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Sample records for african region methods

  1. Validation of the TEC2F2 model over the African equatorial region

    NASA Astrophysics Data System (ADS)

    Ssessanga, Nicholas

    2016-06-01

    In this paper a statistical method, TEC2F2, of estimating critical F2 layer frequency (foF2) from Global Positioning System (GPS) Vertical Total Electron content (VTEC) is extended from Africa's mid-latitudes to the equatorial region, and the results validated. The equatorial region is one of the most dynamic yet under-represented over Africa in ionospheric studies. The TEC2F2 method was first considered for the South African region (mid-latitudes). This region is covered by a network of ionosondes that provided a validation platform for the TEC2F2 method before being applied to other parts of Africa. The results show that over the African equatorial region, the TEC2F2 method is a potential candidate in more accurately estimating the foF2 parameter than the most recent version of the International Reference Ionosphere (IRI-2012) model.

  2. Using the Afrocentric Method in Researching Indigenous African Culture

    ERIC Educational Resources Information Center

    Mkabela, Queeneth

    2005-01-01

    The article highlights the realities and dynamics facing researchers researching indigenous African culture. The cultural aspirations, understandings, and practices of African indigenous people should position researchers to implement and organize the research process. Suggestions are also made for implementing the "Afrocentric method," and how to…

  3. Regional analysis of convective systems during the West African monsoon

    NASA Astrophysics Data System (ADS)

    Guy, Bradley Nicholas

    characteristics (e.g. total precipitation and vertical reflectivity profiles) at the inland and maritime sites. The wave regime also resulted in an increased population of the largest observed mesoscale convective systems observed near the coast, which led to an increase in stratiform precipitation. Despite this increase, differentiation of convective strength characteristics was less obvious between wave and no-wave regimes at the coast. Due to the propagating nature of these advecting mesoscale convective systems, interaction with the regional thermodynamic and dynamic environment appears to result in more variability than enhancements due to the wave regime, independent of location. A 13-year (1998-2010) climatology of mesoscale convective characteristics associated with the West African monsoon are also investigated using precipitation radar and passive microwave data from the NASA Tropical Rainfall Measuring Mission satellite. Seven regions defined as continental northeast and northwest, southeast and southwest, coastal, and maritime north and south are compared to analyze zonal and meridional differences. Data are categorized according to identified African easterly wave (AEW) phase and when no wave is present. While some enhancements are observed in association with AEW regimes, regional differences were generally more apparent than wave vs. no-wave differences. Convective intensity metrics confirm that land-based systems exhibit stronger characteristics, such as higher storm top and maximum 30-dBZ heights and significant 85-GHz brightness temperature depressions. Continental systems also contain a lower fraction of points identified as stratiform. Results suggest that precipitation processes also varied depending upon region and AEW regime, with warm-rain processes more apparent over the ocean and the southwest continental region and ice-based microphysics more dominant over land, including mixed-phase processes. AEW regimes did show variability in stratiform fraction and

  4. Monitoring Southern African Rainfall Season Utilizing Growing Regions

    NASA Astrophysics Data System (ADS)

    Husak, G. J.; Magadzire, T.

    2005-12-01

    Variability in timing and amount of rainfall during the growing season in southern Africa can have a dramatic impact on livelihoods in the region. This research integrates satellite model rainfall amounts with expectations for the remainder of the season to provide an envelope of likely outcomes for different growing regions. Satellite information combined with station observations combine to make the African Rainfall Climatology (ARC), which is used to estimate the start of season (SOS) and monitor the season-to-date rainfall accumulations at a pixel level. The Collaborative Historical African Rainfall Model (CHARM) - a 36-year climatology based on available station fields, global climate models and an orographic component - is used to estimate various scenarios for the remainder of the season. The season length is defined by location specific length of growing period provided by the Southern African Development Community (SADC). Once the SOS is observed according to the ARC, seasonal accumulations for each pixel begin and are evaluated at a dekadal interval. These accumulations can be compared to historical accumulations after an equal number of dekads to evaluate the progression of the season as a percentage of historical season-to-date totals for each pixel. Rainfall accumulations for the remainder of the growing period can be tallied for each year of the CHARM dataset, and Gamma probability distribution parameters can be fit to these values. Using these distribution parameters, it is possible to evaluate scenarios for the remainder of the season and combine them with the accumulations from the ARC to arrive at total rainfall accumulated during a growing period. Analysis of these totals can be compared with long-term mean accumulations for the growing period to estimate how crops will fare relative to past performance. Evaluation of various wet and dry scenarios for the remainder of the season, defined here as the 80th percentile and 20th percentile, provide an

  5. Impact of disaster-related mortality on gross domestic product in the WHO African Region

    PubMed Central

    Kirigia, Joses M; Sambo, Luis G; Aldis, William; Mwabu, Germano M

    2004-01-01

    Background Disaster-related mortality is a growing public health concern in the African Region. These deaths are hypothesized to have a significantly negative effect on per capita gross domestic product (GDP). The objective of this study was to estimate the loss in GDP attributable to natural and technological disaster-related mortality in the WHO African Region. Methods The impact of disaster-related mortality on GDP was estimated using double-log econometric model and cross-sectional data on various Member States in the WHO African Region. The analysis was based on 45 of the 46 countries in the Region. The data was obtained from various UNDP and World Bank publications. Results The coefficients for capital (K), educational enrolment (EN), life expectancy (LE) and exports (X) had a positive sign; while imports (M) and disaster mortality (DS) were found to impact negatively on GDP. The above-mentioned explanatory variables were found to have a statistically significant effect on GDP at 5% level in a t-distribution test. Disaster mortality of a single person was found to reduce GDP by US$0.01828. Conclusions We have demonstrated that disaster-related mortality has a significant negative effect on GDP. Thus, as policy-makers strive to increase GDP through capital investment, export promotion and increased educational enrolment, they should always keep in mind that investments made in the strengthening of national capacity to mitigate the effects of national disasters expeditiously and effectively will yield significant economic returns. PMID:15113453

  6. Impact of disaster-related mortality on gross domestic product in the WHO African Region.

    PubMed

    Kirigia, Joses M; Sambo, Luis G; Aldis, William; Mwabu, Germano M

    2004-03-15

    BACKGROUND: Disaster-related mortality is a growing public health concern in the African Region. These deaths are hypothesized to have a significantly negative effect on per capita gross domestic product (GDP). The objective of this study was to estimate the loss in GDP attributable to natural and technological disaster-related mortality in the WHO African Region. METHODS: The impact of disaster-related mortality on GDP was estimated using double-log econometric model and cross-sectional data on various Member States in the WHO African Region. The analysis was based on 45 of the 46 countries in the Region. The data was obtained from various UNDP and World Bank publications. RESULTS: The coefficients for capital (K), educational enrolment (EN), life expectancy (LE) and exports (X) had a positive sign; while imports (M) and disaster mortality (DS) were found to impact negatively on GDP. The above-mentioned explanatory variables were found to have a statistically significant effect on GDP at 5% level in a t-distribution test. Disaster mortality of a single person was found to reduce GDP by US$0.01828. CONCLUSIONS: We have demonstrated that disaster-related mortality has a significant negative effect on GDP. Thus, as policy-makers strive to increase GDP through capital investment, export promotion and increased educational enrolment, they should always keep in mind that investments made in the strengthening of national capacity to mitigate the effects of national disasters expeditiously and effectively will yield significant economic returns. PMID:15113453

  7. Regional environmental simulation of African cattle herding societies

    SciTech Connect

    Krummel, J.R.; Markin, J.B.; O'Neill, R.V.

    1986-03-01

    Regional analyses of the interaction between human populations and natural resources must integrate landscape scale environmental problems. An approach that considers human culture, environmental processes, and resource needs offers an appropriate methodology. With this methodology, we analyze problems of food availability in African cattle-keeping societies. The analysis interrelates cattle biomass, forage availability, milk and blood production, crop yields, gathering, food subsidies, population, and variable precipitation. While an excess of cattle leads to overgrazing, cattle also serve as valuable food storage mechanisms during low rainfall periods. Food subsidies support higher population levels but do not alter drought-induced population fluctuations. Variable precipitation patterns require solutions that stabilize year-to-year food production and also address problems of overpopulation.

  8. Extreme events evaluation over African cities with regional climate simulations

    NASA Astrophysics Data System (ADS)

    Bucchignani, Edoardo; Mercogliano, Paola; Simonis, Ingo; Engelbrecht, Francois

    2013-04-01

    The warming of the climate system in recent decades is evident from observations and is mainly related to the increase of anthropogenic greenhouse gas concentrations (IPCC, 2012). Given the expected climate change conditions on the African continent, as underlined in different publications, and their associated socio-economic impacts, an evaluation of the specific effects on some strategic African cities on the medium and long-term is of crucial importance with regard to the development of adaptation strategies. Assessments usually focus on averages climate properties rather than on variability or extremes, but often these last ones have more impacts on the society than averages values. Global Coupled Models (GCM) are generally used to simulate future climate scenarios as they guarantee physical consistency between variables; however, due to the coarse spatial resolution, their output cannot be used for impact studies on local scales, which makes necessary the generation of higher resolution climate change data. Regional Climate Models (RCM) describe better the phenomena forced by orography or by coastal lines, or that are related to convection. Therefore they can provide more detailed information on climate extremes that are hard to study and even harder to predict because they are, by definition, rare and obey different statistical laws. The normal bias of the RCM to represent the local climatology is reduced using adequate statistical techniques based on the comparison of the simulated results with long observational time series. In the framework of the EU-FP7 CLUVA (Climate Change and Urban Vulnerability in Africa) project, regional projections of climate change at high resolution (about 8 km), have been performed for selected areas surrounding five African cities. At CMCC, the regional climate model COSMO-CLM has been employed: it is a non-hydrostatic model. For each domain, two simulations have been performed, considering the RCP4.5 and RCP8.5 emission

  9. Projections of African drought extremes in CORDEX regional climate simulations

    NASA Astrophysics Data System (ADS)

    Gbobaniyi, Emiola; Nikulin, Grigory; Jones, Colin; Kjellström, Erik

    2013-04-01

    We investigate trends in drought extremes for different climate regions of the African continent over a combined historical and future period 1951-2100. Eight CMIP5 coupled atmospheric global climate models (CanESM2, CNRM-CM5, HadGEM2-ES, NorESM1-M, EC-EARTH, MIROC5, GFDL-ESM2M and MPI-ESM-LR) under two forcing scenarios, the relative concentration pathways (RCP) 4.5 and 8.5, with spatial resolution varying from about 1° to 3° are downscaled to 0.44° resolution by the Rossby Centre (SMHI) regional climate model RCA4. We use data from the ensuing ensembles of CORDEX-Africa regional climate simulations to explore three drought indices namely: standardized precipitation index (SPI), moisture index (MI) and difference in precipitation and evaporation (P-E). Meteorological and agricultural drought conditions are assessed in our analyses and a climate change signal is obtained for the SPI by calculating gamma functions for future SPI with respect to a baseline present climate. Results for the RCP4.5 and RCP8.5 scenarios are inter-compared to assess uncertainties in the future projections. We show that there is a pronounced sensitivity to the choice of forcing GCM which indicates that assessments of future drought conditions in Africa would benefit from large model ensembles. We also note that the results are sensitive to the choice of drought index. We discuss both spatial and temporal variability of drought extremes for different climate zones of Africa and the importance of the ensemble mean. Our study highlights the usefulness of CORDEX simulations in identifying possible future impacts of climate at local and regional scales.

  10. Analysis of Genomic Regions Associated With Coronary Artery Disease Reveals Continent-Specific Single Nucleotide Polymorphisms in North African Populations

    PubMed Central

    Zanetti, Daniela; Via, Marc; Carreras-Torres, Robert; Esteban, Esther; Chaabani, Hassen; Anaibar, Fatima; Harich, Nourdin; Habbal, Rachida; Ghalim, Noreddine; Moral, Pedro

    2016-01-01

    Background In recent years, several genomic regions have been robustly associated with coronary artery disease (CAD) in different genome-wide association studies (GWASs) conducted mainly in people of European descent. These kinds of data are lacking in African populations, even though heart diseases are a major cause of premature death and disability. Methods Here, 384 single nucleotide polymorphisms (SNPs) in the top four CAD risk regions (1p13, 1q41, 9p21, and 10q11) were genotyped in 274 case-control samples from Morocco and Tunisia, with the aim of analyzing for the first time if the associations found in European populations were transferable to North Africans. Results The results indicate that, as in Europe, these four genetic regions are also important for CAD risk in North Africa. However, the individual SNPs associated with CAD in Africa are different from those identified in Europe in most cases (1p13, 1q41, and 9p21). Moreover, the seven risk variants identified in North Africans are efficient in discriminating between cases and controls in North African populations, but not in European populations. Conclusions This study indicates a disparity in markers associated to CAD susceptibility between North Africans and Europeans that may be related to population differences in the chromosomal architecture of these risk regions. PMID:26780859

  11. Progress toward measles preelimination--African Region, 2011-2012.

    PubMed

    Masresha, Balcha G; Kaiser, Reinhard; Eshetu, Messeret; Katsande, Reggis; Luce, Richard; Fall, Amadou; Dosseh, Annick R G A; Naouri, Boubker; Byabamazima, Charles R; Perry, Robert; Dabbagh, Alya J; Strebel, Peter; Kretsinger, Katrina; Goodson, James L; Nshimirimana, Deo

    2014-04-01

    In 2008, the 46 member states of the World Health Organization (WHO) African Region (AFR) adopted a measles preelimination goal to reach by the end of 2012 with the following targets: 1) >98% reduction in estimated regional measles mortality compared with 2000, 2) annual measles incidence of fewer than five reported cases per million population nationally, 3) >90% national first dose of measles-containing vaccine (MCV1) coverage and >80% MCV1 coverage in all districts, and 4) >95% MCV coverage in all districts by supplementary immunization activities (SIAs). Surveillance performance objectives were to report two or more cases of nonmeasles febrile rash illness per 100,000 population, one or more suspected measles cases investigated with blood specimens in ≥80% of districts, and 100% completeness of surveillance reporting from all districts. This report updates previous reports and describes progress toward the measles preelimination goal during 2011-2012. In 2012, 13 (28%) member states had >90% MCV1 coverage, and three (7%) reported >90% MCV1 coverage nationally and >80% coverage in all districts. During 2011-2012, four (15%) of 27 SIAs with available information met the target of >95% coverage in all districts. In 2012, 16 of 43 (37%) member states met the incidence target of fewer than five cases per million, and 19 of 43 (44%) met both surveillance performance targets. In 2011, the WHO Regional Committee for AFR established a goal to achieve measles elimination by 2020. To achieve this goal, intensified efforts to identify and close population immunity gaps and improve surveillance quality are needed, as well as committed leadership and ownership of the measles elimination activities and mobilization of adequate resources to complement funding from global partners. PMID:24699765

  12. Assigning African elephant DNA to geographic region of origin: Applications to the ivory trade

    PubMed Central

    Wasser, Samuel K.; Shedlock, Andrew M.; Comstock, Kenine; Ostrander, Elaine A.; Mutayoba, Benezeth; Stephens, Matthew

    2004-01-01

    Resurgence of illicit trade in African elephant ivory is placing the elephant at renewed risk. Regulation of this trade could be vastly improved by the ability to verify the geographic origin of tusks. We address this need by developing a combined genetic and statistical method to determine the origin of poached ivory. Our statistical approach exploits a smoothing method to estimate geographic-specific allele frequencies over the entire African elephants' range for 16 microsatellite loci, using 315 tissue and 84 scat samples from forest (Loxodonta africana cyclotis) and savannah (Loxodonta africana africana) elephants at 28 locations. These geographic-specific allele frequency estimates are used to infer the geographic origin of DNA samples, such as could be obtained from tusks of unknown origin. We demonstrate that our method alleviates several problems associated with standard assignment methods in this context, and the absolute accuracy of our method is high. Continent-wide, 50% of samples were located within 500 km, and 80% within 932 km of their actual place of origin. Accuracy varied by region (median accuracies: West Africa, 135 km; Central Savannah, 286 km; Central Forest, 411 km; South, 535 km; and East, 697 km). In some cases, allele frequencies vary considerably over small geographic regions, making much finer discriminations possible and suggesting that resolution could be further improved by collection of samples from locations not represented in our study. PMID:15459317

  13. Regional view of a Trans-African Drainage System

    PubMed Central

    Abdelkareem, Mohamed; El-Baz, Farouk

    2014-01-01

    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. PMID:26257941

  14. Regional view of a Trans-African Drainage System.

    PubMed

    Abdelkareem, Mohamed; El-Baz, Farouk

    2015-05-01

    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. PMID:26257941

  15. Lassa fever in West African sub-region: an overview.

    PubMed

    Ogbu, O; Ajuluchukwu, E; Uneke, C J

    2007-03-01

    Lassa fever is an acute viral zoonotic illness caused by Lassa virus, an arenavirus known to be responsible for a severe haemorrhagic fever characterised by fever, muscle aches, sore throat, nausea, vomiting and, chest and abdominal pain. The virus exhibits persistent, asymptomatic infection with profuse urinary virus excretion in the ubiquitous rodent vector, Mastomys natalensis. Lassa fever is endemic in West Africa and has been reported from Sierra Leone, Guinea, Liberia, and Nigeria. Some studies indicate that 300,000 to 500,000 cases of Lassa fever and 5000 deaths occur yearly across West Africa. Studies reported in English, that investigated Lassa fever with reference to West Africa were identified using the Medline Entrez-PubMed search and were used for this review. The scarcity of resources available for health care delivery system and the political instability that characterise the West African countries would continue to impede efforts for the control of Lassa fever in the sub-region. There is need for adequate training of health care workers regarding diagnostics, intensive care of patients under isolation, contact tracing, adequate precautionary measures in handling infectious laboratory specimens, control of the vector as well as care and disposal of infectious waste. PMID:17378212

  16. African-American Materials Project Experiment in Regional Cooperation. Final Report.

    ERIC Educational Resources Information Center

    Hall, Carol J.

