snow. Two distinct SD events reaching the European Alps in February and May 2014 were preserved as distinct ochre-coloured layers within the snowpack. In June 2014, we collected samples from a snow profile at 3621 m a.s.l. close to the Jungfraujoch (Swiss Alps). SD particles were analyzed by Scanning Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy (SEM-EDX). Backward trajectories were calculated using the NOAA HYSPLIT model. Bacterial communities were charac-terized by MiSeq Illumina sequencing of the 16S rRNA gene. Microbial physiological profiles were assessed by incubation of samples on BIOLOG plates. The SD-layers were generally enriched in illite and kaolinite particles as compared to the adjacent snow layers. The source of SD could be traced back to Algeria. We observed distinct bacterial community structures in the SD-layers as compared to the clean snow layers. While sporulating bacteria were not enriched in the SD-layers, low abundant (<1%) phyla such as Gemmatimonadetes and Deinococcus-Thermus appeared to be specific bioindicators for SD. Both phyla are adapted to arid oligotrophic environments and UV radiation and thus are well suited to survive the harsh conditions of long-distance airborne transport. Our results show that bacteria are viable and metabolically active after the trek to the European Alps.

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

    PubMed Central

    2016-01-01

    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

  11. 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…

  12. Reemerging Threat of Epidemic Typhus in Algeria

    PubMed Central

    Mokrani, K.; Fournier, P. E.; Dalichaouche, M.; Tebbal, S.; Aouati, A.; Raoult, D.

    2004-01-01

    We report a case of epidemic typhus in a patient from the Batna region of Algeria, who presented with generalized febrile exanthema. The clinical diagnosis was confirmed by serological cross-adsorption followed by Western blotting. Our report emphasizes the threat of epidemic typhus in the highlands of Algeria. PMID:15297561

  13. 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…

  14. 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…

  15. 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…

  16. 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…

  17. Morocco and Algeria

    Atmospheric Science Data Center

    2013-04-15

    ... atop a high plain, known as the Central Plateau, and many mountain ranges, rivers, geological basement rock and vegetation types are ... where the valley of the Guadalquivir River is shut in by mountain ranges on every side except the southwest, where the valley descends ...

  18. 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.

  19. 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.

  20. [Cardiovascular morbimortality after a follow-up of six years in black hypertensive in South Algeria].

    PubMed

    Bachir Cherif, A; Temmar, M; Labat, C; Atif, L; Chibane, A; Benkhedda, S; Taleb, A; Benfenatki, N; Benetos, A; Bouafia, M T

    2014-06-01

    Arterial hypertension is a major public health problem not only internationally, but also in our country, and it is the major risk factor for cardiovascular diseases. In south Algeria, the black population is nearly half the population of the oases of the Algerian Sahara. The objectives of the study are to analyze the long-term fate of the black hypertensive subjects in Algerian oases in southern Algeria, in terms of morbidity and mortality, comparing the morphometric profile and cardiovascular complications with the white population of the same oases. One thousand four hundred and twenty-five subjects of both sexes were included (811 blacks and 614 white subjects), aged 40 and older, living in the Algerian Sahara and were reviewed after six years of decline. The control consisted of filling a questionnaire oriented on civil status, target organ damage, the number of hospitalizations and mortality. All calculations and statistical analyzes are processed by the SPSS 17.0 and Epi Info6 software. Mean age for the black population and the white population was 60.3±11.1 and 58.6±10.6years, respectively. The incidence of hypertension was 50 % among blacks. The main complications observed were: stroke in 3.8 %, heart failure in 3.1 %, myocardial infarction in 1.7 %, hospitalizations related to cardiovascular complications of the black population was around 4.4 %, mortality 5.4 %. These data on hypertension black subjects emphasize the importance of a policy of adequate local health issues raised, both in terms of the management of hypertension, as in investment in local medical research. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  1. 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.

  2. [Demography and crises in Algeria].

    PubMed

    Cherrad, S E

    1996-01-01

    This article argues that demographic factors are an underlying cause of the many political, economic, social, and cultural crises that Algeria has experienced over the course of the 1990s. The author suggests that although the demography of the country is generally ignored when these issues are discussed, the rapid rate of population growth, which has caused the population to double in about 20 years, and the continued dependency burden, due to the fact that over 50% of the population are under age 20, are major causes of the country's current malaise.

  3. Algeria: World Oil Report 1991

    SciTech Connect

    Not Available

    1991-08-01

    This paper reports that Algeria is positioned to achieve important, new natural gas markets. Over half of its hydrocarbon income is from exports of gas and derived products, liquified petroleum gas (LPG) and condensates, which are not subject to Opec quotas. Officials are moving away from inflexible past policies and are becoming vastly more realistic now that foreign investment laws have been liberalized and there is a need to attract foreign investors. Sonatrach must address three key issues to consolidate recent progress. Sales to existing customers in Europe, like Italy, must be expanded; new customers and markets need to found: and U.S. liquified natural gas (LNG) markets must be revived.

  4. Algeria schedules onshore licensing round

    SciTech Connect

    Not Available

    1992-08-17

    This paper reports that Algeria's Sonatrach will conduct its first international onshore exploration licensing round in a move designed to triple drilling activity in the country. A second round will follow next April. Sonatrach plans to drill 200 wells during 1991-95, which will require the current level of 37/year to be almost trebled toward the end of the period. To this end foreign operators are being courted in an open exploration bidding round. Deadline for bid submittal in Nov. 30. Companies may enter singly or in groups to form partnerships with Sonatrach. Foreign licensees will be able to take a maximum 49% of production under Algerian law.

  5. 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.

  6. 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

  7. Middle Devonian (Givetian) coral-stromatoporoid reefs in West Sahara (Morocco)

    NASA Astrophysics Data System (ADS)

    Wendt, Jobst; Kaufmann, Bernd

    2006-03-01

    Spectacular table reefs, biostromes and patch reefs occur in two areas (Uein Terguet and Gor Loutad) of West Sahara which are part of a narrow belt along the northern margin of the West African Craton (Reguibat Massif) extending for 1500 km from the Zemmour (Mauritania) in the SW to southern Algeria in the E. Six reef cycles can be distinguished in the Givetian which are separated by shales and sandstones. The first cycle is constituted by stromatactis mud mounds which probably also form the nucleus of the 2nd and 3rd reef cycle. The biota of the 2nd to 6th cycles are dominated by large stromatoporoids, associated with tabulate as well as solitary and colonial rugose corals and a great variety of reef-dwelling organisms. The cyclicity may be either a result of relative eustatic sealevel changes or of oscillating siliciclastic input from the West African Craton shelf margin which has repeatedly interrupted reef growth. Isotopic compositions of early cements in the 1st reef cycle indicate a cooler-water setting of about 40° S compared to coeval tropical low latitude reefs in Euramerica and Australia.

  8. Eghindi among Sahrawi refugees of Western Sahara.

    PubMed

    Volpato, Gabriele; Waldstein, Anna

    2014-01-01

    Eghindi is an illness built around a set of pathological states experienced by Sahrawi in the desert environment of Western Sahara. Its core symptoms are caused by osmotic imbalances related to salt consumption. In 1975, many Sahrawi were exiled into refugee camps, and they have since experienced radical sociocultural changes, which are reflected in changing explanatory models of eghindi. Older and conservative refugees, attached to traditional Sahrawi culture, have expanded its conceptualization to include new pathogenic factors, while younger and progressive refugees, acculturated with Western culture, began challenging its existence. Eghindi became embodied within a broader process of negotiation of Sahrawi cultural identity. Our findings provide a framework for thinking about the evolution of illness in response to displacement, and highlight that when explanatory models evolve, intracultural tensions can arise within a population.

  9. Early cretaceous dinosaurs from the sahara.

    PubMed

    Sereno, P C; Wilson, J A; Larsson, H C; Dutheil, D B; Sues, H D

    1994-10-14

    A major question in Mesozoic biogeography is how the land-based dinosaurian radiation responded to fragmentation of Pangaea. A rich fossil record has been uncovered on northern continents that spans the Cretaceous, when continental isolation reached its peak. In contrast, dinosaur remains on southern continents are scarce. The discovery of dinosaurian skeletons from Lower Cretaceous beds in the southern Sahara shows that several lineages of tetanuran theropods and broad-toothed sauropods had a cosmopolitan distribution across Pangaea before the onset of continental fragmentation. The distinct dinosaurian faunas of Africa, South America, and Asiamerica arose during the Cretaceous by differential survival of once widespread lineages on land masses that were becoming increasingly isolated from one another.

  10. Recharge Mechanism to North-Western Sahara Aquifer System (NWSAS) Using Environmental Isotopes

    NASA Astrophysics Data System (ADS)

    Al-Gamal, Samir

    2010-05-01

    A comprehensive understanding is highly needed for any successful transboundary cooperation policy. Moreover, an analysis of the NWSAS can be of particular interest for policy makers and researchers. This paper aims to reveals and to assess the renewability of North Western Sahara Aquifer System(NWSAS) as one of the major transboundary multi-layered aquifer system, in North Africa, shared by Algeria, Tunisia, and Libya and is often referred to as the Système Aquifère du Sahara Septentrional (SASS).The paper is primarily intended for exploring whether it receives a considerable fraction of modern water as recharge or it is at risk of being depleted and excessively pumped, where the main challenge for NWSAS ,is that it should be abstracted rationally for equitable use. Environmental isotopes data of δ18O, δ2H, 3H ,14C as well as characteristics of d-excess are used to illustrate whether NSWAS is renewable or non-renewable resource.Geochemical, hydrological and statistical evidences supporting the renewability of NWSAS are provided through pairs of cross-plots . The study has clearly indicated that NWSAS is receiving a considerable fraction of modern water as recharge to the aquifer because of the following reasons; Firstly, the moderately depleted delta values of O-18 and H-2 of water from Sahara Atlas in Algeria and the Dahar and the Dj. Nefoussa in Tunisia and Libya with δ18O content (- 6.0‰ to -5.0‰) compared with that of palaeowater (-7.0 to -9.0 ‰) indicate a considerable fraction of modern water recharging NWSAS.This considerable fraction of modern water should be attributed to originate from the present-day precipitation (-6.5‰).Secondly, the presence of significant amount of 14C >2 % and 3H > 5TU., frequently found in data should be attributed to a mixing with shallow and modern water, where old water practically contains no 14C. The foregoing facts are in good agreement with the results of conventional hydrologic approach. This would contradicts

  11. An assessment of recharge possibility to North-Western Sahara Aquifer System (NWSAS) using environmental isotopes

    NASA Astrophysics Data System (ADS)

    Al-Gamal, Samir Anwar

    2011-02-01

    SummaryA comprehensive understanding of the groundwater dynamics of a transboundary aquifer system is highly needed for any successful transboundary cooperation policy. Moreover, an analysis of the NWSAS can be of particular interest for policy makers and researchers. This paper aims to reveals and to assess the renewability of North-Western Sahara Aquifer System (NWSAS) as one of the major transboundary multi-layered aquifer system, in North Africa, shared by Algeria, Tunisia, and Libya and is often referred to as the Système Aquifère du Sahara Septentrional (SASS). The paper is primarily intended for exploring whether it receives a considerable fraction of modern water as recharge or it is at risk of being depleted and excessively pumped, where the main challenge for NWSAS, is that it should be abstracted rationally for equitable use. Environmental isotopes data of δ 18O, δ 2H, 3H, 14C as well as characteristics of d-excess are used to illustrate whether NSWAS is renewable or non-renewable resource. Geochemical, hydrological and statistical evidences supporting the renewability of NWSAS are provided through pairs of cross-plots. The study has clearly indicated that NWSAS is receiving a considerable fraction of modern water as recharge to the aquifer because of the following reasons: Firstly, the moderately depleted delta values of δ 18O and δ 2H of water from Sahara Atlas in Algeria and the Dahar and the Dj. Nefoussa in Tunisia and Libya with δ 18O content (-6.0‰ to -5.0‰) compared with that of palaeowater (-7.0‰ to -9.0‰) indicate an appreciable fraction of modern water recharging NWSAS. This appreciable fraction of modern water should be attributed to originate from the present-day precipitation (-6.5‰). Secondly, the presence of significant amount of 14C > 2% and 3H > 5 TU, frequently found in data should be attributed to a mixing with shallow and modern water, where old water practically contains no 14C. The foregoing facts are in good

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

    NASA Image and Video Library

    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 ...

  13. 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)

  14. Special Education through Neighbourhood Centers in Algeria.

    ERIC Educational Resources Information Center

    Boucebci, Mahfoud

    1981-01-01

    The article provides a survey of special education needs in Algeria with emphasis on the role of neighborhood centers which involve parents in the education of mentally handicapped children. Journal availability: see EC 133 861. (DB)

  15. 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)

  16. Special Education through Neighbourhood Centers in Algeria.

    ERIC Educational Resources Information Center

    Boucebci, Mahfoud

    1981-01-01

    The article provides a survey of special education needs in Algeria with emphasis on the role of neighborhood centers which involve parents in the education of mentally handicapped children. Journal availability: see EC 133 861. (DB)

  17. [Leprosy in Algeria. Apropos of an autochthonous case in the Wilaya de Tlemcen, Algeria].

    PubMed

    Boudghene-Stambouli, O; Merad-Boudia, A

    1989-01-01

    Leprosy is not a problem for public health in Algeria. For one century (from 1888 to 1987), a maximum of 250 cases were reported, only 75 of them were Algerians and 61 caught the disease in Algeria. Hence leprosy was mainly an imported disease. Will multiple exchanges with other countries increase the magnitude of the problem?

  18. 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.

  19. [An unusual genital ulcer in Algeria: soft chancre].

    PubMed

    Boudghene-Stambouli, O; Merad-Boudia, A

    1989-01-01

    Four cases of soft chancre have been observed in the service of Dermato-Venereology, CHU Tlemcen. Three were contracted in Morroco and one in Algeria. This affection which no long existed in Algeria, has reappeared through tourism.

  20. [Status quo and progress of Chinese acupuncture in Algeria].

    PubMed

    Huang, Yisheng

    2015-10-01

    The development of Chinese acupuncture in Algeria and realistic working status in recent years is in- troduced. From five aspects, including general condition of acupuncture in Algeria, clinical application and analysis, of acupuncture, promotion and publicity of acupuncture, existing problem and deficiency, and awards and honor, the status quo and progress of Chinese acupuncture in Algeria are discussed in detail.

  1. 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

  2. Historical and future trends of the Sahara Desert

    NASA Astrophysics Data System (ADS)

    Liu, Ping; Washington, Warren M.; Meehl, Gerald A.; Wu, Guoxiong; Potter, Gerald L.

    The Parallel Climate Model (PCM) Version 1.1 simulates a reasonable twentieth century climatology in the Sahara Desert. From late 1940s to the end of 1980s, the simulated Sahara Desert, bounded by the 50 mm mean annual rainfall isoline, becomes larger and shifts eastward. The model produces a decreasing rainfall trend while the surface temperature and meridional boundaries are almost stable. In the usual scenario with increasing greenhouse gases from the 1980s to the 2090s the Sahara becomes smaller, moves north and west and continues to dry. Both the size change and latitudinal shift show a century long trend. Compared to 1961-90 climatology, the average northward shift is around 1° and the surface temperature about 2.8°C warmer to the end of 21st century. The local greenhouse effect may cause such warming trend.

  3. 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.

  4. 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…

  5. Africa, Sub-Sahara: A Selected Functional and Country Bibliography.

    ERIC Educational Resources Information Center

    Foreign Service (Dept. of State), Washington, DC. Foreign Service Inst.

    Sub-Sahara Africa is covered in this bibliography prepared for use in training programs. Consisting of nearly 500 citations which date from 1940 to the present, topics covered include: POPULATION, Traditional Cultures, Religion, Art, Literature, History, Colonialism, Economic Development, Agricultural Modernization, Education and Manpower,…

  6. Development of the Peace Process in the Western Sahara Conflict

    DTIC Science & Technology

    2014-06-13

    Thesis Committee Chair John Cary, M.A , Member Jack D. Kem, Ph.D. , Member William L. Knight, M.B.A Accepted this...balanced research thesis. Dr. Jack D. Kem and Mr. William L. Knight offered expert perspective and encouragement. I express my sincerest gratitude to...rule over the Western Sahara ......................................................................... 5 The Spanish Occupation of Sidi Ifni and

  7. 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…

  8. Brazil, Atlantic Ocean, Africa, Sahara & Antarctica seen from Apollo 4

    NASA Image and Video Library

    1967-11-09

    AS04-01-410 (9 Nov. 1967) --- Coastal Brazil, Atlantic Ocean, West Africa, Sahara, Antarctica, looking west, as photographed from the Apollo 4 (Spacecraft 017/Saturn 501) unmanned, Earth-orbital space mission. This picture was taken when the Spacecraft 017 and Saturn S-IVB (third) stage were orbiting Earth at an altitude of 9,745 nautical miles.

  9. 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.

  10. Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara

    NASA Astrophysics Data System (ADS)

    Kemena, Tronje Peer; Matthes, Katja; Martin, Thomas; Wahl, Sebastian; Oschlies, Andreas

    2017-09-01

    Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR's CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

  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.

  12. Vocational Training and Rural Development in Algeria

    ERIC Educational Resources Information Center

    Boumaza, S.; Gara, A.

    1973-01-01

    Better organization of the agricultural sector, expansion of production capabilities, increased employment, satisfaction of the country's needs, and improved productivity are the guidelines considered in the planning and development of the agricultural vocational training system in Algeria. Charts illustrate and clarify the organization of this…

  13. Library-Information Education in Algeria.

    ERIC Educational Resources Information Center

    Boumarafi, B. B.; Haythornthwaite, J.

    1988-01-01

    Reviews the development of educational programs for library technicians, librarians, and information professionals in Algeria and describes the current educational structure. Topics discussed include the need for improvements in curriculum development, teaching staff development, library facilities, and the use of information technologies. (CLB)

  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. [Demography and social problems in Algeria].

    PubMed

    Benissad, M E

    1982-01-01

    A review of current population trends in Algeria is presented. Sections are included on fertility, mortality, projections, spatial distribution, employment and economic development, and the development of emigration. Some social problems associated with demographic factors are also considered, such as education, housing, and food supplies.

  17. Vocational Training and Rural Development in Algeria

    ERIC Educational Resources Information Center

    Boumaza, S.; Gara, A.

    1973-01-01

    Better organization of the agricultural sector, expansion of production capabilities, increased employment, satisfaction of the country's needs, and improved productivity are the guidelines considered in the planning and development of the agricultural vocational training system in Algeria. Charts illustrate and clarify the organization of this…

  18. 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)

  19. Library-Information Education in Algeria.

    ERIC Educational Resources Information Center

    Boumarafi, B. B.; Haythornthwaite, J.

    1988-01-01

    Reviews the development of educational programs for library technicians, librarians, and information professionals in Algeria and describes the current educational structure. Topics discussed include the need for improvements in curriculum development, teaching staff development, library facilities, and the use of information technologies. (CLB)

  20. Structural characterization and rheological properties of a galactomannan from Astragalus gombo Bunge seeds harvested in Algerian Sahara.

    PubMed

    Chouana, T; Pierre, G; Vial, C; Gardarin, C; Wadouachi, A; Cailleu, D; Le Cerf, D; Boual, Z; Ould El Hadj, M D; Michaud, P; Delattre, C

    2017-11-01

    A water soluble polysaccharide (WSP) was extracted and purified from Astragalus gombo seeds (Fabaceae) harvested in Septentrional Sahara (Ouargla, Algeria) with a yield of 6.8% (w/w of the dry seed ground). It was characterized by gas chromatography coupled to the mass spectrometry (GC-MS), size exclusion chromatography with Multi-Angle Light Scattering analysis (SEC-MALLS), high-resolution (1)H and (13)C NMR, and rheological measurements. The structural characterization indicated that this WSP fraction is a galactomannan with a mannose/galactose ratio of 1.7 formed by a backbone of β-(1,4)-d-mannopyranosyl residues (63%) substituted at O-6 position by a single α-galactopyranose residue (37%). SEC-MALLS analysis revealed that this galactomannan has an average molecular mass (Mw) of 1.1×10(6)g/mol, an intrinsic viscosity of 860mL/g and, a random coil conformation structure. Rheological analysis in semi diluted regimes shown pseudo-plastic and viscoelastic behaviour. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. 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.

  2. The Sources Of Protracted Conflict In The Western Sahara

    DTIC Science & Technology

    2016-03-01

    and Security (Paris: OECD Publishing, 2014), 174–176. 4 spent billions of petro dollars to extend his influence in Africa, creating the Community...Organisation for Economic Co-operation and Development, Global Security Risks and West Africa Development Challenges (Paris: OECD Publishing, 2012), 44...Algeria, killing 26 civilians and injuring 177.13 9 OECD , Global Security Risks, 48. 10 OECD

  3. Lower Devonian paleomagnetic dating of a large mafic sill along the western border of the Murzuq cratonic basin (Saharan metacraton, SE Algeria).

    NASA Astrophysics Data System (ADS)

    El-M. Derder, Mohamed; Maouche, Said; Liégeois, Jean-Paul; Henry, Bernard; Amenna, Mohamed; Ouabadi, Aziouz; Bellon, Hervé; Bruguier, Olivier; Bayou, Boualem; Bestandji, Rafik; Nouar, Omar; Bouabdallah, Hamza; Ayache, Mohamed; Beddiaf, Mohamed

    2017-04-01

    The Murzuq basin located in central North Africa, in Algeria, Libya and Niger is a key area, delineating a relictual cratonic area within the Saharan metacraton (Liégeois et al., 2013). On its western border, we discovered a very large sill ("Arrikine" sill), with a thickness up to 250m and a minimum length of 35 km. It is made of mafic rocks and is interbedded within the Silurian sediments of the Tassilis series. In the vicinity, the only known post-Pan-African magmatism is the Cenozoic volcanism in the In Ezzane area. Further south in Niger, also along the SW border of the Murzuq basin, large Paleozoic dolerite (Carte géologique du Sahara central, 1962) are probably related to the "Arrikine" sill magmatism, as they are in the same stratigraphical position. Several hundred kilometers westward and southwestward of Arrikine, Paleozoic magmatic products are known: Carboniferous basic intrusives (346 Ma; Djellit et al., 2006) are located in the Tin Serririne basin and Devonian ring complexes (407 Ma; Moreau et al, 1994) in the Aïr Mountains. For the Arrikine sill, K/Ar data gave a rejuvenation age (326 Ma) related to a K-rich aplitic phase and the LA-ICP-MS U-Pb method on zircon showed that only inherited zircons are present (0.6 to 0.7, 2.0 and 2.7 Ga ages), pointing to ages from the underlying basement corresponding to the Murzuq craton covered by Pan-African sediments (Derder et al., 2016). By contrast, a well-defined paleomagnetic pole yielded an age of 410-400 Ma by comparison with the Gondwana Apparent Polar Wander Path (APWP). This age, similar to that reported for the Aïr complexes (Moreau et al., 1994), can be correlated with the deep phreatic eruption before Pragian time thought to be at the origin of sand injections, which gave circular structures observed on different borders of the Murzuq basin (Moreau et al,. 2012). This Lower Devonian magmatism had therefore a regional extension and can be related to a "Caledonian" transtensive reactivation of the

  4. Obesity and type 2 diabetes in Sub-Sahara Africa.

    PubMed

    Mbanya, Jean Claude; Assah, Felix K; Saji, Jude; Atanga, Emmanuella N

    2014-07-01

    There is a mounting body of evidence regarding the challenge posed by diabetes and obesity on the health systems of many Sub-Sahara African countries. This trend has been linked to the changing demographic profile together with rapid urbanization and changing lifestyles in both rural and urban settings in Africa. Africa is expected to witness the greatest increase in the number of people with diabetes from 19.8 million in 2013 to 41.4 million in 2035 if current trends persist. Excess weight alone currently accounts for at least 2.8 million deaths globally each year through increased risk for type 2 diabetes and cardiovascular complications. This review highlights recent literature on the problem of obesity and type 2 diabetes in Sub-Sahara Africa. It exposes the need for concrete interventions based on the now available wealth of evidence.

  5. 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.

  6. Événements panafricains dans l'Adrar Souttouf (Sahara marocain)

    NASA Astrophysics Data System (ADS)

    Villeneuve, Michel; Bellon, Hervé; El Archi, Abdelkrim; Sahabi, Mohamed; Rehault, Jean-Pierre; Olivet, Jean-Louis; Aghzer, Abdel M.

    2006-05-01

    The Adrar Souttouf belt (Western Sahara) lies in the northern part of the Mauritanide belt and was considered as a part of the Hercynian Mauritanian-Appalachian belt. Recently the presence of a Panafrican protolith (595 Ma) was evidenced by the age of inherited zircons from an eclogitic unit and led to consider complex Panafrican events included in the Hercynian belt, as in the central and southern Mauritanide belt. Our new field survey completed by ten K sbnd Ar dating (whole rocks and separate minerals) confirmed that multiphased Panafrican formations outcrop within the center of the Adrar Souttouf massif. Diverse events ranged from ca. 1000 to 500 Ma, some of them being indicative of an oceanic type environment and metamorphism. The 1000 Ma metamorphic event is recorded for the first time in the West African craton. A large Hercynian remobilisation is also evidenced. To cite this article: M. Villeneuve et al., C. R. Geoscience 338 (2006).

  7. 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.

  8. 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.

  9. JPRS Report, Africa, (Sub-Sahara).

    DTIC Science & Technology

    2007-11-02

    Reestablished 99 2,000 Repatriated From Zimbabwe 99 Refugees Trained in Zimbabwe 99 - d - Demobilization in Cabo Delgado 100 New Tete Officials 100...graft within the context of the massive campaign launched by Maj Manuel Joao Lourenco, a member of the Central Committee of the party and provincial...which according to the provincial commissar, Maj Manuel Joao Lourenco, was considered a prohibited zone for domestic consumption. The provincial

  10. Burden of fungal infections in Algeria.

    PubMed

    Chekiri-Talbi, M; Denning, D W

    2017-02-21

    We report for the first time in Algeria and provide burden estimates. We searched for existing data and estimated the incidence and prevalence of fungal diseases based on the population at risk and available epidemiological data. Demographic data were derived from the National Office of Statistics (Office National des Statistiques: ONS), World Health Organization (WHO), The Joint Nations Programme on HIV/AIDS (UNAIDS) and national published reports. When no data existed, risk populations were used to estimate frequencies of fungal infections, using previously described methodology. Algeria has 40.4 million inhabitants, and probably at least 568,900 (1.41%) of Algerians have a serious fungal infection each year. Recurrent vulvovaginal candidiasis (485,000) and fungal asthma (72,000) are probably the commonest problems, as there are over 1 million adult asthmatics. Candidaemia is estimated in 2,020 people, invasive aspergillosis in 2,865 people, and intra-abdominal candidiasis in 303 people; these are the most common life-threatening problems. AIDS is uncommon, but cancer is not (45,000 new cases of cancer including 1,500 in children), nor is COPD (an estimated 317,762 patients, of whom 20.3% are admitted to hospital each year). A focus on improving the diagnosis and epidemiological data related to fungal infection is necessary in Algeria.

  11. Hematopoietic stem cell transplantation in Algeria.

    PubMed

    Bekadja, Mohamed Amine; Brahimi, Mohamed; Osmani, Soufi; Yafour, Nabil; Krim, Amina; Serradj, Faiza; Talhi, Souad; Amani, Kamila; Bouhass, Rachid Amar

    2017-07-11

    Algeria is a country of 40,.4 million inhabitants and half of which is under 30years. In Algeria, Health-care insurance covered, 90% of the population. Health care is free and it is supported by the Ministry of Health. 16 university hospitals exist in Algeria and only two (Algiers and Oran) practicing bone marrow transplant. Adult hematologic malignancies account for 10% (about 4000 new cases/year) of the malignancy affecting in most cases young patients under 65years of age. In 2016, 270 transplants were performed in total (Algiers+Oran), including 149 allografts (related donor transplants: 99%) and 121 autografts. 98% of transplants are done in adults and only 2% in children with cord blood transplants. In summary for the two transplant centers, the predominant types of transplantation performed are allogeneic transplant in 55% and autologous transplant in 45%. The particularity of EHU1st November in Oran, is the use of non-cryopreserved stem cells. Stem cell was mobilized using G-CSF alone and the grafts were kept in a conventional blood bank refrigerator at +4°C until reinfusion on day 0. The outcome with non-cryopreserved stem cells are the same as those with cryopreserved stem cells and we conclude that autologous transplant with non cryopreserved hematopoietic stem cells (HSC) is a simple, effective and safe method and the cryopreservation is not necessary in our work conditions in developing countries. The projects are achieving the autograft in all University Hospitals with non cryopreserved HSC, achieving a center allograft in the east of the country and the development of bone marrow transplantation in children. Currently in Algeria, the number of transplantation is insufficient and the development of new transplant centers is essential. In the future, we hope to implement the National Society of Bone Marrow transplant and also the National recipient registry and Donor registry in Algeria. Copyright © 2017 King Faisal Specialist Hospital & Research

  12. Impacts of climatic change on carbon storage in the Sahara?Gobi desert belt since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Lioubimtseva, E.; Simon, B.; Faure, H.; Faure-Denard, L.; Adams, J. M.

    1998-05-01

    Reconstructions of palaeolandscapes for intervals with different climatic conditions help define regional trends in palaeobiomass and carbon storage due to global climatic change. The Sahara-Gobi desert belt stretches for about 15,000 km from the Atlantic coast to Northern China. Natural vegetation zones have undergone a number of significant shifts and complex qualitative changes under the contrasting climatic conditions of the Last Glacial Maximum (LGM) and the Holocene Climatic Optimum (HCO). The results presented here are based on palynological, pedological and sedimentological evidence, which indicate that the amount of carbon stored in vegetation and soils would have been much smaller during the Glacial Maximum than in the interglacial and post glacial times. Comparison of a set of palaeogeographic maps of this region for the chosen time-slices (ca. 20-18 ka, 9-8 ka and the present) allows us to discuss land biomass changes. Dry and cool conditions during the LGM resulted in the spread of arid and semi-arid ecosystems at northern and southern margins of the desert belt. The southern limit of the Sahara migrated southward at least 400 km relative to its present position, and almost 1000 km south compared to the mid-Holocene. The northern margin of the temperate deserts and dry steppes of Central Asia shifted northward for not less than 200-300 km over Kazakhstan, southern Siberia and Mongolia. In this study we have quantified variations of the main ecosystems from the LGM to the HCO in terms of changes in carbon storage. Each vegetation zone has been assigned a carbon density for living and dead (soil) organic matter. During the last world deglaciation, the Sahara-Gobi desert belt was a sink for approximately 200 Gt of atmospheric carbon, but since the mid-Holocene, it has been a source of carbon.

