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Sample records for african ephemeral rivers

  1. Towards reliable seasonal ensemble streamflow forecasts for ephemeral rivers

    Science.gov (United States)

    Bennett, James; Wang, Qj; Li, Ming; Robertson, David

    2016-04-01

    Despite their inherently variable nature, ephemeral rivers are an important water resource in many dry regions. Water managers are likely benefit considerably from even mildly skilful ensemble forecasts of streamflow in ephemeral rivers. As with any ensemble forecast, forecast uncertainty - i.e., the spread of the ensemble - must be reliably quantified to allow users of the forecasts to make well-founded decisions. Correctly quantifying uncertainty in ephemeral rivers is particularly challenging because of the high incidence of zero flows, which are difficult to handle with conventional statistical techniques. Here we apply a seasonal streamflow forecasting system, the model for generating Forecast Guided Stochastic Scenarios (FoGSS), to 26 Australian ephemeral rivers. FoGSS uses post-processed ensemble rainfall forecasts from a coupled ocean-atmosphere prediction system to force an initialised monthly rainfall runoff model, and then applies a staged hydrological error model to describe and propagate hydrological uncertainty in the forecast. FoGSS produces 12-month streamflow forecasts; as forecast skill declines with lead time, the forecasts are designed to transit seamlessly to stochastic scenarios. The ensemble rainfall forecasts used in FoGSS are known to be unbiased and reliable, and we concentrate here on the hydrological error model. The FoGSS error model has several features that make it well suited to forecasting ephemeral rivers. First, FoGSS models the error after data is transformed with a log-sinh transformation. The log-sinh transformation is able to normalise even highly skewed data and homogenise its variance, allowing us to assume that errors are Gaussian. Second, FoGSS handles zero values using data censoring. Data censoring allows streamflow in ephemeral rivers to be treated as a continuous variable, rather than having to model the occurrence of non-zero values and the distribution of non-zero values separately. This greatly simplifies parameter

  2. The evolution of an ephemeral river during the rising and receding phases of medium and low magnitude discharge events

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    Lotsari, E. S.; Calle, M.; Benito-Ferrandez, G.; Kaartinen, H.; Kukko, A.; Hyyppä, J.; Hyyppä, H.; Alho, P.

    2015-12-01

    In addition to great flash floods, medium and low magnitude discharge events can also cause great morphological changes in ephemeral river channels. Despite the advances in measurement techniques, such as laser scanning, and simulation approaches, the channel evolution during the different phases of discharge events is still not well known in gravelly ephemeral rivers, such as Rambla de la Viuda (Spain). The aim is to detect the temporal evolution of the ephemeral river channel during consecutive medium (March 2013) and low (May 2013) magnitude discharge events. The study is based on both accurate topographical measurements (laser scanning) and morphodynamic simulations (Delft 2D). Before the final analysis, the model's performance was tested with different parameterizations. When compared to the observed channel changes, the transport equation had crucial role in simulation results. Engelund-Hansen equation succeeded the best. It was important to use spatially varying grain sizes. Erosion and deposition (m3) were the greatest during the first hours of the rising phase of the discharge events. After this, erosion and deposition amounts, which were detected hourly, started declining. Thus, this occurred before the peak discharge, and erosion slowed down more than deposition. After the discharge peak, changes in deposition and erosion amounts were slightly more gradual than changes in discharge. The deposition during the receding phase was due to the advancing bar lobe frontier. River bed changes followed temporally the changes in discharges during the receding phase. This was different to the rising phase, when temporal differences occurred between changes in discharges and changes in deposition and erosion. This study shows that both rising and receding phases of discharge events are important for bar movement and channel evolution of the gravelly ephemeral river.

  3. Ground water input to a rare flood event in an arid zone ephemeral river identified with isotopes and chemistry

    International Nuclear Information System (INIS)

    Various isotope studies in temperate climates have shown that the shallow groundwater component feeding perennial rivers during rainfall events can be more important than surface runoff. We report, here on possibly unique isotopic and chemical evidence of groundwater contributions to a rare Hood event of the ephemeral Auob River during the exceptional rains of 1999/2000 in the arid/semi-arid Kalahari of southeastern Namibia. The recognition of this process was enabled by a detailed knowledge of the isotope hydrology of groundwater in the area and provided insights into aspects of the palaeo-hydrology of the Auob River catchment. (author)

  4. Ground water input to a rare flood event in an arid zone ephemeral river identified with isotopes and chemistry

    International Nuclear Information System (INIS)

    Various isotope studies in temperate climates have shown that the shallow groundwater component feeding perennial rivers during rainfall events can be more important than surface runoff, We report here on possibly unique isotopic and chemical evidence of groundwater contributions to a rare flood event of the ephemeral Auob River during the exceptional rains of 1999/2000 in the arid/semiarid Kalahari of south-eastern Namibia. The recognition of this process was enabled by a detailed knowledge of the isotope hydrology of groundwater in the area and provided insights into aspects of the palaeo-hydrology of the Auob River catchment. (author)

  5. Recent human impacts and change in dynamics and morphology of ephemeral rivers

    Directory of Open Access Journals (Sweden)

    J. A. Ortega

    2013-04-01

    Full Text Available Ephemeral streams induce flash-flood events which cause dramatic morphological changes and impacts on population, due the intermittent activity of these fluvial systems. Human pressure changes the fluvial environment and so enhances the effects of natural dynamics. Local human-induced modifications can be latent over long periods of time. These changes can be studied after the flood event, to quantify their effects and detect which are most harmful. In this paper we study flash-flood effects at two sites in Spain and compare the results before and after a~flood event. Erosion is associated with areas where there have been more anthropogenic changes in floodplains and channels. Deposition is related to erosional processes in the watershed and to the tributaries. Disruption of river channel patterns changes connectivity and scouring appears due to energy excess. This excess tends to concentrate at weak points downstream produced by anthropic disturbances. Riparian vegetation is an energy sink and reaches with more cover show less erosion than those with deforestation. Infrastructures perpendicular to the direction of flow increase stream power, but peaks of erosion on the floodplain appear displaced downstream. It is important to detect human changes by analysis of hydraulic variables before the occurrence of an extraordinary event in order to anticipate catastrophic consequences resulting from inappropriate fluvial management.

  6. Integrated and adaptive management for sustainable water use along ephemeral rivers under severe uncertainty of future flood regimes

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    Arnold, Sven; Attinger, Sabine; Frank, Karin; Baxter, Peter; Hildebrandt, Anke

    2010-05-01

    Ephemeral rivers are located throughout the world's arid regions. They are characterised by temporary surface flow that strongly varies between seasons and years. Along the river course often a coupled eco-hydrological vegetation-groundwater system has established, which is referred to as linear oasis, reflecting the ecological and socio-economic importance of ephemeral rivers in otherwise dry areas. The Kuiseb River denotes such a linear oasis and is one of the most diversely used environments among the ephemeral rivers in Namibia. Along the entire river course surface runoff and ground water are exploited for drinking, farming, and mining. The middle section of the Kuiseb River is characterised by strong eco-hydrological feedbacks between the vegetation and the ground water resource. Temporary floods infiltrate into sediments, which are accumulated in geological pools of impermeable bedrocks. This enables the formation of shallow ground water. The low depth to ground water allows root water uptake by plants and the establishment of a thriving ecosystem. The sustainable use of ecological and hydrological resources along ephemeral rivers is crucial to preserve the natural ecosystem. However, the investigation of management strategies that consider both the regulation of water extraction and vegetation structure requires models that explicitly consider the feedbacks between the water resource and the ecosystem structure. Further, uncertainties arise from stochastic hydrologic drivers such as flash flood events. Particularly in the face of climate change, the management strategies have to be applicable to a wide range of possible flood regimes, i.e. they have to be robust to the uncertainty of future flood regimes. In this study we assess a variety of management strategies regarding their robustness under different theoretical ecosystems and under uncertainty in the future stochastic flood regimes along the Kuiseb River. We consider the trade-off between ecological

  7. Fertilisation of the Southern Atlantic: Ephemeral River Valleys as a replenishing source of nutrient-enriched mineral aerosols

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    Dansie, Andrew; Wiggs, Giles; Thomas, David

    2016-04-01

    Oceanic dust deposition provides biologically important iron and macronutrients (Phosphorus (P) and Nitrogen-based (N) compounds) that contribute to phytoplankton growth, marine productivity and oceanic atmospheric CO2 uptake. Research on dust emission sources to date has largely focused on the northern hemisphere and on ephemeral lakes and pans. Our work considers the ephemeral river valleys of the west coast of Namibia as an important yet overlooked source of ocean-fertilizing dust. Dust plumes are frequently emitted from the river valleys by strong easterly winds during the Southern Hemisphere winter, when the upwelling of the Benguela Current is at its weakest. We present field data from dust emission source areas along the main river channels near the coastal termini of the Huab, Kuiseb and Tsauchab river valleys. Collected data include erodible surface sediment, wind-blown flux, and associated meteorological data. Extensive surface sediment sampling was also undertaken throughout the combined 34,250 km2 extent of each river valley catchment with samples collected from within the main river channels, the main branches of each river system, selected tributaries, and into the upper watersheds. Geochemical data show valley sediment and wind-blown flux material have high concentrations of bioavailable Fe, P and N, exceeding that measured at the major dry lake basin dust sources in southern Africa. The contribution of fertilising deposition material is enhanced by both the spatial proximity of the source areas to the ocean and enrichment of source material by ephemeral fluvial accumulation and desiccation. Results show that geographical factors within each watershed play a key role in the nutrient composition of the emitting fluvial deposits in the river valleys. Analysis explores potential relationships between land use, geology, climate and precipitation in the upper watersheds and their influence on bioavailability of Fe, P and N compounds in wind

  8. Nutrient contributions to the Santa Barbara Channel, California, from the ephemeral Santa Clara River

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    Warrick, J.A.; Washburn, L.; Brzezinski, Mark A.; Siegel, D.A.

    2005-01-01

    The Santa Clara River delivers nutrient rich runoff to the eastern Santa Barbara Channel during brief (???1-3 day) episodic events. Using both river and oceanographic measurements, we evaluate river loading and dispersal of dissolved macronutrients (silicate, inorganic N and P) and comment on the biological implications of these nutrient contributions. Both river and ocean observations suggest that river nutrient concentrations are inversely related to river flow rates. Land use is suggested to influence these concentrations, since runoff from a subwatershed with substantial agriculture and urban areas had much higher nitrate than runoff from a wooded subwatershed. During runoff events, river nutrients were observed to conservatively mix into the buoyant, surface plume immediately seaward of the Santa Clara River mouth. Dispersal of these river nutrients extended 10s of km into the channel. Growth of phytoplankton and nutrient uptake was low during our observations (1-3 days following runoff), presumably due to the very low light levels resulting from high turbidity. However, nutrient quality of runoff (Si:N:P = 16:5:1) was found to be significantly different than upwelling inputs (13:10:1), which may influence different algal responses once sediments settle. Evaluation of total river nitrate loads suggests that most of the annual river nutrient fluxes to the ocean occur during the brief winter flooding events. Wet winters (such as El Nin??o) contribute nutrients at rates approximately an order-of-magnitude greater than "average" winters. Although total river nitrate delivery is considerably less than that supplied by upwelling, the timing and location of these types of events are very different, with river discharge (upwelling) occurring predominantly in the winter (summer) and in the eastern (western) channel. ?? 2004 Elsevier Ltd. All rights reserved.

  9. The role of vegetation in the formation of anabranching channels in an ephemeral river, Northern plains, arid central Australia

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    Tooth, Stephen; Nanson, Gerald C.

    2000-10-01

    As the distribution and abundance of vegetation in drylands is often controlled by the greater availability of water along river channels, riparian vegetation has the potential to influence significantly dryland river form, process and behaviour. This paper demonstrates how a small indigenous shrub, the inland teatree (Melaleuca glomerata), influences the formation and maintenance of anabranching channels in a reach of the ephemeral Marshall River, Northern Plains, arid central Australia. Here, the Marshall is characterized by ridge-form anabranching, where water and sediment are routed through subparallel, multiple channels of variable size which occur within a typically straight channel-train. Channels are separated by channel-train ridges - narrow, flow-aligned, vegetated features - or by wider islands. By providing a substantial element of boundary roughness, dense stands of teatrees growing on channel beds or atop the ridges and islands influence flow velocities, flow depths and sediment transport, resulting in flow diversion, bank and floodplain erosion, and especially sediment deposition. Ridges and islands represent a continuum of forms, and their formation and development can be divided into a three-stage sequence involving teatree growth and alluvial sedimentation.1Teatrees colonize a flat, sandy channel bed, initiating the formation of ridges by lee-side accretion. Individual ridges grow laterally, vertically and longitudinally and maintain a geometrically similar streamlined (lemniscate) form that presents minimum drag.2Individual ridges grow in size, and interact with neighbouring ridges, causing the lemniscate forms to become distorted. Ridges in the lee of other ridges tend to be protected from the erosive effects of floods and survive, whereas individual teatrees or small ridges exposed to flow concentrated between larger ridges, tend to be removed.3organized system of ridge-form anabranches. In the moderate- to low-gradient Marshall River, which is

  10. Water quality modelling for ephemeral rivers: Model development and parameter assessment

    Science.gov (United States)

    Mannina, Giorgio; Viviani, Gaspare

    2010-11-01

    SummaryRiver water quality models can be valuable tools for the assessment and management of receiving water body quality. However, such water quality models require accurate model calibration in order to specify model parameters. Reliable model calibration requires an extensive array of water quality data that are generally rare and resource-intensive, both economically and in terms of human resources, to collect. In the case of small rivers, such data are scarce due to the fact that these rivers are generally considered too insignificant, from a practical and economic viewpoint, to justify the investment of such considerable time and resources. As a consequence, the literature contains very few studies on the water quality modelling for small rivers, and such studies as have been published are fairly limited in scope. In this paper, a simplified river water quality model is presented. The model is an extension of the Streeter-Phelps model and takes into account the physico-chemical and biological processes most relevant to modelling the quality of receiving water bodies (i.e., degradation of dissolved carbonaceous substances, ammonium oxidation, algal uptake and denitrification, dissolved oxygen balance, including depletion by degradation processes and supply by physical reaeration and photosynthetic production). The model has been applied to an Italian case study, the Oreto river (IT), which has been the object of an Italian research project aimed at assessing the river's water quality. For this reason, several monitoring campaigns have been previously carried out in order to collect water quantity and quality data on this river system. In particular, twelve river cross sections were monitored, and both flow and water quality data were collected for each cross section. The results of the calibrated model show satisfactory agreement with the measured data and results reveal important differences between the parameters used to model small rivers as compared to

  11. Design of a sediment-monitoring gaging network on ephemeral tributaries of the Colorado River in Glen, Marble, and Grand Canyons, Arizona

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    Griffiths, Ronald E.; Topping, David J.; Anderson, Robert S.; Hancock, Gregory S.; Melis, Theodore S.

    2014-01-01

    Management of sediment in rivers downstream from dams requires knowledge of both the sediment supply and downstream sediment transport. In some dam-regulated rivers, the amount of sediment supplied by easily measured major tributaries may overwhelm the amount of sediment supplied by the more difficult to measure lesser tributaries. In this first class of rivers, managers need only know the amount of sediment supplied by these major tributaries. However, in other regulated rivers, the cumulative amount of sediment supplied by the lesser tributaries may approach the total supplied by the major tributaries. The Colorado River downstream from Glen Canyon has been hypothesized to be one such river. If this is correct, then management of sediment in the Colorado River in the part of Glen Canyon National Recreation Area downstream from the dam and in Grand Canyon National Park may require knowledge of the sediment supply from all tributaries. Although two major tributaries, the Paria and Little Colorado Rivers, are well documented as the largest two suppliers of sediment to the Colorado River downstream from Glen Canyon Dam, the contributions of sediment supplied by the ephemeral lesser tributaries of the Colorado River in the lowermost Glen Canyon, and Marble and Grand Canyons are much less constrained. Previous studies have estimated amounts of sediment supplied by these tributaries ranging from very little to almost as much as the amount supplied by the Paria River. Because none of these previous studies relied on direct measurement of sediment transport in any of the ephemeral tributaries in Glen, Marble, or Grand Canyons, there may be significant errors in the magnitudes of sediment supplies estimated during these studies. To reduce the uncertainty in the sediment supply by better constraining the sediment yield of the ephemeral lesser tributaries, the U.S. Geological Survey Grand Canyon Monitoring and Research Center established eight sediment-monitoring gaging

  12. Precipitation and runoff simulations of select perennial and ephemeral watersheds in the middle Carson River basin, Eagle, Dayton, and Churchill Valleys, west-central Nevada

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    Jeton, Anne E.; Maurer, Douglas K.

    2011-01-01

    The effect that land use may have on streamflow in the Carson River, and ultimately its impact on downstream users can be evaluated by simulating precipitation-runoff processes and estimating groundwater inflow in the middle Carson River in west-central Nevada. To address these concerns, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, began a study in 2008 to evaluate groundwater flow in the Carson River basin extending from Eagle Valley to Churchill Valley, called the middle Carson River basin in this report. This report documents the development and calibration of 12 watershed models and presents model results and the estimated mean annual water budgets for the modeled watersheds. This part of the larger middle Carson River study will provide estimates of runoff tributary to the Carson River and the potential for groundwater inflow (defined here as that component of recharge derived from percolation of excess water from the soil zone to the groundwater reservoir). The model used for the study was the U.S. Geological Survey's Precipitation-Runoff Modeling System, a physically based, distributed-parameter model designed to simulate precipitation and snowmelt runoff as well as snowpack accumulation and snowmelt processes. Models were developed for 2 perennial watersheds in Eagle Valley having gaged daily mean runoff, Ash Canyon Creek and Clear Creek, and for 10 ephemeral watersheds in the Dayton Valley and Churchill Valley hydrologic areas. Model calibration was constrained by daily mean runoff for the 2 perennial watersheds and for the 10 ephemeral watersheds by limited indirect runoff estimates and by mean annual runoff estimates derived from empirical methods. The models were further constrained by limited climate data adjusted for altitude differences using annual precipitation volumes estimated in a previous study. The calibration periods were water years 1980-2007 for Ash Canyon Creek, and water years 1991-2007 for Clear Creek. To

  13. Rainfall-runoff modelling and palaeoflood hydrology applied to reconstruct centennial scale records of flooding and aquifer recharge in ungauged ephemeral rivers

    Directory of Open Access Journals (Sweden)

    G. Benito

    2010-12-01

    Full Text Available In this study we propose a multi-source data approach for quantifying long-term flooding and aquifer recharge in ungauged ephemeral rivers. The methodology is applied to the Buffels River, at 9000 km2 the largest ephemeral river in Namaqualand (NW South Africa, a region with scarce stream flow records limiting research investigating hydrological response to global change. Daily discharge and annual flood series (1965–2006 were estimated from a distributed rainfall-runoff hydrological model (TETIS using rainfall gauge records located within the catchment. The model was calibrated and validated with data collected during a two year monitoring programme (2005–2006 at two stream flow stations, one each in the upper and lower reaches of the catchment. In addition to the modelled flow records, non-systematic flood data were reconstructed using both sedimentary and documentary evidence. The palaeoflood record identified at least 25 large floods during the last 700 yr; with the largest events reaching a minimum discharge of 255 m3 s−1 (450 yr return period in the upper basin, and 510 m3 s−1 (100 yr return period in the lower catchment. Since 1925 AD, the flood hydrology of the Buffels River has been characterised by a decrease in the magnitude and frequency of extreme events, with palaeoflood discharges five times greater than the largest modelled floods during the period 1965–2006. Large floods generated the highest hydrograph volumes, however their contribution to aquifer recharge is limited as this depends on other factors such as flood duration and storage capacity of the unsaturated zone prior to the flood. Floods reaching flows associated with 5–10 yr return periods (120–140 m3 s−1 and flowing for 12 days are able to fully saturate the Spektakel aquifer in the lower Buffels River basin.

  14. Discontinuous ephemeral streams

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    Bull, William B.

    1997-07-01

    Many ephemeral streams in western North America flowed over smooth valley floors before transformation from shallow discontinuous channels into deep arroyos. These inherently unstable streams of semiarid regions are sensitive to short-term climatic changes, and to human impacts, because hillslopes supply abundant sediment to infrequent large streamflow events. Discontinuous ephemeral streams appear to be constantly changing as they alternate between two primary modes of operation; either aggradation or degradation may become dominant. Attainment of equilibrium conditions is brief. Disequilibrium is promoted by channel entrenchment that causes the fall of local base level, and by deposition of channel fans that causes the rise of local base level. These opposing base-level processes in adjacent reaches are maintained by self-enhancing feedback mechanisms. The threshold between erosion and deposition is crossed when aggradational or degradational reaches shift upstream or downstream. Extension of entrenched reaches into channel fans tends to create continuous arroyos. Upvalley migration of fan apexes tends to create depositional valley floors with few stream channels. Less than 100 years is required for arroyo cutting, but more than 500 years is required for complete aggradation of entrenched stream channels and valley floors. Discontinuous ephemeral streams have a repetitive sequence of streamflow characteristics that is as distinctive as sequences of meander bends or braided gravel bars in perennial rivers. The sequence changes from degradation to aggradation — headcuts concentrate sheetflow, a single trunk channel conveys flow to the apex of a channel fan, braided distributary channels end in an area of diverging sheetflow, and converging sheetflow drains to headcuts. The sequence is repeated at intervals ranging from 15 m for small streams to more than 10 km for large streams. Lithologic controls on the response of discontinuous ephemeral streams include: (1

  15. Rainfall-runoff modelling and palaeoflood hydrology applied to reconstruct centennial scale records of flooding and aquifer recharge in ungauged ephemeral rivers

    Directory of Open Access Journals (Sweden)

    G. Benito

    2011-04-01

    Full Text Available In this study we propose a multi-source data approach for quantifying long-term flooding and aquifer recharge in ungauged ephemeral rivers. The methodology is applied to the Buffels River, at 9000 km2 the largest ephemeral river in Namaqualand (NW South Africa, a region with scarce stream flow records limiting research investigating hydrological response to global change. Daily discharge and annual flood series (1965–2006 were estimated from a distributed rainfall-runoff hydrological model (TETIS using rainfall gauge records located within the catchment. The model was calibrated and validated with data collected during a two year monitoring programme (2005–2006 at two stream flow stations, one each in the upper and lower reaches of the catchment. In addition to the modelled flow records, non-systematic flood data were reconstructed using both sedimentary and documentary evidence. The palaeoflood record identified at least 25 large floods during the last 700 yr; with the largest floods reaching a minimum discharge of 255 m3 s−1 (450 yr return period in the upper basin, and 510 m3 s−1 (100 yr return period in the lower catchment. Since AD 1925, the flood hydrology of the Buffels River has been characterised by a decrease in the magnitude and frequency of extreme floods, with palaeoflood discharges (period 1500–1921 five times greater than the largest modelled floods during the period 1965–2006. Large floods generated the highest hydrograph volumes, however their contribution to aquifer recharge is limited as this depends on other factors such as flood duration and storage capacity of the unsaturated zone prior to the flood. Floods having average return intervals of 5–10 yr (120–140 m3 s−1 and flowing for 12 days are able to fully saturate the Spektakel aquifer in the lower Buffels River basin. Alluvial aquifer storage capacity limiting potential recharge

  16. On the effects of improved cross-section representation in one-dimensional flow routing models applied to ephemeral rivers

    Science.gov (United States)

    Hutton, Christopher J.; Brazier, Richard E.; Nicholas, Andrew P.; Nearing, Mark

    2012-04-01

    Flash floods are an important component of the semiarid hydrological cycle, and provide the potential for groundwater recharge as well as posing a dangerous natural hazard. A number of catchment models have been applied to flash flood prediction; however, in general they perform poorly. This study has investigated whether the incorporation of light detection and ranging (lidar) derived data into the structure of a 1-D flow routing model can improve the prediction of flash floods in ephemeral channels. Two versions of this model, one based on an existing trapezoidal representation of cross-section morphology (K-Tr), and one that uses lidar data (K-Li) were applied to 5 discrete runoff events measured at two locations on the main channel of The Walnut Gulch Experimental Watershed, United States. In general, K-Li showed improved performance in comparison to K-Tr, both when each model was calibrated to individual events and during an evaluation phase when the models (and parameter sets) were applied across events. Sensitivity analysis identified that the K-Li model also had more consistency in behavioral parameter sets across runoff events. In contrast, parameter interaction within K-Tr resulted in poorly constrained behavioral parameter sets across the multidimensional parameter space. These results, revealed with a modeling focus on the structure of a particular element of a distributed catchment model, suggest that lidar derived cross-section morphology can lead to improved, and more robust flash flood prediction.

  17. Stable isotope content of South African river water

    International Nuclear Information System (INIS)

    Variations of the isotopic ratios 18O/16O and D/H in natural waters reflect the variety of processes to which the water was subjected within the hydrological cycle. Time series of the 18O content of the major South African rivers over a few years have been obtained in order to characterise the main features of these variations in both time and space. Regionally the average '18O content of river water reflects that of the prevailing rains within the catchment. 18O variations with time are mainly correlated with river flow rates. Impoundments upstream and management of river flows reduce this correlation. Isotope variations along the course of a river show the effects of inflow from smaller streams and evaporation in the river or its impoundments. These observations indicate the use of isotopic methods to study the evaporation and mixing of river water and its interaction with the surrounding environment

  18. Geochemical data as indicators of environmental change and human impact in sediments derived from downstream marshes of an ephemeral river, Northeast China

    Science.gov (United States)

    Wang, Guo-Ping; Zhai, Zheng-Li

    2008-01-01

    Recent sedimentary history of natural environmental change and anthropogenic influence in an ephemeral river catchment has been reconstructed using selected major and trace elements, element ratios, and their different geochemical phases ( Tessier sequential extraction methods), pollen, and grain size combined with 210Pb- and 137Cs-dating method in marsh sedimentary cores. Attempts were made to use selected element ratios with different geochemical phases—residual phase of Ti, Al, V, Cr, Ni, Rb, K, Sr, and Ba; mobile Sr and Ba—combined with 210Pb- and 137Cs-chronology to interpret certain time information of environmental changes saved within the marsh sediments. Results indicate that there were two marked humid periods during 1850-1860 ad and 1890-1920 ad, and sand storm activities prevailed during 1920-1930 ad. After about 1900 ad, soil erosion has increased with the extensive agricultural activities in the Huolin River catchments, and further intensified after 1950s. After 1980, soil erosion has become even more intense, which is consistent with the reinforcement of human activities, the drastic loss of vegetation cover in the upstream lands, especially, the exploitation of the open cast coalmine in the upstream of Huolin River at that time. Influenced by the inundation of the Huolin River, the heavy metal pollution historical trends in Xianghai marsh wetland could be roughly divided into three periods by analysis of sediment enrichment factor (KSEF) and the index of geoaccumulation ( I geo):1760-1880 ad, 1880-1980 ad, and 1980-now. Human activities accelerate the inputs of heavy metal, which leads to degradation of the marsh. This study also investigated on source of marsh sediments (by Ti/Al), redox condition [by V/Cr and V/(V + Ni)], and salinization indicators (by Sr/Ba and Rb/K). The results demonstrate that sources of sediments and redox conditions were partly similar for both riparian and depressional marshes. Besides, some differences in degree of

  19. MULTI-TEMPORAL LAND USE ANALYSIS OF AN EPHEMERAL RIVER AREA USING AN ARTIFICIAL NEURAL NETWORK APPROACH ON LANDSAT IMAGERY

    Directory of Open Access Journals (Sweden)

    M. Aquilino

    2014-01-01

    The historical archive of LANDSAT imagery dating back to the launch of ERTS in 1972 provides a comprehensive and permanent data source for tracking change on the planet‟s land surface. In this study case the imagery acquisition dates of 1987, 2002 and 2011 were selected to cover a time trend of 24 years. Land cover categories were based on classes outlined by the Curve Number method with the aim of characterizing land use according to the level of surface imperviousness. After comparing two land use classification methods, i.e. Maximum Likelihood Classifier (MLC and Multi-Layer Perceptron (MLP neural network, the Artificial Neural Networks (ANN approach was found the best reliable and efficient method in the absence of ground reference data. The ANN approach has a distinct advantage over statistical classification methods in that it is non-parametric and requires little or no a priori knowledge on the distribution model of input data. The results quantify land cover change patterns in the river basin area under study and demonstrate the potential of multitemporal LANDSAT data to provide an accurate and cost-effective means to map and analyse land cover changes over time that can be used as input in land management and policy decision-making.

  20. Abundance and Distribution of African Fish Eagles along Major Rivers in Gonarezhou National Park, Zimbabwe

    NARCIS (Netherlands)

    Zisadza-Gandiwa, P.; Chiganze, S.; Chirombe, P.; Mashapa, C.; Muboko, N.; Gandiwa, E.

    2013-01-01

    African fish eagles (Haliaeetus vocifer) are important birds of prey and indicator of ecosystem integrity in aquatic environments. We assessed the population abundance and spatial distribution of African fish eagles along three major rivers in Gonarezhou National Park, Zimbabwe. Data were collected

  1. Ephemeral stream reaches preserve the evolutionary and distributional history of threespine stickleback in the Santa Clara and Ventura River watersheds of southern California

    Science.gov (United States)

    Richmond, Jonathan Q.; Jacobs, David K.; Backlin, Adam R.; Swift, Camm C.; Dellith, Chris; Fisher, Robert N.

    2015-01-01

    Much remains to be understood about the evolutionary history and contemporary landscape genetics of unarmored threespine stickleback in southern California, where populations collectively referred to as Gasterosteus aculeatus williamsoni have severely declined over the past 70+ years and are now endangered. We used mitochondrial sequence and microsatellite data to assess the population genetics and phylogeography of unarmored populations sampled immediately downstream from the type locality of G. a. williamsoni in the upper Santa Clara River, and assessed their distinctiveness with respect to low-armor populations in the downstream sections of the river and the adjacent Ventura River. We also characterized the geographic limits of different plate morphs and evaluated the congruence of those boundaries with barriers to dispersal in both river systems and to neutral genetic variation. We show substantial population structuring within the upper reach of the Santa Clara River, but little partitioning between the lower Santa Clara and Ventura Rivers—we attribute these patterns to different ancestry between spatially subdivided populations within the same drainage, a predominance of downstream gene flow, and ability for coastal dispersal between the Santa Clara and Ventura Rivers. We also show that alleles from introduced low-plate stock have infiltrated a native population in at least one upper Santa Clara River tributary, causing this formerly unarmored population to become gradually low-plated over a 30 + year time period. Measures of genetic diversity, census surveys, and severe habitat disturbance all indicate that unarmored stickleback near the type locality are currently at high risk of extinction.

  2. In situ measurements of microbially-catalyzed nitrification and nitrate reduction rates in an ephemeral drainage channel receiving water from coalbed natural gas discharge, Powder River Basin, Wyoming, USA

    Science.gov (United States)

    Harris, S.H.; Smith, R.L.

    2009-01-01

    Nitrification and nitrate reduction were examined in an ephemeral drainage channel receiving discharge from coalbed natural gas (CBNG) production wells in the Powder River Basin, Wyoming. CBNG co-produced water typically contains dissolved inorganic nitrogen (DIN), primarily as ammonium. In this study, a substantial portion of discharged ammonium was oxidized within 50??m of downstream transport, but speciation was markedly influenced by diel fluctuations in dissolved oxygen (> 300????M). After 300??m of transport, 60% of the initial DIN load had been removed. The effect of benthic nitrogen-cycling processes on stream water chemistry was assessed at 2 locations within the stream channel using acrylic chambers to conduct short-term (2-6??h), in-stream incubations. The highest ambient DIN removal rates (2103????mol N m- 2 h- 1) were found at a location where ammonium concentrations > 350????M. This occurred during light incubations when oxygen concentrations were highest. Nitrification was occurring at the site, however, net accumulation of nitrate and nitrite accounted for nitrification was not a factor and changes in DIN removal rates were controlled by nitrate reduction, diel fluctuations in oxygen concentration, and availability of electron donor. This study indicates that short-term adaptation of stream channel processes can be effective for removing CBNG DIN loads given sufficient travel distances, but the long-term potential for nitrogen remobilization and nitrogen saturation remain to be determined.

  3. African Models for Transnational River Basin Organisations in Africa: An Unexplored Dimension

    OpenAIRE

    Merrey, Douglas.J

    2009-01-01

    One of the many legacies of colonialism in Africa is the multiplicity of river basins shared by two or more – and often far more – countries. Since changing national boundaries is not an option, African governments have no choice but to develop transnational institutions for developing shared water resources. Therefore, one finds a plethora of bilateral and multilateral committees, commissions, and authorities intended to facilitate agreements for infrastructural investments, management of wa...

  4. Hydroclimatogical Changes and Impacts on Seasonal Regimes of African Equatorial Rivers

    Science.gov (United States)

    Mahe, G. M.

    2015-12-01

    In recent decades, changes in the pattern of hydroclimatogical cycle have been observed with impacts on seasonal regimes of African equatorial rivers. This communication reports on studies carried out for a set of river basins in equatorial Africa, tributaries of the Atlantic Gulf of Guinea: the Ogooue River in Gabon, the Kouilou River in Congo, and the basins of South Cameroon. These rivers are compared to the Congo River. A new monthly gridded rainfall dataset, and streamflow from selected rivers where used in the analysis. The observed changes include changes in seasonal pattern of rainfall and changes in monthly streamflow regimes. The study shows a decrease of rainfall in the southern hemisphere during February to May since the end of the 80s, while the decrease is much more limited in the Northern hemisphere. For the equatorial rivers, the March-June flood decreased steadily between the 70s and 80s, in correlation with a slight decrease of the rainfall between March and June, while the October-December flood showed no change. This trend was confirmed during the 2000s for the Ogooue River from updated times series, including a shift of the maximum in April instead of May. Locally, the dry season (July-September) disappeared on the coastal basin of the Kienke River at Kribi in Cameroon. It seems that these two months of July and August have become part of a 'single' large rainy season instead of separating the former two rainy seasons. A slight decrease in seasonal rainfall together with a small change in the intra-seasonal rainfall distribution, most probably led to one of the biggest change in hydrological regimes in Equatorial Africa, which could be a clue to understanding climate change in the region. This rainfall change is different for the Congo River which large basins integrates various climatic forcings.

  5. African Models for Transnational River Basin Organisations in Africa: An Unexplored Dimension

    Directory of Open Access Journals (Sweden)

    Douglas J. Merrey

    2009-06-01

    Full Text Available One of the many legacies of colonialism in Africa is the multiplicity of river basins shared by two or more – and often far more – countries. Since changing national boundaries is not an option, African governments have no choice but to develop transnational institutions for developing shared water resources. Therefore, one finds a plethora of bilateral and multilateral committees, commissions, and authorities intended to facilitate agreements for infrastructural investments, management of water flows (quantity and quality, and response to disasters, especially floods. These efforts are supported by – indeed often, at least behind the scenes, driven by – western and international development partners. With few exceptions, the results to date are not impressive, as governments drag their feet on ratifying or implementing agreements and investing in creating the necessary institutional infrastructure, and donors’ funds go unspent because such agreements are conditions precedent for investment. Despite the work done by many international and local non-government organisations (NGOs as well as some governments, hardly any of the residents of African river basins are aware of these commissions. All of them are based on organisational models derived from western experiences and governing principles and are created by inter-governmental agreements. The citizens residing in the basin are rarely consulted. In some cases, powerful national hydraulic bureaucracies seek to control the process in an effort to gain leverage over infrastructural investments. There is a body of literature seeking to explain the ineffectiveness of transnational river basin management to date, largely based on political science, sociology and economics. Some but not all observers are concerned with the degree of democracy in the political process. This paper addresses a dimension that has received very little attention and therefore complements the existing literature

  6. Ephemeral China/Handmade China

    Directory of Open Access Journals (Sweden)

    Xing Ruan

    2014-07-01

    Full Text Available A China that is in a frenzied state of economic boom and potential social instability, which is most vividly represented in its architectural and urban developments, is, I hope I will convince you, ephemeral. A quite different China, perhaps is not so visible as its new buildings and cities, is metaphorically ‘handmade’. I should like to extend the meanings of the handmade to the more stable and long lasting attitudes towards social life, and even mortality. My sources for the second China are partially from literature (not from architecture. With the construction boom since the mid-1990s, mainstream Western architectural journals and galleries have been racing to expose new architecture in China; celebrity Western architects have been winning major commissions in China: the 2008 Beijing Olympic Games is a case in point. The sheer quantity and speed of China’s development, as evidenced in architecture and urbanisation, causes an ‘unbearable lightness of being’ (to paraphrase Milan Kundera. Does all this then suggest that China, as solidified in its buildings and cities, is no longer ‘handmade’ in the sense that memory and a sense of history are redundant (particularly for a country that has a recorded history of more than 5000 years, which have been so lovingly recorded in handmade artefacts? The true meaning of the handmade, which absorbs labour — an ‘honourable labour’ as Joseph Conrad lovingly put it in his Mirror of the Sea, as well as memory, like that of a home, is a static artefact, which harbours our changing emotion, the frailties of human life, and indeed, the growing awareness that comes with time of our mortality: the handmade offers the necessary enshrinement of life’s vulnerability. Let me assure you, the seemingly fast-changing China, as represented in its new architecture and city forms, as well in its frenzied urbanisation and booming economy, is but a smoke screen. It is, in other words, ephemeral. The

  7. EphCOM: Practical Ephemeral Communications (How to implement ephemeral data with only primary Internet services)

    CERN Document Server

    Project, The Ephemeral Data

    2010-01-01

    The Internet never forgets and data lingers virtually forever. Private data created by users is frequently disseminated around the Internet and users often lose the control and ownership of their contents. This increasing diffusion of private data over the Internet motivates the need for ephemeral data, i.e. time-bounded data that cannot be accessed after a userspecified expiration time. This paper explores and formalizes the concept of Ephemeral Data Systems, systems that prevent an adversary from accessing expired contents. We present EphCOM, a practical Ephemeral Data System that supports ephemeral data using only a primary Internet service, namely the Domain Name Service (DNS). Our proposal leverages DNS servers caching mechanisms. EphCOM does not rely on any Trusted Platform Modules (TPM), peer-to-peer networks, or centralized servers, and is transparent to existing applications and services. It allows users to closely control data lifetime. We analyze its security and show, through extensive and large-s...

  8. MODELING EPHEMERAL GULLY EROSION FOR CONSERVATION PLANNING

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper discusses the overland flow and concentrated flow systems that occur in most farm fields. Concentrated flow areas, which are distinct from overland flow areas, can be a major sediment source and are the main conduits that convey runoff and sediment from most farm fields. Ephemeral gully erosion, which occurs in concentrated flow areas, is similar to but differs from both rill and classical gully erosion. Concentrated flow areas occupy much of the flow path between the end of overland flow areas and defined stream channels. This paper describes the erosion and deposition processes that occur in concentrated flow areas and the effect of soil and cover management on these processes. Ephemeral gully erosion is not estimated with rill-interrill erosion prediction methods, which can result in major errors in estimates of sediment yield leaving farm fields. Much deposition can occur in concentrated flow areas resulting in sediment load leaving a farm field being much less than the sediment produced by rill-interrill and ephemeral gully erosion within the field. This paper describes model structure, topographic representation, and features of ephemeral gully erosion control practices needed in mathematical models used in conservation planning for farm fields.

  9. Tools for Ephemeral Gully Erosion Process Research

    Science.gov (United States)

    Techniques to quantify ephemeral gully erosion have been identified by USDA Natural Resources Conservation Service (NRCS) as one of gaps in current erosion assessment tools. One reason that may have contributed to this technology gap is the difficulty to quantify changes in channel geometry to asses...

  10. Nutrients, trace metals and B-vitamin composition of the Moulouya River: A major North African river discharging into the Mediterranean Sea

    Science.gov (United States)

    Tovar-Sánchez, Antonio; Basterretxea, Gotzon; Ben Omar, Mostapha; Jordi, Antoni; Sánchez-Quiles, David; Makhani, Mardjan; Mouna, Daoudi; Muya, Cedrick; Anglès, Silvia

    2016-07-01

    We analyzed dissolved nutrient, trace metal and vitamin (B-vitamins and methionine) concentrations in the lower course of the Moulouya River (MR, Morocco) and its estuary. The flow of this African river has changed drastically (a reduction of almost 50%) in the last 50 years due to the regulation of the river flow through dams and alterations of the course constructed to satisfy population necessities and growing agricultural requirements. Consequently, it has produced a remarkable increase in nitrate concentrations (up to 270 μM) and alteration of N:P ratios within the river, as well as a reduction of overall P and Si efflux to nearby coastal waters. Despite the historical mining activities in the upper MR, concentrations of Pb, Zn and other metals in sediments and waters do not display significant contamination as compared with other Mediterranean rivers, mainly due to the retention by dams of upstream metal contamination. Mean concentrations of dissolved B-vitamins in the river showed lower levels (13-55% lower) than those in coastal waters and hence the river does not represent an important B-vitamin source.

  11. Physicochemical characteristics of organic honey samples of africanized honeybees from Parana River islands

    Directory of Open Access Journals (Sweden)

    Eloi Machado Alves

    2011-09-01

    Full Text Available This research was carried out to evaluate the physicochemical composition of organic honey in Paraná River islands, in Porto Brasílio, State of Paraná. Honey was harvested directly from super of the colonies in three apiaries spread in the Floresta and Laranjeira Islands, from August 2005 to August 2006. Twenty-four samples of organic honey produced by Africanized honeybees were evaluated. The following parameters were analyzed: pH, acidity, formol index, hydroxymethylfurfural, ashes, color, electric conductivity and moisture. Three replications per sample were performed for laboratorial analysis, giving the means and standard deviation. Most honey samples were in conformity with the Normative Instruction 11 from October 20, 2000. However, 4.17% were not in accordance with the moisture standards, 8.33% showed high concentrations of hydroxymethylfurfural, thus, totalizing 12.50% of non-complying samples. Nevertheless, 87.50% of the analyzed honey samples are within the standards, being characterized as an organic product of excellent quality, with good commercialization perspectives in the market.

  12. OREN: Optimal Revocations in Ephemeral Networks

    OpenAIRE

    Bilogrevic, Igor; Manshaei, Mohammadhossein; Raya, Maxime; Hubaux, Jean-Pierre

    2011-01-01

    Public-key certificates allow a multitude of entities to securely exchange and verify the authenticity of data. However, the ability to effectively revoke compromised or untrustworthy certificates is of great importance when coping with misbehavior. In this paper, we design a fully distributed local certificate revocation scheme for ephemeral networks - a class of extremely volatile wireless networks with short-duration and short-range communications - based on a game-theoretic approach. Firs...

  13. Vegetation Structure and Function along Ephemeral Streams in the Sonoran Desert

    Science.gov (United States)

    Stromberg, J. C.; Katz, G.

    2011-12-01

    Despite being the most prevalent stream type in the American Southwest, far less is known about riparian ecosystems associated with ephemeral streams than with perennial streams. Patterns of plant composition and structure reflect complex environmental gradients, including water availability and flood intensity, which in turn are related to position in the stream network. A survey of washes in the Sonoran Desert near Tucson, Arizona showed species composition of small ephemeral washes to be comprised largely of upland species, including large seeded shrubs such as Acacia spp. and Larrea tridentata. Small seeded disturbance adapted xerophytic shrubs, such as Baccharis sarothroides, Hymenoclea monogyra and Isocoma tenuisecta, were common lower in the stream network on the larger streams that have greater scouring forces. Because ephemeral streams have multiple water sources, including deep (sometimes perched) water tables and seasonally variable rain and flood pulses, multiple plant functional types co-exist within a stream segment. Deep-rooted phreatophytes, including Tamarix and nitrogen-fixing Prosopis, are common on many washes. Such plants are able to access not only water, but also pools of nutrients, several meters below ground thereby affecting nutrient levels and soil moisture content in various soil strata. In addition to the perennial plants, many opportunistic and shallow-rooted annual species establish during the bimodal wet seasons. Collectively, wash vegetation serves to stabilize channel substrates and promote accumulation of fine sediments and organic matter. In addition to the many streams that are ephemeral over their length, ephemeral reaches also occupy extensive sections of interrupted perennial rivers. The differences in hydrologic conditions that occur over the length of interrupted perennial rivers influence plant species diversity and variability through time. In one study of three interrupted perennial rivers, patterns of herbaceous species

  14. Use of Landscape-level River Signatures in Conservation Planning: a South African Case Study

    Directory of Open Access Journals (Sweden)

    Jim Cambray

    2002-12-01

    Full Text Available A strategy for assigning priorities in biodiversity conservation was developed for the rivers of the proposed Greater Addo Elephant National Park (GAENP in South Africa. Due to the limited availability of biological information on the freshwater ecosystems of this area, a desktop approach, supplemented by aerial and land surveys, was used to devise a new river classification typology. This typology incorporated landscape attributes as surrogates for biodiversity patterns, resulting in defined physical "signatures" for each river type. Riverine biodiversity is considered to be conserved by including rivers of each type as defined by the respective signatures. Where options existed, and two or more rivers shared the same signature, a simple procedure was used to assign priorities to "similar" rivers for conservation. This procedure considered the extent of transformation, degree of inclusion within the park, irreplaceability or uniqueness, and geomorphological diversity of each river. The outcome of the study was that 18 of the 31 rivers within the GAENP must be conserved to achieve representation of all of the biodiversity patterns identified. It is concluded that, given further development and testing, the river signature concept holds promise for elevating the river focus in general conservation planning exercises.

  15. The role of North African rivers in driving Mediterranean-Atlantic exchange

    Science.gov (United States)

    Flecker, Rachel; Marzocchi, Alice; van der Schee, Marlies; Meijer, Paul; Lofi, Johanna; Lunt, Dan

    2014-05-01

    The main driver for exchange through the Gibraltar Strait today is the density contrast between Mediterranean and Atlantic water. Mediterranean water is more saline than Atlantic water because the amount of water the Mediterranean loses through evaporation exceeds both precipitation and freshwater input from rivers. This means it has a negative hydrologic budget. In the Late Miocene however, a very large river known as the Esohabi River drained across North Africa and had its mouth in the Gulf of Sirt. This river was sourced in palaeo-Lake Chad and was strongly influenced by precession-driven monsoonal rainfall. Multiple General Circulation Model simulations through a single precessional cycle indicate that river water may only have reached the Mediterranean in significant quantities in summer during particular orbital configurations e.g. precession minima combined with eccentricity maxima. However, during high amplitude eccentricity maxima, the volume of water supplied through the Esohabi and Nile rivers may have been sufficient to switch the hydrologic budget from negative to positive. In doing so, the fresh water supply should have reduced the salinity of the Mediterranean and consequently the density contrast with adjacent Atlantic water leading to a reduction in exchange. In this presentation we explore the evidence for the timing and nature of freshwater input to the Mediterranean from North Africa. We also consider how relevant this freshwater flux may be in determining some of the major environmental and sedimentological changes in the Late Miocene to early Pliocene including some of the salinity changes that occurred during the Messinian Salinity Crisis.

  16. 'Beyond the rivers of Ethiopia' : Pentecostal Pan-Africanism and Ghanaian identities in the transnational domain

    NARCIS (Netherlands)

    Dijk, van R.A.; Binsbergen, van W.M.J.; Dijk, van R.A.; Gewald, J.B.

    2004-01-01

    Rev. Mensa Otabil, the founder of the International Central Gospel Church in Accra, is considered an influential representative of a new Pentecostal-inspired Pan-Africanist ideology. His book 'Beyond the Rivers of Ethiopia' lays the foundations of a Pentecostal Liberation Theology that proclaims a C

  17. Accentuating River Border Conflicts and Water Privatization:The Southern African Development Community

    Science.gov (United States)

    Al-Essawi, Mohammed H. K.; Ntuli, Elijah M.

    The Southern African Development Community (SADC) is an international organization that has been in existence since 1980. Previously known as the Southern African Development Coordination Conference (SADCC), its primary aim was to coordinate development projects in order to lessen economic dependence on the then apartheid South Africa. Over the years, the coordination of such developmental projects has increasingly demanded a collective utilization of resources, such as energy, health and water sectors, among others. However, national boarders have also been pivotal in not only conflict management aspects, but also as protocolly agreed-upon component defining SADC`s contemporary international relations and legal regime. In the context of the accessibility and insufficiency of resources, our findings show that water as a resource has not only sparked inter-boarder issues, but also internal resistance from non-governmental organizations and major labor organizations in the SADC region. Policy formulation and implementation (under the international law umbrella) remain a greatest challenge in addressing the pressing issues of water privatization through political means.

  18. Linking biochemical perturbations in tissues of the African catfish to the presence of polycyclic aromatic hydrocarbons in Ovia River, Niger Delta region

    International Nuclear Information System (INIS)

    Petroleum hydrocarbons including polycyclic aromatic hydrocarbons (PAHs) are a pollution issue in the Niger Delta region due to oil industry activities. PAHs were measured in the water column of the Ovia River with concentrations ranging from 0.1 to 1055.6 ng L−1. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy detected alterations in tissues of the African catfish (Heterobranchus bidorsalis) from the region showed varying degrees of statistically significant (P < 0.0001, P < 0.001, P < 0.05) changes to absorption band areas and shifts in centroid positions of peaks. Alteration patterns were similar to those induced by benzo[a]pyrene in MCF-7 cells. These findings have potential health implications for resident local communities as H. bidorsalis constitutes a key nutritional source. The study provides supporting evidence for the sensitivity of infrared spectroscopy in environmental studies and supports their potential application in biomonitoring. - Highlights: • PAHs measured in the water column of the Ovia River (Nigeria). • ATR-FTIR spectroscopy detects alterations in tissues of the African catfish (Heterobranchus bidorsalis). • Spectral alteration similar to those induced by benzo[a]pyrene in MCF-7 cells. • Alterations in tissues of African catfish (H. bidorsalis) a function of exposure to waterborne PAHs. • Vibrational spectroscopy techniques detect minimal changes induced by environmental exposures. - Spatial and temporal analyses by biospectroscopy techniques of African catfish (Heterobranchus bidorsalis) tissues suggest that detected alterations can reflect fluctuating exposures to PAHs

  19. LOW-ALTITUDE DIGITAL PHOTOGRAMMETRY TECHNIQUE TO ASSESS EPHEMERAL GULLY EROSION

    Science.gov (United States)

    Ephemeral gully erosion is the main source of sediment from the agricultural landscape, unfortunately, it has been overlooked in traditional soil erosion assessment. Since an ephemeral gully can be easily alleviated or filled by normal tillage, the difficulty in making the ephemeral gully erosion a...

  20. Microbial flora in organic honey samples of africanized honeybees from Parana river islands

    Directory of Open Access Journals (Sweden)

    Maria Josiane Sereia

    2011-06-01

    Full Text Available The purpose of this study was to verify and compare the main contamination sources and the hygienic/sanitary conditions of organic honey samples of Apis mellifera from Parana River islands. Thirty-three (33 samples were analyzed between January 2005 and August 2006. Eleven (11 samples were collected by beekeepers and twenty-two (22 samples were collected and processed in accordance with ideal personal hygiene norms and good manufacturing practices. The samples underwent microbiological analysis in search of coliforms at 35 ºC and 45 ºC, as well as fungi enumeration analysis. As for fungi counting, the samples harvested by beekeepers showed values above the maximum established by Resolution nº 15/94 of Common Market Group - Mercosul. The results showed that secondary contamination sources are responsible for the reduction of organic honey quality.

  1. GridFactory - Distributed computing on ephemeral resources

    DEFF Research Database (Denmark)

    Orellana, Frederik; Niinimaki, Marko

    2011-01-01

    A novel batch system for high throughput computing is presented. The system is specifically designed to leverage virtualization and web technology to facilitate deployment on cloud and other ephemeral resources. In particular, it implements a security model suited for forming collaborations...

  2. Study on Freshwater Macroinvertebrates of Some Tanzanian Rivers as a Basis for Developing Biomonitoring Index for Assessing Pollution in Tropical African Regions

    Directory of Open Access Journals (Sweden)

    Julius D. Elias

    2014-01-01

    Full Text Available Macroinvertebrates and physicochemical parameters were assessed at 15 sites along five rivers in Kilimanjaro region, Tanzania, with the aim of understanding their ecological status and setting a base to the development of a biological index for tropical regions. Investigated rivers that occur within Pangani basin include Karanga, Rau, Lumbanga, Sere, and Umbwe. Sampling sites were categorized according to the level of water and habitat quality as follows: reference or least impacted (4 sites, moderately impacted (5 sites, and highly impacted (6 sites sites. A total of 12,527 macroinvertebrates belonging to 13 orders and 48 families were recorded. The highest total abundance of 4,110 individuals per m2 was found in Karanga river, while Umbwe river had the lowest with 1,203 individuals per m2. Chironomidae was the most abundant family (2,588 individuals per m2 and the least were Hydridae and Thiaridae, each having 5 individuals per m2. High numbers of taxa were noted among the orders: Ephemeroptera (8, Odonata (8, Diptera (7, and Trichoptera (6. In conclusion, orders with greater diversity of macroinvertebrate families offer a wide range of tolerance to pollution and, thus can potentially be used to develop a biomonitoring index for evaluating pollution in tropical African rivers.

  3. Models of invasion and establishment of African Mustard (Brassica tournefortii)

    Science.gov (United States)

    Berry, Kristin H.; Gowan, Timothy A.; Miller, David M.; Brooks, Matthew L.