    The African-American Materials Project was a three year venture in bibliographic control of African-American materials. It was a regional project, designed to locate and describe materials in six Southern states. The project was divided into three periods. Phase I was devoted to locating existing collections through the use of a questionnaire,…

  17. Ethnobotanical knowledge on botanical repellents employed in the African region against mosquito vectors - A review.

    PubMed

    Pavela, Roman; Benelli, Giovanni

    2016-08-01

    Mosquitoes (Diptera: Culicidae) represent a huge threat for millions of humans and animals worldwide, since they act as vectors for important parasites and pathogens, including malaria, filariasis and important arboviruses, such as dengue, West Nile and Zika virus. No vaccines or other specific treatments are available against the arboviruses transmitted by mosquitoes, and avoidance of mosquito bites remains the best strategy. African regions are usually hit most whose inhabitants are poor, and the use of repellent plants is the only efficient protection against vectors they have. Ethnobotanical knowledge of such plants and their use is usually passed on orally from one generation to another. However, it is also important to preserve this information in a written form, as well. Ethnobotanical research projects carried out in the regions of today's Ethiopia, South Africa, Nigeria, Kenya, and Tanzania indicate that the native inhabitants of the African study regions traditionally use 64 plant species, belonging to 30 families. Aromatic plants (i.e., Citrus spp., Eucalyptus spp., Lantana camara, Ocimum spp. and Lippia javanica) the most commonly used in all the study regions. Native people know three major methods of using repellent plants: (i) production of repellent smoke from burning plants, (ii) hanging plants inside the house or sprinkling leaves on the floor, (iii) the use of plant oils, juices from crushed fresh parts of the plants, or various prepared extracts applied on uncovered body parts. Overall, this review covers studies conducted only in a limited part of the African continent, highlighting the importance to undertake further research efforts to preserve the unique knowledge and traditions of the native tribes. PMID:27260568

  18. Association studies in QTL regions linked to bovine trypanotolerance in a West African crossbred population.

    PubMed

    Dayo, G K; Gautier, M; Berthier, D; Poivey, J P; Sidibe, I; Bengaly, Z; Eggen, A; Boichard, D; Thevenon, S

    2012-04-01

    African animal trypanosomosis is a parasitic blood disease transmitted by tsetse flies and is widespread in sub-Saharan Africa. West African taurine breeds have the ability, known as trypanotolerance, to limit parasitaemia and anaemia and remain productive in enzootic areas. Several quantitative trait loci (QTL) underlying traits related to trypanotolerance have been identified in an experimentally infected F(2) population resulting from a cross between taurine and zebu cattle. Although this information is highly valuable, the QTL remain to be confirmed in populations subjected to natural conditions of infection, and the corresponding regions need to be refined. In our study, 360 West African cattle were phenotyped for the packed cell volume control under natural conditions of infection in south-western Burkina Faso. Phenotypes were assessed by analysing data from previous cattle monitored over 2 years in an area enzootic for trypanosomosis. We further genotyped for 64 microsatellite markers mapping within four previously reported QTL on BTA02, BTA04, BTA07 and BTA13. These data enabled us to estimate the heritability of the phenotype using the kinship matrix between individuals computed from genotyping data. Thus, depending on the estimators considered and the method used, the heritability of anaemia control ranged from 0.09 to 0.22. Finally, an analysis of association identified an allele of the MNB42 marker on BTA04 as being strongly associated with anaemia control, and a candidate gene, INHBA, as being close to that marker. PMID:22404348

  19. Status of national health research systems in ten countries of the WHO African Region

    PubMed Central

    Kirigia, Joses M; Wambebe, Charles

    2006-01-01

    Background The World Health Organization (WHO) Regional Committee for Africa, in 1998, passed a resolution (AFR/RC48/R4) which urged its Member States in the Region to develop national research policies and strategies and to build national health research capacities, particularly through resource allocation, training of senior officials, strengthening of research institutions and establishment of coordination mechanisms. The purpose of this study was to take stock of some aspects of national resources for health research in the countries of the Region; identify current constraints facing national health research systems; and propose the way forward. Methods A questionnaire was prepared and sent by pouch to all the 46 Member States in the WHO African Region through the WHO Country Representatives for facilitation and follow up. The health research focal person in each of the countries Ministry of Health (in consultation with other relevant health research bodies in the country) bore the responsibility for completing the questionnaire. The data were entered and analysed in Excel spreadsheet. Results The key findings were as follows: the response rate was 21.7% (10/46); three countries had a health research policy; one country reported that it had a law relating to health research; two countries had a strategic health research plan; three countries reported that they had a functional national health research system (NHRS); two countries confirmed the existence of a functional national health research management forum (NHRMF); six countries had a functional ethical review committee (ERC); five countries had a scientific review committee (SRC); five countries reported the existence of health institutions with institutional review committees (IRC); two countries had a health research programme; and three countries had a national health research institute (NHRI) and a faculty of health sciences in the national university that conducted health research. Four out of the ten

  20. Multiple Origins and Regional Dispersal of Resistant dhps in African Plasmodium falciparum Malaria

    PubMed Central

    Pearce, Richard J.; Pota, Hirva; Evehe, Marie-Solange B.; Bâ, El-Hadj; Mombo-Ngoma, Ghyslain; Malisa, Allen L.; Ord, Rosalynn; Inojosa, Walter; Matondo, Alexandre; Diallo, Diadier A.; Mbacham, Wilfred; van den Broek, Ingrid V.; Swarthout, Todd D.; Getachew, Asefaw; Dejene, Seyoum; Grobusch, Martin P.; Njie, Fanta; Kweku, Margaret; Owusu-Agyei, Seth; Chandramohan, Daniel; Bonnet, Maryline; Guthmann, Jean-Paul; Clarke, Sian; Barnes, Karen I.; Streat, Elizabeth; Katokele, Stark T.; Uusiku, Petrina; Agboghoroma, Chris O.; Elegba, Olufunmilayo Y.; Cissé, Badara; A-Elbasit, Ishraga E.; Giha, Hayder A.; Kachur, S. Patrick; Lynch, Caroline; Rwakimari, John B.; Chanda, Pascalina; Hawela, Moonga; Naidoo, Inbarani; Roper, Cally

    2009-01-01

    Background Although the molecular basis of resistance to a number of common antimalarial drugs is well known, a geographic description of the emergence and dispersal of resistance mutations across Africa has not been attempted. To that end we have characterised the evolutionary origins of antifolate resistance mutations in the dihydropteroate synthase (dhps) gene and mapped their contemporary distribution. Methods and Findings We used microsatellite polymorphism flanking the dhps gene to determine which resistance alleles shared common ancestry and found five major lineages each of which had a unique geographical distribution. The extent to which allelic lineages were shared among 20 African Plasmodium falciparum populations revealed five major geographical groupings. Resistance lineages were common to all sites within these regions. The most marked differentiation was between east and west African P. falciparum, in which resistance alleles were not only of different ancestry but also carried different resistance mutations. Conclusions Resistant dhps has emerged independently in multiple sites in Africa during the past 10–20 years. Our data show the molecular basis of resistance differs between east and west Africa, which is likely to translate into differing antifolate sensitivity. We have also demonstrated that the dispersal patterns of resistance lineages give unique insights into recent parasite migration patterns. PMID:19365539

  1. Estimation of foF2 from GPS TEC over the South African region

    NASA Astrophysics Data System (ADS)

    Ssessanga, Nicholas; Mckinnell, Lee-Anne; Bosco Habarulema, John

    2014-05-01

    This paper describes a statistical method (TEC2F2) of estimating the critical frequency (foF2) values from Global Positioning System (GPS) Vertical Total Electron Content (VTEC). The method has been developed over the South African region using the available ionosonde stations; Grahamstown (33.2°S, 26.3°E), Hermanus (34.4°S, 19.2°E), Louisvale (28.5°S, 21.2°E) and Madimbo (22.4°S, 30.9°E), and nearby GPS receiver stations. The analysis of the results showed the TEC2F2 method to be more accurate at estimating the foF2 parameter over South Africa than the most commonly used International Reference Ionosphere (IRI-2012) model. On average, the TEC2F2 improves foF2 estimation by 15% (2006-2012) over the IRI-2012 model. The application of this method over the rest of Africa is proposed in order to more accurately estimate the foF2 parameter in regions where ionosondes do not exist. This is a pioneering new method that allows for the utilisation of additional resources to close the gap in ionospheric mapping over Africa.

  2. Bacterial diversity in different regions of gastrointestinal tract of Giant African Snail (Achatina fulica)

    PubMed Central

    Pawar, Kiran D; Banskar, Sunil; Rane, Shailendra D; Charan, Shakti S; Kulkarni, Girish J; Sawant, Shailesh S; Ghate, Hemant V; Patole, Milind S; Shouche, Yogesh S

    2012-01-01

    The gastrointestinal (GI) tract of invasive land snail Achatina fulica is known to harbor metabolically active bacterial communities. In this study, we assessed the bacterial diversity in the different regions of GI tract of Giant African snail, A. fulica by culture-independent and culture-dependent methods. Five 16S rRNA gene libraries from different regions of GI tract of active snails indicated that sequences affiliated to phylum γ-Proteobacteria dominated the esophagus, crop, intestine, and rectum libraries, whereas sequences affiliated to Tenericutes dominated the stomach library. On phylogenetic analysis, 30, 27, 9, 27, and 25 operational taxonomic units (OTUs) from esophagus, crop, stomach, intestine, and rectum libraries were identified, respectively. Estimations of the total bacterial diversity covered along with environmental cluster analysis showed highest bacterial diversity in the esophagus and lowest in the stomach. Thirty-three distinct bacterial isolates were obtained, which belonged to 12 genera of two major bacterial phyla namely γ-Proteobacteria and Firmicutes. Among these, Lactococcus lactis and Kurthia gibsonii were the dominant bacteria present in all GI tract regions. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated significant differences in bacterial load in different GI tract regions of active and estivating snails. The difference in the bacterial load between the intestines of active and estivating snail was maximum. Principal component analysis (PCA) of terminal restriction fragment length polymorphism suggested that bacterial community structure changes only in intestine when snail enters estivation state. PMID:23233413

  3. Region of birth, migration and homicide rates of African Americans.

    PubMed

    Greenberg, M; Schneider, D

    1997-08-01

    A study was made of all homicide deaths among black Americans during the period 1979-1991 in order to test two competing hypotheses about region of birth and region of death. One hypothesis was that Southern-born blacks had the highest homicide rates in every region of the US. The competing hypothesis was that blacks who did not migrate out of their region of birth had the highest homicide rates. We found that Southern-born blacks had the highest homicide rates among the population 35+ years old in the Northeast, Midwest, South and West. Yet non-migrants (region-born population) had higher rates than their Southern-born counterparts among the population 15-34 years old. Long distance migrants who were born in the Northeast, West or were foreign-born had the lowest homicide rates, by far. The distressing implications of these findings for public health efforts to prevent violent death are discussed. PMID:9426984

  4. The Southern African Regional Science Initiative (SAFARI 2000). Dry-Season Campaign: An Overview

    NASA Technical Reports Server (NTRS)

    Swap, R. J.; Annegarn, H. J.; Suttles, J. T.; Haywood, J.; Hely, C.; Hobbs, P. V.; Holben, B. N.; Ji, J.; King, M. D.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The Southern African Regional Science Initiative (SAFARI 2000) is an international science project investigating the southern African earth-atmosphere-human system. The experiment was conducted over a two-year period March 1999 - March 2001. The dry season field campaign (August-Steptember 2000) was the most intensive activity and involving over 200 scientists from 18 different nations. The main objectives of this campaign were to characterize and quantify the biogenic, pyrogenic and anthropogenic aerosol and trace gas emissions and their transport and transformations in the atmosphere and to validate the NASA Earth Observing System (EOS) satellite Terra within a scientific context. Five aircraft, namely two South African Weather Service aircraft, University of Washington CV-580, the UK Meteorological Office C-130 and the NASA ER-2, with different altitude capabilities, participated in the campaign. Additional airborne sampling of southern African air masses that had moved downwind of the subcontinent was conducted by the CSIRO over Australia. Multiple observations were taken in various sectors for a variety of synoptic conditions. Flight missions were designed to maximize synchronous over-flights of the NASA TERRA satellite platform, above regional ground validation and science targets. Numerous smaller-scale ground validation activities took place throughout the region during the campaign period.

  5. Ionospheric Current System over the African Region and East Asian Region as Observed by MAGDAS Stations (Invited)

    NASA Astrophysics Data System (ADS)

    Yumoto, K.; Yamazaki, Y.; Rabiu, A.; Mahrous, A.; Meloni, A.; Baki, P.; Makundi, N.; Afullo, T.; McKinnell, L. A.; Badi, K.; Mweene, H.; Macamo, A.; Abe, S.; Ikeda, A.; Fujimoto, A.; Tokunaga, T.; Fujita, Y.; Matsuyama, K.

    2010-12-01

    The MAGnetic Data Acquisition System (MAGDAS) is the global real-time magnetometer array operated by the Space Environment Research Center (SERC), Kyushu University. This array includes two latitudinal chains; one is along the 210-degree magnetic meridian (210MM in the East Asian region since 2005). And the other is along the 96-degree magnetic meridian (96MM in the African region since 2008). The objective of this paper is to describe the longitudinal difference of the ionospheric current system using the MAGDAS data observed along the two different longitudinal chains. We analyzed the data recorded during the latest solar minimum (2008-2010) when the Sun was abnormally quiet. Our analysis shows some important characteristics of the equivalent current system over the African region: (1) From May to September, the current vortex in the Northern Hemisphere penetrates into the Southern Hemisphere in the morning hours as deeply as 40-degree at the dip latitude. (2) During this period, the strength of the equatorial electrojet becomes weaker than during other periods. These features are seen only in the current system over the African region. In the presentation, we will explain more details of the longitudinal difference of the ionospheric current system.

  6. African Traditional Education: A Method of Dissseminating Cultural Values.

    ERIC Educational Resources Information Center

    Boateng, Felix

    1983-01-01

    Describes how the philosophical foundations of traditional African education, including oral literature, secret societies and other religious practices, served as a vehicle for intergenerational communication. Warns educational planners in contemporary Africa that a rejection of African heritage will create confusion, loss of identity, and a break…

  7. Global diversity and genetic contributions of chicken populations from African, Asian and European regions.

    PubMed

    Lyimo, C M; Weigend, A; Msoffe, P L; Eding, H; Simianer, H; Weigend, S

    2014-12-01

    Genetic diversity and population structure of 113 chicken populations from Africa, Asia and Europe were studied using 29 microsatellite markers. Among these, three populations of wild chickens and nine commercial purebreds were used as reference populations for comparison. Compared to commercial lines and chickens sampled from the European region, high mean numbers of alleles and a high degree of heterozygosity were found in Asian and African chickens as well as in Red Junglefowl. Population differentiation (FST ) was higher among European breeds and commercial lines than among African, Asian and Red Junglefowl populations. Neighbour-Net genetic clustering and structure analysis revealed two main groups of Asian and north-west European breeds, whereas African populations overlap with other breeds from Eastern Europe and the Mediterranean region. Broilers and brown egg layers were situated between the Asian and north-west European clusters. structure analysis confirmed a lower degree of population stratification in African and Asian chickens than in European breeds. High genetic differentiation and low genetic contributions to global diversity have been observed for single European breeds. Populations with low genetic variability have also shown a low genetic contribution to a core set of diversity in attaining maximum genetic variation present from the total populations. This may indicate that conservation measures in Europe should pay special attention to preserving as many single chicken breeds as possible to maintain maximum genetic diversity given that higher genetic variations come from differentiation between breeds. PMID:25315897

  8. African Regional Seminar for Advanced Training In Systematic Curriculum Development and Evaluation. (Achimota, Ghana, 14 July--15 August 1975). Report.

    ERIC Educational Resources Information Center

    Swedish International Development Authority (SIDA).

    This report summarizes the African Regional Seminar for Advanced Training in Systematic Curriculum Development and Evaluation that was held at Achimota, Ghana, July 14-August 15 1975. Attending the seminar were 67 participants from 12 African countries, including Cameroon, Gambia, Ghana, Kenya, Liberia, Malawi, Nigeria, Sierra Leone, Swaziland,…

  9. Increase in African dust flux at the onset of commercial agriculture in the Sahel region.

    PubMed

    Mulitza, Stefan; Heslop, David; Pittauerova, Daniela; Fischer, Helmut W; Meyer, Inka; Stuut, Jan-Berend; Zabel, Matthias; Mollenhauer, Gesine; Collins, James A; Kuhnert, Henning; Schulz, Michael

    2010-07-01

    The Sahara Desert is the largest source of mineral dust in the world. Emissions of African dust increased sharply in the early 1970s (ref. 2), a change that has been attributed mainly to drought in the Sahara/Sahel region caused by changes in the global distribution of sea surface temperature. The human contribution to land degradation and dust mobilization in this region remains poorly understood, owing to the paucity of data that would allow the identification of long-term trends in desertification. Direct measurements of airborne African dust concentrations only became available in the mid-1960s from a station on Barbados and subsequently from satellite imagery since the late 1970s: they do not cover the onset of commercial agriculture in the Sahel region approximately 170 years ago. Here we construct a 3,200-year record of dust deposition off northwest Africa by investigating the chemistry and grain-size distribution of terrigenous sediments deposited at a marine site located directly under the West African dust plume. With the help of our dust record and a proxy record for West African precipitation we find that, on the century scale, dust deposition is related to precipitation in tropical West Africa until the seventeenth century. At the beginning of the nineteenth century, a sharp increase in dust deposition parallels the advent of commercial agriculture in the Sahel region. Our findings suggest that human-induced dust emissions from the Sahel region have contributed to the atmospheric dust load for about 200 years. PMID:20613839

  10. Regional Climate Modeling of West African Summer Monsoon Climate: Impact of Historical Boundary Forcing

    NASA Astrophysics Data System (ADS)

    Kebe, I.

    2015-12-01

    In this paper, we analyze and intercompare the performance of an ensemble of three Regional Climate Models (RCMs) driven by three set of Global Climate Models (GCMs), in reproducing seasonal mean climatologies with their annual cycle and the key features of West African summer monsoon over 20 years period (1985-2004) during the present day. The results show that errors in lateral boundary conditions from the GCM members, have an unexpected way on the skill of the RCMs in reproducing regional climate features such as the West African Monsoon features and the annual cycle of precipitation and temperature in terms of outperforming the GCM simulation. It also shows the occurrence of the West African Monsoon jump, the intensification and northward shift of the Saharan Heat Low (SHL) as expressed in some RCMs than the GCMs. Most RCMs also capture the mean annual cycle of precipitation and temperature, including, single and double-peaked during the summer months, in terms of events and amplitude. In a series of RCMs and GCMs experiments between the Sahara region and equatorial Africa, the presence of strong positive meridional temperature gradients at the surface and a strong meridional gradients in the potential temperatures near the surface are obvious, indicating the region of strong vertical shear development enough to establish easterly flow such as the African easterly jet. In addition, the isentropic potential vorticity (IPV) gradient decreases northward in the lower troposphere across northern Africa, with the maximum reversal on the 315-K surface. The region with negative IPV gradient favors the potential instability which has been associated with the growth of easterly waves.