  13. Ocular complications of HIV infection in sub-Sahara Africa.

    PubMed

    Nkomazana, Oathokwa; Tshitswana, Dintle

    2008-08-01

    This article reviews the magnitude and spectrum of ocular complications of HIV infection in sub-Sahara Africa. A literature search was done using PubMed, Google, and UpToDate and by talking to ophthalmologists and HIV experts working in the region. Ocular complications of HIV infection, mostly retinal, are seen in 29% to 71% of patients. Cytomegalovirus retinitis affects 0% to 16.5% of HIV-infected patients and is treated successfully with intravitreal ganciclovir in South Africa and Botswana. Ocular surface squamous neoplasia is seen in 4% to 7.8% of persons with HIV (a 5%-6% increase in Uganda and Tanzania), and recurrence after surgery occurs in 3.2% to 31.2%. In Zimbabwe, 45% of meningitis in adults is cryptococcal, and cryptococcal meningitis is the third leading cause of death in HIV patients in rural Uganda. In Rwanda, 9% of patients with cryptococcal meningitis developed visual loss and sixth nerve palsy. Thus, HIV infection leads to significant ocular morbidity in sub-Sahara Africa.

  14. [Medical General Inspector Debenedetti and Algeria (1956-1961)].

    PubMed

    Linon, Pierre-Jean

    2005-01-01

    M.G.I. Debenedetti was appointed as director of French Military Health Service in June 1956 for seven years, during the war of Algeria where he travelled eight times. Thus, he surveyed the good organisation of the Military Health Service in Algeria from 1956 to 1961 when he had his last journey in this country. This paper tries to report his career, his survey of the French Military Health Service on the theatre of operations, of the hospitals and of the Free Medical Care of Algeria.

  15. The Temaguessine Fe-cordierite orbicular granite (Central Hoggar, Algeria): U Pb SHRIMP age, petrology, origin and geodynamical consequences for the late Pan-African magmatism of the Tuareg shield

    NASA Astrophysics Data System (ADS)

    Abdallah, Nachida; Liégeois, Jean-Paul; De Waele, Bert; Fezaa, Nassima; Ouabadi, Aziouz

    2007-11-01

    The Temaguessine high-level subcircular pluton is intrusive into the LATEA metacraton (Central Hoggar) Eburnian (2 Ga) basement and in the Pan-African (615 Ma) granitic batholiths along a major NW-SE oriented major shear zone. It is dated here (SHRIMP U-Pb on zircon) at 582 ± 5 Ma. Composed of amphibole-biotite granite and biotite syenogranite, it comprises abundant enclaves: mafic magmatic enclaves, country-rock xenoliths and remarkable Fe-cordierite (#Fe = 0.87) orbicules. The orbicules have a core rich in cordierite (40%) and a leucocratic quartz-feldspar rim. They are interpreted as resulting from the incongruent melting of the meta-wacke xenoliths collapsed into the magma: the breakdown of the biotite + quartz assemblage produced the cordierite and a quartz-feldspar minimum melt that is expelled, forming the leucocratic rim. The orbicule generation occurred at T < 850° and P < 0.3 GPa. The Fe-rich character of the cordierite resulted from the Fe-rich protolith (wacke with 4% Fe 2O 3 for 72% SiO 2). Strongly negative ɛNd (-9.6 to -11.2), Nd TDM model ages between 1.64 and 1.92 Ga, inherited zircons between 1.76 and 2.04 Ga and low to moderately high ISr (0.704-0.710) indicate a Rb-depleted lower continental crust source for the Temaguessine pluton; regional considerations impose however also the participation of asthenospheric material. The Temaguessine pluton, together with other high-level subcircular pluton, is considered as marking the end of the Pan-African magma generation in the LATEA metacraton, resulting from the linear delamination along mega-shear zones, allowing asthenospheric uprise and melting of the lower continental crust. This implies that the younger Taourirt granitic province (535-520 Ma) should be considered as a Cambrian intraplate anorogenic event and not as a very late Pan-African event.

  16. [Epidemiological data on scorpion envenomation in Algeria].

    PubMed

    Hellal, H; Guerinik, M; Griene, L; Laid, Y; Mesbah, S; Merad, R; Alamir, B

    2012-08-01

    The scorpion envenomation is a major public health problem in Algeria. Given this fact, the Ministry of Health has developed a national strategy for prevention and control based on the training of health personnel, information, education and communication, and standardization of care on the basis of a therapeutic consensus. The monitoring and evaluation activities are carried out by epidemiological indicators through the implementation of an information system based in the services of Epidemiology, INSP (National Institute of Public Health) and Prevention Department of the Health Ministry. The information carriers are report cards implemented in different health facilities that collect data on bites and deaths from scorpion envenomation. Summaries of notifications from the wilayas are collected monthly, and processed by the Epi info software using monitoring indicators. From 1991 to 2010, there has been a stagnation in the number of stings with an average of 50,000 cases per year, but mortality decreased from more than 100 deaths in the last fifty years to 50 nowadays. The higher proportion of stings was recorded during the summer period. The most affected group is from 15 to 49 years which constitute the workforce, but children from 5 to 14 years rank first in terms of mortality. But these rates vary across years and regions. Despite all these efforts, the scorpion envenomation in Algeria remains of concern and our main challenges are to strengthen cross-sectional actions at the local level and improving the quality of care.

  17. [Assisted returns to country of origin: a study of Algeria].

    PubMed

    Benattig, R

    1989-01-01

    The author analyzes trends in government-assisted return migration to Algeria. Factors considered include employment and occupational status and individual and family readjustment to the local community. (SUMMARY IN ENG AND SPA)

  18. Tobacco use in sub-Sahara Africa: estimates from the demographic health surveys.

    PubMed

    Pampel, Fred

    2008-04-01

    Despite the growing problem of global tobacco use, accurate information on the prevalence and patterns in the world's poorest nations remains sparse. For sub-Sahara Africa, in particular, a weak knowledge base limits the targeting of strategies to combat the potential growth of tobacco use and its harmful effect on future mortality. To describe the prevalence and social patterns of the use of cigarettes and other tobacco in Africa, this study examines population-based data from 16 Demographic Health Surveys (DHS) of men aged 15-54 years and women aged 15-49 years in 14 nations. Descriptive statistics show the highest cigarette use among men in several nations of east central Africa and Madagascar, lowest use in nations of west central Africa, and medium use in nations of southern Africa. Multinomial logistic regression results for men show highest cigarette use among urban, less educated, and lower status workers. Results for women show much lower prevalence than men but similar social patterns of use. The DHS results thus give new and comparable information about tobacco use in low-income nations, disadvantaged social groups, and an understudied region of the world.

  19. Wildfire management policies in Algeria: present and future needs

    Treesearch

    Ouahiba Meddour-Sahar; Armando González-Cabán; Rachid Meddour; Arezki Derridj

    2013-01-01

    Algerian forest lands cover 4,115,908 hectares (ha), of which 2,413,090 (58%) ha are bush or maquis. Recent work has shown that forest fires are the main factor explaining (90%) degradation of Algeria forest lands at an annual rate of 45,000 to 50,000 ha. From 1985 to 2010 in 40 provinces of northern Algeria, 42,555 forest fires have burned a total...

  20. 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

  1. 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

  2. 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

    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.

  3. 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

  4. 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.

  5. 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.

  6. A last interglacial fauna from the Eastern Sahara

    NASA Astrophysics Data System (ADS)

    Kowalski, Kazimierz; Neer, Wim van; Bocheński, Zygmunt; Młynarski, Marian; Rzebik-Kowalska, Barbara; Szyndlar, Zbigniew; Gautier, Achilles; Schild, Romuald; Close, Angela E.; Wendorf, Fred

    1989-11-01

    Recent work on the middle Paleolithic at Bir Tarfawi, in the hyperarid Eastern Sahara (<1 mm of rain per annum), has yielded a rich faunal assemblage, including several thousand remains of fish, amphibians, reptiles, birds, and small mammals. They are derived from the sediments of two consecutive lakes dated by several techniques to about 135,000 yr B.P. Fifty-nine taxa have been identified and indicate that at times during the Last Interglaciation the area received at least 500 mm of rainfall as a result of the northward shift of the monsoon belt, and that, on several occasions, there may have been water connections between Bir Tarfawi and unidentified but permanent bodies of water elsewhere.

  7. Antimicrobial activity of Ammodaucus leucotrichus fruit oil from Algerian Sahara.

    PubMed

    El-Haci, Imad Abdelhamid; Bekhechi, Chahrazed; Atik-Bekkara, Fewzia; Mazari, Wissame; Gherib, Mohamed; Bighelli, Ange; Casanova, Joseph; Tomi, Félix

    2014-05-01

    Three fruit oil samples of Ammodaucus leucotrichus Cosson & Durieu from Algerian Sahara were obtained by hydrodistillation and analyzed by GC(RI), GC-MS and 13C NMR spectroscopy. The main compounds were perillaldehyde (87.0-87.9%) and limonene (7.4-8.2%). The antimicrobial effect of the essential oil was evaluated against bacteria, yeasts and filamentous fungi. High antibacterial activity was observed against Escherichia coli, Staphylococcus aureus. Enterobacter cloaceae, Bacillus cereus and Salmonella typhimurium, with MIC values between 0.5-1.0 microL/mL. Fungal strains were also sensitive to the essential oil (MIC values: 0.25-0.75 microL/mL).The most potent activity was observed against the filamentous fungi, Fusarium oxysporum and Aspergillusflavus (0.25-0.50 microL/mL).

  8. [The reappearance of chancroid in Algeria].

    PubMed

    Boudghene-Stambouli, O; Merad-Boudia, A; Aissa-Mamoun, A

    1992-01-01

    After 35 observations of the chancroid observed in the department of dermato-venereology of the University Hospital of Tlemcen (West Algeria) from August 1988 to December 1991, we are led to analyze the flare of this sexual transmitted disease. The principal affected subjects are single male no older than 30 years, having had sexual intercourse with prostitutes (30/35). Less than 10 days (19/29) after the sexual contacts, the ulcer appears, and most often unique (25/35), mildly painful, accompanied frequently by adenopathies (31/35). The contamination took place mainly in Bel Abbès--city located at 90 km from Tlemcen--(12 cases), in Tlemcen (4 cases) and Morocco (5 cases). The treatment based on sulfonamides, erythromycin and tetracycline or doxycycline, has been constantly efficient. No concomitant HIV infection has been revealed. The chancroid is the first STD observed in our department in 1991, and also, the first cause for genital ulcer.

  9. Algeria- Gemini 7, Earth-Sky View

    NASA Image and Video Library

    1965-12-05

    S65-63830 (5 Dec. 1965) --- Algeria, south-southeast of the Colomb Bechar area, as seen from the National Aeronautics and Space Administration's Gemini-7 spacecraft. Sand dunes are 200 to 300 feet high in the Grand Erg Occidental area. The Quod Sacura River can be seen in the upper left corner. The white spot in the middle of the picture is the Sebcha el Malah salt beds. It should be noted that the area had just experienced very heavy rains (first in many years) and the stream and salt flat are inundated. This photograph was taken with a modified 70mm Hasselblad camera, with Eastman Kodak, Ektachrome MS (S.O. 217) color film. Photo credit: NASA

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

    PubMed Central

    Both, Christiaan

    2016-01-01

    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

  11. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Genetic diversity of Mycobacterium tuberculosis strains isolated in Algeria: Results of spoligotyping.

    PubMed

    Ifticene, Malika; Kaïdi, Saïd; Khechiba, Mesbah-Mounir; Yala, Djamel; Boulahbal, Fadila

    2015-12-01

    Molecular typing tools, including spoligotyping, are currently widely used in the monitoring and study of the dynamics of tuberculosis epidemics. A study of the molecular profile of a sample of 129 Myobacterium tuberculosis strains isolated during 2011 was carried out in the National Reference Laboratory for Tuberculosis and Mycobacteria at the Pasteur Institute of Algeria. This sample was selected at random from a set of 350 strains isolated from tuberculosis patients from central and eastern areas of the country. Genotypic analysis helped to clarify the frequencies of the different genotypes in the current study population: H family, 29%; LAM family, 26%; T family, 25%; S family, 5%, and other genomic families, including orphan strains, 15%. The study of strains isolated between January and December 2011 has allowed insight into the frequency of different genomic families and the importance of existing clusters in the population of central and eastern Algeria. Copyright © 2015 Asian African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.

  13. Evidence of Laurussian affinity for parts of the Mauritanides and Souttoufides (Moroccan Sahara)

    NASA Astrophysics Data System (ADS)

    Gärtner, Andreas; Villeneuve, Michel; Linnemann, Ulf; El Archi, Abdelkrim; Bellon, Hervé

    2013-04-01

    The Soutouffide belt is located in the southern part of the Moroccan Sahara. Representing the northern section of the Carboniferous Mauritanide belt, it extends from Morocco to Senegal. The Dhlou and Adrar Souttouf Massifs, both of which belong to the Souttoufide belt, are located on the western margin of the Archean Reguibat Shield. Previously, the Adrar Souttouf Massif has been suggested to be part of the Variscan Mauritanian-Appalachian system. To date the Moroccan Sahara has been one of the least studied regions in West Africa. This study presents new zircon ages from two units of the Adrar Souttouf Massif which have nevertheless allowed us to hypothesise a complex polyphased history. The Massif can be subdivided into four NNE-SSW trending units (listed here from east to west). The Sebkha Matallah unit represents the eastern margin of the Adrar Souttouf Massif and is thrust over the Ordovician to Devonian sedimentary Dhloat Ensour Group to the east. A central (Dayet Lawda) unit consisting of mafic and ultramafic rocks is interpreted as a possible remnant of Neoproterozoic oceanic crust or mafic terranes. The western Sebkha Gezmayet and Oued Togba units are mainly composed of granitoids and orthogneisses. Zircon ages of the Tonian-Stenian (1.4-1.0 Ga) were recorded in the Oued Togba and Sebkha Gezmayet units and suggest an Avalonian-Meguman-like relationship. Three other age groups were obtained in these two units: 610 to 570 Ma (Pan-African), 530 to 490 Ma (Cambrian), and 440 to 270 Ma. The latter population cannot result from Variscan orogeny alone, and is possibly linked to the Salinic and Acadian orogenies of Laurentia. Zircon age populations at ~3.0 Ga and ~2.65 Ga determined for two granite samples from the Archean foreland are in accordance to data already published. Ages of between 226 Ma (Upper Triassic) and 158 Ma (Upper Jurassic) result from lower intercepts of discordia lines and are interpreted as a Mesozoic thermal overprint of the area attributed

  14. Phenotypic and genotypic diversity of Genista saharae microsymbionts from the infra-arid region of Tunisia.

    PubMed

    Mahdhi, M; Nzoué, A; Gueye, F; Merabet, C; de Lajudie, P; Mars, M

    2007-12-01

    Genista saharae, indigenous of Sahara, is a spontaneous shrub that plays an important ecological role for the preservation and fertility of poor and eroded soils. This legume has not been examined for its root nodule bacteria. The taxonomic diversity of bacteria from root nodules of G. saharae growing in the infra-arid region of Tunisia was investigated. A total of 28 bacterial strains isolated from root nodules of G. saharae grown in Tunisian soil were characterized using a polyphasic approach including phenotypic characteristics, PCR-RFLP of 16S rDNA and 16S rRNA gene sequencing. It was found that new isolates are diverse and affiliated to Ensifer (75%), Rhizobium (10%) and Phyllobacterium (15%). The Phyllobacterium isolates lacked the capacity for nodule formation on this plant. Genista saharae formed nodules with diverse rhizobia in Tunisian soils. Furthermore, our results support the presence of non-nodulating commensal strains (Phyllobacterium) in legumes nodule. This study is the first report on the characterization of G. saharae microsymbionts in Tunisia.

  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. Remote sensing of the hydrologic history of the eastern Sahara

    NASA Astrophysics Data System (ADS)

    Farr, T. G.; Blom, R. G.; Paillou, P.

    2010-12-01

    The eastern Sahara Desert has never been thoroughly mapped in terms of the landforms and subsurface signs of past climates conducive to human occupation. As part of ongoing work and through a new proposal to NASA, we are generating new maps of the paleohydrology, topography, geomorphology, and surficial deposits of the area and developing GIS-based models which use the data to pinpoint past resources and travel pathways. The maps we are generating will constitute a unique resource for exploration for water and archeological sites in the Gilf Kebir and other regions of NE Africa. That the Sahara was favorable for human habitation at times has long been known. With the remarkable paleo-landscape revealed by the L-band (25 cm) Shuttle Imaging Radar-A in 1981, it became clear that ancient humans concentrated along integrated drainage systems dubbed “radar rivers” by McCauley and colleagues. However SIR-A and subsequent long-wavelength radar coverage was limited and regional understanding of the drainage network has remained elusive. We are mapping the area with three sensors optimized for mapping and characterizing arid regions: The Japanese PALSAR L-band imaging radar, NASA’s SRTM, and ASTER. Together these sensors provide full coverage of the area allowing characterization and mapping of surface and subsurface landforms formed and modified by former wetter climates. In particular and following the work of Ghoneim, Robinson, El Baz and others, we are mapping the regional drainage network revealed by the radar images and applying modern analysis tools to the drainage basins and channels. These include drainage density, channel gradient vs. distance, and longitudinal and cross-channel topographic profiles. We use these quantities to estimate a stream’s past approach to equilibrium and this to infer balances between climate, tectonic uplift, and other changes in base level. Discovery over the last few years of large paleolakes (e.g. Mega Lake Chad, North Darfur

  17. 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. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  18. Diabetes mellitus and Ramadan in Algeria.

    PubMed

    Chentli, Farida; Azzoug, Said; Amani, Mohammed El Amine; Elgradechi, Aldjia

    2013-10-01

    Ramadan, one of the five pillars of Islam, is a holy month in Algeria where diabetes mellitus (DM) is more frequent in urban areas with a frequency which varies from 8 to 16%. DM complications are broadly as frequent as in developed countries, except for neuropathy which seems more frequent. Despite contraindications which are regularly explained to our patients and despite the flexible side of Islam toward chronic diseases, most Algerian people with DM insist on fasting. Not fasting is considered a sin and shameful. There are also other reasons put forward by diabetic persons, such as very strong religious faith, habit of fasting together with the whole family since an early age, solidarity with the family, friends, and neighbors, and finally and probably because of the desire to appear "normal" and share a festive and a spiritual atmosphere of Ramadan. As in other Muslim countries, severe hypoglycemia the main motive of hospitalizations during the holy month, ketoacidosis, dehydration, orthostatic hypotension and thrombosis are some of the complications which Algerian people with DM are exposed to when fasting.

  19. Diabetes mellitus and Ramadan in Algeria

    PubMed Central

    Chentli, Farida; Azzoug, Said; Amani, Mohammed El Amine; Elgradechi, Aldjia

    2013-01-01

    Ramadan, one of the five pillars of Islam, is a holy month in Algeria where diabetes mellitus (DM) is more frequent in urban areas with a frequency which varies from 8 to 16%. DM complications are broadly as frequent as in developed countries, except for neuropathy which seems more frequent. Despite contraindications which are regularly explained to our patients and despite the flexible side of Islam toward chronic diseases, most Algerian people with DM insist on fasting. Not fasting is considered a sin and shameful. There are also other reasons put forward by diabetic persons, such as very strong religious faith, habit of fasting together with the whole family since an early age, solidarity with the family, friends, and neighbors, and finally and probably because of the desire to appear “normal” and share a festive and a spiritual atmosphere of Ramadan. As in other Muslim countries, severe hypoglycemia the main motive of hospitalizations during the holy month, ketoacidosis, dehydration, orthostatic hypotension and thrombosis are some of the complications which Algerian people with DM are exposed to when fasting. PMID:24251192

  20. Plague Outbreak in Libya, 2009, Unrelated to Plague in Algeria

    PubMed Central

    Cabanel, Nicolas; Leclercq, Alexandre; Chenal-Francisque, Viviane; Annajar, Badereddin; Rajerison, Minoarisoa; Bekkhoucha, Souad; Bertherat, Eric

    2013-01-01

    After 25 years of no cases of plague, this disease recurred near Tobruk, Libya, in 2009. An epidemiologic investigation identified 5 confirmed cases. We determined ribotypes, Not1 restriction profiles, and IS100 and IS1541 hybridization patterns of strains isolated during this outbreak. We also analyzed strains isolated during the 2003 plague epidemic in Algeria to determine whether there were epidemiologic links between the 2 events. Our results demonstrate unambiguously that neighboring but independent plague foci coexist in Algeria and Libya. They also indicate that these outbreaks were most likely caused by reactivation of organisms in local or regional foci believed to be dormant (Libya) or extinct (Algeria) for decades, rather than by recent importation of Yersinia pestis from distant foci. Environmental factors favorable for plague reemergence might exist in this area and lead to reactivation of organisms in other ancient foci. PMID:23347743

  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.

  2. Plague outbreak in Libya, 2009, unrelated to plague in Algeria.

    PubMed

    Cabanel, Nicolas; Leclercq, Alexandre; Chenal-Francisque, Viviane; Annajar, Badereddin; Rajerison, Minoarisoa; Bekkhoucha, Souad; Bertherat, Eric; Carniel, Elisabeth

    2013-02-01

    After 25 years of no cases of plague, this disease recurred near Tobruk, Libya, in 2009. An epidemiologic investigation identified 5 confirmed cases. We determined ribotypes, Not1 restriction profiles, and IS100 and IS1541 hybridization patterns of strains isolated during this outbreak. We also analyzed strains isolated during the 2003 plague epidemic in Algeria to determine whether there were epidemiologic links between the 2 events. Our results demonstrate unambiguously that neighboring but independent plague foci coexist in Algeria and Libya. They also indicate that these outbreaks were most likely caused by reactivation of organisms in local or regional foci believed to be dormant (Libya) or extinct (Algeria) for decades, rather than by recent importation of Yersinia pestis from distant foci. Environmental factors favorable for plague reemergence might exist in this area and lead to reactivation of organisms in other ancient foci.

  3. Multi vegetation model evaluation of the Green Sahara climate regime

    NASA Astrophysics Data System (ADS)

    Hopcroft, Peter O.; Valdes, Paul J.; Harper, Anna B.; Beerling, David J.

    2017-07-01

    During the Quaternary, the Sahara desert was periodically colonized by vegetation, likely because of orbitally induced rainfall increases. However, the estimated hydrological change is not reproduced in climate model simulations, undermining confidence in projections of future rainfall. We evaluated the relationship between the qualitative information on past vegetation coverage and climate for the mid-Holocene using three different dynamic vegetation models. Compared with two available vegetation reconstructions, the models require 500-800 mm of rainfall over 20°-25°N, which is significantly larger than inferred from pollen but largely in agreement with more recent leaf wax biomarker reconstructions. The magnitude of the response also suggests that required rainfall regime of the early to middle Holocene is far from being correctly represented in general circulation models. However, intermodel differences related to moisture stress parameterizations, biases in simulated present-day vegetation, and uncertainties about paleosoil distributions introduce uncertainties, and these are also relevant to Earth system model simulations of African humid periods.

  4. Managing tuberculosis and HIV in sub-Sahara Africa.

    PubMed

    Lalloo, Umesh G; Pillay, Sandy

    2008-08-01

    Tuberculosis (TB) and HIV represent a deadly duo in sub-Sahara Africa, a region most affected by both diseases. The HIV epidemic has aggravated already strained and frequently poorly performing TB control programs. These programs face numerous challenges, and novel, regionally appropriate solutions need to be developed. In the context of TB, some challenges include the rapid diagnosis of active TB in the face of paucibacillary lung disease and atypical presentations with HIV/AIDS, lack of clinical expertise, poor contact tracing, limited laboratory facilities, delayed recognition of drug-resistant TB, increased workload of health care workers, erratic drug supplies, inadequate isolation facilities, and environmental and personal protection in drug-resistant cases. Similar problems exist in the context of HIV but are aggravated by the need for complex antiretroviral drug regimens and lifelong treatment. Treating both conditions invites drug interactions and toxic effects that are common to both HIV and TB treatment and the vexing question of when to introduce antiretroviral treatment in subjects with active TB. Combining HIV and TB care has the potential to bring additional infrastructural and human resources to the respective programs, with synergistic benefits.

  5. Prevalence and determinants of hypertension in the Algerian Sahara.

    PubMed

    Temmar, Mohamed; Labat, Carlos; Benkhedda, Salim; Charifi, Meriem; Thomas, Frederique; Bouafia, Mohamed Tahar; Bean, Kathy; Darne, Bernadette; Safar, Michel E; Benetos, Athanase

    2007-11-01

    In-Salah is a city-oasis located in the middle of the Algerian Sahara, a desert area whose drinking water has a high sodium content. No cardiovascular epidemiological studies have ever been conducted in this region. A randomized sample of 635 men and 711 women, aged 40-99 years, was studied. Blood pressure measurements, combined with a clinical questionnaire that included educational and socio-economic data, and standard blood samples for the detection of dyslipidemia and diabetes mellitus, were collected. The mean age was 55 +/- 12 years. The prevalence of hypertension was 44% and was highly influenced by age, sex, skin colour, educational status, obesity and metabolic parameters. The higher prevalence of hypertension among black individuals was independent of socio-economic and educational levels, and of metabolic parameters. The presence of antihypertensive treatment was three times more frequent in women than in men, and there was no difference according to skin colour. Among treated subjects, 25% were well controlled, and this percentage was similar among both black and white individuals. Epidemiological studies in such an emergent population indicate that hypertension is a major public health problem. The high sodium content in drinking water in this region could play a major role in the development of hypertension.

  6. 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.

  7. New Instructional Materials on Africa South of the Sahara (1969-1970). A Supplement to Africa South of the Sahara: A Resource and Curriculum Guide.

    ERIC Educational Resources Information Center

    Beyer, Barry K.

    This guide cites instructional materials on Africa south of the Sahara which have become available since February 1969. Acknowledging the probability of inaccuracies in the majority of the materials cited, the guide neither evaluates nor promotes items, but simply presents annotations of readings, textbooks, fact sheets, atlases, African…

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

    PubMed

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

    2011-01-11

    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.

  9. [Epidemiology of Tinea capitis in the suburbs of Tipasa, Algeria].

    PubMed

    Bendjaballah-Laliam, A; Djazer, H

    2014-06-01

    Tinea capitis represent a public health problem in Algeria, despite improvement of living conditions. We conducted a retrospective study of cases diagnosed in the hospital Hadjout (Tipasa), Algeria, during 3 years (January 2010-January 2013). Among a total of 213 hair samples, 133 were positive (direct examination or culture). Incidence average was 44 cases per year. Patients were under 12 years of age in 91%. Three species of dermatophytes were isolated: Trichophyton violaceum (66%), Microsporum canis (32.5%) and Trichophyton mentagrophytes (1.5%). No favus was diagnosed during the study period. Copyright © 2014. Published by Elsevier Masson SAS.

  10. Late Devonian conodonts and event stratigraphy in northwestern Algerian Sahara

    NASA Astrophysics Data System (ADS)

    Mahboubi, Abdessamed; Gatovsky, Yury

    2015-01-01

    Conodonts recovered from the Late Devonian South Marhouma section comprise 5 genera with 31 species (3 undetermined). The fauna establishes the presence of MN Zones 5, undifferentiated 6/7, 8/10 for the Middle Frasnian, the MN Zones 11, 12, 13 for the Upper Frasnian as well as the Early through Late triangularis Zones in the basal Famennian. The outcropping lithological succession is one of mostly nodular calcilutites alternating with numerous marly and shaly deposits, which, in the lower and upper part, comprise several dysoxic dark shale intervals. Among these the Upper Kellwasser horizon can be precisely dated and as such the presence of the terminal Frasnian Kellwasser Event is recognized for the first time in Algeria. Both the Middlesex and Rhinestreet Events cannot yet be precisely located, but supposedly occur among the dark shale horizons in the lower part of the section. However, their assignment to a precise level has so far not been established. Though poor in conodont abundance the South Marhouma section provides first evidence of the presence of several Montagne Noire conodont zones within the so far widely unstudied Frasnian of the Ougarta Chain. As such it is considered representative for the northwestern Algerian Saoura region.

  11. The Impact of Sahara desertification on Arctic cooling during the Holocene

    NASA Astrophysics Data System (ADS)

    Davies, Frazer; Renssen, Hans

    2013-04-01

    The Holocene is clearly defined by an early thermal maximum, followed by a steadily declining global temperature that persists up until the recent anthropogenically induced warming. This gradual cooling is accredited to the Milankovitch theory of orbitally induced climate change. However, over the course of the Holocene the Sahara region has undergone a dramatic change, from a humid environment (Green Sahara) to a hyper-arid environment (Desert Sahara). This is likely to have had profound effects upon the regional and global climate, due to the change in surface albedo and moisture content of the atmosphere in this region. In this study we have looked at how desertification in the Sahara between 9 and 0ka contributed to cooling on a global scale, but most noticeably in the Arctic. Using LOVECLIM, a global climate model, we show that the desertification of the Sahara during the Holocene was responsible for a significant degree of cooling, not only in the Saharan region, but also in the high-latitudes through a teleconnection involving both the atmosphere and ocean. The change in vegetation type from predominantly grass to desert, lowers the surface albedo in the Sahara region, which reduces local temperatures, increases surface pressure and decreases the wind strength in the equatorial Atlantic. This reduces the pressure gradient between the northern and equatorial Atlantic, resulting in weaker westerly winds and therefore a reduction in the transport of heat and energy to the high northern latitudes. As a result temperatures in the Arctic cool. The overall Arctic cooling from 9 to 0ka, due to orbital and greenhouse gases, ranges from 3-4°C. We show that 1-2°C of this cooling is the result of a long-distance impact from the Sahara desertification, with the remaining cooling due to the localised effects of insolation changes. However, the localised response is clearly delayed from summer to autumn, due to a combination of processes, including the sea-ice insulation

  12. Geological fieldwork in the Libyan Sahara: A multidisciplinary approach

    NASA Astrophysics Data System (ADS)

    Meinhold, Guido; Whitham, Andrew; Howard, James P.; Morton, Andrew; Abutarruma, Yousef; Bergig, Khaled; Elgadry, Mohamed; Le Heron, Daniel P.; Paris, Florentin; Thusu, Bindra

    2010-05-01

    Libya is one of the most hydrocarbon-rich countries in the world. Its large oil and gas reserves make it attractive to international oil and gas companies, which provide the impetus for field-based research in the Libyan Sahara. North Africa is made up of several enormous intracratonic basins, two of which are found in southern Libya: the Murzuq Basin, in the southwest, and the Kufra Basin, in the southeast, separated by the Tibesti Massif. Both basins are filled with Palaeozoic and Mesozoic clastic sedimentary rocks reaching up to 5 km in thickness. These basins developed from the Cambrian onwards following an earlier period of orogenesis (the Panafrican Orogeny) in the Neoproterozoic. Precambrian metasediments and granitoids are unconformably overlain by Cambrian and Ordovician conglomerates and sandstones. They show a transitional environment from continental to shallow marine. Skolithos-bearing sandstone is common in Ordovician strata. By the Late Ordovician, ice masses had developed across West Gondwana. Upon melting of the ice sheets in the latest Hirnantian, large volumes of melt water and sediment were released that were transported to the periphery of Gondwana. In Libya, these sediments are predominantly highly mature sandstones, which, in many places, are excellent hydrocarbon reservoirs. Polished and striated surfaces in these sandstones clearly point to their glaciogenic origin. Following Late Ordovician deglaciation, black shale deposition occurred in the Silurian. Some of the shales are characterised by high values of total organic carbon (TOC). These shales are commonly referred to as ‘hot shales' due to their associated high uranium content, and are the major source rock for Early Palaeozoic-sourced hydrocarbons in North Africa. Late Ordovician glaciogenic sediments and the Early Silurian ‘hot shales' are therefore the main focus of geological research in the Libyan Sahara. Fluvial conglomerates and sandstones of Devonian age unconformably

  13. Changing patterns of mobility as a response to climatic deterioration and aridification in the middle Holocene Southern Sahara.