    2015-01-01

    Introduced exotic plants can drive ecosystem change. We studied invasion and establishment ofBrassica tournefortii (African mustard), a noxious weed, in the Chemehuevi Valley, western Sonoran Desert, California. We used long-term data sets of photographs, transects for biomass of annual plants, and densities of African mustard collected at irregular intervals between 1979 and 2009. We suggest that African mustard may have been present in low numbers along the main route of travel, a highway, in the late 1970s; invaded the valley along a major axial valley ephemeral stream channel and the highway; and by 2009, colonized 22 km into the eastern part of the valley. We developed predictive models for invasibility and establishment of African mustard. Both during the initial invasion and after establishment, significant predictor variables of African mustard densities were surficial geology, proximity to the highway and axial valley ephemeral stream channel, and number of small ephemeral stream channels. The axial valley ephemeral stream channel was the most vulnerable of the variables to invasions. Overall, African mustard rapidly colonized and quickly became established in naturally disturbed areas, such as stream channels, where geological surfaces were young and soils were weakly developed. Older geological surfaces (e.g., desert pavements with soils 140,000 to 300,000 years old) were less vulnerable. Microhabitats also influenced densities of African mustard, with densities higher under shrubs than in the interspaces. As African mustard became established, the proportional biomass of native winter annual plants declined. Early control is important because African mustard can colonize and become well established across a valley in 20 yr.

  4. The Topos of the Ephemeral in the Ancient Greek Tragedy

    Directory of Open Access Journals (Sweden)

    Ioana PETCU

    2010-12-01

    Full Text Available Fragment of the human condition, the ephemeral which lives within us. Trying to see how much the ephemeral ‘topos’ can be transfered to the performance level, particularly in the staging of the ancient tragedy. An intrusion in the history of this cause gives us the possibility to review in raccourcis its multiple semnifications. The second part of the article draws Hecuba’s portrait into a double mirror, the story of the Troy queen represents the myth of unstable happiness of the ancient world. Ambivalent picture of the character-ephemeris is built between the text of Euripides and modern perfomances on the stages of English, American, Australian and Romanian theatres.We also analyzed a few texts less approached from the directorial point of view, one the one hand in order to nuance the ephemerality topos and, on the other hand, in order to let them out of their shadow corner. The Aeschylian writings, The Seven against Thebes, The Persians and Euripides’ two tragedies Phoenician Women and The Suppliants have been our fundament to discovering new valences of the perishable and to showing the way that this motif can take from reading to scenic practice.

  5. Spatial patterns of ephemeral plants in Gurbantünggüt Desert

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the present research, the authors measured parameters of richness, cover and importance value of ephemeral and ephemeroid plants on south-north and east-west transects in the Gurbantünggüt Desert in early spring, and investigated and analyzed the microhabitats, such as terrain, geomorphology, soil physical-chemical properties and crusts. By comparison, the regional differences in the ephemeral distribution in the desert were revealed. The species of ephemeral plants in the south and center are the richest and those in the west are the poorest in the desert. The cover of ephemeral plants in the mid-south is higher than that in the north, and that in the mid-east is higher than that in the west. The response of ephemeral plants to the spatial variation of the desert habitat forms the population-habitat gradient of ephemeral plants. The characteristics are: (1) In the habitat with higher terrain, coarser textured soil with poorer sorting and correspondingly higher organic matter and lower alkali-saline contents, Carex physoides and Eremopyrum orientale are the dominant ephemeral plants; (2) In the dry habitat with lower terrain, looser textured soil, some organic matter, alkali-saline soil, and developed crust, the ephemeral plants Alyssum linifolium and Erodium oxyrrhynchum are of characteristic of drought and alkali-saline tolerance; (3) In the habitat with lower terrain, some water and more alkali-saline soil, the ephemeral plants Neotorularia torulosa and Hypecoum parviflorum being of alkali-saline tolerance are mainly developed. However, most ephemerals are distributed in a habitat order of higher terrain, some organic, and less alkali-saline soil on the above-mentioned ephemeral population-habitat gradient. The spatial gradient of variation in desert microhabitats is small, and as a whole, the physiological character of mesophytism is represented by the desert ephemerals.

  6. Spring Ephemerals Adapt to Extremely High Light Conditions via an Unusual Stabilization of Photosystem II

    OpenAIRE

    Tu, Wenfeng; Li, Yang; Liu, Wu; Wu, Lishuan; Xie, Xiaoyan; Zhang, Yuanming; Wilhelm, Christian; Yang, Chunhong

    2016-01-01

    Ephemerals, widely distributed in the Gobi desert, have developed significant characteristics to sustain high photosynthetic efficiency under high light (HL) conditions. Since the light reaction is the basis for photosynthetic conversion of solar energy to chemical energy, the photosynthetic performances in thylakoid membrane of the spring ephemerals in response to HL were studied. Three plant species, namely two C3 spring ephemeral species of Cruciferae: Arabidopsis pumila (A. pumila) and Si...

  7. ModABa Model: Annual Flow Duration Curves Assessment in Ephemeral Basins

    Science.gov (United States)

    Pumo, Dario; Viola, Francesco; Noto, Leonardo V.

    2013-04-01

    A representation of the streamflow regime for a river basin is required for a variety of hydrological analyses and engineering applications, from the water resource allocation and utilization to the environmental flow management. The flow duration curve (FDC) represents a comprehensive signature of temporal runoff variability often used to synthesize catchment rainfall-runoff responses. Several models aimed to the theoretical reconstruction of the FDC have been recently developed under different approaches, and a relevant scientific knowledge specific to this topic has been already acquired. In this work, a new model for the probabilistic characterization of the daily streamflows in perennial and ephemeral catchments is introduced. The ModABa model (MODel for Annual flow duration curves assessment in intermittent BAsins) can be thought as a wide mosaic whose tesserae are frameworks, models or conceptual schemes separately developed in different recent studies. Such tesserae are harmoniously placed and interconnected, concurring together towards a unique final aim that is the reproduction of the FDC of daily streamflows in a river basin. Two separated periods within the year are firstly identified: a non-zero period, typically characterized by significant streamflows, and a dry period, that, in the cases of ephemeral basins, is the period typically characterized by absence of streamflow. The proportion of time the river is dry, providing an estimation of the probability of zero flow occurring, is empirically estimated. Then, an analysis concerning the non-zero period is performed, considering the streamflow disaggregated into a slow subsuperficial component and a fast superficial component. A recent analytical model is adopted to derive the non zero FDC relative to the subsuperficial component; this last is considered to be generated by the soil water excess over the field capacity in the permeable portion of the basin. The non zero FDC relative to the fast

  8. Recharge From an Ephemeral Stream Following Wetting Front Arrival to Water Table

    Science.gov (United States)

    Abdulrazzak, Mohamed J.; Morel-Seytoux, Hubert J.

    1983-02-01

    After the infiltration wetting front from a river bed of an ephemeral stream in flood reaches the shallow water table, the rate of recharge, which is also that of infiltration, is affected by the development of a groundwater mound. The effect is practically immediate if the water content behind the wetting front is close to saturation. An approximate analytical solution is developed in that case, which predicts the time dependence of the recharge rate. Comparison with experimental results in the laboratory shows that the solution is excellent in spite of the assumptions necessary in the derivations. As long as the ratio of river width over depth to water table exceeds 2 and as long as the ratio of initial saturated thickness over depth to the water table exceeds 2.5, the analytical solution is essentially exact. Under most field conditions these ratios are largely exceeded. Consequently, the predictive equation for the time dependence of the recharge is both quite simple to use and adequately accurate for field applications.

  9. Effects of Hysteresis on Groundwater Recharge From Ephemeral Flows

    Science.gov (United States)

    Parissopoulos, G. A.; Wheater, H. S.

    1992-11-01

    The effects of hysteresis on the movement of the saturated and unsaturated soil water phase due to infiltration from ephemeral surface water flows are investigated for different scenarios of flood events in homogeneous and heterogeneous media with the use of a two-dimensional model based on Richards' equation and the dependent domain hysteresis model of Mualem (1984). Hysteresis effects were found in general to be small, but sensitive to water ponding depth, hydraulic contact between surface and groundwater and initial moisture distribution. In all cases tested, hysteresis resulted in higher rise of the toe of the water mound formed beneath the wadi despite a decrease of cumulative infiltration.

  10. Timely crawling of high-quality ephemeral new content

    OpenAIRE

    Lefortier, Damien; Ostroumova, Liudmila; Samosvat, Egor; Serdyukov, Pavel

    2013-01-01

    Nowadays, more and more people use the Web as their primary source of up-to-date information. In this context, fast crawling and indexing of newly created Web pages has become crucial for search engines, especially because user traffic to a significant fraction of these new pages (like news, blog and forum posts) grows really quickly right after they appear, but lasts only for several days. In this paper, we study the problem of timely finding and crawling of such ephemeral new pages (in term...

  11. EVALUATION OF TOPOGRAPHIC INDICES FOR EPHEMERAL-GULLY EROSION ASSESSMENT

    Institute of Scientific and Technical Information of China (English)

    J. CASAL(I); L. M. De SANTISTEBAN; J. J. L(O)PEZ; J. V. GIRALDEZ; J. POESEN; J. NACHTERGAELE; M. GO(N)I; J. LOIZU; M. A. CAMPO

    2005-01-01

    Soil erosion by concentrated flows in agricultural areas is an important process affecting soil losses and landscape degradation. The main factors controlling concentrated flow erosion include the erodibility of materials, soil use and management, climate, and watershed topography. In this paper,two topographic indices, closely related with mathematical expressions suggested by different authors, are used to characterize the influence of watershed topography on gully erosion. The AS1 index is defined as the product of the watershed area and the partial area-weighted average slope.The AS2 index is the product of the watershed area and the length-weighted average swale slope.Using different ephemeral gully erosion databases, a high correlation was found between the topographic indices and the volume of eroded soil. The accuracy of different methods for field measurement of ephemeral gullies was evaluated to ensure that the relation between erosion and topographic indices is not affected by assessment errors. The resulting relation are useful to assess soil losses from gully erosion, to identify the most susceptible watersheds within large areas, and to compare the susceptibility to gully erosion among different catchments. This information also can be important to study the response of natural drainage network systems to different rainfall inputs.

  12. Distribution of ephemeral plants and their significance in dune stabilization in Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    WANGXueqin; JIANGJin; LEIJiaqiang; ZHANGWeimin; QIANYibing

    2003-01-01

    Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation,describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes,analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert.Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.

  13. Airborne laser profile data for measuring ephemeral gully erosion

    International Nuclear Information System (INIS)

    Soil erosion, which leads to a decrease in soil productivity and a degradation of water quality, is a major problem on at least one-third of our nation's cropland. Better information is needed on the extent and severity of erosion, especially information on ephemeral gully erosion was investigated. Laser profile data were obtained over control fields with both artificial and natural gullies and recorded at 4000 pulses per second at a nominal aircraft speed of 25 metres per second and altitudes of 50 and 100 metres. A moving average filter was used to remove random noise and surface micro roughness effects. Analysis of the data from the artificial and natural gully fields clearly indicated the location and cross section of gullies as small as 50 cm wide and 15 cm deep. These results demonstrated the feasibility of the approach because the tested conditions were what would be considered very small gullies

  14. The Permanence of Ephemeral: Tsoi Wall 23 years after

    Directory of Open Access Journals (Sweden)

    Oksana Zaporozhets

    2014-05-01

    Full Text Available It became an academic convention to refer to ephemerality and temporality of graffiti and street-art. However studying some places as shaped by and known for these urban visuals, it is possible to consider them as con- stant and ever-present element of a city. A case under analysis is the Tsoi Wall, people’s memorial appeared in Moscow in 1990. The paper discusses how this city site gains its right to exist in multitude of cultural practices, interactions, and meanings assigned. The article reveals the role of creative sites for Soviet and Post-Soviet cities and explores who and why has been maintaining and protecting the Tsoi Wall for almost two decades.

  15. Remote sensing of ephemeral water bodies in western Niger

    Science.gov (United States)

    Verdin, J.P.

    1996-01-01

    Research was undertaken to evaluate the feasibility of monitoring the small ephemeral water bodies of the Sahel with the 1.1 km resolution data of the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR). Twenty-one lakes of western Niger with good ground observation records were selected for examination. Thematic Mapper images from 1988 were first analysed to determine surface areas and temperature differences between water and adjacent land. Six AVHRR scenes from the 1988-89 dry season were then studied. It was found that a lake can be monitored until its surface area drops below 10 ha, in most cases. Furthermore, with prior knowledge of the location and shape of a water body, its surface area can be estimated from AVHRR band 5 data to within about 10 ha. These results are explained by the sharp temperature contrast between water and land, on the order of 13?? C.

  16. Molecular and biochemical studies on bovine ephemeral fever

    Directory of Open Access Journals (Sweden)

    Nahed S. Thabet; Emad W. Ghazy; Mohamed A. Nayel; Mohamed Abo-Elkhair

    2011-05-01

    Full Text Available Bovine ephemeral fever (BEF in cattle has been reported to be associated with a range of biochemical changes which are similar to those seen in milk fever. This study aimed to clarify the biochemical alterations that associate infection of cattle with BEF with special references to the mechanisms involved in the development of hypocalcemia. The study was conducted on 30 cases of cattle infected with BEF based on the characteristic clinical signs which were confirmed by isolation of virus and RT-PCR. Another 6 healthy cows were used in the study as control. The evaluated parameters included biochemical variables such as serum values of total protein (TP, albumin (Alb, glucose (Glu, total calcium (tCa, ionized calcium (iCa, inorganic phosphorus (P, magnesium (Mg, sodium (Na, potassium (K, chloride (Cl, creatinine (Cr, blood urea nitrogen (BUN and serum activity of alkaline phosphatase (ALP. Hormonal profile included parathyroid hormone (PTH, insulin (Ins, and cortisol (Cor. The results showed that BEF-infected animals demonstrated a significant decrease (P<0.05 in serum concentrations of TP, Glo, iCa, P, Na, K, BUN and ALP while the mean values of serum levels of Glu and Cl were significantly increased (P<0.05. The mean values of serum levels of PTH were significantly decreased (P<0.05 while serum concentrations of Ins and Cor showed a significant increase. It was concluded that the clinical signs of bovine ephemeral fever are related to the hypocalcemia resulting from suppression of parathyroid hormone which seems to be mediated by respiratory alkalosis caused by the disease. This explanation needs future studies to provide a direct link between measurement of blood indicators of acid-base status, blood biochemical parameters and urine analysis. However, this work can provide a good knowledge about the pathogenesis of the disease that can lead to better management and proper treatment.

  17. Fissurelike features in ephemeral channels, Trans-Pecos Texas

    International Nuclear Information System (INIS)

    Active and relict ephemeral channels in the Eagle Flat basin west of Van Horn contain abundant fissurelike features, which are being studied as part of the geologic characterization of a proposed site for the Texas low-level radioactive waste repository. Tensional cracks are absent in excavations of fissurelike features in Eagle Flat, so the term 'fissurelike' is used instead of 'fissure'. Fissurelike features in active channels are characterized by curvilinear patterns of holes, pipes, and collapse structures developed at the surface within silt and fine sand basin-fill sediments. Typical single depressions range from 20 to 40 cm in depth and 0.4 to 2 m in length and form clusters as much as 2,000 m in length. Relict channel deposits exhibit filled burrows and sandy crossbedded deposits. Linear fissurelike features, located in silts and clays at the surface, may have been the loci for shallow infiltration of surface waters, which caused dissolution and reprecipitation of calcic soils. Ground-water withdrawal, a cause of fissure development elsewhere in the southwest, is an unlikely origin for fissures at this location because pumpage from nearby wells is minimal. Fissurelike features, where excavated, are not underlain by tensional cracks. In addition, the features are located in low-gradient ephemeral channel areas, and are most abundant gown gradient from a railroad embankment where water ponds relatively frequently. Localized wetting and soil-collapse processes, rather than basinal-scale tensional stresses produced by ground-water withdrawal, may have caused most of the fissurelike features in northern Eagle Flat basin

  18. Biomarkers of Oxidative Stress and Heavy Metal Levels as Indicators of Environmental Pollution in African Cat Fish (Clarias gariepinus) from Nigeria Ogun River

    Science.gov (United States)

    Farombi, E. O.; Adelowo, O. A.; Ajimoko, Y. R.

    2007-01-01

    Levels of Zn, Cu, Cd, As, and Pb in the kidney, Liver, Gills and Heart of African cat fish (Clarias gariepinus) from the Ogun River in Ogun State located close to six major industries in the South Western part of Nigeria, were determined using Bulk Scientific Atomic Absorption Spectrophotometer. Fishes were also collected from Government owned fish farm in Agodi, Ibadan which was considered a reference site. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione (GSH) concentration and malondialdehyde (MDA) formation were also determined. The trend of accumulation of the metals in the organs is as follows: Heart - Zn > Cu > Pb > As > Cd; Gills - Zn > Cu > Pb > Cd > As; Kidney - Zn > Cu > Pb > As > Cd; Liver -Zn > Cu > Pb > As > Cd. The order of concentration of the metals in the organs is as follows: Arsenite - Kidney > Liver > Gills > Heart; Zinc - Gills > Liver > Kidney > Heart; Lead- Liver > Kidney > Gills > Heart; Copper- Kidney > Liver > Gills > Heart; Cadmium > Liver > Gills > Kidney > Heart. The levels of heavy metals ranged between 0.25–8.96 ppm in the heart, 0.69– 19.05 ppm in the kidneys, 2.10–19.75 ppm in the liver and 1.95–20.35 ppm in the gills. SOD activity increased by 61% in the liver, 50% in the kidney and in the heart by 28 % while a significant decrease (44%) was observed in the gill of Clarias gariepinus from Ogun river compared to that Agodi fish farm (P<0.001). On the contrary there was 46%, 41%, 50% and 19% decrease in CAT activity in the liver, kidney, gills and heart respectively. The levels of GST activities in the liver, kidney and heart of Clarias gariepinus from Ogun river increased by 62%, 72% and 37% respectively (P<0.001) whereas there was a significant decrease (41%) in the gills (P<0.05) compared to that from the Agodi fish farm. GSH concentration increased by 81%, 83% and 53% in the liver, kidney and heart respectively but decreased by 44% in the gills. MDA levels of

  19. Biomarkers of Oxidative Stress and Heavy Metal Levels as Indicators of Environmental Pollution in African Cat Fish (Clarias gariepinus from Nigeria Ogun River

    Directory of Open Access Journals (Sweden)

    Y. R. Ajimoko

    2007-06-01

    Full Text Available Levels of Zn, Cu, Cd, As, and Pb in the kidney, Liver, Gills and Heart of African cat fish (Clarias gariepinus from the Ogun River in Ogun State located close to six major industries in the South Western part of Nigeria, were determined using Bulk Scientific Atomic Absorption Spectrophotometer. Fishes were also collected from Government owned fish farm in Agodi, Ibadan which was considered a reference site. The activities of superoxide dismutase (SOD, catalase (CAT, glutathione S-transferase (GST, glutathione (GSH concentration and malondialdehyde (MDA formation were also determined. The trend of accumulation of the metals in the organs is as follows: Heart - Zn > Cu > Pb > As > Cd; Gills - Zn > Cu > Pb > Cd > As; Kidney - Zn > Cu > Pb > As > Cd; Liver -Zn > Cu > Pb > As > Cd. The order of concentration of the metals in the organs is as follows: Arsenite - Kidney > Liver > Gills > Heart; Zinc - Gills > Liver > Kidney > Heart; Lead- Liver > Kidney > Gills > Heart; Copper- Kidney > Liver > Gills > Heart; Cadmium > Liver > Gills > Kidney > Heart. The levels of heavy metals ranged between 0.25-8.96 ppm in the heart, 0.69- 19.05 ppm in the kidneys, 2.10-19.75 ppm in the liver and 1.95-20.35 ppm in the gills. SOD activity increased by 61% in the liver, 50% in the kidney and in the heart by 28 % while a significant decrease (44% was observed in the gill of Clarias gariepinus from Ogun river compared to that Agodi fish farm (P<0.001. On the contrary there was 46%, 41%, 50% and 19% decrease in CAT activity in the liver, kidney, gills and heart respectively. The levels of GST activities in the liver, kidney and heart of Clarias gariepinus from Ogun river increased by 62%, 72% and 37% respectively (P<0.001 whereas there was a significant decrease (41% in the gills (P<0.05 compared to that from the Agodi fish farm. GSH concentration increased by 81%, 83% and 53% in the liver, kidney and heart respectively but decreased by 44% in the gills. MDA levels of

  20. Patterning and predicting aquatic insect richness in four West-African coastal rivers using artificial neural networks

    OpenAIRE

    Edia E.O.; Gevrey M.; Ouattara A.; Brosse S.; Gourène G.; Lek S.

    2010-01-01

    Despite their importance in stream management, the aquatic insect assemblages are still little known in West Africa. This is particularly true in South-Eastern Ivory Coast, where aquatic insect assemblages were hardly studied. We therefore aimed at characterising aquatic insect assemblages on four coastal rivers in South-Eastern Ivory Coast. Patterning aquatic insect assemblages was achieved using a Self-Organizing Map (SOM), an unsupervised Artificial Neural Networks (ANN) method. This metho...

  1. How to survive and persist in ephemeral water bodies?: the case of sponges (Porifera: Spongillina)

    OpenAIRE

    Manconi,Renata; Cadeddu, Barbara; Padiglia, Andrea; Demurtas, Daniela; Stocchino, Giacinta Angela; Pronzato, Roberto

    2015-01-01

    Ephemeral water bodies are subjected to unforeseeable and extreme fluctuations of environmental conditions constraining biodiversity values. Although data are fragmentary and scattered in the literature sponges are known to be able to colonize temporary/intermittent water bodies.

  2. 4chan and /b/: An Analysis of Anonymity and Ephemerality in a Large Online Community

    OpenAIRE

    Bernstein, Michael; Monroy-Hernández, Andrés; Harry, Drew; André, Paul; Panovich, Katrina; Vargas, Greg

    2011-01-01

    We present two studies of online ephemerality and anonymity based on the popular discussion board /b/ at 4chan.org: a website with over 7 million users that plays an influential role in Internet culture. Although researchers and practitioners often assume that user identity and data permanence are central tools in the design of online communities, we explore how /b/ succeeds despite being almost entirely anonymous and extremely ephemeral. We begin by describing /b/ and performing a content an...

  3. Spring Ephemerals Adapt to Extremely High Light Conditions via an Unusual Stabilization of Photosystem II

    Science.gov (United States)

    Tu, Wenfeng; Li, Yang; Liu, Wu; Wu, Lishuan; Xie, Xiaoyan; Zhang, Yuanming; Wilhelm, Christian; Yang, Chunhong

    2016-01-01

    Ephemerals, widely distributed in the Gobi desert, have developed significant characteristics to sustain high photosynthetic efficiency under high light (HL) conditions. Since the light reaction is the basis for photosynthetic conversion of solar energy to chemical energy, the photosynthetic performances in thylakoid membrane of the spring ephemerals in response to HL were studied. Three plant species, namely two C3 spring ephemeral species of Cruciferae: Arabidopsis pumila (A. pumila) and Sisymbrium altissimum (S. altissimum), and the model plant Arabidopsis thaliana (A. thaliana) were chosen for the study. The ephemeral A. pumila, which is genetically close to A. thaliana and ecologically in the same habitat as S. altissimum, was used to avoid complications arising from the superficial differences resulted from comparing plants from two extremely contrasting ecological groups. The findings manifested that the ephemerals showed significantly enhanced activities of photosystem (PS) II under HL conditions, while the activities of PSII in A. thaliana were markedly decreased under the same conditions. Detailed analyses of the electron transport processes revealed that the increased plastoquinone pool oxidization, together with the enhanced PSI activities, ensured a lowered excitation pressure to PSII of both ephemerals, and thus facilitated the photosynthetic control to avoid photodamage to PSII. The analysis of the reaction centers of the PSs, both in terms of D1 protein turnover kinetics and the long-term adaptation, revealed that the unusually stable PSs structure provided the basis for the ephemerals to carry out high photosynthetic performances. It is proposed that the characteristic photosynthetic performances of ephemerals were resulted from effects of the long-term adaptation to the harsh environments. PMID:26779223

  4. Ephemerality of discrete methane vents in lake sediments

    Science.gov (United States)

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn; Hemond, Harold F.; Juanes, Ruben

    2016-05-01

    Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

  5. Bovine Ephemeral Fever As A Disease Related To Climate Change

    Directory of Open Access Journals (Sweden)

    Indrawati Sendow

    2013-06-01

    Full Text Available Bovine Ephemeral Fever (BEF is one of arbovirus diseases infecting in ruminants especially cattle and buffaloes, which is transmitted by mosquito vectors. In general, vector borne disease is also related to climate change, that mosquito as a vector will significantly increase when the environment temperature increases. The disease was found in many countries in Asia, Africa and Australia. The clinical sign of the disease such as fever to paralysis causes economical impact to the farmer, eventhough the mortality is very low. This review will discuss the disease in relation to climate change, which affects vector population that spread the disease. The more population of vector is the higher chance of animal to be infected. This condition describes that the spread of BEF will depend on some factors included the increase of vectors, the availability of susceptible host and vector media facilities, climate condition and supportive ecology. This paper will discuss the feature of BEF, mode of transmission, the impact of environment and climate change, disease prevention and control, and other aspects to prevent further economical impact. It will also discuss how to the transmission, prevention and control of disease BEF. The information can be taken as an input for policy makers to prevent BEF infection in Indonesia.

  6. Annual flow duration curves assessment in ephemeral small basins

    Science.gov (United States)

    Pumo, D.; Viola, F.; La Loggia, G.; Noto, L. V.

    2014-11-01

    Flow duration curve (FDC) represents a comprehensive signature of temporal runoff variability often used to synthesize catchment rainfall-runoff responses. A new model, the ModABa (MODel for Annual flow duration curves assessment in ephemeral small BAsins), is here introduced. It can be thought as a wide mosaic whose tesserae are frameworks, models or conceptual schemes separately developed in different studies and harmoniously interconnected with the final aim of reproducing the annual FDC in intermittent small catchments. Two separated seasons within the hydrological year are distinguished: a dry season, characterized by absence of streamflow, and a non-zero season. Streamflow is disaggregated into a subsurface component and a surface component that, in turn, is considered formed by two different contributions: impervious runoff and surface runoff from permeable areas induced by heavy rains. The FDCs of the two streamflow components are first separately and differently computed, and then combined to obtain the non-zero FDC. This last, together with the estimated probability of null streamflow, allows the annual FDC assessment through the theory of total probability. The ModABa is here tested on a small Italian catchment and the results show how the model, once calibrated, is able to accurately reproduce the empirical FDC for the analyzed case, starting from easily derivable parameters and commonly available climatic data. In this sense, the model reveals itself as a valid tool, potentially suitable for predictions at ungauged basins in a regionalization framework.

  7. Ephemerality of discrete methane vents in lake sediments

    Science.gov (United States)

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn; Hemond, Harold F.; Juanes, Ruben

    2016-01-01

    Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

  8. Adaptive management and water temperature variability within a South African river system: what are the management options?

    Science.gov (United States)

    Rivers-Moore, N A; Jewitt, G P W

    2007-01-01

    Water temperatures, and in particular daily maximum water temperatures, are a critical water quality parameter. An understanding of associated resource management issues, including links between water temperature variability and aquatic diversity values, should be part of any management programme that considers river systems. Simple rule-based models have been shown to be appropriate tools within an adaptive management approach, both because of their heuristic value and in their application for scenario generation. Such a model was developed to simulate changes in the condition factor of Chiloglanis anoterus [Crass, R.S., 1960. Notes on the freshwater fishes of Natal with descriptions of 4 new species. Annals of the Natal Museum 14, 405-458] (Pisces: Mochokidae) in response to annual frequency of exceedance of a threshold temperature under three broad environmental scenarios for part of the Sabie River falling within South Africa's Kruger National Park. This model has potential for application within the adaptive management programme being implemented by the Kruger National Park. Results show that under broad scenarios of a 10% reduction in mean daily flow rates, or a 2 degrees C increase in mean daily air temperatures, system variability is likely to increase relative to reference conditions . It is suggested that so-called "thresholds of probable concern" (TPCs), which are based on current levels of "natural" system variability, are useful as management targets for achieving a "desired future state" for the river system. The model, recognised as a preliminary hypothesis, highlights a lack of knowledge regarding the nature of system variability, and the correspondingly wide confidence limits of the proposed TPC restricts its utility in a short-term management context. Thus, it is now recognised that its value lies more in its use as a long-term modelling tool to reflect water temperature responses to flow variability. This highlights the fact that research

  9. Morphological impacts of flow events of varying magnitude on ephemeral channels in a semiarid region

    Science.gov (United States)

    Hooke, J. M.

    2016-01-01

    Flows in ephemeral channels in semiarid areas are only occasional, and channel changes are episodic; but the flash floods can be devastating and have major geomorphological impacts. Data on morphological impacts of flows in semiarid areas are needed to increase understanding of the dynamics and variability of geomorphic responses in such channels. For this purpose nine reaches of river channel in three catchments in SE Spain - the Nogalte, Torrealvilla, and Salada - have been sites for measurement of flows and their effects over the period 1997-2012. The sites encompass a range of channel size, channel morphology, substrate, vegetation, and position within the catchments. A major difference is between schist and marl bedrock areas. Peak flow stage has been recorded and topography surveyed at frequent intervals and after major flow events. Over the 16-year period, an average of 0.5 flow events per year has been recorded at the schist sites, and an average of one per year at the marl sites; but occurrence has been highly variable from year to year. Threshold daily rainfall for channel flow is mostly 15-20 mm, but higher rainfalls do not always produce flow. One to two major floods have occurred in each of the catchments in the period, including the extreme flood event of September 2012 in the Nogalte catchment. Measured morphological changes have occurred between 2 and 10 times at the monitored sites. The same size flow can have differing effects depending on the state of the system. Low flow can mobilise sediment without producing much morphological change. The long-term trajectory of the reaches and the sediment substrate has a major influence on response to events. Channel change is governed by threshold values of hydraulic conditions. The measurements provide an indication of the scale of maximum erosion and deposition that occurs within the channels and on the floodplains over a range of flow magnitudes and the flow impacts that need to be considered in

  10. Evolution of the African continental crust as recorded by U-Pb, Lu-Hf and O isotopes in detrital zircons from modern rivers

    Science.gov (United States)

    Iizuka, Tsuyoshi; Campbell, Ian H.; Allen, Charlotte M.; Gill, James B.; Maruyama, Shigenori; Makoka, Frédéric

    2013-04-01

    To better understand the evolutionary history of the African continental crust, a combined U-Pb, Lu-Hf and O isotopic study has been carried out by in situ analyses of approximately 450 detrital zircon grains from the Niger, Nile, Congo, Zambezi and Orange Rivers. The U-Pb isotopic data show age peaks at ca. 2.7, 2.1-1.8, 1.2-1.0, ca. 0.8, 0.7-0.5 and ca. 0.3 Ga. These peaks, with the exception of the one at ca. 0.8 Ga, correspond with the assembly of supercontinents. Furthermore, the detrital zircons that crystallized during these periods of supercontinent assembly have dominantly non-mantle-like O and Hf isotopic signatures, in contrast to the ca. 0.8 Ga detrital zircons which have juvenile characteristics. These data can be interpreted as showing that continental collisions during supercontinent assembly resulted in supermountain building accompanied by remelting of older continental crust, which in turn led to significant erosion of young igneous rocks with non-mantle-like isotopic signatures. Alternatively, the data may indicate that the major mode of crustal development changed during the supercontinent cycle: the generation of juvenile crust in extensional settings was dominant during supercontinent fragmentation, whereas the stabilization of the generated crust via crustal accretion and reworking was important during supercontinent assembly. The Lu-Hf and O isotope systematics indicate that terreigneous sediments could attain elevated 18O/16O via prolonged sediment-sediment recycling over long crustal residence time, and also that reworking of carbonate and chert which generally have elevated 18O/16O and low Hf contents is minor in granitoid magmatism. The highest 18O/16O in detrital zircon abruptly increased at ca. 2.1 Ga and became nearly constant thereafter. This indicates that reworking of mature sediments increased abruptly at that time, probably as a result of a transition in the dynamics of either granitoid crust formation or sedimentary evolution

  11. Properties of solar ephemeral regions at the emergence stage

    International Nuclear Information System (INIS)

    For the first time, we statistically study the properties of ephemeral regions (ERs) and quantitatively determine their parameters at the emergence stage based on a sample of 2988 ERs observed by the Solar Dynamics Observatory. During the emergence process, there are three kinds of kinematic performances, i.e., separation of dipolar patches, shift of the ER's magnetic centroid, and rotation of the ER's axis. The average emergence duration, flux emergence rate, separation velocity, shift velocity, and angular speed are 49.3 minutes, 2.6 × 1015 Mx s–1, 1.1 km s–1, 0.9 km s–1, and 0.°6 minute–1, respectively. At the end of emergence, the mean magnetic flux, separation distance, shift distance, and rotation angle are 9.3 × 1018 Mx, 4.7 Mm, 1.1 Mm, and 12.°9, respectively. We also find that the higher the ER magnetic flux is, (1) the longer the emergence lasts, (2) the higher the flux emergence rate is, (3) the further the two polarities separate, (4) the lower the separation velocity is, (5) the larger the shift distance is, (6) the slower the ER shifts, and (7) the lower the rotation speed is. However, the rotation angle seems not to depend on the magnetic flux. Not only at the start time, but also at the end time, the ERs are randomly oriented in both the northern and the southern hemispheres. Finally, neither the anti-clockwise-rotated ERs nor the clockwise rotated ones dominate the northern or the southern hemisphere.

  12. Bacterial succession within an ephemeral hypereutrophic mojave desert playa lake

    Science.gov (United States)

    Navarro, J.B.; Moser, D.P.; Flores, A.; Ross, C.; Rosen, Michael R.; Dong, H.; Zhang, G.; Hedlund, B.P.

    2009-01-01

    Ephemerally wet playas are conspicuous features of arid landscapes worldwide; however, they have not been well studied as habitats for microorganisms. We tracked the geochemistry and microbial community in Silver Lake playa, California, over one flooding/desiccation cycle following the unusually wet winter of 2004-2005. Over the course of the study, total dissolved solids increased by 10-fold and pH increased by nearly one unit. As the lake contracted and temperatures increased over the summer, a moderately dense planktonic population of 1 ?????106 cells ml-1 of culturable heterotrophs was replaced by a dense population of more than 1????????109 cells ml-1, which appears to be the highest concentration of culturable planktonic heterotrophs reported in any natural aquatic ecosystem. This correlated with a dramatic depletion of nitrate as well as changes in the microbial community, as assessed by small subunit ribosomal RNA gene sequencing of bacterial isolates and uncultivated clones. Isolates from the early-phase flooded playa were primarily Actinobacteria, Firmicutes, and Bacteroidetes, yet clone libraries were dominated by Betaproteobacteria and yet uncultivated Actinobacteria. Isolates from the late-flooded phase ecosystem were predominantly Proteobacteria, particularly alkalitolerant isolates of Rhodobaca, Porphyrobacter, Hydrogenophaga, Alishwenella, and relatives of Thauera; however, clone libraries were composed almost entirely of Synechococcus (Cyanobacteria). A sample taken after the playa surface was completely desiccated contained diverse culturable Actinobacteria typically isolated from soils. In total, 205 isolates and 166 clones represented 82 and 44 species-level groups, respectively, including a wide diversity of Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Gemmatimonadetes, Acidobacteria, and Cyanobacteria. ?? 2008 Springer Science+Business Media, LLC.

  13. Responses of ephemeral plant germination and growth to water and heat conditions in the southern part of Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    WANG Xueqing; JIANG Jin; WANG Yuanchao; LUO Weilin; SONG Chunwu; CHEN Junjie

    2006-01-01

    Ephemeral plants in the southern part of Gurbantunggut Desert were systematically monitored from 2002 to 2004 and the meteorological data and soil moisture during the same period were analyzed.The results show that the ephemeral plants germination and growth are sensitive to the changes of water and heat condition. The time for daily temperature over 0℃ in early spring in 2003 was delayed nearly 10 d compared with that in 2002, while the soil water changed little in the same period. Observation showed that there were 28 ephemeral species germinated in 2002, their life period was about 70 d in spring, and the maximum cover of ephemeral synusia reached 46.4%. However, only 17 ephemeral species germinated in 2003, their life period was about 50 d in spring, and their maximum cover was only 20.8%.The height of ephemeral plants was significantly higher in 2002 than that in 2003. It can be seen that ephemeral plant germination and growth in spring are strongly dependent on temperature. The changes of water conditions can affect ephemerals germination and growth as well. Because no heavy precipitation occurred during summer in 2002, only a few ephemerophytes were observed in autumn after ephemerals completed their life circle in early spring. However,about 60 mm precipitation was recorded from July to August both in 2003 and in 2004. Some ephemerals such as Erodium oxyrrhynchum and Carex physodes,etc. covered the dune surface rapidly with a cover >10%. Therefore, the ephemerals not only germinate in autumn after the early spring, some species may germinate in summer if adequate rainfall occurs. The study on responses of ephemerals growth to water and heat conditions not only has a certain ecological significance but also contributes a better understanding to the effect of climate changes on the desert surface stability.

  14. Monogenean parasites of the African catifsh Clarias gariepinus from two ifsh farms in Calabar, Cross River State, Nigeria

    Institute of Scientific and Technical Information of China (English)

    Eyo Victor Oscar; Edet Theresa Arit; Ekanem Albert Philip

    2015-01-01

    Objective: To determine the prevalence, mean intensity, and abundance of monogenean parasites in Clarias gariepinus (C. gariepinus) from two selected fish farms in Calabar, Cross River State, Nigeria. Methods:Eighty specimens of C. gariepinus from the two farms (40 each) were necropsied for parasitological analysis. Skin, gill and fin biopsies were prepared from each specimen following standard methods for microscopic analysis. Parasitological indices including dominance (D), prevalence, mean intensity and abundance were calculated according to standard formulae. Data were analyzed using the Fisher's exact test. Results:C. gariepinus from the two farms were infested with a total of ninety individuals of monogenean parasites belonging to three species including Macrogyrodactylus clarii (M. clarii), Gyrodactylus sp. and Dactylogyrus sp. D index showed that the three monogenean species were eudominant (D-value>10%). Gyrodactylus sp. was more abundant (46) followed by Dactylogyrus sp. (23) while M. clarii was the lowest (21). Prevalence, meaning intensity and abundance of monogenean parasites in the two farms, varied insignificantly higher (P>0.05). Prevalence in both farms were higher in female C. gariepinus than that in male. Monogenean parasites exhibited organ specificity as M. clarii and Dactylogyrus sp. were recovered from the gills while Gyrodactylus sp. colonized the skin and fin. Conclusions:High abundance of these parasites may lead to poor growth performance and high mortality in C. gariepinus, leading to huge monetary loss and low profit margin by increasing production cost due to the cost of treatments.

  15. Patterning and predicting aquatic insect richness in four West-African coastal rivers using artificial neural networks

    Directory of Open Access Journals (Sweden)

    Edia E.O.

    2010-10-01

    Full Text Available Despite their importance in stream management, the aquatic insect assemblages are still little known in West Africa. This is particularly true in South-Eastern Ivory Coast, where aquatic insect assemblages were hardly studied. We therefore aimed at characterising aquatic insect assemblages on four coastal rivers in South-Eastern Ivory Coast. Patterning aquatic insect assemblages was achieved using a Self-Organizing Map (SOM, an unsupervised Artificial Neural Networks (ANN method. This method was applied to pattern the samples based on the richness of five major orders of aquatic insects (Diptera, Ephemeroptera, Coleoptera, Trichoptera and Odonata. This permitted to identify three clusters that were mainly related to the local environmental status of sampling sites. Then, we used the environmental characteristics of the sites to predict, using a multilayer perceptron neural network (MLP, trained by BackPropagation algorithm (BP, a supervised ANN, the richness of the five insect orders. The BP showed high predictability (0.90 for both Diptera and Trichoptera, 0.84 for both Coleoptera and Odonata, 0.69 for Ephemeroptera. The most contributing variables in predicting the five insect order richness were pH, conductivity, total dissolved solids, water temperature, percentage of rock and the canopy. This underlines the crucial influence of both instream characteristics and riparian context.

  16. Future Water Resources Assessment for West African River Basins Under Climate Change, Population Growth and Irrigation Development

    Science.gov (United States)

    Wisser, D.; Ibrahim, B.; Proussevitch, A. A.

    2014-12-01

    West Africa economies rely on rain-fed agriculture and are extremely vulnerable to changes in precipitation. Results from the most recent generation of regional climate models suggest increases in rainy season rainfall variability (delayed rainy season onset, increased probability of dry spells, shorter rainy season duration) despite a moderate increase in rainy season total precipitation. These changes could potentially have detrimental effects on crop yield and food security. Additional pressures on water resources come from increased demand as a result of high population growth rates (~3% per year). Increased water storage and irrigation can help improve crop yields but future assessments of water resources are needed to prioritize irrigation development as an adaptation option. Increased water abstraction, in turn can impact water availability in downstream regions so that an integrated assessment of future water availability and demand is needed. We use a set of 15 RCM outputs from the CORDEX data archive to drive WBMplus, a hydrological model and simulate water availability under climate change. Based on estimated water constraints, we develop scenarios to expand irrigated areas (from the current 1% of all croplands) and calculate the effects on water scarcity, taking into account increased demand for domestic consumption and livestock water demand, at a spatial resolution of 10 km. Results around the 2050's indicate large potential to develop irrigated areas on ground and surface water and increase local water storage without increasing water scarcity downstream for many river basins in the region that could help alleviate pressures on the cropping systems and thereby increase food security.

  17. Benefiting Africans

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Along with thriving Sino-African economic and trade ties,Chinese companies have attached greater importance to their social responsibility to Africans.More than 2,000 sweaters woven by Chinese mothers were sent to orphans and disabled children in Kenya and four other African countries in September. This activity was launched by Hengyuanxiang,aleading Chinese wool manufacturer.

  18. Benefiting Africans

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZHIPING

    2011-01-01

    Along with thriving Sino-African economic and trade ties,Chinese companies have attached greater importance to their social responsibility to Africans.More than 2,000 sweaters woven by Chinese mothers were sent to orphans and disabled children in Kenya and four other African countries in September.This activity was launched by Hengyuanxiang,a leading Chinese wool manufacturer.

  19. Evaluating ephemeral gully erosion impact on Zea mays L. yield and economics using AnnAGNPS

    Science.gov (United States)

    Ephemeral gully erosion causes serious water quality and economic problems in the Midwest United States. A critical barrier to soil conservation practice adoption is often the implementation cost, although it is recognized that erosion reduces farm income. Yet few, if any, understand the relationshi...

  20. Rainfall Threshold For Ephemeral Gully Erosion In Foothill Cultivated Lands (Wiśnicz Foothills, Poland)

    Science.gov (United States)

    Święchowicz, Jolanta

    2016-04-01

    The paper presents the results of ephemeral gullies studies carried out in hydrological years 1998-2009 on the Jagiellonian University's farm, which is located in the village of Łazy (Southern Poland). The farm covers an area of 103 ha. The dominant relief type is low hills. Soil erosion hardly ever occurs on the whole area of slopes in the catchment, and transport of eroded material is irregular and not simultaneous. The formation of ephemeral gullies happens once a year or once in a few years. The events are occasional and happen locally. Ephemeral gullies most frequently form and develop on cultivated slopes in natural drainage lines or they are associated with man-made agricultural activities like field borders, furrows, tractor traces and cart roads. The research carried out in Wiśnicz Foothills shows that the development of ephemeral gullies was limited both by extrinsic (erosivity of rain) and intrinsic thresholds (the length of slope, the presence (or lack of) Bt horizon, soil moisture, type and calendar of crops and farming activities). Ephemeral gullies usually form and develop during single rain or several subsequent rains of high erosivity (of several hundred MJmmha-1h-1) on long cultivated slopes, particularly at the beginning of vegetation period, when most slopes are devoid of vegetation cover or plants are in the initial stage of growth. The process of enlarging and deepening of ephemeral gullies slows down when the incision of a gully reaches Bt horizon. Then the effectiveness of even high erosivity rainfall is much smaller. Similarly, very high erosivity of rainfall in the middle of the vegetation season is not able to cause such serious effect and the intensity of deepening of ephemeral gullies is much smaller. The process of intensified linear water erosion is more significant on commercial farms with a large acreage of crops. As a result all the mapped erosion forms were disposed of by farmers (e.g. by ploughing or filling up). If these forms

  1. Effects of ephemeral gully erosion on soil degradation in a cultivated area in Sicily

    Science.gov (United States)

    La Spada, Carmelo; Capra, Antonina; Gelsomino, Antonio; Ollobarren del Barrio, Paul

    2015-04-01

    Water erosion is the main cause of soil degradation on cultivated lands under Mediterranean climate. In this conditions, gully erosion is a major contributor to loss of soil productivity due to the big amounts of soil removed from the most productive top-layer. However, only few studies on the effects of gully erosion and artificial controlling measures on soil degradation are available. The study analyzes the effects of the ephemeral gully erosion and infilling by tillage operations on several physical-chemical soil properties influencing the soil productivity. The study area is located in the center of Sicily, in an agricultural context characterized by ephemeral gully erosion. Five fields with different crops and soil characteristics affected by this type of erosion were selected. Currently, local farmers adopt the artificial measure to gully filling activities to control gully erosion and continue the same agricultural management practice. Therefore, the studied ephemeral gullies show a cyclic behavior. They appear during the rainy season, are erased from July to October by soil infill from areas adjacent to the channel using ordinary tillage equipment, and, in most years, they reappear in the same position during the following rainy season. For each situation, 20 samples were taken, located on 5 transects in the direction perpendicular to the ephemeral gully, in specific positions: 2 outside the erosive channel (one in the valley-deposit area and one upstream of the basin in the undisturbed area), and 3 along the same. For each transect, the samples were collected in 4 different positions: one inside the ephemeral gully, the other 3 in external points spaced to represent the areas affected by the annual process of erosion and infilling of the gully. For each sample, a set of the main chemical and physical soil characteristics which influence the soil fertility were determined: particle size, pH, electrical conductivity, total content of carbonates, nitrates

  2. Conrad, David C. – Somono Bala of the Upper Niger. River People, Charismatic Bards and Mischievious Music in a West African Culture

    OpenAIRE

    Perrot, Claude-Hélène

    2007-01-01

    Ce livre est le premier d’une nouvelle collection (« African Sources for African History ») lancée par des chercheurs des universités de Liverpool (Dmitri van den Bersselaar), de Groningen (Michel Doortmont) et de Leiden (Jan Jansen), où elle a été premièrement conçue. Le propos est la publication de sources inédites (ou dont l’édition existante serait tronquée ou défectueuse) englobant manuscrits, dessins et photographies. Les auteurs en sont des Africains, mais les collecteurs de ces source...

  3. The Influence of Ephemeral Beaches on Alongshore Variability of Hard-rock Cliff Erosion

    Science.gov (United States)

    Vann Jones, E. C.; Rosser, N. J.; Brain, M.; Varley, S. J.

    2015-12-01

    The role of abrasion of rock cliffs is typically considered in the long-term presence of a beach. During monthly monitoring of hard rock cliff erosion along the North Yorkshire coast, UK, we have observed a number of small ephemeral beaches of highly variable duration and extent. The erosive significance of the temporary presence of sediment at the cliffs is unknown and we set out to examine whether observed alongshore variability in erosion can be linked to the presence of ephemeral beaches. We explore the temporal and spatial variability in sediment deposition and transport along a low-sediment rock coast foreshore, the controlling marine conditions and the effects on cliff erosion. We focus on a 500 m wide embayment set into 70 m high hard rock cliffs consisting of horizontally bedded Jurassic mudstone, shale, siltstone and sandstone. The bay has a wide, shallow gradient foreshore up to 300 m wide with highly variable topography. With the exception of an ephemeral beach (of widths up to approximately 150 m alongshore and 10 m cross-shore) the rock foreshore is typically sand-free, with failed material from the cliffs quickly removed from the cliff toe by the sea leaving only boulders. The high tidal range (6 m) and storm wave environment of the North Sea result in variable marine conditions at the site. We use magnetic sand tracers and a grid of foreshore and cliff face magnets to examine the sand transport across the foreshore and to identify the vertical extent of cliff face impacted by sand. We monitor the driving marine conditions on the foreshore using a network of current meters and wave pressure sensors. Erosion of the cliff face across the whole bay is monitored at high-resolution using terrestrial laser scanning to examine the spatial distribution of abrasion and the influence of the ephemeral beach.

  4. ‘Not Months but Moments’: Ephemerality, Monumentality, and the Pavilion in Ruins

    Directory of Open Access Journals (Sweden)

    Ihor Junyk

    2014-02-01

    Full Text Available This article examines a fundamental tension between ephemerality and monumentality in the history of pavilion architecture. Descended from the ancient tent, the pavilion was taken up by European landscape architecture in the eighteenth century. Integrated into an aesthetic of the picturesque, these ephemeral structures were both settings and instruments of a set of fleeting experiences that can be grouped under the category of reverie. However, during the course of the nineteenth century, the pavilion underwent a dramatic change, gradually becoming the monumental representative of the nations that participated at the various expositions and World’s Fairs that took place during that century and the next. Unable to actualize the permanence they were meant to embody, pavilions instead called forth aggressive fantasies of ruin and death. Wary of the deathly aesthetics of monumentality and sublimity, architects working in the last couple decades have returned the pavilion to its original ephemerality. Experimenting with new materials and digital technologies they have created contemporary follies as new spaces for reverie.

  5. Behavior and identification of ephemeral sand dunes at the backshore zone using video images

    Directory of Open Access Journals (Sweden)

    PEDRO V. GUIMARÃES

    2016-01-01

    Full Text Available ABSTRACT The backshore zone is transitional environment strongly affected by ocean, air and sand movements. On dissipative beaches, the formation of ephemeral dunes over the backshore zone plays significant contribution in the beach morphodynamics and sediment budget. The aim of this work is to describe a novel method to identify ephemeral dunes in the backshore region and to discuss their morphodynamic behavior. The beach morphology is identified using Argus video imagery, which reveals the behavior of morphologies at Cassino Beach, Rio Grande do Sul, Brasil. Daily images from 2005 to 2007, topographic profiles, meteorological data, and sedimentological parameters were used to determine the frequency and pervasiveness of these features on the backshore. Results indicated that coastline orientation relative to the dominant NE and E winds and the dissipative morphological beach state favored aeolian sand transport towards the backshore. Prevailing NE winds increase sand transportation to the backshore, resulting in the formation of barchans, transverse, and barchanoid-linguiod dunes. Precipitation inhibits aeolian transport and ephemeral dune formation and maintains the existing morphologies during strong SE and SW winds, provided the storm surge is not too high.

  6. Behavior and identification of ephemeral sand dunes at the backshore zone using video images.

    Science.gov (United States)

    Guimarães, Pedro V; Pereira, Pedro S; Calliari, Lauro J; Ellis, Jean T

    2016-09-01

    The backshore zone is transitional environment strongly affected by ocean, air and sand movements. On dissipative beaches, the formation of ephemeral dunes over the backshore zone plays significant contribution in the beach morphodynamics and sediment budget. The aim of this work is to describe a novel method to identify ephemeral dunes in the backshore region and to discuss their morphodynamic behavior. The beach morphology is identified using Argus video imagery, which reveals the behavior of morphologies at Cassino Beach, Rio Grande do Sul, Brasil. Daily images from 2005 to 2007, topographic profiles, meteorological data, and sedimentological parameters were used to determine the frequency and pervasiveness of these features on the backshore. Results indicated that coastline orientation relative to the dominant NE and E winds and the dissipative morphological beach state favored aeolian sand transport towards the backshore. Prevailing NE winds increase sand transportation to the backshore, resulting in the formation of barchans, transverse, and barchanoid-linguiod dunes. Precipitation inhibits aeolian transport and ephemeral dune formation and maintains the existing morphologies during strong SE and SW winds, provided the storm surge is not too high.

  7. The traditional, the innovative, the ephemeral: conception, realization, intervention in contemporary art

    Directory of Open Access Journals (Sweden)

    Salvatore Lorusso

    2009-03-01

    Full Text Available The traditional, the innovative, the ephemeral: conception, realization, intervention in contemporary art. One must consider the traditional, the innovative and also the ephemeral related to the artistic intentions and thus to the interventions on works of contemporary art, for which the concepts of originality and authenticity do not always correspond. The Brandian vision and point of view do not completely resolve the problematics relative to restoration and conservation: artists realize their artifacts with the intention of undermining tradition or, however, of interpreting it in an unusual way. There are, therefore, cases when a diagnostic-analytical and conservative intervention is possible correspondently to the different and numerous typologies of the materials (poor, plastic, industrial and techniques (collage, enamel on rubber foam, paint on textile or plastic, neon. A vocation for the ephemeral can be transformed into the adoption of deteriorated materials or into the realization of works of conceptual art and net-art. Some case studies are treated in the comparison of art works of different age. The solutions to the aforementioned problematics are offered and the importance of the involvement of the historical-technical experts, authors and manufacturers of the materials used in the artifacts is highlighted. Finally the procedure of intervention cannot be the same for all works of contemporary art. One must employ a methodology based on the critical study, not only of the materials used but also of the philosophy and creative conceptual intentions of the artist.

  8. Diversity of arbuscular mycorrhizal fungi associated with desert ephemerals growing under and beyond the canopies of Tamarisk shrubs

    Institute of Scientific and Technical Information of China (English)

    SHI Zhaoyong; ZHANG Liyun; FENG Gu; Christie Peter; TIAN Changyan; LI Xiaolin

    2006-01-01

    The arbuscular mycorrhizal (AM) fungal status of the four most common ephemeral plant species, Chorispora tenella (Pall.) DC., Ceratocephalus testiculatus (Crantz) Bess., Eremopyrum orientale (L.) Jaub et. Spash and Veronica campylopoda Boiss growing in an area dominated by Tamarisk shrubs (Tamarix spp.) was investigated.Samples of the four ephemerals and their rhizosphere soils were collected from underneath and beyond the canopies of the Tamarisk shrubs.Plant mycorrhizal status and soil AM fungal spore densities and community structures were analyzed and compared under and beyond the shrub canopies.The mycorrhizal colonization rates of the ephemerals and spore densities in their corresponding rhizosphere soils were significantly lower under the shrub canopies than beyond. The number of AM fungal species under the shrubs (12) was also lower than beyond the canopies (19). When soil properties in the rhizospheres of the four ephemerals were examined, available N and P and total P, organic matter content, total salt content and electrical conductivity (EC) were all higher under the canopies than beyond. In contrast, soil available K and pH showed no such trend. A total of 21 AM fungal species were isolated from rhizosphere soils of the four ephemerals. Five belonged to Acaulospora, one to Archaeospora, thirteen to Glomus and two to Paraglomus. We conclude that the canopies of Tamarix spp. exerted some influence on the AM status of the ephemerals and on the AM fungal communities and some of the properties of their rhizosphere soils.