  11. Effects of maternal mortality on gross domestic product (GDP) in the WHO African region.

    PubMed

    Kirigia, Joses M; Oluwole, Doyin; Mwabu, Germano M; Gatwiri, Doris; Kainyu, Lenity H

    2006-01-01

    WHO African region has got the highest maternal mortality rate compared to the other five regions. Maternal mortality is hypothesized to have significantly negative effect on the gross domestic product (GDP). The objective of the current study was to estimate the loss in GDP attributable to maternal mortality in the WHO African Region. The burden of maternal mortality on GDP was estimated using a double-log econometric model. The analysis is based on cross-sectional data for 45 of the 46 Member States in the WHO African Region. Data were obtained from UNDP and the World Bank publications. All the explanatory variables included in the double-log model were found to have statistically significant effect on per capita gross domestic product (GDP) at 5 % level in a t-distribution test. The coefficients for land (D), capital (K), educational enrollment (EN) and exports (X) had a positive sign; while labor (L), imports (M) and maternal mortality rate (MMR) were found to impact negatively on GDP. Maternal mortality of a single person was found to reduce per capita GDP by US $ 0.36 per year. The study has demonstrated that maternal mortality has a statistically significant negative effect on GDP. Thus, as policy-makers strive to increase GDP through land reform programs, capital investments, export promotion and increase in educational enrollment, they should always remember that investment in maternal mortality-reducing interventions promises significant economic returns. PMID:17348747

  12. REGIONAL RESEARCH, METHODS, AND SUPPORT

    EPA Science Inventory

    The Human Exposure and Atmospheric Sciences Division (HEASD) has several collaborations with regional partners through the Regional Science Program (RSP) managed by ORD's Office of Science Policy (OSP). These projects resulted from common interests outlined in the Regional Appli...

  13. Investigation of TEC variations over the magnetic equatorial and equatorial anomaly regions of the African sector

    NASA Astrophysics Data System (ADS)

    Oryema, B.; Jurua, E.; D'ujanga, F. M.; Ssebiyonga, N.

    2015-11-01

    This paper presents the annual, seasonal and diurnal variations in ionospheric TEC along the African equatorial region. The study also investigated the effects of a geomagnetic storm on ionospheric TEC values. Dual-frequency GPS derived TEC data obtained from four stations within the African equatorial region for the high solar activity year 2012 were used in this study. Annual variations showed TEC having two peaks in the equinoctial months, while minima values were observed in the summer and winter solstices. The diurnal pattern showed a pre-dawn minimum, a steady increase from about sunrise to an afternoon maximum and then a gradual fall after sunset to attain a minimum just before sunrise. Nighttime enhancements of TEC were observed mostly in the equinoctial months. There was comparably higher percentage TEC variability during nighttime than daytime and highest during equinoxes, moderate in winter and least during summer solstice. TEC was observed to exhibit a good correlation with geomagnetic storm indices.

  14. Southern African Phanerozoic marine invertebrates: Biogeography, pal˦oecology, climatology and comments on adjacent regions

    NASA Astrophysics Data System (ADS)

    Boucot, A. J.

    The Palaeozoic marine invertebrate fossil record in southern Africa is characterised by extensive data for the Early and Middle Devonian but extremely limited or absent for other Palaeozoic Periods. The Mesozoic Era is lacking in marine invertebrate fossils for the Triassic, Late Jurassic, and Cretaceous. For the Cenozoic Era there is limited marine megafossil information. Overall, in benthic, cool waters, Palaeozoic, marine megafossils from southern Africa appear to represent relatively low diversity communities, when compared to ecologically comparable warm water environments elsewhere. However, the marine benthic Cretaceous and Cenozoic faunas of southwestern Africa are typically diverse warm water types, until the later Miocene when cool waters again prevailed. The Benguela Current clearly influenced lower diversity faunas. Climatically, it can be inferred from the marine megabenthic pal˦ontological evidence, thatwarm conditions were present from Early Cambrian until mid-Ordovician times, followed by a much cooler climate that persisted well into the Middle Devonian. The Late Palaeozoic evidence thus indicates cool to cold conditions. In contrast, the Late Permian fossils are consistent with warmer conditions, continuing through Late Jurassic and Cretaceous times along the East African and West African coasts, until the Late Miocene. Within the Gondwanan framework, a Central African region can be envisaged that was subject to non-marine conditions during the entire Phanerozoic Eon. Peripheral to this central African region were marine environments of various ages. The geological history of these peripheral regions was fairly unique. Some features in southern Africa are similar of those found in the Paraná Basin and the Falkland Islands. Most of North Africa from central Senegal to Libya contains a Phanerozoic marine cover extending from the Early Cambrian through to the Carboniferous, characterised by warm water faunas, except for the Ordovician which yields

  15. Regional health governance: A suggested agenda for Southern African health diplomacy

    PubMed Central

    Penfold, Erica Dale; Fourie, Pieter

    2015-01-01

    Regional organisations can effectively promote regional health diplomacy and governance through engagement with regional social policy. Regional bodies make decisions about health challenges in the region, for example, the Union of South American Nations (UNASUR) and the World Health Organisation South East Asia Regional Office (WHO-SEARO). The Southern African Development Community (SADC) has a limited health presence as a regional organisation and diplomatic partner in health governance. This article identifies how SADC facilitates and coordinates health policy, arguing that SADC has the potential to promote regional health diplomacy and governance through engagement with regional social policy. The article identifies the role of global health diplomacy and niche diplomacy in health governance. The role of SADC as a regional organisation and the way it functions is then explained, focusing on how SADC engages with health issues in the region. Recommendations are made as to how SADC can play a more decisive role as a regional organisation to implement South–South management of the regional social policy, health governance and health diplomacy agenda. PMID:26635498

  16. Can countries of the WHO African Region wean themselves off donor funding for health?

    PubMed

    Kirigia, Joses Muthuri; Diarra-Nama, Alimata J

    2008-11-01

    More than 20% of total health expenditure in 48% of the 46 countries in the WHO African Region is provided by external sources. Issues surrounding aid effectiveness suggest that these countries ought to implement strategies for weaning off aid dependency. This paper broaches the following question: what are some of the strategies that countries of the region can employ to wean off donor funding for health? Five strategies are discussed: reduction in economic inefficiencies; reprioritizing public expenditures; raising additional tax revenues; increased private sector involvement in health development; and fighting corruption. PMID:19030696

  17. The Southern African Regional Science Initiative (SAFARI 2000): Overview of the Dry Season Field Campaign

    NASA Technical Reports Server (NTRS)

    Swap, R. J.; Annegarn, H. J.; Suttles, J. T.; Haywood, J.; Helmlinger, M. C.; Hely, C.; Hobbs, P. V.; Holben, B. N.; Ji, J.; King, M. D.

    2002-01-01

    The Southern African Regional Science Initiative (SAFARI 2000) is an international project investigating the earth atmosphere -human system in southern Africa. The programme was conducted over a two year period from March 1999 to March 2001. The dry season field campaign (August-September 2000) was the most intensive activity involved over 200 scientist from eighteen countries. The main objectives were to characterize and quantify biogenic, pyrogenic and anthropogenic aerosol and trace gas emissions and their transport and transformations in the atmosphere and to validate NASA's Earth Observing System's Satellite Terra within a scientific context. Five aircraft-- two South African Weather Service Aeorcommanders, the University of Washington's CV-880, the U.K. Meteorological Office's C-130, and NASA's ER-2 --with different altitude capabilities, participated in the campaign. Additional airborne sampling of southern African air masses, that had moved downwind of the subcontinent, was conducted by the CSIRO over Australia. Multiple Observations were made in various geographical sections under different synoptic conditions. Airborne missions were designed to optimize the value of synchronous over-flights of the Terra Satellite platform, above regional ground validation and science targets. Numerous smaller scale ground validation activities took place throughout the subcontinent during the campaign period.

  18. Bias reduction in decadal predictions of West African monsoon rainfall using regional climate models

    NASA Astrophysics Data System (ADS)

    Paxian, A.; Sein, D.; Panitz, H.-J.; Warscher, M.; Breil, M.; Engel, T.; Tödter, J.; Krause, A.; Cabos Narvaez, W. D.; Fink, A. H.; Ahrens, B.; Kunstmann, H.; Jacob, D.; Paeth, H.

    2016-02-01

    The West African monsoon rainfall is essential for regional food production, and decadal predictions are necessary for policy makers and farmers. However, predictions with global climate models reveal precipitation biases. This study addresses the hypotheses that global prediction biases can be reduced by dynamical downscaling with a multimodel ensemble of three regional climate models (RCMs), a RCM coupled to a global ocean model and a RCM applying more realistic soil initialization and boundary conditions, i.e., aerosols, sea surface temperatures (SSTs), vegetation, and land cover. Numerous RCM predictions have been performed with REMO, COSMO-CLM (CCLM), and Weather Research and Forecasting (WRF) in various versions and for different decades. Global predictions reveal typical positive and negative biases over the Guinea Coast and the Sahel, respectively, related to a southward shifted Intertropical Convergence Zone (ITCZ) and a positive tropical Atlantic SST bias. These rainfall biases are reduced by some regional predictions in the Sahel but aggravated by all RCMs over the Guinea Coast, resulting from the inherited SST bias, increased westerlies and evaporation over the tropical Atlantic and shifted African easterly waves. The coupled regional predictions simulate high-resolution atmosphere-ocean interactions strongly improving the SST bias, the ITCZ shift and the Guinea Coast and Central Sahel precipitation biases. Some added values in rainfall bias are found for more realistic SST and land cover boundary conditions over the Guinea Coast and improved vegetation in the Central Sahel. Thus, the ability of RCMs and improved boundary conditions to reduce rainfall biases for climate impact research depends on the considered West African region.

  19. African Anthropogenic Combustion Emissions: Estimate of Regional Mortality Attributable to Fine Particle Concentrations in 2030

    NASA Astrophysics Data System (ADS)

    Liousse, C.; Roblou, L.; Assamoi, E.; Criqui, P.; Galy-Lacaux, C.; Rosset, R.

    2014-12-01

    Fossil fuel (traffic, industries) and biofuel (domestic fires) emissions of gases and particles in Africa are expected to significantly increase in the near future, particularly due to rapid growth of African cities and megacities. In this study, we will present the most recent developments of African combustion emission inventories, including African specificities. Indeed, a regional fossil fuel and biofuel inventory for gases and particulates described in Liousse et al. (2014) has been developed for Africa at a resolution of 0.25° x 0.25° for the years 2005 and 2030. For 2005, the original database of Junker and Liousse (2008) was used after modification for updated regional fuel consumption and emission factors. Two prospective inventories for 2030 are derived based on Prospective Outlook on Long-term Energy Systems (POLES) model (Criqui, 2001). The first is a reference scenario (2030ref) with no emission controls and the second is for a "clean" scenario (2030ccc*) including Kyoto policy and African specific emission control. This inventory predicts very large increases of pollutant emissions in 2030 (e.g. contributing to 50% of global anthropogenic organic particles), if no emission regulations are implemented. These inventories have been introduced in RegCM4 model. In this paper we will focus on aerosol modelled concentrations in 2005, 2030ref and 2030ccc*. Spatial distribution of aerosol concentrations will be presented with a zoom at a few urban and rural sites. Finally mortality rates (respiratory, cardiovascular) caused by anthropogenic PM2.5 increase from 2005 to 2030, calculated following Lelieveld et al. (2013), will be shown for each scenarios. To conclude, this paper will discuss the effectiveness of scenarios to reduce emissions, aerosol concentrations and mortality rates, underlining the need for further measurements scheduled in the frame of the new DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions) program.

  20. Malaria control in the African Region: perceptions and viewspoints on proceedings of the Africa Leaders Malaria Alliance (ALMA)

    PubMed Central

    2011-01-01

    Background In 2009 a total of 153,408 malaria deaths were reported in Africa. Eleven countries showed a reduction of more than 50% in either confirmed malaria cases or malaria admissions and deaths in recent years. However, many African countries are not on track to achieve the malaria component of the Millennium Development Goal (MDG) 6. The African Leaders Malaria Alliance (ALMA) working session at the 15th African Union Summit discussed the bottlenecks to achieving MDG 6 (specifically halting and beginning to reverse the incidence of malaria by 2015), success factors, and what countries needed to do to accelerate achievement of the MDG. The purpose of this article is to reflect on the proceedings of the ALMA working session. Methods Working methods of the session included speeches and statements by invited speakers and high-level panel discussions. Discussion The main bottlenecks identified related to the capacity of the health systems to deliver quality care and accessibility issues; need for strong, decentralized malaria-control programmes with linkages with other health and development sectors, the civil society and private sector entities; benefits of co-implementation of malaria control programmes with child survival or other public health interventions; systematic application of integrated promotive, preventive, diagnostic and case management interventions with full community participation; adapting approaches to local political, socio-cultural and administrative environments. The following prerequisites for success were identified: a clear vision and effective leadership of national malaria control programmes; high level political commitment to ensure adequate capacity in expertise, skill mix and number of managers, technicians and service providers; national ownership, intersectoral collaboration and accountability, as well as strong civil society and private sector involvement; functional epidemiological surveillance systems; and levering of African

  1. Marine protected areas in the eastern African Region: how successful are they?

    PubMed

    Francis, Julius; Nilsson, Agneta; Waruinge, Dixon

    2002-12-01

    This article reviews the governance and management of Marine Protected Areas (MPAs), and the coral reefs they contain, in the eastern African Region. This includes the Comoros, Kenya, Madagascar, Mauritius, Mozambique, Tanzania, and the Seychelles. Three generations or categories of MPAs are distinguished: i) small areas for protection of a single species or unique marine habitat; iii) large multiple use MPAs designed for coastal development as well as biodiversity protection; and iii) MPAs managed by a nongovernmental organization (NGO) or the private sector. Each of these MPA types is examined according to the policies, legislation, and management systems they entail as well as the economic and community situation they operate within. The paper also provides a review of some eastern African MPAs in terms of their size and location, the type of MPA, zonation schemes, and financial status. The successes of the different types of MPAs are discussed based on specific indicators, such as changes in biodiversity, infrastructure, compliance to regulations and the level of involvement of primary stakeholders in the management. From the review it is clear that a fourth generation of MPAs may be forthcoming; community-based MPAs. Although lack of data makes it difficult to assess the effectiveness of these different categories of MPAs, it is clear that no MPA can succeed without support of the local communities. Generally, the results of the analysis are promising for MPAs, however a lack of data is hampering a deeper analysis. The major issues facing MPAs in the region are highlighted, as well as some regional initiatives striving to address these issues. A number of recommendations are made, aiming to strengthen the establishment and management of MPAs in the eastern African region. PMID:12572815

  2. Phylogenetic relations of humans and African apes from DNA sequences in the Psi eta-globin region

    SciTech Connect

    Miyamoto, M.M.; Slightom, J.L.; Goodman, M.

    1987-10-16

    Sequences from the upstream and downstream flanking DNA regions of the Psi eta-globin locus in Pan troglodytes (common chimpanzee), Gorilla gorilla (gorilla), and Pongo pygmaeus (orangutan, the closest living relative to Homo, Pan, and Gorilla) provided further data for evaluating the phylogenetic relations of humans and African apes. These newly sequenced orthologs (an additional 4.9 kilobase pairs (kbp) for each species) were combined with published Psi eta-gene sequences and then compared to the same orthologous stretch (a continuous 7.1-kbp region) available for humans. Phylogenetic analysis of these nucleotide sequences by the parsimony method indicated (i) that human and chimpanzee are more closely related to each other than either is to gorilla and (ii) that the slowdown in the rate of sequence evolution evident in higher primates is especially pronounced in humans. These results indicate that features unique to African apes (but not to humans) are primitive and that even local molecular clocks should be applied with caution.

  3. Regional distribution models with lack of proximate predictors: Africanized honeybees expanding north

    USGS Publications Warehouse

    Jarnevich, Catherine S.; Esaias, Wayne E.; Ma, Peter L.A.; Morisette, Jeffery T.; Nickeson, Jaime E.; Stohlgren, Thomas J.; Holcombe, Tracy R.; Nightingale, Joanne M.; Wolfe, Robert E.; Tan, Bin

    2014-01-01

    Species distribution models have often been hampered by poor local species data, reliance on coarse-scale climate predictors and the assumption that species–environment relationships, even with non-proximate predictors, are consistent across geographical space. Yet locally accurate maps of invasive species, such as the Africanized honeybee (AHB) in North America, are needed to support conservation efforts. Current AHB range maps are relatively coarse and are inconsistent with observed data. Our aim was to improve distribution maps using more proximate predictors (phenology) and using regional models rather than one across the entire range of interest to explore potential differences in drivers.

  4. Regional Distribution Models with Lack of Proximate Predictors: Africanized Honeybees Expanding North

    NASA Technical Reports Server (NTRS)

    Jarnevich, Catherine S.; Esaias, Wayne E.; Ma, Peter L. A.; Morisette, Jeffery T.; Nickeson, Jaime E.; Stohlgren, Thomas J.; Holcombe, Tracy R.; Nightingale, Joanne M.; Wolfe, Robert E.; Tan, Bin

    2014-01-01

    Species distribution models have often been hampered by poor local species data, reliance on coarse-scale climate predictors and the assumption that species-environment relationships, even with non-proximate predictors, are consistent across geographical space. Yet locally accurate maps of invasive species, such as the Africanized honeybee (AHB) in North America, are needed to support conservation efforts. Current AHB range maps are relatively coarse and are inconsistent with observed data. Our aim was to improve distribution maps using more proximate predictors (phenology) and using regional models rather than one across the entire range of interest to explore potential differences in drivers.

  5. Trends of ionospheric irregularities over African low latitude region during quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Mungufeni, Patrick; Habarulema, John Bosco; Jurua, Edward

    2016-02-01

    The occurrence patterns of ionospheric irregularities during quiet geomagnetic conditions over the African low latitude region were analysed. GNSS-derived Total Electron Content of the ionosphere data during the period 2001-2012 were used. The data were obtained from Libreville, Gabon (0.35°N, 9.68°E, geographic, 8.05°S, magnetic), Mbarara, Uganda (0.60°S, 30.74°E, geographic, 10.22°S, magnetic), and Malindi, Kenya (2.99°S, 40.19°E, geographic, 12.42°S, magnetic). The rate of change of total electron content index greater than 0.5 TECU/Min were considered as severe ionospheric irregularities. For most of the time, the strength of ionospheric irregularities in March equinox were greater than those during September equinox over East Africa and an opposite observation was made over West Africa. These asymmetries might be due to the direction of the meridional winds during equinoxes over the different stations. Severity of ionospheric irregularity reduced from west towards the east. This might have been related to the decreasing geomagnetic field strength from east towards the west. This is the first study that reveals the equinoctial asymmetry is different in the West and East African sectors. Moreover, the importance of this study lies in the fact that it has used extensive data to examine the isolated and un-explained earlier observations of equinoctial asymmetry and longitudinal variation of ionospheric irregularities over the African low latitude region.