    PubMed

    Stojanowski, Christopher M; Knudson, Kelly J

    2014-05-01

    The African Humid Period witnessed a rapid human re-occupation of the Sahara as numerous lakes formed during the Holocene climatic optimum circa 10-5 kya. Permanent waters attracted a variety of aquatic and terrestrial fauna allowing for long-term occupation of specific paleolake basins. The Gobero paleolake in central Niger was one such location that preserves a unique mortuary record from the southern Sahara. Here, we use radiogenic strontium isotope analysis to investigate how human communities adapted to aridification throughout the Holocene. In particular, we examine the effects of increasing climate instability on patterns of human mobility. Results of radiogenic strontium isotope analysis of enamel and bone samples from Middle Holocene burials (∼7.2-4.9 kya) indicate predominantly local values with no evidence for sex-based variation. Comparisons of radiogenic strontium isotope data with previously published (Stojanowski and Knudson: Am J Phys Anthropol 146 (2011) 49-61) Early Holocene burials (∼9.7-8.3 kya) indicate significant differences in both enamel and bone values. Middle Holocene individuals demonstrate a predominantly non-local signature for enamel values and a predominantly local signature for bone values. Those individuals with non-local bone values always demonstrated non-local enamel values; however, the opposite was not the case. This suggests a divergence of mobility strategies during the Middle Holocene with a minority of individuals maintaining a more mobile existence throughout their life and others maintaining a similar strategy as Early Holocene hunter-gatherers that was tied to the paleolake basin. The more mobile individuals likely lived during the terminal phase of the lake's occupation. One response to aridification by Saharan peoples, then, was increasing mobility. Copyright © 2014 Wiley Periodicals, Inc.

  14. LOW {sup 60}FE ABUNDANCE IN SEMARKONA AND SAHARA 99555

    SciTech Connect

    Tang, Haolan; Dauphas, Nicolas

    2015-03-20

    Iron-60 (t{sub 1/2} = 2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of Solar System formation and date early Solar System events. A high abundance of {sup 60}Fe({sup 60}Fe/{sup 56}Fe ≈ 4 × 10{sup −7}) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements of a wide range of meteoritic materials, including chondrules, showed that {sup 60}Fe was present in the early Solar System at a much lower level ({sup 60}Fe/{sup 56}Fe ≈ 10{sup −8}). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ∼2× chondritic. Here, we show that the initial {sup 60}Fe/{sup 56}Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ∼24× chondritic is (5.39 ± 3.27) × 10{sup −9}. We also establish the initial {sup 60}Fe/{sup 56}Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be (1.97 ± 0.77) × 10{sup −9}. These results demonstrate that the initial abundance of {sup 60}Fe at Solar System birth was low, corresponding to an initial {sup 60}Fe/{sup 56}Fe ratio of (1.01 ± 0.27) × 10{sup −8}.

  15. Low 60Fe Abundance in Semarkona and Sahara 99555

    NASA Astrophysics Data System (ADS)

    Tang, Haolan; Dauphas, Nicolas

    2015-03-01

    Iron-60 (t1/2 = 2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of Solar System formation and date early Solar System events. A high abundance of 60Fe(60Fe/56Fe ≈ 4 × 10-7) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements of a wide range of meteoritic materials, including chondrules, showed that 60Fe was present in the early Solar System at a much lower level (60Fe/56Fe ≈ 10-8). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ˜2× chondritic. Here, we show that the initial 60Fe/56Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ˜24× chondritic is (5.39 ± 3.27) × 10-9. We also establish the initial 60Fe/56Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be (1.97 ± 0.77) × 10-9. These results demonstrate that the initial abundance of 60Fe at Solar System birth was low, corresponding to an initial 60Fe/56Fe ratio of (1.01 ± 0.27) × 10-8.

  16. 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…

  17. Notice to Nurserymen of the Naming and Release for Propagation of Sahara Sunset, A New African Hibiscus Cultivar

    USDA-ARS?s Scientific Manuscript database

    Hibiscus asetosella 'Sahara Sunset' is an African hibiscus released by the United States Department of Agriculture Agricultural Research Service that was Developed by Dr. Cecil Pounders at the Thad Cochran Southern Horticultural Laboratory in Poplarville, MS. ‘Sahara Sunset’ is a tropical shrub (USD...

  18. 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…

  19. 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…

  20. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A 100-item bibliography with abstracts of books, newspaper articles, and periodical articles in English and French published predominantly in 1970 offers information on various aspects of education in Algeria, Libya, Morocco, and Tunisia. Emphasis is placed on sections dealing with: (1) educational philosophy, administration, statistics, and…

  1. Algerian orphans and colonial Christianity in Algeria, 1866-1939.

    PubMed

    Taithe, Bertrand

    2006-01-01

    This article considers the exceptional fate of the orphan survivors of the great Algerian demographic crisis of the late 1860s who subsequently converted to Catholicism. Using a prosopographical approach, this study seeks to highlight the complexities of national identity in France and to explore some of the racial tensions emerging in Algeria in the late nineteenth century.

  2. [The necessity of controlling population growth in Algeria].

    PubMed

    Sari, D

    1990-01-01

    The case is made for controlling Algeria's rapid rate of population growth. The author notes that at the present rate of growth the population is doubling every 20 years. The decline in the labor market and increases in unemployment and underemployment are also examined. The need for strong population policies and programs is stressed.

  3. Algeria to use gas to meet energy demands

    SciTech Connect

    Not Available

    1986-12-01

    Sonelgaz, Algeria's natural gas distribution monopoly, plans to supply all major towns in the country with natural gas for domestic energy demands by 1989. The utility uses copper tubing in residences and plastic pipe for distribution mains and services to the houses for new construction and conversion to natural gas from LPG systems.

  4. 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…

  5. 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…

  6. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A 100-item bibliography with abstracts of books, newspaper articles, and periodical articles in English and French published predominantly in 1970 offers information on various aspects of education in Algeria, Libya, Morocco, and Tunisia. Emphasis is placed on sections dealing with: (1) educational philosophy, administration, statistics, and…

  7. 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.

  8. 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

  9. Climate-driven ecosystem succession in the Sahara: the past 6000 years.

    PubMed

    Kröpelin, S; Verschuren, D; Lézine, A-M; Eggermont, H; Cocquyt, C; Francus, P; Cazet, J-P; Fagot, M; Rumes, B; Russell, J M; Darius, F; Conley, D J; Schuster, M; von Suchodoletz, H; Engstrom, D R

    2008-05-09

    Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a "green Sahara" to the present hyperarid desert. Our continuous 6000-year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site-specific thresholds. Strong reductions in tropical trees and then Sahelian grassland cover allowed large-scale dust mobilization from 4300 calendar years before the present (cal yr B.P.). Today's desert ecosystem and regional wind regime were established around 2700 cal yr B.P. This gradual rather than abrupt termination of the African Humid Period in the eastern Sahara suggests a relatively weak biogeophysical feedback on climate.

  10. The Emergence of Transnational Terrorist Safe Havens: A Comparative Analysis of the Federally Administered Tribal Areas in Pakistan and Kabylia in Algeria

    DTIC Science & Technology

    2012-12-01

    INTENTIONALLY LEFT BLANK xiii LIST OF ACRONYMS AND ABBREVIATIONS ALN l’Armee de Liberation National ANDI National Agency for Investment and...www.ispu.org/files/PDFs/fata_report.pdf. 5 International Crisis Group, “Algeria: Agitation and Impasse in Kabylia,” Middle East/ North Africa ...North, West and Central Africa : From 9/11 to the Arab Spring, Potomac Institute for Policy Studies report (Arlington, 2012). 5 relationship of

  11. 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

  12. 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

  13. Health effects from Sahara dust episodes in Europe: literature review and research gaps.

    PubMed

    Karanasiou, A; Moreno, N; Moreno, T; Viana, M; de Leeuw, F; Querol, X

    2012-10-15

    The adverse consequences of particulate matter (PM) on human health have been well documented. Recently, special attention has been given to mineral dust particles, which may be a serious health threat. The main global source of atmospheric mineral dust is the Sahara desert, which produces about half of the annual mineral dust. Sahara dust transport can lead to PM levels that substantially exceed the established limit values. A review was undertaken using the ISI web of knowledge database with the objective to identify all studies presenting results on the potential health impact from Sahara dust particles. The review of the literature shows that the association of fine particles, PM₂.₅, with total or cause-specific daily mortality is not significant during Saharan dust intrusions. However, regarding coarser fractions PM₁₀ and PM₂.₅₋₁₀ an explicit answer cannot be given. Some of the published studies state that they increase mortality during Sahara dust days while other studies find no association between mortality and PM₁₀ or PM₂.₅₋₁₀. The main conclusion of this review is that health impact of Saharan dust outbreaks needs to be further explored. Considering the diverse outcomes for PM₁₀ and PM₂.₅₋₁₀, future studies should focus on the chemical characterization and potential toxicity of coarse particles transported from Sahara desert mixed or not with anthropogenic pollutants. The results of this review may be considered to establish the objectives and strategies of a new European directive on ambient air quality. An implication for public policy in Europe is that to protect public health, anthropogenic sources of particulate pollution need to be more rigorously controlled in areas highly impacted by the Sahara dust.

  14. Quantifying particle size and turbulent scale dependence of dust flux in the Sahara using aircraft measurements

    NASA Astrophysics Data System (ADS)

    Rosenberg, Philip D.; Parker, Douglas J.; Ryder, Claire L.; Marsham, John H.; Garcia-Carreras, Luis; Dorsey, James R.; Brooks, Ian M.; Dean, Angela R.; Crosier, Jonathon; McQuaid, James B.; Washington, Richard

    2014-06-01

    The first size-resolved airborne measurements of dust fluxes and the first dust flux measurements from the central Sahara are presented and compared with a parameterization by Kok (2011a). High-frequency measurements of dust size distribution were obtained from 0.16 to 300 µm diameter, and eddy covariance fluxes were derived. This is more than an order of magnitude larger size range than previous flux estimates. Links to surface emission are provided by analysis of particle drift velocities. Number flux is described by a -2 power law between 1 and 144 µm diameter, significantly larger than the 12 µm upper limit suggested by Kok (2011a). For small particles, the deviation from a power law varies with terrain type and the large size cutoff is correlated with atmospheric vertical turbulent kinetic energy, suggesting control by vertical transport rather than emission processes. The measured mass flux mode is in the range 30-100 µm. The turbulent scales important for dust flux are from 0.1 km to 1-10 km. The upper scale increases during the morning as boundary layer depth and eddy size increase. All locations where large dust fluxes were measured had large topographical variations. These features are often linked with highly erodible surface features, such as wadis or dunes. We also hypothesize that upslope flow and flow separation over such features enhance the dust flux by transporting large particles out of the saltation layer. The tendency to locate surface flux measurements in open, flat terrain means these favored dust sources have been neglected in previous studies.

  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. 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.

  17. [The extension of cutaneous leishmaniasis in Algeria. Apropos of 25 cases observed in Wilaya de Tlemcen (West Algeria)].

    PubMed

    Boudghene-Stambouli, O; Merad-Boudia, A

    1991-01-01

    Following 25 observations, 19 of which are autochtonous, the authors bring to attention the problem of the cutaneous leishmaniasis in Algeria. Actually, this affection touches all the regions. The west part, supposed sofar untouched, has seen the hatching of a foyer in Tlemcen.

  18. Sedimentology of the Sbaa oil reservoir in the Timimoun basin (S. Algeria)

    SciTech Connect

    Mehadi, Z. )

    1990-05-01

    In 1980 oil was discovered in the Timimoun portion of the Sbaa depression in Southern Algeria. Until that time this basin had produced only dry gas. Since the 1980 oil discovery, several wells have been drilled. Data acquired from these wells were analyzed and are presented in this study. The oil reservoir is located within a sandstone interval of the Sbaa formation which has an average thickness of 75 m. The Sbaa lies between the Tournaisian (Lower Carboniferous) silts and the Strunian (uppermost Devonian) shales and sandstones. The sedimentological study reveals that the Sbaa formation contains bimodal facies consisting of coarse siltstones and fine sandstones. The sequence has been attributed to a deltaic environment developed in the central part of the Ahnet basin. The sources of the associated fluvial system are from the surrounding In-Semmen, Tinessourine, and Arak-Foum-Belrem paleohighs. Thermoluminescence indicates the provenance for the Sbaa sands was the crystalline basement Cambrian and Ordovician sections.

  19. 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

  20. A reassessment of the Quaternary Paleoclimatic data from the Sahara

    NASA Astrophysics Data System (ADS)

    Abotalib, A. Z.; Sultan, M.; Krishnamurthy, R. V.; Elkadiri, R.

    2016-12-01

    of thick Quaternary terraces in Sinai (up to 50 m)—where groundwater contribution is diminished—place their deposition into the glacial MIS2 (between 27 and 11 ka), a time period where no wet conditions were reported from the Western Desert. Findings call on re-visiting earlier practices for paleoclimatic interpretations of the Sahara.

  1. 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.

  2. [The humanitarian work of France in the Sahara. The Health Service of the army in the territories of Southern Algeria (1900-1976].

    PubMed

    Savelli, André

    2012-01-01

    Medical assistance to the Saharian populations (1900-1976) is viewed through its organization. The management of the Health Service in the Southern Territories, doctors, nursing staff, medical districts, centred on infirmary-hospitals and rural first-aid posts. We insist on the everrising free consultations and the care to sick and wounded patients in infirmaries; the fight against epidemics and social scourges. Then on French medical mission from 1963 to 1976, and on the humanitarian work by the Health Service throughout the five continents.

  3. Effects of ethnicity and gender on reliable measurements using the Sahara ultrasonometer.

    PubMed

    Tylavsky, Frances A; Carbone, Laura D; Bush, Andrew J

    2002-01-01

    The objectives of this study were to evaluate the relationship between age and ultrasound (US) parameters and to assess the influences of ethnicity, sex, body mass index (BMI), and age on the ability to obtain a reliable measurement as indicated by the Sahara software. Quantitative ultrasound parameters were assessed in 1554 African American and Caucasian men and women between the ages of 18 and 93 using the Sahara ultrasonometer. The relationships among age and broadband ultrasound attenuation, speed of sound (SOS), qualitative ultrasound index, and bone mineral density showed a decline in all US parameters with age. The relationship was linear for males and curvilinear for females for all parameters except SOS, which was also linear for females. The Sahara software indicated that 66% of the measurements for African American men were unreliable, 27% for African American females, 14% for Caucasian males, and 6% for Caucasian females. The factors found to contribute to the likelihood (odds ratio, [95% confidence interval]) of obtaining an unreliable estimate were having a high BMI (1.13, [1.1, 1.16]), being of African American ethnicity (5.29 [3.78, 7.41]), and being male (3.1 [2.8, 4.1]). Our study provides evidence that US results from the Sahara should be interpreted with caution in males, in individuals with African American ancestry, and in individuals with a high BMI.

  4. Evaluation of Africa South of the Sahara. An Inquiry Program for Grades 7-10.

    ERIC Educational Resources Information Center

    Beyer, Barry K.; And Others

    Project Africa, a social studies curriculum research and development project, is primarily engaged in testing new materials and techniques for teaching about Africa south of the Sahara in American secondary schools. The purpose of this technical report is to highlight the program's strengths and weaknesses from a variety of viewpoints -- those of…

  5. Africa South of the Sahara. Grade Twelve. [Resource Unit IV.] Project Social Studies.

    ERIC Educational Resources Information Center

    Minnesota Univ., Minneapolis. Project Social Studies Curriculum Center.

    This is the fourth of seven resource units for a twelfth grade course on value conflicts and policy decisions. The topic for this unit is Africa south of the Sahara. The objectives are listed as to generalizations, skills, and values. The double-page format relates objectives to pertinent content, teaching procedures, and instructional materials.…

  6. African South of the Sahara: An Objective Test for Secondary Schools. A World Regions Perception Survey.

    ERIC Educational Resources Information Center

    Carnegie-Mellon Univ., Pittsburgh, PA.

    Designed by Project Africa of Carnegie-Mellon University, these two test instruments have been used to discover what selected American secondary school students know or believe about Africa and other regions of the world. The first instrument, a 30-minute objective test, "Africa South of the Sahara," is comprised of 60 multiple-choice…

  7. Preliminary Bibliography on Africa South of the Sahara for Undergraduate Libraries.

    ERIC Educational Resources Information Center

    Ehrman, Edith; Morehouse, Ward

    This classified bibliography on Africa south of the Sahara and similar bibliographies on South Asia (LI 000 061) and East Asia (LI 000 881) have been compiled under the first phase of a three-year cooperative project to strengthen bibliographical resources for undergraduate libraries on "neglected" foreign areas. The bibliography in its…

  8. Africa South of the Sahara: A Resource Guide for Secondary School Teachers. Interim Report.

    ERIC Educational Resources Information Center

    Beyer, Barry K., Ed.

    Information to help educators develop a program of study about Africa south of the Sahara is presented in this guide for use with secondary school students. Appropriate objectives for a study of this region and its people are stated: the acquisition of sufficient information to make contemporary Africa intelligible, the formulation of concepts…

  9. Tropical storm activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Emanuel, Kerry; Chiacchio, Marc; Diro, Gulilat T.; Zhang, Qiong; Sushama, Laxmi; Stager, J. Curt; Donnelly, Jeffrey P.

    2017-04-01

    Tropical cyclones (TCs) have devastating socioeconomic impacts and understanding the nature and causes of their natural variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are still very few both temporally and geographically. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yr BP) characterized by increased boreal summer insolation, vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also prescribed vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust lead to more favorable conditions for tropical storm development compared to the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the greening of the Sahara triggers a change in atmospheric circulation that embraces the entire tropics. Furthermore, while stronger boreal summer insolation and hence warmer sea surface temperature may actually lower TC activity in the Northern Hemisphere as shown in previous studies, accounting for the Sahara greening and its associated reduction in dust emissions leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and east coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of TCs, and suggests the roles they might play in a future warmer climate.

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

    USDA-ARS?s Scientific Manuscript database

    '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. Green Sahara impact on mid-latitudes during mid-Holocene

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    In the mid-Holocene (6 kyr before present), North Africa was characterised by a vegetated Sahara and a stronger summer monsoon, resulting in a wetter climate. These conditions, induced by the different Earth's orbital parameters, and maintained by the precipitation-vegetation feedback, were associated with a substantial change of the regional atmospheric dynamics, with influences extending across the global Tropics and beyond. In this study, we explore the mid-latitude response to the vegetated Sahara in the mid-Holocene. We use the EC-Earth climate model to simulate the North African environment during mid-Holocene, i.e. extensive vegetation over the Sahara, and a consequent reduced dust emission. Vegetation and dust reduction are prescribed both in combination and in isolation, to determine the specific responses to the individual forcings. A significant response at mid-latitudes is simulated during boreal summer, when the precipitation-vegetation feedback is maximum in the Sahara. Results show increased precipitation over Mediterranean and Middle East, and warm anomalies across western Europe. This response is associated with the modification of the atmospheric circulation in the Euro-Atlantic sector. Specifically, the intensification of the subtropical jetstream favours precipitation across the Middle East, while a positive anomaly in the North Atlantic Oscillation leads the warming further west. These results suggest important implications for the understanding of future climate scenarios in the region, since a number of simulations project wetter conditions in North Africa.

  12. Abrupt shifts of the Sahara-Sahel boundary during Heinrich Stadials

    NASA Astrophysics Data System (ADS)

    Collins, J. A.; Govin, A.; Mulitza, S.; Heslop, D.; Zabel, M.; Hartmann, J.; Röhl, U.; Wefer, G.

    2013-01-01

    Relict dune fields that are found at 14° N in the modern-day African Sahel are testament to equatorward expansions of the Sahara desert during the late Pleistocene. However, difficulties of dating dune formation mean that abrupt millennial-scale climate events are not always resolved in these records. High-resolution marine core studies have identified Heinrich Stadials as the dustiest periods of the last glacial, although no studies have mapped the spatio-temporal evolution of dust export from West Africa. We use the major-element composition of four marine sediment cores to reconstruct the spatial extent of Saharan-dust versus river-sediment input to the continental margin from West Africa over the last 60 ka. This allows us to map the position of the sediment composition corresponding to the Sahara-Sahel boundary. Our records indicate that the Sahara-Sahel boundary reached its most southerly position (13° N) during Heinrich Stadials, suggesting that these were the periods when the sand dunes formed at 14° N on the continent, rather than at the Last Glacial Maximum. We find that SSB position was closely linked to North Atlantic sea surface temperatures, which during Heinrich Stadials triggered abrupt increases of aridity and wind strength in the Sahel, exposing new dust sources. This result illustrates the influence of the Atlantic meridional overturning circulation on the southerly extent of the Sahara desert and has implications for global atmospheric dust loading.

  13. Abrupt shifts of the Sahara-Sahel boundary during Heinrich stadials

    NASA Astrophysics Data System (ADS)

    Collins, J. A.; Govin, A.; Mulitza, S.; Heslop, D.; Zabel, M.; Hartmann, J.; Röhl, U.; Wefer, G.

    2013-05-01

    Relict dune fields that are found as far south as 14° N in the modern-day African Sahel are testament to equatorward expansions of the Sahara desert during the Late Pleistocene. However, the discontinuous nature of dune records means that abrupt millennial-timescale climate events are not always resolved. High-resolution marine core studies have identified Heinrich stadials as the dustiest periods of the last glacial in West Africa although the spatial evolution of dust export on millennial timescales has so far not been investigated. We use the major-element composition of four high-resolution marine sediment cores to reconstruct the spatial extent of Saharan-dust versus river-sediment input to the continental margin from West Africa over the last 60 ka. This allows us to map the position of the sediment composition corresponding to the Sahara-Sahel boundary. Our records indicate that the Sahara-Sahel boundary reached its most southerly position (13° N) during Heinrich stadials and hence suggest that these were the periods when the sand dunes formed at 14° N on the continent. Heinrich stadials are associated with cold North Atlantic sea surface temperatures which appear to have triggered abrupt increases of aridity and wind strength in the Sahel. Our study illustrates the influence of the Atlantic meridional overturning circulation on the position of the Sahara-Sahel boundary and on global atmospheric dust loading.

  14. The impact of Sahara desertification on Arctic cooling during the Holocene

    NASA Astrophysics Data System (ADS)

    Davies, F. J.; Renssen, H.; Blaschek, M.; Muschitiello, F.

    2015-03-01

    Since the start of the Holocene, temperatures in the Arctic have steadily declined. This has been accredited to the orbitally forced decrease in summer insolation reconstructed over the same period. However, here we present climate modelling results from an Earth model of intermediate complexity (EMIC) that indicate that 17-40% of the cooling in the Arctic, over the period 9-0 ka, was a direct result of the desertification that occurred in the Sahara after the termination of the African Humid Period. We have performed a suite of sensitivity experiments to analyse the impact of different combinations of forcings, including various vegetation covers in the Sahara. Our simulations suggest that over the course of the Holocene, a strong increase in surface albedo in the Sahara as a result of desertification led to a regional increase in surface pressure, a weakening of the trade winds, the westerlies and the polar easterlies, which in turn reduced the meridional heat transported by the atmosphere to the Arctic. We conclude that during interglacials, the climate of the Northern Hemisphere is sensitive to changes in Sahara vegetation type.

  15. 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

  16. 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

  17. Trans-Tethyan correlation of the Lower-Middle Cenomanian boundary interval; southern England (Southerham, near Lewes, Sussex) and Douar el Khiana, northeastern Algeria

    NASA Astrophysics Data System (ADS)

    Kennedy, William J.; Gale, Andrew S.

    2017-03-01

    A 480 m section of marls with widely separated levels of nodular limestone in the Fahdene Formation north of Bou Khadra in Tebessa Province, northeastern Algeria, spans the Lower/Middle Cenomanian boundary. A total of 30 ammonite species are present, of which two: Forbesiceras reversum and Calycoceras (Newboldiceras) algeriense are new. The fauna allows recognition of the Northwest European upper Lower Cenomanian Mantelliceras dixoni Zone, the succeeding lower Middle Cenomanian Cunningtoniceras inerme Zone, the Acanthoceras rhotomagense Zone and its subzones of Turrilites costatus and Turrilites acutus. The sequence of index species occurs in the same order in both north-eastern Tunisia and the Southerham Grey Pit in Sussex (and indeed elsewhere in Northwest Europe), indicating these to be robust assemblage zones and subzones that can be recognised on both the north and south sides of the Tethys. Other occurrences of taxa that are common in both sections and regions are markedly different, and include the co-occurrence of Cunningtoniceras inerme (Pervinquière, 1907) with Acanthoceras rhotomagense (Brongniart, 1822) in the costatus Subzone in north-eastern Algeria and central Tunisia, the extension of Acompsoceras renevieri (Sharpe, 1857) into the lower Middle Cenomanian in north-eastern Tunisia, whilst the acme of Turrilites scheuchzerianus Bosc, 1801, is in the dixoni Zone in Northwest Europe, and in the inerme Zone in northeasten Algeria and adjacent parts of Central Tunisia. These differences are not a result of collection failure or non-preservation, but must rather reflect environmental controls on occurrence and abundance.

  18. Algeria 1992: results from the PAPCHILD Survey.

    PubMed

    1994-01-01

    The summary statistics from the 1992 Algeria Maternal and Child Health Survey are presented in a series of tables on fertility and preferences, contraception, infant mortality, and nutrition. The sample includes 6449 households and 5019 ever married women aged 15-49 years with 4331 children aged under 5 years. Anthropometric measurements are taken on all children aged under 5 years in the sample. Population numbered 21.8 million in 1985, of which 47.5% was urban. The crude birth rate was 38.0 per 1000, and the crude death rate was 9.4 per 1000 live births. Population growth was 2.87%. 55.8% of ever married women in the sample had no schooling (70.7% in rural and 41.0 in urban areas). Fertility between 1989 and 1992 was 4.2 children. Fertility was highest among those women with no education (5.3 compared to 3.7 among women with a primary education). Fertility was highest among women aged 30-34 years at 220 births per 1000 women followed by women aged 25-29 years at 214 births per 1000 women in the 4 years immediately preceding the survey. The teenage pregnancy rate was 21 per 1000. The mean ideal number of children was 3.5 for women aged 15-19 years and 3.8 for women aged 20-24 years; the mean ideal increased with increasing age and with increasing parity. 87.5% of women with 1 child desired another child and only 5.3% did not; 4.3% were infertile. 77.1% of women with over 6 children did not want another child. Among all women 50.1% did not want another child, and 37.8% wanted another child. 4.85 were infertile, and 5.8% did not respond. Contraceptive prevalence was 50.7%: 42.9% with modern methods and 7.8% with traditional methods. Use was highest at 62.4% among women with a junior high school education. Use was high among women aged 35-39 years (56.4%) and with 4 children (62.6%). 10.8% of never users planned to use in the next 12 months; 10.8% of never users planned to use within the next 2 years. 28.9% did not intend to use contraception. 22.7% were nonusers

  19. 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.

  20. 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

  1. [Fifteen years' experience in scorpion envenomation control in Algeria].

    PubMed

    Benguedda, A C; Laraba-Djébari, F; Ouahdi, M; Hellal, H; Griene, L; Guerenik, M; Laid, Y

    2002-08-01

    In Algeria, scorpion envenomation is real public health problem. Since the creation of the National Committee of Control of Scorpion envenomations (CNLES), several steps have been taken to deal with this problem. After a brief historical introduction, we present the main elements of the action carried out both in terms of treatment and of prevention of scorpion proliferation. The epidemiological situation is presented by stressing the difficulties involved in collecting reliable data. We also address the question of citizen and stakeholder awareness since public participation is crucial in all prevention programmes. Training for healthcare providers is also one of the principal axes of the Committee's programme which includes national, regional, and even local seminars. We describe the improvement of production and research on venoms carried out by the Institute Pasteur of Algeria. We conclude by discussing the action plan for 2001 and prospects for an enhanced strategy in the fight against the scorpion envenomation.

  2. 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.

  3. Carbon dioxide emissions, output, and energy consumption categories in Algeria.

    PubMed

    Amri, Fethi

    2017-06-01

    This study examines the relation between CO2 emissions, income, non-renewable, and renewable energy consumption in Algeria during the period extending from 1980 to 2011. Our work gives particular attention to the validity of environmental Kuznets curve (EKC) hypothesis. The autoregressive distributed lag (ARDL) with break point method outcome demonstrates the positive effect of non-renewable type of energy on CO2 emissions consumption. On the contrary, the results reveal an insignificant effect of renewable energy on environment improvement. Moreover, the results accept the existence of EKC hypothesis but the highest gross domestic product value in logarithm scale of our data is inferior to the estimated turning point. Consequently, policy-makers in Algeria should expand the ratio of renewable energy and should decrease the quota of non-renewable energy consumption.

  4. Islamic Movements in Algeria and the Strategy of Violence

    DTIC Science & Technology

    2011-03-23

    Islamic Movements in Algeria and the Strategy of Violence FORMAT : Strategy Research Project DATE: 23 March 2011 WORD COUNT: 7,820 PAGES: 32...James D Le Sueur after the party‟s victory in the first round of parliamentary elections, stated: Democracy is one of the numerous nefarious...democratic model , dealing with man‟s spiritual element besides his human and social aspects. For Ben Nabi the development of democracy in Islam needs not

  5. Epidemiology of visceral leishmaniasis in Algeria: an update.

    PubMed

    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.