  9. Cancer and African Americans

    Science.gov (United States)

    ... Population Profiles > Black/African American > Cancer Cancer and African Americans African Americans have the highest mortality rate ... 65MB] At a glance – Top Cancer Sites for African Americans (2008-2012) Cancer Incidence Rates per 100, ...

  10. The Allure of Privacy or the Desire for Self-Expression? Identifying Users' Gratifications for Ephemeral, Photograph-Based Communication.

    Science.gov (United States)

    Waddell, T Franklin

    2016-07-01

    Temporary messaging programs continue to rise in popularity, due in large part to the perceived privacy that they afford. However, recent controversies have revealed that messages shared on ephemeral messaging services are persistent and potentially retrieval, thus undermining the privacy they are assumed to provide. Given this paradox, why are temporary messaging services so popular? Does the allure of privacy still motivate the use of temporary messaging programs? Or, if privacy is no longer afforded by ephemeral messaging, what other psychological gratifications do these applications fulfill that might account for their continued use? Informed by the Modality-Agency-Interactivity-Navigability (MAIN) model and the uses and gratifications tradition, the current study conducted qualitative interviews to identify the gratifications that individuals derive from the popular ephemeral messaging application, Snapchat. Study results show that the visual affordances of ephemeral messaging have legitimized photographic communication, providing self-expression and relational gratifications that are unfulfilled by text-based applications. By comparison, users report low levels of trust in the privacy affordances of ephemeral messaging, and instead projecting negative effects of temporary messaging on other users rather than self. Theoretical and practical implications of these results are discussed. PMID:27428032

  11. Pollination biology of the urban populations of an ancient forest, spring ephemeral plant

    Directory of Open Access Journals (Sweden)

    Maciej A. Ziemiański

    2016-04-01

    Full Text Available Habitat fragmentation, caused by, among all, agriculture and urbanization, is one of the most important drivers of plant biodiversity decline worldwide. One of the signs of deteriorating zoogamous plant reproduction is pollen limitation, often associated with a decline in pollinator diversity and abundance. Various authors predict that the most vulnerable taxa are outbreeding plant species characterized by specialist pollination systems. We have, therefore, focused on self-incompatible Corydalis solida, an ancient forest, spring ephemeral plant, growing in three remnant urban populations in the city of Warsaw (Poland. Over two years, we checked for pollen limitation and recorded insect diversity and abundance for C. solida flowers. Our study populations composed of self-incompatible individuals were mainly visited by generalist pollinators, and produced more seeds when supplementally pollinated. Pollen limitation, however, was greater during 1 year with an early spring onset, when we observed a decline in floral visitors diversity and activity. This was probably an effect of phenological mismatch between plants and their pollinators, in this case, mostly social bees, i.e., over-wintered bumblebee queens and Apis mellifera. We conclude that for outbreeding zoogamous spring ephemerals, such as C. solida serviced by generalist pollinators, changing climatic conditions may override the effects of habitat fragmentation and influence their reproductive success.

  12. Flood routing in an ephemeral channel with compound cross-section

    Indian Academy of Sciences (India)

    M BALAMURUGAN; S MURTY BHALLAMUDI

    2016-07-01

    Natural phenomenon of surface and subsurface flow interaction is an intrinsic component of the hydrological processes in any watershed. It is a highly sensitive process, especially in arid and semi-arid regions, and should be considered while dealing with any water management activity in these regions. This paper describes a novel approach for flood routing in an ephemeral channel with compound cross-sections. The proposed mathematical model couples the numerical solution for complete Saint-Venant equations for surfaceflow with the numerical solution for one-dimensional Richards equation for sub-surface flow through an iterative procedure. Recently developed interactive divided channel (IDC) method is incorporated for simulating the main channel and flood plain flow interactions. In the one-dimensional surface and pseudo two-dimensional subsurface (1DSP2DSS) model presented here, the effect of lateral variation in infiltration rate at a cross section arising due to (i) lateral variation in flow depth and (ii) lateral variation in soil characteristics is incorporated by considering infiltration into different soil columns for main channel and flood plains. The proposed model is verified by comparing the model results with those available in literature for benchmark problems Simulations are presented to demonstrate the capability of the model for flood routing in ephemeral channels with flood plains and the effect of lateral variation in infiltration rate on transmission losses.

  13. Latitude of Ephemeral Regions as Indicator of Strength of Solar Cycles

    CERN Document Server

    Tlatov, Andrey G

    2010-01-01

    Digitized images of full disk CaK spectroheliograms from two solar observatories were used to study cycle variation of ephemeral regions (ERs) over ten solar cycles 14-23. We calculate monthly averaged unsigned latitude of ERs and compare it with annual sunspot number. We find that average latitude of ERs can be used as a predictor for strength of solar cycle. For a short-term prediction (dT about 1-2 years), maximum latitude of ephemeral regions (in current cycle) defines the amplitude of that cycle (higher is the latitude of ERs, larger are the amplitudes of sunspot cycle). For a long-term prediction (dT about 1.5 solar cycles), latitude of ERs at declining phase of n-th cycle determines the amplitude of (n+2)-th sunspot cycle (lower is the latitude of ERs, stronger is the cycle). Using this latter dependency, we forecast the amplitude of sunspot cycle 24 at W=92 +/- 13 (in units of annual sunspot number).

  14. Analysis of phosphorus forms in sediment cores from ephemeral ponds on Ardley Island, West Antarctica

    Institute of Scientific and Technical Information of China (English)

    YANG Lianjiao; QIN Xianyan; SUN Liguang; HUANG Tao; WANG Yuhong

    2015-01-01

    The guano of penguins, other seabirds, and pinnipeds is an important source of phosphorus in the ecosystems of Antarctica. To study the vertical distribution of phosphorus in sediments influenced by penguins, we measured phosphorus forms in two sediment cores (G1 and Q2) from ephemeral ponds on Ardley Island. We also investigated the correlations between these phosphorus forms and physicochemical characteristics. Inorganic phosphorus was the main form of phosphorus in both cores. The vertical distribution patterns of phosphorus forms in G1 and Q2 differed, indicating different sedimentary sources. The G1 sediment profile was more influenced by penguin guano than the Q2 profile, and as a result sediments in the G1 core had higher total phosphorus, non-apatite inorganic phosphorus, and apatite phosphorus content. The findings from two ephemeral ponds on Ardley Island indicate that the contribution of penguin guano to organic matter in G1 core has increased in recent times, while Q2 showed a relatively larger contribution from mosses in ancient times, evident from the lithology and the vertical trend in organic matter.

  15. Ephemeral Fe(II)/Fe(III) layered double hydroxides in hydromorphic soils: A review

    Science.gov (United States)

    Vodyanitskii, Yu. N.; Shoba, S. A.

    2015-03-01

    Ephemeral green rust is formed seasonally in some hydromorphic soils. It consists of Fe(II)/Fe(III) layered double hydroxides with different types of interlayer anions and different oxidation degrees of iron ( x). In synthetized stoichiometric green rust, x = 0.25-0.33; in soil fougerite, it may reach 0.50-0.66. The mineral stability is provided by the partial substitution of Mg2+ for Fe2+. The ephemeral properties of the green rust are manifested in the high sensitivity to the varying redox regime in hydromorphic soils. Green rust disappears during oxidation stages, which complicates its diagnostics in soils. For green rust formation, excessively moist mineral soil needs organic matter as a source of energy for the vital activity of iron-reducing bacteria. In a gleyed Cambisol France, where fougerite is formed in the winter, the index of hydrogen partial pressure rH2 is 7.0-8.2, which corresponds to highly reducing conditions; upon the development of oxidation, fougerite is transformed into lepidocrocite. In the mineral siderite horizon of peatbogs in Belarus, where green rust is formed in the summer, rH2 is 11-14, which corresponds to the lower boundary of reducing conditions ( rH2 = 10-18); magnetite is formed in these soils in the winter season upon dehydration of the soil mass.

  16. EVALUATION OF RILL AND EPHEMERAL GULLY EROSION IN CULTIVATED AREAS OF NAVARRE (SPAIN)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Although there is much evidence of intense soil erosion in cultivated areas of Navarre (Spain), scarce information currently is available regarding soil loss rates, the spatial and temporal distribution of erosion, and the factors controlling these processes. Rills and ephemeral gullies are frequently responsible for a high percentage of total soil erosion, and these features can be considered a good approximation for the minimum erosion rates. With the main purpose of determining the annual soil loss rates in cultivated areas of Central Navarre, a detailed assessment of rainfall and rill and gully erosion was made in 19 small watersheds cultivated with winter grains or vineyards. The study period spanned from 1995 to 2001. For cereal watersheds, soil losses were caused by only one or two rainfall events each year. High erosion rates were observed (0.20-11.50 kg/m2 per year). In vineyards, soil losses were caused by several rainfall events each year, occurring year round. High erosion rates were observed in these vineyards (0.33 y 16.19 kg/m2 per year). No erosion was observed in those cultivated watersheds with no-till practices. It can be concluded that rill and ephemeral gully erosion can be very significant in Mediterranean regions, and much more attention should be paid to the problem.

  17. New empirical relationship between grain size distribution and hydraulic conductivity for ephemeral streambed sediments

    KAUST Repository

    Rosas, Jorge

    2014-07-19

    Grain size distribution, porosity, and hydraulic conductivity were determined for 39 sediment samples collected from ephemeral streams (wadis) in western Saudi Arabia. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly with the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical offsets, were made to produce modified equations that considerably improved the hydraulic conductivity estimates from grain size data for wadi sediments. The Chapuis, Hazen, Kozeny, Slichter, Terzaghi, and Barr equations produced the best correlations, but still had relatively high predictive errors. The Chapius equation was modified for wadi sediments by incorporating mud percentage and the standard deviation (in phi units) into a new equation that reduced the predicted hydraulic conductivity error to ±14.1 m/day. The equation is best applied to ephemeral stream samples that have hydraulic conductive values greater than 2 m/day.

  18. African dance

    OpenAIRE

    Mumberson, Stephen

    2012-01-01

    The RE Open will be shown at the Mall Gallery London and the international section was judged by major practitioners and educators, print dealers and collectors, President of RE and Keeper of the Ashmolean Museum Dr Bren Unwin, John Purcell, Deborah Roslund, Colin Harrison, Dave Ferry, and Mark Hampson. Piece selected "African Dance" print.

  19. "African Connection."

    Science.gov (United States)

    Adelman, Cathy; And Others

    This interdisciplinary unit provides students in grades kindergarten through seventh grade an opportunity to understand diversity through a study of Africa as a diverse continent. The project is designed to provide all elementary students with cultural enrichment by exposing them to African music, art, storytelling, and movement. This project can…

  20. Lessons learned from integrated hydrological modeling of ephemeral catchments with different land uses

    Science.gov (United States)

    Camporese, Matteo; Dean, Joshua; Daly, Edoardo

    2016-04-01

    Land use, in particular tree cover, has a strong influence on evapotranspiration (ET) and thus a large effect on the water budget of ephemeral catchments in arid and semi-arid climates. Unfortunately, the dearth of medium to long-term experimental observations in such areas limits the understanding of the interplay between catchment geology, land use, and climate in driving catchment water balance. Here we use four years (2011-2014) of rainfall, streamflow, and groundwater level measurements to estimate the water balance components in two small, adjacent, ephemeral catchments in a semi-arid region of south-eastern Australia; one catchment was predominantly covered with a eucalypt plantation established in July 2008 and the other was dedicated to grazing pasture. The integrated hydrological model CATHY (CATchment HYdrology) was calibrated against the data in the two catchments using streamflow and groundwater level observations in 2011; the data in the following years (2012-2014) were used for the model validation. The model was able to adequately reproduce the periods of flow in both catchments in all years, although streamflow and groundwater levels were better reproduced in the pasture than in the plantation. This can partly be attributed to the root growth of the trees, which is difficult to estimate; the declining water storage in the eucalypt catchment could only be obtained when including a simple model of root growth dynamics. Other sources of uncertainty could be due to an imperfect description of the surface topography and bedrock geology, which prevent us from accurately reproducing the effects of the tree furrows and subsurface wetness connectivity. The water balances estimated from both data and model showed a significant increase in ET in the eucalypt plantation catchment at the expense of groundwater storage: ET accounted for 95-104% of rainfall in the pasture catchment and 104-119% in the eucalypt catchment across the four years studied. However, the

  1. Evidence for a Noachian-Aged Ephemeral Lake in Gusev Crater, Mars

    Science.gov (United States)

    Ruff, S. W.; Niles, P. B.; Alfano, F.; Clarke, A. B.

    2014-01-01

    Gusev crater was selected as the landing site for the Spirit rover because of the likelihood that it contained an ancient lake. Although outcrops rich in Mg-Fe carbonate dubbed Comanche were discovered in the Noachian-aged Columbia Hills, they were inferred to result from volcanic hydrothermal activity. Spirit encountered other mineral and chemical indicators of aqueous activity, but none was recognized as definitive evidence for a former lake in part because none was associated with obvious lacustrine sedimentary deposits. However, water discharge into Martian crater basins like Gusev may have been episodic, producing only small amounts of sediment and shallow ephemeral lakes. Evaporative precipitation from such water bodies has been suggested as a way of producing the Mg- and Fe-rich carbonates found in ALH84001 and carbonates and salts in some nakhlites a hypothesis we examine for the Comanche carbonate.

  2. 牛暂时热研究进展%The Progress on the Bovine Ephemeral Fever

    Institute of Scientific and Technical Information of China (English)

    黄金海; 丁伯良

    2001-01-01

    Bovine ephemeral fever (BEF)is a acute immunopathological viral disease of cattle in substropical and temperate regions. Flying insect vector(including culcoides and mosquitoes) is responsible for the transmission of BEF. In this review ,the etiology,epidemiology,transmission,ecology,prevention,control ,the researchprogress and trend of BEF has been provided.%牛暂时热是一种发生于热带与温带地区牛的急性、免疫病理性病毒病,包括蚊、蠓在内的多种昆虫参与了该病的传播。本文就BEFV的病原学、流行病学、传播、防制、研究进展及研究趋势做了综述。

  3. Canarian leftist nationalism: The ephemeral Unión del Pueblo Canario

    Directory of Open Access Journals (Sweden)

    Ángel Dámaso Luis León

    2015-10-01

    Full Text Available Union del Pueblo Canario was the most important experience in the history of Canarian leftist nationalism. Emerged in the last years of the seventies, this coalition of individuals and groups from the former antifrancoist left, it development in the islands a powerful but ephemeral political activity. Closely connected with communism, thirdworldism and national liberation movements in Africa Union del Pueblo Canario tried to channel the rising nationalist and worker awakening on the islands. The main objective of this paper is to analyze aspects that produce the appropriate context for the development of the caolition like Union del Pueblo Canario, and also try to describe the factors causing its rise to certain levels of power and how its actions and the changing context of the eighties in the Canary Islands Spain and the world, makes the coalition losing its strength and crumble.

  4. Method for estimating spatially variable seepage loss and hydraulic conductivity in intermittent and ephemeral streams

    Science.gov (United States)

    Niswonger, R.G.; Prudic, D.E.; Fogg, G.E.; Stonestrom, D.A.; Buckland, E.M.

    2008-01-01

    A method is presented for estimating seepage loss and streambed hydraulic conductivity along intermittent and ephemeral streams using streamflow front velocities in initially dry channels. The method uses the kinematic wave equation for routing streamflow in channels coupled to Philip's equation for infiltration. The coupled model considers variations in seepage loss both across and along the channel. Water redistribution in the unsaturated zone is also represented in the model. Sensitivity of the streamflow front velocity to parameters used for calculating seepage loss and for routing streamflow shows that the streambed hydraulic conductivity has the greatest sensitivity for moderate to large seepage loss rates. Channel roughness, geometry, and slope are most important for low seepage loss rates; however, streambed hydraulic conductivity is still important for values greater than 0.008 m/d. Two example applications are presented to demonstrate the utility of the method. Copyright 2008 by the American Geophysical Union.

  5. Rain and channel flow supplements to subsurface water beneath hyper-arid ephemeral stream channels

    Science.gov (United States)

    Kampf, Stephanie K.; Faulconer, Joshua; Shaw, Jeremy R.; Sutfin, Nicholas A.; Cooper, David J.

    2016-05-01

    In hyper-arid regions, ephemeral stream channels are important sources of subsurface recharge and water supply for riparian vegetation, but few studies have documented the subsurface water content dynamics of these systems. This study examines ephemeral channels in the hyper-arid western Sonoran Desert, USA to determine how frequently water recharges the alluvial fill and identify variables that affect the depth and persistence of recharge. Precipitation, stream stage, and subsurface water content measurements were collected over a three-year study at six channels with varying contributing areas and thicknesses of alluvial fill. All channels contain coarse alluvium composed primarily of sands and gravels, and some locations also have localized layers of fine sediment at 2-3 m depth. Rain alone contributed 300-400 mm of water input to these channels over three years, but water content responses were only detected for 36% of the rain events at 10 cm depth, indicating that much of the rain water was either quickly evaporated or taken up by plants. Pulses of water from rain events were detected only in the top meter of alluvium. The sites each experienced ⩽5 brief flow events, which caused transient saturation that usually lasted only a few hours longer than flow. These events were the only apparent source of water to depths >1 m, and water from flow events quickly percolated past the deepest measurement depths (0.5-3 m). Sustained saturation in the shallow subsurface only developed where there was a near-surface layer of finer consolidated sediments that impeded deep percolation.

  6. Obesity and African Americans

    Science.gov (United States)

    ... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6304.pdf [PDF | 3.38MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

  7. Preliminary data on the feeding habits of the endemic species Synodontis koensis Pellegrin, 1933 (Siluriformes, Mochokidae in a West African River (Sassandra River Basin, Côte d’Ivoire

    Directory of Open Access Journals (Sweden)

    Yao S.S.

    2010-06-01

    Full Text Available In the implementation of programs for protection and management of ichthyofauna, endemic species should have high priority in the conservation measures. Their fishery should be based on intimate knowledge of their ecology and biology. Feeding habits of the endemic Mochokid Synodontis koensis were assessed in the Sassandra River (Côte d’Ivoire in relation to the study zone, the specimen sex and size, and the season. Of the 303 stomachs examined, 49 were empty (16%. The fluctuation of the vacuity index indicated that S. koensis feeds more at night. The diet consisted mainly of plant detritus and chironomid larvae. The statistical analysis of the feeding according to the study zones, the sex of fish and the seasons does not show any significant difference between regimes, whereas significant ontogenic shifts in diet were observed.

  8. Monitoring Potential Transport of Radioactive Contaminants in Shallow Ephemeral Channels: FY 2012

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Julianne J.; Mizell, Steve A.; McCurdy, Greg; Campbell, Scott A.

    2012-09-01

    The US Department of Energy (DOE) National Nuclear Security Administration (NNSA), Nevada Site Office (NSO), Environmental Management’s Soils Activity has authorized the Desert Research Institute (DRI) to conduct field assessments of potential sediment transport of contaminated soil from Corrective Action Unit (CAU) 550, Smoky Contamination Area (CA), during precipitation runoff events. CAU 550 includes Corrective Action Sites (CASs) 08-23-03, 08-23-04, 08-23-06, and 08-23-07; these CASs are associated with tests designated Ceres, Smoky, Oberon, and Titania, respectively. Field measurements at the T-4 Atmospheric Test Site, CAU 370, suggest that radioactive material may have migrated along a shallow ephemeral drainage that traverses the site (NNSA/NSO, 2009). (It is not entirely clear how contaminated soils got into their present location at the T-4 Site, but flow to the channel has been redirected and the contamination does not appear to be migrating at present.) Although DRI initially looked at the CAU 370 site, given that it could not be confirmed that migration of contamination into the channel was natural, an alternate study site was selected at CAU 550. Aerial surveys in selected portions of the Nevada National Security Site (NNSS) also suggest that radioactivity may be migrating along ephemeral channels in Areas 3, 8, 11, 18, and 25 (Colton, 1999). Figure 1 shows the results of a low-elevation aerial survey (Colton, 1999) in Area 8. The numbered markers in Figure 1 identify ground zero for three safety experiments conducted in 1958 [Oberon (number 1), Ceres (number 2), and Titania (number 4)] and a weapons effects test conducted in 1964, Mudpack (number 3). This survey suggests contaminants may be migrating down the ephemeral channels that traverse CAU 550. Note particularly the lobe of higher concentration extending southeastward at the south end of the high concentration area marked as number 3 in Figure 1. CAU 550 in Area 8 of the NNSS was selected for

  9. The significance and lag-time of deep through flow: an example from a small, ephemeral catchment with contrasting soil types in the Adelaide Hills, South Australia

    OpenAIRE

    Bestland, E.; S. Milgate; D. Chittleborough; J. VanLeeuwen; Pichler, M.; L. Soloninka

    2009-01-01

    The importance of deep soil-regolith through flow in a small (3.4 km2) ephemeral catchment in the Adelaide Hills of South Australia was investigated by detailed hydrochemical analysis of soil water and stream flow during autumn and early winter rains. In this Mediterranean climate with strong summer moisture deficits, several significant rainfalls are required to generate soil through flow and stream flow [in ephemeral streams]. During autumn 2007, a large (127 mm) drou...

  10. Hindcasting Historical Breeding Conditions for an Endangered Salamander in Ephemeral Wetlands of the Southeastern USA: Implications of Climate Change.

    Directory of Open Access Journals (Sweden)

    Houston C Chandler

    Full Text Available The hydroperiod of ephemeral wetlands is often the most important characteristic determining amphibian breeding success, especially for species with long development times. In mesic and wet pine flatwoods of the southeastern United States, ephemeral wetlands were a common landscape feature. Reticulated flatwoods salamanders (Ambystoma bishopi, a federally endangered species, depend exclusively on ephemeral wetlands and require at least 11 weeks to successfully metamorphose into terrestrial adults. We empirically modeled hydroperiod of 17 A. bishopi breeding wetlands by combining downscaled historical climate-model data with a recent 9-year record (2006-2014 of observed water levels. Empirical models were subsequently used to reconstruct wetland hydrologic conditions from 1896-2014 using the downscaled historical climate datasets. Reconstructed hydroperiods for the 17 wetlands were highly variable through time but were frequently unfavorable for A. bishopi reproduction (e.g., only 61% of years, using a conservative estimate of development time [12 weeks], were conducive to larval development and metamorphosis. Using change-point analysis, we identified significant shifts in average hydroperiod over the last century in all 17 wetlands. Mean hydroperiods were shorter in recent years than at any other point since 1896, and thus less suitable for A. bishopi reproduction. We suggest that climate change will continue to impact the reproductive success of flatwoods salamanders and other ephemeral wetland breeders by reducing the number of years these wetlands have suitable hydroperiods. Consequently, we emphasize the importance of conservation and management for mitigating other forms of habitat degradation, especially maintenance of high quality breeding sites where reproduction can occur during appropriate environmental conditions.

  11. C3PO: Computation Congestion Control (PrOactive) - an algorithm for dynamic diffusion of ephemeral in-network services

    OpenAIRE

    Wang, Liang; Almeida, Mario; Blackburn, Jeremy; Crowcroft, Jon

    2016-01-01

    There is an obvious trend that more and more data and computation are migrating into networks nowadays. Combining mature virtualization technologies with service-centric net- working, we are entering into an era where countless services reside in an ISP network to provide low-latency access. Such services are often computation intensive and are dynamically created and destroyed on demands everywhere in the network to perform various tasks. Consequently, these ephemeral in-network services int...

  12. Confluence Dynamics in an Ephemeral Gully Basin (A Case Study at Rangamati, Paschim Medinipur, West Bengal, India)

    OpenAIRE

    Pravat Kumar Shit; Ramkrishna Maiti

    2013-01-01

    Despite many efforts over the last decades to understand confluence angles of rill or gully, they remain unclear. This paper presents the results of gully confluence angles developed at Rangamati ephemeral gully basin of Paschim Medinipur District, West Bengal in India. The confluence angles are monitored for 3 years (2007-2009) and gradient, discharge and stream power of both parent and tributary stream are measured at each junction. Calibrating the data to existing models shows that Optimal...

  13. Hindcasting Historical Breeding Conditions for an Endangered Salamander in Ephemeral Wetlands of the Southeastern USA: Implications of Climate Change.

    Science.gov (United States)

    Chandler, Houston C; Rypel, Andrew L; Jiao, Yan; Haas, Carola A; Gorman, Thomas A

    2016-01-01

    The hydroperiod of ephemeral wetlands is often the most important characteristic determining amphibian breeding success, especially for species with long development times. In mesic and wet pine flatwoods of the southeastern United States, ephemeral wetlands were a common landscape feature. Reticulated flatwoods salamanders (Ambystoma bishopi), a federally endangered species, depend exclusively on ephemeral wetlands and require at least 11 weeks to successfully metamorphose into terrestrial adults. We empirically modeled hydroperiod of 17 A. bishopi breeding wetlands by combining downscaled historical climate-model data with a recent 9-year record (2006-2014) of observed water levels. Empirical models were subsequently used to reconstruct wetland hydrologic conditions from 1896-2014 using the downscaled historical climate datasets. Reconstructed hydroperiods for the 17 wetlands were highly variable through time but were frequently unfavorable for A. bishopi reproduction (e.g., only 61% of years, using a conservative estimate of development time [12 weeks], were conducive to larval development and metamorphosis). Using change-point analysis, we identified significant shifts in average hydroperiod over the last century in all 17 wetlands. Mean hydroperiods were shorter in recent years than at any other point since 1896, and thus less suitable for A. bishopi reproduction. We suggest that climate change will continue to impact the reproductive success of flatwoods salamanders and other ephemeral wetland breeders by reducing the number of years these wetlands have suitable hydroperiods. Consequently, we emphasize the importance of conservation and management for mitigating other forms of habitat degradation, especially maintenance of high quality breeding sites where reproduction can occur during appropriate environmental conditions.

  14. Maintenance of Ecosystem Nitrogen Limitation by Ephemeral Forest Disturbance: An Assessment using MODIS, Hyperion, and Landsat ETM+

    Science.gov (United States)

    McNeil, Brenden E.; deBeurs, Kirsten M.; Eshleman, Keith N.; Foster, Jane R.; Townsend, Philip A.

    2007-01-01

    Ephemeral disturbances, such as non-lethal insect defoliations and crown damage from meteorological events, can significantly affect the delivery of ecosystem services by helping maintain nitrogen (N) limitation in temperate forest ecosystems. However, the impacts of these disturbances are difficult to observe across the broad-scales at which they affect ecosystem function. Using remotely sensed measures and field data, we find support for the hypothesis that ephemeral disturbances help maintain landscape-wide ecosystem N limitation. Specifically, a phenology-based defoliation index derived from daily MODIS satellite imagery predicts three ecosystem responses from oak-dominated forested watersheds: elevated stream water N export (R(exp 2) = 0.48), decreased foliar N (R(exp 2) = 0.69, assessed with Hyperion imagery), and reduced vegetation growth vigor (R(exp 2) = 0.49, assessed with Landsat ETM+ imagery). The results indicate that ephemeral disturbances and other forest stressors may sustain N limitation by reducing the ability of trees to compete for--and retain--soil available N.

  15. Species traits predict assemblage dynamics at ephemeral resource patches created by carrion.

    Science.gov (United States)

    Barton, Philip S; Cunningham, Saul A; Macdonald, Ben C T; McIntyre, Sue; Lindenmayer, David B; Manning, Adrian D

    2013-01-01

    Carrion is an ephemeral and spatially patchy resource that supports a diverse subset of species linked to nutrient cycling and the decomposition process. A number of studies have separately documented changes in the diversity of plants, arthropods and vertebrates at individual carcasses, but there are few studies that have examined how functional traits of different groups of organisms underpin their responses to carrion patches. We used a carrion addition experiment to compare changes in composition and functional traits of insect and plant assemblages at carcasses compared with control sites. We found that significant changes in insect assemblage evenness and heterogeneity was associated with species' dispersal traits, and that plant assemblage responses to subsequent soil nitrogen changes was most apparent among graminoids and exotic species. Beetles at carcasses were twice as large as their counterparts at control sites during the first week of carrion decomposition, and also had higher wing loadings. Plants with high specific leaf area responded faster to the carcass addition, and twice as many species recolonised the centre of carcasses in exotic-dominated grassland compared with carcasses in native-dominated grassland. These results provide an example of how traits of opportunist species enable them to exploit patchy and dynamic resources. This increases our understanding of how carcasses can drive biodiversity dynamics, and has implications for the way carrion might be managed in ecosystems, such as appropriate consideration of spatial and temporal continuity in carrion resources to promote heterogeneity in nutrient cycling and species diversity within landscapes.

  16. Species traits predict assemblage dynamics at ephemeral resource patches created by carrion.

    Directory of Open Access Journals (Sweden)

    Philip S Barton

    Full Text Available Carrion is an ephemeral and spatially patchy resource that supports a diverse subset of species linked to nutrient cycling and the decomposition process. A number of studies have separately documented changes in the diversity of plants, arthropods and vertebrates at individual carcasses, but there are few studies that have examined how functional traits of different groups of organisms underpin their responses to carrion patches. We used a carrion addition experiment to compare changes in composition and functional traits of insect and plant assemblages at carcasses compared with control sites. We found that significant changes in insect assemblage evenness and heterogeneity was associated with species' dispersal traits, and that plant assemblage responses to subsequent soil nitrogen changes was most apparent among graminoids and exotic species. Beetles at carcasses were twice as large as their counterparts at control sites during the first week of carrion decomposition, and also had higher wing loadings. Plants with high specific leaf area responded faster to the carcass addition, and twice as many species recolonised the centre of carcasses in exotic-dominated grassland compared with carcasses in native-dominated grassland. These results provide an example of how traits of opportunist species enable them to exploit patchy and dynamic resources. This increases our understanding of how carcasses can drive biodiversity dynamics, and has implications for the way carrion might be managed in ecosystems, such as appropriate consideration of spatial and temporal continuity in carrion resources to promote heterogeneity in nutrient cycling and species diversity within landscapes.

  17. Arroyo channel head evolution in a flash-flood-dominated discontinuous ephemeral stream system

    Science.gov (United States)

    DeLong, Stephen B.; Johnson, Joel P.L.; Whipple, Kelin X.

    2014-01-01

    We study whether arroyo channel head retreat in dryland discontinuous ephemeral streams is driven by surface runoff, seepage erosion, mass wasting, or some combination of these hydrogeomorphic processes. We monitored precipitation, overland flow, soil moisture, and headcut migration over several seasonal cycles at two adjacent rangeland channel heads in southern Arizona. Erosion occurred by headward retreat of vertical to overhanging faces, driven dominantly by surface runoff. No evidence exists for erosion caused by shallow-groundwater–related processes, even though similar theater-headed morphologies are sometimes attributed to seepage erosion by emerging groundwater. At our field site, vertical variation in soil shear strength influenced the persistence of the characteristic theater-head form. The dominant processes of erosion included removal of grains and soil aggregates during even very shallow (1–3 cm) overland flow events by runoff on vertical to overhanging channel headwalls, plunge-pool erosion during higher-discharge runoff events, immediate postrunoff wet mass wasting, and minor intra-event dry mass wasting on soil tension fractures developing subparallel to the headwall. Multiple stepwise linear regression indicates that the migration rate is most strongly correlated with flow duration and total precipitation and is poorly correlated with peak flow depth or time-integrated flow depth. The studied channel heads migrated upslope with a self-similar morphologic form under a wide range of hydrological conditions, and the most powerful flash floods were not always responsible for the largest changes in landscape form in this environment. 

  18. A critical discussion on the applicability of Compound Topographic Index (CTI) for predicting ephemeral gully erosion

    Science.gov (United States)

    Casalí, Javier; Chahor, Youssef; Giménez, Rafael; Campo-Bescós, Miguel

    2016-04-01

    The so-called Compound Topographic Index (CTI) can be calculated for each grid cell in a DEM and be used to identify potential locations for ephemeral gullies (e. g.) based on land topography (CTI = A.S.PLANC, where A is upstream drainage area, S is local slope and PLANC is planform curvature, a measure of the landscape convergence) (Parker et al., 2007). It can be shown that CTI represents stream power per unit bed area and it considers the major parameters controlling the pattern and intensity of concentrated surface runoff in the field (Parker et al., 2007). However, other key variables controlling e.g. erosion (e. g. e.) such as soil characteristics, land-use and management, are not had into consideration. The critical CTI value (CTIc) "represents the intensity of concentrated overland flow necessary to initiate erosion and channelised flow under a given set of circumstances" (Parker et al., 2007). AnnAGNPS (Annualized Agriculture Non-Point Source) pollution model is an important management tool developed by (USDA) and uses CTI to locate potential ephemeral gullies. Then, and depending on rainfall characteristics of the period simulated by AnnAGNPS, potential e. g. can become "actual", and be simulated by the model accordingly. This paper presents preliminary results and a number of considerations after evaluating the CTI tool in Navarre. CTIc values found are similar to those cited by other authors, and the e. g. networks that on average occur in the area have been located reasonably well. After our experience we believe that it is necessary to distinguish between the CTIc corresponding to the location of headcuts whose migrations originate the e. g. (CTIc1); and the CTIc necessary to represent the location of the gully networks in the watershed (CTIc2), where gully headcuts are located in the upstream end of the gullies. Most scientists only consider one CTIc value, although, from our point of view, the two situations are different. CTIc1 would represent the

  19. Microbial communities reflect temporal changes in cyanobacterial composition in a shallow ephemeral freshwater lake.

    Science.gov (United States)

    Woodhouse, Jason Nicholas; Kinsela, Andrew Stephen; Collins, Richard Nicholas; Bowling, Lee Chester; Honeyman, Gordon L; Holliday, Jon K; Neilan, Brett Anthony

    2016-06-01

    The frequency of freshwater cyanobacterial blooms is at risk of increasing as a consequence of climate change and eutrophication of waterways. It is increasingly apparent that abiotic data are insufficient to explain variability within the cyanobacterial community, with biotic factors such as heterotrophic bacterioplankton, viruses and protists emerging as critical drivers. During the Australian summer of 2012-2013, a bloom that occurred in a shallow ephemeral lake over a 6-month period was comprised of 22 distinct cyanobacteria, including Microcystis, Dolichospermum, Oscillatoria and Sphaerospermopsis. Cyanobacterial cell densities, bacterial community composition and abiotic parameters were assessed over this period. Alpha-diversity indices and multivariate analysis were successful at differentiating three distinct bloom phases and the contribution of abiotic parameters to each. Network analysis, assessing correlations between biotic and abiotic variables, reproduced these phases and assessed the relative importance of both abiotic and biotic factors. Variables possessing elevated betweeness centrality included temperature, sodium and operational taxonomic units belonging to the phyla Verrucomicrobia, Planctomyces, Bacteroidetes and Actinobacteria. Species-specific associations between cyanobacteria and bacterioplankton, including the free-living Actinobacteria acI, Bacteroidetes, Betaproteobacteria and Verrucomicrobia, were also identified. We concluded that changes in the abundance and nature of freshwater cyanobacteria are associated with changes in the diversity and composition of lake bacterioplankton. Given this, an increase in the frequency of cyanobacteria blooms has the potential to alter nutrient cycling and contribute to long-term functional perturbation of freshwater systems. PMID:26636552

  20. Life cycle assessment of wood wastes: A case study of ephemeral architecture.

    Science.gov (United States)

    Rivela, Beatriz; Moreira, María Teresa; Muñoz, Iván; Rieradevall, Joan; Feijoo, Gumersindo

    2006-03-15

    One of the most commonly used elements in ephemeral architecture is a particleboard panel. These types of wood products are produced from wood wastes and they are used in temporary constructions such as trade fairs. Once the event is over, they are usually disposed into landfills. This paper intends to assess the environmental effects related to the use of these wood wastes in the end-of-life stage. The Life Cycle Assessment (LCA) of two scenarios was performed, considering the recycling of wood waste for particleboard manufacture and energy generation from non-renewable resources (Scenario 1) versus the production of energy from the combustion of wood waste and particleboard manufacture with conventional wooden resources (Scenario 2). A sensitive analysis was carried out taking into account the influence of the percentage of recycled material and the emissions data from wood combustion. According to Ecoindicator 99 methodology, Damage to Human Health and Ecosystem Quality are more significant in Scenario 2 whereas Scenario 1 presents the largest contribution to Damage to Resources. Between the two proposed alternatives, the recycling of wood waste for particleboard manufacture seems to be more favorable under an environmental perspective. PMID:15922411

  1. Experimental infection with bovine ephemeral fever virus and analysis of its antibody response cattle.

    Science.gov (United States)

    Zheng, F Y; Chen, Q W; Li, Z; Gong, X W; Wang, J D; Yin, H

    2016-02-01

    Bovine ephemeral fever (BEF) is an arthropod-borne viral disease that occurs throughout mainland China. LS11 obtained in the 2011 BEF epidemic was a wild strain, and its virulence and antibody response have never been studied in China. Therefore, the issues were investigated in this work. Experimental cattle were intravenously infected with different doses of BEF virus, and some non-infected cattle were simultaneously monitored. Blood and serum samples were collected from all animals over the course of our study. Infected cattle were challenged for a second time with BEF virus to determine protective period of the antibodies. BEF virus was detected in blood samples from infected cattle, but not in monitored cattle. The neutralizing antibodies (nAbs) against BEFV were easier to be detected and persisted for longer periods in cattle infected with higher doses of BEFV than in those infected with lower doses. When the titer of nAbs was equal to 5 or 6, re-infected cattle still could mount a challenge against BEFV. However, after 3 or 6months, when nAbs were no longer apparent, re-infected cattle displayed typical symptoms of BEF. Our findings indicated that vaccination should be performed once the titer of nAb decreased to 5 or 6.

  2. Species traits predict assemblage dynamics at ephemeral resource patches created by carrion.

    Science.gov (United States)

    Barton, Philip S; Cunningham, Saul A; Macdonald, Ben C T; McIntyre, Sue; Lindenmayer, David B; Manning, Adrian D

    2013-01-01

    Carrion is an ephemeral and spatially patchy resource that supports a diverse subset of species linked to nutrient cycling and the decomposition process. A number of studies have separately documented changes in the diversity of plants, arthropods and vertebrates at individual carcasses, but there are few studies that have examined how functional traits of different groups of organisms underpin their responses to carrion patches. We used a carrion addition experiment to compare changes in composition and functional traits of insect and plant assemblages at carcasses compared with control sites. We found that significant changes in insect assemblage evenness and heterogeneity was associated with species' dispersal traits, and that plant assemblage responses to subsequent soil nitrogen changes was most apparent among graminoids and exotic species. Beetles at carcasses were twice as large as their counterparts at control sites during the first week of carrion decomposition, and also had higher wing loadings. Plants with high specific leaf area responded faster to the carcass addition, and twice as many species recolonised the centre of carcasses in exotic-dominated grassland compared with carcasses in native-dominated grassland. These results provide an example of how traits of opportunist species enable them to exploit patchy and dynamic resources. This increases our understanding of how carcasses can drive biodiversity dynamics, and has implications for the way carrion might be managed in ecosystems, such as appropriate consideration of spatial and temporal continuity in carrion resources to promote heterogeneity in nutrient cycling and species diversity within landscapes. PMID:23326549

  3. Heart Disease and African Americans

    Science.gov (United States)

    ... Minority Population Profiles > Black/African American > Heart Disease Heart Disease and African Americans Although African American adults are ... were 30 percent more likely to die from heart disease than non-Hispanic whites. African American women are ...

  4. Vertical Stability of Ephemeral Step-Pool Streams Largely Controlled By Tree Roots, Central Kentucky, USA

    Science.gov (United States)

    Macmannis, K. R.; Hawley, R. J.

    2013-12-01

    The mechanisms controlling stability on small streams in steep settings are not well documented but have many implications related to stream integrity and water quality. For example, channel instability on first and second order streams is a potential source of sediment in regulated areas with Total Maximum Daily Loads (TMDLs) on water bodies that are impaired for sedimentation, such as the Chesapeake Bay. Management strategies that preserve stream integrity and protect channel stability are critical to communities that may otherwise require large capital investments to meet TMDLs and other water quality criteria. To contribute to an improved understanding of ephemeral step-pool systems, we collected detailed hydrogeomorphic data on 4 steep (0.06 - 0.12 meter/meter) headwater streams draining to lower relief alluvial valleys in Spencer County, Kentucky, USA. The step-pool streams (mean step height of 0.47 meter, mean step spacing of 4 meters) drained small undeveloped catchments dominated by early successional forest. Data collection for each of the 4 streams included 2 to 3 cross section surveys, bed material particle counts at cross section locations, and profile surveys ranging from approximately 125 to 225 meters in length. All survey data was systematically processed to understand geometric parameters such as cross sectional area, depth, and top width; bed material gradations; and detailed profile measurements such as slope, pool and riffle lengths, pool spacing, pool depth, step height, and step length. We documented the location, frequency, and type of step-forming materials (i.e., large woody debris (LWD), rock, and tree roots), compiling a database of approximately 130 total steps. Lastly, we recorded a detailed tree assessment of all trees located within 2 meters of the top of bank, detailing the species of tree, trunk diameter, and approximate distance from the top of bank. Analysis of geometric parameters illustrated correlations between channel

  5. Specialist pollinators deplete pollen in the spring ephemeral wildflower Claytonia virginica.

    Science.gov (United States)

    Parker, Alison J; Williams, Neal M; Thomson, James D

    2016-08-01

    Pollinators that collect pollen - and specifically, pollen-specialist bees - are often considered to be the best pollinators of a (host) plant. Although pollen collectors and pollen specialists often benefit host plants, especially in the pollen that they deliver (their pollination "effectiveness"), they can also exact substantial costs because they are motivated to collect as much pollen as possible, reducing the proportion of pollen removed that is subsequently delivered to stigmas (their pollination "efficiency"). From the plant perspective, pollen grains that do not pollinate conspecific stigmas are "wasted", and potentially costly. We measured costs and benefits of nectar-collecting, pollen-collecting, and pollen-specialist pollinator visitation to the spring ephemeral Claytonia virginica. Visits by the pollen-specialist bee Andrena erigeniae depleted pollen quickly and thoroughly. Although all pollinators delivered roughly the same number of grains, the pollen specialist contributed most to C. virginica pollen delivery because of high visitation rates. However, the pollen specialist also removed a large number of grains; this removal may be especially costly because it resulted in the depletion of pollen grains in C. virginica populations. While C. virginica appears to rely on pollen transfer by the pollen specialist in these populations, nectar-collecting visitors could provide the same benefit at a lower cost if their visitation rates increased. Pollen depletion affects a pollinator's value to plants, but is frequently overlooked. If they lower the effectiveness of future floral visitors, visits by A. erigeniae females to C. virginica may be more detrimental than beneficial compared to other pollinators and may, in some circumstances, reduce plant fitness rather than increase it. Therefore, A. erigeniae and C. virginica may vary in their degree of mutualism depending on the ecological context. PMID:27551374

  6. Safety, immunogenicity and duration of immunity elicited by an inactivated bovine ephemeral fever vaccine.

    Directory of Open Access Journals (Sweden)

    Orly Aziz-Boaron

    Full Text Available Bovine ephemeral fever (BEF is an economically important viral vector-borne cattle disease. Several live-attenuated, inactivated and recombinant vaccines have been tested, demonstrating varying efficacy. However, to the best of our knowledge, duration of immunity conferred by an inactivated vaccine has never been reported. In the last decade, Israel has faced an increasing number of BEF outbreaks. The need for an effective vaccine compatible with strains circulating in the Middle East region led to the development of a MONTANIDE™ ISA 206 VG (water-in-oil-in-water, inactivated vaccine based on a local strain. We tested the safety, immunogenicity and duration of immunity conferred by this vaccine. The induced neutralizing antibody (NA response was followed for 493 days in 40 cows vaccinated by different protocols. The vaccine did not cause adverse reactions or a decrease in milk production. All cows [except 2 (6.7% which did not respond to vaccination] showed a significant rise in NA titer of up to 1:256 following the second, third or fourth booster vaccination. Neutralizing antibody levels declined gradually to 1:16 up to 120 days post vaccination. This decline continued in cows vaccinated only twice, whereas cows vaccinated 3 or 4 times showed stable titers of approximately 1:16 for up to 267 days post vaccination. At least three vaccinations with the inactivated BEF vaccine were needed to confer long-lasting immunity. These results may have significant implications for the choice of vaccination protocol with inactivated BEF vaccines. Complementary challenge data should however be added to the above results in order to determine what is the minimal NA response conferring protection from clinical disease.

  7. African Americans and Glaucoma

    Science.gov (United States)

    ... Involved News About Us Donate In This Section African Americans and Glaucoma email Send this article to ... glaucoma is the leading cause of blindness in African Americans. Half of those with glaucoma don't ...

  8. African American Suicide

    Science.gov (United States)

    African American Suicide Fact Sheet Based on 2012 Data (2014) Overview • In 2012, 2,357 African Americans completed suicide in the U.S. Of these, ... 46 per 100,000. • The suicide rate for African Americans ages 10-19 was 2.98 per ...

  9. Linguistic Imperialism: African Perspectives.

    Science.gov (United States)

    Phillipson, Robert

    1996-01-01

    Responds to an article on aspects of African language policy and discusses the following issues: multilingualism and monolingualism, proposed changes in language policy from the Organization for African Unity and South African initiatives, the language of literature, bilingual education, and whose interests English-language teaching is serving.…

  10. Water balance complexities in ephemeral catchments with different land uses: Insights from monitoring and distributed hydrologic modeling

    Science.gov (United States)

    Dean, J. F.; Camporese, M.; Webb, J. A.; Grover, S. P.; Dresel, P. E.; Daly, E.

    2016-06-01

    Although ephemeral catchments are widespread in arid and semiarid climates, the relationship of their water balance with climate, geology, topography, and land cover is poorly known. Here we use 4 years (2011-2014) of rainfall, streamflow, and groundwater level measurements to estimate the water balance components in two adjacent ephemeral catchments in south-eastern Australia, with one catchment planted with young eucalypts and the other dedicated to grazing pasture. To corroborate the interpretation of the observations, the physically based hydrological model CATHY was calibrated and validated against the data in the two catchments. The estimated water balances showed that despite a significant decline in groundwater level and greater evapotranspiration in the eucalypt catchment (104-119% of rainfall) compared with the pasture catchment (95-104% of rainfall), streamflow consistently accounted for 1-4% of rainfall in both catchments for the entire study period. Streamflow in the two catchments was mostly driven by the rainfall regime, particularly rainfall frequency (i.e., the number of rain days per year), while the downslope orientation of the plantation furrows also promoted runoff. With minimum calibration, the model was able to adequately reproduce the periods of flow in both catchments in all years. Although streamflow and groundwater levels were better reproduced in the pasture than in the plantation, model-computed water balance terms confirmed the estimates from the observations in both catchments. Overall, the interplay of climate, topography, and geology seems to overshadow the effect of land use in the study catchments, indicating that the management of ephemeral catchments remains highly challenging.

  11. The evolution of an annual life cycle in killifish: adaptation to ephemeral aquatic environments through embryonic diapause.

    Science.gov (United States)

    Furness, Andrew I

    2016-08-01

    An annual life cycle is characterized by growth, maturity, and reproduction condensed into a single, short season favourable to development, with production of embryos (seeds, cysts, or eggs) capable of surviving harsh conditions which juveniles or adults cannot tolerate. More typically associated with plants in desert environments, or temperate-zone insects exposed to freezing winters, the evolution of an annual life cycle in vertebrates is fairly novel. Killifish, small sexually dimorphic fishes in the Order Cyprinodontiformes, have adapted to seasonally ephemeral water bodies across much of Africa and South America through the independent evolution of an annual life history. These annual killifish produce hardy desiccation-resistant eggs that undergo diapause (developmental arrest) and remain buried in the soil for long periods when fish have perished due to the drying of their habitat. Killifish are found in aquatic habitats that span a continuum from permanent and stable to seasonal and variable, thus providing a useful system in which to piece together the evolutionary history of this life cycle using natural comparative variation. I first review adaptations for life in ephemeral aquatic environments in killifish, with particular emphasis on the evolution of embryonic diapause. I then bring together available evidence from a variety of approaches and provide a scenario for how this annual life cycle evolved. There are a number of features within Aplocheiloidei killifish including their inhabitation of marginal or edge aquatic habitat, their small size and rapid attainment of maturity, and egg properties that make them particularly well suited to the colonization of ephemeral waters. PMID:25969869

  12. The "Bantu Clinic": a genealogy of the African patient as object and effect of South African clinical medicine, 1930-1990.

    Science.gov (United States)

    Butchart, A

    1997-12-01

    This paper is about power, medicine and the identity of the African as a patient of western medicine. From a conventional perspective and as encoded in the current "quest for wholeness" that characterises South African biomedical discourse, the African patient--like any other patient--has always existed as an authentic and subjectified being, whose true attributes and experiences have been denied by the "mechanistic," "reductionistic" and "ethnocentric" practices of clinical medicine. Against this liberal humanist perspective on the body as ontologically independent of power, this paper offers a Foucaultian reading of the African patient as-like any other patient--contingent upon the force relations immanent within and relayed through the clinical practices of biomedicine. A quintessential form of disciplinary micro-power, these fabricate the most intimate recesses of the human body as manageable objects of medical knowledge and social consciousness to make possible the great control strategies of repression, segmentation and liberation that are the usual focus of conventional investigations into the place and function of medicine in society. Since the 1930s when the African body first emerged as a discrete object of a secular clinical knowledge, these have repeatedly transformed the attributes and identity of the African patient, and the paper traces this archaeology of South African clinical perception from then until the 1990s to show how its "quest for wholeness" is not an end point of "discovery" or "liberation," but merely another ephemeral crystallization of socio-medical knowledge in a constantly changing force field of disciplinary power. PMID:9492973

  13. Flow Regime Classification and Hydrological Characterization: A Case Study of Ethiopian Rivers

    Directory of Open Access Journals (Sweden)

    Belete Berhanu

    2015-06-01

    Full Text Available The spatiotemporal variability of a stream flow due to the complex interaction of catchment attributes and rainfall induce complexity in hydrology. Researchers have been trying to address this complexity with a number of approaches; river flow regime is one of them. The flow regime can be quantified by means of hydrological indices characterizing five components: magnitude, frequency, duration, timing, and rate of change of flow. Similarly, this study aimed to understand the flow variability of Ethiopian Rivers using the observed daily flow data from 208 gauging stations in the country. With this process, the Hierarchical Ward Clustering method was implemented to group the streams into three flow regimes (1 ephemeral, (2 intermittent, and (3 perennial. Principal component analysis (PCA is also applied as the second multivariate analysis tool to identify dominant hydrological indices that cause the variability in the streams. The mean flow per unit catchment area (QmAR and Base flow index (BFI show an incremental trend with ephemeral, intermittent and perennial streams. Whereas the number of mean zero flow days ratio (ZFI and coefficient of variation (CV show a decreasing trend with ephemeral to perennial flow regimes. Finally, the streams in the three flow regimes were characterized with the mean and standard deviation of the hydrological variables and the shape, slope, and scale of the flow duration curve. Results of this study are the basis for further understanding of the ecohydrological processes of the river basins in Ethiopia.

  14. The Use of Stereoscopic Satellite Images to Map Rills and Ephemeral Gullies

    Directory of Open Access Journals (Sweden)

    Federica Fiorucci

    2015-10-01

    Full Text Available Accurate mapping and measurement of erosion channels is necessary to accurately estimate the impact of channeled erosion in an area. Field surveys can provide optimal quantitative results, but they are only applicable to small areas. Recently, photogrammetric techniques have been applied to small format aerial photographs that were taken by UAVs. Few studies have applied photogrammetry for mapping and measuring single permanent gullies using very high resolution stereoscopic satellite images. We explore the use of such images to map rills and ephemeral gullies and to measure the length, width and depth of individual erosion channels to estimate the eroded volumes. The proposed methodology was applied to the Collazzone area of Central Italy. All of the channel characteristics were determined using GeoEye-1® panchromatic stereoscopic satellite images of the 48-km2 study area and a 3D floating cursor. We identified, mapped, and measured the lengths of 555 channel segments. The top width and depth could be measured in only a subset of the channel segments (the SMC subset. The SMC data were used to determine the coefficients of the power law relationship between the rill/gully volume and length (V = aLb and the uncertainties due to the channel depth measurements and the cross-sectional shape. The field data of the rill and gully volumes were within the estimated uncertainty. We defined a decision rule to distinguish rills from gullies on the basis of the segment length and applied the corresponding power law relationship that was derived from the SMC subset to estimate the eroded volume of the entire dataset. The erosion values that were calculated at different scales (0.680 Mg∙ha−1 at the catchment scale, 28.4 Mg∙ha−1 on the parcels affected by erosion are consistent with values found in the literature. Our results indicate that erosion at the catchment scale can be considered moderate, whereas the erosion at the field scale exceeds the

  15. Hydraulic Geometry, GIS and Remote Sensing, Techniques against Rainfall-Runoff Models for Estimating Flood Magnitude in Ephemeral Fluvial Systems

    Directory of Open Access Journals (Sweden)

    Rafael Garcia-Lorenzo

    2010-11-01

    Full Text Available This paper shows the combined use of remotely sensed data and hydraulic geometry methods as an alternative to rainfall-runoff models. Hydraulic geometric data and boolean images of water sheets obtained from satellite images after storm events were integrated in a Geographical Information System. Channel cross-sections were extracted from a high resolution Digital Terrain Model (DTM and superimposed on the image cover to estimate the peak flow using HEC-RAS. The proposed methodology has been tested in ephemeral channels (ramblas on the coastal zone in south-eastern Spain. These fluvial systems constitute an important natural hazard due to their high discharges and sediment loads. In particular, different areas affected by floods during the period 1997 to 2009 were delimited through HEC-GeoRAs from hydraulic geometry data and Landsat images of these floods (Landsat‑TM5 and Landsat-ETM+7. Such an approach has been validated against rainfall-surface runoff models (SCS Dimensionless Unit Hydrograph, SCSD, Témez gamma HU Tγ and the Modified Rational method, MRM comparing their results with flood hydrographs of the Automatic Hydrologic Information System (AHIS in several ephemeral channels in the Murcia Region. The results obtained from the method providing a better fit were used to calculate different hydraulic geometry parameters, especially in residual flood areas.