  6. Relative rates of evolution in the coding and control regions of African mtDNAs.

    PubMed

    Howell, Neil; Elson, Joanna L; Howell, Corinna; Turnbull, Douglass M

    2007-10-01

    Reduced median networks of African haplogroup L mitochondrial DNA (mtDNA) sequences were analyzed to determine the pattern of substitutions in both the noncoding control and coding regions. In particular, we attempted to determine the causes of the previously reported (Howell et al. 2004) violation of the molecular clock during the evolution of these sequences. In the coding region, there was a significantly higher rate of substitution at synonymous sites than at nonsynonymous sites as well as in the tRNA and rRNA genes. This is further evidence for the operation of purifying selection during human mtDNA evolution. For most sites in the control region, the relative rate of substitution was similar to the rate of neutral evolution (assumed to be most closely approximated by the substitution rate at 4-fold degenerate sites). However, there are a number of mutational hot spots in the control region, approximately 3% of the total sites, that have a rate of substitution greater than the neutral rate, at some sites by more than an order of magnitude. It is possible either that these sites are evolving under conditions of positive selection or that the substitution rate at some sites in the control region is strongly dependent upon sequence context. Finally, we obtained preliminary evidence for "nonideal" evolution in the control region, including haplogroup-specific substitution patterns and a decoupling between relative rates of substitution in the control and coding regions. PMID:17642471

  7. [People of African descent in the region of the Americas and health equity].

    PubMed

    Torres, Cristina

    2002-01-01

    The Region of the Americas and the Caribbean has a complex demographic profile from an ethnic and racial perspective. One of the largest groups is composed of persons of African descent, who in some countries, such as Brazil and the Dominican Republic, comprise 46 and 84% of the total population, respectively. Recent analyses of the statistics available in some countries of the Region show wide gaps in terms of living conditions and health in these communities, as well as gaps in access to health services. PAHO, through its Public Policy and Health Program, under the Division of Health and Human Development, supports sectorial efforts and those of civil organizations that aim to improve health conditions in this segment of the population, while taking into account their sociodemographic and cultural characteristics. This article briefly summarizes health conditions and access to health services in selected countries, as well as some aspects of the recent changes to the legislation in those countries. Finally, collaborative activities on the part of United Nations agencies and international financial institutions for the benefit of people of African descent and other ethnic minorities are described. PMID:12162849

  8. Solar Spectral Radiative Forcing During the Southern African Regional Science Initiative

    NASA Technical Reports Server (NTRS)

    Pilewskie, P.; Pommier, J.; Bergstrom, R.; Gore, W.; Howard, S.; Rabbette, M.; Schmid, B.; Hobbs, P. V.; Tsay, S. C.

    2003-01-01

    During the dry season component of the Southern African Regional Science Initiative (SAFARI) in late winter 2000, the net solar spectral irradiance was measured at flight levels throughout biomass burning haze layers. From these measurements, the flux divergence, fractional absorption, instantaneous heating rate, and absorption efficiency were derived. Two cases are examined: on 24 August 2000 off the coast of Mozambique in the vicinity of Inhaca Island and on 6 September 2000 in a very thick continental haze layer over Mongu, Zambia. The measured absolute absorption was substantially higher for the case over Mongu where the measured midvisible optical depth exceeded unity. Instantaneous heating from aerosol absorption was 4 K d(sup -1) over Mongu, Zambia and 1.5 K d(sup -1) near Inhaca Island, Mozambique. However, the spectral absorption efficiency was nearly identical for both cases. Although the observations over Inhaca Island preceded the river of smoke from the southern African continent by nearly 2 weeks, the evidence here suggests a continental influence in the lower tropospheric aerosol far from source regions of burning.

  9. Solar quiet day ionospheric source current in the West African region

    PubMed Central

    Obiekezie, Theresa N.; Okeke, Francisca N.

    2012-01-01

    The Solar Quiet (Sq) day source current were calculated using the magnetic data obtained from a chain of 10 magnetotelluric stations installed in the African sector during the French participation in the International Equatorial Electrojet Year (IEEY) experiment in Africa. The components of geomagnetic field recorded at the stations from January–December in 1993 during the experiment were separated into the source and (induced) components of Sq using Spherical Harmonics Analysis (SHA) method. The range of the source current was calculated and this enabled the viewing of a full year’s change in the source current system of Sq. PMID:25685434

  10. Solar quiet day ionospheric source current in the West African region.

    PubMed

    Obiekezie, Theresa N; Okeke, Francisca N

    2013-05-01

    The Solar Quiet (Sq) day source current were calculated using the magnetic data obtained from a chain of 10 magnetotelluric stations installed in the African sector during the French participation in the International Equatorial Electrojet Year (IEEY) experiment in Africa. The components of geomagnetic field recorded at the stations from January-December in 1993 during the experiment were separated into the source and (induced) components of Sq using Spherical Harmonics Analysis (SHA) method. The range of the source current was calculated and this enabled the viewing of a full year's change in the source current system of Sq. PMID:25685434

  11. Attitudes Toward Contraceptive Methods Among African American Men and Women: Similarities and Differences

    PubMed Central

    Thorburn, Sheryl

    2007-01-01

    Purpose Men’s attitudes toward contraceptives are an understudied area, even though many men participate in contraceptive decision-making. The purpose of this study was to examine attitudes and perceptions regarding a selection of contraceptive methods among a national sample of African Americans, with a particular focus on gender differences. Methods Data come from a telephone survey of African Americans (aged 15–44 years) living in the contiguous U.S. For the present analyses, the sample was restricted to 152 men and 281 women who reported having had a sexual partner of the opposite gender at some point in their lives. Bivariate analyses compared men and women’s ratings of birth control pills, male condoms, female condoms, Norplant, Depo Provera, female sterilization, and male sterilization along several dimensions: bad/good, harmful/beneficial, difficult/easy, dangerous/safe, immoral/moral, and effectiveness. Multiple logistic regressions were performed to determine the association between gender and contraceptive attitudes, adjusting for sociodemographic variables. Results Male condoms were given the most favorable ratings along most dimensions by both African American men and women. In general, ratings of male condoms, female condoms, and Norplant did not significantly differ by gender. African American men did, however, give female and male sterilization, birth control pills, and Depo Provera significantly poorer ratings than did African American women. Conclusion African American men had less favorable evaluations of some contraceptive methods than did African American women. Further research is needed to examine how such gender differences may play a role in contraceptive decisions. PMID:17321945

  12. The West African Monsoon simulated by global and regional climate models

    NASA Astrophysics Data System (ADS)

    Nikulin, Grigory; Jones, Colin; Kjellström, Erik; Gbobaniyi, Emiola

    2013-04-01

    We present results from two ensembles of global and regional climate simulations with a focus on the West African Monsoon (WAM). The first ensemble includes eight coupled atmosphere ocean general circulation models (AOGCMs) from the CMIP5 project, namely: CanESM2, CNRM-CM5, HadGEM2-ES, NorESM1-M, EC-EARTH, MIROC5, GFDL-ESM2M and MPI-ESM-LR. The second ensemble consists of corresponding downscaling of all 8 AOGCMs by a regional climate model - RCA4 produced at the Rossby Centre (SMHI) in the Africa-CORDEX activities. Spatial resolution varies from about 1° to 3° in the AOGCM ensemble while all regional simulations are at the same 0.44° resolution. To see what added value higher resolution can provide ability of the eight AOGCMs and the downscaled RCA4(AOGCMs) to simulate the key characteristics of the WAM rainy season are evaluated and then inter-compared between the global and regional ensembles. The main focus in our analysis is on the WAM rainy season onset, cessation, length, total precipitation, its mean intensity and intraseasonal variability. Future climate projections under the RCP45 and RCP85 scenarios are analyzed and again inter-compared for both ensembles in order to assess uncertainties in the future projections of the WAM rainy season from the global and regional ensembles.

  13. Possible Effects of Seasonal Fires on Drought Across the Northern Sub-Saharan African Region

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles

    2010-01-01

    Recent satellite-based studies have revealed that the northern sub-Saharan African (NSSA) region has one of the highest biomass-burning rates per unit land area among all regions of the world. Because of the high concentration and frequency of fires in this region, with the associated abundance of heat release and gaseous and particulate smoke emissions, biomass-burning activity is believed to be a major driver of the regional carbon, energy, and water cycles. We acknowledge that the rainy season in the NSSA region is from April to September while biomass burning occurs mainly during the dry season (October to March). Nevertheless, these two phenomena are indirectly coupled to each other through a chain of complex processes and conditions, including land-cover and surface-albedo changes, the carbon cycle, evapotranspiration, drought, desertification, surface water runoff, ground water recharge, and variability in atmospheric composition, heating rates, and circulation. In this presentation, we will examine the theoretical linkages between these processes, discuss the preliminary results based on satellite data analysis, and provide an overview of plans for more integrated research to be conducted over the next few years.

  14. North African petroleum geology: regional structure and stratigraphic overview of a hydrocarbon-rich cratonic area

    SciTech Connect

    O'Connor, T.E.; Kanes, W.H.

    1985-02-01

    North Africa, including Sinai, contains some of the most important hydrocarbon-producing basins in the world. The North African Symposium is devoted to examining the exploration potential of the North African margin in light of the most recent and promising exploration discoveries. The geologic variety of the region is extraordinary and can challenge any exploration philosophy. Of primary interest are the Sirte basin of Libya, which has produced several billion barrels of oil, and the Gulf of Suez, a narrow, evaporite-capped trough with five fields that will produce more than 5 billion bbl. Both are extensional basins with minimal lateral movement and with good source rocks in direct proximity to reservoirs. Structural models of these basins give firm leads for future exploration. More difficult to evaluate are the Tethyan realm basins of the northern Sinai, and the Western Desert of Egypt, the Cyrenaican Platform of Libya, and the Tunisia-Sicily shelf area, where there are only limited subsurface data. These basins are extensional in origin also, but have been influenced by lateral tectonics. Favorable reservoirs exist, but source rocks have been a problem locally. Structural models with strong stratigraphic response offer several favorable play concepts. The Paleozoic Ghadames basin in Libya, Tunisia, and Algeria has the least complex structural history, and production appears to be limited to small structures. A series of stratigraphic models indicates additional areas with exploration potential. The Paleozoic megabasin of Morocco, with its downfaulted Triassic grabens, remains an untested but attractive area.

  15. Simultaneous observations of ionospheric irregularities in the African low-latitude region

    NASA Astrophysics Data System (ADS)

    Ngwira, Chigomezyo M.; Seemala, Gopi K.; Bosco Habarulema, John

    2013-05-01

    Ionospheric storms represent large global disturbances of the ionospheric F-region electron density in response to geomagnetic storms. This study investigates the ionospheric response during a minor geomagnetic storm that occurred on 13-15 September 2004. In particular, we use total electron content (TEC) measurements (rate of TEC change, ROT) to examine the presence of ionospheric irregularities over four low-latitude stations in the African sector, a region that has been less studied. Ionospheric irregularities are known to cause fading and phase fluctuation of L-band radio navigation signals such as those used by the Global Navigation Satellite Systems (GNSS), and are a common feature in the equatorial and low-latitude ionosphere. In the present study, the storm began with a sudden commencement at approximately 20:00 UT on 13 September, while the peak of the main phase occurred on 14 September with an SYM-H index value around -59 nT. On 13 September, the storm did not appear to hinder the development of irregularities as they were observed over all the stations. In contrast, irregularities were rarely observed at two of the 4 stations under study and were absent over the other two stations on 14 September. The DSMP F15 satellite post-sunset flight over the African region observed deep density depletions on 13 September that can be associated with the presence of ionospheric plasma bubble irregularities. Furthermore, an analysis of ΔH (horizontal geomagnetic component corrected for ring current effects) shows that there was a strong positive ΔH perturbation observed in the post-sunset hours on 13 September, which suggests the presence of an eastward penetration electric field, while a negative perturbation of ΔH, which is associated with the equatorial counter-electrojet, was observed on 14 September.

  16. Africanized honey bees (Apis mellifera) have low infestation levels of the mite Varroa destructor in different ecological regions in Mexico.

    PubMed

    Medina-Flores, C A; Guzmán-Novoa, E; Hamiduzzaman, M M; Aréchiga-Flores, C F; López-Carlos, M A

    2014-01-01

    Honey bee (Apis mellifera) colonies of African and European descent were compared for levels of Varroa destructor infestation in 3 different ecological regions in Mexico. The 300 colonies that were studied were located in subtropical, temperate sub-humid, and temperate dry climates. The morphotype and mitotype of adult bees as well as their rates of infestation by varroa mites were determined. Additionally, the number of combs with brood and covered with bees was recorded for each colony. The highest frequency of colonies that were classified as African-derived was found in the subtropical environment, whereas the lowest occurred in the temperate dry region. Overall, the colonies of African genotype had significantly lower mite infestation rates (3.5±0.34%) than the colonies of European genotype (4.7±0.49%) regardless of the region sampled. Significant effects of genotype and region on Varroa infestation rates were evident, and there were no differences in bee population or capped brood between genotypes. Mite infestation levels were significantly lower in the colonies of the temperate dry region than in the colonies of the other 2 regions. These results are discussed within the context of results from studies that were previously conducted in Brazil. This is the first study that demonstrates the effects of Africanization and ecological environment on V. destructor infestation rates in honey bee colonies in North America. PMID:24634296

  17. A review of groundwater recharge estimation in humid and semi-arid African regions

    NASA Astrophysics Data System (ADS)

    Chung, Il-Moon; Kim, Nam Won

    2016-04-01

    For the review of African recharge estimation, the distinct methods such as the geochemical approach, a method using groundwater level data, the streamflow method, and the water balance methods were first outlined. The major challenge of an African recharge study is the lack of basic data. Thus, this work suggests how to deal with this limitation and from future perspective using recently developed technologies such as RS, GIS, etc. With the rapid growth of information technology, more and more data, in terms of both volume and variety, are expected to be made available on the internet in the near future. RS technology has a great potential to revolutionize the groundwater development and management in the future by providing unique and completely new hydrological and hydrogeological data. However, at present, the RS data should be considered along with the conventional field data. In spite of the weaknesses of water balance methods in semi-arid areas, recently developed water balance methods combined with GIS technology are powerful tools for estimating groundwater re-charge, when spatial-temporal variability of components in water balance is taken into account (Lerner et al., 1990; De Vries and Simmers, 2002; Eilers et al., 2007).When enough data sets are available, integrated surface-groundwater modeling is recommended for more accurate estimation of groundwater recharge and discharge. Acknowledgements This work was supported by a grant(14RDRP-B076275-01-000000) from Infrastructure and transportation technology promotion research Program funded by the Ministry of Land, Infrastructure and Transport of Korean government.

  18. Responses of equatorial F region to different geomagnetic storms observed by GPS in the African sector

    NASA Astrophysics Data System (ADS)

    Adewale, A. O.; Oyeyemi, E. O.; Adeloye, A. B.; Ngwira, C. M.; Athieno, R.

    2011-12-01

    This article presents the first results regarding the investigation of the response of the equatorial ionospheric F region in the African sector during geomagnetic storm periods between April 2000 and November 2007 using GPS-derived vertical total electron content observed at Libreville, Gabon (0.35°N, 9.67°E, dip latitude -8.05°S). We performed a superposed epoch analysis of the storms by defining the start time of the epoch as the storm onset time. During geomagnetic storms, the altered electric fields contribute significantly to the occurrence of negative and positive ionospheric storm effects. Our results showed that the positive storm effects are more prevalent than the negative storm effects and generally last longer irrespective of storm onset times. Also, the positive storm effects are most pronounced in the daytime than in the premidnight and postmidnight periods.

  19. Barriers to condom use and barrier method preferences among low-income African-American women.

    PubMed

    Eldridge, G D; St Lawrence, J S; Little, C E; Shelby, M C; Brasfield, T L

    1995-01-01

    Low-income African-American women (N = 178) entering health clinics completed surveys assessing perceived barriers to condom use for themselves personally and for African-American women generally. Following the survey, each woman received a demonstration of five barrier contraceptive methods and then rated her preference among those methods. The women perceived relatively few personal barriers to use of the male condom but perceived significantly greater barriers for other African-American women (all p < .0001). The male condom was first choice of the largest percentage of women (45%) and last choice of the smallest percentage of women (11%). The male condom was preferred for its convenience, availability, and safety, although the necessity for active cooperation by the male partner was considered a hindrance to using the method. Only 23% of women ranked the female condom as first choice and 35% ranked the female condom as last choice. Reasons for selecting the female condom included preference for a female-controlled method, safety, and protection. However, the female condom was perceived to be uncomfortable, to require the partner's acquiescence, and to interfere with sexual experience. Differences in the women's perceptions of barriers to condom use for themselves and for other African-American women are consistent with Weinstein's theory of optimistic bias. Preferences among barrier methods indicate that further research and product development are needed to develop barrier methods that are female-controlled, do not require the awareness of the male partner, and are safe, comfortable, and convenient. PMID:7483652

  20. New vaccine introduction in the East and Southern African sub-region of the WHO African region in the context of GIVS and MDGs.

    PubMed

    Chauke-Moagi, Bafedile E; Mumba, Mutale

    2012-09-01

    number of countries have adopted and operationalized GIVS through comprehensive multi-year plans for immunization (cMYP). This paper reviews progress with respect to introduction of some of the new vaccines in the East and Southern sub-region of WHO African region in the context of GIVS and MDGs as well as the challenges thereof. PMID:22939018

  1. Characterisation of plumes from the Johannesburg-Pretoria megacity within the regional South African context

    NASA Astrophysics Data System (ADS)

    Beukes, J. P.; Vakkari, V.; Van Zyl, P. G.; Venter, A. D.; Josipovic, M.; Tiitta, P.; Jaars, K.; Pienaar, J. J.; Kulmala, M.; Worsnop, D.; Laakso, L.