  6. 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

  7. AIDS in Algeria: the disease and the shame.

    PubMed

    Hadefri, R

    1995-01-01

    The latest figures published by the Algerian authorities report 187 people with AIDS and 451 people infected with HIV in the country. Medical specialists, however, argue the presence of 1499 AIDS cases and 26,057 people known to be HIV-seropositive. Although accurate and comprehensive data on the extent of HIV infection and the prevalence of full-blown AIDS is hard to come by, it is clear that HIV has taken a firm hold among the population of Algeria and continues to spread. Extremely conservative sexual taboos in Algeria make it impossible to discuss AIDS whether among friends or in public. These taboos combined with the lack of information and political will among top government functionaries have made it very difficult to mount an effective campaign against the epidemic. Tens of thousands of young Algerians travel abroad annually and do not take preventive measures against HIV when having sexual intercourse. Moreover, the use of improperly sterilized medical instruments, contaminated blood in transfusions, and clandestine prostitution also contribute to the dissemination of HIV in Algeria. Doctors on some television programs report on AIDS, but they do not talk freely and frankly. Instead, they speak in generalities or describe the epidemic in technical scientific language. This failure to communicate does much to explain the lack of success of the public education campaigns launched by government and other national organizations in recent years.

  8. Gastrointestinal lymphoma in Western Algeria: pattern of distribution and histological subtypes (retrospective study)

    PubMed Central

    Harir, Noria; Tou, Abdenacer; Medjamia, Miloud; Guenaoui, Khaira

    2016-01-01

    Background Primary gastrointestinal (GI) lymphomas (GIL) are uncommon diseases that can involve the whole GI tract. Considerable variation exists in the literature with respect to incidence of the various histological subtypes and sites of involvement. This study was undertaken to establish the anatomic distribution, histological subtypes and sites of GI lymphomas of patients from Western Algeria. Methods The case records of 58 consecutive patients with GIL diagnosed at the Pathologies Departments of Algerian west region (the Military Hospital of Oran city and the Central University Hospital of Sidi Bel Abbes city) from January 2006 to December 2013 were retrospectively evaluated for epidemiology and histopathology report. All lymphomas were reclassified according to the WHO 2008 classification. Results A total of 58 patients (39 male, 19 female) with mean age of 61 years and a range of 20–89 years were included in this study. Stomach was the most common site involved (70.7%). The commonest histological subtype was mucosa-associated lymphoid tissue (MALT) B cell lymphoma (46.6%), followed by diffuse large B-cell lymphomas (DLBCL) (43.1%).The frequency of Helicobacter pylori (HP) positivity differ between gastric and intestinal location P=0.003 and correlates with the histological type P=0.01. Conclusions This retrospective study of patients with GI lymphoma from Western Algeria illustrates the pattern of distribution of various common and rare histological subtypes. More studies are necessary to find a potential cause, risk factor or genetic mutation that can explain these specific characteristics of GIL. PMID:28078126

  9. 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

  10. Archaeoseismology in Algeria: observed damages related to probable past earthquakes on archaeological remains on Roman sites (Tel Atlas of Algeria)

    NASA Astrophysics Data System (ADS)

    Roumane, Kahina; Ayadi, Abdelhakim

    2017-04-01

    The seismological catalogue for Algeria exhibits significant lack for the period before 1365. Some attempts led to retrieve ancient earthquakes evidenced by historical documents and achieves. Archaeoseismology allows a study of earthquakes that have affected archaeological sites, based on the analysis of damage observed on remains. We have focused on the Antiquity period that include Roman, Vandal and Byzantine period from B.C 146 to A.D. 533. This will contribute significantly to the understanding of seismic hazard of the Tell Atlas region known as an earthquake prone area. The Tell Atlas (Algeria) experienced during its history many disastrous earthquakes their impacts are graved on landscape and archaeological monuments. On Roman sites such, Lambaesis (Lambèse), Thamugadi (Timgad) Thibilis (Salaoua Announa) or Thevest (Tebessa), damage were observed on monuments and remains related to seismic events following strong shacking or other ground deformation (subsidence, landslide). Examples of observed damage and disorders on several Roman sites are presented as a contribution to Archaeoseismology in Algeria based on effects of earthquakes on ancient structures and monuments. Keywords : Archaeoseismology. Lambaesis. Drop columns. Aspecelium. Ancient earthquakes

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

    PubMed

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

    2013-02-01

    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.

  12. 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

  13. 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.

  14. 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

  15. Were rivers flowing across the Sahara during the last interglacial? Implications for human migration through Africa.

    PubMed

    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.

  16. Revision of the genus Achmonia of Africa south of the Sahara (Coleoptera: Staphylinidae: Staphylininae).

    PubMed

    Janák, Jiří; Bordoni, Arnaldo

    2014-10-09

    A redescription of the genus Achmonia Bordoni, 2004 is presented. Based on a revision of types and of additional material, seven species are recognized in Africa south of the Sahara and placed into two species groups. All species are described or redescribed and illustrated, four of them for the first time: Achmonia carinata sp. nov., A. kapangana sp. nov., A. knirschi sp. nov., and A. simulator sp. nov. A lectotype is designated for Xantholinus amabilis Boheman, 1848, Eulissus flavomarginatus Bernhauer, 1929 and E. congoensis Bernhauer, 1932. These species are transferred to Achmonia. A lectotype is designated for Eulissus semiflavus Bernhauer, 1913, and E. gerardi Bernhauer, 1929 and the following synonymy is proposed: Achmonia amabilis (Boheman, 1848) = Eulissus semiflavus Bernhauer, 1913, syn. nov. = Eulissus gerardi Bernhauer, 1929, syn. nov. The distribution of the genus in Africa south of Sahara is mapped and a key to species is presented.

  17. Seismotectonics and seismic quietness of the Oranie region (Western Algeria): The Mascara earthquake of August 18th 1994, Mw = 5.7, Ms = 6.0

    NASA Astrophysics Data System (ADS)

    Ayadi, A.; Ousadou-Ayadi, F.; Bourouis, S.; Benhallou, H.

    The plate dynamics in the central western Mediterranean region is characterised by a collision between the Eurasian and African plates. In response to this dynamics, many systems of faults and folds having a NE-SW and E-W trending have been generated along the Tellian Atlas of Algeria. The Oranie region (north western Algeria) has experienced some significant earthquakes in the last centuries, the most important one is that of Oran city on February 9th 1790, Io = XI which destroyed the town completely and caused the loss of many lives. Since 1790 no other event was so disastrous except that of August 18th 1994, Mw = 5.7, which struck Mascara province (Algeria) at 01 h 13 mn GMT. Since the beginning of this century the region has been dominated by a seismic quietness. Thus, no event with magnitude larger than 5.5 have occurred in this area. In relation with this recent event, a seismotectonic framework summarising the tectonic, seismicity and focal solution results is presented. The Maximum Observed Intensities Map (MOI) made for Algeria (Bezzeghoud et al., 1996) is also used to show that the Mascara region is located in an VIII-X intensity zone, which explain partially the casualties caused by the 18/08/1994 (Mw = 5.7) earthquake. This earthquake is not anomalous compared to historical records but is unusual compared to recorded seismicity of this century. The seismotectonic map made in this study and also the review of the focal solutions given by the EMSC, Harvard, and other authors shows that our event is probably associated with a source belonging to a system of faults located in the vicinity of the village of Hacine where the maximum damage was observed.

  18. 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.

  19. On the stability of the atmosphere-vegetation system in the Sahara/Sahel region

    NASA Astrophysics Data System (ADS)

    Brovkin, Victor; Claussen, Martin; Petoukhov, Vladimir; Ganopolski, Andrey

    1998-12-01

    A conceptual model has been developed for the analysis of atmosphere-vegetation interaction in subtropical deserts. The model can exhibit multiple stable states in the system: a "desert" equilibrium with low precipitation and absent vegetation and a "green" equilibrium with moderate precipitation and permanent vegetation cover. The conceptual model is applied to interpret the results of two climate-vegetation models: a comprehensive coupled atmosphere-biome model and a simple box model. In both applications, two stable states exist for the western Sahara/Sahel region for the present-day climate, and the only green equilibrium is found for the mid-Holocene climate. The latter agrees well with paleoreconstructions of Sahara/Sahel climate and vegetation. It is shown that for present-day climate the green equilibrium is less probable than the desert equilibrium, and this explains the existence of the Sahara desert as it is today. The difference in albedo between the desert and vegetation cover appears to be the main parameter that controls an existence of multiple stable states. The Charney's mechanism of self-stabilization of subtropical deserts is generalized by accounting for atmospheric hydrology, the heat and moisture exchange at the side boundaries, and taking into account the dynamic properties of the surface. The generalized mechanism explains the self-stabilization of both desert and vegetation in the western Sahara/Sahel region. The role of surface roughness in climate-vegetation interaction is shown to be of secondary importance in comparison with albedo. Furthermore, for the high albedo, precipitation increases with increasing roughness while, for the low albedo, the opposite is found.

  20. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Emanuel, Kerry A.; Chiacchio, Marc; Diro, Gulilat T.; Zhang, Qiong; Sushama, Laxmi; Stager, J. Curt; Donnelly, Jeffrey P.

    2017-06-01

    Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate.

  1. 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.

  2. Characterizing land surface phenology and responses to rainfall in the Sahara desert

    NASA Astrophysics Data System (ADS)

    Yan, Dong; Zhang, Xiaoyang; Yu, Yunyue; Guo, Wei; Hanan, Niall P.

    2016-08-01

    Land surface phenology (LSP) in the Sahara desert is poorly understood due to the difficulty in detecting subtle variations in vegetation greenness. This study examined the spatial and temporal patterns of LSP and its responses to rainfall seasonality in the Sahara desert. We first generated daily two-band enhanced vegetation index (EVI2) from half-hourly observations acquired by the Spinning Enhanced Visible and Infrared Imager on board the Meteosat Second Generation series of geostationary satellites from 2006 to 2012. The EVI2 time series was used to retrieve LSP based on the Hybrid Piecewise Logistic Model. We further investigated the associations of spatial and temporal patterns in LSP with those in rainfall seasonality derived from the daily rainfall time series of the Tropical Rainfall Measurement Mission. Results show that the spatial shifts in the start of the vegetation growing season generally follow the rainy season onset that is controlled by the summer rainfall regime in the southern Sahara desert. In contrast, the end of the growing season significantly lags the end of the rainy season without any significant dependence. Vegetation growing season can unfold during the dry seasons after onset is triggered during rainy seasons. Vegetation growing season can be as long as 300 days or more in some areas and years. However, the EVI2 amplitude and accumulation across the Sahara region was very low indicating sparse vegetation as expected in desert regions. EVI2 amplitude and accumulated EVI2 strongly depended on rainfall received during the growing season and the preceding dormancy period.

  3. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period.

    PubMed

    Pausata, Francesco S R; Emanuel, Kerry A; Chiacchio, Marc; Diro, Gulilat T; Zhang, Qiong; Sushama, Laxmi; Stager, J Curt; Donnelly, Jeffrey P

    2017-06-13

    Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate.

  4. Spatial and temporal variability of water quality of an urbanized river in Algeria: the case of Soummam Wadi.

    PubMed

    Maane-Messai, S; Laignel, B; Motelay-Massei, A; Madani, K; Chibane, M

    2010-08-01

    Spatial and temporal variations of water quality were investigated at four sites of an urbanized river in Algeria during a period of low water level in the years 2002, 2003, and 2004. Physical-chemical parameters (temperature, pH, conductivity, dissolved oxygen, suspended matter, chemical oxygen demand [COD], and 5-day biochemical oxygen demand [BOD5]) were measured. The Soummam River showed a strong pollutant load, which was organic in origin and expressed by mean concentrations in suspended matter, COD and BOD5 exceeding 150, 100, and 50 mg/L, respectively. The spatial variation highlighted two areas--(1) the first one gathers the upstream and central sites of the river, and (2) the second one is found downstream. In the downstream area, the pollutant load is almost twice as high as in the first area and, the percent saturation of dissolved oxygen is relatively weak (< 55%). This load is the result of the significant volume of urban and industrial emissions in the river, the high temperature during low-water-level periods, and flood events, which occurred just before the period of low water level. The Soummam River was classified according to the criteria of appreciation of surface water and was found to be extremely polluted. This work is one of the first studies on the quality of rivers in Algeria. This research will be useful as a first step for future works in North Africa and will add to knowledge on the water quality in the Mediterranean Basin.

  5. How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors.

    PubMed

    Strandberg, Roine; Klaassen, Raymond H G; Hake, Mikael; Alerstam, Thomas

    2010-06-23

    We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey Pandion haliaetus, honey buzzard Pernis apivorus, marsh harrier Circus aeruginosus and Eurasian hobby Falco subbuteo) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles.

  6. How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors

    PubMed Central

    Strandberg, Roine; Klaassen, Raymond H. G.; Hake, Mikael; Alerstam, Thomas

    2010-01-01

    We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey Pandion haliaetus, honey buzzard Pernis apivorus, marsh harrier Circus aeruginosus and Eurasian hobby Falco subbuteo) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles. PMID:19955169

  7. Aquatic community response in a groundwater-fed desert lake to Holocene desiccation of the Sahara

    NASA Astrophysics Data System (ADS)

    Eggermont, Hilde; Verschuren, Dirk; Fagot, Maureen; Rumes, Bob; Van Bocxlaer, Bert; Kröpelin, Stefan

    2008-12-01

    The finely laminated sediment record of a permanent, hypersaline, desert oasis lake in the Ounianga region of northeastern Chad presents a unique opportunity to document the hydrological evolution of this groundwater-fed aquatic ecosystem during mid- and late-Holocene desiccation of the Sahara. In this study we reconstruct long-term changes in zoobenthos and zooplankton communities of Lake Yoa as their early-Holocene freshwater habitat changed into the hypersaline conditions prevailing today. Chironomid production peaked during the fresh-to-saline transition period, then stabilized at about half that of the earlier freshwater ecosystem. Quantitative salinity inferences based on fossil chironomid assemblages indicate that the fresh-to-saline transition occurred fairly abruptly between ˜4100 and 3400 cal yr BP, but that the ecosystem was buffered against shorter-term climate fluctuations due to continuous inflow of fossil groundwater. The mixture of tropical-African and southern Palaearctic chironomid faunas in the Lake Yoa fossil record required us to address several methodological issues concerning chironomid-based salinity reconstruction, and the applicability of a calibration dataset based on tropical East and West African lakes to this Sahara desert locality. The most coherent reconstruction was obtained with an inference model that applies a weighted best-modern-analogue (WMAT) transfer function to the African calibration dataset expanded with six Sahara lakes.

  8. 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.

  9. Time of foaling in Arabian mares raised in Tiaret, Algeria

    PubMed Central

    Meliani, Samia; Benallou, Bouabdellah; Halbouche, Miloud; Haddouche, Zohra

    2013-01-01

    Objective To enhance effectiveness of reproduction management in Arabian mares, factors influencing the time of foaling were investigated in this study. Methods Data were collected at the National Haras of Tiaret in Algeria from 2003 to 2010. The foaling time of 255 Arabian pure bred mares, aged from 3 to 20 years were used for this study. Results A total of 78.07% of foaling happens between 7 pm and 6 am. Conclusions The influence of the month of foaling and the sex of the foal, on the time of foaling was statically significant. PMID:23835758

  10. [Pediatric cancerology in Algeria. Current status and perspectives].

    PubMed

    Aguercif, M; Meziane, F

    1988-01-01

    Pediatric oncohematology represents 40% of our daily activity. Its management is analyzed and conditions of its development discussed. In underdeveloped countries, financial, human and management health resources are severely limited. Far less than 8.5% of national product (estimated necessary for a health service to meet population requirements) are spent in Algeria. Then rationing health services is implicit and eventually left to physicians. Limited access to hospitals is more drastic to children than to adults. Paediatricians have therefore to manage their activity to get best value for money spent on health care, training and research.

  11. Bioactive phenylpropanoids from Daucus crinitus Desf. from Algeria.

    PubMed

    Lanfranchi, Don-Antoine; Laouer, Hocine; El Kolli, Meriem; Prado, Soizic; Maulay-Bailly, Christine; Baldovini, Nicolas

    2010-02-24

    The volatile constituents of Daucus crinitus Desf. from Algeria were analyzed by GC and GC-MS, The main constituent was isochavicol isobutyrate (39.0%), an uncommon phenylpropanoid. By synthesis of a series of homologous esters, it was also possible to determine the presence of small amounts of isochavicol propionate, which has never been described previously as a natural product. The antibacterial and antifungal activities of the whole essential oil, of these two esters, and of isochavicol itself were investigated against a wide range of bacteria and fungi. Additionally, their antimalarial and antiradical properties were also evaluated, showing an interesting antiplasmodial activity of isochavicol.

  12. Hercynian Granite and Related Mineralisation in Beni Snouss, Western Algeria

    NASA Astrophysics Data System (ADS)

    Nacera, Hadj Mohamed; Abdelhak, Boutaleb

    2016-10-01

    The purpose of this research is to describe the mineralisation related to the Hercynian granite located in western Algeria by combining geologic, tectonic, mineralogical and fluid inclusion studies. Quartz veins bearing sulphides occur in close spatial association with granitoids, which, representing hydrothermal activities associated with them. Visible but rare gold occurs in a very small quantity connected with arsenopyrite. Barite veins and stock works are developed in the granites where are observed at Mallal and Bouabdous. The vein varies in thickness from a few centimetres up to 2 meters, and their length varies from 10 up to up 100 m. Most of veins are N50 - N75 and 60 to 90 dip.

  13. 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

  14. 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

  15. 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).

  16. [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.

  17. 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.

  18. Estimating daily global solar radiation by day of the year in Algeria

    NASA Astrophysics Data System (ADS)

    Aoun, Nouar; Bouchouicha, Kada

    2017-05-01

    This study presents six empirical models based on the day-of-the-year number for estimating global solar radiation on a horizontal surface. For this case study, 21 years of experimental data sets for 21 cities over the whole Algerian territory are utilized to develop these models for each city and for all of Algeria. In this study, the territory of Algeria was divided into four different climatic zones, i.e., Arid, Semi-arid, Highlands and Mediterranean. The accuracy of the all-Algeria model was tested for each city and for each climate zone. To evaluate the accuracy of the models, the RMSE, rRMSE, MABE, MAPE, and R, which are the most commonly applied statistical parameters, were utilized. The results show that the six developed models provide excellent predictions for global solar radiation for each city and for all-Algeria. Furthermore, the model showing the greatest accuracy is the sine and cosine wave trigonometric model.

  19. 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

  20. Antibacterial and antioxidant activities of three endemic plants from Algerian Sahara.

    PubMed

    Bouchouka, Elmouloud; Djilani, Abdelouaheb; Bekkouche, Abdesselem

    2012-01-01

    Saharan plants are known by their high content of antioxidant products like phenolic compounds due to the extreme climatic conditions. They constitute the basis of treatments used by local population for various diseases. The purposes of this study were to measure the total phenolic compounds and total fl avonoid compounds, to determine antioxidant capacity, and to evaluate the antibacterial activity of three wild Saharan medicinal plants. Hexane and ethyl acetate fractions of ethanol:water extract and the residu of the extracted aqueous layer of Ferula vesceritensis fruits, Genista saharae aerial parts and Zilla macropterae fruits were assayed to determine their antibacterial activity using the disc diffusion method against: Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Pseudomonas aeruginosa (ATCC 27853). In addition, the total phenolic compounds and total flavonoids and antioxydant activity using DPPH test of ethyl acetate fractions (EAF) of plant parts studied were investigated. Gallic acid, quercetin and vitamin C were used for these parameters. Among the extracts tested, ethyl acetate fractions of all plants and hexane fraction of F. vesceritensis showed activity against S. aureus. Good activity was shown by EAF of G. saharae. According to the results, it is observed that Z. macropterae fruits possess a good antioxidant activity. The results indicate that the ethyl acetate fraction of G. sahara Aerial parts possesses a good antibacterial activity against S. aureus, which justifies its use in traditional medicine for treating respiratory diseases. Furthermore, evaluation of in vitro antioxidant capacity of Ethyl acetate fractions of these plants, particular Z. macroptera fruits, has also provided interesting results. Zilla macroptera fruits may therefore be a good source of antioxidants.

  1. Mineral dust aerosols over the Sahara: Meteorological controls on emission and transport and implications for modeling

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter; Todd, Martin C.

    2012-02-01

    Atmospheric mineral dust has recently become an important research field in Earth system science because of its impacts on radiation, clouds, atmospheric dynamics and chemistry, air quality, and biogeochemical cycles. Studying and modeling dust emission and transport over the world's largest source region, the Sahara, is particularly challenging because of the complex meteorology and a very sparse observational network. Recent advances in satellite retrievals together with ground- and aircraft-based field campaigns have fostered our understanding of the spatiotemporal variability of the dust aerosol and its atmospheric drivers. We now have a more complete picture of the key processes in the atmosphere associated with dust emission. These cover a range of scales from (1) synoptic scale cyclones in the northern sector of the Sahara, harmattan surges and African easterly waves, through (2) low-level jets and cold pools of mesoscale convective systems (particularly over the Sahel), to (3) microscale dust devils and dusty plumes, each with its own pronounced diurnal and seasonal characteristics. This paper summarizes recent progress on monitoring and analyzing the dust distribution over the Sahara and discusses implications for numerical modeling. Among the key challenges for the future are a better quantification of the relative importance of single processes and a more realistic representation of the effects of the smaller-scale meteorological features in dust models. In particular, moist convection has been recognized as a major limitation to our understanding because of the inability of satellites to observe dust under clouds and the difficulties of numerical models to capture convective organization.

  2. 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%.

  3. Inhibition of stromelysin-1 by caffeic acid derivatives from a propolis sample from Algeria.

    PubMed

    Segueni, Narimane; Magid, Abdulmagid Alabdul; Decarme, Martine; Rhouati, Salah; Lahouel, Mesbah; Antonicelli, Frank; Lavaud, Catherine; Hornebeck, William

    2011-07-01

    Stromelysin-1 (matrix metalloproteinase-3: MMP-3) occupies a central position in collagenolytic and elastolytic cascades, leading to cutaneous intrinsic and extrinsic aging. We screened extracts of a propolis sample from Algeria with the aim to isolate compounds able to selectively inhibit this enzyme. A butanolic extract (B (3)) of the investigated propolis sample was found to potently inhibit MMP-3 activity (IC (50) = 0.15 ± 0.03 µg/mL), with no or only weak activity on other MMPs. This fraction also inhibited plasmin amidolytic activity (IC (50) = 0.05 µg/mL) and impeded plasmin-mediated proMMP-3 activation. B (3) was fractionated by HPLC, and one compound, characterized by NMR and mass spectroscopy and not previously identified in propolis, i.e., (+)-chicoric acid, displayed potent IN VITRO MMP-3 inhibitory activity (IC (50) = 6.3 × 10 (-7) M). In addition, both caffeic acid and (+)-chicoric acid methyl ester present in fraction B (3) significantly inhibited UVA-mediated MMP-3 upregulation by fibroblasts.

  4. 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. © 2014 The Royal Entomological Society.

  5. Consanguinity and epilepsy in Oran, Algeria: A case-control study.

    PubMed

    Chentouf, Amina; Talhi, Randa; Dahdouh, Aicha; Benbihi, Latifa; Benilha, Soumia; Oubaiche, Mohand Laid; Chaouch, Malika

    2015-03-01

    The goal of this case-control study was to identify the significance of consanguinity and other risk factors for epilepsy in Oran, Algeria. Unrelated epileptic patients upwards of 16 years, who attended the Neurology Department between October 2013 and March 2014 were included in the study. Controls, matched for age and sex, were selected among non-epileptic patients attending the same department during the same period. The risk factors evaluated were: consanguinity, family history of epilepsy, perinatal complications, infection of the central nervous system, mental retardation, neurological impairment, history of febrile seizures, severe head trauma, cerebrovascular diseases, and addiction. 101 cases and 202 controls participated in the study. Multivariate logistic regression identified five factors significantly associated with epilepsy: first-degree of consanguinity (odds ratio (OR)=2.15), history of epilepsy in first-degree relatives (OR=4.03), antecedent of febrile seizures (OR=5.38), severe head injury (OR=2.94) and mental retardation (OR=9.32). Consanguinity, family history of epilepsy, history of febrile seizures, severe head trauma and mental retardation are risk factors for epilepsy. The implementation of a strategy for prevention and awareness of the impact of consanguineous marriages as well as genetic counseling for couples with a family history of epilepsy are needed. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. 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

  7. 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.

  8. Factors Affecting the Role and Employment of Peacekeeping Forces in Africa South of the Sahara.

    DTIC Science & Technology

    1982-12-01

    Libyan troops E occupied the Aouzou Strip, a 60- mile wide area in Chad that parallels the 600- mile border between the countries and is said to...FORCES IN AFRICA SOUTH OF THE SAHARA CONTRACT NO. iMDA908-82-C-Ol74 Principal Researcher: Morris Davis Faculty Participants: Roger E . Kanec George T...Yu Steven Thomas Seitz SSte ’.,en ?. Cohen U Other ?articipants: William C. Loeffel "avid T. Best DTIC £Donald R. Zoufal E E T John B. HowellS 22

  9. Climate-Controlled Holocene Occupation in the Sahara: Motor of Africa's Evolution

    NASA Astrophysics Data System (ADS)

    Kuper, Rudolph; Kröpelin, Stefan

    2006-08-01

    Radiocarbon data from 150 archaeological excavations in the now hyper-arid Eastern Sahara of Egypt, Sudan, Libya, and Chad reveal close links between climatic variations and prehistoric occupation during the past 12,000 years. Synoptic multiple-indicator views for major time slices demonstrate the transition from initial settlement after the sudden onset of humid conditions at 8500 B.C.E. to the exodus resulting from gradual desiccation since 5300 B.C.E. Southward shifting of the desert margin helped trigger the emergence of pharaonic civilization along the Nile, influenced the spread of pastoralism throughout the continent, and affects sub-Saharan Africa to the present day.

  10. 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.

  11. Environmental Assessment. Proposed Sahara Mustard Control on the Barry M. Goldwater Range - East

    DTIC Science & Technology

    2012-02-01

    dateable) artifacts. Radiocarbon dates , obtained from thermal features indicates that BMGR- 00-D-01 dates to AD 1400-1600 and BMGR-00-D-02 dates to AD...failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 19 JUL 2012 2...REPORT TYPE 3. DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Proposed Sahara Mustard Control on the Barry M. Goldwater Range - Easy

  12. 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

  13. Climate-controlled Holocene occupation in the Sahara: motor of Africa's evolution.

    PubMed

    Kuper, Rudolph; Kröpelin, Stefan

    2006-08-11

    Radiocarbon data from 150 archaeological excavations in the now hyper-arid Eastern Sahara of Egypt, Sudan, Libya, and Chad reveal close links between climatic variations and prehistoric occupation during the past 12,000 years. Synoptic multiple-indicator views for major time slices demonstrate the transition from initial settlement after the sudden onset of humid conditions at 8500 B.C.E. to the exodus resulting from gradual desiccation since 5300 B.C.E. Southward shifting of the desert margin helped trigger the emergence of pharaonic civilization along the Nile, influenced the spread of pastoralism throughout the continent, and affects sub-Saharan Africa to the present day.

  14. Does wintering north or south of the Sahara correlate with timing and breeding performance in black-tailed godwits?

    PubMed

    Kentie, Rosemarie; Marquez-Ferrando, Rocío; Figuerola, Jordi; Gangoso, Laura; Hooijmeijer, Jos C E W; Loonstra, A H Jelle; Robin, Frédéric; Sarasa, Mathieu; Senner, Nathan; Valkema, Haije; Verhoeven, Mo A; Piersma, Theunis

    2017-04-01

    Migrating long distances requires time and energy, and may interact with an individual's performance during breeding. These seasonal interactions in migratory animals are best described in populations with disjunct nonbreeding distributions. The black-tailed godwit (Limosa limosa limosa), which breeds in agricultural grasslands in Western Europe, has such a disjunct nonbreeding distribution: The majority spend the nonbreeding season in West Africa, while a growing number winters north of the Sahara on the Iberian Peninsula. To test whether crossing the Sahara has an effect on breeding season phenology and reproductive parameters, we examined differences in the timing of arrival, breeding habitat quality, lay date, egg volume, and daily nest survival among godwits (154 females and 157 males), individually marked in a breeding area in the Netherlands for which wintering destination was known on the basis of resightings. We also examined whether individual repeatability in arrival date differed between birds wintering north or south of the Sahara. Contrary to expectation, godwits wintering south of the Sahara arrived two days earlier and initiated their clutch six days earlier than godwits wintering north of the Sahara. Arrival date was equally repeatable for both groups, and egg volume larger in birds wintering north of the Sahara. Despite these differences, we found no association between wintering location and the quality of breeding habitat or nest survival. This suggests that the crossing of an important ecological barrier and doubling of the migration distance, twice a year, do not have clear negative reproductive consequences for some long-distance migrants.

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

    PubMed

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

    2016-08-31

    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).

  16. The first two cadaveric renal transplantations in Blida, Algeria.

    PubMed

    Si-ahmed, E M

    2011-11-01

    Currently, living related donor renal transplantation is the most common source for transplantation in Algeria. To develop cadaveric organ donation, the Blida Transplantation Team (BTT) started a local education program and campaign. On March 31, 2010, we procured and transplanted 2 kidneys from a 17-year-old brain-dead donor. The BTT is conscious that the local initiative must be followed nationally, with the help of the health authorities. There is an urgent need to promote brain-dead donors and cadaveric organ retriveal throughout the country. It will also be necessary to create national waiting lists for candidates not only for renal, but also for other organ transplantations. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. [Tinea capitis in the University Hospital of Constantine (Algeria)].

    PubMed

    Benmezdad, A; Moulahem, T; Benyezzar, M; Djaballah, M; Beldjoudi, W; Fendri, A H

    2012-12-01

    Although benign, tinea capitis are a public health problem and a frequent complaint in children. In Algeria, these disorders have long been known; their high frequency was related to unfavorable social conditions of people both in cities than in rural areas. Our aim is the study of tinea capitis diagnosed in the laboratory of Parasitology and Mycology of the University Hospital of Constantine through a retrospective review of 15 consecutive years from 1997 to 2011. Currently the clinical and biological differ from those described by ancient authors; dermatophytic flora has evolved significantly and favus, once quite common in our country, is hardly ever found. In addition, we are witnessing a resurgence of zoophilic tinea particularly those caused by Microsporum canis. Copyright © 2012. Published by Elsevier SAS.

  18. [Seroprevalence of toxoplasmosis in pregnant women in Annaba, Algeria].