  16. Expression and Antigenic Characterization of the Epitope-G1 of the Bovine Ephemeral Fever Virus Glycoprotein in Pichia pastoris

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The epitope-G1 gene of Bovine ephemeral fever virus (BEFV) glycoprotein was synthesised by PCR and cloned into expression vector pPIC9K to construct recombinant plasmid pPIC9K-G1. Then the pPIC9K-G1 was linearized and transformed into Pichia pastoris GS 115. The recombinant P. pastoris strains were selected by a G418 transformation screen and confirmed by PCR. After being induced with methanol, an expressed protein with 26 kDa molecular weight was obtained, which was much bigger than the predicted size (15.54 kDa). Deglycosylation analysis indicated the recombinant G1 was glycosylated. Western blot and ELISA tests, as well as rabbit immunization and specificity experiments indicated that the target protein had both higher reaction activity and higher immunocompetence and specificity. The recombinant G1 protein could be used as a coating antigen to develop an ELISA kit for bovine ephemeral fever diagnosis.

  17. Freshwater seepages and ephemeral macroalgae proliferation in an intertidal bay: I Effect on benthic community structure and food web

    Science.gov (United States)

    Ouisse, Vincent; Riera, Pascal; Migné, Aline; Leroux, Cédric; Davoult, Dominique

    2011-01-01

    Freshwater seepages and ephemeral Enteromorpha spp. proliferation create heterogeneity at small spatial scale in intertidal sediment. Macrobenthic community diversity was compared between these two disturbances and their respective control points throughout the year 2007 at the Roscoff Aber Bay (Western English Channel, France). In March and September 2007, trophic community pathways of characteristic species were additionally studied using stable isotope ratios of carbon and nitrogen. The low salinity recorded at the freshwater seepage induced the exclusion of the main bioturbator and the presence of omnivores which modified the community composition by biotic pressure. Moreover, food web analyses clearly highlighted a separation at small spatial scale between the two trophic pathways of the impacted area and its control. On the contrary, little differences were observed owning to the ephemeral Enteromorpha spp. proliferation. This suggested a progressive and diffusive disturbance which was applied from the algal mat to the nearby area. However, seasonal changes were observed. First, the algal expansion phase increased the macrofauna diversity and foraminifers' abundance (meiofauna) and then acted as a physical barrier decreasing sediment and water column exchanges and decreasing the fauna diversity. This study highlights the need to take into account small spatial heterogeneity to avoid misinterpretations in intertidal ecology studies.

  18. 古尔班通古特沙漠短命植物分布及其沙面稳定意义%Distribution of ephemeral plants and their significance in dune stabilization in Gurbantunggut Desert

    Institute of Scientific and Technical Information of China (English)

    王雪芹; 蒋进; 雷加强

    2003-01-01

    Based on systematically monitoring plants on dune ridges in the southern part of theGurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation,describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes,analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface andexpounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plantspecies were identified in the study area, 29 of which are ephemeral plants. Ephemeral plantssprouted in early April and completed their life-circle within about two months. Just as aeolian sandactivities came to the strongest stage from April to June in desert regions of northern Xinjiang, thetotal coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was lessthan 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surfacestabilization in the Gurbantunggut Desert. Investigations of vegetation restoration onengineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dunesurface.

  19. Modeling the Contribution of Ephemeral Gully Erosion Under Different Soil Management in An Olive Orchard Microcatchment Using AnnAGNPS Model

    Science.gov (United States)

    In Spain, few studies have been carried out to explore the erosion caused by processes other than interrill and rill erosion, such as gully and ephemeral gully erosion, especially because most of the available studies have evaluated the erosion at plot scale. A study about the en...

  20. Keeping African Masks Real

    Science.gov (United States)

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  1. African agricultural trade

    DEFF Research Database (Denmark)

    Jensen, Hans Grinsted; Sandrey, Ron

    2015-01-01

    This article starts with a profile of African agricultural trade. Using the pre-release version 9.2 of the GTAP database, we then show that the results for tariff elimination on intra-African trade are promising, but these tariff barriers are not as significant as the various trade-related barriers...

  2. African Literature as Celebration.

    Science.gov (United States)

    Achebe, Chinua

    1989-01-01

    Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

  3. Empowering African States

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China helps bring lasting peace and stability to Africa African think tanks expressed a high opinion of China’s role in helping build African peace and security at the first meeting of the China-Africa Think Tanks Forum. The

  4. High pH microbial ecosystems in a newly discovered, ephemeral, serpentinizing fluid seep at Yanartaş (Chimera), Turkey

    Science.gov (United States)

    Meyer-Dombard, D'Arcy R.; Woycheese, Kristin M.; Yargıçoğlu, Erin N.; Cardace, Dawn; Shock, Everett L.; Güleçal-Pektas, Yasemin; Temel, Mustafa

    2015-01-01

    Gas seeps emanating from Yanartaş (Chimera), Turkey, have been documented for thousands of years. Active serpentinization produces hydrogen and a range of carbon gases that may provide fuel for life. Here we report a newly discovered, ephemeral fluid seep emanating from a small gas vent at Yanartaş. Fluids and biofilms were sampled at the source and points downstream. We describe site conditions, and provide microbiological data in the form of enrichment cultures, Scanning electron microscopy (SEM), carbon and nitrogen isotopic composition of solids, and PCR screens of nitrogen cycle genes. Source fluids are pH 11.95, with a Ca:Mg of ~200, and sediments under the ignited gas seep measure 60°C. Collectively, these data suggest the fluid is the product of active serpentinization at depth. Source sediments are primarily calcite and alteration products (chlorite and montmorillonite). Downstream, biofilms are mixed with montmorillonite. SEM shows biofilms distributed homogeneously with carbonates. Organic carbon accounts for 60% of the total carbon at the source, decreasing downstream to <15% as inorganic carbon precipitates. δ13C ratios of the organic carbon fraction of solids are depleted (−25 to −28‰) relative to the carbonates (−11 to −20‰). We conclude that heterotrophic processes are dominant throughout the surface ecosystem, and carbon fixation may be key down channel. δ15N ratios ~3‰, and absence of nifH in extracted DNA suggest that nitrogen fixation is not occurring in sediments. However, the presence of narG and nirS at most locations and in enrichments indicates genomic potential for nitrate and nitrite reduction. This small seep with shallow run-off is likely ephemeral, but abundant preserved microterracettes in the outflow and the surrounding area suggest it has been present for some time. This site and others like it present an opportunity for investigations of preserved deep biosphere signatures, and subsurface-surface interactions

  5. River sedimentation and channel bed characteristics in northern Ethiopia

    Science.gov (United States)

    Demissie, Biadgilgn; Billi, Paolo; Frankl, Amaury; Haile, Mitiku; Lanckriet, Sil; Nyssen, Jan

    2016-04-01

    Excessive sedimentation and flood hazard are common in ephemeral streams which are characterized by flashy floods. The purposes of this study was to investigate the temporal variability of bio-climatic factors in controlling sediment supply to downstream channel reaches and the effect of bridges on local hydro-geomorphic conditions in causing the excess sedimentation and flood hazard in ephemeral rivers of the Raya graben (northern Ethiopia). Normalized Difference Vegetation Index (NDVI) was analyzed for the study area using Landsat imageries of 1972, 1986, 2000, 2005, 2010, and 2012). Middle term, 1993-2011, daily rainfall data of three meteorological stations, namely, Alamata, Korem and Maychew, were considered to analyse the temporal trends and to calculate the return time intervals of rainfall intensity in 24 hours for 2, 5, 10 and 20 years using the log-normal and the Gumbel extreme events method. Streambed gradient and bed material grain size were measured in 22 river reaches (at bridges and upstream). In the study catchments, the maximum NDVI values were recorded in the time interval from 2000 to 2010, i.e. the decade during which the study bridges experienced the most severe excess sedimentation problems. The time series analysis for a few rainfall parameters do not show any evidence of rainfall pattern accountable for an increase in sediment delivery from the headwaters nor for the generation of higher floods with larger bedload transport capacities. Stream bed gradient and bed material grain size data were measured in order to investigate the effect of the marked decrease in width from the wide upstream channels to the narrow recently constructed bridges. The study found the narrowing of the channels due to the bridges as the main cause of the thick sedimentation that has been clogging the study bridges and increasing the frequency of overbank flows during the last 15 years. Key terms: sedimentation, ephemeral streams, sediment size, bridge clogging

  6. River engineering

    NARCIS (Netherlands)

    De Vries, M.

    1993-01-01

    One dimension models - basic eauations, analytical models, numberical models. One dimensional models -suspended load, roughness and resistance of river beds. Solving river problems - tools, flood mitigation, bank protection.

  7. African American Diaspora

    Directory of Open Access Journals (Sweden)

    Angela Brown

    2013-07-01

    Full Text Available The migration of blacks in North America through slavery became united.  The population of blacks past downs a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape from poverty of enslavement and to establish a way of life through tradition. A way of personal freedoms was through getting a good education that lead to a better foundation and a better way of life. With regard to all historic migrations (forced and voluntary, the African Union defined the African diaspora as "[consisting] of people of African origin living outside the continent, irrespective of their citizenship and nationality and who are willing to contribute to the development of the continent and the building of the African Union." Its constitutive act declares that it shall "invite and encourage the full participation of the African diaspora as an important part of our continent, in the building of the African Union." Keywords: literature concepts, African American abstracts

  8. African Peacekeepers in Africa

    DEFF Research Database (Denmark)

    Emmanuel, Nikolas G.

    2015-01-01

    peacekeeping operations in the region. It is important to add that the international community has frequently tried to facilitate the deployment of African armed forces with aid and training. From this reality, the following study goes beyond the current literature by focusing on the international factors...... behind African participation in United Nations (UN) peacekeeping operations in Africa. In doing so, this research focuses on US military aid and foreign troop training from 2002 to 2012, and its impact on African deployments into UN peacekeeping missions in Africa. As can be expected, such third...

  9. Reading the African context

    OpenAIRE

    Musonda Bwalya

    2012-01-01

    There is so much alienation, pain and suffering in our today�s world. In this vein, African Christianity, a voice amongst many voices, should seek to be a transformational religion for the whole of life, affecting all facets of human life towards a fuller life of all in Africa. This article sought to highlight and point to some of the major societal challenges in the African context which African Christianity, as a life-affirming religion, should continue to embrace, re-embrace and engag...

  10. Capitalism and African business cultures

    OpenAIRE

    Taylor, Scott D.

    2014-01-01

    Scholars and practitioners once commonly linked 'African culture' to a distinctive 'African capitalism', at odds with genuine capitalism and the demands of modern business. Yet contemporary African business cultures reveal that a capitalist ethos has taken hold within both state and society. The success and visibility of an emergent, and celebrated, class of African big business reveals that business and profit are culturally acceptable. Existing theories of African capitalism are ill-equippe...

  11. Quantifying Irrigation Return Flows Using Stable Isotopes of Water along the South Platte River, Colorado USA

    Science.gov (United States)

    Sanford, W. E.; Davila Olmo, K.; Stednick, J. D.

    2011-12-01

    As the South Platte River flows from Denver, CO to the Nebraska border it crosses urban and agricultural settings which affect water quality and quantity. This reach of the river is highly regulated, with numerous diversions, off-channel reservoirs, and flow-augmentation projects. Water in the river is used 7 different times between Denver and the state line. Much of the water diverted from the river is used for irrigation. A significant portion of this water returns to the river as groundwater flow, often during times of low stream flow. Groundwater return flows, coupled with wastewater treatment plant and reservoir storage, have turned the once ephemeral river into a perennial one. The goal of this research was to determine if the stable isotopes of water (δ 2H and δ18O) in the river can be used to identify and to help quantify groundwater return flows to the river. Water samples were collected and analyzed for their isotopic signature at 17 sites from Denver to Julesburg. Nine rounds of samples were collected from June 2009 to June 2010. Well defined linear patterns of isotope ratios are observed on individual sampling events indicating that the water in the river is becoming enriched as it moves downstream. The enrichment is caused by evaporation from irrigation waters and their discharge to the river as groundwater return flows. These promising results indicate that it may be possible to quantify irrigation return flow to the South Platte River using the stable isotopes of water.

  12. Archaean Crustal Growth, Proterozoic Terrane Amalgamation and the Pan-African Orogeny, as Recorded in the NE African Sedimentary Record.

    Science.gov (United States)

    Najman, Y.; Fielding, L.; Millar, I.; Butterworth, P.; Andò, S.; Padoan, M.; Barfod, D. N.; Kneller, B. C.

    2015-12-01

    The cratons of Central Africa are formed of various blocks of Archaean and Palaeoproterozoic crust, flanked or truncated by Palaeoproterozoic to Mesoproterozoic orogenic belts. The geology of east Africa has largely been shaped by the events of the Pan-African Orogeny when east and west Gondwana collided to form 'Greater Gondwana' at the end of the Neoproterozoic. The Pan-African orogeny in NE Africa involved the collision of Archaean cratons and the Saharan Metacraton with the Arabian Nubian Shield, a terrane comprising Neoproterozoic juvenile oceanic island arcs. Phanerozoic cover sedimentary rocks, eroded from the Pan-African orogenies, blanket much of NE Africa. Detrital data from these Phanerozoic cover sedimentary rocks, and modern rivers draining both the cover the basement, provide a wealth of information on basement evolution, of particular relevance for regions where the basement itself is poorly exposed due to ancient or modern sedimentary cover. From samples collected in Uganda, Ethiopia, Sudan and Egypt, we provide combined U-Pb and Hf-isotope zircon, U-Pb rutile and Ar-Ar mica datasets, heavy mineral analyses, and bulk trace element data, from Archaean basement, Phanerozoic cover and modern river sediment from the Nile and its tributaries to document the evolution of the North African crust. The data document early crust-forming events in the Congo Craton and Sahara Metacraton, phased development of the Arabian Nubian Shield culminating in the Neoproterozoic assembly of Gondwana during the Pan African Orogeny, and the orogen's subsequent erosion, with deposition of voluminous Phanerozoic cover.

  13. A comparison of methane flux rates from the margins of a permanent wetland and an ephemeral wetland in southern Minnesota

    Science.gov (United States)

    Nelson, L. C.; Kannenberg, S.; Ludwig, S.; Rich, H.; Spawn, S.; Porterfield, J.; Schade, J. D.

    2012-12-01

    The degree of expansion and contraction of wetlands is likely to change as climate change alters drought and precipitation events. As wetland size becomes more dynamic, the extent and duration of inundation of soils on their margins will change. The amount of methane released from wetlands will also change since methanogens thrive in anoxic, saturated soils. It is critical to study the factors that influence methane emissions from wetlands because methane is 20 times more effective at trapping heat in the atmosphere than carbon dioxide. The objective of our research was to compare methane flux rates from the margins of a permanent wetland and an ephemeral wetland. We also assessed the impact of Reed Canary Grass (Phalaris arundinacea) on transport of methane from the soil to the atmosphere. Methane flux emissions were measured using portable gas flux chambers at Bakko Pond (a permanent wetland) and East Coyote Pond (an ephemeral wetland) on the St. Olaf College Natural Lands in southern Minnesota. At each wetland, we measured methane emissions from plots of clipped and unclipped Reed Canary Grass. We found no statistical difference between clipped and unclipped plots, suggesting that a diffusive gas transport system rather than a coupling of a diffusive and convective gas transport emits methane. We also found that the average rate of methane flux was higher at East Coyote Pond at both the wet Reed Canary Grass and dry Reed Canary Grass sites, when compared to the dry Reed Canary Grass site at Bakko Pond. Higher methane emission rates at East Coyote Pond is consistent with the characteristics of a wetland with a shallow bank where marginal soil is frequently inundated with water, creating a favorable anoxic environment for active methanogens. In contrast, Bakko Pond has a steep embankment, reducing soil saturation. We also found that soil moisture was strongly correlated with methane flux rates between the sites and over time within a site. Overall, our results

  14. Evaluating recharge to an ephemeral dryland stream using a hydraulic model and water, chloride and isotope mass balance

    Science.gov (United States)

    Dogramaci, Shawan; Firmani, Giovanni; Hedley, Paul; Skrzypek, Grzegorz; Grierson, Pauline F.

    2015-02-01

    Dewatering associated with mining below water table to achieve dry mining conditions may exert significant pressure on water balance in terms of lowering the water table and change in the dynamics of interactions between surface water and groundwater. The discharge of surplus mine water into ephemeral streams may also affect the water balance, by elevating groundwater levels and altering the exchange rate between streams and underlying aquifers. However, it is unclear whether volumes and recharge processes are within the range of natural variability. Here, we present a case study of an ephemeral creek in the semi-arid Hamersley Basin of northwest Australia that has received continuous mine discharge for more than six years. We used a numerical model coupled with repeated measurements of water levels, chloride concentrations and the hydrogen and oxygen stable isotope composition (δ2H and δ18O) to estimate longitudinal evapotranspiration and recharge rates along a 27 km length of Weeli Wolli Creek. We found that chloride increased from 73 to 120 mg/L across this length, while δ18O increased from -8.2‰ to -7.00‰. Groundwater is directly connected to the creek for the first 13 km and recharge rates are negligible. Below this point, the creek flows over a highly permeable aquifer and water loss by recharge increases to a maximum rate of 4.4 mm/d, which accounts for ∼65% of the total water discharged to the creek. Evapotranspiration losses account for the remaining ∼35%. The calculated recharge from continuous flow due to surplus water discharge is similar to that measured for rainfall-driven flood events along the creek. Groundwater under the disconnected section of the creek is characterised by a much lower Cl concentration and more depleted δ18O value than mining discharge water but is similar to flood water generated by large episodic rainfall events. Our results suggest that the impact of recharge from continuous flow on the water balance of the creek

  15. The contemporary geomorphology of the Letaba River in the Kruger National Park

    Directory of Open Access Journals (Sweden)

    B.P. Moon

    2001-07-01

    Full Text Available The Letaba River drains part of Northern Province in north-east South Africa. Its catchment has been modified significantly by human activity which has affected the flow regime; it experiences only ephemeral flows through the Kruger National Park to its confluence with the Olifants River. Although the Letaba is similar to the other rivers in the Kruger National Park in that it displays some bedrock influenced channel features, increased sediment delivery from the degraded catchment upstream has resulted in extensive alluviation within the channel. Sections of channel flowing over bedrock with no sediment covering are rare, and the river comprises a series of channel types: mixed anastomosing, alluvial braided, mixed pool-rapid and alluvial single thread. Each is characterised by a different combination of morphological units which relate to the degree of alluviation in the channel. These channel types are described in detail and inferences are made concerning their formation and maintenance from field observation and measurement.

  16. Berg River Textiles - Cleaner Production Option Report

    DEFF Research Database (Denmark)

    Wenzel, Henrik; Schneider, Zsig

    In October and November 2002 meetings were held between Berg River Textiles, Mr. Juan Laubscher, and external consultants from the South African – Danish Cleaner Textile Production Project, Mr. Zsig Schneider and Mr. Henrik Wenzel. This team of people collected information on recipes and flow...

  17. A further investigation into the bioaccumulation of lead and zinc in the organs and tissues of the African sharptooth catfish, Glorias gariepinus from two localities in the Olifants River, Kruger National Park

    Directory of Open Access Journals (Sweden)

    H.M. Marx

    1998-02-01

    Full Text Available The bioaccumulation of lead and zinc in the gills, liver, muscle and skin of Glorias gariepinus from two locations, Mamba and Balule, on the Olifants River within the Kruger National Park is reported here. Over a one year period (1994, four surveys (February, May, July and November were undertaken. Atomic absorption spectrophotometry was used to determine the concentrations of both metals in the tissues. The gills were the major route of uptake, with the liver accumulating high lead and zinc concentrations. The concentration of metals in the fish found at Mamba and Balule were found to be significantly different from each other. However, it could not be established at which location the greatest amount of bioaccumulation had taken place. The influences of temperature, alkalinity, salinity and pH on metal toxicity, bioavailability and bioaccumulation rates are discussed in detail. It is imperative that pollution levels in the Olifants River and its effect on fish is continually monitored and captured, so as to main- tain and conserve this river and the biota dependant on it.

  18. The Ephemeral Cathedral of Créteil : a 350m2 lightweight gridshell structure made of 2 kilometers of GFRP tubes

    OpenAIRE

    du Peloux, Lionel; Tayeb, Frédéric; Caron, Jean-François; Baverel, Olivier

    2015-01-01

    International audience The Ephemeral Cathedral of Créteil (Paris, France) is a gridshell structure made of composite materials. Built in 2013, this religious edifice of 350m 2 is a temporary church meant to gather the parishioners during the two-years renovation of their permanent cathedral. This large-scale prototype (Figure 1) represents a first in the building industry, which still shows excessive apprehension for the use of non-traditional materials such as composites, especially when ...

  19. Sensitivity of growth and biomass allocation patterns to increasing nitrogen: a comparison between ephemerals and annuals in the Gurbantunggut Desert, north-western China

    Science.gov (United States)

    Zhou, Xiaobing; Zhang, Yuanming; Niklas, Karl J.

    2014-01-01

    Background and Aims Biomass accumulation and allocation patterns are critical to quantifying ecosystem dynamics. However, these patterns differ among species, and they can change in response to nutrient availability even among genetically related individuals. In order to understand this complexity further, this study examined three ephemeral species (with very short vegetative growth periods) and three annual species (with significantly longer vegetative growth periods) in the Gurbantunggut Desert, north-western China, to determine their responses to different nitrogen (N) supplements under natural conditions. Methods Nitrogen was added to the soil at rates of 0, 0·5, 1·0, 3·0, 6·0 and 24·0 g N m−2 year−1. Plants were sampled at various intervals to measure relative growth rate and shoot and root dry mass. Key Results Compared with annuals, ephemerals grew more rapidly, increased shoot and root biomass with increasing N application rates and significantly decreased root/shoot ratios. Nevertheless, changes in the biomass allocation of some species (i.e. Erodium oxyrrhynchum) in response to the N treatment were largely a consequence of changes in overall plant size, which was inconsistent with an optimal partitioning model. An isometric log shoot vs. log root scaling relationship for the final biomass harvest was observed for each species and all annuals, while pooled data of three ephemerals showed an allometric scaling relationship. Conclusions These results indicate that ephemerals and annuals differ observably in their biomass allocation patterns in response to soil N supplements, although an isometric log shoot vs. log root scaling relationship was maintained across all species. These findings highlight that different life history strategies behave differently in response to N application even when interspecific scaling relationships remain nearly isometric. PMID:24287812

  20. Strong potential for endozoochory by waterfowl in a rare, ephemeral wetland plant species, Astragalus contortuplicatus (Fabaceae

    Directory of Open Access Journals (Sweden)

    Ádám Lovas-Kiss

    2015-10-01

    Full Text Available It was proposed previously that passive dispersal by migratory aquatic birds explain the widespread distribution of many wetland organisms. Several experimental studies have shown that many widespread wetland plant species can be readily dispersed within the guts of Anatidae. However, it is unclear whether plants with a more restricted distribution are able to disperse via waterbirds. This paper addresses the dispersal ability and germination ecology of the little-known Hungarian milkvetch Astragalus contortuplicatus, which occurs on banks of continental rivers and has a limited and unpredictable distribution. To test whether limited capacity for endozoochory by waterfowl could explain the sporadic appearance of this species, we force-fed ten captive mallards (Anas platyrhynchos with 100 milkvetch seeds each. Droppings were collected for up to 45 h after feeding. Intact and viable seeds were found in the droppings of each mallard, and altogether 24.7% of seeds fed were recovered intact. The proportion of retrieved seeds that germinated (27.0% was significantly higher than that of untreated control seeds (0.5%, but significantly lower than that of mechanically scarified seeds (96.0%. Retrieved seeds that germinated developed into healthy mature plants. Given the average flight velocity of mallards, seeds of A. contortuplicatus may travel up to 1600 km inside the digestive tract of migrating individuals. Our results suggest that avian vectors may be more important for the dispersal of rare higher plants (especially those with a hard seed-coat than hitherto considered. Moreover, they suggest that rarity does not necessarily indicate limited dispersal ability, and may instead be explained by specific habitat requirements.

  1. Local structuring factors of invertebrate communities in ephemeral freshwater rock pools and the influence of more permanent water bodies in the region

    Science.gov (United States)

    Jocque, M.; Graham, T.; Brendonck, L.

    2007-01-01

    We used three isolated clusters of small ephemeral rock pools on a sandstone flat in Utah to test the importance of local structuring processes on aquatic invertebrate communities. In the three clusters we characterized all ephemeral rock pools (total: 27) for their morphometry, and monitored their water quality, hydrology and community assemblage during a full hydrocycle. In each cluster we also sampled a set of more permanent interconnected freshwater systems positioned in a wash, draining the water from each cluster of rock pools. This design allowed additional testing for the potential role of more permanent water bodies in the region as source populations for the active dispersers and the effect on the community structure in the rock pools. Species richness and community composition in the rock pools correlated with level of permanence and the ammonia concentration. The length of the rock pool inundation cycle shaped community structure, most probably by inhibiting colonization by some taxa (e.g. tadpoles and insect larvae) through developmental constraints. The gradient in ammonia concentrations probably reflects differences in primary production. The more permanent water bodies in each wash differed both environmentally and in community composition from the connected set of rock pools. A limited set of active dispersers was observed in the rock pools. Our findings indicate that aquatic invertebrate communities in the ephemeral rock pools are mainly structured through habitat permanence, possibly linked with biotic interactions and primary production. ?? 2007 Springer Science+Business Media B.V.

  2. Super-Eddington Accretion in the Ultraluminous X-ray Source NGC1313 X-2: An Ephemeral Feast

    CERN Document Server

    Weng, Shan-Shan; Zhao, Hai-Hui

    2013-01-01

    We investigate the X-ray spectrum, variability and the surrounding ionized bubble of NGC1313 X-2 to explore the physics of super-Eddington accretion. Beyond the Eddington luminosity, the accretion disk of NGC1313 X-2 is truncated at a large radius ($\\sim$ 50 times of innermost stable circular orbit), and displays the similar evolution track with both luminous Galactic black-hole and neutron star X-ray binaries. In super-critical accretion, the speed of radiatively driven outflows from the inner disk is mildly relativistic. Such ultra-fast outflows would be over ionized and might produce weak Fe K absorption lines, which may be detected by the coming X-ray mission {\\it Astro-H}. If the NGC1313 X-2 is a massive stellar X-ray binary, the high luminosity indicates that an ephemeral feast is held in the source. That is, the source must be accreting at a hyper-Eddington mass rate to give the super-Eddington emission over $\\sim 10^{4}-10^{5}$ yr. The expansion of the surrounding bubble nebula with a velocity of $\\si...

  3. Confluence Dynamics in an Ephemeral Gully Basin (A Case Study at Rangamati, Paschim Medinipur, West Bengal, India

    Directory of Open Access Journals (Sweden)

    Pravat Kumar Shit

    2013-04-01

    Full Text Available Despite many efforts over the last decades to understand confluence angles of rill or gully, they remain unclear. This paper presents the results of gully confluence angles developed at Rangamati ephemeral gully basin of Paschim Medinipur District, West Bengal in India. The confluence angles are monitored for 3 years (2007-2009 and gradient, discharge and stream power of both parent and tributary stream are measured at each junction. Calibrating the data to existing models shows that Optimal Confluence model (Roy, 1983 is better applicable to the present study where average value of symmetry ratio becomes, 0.300 and the value of exponent ‘x’ becomes -0.20. The plot experiment at laboratory under simulated rain shows the tendency of Tran’s link development and downward migration of the lower most junctions due to availability of maximum discharge under constant slope condition. In the situation of homogeneous soil resistance, equal distributed rain and general gradient, local variation of energy is observed due to localized erosion or deposition and associated local variation of gradient in micro scale. Angles of junction are changed in response to the variation of gradient (S, discharge (Q and Sediment Yield (SY. These changes are episodic in nature and so no average rate can be estimated. The junction migrates both upstream and downstream depending on the relative importance of deposition, erosion and associated change in junction angle.

  4. Spatial and temporal transcriptome changes occurring during flower opening and senescence of the ephemeral hibiscus flower, Hibiscus rosa-sinensis

    Science.gov (United States)

    Trivellini, Alice; Cocetta, Giacomo; Hunter, Donald A.; Vernieri, Paolo; Ferrante, Antonio

    2016-01-01

    Flowers are complex systems whose vegetative and sexual structures initiate and die in a synchronous manner. The rapidity of this process varies widely in flowers, with some lasting for months while others such as Hibiscus rosa-sinensis survive for only a day. The genetic regulation underlying these differences is unclear. To identify key genes and pathways that coordinate floral organ senescence of ephemeral flowers, we identified transcripts in H. rosa-sinensis floral organs by 454 sequencing. During development, 2053 transcripts increased and 2135 decreased significantly in abundance. The senescence of the flower was associated with increased abundance of many hydrolytic genes, including aspartic and cysteine proteases, vacuolar processing enzymes, and nucleases. Pathway analysis suggested that transcripts altering significantly in abundance were enriched in functions related to cell wall-, aquaporin-, light/circadian clock-, autophagy-, and calcium-related genes. Finding enrichment in light/circadian clock-related genes fits well with the observation that hibiscus floral development is highly synchronized with light and the hypothesis that ageing/senescence of the flower is orchestrated by a molecular clock. Further study of these genes will provide novel insight into how the molecular clock is able to regulate the timing of programmed cell death in tissues. PMID:27591432

  5. Comparative orbital evolution of transient Uranian co-orbitals: exploring the role of ephemeral multi-body mean motion resonances

    CERN Document Server

    Marcos, C de la Fuente

    2014-01-01

    Uranus has three known co-orbitals: 83982 Crantor (2002 GO9), 2010 EU65 and 2011 QF99. Here, we perform a comparative analysis of the orbital evolution of these transient co-orbitals to understand better how they got captured in the first place and what makes them dynamically unstable. We also look for additional temporary Uranian co-orbital candidates among known objects. Our N-body simulations show that the long-term stability of 2011 QF99 is controlled by Jupiter and Neptune; it briefly enters the 1:7 mean motion resonance with Jupiter and the 2:1 with Neptune before becoming a Trojan and prior to leaving its tadpole orbit. During these ephemeral two-body mean motion resonance episodes, apsidal corotation resonances are also observed. For known co-orbitals, Saturn is the current source of the main destabilizing force but this is not enough to eject a minor body from the 1:1 commensurability with Uranus. These objects must enter mean motion resonances with Jupiter and Neptune in order to be captured or beco...

  6. African-Americans and Alzheimer's

    Science.gov (United States)

    ... Share Plus on Google Plus African-Americans and Alzheimer's alz.org | IHaveAlz Introduction 10 Warning Signs Brain ... African-Americans are at a higher risk for Alzheimer's disease. Many Americans dismiss the warning signs of ...

  7. African Cultural Astronomy

    CERN Document Server

    Holbrook, Jarita C; Medupe, R. Thebe; Current Archaeoastronomy and Ethnoastronomy research in Africa

    2008-01-01

    Astronomy is the science of studying the sky using telescopes and light collectors such as photographic plates or CCD detectors. However, people have always studied the sky and continue to study the sky without the aid of instruments this is the realm of cultural astronomy. This is the first scholarly collection of articles focused on the cultural astronomy of Africans. It weaves together astronomy, anthropology, and Africa. The volume includes African myths and legends about the sky, alignments to celestial bodies found at archaeological sites and at places of worship, rock art with celestial imagery, and scientific thinking revealed in local astronomy traditions including ethnomathematics and the creation of calendars. Authors include astronomers Kim Malville, Johnson Urama, and Thebe Medupe; archaeologist Felix Chami, and geographer Michael Bonine, and many new authors. As an emerging subfield of cultural astronomy, African cultural astronomy researchers are focused on training students specifically for do...

  8. African Indigenous Cattle: Unique Genetic Resources in a Rapidly Changing World.

    Science.gov (United States)

    Mwai, Okeyo; Hanotte, Olivier; Kwon, Young-Jun; Cho, Seoae

    2015-07-01

    At least 150 indigenous African cattle breeds have been named, but the majority of African cattle populations remain largely uncharacterized. As cattle breeds and populations in Africa adapted to various local environmental conditions, they acquired unique features. We know now that the history of African cattle was particularly complex and while several of its episodes remain debated, there is no doubt that African cattle population evolved dramatically over time. Today, we find a mosaic of genetically diverse population from the purest Bos taurus to the nearly pure Bos indicus. African cattle are now found all across the continent, with the exception of the Sahara and the river Congo basin. They are found on the rift valley highlands as well as below sea level in the Afar depression. These unique livestock genetic resources are in danger to disappear rapidly following uncontrolled crossbreeding and breed replacements with exotic breeds. Breeding improvement programs of African indigenous livestock remain too few while paradoxically the demand of livestock products is continually increasing. Many African indigenous breeds are endangered now, and their unique adaptive traits may be lost forever. This paper reviews the unique known characteristics of indigenous African cattle populations while describing the opportunities, the necessity and urgency to understand and utilize these resources to respond to the needs of the people of the continent and to the benefit of African farmers. PMID:26104394

  9. African names for American plants

    NARCIS (Netherlands)

    Andel, van T.R.

    2015-01-01

    African slaves brought plant knowledge to the New World, sometimes applying it to related plants they found there and sometimes bringing Old World plants with them. By tracing the linguistic parallels between names for plants in African languages and in communities descended from African slaves, pie

  10. The Struggles over African Languages

    Science.gov (United States)

    Maseko, Pam; Vale, Peter

    2016-01-01

    In this interview, African Language expert Pam Maseko speaks of her own background and her first encounter with culture outside of her mother tongue, isiXhosa. A statistical breakdown of South African languages is provided as background. She discusses Western (originally missionary) codification of African languages and suggests that this approach…

  11. Spatio-temporal complexity of chimpanzee food: How cognitive adaptations can counteract the ephemeral nature of ripe fruit.

    Science.gov (United States)

    Janmaat, Karline R L; Boesch, Christophe; Byrne, Richard; Chapman, Colin A; Goné Bi, Zoro B; Head, Josephine S; Robbins, Martha M; Wrangham, Richard W; Polansky, Leo

    2016-06-01

    Ecological complexity has been proposed to play a crucial role in primate brain-size evolution. However, detailed quantification of ecological complexity is still limited. Here we assess the spatio-temporal distribution of tropical fruits and young leaves, two primary chimpanzee (Pan troglodytes) foods, focusing on the predictability of their availability in individual trees. Using up to 20 years of information on monthly availability of young leaf, unripe and ripe fruit in plant species consumed by chimpanzees from tropical forests in East, Central, and West Africa, we estimated: (1) the forest-wide frequency of occurrence of each food type and (2) the predictability of finding ripe fruit-bearing trees, focusing on the timing, frequency, and amount of ripe fruit present. In all three forests, at least half of all encountered trees belonged to species that chimpanzees were known to feed on. However, the proportion of these trees bearing young leaves and fruit fluctuated widely between months. Ripe fruit was the most ephemeral food source, and trees that had more than half of their crown filled were at least nine times scarcer than other trees. In old growth forests only one large ripe fruit crop was on average encountered per 10 km. High levels of inter-individual variation in the number of months that fruit was present existed, and in some extreme cases individuals bore ripe fruit more than seven times as often as conspecifics. Some species showed substantially less variation in such ripe fruit production frequencies and fruit quantity than others. We hypothesize that chimpanzees employ a suite of cognitive mechanisms, including abilities to: (1) generalize or classify food trees; (2) remember the relative metrics of quantity and frequency of fruit production across years; and (3) flexibly plan return times to feeding trees to optimize high-energy food consumption in individual trees, and efficient travel between them. Am. J. Primatol. 78:626-645, 2016. © 2016

  12. Risk analysis and seroprevalence of bovine ephemeral fever virus in cattle in the Kingdom of Saudi Arabia.

    Science.gov (United States)

    Zaghawa, Ahmed; Housawi, Fadhel Mohamed Taher; Al-Naeem, Abdulmohsen; Al-Nakhly, Hassan; Kamr, Ahmed; Toribio, Ramiro

    2016-03-01

    Bovine ephemeral fever virus (BEFV) is an arthropod-borne rhabdovirus that causes disabling clinical signs and major economic losses in cattle and water buffalo. The disease is well documented in Asia, Africa, and the Middle East; however, the seroprevalence of BEFV in different regions and bovine breeds in the Kingdom of Saudi Arabia (KSA) is unknown. The aim of this study was to analyze risk factors which affect the prevalence of antibodies against BEFV in small herds of cattle in four geographical regions of KSA. A total of 1480 serum samples from non-BEFV vaccinated small herds of cattle were collected from the Eastern, Jizan, Qasim, and Riyadh regions (370 samples per region) during the summer of 2010. Serum neutralization test was used to detect antibodies against BEFV. There was a significant effect of region, breed, sex, and age on the seroprevalence of BEFV. Seropositive ratios were 18, 18, 26, and 12 % for the Eastern, Jizan, Qasim, and Riyadh regions, respectively (P = 0.00002); 23.2 % for dairy and 13.7 % for non-dairy breeds (P = 0.00004); 24.4 % for males and 14.6 % for females (P = 0.00004); and 15.4, 29.1, and 11.4 % for animals 3 years, respectively (P < 0.001). Risk analysis showed a significant effect of different regions of KSA on the seroprevalence of BEFV. Host risk factors (age, sex, and breed) showed also a significant effect on the seroprevalence of BEFV. This indicates active circulation of this virus in small herds of cattle. Insect control strategies and BEFV vaccination programs during the spring are recommended to reduce the spread of BEFV and minimize subsequent economic losses as this is adopted in many enzootic countries. PMID:26676243

  13. Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai'i Island.

    Science.gov (United States)

    Stacy, E A; Johansen, J B; Sakishima, T; Price, D K

    2016-09-01

    Intraspecific hybrid zones involving long-lived woody species are rare and can provide insights into the genetic basis of early-diverging traits in speciation. Within the landscape-dominant Hawaiian tree, Metrosideros polymorpha, are morphologically distinct successional varieties, incana and glaberrima, that dominate new and old lava flows, respectively, below 1200 me on volcanically active Hawai'i Island, with var. glaberrima also extending to higher elevations and bogs. Here, we use morphological measurements on 86 adult trees to document the presence of an incana-glaberrima hybrid zone on the 1855 Mauna Loa lava flow on east Hawai'i Island and parent-offspring analysis of 1311 greenhouse seedlings from 71 crosses involving 72 adults to estimate heritabilities and genetic correlations among vegetative traits. Both the variation in adult leaf pubescence at the site and the consistency between adult and offspring phenotypes suggest the presence of two hybrid classes, F1s and var. incana backcrosses, as would be expected on a relatively young lava flow. Nine nuclear microsatellite loci failed to distinguish parental and hybrid genotypes. All four leaf traits examined showed an additive genetic basis with moderate to strong heritabilities, and genetic correlations were stronger for the more range-restricted var. incana. The differences between varieties in trait values, heritabilities and genetic correlations, coupled with high genetic variation within but low genetic variation between varieties, are consistent with a multi-million-year history of alternating periods of disruptive selection in contrasting environments and admixture in ephemeral hybrid zones. Finally, the contrasting genetic architectures suggest different evolutionary trajectories of leaf traits in these forms. PMID:27301333

  14. The African landscape through space and time

    Science.gov (United States)

    Paul, Jonathan D.; Roberts, Gareth G.; White, Nicky

    2014-06-01

    It is generally accepted that Cenozoic epeirogeny of the African continent is moderated by convective circulation of the mantle. Nevertheless, the spatial and temporal evolution of Africa's "basin-and-swell" physiography is not well known. Here we show how continental drainage networks can be used to place broad constraints on the pattern of uplift through space and time. First, we assemble an inventory of 710 longitudinal river profiles that includes major tributaries of the 10 largest catchments. River profiles have been jointly inverted to determine the pattern of uplift rate as a function of space and time. Our inverse model assumes that shapes of river profiles are controlled by uplift rate history and modulated by erosional processes, which can be calibrated using independent geologic evidence (e.g., marine terraces, volcanism and thermochronologic data). Our results suggest that modern African topography started to develop ˜30 Myr ago when volcanic swells appeared in North and East Africa. During the last 15-20 Myr, subequatorial Africa was rapidly elevated, culminating in the appearance of three large swells that straddle southern and western coasts. Our results enable patterns of sedimentary flux at major deltas to be predicted and tested. We suggest that the evolution of drainage networks is dominated by rapid upstream advection of signals produced by a changing pattern of regional uplift. An important corollary is that, with careful independent calibration, these networks might act as useful tape recorders of otherwise inaccessible mantle processes. Finally, we note that there are substantial discrepancies between our results and published dynamic topographic predictions.

  15. African Women Writing Resistance

    Institute of Scientific and Technical Information of China (English)

    Jennifer Browdy de Hernandez; Pauline Dongala; Omotayo; Jolaosho; Anne Serafin

    2011-01-01

    AFRICAN Women Writing Resistance is the first transnational anthology to focus on women's strategies of resistance to the challenges they face in Africa today.The anthology brings together personal narratives,testimony,interviews,short stories,poetry,performance scripts,folktales and lyrics.

  16. African Women Writing Resistance

    Institute of Scientific and Technical Information of China (English)

    Jennifer; Browdy; de; Hernandez; Pauline; Dongala; Omotayo; Jolaosho; Anne; Serafin

    2011-01-01

    An Anthology of Contemporary Voices AFRICAN Women Writing Resistance is the first transnational anthology to focus on women’s strategies of resistance to the challenges they face in Africa today.The anthology brings together personal narratives,testimony,interviews, short stories,po-

  17. Deepening African Ties

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chinese President Hu Jintao has just embarked on his state visits to eight African countries that will take him to both the northern and southern tips of the continent. This is his first trip abroad this year, and also his third visit to Africa

  18. East African institutions

    DEFF Research Database (Denmark)

    Nordby, Johannes Riber; Jacobsen, Katja

    For the past decade security in East Africa has gained focus internationally. However there is a growing ambition among African states to handle such issues by themselves, sometimes through regional institutions. This has been supported by many Western states but potential risks are often forgotten....

  19. African tick bite fever

    DEFF Research Database (Denmark)

    Johansen, Jakob Aaquist; Thybo, Søren

    2011-01-01

    The incident of spotted fever imported to Denmark is unknown. We present a classic case of African Tick Bite Fever (ATBF) to highlight a disease, which frequently infects wildlife enthusiasts and hunters on vacation in South Africa. ATBF has a good prognosis and is easily treated with doxycyclin...

  20. West African Antislavery Movements

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi; Pelckmans, Lotte

    2011-01-01

    In the context of liberalization of West African political regimes, the upsurge of audacious political entrepreneurs who want to end chattel slavery in their nation-state, resulted in the legal criminalisation of slavery in both Mauritania (2007) and Niger (2003) and in a proposal to revise the...... cultures (or ‘mentalities’) go hand in hand....

  1. Immunizations and African Americans

    Science.gov (United States)

    ... Program Grants Other Grants Planning and Evaluation Grantee Best Practices Black/African American Asthma Cancer Chronic Liver Disease ... 13 to 17 years who ever received the human papillomavirus (HPV) vaccination, 2014 - Males # doses ... 240-453-2882 Office of Minority Health Resource Center Toll Free: 1-800-444-6472 / Fax: ...

  2. Female genital mutilation in African and African American women's literature

    Directory of Open Access Journals (Sweden)

    Darja Marinšek

    2007-12-01

    Full Text Available The article builds on the existing dispute between African and African American women writers on the competence of writing about female genital mutilation (FGM, and tries to determine the existence and nature of the differences between the writings of these two groups. The author uses comparative analysis of two popular African and African American novels, comparing their ways of describing FGM, its causes and consequences, the level ob objectivity and the style of the narrations.This is followed by a discussion on the reasons for such differences, incorporating a larger circle of both African and African American women authors, at the same time analysing the deviance within the two groups. While the differences between African American writers are not that great, as they mostly fail to present the issue from different points of view, which is often the result of their lack of direct knowledge of the topic, African authors' writing is in itself discovered to be ambivalent and not at all invariable. The reasons for such ambivalence are then discussed in greater context, focusing on the effect of the authors' personal contact with circumcision as well as their knowledge and acceptance of Western values. The author concludes by establishing the African ambivalent attitude towards FGM, which includes different aspects of the issue, as the most significant difference between their and African American writers' description of this practice.

  3. Comparison of the lipid properties of healthy and pansteatitis-affected African sharptooth catfish, Clarias gariepinus (Burchell), and the role of diet in pansteatitis outbreaks in the Olifants River in the Kruger National Park, South Africa.

    Science.gov (United States)

    Huchzermeyer, K D A; Osthoff, G; Hugo, A; Govender, D

    2013-11-01

    Pansteatitis has been identified in wild populations of sharptooth catfish, Clarias gariepinus (Burchell), and Nile crocodiles, Crocodylus niloticus Laurenti, inhabiting the same waters in the Olifants River Gorge in the Kruger National Park, South Africa. Mesenteric and pectoral fat tissue was investigated microscopically and by fatty acid analysis in healthy and pansteatitis-affected catfish from both captive and wild populations. Variation in fatty acid composition between pectoral and mesenteric fat was noted. Composition of mesenteric fat differed between fish from various localities as a result of differences in diet. Pansteatitis in the captive population, resulting from ingestion of high amounts of dietary oxidized fat, reflected higher levels of unsaturated fatty acids within the mesenteric fat. Mesenteric fat of pansteatitis-affected wild catfish was characterized by an increase in moisture content, a decrease in fat content and a decrease in stearic and linoleic acids. The n-3 to n-6 fatty acid ratio of mesenteric fat was higher in pansteatitis-affected wild catfish than in healthy catfish from the same locality, reflecting higher polyunsaturated fat intake by pansteatitis-affected fish. The possible role of alien, invasive, phytoplankton-feeding silver carp, Hypophthalmichthys molitrix (Valenciennes), in the aetiology of pansteatitis in both catfish and crocodiles in the Olifants Gorge is discussed.

  4. Leadership in the African context

    Directory of Open Access Journals (Sweden)

    M. Masango

    2002-08-01

    Full Text Available The Western world has always viewed the African continent as plagued by corruption; dictatorship; military coups; rebellious leaders; greediness; misuse of power; and incompetent, politically unstable leaders - in effect, suspicious leaders who undermine their own democracies. This paper analyzes African leadership and its impact by concentrating on three historical eras, namely; the African Religious era; the Christian era, and the era of Globalization. These affected African leadership. In addition, many brilliant minds left the continent in search of greener pastures. A review of these three eras will help us understand how leadership shifted from African values into Western concepts. The role of missionaries lead African people to live with both an African and a Western concept of life. In spite of the above problems, our past leaders did their best in addressing the difficulties they faced during the three eras. African concepts of leadership were often regarded as barbaric and uncultured. Structures were evaluated by Western standards. Due to globalisation, African leaders, through programmes like NEPAD, are going back to basics, drawing on African concepts of unity among its leadership. Effectiveness or life-giving leadership is emerging and empowering villagers/communities in the continent. This type of leadership is innovative and has brought new hope for the continent.

  5. The Ephemeral Cathedral of Créteil : a 350m2 lightweight gridshell structure made of 2 kilometers of GFRP tubes

    OpenAIRE

    du Peloux, Lionel; Tayeb, Frédéric; Caron, Jean-François; Baverel, Olivier

    2015-01-01

    The Ephemeral Cathedral of Créteil (Paris, France) is a gridshell structure made of composite materials. Built in 2013, this religious edifice of 350m 2 is a temporary church meant to gather the parishioners during the two-years renovation of their permanent cathedral. This large-scale prototype (Figure 1) represents a first in the building industry, which still shows excessive apprehension for the use of non-traditional materials such as composites, especially when it comes to structural app...

  6. Ecomorphodynamic approaches to river anabranching patterns

    Science.gov (United States)

    Crouzy, Benoît; Bärenbold, Fabian; D'Odorico, Paolo; Perona, Paolo

    2016-07-01

    We investigate the influence of vegetation on river morphological instabilities using an analytical framework. We first discuss the important role of the hydrological (flooding frequency) and biological (vegetation development rate) timescales. As long as the changes in riverbed morphology and vegetation over an interval comprising one flood and one low-flow period are small, we show that it is possible to simplify the description of a vegetated river with non-constant discharge. We propose physically-based and effective (neural) models for the feedback between vegetation and morphodynamics. Physically-based approaches use equations of morphodynamics extended to account for the interplay between flow, sediment and vegetation dynamics. While their foundation is solid, a physically-based description is only feasible for simple vegetation cover (grass to shrubs). For complex vegetated obstacles we present as an alternative effective approaches, explicitly including interactions (local and non-local) between obstacles. We focus on the role of vegetation in the emergence of ridge patterns observed in the presence of an ephemeral flow and correspondingly derive a set of conditions for patterns.

  7. Steps to African Development

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The development of Africa is vital to the world’s sustainable development.However,African countries still face key challenges in achieving the meaningful expansion of their economies.At the High-Level Symposium on China-Africa Investment Cooperation in Xiamen,southeast China’s Fujian Province,held from September 8 to 10,Chen Deming,Minister of Commerce of China,elaborates on these challenges and sees

  8. Diversity among African pygmies.

    Science.gov (United States)

    Ramírez Rozzi, Fernando V; Sardi, Marina L

    2010-01-01

    Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D) landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies) were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression) and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.

  9. Diversity among African pygmies.

    Directory of Open Access Journals (Sweden)

    Fernando V Ramírez Rozzi

    Full Text Available Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.

  10. Biofuels: The African experience

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo, L.A.; Nkolo, M. [German Agency for Technical Cooperation GTZ, Delegation Regionale des Eaux et Forets, Bertoua (Cameroon)

    2009-07-01

    In July 2006, the African Non-Petroleum Producers Association was formed in Senegal, Africa to develop alternative energy sources. It involved 13 of Africa's poorest nations, who joined forces to become global suppliers of biofuels, and some have set mandatory mixing of ethanol into gasoline. Although several biofuel production projects have been launched in western Africa, many of the new projects and plantations have not yet reached maturity due to the time lag between plantation and full-scale production, which is about 6 years. Major projects that could be producing significant quantities of biofuels in the next few years are not yet reflected in production statistics. Although ethanol is not yet being produced in large quantities in Africa, short-term opportunities exist. Countries in the South African Development Community are using molasses from the sugar can industry to produce ethanol. Biodiesel is also not currently produced on a significant scale in western Africa, but several other countries are gaining experience with cotton and palm oil resources, and Jatropha. Biomass residue also represents a large potential for all African countries involved in timber production. Unlike biodiesel production, land use conflicts are not an issue with biomass residue production.

  11. Institution Building for African Regionalism

    OpenAIRE

    Khadiagala, Gilbert M.

    2011-01-01

    Since the 1960s, African states have embraced regional integration as a vital mechanism for political cooperation and for pooling resources to overcome problems of small and fragmented economies. In building meaningful institutions for regionalism, however, Africans have faced the challenges of reconciling the diversities of culture, geography, and politics. As a result, African regional institutions are characterized by multiple and competing mandates and weak institutionalization. This stud...

  12. Complexity of the Ephemeral

    DEFF Research Database (Denmark)

    Ekman, Ulrik

    2015-01-01

    This brief article presents the everyday cultural use of the Snapchat instant messaging application for video chats as an exemplary case of the challenges confronting studies of cinematics in an epoch marked by the rise in network societies of ubiquitous mobile and social media and technics. It...

  13. African-Americans and Heart Disease, Stroke

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More African-Americans and Heart Disease, Stroke Updated:Apr 18, ... of getting those diseases are even higher for African-Americans. The good news is, African-Americans can ...

  14. Late Quaternary climatic changes revealed by luminescence dating, mineral magnetism and diffuse reflectance spectroscopy of river terrace palaeosols: a new form of geoproxy data for the southern African interior

    Science.gov (United States)

    Lyons, Richard; Tooth, Stephen; Duller, Geoff A. T.