    2012-04-01

    plumes from the more well-known source regions i.e. the Mpumalanga Highveld and the Vaal Triangle, which have been proclaimed as a national air pollution hotspots in terms of the South African National Environmental Management: Air Quality Act (Government Gazette Republic of South Africa, 2005; Government Gazette Republic of South Africa, 2007). The above-mentioned results obtained for the Johannesburg-Pretoria conurbation indicate serious air quality and climate change related impacts for the human population and regional ecosystems.

  2. Assessing the Change in Rainfall Characteristics and Trends for the Southern African ITCZ Region

    NASA Astrophysics Data System (ADS)

    Baumberg, Verena; Weber, Torsten; Helmschrot, Jörg

    2015-04-01

    Southern Africa is strongly influenced by the movement and intensity of the Intertropical Convergence Zone (ITCZ) thus determining the climate in this region with distinct seasonal and inter-annual rainfall dynamics. The amount and variability of rainfall affect the various ecosystems by controlling the hydrological system, regulating water availability and determining agricultural practices. Changes in rainfall characteristics potentially caused by climate change are of uppermost relevance for both ecosystem functioning and human well-being in this region and, thus, need to be investigated. To analyse the rainfall variability governed by the ITCZ in southern Africa, observational daily rainfall datasets with a high spatial resolution of 0.25° x 0.25° (about 28 km x 28 km) from satellite-based Tropical Rainfall Measuring Mission (TRMM) and Global Land Data Assimilation System (GLDAS) are used. These datasets extend from 1998 to 2008 and 1948 to 2010, respectively, and allow for the assessment of rainfall characteristics over different spatial and temporal scales. Furthermore, a comparison of TRMM and GLDAS and, where available, with observed data will be made to determine the differences of both datasets. In order to quantify the intra- and inner-annual variability of rainfall, the amount of total rainfall, duration of rainy seasons and number of dry spells along with further indices are calculated from the observational datasets. Over the southern African ITCZ region, the rainfall characteristics change moving from wetter north to the drier south, but also from west to east, i.e. the coast to the interior. To address expected spatial and temporal variabilities, the assessment of changes in the rainfall parameters will be carried out for different transects in zonal and meridional directions over the region affected by the ITCZ. Revealing trends over more than 60 years, the results will help to identify and understand potential impacts of climate change on

  3. Polio eradication in the World Health Organization African Region, 2008-2012.

    PubMed

    Kretsinger, Katrina; Gasasira, Alex; Poy, Alain; Porter, Kimberly A; Everts, Johannes; Salla, Mbaye; Brown, Kristin H; Wassilak, Steven G F; Nshimirimana, Deogratias

    2014-11-01

    A renewed commitment at the regional and the global levels led to substantial progress in the fight for polio eradication in the African Region (AFR) of the World Health Organization (WHO) during 2008-2012. In 2008, there were 912 reported cases of wild poliovirus (WPV) infection in 12 countries in the region. This number had been reduced to 128 cases in 3 countries in 2012, of which 122 were in Nigeria, the only remaining country with endemic circulation of WPV in AFR. During 2008-2012, circulation apparently ceased in the 3 AFR countries with reestablished WPV transmission-Angola, the Democratic Republic of the Congo, and Chad. Outbreaks in West Africa continued to occur in 2008-2010 but were more rapidly contained, with fewer cases than during earlier years. This progress has been attributed to better implementation of core strategies, increased accountability, and implementation of innovative approaches. During this period, routine coverage with 3 doses of oral polio vaccine in AFR, as measured by WHO-United Nations Children's Fund estimates, increased slightly, from 72% to 74%. Despite this progress, challenges persist in AFR, and 2013 was marked by new setbacks and importations. High population immunity and strong surveillance are essential to sustain progress and assure that AFR reaches its goal of eradicating WPV. PMID:25316840

  4. Physical impacts of regional climate change in the West African Sahel and the question of desertification

    SciTech Connect

    Nicholson, S.E.; Ba, M.

    1997-11-01

    The question of desertification is examined in the West African Sahel region by considering various physical indicators assumed to accompany this process. The study considers only the past 14 years, since the availability of comprehensive satellite data sets. The physical indicators examined include vegetation cover, surface albedo, soil moisture, wind-borne dust, river flow, lakes, and the ratio of available moisture to vegetation growth. Vegetation cover and albedo are assessed from satellite data. Soil moisture is assessed using a surface hydrologic model. Dust is estimated from visibility measurements. The most important results are that: (1) there is no progressive change in the vegetation cover, (2) an increase of albedo as the region dries up cannot be documented, and (3) there has been a tremendous increase in wind-borne dust over the Sahel. The vegetation cover responds almost directly to rainfall and the movement of the desert boundary corresponds roughly to rainfall fluctuations. The most important meteorological effect of the drought and/or desertification in the Sahel may be the enhanced dust generation, with the region becoming a major global source of atmospheric mineral dust. 5 refs., 7 figs., 1 tab.

  5. Integrated mapping of groundwater drought risk in the Southern African Development Community (SADC) region

    NASA Astrophysics Data System (ADS)

    Villholth, Karen G.; Tøttrup, Christian; Stendel, Martin; Maherry, Ashton

    2013-06-01

    Groundwater drought denotes the condition and hazard during a prolonged meteorological drought when groundwater resources decline and become unavailable or inaccessible for human use. Groundwater drought risk refers to the combined physical risk and human vulnerability associated with diminished groundwater availability and access during drought. An integrated management support tool, GRiMMS, is presented, for the mapping and assessment of relative groundwater drought risk in the Southern African Development Community (SADC) region. Based on composite mapping analysis of region-wide gridded relative indices of meteorological drought risk, hydrogeological drought proneness and human groundwater drought vulnerability, the mapping results highlight consistent areas across the region with highest groundwater drought risk and populations in the order of 39 million at risk of groundwater drought at present. Projective climate-model results suggest a potentially significant negative impact of climate change on groundwater drought risk. The tool provides a means for further attention to the key, but neglected, role of groundwater in drought management in Africa.

  6. Feedback of observed interannual vegetation change: a regional climate model analysis for the West African monsoon

    NASA Astrophysics Data System (ADS)

    Klein, Cornelia; Bliefernicht, Jan; Heinzeller, Dominikus; Gessner, Ursula; Klein, Igor; Kunstmann, Harald

    2016-06-01

    West Africa is a hot spot region for land-atmosphere coupling where atmospheric conditions and convective rainfall can strongly depend on surface characteristics. To investigate the effect of natural interannual vegetation changes on the West African monsoon precipitation, we implement satellite-derived dynamical datasets for vegetation fraction (VF), albedo and leaf area index into the Weather Research and Forecasting model. Two sets of 4-member ensembles with dynamic and static land surface description are used to extract vegetation-related changes in the interannual difference between August-September 2009 and 2010. The observed vegetation patterns retain a significant long-term memory of preceding rainfall patterns of at least 2 months. The interannual vegetation changes exhibit the strongest effect on latent heat fluxes and associated surface temperatures. We find a decrease (increase) of rainy hours over regions with higher (lower) VF during the day and the opposite during the night. The probability that maximum precipitation is shifted to nighttime (daytime) over higher (lower) VF is 12 % higher than by chance. We attribute this behaviour to horizontal circulations driven by differential heating. Over more vegetated regions, the divergence of moist air together with lower sensible heat fluxes hinders the initiation of deep convection during the day. During the night, mature convective systems cause an increase in the number of rainy hours over these regions. We identify this feedback in both water- and energy-limited regions of West Africa. The inclusion of observed dynamical surface information improved the spatial distribution of modelled rainfall in the Sahel with respect to observations, illustrating the potential of satellite data as a boundary constraint for atmospheric models.

  7. A model for selecting assessment methods for evaluating medical students in African medical schools.

    PubMed

    Walubo, Andrew; Burch, Vanessa; Parmar, Paresh; Raidoo, Deshandra; Cassimjee, Mariam; Onia, Rudy; Ofei, Francis

    2003-09-01

    Introduction of more effective and standardized assessment methods for testing students' performance in Africa's medical institutions has been hampered by severe financial and personnel shortages. Nevertheless, some African institutions have recognized the problem and are now revising their medical curricula, and, therefore, their assessment methods. These institutions, and those yet to come, need guidance on selecting assessment methods so as to adopt models that can be sustained locally. The authors provide a model for selecting assessment methods for testing medical students' performance in African medical institutions. The model systematically evaluates factors that influence implementation of an assessment method. Six commonly used methods (the essay examinations, short-answer questions, multiple-choice questions, patient-based clinical examination, problem-based oral examination [POE], and objective structured clinical examination) are evaluated by scoring and weighting against performance, cost, suitability, and safety factors. In the model, the highest score identifies the most appropriate method. Selection of an assessment method is illustrated using two institutional models, one depicting an ideal situation in which the objective structured clinical examination was preferred, and a second depicting the typical African scenario in which the essay and short-answer-question examinations were best. The POE method received the highest score and could be recommended as the most appropriate for Africa's medical institutions, but POE assessments require changing the medical curricula to a problem-based learning approach. The authors' model is easy to understand and promotes change in the medical curriculum and method of student assessment. PMID:14507620

  8. Translating the potential of hydrological forecasts into improved decision making in African regions

    NASA Astrophysics Data System (ADS)

    Sheffield, J.; He, X.; Wanders, N.; Wood, E. F.; Ali, A.; Olang, L.; Estes, L. D.; Caylor, K. K.; Evans, T. P.

    2015-12-01

    Hydrological forecasts at local scale and seasonal time scales have the potential to inform decision-making by individuals and institutions to improve management of water resources and enhance food security. Much progress has been made in recent years in understanding climate variability and its predictability over African regions. However, there remain many challenges in translating large-scale evaluations and forecasts into locally relevant information. This is hampered by lack of on the ground data of hydrological and agricultural states, and the generally low skill of climate forecasts at time scales beyond one or two weeks. Additionally, the uptake of forecasts is not prevalent because of lack of capacity, and institutional and cultural barriers to using new and uncertain information. New technologies for monitoring and forecasting relevant hydrological variables, and novel approaches to understanding how this information may be used within decision making processes, have the potential to make substantial progress in addressing these challenges. We present a quasi-operational drought and flood monitoring and forecasting system and its use in understanding the potential of hydrological forecasts for improved decision-making. The system monitors in near real-time the terrestrial water cycle for the African continent based on remote sensing data and land surface hydrological modeling. The monitoring forms initial conditions for hydrological forecasts at short time scale, aimed at flood forecasting, and seasonal scale aimed at drought and crop yield forecasts. The flood forecasts are driven by precipitation and temperature forecasts from the Global Forecast System (GFS). The drought forecasts are driven by climate forecasts from the North American Multi-Model Ensemble (NMME). The seasonal forecast skill is modest and seasonally/regionally dependent with part of the skill coming from persistence in initial land surface conditions. We discuss the use of the system

  9. The negative impacts of human activities in the eastern African region: an international waters perspective.

    PubMed

    Payet, Rolph; Obura, David

    2004-02-01

    The complex interactions between human activities and the environment at the interface of land and water is analyzed with a focus on the Somali Current (East Africa), and Indian Ocean Island States, subregions of the Global International Waters Assessment (GIWA). These 2 subregions contain some of the world's richest ecosystems, including the high biodiversity forests of Madagascar and the diverse coastal habitats of the eastern African coast. These ecosystems support local communities and national and regional economies. Current and future degradation of these systems, from water basins to continental shelves, affects the livelihoods and sustainability of the countries in the region, and long-term efforts to reduce poverty. The assessments determined that pollution and climate change are the primary environmental and social concerns in the Islands of the Indian Ocean, while freshwater shortage and unsustainable exploitation of fisheries and other living resources are the primary environmental and social concerns in East Africa. The GIWA approach, through assessing root causes of environmental concerns, enables the development of policy approaches for mitigating environmental degradation. This paper explores policy frameworks for mitigating the impacts, and reducing the drivers, of 3 environmental concerns--freshwater shortage; solid waste pollution; and climate change--addressing social and institutional causes and effects, and linking the subregions to broad international frameworks. The common theme in all 3 case studies is the need to develop integrated ecosystem and international waters policies, and mechanisms to manage conflicting interests and to limit threats to natural processes. PMID:15083647

  10. Regional diversity patterns in African bovids, hyaenids, and felids during the past 3 million years: the role of taphonomic bias and implications for the evolution of Paranthropus

    NASA Astrophysics Data System (ADS)

    Patterson, David B.; Faith, J. Tyler; Bobe, René; Wood, Bernard

    2014-07-01

    Reconstructing patterns of Plio-Pleistocene mammalian faunal exchange between eastern and southern Africa may help us to better understand patterns of evolution within the hominin clade. However, differences in geological context, taphonomic history and collection methods, as well as a lack of a precise chronology in one of the regions, complicate attempts to compare the faunas of the two regions, but access to new comprehensive datasets encouraged us to re-examine this critical time period in the African paleontological record. In this study, we examine the biogeographic histories of three terrestrial African mammalian families whose fossil records span the past 3 million years to test hypotheses related to the evolutionary history of the hominin genus Paranthropus. We used presence/absence data for 117 species from 38 genera within the family Bovidae and 34 species from 15 genera within the families Hyaenidae and Felidae from 52 eastern African and 40 southern African fossil localities. These assemblages were placed into 500 ka time slices and compared at both the genus and species level using the Jaccard index of faunal similarity. Our findings indicate that sampling biases have more effect on the patterns of interchange between eastern and southern African Bovidae than they do the patterns of interchange seen in the Hyaenidae and Felidae. However, even when these biases are taken into account there are persistent differences in the degree of interchange within and between these families. These findings suggest that mammalian groups (including hominins) can have very different histories of exchange between eastern and southern Africa over the past 3 million years. There is no a priori reason why any of the three families we examined is a suitable proxy for the eastern and southern African hyper-megadont and megadont hominin taxa presently included in Paranthropus, but of the three we suggest that the Bovidae is likely to come closest to being an appropriate

  11. Regional Variations in the Phonological Characteristics of African American Vernacular English.

    ERIC Educational Resources Information Center

    Hinton, Linette N.; Pollock, Karen E.

    2000-01-01

    Investigated African American Vernacular English dialect features in the midwestern community of Davenport, Iowa, and compared them to those reported by Pollock and Berni (1997) for Memphis, Tennessee--specifically productions of vocalic and postvocalic /r/ across African-American speakers from Davenport and Memphis. (Author/VWL)

  12. Political Implications of the Southern African Development Community Agenda on Educational Development in the Region.

    ERIC Educational Resources Information Center

    Nziramasanga, Caiphas T.

    This paper briefly describes the historical development of the Southern African Development Coordination Conference (SADCC) from its roots in 1980 and examines the work of the Southern African Development Community (SADC) today. The objectives of the SADCC are listed from the 1980 declaration and the achievement of those objectives are assessed.…

  13. African Regional Symposium on Telematics for Development. Report and Recommendations = Colloque regional africain la telematique au service du developpement. Rapport et recommandations (Addis Ababa, Ethiopia, April 3-7, 1995).

    ERIC Educational Resources Information Center

    International Telecommunication Union, Geneva (Switzerland).

    The African Regional Symposium on Telematics for Development was organized in view of the special educational and communication needs of Africa in a time of accelerating change and development of information technologies. The symposium brought together more than 150 African specialists, and over 40 participants from other regions and development…

  14. The self-organizing map, a new approach to apprehend the Madden-Julian Oscillation influence on the intraseasonal variability of rainfall in the southern African region

    NASA Astrophysics Data System (ADS)

    Oettli, Pascal; Tozuka, Tomoki; Izumo, Takeshi; Engelbrecht, Francois A.; Yamagata, Toshio

    2014-09-01

    The Madden-Julian Oscillation (MJO) is the major mode of intraseasonal variability (30-60 days) in the tropics, having large rainfall impacts globally, and possibly on southern Africa. However, the latter impact is not well understood and needs to be further explored. The life cycle of the MJO, known to be asymmetric, has been nevertheless analyzed usually through methods constrained by both linearity and orthogonality, such as empirical orthogonal function analysis. Here we explore a non-linear classification method, the self-organizing map (SOM), a type of artificial neural network used to produce a low-dimensional representation of high-dimensional datasets, to capture more accurately the life cycle of the MJO and its global impacts. The classification is applied on intraseasonal anomalies of outgoing longwave radiation within the tropical region over the 1980-2009 period. Using the SOM to describe the MJO is a new approach, complimentary to the usual real-time multivariate MJO index. It efficiently captures this propagative phenomenon and its seasonality, and is shown to provide additional temporal and spatial information on MJO activity. For each node, the subtropical convection is analyzed, with a particular focus on the southern Africa region. Results show that the convection activity over the central tropical Indian Ocean is a key factor influencing the intraseasonal convective activity over the southern African region. Enhanced (suppressed) convection over the central Indian Ocean tends to suppress (enhance) convection over the southern African region with a 10-day lag by modulating the moisture transport.