    PubMed

    Messerer, L; Bouzbid, S; Gourbdji, E; Mansouri, R; Bachi, F

    2014-04-01

    The aim of the study was to estimate the seroprevalence and risk factors of toxoplasmosis in pregnant women in the department of Annaba, Algeria. We performed a cross-sectional study with analytical purposes. The study was collaboration between the laboratory of Parasitology-Mycology, Faculty of Medicine of Annaba and Parasite Biology Department at the Pasteur Institute of Algeria. A total of 1028 pregnant women who underwent prenatal diagnosis/visit were included over a period of 4 years from January 2006 to December 2009. Immunoglobulin G and M were assayed, using the microparticle enzyme method. The avidity test was used to determine the date of contamination according to age of pregnancy. Search for the parasite was made by inoculation of the placenta and cord blood in white mice. The study compared mother-to-child serological profiles using Western Blot (WB) IgG and IgM. Direct (not well-cooked meat) and indirect (presence of cat, gardening) indicators were recorded to search for parasite exposure. Seroprevalence was 47.8 % (95 % CI: 44.8 to 51.0) and the rate of active toxoplasmosis was 1.1 % (95 % CI 0.6 to 1.8). According to their immune status, this was the first serology for 41 % (CI95 %: 38.0-44.0) of women; 12 % (CI95 %: 10.5-14.6) of primiparous women had only one serology test during their entire pregnancy. Major risk factors were consumption of poorly-cooked meat and exposure to cats. Toxoplasmosis during pregnancy is a serious issue and an effective prevention program is needed. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  19. 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%).

  20. Modeling the Effects of Sahara Dust on the Climate and Water Cycle of the Tropical Atlantic/Caribbean Region

    NASA Astrophysics Data System (ADS)

    Lau, W. K.; Kim, K.

    2006-12-01

    We have investigated the direct effects of air-borne dust particles generated by dust storm over the Sahara desert on the water cycle of the tropical Atlantic and Caribbean region using the NASA finite-volume general circulation model (fvGCM). Global aerosol forcings are computed from radiative transfer functions derived from global distributions of five species of aerosols, i.e., dust, black carbon, organic carbon, sulphate and sea salt from the Goddard Chemistry Aerosol Radiation Transport (GOCART) model. Comparing fvGCM experiments without aerosol forcing, and with different combinations of aerosol forcing, we evaluate the impacts of aerosol direct heating on the onset, maintenance and evolution of the South American summer monsoon. We find that during the boreal summer, Saharan dust contribute to substantial heating of the atmosphere over the central and eastern equatorial Atlantic/Africa region through the "elevated heat pump" (EHP) mechanism, which works as follows. Absorption of solar radiation by the upper portion of the thick dust layer causes heating of the middle atmosphere, while the blocking of solar radiation by dust reduces surface solar radiation and leads to cooling over the desert land surface. When the dust layer is sufficiently thick, heating by the elevated portion of dust layer produces a pressure gradient in the mid-troposphere between the dust layer and the surrounding clean air. The pressure gradient draws in low level anomalous westerlies which brings in warm, moist air from the central and western Atlantic. The warm, moist air flows eastward, and rises above the cold surface air as they approach the West Africa continent, and converges in the middle troposphere to produce anomalous rain over the eastern Atlantic and West Africa coast. The latent heat of condensation from the increased rain causes more warm air to rise over the dust layer. Eventually, through the aforementioned aerosol heating and water cycle feedback, an anomalous Walker

  1. 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.

  2. 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.

  3. Uneven distribution of Halobacillus trueperi species in arid natural saline systems of Southern Tunisian Sahara.

    PubMed

    Guesmi, Amel; Ettoumi, Besma; El Hidri, Darine; Essanaa, Jihene; Cherif, Hanene; Mapelli, Francesca; Marasco, Ramona; Rolli, Eleonora; Boudabous, Abdellatif; Cherif, Ameur

    2013-11-01

    The genetic diversity of a collection of 336 spore-forming isolates recovered from five salt-saturated brines and soils (Chott and Sebkhas) mainly located in the hyper-arid regions of the southern Tunisian Sahara has been assessed. Requirements and abilities for growth at a wide range of salinities\\ showed that 44.3 % of the isolates were extremely halotolerant, 23 % were moderate halotolerant, and 32.7 % were strict halophiles, indicating that they are adapted to thrive in these saline ecosystems. A wide genetic diversity was documented based on 16S-23S rRNA internal transcribed spacer fingerprinting profiles (ITS) and 16S rRNA gene sequences that clustered the strains into seven genera: Bacillus, Gracilibacillus, Halobacillus, Oceanobacillus, Paenibacillus, Pontibacillus, and Virgibacillus. Halobacillus trueperi was the most encountered species in all the sites and presented a large intraspecific diversity with a multiplicity of ITS types. The most frequent ITS type included 42 isolates that were chosen for assessing of the intraspecific diversity by BOX-PCR fingerprinting. A high intraspecific microdiversity was documented by 14 BOX-PCR genotypes whose distribution correlated with the strain geographic origin. Interestingly, H. trueperi isolates presented an uneven geographic distribution among sites with the highest frequency of isolation from the coastal sites, suggesting a marine rather than terrestrial origin of the strains. The high frequency and diversity of H. trueperi suggest that it is a major ecosystem-adapted microbial component of the Tunisian Sahara harsh saline systems of marine origin.

  4. Endovascular Treatment of a Severe Stroke Occurring in a Commercial Airplane Over the Sahara.

    PubMed

    Foerch, Christian; Mayer, Christoph A; Berkefeld, Joachim; You, Se-Jong

    2016-09-01

    The occurrence of an acute stroke syndrome during a long-distance flight demands critical decisions from the crew and attendant physicians. One in particular is whether the flight should be continued or be detoured to a nearby airport. We describe a 42-yr-old woman who suffered from a severe stroke in a commercial airplane over the Sahara. The captain, together with a physician aboard and the next of kin, decided not to detour to north African or south European airports, but to continue flying to Frankfurt, Germany (final destination; remaining flight time 4 h), where an efficient transfer infrastructure and an advanced medical standard were presumed. At the hospital, the patient was successfully treated by means of catheter-based mechanical thrombus extraction. The patient was free of neurological deficits at discharge. The geographically unbalanced availability of complex but highly effective therapies such as mechanical recanalization in acute stroke challenges decision making in aviation medicine. In selected cases it might be beneficial to continue flying to cities with advanced medical standards instead of deviating to nearby airports. Foerch C, Mayer CA, Berkefeld J, You S-J. Endovascular treatment of a severe stroke occurring in a commercial airplane over the Sahara. Aerosp Med Hum Perform. 2016; 87(9):825-829.

  5. 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.

  6. 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).

  7. Declines in a ground-dwelling arthropod community during an invasion by Sahara mustard (Brassica tournefortii) in aeolian sand habitats

    Treesearch

    Heather L. Hulton VanTassel; Anne M. Hansen; Cameron W. Barrows; Quresh Latif; Margaret W. Simon; Kurt E. Anderson

    2014-01-01

    Sahara Mustard (Brassica tournefortii; hereafter mustard), an exotic plant species, has invaded habitats throughout the arid southwestern United States. Mustard has reached high densities across aeolian sand habitats of southwestern deserts, including five distinct sand habitats in the eastern Coachella Valley, California. We examined trends in ground-dwelling...

  8. Libraries in National Literacy Education Programmes in Africa South of the Sahara: The State-of-the-Art.

    ERIC Educational Resources Information Center

    Newa, John M.

    1990-01-01

    Examines the involvement of public and village libraries in literacy and postliteracy programs in Africa south of the Sahara during the last two decades. Issues discussed include the extent of illiteracy in Black Africa, populations served by village libraries, African rural strategies of development, and the implications for library services. (44…

  9. Long-distance autumn migration across the Sahara by painted lady butterflies: exploiting resource pulses in the tropical savannah.

    PubMed

    Stefanescu, Constantí; Soto, David X; Talavera, Gerard; Vila, Roger; Hobson, Keith A

    2016-10-01

    The painted lady, Vanessa cardui, is a migratory butterfly that performs an annual multi-generational migration between Europe and North Africa. Its seasonal appearance south of the Sahara in autumn is well known and has led to the suggestion that it results from extremely long migratory flights by European butterflies to seasonally exploit the Sahel and the tropical savannah. However, this possibility has remained unproven. Here, we analyse the isotopic composition of butterflies from seven European and seven African countries to provide new support for this hypothesis. Each individual was assigned a geographical natal origin, based on its wing stable hydrogen isotope (δ(2)Hw) value and a predicted δ(2)Hw basemap for Europe and northern Africa. Natal assignments of autumn migrants collected south of the Sahara confirmed long-distance movements (of 4000 km or more) starting in Europe. Samples from Maghreb revealed a mixed origin of migrants, with most individuals with a European origin, but others having originated in the Sahel. Therefore, autumn movements are not only directed to northwestern Africa, but also include southward and northward flights across the Sahara. Through this remarkable behaviour, the productive but highly seasonal region south of the Sahara is incorporated into the migratory circuit of V. cardui.

  10. 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…

  11. Images of Africa: A Report on What American Secondary School Students Know and Believe about Africa South of the Sahara.

    ERIC Educational Resources Information Center

    Beyer, Barry K.; Hicks, E. Perry

    "Project Africa" surveyed selected seventh- and 12th-grade students in 24 states to determine (1) the specific nature of their images of Africa south of the Sahara, both before and after any formal study of this region, and (2) the types and accuracy of the students' knowledge about the region and its peoples. In one survey, students…

  12. Algeria: A Study of the Educational System of Algeria and a Guide to the Academic Placement of Students in Educational Institutions of the United States.

    ERIC Educational Resources Information Center

    Mize, David W.

    Written as a guide to be used in the admission and placement of Algerian students in U.S. institutions of higher education, this study discusses the educational system of Algeria. The organization of Algerian education is summarized. Information is provided on preschool and primary education, middle school education, secondary education,…

  13. Sahara Dust

    Atmospheric Science Data Center

    2013-04-15

    ... with application to enhancing our understanding of the effects of such particles on meteorology, ocean biological productivity, and human health. MISR images the Earth by measuring the spatial patterns of reflected sunlight. In the upper panel of the still image ...

  14. 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

  15. 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…

  16. [Evolution of tinea capitis observed in mycology laboratory of institute Pasteur of Algeria from1995 to 2015].

    PubMed

    Hamroune, Z; Mazouz, A; Benelmouffok, A-B; Kellou, D

    2016-12-01

    Tinea capitis are common in Algeria and are a frequent reason for consultation. This mycosis affects children and rarely adults. This is a retrospective study over a period of 20 years from 1995 to 2015 at the mycology laboratory of the Pasteur institute of Algeria.

  17. 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.

  18. 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

  19. Aetiological factors of Budd-Chiari syndrome in Algeria

    PubMed Central

    Afredj, Nawel; Guessab, Nawal; Nani, Abdelbasset; Faraoun, Sid Ahmed; Ouled Cheikh, Ibtissem; Kerbouche, Rafik; Hannoun, Djouhar; Amir, Zine Charef; Ait Kaci, Hayet; Bentabak, Kamel; Plessier, Aurélie; Valla, Dominique-Charles; Cazals-Hatem, Valerie; Denninger, Marie-Hélène; Boucekkine, Tadjeddine; Debzi, Nabil

    2015-01-01

    AIM: To study the clinical presentation of Budd-Chiari syndrome (BCS) and identify the aetiologies of this disease in Algeria. METHODS: Patients with BCS, hospitalised in our unit from January 2004 until June 2010 were included and the aetiological factors were assessed. Patients presenting a BCS in the setting of advanced-stage cirrhosis or a liver transplantation were excluded from the study. The diagnosis was established when an obstruction of hepatic venous outflow (thrombosis, stenosis or compression) was demonstrated. We diagnosed myeloproliferative disease (MPD) by bone marrow biopsy and V617F JAK2 mutation. Anti-phospholipid syndrome (APLS) was detected by the presence of anticardiolipin antibodies, anti-β2 glycoprotein antibodies and Lupus anticoagulant. We also detected paroxysmal nocturnal haemoglobinuria (PNH) by flow cytometry. Celiac disease and Behçet disease were systematically investigated in our patients. Hereditary anticoagulant protein deficiencies were also assessed. We tested our patients for the G20210A mutation at Beaujon Hospital. Imaging procedures were performed to determine a local cause of BCS, such as a hydatid cyst or a liver tumour. RESULTS: One hundred and fifteen patients were included. Mean follow up: 32.12 mo. Mean age: 34.41 years, M/F = 0.64. Chronic presentation was frequent: 63.5%. The revealing symptoms for the BCS were ascites (74.8%) and abdominal pain (42.6%). The most common site of thrombosis was the hepatic veins (72.2%). Involvement of the inferior vena cava alone was observed in 3 patients. According to the radiological investigations, BCS was primary in 94.7% of the cases (n = 109) and secondary in 5.2% (n = 6). An aetiology was identified in 77.4% of the patients (n = 89); it was multifactorial in 27% (n = 31). The predominant aetiology of BCS in our patients was a myeloproliferative disease, observed in 34.6% of cases. APLS was found in 21.7% and celiac disease in 11.4%. Other acquired conditions were: PNH (n

  20. Aetiological factors of Budd-Chiari syndrome in Algeria.

    PubMed

    Afredj, Nawel; Guessab, Nawal; Nani, Abdelbasset; Faraoun, Sid Ahmed; Ouled Cheikh, Ibtissem; Kerbouche, Rafik; Hannoun, Djouhar; Amir, Zine Charef; Ait Kaci, Hayet; Bentabak, Kamel; Plessier, Aurélie; Valla, Dominique-Charles; Cazals-Hatem, Valerie; Denninger, Marie-Hélène; Boucekkine, Tadjeddine; Debzi, Nabil

    2015-04-28

    To study the clinical presentation of Budd-Chiari syndrome (BCS) and identify the aetiologies of this disease in Algeria. Patients with BCS, hospitalised in our unit from January 2004 until June 2010 were included and the aetiological factors were assessed. Patients presenting a BCS in the setting of advanced-stage cirrhosis or a liver transplantation were excluded from the study. The diagnosis was established when an obstruction of hepatic venous outflow (thrombosis, stenosis or compression) was demonstrated. We diagnosed myeloproliferative disease (MPD) by bone marrow biopsy and V617F JAK2 mutation. Anti-phospholipid syndrome (APLS) was detected by the presence of anticardiolipin antibodies, anti-β2 glycoprotein antibodies and Lupus anticoagulant. We also detected paroxysmal nocturnal haemoglobinuria (PNH) by flow cytometry. Celiac disease and Behçet disease were systematically investigated in our patients. Hereditary anticoagulant protein deficiencies were also assessed. We tested our patients for the G20210A mutation at Beaujon Hospital. Imaging procedures were performed to determine a local cause of BCS, such as a hydatid cyst or a liver tumour. One hundred and fifteen patients were included. Mean follow up: 32.12 mo. Mean age: 34.41 years, M/F = 0.64. Chronic presentation was frequent: 63.5%. The revealing symptoms for the BCS were ascites (74.8%) and abdominal pain (42.6%). The most common site of thrombosis was the hepatic veins (72.2%). Involvement of the inferior vena cava alone was observed in 3 patients. According to the radiological investigations, BCS was primary in 94.7% of the cases (n = 109) and secondary in 5.2% (n = 6). An aetiology was identified in 77.4% of the patients (n = 89); it was multifactorial in 27% (n = 31). The predominant aetiology of BCS in our patients was a myeloproliferative disease, observed in 34.6% of cases. APLS was found in 21.7% and celiac disease in 11.4%. Other acquired conditions were: PNH (n = 4), systemic disease (n

  1. 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

  2. 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.

  3. Greening of the Sahara suppressed ENSO activity during the mid-Holocene

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Zhang, Qiong; Muschitiello, Francesco; Lu, Zhengyao; Chafik, Léon; Niedermeyer, Eva M.; Stager, J. Curt; Cobb, Kim M.; Liu, Zhengyu

    2017-07-01

    The evolution of the El Niño-Southern Oscillation (ENSO) during the Holocene remains uncertain. In particular, a host of new paleoclimate records suggest that ENSO internal variability or other external forcings may have dwarfed the fairly modest ENSO response to precessional insolation changes simulated in climate models. Here, using fully coupled ocean-atmosphere model simulations, we show that accounting for a vegetated and less dusty Sahara during the mid-Holocene relative to preindustrial climate can reduce ENSO variability by 25%, more than twice the decrease obtained using orbital forcing alone. We identify changes in tropical Atlantic mean state and variability caused by the momentous strengthening of the West Africa Monsoon (WAM) as critical factors in amplifying ENSO's response to insolation forcing through changes in the Walker circulation. Our results thus suggest that potential changes in the WAM due to anthropogenic warming may influence ENSO variability in the future as well.

  4. Greening of the Sahara suppressed ENSO activity during the mid-Holocene.

    PubMed

    Pausata, Francesco S R; Zhang, Qiong; Muschitiello, Francesco; Lu, Zhengyao; Chafik, Léon; Niedermeyer, Eva M; Stager, J Curt; Cobb, Kim M; Liu, Zhengyu

    2017-07-07

    The evolution of the El Niño-Southern Oscillation (ENSO) during the Holocene remains uncertain. In particular, a host of new paleoclimate records suggest that ENSO internal variability or other external forcings may have dwarfed the fairly modest ENSO response to precessional insolation changes simulated in climate models. Here, using fully coupled ocean-atmosphere model simulations, we show that accounting for a vegetated and less dusty Sahara during the mid-Holocene relative to preindustrial climate can reduce ENSO variability by 25%, more than twice the decrease obtained using orbital forcing alone. We identify changes in tropical Atlantic mean state and variability caused by the momentous strengthening of the West Africa Monsoon (WAM) as critical factors in amplifying ENSO's response to insolation forcing through changes in the Walker circulation. Our results thus suggest that potential changes in the WAM due to anthropogenic warming may influence ENSO variability in the future as well.

  5. Greening of the Sahara suppressed ENSO activity during the mid-Holocene

    PubMed Central

    Pausata, Francesco S. R.; Zhang, Qiong; Muschitiello, Francesco; Lu, Zhengyao; Chafik, Léon; Niedermeyer, Eva M.; Stager, J. Curt; Cobb, Kim M.; Liu, Zhengyu

    2017-01-01

    The evolution of the El Niño-Southern Oscillation (ENSO) during the Holocene remains uncertain. In particular, a host of new paleoclimate records suggest that ENSO internal variability or other external forcings may have dwarfed the fairly modest ENSO response to precessional insolation changes simulated in climate models. Here, using fully coupled ocean-atmosphere model simulations, we show that accounting for a vegetated and less dusty Sahara during the mid-Holocene relative to preindustrial climate can reduce ENSO variability by 25%, more than twice the decrease obtained using orbital forcing alone. We identify changes in tropical Atlantic mean state and variability caused by the momentous strengthening of the West Africa Monsoon (WAM) as critical factors in amplifying ENSO’s response to insolation forcing through changes in the Walker circulation. Our results thus suggest that potential changes in the WAM due to anthropogenic warming may influence ENSO variability in the future as well. PMID:28685758

  6. CELL5M: A geospatial database of agricultural indicators for Africa South of the Sahara

    PubMed Central

    Koo, Jawoo; Cox, Cindy M.; Bacou, Melanie; Azzarri, Carlo; Guo, Zhe; Wood-Sichra, Ulrike; Gong, Queenie; You, Liangzhi

    2016-01-01

    Recent progress in large-scale georeferenced data collection is widening opportunities for combining multi-disciplinary datasets from biophysical to socioeconomic domains, advancing our analytical and modeling capacity. Granular spatial datasets provide critical information necessary for decision makers to identify target areas, assess baseline conditions, prioritize investment options, set goals and targets and monitor impacts. However, key challenges in reconciling data across themes, scales and borders restrict our capacity to produce global and regional maps and time series. This paper provides overview, structure and coverage of CELL5M—an open-access database of geospatial indicators at 5 arc-minute grid resolution—and introduces a range of analytical applications and case-uses. CELL5M covers a wide set of agriculture-relevant domains for all countries in Africa South of the Sahara and supports our understanding of multi-dimensional spatial variability inherent in farming landscapes throughout the region. PMID:27853519

  7. 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.

  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. 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.

  10. 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.

  11. Tuberculosis in African refugees from the Eastern Sub-Sahara region.

    PubMed

    Nesher, Lior; Riesenberg, Klaris; Saidel-Odes, Lisa; Schlaeffer, Francisc; Smolyakov, Rorzalia

    2012-02-01

    The southern region of Israel has recently experienced an influx of African refugees from the Eastern Sub-Sahara desert area. These influxes have led to a significant increase in incidence of tuberculosis (TB) in that region. To review the data of African refugees diagnosed with TB between January 2008 and August 2010 at a tertiary care regional hospital. Twenty-five TB cases were diagnosed, 22 of which presented with pulmonary TB, 3 with extra-pulmonary TB (EPTB), and 7 with combined pulmonary and EPTB. Only one case had concomitant human immunodeficiency virus (HIV) infection and multidrug-resistant TB. Fifteen patients underwent extensive radiological investigations including chest, abdominal and spine computed tomography, 1 was reviewed by magnetic resonance imaging, and 9 underwent tissue biopsy. Eighteen patients were admitted as suspected TB and 4 as suspected pneumonia or pulmonary infiltrates that could have been defined as suspected TB. All 24 HIV-negative cases were sensitive to first-line drugs for TB, except for one case that was resistant to streptomycin and one to rifampicin. All patients responded well to first-line therapy. The average duration of hospitalization was 8.7 days (range 1-36). Following diagnosis 23 patients were transferred to a quarantine facility. We identified overutilization of medical resources and invasive procedures. For African refugees from the eastern Sub-Sahara who were HIV-negative and suspected of having TB, a sputum acid-fast smear and culture should have been the primary investigative tools before initiating treatment with four drugs (first-line), and further investigations should have been postponed and reserved for non-responders or for patients for whom the culture was negative. Physicians should maintain a high index of suspicion for EPTB in this population.

  12. The Effects of Surface Longwave Emissivity on Atmospheric Circulation and Convection at Sahara and Sahel Regions

    NASA Astrophysics Data System (ADS)

    Chen, Y. H.; Chen, X.; Huang, X.; Flanner, M.

    2016-12-01

    The longwave spectral emissivities of desert and vegetation are considerably different from blackbody emissivity. A dominant majority of current atmospheric GCMs still treat the surface as blackbody and ignore spectral variations of surface emissivity. Charney (1975) proposed a positive feedback in arid areas via interactions among solar radiation, surface albedo, and atmospheric motion. This leads us to postulate that similar feedback as in Charney (1975) could operate in the longwave and such longwave feedback might not be properly represented by current GCMs. We incorporate realistic surface spectral emissivity over the Sahara and Sahel regions, where the emissivity is as low as 0-6-0.7 over the IR window region, into the NCAR CESM v1.1.1, while keeping treatments for the rest of the globe unchanged. Both the standard and the modified CESM are then used to carry out a 10-year simulation with prescribed climatological SST. Compared to the standard CESM simulation, the mean surface radiative temperature in the modified CESM simulation increases by 1.6 K over the region. However, the net upward longwave flux at the top of the atmosphere is decreased by 2.33 Wm-2 because the low emissivity of desert leads to less longwave emission over the IR window region. Energy budget analysis shows that the atmospheric radiative cooling over the region is decreased by 1.33 Wm-2 in the modified CESM simulation. The changes in 500-hPa vertical velocities indicate in average enhanced descending motion over the region, result in suppression of convection, which in return enhances arid situation in the region. Our findings demonstrate that change in surface LW spectral emissivity can influence simulated climate in the Sahara and Sahel regions in a way, to some extent, similar to the mechanism proposed by Charney (1975).

  13. 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.

  14. Multisensor Satellite Analysis Of The November 2001 Algeria Flood

    NASA Astrophysics Data System (ADS)

    Pinori, S.; Adamo, C.; Dietrich, S.; Mugnai, A.; Tripoli, G. J.

    A major flood event occurred in northern Africa (Algeria) at the beginning of Novem- ber 2001. After several months of drought, torrential rain, over 100 mm of rain fell in 6 hour, and strong winds of up to 200 km/h caused huge mudslides and floods on Sat- urday 10 November in the capital Algiers and other villages, particularly in the coastal zones, causing more than 700 deaths according to official reports. The aim of the pa- per is to show the evolution of this event as seen from a satellite point of view, and to compare it with the simulation of the event performed with the non-hydrostatical UW model developed at the University of Wisconsin (Tripoli, 1992). In such perspective we will discuss results obtained combining measurements acquired by different sen- sors to better exploit the potential of each technique. The principal satellite observing the event was the Tropical Rainfall Measuring Mission (TRMM) carry on board the sensors: PR (Precipitation Radar), TMI (TRMM Microwave Imager) and LIS (Light- ning Image Sensor). Also, the measurements acquired by the SSM/I (Special Sensor Microwave Imager) on board the Defense Meteorological Satellite Program (DMSP) satellites are available. In this way the retrieved precipitation from radar and mi- crowave sensors can be related to the lightning occurrences and the microphysical cloud content.

  15. 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

  16. The Oran (Northwest Algeria) earthquake of 9 October 1790

    NASA Astrophysics Data System (ADS)

    Buforn, Elisa; Coca, Pilar; Udías, Agustín; Bezzeghoud, Mourad

    2017-04-01

    On the 9th of October of 1790, one of the largest earthquakes in the western Mediterranean took place that destroyed almost completely the city of Oran in the Northwest coast of Algeria, produced a small tsunami and was followed by an aftershock series. At that time, Oran was a Spanish presidium-city of small dimensions surrounded by relevant defensive walls and fortifications with five outside defense forts. Contemporary reports preserved at Spanish archives give very detailed information of the damage, including maps of the destruction suffered by the buildings and the number of casualties, approximately 2,000 of its 9,500 inhabitants. Due to its total destruction, Spain abandoned the site in 1792. Based on contemporary documents, seismic intensities according to EMS-98 scale have been estimated for the city and its fortifications, as well as in other Spanish and Algerian sites. Generation of the tsunami, which affected Spanish and Algerian coasts, locate the epicenter offshore very near to the city itself. The source may be assigned to the off-shore NE-SW trending faults.

  17. Familial epilepsy in Algeria: Clinical features and inheritance profiles.

    PubMed

    Chentouf, Amina; Dahdouh, Aïcha; Guipponi, Michel; Oubaiche, Mohand Laïd; Chaouch, Malika; Hamamy, Hanan; Antonarakis, Stylianos E

    2015-09-01

    To document the clinical characteristics and inheritance pattern of epilepsy in multigeneration Algerian families. Affected members from extended families with familial epilepsy were assessed at the University Hospital of Oran in Algeria. Available medical records, neurological examination, electroencephalography and imaging data were reviewed. The epilepsy type was classified according to the criteria of the International League Against Epilepsy and modes of inheritance were deduced from pedigree analysis. The study population included 40 probands; 23 male (57.5%) and 17 female subjects (42.5%). The mean age of seizure onset was 9.5 ± 6.1 years. According to seizure onset, 16 patients (40%) had focal seizures and 20 (50%) had generalized seizures. Seizure control was achieved for two patients (5%) for 10 years, while 28 (70%) were seizure-free for 3 months. Eleven patients (27.5%) had prior febrile seizures, 12 were diagnosed with psychiatric disorders and four families had syndromic epilepsy. The consanguinity rate among parents of affected was 50% with phenotypic concordance observed in 25 families (62.5%). Pedigree analysis suggested autosomal dominant (AD) inheritance with or without reduced penetrance in 18 families (45%), probable autosomal recessive (AR) inheritance in 14 families (35%), and an X-linked recessive inheritance in one family. This study reveals large Algerian families with multigenerational inheritance of epilepsy. Molecular testing such as exome sequencing would clarify the genetic basis of epilepsy in some of our families. Copyright © 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

  18. [An analysis of factors influencing maternal mortality in Southern Algeria].

    PubMed

    Coppieters, Yves; Bivort, Philippe; Madani, Kamel; Metboul, Mohamed

    2011-01-01

    Southern Algeria has the highest rate of maternal mortality in the country. An action-research study was conducted to identify the explanatory factors of this issue. Three methodological approaches were used: (i) an epidemiological data analysis of maternal mortality and an analysis of obstetric complications at the hospital of Tamanrasset; (ii) a socio-anthropological study conducted among women in Tamanrasset; and (iii) semi-structured interviews with health professionals aimed at understanding their beliefs and representations. RESULTS; The study identified three major factors influencing the decision to seek care: (i) the interpretation of illness by mothers; (ii) the origin of their decision to seek care based on their assessment of the range of available therapeutic options; and (iii) medical uncertainty, with mothers often forced to resort to a range of therapeutic options because of uncertainty and pressure from family and other local residents. A detailed analysis of the implementation of mobile healthcare services is required to provide local health services to the population.

  19. [Deficiency rickets: the current situation in France and Algeria].

    PubMed

    Garabedian, M; Ben-Mekhbi, H

    1989-01-01

    Persisting vitamin D deficiency rickets in France results from the climatic, environmental and geographic situation of this country. Although systematic administration of vitamin D supplements to infants greatly reduced the prevalence of rickets among infants, clinical and/or biological signs of vitamin D deficiency are still found in children and adolescents, mainly during the winter and in populations vulnerable for economic, cultural or religious reasons. Signs of vitamin D deficiency are also found, during the winter-spring seasons, in pregnant women and their newborns living in urban areas. Such vitamin D deficiencies could be overcome by vitamin D supplementation to susceptible populations. In Algeria, vitamin D deficiency rickets present a continuing public health problem. The persisting high incidence of rickets among children appears to result mainly from economic and cultural factors. Vitamin D supplementation and health education are mandatory to reduce the prevalence of vitamin D deficiency among pregnant women and the occurrence of vitamin D deficiency rickets in infants, whether breast-fed or not.

  20. [Antimicrobial activity of Actinomycetale isolated from the lagoon in Algeria].

    PubMed

    Alliouch-Kerboua, Chérifa; Gacemi Kirane, Djamila; La Scola, Bernard

    2015-01-01

    In the aim of the study of the taxonomy and the antimicrobial activity, a strain of actinomycete SM2/2GF which was isolated from sediment of the lagoon El-Mellah which is situated in the city of El-Kala in the Northeast of Algeria, was tested against diverse pathogenic microorganisms and against a Gram-negative bacterium Pseudomonas alcaliphila which was isolated from water of the lagoon El-Mellah. The phenotypic and the molecular characteristics show that the isolate SM2/2GF belongs to the kind Streptomyces. This strain showed an antimicrobial activity against a Gram-negative bacterium Pseudomonas alcaliphila and the positive-Gram bacteria as Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtilis, Enterococcus faecalis, as well as the yeast Candida albicans. It has no activity against Pseudomonas aeruginosa. The interesting antimicrobial activity of the strain SM2/2GF against the pathogenic microorganisms could encourage further researches on one or several bioactive molecules which it secretes.