    2014-07-01

    The nature, spatial patterns and forcing mechanisms of Quaternary climatic changes across southern Africa remain unresolved and contentious, principally due to the scarcity of continuous and robustly-dated proxy records. We present what we interpret to be a broadly continuous record of late Quaternary climatic change based on optically stimulated luminescence (OSL) dating, and mineral magnetic and diffuse reflectance spectroscopy (DRS) analyses of stacked palaeosols within an overbank alluvial succession along the Modder River, central South Africa. The OSL ages indicate that alluvial sedimentation occurred at a fairly steady rate, averaging ˜0.15 mm/yr from at least 44 ka until ˜0.83 ka. This suggests that the palaeosols are accretionary, having formed contemporaneously with sedimentation. Climate is identified as the key soil-forming factor controlling the intensity of pedogenesis and is reflected in the changing concentration of pedogenic ferrimagnetic minerals (magnetite/maghemite) of single domain and superparamagnetic dimensions, and by variations in the amount of hematite compared to goethite. These data indicate that the climate was generally dry (rainfall ˜200-400 mm/yr) from ˜46 to 32 ka, except for a brief peak in humidity at ˜42 ka. There was then a period of greater humidity (rainfall ˜400-600 mm/yr) from ˜32 to 28 ka, possibly reflecting enhanced moisture supply from the Atlantic Ocean associated with the equatorward migration and intensification of westerly storm tracks. Although the precise mechanism remains unresolved, this climatic change may have been linked to an obliquity minimum at ˜29 ka. After ˜28 ka, the climate became progressively cooler and drier, especially between ˜18 and 15.5 ka when rainfall was as low as ˜100-200 mm/yr. Temperatures and rainfall then increased from ˜15.5 ka onwards, with the latter possibly linked to rising sea-surface temperatures in the SW Indian Ocean and enhanced moisture supply from easterly

  15. Sandstone-body structures and ephemeral stream processes in the Dinosaur Canyon Member, Moenave Formation (Lower Jurassic), Utah, U.S.A.

    Science.gov (United States)

    Olsen, Henrik

    1989-02-01

    Studies of fluvial sandstone-body structures in the Lower Jurassic Dinosaur Canyon Member suggest a threefold subdivision of the ephemeral stream deposits. Sandstone-sheets with interbedded siltstones are less than 1 m thick and laterally extensive for hundreds of metres. They are interpreted as sheetflood deposits. Simple channel sandstone-bodies are a few metres thick and a few tens of metres wide. They reflect solitary channel incision, episodic migration and plugging. Multistorey channel sandstone-bodies are a few metres thick and laterally extensive for hundreds of metres. They are composed of several channel-shaped storeys and exhibit only local incision. The multistorey sandstone-bodies are interpreted as braided ephemeral stream deposits. Two sandstone-sheet subtypes with grooves and mounds, respectively, are interpreted as intermediate between the sheetflood deposits and solitary incised channel deposits on one hand and between sheetflood deposits and braided stream deposits on the other hand. The solitary channels and braided streams are accordingly interpreted to be initiated from sheetfloods through differential erosion and differential deposition, respectively. This model of channel evolution from sheetfloods is probably applicable to other semiarid and arid fluvial environments dominated by surface runoff.

  16. The African Diaspora, Civil Society and African Integration

    DEFF Research Database (Denmark)

    Opoku-Mensah, Paul Yaw

    This paper, a work-in-progress, makes a contribution to the discussions on the appropriate modalities for incorporating the African diaspora in the African integration project.  It argues that the most appropriate entry points for incorporating the African diaspora into the integration project...... might not, necessarily, be in the formal political structures, although this is important. To the contrary, the most effective and sustainable might be within civil society---that is the links between the peoples and organizations of Africa and the diaspora. Using the case of the African academy-- as an...... institution of civil society--- the paper outlines a conceptual framework for incorporating the diaspora into the African integration project....

  17. African Conservation Tillage Network Website

    OpenAIRE

    African Conservation Tillage Network (ACT)

    2009-01-01

    Metadata only record Maintained by the African Conservation Tillage Network (ACT), this website provides information on Conservation Agriculture in an African context and gathered by stakeholders (NGOs) native to the continent. Resources on projects, practices, reports, and training courses are provided.

  18. African Diaspora Associations in Denmark

    DEFF Research Database (Denmark)

    Vammen, Ida Marie; Trans, Lars Ove

    2011-01-01

    Since the early 1990s, an increasing number of African migrants have come to Denmark, where they have formed a large number of migrant associations. This chapter presents selected findings from a comprehensive survey of African diaspora associations in Denmark and focuses specifically on their...

  19. Booster for African Economy

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China’s investment is fueling African growth SINCE 2000,driven by the Forum on China-Africa Cooperation,China’s foreign direct investment(FDI) in Africa has been growing rapidly.In the face of the global financial crisis,which led to global FDI flows falling,China’s investment in Africa has been on a steady, upbeat rise without any interruption.In 2009,China’s direct investment in Africa reached $1.44 billion,of which nonfinancial direct investment soared by 55.4 percent from the previous year.Africa

  20. The opportunistic feeding and reproduction strategies of the annual fish Cynopoecilus melanotaenia (Cyprinodontiformes: Rivulidae inhabiting ephemeral habitats on southern Brazil

    Directory of Open Access Journals (Sweden)

    Cristina da Silva Gonçalves

    2011-03-01

    Full Text Available Most Rivulidae fishes are popularly known as annual fishes which live in ephemeral environments such as pools, that obligatorily dry out seasonally causing the death of adult individuals. They have unique biological characteristics such as small body size, early sexual maturation, continuous reproduction, an elaborated courtship behavior, and a great reproductive capacity among fishes. The rivulids are widely distributed in North, Central and South America. In this study, the diet and reproductive biology of Cynopoecilus melanotaenia was analyzed. A total of 263 specimens were collected and the analysis of 233 gastrointestinal contents revealed an invertivorous diet composed mainly of small crustaceans (Cladocera, Amphipoda, and Ostracoda and immature insects (Chaoboridae, Culicidae, Syrphidae, but mainly Chironomidae larvae. Lepidophagy on male's diet was also registered. Fecundity was estimated by analyzing 59 pairs of mature ovaries and ranged from 2 to 157 oocytes (mean, 19 ± 26[SD]. The species has fractional spawning, a strategy to increase the chance of survival to prolonged depletions. This study is the first to investigate the reproductive biology of C. melanotaenia. The results confirmed the opportunistic character of the rivulid C. melanotaenia and provided unreported reproductive information that may aid conservation of the species.A maioria dos peixes da família Rivulidae são popularmente conhecidos como anuais por completarem todo seu ciclo biológico em pequenos corpos de água temporários que secam obrigatoriamente em determinados períodos do ano causando a morte dos indivíduos adultos. Possuem características biológicas peculiares como pequeno porte, maturação sexual precoce, reprodução contínua, um elaborado padrão de corte e uma grande capacidade reprodutiva entre os peixes. Os rivulídeos se encontram amplamente distribuídos nas Américas do Norte, Central e Sul. Este trabalho analisou a dieta e a biologia

  1. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Jeppesen, Søren; Hansen, Michael W.

    In light of recent enthusiasm over the African private sector, this paper reviews the existing empirical literature on successful African enterprises and proposes an analytical framework for understanding African firm success. Overall, it is argued that we need to develop an understanding...... of African firm strategy and performance that takes into account the specificities of the African business environment and African firm capabilities. The paper starts by juxtaposing the widespread pessimistic view of African business with more recent, optimistic studies on African firms’ performance....... The latter suggests that profound improvements in African business performance are indeed under way: with the private sector playing a more important role as an engine of growth, with the rise of a capable African entrepreneurial class, and with the emergence of dynamic and competitive African enterprises...

  2. Bioenergy and African transformation.

    Science.gov (United States)

    Lynd, Lee R; Sow, Mariam; Chimphango, Annie Fa; Cortez, Luis Ab; Brito Cruz, Carlos H; Elmissiry, Mosad; Laser, Mark; Mayaki, Ibrahim A; Moraes, Marcia Afd; Nogueira, Luiz Ah; Wolfaardt, Gideon M; Woods, Jeremy; van Zyl, Willem H

    2015-01-01

    Among the world's continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures.

  3. On Rivers

    OpenAIRE

    Gleason, Colin Joseph

    2016-01-01

    Despite the importance of rivers to industry, agriculture, the climate system, and global ecosystems, our current knowledge of river discharge (volume of available water per unit time) is surprisingly poor for many regions of the world as political cloistering, aging infrastructure, and rapid human changes limit our ability to understand global surface waters holistically. Closing this knowledge gap is critical for better management of surface water in light of drought and increasing human de...

  4. Court stories in selected African short narratives

    OpenAIRE

    E. Yewah

    1994-01-01

    This article attempts to cross-examine African Literature and African costumary, Islamic and inherited colonial laws. It opens a new topic in the study of African literature by showing how legal discourses are inscribed in certain African narratives and how these discourses link the narratives to the overall context of their production.

  5. 2002 Sino-African SHP Training Workshop

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The 2002 Sino-African SHP Training Workshop was held from 10 May to 18 June 2002 at Hangzhou Regional Center for Small Hydro Power(HRC). Attended altogether 9 participants from 5 African countries, i.e. Burundi, Nigeria, South African, Tanzania and Tunisia. This is the second training workshop on SHP that HRC conducted for African countries.

  6. Assimilation Differences among Africans in America.

    Science.gov (United States)

    Dodoo, F. Nii-Amoo

    1997-01-01

    Census data (1990) indicate that male African immigrants earn more than their Caribbean-born counterparts or native-born African Americans, but controlling for relevant earnings-related endowments erases the African advantage and elevates Caribbean earnings above those of the other groups. Also, African (but not Caribbean) university degree…

  7. Succession of Ephemeral Secondary Forests and Their Limited Role for the Conservation of Floristic Diversity in a Human-Modified Tropical Landscape

    DEFF Research Database (Denmark)

    van Breugel, Michiel; Hall, Jefferson S.; Craven, Dylan;

    2013-01-01

    a deterministic shift in the diversity and composition of the local plant communities as well as the metacommunity, driven by variation in the rate at which species recruited into and disappeared from the secondary forests across the landscape. Our results indicate that dispersal limitation and the successional...... niche operate simultaneously and shape successional dynamics of the metacommunity of these early secondary forests. A high diversity of plant species across the metacommunity of early secondary forests shows a potential for restoration of diverse forests through natural succession, when trees....... This implies that ephemeral secondary forests have a limited role in the long-term conservation of tree species diversity in human-modified tropical landscapes....

  8. A Call to African Unity

    DEFF Research Database (Denmark)

    Muchie, Mammo

    This month's paper, written by Professor Mammo Muchie, examines the necessity for a pan-African monetary union.  Professor Muchie argues for the "the creation of a unified African strategy and unified approach to dealing with the outside donor world by neutralising the poison of money as honey...... that donor aid has come to be in Africa." He provides a historic and contemporary context for the unification of monetary and customs systems across Africa and argues for a dual currency system for the self-financing of African development and for sustained self-determination....

  9. How student teachers understand African philosophy

    OpenAIRE

    Matsephe M. Letseka; Elza Venter

    2012-01-01

    The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980) Philosophy and an African culture, Hountondji’s (1983) African philosophy: Myth and reality, Oruka’s (1990) Sage philosophy: Indigenous thinkers and modern debate on African philoso...

  10. Surfaces on African sculpture

    Directory of Open Access Journals (Sweden)

    John Mack

    2011-12-01

    Full Text Available Review of: Leonard Kahan, Donna Page, and Pascal James Imperato (eds in collaboration with Charles Bordogna and Bolaji Campbell with an introduction by Patrick McNaughton, Surfaces: Color, Substances, and Ritual Applications on African Sculpture, Indiana University Press, 2009.The book reviewed here has potential interest to a wide range of readers, whether researchers and academics, museum, curators, conservators or connoisseurs. It examines the perception of surface as an aspect of the indigenous understanding of sculpted objects in sub-Saharan Africa, treating of questions of materials, patination, colouration and use. It includes both survey essays and case studies (on the Bamana of Mali and the Yoriuba of Nigeria in a compendium which has suggestive implications beyond the immediate field of the Africanists to whom it is principally addressed.

  11. West African Antislavery Movements

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi; Pelckmans, Lotte

    2011-01-01

    to unite, mobilize and struggle. Members of anti-slavery movements with slave origins accessed power positions through peaceful electoral processes in Benin, mali, Niger and Mauritania. People of slave origins gained ground in local politics of a number of municipalities. In localities where anti-slavery......In the context of liberalization of West African political regimes, the upsurge of audacious political entrepreneurs who want to end chattel slavery in their nation-state, resulted in the legal criminalisation of slavery in both Mauritania (2007) and Niger (2003) and in a proposal to revise...... the penal code of Mali. Anti-slavery activists not only address their claims to their national governments but also intend to initiate change at local level. In that respect the democratic decentralization reforms were significant because they allowed educated anti-slavery activists to appeal their brethren...

  12. African Ethnobotany in the Americas

    Directory of Open Access Journals (Sweden)

    Egleé L. Zent

    2013-10-01

    Full Text Available Review of African Ethnobotany in the Americas. Edited by Robert Voeks and John Rashford. 2013. Springer. Pp. 429, 105 illustrations, 69 color illustrations. $49.95 (paperback. ISBN 978‐1461408352.

  13. African Ethnobotany in the Americas

    OpenAIRE

    Zent, Egleé L

    2013-01-01

    Review of African Ethnobotany in the Americas. Edited by Robert Voeks and John Rashford. 2013. Springer. Pp. 429, 105 illustrations, 69 color illustrations. $49.95 (paperback). ISBN 978‐1461408352.

  14. The Good African Society Index

    OpenAIRE

    Ferdi Botha

    2014-01-01

    This paper constructs a Good Society Index for 45 African countries, termed the Good African Society Index (GASI). The GASI consists of nine main indexes: (i) economic sustainability, (ii) democracy and freedom, (iii) child well-being, (iv) environment and infrastructure, (v) safety and security, (vi) health and health systems, (vii) integrity and justice, (viii) education, and (xi) social sustainability and social cohesion. Each component is split into four sub-components for a total of 36 i...

  15. Twin Sessions Through African Eyes

    Institute of Scientific and Technical Information of China (English)

    Ni Yanshuo

    2012-01-01

    Every year journalists from around China and the world flock to Beijing in March to cover the sessions of the National People's Congress (NPC) and the Chinese People's Political Consultative Conference (CPPCC), known as the lianghui, or twin sessions. With the deepening of Sino-African relations in the past decades, an increasing number of African journalists are involved in reporting China's lianghui to their audiences in Africa.

  16. Training in African aquaculture development

    OpenAIRE

    Brummett, R. E.

    1994-01-01

    The article focuses on the types of training needed in African aquaculture development. The author suggested that rather than needing less training, extension agents and others who operate in the idiosyncratic world of the poor African farmer, need a far deeper understanding of fish culture (particularly the basics of pond dynamics and ecology) than do those who can take advantage of industrialized-country infrastructure.

  17. Managing the wetlands. People and rivers: Africa.

    Science.gov (United States)

    Dugan, P

    1993-01-01

    At the current population growth rate in Africa, the population will reach 1 billion by 2010. Water is needed to sustain these people, yet rainfall in Africa is erratic. Africans are already confronting a shortage of freshwater. Agriculture supports 66% of the population of sub-Saharan Africa. Sound agricultural development is needed to curb rural-urban migration, but a constant supply of freshwater is essential. Major rivers (the Limpopo in southern Africa and the Save/Sabi in Zimbabwe and Mozambique) now flow only seasonally. The flows of the Chari-Logona, the Nile, and the Zambezi are falling. Continual mismanagement of Africa's river basins coupled with current projections of global climate change will expand desiccation. All but the White Nile and the Zaire rivers flood seasonally every year, thereby expanding Africa's wetlands. Wetlands have been targeted for development projects (e.g., hydroelectric projects and large dams), largely to meet urban-industrial demands. Development planners tend to ignore the economic value of the wetlands. For example, the Niger Inland Delta sustains 550,000 people, 1 million cattle, and 1 million sheep. Wetlands replenish ground water and serve as natural irrigation. River basin planning often results in environmentally disastrous schemes which do not understand local management practices. Hydrologists, engineers, geologists, and economics design these schemes, but sociologists, anthropologists, and development experts should be included. The unfinished Jonglei Canal in southern Sudan would have adversely affected 400,000 pastoralists. The Volta River Authority's Akosombo Dam displaced 84,000 people and flooded the most productive agricultural land in Ghana. A sustainable future in Africa depends on understanding the interactions of human uses and the ways in which they relate to the natural variations in river flow. The IUCN Wetlands Programme, based on the principles of the World Conservation Strategy, is working with

  18. Statistical analysis and mathematical modeling of a tracer test on the Santa Clara River, Ventura County, California

    Science.gov (United States)

    Paybins, Katherine S.; Nishikawa, Tracy; Izbicki, John A.; Reichard, Eric G.

    1998-01-01

    To better understand flow processes, solute-transport processes, and ground-water/surface-water interactions on the Santa Clara River in Ventura County, California, a 24-hour fluorescent-dye tracer study was performed under steady-state flow conditions on a 28-mile reach of the river. The study reach includes perennial (uppermost and lowermost) subreaches and ephemeral subreaches of the lower Piru Creek and the middle Santa Clara River. Dye was injected at a site on Piru Creek, and fluorescence of river water was measured continuously at four sites and intermittently at two sites. Discharge measurements were also made at the six sites. The time of travel of the dye, peak dye concentration, and time-variance of time-concentration curves were obtained at each site. The long tails of the time-concentration curves are indicative of sources/sinks within the river, such as riffles and pools, or transient bank storage. A statistical analysis of the data indicates that, in general, the transport characteristics follow Fickian theory. These data and previously collected discharge data were used to calibrate a one-dimensional flow model (DAFLOW) and a solute-transport model (BLTM). DAFLOW solves a simplified form of the diffusion-wave equation and uses empirical relations between flow rate and cross-sectional area, and flow rate and channel width. BLTM uses the velocity data from DAFLOW and solves the advection-dispersion transport equation, including first-order decay. The simulations of dye transport indicated that (1) ground-water recharge explains the loss of dye mass in the middle, ephemeral, subreaches, and (2) ground-water recharge does not explain the loss of dye mass in the uppermost and lowermost, perennial, subreaches. This loss of mass was simulated using a linear decay term. The loss of mass in the perennial subreaches may be caused by a combination of photodecay or adsorption/desorption.

  19. The New African Civil-Military Relations

    DEFF Research Database (Denmark)

    on the African continent to embark upon the New African Civil Military Relations (ACMR). In the last decade and half, the implosion of African states exposed to forces of democratization has escalated, manifest in Algeria, Egypt, Mali, Madagascar, Somalia, South Sudan, Central African Republic and Lesotho...... accorded the responsibility of organizing a Session on ACMR. From amongst some of the exciting Abstracts presented, authors submitted these as full chapters for this book which captures International African Studies Perspectives, managed by the African Public Policy & Research Institute (APPRI...

  20. East African Rift

    Science.gov (United States)

    2008-01-01

    Places where the earth's crust has formed deep fissures and the plates have begun to move apart develop rift structures in which elongate blocks have subsided relative to the blocks on either side. The East African Rift is a world-famous example of such rifting. It is characterized by 1) topographic deep valleys in the rift zone, 2) sheer escarpments along the faulted walls of the rift zone, 3) a chain of lakes within the rift, most of the lakes highly saline due to evaporation in the hot temperatures characteristic of climates near the equator, 4) voluminous amounts of volcanic rocks that have flowed from faults along the sides of the rift, and 5) volcanic cones where magma flow was most intense. This example in Kenya displays most of these features near Lake Begoria. The image was acquired December 18, 2002, covers an area of 40.5 x 32 km, and is located at 0.1 degrees north latitude, 36.1 degrees east longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  1. Disarmament: the African perspective

    International Nuclear Information System (INIS)

    Disarmament is now generally accepted as the process of reduction in the size of, and expenditures on, armed forces, the destruction or dismantling of weapons, whether deployed or stockpiled, the progressive elimination of the capacity to produce new weapons and the release and integration into civilian life of military personnel. To realize this objective, the nations of the world have been advocating such measures as the establishment of nuclear weapon-free zones, non-proliferation, limitation of the arms trade, reduction of military budgets, and confidence-building measures. To ensure general and complete elimination of arms, there has been widespread recognition of the need to link the disarmament process with other political as well as socio-economic problems of the world such as the need for security, good relations between states and development of a system of peaceful settlement of disputes. Other measures that have been considered to be relevant in boosting the disarmament process include the role of the general public in putting pressure on their respective governments with a view to accelerating and realizing disarmament objectives. Africans have presented to the world a strong case for global disarmament

  2. An African ethic for nursing?

    Science.gov (United States)

    Haegert, S

    2000-11-01

    This article derives from a doctoral thesis in which a particular discourse was used as a 'paradigm case'. From this discourse an ethic set within a South African culture arose. Using many cultural 'voices' to aid the understanding of this narrative, the ethic shows that one can build on both a 'justice' and a 'care' ethic. With further development based on African culture one can take the ethic of care deeper and reveal 'layers of understanding'. Care, together with compassion, forms the foundation of morality. Nursing ethics has followed particular western moral philosophers. Often nursing ethics has been taught along the lines of Kohlberg's theory of morality, with its emphasis on rules, rights, duties and general obligations. These principles were universalistic, masculine and noncontextual. However, there is a new ethical movement among Thomist philosophers along the lines to be expounded in this article. Nurses such as Benner, Bevis, Dunlop, Fry and Gadow--to name but a few--have welcomed the concept of an 'ethic of care'. Gilligan's work gave a feminist view and situated ethics in the everyday aspects of responsiveness, responsibility, context and concern. Shutte's search for a 'philosophy for Africa' has resulted in finding similarities in Setiloane and in Senghor with those of Thomist philosophers. Using this African philosophy and a research participant's narrative, an African ethic evolves out of the African proverb: 'A person is a person through other persons', or its alternative rendering: 'I am because we are: we are because I am.' This hermeneutic narrative reveals 'the way affect imbues activity with ethical meaning' within the context of a black nursing sister in a rural South African hospital. It expands upon the above proverb and incorporates the South African constitutional idea of 'Ubuntu' (compassion and justice or humanness).

  3. Infrastructure and climate change: Impacts and adaptations for the Zambezi River Valley

    OpenAIRE

    Paul S. Chinowsky; Amy E. Schweikert; Strzepek, Niko L.; Strzepek, Kenneth

    2013-01-01

    The African Development Bank has called for US$40 billion per year over the coming decades to be provided to African countries to address development issues directly related to climate change. The current study addresses a key component of these issues, the effect of climate change on the road infrastructure of Malawi, Mozambique, and Zambia, all located within the Zambezi River Basin. The study incorporates a stressor-response approach to estimate the effects of projected precipitation, temp...

  4. Human action as inducing changes in the fluvial pattern of river Rivera de Huelva (Guillena sector-Sevilla); La accion antropica como inductora de cambios en el ptraon fluvial del rio Rivera de Huelva (sector Guillena-Sevilla)

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Martinez, B.; Baena Escudero, R.; Posada Simenon, C.

    2009-07-01

    This paper aims to highlight the changes that occur in hydro morphological the final stretch of a river as the Rivera de Huelva, with a catchment of more than 2000 km{sup 2}, which throughout the 20{sup t}h century has been a strong human intervention, for the construction of seven reservoir for water supply in the municipality of Seville and its metropolitan area. This intense man brigs an important change in the hydrological behaviour of the natural river, which is reflected not only in its river system, but also in the behavior of extreme hydrological events. At the morphological changes resulting in a change in the morphologic pattern of the channel, which acquires, at present, characteristics of ephemeral river with plenty of cargo and marked incision general fund. Likewise, this trend is generating significant incision instability problems in the infrastructure. (Author) 15 refs.

  5. Towards a better understanding of ephemeral stream morphodynamics during the last 100 ka in the vicinity of the prehistoric site of Ifri n'Ammar (Morocco)

    Science.gov (United States)

    Bartz, Melanie; Rixhon, Gilles; Kehl, Martin; El Ouahabi, Meriam; Klasen, Nicole; Brill, Dominik; Szemkus, Nina; Weniger, Gerd-Christian; Mikdad, Abdeslam; Brückner, Helmut

    2016-04-01

    This research focuses on the ephemeral stream deposits of Wadi Selloum to reconstruct the palaeoenvironmental evolution in the direct vicinity of the rock shelter Ifri n'Ammar (NE Morocco). As one of the oldest settlement sites of anatomically modern humans (AMH) in North Africa, Ifri n'Ammar documents periodic occupation phases since ~170 ka. These discontinuous settlement dynamics may have been related to or influenced by landscape changes and climate forcing. Therefore, our study aims at identifying phases of morphodynamic activity and stability, respectively, in the deposits of Wadi Selloum by using micromorphological, sedimentological (laser diffractometry), geochemical (LOI, magnetic susceptibility, Scheibler method) and mineralogical (XRD) methods. A robust chronology for the ephemeral stream deposits was built by applying different luminescence dating techniques (OSL dating of quartz and pIRIR290 dating of potassium feldspar). An internal cross-check is provided by the TL-age of a pottery shard. The application of luminescence dating techniques to Wadi Selloum deposits yield burial ages between 1.3 ± 0.2 and 102 ± 8 ka, with enhanced aggradation occurring during three time spans: between ~100 and 60 ka, ~21 and 14 ka and during the Holocene. The development of a major palaeosol (2B-2C-sequence) points to a stability phase during the OIS 3. Pedogenesis is evident in thin sections by well-developed subangular blocky microstructures. The main soil forming process is the precipitation of secondary carbonate in subsoil horizons, indicated by pedofeatures such as calcite infillings and hypocoatings. Holocene deposits (6.4 ± 4 to 1.3 ± 0.2 ka) seem to be affected by short-term changes between a relative stability of the landscape and hydromorphic activity, evidenced by the strong variations in the mineralogical and geochemical characteristics. This is supported by an insignificant differentiation in soil horizons with only weakly developed pedofeatures. The

  6. The significance and lag-time of deep throughflow: an example from a small, ephemeral catchment with contrasting soil types in the Adelaide Hills, South Australia

    Directory of Open Access Journals (Sweden)

    E. Bestland

    2009-03-01

    Full Text Available The importance of deep throughflow in a small (3.4 km2 ephemeral catchment in the Adelaide Hills of South Australia was investigated by detailed hydrochemical analysis of soil water and stream flow during autumn and early winter rains. In this Mediterranean climate with strong summer moisture deficits, several significant rainfalls are required to generate soil throughflow and stream flow (in ephemeral streams. During Autumn 2007, a large (127 mm drought-breaking rain occurred in April followed by significant May rains; most of this precipitation occurred prior to the initiation of stream flow in late May. These early events, especially the 127 mm event, had low (depleted stable water isotope values compared with both later rains and average winter precipitation. Thus, this large depleted early rain event provided an excellent natural tracer. During the June and July rainfall events, daily stream and soil water samples were collected and analysed. Results from major and trace elements, water isotopes (δ18O, δD, and dissolved organic carbon analysis clearly demonstrate that a large component of this early April and May rain was stored and later pushed out of deep soil or regolith zones. This pre-event water was identified in the stream as well as identified in deeper soil horizons due to its different isotopic signature which contrasted sharply with the June–July event water. Based on this data, the regolith and throughflow system for this catchment has been re-thought. The catchment area consists of about half sandy and half clayey soils. Regolith flow is now thought to be dominated by the sandy soil system not the clayey soil system. The clayey duplex soils had rapid response to rain events and saturation excess overland flow. The sandy soils had delayed soil throughflow and infiltration excess overland flow. A pulse of macropore throughflow was observed in the sandy soils three days after the rainfall event

  7. The significance and lag-time of deep through flow: an example from a small, ephemeral catchment with contrasting soil types in the Adelaide Hills, South Australia

    Directory of Open Access Journals (Sweden)

    J. VanLeeuwen

    2009-07-01

    Full Text Available The importance of deep soil-regolith through flow in a small (3.4 km2 ephemeral catchment in the Adelaide Hills of South Australia was investigated by detailed hydrochemical analysis of soil water and stream flow during autumn and early winter rains. In this Mediterranean climate with strong summer moisture deficits, several significant rainfalls are required to generate soil through flow and stream flow [in ephemeral streams]. During autumn 2007, a large (127 mm drought-breaking rain occurred in April followed by significant May rains; most of this April and May precipitation occurred prior to the initiation of stream flow in late May. These early events, especially the 127 mm April event, had low stable water isotope values compared with later rains during June and July and average winter precipitation. Thus, this large early autumn rain event with low isotopic values (δ18O, δD provided an excellent natural tracer. During later June and July rainfall events, daily stream and soil water samples were collected and analysed. Results from major and trace elements, water isotopes (δ18O, δD, and dissolved organic carbon analysis clearly demonstrate that a large component of this early April and May rain was stored and later pushed out of deep soil and regolith zones. This pre-event water was identified in the stream as well as identified in deep soil horizons due to its different isotopic signature which contrasted sharply with the June–July event water. Based on this data, the soil-regolith hydrologic system for this catchment has been re-thought. The catchment area consists of about 60% sandy and 40% clayey soils. Regolith flow in the sandy soil system and not the clayey soil system is now thought to dominate the deep subsurface flow in this catchment. The clayey texture contrast soils had rapid response to rain events and saturation excess overland flow. The sandy soils had delayed soil through flow and

  8. African N Assessment

    Science.gov (United States)

    Bekunda, M.; Galford, G. L.; Hickman, J. E.; Palm, C.

    2011-12-01

    Africa's smallholder agricultural systems face unique challenges in planning for reducing poverty, concurrent with adaptation and mitigation to climate change. At continental level, policy seeks to promote a uniquely African Green Revolution to increase crop yields and food production, and improve local livelihoods. However, the consequences on the environment and climate are not clear; these pro-economic development measures should be linked to climate change adaptation and mitigation measures, and research is required to help achieve these policy proposals by identifying options, and testing impacts. In particular, increased nitrogen (N) inputs are essential for increasing food production in Africa, but are accompanied by inevitable increases in losses to the environment. These losses appear to be low at input levels promoted in agricultural development programs, while the increased N inputs both increase current food production and appear to reduce the vulnerability of food production to changes in climate. We present field and remote sensing evidence from Malawi that subsidizing improved seed and fertilizers increases resilience to drought without adding excess N to the environment. In Kenya, field research identified thresholds in N2O losses, where emissions are very low at fertilization rates of less than 200 kg ha-1. Village-scale models have identified potential inefficiencies in the food production process where the largest losses of reactive N occur, and which could be targeted to reduce the amount of N released to the environment. We further review some on-going research activities and progress in Africa that compare different methods of managing resources that target resilience in food production and adaptation to climate change, using nutrient N as an indicator, while evaluating the effects of these resource management practices on ecosystems and the environment.

  9. African horse sickness.

    Science.gov (United States)

    Mellor, Philip Scott; Hamblin, Christopher

    2004-01-01

    African horse sickness virus (AHSV) causes a non-contagious, infectious insect-borne disease of equids and is endemic in many areas of sub-Saharan Africa and possibly Yemen in the Arabian Peninsula. However, periodically the virus makes excursions beyond its endemic areas and has at times extended as far as India and Pakistan in the east and Spain and Portugal in the west. The vectors are certain species of Culicoides biting midge the most important of which is the Afro-Asiatic species C. imicola. This paper describes the effects that AHSV has on its equid hosts, aspects of its epidemiology, and present and future prospects for control. The distribution of AHSV seems to be governed by a number of factors including the efficiency of control measures, the presence or absence of a long term vertebrate reservoir and, most importantly, the prevalence and seasonal incidence of the major vector which is controlled by climate. However, with the advent of climate-change the major vector, C. imicola, has now significantly extended its range northwards to include much of Portugal, Spain, Italy and Greece and has even been recorded from southern Switzerland. Furthermore, in many of these new locations the insect is present and active throughout the entire year. With the related bluetongue virus, which utilises the same vector species of Culicoides this has, since 1998, precipitated the worst outbreaks of bluetongue disease ever recorded with the virus extending further north in Europe than ever before and apparently becoming endemic in that continent. The prospects for similar changes in the epidemiology and distribution of AHSV are discussed.

  10. The transmission of African culture to children

    OpenAIRE

    Michele Tanon Lora

    2014-01-01

    African ancient traditions suffered a major historical change as a result of colonization. Several decades after decolonization and access to independence, what is the situation and place of the African culture in Africa and outside Africa? Does African culture perpetuate effectively today? What are the obstacles to the transmission of African culture to our children? What are the beliefs or elements that have influenced the transmission of our culture after the period of independence? Roughl...

  11. Translating Culture: Contemporary African American Poetry

    OpenAIRE

    Kristina Kočan Šalamon

    2015-01-01

    The paper interrogates cultural specifics of contemporary African American poetry and exhibits translation problems when translating this poetic work. African American writers have always included much of their cultural heritage in their writing and this is immediately noticed by a translator. The cultural elements, such as African American cuisine, attire and style in general, as well as spiritual and religious practices, often play a significant role for African American poets who are procl...

  12. African American Teaching and the Matriarchal Performance.

    Science.gov (United States)

    Jeffries, Rhonda Baynes

    This paper discusses the role of matriarchs in African-American culture, explaining that traditionally, African-American matriarchs arise from a combination of African norms and American social positions that naturally forces them to assume leadership conditions. The roles these women assume are a response to the desire to survive in a society…

  13. African pastoralist systems: An integrated approach

    OpenAIRE

    Fratkin, E.; Galvin, K.A.; Roth, E.A.

    1994-01-01

    Metadata only record The chapters in this book cover the following topics: Archaeological Perspectives on East African Pastoralism; Pastoralism in Historic Perspective; Mobility and Land Use Among African Pastoralists: Old Conceptual Problems and New Interpretations; Labor, Livestock, and Land: The Organization of Pastoral Production; Diet, Nutrition, and Pastoral Strategy; Demographic Systems: Two East African Examples; Child Fostering Among Nomadic Turkana Pastoralists: Demographic and H...

  14. The African American Image in American Cinema.

    Science.gov (United States)

    Bourne, St. Clair

    1990-01-01

    Political conditions have influenced the screen images of U.S. cinema, and the images of African Americans have reflected prevailing social stereotypes. The history of African-American representation in films is traced, and it is noted that the tendency to portray African Americans stereotypically has not changed. (SLD)

  15. MORE CHINESE CARS ON AFRICAN ROADS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China drives into the African vehicle market and meets the challenges head on with some advantages of its own High-quality but inexpensive Chinese automobiles have gradually won the confidence of the African market and are becoming a bright new link in Sino-African economic ties. On September 4, a total of 400 Polarsun minibuses, made in Shenyang, capital of northeast

  16. African Centered Knowledge: A British Perspective.

    Science.gov (United States)

    Christian, Mark

    2001-01-01

    Considers the impact of African centered knowledge within the United Kingdom. Recent development of African Diaspora studies has forged links between various black Atlantic communities. The United Kingdom has experienced positive grassroots community response to the work of noted African centered scholars, yet within the British academy,…

  17. Comparative contributions of solution geochemistry, microbial metabolism and aquatic photosynthesis to the development of high pH in ephemeral wetlands in South East Australia.

    Science.gov (United States)

    Reid, R J; Mosley, L M

    2016-01-15

    The development of alkaline conditions in lakes and wetlands is common but the process of alkalinisation is not well elaborated. In this study we investigated causes of the seasonal alkalinisation of ephemeral wetlands in the South East of South Australia where pH values above 10 are frequently observed. This research combined field observations, geochemical analysis of wetland sediment and surface water, with mesocosm studies under controlled conditions. The results revealed a complex interplay between a number of different processes. A primary cause was attributed to sequestration of CO2 from the water column by plant photosynthesis, coupled with slow diffusion of CO2 from the air which led to its depletion in the water. Abundant plant growth also modified the water chemistry via uptake of nutrient elements, in particular calcium and magnesium and increased carbonate alkalinity in the water. Assessment of field results and geochemical modeling showed that low Ca/(HCO3(-) and CO3(-2)) ratios in the water, coupled with carbonate mineral (calcite, Mg substituted calcite, dolomite) precipitation and evapoconcentration, create a high alkalinity and pH (>9) baseline in many wetlands. The high baseline pH is then further increased by CO2 depletion due to photosynthesis. We could find no evidence that reduction of sulfate to sulfides by sulfur-reducing bacteria significantly contributed to the very high pH conditions.

  18. Late Quaternary paleoenvironments of an ephemeral wetland in North Dakota, USA: Relative interactions of ground-water hydrology and climate change

    Science.gov (United States)

    Yansa, C.H.; Dean, W.E.; Murphy, E.C.

    2007-01-01

    This study of fossils (pollen, plant macrofossils, stomata and fish) and sediments (lithostratigraphy and geochemistry) from the Wendel site in North Dakota, USA, emphasizes the importance of considering ground-water hydrology when deciphering paleoclimate signals from lakes in postglacial landscapes. The Wendel site was a paleolake from about 11,500 14C yr BP to 11,100 14C yr BP. Afterwards, the lake-level lowered until it became a prairie marsh by 9,300 14C yr BP and finally, at 8,500 14C yr BP, an ephemeral wetland as it is today. Meanwhile, the vegetation changed from a white spruce parkland (11,500 to 10,500 14C yr BP) to deciduous parkland, followed by grassland at 9,300 14C yr BP. The pattern and timing of these aquatic and terrestrial changes are similar to coeval kettle lake records from adjacent uplands, providing a regional aridity signal. However, two local sources of ground water were identified from the fossil and geochemical data, which mediated atmospheric inputs to the Wendel basin. First, the paleolake received water from the melting of stagnant ice buried under local till for about 900 years after glacier recession. Later, Holocene droughts probably caused the lower-elevation Wendel site to capture the ground water of up-gradient lakes. ?? 2007 Springer Science+Business Media, Inc.

  19. Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications

    Directory of Open Access Journals (Sweden)

    L. Luiselli

    2012-07-01

    Full Text Available African manatees (Trichechus senegalensis and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles Crocodylus suchus and dwarf crocodile Osteolaemus tetraspis in the Niger Delta (Nigeria, testing the hypotheses that (i manatees may avoid crocodiles in order to minimize risks of predation, and (ii the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i the three species differing significantly in terms of their macro-habitat type selection, and (ii significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant.

  20. Mitochondrial phylogeny and phylogeography of East African squeaker catfishes (Siluriformes: Synodontis

    Directory of Open Access Journals (Sweden)

    Meyer Axel

    2006-06-01

    Full Text Available Abstract Background Squeaker catfishes (Pisces, Mochokidae, Synodontis are widely distributed throughout Africa and inhabit a biogeographic range similar to that of the exceptionally diverse cichlid fishes, including the three East African Great Lakes and their surrounding rivers. Since squeaker catfishes also prefer the same types of habitats as many of the cichlid species, we hypothesized that the East African Synodontis species provide an excellent model group for comparative evolutionary and phylogeographic analyses. Results Our analyses reveal the existence of six major lineages of Synodontis in East Africa that diversified about 20 MYA from a Central and/or West African ancestor. The six lineages show a clear geographic patterning. Two lineages are endemic to Lake Tanganyika (plus one non-endemic representative, and these are the only two Synodontis lineages that diversified further into a small array of species. One of these species is the cuckoo catfish (S. multipunctatus, a unique brood parasite of mouthbrooding haplochromine cichlids, which seems to have evolved in parallel with the radiation of its cichlid host lineage, the Tropheini. We also detect an accelerated rate of molecular evolution in S. multipunctatus, which might be the consequence of co-evolutionary dynamics. Conclusion We conclude that the ancestral lineage of today's East African squeaker catfish fauna has colonized the area before the Great Lakes have formed. This ancestor diversified rapidly into at least six lineages that inhabit lakes and rivers in East Africa. Lake Tanganyika is the only lake harboring a small species flock of squeaker catfishes.

  1. How student teachers understand African philosophy

    Directory of Open Access Journals (Sweden)

    Matsephe M. Letseka

    2012-10-01

    Full Text Available The question ‘What constitutes African philosophy?’ was first raised with the publication of Placide Tempels’s seminal work Bantu philosophy in 1959. Tempels’s book inevitably elicited considerable critical response from African philosophers, which culminated in a wide range of publications such as Wiredu’s (1980 Philosophy and an African culture, Hountondji’s (1983 African philosophy: Myth and reality, Oruka’s (1990 Sage philosophy: Indigenous thinkers and modern debate on African philosophy, Shutte’s (1993 Philosophy for Africa, Masolo’s (1994 African philosophy in search of identity and Gyekye’s (1995 An essay of African philosophical thought: The Akan conceptual scheme. It has been over 60 years since the publication of Temples’s book and there continues to be serious debate about African philosophy. This article sought to contribute to the debate on the various conceptions of African philosophy, but with a focus on the challenges of teaching African philosophy to Philosophy of Education students at an open distance learning institution in South Africa. This article discussed the tendency amongst undergraduate Philosophy of Education students to conflate and reduce African philosophy to African cultures and traditions, and to the notion of ubuntu, and sought to understand the reasons for students’ inclination to treat African philosophy in this way. It examined students’ background knowledge of African philosophy, their critical thinking skills and whether their official study materials are selected and packaged in a manner that, in fact, adds to the challenges they face. Finally, the article explored the ways in which Philosophy of Education lecturers can adapt their pedagogy to provide students with a better understanding of African philosophy.

  2. African women, literature, language and culture

    OpenAIRE

    Rosamond S. King

    2014-01-01

    This essay will link African women’s writing to culture, including literary culture and the politics of literature. It describes how African women’s literature can act as a mirror, reflecting African cultures to Africans, and how it can serve as a window and a door, revealing African cultures to those outside of them in whole or in part. It ends with a description of “communal agency,” an example of how scholarly writing can act as a door for both those who are and are not a part of a literat...

  3. Origins, consolidation and challenges of African Hispanism

    Directory of Open Access Journals (Sweden)

    Vital Tama Bena

    2014-08-01

    Full Text Available The African continent today takes into consideration a cultural movement which can be called African Hispanism. Born with the beginning of the post-colonial era, this African Hispanism has witnessed a progressive setting up in African countries thanks to the impetus of teachers of the Spanish language. Today that action benefits from a notorious cultural life as observed trough Spanish users of that language on the one hand; on the other hand the birth of a very promising African Spanish literature. Yet some future challenges are to come for a real fruitful future of that cultural movement. Key words: Spanish language; Africa intercultural exchanges.

  4. YELLOWSTONE RIVER WATCH (YRW)

    Science.gov (United States)

    Yellowstone River Watch seeks to expand its monitoring and education efforts throughout the Yellowstone River Basin by actively recruiting and training new teacher members. Yellowstone River Watch also seeks to advance existing school programs by offering quality assurance/quali...

  5. Improvisation in West African Musics.

    Science.gov (United States)

    Locke, David

    1980-01-01

    Discussed is music of the sub-Sahara. Vocal, instrumental, and dance drumming from the Sudan Desert, the North Coast, East Horn, Central and West Africa, and contrapuntal yodeling of Pygmies is described. For African musicians, the ability to improvise, and creativity, are gifts from God. Includes selected readings and recordings. (KC)

  6. Vitamin D and African Americans

    Science.gov (United States)

    Vitamin D insufficiency is more prevalent among African Americans than other Americans and, in North America, most young, healthy blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of the year. This is primarily due to the fact that pigmentation reduces vitamin D...

  7. Classic African American Children's Literature

    Science.gov (United States)

    McNair, Jonda C.

    2010-01-01

    The purpose of this article is to assert that there are classic African American children's books and to identify a sampling of them. The author presents multiple definitions of the term classic based on the responses of children's literature experts and relevant scholarship. Next, the manner in which data were collected and analyzed in regard to…

  8. Quo vadis South African universities?

    OpenAIRE

    Johann RE lutjeharms

    2007-01-01

    The Economist has recently identified some specific factors that explain why European universities are not competing adequately with their American counterparts. These factors are used here to evaluate South African government policy for universities. It is demonstrated that this current policy is directly contrary to what is now internationally considered best for universities in a knowledge economy.

  9. Acid neutralization capacity measurements in surface and ground waters in the Upper River Severn, Plynlimon: from hydrograph splitting to water flow pathways

    Directory of Open Access Journals (Sweden)

    C. Neal

    1997-01-01

    Full Text Available Acid Neutralization Capacity (ANC data for ephemeral stream and shallow groundwater for the catchments of the upper River Severn show a highly heterogeneous system of within-catchment water flow pathways and chemical weathering on scales of less than 100m. Ephemeral streams draining permeable soils seem to be supplied mainly from shallow groundwater sources. For these streams, large systematic differences in pH and alkalinity occur due to the variability of the groundwater sources and variability in water residence times. However, the variability cannot be gauged on the basis of broad based physical information collected in the field as geology, catchment gradients and forest structure are very similar. In contrast, ephemeral streams draining impermeable soils are of more uniform chemistry as surface runoff is mainly supplied from the soil zone. Groundwater ANC varies considerably over space and time. In general, the groundwaters have higher ANCs than the ephemeral streams. This is due to increased chemical weathering from the inorganic materials in the lower soils and groundwater areas and possibly longer residence times. However, during the winter months the groundwater ANCs tend to be at their lowest due to additional event driven acidic soil water contributions and intermediate groundwater residence times. The results indicate the inappropriateness of a blanket approach to classifying stream vulnerability to acidification simply on the basis of soil sensitivity. However, the results may well indicate good news for the environmental management of acidic and acid sensitive systems. For example, they clearly indicate a large potential supply of weathering components within the groundwater zone to reduce or mitigate the acidifying effects of land use change and acidic deposition without the environmental needs for Aiming. Furthermore, the high variability of ephemeral stream runoff means that certain areas of catchments where there are specific

  10. Impacts of artificial inundation of ephemeral creek beds on mature riparian eucalypts in semi-arid northwest Australia

    Science.gov (United States)

    Argus, Rachel; Page, Gerald; Grierson, Pauline

    2014-05-01

    The resilience of riparian ecosystems of intermittent rivers to changes in their hydrological regimes is not well understood. In the Pilbara region of northwest Australia, streams flow only occasionally, reflecting a highly dynamic and extremely variable cycle of prolonged droughts punctuated by occasional floods. However, discharge of ground water pumped from mining activities over recent years has resulted in localised areas with constant surface water. Here we sought to assess impacts of prolonged saturation on the health and functioning of two co-occurring eucalypts (Eucalyptus camaldulensis and Eucalyptus victrix). While riparian vegetation is clearly adapted to partial root-zone hypoxia, we hypothesised that trees in inundated areas experience reduced root function due to an energy crisis, which will be reflected by symptoms in the foliage. We expected that complete saturation of the entire root system for an extended time period reduces physiological function through lower stomatal conductance and more negative water potential, results in canopy sparseness and reduces accumulation of foliar nitrogen and phosphorus. Trees (n=26) were assessed at two sites with artificially permanent surface water (discharge sites) and compared to trees (n=21) at a site with a naturally occurring permanent groundwater fed pool ('reference site'). Trees were sampled from a range of positions including the stream bed, the lower bank and the upper bank, in order to determine the extent of influence of the discharge water. No eucalypts grew in the stream bed at the reference site, indicating either the stream bed conditions were unsuitable for seedling survival or eucalypts were outcompeted by the flood tolerant tree Melaleuca argentea (which was absent from the impact sites). Soil redox potential, an indicator of oxygen availability and other soil chemical conditions, was measured with platinum redox probes at 25 cm depth. Trees were assessed for canopy cover, foliage water

  11. The Nahal Oz Reservoir dam-break flood: Geomorphic impact on a small ephemeral loess-channel in the semi-arid Negev Desert, Israel

    Science.gov (United States)

    Roskin, Joel; Bergman, Nathaniel; Shaulker, Ofer; Greenbaum, Noam

    2014-05-01

    The Nahal Oz Reservoir - in the coastal, semi-arid southwestern Israel was designed to enhance local irrigation of crops using reclaimed sewage water during the dry summer months. On March 2001, part of the western dike of the reservoir was breached and generated a flow release of 3.5*106 m3 of secondary irrigation water that was channeled down the 1st order ephemeral loess stream (Nahal Yare'akh). The consequent 12-hour flood surge, with an estimated peak discharge of 1000 m3s-1, inflicted severe loess erosion, agricultural, property and infrastructural damage downstream. Post-flood mapping documented the geomorphic response to the flood which included channel scour and widening along the initial 2 km downstream of the reservoir where a spillway channel was formed. The increase in the cross-sectional area was about 60% and had an estimated 170,000 m3 of sediment bed, bank and floodplain erosion. Calculated maximum shear stress and stream power along this section are estimated at 300 Nm-2 and 900 wm-2, respectively. The peak discharge at the end of this segment was estimated at 800 m3s-1 indicating only minor attenuation along this segment. Two km downstream of the breach, a wide braided fan indicated deposition of the eroded sediments. At the end of this segment the floodwater diverged into several watercourses and inundated tilled agricultural fields and neighborhoods. Downstream, 9 km from the reservoir, the discharge attenuated to 100 m3s-1, slightly above bankfull. Further downstream and upon reaching the large Shikma stream the flow was already very low. This reduction in discharge is attributed to the anthropogenic infrastructure - roads, neighborhoods and agricultural fields and the large transmission losses typical of sandy ephemeral streams. The study shows that channels within erodible materials respond to high peak discharges very locally. Erosional thresholds that severely incised the channel are only maintained for 2 km below the breached reservoir

  12. Kinetics of selected plasma cytokines during innate-adaptive immune response transition in adult cattle infected with the bovine ephemeral fever virus.

    Science.gov (United States)

    Barigye, R; Melville, L F; Davis, S; Walsh, S; Hunt, N; Hunt, R

    2016-04-15

    While virus neutralizing antibodies are known to be variably protective against bovine ephemeral fever (BEF) virus (BEFV) infections, the cytokine events that mediate the nascent adaptive immune response have not been defined in cattle. This study determined the plasma kinetics of IL-2, IFN-γ, IL-6, and IL-10 during the period of innate-immune response transition and evaluated the relationship between the virus neutralizing antibody response and viraemia in BEFV-infected cattle. Plasma from four virus-infected and uninfected negative control animals was tested by cytokine-specific immunoenzymatic assays, viraemia monitored by qRT-PCR, and virus neutralizing antibody titres determined using a standard protocol. Unlike the negative controls, plasma IL-6 and IL-10 were increased in all the virus-infected animals starting several days prior to initiation of viraemia. In one animal, plasma IL-2 and IFN-γ were consistently higher than in the other three virus-infected animals and the negative control mean. The animal with the strongest IL-2 and IFN-γ responses had the shortest viraemia while the heifer with the lowest IL-2/IFN-γ indices demonstrated the longest viraemia. Evidently, increase in plasma IL-6 and IL-10 precedes seroconversion during BEFV infections in cattle suggesting the two cytokines may influence immunological events that pave way to B-cell activation and seroconversion. While there is remarkable variability in IL-2 and IFN-γ expression amongst BEFV-infected animals, increased plasma levels of the two cytokines appear to be associated with a shorter viraemia. Ongoing studies will help define the precise role of T cells in anti-BEFV adaptive immune responses. PMID:27016765

  13. Succession of ephemeral secondary forests and their limited role for the conservation of floristic diversity in a human-modified tropical landscape.

    Directory of Open Access Journals (Sweden)

    Michiel van Breugel

    Full Text Available Both local- and landscape-scale processes drive succession of secondary forests in human-modified tropical landscapes. Nonetheless, until recently successional changes in composition and diversity have been predominantly studied at the patch level. Here, we used a unique dataset with 45 randomly selected sites across a mixed-use tropical landscape in central Panama to study forest succession simultaneously on local and landscape scales and across both life stages (seedling, sapling, juvenile and adult trees and life forms (shrubs, trees, lianas, and palms. To understand the potential of these secondary forests to conserve tree species diversity, we also evaluated the diversity of species that can persist as viable metapopulations in a dynamic patchwork of short-lived successional forests, using different assumptions about the average relative size at reproductive maturity. We found a deterministic shift in the diversity and composition of the local plant communities as well as the metacommunity, driven by variation in the rate at which species recruited into and disappeared from the secondary forests across the landscape. Our results indicate that dispersal limitation and the successional niche operate simultaneously and shape successional dynamics of the metacommunity of these early secondary forests. A high diversity of plant species across the metacommunity of early secondary forests shows a potential for restoration of diverse forests through natural succession, when trees and fragments of older forests are maintained in the agricultural matrix and land is abandoned or set aside for a long period of time. On the other hand, during the first 32 years the number of species with mature-sized individuals was a relatively small and strongly biased sub-sample of the total species pool. This implies that ephemeral secondary forests have a limited role in the long-term conservation of tree species diversity in human-modified tropical landscapes.

  14. The role of unpaved roads as active source areas of precipitation excess in small watersheds drained by ephemeral streams in the Northeastern Caribbean

    Science.gov (United States)

    Ramos-Scharrón, Carlos E.; LaFevor, Matthew C.

    2016-02-01

    Quantitative understanding of the impacts of land development on runoff generation is vital for managing aquatic habitats. Although unpaved roads are broadly recognized as significant sources of sediment within managed forested landscapes, their role in altering runoff response is characteristically dependent on rainstorm and watershed size. Here we evaluate the role of unpaved roads in the development of Horton overland flow and their potential to influence the delivery of runoff from small watersheds (∼1s km2) drained by ephemeral streams flowing toward coral reef bearing waters of the Northeastern Caribbean. Infiltration capacity curves for undisturbed forest soils and unpaved roads were developed based on hydrologic characterization performed with a Guelph permeameter. Results demonstrate that infiltration capacities from unpaved roads are roughly a quarter of those for forest soils. Consequently, localized precipitation excess is about four times greater on unpaved roads than on forest soils. Analyses indicate that unpaved roads generate precipitation excess roughly ten times more frequently than watershed-scale storm flow generated by the combined effects of precipitation excess and saturation overland flow. Comparison of unpaved road precipitation excess with observed watershed discharge suggests that road networks may produce localized surface runoff equal to 62% of total watershed discharge for rainstorms up to 3.0 cm, and this holds even for watersheds with low and moderate road densities (0.8-2.3 km km-2). For watersheds with high road densities (∼7.6 km km-2), roads may contribute about one-quarter of storm flow for rain events up to 10 cm. Our results stress the high sensitivity of runoff response in dry tropical watersheds to land disturbance, even when this disturbance occurs on only about 1% of the land surface. In this particular case study, unpaved roads prove capable of altering the time distribution of runoff and, by extension, sediment

  15. Polybrominated diphenyl ether metabolism in field collected fish from the Gila River, Arizona, USA-Levels, possible sources, and patterns

    Science.gov (United States)

    Echols, Kathy R.; Peterman, Paul H.; Hinck, Jo Ellen; Orazio, Carl E.