  15. Optical, physical and chemical properties of transported African mineral dust aerosols in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Di Biagio, Claudia; Chevaillier, Servanne; Gaimoz, Cécile; Grand, Noel; Loisil, Rodrigue; Triquet, Sylvain; Zapf, Pascal; Roberts, Greg; Bourrianne, Thierry; Torres, Benjamin; Blarel, Luc; Sellegri, Karine; Freney, Evelyn; Schwarzenbock, Alfons; Ravetta, François; Laurent, Benoit; Mallet, Marc; Formenti, Paola

    2014-05-01

    The transport of mineral dust aerosols is a global phenomenon with strong climate implications. Depending on the travel distance over source regions, the atmospheric conditions and the residence time in the atmosphere, various transformation processes (size-selective sedimentation, mixing, condensation of gaseous species, and weathering) can modify the physical and chemical properties of mineral dust, which, in turn, can change the dust's optical properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of these properties, and their temporal evolution with transport time. Within the frame of the ChArMex project (Chemistry-Aerosol Mediterranean experiment, http://charmex.lsce.ipsl.fr/), two intensive airborne campaigns (TRAQA, TRansport and Air QuAlity, 18 June - 11 July 2012, and ADRIMED, Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region, 06 June - 08 July 2013) have been performed over the Central and Western Mediterranean, one of the two major transport pathways of African mineral dust. In this study we have set up a systematic strategy to determine the optical, physical and optical properties of mineral dust to be compared to an equivalent dataset for dust close to source regions in Africa. This study is based on airborne observations onboard the SAFIRE ATR-42 aircraft, equipped with state of the art in situ instrumentation to measure the particle scattering and backscattering coefficients (nephelometer at 450, 550, and 700 nm), the absorption coefficient (PSAP at 467, 530, and 660 nm), the extinction coefficient (CAPS at 530 nm), the aerosol optical depth (PLASMA at 340 to 1640 nm), the size distribution in the extended range 40 nm - 30 µm by the combination of different particle counters (SMPS, USHAS, FSSP, GRIMM) and the chemical composition obtained by filter sampling. The chemistry and transport model CHIMERE-Dust have been used to classify the air masses according to

  16. Properties of transported African mineral dust aerosols in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Chevaillier, Servanne; Gaimoz, Cécile; Grand, Noel; Triquet, Sylvain; Zapf, Pascal; Loisil, Rodrigue; Bourrianne, Thierry; Freney, Evelyn; Dupuy, Regis; Sellegri, Karine; Schwarzenbock, Alfons; Torres, Benjamin; Mallet, Marc; Cassola, Federico; Prati, Paolo; Formenti, Paola

    2015-04-01

    The transport of mineral dust aerosols is a global phenomenon with strong climate implications. Depending on the travel distance over source regions, the atmospheric conditions and the residence time in the atmosphere, various transformation processes (size-selective sedimentation, mixing, condensation of gaseous species, and weathering) can modify the physical and chemical properties of mineral dust, which, in turn, can change the dust's optical properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of these properties, and their temporal evolution with transport time. Within the frame of the ChArMex project (Chemistry-Aerosol Mediterranean experiment, http://charmex.lsce.ipsl.fr/), one intensive airborne campaign (ADRIMED, Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region, 06 June - 08 July 2013) has been performed over the Central and Western Mediterranean, one of the two major transport pathways of African mineral dust. In this study we have set up a systematic strategy to determine the optical, physical and optical properties of mineral dust to be compared to an equivalent dataset for dust close to source regions in Africa. This study is based on airborne observations onboard the SAFIRE ATR-42 aircraft, equipped with state of the art in situ instrumentation to measure the particle scattering and backscattering coefficients (nephelometer at 450, 550, and 700 nm), the absorption coefficient (PSAP at 467, 530, and 660 nm), the extinction coefficient (CAPS at 530 nm), the aerosol optical depth (PLASMA at 340 to 1640 nm), the size distribution in the extended range 40 nm - 30 µm by the combination of different particle counters (SMPS, USHAS, FSSP, GRIMM) and the chemical composition obtained by filter sampling. The chemistry and transport model CHIMERE-Dust have been used to classify the air masses according to the dust origin and transport. Case studies of dust transport

  17. Interactions and Feedbacks Between Biomass Burning and Water Cycle Dynamics Across the Northern Sub-Saharan African Region

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles

    2012-01-01

    The northern sub-Saharan African (NSSA) region, bounded on the north and south by the Sahara and the Equator, respectively, and stretching from the West to the East African coastlines, has one of the highest biomass-burning rates per unit land area among all regions of the world. Because of the high concentration and frequency of fires in this region, with the associated abundance of heat release and gaseous and particulate smoke emissions, biomass-burning activity is believed to be one of the drivers of the regional carbon and energy cycles, with serious implications for the water cycle. A new interdisciplinary research effort sponsored by NASA is presently being focused on the NSSA region, to better understand the possible connection between the intense biomass burning observed from satellite year after year across the region and the rapid depletion of the regional water resources, as exemplified by the dramatic drying of Lake Chad. A combination of remote sensing and modeling approaches is being utilized in investigating multiple regional surface, atmospheric, and water-cycle processes, and inferring possible links between them. In this presentation, we will discuss preliminary results as well as the path toward improved understanding of the interrelationships and feedbacks between the biomass burning and the environmental change dynamics in the NSSA region.

  18. Exploring child prostitution in a major city in the West African region.

    PubMed

    Hounmenou, Charles

    2016-09-01

    The study explored the characteristics of child prostitution in a major city in the West African region. A convenience sample of children in prostitution, specifically girls below age 18 (n=243), were recruited on 83 prostitution sites identified in Ouagadougou, the capital city of Burkina Faso. A survey instrument, consisting of 71 closed-ended question items, was used to explore various variables including profile of children in prostitution, factors of vulnerability to prostitution; prostitution practices, compensations and related issues in child prostitution. The findings show that most children in prostitution in the city were from Burkina Faso (63%) and Nigeria (30%), two countries that do not share borders. Most native respondents practiced prostitution for survival and to support their families. In contrast, all the respondents from Nigeria practiced prostitution as victims of international sex trafficking. An important finding was that 77% of the children in prostitution surveyed were educated. Among the respondents, there were similarities in the major life events that contributed to their situation of prostitution. These life events include early separation with parents, sexual abuse, foster care, and forced marriage. Implications for policy, practice and research are discussed. PMID:27490517

  19. Tracking cashew economically important diseases in the West African region using metagenomics.

    PubMed

    Monteiro, Filipa; Romeiras, Maria M; Figueiredo, Andreia; Sebastiana, Mónica; Baldé, Aladje; Catarino, Luís; Batista, Dora

    2015-01-01

    During the last decades, agricultural land-uses in West Africa were marked by dramatic shifts in the coverage of individual crops. Nowadays, cashew (Anacardium occidentale L.) is one of the most export-oriented horticulture crops, notably in Guinea-Bissau. Relying heavily on agriculture to increase their income, developing countries have been following a strong trend of moving on from traditional farming systems toward commercial production. Emerging infectious diseases, driven either by adaptation to local conditions or inadvertent importation of plant pathogens, are able to cause tremendous cashew production losses, with economic and social impact of which, in developing countries is often underestimated. Presently, plant genomics with metagenomics as an emergent tool, presents an enormous potential to better characterize diseases by providing extensive knowledge on plant pathogens at a large scale. In this perspective, we address metagenomics as a promising genomic tool to identify cashew fungal associated diseases as well as to discriminate the causal pathogens, aiming at obtaining tools to help design effective strategies for disease control and thus promote the sustainable production of cashew in West African Region. PMID:26175748

  20. Tracking cashew economically important diseases in the West African region using metagenomics

    PubMed Central

    Monteiro, Filipa; Romeiras, Maria M.; Figueiredo, Andreia; Sebastiana, Mónica; Baldé, Aladje; Catarino, Luís; Batista, Dora

    2015-01-01

    During the last decades, agricultural land-uses in West Africa were marked by dramatic shifts in the coverage of individual crops. Nowadays, cashew (Anacardium occidentale L.) is one of the most export-oriented horticulture crops, notably in Guinea-Bissau. Relying heavily on agriculture to increase their income, developing countries have been following a strong trend of moving on from traditional farming systems toward commercial production. Emerging infectious diseases, driven either by adaptation to local conditions or inadvertent importation of plant pathogens, are able to cause tremendous cashew production losses, with economic and social impact of which, in developing countries is often underestimated. Presently, plant genomics with metagenomics as an emergent tool, presents an enormous potential to better characterize diseases by providing extensive knowledge on plant pathogens at a large scale. In this perspective, we address metagenomics as a promising genomic tool to identify cashew fungal associated diseases as well as to discriminate the causal pathogens, aiming at obtaining tools to help design effective strategies for disease control and thus promote the sustainable production of cashew in West African Region. PMID:26175748

  1. Identifying transboundary aquifers in need of international resource management in the Southern African Development Community region

    NASA Astrophysics Data System (ADS)

    Davies, Jeff; Robins, Nick S.; Farr, John; Sorensen, James; Beetlestone, Philip; Cobbing, Jude E.

    2013-03-01

    Transboundary aquifer (TBA) management, in part, seeks to mitigate degradation of groundwater resources caused either by an imbalance of abstraction between countries or by cross-border pollution. Fourteen potential TBAs were identified within a hydrogeological mapping programme based on simple hydrogeological selection criteria for the Southern African Development Community (SADC) region. These have been reassessed against a set of data associated with five categories: (1) groundwater flow and vulnerability (which is perceived as the over-arching influence on the activity level of each TBA), (2) knowledge and understanding, (3) governance capability, (4) socio-economic/water-demand factors, and (5) environmental issues. These assessments enable the TBAs to be classified according to their need for cross-border co-operation and management. The study shows that only two of the 14 TBAs have potential to be the cause of tension between neighbouring states, while nine are potentially troublesome and three are unlikely to become problematic even in the future. The classification highlights the need to focus on data gathering to enable improved understanding of the TBAs that could potentially become troublesome in the future due to, for example, change in demographics and climate.

  2. Africans in America.

    ERIC Educational Resources Information Center

    Hart, Ayanna; Spangler, Earl

    This book introduces African-American history and culture to children. The first Africans in America came from many different regions and cultures, but became united in this country by being black, African, and slaves. Once in America, Africans began a long struggle for freedom which still continues. Slavery, the Civil War, emancipation, and the…

  3. Capacity Building and Financing Oral Health in the African and Middle East Region.

    PubMed

    Mumghamba, E G; Joury, E; Fatusi, O; Ober-Oluoch, J; Onigbanjo, R J; Honkala, S

    2015-07-01

    Many low- and middle-income countries do not yet have policies to implement effective oral health programs. A reason is lack of human and financial resources. Gaps between resource needs and available health funding are widening. By building capacity, countries aim to improve oral health through actions by oral health care personnel and oral health care organizations and their communities. Capacity building involves achieving measurable and sustainable results in training, research, and provision of care. Actions include advancement of knowledge, attitudes and skills, expansion of support, and development of cohesiveness and partnerships. The aim of this critical review is to review existing knowledge and identify gaps and variations between and within different income levels in relation to the capacity building and financing oral health in the African and Middle East region (AMER). A second aim is to formulate research priorities and outline a research agenda for capacity building and financing to improve oral health and reduce oral health inequalities in the AMER. The article focuses on capacity building for oral health and oral health financing in the AMER of the IADR. In many communities in the AMER, there are clear and widening gaps between the dental needs and the existing capacity to meet these needs in terms of financial and human resources. Concerted efforts are required to improve access to oral health care through appropriate financing mechanisms, innovative health insurance schemes, and donor support and move toward universal oral health care coverage to reduce social inequality in the region. It is necessary to build capacity and incentivize the workforce to render evidence-based services as well as accessing funds to conduct research on equity and social determinants of oral health while promoting community engagement and a multidisciplinary approach. PMID:26101338

  4. Impact of burned areas on the northern African seasonal climate from the perspective of regional modeling

    NASA Astrophysics Data System (ADS)

    De Sales, F.; Xue, Y.; Okin, G. S.

    2014-12-01

    This study presents an investigation of the impact of burned areas on the surface energy balance and monthly precipitation in the northern Africa as simulated by a state-of-the-art regional model. Mean burned area fraction derived from MODIS approximate date of burning product were implemented in a set of 1-year long WRF/NMM/SSiB2 model simulations. Vegetation cover fraction and LAI were degraded daily based on mean burned area fraction and on the survival rate for each vegetation land cover type. Additionally, ground darkening associated with wildfire-induced ash and charcoal deposition was temporarily imposed through lower ground albedo for a period of 10 days after burning. In general, wildfire-induced vegetation and ground degradation increased surface albedo by exposing the brighter bare ground of the region, which in turn caused a decrease in surface net radiation and evapotranspiration in northern sub-saharan Africa. A decrease in atmospheric moisture flux convergence was simulated in the burned area experiments, which plays a dominant role in reducing precipitation over the area, especially in the months preceding the West African monsoon onset. The areas with largest impacts were those covered by forests and savanna, where annual precipitation decreased by 4.2% and 3.6%, respectively. This study suggests the cooling and drying of atmosphere induced by burned areas led to strengthening of subsidence during pre-onset and weakening of upward motion during onset and mature stages of the monsoon leading to a waning of convective instability and precipitation. Monthly vertical wind over the area showed a strengthening of downward motion in winter and spring seasons, and weakening of upward movement during the rainy months. Furthermore, precipitation energy analysis revealed that most of precipitation decrease originated from convective events, especially for those with daily precipitation rates above 2.0 mm day-1, which substantiates the hypothesis of convective

  5. The Chew Bahir Project, southern Ethiopia: Reconstructing East African palaeoenvironments in the source region of modern man

    NASA Astrophysics Data System (ADS)

    Foerster, V. E.; Chew Bahir Science Team

    2011-12-01

    Chew Bahir is a tectonically bounded basin in the southern part of the Main Ethiopian Rift and in close proximity to the Omo valley, which contains some of the oldest known early modern human sites. As East African palaeoenvironments are highly variable and marked by extreme fluctuations in moisture availability, this in turn bears far reaching implications for the life, evolution and most notably for the expansion of Homo sapiens beyond the limits of the African continent. This study is a prerequisite for the ICDP- Hominin Sites And Paleolakes Drilling Project and part of the CRC-806 "Our way to Europe". The Chew Bahir Project will provide fundamental data to reconstruct late Quaternary East African environments including the timing, amplitude, synchronicity and abruptness of dry-wet-dry cycles and focuses on the interaction between those rapid climate shifts and their influence on the biosphere. This poster presents results from six cores (9-18m depth) from a NW-SE transect across the Chew Bahir basin that have recorded the climatic history of the past 45 ka and therewith can potentially elucidate those highly variable East African palaeoenvironments with emphasis on the last of the wet periods, the African Humid Period (AHP). Based on a series of multi-proxy analyses, comprising geochemical, physical and biological indicators as well as AMS 14C dates, it becomes obvious that the Chew Bahir responds decidedly sensitive towards even minor climatic fluctuations on millennial to even centennial timescales. Therefore, the Chew Bahir represents a unique site to reveal the impact of timing and mechanisms of local, regional and global climate events on the key region for humankind.

  6. Novel swine virulence determinant in the left variable region of the African swine fever virus genome.

    PubMed

    Neilan, J G; Zsak, L; Lu, Z; Kutish, G F; Afonso, C L; Rock, D L

    2002-04-01

    Previously we have shown that the African swine fever virus (ASFV) NL gene deletion mutant E70DeltaNL is attenuated in pigs. Our recent observations that NL gene deletion mutants of two additional pathogenic ASFV isolates, Malawi Lil-20/1 and Pr4, remained highly virulent in swine (100% mortality) suggested that these isolates encoded an additional virulence determinant(s) that was absent from E70. To map this putative virulence determinant, in vivo marker rescue experiments were performed by inoculating swine with infection-transfection lysates containing E70 NL deletion mutant virus (E70DeltaNL) and cosmid DNA clones from the Malawi NL gene deletion mutant (MalDeltaNL). A cosmid clone representing the left-hand 38-kb region (map units 0.05 to 0.26) of the MalDeltaNL genome was capable of restoring full virulence to E70DeltaNL. Southern blot analysis of recovered virulent viruses confirmed that they were recombinant E70DeltaNL genomes containing a 23- to 28-kb DNA fragment of the Malawi genome. These recombinants exhibited an unaltered MalDeltaNL disease and virulence phenotype when inoculated into swine. Additional in vivo marker rescue experiments identified a 20-kb fragment, encoding members of multigene families (MGF) 360 and 530, as being capable of fully restoring virulence to E70DeltaNL. Comparative nucleotide sequence analysis of the left variable region of the E70DeltaNL and Malawi Lil-20/1 genomes identified an 8-kb deletion in the E70DeltaNL isolate which resulted in the deletion and/or truncation of three MGF 360 genes and four MGF 530 genes. A recombinant MalDeltaNL deletion mutant lacking three members of each MGF gene family was constructed and evaluated for virulence in swine. The mutant virus replicated normally in macrophage cell culture but was avirulent in swine. Together, these results indicate that a region within the left variable region of the ASFV genome containing the MGF 360 and 530 genes represents a previously unrecognized virulence

  7. Novel Swine Virulence Determinant in the Left Variable Region of the African Swine Fever Virus Genome

    PubMed Central

    Neilan, J. G.; Zsak, L.; Lu, Z.; Kutish, G. F.; Afonso, C. L.; Rock, D. L.

    2002-01-01

    Previously we have shown that the African swine fever virus (ASFV) NL gene deletion mutant E70ΔNL is attenuated in pigs. Our recent observations that NL gene deletion mutants of two additional pathogenic ASFV isolates, Malawi Lil-20/1 and Pr4, remained highly virulent in swine (100% mortality) suggested that these isolates encoded an additional virulence determinant(s) that was absent from E70. To map this putative virulence determinant, in vivo marker rescue experiments were performed by inoculating swine with infection-transfection lysates containing E70 NL deletion mutant virus (E70ΔNL) and cosmid DNA clones from the Malawi NL gene deletion mutant (MalΔNL). A cosmid clone representing the left-hand 38-kb region (map units 0.05 to 0.26) of the MalΔNL genome was capable of restoring full virulence to E70ΔNL. Southern blot analysis of recovered virulent viruses confirmed that they were recombinant E70ΔNL genomes containing a 23- to 28-kb DNA fragment of the Malawi genome. These recombinants exhibited an unaltered MalΔNL disease and virulence phenotype when inoculated into swine. Additional in vivo marker rescue experiments identified a 20-kb fragment, encoding members of multigene families (MGF) 360 and 530, as being capable of fully restoring virulence to E70ΔNL. Comparative nucleotide sequence analysis of the left variable region of the E70ΔNL and Malawi Lil-20/1 genomes identified an 8-kb deletion in the E70ΔNL isolate which resulted in the deletion and/or truncation of three MGF 360 genes and four MGF 530 genes. A recombinant MalΔNL deletion mutant lacking three members of each MGF gene family was constructed and evaluated for virulence in swine. The mutant virus replicated normally in macrophage cell culture but was avirulent in swine. Together, these results indicate that a region within the left variable region of the ASFV genome containing the MGF 360 and 530 genes represents a previously unrecognized virulence determinant for domestic swine

  8. MEDCAN-GRO: Medical Capacity for African Nations - Growing Regional Operability A Case Study in Special Operations Forces Capacity Building.