  1. Mutagenic and genotoxic effects of Guelma's urban wastewater, Algeria.

    PubMed

    Tabet, Mouna; Abda, Ahlem; Benouareth, Djamel E; Liman, Recep; Konuk, Muhsin; Khallef, Messaouda; Taher, Ali

    2015-02-01

    Assessment of water pollution and its effect upon river biotic communities and human health is indispensable to develop control and management strategies. In this study, the mutagenicity and genotoxicity of urban wastewater of the city of Guelma in Algeria were examined between April 2012 and April 2013. For this, two biological tests, namely Amesand chromosomal aberrations (CA) test in Allium cepa root tips were employed on the samples collected from five different sampling stages (S1-S5). In Ames test, two strains of Salmonella typhimurium TA98 and TA100 with or without metabolic activation (S9-mix) were used. All water samples were found to be mutagenic to S. typhimurium TA98 with or without S9-mix. A significant decrease in mitotic index (MI) was observed with a decrease in the percentage of cells in the prophase and an increase in the telophase. Main aberrations observed were anaphase bridges, disturbed anaphase-telophase cells, vagrants and stickiness in anaphase-telophase cells. All treatments of wastewater in April 2012, at S5 in July 2012, at S1 and S5 in November 2012, at S5 in February 2013, and at S1 in April 2013 induced CA when compared to the negative control. Some physicochemical parameters and heavy metals (Cd, Pb, and Cu) were also recorded in the samples examined.

  2. 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.

  3. 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.

  4. 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)).

  5. 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

  6. An overview on the origin of post-collisional Miocene magmatism in the Kabylies (northern Algeria): Evidence for crustal stacking, delamination and slab detachment

    NASA Astrophysics Data System (ADS)

    Chazot, Gilles; Abbassene, Fatiha; Maury, René C.; Déverchère, Jacques; Bellon, Hervé; Ouabadi, Aziouz; Bosch, Delphine

    2017-01-01

    Miocene (17-11 Ma) magmatic activity in the Kabylies emplaced K-rich (and minor medium-K) calc-alkaline plutonic and volcanic rocks in five zones, delineating a ∼450 km long EW trending strip located along the northern coast of Algeria, between Annaba and Algiers. Their most likely source is the Kabylian subcontinental lithospheric mantle previously metasomatized during the Paleogene subduction of the Tethys oceanic lithosphere. Our preferred tectono-magmatic model involves a Tethyan slab detachment combined with African mantle delamination and crustal stacking, leading to the superimposition of the African continental crust over the Kabylian metasomatized lithospheric mantle. At ca. 17 Ma, the asthenospheric upwelling arising from lithospheric delamination and Tethyan slab tear triggered the thermal erosion of the latter mantle, inducing its partial melting. The corresponding mafic medium-K calc-alkaline magmas interacted with the African basement units during their ascent, generating intermediate to felsic K-rich calc-alkaline melts that display a characteristic trace element and isotopic crustal signature. Later on, slab tears propagated eastward and westward, promoting slab rollback perpendicular to plate convergence and inducing the emplacement of magmatic rocks of decreasing ages from central-eastern Algeria towards Tunisia and Morocco.

  7. [Independence of the Central Asian faunistic region (according to the distribution of lizards (Reptilia, Sauria))].

    PubMed

    Bobrov, V V

    2005-01-01

    Central Asian area above 2000 m was studied to test the independence of the Central Asian Mountain region in the herpetogeographical map of the Palearctic Region and the neighboring Sahara-Gobi Desert region. According to the range and origin similarity, all species inhabiting this area were assigned to several groups: mountain Central Asian species (the bulk of the range lies within the studied area), Western Asian upland species (the bulk of the range lies in the Near Eastern uplands), plain desert species (the bulk of the range is below 2000 m), Indo-Malayan species (the bulk of the range lies within the Indo-Malayan Kingdom), European species (the bulk of the range lies in the forest and steppe zones of Europe and West Siberia), and mountain desert species (equal parts of the range lie in the deserts and mountains of Central Asia). The distribution of species density was mapped by range superposition for each group. The dominance (over 50% of the total number of species) of mountain Central Asian or other species groups allowed us to assign the studied area to either the Central Asian mountain region or Sahara-Gobi desert region. The areas where neither of the specified groups exceeded the 50% threshold were recognized as transitional. Considering a large number of endemic species (28% of the total fauna), the Central Asian mountain area should be recognized as an independent region rather than a subregion of the Sahara-Gobi Desert region.

  8. [Epidemiology of cervical cancer in a region of western Algeria, 2006-2010].

    PubMed

    Boublenza, L; Hadef, K; Beldjillali, H; Chabni, N; Reguegba, D; Meguenni, K

    2013-05-01

    The authors present a retrospective analysis of data about cervical cancer from 2006 through 2010 in the province (wilaya) of Tlemcen (Algeria). During this five-year study period, 196 cases of cervical cancer were recorded, with a mean age at onset of 48.5 years. These cervical cancers accounted for 13% of all gynecologic cancers. It is the second leading cancer among women in this province, with an incidence of 13.3 per 100 000 women. The health authorities in Algeria must set up an organized screening policy and appropriate treatment to reduce the mortality rate from this cancer.

  9. 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

  10. 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

    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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. Dust transport and synoptic conditions over the Sahara-Arabia deserts during the MIS6/5 and 2/1 transitions from grain-size, chemical and isotopic properties of Red Sea cores

    NASA Astrophysics Data System (ADS)

    Palchan, D.; Stein, M.; Almogi-Labin, A.; Erel, Y.; Goldstein, S. L.

    2013-11-01

    The Red Sea, situated between the Sahara and Arabia deserts, is a natural trap for fine-grained particles transported by winds and floods from weathered materials in these deserts, derived from the Proterozoic crustal granitic and basaltic terrains and Phanerozoic carbonates. The accumulated fine particles provide valuable information on the climate conditions in the source regions, and modes of atmospheric circulation over the Red Sea region. Here, we report on the grain-size, mineralogy, chemical composition, and Nd and Sr isotope ratios of fine-grained insoluble residues (IR) from acid leaching, that were recovered from two deep-sea cores KL23 and KL11 drilled in the northern and central Red Sea, respectively. We focus on the MIS6/5 and MIS2/1 transitions. KL23 samples are closer to the “Sahara granitoids” field and display significant variations during the MIS6/5 transition, between εNd of -7 to -2 and 87Sr/86Sr of 0.7096 to 0.7114. Smaller variations occurred during the MIS2/1 transition, between εNd of -5 to -6 and 87Sr/86Sr of 0.7104 to 0.7118. The KL11 values are closer to the “Blue Nile” field, which comprises mixtures of granitoid and basalt derived particles. During the MIS6/5 transition their εNd varies from -4 to -1 and in 87Sr/86Sr from 0.7059 to 0.7091. During periods equivalent to sapropels S5 and S1, both cores appear to converge to similar isotope ratios of εNd∼-2 and 87Sr/86Sr ∼ 0.7095, indicating derivation from the granitoid terrains of the Arabian-Nubian Shield occurring adjacent to the Red Sea and possibly distributed by runoff. In terms of synoptic conditions, the data indicate that during glacials, dust was blown to the northern Red Sea from the northern Sahara desert in association with the Mediterranean winter cyclones, and to the central Red Sea from the Ethiopian plateau by southern winds that are associated with monsoonal circulation. During interglacials, especially sapropel intervals, monsoonal rains caused erosion

  16. The Reagan Doctrine, Morocco, and the Conflict in the Western Sahara: An Appraisal of United States Policy

    DTIC Science & Technology

    1988-06-01

    supporting self-determination, decolonialization and human rights may come into conflict with a foreign policy premised on ideology, geostrategic concerns, and...Premises in Postwar American r Foreign Policy," 4. Vj 127 Traditional American concerns of human-rights, support for decolonialization , and self...to affirm, as recently as October 13 1986, that the conflict in the Western Sahara is a question of decolonialization * and self-determination. The

  17. Lake Yoa (Northern Chad): A Seasonal Footprint of 10,500 Years of Climate Change in the Sahara

    NASA Astrophysics Data System (ADS)

    Kroepelin, S.; Cocquyt, C.; Darius, F.; Dinies, M.; Francus, P.; Just, J.; Karls, J.; Kuper, J.; Lézine, A. M.; Mallaye, B.; Melles, M.; Sylvestre, F.; Viehberg, F. A.; Wennrich, V.

    2016-12-01

    We present Africa's most complete Holocene climate record in a long awaited breakthrough that few would have expected in one of the driest and most remote parts of the Sahara, the planet's major hot desert. A 16 m thick continuous sequence of seasonally laminated (varved) deposits at the bottom of a now fully groundwater-supported oasis lake at Ounianga Kebir in northern Chad extends our earlier 6,000 year record published in 2008 back to the onset of postglacial humid conditions 10,500 years ago in unrivalled detail. Main results indicate a rather slow regreening in northern Africa after 100,000 years of apparently continuous late Pleistocene aridity; precisely define the severe environmental impact of global climate events such as the 8,200 BP North Atlantic cooling even in hypercontinental positions far away from the oceans; and corroborate the gradual termination of the last "Green Sahara" period over millennia. Lake Yoa's varve count-controlled age model also shows the high error potential of the existing 14C chronology from bulk carbonate-dated paleolacustrine archives elsewhere in the Sahara and provides a basis for its correction. The new terrestrial multiproxy data set discloses agreements and discrepancies to marine and ice core data, and numeric climate models. As a natural analogue, it helps to foresee how North Africa's climate and environments might evolve due to anthropogenic global warming.

  18. Ethnoveterinary of Sahrawi pastoralists of Western Sahara: camel diseases and remedies.

    PubMed

    Volpato, Gabriele; Lamin Saleh, Saleh Mohamed; Di Nardo, Antonello

    2015-06-20

    Pastoral populations around the world hold complex and detailed ethnoveterinary knowledge, essential for the survival of their herds and securing their livelihood. In recent decades, several studies have given attention to local veterinary remedies and practices and their validation, and to the local conceptualization of livestock diseases. Despite this, relatively little has been reported on indigenous knowledge of camel diseases (e.g., aetiological factors, epidemiological patterns, symptoms, prevention and treatments). This paper focuses on the traditional knowledge of camel diseases and their treatments among Sahrawi nomads, detailing how this knowledge is powerfully reflected on pastoral adaptation strategies to the ecological system of Western Sahara. Between 2005 and 2010, freelisting exercise on camel diseases with 46 Sahrawi nomads and refugees, semi-structured interviews with 36 knowledgeable informants about camel diseases and associated treatments, and a voucher specimen collection of the plants and products cited were conducted in the territories administered by the Saharawi Arab Democratic Republic, Western Sahara. Analytical methods included standard ethnobiological, ethnobotanical and cultural consensus analyses. In total, 42 camel diseases were freelisted by informants, with four (i.e., mange, dermatomycosis, respiratory infections, and mastitis) found to be culturally highly salient. These four represent the most common veterinary conditions experienced by Sahrawi pastoralists. In addition, 42 plant species belonging to 22 botanical families (Hammada scoparia, Acacia tortilis, Zygophyllum gaetulum, Nucularia perrinii, and Panicum turgidum among the species most used) were listed as used in the treatment of these diseases, as well as about 30 remedies of animal (e.g., from camels, donkeys, and/or spiny-tailed lizards) and mineral origin, and of cauterizations. This study provides an overall picture of the most important camel diseases and remedies

  19. Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Isolated in Algiers, Algeria

    PubMed Central

    Ramdani-Bouguessa, Nadjia; Rahal, Kheira

    2003-01-01

    There are few data on antibiotic resistance of Streptococcus pneumoniae in Algeria. Among 309 strains, 34.6% were penicillin G-nonsusceptible S. pneumoniae strains (25.2% were intermediate and 9.4% were resistant). Serotypes 1, 5, 14, and 6 were the most frequent in invasive child infections. A multicenter study to standardize the national guidelines is needed. PMID:12543703

  20. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 2, Numbers 1, 2, 3, 1968.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    Three volumes comprise a 375-item bibliography with abstracts of books and articles in English, French, Italian, and Arabic that provides information on various aspects of education in the Maghreb countries of Algeria, Libya, Morocco, and Tunisia. Each entry identifies the country with which it is concerned, and foreign language titles are…

  1. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 3, Number 1, 1969.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A 130-item bibliography with abstracts of books and articles in English and French provides information on various aspects of education (many of them language-related) in the Maghreb countries of Algeria, Libya, Morocco, and Tunisia. Each entry identifies the country with which it is concerned, and French titles are translated into English.…

  2. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 6, Number 1, 1972.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    Annotations of articles, written in English, provide the content for a bibliography of educational materials written in French useful to those with an interest in North Africa. Sections on Algeria, Libya, Morocco, and Tunisia are preceded by a section on the Maghreb which deals with the special problems of illiteracy, multilingualism, and rapid…

  3. Empirical relations to convert magnitudes of the earthquake catalogue for the north western of Algeria

    NASA Astrophysics Data System (ADS)

    Belayadi, Ilyes; Bezzeghoud, Mourad; Fontiela, João; Nadji, Amansour

    2017-04-01

    North Algeria is one of the most seismically active regions on the western Mediterranean basin and it is related with the boundaries of the Eurasian and Nubian plates. We compiled an earthquake catalogue for the north western of Algeria, within the area -2°W-1°E and 34°N-37°N for the time span 1790 - 2016. To compile the earthquake catalogue we merge all available catalogues either national and international. Then we remove all duplicates and fake earthquakes. The lower level of the catalogue entries is set at M = 2.5. Nevertheless, the magnitudes reported on the catalogue are ML, Ms, Mb, Mw and macroseismic intensity. Thus, we develop new empirical relations to calculate the Mw from the different magnitudes and intensity suitable to the seismic hazard and geodynamic context of North Algeria. Acknowledgements: Ilyes Belayadi is funded entirely by the University of Oran 2 Mohamed Ben Ahmed (Algeria). This work is co-financed by the European Union through the European Regional Development Fund under COMPETE 2020 (Operational Program for Competitiveness and Internationalization) through the ICT project (UID / GEO / 04683/2013) under the reference POCI-01-0145 -FEDER-007690.

  4. 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…

  5. 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…

  6. 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)

  7. 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…

  8. 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,…

  9. 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…

  10. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Vol. 4, No. 2.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A 100-item bibliography with abstracts of books, newspaper articles, and periodical articles in English and French published predominantly in 1970 offers information on various aspects of education in Algeria, Libya, Morocco, and Tunisia. Emphasis is placed on sections dealing with educational organization in primary, secondary, vocational, and…

  11. 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,…

  12. Issues in Strategic Planning for Vocational Education: Lessons from Algeria, Egypt, and Morocco.

    ERIC Educational Resources Information Center

    Salmi, Jamil

    1991-01-01

    Although Algeria, Egypt, and Morocco have followed substantially different development strategies, they exhibit similar signs of crisis in vocational education. An integrated approach to planning that acknowledges social, financial, technological, and economic constraints could help coordinate general and vocational education and specialized…

  13. 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.…

  14. 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.

  15. 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…

  16. Vocational Education in Algeria, Egypt, and Morocco: The Crisis and its Lessons.

    ERIC Educational Resources Information Center

    Salmi, Jamil

    1990-01-01

    Examines developments in vocational and technical education systems in Algeria, Egypt, and Morocco. Argues each system faces critical problems resulting from demographic pressures, educational demand, lack of funding, and job placement difficulties. Recommends programs should reflect industry's needs, urging integration between general and…

  17. 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.

  18. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 3, Number 4, 1969.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A 100-item bibliography with abstracts of books, newspaper articles, and periodical articles in English and French dating from 1953 offers information on various aspects of education in Algeria, Libya, Morocco, and Tunisia. Emphasis is placed on sections dealing with educational organization in primary, secondary, vocational and higher education;…

  19. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 4, Number 1, 1970.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine, Comp.; And Others

    A 100-item bibliography with abstracts of books, newspaper articles, and periodical articles in English and French published predominantly in 1969 offers information on various aspects of education in Algeria, Libya, Morocco, and Tunisia. Emphasis is placed on sections dealing with educational organization in primary, secondary, vocational, and…

  20. Selected Bibliography of Educational Materials: Algeria, Libya, Morocco, Tunisia. Volume 3, Numbers 2, 3, 1969.

    ERIC Educational Resources Information Center

    Azzouz, Azzedine; And Others

    A two volume, 200-item bibliography with English abstracts of books and articles in English and French dating from 1957 offers information on various aspects of education in Algeria, Libya, Morocco, and Tunisia. Emphasis is placed on sections dealing with educational organization in primary, secondary, vocational, and higher education; and…

  1. 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…

  2. 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)

  3. Vocational Education in Algeria, Egypt, and Morocco: The Crisis and its Lessons.

    ERIC Educational Resources Information Center

    Salmi, Jamil

    1990-01-01

    Examines developments in vocational and technical education systems in Algeria, Egypt, and Morocco. Argues each system faces critical problems resulting from demographic pressures, educational demand, lack of funding, and job placement difficulties. Recommends programs should reflect industry's needs, urging integration between general and…

  4. Issues in Strategic Planning for Vocational Education: Lessons from Algeria, Egypt, and Morocco.

    ERIC Educational Resources Information Center

    Salmi, Jamil

    1991-01-01

    Although Algeria, Egypt, and Morocco have followed substantially different development strategies, they exhibit similar signs of crisis in vocational education. An integrated approach to planning that acknowledges social, financial, technological, and economic constraints could help coordinate general and vocational education and specialized…

  5. 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,…

  6. 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…

  7. 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…

  8. Political economy of Maghribi oil: Change and development in Algeria and Libya

    SciTech Connect

    Vandewalle, D.J.

    1988-01-01

    In the wake of rapidly growing oil and natural gas revenues, Algeria and Libya during the 1970s adopted a state capitalist strategy in order to minimize the dislocations caused by continued reliance on the international economy and, in the long run, to move toward more self-reliant local economies. International political economy theories until now have paid relatively little attention to the impact of the state in the development process, assuming that state formation and bureaucratic development go hand in hand. But in Libya and Algeria they remained disjointed. This was further exacerbated by the rentier nature of their economies which allowed for the distribution of assets without real political participation. In Algeria a techno-bureaucratic elite, to which the state quickly lost control during the 1970s, was put in charge of development. By 1976 the inefficiencies of the public sector and the alignment of the techno-bureaucratic elite with an expanding private sector led Algeria back toward a more market-oriented development strategy. In Libya a much smaller population and larger revenues have allowed the Qadhdhafi government to prolong the state capitalists experiment without paying serious attention to either economic or political development.

  9. NWA 1152 and Sahara 00182: New primitive carbonaceous chondrites with affinities to the CR and CV groups

    NASA Astrophysics Data System (ADS)

    Smith, Caroline L.; Russell, Sara S.; Gounelle, Matthieu; Greenwood, Richard C.; Franchi, Ian A.

    2004-12-01

    We have investigated the mineralogy, petrography, bulk chemistry, and light element isotope composition of the ungrouped chondrites North West Africa (NWA) 1152 and Sahara 00182. NWA 1152 contains predominantly type 1 porphyritic olivine (PO) and porphyritic olivine-pyroxene (POP) chondrules. Chondrule silicates are magnesium-rich (Fo98.8 +/- 1.2, n = 36; Fs2.3 +/- 2.1 Wo1.2 +/- 0.3, n = 23). Matrix comprises ~40 vol% of the sample and is composed of a micron sized silicate groundmass with larger silicate, sulfide, magnetite, and Fe-Ni metal (Ni ~50 wt%) grains. Phyllosilicates were not observed in the matrix. Refractory inclusions are rare (0.3 vol%) and are spinel pyroxene aggregates or amoeboid olivine aggregates; melilite is absent from the refractory inclusions. Sahara 00182 contains predominantly type 1 PO chondrules, POP chondrules are less common. Most chondrules contain blebs of, and are often rimmed with, Fe-Ni metal and sulfide. Chondrule phenocrysts are magnesium-rich (Fo92.2 +/- 0.6, n = 129; Fs4.4 +/- 1.8 Wo1.3 +/- 1.1, n = 16). Matrix comprises ~30 vol% of the meteorite and is predominantly sub-micron silicates, with rare larger silicate gains. Matrix Fe-Ni metal (mean Ni = 5.8 wt%) and sulfide grains are up to mm scale. No phyllosilicates were observed in the matrix. Refractory inclusions are rare (1.1 vol%) and melilite is absent. The oxygen isotope composition of NWA 1152 falls within the range of the CV chondrites with ?17O = ?3.43? ?18O = 0.70? and is similar to Sahara 00182, ?17O = ?3.89?, ?18O = ?0.19? (Grossman and Zipfel 2001). Based on mineralogical and petrographic characteristics, we suggest NWA 1152 and Sahara 00182 show many similarities with the CR chondrites, however, oxygen isotopes suggest affinity with the CVs. Thus, neither sample can be assigned to any of the currently known carbonaceous chondrite groups based on traditionally recognized characteristics. Both samples demonstrate the complexity of inter- and intra

  10. Spatial distribution of dust's optical properties over the Sahara and Asia inferred from Moderate Resolution Imaging Spectroradiometer

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Haywood, J. M.; Johnson, B. T.; Murakami, H.; Nakajima, T.

    2012-12-01

    There is a great deal of uncertainty surrounding the role of mineral dust aerosols in the earth's climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction), are poorly understood because ground observations are limited to several locations and the satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength. We develop a method in this paper to estimate the spatial distributions of the aerosol single scattering albedo (ω0) and optical depth (τa), with daily 1 degree latitude and 1 degree longitude resolution, using data from Moderate Resolution Imaging Spectroradiometer (MODIS), as well as model simulations of radiative transfer. This approach is based on the "critical surface reflectance" method developed in the literature, which estimates ω0 from the top of the atmospheric radiance. We confirm that the uncertainties in our estimation of ω0 and τa are suitably minor and that the characteristic spatial distributions estimated over the Sahara and Asia are significant. The results for the Sahara indicate good correlation between ω0 and the surface reflectance and between ω0 and τa. Therefore, ω0 is determined mainly by the mineral composition of surface dust and/or the optical depth of airborne dust in the Sahara. On the other hand, the relationships between ω0, τa, and the surface reflectance are less clear in Asia than in the Sahara, and the values of ω0 are smaller than those in the Sahara. The regions with small ω0 values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are thought to be transported, as reported in previous studies. Because the coal-burning and carbonaceous aerosols are known to be more absorptive and have smaller ω0 values than dust aerosols, our results indicate that the dust aerosols in Asia are contaminated by

  11. 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.

  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

    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.

  14. Dental indicators of adaptation in the Sahara Desert during the Late Holocene.

    PubMed

    Nikita, E; Mattingly, D; Lahr, M M

    2014-10-01

    The present paper examines dental diseases and linear enamel hypoplasia among the Garamantes, a Late Holocene Saharan population, and aims to draw conclusions about nutrition and adaptation to a hyper-arid environment. Archaeological evidence suggests that the Garamantian diet included animal protein and local, Mediterranean and Near Eastern plants. Moreoever, although the Garamantes had developed urban centres, the size of these was not large enough to allow for particularly unhygienic conditions to appear. The above archaeological findings were partly corroborated by the current bioarchaeological study. At an intra-population level, the Garamantes showed limited sex differences in dental disease prevalence, while all dental conditions increased in frequency with age, as expected. At an inter-population level, the frequency of all dental conditions was comparable to that found among other North African groups, with the exception of ante-mortem tooth loss. The low frequency of most dental conditions is an indication that the Garamantian diet was overall balanced, while the high frequency of ante-mortem tooth loss may be related to factors such as oral hygiene, food preparation or eating mode, which cannot be controlled for osteologically. Finally, the low frequency of enamel hypoplasia suggests either that the Sahara did not inflict particular stresses on the population, or, more likely, that the Garamantes had developed effective mechanisms for coping with their natural environment.

  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.

  16. 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.

  17. 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.

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

    PubMed

    Gehring, W J; Wehner, R

    1995-03-28

    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.

  19. 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

  20. 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

  1. Gold mineralization in the West Hoggar shear zone, Algeria

    NASA Astrophysics Data System (ADS)

    Ferkous, K.; Leblanc, M.

    1995-06-01

    The Amesmessa gold prospect is located along a vertical N-S-trending crustal-scale ductile shear zone; stretching lineations are subhorizontal. This major shear zone is a Late Pan African dextral strike-slip fault of the Pharusian Belt of the Tuareg Shield (Algeria). The Amesmessa shear zone is asymmetric: strong thermal and deformational gradients are present along its western border where biotitic ultramylonites are in contact with a rigid Archean complex (In Ouzzal block), whereas there is a progressive gradation, through mylonite then protomylonite, to the Proterozoic gneiss of the Eastern block which displays co-axial Pan African structures. The Amesmessa shear zone is characterized by the presence of a felsic dike complex emplaced during shearing, and forming the most important parent material for ultramylonites. Basic magmas and carbonatites also intruded within the shear zone. The gold-rich quartz veins are located within the ultramylonitic western part of the shear zone. These N-S-trending laminated quartz veins formed during the late increments of shearing (plastic/brittle transition), by repeated syntectonic hydraulic fracturing along zones of rheological contrast parallel to foliation. The ore mineral association (pyrite, galena, native gold, sphalerite) crystallized in the deformed quartz matrix along late shear planes. Undeformed E-W trending banded quartz veins are present in the mylonitic eastern part of the shear zone; their gold content is low and no native gold has been observed. A strong hydrothermal alteration resulted in the development (along the walls of the N-S gold-bearing quartz veins) of a 5-m-wide carbonate-sericite-albite-pyrite secondary mineral association which implies an important CO2 supply and moderate temperature conditions. There is no alteration halo around the E-W quartz veins. Ultramylonites, hydrothermally altered rocks and quartz veins display similar REE patterns characterized by strong LREE enrichments. Shear

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Subsurface valleys and geoarcheology of the eastern sahara revealed by shuttle radar.

    PubMed

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

    1982-12-03

    The shuttle imaging radar (SIR-A) carried on the space shuttle Columbia in November 1981 penetrated the extremely dry Selima Sand Sheet, dunes, and drift sand of the eastern Sahara, revealing previously unknown buried valleys, geologic structures, and possible Stone Age occupation sites. Radar responses from bedrock and gravel surfaces beneath windblown sand several centimeters to possibly meters thick delineate sand- and alluvium-filled valleys, some nearly as wide as the Nile Valley and perhaps as old as middle Tertiary. The now-vanished major river systems that carved these large valleys probably accomplished most of the erosional stripping of this extraordinarily flat, hyperarid region. Underfit and incised dry wadis, many superimposed on the large valleys, represent erosion by intermittent running water, probably during Quaternary pluvials. Stone Age artifacts associated with soils in the alluvium suggest that areas near the wadis may have been sites of early human occupation. The presence of old drainage networks beneath the sand sheet provides a geologic explanation for the locations of many playas and present-day oases which have been centers of episodic human habitation. Radar penetration of dry sand and soils varies with the wavelength of the incident signals (24 centimeters for the SIR-A system), incidence angle, and the electrical properties of the materials, which are largely determined by moisture content. The calculated depth of radar penetration of dry sand and granules, based on laboratory measurements of the electrical properties of samples from the Selima Sand Sheet, is at least 5 meters. Recent (September 1982) field studies in Egypt verified SIR-A signal penetration depths of at least 1 meter in the Selima Sand Sheet and in drift sand and 2 or more meters in sand dunes.

  9. Actinopolyspora biskrensis sp. nov., a novel halophilic actinomycete isolated from Northern Sahara.

    PubMed

    Saker, Rafika; Bouras, Noureddine; Meklat, Atika; Zitouni, Abdelghani; Schumann, Peter; Spröer, Cathrin; Klenk, Hans-Peter; Sabaou, Nasserdine

    2015-03-01

    A novel halophilic, filamentous actinomycete, designated H254(T), was isolated from a Saharan soil sample collected from Biskra (Northern Sahara), and subjected to a polyphasic taxonomic characterization. The strain is Gram-positive, aerobic, and halophilic, and the optimum NaCl concentration for growth is 15-20 % (w/v). The cell-wall hydrolysate contained meso-diaminopimelic acid, and the diagnostic whole-cell sugars were arabinose and galactose. The diagnostic phospholipid detected was phosphatidylcholine, and MK-9(H4) was the predominant menaquinone. The major fatty acid profiles were anteiso-C17:0 (32.8 %), C15:0 (28 %), and iso-C17:0 (12.3 %). Comparative analysis of the 16S rRNA gene sequences revealed that the strain H254(T) formed a well-separated sub-branch within the radiation of the genus Actinopolyspora, and the microorganism was most closely related to Actinopolyspora saharensis DSM 45459(T) (99.2 %), Actinopolyspora halophila DSM 43834(T) (99.1 %), and Actinopolyspora algeriensis DSM 45476(T) (99.0 %). Nevertheless, the strain had relatively lower mean values for DNA-DNA relatedness with the above strains (57.2, 68.4, and 45.6 %, respectively). Based on phenotypic features and phylogenetic position, we propose that strain H254(T) represents a novel species of the genus Actinopolyspora, for which the name Actinopolyspora biskrensis sp. nov. is proposed. The type strain of A. biskrensis is strain H254(T) (=DSM 46684(T) =CECT 8576(T)).

  10. 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.

  11. Subsurface valleys and geoarcheology of the Eastern Sahara revealed by shuttle radar

    USGS Publications Warehouse

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

    1982-01-01

    The shuttle imaging radar (SIR-A) carried on the space shuttle Columbia in November 1981 penetrated the extremely dry Selima Sand Sheet, dunes, and drift sand of the eastern Sahara, revealing previously unknown buried valleys, geologic structures, and possible Stone Age occupation sites. Radar responses from bedrock and gravel surfaces beneath windblown sand several centimeters to possibly meters thick delineate sand- and alluvium-filled valleys, some nearly as wide as the Nile Valley and perhaps as old as middle Tertiary. The nov-vanished maijor river systems that carved these large valleys probably accomplished most of the erosional stripping of this extraordinarily flat, hyperarid region. Underfit and incised dry wadis, many superimposed on the large valleys, represent erosion by intermittent running water, probably during Quaternary pluvials. Stone Age artifacts associated with soils in the alluvium suggest that areas near the wadis may have been sites of early human occupation. The presence of old drainage networks beneath the sand sheet provides a geologic explanation for the locations of many playas and present-day oases which have been centers of episodic human habitation. Radar penetration of dry sand and soils varies with the wavelength of the incident signals (24 centimeters for the SIR-A system), incidence angle, and the electrical properties of the materials, which are largely determined by moisture content. The calculated depth of radar penetration of dry sand and granules, based on laboratory measurements of the electrical properties of samples from the Selima Sand Sheet, is at least 5 meters. Recent (September 1982) field studies in Egypt verified SIR-A signal penetration depths of at least 1 meter in the Selima Sand Sheet and in drift sand and 2 or more meters in sand dunes. Copyright ?? 1982 AAAS.