    2013-01-01

    Polybrominated diphenyl ethers (PBDEs) were determined in fish collected from the Gila River, Arizona, a tributary of the Colorado River in the lower part of the Colorado River Basin. Fish samples were collected at sites on the Gila River downstream from Hayden, Phoenix, and Arlington, Arizona in late summer 2003. The Gila River is ephemeral upstream of the Phoenix urban area due to dams and irrigation projects and has limited perennial flow downstream of Phoenix due to wastewater and irrigation return flows. Fifty PBDE congeners were analyzed by high resolution gas chromatography/high resolution mass spectrometry using labeled surrogate standards in composite samples of male and female common carp (Cyrpinus carpio), largemouth bass (Micropterus salmoides) and channel catfish (Ictalurus punctatus). The predominant PBDE congeners detected and quantified were 47, 100, 153, 49, 28, and 17. Concentrations of total PBDEs in these fish ranged from 1.4 to 12700 ng g-1 wet weight, which are some of the highest concentrations reported in fish from the United States. Differences in metabolism of several PBDE congeners by carp is clear at the Phoenix site; congeners with at least one ring of 2,4,5-substitution are preferentially metabolized as are congeners with 2,3,4-substitution.

  16. The UCAR Africa Initiative: Enabling African Solutions to African Needs

    Science.gov (United States)

    Pandya, R.; Bruintjes, R.; Foote, B.; Heck, S.; Hermann, S.; Hoswell, L.; Konate, M.; Kucera, P.; Laing, A.; Lamptey, B.; Moncrieff, M.; Ramamurthy, M.; Roberts, R.; Spangler, T.; Traoré, A.; Yoksas, T.; Warner, T.

    2007-12-01

    The University Corporation for Atmospheric Research (UCAR) Africa Initiative (AI) is a coordinated effort aimed at building sustainable partnerships between UCAR and African institutions in order to pursue research and applications for the benefit of the African people. The initiative is based on four fundamental operating principles, concisely summarized by the overall philosophy of enabling African solutions to African needs. The four principles are: • Collaborate with African institutions • Focus on institutional capacity building and research support • Explore science research themes critical to Africa and important for the world • Leverage the research infrastructure in UCAR to add value These principles are realized in a set of pilot activities, chosen for their high probability of short-term results and ability to set the stage for longer-term collaboration. The three pilot activities are listed below. 1. A modest radar network and data-distribution system in Mali and Burkina Faso, including a data-sharing MOU between the Mail and Burkina Faso Weather Services. 2. A partnership among UCAR, the Ghana Meteorological Agency, and the Ghana university community to develop an operational Weather Research and Forecasting (WRF) model for West Africa. The output is used by researchers and operational forecasters in Africa. Model output is also part of a demonstration project that aims to allow humanitarian agencies to share geo-referenced information in Africa via a web portal. 3. A workshop in Ouagadougou, Burkina Faso from April 2-6, 2007, with the theme Improving Lives by Understanding Weather. The workshop, co-organized with Programme SAAGA and the Commité Permanent Inter-Etats de Lutte Contre la Sécheresse dans le Sahel (CILSS), included over 80 participants from 18 countries, and produced a set of recommendations for continued collaboration. Our presentation will provide an update of these pilot activities and point to future directions. Recognizing

  17. Schistosomes in South African penguins.

    Science.gov (United States)

    Aldhoun, Jitka A; Horne, Elizabeth C

    2015-01-01

    During the years 2009-2012, faeces of African penguins (Spheniscus demersus L.) from South African rehabilitation centres were examined for helminths. In total, 46 out 555 samples (8.29 %), mostly belonging to adult birds, were found to contain oval schistosome eggs with a spine on one pole. Their dimensions were 153.21 ± 9.07 × 87.14 ± 8.67 μm. Selected DNA fragments (18S, 28S and ITS rDNA) were sequenced and compared to other schistosome isolates deposited in GenBank. The shape of the eggs suggests that they belong to the genus Gigantobilharzia; however, due to the insufficient stage of knowledge of the genus and limited number of species available for comparison, we were not able to assign the isolate unambiguously to this genus based on either the egg morphology or the results of molecular analysis.

  18. African palm ethno-medicine

    DEFF Research Database (Denmark)

    Gruca, Marta; Blach-Overgaard, Anne; Balslev, Henrik

    2015-01-01

    Ethnopharmacological relevance This study is the first to demonstrate the breadth and patterns of the medicinal applications of African palms. It sheds light on species with the potential to provide new therapeutic agents for use in biomedicine; and links the gap between traditional use of palms...... and pharmacological evaluation for the beneficial effects of palm products on human health. Last but not least, the study provides recommendations for the areas that should be targeted in future ethno-botanical surveys. Aim of the study The primary objective of this survey was to assemble all available ethno-medicinal...... data on African palms, and investigate patterns of palm uses in traditional medicine; and highlight possible under-investigated areas. Materials and methods References were found through bibliographic searches using several sources including PubMed, Embase, and Google Scholar and search engines...

  19. Palaearctic-African Bird Migration

    DEFF Research Database (Denmark)

    Iwajomo, Soladoye Babatola

    Bird migration has attracted a lot of interests over past centuries and the methods used for studying this phenomenon has greatly improved in terms of availability, dimension, scale and precision. In spite of the advancements, relatively more is known about the spring migration of trans......-Saharan migrants than autumn migration. Information about the behavior and interactions of migrants during the nonbreeding season in sub-Saharan Africa is also scarce for many species. Furthermore, very little is known about intra-African migration. This thesis summarizes my research on the autumn migration...... of birds from Europe to Africa and opens up the possibility of studying intra-African migration. I have used long-term, standardized autumn ringing data from southeast Sweden to investigate patterns in biometrics, phenology and population trends as inferred from annual trapping totals. In addition, I...

  20. A new perspective on West African hydroclimate during the last deglaciation

    Science.gov (United States)

    Parker, Andrew O.; Schmidt, Matthew W.; Jobe, Zane R.; Slowey, Niall C.

    2016-09-01

    Widespread drought characterized the Heinrich 1 and Younger Dryas cold periods of the last deglaciation throughout much of Africa, causing large increases in dust emissions from the Sahara and Sahel. At the same time, increases in wind strength may have also contributed to dust flux, making it difficult to interpret dust records alone as reflecting changes in rainfall over the region. The Niger River has the third largest drainage basin in Africa and drains most of the Sahara and Sahel and thus preserves and propagates climatic signals. Here, we present new reconstructions of Niger Delta sea surface salinity and Niger River discharge for the last 20,000 years in order to more accurately reconstruct the onset of the Western African Monsoon system. Based on calculated δ18OSEAWATER (δ18OSW) and measured Ba/Ca ratios in planktonic foraminifera, these new records reflect changes in sub-Saharan precipitation across the Niger River Basin in West Africa and reveal that the West African Monsoon system began to intensify several thousand years after the equatorial Monsoon system in Central Africa. We also present new records of primary productivity in the Niger Delta that are related to wind-driven upwelling and show that productivity is decoupled from changes in Niger River discharge. Our results suggest that wind strength, rather than changes in monsoon moisture, was the primary driver of dust emissions from the Sahara and Sahel across the last deglaciation.

  1. Financial Liberalization: The African Experience

    OpenAIRE

    Reinhart, Carmen; Tokatlidis, Ioannis

    2000-01-01

    Almost a decade after their initiation, financial reforms appear to have had little effect on the economies of Sub-Sahara Africa. Whether the blame is to fall on their initial design itself, or on the partial nature of their implementation, liberalization policies have not mobilized savings, deepened intermediation or raised investment. Yet, Africa needs properly functioning financial markets for a more efficient allocation of resources for growth and risk diversification. How can African go...

  2. The African Financial Development Gap

    OpenAIRE

    Allen, Franklin; Carletti, Elena; Cull, Robert; Qian, Jun; Senbet, Lemma

    2010-01-01

    Economic growth in Africa has long been disappointing. We document that the financial sectors of most sub-Saharan African countries remain significantly underdeveloped by the standards of other developing countries. We examine the factors that are associated with financial development in Africa and compare them with those in other developing countries. Population density appears to be considerably more important for banking sector development in Africa than elsewhere. Given the high costs of ...

  3. Recent growth in African cassava

    OpenAIRE

    Nweke, Felix; Haggblade, Steven; Zulu, Ballard

    2004-01-01

    According to the authors, "Cassava serves as a staple food for 200 million Africans, second only to maize in its calorie contribution. In response to a series of devastating attacks by cassava diseases and pests over the past several decades, the International Institute of Tropical Agriculture (IITA) and several national agricultural research services have launched successful cassava research programs... " This brief describes some of the programs, their impact and the drivers of change. It c...

  4. Ideology and the possibility of African political theory: African socialism and “ubuntu” compared

    OpenAIRE

    Gil, Manuel

    2011-01-01

    This article explores the lack of investigation into African political theory in the postcolonial period. After discussing the epistemological problems in the study of African political thought, the paper then adopts Michael Freeden’s methodology for the analysis of political ideologies. Through this approach a comparison is made between African Socialism and ubuntu. African Socialism – as developed by Cabral, Nkrumah, Nyerere and Senghor – is defined by its core commitment to freedom from co...

  5. 21st Century South African Science Fiction

    OpenAIRE

    CARAIVAN LUIZA

    2014-01-01

    The paper analyses some aspects of South African science fiction, starting with its beginnings in the 1920s and focusing on some 21st century writings. Thus Lauren Beukes’ novels Moxyland (2008) and Zoo City (2010) are taken into consideration in order to present new trends in South African literature and the way science fiction has been marked by Apartheid. The second South African science fiction writer whose writings are examined is Henrietta Rose-Innes (with her novel Nineveh, published i...

  6. Ectomycorrhizal symbiosis of tropical African trees

    OpenAIRE

    Bâ, Amadou; Duponnois, Robin; Moyersoen, B.; Diédhiou, A.G.

    2012-01-01

    The diversity, ecology and function of ectomycorrhizal (EM) fungi and ectomycorrhizas (ECMs) on tropical African tree species are reviewed here. While ECMs are the most frequent mycorrhizal type in temperate and boreal forests, they concern an economically and ecologically important minority of plants in African tropical forests. In these African tropical forests, ECMs are found mainly on caesalpionioid legumes, Sarcolaenaceae, Dipterocarpaceae, Asterpeiaceae, Phyllantaceae, Sapotaceae, Papil...

  7. African Music: Source of the Blues

    OpenAIRE

    Bayer, Konrad Sidney

    2010-01-01

    [Abstract] African music is the primary source for the blues. Scholars have supplied ample evidence to support this assertion. However, the African retentions still present in the blues are not immediately apparent. African music and the blues share many similarities, including the predominance of rhythm, the uses of music as social commentary and critique, types of instruments, and musical structure. Slaves brought their culture with them to the New World when they were forcibly taken from t...

  8. Representation of African Heritage in Trinidad Carnival

    OpenAIRE

    三吉, 美加

    2016-01-01

    This paper focuses on the cultural representation of African Trinidadian or African creole in Trinidad Carnival. The Republic of Trinidad and Tobago is the most ethnically and culturally diverse society in the East Caribbean. This diversity comprises of 40 percent of East Indians, 40 percent of Africans, and 20 percent of mixed race such as Chinese, Syrians, Lebanese, and Europeans. In the course of making tourism a national agenda, Carnival has gained commercial values, diversifying particip...

  9. 75 FR 45600 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-08-03

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, August 17, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  10. 75 FR 2844 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-01-19

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, January 26, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  11. 75 FR 14418 - African Development Foundation, Board of Directors Meeting

    Science.gov (United States)

    2010-03-25

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, April 13, 2010, 9:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  12. Gentle Africanized bees on an oceanic island.

    Science.gov (United States)

    Rivera-Marchand, Bert; Oskay, Devrim; Giray, Tugrul

    2012-11-01

    Oceanic islands have reduced resources and natural enemies and potentially affect life history traits of arriving organisms. Among the most spectacular invasions in the Western hemisphere is that of the Africanized honeybee. We hypothesized that in the oceanic island Puerto Rico, Africanized bees will exhibit differences from the mainland population such as for defensiveness and other linked traits. We evaluated the extent of Africanization through three typical Africanized traits: wing size, defensive behavior, and resistance to Varroa destructor mites. All sampled colonies were Africanized by maternal descent, with over 65% presence of European alleles at the S-3 nuclear locus. In two assays evaluating defense, Puerto Rican bees showed low defensiveness similar to European bees. In morphology and resistance to mites, Africanized bees from Puerto Rico are similar to other Africanized bees. In behavioral assays on mechanisms of resistance to Varroa, we directly observed that Puerto Rican Africanized bees groomed-off and bit the mites as been observed in other studies. In no other location, Africanized bees have reduced defensiveness while retaining typical traits such as wing size and mite resistance. This mosaic of traits that has resulted during the invasion of an oceanic island has implications for behavior, evolution, and agriculture.

  13. Fragile states and protection under the 1969 African Refugee Convention

    Directory of Open Access Journals (Sweden)

    Tamara Wood

    2013-05-01

    Full Text Available Current practice in African states highlights both the potential andthe limitations of the 1969 African Refugee Convention in providingprotection to persons displaced from fragile states.

  14. Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

    Science.gov (United States)

    Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua

    2015-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

  15. The African agent discovered: The recognition and involvement of the African biblical interpreter in Bible translation

    Directory of Open Access Journals (Sweden)

    S V Coertze

    2008-05-01

    Full Text Available This article explores the extent to which the role of the African biblical interpreter is acknowledged in the process of Bible translation, as the Bible and Bible translation form an important part of the establishment of the African church on the continent of Africa. It points out that even though foreign discovery of African agency in Bible translation is evident, indigenous discovery of the same is largely absent. Part of the relevance of this article is for the African church to own and be actively involved in the translation of the Bible into the remaining African languages that are in need of a translation of the Bible.

  16. Coupled flow and salinity transport modelling in semi-arid environments: The Shashe River Valley, Botswana

    Science.gov (United States)

    Bauer, Peter; Held, Rudolf J.; Zimmermann, Stephanie; Linn, Flenner; Kinzelbach, Wolfgang

    2006-01-01

    Numerical groundwater modelling is used as the base for sound aquifer system analysis and water resources assessment. In many cases, particularly in semi-arid and arid regions, groundwater flow is intricately linked to salinity transport. A case in point is the Shashe River Valley in Botswana. A freshwater aquifer located around an ephemeral stream is depleted by the combined effect of transpiration and pumping. Quantitative system analysis reveals that the amount of water taken by transpiration is far more than the quantities pumped for water supply. Furthermore, the salinity distribution in and around Shashe River Valley as well as its temporal dynamics can be satisfactorily reproduced if the transpiration is modelled as a function of groundwater salinity. The location and dynamics of the saltwater-freshwater interface are highly sensitive to the parameterization of evaporative and transpirative salt enrichment. An existing numerical code for coupled flow/transport simulations (SEAWAT) was adapted to this situation. Model results were checked against a large set of field data including water levels, water chemistry, isotope data and ground and airborne geophysical data. The resulting groundwater model was able to reproduce the long-term development of the freshwater lens located in Shashe River Valley as well as the decline in piezometric heads observed over the last decade. Furthermore, the old age of the saline water surrounding the central freshwater lens could be explained.

  17. Kinetics of pro-inflammatory cytokines, interleukin-10, and virus neutralising antibodies during acute ephemeral fever virus infections in Brahman cattle.

    Science.gov (United States)

    Barigye, R; Melville, L F; Davis, S; Walsh, S; Hunt, N; Hunt, R; Elliot, N

    2015-12-15

    While fever and inflammation are hallmark features of bovine ephemeral fever (BEF), the cytokine networks that underlie the acute phase of the disease have not been empirically defined in cattle. This study characterised the plasma kinetics of proinflammatory cytokines (IL-1β, IL-6, TNF-α) and IL-10 during acute BEF and elucidated on the relationship between the onset of the virus neutralizing antibody response and resolution of viraemia in natural BEF virus (BEFV) infections in cattle. Plasma from three BEFV-infected and three uninfected cattle was tested for the study cytokines by a cELISA, viraemia monitored by qRT-PCR, and virus neutralizing antibody titres determined using a standard protocol. Unlike the negative controls, plasma concentrations of IL-1β, TNF-α, IL-6, and IL-10 were consistently increased in the three virus-infected animals. Two of the infected heifers were recumbent and pyrexic on the first day of monitoring and increased cytokine production was already in progress by the time viraemia was detected in all the three infected animals. In all the virus-infected heifers, IL-1β was the most strongly expressed cytokine, IL-6 and IL-10 manifested intermediate plasma concentrations while TNF-α was the least expressed and demonstrated bi-phasic peaks three and five days after the onset of pyrexia. In two of the BEFV-infected heifers, viraemia resolved on the day of seroconversion while in the other infected animal, viral RNA was detectable up to three days after seroconversion. The present data document variable increase in plasma IL-1β, IL-6, TNF-α, and IL-10 during natural BEFV infections and the fact that upregulation of all but TNF-α precedes seroconversion. In addition to virus neutralising antibodies, it is likely that cytokine-mediated cellular mechanisms may be required for resolution of viraemia in BEF. Considering the anti-inflammatory properties of IL-10, its upregulation may potentially antagonise the fever response in BEFV

  18. River Morphology and River Channel Changes

    Institute of Scientific and Technical Information of China (English)

    CHANG Howard H

    2008-01-01

    River morphology has been a subject of great challenge to scientists and engineers who recognize that any effort with regard to river engineering must be based on a proper understanding of the morphological features involved and the responses to the imposed changes. In this paper,an overview of river morphology is presented from the geomorphic viewpoint. Included in the scope are the regime concept, river channel classification, thresholds in river morphology, and geomor-phic analysis of river responses. Analytical approach to river morphology based on the physical principles for the hydraulics of flow and sediment transport processes is also presented. The appli-cation of analytical river morphology is demonstrated by an example. Modeling is the modern tech-nique to determine both short-term and long-term river channel responses to any change in the en-vironment. The physical foundation of fluvial process-response must be applied in formatting a mathematical model. A brief introduction of the mathematical model FLUVIAL-12 is described.

  19. Depression, Sociocultural Factors, and African American Women

    Science.gov (United States)

    Hunn, Vanessa Lynn; Craig, Carlton David

    2009-01-01

    The authors discuss depression in African American women from a sociocultural perspective, including aspects of oppression and racism that affect symptom manifestation. The authors highlight John Henryism as a coping mechanism, the history and continuing role of the African American church as a safe haven, and strategies for culturally competent…

  20. British African Caribbean Women and Depression

    Science.gov (United States)

    Adkison-Bradley, Carla; Maynard, Donna; Johnson, Phillip; Carter, Stephaney

    2009-01-01

    Depression is a common condition among women in the United Kingdom. However, little is known about the context of depression among British African Caribbean women. This article offers a preliminary discussion regarding issues and information pertaining to depression among British African Caribbean women. Characteristics and symptoms of depression…

  1. Prostate cancer in men of African origin.

    Science.gov (United States)

    McGinley, Kathleen F; Tay, Kae Jack; Moul, Judd W

    2016-02-01

    Men of African origin are disproportionately affected by prostate cancer: prostate cancer incidence is highest among men of African origin in the USA, prostate cancer mortality is highest among men of African origin in the Caribbean, and tumour stage and grade at diagnosis are highest among men in sub-Saharan Africa. Socioeconomic, educational, cultural, and genetic factors, as well as variations in care delivery and treatment selection, contribute to this cancer disparity. Emerging data on single-nucleotide-polymorphism patterns, epigenetic changes, and variations in fusion-gene products among men of African origin add to the understanding of genetic differences underlying this disease. On the diagnosis of prostate cancer, when all treatment options are available, men of African origin are more likely to choose radiation therapy or to receive no definitive treatment than white men. Among men of African origin undergoing surgery, increased rates of biochemical recurrence have been identified. Understanding differences in the cancer-survivorship experience and quality-of-life outcomes among men of African origin are critical to appropriately counsel patients and improve cultural sensitivity. Efforts to curtail prostate cancer screening will likely affect men of African origin disproportionately and widen the racial disparity of disease.

  2. Understanding the Rise of African Business

    DEFF Research Database (Denmark)

    Jorem, Kaja Tvedten; Hansen, Michael Wendelboe; Jeppesen, Søren

    2014-01-01

    in the literature are identified and an integrative framework for analysing African enterprise development is developed. The framework is used to provide an overview of the received literature on African enterprise development, to identify voids and lacunas and to identify new research agendas. Findings: While...

  3. African-American Student Achievement Research Project.

    Science.gov (United States)

    Wagstaff, Mark; Melton, Jerry; Lawless, Brenda; Combs, Linda

    Data from the Texas Assessment of Academic Skills (TAAS) reveal that gains in performance for the African American student population of Region VII of the state's educational system were not keeping pace with the performance of African Americans in the rest of Texas. This study investigated practices in school districts in the region in which…

  4. The South African National Defence Force

    DEFF Research Database (Denmark)

    Mandrup, Thomas

    2009-01-01

    This research paper is an evaluation of The Souch African National Defence Force´s (SANDF) involvement in Peace Support Operations.......This research paper is an evaluation of The Souch African National Defence Force´s (SANDF) involvement in Peace Support Operations....

  5. Cancer and the African American Experience

    Science.gov (United States)

    The first plenary of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores the many factors that lead to inequalities in cancer care outcomes for African Americans.

  6. African American Teachers and Culturally Relevant Pedagogy.

    Science.gov (United States)

    Foster, Michele

    An overview is presented of research on African American teachers, addressing the large body of literature written by policy analysts, first-person narratives, and the sociological and anthropological literature. Policy research has identified the small number of African American teachers and has studied some reasons for this shortage and some of…

  7. New data on African health professionals abroad

    Directory of Open Access Journals (Sweden)

    Clemens Michael A

    2008-01-01

    Full Text Available Abstract Background The migration of doctors and nurses from Africa to developed countries has raised fears of an African medical brain drain. But empirical research on the causes and effects of the phenomenon has been hampered by a lack of systematic data on the extent of African health workers' international movements. Methods We use destination-country census data to estimate the number of African-born doctors and professional nurses working abroad in a developed country circa 2000, and compare this to the stocks of these workers in each country of origin. Results Approximately 65,000 African-born physicians and 70,000 African-born professional nurses were working overseas in a developed country in the year 2000. This represents about one fifth of African-born physicians in the world, and about one tenth of African-born professional nurses. The fraction of health professionals abroad varies enormously across African countries, from 1% to over 70% according to the occupation and country. Conclusion These numbers are the first standardized, systematic, occupation-specific measure of skilled professionals working in developed countries and born in a large number of developing countries.

  8. Population genetics of African ungulates

    DEFF Research Database (Denmark)

    Lorenzen, Eline

    Molecular genetic techniques were used to gain insights into the evolutionary forces that have shaped the present day diversity of African savannah ungu-lates, which constitute the most species-rich mega faunal assemblage on earth. The studies included in this thesis represent individual species......-specific data sets, which are used to elucidate evolutionary processes of importance to the savannah ungulate community. Patterns of DNA variation were analyzed to assess the genetic signatures of Pleistocene refugia and investigate aspects of speciation, intraspecific structuring, hybridization, and historic...

  9. Environmental sensing by African trypanosomes.

    Science.gov (United States)

    Roditi, Isabel; Schumann, Gabriela; Naguleswaran, Arunasalam

    2016-08-01

    African trypanosomes, which divide their life cycle between mammals and tsetse flies, are confronted with environments that differ widely in temperature, nutrient availability and host responses to infection. In particular, since trypanosomes cannot predict when they will be transmitted between hosts, it is vital for them to be able to sense and adapt to their milieu. Thanks to technical advances, significant progress has been made in understanding how the parasites perceive external stimuli and react to them. There is also a growing awareness that trypanosomes use a variety of mechanisms to exchange information with each other, thereby enhancing their chances of survival. PMID:27131101

  10. Efficient Maintenance of Ephemeral Data

    DEFF Research Database (Denmark)

    Schmidt, Albrecht; Jensen, Christian Søndergaard

    2006-01-01

    Motivated by the increasing prominence of loosely-coupled systems, such as mobile and sensor networks, the characteristics of which include intermittent connectivity and volatile data, we study the tagging of data with so-called expiration times. More specifically, when data are inserted into a d......Motivated by the increasing prominence of loosely-coupled systems, such as mobile and sensor networks, the characteristics of which include intermittent connectivity and volatile data, we study the tagging of data with so-called expiration times. More specifically, when data are inserted...... into a database, they may be stamped with time values indicating when they expire, i.e., when they are regarded as stale or invalid and thus are no longer considered part of the database. In a number of applications, expiration times are known and can be assigned at insertion time. We present data structures...... and algorithms for online management of data stamped with expiration times. The algorithms are based on fully functional treaps, which are a combination of binary search trees with respect to a primary attribute and heaps with respect to a secondary attribute. The primary attribute implements primary keys...

  11. The Impact of the Geologic History and Paleoclimate on the Diversification of East African Cichlids

    Directory of Open Access Journals (Sweden)

    Patrick D. Danley

    2012-01-01

    Full Text Available The cichlid fishes of the East African Great Lakes are the largest extant vertebrate radiation identified to date. These lakes and their surrounding waters support over 2,000 species of cichlid fish, many of which are descended from a single common ancestor within the past 10 Ma. The extraordinary East African cichlid diversity is intricately linked to the highly variable geologic and paleoclimatic history of this region. Greater than 10 Ma, the western arm of the East African rift system began to separate, thereby creating a series of rift basins that would come to contain several water bodies, including the extremely deep Lakes Tanganyika and Malawi. Uplifting associated with this rifting backponded many rivers and created the extremely large, but shallow Lake Victoria. Since their creation, the size, shape, and existence of these lakes have changed dramatically which has, in turn, significantly influenced the evolutionary history of the lakes' cichlids. This paper reviews the geologic history and paleoclimate of the East African Great Lakes and the impact of these forces on the region's endemic cichlid flocks.

  12. An African VLBI network of radio telescopes

    CERN Document Server

    Gaylard, M J; Combrinck, L; Booth, R S; Buchner, S J; Fanaroff, B L; MacLeod, G C; Nicolson, G D; Quick, J F H; Stronkhorst, P; Venkatasubramani, T L

    2014-01-01

    The advent of international wideband communication by optical fibre has produced a revolution in communications and the use of the internet. Many African countries are now connected to undersea fibre linking them to other African countries and to other continents. Previously international communication was by microwave links through geostationary satellites. These are becoming redundant in some countries as optical fibre takes over, as this provides 1000 times the bandwidth of the satellite links. In the 1970's and 1980's some two dozen large (30 m diameter class) antennas were built in various African countries to provide the satellite links. Twenty six are currently known in 19 countries. As these antennas become redundant, the possibility exists to convert them for radio astronomy at a cost of roughly one tenth that of a new antenna of similar size. HartRAO, SKA Africa and the South African Department of Science and Technology (DST) have started exploring this possibility with some of the African countries...

  13. Allegheny County Major Rivers

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains locations of major rivers that flow through Allegheny County. These shapes have been taken from the Hydrology dataset. The Ohio River,...

  14. Qingjiang River Developer

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    THE 400-kilometer Qingjiang River, second tributary of the Yangtze River in Hubei Province, has a drainage area of 17,000 square kilometers. Its advantageous natural conditions have made it a key water power development project.

  15. Iowa's Sovereign Meandered Rivers

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This data set depicts Iowa's Meandered Rivers. These rivers are deemed sovereign land & therefore require any person wishing to conduct construction activities...

  16. River and Stream Pollution

    Science.gov (United States)

    ... Topics Games Activities Lessons MENU River and Stream Pollution Kids Homepage Topics Pollution River and Stream Pollution ... stream in the first place by disturbing the land as little as possible. Farmers and construction workers ...

  17. Onchocerciasis (River Blindness) FAQs

    Science.gov (United States)

    ... The CDC Parasites - Onchocerciasis (also known as River Blindness) Note: Javascript is disabled or is not supported ... infected Simulium blackfly. It is also called River Blindness because the fly that transmits infection breeds in ...

  18. South African AIDS plan criticised.

    Science.gov (United States)

    Sidley, P

    1998-10-17

    In a television broadcast, Deputy President Mbeki of South Africa announced a campaign against HIV/AIDS that would involve coordination between various government departments and nongovernmental organizations. Mbeki, who is associated with Virodene (a drug treatment for AIDS that is considered a scam), replaced President Mandela at the last minute in the broadcast. Two days after the broadcast, the government refused to support treatment of pregnant women infected with HIV with zidovudine to prevent transmission of the virus to the baby. The treatment is considered cost-effective by AIDS workers and public health officials. According to Mark Heywood of the AIDS law project at Witwatersrand University, 16% of pregnant women attending antenatal clinics were HIV-positive in 1997; this means that about 3 million South Africans (8% of the population) were living with HIV. Heywood said that the government believes there are 1500 new cases daily. By the end of 1998, 3.5 million South Africans will be living with HIV. Although the government is asking other sectors to join in the campaign, what the government is doing is unclear. Mother-to-child transmission of HIV is second only to transmission of the virus through heterosexual sex in South Africa. PMID:9841037

  19. Mithi River Restoration Project

    OpenAIRE

    Sanghani, Himanshu

    2009-01-01

    It took only few years to turn a naturally owing river into a drain. 17.84 k.m stretch of MithiNadi (river), an arterial river, running along north-south axis of Bombay (Mumbai) is facing the grimproblems of backyard atrocities. Finding its way through the odds of household garbage, industrialsewage, other pollutants and encroachments, Mithi river originates from the conuence of two essentialreservoirs; Vihar Lake and Powai Lake and merging with Arabian Sea at Mahim creek. The stategovernment...

  20. Regional view of a Trans-African Drainage System

    Directory of Open Access Journals (Sweden)

    Mohamed Abdelkareem

    2015-05-01

    Full Text Available Despite the arid to hyperarid climate of the Great Sahara of North Africa, pluvial climates dominated the region. Radar data shed some light on the postulated Trans-African Drainage System and its relationship to active and inactive tributaries of the Nile basin. Interpretations of recent elevation data confirm a source of the river water from the Red Sea highlands did not connect the Atlantic Ocean across Tushka basin, highlands of Uwinate and Darfur, and Chad basin, but northward to the ancestral Nile Delta. Elements of topography and climate were considered. They show that the former segments of the Nile closely mirror present-day tributaries of the Nile basin in drainage geometry, landscape, and climate. A rainfall data interpolation scenario revealed that this basin received concurrent runoff from both flanks such as Gabgaba-Allaqi to the east and Tushka basin to the west, similar to present-day Sobat and White Nile tributaries, respectively. Overall the western tributaries such as those of Tushka basin and Howar lead to the Nile, which was (and still is the biggest river system in Africa.

  1. Measuring River Pollution

    Science.gov (United States)

    Ayyavoo, Gabriel

    2004-01-01

    The Don River watershed is located within Canada's most highly urbanized area--metropolitan Toronto. Many residential and commercial uses, including alterations to the river's course with bridges, have had a significant impact on the Don's fauna and flora. Pollutants have degraded the river's water quality, a situation exacerbated by the…

  2. The hydrology of sand rivers in Zimbabwe and the use of remote sensing to assess their level of saturation

    Science.gov (United States)

    Mpala, S. C.; Gagnon, A. S.; Mansell, M. G.; Hussey, S. W.

    2016-06-01

    Sand rivers are ephemeral watercourses containing sand that are occasionally flooded with rainwater runoff during the rainy season. Although the riverbed appears dry for most of the year, there is perennial groundwater flow within the sand. This water flowing beneath the surface is a valuable resource for local communities; nonetheless our understanding of such river systems is limited. Hence, this paper aims to improve our understanding of the hydrology of sand rivers and to examine the potential use of remote sensing to detect the presence of water in the sand. The relationship between rainfall events and changes in the water level of two sand rivers in the Matabeleland South Province of Zimbabwe was investigated. A lagged relationship was observed for the Manzamnyama River but for the Shashani River the relationship was seen only when considering cumulative rainfall events. The comparison of the modelled flow as simulated by a water balance model with observations revealed the important influence of the effective sediment depth on the recharge and recession of the alluvial channels in addition to the length of the channel. The possibility of detecting water in the alluvial sands was investigated using remote sensing. During the wet season, optical images showed that the presence of water on the riverbed was associated with a smooth signal, as it tends to reflect the incident radiation. A chronological analysis of radar images for different months of the year demonstrates that it is possible to detect the presence of water in the sand rivers. These results are a first step towards the development of a methodology that would aim to use remote sensing to help reducing survey costs by guiding exploratory activities to areas showing signs of water abstraction potential.

  3. Late Quaternary stratigraphic development in the lower Luni, Mahi and Sabarmati river basins, western India

    Indian Academy of Sciences (India)

    M Jain; S K Tandon; S C Bhatt

    2004-09-01

    This study reviews the Quaternary alluvial stratigraphy in three semi-arid river basins of western India i.e., lower Luni (Rajasthan), and Mahi and Sabarmati (Gujarat alluvial plains). On the basis of OSL chronologies, it is shown that the existing intra-valley lithostratigraphic correlations require a revision. The sand, gravel and mud facies are present during various times in the three basins, however, the fluvial response to climate change, and the resulting facies associations, was different in the Thar desert as compared to that at the desert margin; this makes purely lithostratigraphic correlations unviable. It is further shown that the rivers in the Thar desert were more sensitive to climate change and had small response times and geomorphic thresholds as compared to the desert-margin rivers. This is illustrated during the early OIS 1, when the Luni river in the Thar desert was dynamic and showed frequent variations in fluvial styles such as gravel bedload braided streams, sand-bed ephemeral streams and meandering streams, all followed by incision during the early Holocene. The coeval deposits in Sabarmati, however, only show a meandering, floodplain-dominated river. Late Quaternary alluvial deposits in these basins unconformably overlie some older deposits that lack any absolute chronology. Based on the facies types and their associations, and the composition and architecture of the multistoried gravel sheets in the studied sections, it is suggested that older deposits are of pre-Quaternary age. This hypothesis implies the presence of a large hiatus incorporating much of the Quaternary period in the exposed sections.

  4. Educational Adaptation and Pan-Africanism: Trends in Africa.

    Science.gov (United States)

    Marah, John Karefah

    1987-01-01

    European colonialists believed that Africans should be educated in African traditional values, and that Africans should be made into dedicated workers, not holders of power. The African nationalists of the 1960s, in contrast, rejected most of the arduous aspects of European education as instruments of domination, and lay the foundation for the…

  5. Global drivers of future river flood risk

    Science.gov (United States)

    Winsemius, Hessel C.; Aerts, Jeroen C. J. H.; van Beek, Ludovicus P. H.; Bierkens, Marc F. P.; Bouwman, Arno; Jongman, Brenden; Kwadijk, Jaap C. J.; Ligtvoet, Willem; Lucas, Paul L.; van Vuuren, Detlef P.; Ward, Philip J.

    2016-04-01

    Understanding global future river flood risk is a prerequisite for the quantification of climate change impacts and planning effective adaptation strategies. Existing global flood risk projections fail to integrate the combined dynamics of expected socio-economic development and climate change. We present the first global future river flood risk projections that separate the impacts of climate change and socio-economic development. The projections are based on an ensemble of climate model outputs, socio-economic scenarios, and a state-of-the-art hydrologic river flood model combined with socio-economic impact models. Globally, absolute damage may increase by up to a factor of 20 by the end of the century without action. Countries in Southeast Asia face a severe increase in flood risk. Although climate change contributes significantly to the increase in risk in Southeast Asia, we show that it is dwarfed by the effect of socio-economic growth, even after normalization for gross domestic product (GDP) growth. African countries face a strong increase in risk mainly due to socio-economic change. However, when normalized to GDP, climate change becomes by far the strongest driver. Both high- and low-income countries may benefit greatly from investing in adaptation measures, for which our analysis provides a basis.

  6. Nutrient vectors and riparian nutrient processing in African semiarid savanna ecosystems

    Science.gov (United States)

    Jacobs, Shayne M.; Bechtold, J.S.; Biggs, Harry C.; Grimm, N. B.; McClain, M.E.; Naiman, R.J.; Perakis, Steven S.; Pinay, G.; Scholes, M.C.

    2007-01-01

    This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the impact of fire and herbivory are less pronounced and less predictable. Also unique is the presence of sodic soils in certain hillslopes, which substantially alters hydrological flowpaths and may act as a trap where nitrogen is immobilized while sediment and phosphorus transport is enhanced. Nutrients and sediments are also deposited in the riparian zone during seasonal, intermittent floods while, during the dry season, subsurface movement of water from the stream into riparian soils and vegetation further enrich riparian zones with nutrients. As is found in mesic ecosystems, nutrients are immobilized in semiarid riparian corridors through microbial and plant uptake, whereas dissimilatory processes such as denitrification may be important where labile nitrogen and carbon are in adequate supply and physical conditions are suitablea??such as in seeps, wallows created by animals, ephemeral wetlands and stream edges. Interaction between temporal hydrologic connectivity and spatial heterogeneity are disrupted by disturbances such as large floods and extended droughts, which may convert certain riparian patches from sinks to sources for nitrogen and phosphorus. In the face of increasing anthropogenic pressure, the scientific challenges are to provide a basic

  7. The utility of state parks as a conservation tool for isolated and ephemeral wetlands: A case study from the southern Blue Ridge

    Science.gov (United States)

    Howard, J. H.; Baldwin, R.; Pitt, A. L.; Baldwin, E. D.

    2013-12-01

    were deeper on average than park pools. We found significant differences in total taxonomic richness, invertebrate tolerance values and wetland depth between park and non-park wetlands. We relied heavily on local ecological knowledge (LEK) for identification and information on wetlands within parks. Furthermore, state parks played a vital role in the development of this project and our study was enriched as a result of utilizing state park personnel and their LEK. We were also able to interact with the public during our site visits and this two-way dialogue between scientists and the general public was useful for educating citizens about the importance of isolated/ephemeral wetlands and helped us better understand public perceptions of wetlands. State parks provided a number of study sites, various personnel who were knowledgeable about the locations and dynamics of wetlands and an a priori framework for conservation at the local scale which can help bolster conservation efforts at larger scales. We posit that state parks are an under-utilized but extremely important resource for filling the gaps in conservation.

  8. 21st Century South African Science Fiction

    Directory of Open Access Journals (Sweden)

    CARAIVAN LUIZA

    2014-12-01

    Full Text Available The paper analyses some aspects of South African science fiction, starting with its beginnings in the 1920s and focusing on some 21st century writings. Thus Lauren Beukes’ novels Moxyland (2008 and Zoo City (2010 are taken into consideration in order to present new trends in South African literature and the way science fiction has been marked by Apartheid. The second South African science fiction writer whose writings are examined is Henrietta Rose-Innes (with her novel Nineveh, published in 2011 as this consolidates women's presence in the SF world.

  9. Mandela’s Favourite African Folktales

    OpenAIRE

    Carmen Concilio

    2014-01-01

    In this essay I would like to examine the selection of African tales that Nelson Mandela took care to leave as heritage to the future generations, not only to children, and not only to African children. The fact that a political leader, ex freedom fighter and political prisoner dedicated his time to the collection and editing of stories from all over the African continent to be addressed to new readers as simple entertainment or as educational tools clearly testifies to the great humanity, cu...

  10. The African concept of caring for life

    Directory of Open Access Journals (Sweden)

    Maake Masango

    2005-10-01

    Full Text Available This article analyses the village concept of caring among African people. The old pattern of caring was based on the concept of ubuntu (humanity which respects people, because they are created in the imago Dei. Then the article compares the western concept of caring, which is based on individualism and people's privacy. Finally, economy, globalisation and this western concept are analysed. The impact of the above concepts affects Africans in urban areas, who are caught up in the two worlds, namely the African and western worlds.

  11. MISCONCEPTIONS OF DEPRESSION IN AFRICAN AMERICANS

    Directory of Open Access Journals (Sweden)

    Zohaib eSohail

    2014-06-01

    Full Text Available Major depression is a very common disabling disorder. Although the relationship between race and depression is complex, depression affects all races, all ethnic and geographic locations as well as all age groups. The prevalence of depression in African Americans is controversial, due to the paucity of research. The deficit in the knowledge and skills in treating depression in African Americans have not been adequately addressed so far. Inadequate and insufficient data on African Americans contributes to the problems of under diagnoses, misdiagnosis and under treatment of depression. This article will highlight the existing problem of depression in Afro American with a focus on diagnostic and treatment issues.

  12. The African American Wellness Village in Portland, Ore

    OpenAIRE

    McKeever, Corliss; Koroloff, Nancy; Faddis, Collaine

    2006-01-01

    More than 80% of African Americans in Oregon reside in the Portland metropolitan area; African Americans comprise 1.7% of the state's population. Although relatively small, the African American population in the state experiences substantial health disparities. The African American Health Coalition, Inc was developed to implement initiatives that would reduce these disparities and to promote increased communication and trust between the African American community and local institutions and or...

  13. African diatom palaeoecology and biostratigraphy

    Science.gov (United States)

    Gasse, F.; Fourtanier, E.

    This paper illustrates the different types of information which can be deduced from African diatoms studies. The first section is devoted to the reconstruction of palaeoenvironments. The accuracy of ecological data (estimates of ecological variables e.g. types of habitats, water chemistry…) depends on the times scale and on the spatial scale considered: short-term environments in a given waterbody, environmental evolution during individual humid episodes considered locally or regionally, long-term changes in diatom flora induced by major climatic tendencies at a regional or continental scale. One then summarizes our present state of knowledge in diatom biostratigraphy in Africa. Several centric taxa, belonging to the genera Aulacoseira, Mesodictyon, Cyclotella, Stephanodiscus and Cyclostephanos appear to have limited stratigraphical ranges and to be good chronological markers.

  14. African Biochemists Plan More Collaboration

    Directory of Open Access Journals (Sweden)

    Peter N. Campbell

    2000-01-01

    Full Text Available The Federation of European Biochemical Societies (FEBS was the first regional organisation of biochemists, holding its first congress in London in 1964. There followed the creation of the Pan American Association of Biochemical Societies (PAABS and then the Federation of Asian and Oceanian Biochemists (FAOB. An obvious development was the formation of a similar organisation to take care of Africa, but this proved impossible so long as apartheid survived in South Africa. With the removal of the latter, the way was clear for the foundation of the Federation of African Societies of Biochemistry and Molecular Biology (FASBMB. The first congress of the new federation was held in Nairobi in September 1996 under the Presidency of Prof. Dominic Makawiti of Nairobi University. Among the 300 participants were representatives from 19 countries in Africa. The second congress was held at Potchefstroom in South Africa in 1998 and the third was just held in Cairo.

  15. Africa Pentecostalized? Understanding the African appropriation of Pentecostalism in light of African perspectives

    OpenAIRE

    Østhassel, Ole Aleksander

    2013-01-01

    I want to prepare an understanding of why Pentecostalism seems to be so attractive in Africa. I will outline Ogbu Kalu's understanding of a resonance between African traditional culture and Pentecostalism, and then add perspectives from other African scholars. And the research problem follows: How can we understand the appropriation of Pentecostalism in Africa in light of Ogbu Kalu? Research questions will be: In what way do Pentecostalism and African traditional cult...

  16. Enhancing the African bioethics initiative

    Directory of Open Access Journals (Sweden)

    Ogundiran Temidayo O

    2004-10-01

    Full Text Available Abstract Background Medical ethics has existed since the time of Hippocrates. However, formal training in bioethics did not become established until a few decades ago. Bioethics has gained a strong foothold in health sciences in the developed world, especially in Europe and North America. The situation is quite different in many developing countries. In most African countries, bioethics – as established and practiced today in the west- is either non-existent or is rudimentary. Discussion Though bioethics has come of age in the developed and some developing countries, it is still largely "foreign" to most African countries. In some parts of Africa, some bioethics conferences have been held in the past decade to create research ethics awareness and ensure conformity to international guidelines for research with human participants. This idea has arisen in recognition of the genuine need to develop capacity for reviewing the ethics of research in Africa. It is also a condition required by external sponsors of collaborative research in Africa. The awareness and interest that these conferences have aroused need to be further strengthened and extended beyond research ethics to clinical practice. By and large, bioethics education in schools that train doctors and other health care providers is the hook that anchors both research ethics and clinical ethics. Summary This communication reviews the current situation of bioethics in Africa as it applies to research ethics workshops and proposes that in spite of the present efforts to integrate ethics into biomedical research in Africa, much still needs to be done to accomplish this. A more comprehensive approach to bioethics with an all-inclusive benefit is to incorporate formal ethics education into health training institutions in Africa.

  17. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... the African-American that we treat this as what it is -- an epidemic. Winston Dyer: My introduction ... being ignorant to prostate cancer -- and not knowing what it was -- that was my first, first, first- ...

  18. Cardiac assessment of African hedgehogs (Atelerix albiventris).

    Science.gov (United States)

    Black, Peter A; Marshall, Cecilia; Seyfried, Alice W; Bartin, Anne M

    2011-03-01

    Cardiomyopathy is a common finding in captive African hedgehogs (Atelerix albiventris) at postmortem exam. To date, treatment attempts have been mostly empirical and unrewarding. The objective of this study was to determine reference cardiac values for captive African hedgehogs based on echocardiogram, electrocardiogram (ECG), and radiographs. Adult African hedgehogs with no clinical signs of cardiac disease (n = 13) were selected. Each animal was anesthetized with isoflurane via facemask and an echocardiogram, ECG, and radiographs were performed. Standard measurements were taken and the descriptive statistics performed. Values were comparable to limited data available in other hedgehog species and other similar-sized exotic species. Two animals were removed from consideration of reference values due to valvular defects that were considered significant. These data are the first establishing cardiac parameters in normal African hedgehogs using radiographic cardiac measurement, echocardiogram, and ECG. Evaluating animals with possible cardiomyopathy may allow for earlier diagnosis and more successful treatment. PMID:22946370

  19. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... runs higher. We really don't know. But I would strongly suggest to the African-American that ... then my dad four months later. And then I was told by doctors that I should be ...

  20. Development of 'Serunding' from African catfish

    DEFF Research Database (Denmark)

    Juhari, Nurul Hanisah Binti; MK, Zainol; MM, Masduki

    This research was conducted to develop serunding from African catfish (Clarias gariepinus). Proximate analysis, physical analysis, ascorbic acid analysis, mineral analysis and sensory evaluation were carried out to determine the nutrient compositions and consumer acceptance towards the products. ...

  1. Growth and Institutions in African Development

    OpenAIRE

    Asongu, Simplice A.

    2015-01-01

    Edited by Augustin K. Fosu Routledge Studies in Development Economics, 2015, pp. 393 (Hardcover). Reviewed by Simplice A. Asongu African Governance and Development Institute P.O. Box 8413, Yaoundé, Cameroon.

  2. AN ALTERNATIVE VIEW OF SOUTH AFRICAN ARTILLERY

    Directory of Open Access Journals (Sweden)

    A.C. Lillie

    2012-02-01

    Full Text Available It has been said that 'Necessity is the mother of invention' and there can be few countries, if any, where this is more true than in South Africa.In the late 1930's, prior to World War II, the South African Artillery was severely restricted due to its lack of mobility. The inventiveness shown in tackling this probelm is surely not a thing of the past and the possiblity of adapting South African artillery to current South african needs in warfare should not be overlooked. The South African Defence Force is not able to purchase armament in a free and open market place and the costs of developing new artillery are prohibitive in a country of South Africa's size. it will be argued that it is necessary and possible, in the short term, to take what is currently available and adapt this to South Africa's needs.

  3. African American Men and Prostate Cancer

    Medline Plus

    Full Text Available ... Walker: The researchers don't know exactly why. It is suggested that maybe our diet, maybe our ... African-American that we treat this as what it is -- an epidemic. Winston Dyer: My introduction to ...

  4. The innovative African kilowatt-hour

    International Nuclear Information System (INIS)

    There is a worldwide resurgence of interest in pricing electricity. Whether motivated by deregulation and the treat of competition (as in England and New Zealand) or by restructuring of regulatory goals to encourage competition or conservation (as in the United States), electricity suppliers and distributors are seeing pricing as a means of safeguarding, maintaining, increasing sales. South Africa is no exception in this regard. Past and proposed new developments in electricity pricing in the South African electricity supply industry are discussed, in response to pressures across several fronts: pressures from customers to reduce electricity prices to facilitate growth and survival in the South African economy; the national electrification program; the appointment of the National Electricity Regulator; moves by Southern African electricity utilities to establish a Southern African grid. The current status of electricity pricing, metering, demand profile research and demand management in South Africa are overviewed. (author)

  5. The innovative African kilowatt-hour

    Energy Technology Data Exchange (ETDEWEB)

    Calitz, A.C. [ESKOM, Johannesburg (South Africa)

    1996-12-31

    There is a worldwide resurgence of interest in pricing electricity. Whether motivated by deregulation and the treat of competition (as in England and New Zealand) or by restructuring of regulatory goals to encourage competition or conservation (as in the United States), electricity suppliers and distributors are seeing pricing as a means of safeguarding, maintaining, increasing sales. South Africa is no exception in this regard. Past and proposed new developments in electricity pricing in the South African electricity supply industry are discussed, in response to pressures across several fronts: pressures from customers to reduce electricity prices to facilitate growth and survival in the South African economy; the national electrification program; the appointment of the National Electricity Regulator; moves by Southern African electricity utilities to establish a Southern African grid. The current status of electricity pricing, metering, demand profile research and demand management in South Africa are overviewed. (author).

  6. EL AJARAFE: UN ESPACIO SERRANO OCUPADO EFÍMERAMENTE EN DIFERENTES MOMENTOS DEL HOLOCENO (TANDILIA, PROVINCIA DE BUENOS AIRES / El Ajarafe: An ephemeral mountain space occupied at different times of the Holocene (Tandilia, Province of Buenos Aires

    Directory of Open Access Journals (Sweden)

    Natalia Mazzia

    2011-12-01

    Full Text Available El Ajarafe es un sitio arqueológico excavado recientemente en el sector centro oriental del sistema serrano de Tandilia, provincia de Buenos Aires, Argentina. Se trata de un pequeño reparo rocoso ubicado en la cima de Sierra Larga sur. A partir de cuatro fechados radiocarbónicos fueron identificados tres momentos de ocupación humana de carácter efímero ocurridos en el Holoceno temprano y en el Holoceno tardío. En este trabajo se presenta la descripción del sitio, sus características espaciales y contextuales y los resultados obtenidos a partir de los diferentes análisis realizados. Entre éstos se incluyen análisis tecnomorfológicos de los conjuntos líticos, de procedencia de materias primas líticas y de sustancias adheridas a las superficies de los objetos mediante cromatografía gaseosa; además de análisis espaciales mediante el uso de Sistemas de Información Geográfica. A partir de la información presentada, tomando al sitio El Ajarafe como punto de partida, se propone una discusión sobre las ocupaciones humanas efímeras registradas en el ámbito serrano de Tandilia a lo largo del tiempo.   Palabras clave: cazadores recolectores; ocupaciones efímeras; Holoceno; Tandilia; Región Pampeana   Abstract El Ajarafe is an archaeological site recently excavated in the central east portion of Tandilia range, in the Buenos Aires province, Argentina. It is a small rock shelter located on the hilltop of the south portion of Sierra Larga. Three different ephemeral human occupations during early and late Holocene were identified by four radiocarbon dates. In this paper we introduce the description of the site along with its contextual and spatial characteristics. The results of different analyses are presented, as well, including the technomorphological analysis of the lithic assemblage, the lithic raw materials provenience and quantification and the gas chromatography analysis applied to organic substances adhered to the surface of

  7. 76 FR 51887 - Safety Zone; Patuxent River, Patuxent River, MD

    Science.gov (United States)

    2011-08-19

    ...) entitled ``Safety Zone; Patuxent River, Patuxent River, MD'' in the Federal Register (76 FR 36447). We... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Patuxent River, Patuxent River, MD AGENCY... safety zone during the ``NAS Patuxent River Air Expo '11,'' which consists of aerial...

  8. Contemporary Literature in the African Diaspora

    OpenAIRE

    Barrios Herrero, Olga; Bell, Bernard W.

    1997-01-01

    [ES] El libro es una colección de ensayos divididos entre las tres grandes secciones del libro: Literatura afroamericana, Literatura Afro-caribeña y Afro-latinoamericana y Literatura africana en inglés. [EN] The book is a collection of essays included in the three sections of the book: on African American Literature, Afro-Caribbean and Afro-Latin American Literature and African Literature in English.

  9. Development of 'Serunding' from African catfish

    OpenAIRE

    Juhari, Nurul Hanisah Binti; MK, Zainol; MM, Masduki

    2009-01-01

    This research was conducted to develop serunding from African catfish (Clarias gariepinus). Proximate analysis, physical analysis, ascorbic acid analysis, mineral analysis and sensory evaluation were carried out to determine the nutrient compositions and consumer acceptance towards the products. samples of serunding were prepared with 3 different sizes (30-40cm, 40-50cm, 50-60cm) of African catfish and control was prepared using round scad fish ('ikan selayang') with same amount of fish flesh...