    PubMed

    Givens, Melissa L; Verlo, April

    2015-01-01

    Medical Capacity for African Nations-Growing Regional Operability (MEDCAN-GRO) is a framework for addressing healthcare engagements that are intended to provide sustainable capacity building with partner nations. MEDCAN-GRO provides SOF units with a model that can be scaled to partner nation needs and aligned with the goals of the TSOC in an effort to enhance partner nation security. PMID:25770807

  9. Powerful methods for detecting introgressed regions from population genomic data.

    PubMed

    Rosenzweig, Benjamin K; Pease, James B; Besansky, Nora J; Hahn, Matthew W

    2016-06-01

    Understanding the types and functions of genes that are able to cross species boundaries-and those that are not-is an important step in understanding the forces maintaining species as largely independent lineages across the remainder of the genome. With large next-generation sequencing data sets we are now able to ask whether introgression has occurred across the genome, and multiple methods have been proposed to detect the signature of such events. Here, we introduce a new summary statistic that can be used to test for introgression, RNDmin , that makes use of the minimum pairwise sequence distance between two population samples relative to divergence to an outgroup. We find that our method offers a modest increase in power over other, related tests, but that all such tests have high power to detect introgressed loci when migration is recent and strong. RNDmin is robust to variation in the mutation rate, and remains reliable even when estimates of the divergence time between sister species are inaccurate. We apply RNDmin to population genomic data from the African mosquitoes Anopheles quadriannulatus and A. arabiensis, identifying three novel candidate regions for introgression. Interestingly, one of the introgressed loci is on the X chromosome, but outside of an inversion separating these two species. Our results suggest that significant, but rare, sharing of alleles is occurring between species that diverged more than 1 million years ago, and that application of these methods to additional systems are likely to reveal similar results. PMID:26945783

  10. Impact of burned areas on the northern African seasonal climate from the perspective of regional modeling

    NASA Astrophysics Data System (ADS)

    De Sales, Fernando; Xue, Yongkang; Okin, Gregory S.

    2015-02-01

    This study investigates the impact of burned areas on the surface energy balance and monthly precipitation in northern Africa as simulated by a state-of-the-art regional model. Mean burned area fraction derived from MODIS date of burning product was implemented in a set of 1-year long WRF-NMM/SSiB2 model simulations. Vegetation cover fraction and LAI were degraded daily based on mean burned area fraction and on the survival rate for each vegetation land cover type. Additionally, ground darkening associated with wildfire-induced ash and charcoal deposition was imposed through lower ground albedo for a period after burning. In general, wildfire-induced vegetation and ground condition deterioration increased mean surface albedo by exposing the brighter bare ground, which in turn caused a decrease in monthly surface net radiation. On average, the wildfire-season albedo increase was approximately 6.3 % over the Sahel. The associated decrease in surface available energy caused a drop in surface sensible heat flux to the atmosphere during the dry months of winter and early spring, which gradually transitioned to a more substantial decrease in surface evapotranspiration in April and May that lessened throughout the rainy season. Overall, post-fire land condition deterioration resulted in a decrease in precipitation over sub-Saharan Africa, associated with the weakening of the West African monsoon progression through the region. A decrease in atmospheric moisture flux convergence was observed in the burned area simulations, which played a dominant role in reducing precipitation in the area, especially in the months preceding the monsoon onset. The areas with the largest precipitation impact were those covered by savannas and rainforests, where annual precipitation decreased by 3.8 and 3.3 %, respectively. The resulting precipitation decrease and vegetation deterioration caused a drop in gross primary productivity in the region, which was strongest in late winter and early

  11. Climatology and dynamics of nocturnal low-level stratus over the southern West African monsoon region

    NASA Astrophysics Data System (ADS)

    Fink, A. H.; Schuster, R.; Knippertz, P.; van der Linden, R.

    2013-12-01

    The southern parts of West Africa, from the coast to about 10°N, are frequently covered by an extensive deck of shallow, low (200 - 400 m above ground) stratus or stratocumulus clouds during the summer monsoon season. These clouds usually form at night in association with a nocturnal low-level jet (NLLJ) and can persist into the early afternoon hours until they are dissipated or replaced by fair-weather cumuli. Recent work suggests that the stratus deck and its effect on the surface radiation balance are unsatisfactorily represented in standard satellite retrievals and simulations by state-of-the-art climate models. We will present the first ever climatology of the diurnal cycle of the low cloud deck based on surface observations and satellite products. In addition, we use high-resolution regional simulations with the Weather Research and Forecast (WRF) model and observations from the African Monsoon Multidisciplinary Analysis (AMMA) 2006 campaign to investigate (a) the spatiotemporal distribution, (b) the influence on the radiation balance, and (c) the detailed formation and maintenance mechanisms of the stratiform clouds as simulated by the model. The model configuration used for this study has been determined following an extensive sensitivity study, which has shown that at least some configurations of WRF satisfactorily reproduce the diurnal cycle of the low cloud evolution. The main conclusions are: (a) The observed stratus deck forms after sunset along the coast, spreads inland in the course of the night, reaches maximum poleward extent at about 10°N around 09-10 local time and dissipates in the early afternoon. (b) The average surface net radiation balance in stratus-dominated regions is 35 W m-2 lower than in those with less clouds. (c) The cloud formation is related to a subtle balance between 'stratogenic' upward (downward) fluxes of latent (sensible) heat caused by shear-driven turbulence below the NLLJ, cold advection from the ocean, forced lifting at

  12. Oral Health Inequalities between Rural and Urban Populations of the African and Middle East Region.

    PubMed

    Ogunbodede, E O; Kida, I A; Madjapa, H S; Amedari, M; Ehizele, A; Mutave, R; Sodipo, B; Temilola, S; Okoye, L

    2015-07-01

    Although there have been major improvements in oral health, with remarkable advances in the prevention and management of oral diseases, globally, inequalities persist between urban and rural communities. These inequalities exist in the distribution of oral health services, accessibility, utilization, treatment outcomes, oral health knowledge and practices, health insurance coverage, oral health-related quality of life, and prevalence of oral diseases, among others. People living in rural areas are likely to be poorer, be less health literate, have more caries, have fewer teeth, have no health insurance coverage, and have less money to spend on dental care than persons living in urban areas. Rural areas are often associated with lower education levels, which in turn have been found to be related to lower levels of health literacy and poor use of health care services. These factors have an impact on oral health care, service delivery, and research. Hence, unmet dental care remains one of the most urgent health care needs in these communities. We highlight some of the conceptual issues relating to urban-rural inequalities in oral health, especially in the African and Middle East Region (AMER). Actions to reduce oral health inequalities and ameliorate rural-urban disparity are necessary both within the health sector and the wider policy environment. Recommended actions include population-specific oral health promotion programs, measures aimed at increasing access to oral health services in rural areas, integration of oral health into existing primary health care services, and support for research aimed at informing policy on the social determinants of health. Concerted efforts must be made by all stakeholders (governments, health care workforce, organizations, and communities) to reduce disparities and improve oral health outcomes in underserved populations. PMID:26101336

  13. Cattle ticks in Cameroon: is Rhipicephalus (Boophilus) microplus absent in Cameroon and the Central African region?

    PubMed

    Awa, D N; Adakal, H; Luogbou, N D D; Wachong, K H; Leinyuy, I; Achukwi, M D

    2015-03-01

    In most parts of the world, ticks are rapidly developing resistance to commonly used acaricides thus rendering control difficult. This constraint is further compounded by the introduction of new species in areas where they did not exist before. Such is the case with the introduction into and rapid spread of Rhipicephalus (Boophilus) microplus in some countries of West Africa. With the looming threat of its further spread in the region, the objective of the present study was to update knowledge on cattle ticks in Cameroon. Among 19,189 ticks collected monthly from 60 animals in 5 herds from March 2012 to February 2013, Rh. (B.) decoloratus was the most abundant species with a relative prevalence of 62.2%, followed by Amblyomma variegatum (28.4%), Rh. (B.) annulatus (0.2%), Rh. (B.) geigyi (0.03%), other Rhipicephalus spp. (8.4%) and Hyalomma spp. (0.3%). Rh. (B.) decoloratus and A. variegatum were also the most widely distributed in space. Infestation rate was generally high, with average tick count/animal of about 80 during peak periods. Tick distribution and abundance in the different sites was as varied as the underlying factors, among which the most important were management systems and climatic factors. The effects of rainfall and temperature were confounded by other factors and difficult to evaluate. However, it appears tick development depends among other factors, on a humidity threshold, above which there is not much more effect. Rh. microplus was not found during this study, but more extensive tick collections have to be done to confirm this. In conclusion, cattle tick infestation in Cameroon remains an important cause for concern. Farmers need assistance in the use and management of acaricides in order to increase their efficiency and reduce the development of resistance. Although Rh. microplus was not found, its introduction from other West African countries is imminent if adequate measures, especially in the control and limitation of animal movements

  14. Modelling of ionospheric irregularities during geomagnetic storms over African low latitude region

    NASA Astrophysics Data System (ADS)

    Mungufeni, Patrick

    2016-07-01

    In this study, empirical models of occurrence of ionospheric irregularities over low latitude African region during geomagnetic storms have been developed. The geomagnetic storms considered consisted of Dst ≤ -50 nT. GNSS-derived ionospheric Total Electron Content (TEC) data over Libreville, Gabon (NKLG) (0.35° N, 9.68° E, geographic, 8.05° S, magnetic) and Malindi, Kenya (MAL2) (2.99° S, 40.19° E, geographic, 12.42° S, magnetic) during 2000 - 2014 were used. Ionospheric irregularities at scale- lengths of a few kilometers and ˜400 m were represented with the rate of change of TEC index (ROTI). The inputs for the models are the local time, solar flux index, Auroral Electrojet index, day of the year, and the Dst index, while the output is the median ROTI during these given conditions. To develop the models, the ROTI index values were binned based on the input parameters and cubic B splines were then fitted to the binned data. Developed models using data over NKLG and MAL2 were validated with independent data over stations within 510 km and 680 km radius, respectively. The models captured the enhancements and inhibitions of the occurrence of the ionospheric irregularities during the storm period. The models even emulated these patterns in the various seasons, during medium and high solar activity conditions. The correlation coefficients for the validations were statistically significant and ranged from 0.58 - 0.73, while the percentage of the variance in the observed data explained by the modelled data ranged from 34 - 53.

  15. The Rising Burden of Diabetes and Hypertension in Southeast Asian and African Regions: Need for Effective Strategies for Prevention and Control in Primary Health Care Settings

    PubMed Central

    Mohan, Viswanathan; Seedat, Yackoob K.; Pradeepa, Rajendra

    2013-01-01

    Aim. To review the available literature on burden of diabetes mellitus (DM) and hypertension (HTN) and its coexistence in Southeast Asian (SEA) and the African (AFR) regions and to suggest strategies to improve DM and HTN prevention and control in primary health care (PHC) in the two regions. Methods. A systematic review of the papers published on DM, HTN, and prevention/control of chronic diseases in SEA and AFR regions between 1980 and December 2012 was included. Results. In the year 2011, SEA region had the second largest number of people with DM (71.4 million), while the AFR region had the smallest number (14.7 million). Screening studies identified high proportions (>50%) of individuals with previously undiagnosed HTN and DM in both of the SEA and AFR regions. Studies from both regions have shown that DM and HTN coexist in type 2 DM ranging from 20.6% in India to 78.4% in Thailand in the SEA region and ranging from 9.7% in Nigeria to 70.4% in Morocco in the AFR region. There is evidence that by lifestyle modification both DM and HTN can be prevented. Conclusion. To meet the twin challenge of DM and HTN in developing countries, PHCs will have to be strengthened with a concerted and multipronged effort to provide promotive, preventive, curative, and rehabilitative services. PMID:23573413

  16. Establishing a Functional Link Between African Dust and Region-wide Coral Reef Decline

    NASA Astrophysics Data System (ADS)

    Hayes, M. L.; Barber, R. T.

    2003-12-01

    For nearly thirty years, coral reefs in the Western Atlantic and Caribbean basin have experienced historically unprecedented declines. Algal blooms, mass coral bleaching, disease outbreaks and shifts in the dominance of benthic coral-competitors were first documented in the 1970s and have increased in frequency, intensity, variety and range over the past two decades. Recent studies of decreasing coral cover document regional losses averaging nearly 80% over this period. Here, we provide experimental evidence that increased supplies of iron-rich eolian dust from Africa to typically iron-poor marine environments throughout the region could have played a key role in these profound changes. Atmospheric inputs of "new" micronutrients, especially iron, have the potential to overcome limitations to the growth of opportunistic coral-competitors and the virulence of coral pathogens. Microcosm and mesocosm experiments with a putative bacterial pathogen of stony corals, Aurantimonas coralicida, and a temperate stony coral, Oculina arbuscula, provide a means to test the functional relationship between iron availability, microbial growth and coral health. Iron limitation of A. coralicida growth rates is readily induced by the addition of synthetic chelators such as 2,2' Dipyridyl to bacterial cultures at relatively low concentrations (e.g. 10 μ M). This growth limitation is reversed by 100 nM over-enrichments of pure reagent-grade iron as well as iron-rich "synthetic dust" derived from African lake-bed sediments. The Chrome-azurol S assay demonstrates that A. coralicida also synthesizes high-affinity iron-capture mechanisms (i.e. siderophores) that may serve as critical determinants of virulence. Finally, our experimental mesocosms are based on oligotrophic Mediterranean seawater and permit controlled experimentation under relatively low iron ( ˜5 nM) conditions. Using this system, denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified ribosomal DNA

  17. Modelling the probability of ionospheric irregularity occurrence over African low latitude region

    NASA Astrophysics Data System (ADS)

    Mungufeni, Patrick; Jurua, Edward; Bosco Habarulema, John; Anguma Katrini, Simon

    2015-06-01

    This study presents models of geomagnetically quiet time probability of occurrence of ionospheric irregularities over the African low latitude region. GNSS-derived ionospheric total electron content data from Mbarara, Uganda (0.60°S, 30.74°E, geographic, 10.22°S, magnetic) and Libreville, Gabon (0.35°N, 9.68°E, geographic, 8.05°S, magnetic) during the period 2001-2012 were used. First, we established the rate of change of total electron content index (ROTI) value associated with background ionospheric irregularity over the region. This was done by analysing GNSS carrier-phases at L-band frequencies L1 and L2 with the aim of identifying cycle slip events associated with ionospheric irregularities. We identified at both stations a total of 699 events of cycle slips. The corresponding median ROTI value at the epochs of the cycle slip events was 0.54 TECU/min. The probability of occurrence of ionospheric irregularities associated with ROTI ≥ 0.5 TECU / min was then modelled by fitting cubic B-splines to the data. The aspects the model captured included diurnal, seasonal, and solar flux dependence patterns of the probability of occurrence of ionospheric irregularities. The model developed over Mbarara was validated with data over Mt. Baker, Uganda (0.35°N, 29.90°E, geographic, 9.25°S, magnetic), Kigali, Rwanda (1.94°S, 30.09°E, geographic, 11.62°S, magnetic), and Kampala, Uganda (0.34°N, 32.60°E, geographic, 9.29°S, magnetic). For the period validated at Mt. Baker (approximately, 137.64 km, north west), Kigali (approximately, 162.42 km, south west), and Kampala (approximately, 237.61 km, north east) the percentages of the number of errors (difference between the observed and the modelled probability of occurrence of ionospheric irregularity) less than 0.05 are 97.3, 89.4, and 81.3, respectively.

  18. Low latitude nighttime ionospheric vertical E × B drifts at African region

    NASA Astrophysics Data System (ADS)

    Adebesin, B. O.; Adeniyi, J. O.; Adimula, I. A.; Reinisch, B. W.

    2013-12-01

    The nighttime vertical E × B drifts velocities of the F2-region were inferred from the hourly hmF2 values obtained from ionosonde data over an African equatorial station, Ilorin (8.50oN, 4.68oE; dip lat. 2.95o) during period of low solar activity. For each season, the plasma drift Vz is characterized by an evening upward enhancement, then by a downward reversal at 1900 LT till around 0000 LT, except for June solstice. This was explained using the Rayleigh-Taylor (R-T) instability mechanism. The occasional drift differences in Vz obtained by inferred and direct measurement over Ilorin and Jicamarca, respectively are reflective of the importance of chemistry and divergent transport system due to both the E region electric and magnetic fields instead of simple motions. The pre-reversal enhancement (PRE) magnitude is higher during the equinoctial months than the solsticial months over Jicamarca, highest during December solstice and the equinoctial months over Ilorin, suggesting the dominance of higher E × B fountain during equinoxes at both stations. The lowest PRE magnitude was in June solstice. The appearance of post-noon peak in NmF2 around 1700 LT is highest during the equinoctial months and lowest during the solsticial period. A general sharp drop in NmF2 around 1800 LT is distinct immediately after sunset, lowest during June solstice and highest in March equinox. Our result suggests that between 0930 and 2100 LT, the general theory that vertical drifts obtained by digisonde measurements only match the E × B drift if the F layer is higher than 300 km is reliable, but does not hold for the nighttime period of 2200-0600 LT under condition of solar minima. Hence, the condition may not be sufficient for the representation of vertical plasma drift at nighttime during solar minima. This assertion may still be tentative, as more equatorial stations needed to be studied for better confirmation.

  19. Global and Regional-scale Sst Variability and West African Monsoon. The Role of The Indian Ocean : A Numerical Study

    NASA Astrophysics Data System (ADS)

    Trzaska, S.; Fontaine, B.; Janicot, S.

    Interannual to decadal variability of the West African Monsoon has been commonly linked to Tropical Atlantic and Pacific SST variabilities (so called "Atlantic Dipole" and ENSO). Tropical Atlantic is thought to affect West African Monsoon via modi- fication of low-level thermal gradients driving the monsoon thus the location of the rainbelt over the continent. Warm events in the easten Pacific may affect it via up- per level zonal circulation and eventual subsidence over West Africa. However the teleconnections seem to have modified through time : main association with tropi- cal Atlantic during 50's and 60's i.e. the wetter period vs stronger association with ENSO and relative disconnection with tropical Atlantic during recent, dry decades. The role of the Indian Ocean has not been much investigated so far. The variability of this basin is dominated by a slow warming trend which compares well with the global warming. This study is aimed at investigating the possible effects of the Indian Ocean warming on the West African Monsoon dynamics and its teleconnections to ENSO and Tropical Atlantic. It is shown that this warming can potentially modify circulation anomalies related to ENSO in the Atlantic-African region by limiting the zonal extent of the zonal circulation anomalies and shifting the main subsidence branch to Africa and central Atlantic. In non-ENSO case monsoon circulation seems also to have more zonal orientation. The results are documented in the divergent circulation frame since it allows to unify a regional view of the monsoon as a meridional overturning with the global effects of ENSO in the zonal circulation. Modifications in the low-level moisture flux are also presented.

  20. In Order to Teach Me, You Have to Know Me: A Mixed-Methods Study of African-American Male Classroom Engagement

    ERIC Educational Resources Information Center

    Henderson, Jack L.