  12. Predicting physical activity energy expenditure using accelerometry in adults from sub-Sahara Africa.

    PubMed

    Assah, Felix K; Ekelund, Ulf; Brage, Soren; Corder, Kirsten; Wright, Antony; Mbanya, Jean C; Wareham, Nicholas J

    2009-08-01

    Lack of physical activity may be an important etiological factor in the current epidemiological transition characterized by increasing prevalence of obesity and chronic diseases in sub-Sahara Africa. However, there is a dearth of data on objectively measured physical activity energy expenditure (PAEE) in this region. We sought to develop regression equations using body composition and accelerometer counts to predict PAEE. We conducted a cross-sectional study of 33 adult volunteers from an urban (n = 16) and a rural (n = 17) residential site in Cameroon. Energy expenditure was measured by doubly labeled water (DLW) over a period of seven consecutive days. Simultaneously, a hip-mounted Actigraph accelerometer recorded body movement. PAEE prediction equations were derived using accelerometer counts, age, sex, and body composition variables, and cross-validated by the jack-knife method. The Bland and Altman limits of agreement (LOAs) approach was used to assess agreement. Our results show that PAEE (kJ/kg/day) was significantly and positively correlated with activity counts from the accelerometer (r = 0.37, P = 0.03). The derived equations explained 14-40% of the variance in PAEE. Age, sex, and accelerometer counts together explained 34% of the variance in PAEE, with accelerometer counts alone explaining 14%. The LOAs between DLW and the derived equations were wide, with predicted PAEE being up to 60 kJ/kg/day below or above the measured value. In summary, the derived equations performed better than existing published equations in predicting PAEE from accelerometer counts in this population. Accelerometry could be used to predict PAEE in this population and, therefore, has important applications for monitoring population levels of total physical activity patterns.

  13. Evidence of Rift Valley fever seroprevalence in the Sahrawi semi-nomadic pastoralist system, Western Sahara.

    PubMed

    Di Nardo, Antonello; Rossi, Davide; Saleh, Saleh M Lamin; Lejlifa, Saleh M; Hamdi, Sidumu J; Di Gennaro, Annapia; Savini, Giovanni; Thrusfield, Michael V

    2014-04-24

    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. 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). 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.

  14. Thermal response to running across the Sahara desert: data for three men.

    PubMed

    DeGroot, David W; Kenney, W Larry

    2008-09-01

    There are limited data concerning the physiological responses to long-duration exercise collected under field conditions, and less data under harsh environmental conditions. This paper describes select environmental conditions and physiological responses of three runners attempting to run across the entire Sahara desert over a 111-d period. The runners started in Saint-Louis, Senegal, and we collected data on 2 d at the start of the expedition. Core temperature was measured via telemetry pill (Tpill), heart rate via Polar monitor, and metabolic rate (M) was estimated from two equations. The Pandolf equation uses movement speed and grade while Berglund's equation predicts M from heart rate and dry-bulb temperature. Data are presented as mean +/- SD (range). The runners intermittently ran 8.0 km x h(-1) over 6 h during Night (warm-humid) conditions and 6.9 km x h(-1) over 7 h 40 min during Day (hot-dry) desert conditions. Mean Tpill was similar for both days (37.8 +/- 10.34 vs. 37.82 +/- 0.50 degrees C) while range was greater during the day (Day: 36.69-38.91 vs. Night: 37.11-38.48 degrees C). Heart rate was 128 +/- 16 (72-156) and 119 +/- 17 (75-147) bpm for Night and Day, respectively. Mmean was 299 +/- 66 (65-418) W x m(-2) and 364 +/- 117 (58-542) W x m(-2) during Night and 239 +/- 60 (67-356) and 244 +/- 139 (54-464) W x m(-2) during Day, estimated by Berglund and Pandolf, respectively. During Day, the athletes ran slower than during Night, though Tpill was similar, indicative of the greater environmental strain. Mean predicted M was similar between equations, though maximum and minimal values were more extreme and rate-of-change dynamics faster according to Pandolf's equation.

  15. 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

  16. High-Resolution Simulations of Convective Cold Pools over the Northwestern Sahara

    NASA Astrophysics Data System (ADS)

    Knippertz, P.; Trentmann, J.; Seifert, A.

    2009-09-01

    Cooling by evaporation of convective precipitation in the deep and dry subcloud layer over desert regions can generate intense downdrafts and long-lived and extensive atmospheric density currents. The strong gusts at their leading edges can cause so-called haboob dust storms. Despite their importance for the dust cycle, the ability of state-of-the-art numerical weather prediction models to realistically simulate the associated convective cold pools has been investigated very little to date. During the first field campaign of the Saharan Mineral Dust Experiment in southern Morocco in May/June 2006, several density currents were observed. They were triggered by deep moist convection over the Atlas Mountains during the afternoon and propagated into the foothills in the course of the evening. The passage of the leading edge is associated with a marked increase in dew point, wind speed and pressure, a change in wind direction, and a decrease in temperature and visibility. Here we present numerical simulations of three of these density currents using the nonhydrostatic Consortium for Small-Scale Modelling (COSMO) model with 2.8-km horizontal grid spacing, which allows an explicit treatment of deep convection. The model is capable of simulating the timely initiation of convective cells over the Atlas Mountains and the subsequent formation of long-lived, extensive cold pools with a realistic three-dimensional structure. Deviations from available surface and satellite observations are closely related to model deficiencies in simulating precipitating convection over the Algerian Sahara. Sensitivity studies with modified microphysics reveal a large influence of raindrop size distributions on evaporation and surface rainfall but a rather moderate influence on the cold pool evolution. Decreasing the length scale for turbulent vertical mixing in the boundary layer leads to more widespread but weaker precipitation, more evaporation, and a faster and more extended cold pool.

  17. 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

  18. 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)

  19. Spatial distribution of dust's optical properties over the Sahara and Asia inferred from Moderate Resolution Imaging Spectroradiometer

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Haywood, J. M.; Yokohata, T.; Murakami, H.; Nakajimae, T.

    2013-11-01

    There is great uncertainty regarding the role of mineral dust aerosols in Earth's climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction), are poorly constrained because ground observations are limited to a few locations and satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength, which makes robust retrievals difficult. Here, we develop a method to estimate the spatial distributions of the aerosol single scattering albedo (ω0) and optical depth (τa), with daily 1°×1° spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) as well as model simulations of radiative transfer. This approach is based on the "critical surface reflectance" method developed in the literature, which estimates ω0 from the top of the atmospheric radiance. We estimate the uncertainties in ω0 over the Sahara (Asia) to be approximately 0.020 and 0.010 (0.023 and 0.017) for bands 9 and 1, respectively, while the uncertainty in τa is approximately 0.235 and 0.228 (0.464 and 0.370) for bands 9 and 1, respectively. The 5-95% range of the spatial distribution of ω0 over the Sahara (Asia) is approximately 0.90-0.94 and 0.96-0.99 (0.87-0.94 and 0.89-0.97) for bands 9 and 1, respectively, and that of τa over the Sahara (Asia) is approximately 0.8-1.4 and 0.8-1.7 (0.7-2.0 and 0.7-1.9) for bands 9 and 1, respectively. The results for the Sahara indicate a good correlation between ω0 and the surface reflectance, and between ω0 and τa. However, the relationships between ω0, τa, and surface reflectance are less clear in Asia than in the Sahara, and the ω0 values are smaller than those in the Sahara. The regions with small ω0 values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are reported to be transported in previous studies

  20. Role of surface wind and vegetation cover in multi-decadal variations of dust emission in the Sahara and Sahel

    NASA Astrophysics Data System (ADS)

    Kim, Dongchul; Chin, Mian; Remer, Lorraine A.; Diehl, Thomas; Bian, Huisheng; Yu, Hongbin; Brown, Molly E.; Stockwell, William R.

    2017-01-01

    North Africa, the world's largest dust source, is non-uniform, consisting of a permanently arid region (Sahara), a semi-arid region (Sahel), and a relatively moist vegetated region (Savanna), each with very different rainfall patterns and surface conditions. This study aims to better understand the controlling factors that determine the variation of dust emission in North Africa over a 27-year period from 1982 to 2008, using observational data and model simulations. The results show that the model-derived Saharan dust emission is only correlated with the 10-m winds (W10m) obtained from reanalysis data, but the model-derived Sahel dust emission is correlated with both W10m and the Normalized Difference Vegetation Index (NDVI) that is obtained from satellite. While the Saharan dust accounts for 82% of the continental North Africa dust emission (1340-1570 Tg year-1) in the 27-year average, the Sahel accounts for 17% with a larger seasonal and inter-annual variation (230-380 Tg year-1), contributing about a quarter of the transatlantic dust transported to the northern part of South America. The decreasing dust emission trend over the 27-year period is highly correlated with W10m over the Sahara (R = 0.92). Over the Sahel, the dust emission is correlated with W10m (R = 0.69) but is also anti-correlated with the trend of NDVI (R = -0.65). W10m is decreasing over both the Sahara and the Sahel between 1982 and 2008, and the trends are correlated (R = 0.53), suggesting that Saharan/Sahelian surface winds are a coupled system, driving the inter-annual variation of dust emission.

  1. A new cichlid fish in the Sahara: The Ounianga Serir lakes (Chad), a biodiversity hotspot in the desert.

    PubMed

    Trape, Sébastien

    In the rare perennial bodies of water of the Sahara desert, only a few fish species have survived to increasing aridification since the end of the last humid period at the Holocene, approximately 5000 years BP. Here, I report the occurrence of an undescribed haplochomine cichlid fish in Lake Boukou, one of the seven Ounianga Serir lakes (Chad). These lakes are located in one of the most arid areas of the Sahara desert, but they persist by virtue of subsurface inflow of fresh groundwater from a large fossil aquifer. Astatotilapia tchadensis sp. nov. is characterized by a black bar between eye and corner of mouth, rounded orange spots on anal fin, scales ctenoid, lower limb of first gill arch with 7-8 gill rackers, dorsal fin with 13-14 spines and 9-11 soft rays, anal fin with 3 spines and 8-9 soft rays, 29 or 30 lateral line scales, and lower pharyngeal dentition with enlarged molariform teeth. The new species is easily distinguished from A. desfontainii and A. flaviijosephii, the northernmost haplochromine species currently isolated from its other group members, and appears close to an unnamed species of Lake Chad basin. Ounianga Serir lakes and especially Lake Boukou present a remarkable diversity of fish, the highest known in the Sahara desert with a total of at least six fish species belonging to six genera and three families. They also constitute an exceptional natural landscape inscribed on the UNESCO world heritage list in 2012 and a biodiversity hotspot for desert vertebrate species.

  2. Role of Surface Wind and Vegetation Cover in Multi-decadal Variations of Dust Emission in the Sahara and Sahel

    NASA Technical Reports Server (NTRS)

    Kim, Dong; Chin, Mian; Remer, Lorraine A.; Diehl, Thomas L.; Bian, Huisheng; Yu, Hongbin; Brown, Molly E.; Stockwell, William R.

    2016-01-01

    North Africa, the world's largest dust source, is non-uniform, consisting of a permanently arid region (Sahara), a semi-arid region (Sahel), and a relatively moist vegetated region (Savanna), each with very different rainfall patterns and surface conditions. This study aims to better understand the controlling factors that determine the variation of dust emission in North Africa over a 27-year period from 1982 to 2008, using observational data and model simulations. The results show that the model-derived Saharan dust emission is only correlated with the 10-m winds (W10m) obtained from reanalysis data, but the model-derived Sahel dust emission is correlated with both W10m and the Normalized Difference Vegetation Index (NDVI) that is obtained from satellite. While the Saharan dust accounts for 82 of the continental North Africa dust emission (1340-1570 Tg year(exp -1) in the 27-year average, the Sahel accounts for 17 with a larger seasonal and inter-annual variation (230-380 Tg year(exp -1), contributing about a quarter of the transatlantic dust transported to the northern part of South America. The decreasing dust emission trend over the 27-year period is highly correlated with W10m over the Sahara (R equals 0.92). Over the Sahel, the dust emission is correlated with W10m (R 0.69) but is also anti-correlated with the trend of NDVI (R equals 0.65). W10m is decreasing over both the Sahara and the Sahel between 1982 and 2008, and the trends are correlated (R equals 0.53), suggesting that Saharan Sahelian surface winds are a coupled system, driving the inter-annual variation of dust emission.

  3. 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

    2015-11-02

    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

  4. Enhanced tropical storm activity during the African Humid Period induced by Sahara greening and reduced dust emissions

    NASA Astrophysics Data System (ADS)

    Pausata, F. S. R.; Emanuel, K.; Zhang, Q.; Chiacchio, M.; Diro, G. T.; Sushama, L.; Stager, J. C.; Donnelly, J. P.

    2016-12-01

    Given the devastating socioeconomics impact of tropical cyclones (TCs), understanding the amplitude of natural variability is of paramount importance for society. Historical records of TCs are too short to be able to capture such changes and TC paleo-sedimentary archives, spanning several millennia are still very few and patchy. Here we use a fully coupled ocean-atmosphere model to simulate the climate during the African Humid Period (AHP, 10,000 - 5,000 years BP) and investigate potential changes in TC activities compared to pre-industrial (PI) climate. We prescribe the mid-Holocene (MH, 6,000 years BP) orbital forcing as well as more extensive vegetation and reduced airborne dust concentrations relative to PI due to wetter climatic condition in the Sahara. Using a downscaling technique for simulating large numbers of TCs, we analyze a set of sensitivity experiments in which prescribed vegetation and dust concentrations are changed in turn. The changes in solar insolation during the MH (MHPMIP simulation) lead to a westward shift in the Western Pacific tropical storm activity, with an increase in TCs in the South China Sea (Fig. 1a). In the MHPMIP simulation, the TC activity is also increased in the Southern Hemisphere. While stronger boreal summer insolation during the MH does not lead to sizeable changes in the tropical Atlantic cyclones, the Sahara greening and especially the reduced dust largely enhance the storm activity in that region (Fig. 1c), in particular in the Caribbean Sea. The greening of the Sahara and reduced dust alter the thermodynamic state, leading to more favorable conditions for tropical storm development. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in the atmospheric circulation that embraces the entire boreal tropical regions with a net reduction in wind shear during summer. The dust reduction further increases the warming of the ocean surface up to over a 1°C in the North

  5. Late Tertiary and Quaternary river systems of the eastern Sahara as mapped on shuttle radar and LANDSAT images

    NASA Technical Reports Server (NTRS)

    Mccauley, J. F.; Breed, C. S.; Schaber, G. G.

    1985-01-01

    SIR-A pictures of the Eastern Sahara show segments of what are interpreted as relics of once major Tertiary and Quaternary stream valleys. These previously unmapped features have a dark to very dark radar response and are generally concealed below a thin cover of flat to slightly undulating deposits, mostly of eolian origin. In most of the 150 pits and trenches we have studied to date, unconsolidated surface deposits range from a few centimeters to about a meter thick. The SIR-A system was able to "see through" this loose, dry material, to a depth of about a meter or two.

  6. 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

  7. 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.

  8. 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,…).

  9. Survey of Salmonella serovars in broilers and laying breeding reproducers in East of Algeria.

    PubMed

    Ammar, Ayachi; Alloui, Nadir; Bennoune, Omar; Kassah-Laouar, Ahmed

    2010-03-08

    Avian salmonellosis affects the poultry industry in underdeveloped and in developed countries. The aim of this study was to identify the most common Salmonella serovars in broilers and laying breeding reproducers in Eastern Algeria according to the ISO 6579 method. A total of 294 samples were obtained from two flocks of 10,000 broilers and laying breeding reproducers. Samples included livers and spleens, drag swabs of bottom boxes of young chickens, cloacal swabs, and faecal samples of chickens. Additional samples were also taken from water, feed and dusty surfaces. Only the cloacal swabs, poultry faeces and samples from dusty surfaces were positive for Salmonella Typhimurium and Salmonella Livingstone with a detection rate of 12% and 1.6% respectively. The results showed evidence of legislative failure regarding biosafety within the poultry industry in the area of Batna, Eastern Algeria.

  10. First report of Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Oran, West of Algeria.

    PubMed

    Benallal, K E; Allal-Ikhlef, A; Benhamouda, K; Schaffner, F; Harrat, Z

    2016-12-01

    The increasing globalisation of trades, human movements and environmental changes facilitate the introduction and the establishment of the invasive Asian tiger mosquito Aedes albopictus outside its native geographical area. Alerted by the complaints about mosquito biting which occurred daytime for the inhabitants of the seaside town Ain Turk (West of Algeria), an entomological survey was conducted in December 2015 to determine the origin of this nuisance. Among the collected mosquitoes, specimens of Ae. albopictus (2 males, 3 females and 3 pupae) were collected. This is the first observation of that invasive mosquito in the west of Algeria which confirms its presence and establishment in Mediterranean Africa. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. 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. Published by Elsevier B.V.

  12. [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)

  13. 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.

  14. Familial cluster of exposure to a confirmed rabid dog in travelers to Algeria.

    PubMed

    Antwi, Sylvie; Parola, Philippe; Sow, Doudou; Sornin, Victoria; Henrion, Maxime; Gautret, Philippe

    2017-01-09

    A 10 person-family originating from Algeria traveled in rural Algeria for the purpose of visiting friends and relatives without seeking pre-travel advice, did not received pre-travel rabies immunization, and were exposed to a confirmed rabid dog including 8 within less than 4 days of arrival. Three received suckling mouse brain rabies vaccine although WHO strongly recommends that its production and administration be discontinued and seven received insufficient doses of equine rabies immune globulin abroad. Rabies treatment was completed on returning to France. This reports underline the fact that travelers visiting friends and relatives in dog rabies endemic country are at high risk of rabies exposure and unaware of such a risk in most instances. Rabies risk warning should be reinforced and rabies pre-exposure vaccination should be considered in all individuals traveling to North Africa (and to sub-Saharan Africa) whatever the duration of stay.

  15. 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.

  16. 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.

  17. New data on aphid fauna (Hemiptera, Aphididae) in Algeria.

    PubMed

    Laamari, Malik; d'Acier, Armelle Coeur; Jousselin, Emmanuelle

    2013-01-01

    A survey of aphids was carried out during the period 2008-2011 in different regions of Algeria by collecting and identifying aphids and their host plants. Aphids were collected from 46 host plants. Forty-six species were reported including thirty-six species which were recorded for the first time in this country and thirty species which were recorded for the first time in the Maghreb (North Africa). This study extends the number of known Algerian aphid to 156 species.

  18. Medicinal plants used by traditional healers from South-West Algeria: An ethnobotanical study

    PubMed Central

    Benarba, Bachir

    2016-01-01

    Background/Aim: This study aimed to document and analyzes the local knowledge of medicinal plants’ use by traditional healers in South-west Algeria. Methods: The ethnobotanical survey was conducted in two Saharian regions of South-west of Algeria: Adrar and Bechar. In total, 22 local traditional healers were interviewed using semi-structured questionnaire and open questions. Use value (UV), fidelity level (FL), and informant consensus factor (FIC) were used to analyze the obtained data. Results: Our results showed that 83 medicinal plants species belonging to 38 families are used by traditional healers from South-west of Algeria to treat several ailments. Lamiaceae, Asteraceae, Apiaceae, and Fabaceae were the most dominant families with 13, 8, 6, and 4 species, respectively. Leaves were the plant parts mostly used (36%), followed by seeds (18%), aerial parts (17%) and roots (12%). Furthermore, a decoction was the major mode of preparation (49%), and oral administration was the most preferred (80%). Thymus vulgaris L. (UV = 1.045), Zingiber officinale Roscoe (UV = 0.863), Trigonella foenum-graecum L. (UV=0.590), Rosmarinus officinalis L. (UV = 0.545), and Ruta chalepensis L. (UV = 0.5) were the most frequently species used by local healers. A great informant consensus has been demonstrated for kidney (0.727), cancer (0.687), digestive (0.603), and respiratory diseases. Conclusion: This study revealed rich ethnomedicinal knowledge in South-west Algeria. The reported species with high UV, FL, and FIC could be of great interest for further pharmacological studies. PMID:27757260

  19. 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

  20. Tactical Success is Not Enough: The French in Algeria 1954-1962

    DTIC Science & Technology

    2004-02-09

    limit the amount of force used in the operation and prohibited the use of napalm and shelling of villages.55 The French identified the Algerian...organizations.72 In September of 1956, the terror campaign in Algiers began in earnest when three teenage girls , chosen specifically because they were not...Heggoy, A. Insurgency and Counterinsurgency in Algeria (Bloomington, IN: Indiana University Press 1972 ) 4. 32 Clayton, 109. 33 Metz, 37. 34 Ruedy, 134

  1. Deoxynivalenol-producing ability of Fusarium culmorum strains and their impact on infecting barley in Algeria.

    PubMed

    Yekkour, Amine; Toumatia, Omrane; Meklat, Atika; Verheecke, Carol; Sabaou, Nasserdine; Zitouni, Abdelghani; Mathieu, Florence

    2015-06-01

    The cereal-pathogenic Fusarium culmorum (W.G. Smith), causal agent of various blights and rot diseases, is considered as a chronic fungus of economic concern worldwide including North African countries such as Algeria. This pathogen produces a wide range of mycotoxins, amongst which the type B-trichothecene deoxynivalenol (DON). In addition to its acute and chronic side effects in livestock and humans, DON is believed to play a determinant role in the pathogenesis toward Triticeae. However, regardless its significant occurrence and impact, little is known about trichothecenes-producing ability of F. culmorum infecting cereals in Algeria. The PCR assay based on Tri genes of 12 F. culmorum strains (designated Fc1-Fc12), which were recovered from several cropping areas of North Algeria, revealed their trichothecenes-producing ability with 3-AcDON genotype. The molecular prediction was confirmed by HPLC analysis. All strains were able to produce the toxin at detectable levels. Strains Fc1 and Fc12 were the highest producers of this mycotoxin with 220 and 230 µg g(-1), respectively. The evaluation of pathogenic ability of strains through a barley infesting experiment exhibited the significant disease impact of most strains. Significant correlation between the DON-producing ability of strains and the increase in both disease severity (r = 0.88, P = 0.05) and disease occurrence (r = 0.70, P = 0.05) was observed. Chemotyping of F. culmorum isolates and evaluation of their pathogenic ability are reported for the first time for isolates from Algeria, and highlights the important potential of F. culmorum to contaminate cultivated cereal with DON trichothecenes.

  2. Glycaemic threshold for diabetes-specific retinopathy among individuals from Saudi Arabia, Algeria and Portugal.

    PubMed

    Almdal, T P; Handlos, L N; Valerius, M; Juul, E; Nielsen, K E; Vistisen, D; Nielsen, L B; Sheikh, A; Belhadj, M; Nadir, D; Zinai, S; Raposo, J; Lund-Andersen, H; Witte, D R

    2014-03-01

    We studied the glycaemic threshold and prevalence of diabetic retinopathy in screen-detected diabetes in Saudi Arabia, Algeria and Portugal. The prevalence of diabetes-specific retinopathy started to increase at an HbA1c level of 6-6.4% (42-47 mmol/mol) and in individuals with HbA(1c) >7.0% the prevalence was 6.0%. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. Energy consumption renewable energy development and environmental impact in Algeria - Trend for 2030

    NASA Astrophysics Data System (ADS)

    Sahnoune, F.; Imessad, K.; Bouakaz, D. M.

    2017-02-01

    The study provides a detailed analysis of the energy production and consumption in Algeria and the associated CO2 emissions. Algeria is an important energy producer (oil and natural gas). The production is currently around 155 MToe. The total primary energy consumption amounted to about 58 MToe equivalent to 1.46 Toe/capita. The energy demand is still increasing, an average annual growth rate of more than 6% per year during the last decade. The growth rate for electricity production was almost twice that of the total energy consumption. In 2015, the installed capacity of the electricity generation plants reached 17.6 GW. Electricity consumption was 64.6 TWh and is expected to reach at least 75 TWh in 2020 and 130 TWh in 2030. The already high electricity demand will double by 2030. In the structure of final energy consumption, the transport sector ranks first (36%), natural gas consumption ranks second (28.5%), followed by electricity production (27.7%). By activity, the energy sector is the main source of CO2 emissions, about ¾ of the total and this sector has the most important potential for mitigation measures. CO2 emissions from this energy sector amounted to 112.2 MT CO2 as follows: 33% transport, 31% electricity production and 26% from natural gas combustion for residential use. The integration of renewable sources in the energy mix represents for Algeria a major challenge. In 2015, Algeria adopted an ambitious program for development of renewable energy. The target is to achieve 22 GW capacity of electricity from renewable by 2030 to reach a rate of 27 % of national electricity generation through renewable sources. By implementing this program, CO2 emissions of power generation will be reduced by more than 18% in 2030.

  4. Regional Security Cooperation in the Maghreb and Sahel: Algeria’s Pivotal Ambivalence

    DTIC Science & Technology

    2012-02-01

    expected to be completed by 2014. 8 Steven Cook, The Military and Political Development in Egypt, Algeria, and Turkey (Baltimore: Johns Hopkins...Ambassador William M. Bellamy (Ret.) National Defense University 300 Fifth Avenue, Building 21 Fort Lesley J. McNair Washington, DC 20319-5066 Phone...programs, undertaking policy-relevant research and analysis, and fostering awareness of and open dialogue on U.S. strategic priorities and African

  5. American equipment and technology can help satisfy demand for water: Algeria, Egypt, Morocco

    SciTech Connect

    Brown, G.A.

    1982-09-06

    The transfer of US equipment and technology to help North African and Middle East countries develop their water resources must include nonconventional technologies to help them augment existing water supplies. Water development in Morocco, Algeria, and Egypt to meet irrigation, sanitation, and economic development needs presents opportunities to US exporters and investors. This article summarizes the projects and needs in each of the three countries. (DCK)

  6. Molecular detection of Anaplasma platys and Ehrlichia canis in dogs from Kabylie, Algeria.

    PubMed

    Dahmani, Mustapha; Loudahi, Abdelghani; Mediannikov, Oleg; Fenollar, Florence; Raoult, Didier; Davoust, Bernard

    2015-03-01

    Ehrlichia canis and Anaplasma platys are bacteria belonging to the Anaplasmataceae family that cause acute, self-limiting and sometimes fatal vector-borne infections in dogs. These bacteria have been reported worldwide and are transmitted mainly by Rhipicephalus sanguineus. Aside from a report on E. canis once in 1935, no other Anaplasmataceae bacteria have been reported in Algeria to date. The aim of this study was to identify the microbial species implicated in ehrlichiosis and anaplasmosis by a molecular epidemiological survey in dogs. The study was carried out in Kabylie, in northeast Algeria. Sampling was performed in 11 municipalities in the province of Tizi Ouzou and 2 municipalities in the province of Béjaïa. Peripheral blood samples from 110 dogs were screened by qPCR, which is capable of identifying most Anaplasmataceae bacteria. Out of 110, a total of 13 samples screened positive (7/110 E. canis and 6/110 A. platys), and two genetic variants of A. platys and one of E. canis were identified. This is the first study to report the presence of A. platys in dogs from Algeria using a molecular investigative method. This survey was conducted in early spring. As tick activity can affect the prevalence of these pathogens in dogs, further investigations are needed to establish the year-round prevalence of these infections.

  7. GPS water vapor and its comparison with radiosonde and ERA-Interim data in Algeria

    NASA Astrophysics Data System (ADS)

    Namaoui, Houaria; Kahlouche, Salem; Belbachir, Ahmed Hafid; Van Malderen, Roeland; Brenot, Hugues; Pottiaux, Eric

    2017-05-01

    Remote sensing of atmospheric water vapor using global positioning system (GPS) data has become an effective tool in meteorology, weather forecasting and climate research. This paper presents the estimation of precipitable water (PW) from GPS observations and meteorological data in Algeria, over three stations located at Algiers, Bechar and Tamanrasset. The objective of this study is to analyze the sensitivity of the GPS PW estimates for the three sites to the weighted mean temperature ( T m), obtained separately from two types of T m- T s regression [one general, and one developed specifically for Algeria ( T s stands for surface temperature)], and calculated directly from ERA-Interim data. The results show that the differences in T m are of the order of 18 K, producing differences of 2.01 mm in the final evaluation of PW. A good agreement is found between GPS-PW and PW calculated from radiosondes, with a small mean difference with Vaisala radiosondes. A comparison between GPS and ERA-Interim shows a large difference (4 mm) in the highlands region. This difference is possibly due to the topography. These first results are encouraging, in particular for meteorological applications in this region, with good hope to extend our dataset analysis to a more complete, nationwide coverage over Algeria.

  8. [News of antibiotic resistance among Gram-negative bacilli in Algeria].

    PubMed

    Baba Ahmed-Kazi Tani, Z; Arlet, G

    2014-06-01

    Antibiotic resistance has become a major public health problem in Algeria. Indeed the past decade, we have seen a significant increase in resistance to antibiotics especially in Gram-negative bacilli. Resistance to β-lactams in enterobacteria is dominated by the production of ESBL CTX-M-3 and CTX-M-15. The strains producing these enzymes are often the cause of potentially serious infections in both hospital and community settings. Identified plasmid cephalosporinases are CMY-2, CMY-12 and DHA-1. The isolation of strains of Enterobacteriaceae and Pseudomonas aeruginosa producing carbapenemases is rare in Algeria. Some Enterobacteriaceae producing OXA-48 or VIM-19 have been reported; so far, only VIM-2 has been identified in P. aeruginosa. However, the situation regarding the strains of Acinetobacter baumannii resistant to carbapenemases seems to be more disturbing. The carbapenemase OXA-23 is the most common and seems to be endemic in the north. The carbapenemase NDM-1 has also been identified. Resistance to aminoglycosides is marked by the identification armA gene associated with blaCTX-M genes in strains of Salmonella sp. Several other resistance genes have been identified sporadically in strains of Enterobacteriaceae, P. aeruginosa and A. baumannii. Resistance genes to fluoroquinolones are more recent identification in Algeria. The most common are the Qnr determinants followed by the bifunctional enzyme AAC[6']-Ib-cr. Resistance to sulfonamides and trimethoprim was also reported in Enterobacteriaceae strains in the west of the country.

  9. 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.

  10. Silurian shale origin for light oil, condensate, and gas in Algeria and the Middle East

    SciTech Connect

    Zumberge, J.E. ); Macko, S. ) Engel, M. )

    1996-01-01

    Two of the largest gas fields in the world, Hasi R'Mel, Algeria and North Dome, Qatar, also contain substantial condensate and light oil reserves. Gas to source rock geochemical correlation is difficult due to the paucity of molecular parameters in the former although stable isotope composition is invaluable. However, by correlating source rocks with light oils and condensates associated with gas production using traditional geochemical parameters such as biomarkers and isotopes, a better understanding of the origin of the gas is achieved. Much of the crude oil in the Ghadames/Illizi Basins of Algeria has long been thought to have been generated from Silurian shales. New light oil discoveries in Saudi Arabia have also been shown to originate in basal euxinic Silurian shales. Key sterane and terpane biomarkers as well as the stable carbon isotopic compositions of the C15+ saturate and aromatic hydrocarbon fractions allow for the typing of Silurian-sourced, thermally mature light oils in Algeria and the Middle East. Even though biomarkers are often absent due to advanced thermal maturity, condensates can be correlated to the light oils using (1) carbon isotopes of the residual heavy hydrocarbon fractions, (2) light hydrocarbon distributions (e.g., C7 composition), and (3) compound specific carbon isotopic composition of the light hydrocarbons. The carbon isotopes of the C2-C4 gas components ran then be compared to the associated condensate and light oil isotopic composition.