  10. Corynebacterial pneumonia in an African hedgehog.

    Science.gov (United States)

    Raymond, J T; Williams, C; Wu, C C

    1998-04-01

    A 3-mo-old, male African hedgehog (Atelerix albiventris) was anorectic and lethargic for a period of 3 days prior to death. Necropys revealed lungs that were diffusely firm, dark red, and dorsally adhered by fibrinous tags to the pericardial sac. Histopathology revealed necrosuppurative bronchopneumonia with pulmonary abscesses and suppurative pericarditis and myocarditis. A Corynebacterium sp. was isolated from the lungs. We believe this is the first reported case of corynebacterial pneumonia in an African hedgehog. PMID:9577794

  11. Intestinal lymphosarcoma in captive African hedgehogs.

    Science.gov (United States)

    Raymond, J T; Clarke, K A; Schafer, K A

    1998-10-01

    Two captive adult female African hedgehogs (Atelerix albiventris) had inappetance and bloody diarrhea for several days prior to death. Both hedgehogs had ulceration of the small intestine and hepatic lipidosis. Histopathology revealed small intestinal lymphosarcoma with metastasis to the liver. Extracellular particles that had characteristics of retroviruses were observed associated with the surface of some neoplastic lymphoid cells by transmission electron microscopy. These are the first reported cases of intestinal lymphosarcoma in African hedgehogs. PMID:9813852

  12. The african protoproverbial in a multipolar world

    OpenAIRE

    Taiwo, Ọlọruntọba-Oju

    2014-01-01

    The proverb is a rhetorical universal and as such shares features across linguistic, ethnic and culture boundaries, thus making typological distinctions along ethnic or regional lines a daunting task. Further complicating this scenario within the African context is the relentless hybridization and subversion of the African proverb consequent on colonial contact and sundry postcolonial interventions. This twin trajectory, the conceptual universalism of the proverb and the relent...

  13. African American Culture and Hypertension Prevention

    OpenAIRE

    Peters, Rosalind M.; Aroian, Karen J.; Flack, John M.

    2006-01-01

    A qualitative study was done to explore attitudes and beliefs of African Americans regarding hypertension-preventive self-care behaviors. Five focus groups, with 34 participants, were held using interview questions loosely based on the Theory of Planned Behavior (TPB). Analysis revealed themes broadly consistent with the TPB, and also identified an overarching theme labeled “circle of culture.” The circle is a metaphor for ties that bind individuals within the larger African American communit...

  14. Language and Culture in African Postcolonial Literature

    OpenAIRE

    Asante-Darko, Kwaku

    2000-01-01

    In his article, "Language and Culture in African Postcolonial Literature," Kwaku Asante-Darko offers both conceptual basis and empirical evidence in support of the fact that critical issues concerning protest, authenticity, and hybridity in African post-colonial literature have often been heavily laden with nationalist and leftist ideological encumbrances, which tended to advocate the rejection of Western standards of aesthetics. One of the literary ramifications of nationalist/anti-colonial ...

  15. Economic Key to Sino-African Ties

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Following Chinese President Hu Jintao's visit to Africa's Morocco, Nigeria and Kenya in April, Chinese Premier Wen Jiabao is currently visiting seven African countries-Egypt, Ghana, Republic of Congo, Angola, South Africa, Tanzania and Uganda. Haile-Kiros Gessesse, Ethiopia's Ambassador to China, discussed with Beijing Review reporter Ni Yanshuo the future of the Sino-African relationship. As special envoy for the Forum on China-Africa Cooperation, he also expressed his expectations of the forum summit t...

  16. 黄土区坡耕地耕作对浅沟径流产沙及其形态发育特征的影响%Effect of tillage on runoff and sediment yields and morphology development characteristic of ephemeral gully in loessial region

    Institute of Scientific and Technical Information of China (English)

    郭明明; 王文龙; 李建明; 朱宝才; 史倩华; 康宏亮; 李艳富; 李垚林

    2015-01-01

    In the hill-gully area of the Loess Plateau, serious man-made soil and water loss occurs in disturbed soils of sloping farmlands formed in the process of tillage operation. Frequent farming activities cause ephemeral gullies to develop continuously on sloping farmlands. Although an ephemeral gully may be refilled and rehabilitated, new ephemeral gully may develop in the original position in next rainy season. An indoor flow scouring experiment under artificially simulated rainfall was carried out in the State Key Laboratory of Soil Erosion and Dryland Agriculture on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, China in July 2014. The effects of tillage treatments on runoff and sediment yielding in ephemeral gully and its morphology were investigated at different rainfall intensities and slope degrees under the condition of upslope concentrated flow. Based on preliminary field investigations, 3 slope degrees of 15°, 20° and 25° were selected. Rainfall intensity was designed at 1.0, 1.5, and 2.0 mm/min. Flow discharges were 7.53 to 23.45 L/min. Plots of 8 m×1m were laid out for experiments and 3 flow sections were set up for runoff and sediment measurements. Before each test, rainfall intensity was calibrated repeatedly until the rainfall uniformity coefficient reached 85% or above. During each test, flow velocity was measured with dye tracing method and flow width and depth were measured with point gauge system. Runoff sample was taken once a minute within 3 minutes before runoff generation, and once 3 minutes after runoff generation. The results showed that: 1) Flow regimes for non-tilled and tilled ephemeral gullies were characterized by turbulent flow; Tillage could decrease Reynolds number and Froude number by 0.95%-30.77% and 3.41%-35.66%, and increase Darcy-Weisbachcoefficient and Manning roughness coefficient by 4.01%-58.82% and 0.88%-27.87%, respectively; and 2) Compared to non

  17. Application of techniques to identify coal-mine and power-generation effects on surface-water quality, San Juan River basin, New Mexico and Colorado

    Science.gov (United States)

    Goetz, C.L.; Abeyta, Cynthia G.; Thomas, E.V.

    1987-01-01

    Numerous analytical techniques were applied to determine water quality changes in the San Juan River basin upstream of Shiprock , New Mexico. Eight techniques were used to analyze hydrologic data such as: precipitation, water quality, and streamflow. The eight methods used are: (1) Piper diagram, (2) time-series plot, (3) frequency distribution, (4) box-and-whisker plot, (5) seasonal Kendall test, (6) Wilcoxon rank-sum test, (7) SEASRS procedure, and (8) analysis of flow adjusted, specific conductance data and smoothing. Post-1963 changes in dissolved solids concentration, dissolved potassium concentration, specific conductance, suspended sediment concentration, or suspended sediment load in the San Juan River downstream from the surface coal mines were examined to determine if coal mining was having an effect on the quality of surface water. None of the analytical methods used to analyzed the data showed any increase in dissolved solids concentration, dissolved potassium concentration, or specific conductance in the river downstream from the mines; some of the analytical methods used showed a decrease in dissolved solids concentration and specific conductance. Chaco River, an ephemeral stream tributary to the San Juan River, undergoes changes in water quality due to effluent from a power generation facility. The discharge in the Chaco River contributes about 1.9% of the average annual discharge at the downstream station, San Juan River at Shiprock, NM. The changes in water quality detected at the Chaco River station were not detected at the downstream Shiprock station. It was not possible, with the available data, to identify any effects of the surface coal mines on water quality that were separable from those of urbanization, agriculture, and other cultural and natural changes. In order to determine the specific causes of changes in water quality, it would be necessary to collect additional data at strategically located stations. (Author 's abstract)

  18. Changes in northeast African hydrology and vegetation associated with Pliocene-Pleistocene sapropel cycles.

    Science.gov (United States)

    Rose, Cassaundra; Polissar, Pratigya J; Tierney, Jessica E; Filley, Timothy; deMenocal, Peter B

    2016-07-01

    East African climate change since the Late Miocene consisted of persistent shorter-term, orbital-scale wet-dry cycles superimposed upon a long-term trend towards more open, grassy landscapes. Either or both of these modes of palaeoclimate variability may have influenced East African mammalian evolution, yet the interrelationship between these secular and orbital palaeoclimate signals remains poorly understood. Here, we explore whether the long-term secular climate change was also accompanied by significant changes at the orbital-scale. We develop northeast African hydroclimate and vegetation proxy data for two 100 kyr-duration windows near 3.05 and 1.75 Ma at ODP Site 967 in the eastern Mediterranean basin, where sedimentation is dominated by eastern Sahara dust input and Nile River run-off. These two windows were selected because they have comparable orbital configurations and bracket an important increase in East African C4 grasslands. We conducted high-resolution (2.5 kyr sampling) multiproxy biomarker, H- and C-isotopic analyses of plant waxes and lignin phenols to document orbital-scale changes in hydrology, vegetation and woody cover for these two intervals. Both intervals are dominated by large-amplitude, precession-scale (approx. 20 kyr) changes in northeast African vegetation and rainfall/run-off. The δ(13)Cwax values and lignin phenol composition record a variable but consistently C4 grass-dominated ecosystem for both intervals (50-80% C4). Precessional δDwax cycles were approximately 20-30‰ in peak-to-peak amplitude, comparable with other δDwax records of the Early Holocene African Humid Period. There were no significant differences in the means or variances of the δDwax or δ(13)Cwax data for the 3.05 and 1.75 Ma intervals studied, suggesting that the palaeohydrology and palaeovegetation responses to precessional forcing were similar for these two periods. Data for these two windows suggest that the eastern Sahara did not experience the

  19. River Restoration and Meanders

    OpenAIRE

    G. Mathias Kondolf

    2006-01-01

    Among the most visually striking river restoration projects are those that involve the creation of a new channel, often in a new alignment and generally with a form and dimensions that are different from those of the preproject channel. These channel reconstruction projects often have the objective of creating a stable, single-thread, meandering channel, even on rivers that were not historically meandering, on rivers whose sediment load and flow regime would not be consistent with such stable...

  20. Dispersion in Alluvial River

    OpenAIRE

    Ferdousi, Amena

    2014-01-01

    River pollution is the contamination of river water by pollutant being discharged directly or indirectly on it. Depending on the degree of pollutant concentration, subsequent negative environmental effects such as oxygen depletion and severe reductions in water quality may occur which affect the whole environment. River pollution can then cause a serious threat for fresh water and as well as the entire living creatures. Dispersion in natural stream is the ability of a stream to dilute soluble...

  1. The Freshwater Oyster Etheria elliptica as a Tool to Reconstruct Climate Variability across the African Continent

    Science.gov (United States)

    Vanhove, D.; Gillikin, D. P.; Kelemen, Z.; Bouillon, S.

    2015-12-01

    The bivalve Etheria elliptica occurs abundantly in (sub)tropical African river basins. We investigate its potential use for the reconstruction of ambient water chemistry and climate by means of stable oxygen isotope ratios in specimens from the Congo river (Kisangani), the Oubangui river (Bangui) and the Victoria Nile (Jinja). Unlike other common African bivalve species, E. elliptica contains distinct organic-rich growth increments, previously suggested to correlate with lunar periodicity. However, cavities in the shell complicate age reading and little is known about the exact timing and continuity of these growth increments. We set up a comparative study between different techniques to visualize and enhance growth features, and find that staining with Mutvei's solution and confocal fluorescence microscopy perform equally well. Despite the presence of cavities, growth lines can generally be followed from umbo to shell margin. Moreover, preliminary δ18O results of two micro-sampled specimens from the Oubangui river show that 12-13 growth lines occur within one year of growth. This corroborates that these increments can be used as temporal anchor points, providing a moon-monthly time frame for sequential microchemistry. In two Congo river specimens, δ18Oshell values vary between -1.9 and -3.8 ‰ (VPDB), in line with a predicted range of -2.1 to -4.1 ‰ based on fortnightly δ18Owater and T monitoring. Reconstructed intra-annual δ18Owater variability from δ18Oshell values and observed T correlates with discharge, reflecting rainfall and runoff variability in the upstream catchment area. In two Victoria Nile specimens, collected 20 km downstream from Lake Victoria, δ18Oshell values are high and relatively constant, varying between +1.8 and +3.2 ‰. Enrichment of 18Oshell is consistent with isotopically heavy rainfall signatures and elevated surface evaporation in Lake Victoria. These first results suggest that E. elliptica is well-suited for the reconstruction

  2. Perceptions of African American and European American Teachers on the Education of African American Boys

    Science.gov (United States)

    Bacon, Ellen; Banks, Joy; Young, Kathryn; Jackson, Francesina R.

    2007-01-01

    The authors interviewed 27 teachers (16 African American and 11 European American) on instructional factors contributing to overidentification of behavior problems in African American boys. Interviews focused on teachers' perspectives of effective teachers, teacher-student relationships, and communication styles. Analysis of the interviews showed…

  3. African American Pastors' Beliefs and Actions Regarding Childhood Incest in the African American Community

    Science.gov (United States)

    Wells, Tesia Denis

    2012-01-01

    This quantitative study sought to explore African American pastors' beliefs and actions regarding childhood incest in the African American community and their decisions to inform the proper authorities. This exploratory study was developed in order to draw both public and academic attention to the understudied phenomenon of childhood incest…

  4. Research with African Americans: Lessons Learned about Recruiting African American Women

    Science.gov (United States)

    Coker, Angela D.; Huang, Hsin-Hsin; Kashubeck-West, Susan

    2009-01-01

    The authors briefly explore literature related to recruiting African American research participants, reflect on their experiences conducting body image research with a sample of African American college women in an earlier study (S. Kashubeck-West et al., 2008), and discuss some methodological and cultural challenges that they encountered during…

  5. A SNP test to identify Africanized honeybees via proportion of 'African' ancestry.

    Science.gov (United States)

    Chapman, Nadine C; Harpur, Brock A; Lim, Julianne; Rinderer, Thomas E; Allsopp, Michael H; Zayed, Amro; Oldroyd, Benjamin P

    2015-11-01

    The honeybee, Apis mellifera, is the world's most important pollinator and is ubiquitous in most agricultural ecosystems. Four major evolutionary lineages and at least 24 subspecies are recognized. Commercial populations are mainly derived from subspecies originating in Europe (75-95%). The Africanized honeybee is a New World hybrid of A. m. scutellata from Africa and European subspecies, with the African component making up 50-90% of the genome. Africanized honeybees are considered undesirable for bee-keeping in most countries, due to their extreme defensiveness and poor honey production. The international trade in honeybees is restricted, due in part to bans on the importation of queens (and semen) from countries where Africanized honeybees are extant. Some desirable strains from the United States of America that have been bred for traits such as resistance to the mite Varroa destructor are unfortunately excluded from export to countries such as Australia due to the presence of Africanized honeybees in the USA. This study shows that a panel of 95 single nucleotide polymorphisms, chosen to differentiate between the African, Eastern European and Western European lineages, can detect Africanized honeybees with a high degree of confidence via ancestry assignment. Our panel therefore offers a valuable tool to mitigate the risks of spreading Africanized honeybees across the globe and may enable the resumption of queen and bee semen imports from the Americas. PMID:25846634

  6. Fat, fibre and cancer risk in African Americans and rural Africans

    NARCIS (Netherlands)

    O'Keefe, S.J.; Li, J.V.; Lahti, Leo; Ou, J.; Carbonero, F.; Khaled, M.; Postma, J.M.; Kinross, J.; Wahl, E.; Ruder, E.; Vipperla, K.; Naidoo, V.; Mtshali, L.; Tims, S.; Puylaert, P.G.B.; DeLany, J.; Krasinskas, A.; Benefiel, A.C.; Kaseb, H.O.; Newton, K.; Nicholson, J.K.; Vos, De W.M.; Gaskins, H.R.; Zoetendal, E.G.

    2015-01-01

    Rates of colon cancer are much higher in African Americans (65:100,000) than in rural South Africans (<5:100,000). The higher rates are associated with higher animal protein and fat, and lower fibre consumption, higher colonic secondary bile acids, lower colonic short-chain fatty acid quantities and

  7. Changing Fatherhood: An Exploratory Qualitative Study with African and African Caribbean Men in England

    Science.gov (United States)

    Williams, Robert; Hewison, Alistair; Wildman, Stuart; Roskell, Carolyn

    2013-01-01

    This paper presents findings from a qualitative study undertaken with 46 African and African Caribbean men exploring their experiences of fatherhood. Data analysis was informed by Connell's theoretical work on changing gender relations. Findings indicate that fathers' lives were mediated by masculinities, racism, gender, migration and…

  8. Crossing Cultures in Marriage: Implications for Counseling African American/African Couples

    Science.gov (United States)

    Durodoye, Beth A.; Coker, Angela D.

    2008-01-01

    A wealth of literature exists regarding intermarriage between White and ethnic minority couples. Noticeably lacking, however, is information considering within-group diversity amongst Black couples. This paper will focus on cultural dynamics that may operate with African American and African couples residing in the United States. Through an…

  9. Trade in Educational Services: Reflections on the African and South African Higher Education System

    Science.gov (United States)

    Sehoole, Chika Trevor

    2004-01-01

    This article discusses and analyses the emergence of globalisation and its impact on developments within the African continent. Africa's response at a regional level through the New Partnership for Africa's Development and at a subregional level through the Southern African Development Community's "Protocol on Education" come under scrutiny. These…

  10. "Women ... Mourn and Men Carry on": African Women Storying Mourning Practices--A South African Example

    Science.gov (United States)

    Kotze, Elmarie; Els, Lishje; Rajuili-Masilo, Ntsiki

    2012-01-01

    African mourning of loss of lives in South Africa has been shaped by discursive practices of both traditional African cultures and the sociopolitical developments under apartheid and in post-apartheid South Africa. This article reports on changes in mourning practices on the basis of a literature review and uses a collection of examples to…

  11. The taxonomic status of two West African Leptopelis species: L. macrotis Schiøtz, 1967 and L. spiritusnoctis Rödel, 2007 (Amphibia: Anura: Arthroleptidae

    Directory of Open Access Journals (Sweden)

    Mark-Oliver Roedel

    2014-03-01

    Full Text Available We herein examine the taxonomic status of two West African forest-dwelling Leptopelis species. The small L. spiritusnoctis, described from the Upper Guinean forests of West Africa, was recently synonymized with L. aubryi, described from Gabon. The large L. macrotis, known from Ghana to Sierra Leone, was downgraded to a subspecies of L. millsoni, ranging from the Niger Delta to eastern Democratic Republic of Congo. These taxonomic decisions are in contrast to the general biogeographic pattern of African forest anurans and we consequently tested if the morphologically similar taxon pairs are indeed conspecifics by applying acoustic and molecular techniques. Both techniques confirmed that populations from West Africa differ significantly from their Central African morphological equivalents. Consequently, we herein resurrect L. spiritusnoctis as a valid species. The acoustic data indicate that L. aubryi may comprise a complex of cryptic species. We further advocate using the name L. macrotis for West African and L. millsoni for Central African populations of these larger arboreal frogs. However, we had neither genetic nor acoustic data from the type locality of L. millsoni available and could not clarify if these frogs belong to the more western or eastern taxon or even represent a Nigerian endemic. Thus, it is possible that West African populations need to be termed L. millsoni in the future. For populations east of the Cross River, Nigeria, the name L. guineensis would be available.

  12. RIVER FLOW CONDITIONS AND DYNAMIC STATE ANALYSIS OF PAHANG RIVER

    OpenAIRE

    Muhamad Barzani Gasim; M. E. Toriman; Mushrifah Idris; Pan Ian Lun; M. K.A. Kamarudin; A. A. Nor Azlina; Mazlin Mokhtar; S.A. Sharifah Mastura

    2013-01-01

    Pahang River (Sg. Pahang) is the longest river in Peninsular Malaysia. Flood is a common event in Pahang River Basin during wet season which triggered by monsoon season. The hydrodynamic study of Pahang River should be well understood especially when it is a target of northeast monsoon which influenced the Pahang River Basin every year (from November to March). 17 river cross section stations were selected and used to measure its drainage capacity, hydraulic parameters and estimation of flow ...

  13. 77 FR 37886 - Notice of Intent To Obtain Information Regarding Organizations Who Are Assisting African...

    Science.gov (United States)

    2012-06-25

    ... African Governments To Increase Healthcare Institution Capacity To Maintain Complex Medical Equipment..., which are currently helping African government hospitals, clinics, laboratories, and other African... involved in enhancing the long term ability of African government health institutions to maintain...

  14. Henipavirus RNA in African bats.

    Directory of Open Access Journals (Sweden)

    Jan Felix Drexler

    Full Text Available BACKGROUND: Henipaviruses (Hendra and Nipah virus are highly pathogenic members of the family Paramyxoviridae. Fruit-eating bats of the Pteropus genus have been suggested as their natural reservoir. Human Henipavirus infections have been reported in a region extending from Australia via Malaysia into Bangladesh, compatible with the geographic range of Pteropus. These bats do not occur in continental Africa, but a whole range of other fruit bats is encountered. One of the most abundant is Eidolon helvum, the African Straw-coloured fruit bat. METHODOLOGY/PRINCIPAL FINDINGS: Feces from E. helvum roosting in an urban setting in Kumasi/Ghana were tested for Henipavirus RNA. Sequences of three novel viruses in phylogenetic relationship to known Henipaviruses were detected. Virus RNA concentrations in feces were low. CONCLUSIONS/SIGNIFICANCE: The finding of novel putative Henipaviruses outside Australia and Asia contributes a significant extension of the region of potential endemicity of one of the most pathogenic virus genera known in humans.

  15. Park Service prepares river plans

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This article is on the designation of sections of the Missouri River, Niobrara River and Verdigre Creek in Nebraska and South Dakota as a national recreation river...

  16. Effects of flooding and tamarisk removal on habitat for sensitive fish species in the San Rafael River, Utah: implications for fish habitat enhancement and future restoration efforts.

    Science.gov (United States)

    Keller, Daniel L; Laub, Brian G; Birdsey, Paul; Dean, David J

    2014-09-01

    Tamarisk removal is a widespread restoration practice on rivers in the southwestern USA, but impacts of removal on fish habitat have rarely been investigated. We examined whether tamarisk removal, in combination with a large spring flood, had the potential to improve fish habitat on the San Rafael River in southeastern Utah. We quantified habitat complexity and the distribution of wood accumulation in a tamarisk removal site (treated) and a non-removal site (untreated) in 2010, 1 year prior to a large magnitude and long-duration spring flood. We used aerial imagery to analyze river changes in the treated and untreated sites. Areas of channel movement were significantly larger in the treated site compared to the untreated site, primarily because of geomorphic characteristics of the channel, including higher sinuosity and the presence of an ephemeral tributary. However, results suggest that tamarisk removal on the outside of meander bends, where it grows directly on the channel margins, can promote increased channel movement. Prior to the flood, wood accumulations were concentrated in sections of channel where tamarisk had been removed. Pools, riffles, and backwaters occurred more frequently within 30 m upstream and downstream of wood accumulations compared to areas within 30 m of random points. Pools associated with wood accumulations were also significantly larger and deeper than those associated with random points. These results suggest that the combination of tamarisk removal and wood input can increase the potential for channel movement during spring floods thereby diversifying river habitat and improving conditions for native fish. PMID:24993795

  17. Conservation biology of the Cross River gorilla (Gorilla gorilla diehli)

    Science.gov (United States)

    Bergl, Richard Alexander

    The Cross River gorilla (Gorilla gorilla diehli), a recently revived fourth subspecies of gorilla, is the most endangered and poorly studied ape taxon. Only about 300 Cross River gorillas remain and these gorillas occur in at least eleven different localities. This dissertation presents a population-wide assessment of threats to this population based on molecular genetic data, satellite imagery and demographic modeling. I used DNA extracted from non-invasively collected fecal samples to amplify eleven microsatellite loci for population genetic analysis. Microsatellite data suggested that a complex population structure is present in the Cross River gorilla, with three genetically identifiable subpopulations present. Though levels of gene flow between certain subpopulations were low, there is evidence that reproductive contact persists between many of the subpopulations. The genetic data also demonstrate that levels of diversity in the Cross River population are not evenly distributed across subpopulations, and that one subpopulation has higher levels of variability than the others. In a genus-wide comparison, levels of genetic diversity in the Cross River gorilla were comparable to those of the similarly small populations of the mountain gorilla ( Gorilla beringei beringei) in Bwindi and the Virunga volcanoes, but showed lower levels of diversity than a sample from a large, continuous population of Gorilla gorilla gorilla at Mondika, Central African Republic. Genetic data also showed strong evidence of a population bottleneck in the Cross River gorilla, but not in the other three gorilla populations examined. I used analysis of remotely-sensed data from the Landsat satellite to assess the extent and pattern of land cover distribution across the Cross River gorilla's range. Considerable potential gorilla habitat remains within the range of the Cross River gorilla and each gorilla locality is at least tenuously connected by forest. Finally, I developed a model

  18. Tidal river dynamics

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Jay, D.A.

    2016-01-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity

  19. Reining the River

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Concerned about the effects of increasing water scarcity on economic development, China hopes a new law will save the Yellow River The first day of August marked what could be a new page in the history of China's long-suffering "mother river." That day, a regulation took effect that for the first time in histo-

  20. Africans and Black Americans in the United States: Social Distance and Differential Acculturation.

    Science.gov (United States)

    Emoungu, Paul-Albert

    1992-01-01

    Presents an exploratory examination of the causes of social distance characterizing the association between Africans and African Americans. African American's perceptions about Africa and Africans are assessed through anecdotes and impressions, and thoughts and criticisms of Africans about African Americans are considered. A social science…

  1. Afro-Americans and Early Pan-Africanism

    Science.gov (United States)

    Contee, Clarence G.

    1970-01-01

    History of the Pan-African movement, the roles of W.E.B.Du Bois and Marcus Garvey in the movement activities, and the shift to African based leadership of the movement in the 1940's are discussed. (KG)

  2. What about African Americans and High Blood Pressure?

    Science.gov (United States)

    ANSWERS by heart Lifestyle + Risk Reduction High Blood Pressure What About African Americans and High Blood Pressure? The prevalence of high blood pressure in African Americans is among the highest in ...

  3. Men of African Descent and Carcinoma of the Prostate Consortium

    Science.gov (United States)

    The Men of African Descent and Carcinoma of the Prostate Consortium collaborates on epidemiologic studies to address the high burden of prostate cancer and to understand the causes of etiology and outcomes among men of African ancestry.

  4. Sculpture of decorative candlestick based on African totem masks

    Directory of Open Access Journals (Sweden)

    Sofronova Nadezhda

    2015-04-01

    Full Text Available The paper deals with the decorative small sculptures and African totem masks, their artistic and stylistic fea-tures, analysis of the works of sculptors and steps for creating a decorative candlestick based on African totem masks.

  5. Monitoring water and habitat quality in six rivers draining the Mt. Kenya and Aberdare Catchments using Macroinvertebrates and Qualitative Habitat Scoring.

    OpenAIRE

    M'Erimba, C.; Mathooko, J.; Karanja, H; Mbaka, J.

    2014-01-01

    The study was conducted in June and September 2011 in six rivers that drain Mt. Kenya and the Aberdare catchments, i.e. Honi, Naro Moru, Liki, Sirimon, Mariara and Karigu. The main objective was to determine the ecological status of these rivers and identify macroinvertebrates with potential applicability as biomonitors. South African Scoring System version 5 (SASS-5), Multimetric Index (i.e. MI; values ranging from 0 = poor to natural = 1) and the Qualitative Habitat Assessment (QHA) methods...

  6. Attempts at a web presence inventory of African minority languages

    OpenAIRE

    Gee, Quintin

    2006-01-01

    Making an inventory of minority languages that have web sites is difficult. We show that, even if we define “minority” as African languages, then this is of little use since the appearance of web sites in any African languages are few. Many African web sites are hosted outside the continent, and few have totally indigenous languages displayed; rather, it contains a mixture of ex-colonial language illustrating documents in the African language concerned. In addition, many countries have more t...

  7. Lift every voice: voices of African-American lesbian elders.

    Science.gov (United States)

    Woody, Imani

    2015-01-01

    Old lesbians of African descent have experienced racism, heterosexism, homophobia, and ageism. This article explores the topics of aging, ageism, heterosexism, and minority stress among older African-American lesbians. The narratives and subsequent analysis offer significant contributions to the dialogue regarding Black aging lesbians in the aging and lesbian, gay, bisexual, and transgender (LGBT) communities generally and in the African-American and African-American lesbian communities specifically.

  8. On Cultural and Academic Exchanges Between China and African Countries

    OpenAIRE

    Charles Kabwete Mulinda

    2015-01-01

    Cooperation between China and African countries has often been portrayed as an economic one. Despite multiple exchanges in the area of culture and knowledge production, not much is written about chinese culture in Africa or knowledge production interaction between both China and African countries. Just to give an example, each African major town has chinese restaurants and Africans like chinese food. But food is seen as an economic asset, not a cultural one. Chinese cuisine is not enough take...

  9. Psychology and Ubuntu : therapeutic meetings in a South African context

    OpenAIRE

    2008-01-01

    The purpose of this study was to explore therapeutic meetings in a South African context. Utilising a qualitative research method, I have examined how South African therapists work in a multicultural context, asking questions regarding challenges the therapists met, what elements existed in the African context that influence healing. I proposed that the concept of Ubuntu could provide an African perspective to balance the western notion of psychotherapy. I also explored what adjustments thera...

  10. Population Genomics of sub-saharan Drosophila melanogaster: African diversity and non-African admixture.

    Directory of Open Access Journals (Sweden)

    John E Pool

    Full Text Available Drosophila melanogaster has played a pivotal role in the development of modern population genetics. However, many basic questions regarding the demographic and adaptive history of this species remain unresolved. We report the genome sequencing of 139 wild-derived strains of D. melanogaster, representing 22 population samples from the sub-Saharan ancestral range of this species, along with one European population. Most genomes were sequenced above 25X depth from haploid embryos. Results indicated a pervasive influence of non-African admixture in many African populations, motivating the development and application of a novel admixture detection method. Admixture proportions varied among populations, with greater admixture in urban locations. Admixture levels also varied across the genome, with localized peaks and valleys suggestive of a non-neutral introgression process. Genomes from the same location differed starkly in ancestry, suggesting that isolation mechanisms may exist within African populations. After removing putatively admixed genomic segments, the greatest genetic diversity was observed in southern Africa (e.g. Zambia, while diversity in other populations was largely consistent with a geographic expansion from this potentially ancestral region. The European population showed different levels of diversity reduction on each chromosome arm, and some African populations displayed chromosome arm-specific diversity reductions. Inversions in the European sample were associated with strong elevations in diversity across chromosome arms. Genomic scans were conducted to identify loci that may represent targets of positive selection within an African population, between African populations, and between European and African populations. A disproportionate number of candidate selective sweep regions were located near genes with varied roles in gene regulation. Outliers for Europe-Africa F(ST were found to be enriched in genomic regions of locally

  11. South African Artillery in the Eighties

    Directory of Open Access Journals (Sweden)

    A. C. Lillie

    2012-02-01

    Full Text Available Emerging from the Second World War armed with the then completely adequate 25 pounder and BL 5.5" guns, the South African Field Artillery continued to use the same guns operationally over thirty years later.When the armed forces of South Africa were thrown into a conventional conflict during the Angolan Civil War in 1975, the gunners found their equipment to be woefully inadequate. Soviet made artillery systems in the hands of the Russian-backed forces possessed ranges far in excess of the Second World War vintage South African systems and brought home in a very real way the need for drastic modernisation of the artillery branch of the South African Army.

  12. Asynchronous changes in vegetation, runoff and erosion in the nile river watershed during the holocene.

    Directory of Open Access Journals (Sweden)

    Cécile L Blanchet

    Full Text Available The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations.

  13. Resource Use within the Crab-Eating Guild in Upper Kairezi River, Zimbabwe: Proposed Project

    OpenAIRE

    Butler J.

    1993-01-01

    The management problem that this study will address is the apparent decline in the biological productivity of the Upper Kairezi River for rainbow trout. Fishery managers believe that the cause could be predation on trout by resident Cape Clawless Otters and the African mottled eel. The area is part of a CAMPFIRE (Communal Areas Management Programme For Indigenous Resource) programme and agriculture is excluded from the environs. However, owing to the falls in catches, fishermen have been disc...

  14. 33 CFR 117.734 - Navesink River (Swimming River).

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Navesink River (Swimming River... BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.734 Navesink River (Swimming River). The Oceanic Bridge, mile 4.5, shall open on signal; except that, from December 1...

  15. What is Ubuntu? Different Interpretations among South Africans of African Descent

    DEFF Research Database (Denmark)

    Gade, Christian B.N.

    2012-01-01

    In this article, I describe and systematize the different answers to the question 'What is Ubuntu?' that I have been able to identify among South Africans of African descent (SAADs). I show that it is possible to distinguish between two clusters of answers. The answers of the first cluster all...... define ubuntu as a moral quality of a person, while the answers of the second cluster all define ubuntu as a phenomenon (for instance a philosophy, an ethic, African humanism, or, a wordview) according to which persons are interconnected. The concept of a person is of central importance to all the...

  16. Assessing the contributions of East African and West Pacific warming to the 2014 boreal spring East African drought

    Science.gov (United States)

    Funk, Christopher C.; Shukla, Shraddhanand; Hoell, Andrew; Livneh, Ben

    2015-01-01

    Anthropogenic warming contributed to the 2014 East African drought by increasing East African and west Pacific temperatures, and increasing the gradient between standardized western and central Pacific SST causing reduced rainfall, evapotranspiration, and soil moisture.

  17. Student-Centered Designs of Pan-African Literature Courses

    Science.gov (United States)

    M'Baye, Babacar

    2010-01-01

    A student-centered teaching methodology is an essential ingredient of a successful Pan-African literary course. In this article, the author defines Pan-Africanism and how to go about designing a Pan-African literature course. The author combines reading assignments with journals, film presentations, and lectures in a productive learning…

  18. Some Growth Points in African Child Development Research

    Science.gov (United States)

    Serpell, Robert; Marfo, Kofi

    2014-01-01

    We reflect on ways in which research presented in earlier chapters responds to challenges of generating an African child development field and identify additional issues calling for the field's attention. The chapters collectively display a variety of African contexts and reflexive evidence of the authors' African cultural roots.…

  19. African American Educational Leadership in the School Superintendency

    Science.gov (United States)

    Smith, Eva C.

    2013-01-01

    African American educational leadership has long been part of American education and African American activism to resist oppression. However, the field of educational leadership has rarely included the contributions of African American leaders, particularly women leaders, into mainstream leadership theory and practices. This omission is difficult…

  20. North African populations carry the signature of admixture with Neandertals

    DEFF Research Database (Denmark)

    Sánchez-Quinto, Federico; Botigué, Laura R; Civit, Sergi;

    2012-01-01

    One of the main findings derived from the analysis of the Neandertal genome was the evidence for admixture between Neandertals and non-African modern humans. An alternative scenario is that the ancestral population of non-Africans was closer to Neandertals than to Africans because of ancient popu...

  1. Perceived Attractiveness, Facial Features, and African Self-Consciousness.

    Science.gov (United States)

    Chambers, John W., Jr.; And Others

    1994-01-01

    Investigated relationships between perceived attractiveness, facial features, and African self-consciousness (ASC) among 149 African American college students. As predicted, high ASC subjects used more positive adjectives in descriptions of strong African facial features than did medium or low ASC subjects. Results are discussed in the context of…

  2. Registers in the Academic Writing of African American College Students

    Science.gov (United States)

    Syrquin, Anna F.

    2006-01-01

    The study examines the development of the registers of academic writing by African American college-level students through style and grammar: indirection inherent in the oral culture of the African American community and the paratactic functions of "because." Discourse analysis of 74 samples of academic writing by 20 African American undergraduate…

  3. Exposure of African-American Youth to Alcohol Advertising.

    Science.gov (United States)

    2003

    The marketing of alcohol products in African-American communities has, on occasion, stirred national controversy and met with fierce resistance from African Americans and others. Despite occasional media and community spotlights on the marketing of alcohol products in the African-American community, there has been no systematic review of the…

  4. Contrastive Studies - African Languages and English. Specialised Bibliography C9.

    Science.gov (United States)

    British Council, London (England). English-Teaching Information Centre.

    This selective bibliography lists 8 books and 19 journal articles dealing with contrastive studies of African languages and English. The entries range in date from 1953 to 1972 with the majority published since 1965. The books cited are African and British publications and the articles appeared in well-known African, European or American…

  5. Oral Cancer in African Americans: Addressing Health Disparities

    Science.gov (United States)

    Dodd, Virginia J.; Watson, Jennifer M.; Choi, Youjin; Tomar, Scott L.; Logan, Henrietta L.

    2008-01-01

    Objectives: To explore factors underlying African Americans' perceptions of oral cancer and the oral cancer exam. Study findings were used to guide development of oral cancer messages designed to increase oral cancer exams among African Americans. Methods: Focus groups were conducted to understand African Americans' attitudes and expectations…

  6. Engaging Youth through African-Derived Dance and Culture

    Science.gov (United States)

    Franklin, Kikora

    2013-01-01

    This article provides a brief history of African and African-derived dance and culture and highlights the physical health, dance education, historical, and cultural benefits of a school-based program that incorporates African dance as its core component. The article also includes the phases of the programming and brings attention to potential…

  7. African American Single Mothers Raising Sons: Implications for Family Therapy

    Science.gov (United States)

    Gantt, Ann L.; Greif, Geoffrey L.

    2009-01-01

    Being raised by a single mother is one factor that has been suggested as contributing to the plight of African American males. Yet few studies have focused specifically on African American single mothers' experiences with raising sons. This qualitative study explored the following questions: (1) What are the experiences of African American single…

  8. Mammary gland tumors in captive African hedgehogs.

    Science.gov (United States)

    Raymond, J T; Gerner, M

    2000-04-01

    From December 1995 to July 1999, eight mammary gland tumors were diagnosed in eight adult captive female African hedgehogs (Atelerix albiventris). The tumors presented as single or multiple subcutaneous masses along the cranial or caudal abdomen that varied in size for each hedgehog. Histologically, seven of eight (88%) mammary gland tumors were malignant. Tumors were classified as solid (4 cases), tubular (2 cases), and papillary (2 cases). Seven tumors had infiltrated into the surrounding stroma and three tumors had histologic evidence of neoplastic vascular invasion. Three hedgehogs had concurrent neoplasms. These are believed to be the first reported cases of mammary gland tumors in African hedgehogs. PMID:10813628

  9. 'Great power' intervention in African armed conflicts

    DEFF Research Database (Denmark)

    Olsen, Gorm Rye

    2015-01-01

    to contribute to understanding the changing geopolitical environment and the current conditions for conflict management in Africa. The focus is not on trade and aid. The paper launches the hypothesis that the explanations why the US, China and the EU have intervened are basically identical. In spite......This paper asks why the United States (US), China and the European Union (EU) have intervened in a number of armed conflicts in Africa in the twenty-first century. Scrutiny and comparison of the motivations and interests of the three non-African actors in intervening in African crises are assumed...

  10. Cryptosporidium and cryptosporidiosis: the African perspective.

    Science.gov (United States)

    Aldeyarbi, Hebatalla M; Abu El-Ezz, Nadia M T; Karanis, Panagiotis

    2016-07-01

    The present overview discusses the findings of cryptosporidiosis research conducted in Africa and highlights the currently available information on Cryptosporidium epidemiology, genetic diversity, and distribution on the African continent, particularly among vulnerable populations, including children. It also emphasizes the burden of cryptosporidiosis, which is underestimated due to the presence of many silent asymptomatic carriers.Cryptosporidiosis is recognized as one of the leading causes of childhood diarrhea in African countries. It has dramatic adverse effects on child growth and development and causes increased mortality on a continent where HIV, poverty, and lack of sanitation and infrastructure increase the risk of cryptosporidial waterborne infection. PMID:27126869

  11. The landscape of recombination in African Americans

    OpenAIRE

    Anjali G Hinch; Tandon, Arti; Patterson, Nick; Song, Yunli; Rohland, Nadin; Palmer, Cameron D; Chen, Gary K.; Wang, Kai; Buxbaum, Sarah G.; Akylbekova, Meggie; Aldrich, Melinda C.; Ambrosone, Christine B.; Amos, Christopher; Bandera, Elisa V.; Berndt, Sonja I.

    2011-01-01

    Recombination, together with mutation, is the ultimate source of genetic variation in populations. We leverage the recent mixture of people of African and European ancestry in the Americas to build a genetic map measuring the probability of crossing-over at each position in the genome, based on about 2.1 million crossovers in 30,000 unrelated African Americans. At intervals of more than three megabases it is nearly identical to a map built in Europeans. At finer scales it differs significantl...

  12. Uranium in river water

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, M.R. (Univ. of Bristol (United Kingdom)); Edmond, J.M. (Massachusetts Inst. of Technology, Cambridge, MA (United States))

    1993-10-01

    The concentration of dissolved uranium has been determined in over 250 river waters from the Orinoco, Amazon, and Ganges basins. Uranium concentrations are largely determined by dissolution of limestones, although weathering of black shales represents an important additional source in some basins. In shield terrains the level of dissolved U is transport limited. Data from the Amazon indicate that floodplains do not represent a significant source of U in river waters. In addition, the authors have determined dissolved U levels in forty rivers from around the world and coupled these data with previous measurements to obtain an estimate for the global flux of dissolved U to the oceans. The average concentration of U in river waters is 1.3 nmol/kg, but this value is biased by very high levels observed in the Ganges-Brahmaputra and Yellow rivers. When these river systems are excluded from the budget, the global average falls to 0.78 nmol/kg. The global riverine U flux lies in the range of 3-6 [times] 10[sup 7] mol/yr. The major uncertainty that restricts the accuracy of this estimate (and that of all other dissolved riverine fluxes) is the difficulty in obtaining representative samples from rivers which show large seasonal and annual variations in runoff and dissolved load.

  13. Modeling river delta formation

    CERN Document Server

    Seybold, Hansjörg; Herrmann, Hans J

    2007-01-01

    A new model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/ erosion law. Different delta types are reproduced using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore our model is capable to simulate the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi river.

  14. Modeling river delta formation.

    Science.gov (United States)

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  15. Predicting Non-African American Lesbian and Heterosexual Preadoptive Couples' Openness to Adopting an African American Child

    Science.gov (United States)

    Goldberg, Abbie E.; Smith, JuliAnna Z.

    2009-01-01

    Despite increases in transracial adoption, African American children remain the least likely to be adopted. No research has examined the factors that predict prospective adopters' willingness to adopt an African American child. This study used multilevel modeling to examine predictors of willingness to adopt an African American child in a sample…

  16. The African Renaissance and its relation to the geosciences: a South African perspective

    Science.gov (United States)

    Mtimkulu, M. N.; Motloung, M.; Graham, I. T.; Eriksson, P. G.; Bumby, A. J.

    2001-08-01

    Implicit in the African Renaissance is the synergy between government, the private sector, the educated minority and the disadvantaged majority. For this concept to work, belief and commitment must arise first from the African individual, whatever his or her potential contribution may be. The geosciences in South Africa provide a currently vibrant example of such cooperation, which has the potential to contribute significantly to the upliftment of the country and its neighbouring states. Based largely on personal interviews with various role players, from the Presidency of South Africa, through ministerial levels, the corporate sector and down to the individual, we present a spectrum of viewpoints and initiatives which are starting to result in practical implementation of the African revival. An end to conflict and xenophobia, the entrenchment of democratic government and corporate expression of the entrepreneurial spirit are essential to provide the framework within which the individual African can become a "Renaissance Man or Woman".

  17. Resource pulses in desert river habitats: productivity-biodiversity hotspots, or mirages?

    Directory of Open Access Journals (Sweden)

    Carissa L Free

    Full Text Available Resource pulses in the world's hot deserts are driven largely by rainfall and are highly variable in both time and space. However, run-on areas and drainage lines in arid regions receive more water more often than adjacent habitats, and frequently sustain relatively high levels of primary productivity. These landscape features therefore may support higher biotic diversity than other habitats, and potentially act as refuges for desert vertebrates and other biota during droughts. We used the ephemeral Field River in the Simpson Desert, central Australia, as a case study to quantify how resources and habitat characteristics vary spatially and temporally along the riparian corridor. Levels of moisture and nutrients were greater in the clay-dominated soils of the riverine corridor than in the surrounding sand dunes, as were cover values of trees, annual grasses, other annual plants and litter; these resources and habitat features were also greater near the main catchment area than in the distal reaches where the river channel runs out into extensive dune fields. These observations confirm that the riverine corridor is more productive than the surrounding desert, and support the idea that it may act as a refuge or as a channel for the ingress of peri-desert species. However, the work also demonstrates that species diversity of invertebrates and plants is not higher within the river corridor; rather, it is driven by rainfall and the accompanying increase in annual plants following a rain event. Further research is required to identify the biota that depend upon these resource pulses.

  18. River health assessment using macroinvertebrates and water quality parameters: A case of the Orange River in Namibia

    Science.gov (United States)

    Munyika, Shishani; Kongo, Victor; Kimwaga, Richard

    Land use activities that have an effect on water quality and river health are believed to have increased along the Orange River in Namibia. These are mainly agricultural activities, notably irrigation, with more than 2000 ha currently under irrigation and approximately 2000 ha planned for future expansion. Other anthropogenic activities include urban development and weir construction along the Orange River. Population increase along the river has resulted in proliferation of unplanned settlements with no proper sanitation facilities. This study was aimed at assessing the current water quality and overall health status of the Orange River in Namibia. The South African Scoring System 5(SASS5) was applied in eight sites where samples for macroinvertebrates, physical and chemical water quality parameters such as nutrients in the water, pH, turbidity and presence of bacteria were obtained. Satellite images i.e. Landsat images were also used to assess the land-uses over time in the study area with the view of linking such changes to variance in water quality over time. The SASS5 results indicated a fair water quality and river health condition in category C, indicating that the river is moderately modified. Water quality parameters at all sites varied moderately and were within acceptable limits, except for turbidity and chlorophyll a. There was a significant difference in the mean concentrations of nine water quality parameters among sampling periods, whereby F-value > F-critical at α = 0.05 among sites, F-value < F-critical at α = 0.05, except for turbidity and chlorophyll a. The Landsat images also showed minimal changes in land-use activities between 2002 and 2012, with a net increase of 38 ha in irrigated area. According to National Water Policy White Paper of Namibia of 2000, it was found that policies and legislation address water resources management from a broader spectrum and not specific to river health. Thus, it was concluded that the river health of Orange

  19. Co-evolution between the South African venture capital industry and the South [African] government

    OpenAIRE

    Aluko, Olumide Mayowa

    2011-01-01

    This thesis contributes to the current discourse around co-evolution, this study investigates co-evolution between the South African venture capital industry and the South African government. Using a qualitative method which involved gathering data from archival sources and contemporary interviews, this study extends the growing literature on the co-evolution of organizations and their institutional environment in three ways. First, the study shows that the co-evolution that occurs between or...

  20. Human foot bones from Klasies River main site, South Africa.

    Science.gov (United States)

    Rightmire, G Philip; Deacon, H J; Schwartz, Jeffrey H; Tattersall, Ian

    2006-01-01

    The caves at Klasies River contain abundant archaeological evidence relating to human evolution in the late Pleistocene of southern Africa. Along with Middle Stone Age artifacts, animal bones, and other food waste, there are hominin cranial fragments, mandibles with teeth, and a few postcranial remains. Three foot bones can now be added to this inventory. An adult first metatarsal is similar in size and discrete anatomical features to those from Holocene burials in the Cape Province. A complete and well-preserved second metatarsal is especially long and heavy at midshaft in comparison to all Holocene and more recent South African homologues. A large fifth metatarsal is highly distinctive in its morphology. In overall size, these pedal elements resemble specimens from late Pleistocene sites in western Asia, but there are some differences in proportions. The fossils support earlier suggestions concerning a relatively high level of sexual dimorphism in the African Middle Stone Age population. Squatting facets on the two lateral metatarsals appear to indicate a high frequency of kneeling among members of this group. The new postcranial material also underlines the fact that the morphology of particular skeletal elements of some of the 100,000-year-old Klasies River individuals falls outside the range of modern variation.

  1. Dulbi River goose survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A survey of white-fronted goose (Anser albifrons) and Canada goose (Branta canadensis) broods was conducted on 58 3/8 miles of the Dulbi River in Alaska. Four...

  2. Russian River Analysis

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is an analysis and summary of progress toward achieving the interim management objectives for the Russian River during the 1979 season. Additionally,...

  3. Wild and Scenic Rivers

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This map layer portrays the linear federally-owned land features (i.e., national parkways, wild and scenic rivers, etc.) of the United States, Puerto Rico, and the...

  4. Management recommendations: Bear River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Bear River Migratory Bird Refuge, by a land use specialist. Recommendations, time frame and additional...

  5. The Carmans River Story

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In this study, undertaken as an independent project at Bellport High School, the authors have attempted to provide a historical description of the Carmans River...

  6. Down to the River

    DEFF Research Database (Denmark)

    Wessels, Josepha Ivanka

    2015-01-01

    Currently there is no coherent or sustainable water cooperation among the five states—Israel, Jordan, Lebanon, Palestinian territories and Syria—that share the Jordan River. Why do people not cooperate on sustainable river basin management, even if it seems the most rational course from the persp......Currently there is no coherent or sustainable water cooperation among the five states—Israel, Jordan, Lebanon, Palestinian territories and Syria—that share the Jordan River. Why do people not cooperate on sustainable river basin management, even if it seems the most rational course from...... the perspective of economic benefits? I hypothesize that the political uses of citizenship, identity and security at the local level hamper cooperation at the basin level and ignore cognitive dimensions of violence and conflict. In this article, I have chosen the Israeli-occupied Golan Heights as a case study...

  7. Mackenzie River Delta, Canada

    Science.gov (United States)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789. The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  8. Caring School Leadership: A South African Study

    Science.gov (United States)

    van der Vyver, Cornelius P.; van der Westhuizen, Philip C.; Meyer, L. W.

    2014-01-01

    The research pivoted on the question whether South African school principals fulfilled their caring role towards teachers. The aims of the study were threefold. First, to determine how principals rated their care-giving, secondly to determine whether significant discrepancies existed between principals' rating of their care-giving and…

  9. Researching Africa : Explorations of everyday African encounters

    NARCIS (Netherlands)

    Bruijn, de M.E.; Merolla, D.

    2010-01-01

    The studies in this volume are the result of research carried out by students of the Research Masters in African Studies (RMAS) at Leiden University who graduated in 2008. The studies cover such areas as conflict, democracy, migration, urban and rural studies, language, communication and youth. An i

  10. Improving the productivity of indigenous African livestock

    International Nuclear Information System (INIS)

    This document summarizes the results of two Co-ordinated Research Programs to improve the productivity of indigenous African livestock. After an introduction and a summary the reports of the participating countries are presented. The individual contributions have been indexed separately. Refs, figs and tabs

  11. An Exploration of African Students in Malaysia

    Science.gov (United States)

    Lian, Irene Tan Ai

    2011-01-01

    The exploratory study is an attempt to understand the reasons that prompted African students to study in Malaysia, the challenges encountered and the coping strategies used. The research on such topics among international students is well documented, but studies on international students in Malaysia are scarce. The sample included 155 African…

  12. Violent Behaviors among African-American Adolescents.

    Science.gov (United States)

    Garrett, Darhyl

    1995-01-01

    Explores the development of behaviors by using Erik Erikson's psychosocial developmental theory, with emphasis on adolescents. Examines factors, such as identity versus identity diffusion, that may be contributing to increasing acts of violence by African American adolescents. Other factors are examined that may contribute to increased violence.…

  13. Educational Resilience in African American Adolescents

    Science.gov (United States)

    Cunningham, Michael; Swanson, Dena Phillips

    2010-01-01

    The purpose of this article was to examine factors within the school context that facilitates educational resilience among African American high school students. The authors expected academic self-esteem to be positively associated with future expectations (academic and general). They expected perceptions of school-based social support to have…

  14. Dictionaries of African Sign Languages: An Overview

    Science.gov (United States)

    Schmaling, Constanze H.

    2012-01-01

    This article gives an overview of dictionaries of African sign languages that have been published to date most of which have not been widely distributed. After an introduction into the field of sign language lexicography and a discussion of some of the obstacles that authors of sign language dictionaries face in general, I will show problems…

  15. Legacy of a Pioneer African American Educator

    Science.gov (United States)

    Cazers, Gunars; Curtner-Smith, Matthew

    2013-01-01

    Purpose: The purpose was to reconstruct the historical and legendary contribution of one exemplary African American physical education teacher educator who lived and worked in the Deep South prior to and immediately following the 1954 Brown v. Board of Education court case. The following questions guided data collection and analysis: To what…

  16. Seismic imaging of Southern African cratons

    DEFF Research Database (Denmark)

    Soliman, Mohammad Youssof Ahmad

    the southern African regions. Some of the main research problems that have been dealt with during this research are about (1) the heterogeneity scale of crustal structure and composition, (2) the depth extent of the cratonic keels and their layering, and (3) the strength of crustal anisotropy. The...