  11. Silurian shale origin for light oil, condensate, and gas in Algeria and the Middle East

    SciTech Connect

    Zumberge, J.E.; Macko, S. Engel, M.

    1996-12-31

    Two of the largest gas fields in the world, Hasi R`Mel, Algeria and North Dome, Qatar, also contain substantial condensate and light oil reserves. Gas to source rock geochemical correlation is difficult due to the paucity of molecular parameters in the former although stable isotope composition is invaluable. However, by correlating source rocks with light oils and condensates associated with gas production using traditional geochemical parameters such as biomarkers and isotopes, a better understanding of the origin of the gas is achieved. Much of the crude oil in the Ghadames/Illizi Basins of Algeria has long been thought to have been generated from Silurian shales. New light oil discoveries in Saudi Arabia have also been shown to originate in basal euxinic Silurian shales. Key sterane and terpane biomarkers as well as the stable carbon isotopic compositions of the C15+ saturate and aromatic hydrocarbon fractions allow for the typing of Silurian-sourced, thermally mature light oils in Algeria and the Middle East. Even though biomarkers are often absent due to advanced thermal maturity, condensates can be correlated to the light oils using (1) carbon isotopes of the residual heavy hydrocarbon fractions, (2) light hydrocarbon distributions (e.g., C7 composition), and (3) compound specific carbon isotopic composition of the light hydrocarbons. The carbon isotopes of the C2-C4 gas components ran then be compared to the associated condensate and light oil isotopic composition.

  12. Neuromyelitis optica spectrum disorders in Algeria: A preliminary study in the region of Tizi Ouzou.

    PubMed

    Daoudi, Smail; Bouzar, Melissa

    2016-03-01

    Neuromyelitis optica (NMO) is a disabling inflammatory condition that targets astrocytes in the optic nerves and spinal cord. Recent advances led to the individualization of a set of conditions now referred as NMO spectrum disorder (NMOSD). To describe the prevalence and characteristics of NMO SD in north Algeria. The present study is a retrospective and descriptive work which took place in Nedir Mohamed teaching hospital, Tizi-Ouzou, Algeria. 938 Medical files of patients with CNS inflammatory demyelinating diseases were reviewed then patients with optic neuritis and/or myelitis were preselected. Patients who met the 2015 neuromyelitis optica spectrum disorders criteria were selected and analyzed 08 Patients (3.4%) met the 2015 criteria for neuromyelitis optica spectrum disorders, 3/8 (37.5%) were positive to AQ4-IgG and 5/8 (62.5%) were negative. Mean age of onset was 29 years, female to male ratio was 3:1, cerebral MRI was normal in 75% of cases and longitudinally extensive transverse myelitis was present in 75% of cases. 37/232 Patients (15.9%) were considered at high risk of neuromyelitis optica spectrum disorders The present study suggests that the spectrum of NMO disorders is a rare entity among patients with optic nerve and spinal cord demyelinating lesions in north Algeria. However, the lack of accurate AQ4-IgG test certainly underestimates its real prevalence. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Molecular characterization of Mycobacterium bovis strains isolated from cattle slaughtered at two abattoirs in Algeria

    PubMed Central

    Sahraoui, Naima; Müller, Borna; Guetarni, Djamel; Boulahbal, Fadéla; Yala, Djamel; Ouzrout, Rachid; Berg, Stefan; Smith, Noel H; Zinsstag, Jakob

    2009-01-01

    Background Bovine Tuberculosis is prevalent in Algeria despite governmental attempts to control the disease. The objective of this study was to conduct, for the first time, molecular characterization of a population sample of Mycobacterium bovis strains isolated from slaughter cattle in Algeria. Between August and November 2007, 7250 animals were consecutively screened at the abattoirs of Algiers and Blida. In 260 animals, gross visible granulomatous lesions were detected and put into culture. Bacterial isolates were subsequently analysed by molecular methods. Results Altogether, 101 bacterial strains from 100 animals were subjected to molecular characterization. M. bovis was isolated from 88 animals. Other bacteria isolated included one strain of M. caprae, four Rhodococcus equi strains, three Non-tuberculous Mycobacteria (NTM) and five strains of other bacterial species. The M. bovis strains isolated showed 22 different spoligotype patterns; four of them had not been previously reported. The majority of M. bovis strains (89%) showed spoligotype patterns that were previously observed in strains from European cattle. Variable Number of Tandem Repeat (VNTR) typing supported a link between M. bovis strains from Algeria and France. One spoligotype pattern has also been shown to be frequent in M. bovis strains from Mali although the VNTR pattern of the Algerian strains differed from the Malian strains. Conclusion M. bovis infections account for a high amount of granulomatous lesions detected in Algerian slaughter cattle during standard meat inspection at Algiers and Blida abattoir. Molecular typing results suggested a link between Algerian and European strains of M. bovis. PMID:19173726

  14. Molecular and Serological Evidence for the Presence of Novel Phleboviruses in Sandflies from Northern Algeria

    PubMed Central

    Moureau, Grégory; Bichaud, Laurence; Salez, Nicolas; Ninove, Laetitia; Hamrioui, Boussad; Belazzoug, Smail; de Lamballerie, Xavier; Izri, Arezki; Charrel, Rémi N

    2010-01-01

    During summer 2007, a total of 785 phlebotomine flies were trapped in northern Algeria, identified morphologically, organised as monospecific pools and tested for the presence of phlebovirus RNA using degenerate primers. Three pools were positive, and the corresponding PCR products were cloned and sequenced. Viral sequences corresponding to two phleboviruses distinct from each other were detected in sandflies circulating in two close locations (140 km apart) in Northern Algeria. The 3 sequences were aligned with homologous polymerase sequences retrieved from the Genbank database, in order to examine their phylogenetic relationships. One viral sequence (from Phlebotomus papatasi) was closely related to but distinct from a sequence obtained from Phlebotomus ariasi sandflies trapped in Algeria in 2006. The two other viral sequences (from Phlebotomus longicuspis) were genetically distantly related to sequences corresponding to virus members of the Sandfly fever Naples virus species and although falling within the same group, this clearly represents a second distinct novel lineage. These results are indicative of a high genetic heterogeneity within sandflies trapped in a relatively small geographic area. Seroprevalence studies conducted on sera from populations living in the same areas indicated that humans can be infected by these viruses. PMID:20563287

  15. Association of CAT-262C/T with the concentration of catalase in seminal plasma and the risk for male infertility in Algeria.

    PubMed

    Bousnane, Nour El Houda; May, Sadiq; Yahia, Mouloud; Abu Alhaija, Abed Alkarem

    2017-10-01

    Catalase (CAT) plays a central role in the protection of different cell types against the deleterious effects of hydrogen peroxide. In human, CAT is implicated in many physiological and pathological conditions including idiopathic male infertility. In this study we examined the association between CAT levels in seminal plasma with different sperm parameters and with CAT-262 C/T polymorphism and their risk for idiopathic male infertility in Algeria. Semen and blood samples were obtained from 111 infertile males and 104 fertile controls from the region of Eastern Algeria following informed consent. Standard semen parameters, DNA integrity, and CAT concentration in seminal plasma were evaluated. CAT-262C/T genotypes were screened using allele specific PCR. Seminal CAT activity was significantly different (p<0.0001) between infertile males and controls, it was also markedly decreased in oligo-astheno-teratozoospermia (p<0.0001), azoospermia (p<0.0001), and normozoospermia (p=0.045) subgroups compared to controls. Positive correlations between CAT activity and semen parameters (volume, motility, concentration, and morphology) were detected, but not with sperm DNA integrity. There was no direct association between CAT-262C/T polymorphism and general male infertility. However, the results presented in this study showed that CAT activity is remarkably associated with the CAT-262T allele (p=0.001) and the different CAT-262C/T genotypes. This study highlighted the major differences in the seminal plasma CAT content between infertile and fertile males and the differences of CAT concentration between different CAT-262C/T genotypes carriers.

  16. The Role of Meteorology and Surface Condition to Multi-Decadal Variations of Dust Emission in Sahara and Sahel

    NASA Astrophysics Data System (ADS)

    Kim, D.; Chin, M.; Diehl, T. L.; Bian, H.; Brown, M. E.; Remer, L. A.; Stockwell, W. R.

    2014-12-01

    North Africa is the world's largest dust source region influencing regional and global climate, human health, and even the local economy. However North Africa as a dust source is not uniform but it consists of the arid region (Sahara) and the semi-arid region (Sahel) with emission rates depending on meteorological and surface conditions. Several recent studies have shown that dust from North Africa seems to have a decreasing trend in the past three decades. The goal of this study is to better understand the controlling factors that determine the change of dust in North Africa using observational data and model simulations. First we analyze surface bareness conditions determined from a long-term satellite observed Normalized Difference Vegetation Index for 1980-2008. Then we examine the key meteorological variables of precipitation and surface winds. Modeling experiments were conducted using the NASA Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, which has been recently updated with a dynamic dust source function. Using the method we separate the dust originating from the Sahel from that of the Sahara desert. We find that the surface wind speed is the most dominant factor affecting Sahelian dust emission while vegetation has a modulating effect. We will show regional differences in meteorological variables, surface conditions, dust emission, and dust distribution and address the relationships among meteorology, surface conditions, and dust emission/loading in the past three decades (1980-2008).

  17. 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.

  18. 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.

  19. Exploring Subsurface Geology Using Radar Techniques: Experiments in Sahara and Consequences for Mars Exploration

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

    For several years, we have conducted a quantitative study of radar penetration performances in various desert arid environments. This study combines both SAR (Synthetic Aperture Radar) imaging from orbital and airborne platforms and in situ GPR (Ground Penetrating Radar) measurements. Laboratory characterization of various minerals and rocks are used as input to electromagnetic models such as IEM (Integral Equation Model) and FDTD (Finite Difference Time Domain) that describe the subsurface scattering process for inversion purposes. Several test sites were explored, mainly the Sahara. Our first experiment was realized in Republic of Djibouti, an arid volcanic area which is a good analog to Mars. We observed a very little radar penetration there because of the presence of iron oxides and salts in the subsurface that make the soil conductive [Paillou et al., GRL, 2001]. A more favorable site for radar penetration was then explored in southern Egypt: the Bir Safsaf area where buried river channels were discovered using orbital SAR images. We showed how to combine SAR and GPR in order to obtain a complete description of subsurface geology down to several meters [Paillou et al., IEEE TGRS, 2003]. Such field experiments were the basis for more systematic laboratory measurements of the electromagnetic properties of various rocks and minerals which were used in numerical models in order to simulate the performances of future Martian radars, e.g. MARSIS and NETLANDER low frequency radars [Heggy et al., Icarus, 2001; Berthelier et al., JGR, 2003; Heggy et al., JGR, 2003]. More recently, new explorations were conducted in Mauritania in order to demonstrate radar capacities for geologic mapping [Grandjean et al., Coll. Afr. Geol., 2004] and in Libya where radar discovered a double impact crater in the southern desert [Paillou et al., C.R. Geoscience, 2003]. More local radar experiments were also conducted on a test site located in France, the Pyla sand dune, where we observed

  20. 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

  1. 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

  2. Calibration and validation of earthquake catastrophe models. Case study: Impact Forecasting Earthquake Model for Algeria

    NASA Astrophysics Data System (ADS)

    Trendafiloski, G.; Gaspa Rebull, O.; Ewing, C.; Podlaha, A.; Magee, B.

    2012-04-01

    Calibration and validation are crucial steps in the production of the catastrophe models for the insurance industry in order to assure the model's reliability and to quantify its uncertainty. Calibration is needed in all components of model development including hazard and vulnerability. Validation is required to ensure that the losses calculated by the model match those observed in past events and which could happen in future. Impact Forecasting, the catastrophe modelling development centre of excellence within Aon Benfield, has recently launched its earthquake model for Algeria as a part of the earthquake model for the Maghreb region. The earthquake model went through a detailed calibration process including: (1) the seismic intensity attenuation model by use of macroseismic observations and maps from past earthquakes in Algeria; (2) calculation of the country-specific vulnerability modifiers by use of past damage observations in the country. The use of Benouar, 1994 ground motion prediction relationship was proven as the most appropriate for our model. Calculation of the regional vulnerability modifiers for the country led to 10% to 40% larger vulnerability indexes for different building types compared to average European indexes. The country specific damage models also included aggregate damage models for residential, commercial and industrial properties considering the description of the buildings stock given by World Housing Encyclopaedia and the local rebuilding cost factors equal to 10% for damage grade 1, 20% for damage grade 2, 35% for damage grade 3, 75% for damage grade 4 and 100% for damage grade 5. The damage grades comply with the European Macroseismic Scale (EMS-1998). The model was validated by use of "as-if" historical scenario simulations of three past earthquake events in Algeria M6.8 2003 Boumerdes, M7.3 1980 El-Asnam and M7.3 1856 Djidjelli earthquake. The calculated return periods of the losses for client market portfolio align with the

  3. New investigation on the choice of the tailored geopotential model for Algeria

    NASA Astrophysics Data System (ADS)

    Daho, S. A. Benahmed; Fairhead, J. D.; Zeggai, A.; Ghezali, B.; Derkaoui, A.; Gourine, B.; Khelifa, S.

    2008-03-01

    The choice of the best geopotential model to reduce geodetic data is one of the critical steps in computing the geoid. Several studies have shown that the geopotential models tailored to regional or local gravity data are best suited for high precision geoid computations. Since 2000 a number of geoid models for Algeria have been produced by Geodetic Laboratory of the National Centre of Space Techniques. In particular 5' × 5' geoid models were generated in 2000, [ Benahmed Daho, S. A., 2000. The new gravimetric geoid in Algeria. IGeS Bulletin No. 10 of the International Geoid Service (IGeS). ISSN 1128-3955. pp. 78-84.] and in 2004 [ Benahmed Daho, S.A., Fairhead, J.D., 2004. A new quasigeoid computation from gravity and GPS data in Algeria. Newton's Bulletin No. 2. A Joint Bulletin of the Bureau Gravimétrique International and of the International Geoid Service. ISSN 1810-8547. pp. 52-59.] using different data sets and techniques. Although these results were satisfactory and internally consistent they do no have the required accuracy to be able to transform a GPS ellipsoidal height to an orthometric height. During the same time and with the recent satellite missions CHAMP and GRACE several new global gravity models were released. These lead to substantial improvements of our knowledge of the long-wavelength part of the Earth's gravity field, and thereby of the long-wavelengths of the geoid. For the computation of a new gravimetric geoid model for Algeria we need a new investigation on the choice of the best and optimal geopotential model for the combined solution with local gravimetric and topographic data using the remove-restore technique. In this paper, an analysis was carried out to define the geopotential model, which fits best the local gravity field in Algeria. Six global geopotential models are used in this study: The new GRACE satellite-only and combined models EIGEN-GRACE02S and GGM02C, combined CHAMP and GRACE model EIGEN-CG01C, combined CHAMP and

  4. 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

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

    PubMed

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

    2008-10-28

    It is widely accepted that modern humans originated in sub-Saharan Africa approximately 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 approximately 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.

  6. Implementation of Information Communication Technology in the Teaching/Learning Process for Sustainable Development of Adults in West Africa Sub Sahara Region

    ERIC Educational Resources Information Center

    Nwobi, Anthonia; Ngozi, Ugwuoke; Rufina, Nwachukwu; Ogbonnaya, Kingsley A.

    2016-01-01

    This study examines the implementation of information technology in the teaching/learning process for sustainable development of adults in West Africa Sub Sahara Region (WASSR). Three research questions and two hypotheses guided the study. The population for the study was 3071 participants and instructors drawn from 10 education centres that were…

  7. Africa South of the Sahara, Rationale and Introduction: An Experimental Program of Study for Secondary School Social Studies Students. Teaching Guide.

    ERIC Educational Resources Information Center

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

    The articulation of a rationale for Project Africa's instructional program, the collection of materials for improving inquiry-oriented instruction at the secondary level about Africa south of the Sahara, and the preparation of teaching and study guides have been completed. This geographic region, rather than the whole continent, was chosen to…

  8. 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…

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

    NASA Astrophysics Data System (ADS)

    Osborne, A. H.; Vance, D.; Rohling, E. J.; Barton, N.; Rogerson, M.; Fello, N.

    2008-12-01

    The climatic history of the Sahara in the Quaternary is likely to have been a key control on the history of human migrations out of Africa. For example, it is widely accepted that modern humans originated in sub- Saharan Africa around 150-200 thousand years ago (ka), but their route of dispersal across the currently hyper-arid Sahara remains controversial. Given that the first modern humans north of the Sahara are found in the Levant around 120-90 ka, northward dispersal likely occurred during the 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. This would explain scattered findings at desert oases of Middle Stone Age (MSA) 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. We have previously used neodymium and oxygen isotope data to suggest that there was enhanced Nile outflow to the Levantine Sea during Saharan humid periods in Stage 5e and the Holocene1. Here, however, we present further geochemical data which suggest that the freshwater signal from Africa was much stronger further west in the Ionian Sea. Furthermore, analyses of shell samples retrieved from the Libyan fossil river channels traces the geochemical signature found in the Ionian Sea to the Tibesti Mountains in the southern Sahara. These data demonstrate that water in the fossil river systems of the Sahara derived from the south during wet episodes in general, and penetrated all the way to the Mediterranean during MIS 5e in particular, confirming the existence of an uninterrupted freshwater corridor across

  10. Imperialism, colonial identity, and race in Algeria, 1830-1870. The role of the French Medical Corps.

    PubMed

    Lorcin, P M

    1999-12-01

    During the military administration of Algeria, which lasted for forty years, the foundation of the French colony was laid. Indispensable to the military in Algeria was its sizable medical corps. While the ostensible reason for its presence was to maintain the soldiers' health and thus the army's efficiency, it role extended beyond this primary objective. Starting from the intellectual and political influences that shaped the training in France of the members of the medical corps, this essay examines the ways in which they contributed to the creation of a French colonial space in Algeria. It traces how their involvement in the intellectual, cultural, and political life of the colony enabled them both to further their own ambitions and to influence wider developments. It explores how colonial physicians and surgeons, deemed to be among the most efficient agents of the civilizing mission owing to their humane contacts with the indigenous population, in fact contributed to that population's categorization and marginalization.

  11. Lower Palaeozoic of North-Western and West-Central Africa

    SciTech Connect

    Holland, C.H.

    1985-01-01

    The first compilation in English of the stratigraphy, palaeontology, sedimentology, palaeogeography, and palaeoclimatology of the Lower Palaeozoic found in this area. The fourth volume in the Lower Palaeozoic Rocks of the World Series discusses geological formations such as the lower Cambrian tribolite-bearing sequences of Morocco, those showing evidence of late Ordovician glaciation in West-Central Africa, and the Silurian-Devonian sequences of Morocco and Algeria.

  12. Phylogeny of North African Agama lizards (Reptilia: Agamidae) and the role of the Sahara desert in vertebrate speciation.

    PubMed

    Gonçalves, Duarte V; Brito, José C; Crochet, Pierre-André; Geniez, Philippe; Padial, José M; Harris, D James

    2012-09-01

    The origin of Saharan biodiversity is poorly understood, in part because the geological and paleoclimatic events that presumably shaped species diversity are still controversial, but also because few studies have explored causal explanations for the origin of Saharan diversity using a phylogenetic framework. Here, we use mtDNA (16S and ND4 genes) and nDNA (MC1R and CMOS genes) to infer the relationships and biogeographic history of North African agamas (genus Agama). Agamas are conspicuous, diverse and abundant African lizards that also occur in the Saharan xeric and mesic environments. Our results revealed the presence of three Agama lineages in North Africa: one Afrotropical, one Sahelo-Saharan, and one broadly distributed in North Africa and mainly Saharan. Southern Mauritania contains the highest known diversity, with all three lineages present. Results suggest that agamas colonized the Sahara twice, but only one lineage was able to radiate and diversify there. Species in the Saharan lineage are mostly allopatric, and their splitting, genetic diversity and distribution are greatly explained by mountain ranges. One species in this lineage has colonized the Mediterranean climatic zone (A. impalearis), and another one the Sahel savannah (A. boueti). The other lineage to colonize the Sahara corresponds to A. boulengeri, an eminently Sahelian species that also inhabits Saharan mountain ranges in Mauritania and Mali. Phylogenetic analyses indicate that allopatric montane populations within some currently recognized species are also genetically divergent. Our study therefore concludes that vicariant speciation is a leading motor of species diversification in the area: Inside the Sahara, associated to mountain-ranges isolated by dune seas and bare plains; outside, associated to less harsh climates to the North and South. Paleoclimatic oscillations are suggested as causal explanations of the vicariant distribution and origin of species. Agamas are thought to have

  13. The evolution of the 87Sr/86Sr in the Dead Sea brine: from the Sedom lagoon to Sahara dusts

    NASA Astrophysics Data System (ADS)

    Stein, Mordechai

    2016-04-01

    The history of water-bodies in the Dead Sea brines commenced with the intrusion of the Sedom lagoon, possibly in the late Neogene and continued with the development of hypersaline and freshwater lakes (e.g. the modern Dead Sea and Sea of Galilee). 87Sr/86Sr ratios in these water-bodies decreased over the past ~ 5-6 Ma from 0.7087-0.7084 in salts deposited in the Sedom lagoon to ~ 0.7080 in modern Dead Sea brine. The 87Sr/86Sr ratios in the salts deposited from Sedom lagoon are significantly lower than those of the contemporaneous late Miocene seawater (~0.709). This difference was attributed to modification of the 87Sr/86Sr ratio in the Sedom lagoon solution by influx of Ca-chloride brines. The brines, in turn were formed by dolomitization of marine limestones of the DSR Cretaceous wall rocks (87Sr/86Sr ~ 0.7075) by the ingressing evaporated seawaters (Stein et al., 2000). After the disconnection of the Sedom lagoon from the open sea freshwater filled the lakes that occupied the Dead Sea basin. The freshwater influx modified the strontium isotope and chemical composition of the brine and provided bicarbonate and sulfate to the lake that led the precipitation of primary aragonite and gypsum. Freshwater that currently enter the lake are characterize by 87Sr/86Sr ~ 0.7081, significantly higher than the Cretaceous carbonates. Settled dust that deposits on the Judea Mountains is composed of calcite and quartz grains and is characterized by 87Sr/86Sr ratios ~ 0.7084. It appears that significant amounts of the strontium that entered the lakes with the freshwater originated from dissolution of the dust calcites. Large amounts of dust were transported from the Sahara desert to the Dead Sea watershed during glacial periods when the Sahara was dry and sea-level was low. The source of the detrital calcites however, is not known. They could be derived from dry paleo-lakes in the Sahara that were previously filled by waters that retained the required strontium isotope

  14. Dust emission from different sol types and geomorphic units in the Sahara - implications for modeling dust emission and transport

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Mineral dust plays multiple roles in mediating physical and biogeochemical exchanges among the atmosphere, land and ocean, and thus is an active component of the global climate system. To estimate the past, current, and future impacts of dust on climate, sources of dust and their erodibility should be identified. The Sahara is the major source of dust on Earth. Based on qualitative analysis of remotely sensed data with low temporal resolution, the main sources of dust that have been identified are topographic depressions comprised of dry lake and playa deposits in hyprarid regions. Yet, recent studies cast doubts on these as the major sources and call for a search for others. Moreover, the susceptibility of soils to aeolian erosion (wind land erodibility) in the Sahara is still poorly known. In this study we identify and determine the soil types and geomorphic units most important as Saharan dust sources by correlating 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/geomorphic units. During 2006-8 the source of over 90% of the NDS was sand dunes, leptosols, calcisols, arenosols, and rock debris. Few dust storms originated from dry lake beds and playas. Land erodibility by wind for each soil type/geomorphic unit was estimated by a regression of the NDS and the number of days with high-speed wind events; the regression is relatively high for sand dunes and gypsisols. We use these regressions to differentiate between sources of dust that are supply-limited to those that are transport-limited. We propose that the fracturing of saltating sand and the removal of clay coatings from sand grains through eolian abrasion is the dominant dust-emission mechanism for the sand-rich areas covering large portion of the Sahara. Our results also explain the increased dustiness during the last glacial period, when sand dunes activity has been more common than during the Holocene

  15. Probabilistic seismic hazard assessment based on seismic potential of active faults: Example from northern Algeria

    NASA Astrophysics Data System (ADS)

    Bouhadad, Youcef

    2017-04-01

    Northern Algeria is an interplate area where the African and the Eurasian tectonic plates are converging in the NW-SE direction. Therefore, earthquakes are not distributed randomly but directly related to the activity of active faults. The seismotectonic conditions of occurrence of strong damaging earthquakes in the area are well understood following the numerous detailed studies that followed the El-Asnam October 10th , 1980 earthquake (Ms=7.3) and the Zemmouri May 1st , 2003 (Mw=6.8) earthquake. The potentially active structures consist of active folds or asymmetrical folds underlined by thrust faults. Some of the faults are blind as revealed by the Chenoua 29th , 1989 (Ms=6.0) and the Ain Temouchent 1999 (Ms=5.6) earthquakes. We applied the probabilistic approach to assess seismic hazard in the area of Mostaganem, western Algeria. The following steps are performed (i) Seismic sources are identified on the basis of field geological/geophysical investigations,(ii) Source parameters such as b-values, slip rate and maximum magnitude are assessed for each seismic source, and then given a weight in the framework of a logic tree model, (iii) Attenuation relations which fit Algerian strong motion records are used, (iv) Results are presented as annual frequencies of exceedance versus peak ground acceleration (PGA) as well as maps of hazard for different return periods. Finally, we quantified and discussed the scientific uncertainties related to the state of knowledge and the used alternative models and values. Keywords: seismic hazard- active faults- probabilistic approach- uncertainties-Algeria

  16. Predictive Factors of Obesity and their Relationships to Dietary Intake in Schoolchildren in Western Algeria

    PubMed Central

    Saker, Meriem; Merzouk, Hafida; Merzouk, Sid A; Ahmed, Samira Baba; Narce, Michel

    2011-01-01

    ABSTRACT Background: Obesity has reached epidemic proportions world-wide. Its risk factors are poorly studied, especially among children in developing countries such as Algeria. Objectives: The purpose of this study was therefore to determine the prevalence and risk factors of obesity in Algerian schoolchildren 6 to 8 years aged by conducting a school-site retrospective cohort study in Tlemcen Department (western Algeria). Material and Mthods: From 2008 to 2010, socio-demographic characteristics, body mass index (BMI), physical activity categories, lifestyle and nutritional habits of 1520 children (839 boys and 681 girls), at entrance into primary school, were recorded using a self-administered questionnaire. Results: Among the 1520 participants, 99 (6.5%) were obese. Birthweight ≤ 2.5 kg and ≥ 4 kg, early introduction of solid foods and low physical activity were significantly associated with obesity (p<0.001). Additionally, mother's and grandmother's BMI ≥30 kg/m2, fewer children in the household, higher parental education, household income and the presence of familial obesity may predispose significantly to childhood obesity (p<0.001). Furthermore, child's BMI was significant positively correlated with total energy, fat and saturated fatty acid (SFA) intakes (p<0.01). Mother's and grandmother's BMI were significant positively correlated with child total energy, fat and SFA intakes. Physical activity score was significant negatively correlated with child total energy, fat and SFA (p<0.01) intakes in obese children. Conclusions: Mother's and grandmother's obesity, excess energy and fat intakes and low physical activity are the strong predictors of childhood obesity in Algeria. Preventive measures should focus on the promotion of physical activity and maternal and children nutritional education. PMID:22205890

  17. Predictive Factors of Obesity and their Relationships to Dietary Intake in Schoolchildren in Western Algeria.

    PubMed

    Saker, Meriem; Merzouk, Hafida; Merzouk, Sid A; Ahmed, Samira Baba; Narce, Michel

    2011-04-01

    Obesity has reached epidemic proportions world-wide. Its risk factors are poorly studied, especially among children in developing countries such as Algeria. The purpose of this study was therefore to determine the prevalence and risk factors of obesity in Algerian schoolchildren 6 to 8 years aged by conducting a school-site retrospective cohort study in Tlemcen Department (western Algeria).Material and Mthods: From 2008 to 2010, socio-demographic characteristics, body mass index (BMI), physical activity categories, lifestyle and nutritional habits of 1520 children (839 boys and 681 girls), at entrance into primary school, were recorded using a self-administered questionnaire. Among the 1520 participants, 99 (6.5%) were obese. Birthweight ≤ 2.5 kg and ≥ 4 kg, early introduction of solid foods and low physical activity were significantly associated with obesity (p<0.001). Additionally, mother's and grandmother's BMI ≥30 kg/m(2), fewer children in the household, higher parental education, household income and the presence of familial obesity may predispose significantly to childhood obesity (p<0.001). Furthermore, child's BMI was significant positively correlated with total energy, fat and saturated fatty acid (SFA) intakes (p<0.01). Mother's and grandmother's BMI were significant positively correlated with child total energy, fat and SFA intakes. Physical activity score was significant negatively correlated with child total energy, fat and SFA (p<0.01) intakes in obese children. Mother's and grandmother's obesity, excess energy and fat intakes and low physical activity are the strong predictors of childhood obesity in Algeria. Preventive measures should focus on the promotion of physical activity and maternal and children nutritional education.

  18. Implications of high altitude desert dust transport from Western Sahara to Nile Delta during biomass burning season.

    PubMed

    Prasad, Anup K; El-Askary, Hesham; Kafatos, Menas

    2010-11-01

    The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe.

  19. Dust and biological aerosols from the Sahara and Asia influence precipitation in the western U.S.

    PubMed

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

    2013-03-29

    Winter storms in California's Sierra Nevada increase seasonal snowpack and provide critical water resources and hydropower 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, whereas 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 probably serve as IN and play an important role in orographic precipitation processes over the western United States.

  20. A multi-gene analysis of diversity of Bartonella detected in fleas from Algeria.

    PubMed

    Bitam, Idir; Rolain, Jean Marc; Nicolas, Violaine; Tsai, Yi-Lun; Parola, Philippe; Gundi, Vijay A K B; Chomel, Bruno B; Raoult, Didier

    2012-01-01

    We report the molecular detection of several Bartonella species in 44 (21.5%) of 204 fleas from Algeria collected from 26 rodents and 7 hedgehogs. Bartonella elizabethae and B. clarridgeiae were detected in the fleas collected on hedgehogs. Bartonella tribocorum and B. elizabethae were detected in fleas collected from rats and mice, and sequences similar to an unnamed Bartonella sp. detected in rodents from China were detected in rats as well as a genotype of Bartonella closely related to Bartonella rochalimae detected in fleas collected on brown rats (Rattus norvegicus).