  17. Tuberculosis Detection by Giant African Pouched Rats

    Science.gov (United States)

    Poling, Alan; Weetjens, Bart; Cox, Christophe; Beyene, Negussie; Durgin, Amy; Mahoney, Amanda

    2011-01-01

    In recent years, operant discrimination training procedures have been used to teach giant African pouched rats to detect tuberculosis (TB) in human sputum samples. This article summarizes how the rats are trained and used operationally, as well as their performance in studies published to date. Available data suggest that pouched rats, which can…

  18. Cataloging the Pan-African Experience

    Science.gov (United States)

    Hayes, Dianne

    2012-01-01

    Of all the honors and accolades bibliophile and noted authority on the Underground Railroad Charles Blockson has received, being bequeathed recently with some of Harriet Tubman's personal items by her great-niece is one of the most significant experiences of his life. A longtime collector of books and rare items by and about African-Americans,…

  19. The landscape of recombination in African Americans.

    Science.gov (United States)

    Hinch, Anjali G; Tandon, Arti; Patterson, Nick; Song, Yunli; Rohland, Nadin; Palmer, Cameron D; Chen, Gary K; Wang, Kai; Buxbaum, Sarah G; Akylbekova, Ermeg L; Aldrich, Melinda C; Ambrosone, Christine B; Amos, Christopher; Bandera, Elisa V; Berndt, Sonja I; Bernstein, Leslie; Blot, William J; Bock, Cathryn H; Boerwinkle, Eric; Cai, Qiuyin; Caporaso, Neil; Casey, Graham; Cupples, L Adrienne; Deming, Sandra L; Diver, W Ryan; Divers, Jasmin; Fornage, Myriam; Gillanders, Elizabeth M; Glessner, Joseph; Harris, Curtis C; Hu, Jennifer J; Ingles, Sue A; Isaacs, William; John, Esther M; Kao, W H Linda; Keating, Brendan; Kittles, Rick A; Kolonel, Laurence N; Larkin, Emma; Le Marchand, Loic; McNeill, Lorna H; Millikan, Robert C; Murphy, Adam; Musani, Solomon; Neslund-Dudas, Christine; Nyante, Sarah; Papanicolaou, George J; Press, Michael F; Psaty, Bruce M; Reiner, Alex P; Rich, Stephen S; Rodriguez-Gil, Jorge L; Rotter, Jerome I; Rybicki, Benjamin A; Schwartz, Ann G; Signorello, Lisa B; Spitz, Margaret; Strom, Sara S; Thun, Michael J; Tucker, Margaret A; Wang, Zhaoming; Wiencke, John K; Witte, John S; Wrensch, Margaret; Wu, Xifeng; Yamamura, Yuko; Zanetti, Krista A; Zheng, Wei; Ziegler, Regina G; Zhu, Xiaofeng; Redline, Susan; Hirschhorn, Joel N; Henderson, Brian E; Taylor, Herman A; Price, Alkes L; Hakonarson, Hakon; Chanock, Stephen J; Haiman, Christopher A; Wilson, James G; Reich, David; Myers, Simon R

    2011-07-20

    Recombination, together with mutation, gives rise to genetic variation in populations. Here we leverage the recent mixture of people of African and European ancestry in the Americas to build a genetic map measuring the probability of crossing over at each position in the genome, based on about 2.1 million crossovers in 30,000 unrelated African Americans. At intervals of more than three megabases it is nearly identical to a map built in Europeans. At finer scales it differs significantly, and we identify about 2,500 recombination hotspots that are active in people of West African ancestry but nearly inactive in Europeans. The probability of a crossover at these hotspots is almost fully controlled by the alleles an individual carries at PRDM9 (P value < 10(-245)). We identify a 17-base-pair DNA sequence motif that is enriched in these hotspots, and is an excellent match to the predicted binding target of PRDM9 alleles common in West Africans and rare in Europeans. Sites of this motif are predicted to be risk loci for disease-causing genomic rearrangements in individuals carrying these alleles. More generally, this map provides a resource for research in human genetic variation and evolution.

  20. African American Students' Attitudes toward Entrepreneurship Education.

    Science.gov (United States)

    Ede, Fred O.; Panigrahi, Bhagaban; Calcich, Stephen E.

    1998-01-01

    A survey of 171 African-American students found that 72% came from nonentrepreneurial family backgrounds; only 24.5% intended to start their own businesses, there were no gender differences in entrepreneurship attitudes, and seniors and those from entrepreneurial backgrounds were more favorable toward entrepreneurship. (SK)

  1. AFRICAN ADULT EDUCATION--A BIBLIOGRAPHY.

    Science.gov (United States)

    BOWN, LALAGE

    THIS BIBLIOGRAPHY, A TENTATIVE LISTING OF MATERIALS ON AFRICAN ADULT EDUCATION PREPARED WITHOUT FULL BIBLIOGRAPHIC DETAIL IS LIMITED TO SOURCES IN ENGLISH AND FRENCH. THE ENGLISH SOURCES DO NOT INCLUDE MANY FROM AMERICA. IT IS AN EXTENSION AND REVISION OF THE PRELIMINARY BIBLIOGRAPHY DRAWN UP AT THE UNIVERSITY OF IBADAN IN 1965. THE FIRST SECTION…

  2. Myths in African Concept of Reality

    Science.gov (United States)

    Jaja, Jones M.

    2014-01-01

    Myths are accounts of the origin of societies and institutions not subject to rationalization but often used by historians and philosophers in their quest to study African history; for it is only thus that we can comprehend the various aspects of the continent's history and culture. This paper examines the critical understanding of African…

  3. Assessing sanitary mixtures in East African cities

    NARCIS (Netherlands)

    Letema, S.C.

    2012-01-01

    The urbanisation of poverty and informality in East African cities poses a threat to environmental
    health, perpetuates social exclusion and inequalities, and creates service gaps (UN-Habitat, 2008).
    This makes conventional sanitation provision untenable citywide, giving rise to the emerg

  4. African American Homeschooling Practices: Empirical Evidence

    Science.gov (United States)

    Mazama, Ama

    2016-01-01

    Despite a significant increase in scholarly interest for homeschooling, some of its most critical aspects, such as instructional daily practices, remain grossly understudied. This essay thus seeks to fill that void by presenting empirical evidence regarding the homeschooling practices of a specific group, African Americans. Most specifically, the…

  5. African American College Women's Suicide Buffers.

    Science.gov (United States)

    Marion, Michelle S.; Range, Lillian M.

    2003-01-01

    To examine the relationships buffers may have with suicide ideation, 300 African American female college students completed measures of suicide ideation and buffers. Three variables accounted for a significant and unique portion of the variance in suicide ideation: family support, a view that suicide is unacceptable, and a collaborative religious…

  6. Colorectal Cancer in African Americans: An Update.

    Science.gov (United States)

    Williams, Renee; White, Pascale; Nieto, Jose; Vieira, Dorice; Francois, Fritz; Hamilton, Frank

    2016-01-01

    This review is an update to the American College of Gastroenterology (ACG) Committee on Minority Affairs and Cultural Diversity's paper on colorectal cancer (CRC) in African Americans published in 2005. Over the past 10 years, the incidence and mortality rates of CRC in the United States has steadily declined. However, reductions have been strikingly much slower among African Americans who continue to have the highest rate of mortality and lowest survival when compared with all other racial groups. The reasons for the health disparities are multifactorial and encompass physician and patient barriers. Patient factors that contribute to disparities include poor knowledge of benefits of CRC screening, limited access to health care, insurance status along with fear and anxiety. Physician factors include lack of knowledge of screening guidelines along with disparate recommendations for screening. Earlier screening has been recommended as an effective strategy to decrease observed disparities; currently the ACG and American Society of Gastrointestinal Endoscopists recommend CRC screening in African Americans to begin at age 45. Despite the decline in CRC deaths in all racial and ethnic groups, there still exists a significant burden of CRC in African Americans, thus other strategies including educational outreach for health care providers and patients and the utilization of patient navigation systems emphasizing the importance of screening are necessary. These strategies have been piloted in both local communities and Statewide resulting in notable significant decreases in observed disparities. PMID:27467183

  7. Changing governance structures in South African agribusiness

    NARCIS (Netherlands)

    Doyer, O.T.; Haese, D' M.F.C.; Rooyen, van C.J.; Kirsten, J.F.; Haese, D' L.

    2008-01-01

    This article examines the changing governance structures in the South African agri-food sector. Changing legislative and market conditions forced agribusiness managers to rethink their governance structures to ensure the competitiveness of the agri-food sector. They had to adapt to the new structure

  8. Cultural Considerations When Caring for African Americans

    Science.gov (United States)

    The EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans is a free comprehensive multimedia curricula for health professionals caring for persons with cancer and their families.

  9. The South African species of Teucrium (Lamiaceae

    Directory of Open Access Journals (Sweden)

    L. E. Codd

    1977-12-01

    Full Text Available While writing up the three South African species of  Teucrium for the Flora o f Southern Africa it became necessary to replace two well-known names as follows:  T. trifidum Retz. (1779 ( = T.  capense Thunb., 1800 and  T. kraussii Codd  {=T. riparium Hochst., 1845, non Rafin., 1838.

  10. Beijing Summit Promotes Sino-African Relations

    Institute of Scientific and Technical Information of China (English)

    Xu Weizhong

    2007-01-01

    @@ Since the establishment of the Forum on China-Africa Cooperation in 2000, China-Africa relations have entered a new period of cooperation. 2006 not only consolidated friendship between China and Africa, but also laid a sound foundation for more prosperous Sino-African relations.

  11. African Literature and the American University.

    Science.gov (United States)

    Priebe, Richard

    While African literature appears to be firmly established in American colleges and universities, its expansion, and in some cases its continuance, is threatened by two factors: racialism and departmental conservatism. As demands for courses in black literature can be met by an increased supply of scholars in Afro-American literature, fewer schools…

  12. Contemporary Sexism in the South African Navy

    Science.gov (United States)

    Van Wijk, Charles H.

    2011-01-01

    The military traditionally embraces highly sexist attitudes. Over the past decade, the South African Navy (SAN) has been exposed to an increasingly progressive political environment. This study investigated contemporary expressions of sexism in the SAN. A representative sample of 476 sailors completed the Ambivalent Sexism Inventory, Modern Sexism…

  13. African American Vernacular English and Rap Music

    Institute of Scientific and Technical Information of China (English)

    胡波

    2015-01-01

    African American Vernacular English (AAVE) is the language spoken by almost 20 milion speakers al over the world. It is also used frequently in rap lyrics. Studying the origin and grammar rules of AAVE is a very important topic in today's English Language and English Teaching Studies.

  14. Some remarks on the African wild ass

    NARCIS (Netherlands)

    Bemmel, van A.C.V.

    1972-01-01

    INTRODUCTION Without any doubt the African Wild Ass should be considered a species threatened with extinction. Therefore, it seems worth-while to collect as many data on this species as possible and to do this quickly. Data and material, however, are scarce. Many sportsmen and zoologists observed th

  15. Wages and Labor Management in African Manufacturing

    Science.gov (United States)

    Fafchamps, Marcel; Soderbom, Mans

    2006-01-01

    Using matched employer-employee data from ten African countries, we examine the relationship between wages, worker supervision, and labor productivity in manufacturing. Wages increase with firm size for both production workers and supervisors. We develop a two-tier model of supervision that can account for this stylized fact and we fit the…

  16. The rivers of civilization

    Science.gov (United States)

    Macklin, Mark G.; Lewin, John

    2015-04-01

    The hydromorphic regimes that underpinned Old World river-based civilizations are reviewed in light of recent research. Notable Holocene climatic changes varied from region to region, whilst the dynamics of floodplain environments were equally diverse, with river channel changes significantly affecting human settlement. There were longer-term trends in Holocene hydroclimate and multi-centennial length 'flood-rich' and 'flood-poor' episodes. These impacted on five identified flooding and settlement scenarios: (i) alluvial fans and aprons; (ii) laterally mobile rivers; (iii) rivers with well-developed levees and flood basins; (iv) river systems characterised by avulsions and floodouts; and (v) large river-fed wetlands. This gave a range of changes that were either more or less regular or incremental from year-to-year (and thus potentially manageable) or catastrophic. The latter might be sudden during a flood event or a few seasons (acute), or over longer periods extending over many decades or even centuries (chronic). The geomorphic and environmental impacts of these events on riparian societies were very often irreversible. Contrasts are made between allogenic and autogenic mechanism for imposing environmental stress on riverine communities and a distinction is made between channel avulsion and contraction responses. Floods, droughts and river channel changes can precondition as well as trigger environmental crises and societal collapse. The Nile system currently offers the best set of independently dated Holocene fluvial and archaeological records, and the contrasted effects of changing hydromorphological regimes on floodwater farming are examined. The persistence of civilizations depended essentially on the societies that maintained them, but they were also understandably resilient in some environments (Pharaonic Egypt in the Egyptian Nile), appear to have had more limited windows of opportunity in others (the Kerma Kingdom in the Nubian Nile), or required

  17. Cenozoic Landscape evolution of the South-African Plateau around the Orange Valley: tectonic and climate coupling

    Science.gov (United States)

    Dauteuil, Olivier; Bessin, Paul; Guillocheau, François

    2014-05-01

    The plateaus form the key geomorphic element of the African relief with the occurrence of the South African (or Kalahari) Plateau, extending from South Africa to southern Congo (Fig. 1). The origin and evolution of this large relief with a mean elevation ranging 1 to 2 kilometres were largely debated. This work discussed the landscape growth of the South African plateau on both sides of the Orange valley in term of planation process, incision, deformation and climate change. This work is mainly based on a geomorphic analysis done from DEM and field data. First, we proposed a new typology of planation surfaces based on their genetic process (weathering versus erosion), and not depending the elevation, as previously. Five types of planation surfaces were retained: etchplain, peneplain, pediplain, top-weathering surface and wav-cut platform. Using this approach to determine the evolution of Orange valley, we recognised three planation surfaces of which origin is not controlled by the lithology: a top weathering surface recorded the end of Eocene weathering period, a first etchplain-to-pediplain formed during the Oligocene and finally a pediplain initiated after a deformation event during the Miocene. This event reorganised completely the drainage network and the catchment of the Orange River that became similar to the current one. It corresponds to a regional tilting of the southern part of the plateau with a elevation of 200 m at least. Afterwards, global eustatic variations driven the landscape evolution because the Orange River gained the current stream connected to the sea level. Thus the landscape growth of the South African plateau results in a change in planation processes driven by a first climate change occurring during a slow uplift, then a regional tilting and at least by eustasy. Thus, an accurate and detail geomorphic analysis allows discriminating the tectonic to climatic processes causing the current landscape.

  18. Logic in African Philosophy: Examples from two Niger Delta Societies

    Directory of Open Access Journals (Sweden)

    Jones M. Jaja

    2012-04-01

    Full Text Available There have been questions as to whether African Philosophy exists or not. European scholars and some African scholars are at the opposite end of this scholarly debate. The result is the production of various works by Odera Oruka, Omoregbe, Bordunrin, Wright, Maurier and others espousing their views for or against the existence of African Philosophy. This paper attempts to show the existence of a unique Philosophy that deserves to be recognized and rightly known as African Philosophy. It shows the existence of African Logic using examples from two Niger-Delta societies. The paper begins with the concept of Logic in African thought system, the natural nature of it and it’s applicability to these communities especially as it permeates every aspect of the African way of life. The Ibani and Ogoni societies in the Niger-Delta were used as case studies.

  19. An African-American family with dystonia.

    Science.gov (United States)

    Puschmann, Andreas; Xiao, Jianfeng; Bastian, Robert W; Searcy, Jill A; LeDoux, Mark S; Wszolek, Zbigniew K

    2011-08-01

    The genetic cause of late-onset focal and segmental dystonia remains unknown in most individuals. Recently, mutations in Thanatos-associated protein domain containing, apoptosis associated protein 1 (THAP1) have been described in DYT6 dystonia and associated with some cases of familial and sporadic late-onset dystonia in Caucasians. We are not aware of any previous descriptions of familial dystonia in African-Americans or reports of THAP1 mutations in African-Americans. Herein, we characterize an African-American (AA) kindred with late-onset primary dystonia, clinically and genetically. The clinical phenotype included cervical, laryngeal and hand-forearm dystonia. Symptoms were severe and disabling for several family members, whereas others only displayed mild signs. There were no accompanying motor or cognitive signs. In this kindred, age of onset ranged from 45 to 50 years and onset was frequently sudden, with symptoms developing within weeks or months. DYT1 was excluded as the cause of dystonia in this kindred. The entire genomic region of THAP1, including non-coding regions, was sequenced. We identified 13 sequence variants in THAP1, although none co-segregated with dystonia. A novel THAP1 variant (c.-237-3G>T/A) was found in 3/84 AA dystonia patient alleles and 3/212 AA control alleles, but not in 5870 Caucasian alleles. In summary, although previously unreported, familial primary dystonia does occur in African-Americans. Genetic analysis of the entire genomic region of THAP1 revealed a novel variant that was specific for African-Americans. Therefore, genetic testing for dystonia and future studies of candidate genes must take genetic background into consideration. PMID:21601506

  20. The evolution of African plant diversity

    Directory of Open Access Journals (Sweden)

    Hans Peter Linder

    2014-07-01

    Full Text Available Sub-Saharan Africa includes some 45,000 plant species. The spatial patterns of this diversity have been well explored. We can group the species into a set of biogeographical regions (largely co-incident with regions defined for terrestrial vertebrate groups. Furthermore, we know that the diversity is unevenly distributed, with southern Africa (especially the south-western tip disproportionally species rich, while the West African interior is disproportionally species poor. However, the origins of this diversity have only been explored for two anomalous African Floras (the Tropic-alpine Flora and the Cape Flora, whereas the origins of the diversity of the other floras are still unknown. Here I argue that six floras, with distinct geographical centres, different extra-African affinities, ages of radiation and radiation rates, can be delimited: the Austro-temperate, Tropic-alpine, Lowland forest, Tropic-montane, Savanna and Arid Floras. The oldest flora may be the Lowland forest Flora, and the most recent is the Tropic-alpine, which probably evolved during the Plio-Pleistocene on the summits of the East Africa volcanoes. My results suggest that the most rapidly radiating flora is the Austro-temperate Flora, while the other floras are all diversifying at more or less the same rate, this is also consistent with the current massive species richness in this flora (about half of the African species richness. The Austro-temperate Flora appears to be related to the floras of the other southern continents, the Tropic-alpine Flora to that of the Northern Hemisphere, and the four tropical floras to the tropical regions of the other continents, consistent with the theory of phylogenetic niche conservatism. Current African diversity may be the result of the sequential adding of new floras to the continent. Possibly the species poverty especially of the Lowland forest Flora may be the result of the spread of C4 grasslands and associated regular fires.

  1. Uplift of the South African Plateau: mantle-scale deformation, long wavelength relief growth and offshore sediment budget

    Science.gov (United States)

    Guillocheau, François; Dauteuil, Olivier; Baby, Guillaume; Robin, Cécile

    2013-04-01

    The South African Plateau is one of the largest very long wavelength relief (x1000 km) of the world that could be related to mantle dynamics and the effect of the African superplume. Unfortunately, the timing of the uplift and the different steps of the relief growth are still debated with a Late Cretaceous uplift scenario and an Oligocene one. Whatever model, few attentions were paid to the evolution of the overall geomorphic system, from the upstream erosional system to the downstream depositional system. This study is based, onshore, on the mapping and chronology of all the macroforms (weathering surfaces and associated alterites, pediments and pediplains, incised rivers, wave-cut platforms) dated by intersection with the few preserved sediments and the volcanics (mainly kimberlites pipes) and, offshore, on a more classical dataset of seismic lines and petroleum wells (characterization and dating of forced regression, sediment volume measurement, etc..). The main result of this study is that the South African Plateau is an old Late Cretaceous Plateau reactivated during Paleogene times and fossilized since the Middle Miocene. • During Late Cretaceous, in a semiarid climatic setting, the main uplift occurred from the east (around 95 Ma) to the west (around 75 Ma) and could result from the migration of the African plate over the African superplume: This is the paroxysm of the erosion with the growth of a large delta offshore present-day Orange River mouth (sedimentation rate around 100 000 km3/Ma). • During Paleocene - Mid Eocene times, in more humid conditions and in response to a more subtle long wavelength deformation, pedimentation occurred mainly localised along Cape Fold Belt feeding a large delta offshore western Cape Peninsula. During Mid Eocene times, all those landscapes are fossilized and weathered by laterites. • Late Eocene and Oligocene is the second period of uplift of the Plateau, localised along its Indian Ocean side (Drackensberg Moutains

  2. The frontier between Small-scale bipoles and Ephemeral Regions in the solar photosphere: Emergence and Decay of an Intermediate-scale bipole observed with IMaX/SUNRISE

    CERN Document Server

    Guglielmino, S L; Bonet, J A; Iniesta, J Carlos del Toro; Rubio, L R Bellot; Solanki, S K; Schmidt, W; Gandorfer, A; Barthol, P; Knölker, M

    2011-01-01

    We report on the photospheric evolution of an intermediate-scale (~4 Mm footpoint separation) magnetic bipole, from emergence to decay, observed in the quiet Sun at high spatial 0".3 and temporal (33 s) resolution. The observations were acquired by the IMaX imaging magnetograph during the first science flight of the Sunrise balloon-borne solar observatory. The bipole flux content is 6 x 10^17 Mx, representing a structure bridging the gap between granular scale bipoles and the smaller ephemeral regions. Footpoints separate at a speed of 3.5 km s-1 and reach a maximum distance of 4.5 Mm before the field dissolves. The evolution of the bipole is revealed to be very dynamic: we found a proper motion of the bipole axis and detected a change of the azimuth angle of 90{\\deg} in 300 seconds, that provides indication for twist and writhe in the emerging structure. The overall morphology and behaviour are in agreement with previous analyses of bipolar structures emerging at granular scale, but we also found several sim...

  3. Red River Wildlife Management Area HEP Report, Habitat Evaluation Procedures, Technical Report 2004.

    Energy Technology Data Exchange (ETDEWEB)

    Ashley, Paul

    2004-11-01

    A habitat evaluation procedures (HEP) analysis conducted on the 314-acre Red River Wildlife Management Area (RRWMA) managed by the Idaho Department of Fish and Game resulted in 401.38 habitat units (HUs). Habitat variables from six habitat suitability index (HSI) models, comprised of mink (Mustela vison), mallard (Anas platyrhynchos), common snipe (Capella gallinago), black-capped chickadee (Parus altricapillus), yellow warbler (Dendroica petechia), and white-tailed deer (Odocoileus virginianus), were measured by Regional HEP Team (RHT) members in August 2004. Cover types included wet meadow, riverine, riparian shrub, conifer forest, conifer forest wetland, and urban. HSI model outputs indicate that the shrub component is lacking in riparian shrub and conifer forest cover types and that snag density should be increased in conifer stands. The quality of wet meadow habitat, comprised primarily of introduced grass species and sedges, could be improved through development of ephemeral open water ponds and increasing the amount of persistent wetland herbaceous vegetation e.g. cattails (Typha spp.) and bulrushes (Scirpus spp.).

  4. Braided rivers, lakes and sabkhas of the upper Triassic Cifuncho formation, Atacama region, Chile

    Science.gov (United States)

    Suárez, M.; Bell, C. M.

    1994-01-01

    A 1,000-m-thickness of Upper Triassic (to possibly Hettangian) sediments of the Cifuncho Formation are exposed in the coastal Cordillera of the Atacama Region, Chile. These coarse-grained clastic terrigenous strata are interpreted as the deposits of braided rivers, ephemeral lakes, sabkhas and volcaniclastic alluvial fans. They include conglomerates, pebbly sandstones, fine to medium-grained sandstones and thin, finely-laminated limestones. Halite hopper-casts are abundant in sandstones near the top of the section. Approximately 90% of the clastic detritus was derived from an upper Paleozoic metasedimentary accretionary complex located to the west. Andesitic debris flow and pyroclastic flow deposits occur near the base of the sequence. Isolated tuff intercalations and an ignimbritic lava flow occur higher in the section. The great thickness of coarse-grained and ill-sorted clastic sediments suggests deposition in an actively subsiding basin, probably a graben, adjacent to rising highlands. Overlying Hettangian-Sinemurian marine sediments were deposited by a transgression which occurred during a world-wide lowstand. This suggests that thermal subsidence followed the Triassic rifting.

  5. Second floor, please: the fish fauna of floating litter banks in Amazonian streams and rivers

    Directory of Open Access Journals (Sweden)

    Lucelia Nobre Carvalho

    2013-03-01

    Full Text Available Floating litter banks are an ephemeral habitat consisting of branches, twigs, flowers, seeds, and fruits that are trapped on the stream water surface by a variety of retention mechanisms. These heterogeneous materials form a deep layer of dead plant matter that is colonized by a variety of organisms, including fish that forage on the aquatic macroinvertebrates found in this unique habitat. In this study, we aimed to characterize which fish species occupy the floating litter banks and their trophic characteristics, as well as determine if fish assemblage composition and species richness can be predicted by the size of the floating litter banks. Fish sampling was conducted in five rivers located in the Amazon basin. Of the 31 floating litter banks sampled that contained fish, 455 individuals were recorded and were distributed within 40 species, 15 families and five orders. Siluriformes were the most representative order among the samples and contained the largest number of families and species. The fish fauna sampled was mainly composed of carnivorous species that are typically found in submerged litter banks of Amazonian streams. The fish assemblage composition in the kinon can be predicted by the volume of the floating litter banks using both presence/absence and abundance data, but not its species richness. In conclusion, kinon banks harbor a rich fish assemblage that utilizes this habitat for shelter and feeding, and may function as a refuge for the fishes during the peak of the flooding season.

  6. Wind River: A Wild and Scenic River Analysis: Preliminary draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Wind River meets the criteria for inclusion in the National Wild and Scenic Rivers System. Subject to valid existing rights, the minerals in Federal lands which...

  7. Study on the Reutilization of River Sediment

    Institute of Scientific and Technical Information of China (English)

    LIU Gui-yun; JIANG Pei-hua; XI Dan-li

    2002-01-01

    Main components and properties of river sediment are introduced. Secondary pollution of river sediments to the water quality of the river is clarified. The methods of the reutilization of river sediment are elucidated.

  8. In Search of Greater Unity: African States and the Quest for an African Union Government

    Directory of Open Access Journals (Sweden)

    Sharkdam Wapmuk

    2009-12-01

    Full Text Available The paper examines the notion of an African union government.It argues that the proposal for a ‘union government’ has often divided African leaders into different ideological groups. That not withstanding, Africa leaders have had to bury their differences and embrace African unity in the fight against colonialism and racist rule. Under the OAU, these constituted the rallying point for African leaders until the last vestiges of colonialism and racist rule were crushed in South Africa in 1994. More than 40 years after the idea of unification of Africa was first suggested by Kwame Nkrumah of Ghana; the Libyan leader, President Muammar Ghaddafi re-tabled the proposal. However, the machinations being employed by the Libyan leader to actualise his vision of a union government in Africa under a single president necessitate a deeper exploration of the idea. The paper observed that the challenges to achieving a union government are numerous at this time. In addition toproblem of lack of integration at national levels and poor funding of the AU; Africa is presently faced with several problems bordering on violent conflicts, poverty and underdevelopment, economic development, diseases such as HIV-AIDS, malaria, tuberculosis, and bad governance amongst others. The paper concludes that these challenges should serve as the rallying point for African leaders at this time and not the political machinations of some leaders on the continent.

  9. 33 CFR 207.380 - Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Red Lake River, Minn.; logging... Red Lake River, Minn.; logging regulations for portion of river above Thief River Falls. (a) Parties wishing to run logs on Red Lake River must provide storage booms near the head of the river to take...

  10. Glucose intolerance in the West African Diaspora

    DEFF Research Database (Denmark)

    Nielsen, Jannie; Christensen, Dirk Lund

    2011-01-01

    muscle fibre type I. Skeletal muscle fibre type II is less oxidative and more glycolytic than skeletal muscle fibre type I. Lower oxidative capacity is associated with lower fat oxidation and a higher disposal of lipids, which are stored as muscular adipose tissue in higher amounts in Black compared......In the United States, Black Americans are largely descendants of West African slaves; they have a higher relative proportion of obesity and experience a higher prevalence of diabetes than White Americans. However, obesity rates alone cannot explain the higher prevalence of type 2 diabetes. Type 2...... diabetes is characterized by insulin resistance and beta-cell dysfunction. We hypothesize that the higher prevalence of type 2 diabetes in African Americans (as compared to White Americans) is facilitated by an inherited higher percentage of skeletal muscle fibre type II and a lower percentage of skeletal...

  11. Towards a Classification of the African Acacias

    Directory of Open Access Journals (Sweden)

    J. H. Ross

    1973-09-01

    Full Text Available Some of the first attempts to subdivide the genus Acacia Mill, as a whole are discussed briefly. Bentham’s work, in which the subdivisions of the genus were for the first time given names, is considered and his two series into which the African species fall are reproduced. The characters employed by various workers to divide the African species into two main groups are mentioned and the advantages of using each of these characters for the first dichotomy in a key are discussed. Recent work on pollen morphology and seedling morphology is correlated with general morphology. A proposal put forward by Guinet to divide Acacia into three large genera on the basis of pollen morphology is briefly discussed. Certain modifications to Bentham's series Vulgares and Gummiferae are suggested.

  12. 76 FR 36447 - Safety Zone; Patuxent River, Patuxent River, MD

    Science.gov (United States)

    2011-06-22

    ..., 2008, issue of the Federal Register (73 FR 3316). Public meeting We do not now plan to hold a public... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Patuxent River, Patuxent River, MD AGENCY... a temporary safety zone during the ``NAS Patuxent River Air Expo '11'', which consists of...

  13. RIVER FLOW CONDITIONS AND DYNAMIC STATE ANALYSIS OF PAHANG RIVER

    Directory of Open Access Journals (Sweden)

    Muhamad Barzani Gasim

    2013-01-01

    Full Text Available Pahang River (Sg. Pahang is the longest river in Peninsular Malaysia. Flood is a common event in Pahang River Basin during wet season which triggered by monsoon season. The hydrodynamic study of Pahang River should be well understood especially when it is a target of northeast monsoon which influenced the Pahang River Basin every year (from November to March. 17 river cross section stations were selected and used to measure its drainage capacity, hydraulic parameters and estimation of flow discharge. Long term (1980 to 2009 variation of hydrologic data series comprised of river flow, river stage and rainfall data were analyzed based on the Department of Irrigation and Drainage (DID Malaysia record. Monthly rainfall was recorded from Sg. Yap, Temerloh and Lubuk Paku Rainfall Stations. Two hydrologic sampling trips had been carried out; first sampling on January 2010 and second sampling on February 2010. The study indicates that velocity and river flow measurement during first sampling ranged from 0.308 to 0.582 m sec-1 and 153.282 to 439.684 m3 sec-1. Meanwhile, during second sampling, the velocity and river flow ranged from 0.217 to 0.484 and 52.071 to 304.485 m3 sec-1, respectively. Floods were occurred annually at Pahang River especially during northeast monsoon, these events are expected to be stimulated by the inconsistent condition of width and depth along Pahang River which finally create sedimentation and meandering characteristic.

  14. The Offshore East African Rift System

    Science.gov (United States)

    Franke, D.; Klimke, J.; Jokat, W.; Stollhofen, H.; Mahanjane, S.

    2014-12-01

    Numerous studies have addressed various aspects of the East African Rift system but surprisingly few on the offshore continuation of the south-eastern branch of the rift into the Mozambique Channel. The most prominent article has been published almost 30 years ago by Mougenot et al. (1986) and is based on vintage seismic data. Several studies investigating earthquakes and plate motions from GPS measurements reveal recent deformation along the offshore branch of the East African Rift system. Slip vectors from earthquakes data in Mozambique's offshore basins show a consistent NE direction. Fault plane solutions reveal ~ E-W extensional failure with focal depth clustering around 19 km and 40 km, respectively. Here, we present new evidence for neotectonic deformation derived from modern seismic reflection data and supported by additional geophysical data. The modern rift system obviously reactivates structures from the disintegration of eastern Gondwana. During the Jurassic/Cretaceous opening of the Somali and Mozambique Basins, Madagascar moved southwards along a major shear zone, to its present position. Since the Miocene, parts of the shear zone became reactivated and structurally overprinted by the East African rift system. The Kerimbas Graben offshore northern Mozambique is the most prominent manifestation of recent extensional deformation. Bathymetry data shows that it deepens northwards, with approximately 700 m downthrown on the eastern shoulder. The graben can be subdivided into four subbasins by crosscutting structural lineaments with a NW-SE trend. Together with the N-S striking graben-bounding faults, this resembles a conjugate fault system. In seismic reflection data normal faulting is distinct not only at the earthquake epicenters. The faults cut through the sedimentary successions and typically reach the seafloor, indicating ongoing recent deformation. Reference: Mougenot, D., Recq, M., Virlogeux, P., and Lepvrier, C., 1986, Seaward extension of the East

  15. African return migration: past, present, and future.

    Science.gov (United States)

    Gregory, J W; Piche, V

    1983-01-01

    The various forms of return migration in Africa in the twentieth century are first examined, and the factors affecting them are discussed. The authors then consider the value of the household, rather than the individual, as the unit of analysis. Return migration is also analyzed in terms of the linking role it plays between Africa's capitalist and non-capitalist countries. Finally, alternative future trends in the circulatory flow of African labor are considered.

  16. Obesity and Pulmonary Function in African Americans

    OpenAIRE

    Mehari, Alem; Afreen, Samina; Ngwa, Julius; Setse, Rosanna; Thomas, Alicia N.; Poddar, Vishal; Davis, Wayne; Polk, Octavius D.; Hassan, Sheik; Thomas, Alvin V.

    2015-01-01

    Background Obesity prevalence in United States (US) adults exceeds 30% with highest prevalence being among blacks. Obesity is known to have significant effects on respiratory function and obese patients commonly report respiratory complaints requiring pulmonary function tests (PFTs). However, there is no large study showing the relationship between body mass index (BMI) and PFTs in healthy African Americans (AA). Objective To determine the effect of BMI on PFTs in AA patients who did not have...

  17. Social mobility in five African countries

    OpenAIRE

    Bossuroy, T.; Cogneau, Denis

    2013-01-01

    This paper conceptualizes intergenerational occupational mobility between the farm and non-farm sectors in five African countries, measures it using nationally representative household survey data, and analyzes its determinants through a comparative method based on pooled logit regressions. We first analyze intergenerational gross mobility. Until the end of the 1980s, intergenerational flows toward the non-farm sector are high in Cote d'Ivoire and Guinea, flows toward the farm sector are more...

  18. Intestinal plasmacytoma in an African hedgehog.

    Science.gov (United States)

    Ramos-Vara, J A; Miller, M A; Craft, D

    1998-04-01

    A 3-yr-old male African hedgehog (Atelerix albiventris) had anorexia and weight loss for 1 wk before its death. The colon and mesocolon were diffusely infiltrated by a neoplastic proliferation of round cells with plasmacytoid features. A diagnosis of intestinal plasmacytoma was made and confirmed by electron microscopy. No other organs appeared to be affected. This is the first description of intestinal plasmacytoma in a hedgehog. PMID:9577789

  19. South African History Online's Education Programme.

    OpenAIRE

    Jardine, Varushka

    2011-01-01

    This paper outlines South African History Online as a NGO that focuses on the enhancement of history especially at school level. The advent of digital and social media platforms has changed the way scholars learn and the way they perceive their world. The book, paper and journals should no longer provide the exclusive model for historical knowledge to be passed on. With this in mind, SAHO has developed a comprehensive online programme that focuses on the current curriculum a...

  20. Caring school leadership: a South African study

    OpenAIRE

    Van der Vyver, C.P.; Van der Westhuizen, P C; Meyer, L.W.

    2014-01-01

    The research pivoted on the question whether South African school principals fulfilled their caring role towards teachers. The aims of the study were threefold. First, to determine how principals rated their care-giving, secondly to determine whether significant discrepancies existed between principals’ rating of their care-giving and teachers’ experiences thereof and thirdly to identify the determinants of care that contributed the most and the least towards principals’ care-givi...

  1. Africans in the American Labor Market.

    Science.gov (United States)

    Elo, Irma T; Frankenberg, Elizabeth; Gansey, Romeo; Thomas, Duncan

    2015-10-01

    The number of migrants to the United States from Africa has grown exponentially since the 1930s. For the first time in America's history, migrants born in Africa are growing at a faster rate than migrants from any other continent. The composition of African-origin migrants has also changed dramatically: in the mid-twentieth century, the majority were white and came from only three countries; but today, about one-fifth are white, and African-origin migrants hail from across the entire continent. Little is known about the implications of these changes for their labor market outcomes in the United States. Using the 2000-2011 waves of the American Community Survey, we present a picture of enormous heterogeneity in labor market participation, sectoral choice, and hourly earnings of male and female migrants by country of birth, race, age at arrival in the United States, and human capital. For example, controlling a rich set of human capital and demographic characteristics, some migrants-such as those from South Africa/Zimbabwe and Cape Verde, who typically enter on employment visas-earn substantial premiums relative to other African-origin migrants. These premiums are especially large among males who arrived after age 18. In contrast, other migrants-such as those from Sudan/Somalia, who arrived more recently, mostly as refugees-earn substantially less than migrants from other African countries. Understanding the mechanisms generating the heterogeneity in these outcomes-including levels of socioeconomic development, language, culture, and quality of education in countries of origin, as well as selectivity of those who migrate-figures prominently among important unresolved research questions. PMID:26304845

  2. African Woman Gets No.2 UN Post

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With a pledge to work for an inte-grated UN, former Tanzanian Foreign Minister Asha-Rose Migiro was sworn in as UN deputy secretary gen-eral on February 5, making her the first woman from the African conti-nent to hold such a powerful posi-tion in the world body.Migiro’s appointment early last month was widely seen as a signal of new UN Secretary General Ban Ki Moon’s reform initia-

  3. Assessing sanitary mixtures in East African cities

    OpenAIRE

    Letema, S.C.

    2012-01-01

    The urbanisation of poverty and informality in East African cities poses a threat to environmental health, perpetuates social exclusion and inequalities, and creates service gaps (UN-Habitat, 2008). This makes conventional sanitation provision untenable citywide, giving rise to the emergence of sanitation mixtures. Sanitation mixtures have different scales, institutional arrangements, user groups, and rationalities for their establishment, location, and management. For assessing the performan...

  4. Digital Empowerment: African Women and Creative Media

    OpenAIRE

    Neff, Ali Colleen

    2016-01-01

    Drawing from seven years' research with women singers, dancers, emcees, and ritual practitioners in Senegal and beyond, Dr. Neff examines the ways in which ethnic traditions intersect with the possibility of digital futures. Although their work is often overlooked in conventional conversations about digital invention, African women engage digital technologies--from the hip-hop recording studio, to religious media, to pop videos, and, perhaps most importantly, social media, in ways that contri...

  5. African perspectives on the clean development mechanism

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-08-01

    The papers, which are all written from an African perspective, are an important contribution to the debate surrounding the relevance and applicability of the Clean Development Mechanism in Africa. In addition to sector-specific discussions on the prospects for CDM in the energy, transport, industry and forestry sectors, various authors have attempted to tackle complex issues related to the instituional design of CDM, its mode of operation, participatory implementation and methodological questions such as baselines and additionality. (au)

  6. African Primary Care Research: Participatory action research

    OpenAIRE

    Bob Mash

    2014-01-01

    Abstract This article is part of the series on African primary care research and focuses on participatory action research. The article gives an overview of the emancipatory-critical research paradigm, the key characteristics and different types of participatory action research. Following this it describes in detail the methodological issues involved in professional participatory action research and running a cooperative inquiry group. The article is intended to help students with writing thei...

  7. African Independent Churches in Zambia (Lusaka)

    OpenAIRE

    Mildnerová Kateřina

    2014-01-01

    The African Independent churches (AICs) in Zambia, as elsewhere in Africa, from their very beginning formed a protest movement against the cultural imperialism undertaken by the missionary representatives of the historic mission churches and also played an important role in the anti-colonial political struggles. In Zambia, the early AICs were closely related to witchcraft eradication movements such as the Mchape, or socially and politically oriented prophet-healing churches such as The Lumpa ...

  8. The Politics of African Industrial Policy

    DEFF Research Database (Denmark)

    Whitfield, Lindsay; Therkildsen, Ole; Buur, Lars;

    2015-01-01

    This book engages in the debate on growth versus economic transformation and the importance of industrial policy, presenting a comprehensive framework for explaining the politics of industrial policy. Using comparative research to theorize about the politics of industrial policy in countries in the...... early stages of capitalist transformation that also experience the pressures of elections due to democratization, this book provides four in-depth African country studies that illustrate the challenges to economic transformation and the politics of implementing industrial policies....

  9. Sprague River Oregon Floodplain 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  10. Sprague River Oregon Floodplain Centerline

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  11. Sprague River Oregon Vegetation 1968

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  12. Missouri River 1943 Compact Line

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Flood Control, Bank Stabilization and development of a navigational channel on the Missouri River had a great impact on the river and adjacent lands. The new...

  13. Sprague River Oregon Bars 1940

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  14. Sprague River Oregon Bars 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  15. Sprague River Oregon Bars 1968

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  16. Sprague River Oregon Floodplain 1968

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  17. Sprague River Oregon Centerline 1940

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  18. Sprague River Oregon Water 1940

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  19. The River Lune fact file

    OpenAIRE

    1994-01-01

    This document provides a brief introduction to the River Lune catchment and the role that the National Rivers Authority plays in catchment management. Included are a map of the catchment and short introductions to fisheries and characteristics of the catchment.

  20. Sprague River Oregon Centerline 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  1. Sprague River Oregon Centerline 1968

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  2. Sprague River Oregon Floodplain Boundary

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Sprague River drains 4090 square kilometers in south-central Oregon before flowing into the Williamson River and upper Klamath Lake. In cooperation with the...

  3. The college life experiences of African American women athletes.

    Science.gov (United States)

    Sellers, R M; Kuperminc, G P; Damas, A

    1997-10-01

    The present study provides a descriptive analysis of four areas of African American women student athletes' college life experiences: academic performance; alienation and abuse; perceived social advantage as the result of athletics; and life satisfaction. Multivariate comparisons were made between the four areas of college life experiences of 154 African American women student athletes and 793 White women student athletes, 250 African American women nonathletes, and 628 African American men student athletes from a national sample of 39 NCAA Division I universities. Overall, African American women student athletes are performing adequately academically, integrating socially within the university, perceiving some social advantage as the result of being athletes, and are fairly satisfied with their life. Their experiences seem most consistent with African American women nonathletes. Results are discussed in the context of potential policy recommendations as well as the need for more research on this particular population. PMID:9485580

  4. Rethinking "relevance": South African psychology in context.

    Science.gov (United States)

    Long, Wahbie

    2013-02-01

    This article examines the phenomenon known as the "relevance debate" in South African psychology. It begins with a historical overview of the contours of the discipline in that country before describing the controversy's international dimensions, namely, the revolutionary politics of 1960s higher education and the subsequent emergence of cognate versions of the debate in American, European, and "Third World" psychology. The article then details how South Africa's "relevance" project enjoyed a special affinity with an assortment of ethnic-cultural, national, and continental myths and metaphors, all of which served the interests of the political formations of the day. It discusses how, in present-day South Africa, the intelligentsia has become an important catalyst for the so-called African Renaissance, which seeks to provide "relevant" solutions for the regeneration of African society. However, the global hegemony of what began in the 1970s as a "second academic revolution," aided by the lifting of the academic boycott of South Africa, has blunted the once critical edge of "relevance" discourse. A new mode of knowledge production now holds sway, the outcome of a dramatic reformulation of the capitalist manifesto in which the values of the "May 68" generation have been hijacked by a managerialist rationality. In light of the capitalization of the knowledge-production enterprise, it is concluded that the idiom of "relevance" has outlived its usefulness. PMID:23421936

  5. Intracranial aneurysms in an African country

    Directory of Open Access Journals (Sweden)

    Ogeng'o Julius

    2009-12-01

    Full Text Available Background : Characteristics of intracranial aneurysms display ethnic variations. Data on this disease from the African continent is scarce and often conflicting. Aim : To describe site, age and gender distribution of intracranial aneurysms among Kenyans. Study Design and Setting : Retrospective study at Kenyatta National Hospital, Kenya. Materials and Methods: All records of black African patients with a diagnosis of intracranial aneurysms seen at Kenyatta National Hospital, the largest referral hospital in the Eastern and Central African region, over the period from January 1998 to December 2007 were examined for site, age and gender distribution. The data gathered were coded, analyzed with SPSS 11.50. Results : Fifty-six cases of intracranial aneurysms were analyzed. The posterior communicating artery was the most affected (35.7%, followed by the anterior communicating artery (26.8%, while the posterior cerebral artery was the least affected (2%. Multiple aneurysms were present in 2%. The mean age at presentation was 50.9 years (range 21-80 years and the gender distribution was equal. Conclusions : Intracranial aneurysms among Kenyans occur most commonly on the posterior communicating artery, in young individuals, and without gender bias. The distribution differs from that described in the literature and this requires search for risk factors.

  6. Cystic fibrosis on the African continent.

    Science.gov (United States)

    Stewart, Cheryl; Pepper, Michael S

    2016-07-01

    Cystic fibrosis (CF; OMIM 219700) is a life-shortening and costly autosomal recessive disease that has been most extensively studied in individuals of Caucasian descent. There is ample evidence, however, that it also affects other ethnicities. In Africa there have been several reports of CF, but there has been no concerted effort toward establishing the molecular epidemiology of this disease on the continent, which is the first step toward outlining a public health strategy to effectively address the needs of these patients. A literature search revealed reports from only 12 of the 54 African states on the molecular analysis of the mutations present in suspected CF patients, resulting in the identification of 79 mutations. Based on previous functional investigations, 39 of these cause CF, 10 are of varying clinical consequence, 4 have no associated evidence regarding whether they cause CF, 4 are synonymous, 5 are novel, and 21 are unique to Africa. We propose that CF be more thoroughly investigated on the continent to ensure that the public health needs of African CF patients-both those in Africa and those of African descent living elsewhere-are met.Genet Med 18 7, 653-662. PMID:26656651

  7. Micropropagation of African violet (Saintpaulia ionantha Wendl.).

    Science.gov (United States)

    Shukla, Mukund; Sullivan, J Alan; Jain, Shri Mohan; Murch, Susan J; Saxena, Praveen K

    2013-01-01

    Micropropagation is an important tool for rapid multiplication and the creation of genetic variability in African violets (Saintpaulia ionantha Wendl.). Successful in vitro propagation depends on the specific requirements and precise manipulation of various factors such as the type of explants used, physiological state of the mother plant, plant growth regulators in the culture medium, and growth conditions. Development of cost-effective protocols with a high rate of multiplication is a crucial requirement for commercial application of micropropagation. The current chapter describes an optimized protocol for micropropagation of African violets using leaf explants obtained from in vitro grown plants. In this process, plant regeneration occurs via both somatic embryogenesis and shoot organogenesis simultaneously in the explants induced with the growth regulator thidiazuron (TDZ; N-phenyl-N'-1,2,3-thidiazol-5-ylurea). The protocol is simple, rapid, and efficient for large-scale propagation of African violet and the dual routes of regeneration allow for multiple applications of the technology from simple clonal propagation to induction or selection of variants to the production of synthetic seeds. PMID:23179707

  8. Geomorphic change and sediment transport during a small artificial flood in a transformed post-dam delta: The Colorado River delta, United States and Mexico

    Science.gov (United States)

    Mueller, Erich R.; Schmidt, John C.; Topping, David J.; Shafroth, Patrick B.; Rodríguez-Burgueño, Jesús Eliana; Ramírez-Hernández, Jorge; Grams, Paul E.

    2016-01-01

    The Colorado River delta is a dramatically transformed landscape. Major changes to river hydrology and morpho-dynamics began following completion of Hoover Dam in 1936. Today, the Colorado River has an intermittent and/or ephemeral channel in much of its former delta. Initial incision of the river channel in the upstream ∼50 km of the delta occurred in the early 1940s in response to spillway releases from Hoover Dam under conditions of drastically reduced sediment supply. A period of relative quiescence followed, until the filling of upstream reservoirs precipitated a resurgence of flows to the delta in the 1980s and 1990s. Flow releases during extreme upper basin snowmelt in the 1980s, flood flows from the Gila River basin in 1993, and a series of ever-decreasing peak flows in the late 1990s and early 2000s further incised the upstream channel and caused considerable channel migration throughout the river corridor. These variable magnitude post-dam floods shaped the modern river geomorphology. In 2014, an experimental pulse-flow release aimed at rejuvenating the riparian ecosystem and understanding hydrologic dynamics flowed more than 100 km through the length of the delta’s river corridor. This small artificial flood caused localized meter-scale scour and fill of the streambed, but did not cause further incision or significant bank erosion because of its small magnitude. Suspended-sand-transport rates were initially relatively high immediately downstream from the Morelos Dam release point, but decreasing discharge from infiltration losses combined with channel widening downstream caused a rapid downstream reduction in suspended-sand-transport rates. A zone of enhanced transport occurred downstream from the southern U.S.-Mexico border where gradient increased, but effectively no geomorphic change occurred beyond a point 65 km downstream from Morelos Dam. Thus, while the pulse flow connected with the modern estuary, deltaic sedimentary processes were not

  9. Stochastic modelling of river morphodynamics

    OpenAIRE

    Van Vuren, B.G.

    2005-01-01

    Modern river management has to reconcile a number of functions, such as protection against floods and provision of safe and efficient navigation, floodplain agriculture, ecology and recreation. Knowledge on uncertainty in fluvial processes is important to make this possible, to design effective river engineering works, for operational forecasting and for the maintenance of the river system. In this research the focus is in particular on the quantification of uncertainty in river morphodynamic...

  10. Mayo's Older African Americans Normative Studies: WMS-R norms for African American elders.

    Science.gov (United States)

    Lucas, John A; Ivnik, Robert J; Smith, Glenn E; Ferman, Tanis J; Willis, Floyd B; Petersen, Ronald C; Graff-Radford, Neill R

    2005-06-01

    Norms for African American elders on the Wechsler Memory Scale-Revised (WMS-R) were derived from a sample of 309 community-dwelling individuals participating in Mayo's Older African Americans Normative Studies (MOAANS). Normative estimates are provided for traditional WMS-R subtest scores and for supplemental procedures to evaluate forgetting rates and recognition memory. Tables are provided to convert raw WMS-R subtest and supplemental scores to age-corrected scaled scores. These may be further adjusted for years of education, if desired, by applying regression-based corrections. We anticipate that these data will enhance the diagnostic utility and clinical interpretation of WMS-R performance in older African Americans.

  11. Harnessing the Power of Globalization for African Development

    OpenAIRE

    Kwabena Gyimah-Brempong

    2010-01-01

    This address highlights how Africa can take advantage of the current wave of globalization to accelerate its development efforts. The central theme is that African countries should not be afraid to open up their economies to globalization because openness confers several benefits, including technology transfers, expanding markets for African exports, and employment creation. However, to be able to take advantage of the benefits of globalization, African countries need to improve their domesti...

  12. Consumer ethnocentrism and conspicuousness of South African imports in Mozambique

    OpenAIRE

    John, Anna

    2011-01-01

    Focus of the study The study examines the nature and effects of consumer ethnocentrism and conspicuousness of imports on consumer reactions toward South African products in Mozambique. Purpose The purpose of the study is threefold: (1) to indicate those groups of Mozambican consumers who are more ethnocentric and who see greater conspicuousness in South African imports; (2) to indicate those groups of consumers whose consumer ethnocentric responses to South African versus Moza...

  13. Older African American Women’s Lived Experiences with Depression

    OpenAIRE

    Ward, Earlise C.; Mengesha, Maigenete; Issa, Fathiya

    2013-01-01

    Little is known about older African American women’s lived experiences with depression. What does depression mean to this group? What are they doing about their depression? Unfortunately, these questions are unanswered. This study examined older African American women’s lived experiences with depression and coping behaviours. The common sense model provided the theoretical framework for present study. Thirteen community-dwelling African American women aged 60 and older (M =71 years) participa...

  14. Fluconazole in the therapy of multiple osteomyelitis in African histoplasmosis

    OpenAIRE

    Onwuasoigwe, O.

    1999-01-01

     Amphotericin B has been the standard treatment for deep mycoses including African histoplasmosis, but its use is complicated by its toxicity. More recently, Fluconazole, a water-soluble triazole with antimycotic activity and little side effects, has become available. A case of African histoplasmosis from Nigeria, manifesting as multiple osteomyelitis and successfully treated with oral Fluconazole, is presented. Fluconazole may be preferred in the therapy of African histoplasmosis.

  15. The black Dutchmen: African soldiers in the Netherlands East Indies

    OpenAIRE

    Kessel, van, CGM

    2002-01-01

    Between 1831 and 1872 some 3000 African recruits sailed from Elmina (Gold Coast, now Ghana) to Batavia, the capital of the Netherlands East Indies. They had been recruited to serve in the Dutch colonial army, which throughout most of the 19th century experienced a chronic shortage of European manpower. The Africans counted as part of the European contingent of the army. After expiry of their contracts, some Africans returned to the Gold Coast, while others opted to settle in the East Indies. ...

  16. African migrants in South Africa : an interactional perspective / Shingairai Chigeza

    OpenAIRE

    Chigeza, Shingairai

    2012-01-01

    The movement of African migrants from their countries of origin to other countries in search of a better future will continue to increase. However, such movement is accompanied by many challenges. Literature indicates that African migrants in South Africa face challenges such as cultural differences, exploitation and xenophobia. In the context of migration, migrants and citizens constantly interact with one another. The relational patterns between African migrants and citizens accordingly nee...

  17. Welfare of African catfish : effects of stocking density

    OpenAIRE

    Nieuwegiessen, van de, P.G.

    2009-01-01

    The general aim of this thesis was to determine the impact of stocking density on welfare indicators in African catfish, Clarias gariepinus, cultured in a recirculating aquaculture system. The following factors were studied: 1) the effects of stocking density on physical, physiological, and behavioural responses of African catfish, 2) how age mediates the effects of stocking density on physical, physiological, and behavioural responses of African catfish, 3) the potential effects of chemical ...

  18. The Reflection of Race and Law in African American Literature

    Directory of Open Access Journals (Sweden)

    Peter Schneck

    2008-06-01

    Full Text Available Since the law has been crucial in defining and delineating the dimensions of African American experience both in slavery and in freedom, the encounter with the American legal system and its representatives has left a strong imprint on African American cultural and literary memory and expression. The article sketches out a few aspects and features which characterize the reflection of law and race in African American culture and literature.

  19. The Reflection of Race and Law in African American Literature

    OpenAIRE

    Peter Schneck

    2008-01-01

    Since the law has been crucial in defining and delineating the dimensions of African American experience both in slavery and in freedom, the encounter with the American legal system and its representatives has left a strong imprint on African American cultural and literary memory and expression. The article sketches out a few aspects and features which characterize the reflection of law and race in African American culture and literature.

  20. Institutions in African history and development: A review essay

    OpenAIRE

    Fenske, James

    2010-01-01

    In this review, I discuss the role of African institutions in general and pre-colonial institutions in particular in explaining present-day African poverty. Six of the most often cited explanations of African poverty -- geography, ethnolinguistic fractionalization, the slave trades, colonial rule, underdevelopment, and failed aid -- operate largely through institutions. Bad institutions themselves directly affect modern growth. Pre-colonial institutions also matter for present-day outcomes. I...