    2013-01-01

    Nationally, 30% of high school students do not graduate. Among this percentage, 50% are African-American. This study focused on at-promise African-American male classroom engagement where the researcher employed a mixed-methods methodology. Findings reveal that in order to engage and keep at-promise African-American males in high school, educators…

  1. Early Holocenic and Historic mtDNA African Signatures in the Iberian Peninsula: The Andalusian Region as a Paradigm

    PubMed Central

    Hernández, Candela L.; Soares, Pedro; Dugoujon, Jean M.; Novelletto, Andrea; Rodríguez, Juan N.; Rito, Teresa; Oliveira, Marisa; Melhaoui, Mohammed; Baali, Abdellatif; Pereira, Luisa; Calderón, Rosario

    2015-01-01

    Determining the timing, identity and direction of migrations in the Mediterranean Basin, the role of “migratory routes” in and among regions of Africa, Europe and Asia, and the effects of sex-specific behaviors of population movements have important implications for our understanding of the present human genetic diversity. A crucial component of the Mediterranean world is its westernmost region. Clear features of transcontinental ancient contacts between North African and Iberian populations surrounding the maritime region of Gibraltar Strait have been identified from archeological data. The attempt to discern origin and dates of migration between close geographically related regions has been a challenge in the field of uniparental-based population genetics. Mitochondrial DNA (mtDNA) studies have been focused on surveying the H1, H3 and V lineages when trying to ascertain north-south migrations, and U6 and L in the opposite direction, assuming that those lineages are good proxies for the ancestry of each side of the Mediterranean. To this end, in the present work we have screened entire mtDNA sequences belonging to U6, M1 and L haplogroups in Andalusians—from Huelva and Granada provinces—and Moroccan Berbers. We present here pioneer data and interpretations on the role of NW Africa and the Iberian Peninsula regarding the time of origin, number of founders and expansion directions of these specific markers. The estimated entrance of the North African U6 lineages into Iberia at 10 ky correlates well with other L African clades, indicating that U6 and some L lineages moved together from Africa to Iberia in the Early Holocene. Still, founder analysis highlights that the high sharing of lineages between North Africa and Iberia results from a complex process continued through time, impairing simplistic interpretations. In particular, our work supports the existence of an ancient, frequently denied, bridge connecting the Maghreb and Andalusia. PMID:26509580

  2. Early Holocenic and Historic mtDNA African Signatures in the Iberian Peninsula: The Andalusian Region as a Paradigm.

    PubMed

    Hernández, Candela L; Soares, Pedro; Dugoujon, Jean M; Novelletto, Andrea; Rodríguez, Juan N; Rito, Teresa; Oliveira, Marisa; Melhaoui, Mohammed; Baali, Abdellatif; Pereira, Luisa; Calderón, Rosario

    2015-01-01

    Determining the timing, identity and direction of migrations in the Mediterranean Basin, the role of "migratory routes" in and among regions of Africa, Europe and Asia, and the effects of sex-specific behaviors of population movements have important implications for our understanding of the present human genetic diversity. A crucial component of the Mediterranean world is its westernmost region. Clear features of transcontinental ancient contacts between North African and Iberian populations surrounding the maritime region of Gibraltar Strait have been identified from archeological data. The attempt to discern origin and dates of migration between close geographically related regions has been a challenge in the field of uniparental-based population genetics. Mitochondrial DNA (mtDNA) studies have been focused on surveying the H1, H3 and V lineages when trying to ascertain north-south migrations, and U6 and L in the opposite direction, assuming that those lineages are good proxies for the ancestry of each side of the Mediterranean. To this end, in the present work we have screened entire mtDNA sequences belonging to U6, M1 and L haplogroups in Andalusians--from Huelva and Granada provinces--and Moroccan Berbers. We present here pioneer data and interpretations on the role of NW Africa and the Iberian Peninsula regarding the time of origin, number of founders and expansion directions of these specific markers. The estimated entrance of the North African U6 lineages into Iberia at 10 ky correlates well with other L African clades, indicating that U6 and some L lineages moved together from Africa to Iberia in the Early Holocene. Still, founder analysis highlights that the high sharing of lineages between North Africa and Iberia results from a complex process continued through time, impairing simplistic interpretations. In particular, our work supports the existence of an ancient, frequently denied, bridge connecting the Maghreb and Andalusia. PMID:26509580

  3. The burden of natural and technological disaster-related mortality on gross domestic product (GDP) in the WHO African region.

    PubMed

    Kirigia, Joses M; Sambo, Luis G; Aldis, W; Mwabu, Germano M

    2002-01-01

    The WHO Africa region has the highest disaster mortality rate compared to the other five regions of the organization. Those deaths are hypothesized to have significantly negative effect on per capita gross domestic product (GDP). The objective of this study was to estimate the loss in GDP attributable to natural and technological disaster-related mortality in the WHO African Region. We estimated the impact of disaster-related mortality on GDP using double-log econometric model and cross-sectional data (from the UNDP and the World Bank publications) on 45 out of 46 countries in the WHO African Region. The coefficients for capital (K), educational enrolment (EN), life expectancy (LE) and exports (X) had a positive sign; while imports (M) and disaster mortality (DS) were found to impact negatively on GDP. The abovementioned explanatory variables were found to have statistically significant effect on GDP at 5% level in a t-distribution test. Disaster mortality of a single person was found to reduce GDP by US$0.018. We have demonstrated that disaster mortality has a significant negative effect on GDP. Thus, as policy-makers strive to increase GDP through capital investment, export promotion and increase in educational enrolment, they should always recall that investments in strengthening national capacity to mitigate the effects of national disasters expeditiously and effectively shall yield significant economic returns. PMID:17298162

  4. Seismicity Patterns and Magmatic Processes in the Rwenzori Region, East-African Rift

    NASA Astrophysics Data System (ADS)

    Lindenfeld, M.; Rumpker, G.; Schmeling, H.; Wallner, H.

    2010-12-01

    The 5000m high Rwenzori Mountains are situated within the western branch of the East African Rift System (EARS), at the border between Uganda and the Democratic Republic of Congo. They represent a basement block located within the rift valley whose origin and relation to the evolution of the EARS are highly puzzling. During a recent seismological campaign we located more than 800 earthquakes per month with magnitudes ranging from 0.5 to 5.1. Vertical sections across the northern parts of the Rwenzoris show, that west of the mountains (towards the rift valley) the focal depths range from 10 to 20 km, whereas the hypocentres go as deep as 30 km on the eastern side. This is in good agreement with Moho-depths derived from receiver functions and implies that all of these events are located within the crust. However, about 30 km east of the northern mountain ridge we located a cluster of 7 events that exhibit an anomalous depth of about 60 km. We can confidently locate these earthquakes within the mantle lithosphere beneath the rift. The existence of earthquakes at this depth is enigmatic, especially within a rifting regime were one expects hot and weak material relatively close to the surface. We think that these events are possibly related to the evolution of the Rwenzori Mountains. A recent hypothesis to explain the extreme uplift of the Rwenzori Mountains is rift induced delamination (RID) of mantle lithosphere. Here we show that the RID-process is indeed capable of explaining the seismic energy release in the mantle. However, in view of the specific hypocentral location of the event cluster, magmatic impregnation processes associated with dyke propagation into the mantle lithosphere may be a more realistic cause for seismic radiation at the observed depth. Crustal earthquakes northeast of the Rwenzori area are relocated with a double-difference algorithm to improve the spatial resolution of seismicity pattern. Several event clusters in the vicinity of the Fort

  5. Explaining the Ordinary Magic of Stable African Multilingualism in the Vaal Triangle Region in South Africa

    ERIC Educational Resources Information Center

    Coetzee-Van Rooy, Susan

    2014-01-01

    The academic and public debates about language maintenance and language shift in the post-1994 South Africa distract attention from the more productive and important endeavour of explaining the nature of the multilingualism observed among users of African languages in urban contexts. An explanation for this phenomenon is offered here, based on…

  6. Examining science achievement of African American females in suburban middle schools: A mixed methods study

    NASA Astrophysics Data System (ADS)

    Topping, Kecia C.

    This dissertation examined factors that affected the science achievement of African American females in suburban middle schools. The research literature informed that African American females are facing the barriers of race, gender, socioeconomic status, and cultural learning style preferences. Nationally used measurements of science achievement such as the Standardized Achievement Test, Tenth edition (SAT-10), National Assessment for Educational Progress, and National Center for Educational Statistics showed that African American females are continuing to falter in the areas of science when compared to other ethnic groups. This study used a transformative sequential explanatory mixed methods design. In the first, quantitative, phase, the relationships among the dependent variables, science subscale SAT-10 NCE scores, yearly averages, and the independent variables, attitude toward science scores obtained from the Modified Fennema-Sherman Attitudes toward Science Scale, socioeconomics, and caregiver status were tested. The participants were 150 African American females in grades 6 through 8 in four suburban middle schools located in the Southeastern United States. The results showed a positive, significant linear relationship between the females' attitude and their science subscale SAT-10 NCE scores and a positive, significant linear relationship between the females' attitudes and their yearly averages in science. The results also confirmed that attitude was a significant predictor of science subscale SAT-10 NCE scores for these females and that attitude and socioeconomics were significant predictors of the females' yearly averages in science. In the second, qualitative, phase, nine females purposefully selected from those who had high and low attitude towards science scores on the scale in the quantitative phase were interviewed. The themes that emerged revealed seven additional factors that impacted the females' science achievement. They were usefulness of science

  7. African American Organ Donor Registration: A Mixed Methods Design using the Theory of Planned Behavior

    PubMed Central

    DuBay, Derek A.; Ivankova, Nataliya; Herby, Ivan; Wynn, Theresa A.; Kohler, Connie; Berry, Beverly; Foushee, Herman; Carson, April; Redden, David T.; Holt, Cheryl; Siminoff, Laura; Fouad, Mona; Martin, Michelle Y.

    2015-01-01

    Context A large racial disparity exists in organ donation. Objective The purpose of this study was to identify factors associated with becoming a registered organ donor in among African Americans in Alabama. Methods The study utilized a concurrent mixed methods design guided by the Theory of Planned Behavior to analyze African American’s decisions to become a registered organ donor using both qualitative (focus groups) and quantitative (survey) methods. Results The sample consisted of 22 registered organ donors (ROD) and 65 non-registered participants (NRP) from six focus groups completed in urban (n=3) and rural (n=3) areas. Participants emphasized the importance of the autonomy to make one’s own organ donation decision and have this decision honored posthumously. One novel barrier to becoming a ROD was the perception that organs from African Americans were often unusable due to high prevalence of chronic medical conditions such as diabetes and hypertension. Another novel theme discussed as an advantage to becoming a ROD was the subsequent motivation to take responsibility for one’s health. Family and friends were the most common groups of persons identified as approving and disapproving of the decision to become a ROD. The most common facilitator to becoming a ROD was information, while fear and the lack of information were the most common barriers. In contrast, religious beliefs, mistrust and social justice themes were infrequently referenced as barriers to becoming a ROD. Discussion Findings from this study may be useful for prioritizing organ donation community-based educational interventions in campaigns to increase donor registration. PMID:25193729

  8. Modeling geomagnetically induced currents in the South African power transmission network using the finite element method

    NASA Astrophysics Data System (ADS)

    Matandirotya, Electdom; Cilliers, Pierre J.; Van Zyl, Robert R.

    2015-03-01

    Geomagnetically induced currents (GIC) are a result of time variations of the geomagnetic field, which induce a geoelectric field at the Earth's surface. Geomagnetic perturbations are enhanced during adverse space weather events called geomagnetic storms. All ground-based conductor networks can be affected by GIC during such events. As a way of assessing the magnitude of GIC expected in a particular technological system, models are developed, in which the computation of the induced geoelectric field is a key step. Computation of GIC in the South African power transmission network has so far been done using a uniform Earth model and improved using a layered Earth conductivity profile. In this work we present geoelectric field results obtained by using the finite element method (FEM) and improved GIC estimates using a realistic conductivity profile, magnetic field data interpolated from two South African observatories, and a new method for estimating the network coefficients, a and b, which map the north-south and east-west electric fields to their respective GIC components. The performance of the chosen FEM model demonstrates that it is an effective tool for GIC modeling. Unlike previous engineering techniques, our method for estimating the a and b coefficients from GIC and measured magnetic field data gives results that are independent of prior knowledge of the network configuration. The GIC estimated using the a and b coefficients obtained from the proposed method compares well with the measured GIC during the late October 2003 geomagnetic storm.

  9. Assessment of uncertainties in the response of the African monsoon precipitation to land use change simulated by a regional model

    SciTech Connect

    Hagos, Samson M.; Leung, Lai-Yung Ruby; Xue, Yongkang; Boone, Aaron; de Sales, Fernando; Neupane, Naresh; Huang, Maoyi; Yoon, Jin -Ho

    2014-02-22

    Land use and land cover over Africa have changed substantially over the last sixty years and this change has been proposed to affect monsoon circulation and precipitation. This study examines the uncertainties on the effect of these changes on the African Monsoon system and Sahel precipitation using an ensemble of regional model simulations with different combinations of land surface and cumulus parameterization schemes. Furthermore, the magnitude of the response covers a broad range of values, most of the simulations show a decline in Sahel precipitation due to the expansion of pasture and croplands at the expense of trees and shrubs and an increase in surface air temperature.

  10. Impact of GCM boundary forcing on regional climate modeling of West African summer monsoon precipitation and circulation features

    NASA Astrophysics Data System (ADS)

    Kebe, Ibourahima; Sylla, Mouhamadou Bamba; Omotosho, Jerome Adebayo; Nikiema, Pinghouinde Michel; Gibba, Peter; Giorgi, Filippo

    2016-05-01

    In this study, the latest version of the International Centre for Theoretical Physics Regional Climate Model (RegCM4) driven by three CMIP5 Global Climate Models (GCMs) is used at 25 km grid spacing over West Africa to investigate the impact of lateral boundary forcings on the simulation of monsoon precipitation and its relationship with regional circulation features. We find that the RegCM4 experiments along with their multimodel ensemble generally reproduce the location of the main precipitation characteristics over the region and improve upon the corresponding driving GCMs. However, the provision of different forcing boundary conditions leads to substantially different precipitation magnitudes and spatial patterns. For instance, while RegCM4 nested within GFDL-ESM-2M and HadGEM2-ES exhibits some underestimations of precipitation and an excessively narrow Intertropical Convergence Zone, the MPI-ESM-MR driven run produces precipitation spatial distribution and magnitudes more similar to observations. Such a superior performance originates from a much better simulation of the interactions between baroclinicity, temperature gradient and African Easterly Jet along with an improved connection between the Isentropic Potential Vorticity, its gradient and the African Easterly Waves dynamics. We conclude that a good performing GCM in terms of monsoon dynamical features (in this case MPI-ESM-MR) is needed to drive RCMs in order to achieve a better representation of the West Africa summer monsoon precipitation.

  11. The mitochondrial landscape of African Americans: An examination of more than 2500 control region haplotypes from 22 U.S. locations.

    PubMed

    Scheible, M; Just, R; Sturk-Andreaggi, K; Saunier, J; Parson, W; Parsons, T; Coble, M; Irwin, J

    2016-05-01

    The mitochondrial DNA (mtDNA) control region (16024-576) was Sanger-sequenced for a total of 2563 self-identified African Americans, using automated processing techniques and data review standards exceeding guidelines for forensic applications. Genetic diversity ranged from 0.9952 to 0.9998 in 22 population samples from 20 different states. Haplogroups of African ancestry, found in 82.48% of individuals overall, were most concentrated in the Southeast U.S. and decreased to the north and west. West African and West Central African haplotypes were well-represented in the population samples, especially in the southern U.S. states, while East African haplogroups were observed in low-frequency clusters in a handful of locations across the country. East Asian, Native American, and West Eurasian admixture was present in 3.16%, 2.93%, and 11.43% of samples, respectively. While some geographic substructure was detected across the population samples as clines in admixture frequencies, 20 of the 22 population samples were found to be statistically indistinguishable by pairwise comparisons and AMOVA calculations. Datasets from Hawaii and Idaho, however, were clear outliers. Overall, these more than 2500 control region sequences represent the most comprehensive regional sampling of African American mtDNA diversity to date, and are suitable for use in a forensic mtDNA database. The population data are made available via EMPOP (www.empop.org) and GenBank. PMID:26919661

  12. Novel Use of Hydroxyurea in an African Region With Malaria: Protocol for a Randomized Controlled Clinical Trial

    PubMed Central

    Anyanwu, Juliana N; Williams, Olatundun; Sautter, Casey L; Kasirye, Phillip; Hume, Heather; Opoka, Robert O; Latham, Teresa; Ndugwa, Christopher; Ware, Russell E

    2016-01-01

    Background Sickle cell anemia (SCA), one of most prevalent monogenic diseases worldwide, is caused by a glutamic acid to valine substitution on the beta globin protein of hemoglobin, which leads to hemolytic anemia. Hydroxyurea, the only disease-modifying therapy approved by the Food and Drug Administration for SCA, has proven to be a viable therapeutic option for SCA patients in resource-rich settings, given clinical improvements experienced while taking the medication and its once-daily oral dosing. Significant studies have demonstrated its safety and clinical efficacy among children and adults in developed countries. In Sub-Saharan Africa, however, the risk of malaria, hematologic toxicities, and safety of hydroxyurea in children with SCA living in malaria-endemic areas are unknown. Objectives Study objectives include determining the incidence of malaria in SCA patients taking hydroxyurea versus placebo; establishing the frequency of hematologic toxicities and adverse events (AEs) in children with SCA treated with hydroxyurea versus placebo; and defining the relationships between hydroxyurea treatment and fetal hemoglobin, soluble intracellular adhesion molecule-1, and nitric oxide levels, and between levels of these factors and risk of subsequent malaria. Methods Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM, NCT01976416) is a prospective, randomized, placebo-controlled, double-blinded phase III trial to compare risk of malaria with oral hydroxyurea versus placebo. Children will be recruited from the Mulago Hospital Sickle Cell Clinic in Kampala, Uganda. Results Two hundred Ugandan children aged between 1.00 and 3.99 years with confirmed SCA will be randomized into treatment groups by order of entry in the study, based on a predetermined blinded randomization list. The primary outcome of the trial is malaria incidence in the 2 study groups, defined as episodes of clinical malaria occurring over the 1-year randomized study treatment period

  13. Ocean Pollution as a Result of Onshore Offshore Petroleum Activities in the African Gulf of Guinea Region

    NASA Astrophysics Data System (ADS)

    Abubakar, B.

    2007-05-01

    increasing cases of pollution of farmlands, rivers, wells and the environment in general. Apart from all these, what is even becoming more worrisome is that none of all these oil firms operating in the region is able to account on how it disposes its industrial toxic waste generated as a result of its industrial activities within the region. Finally Geological strata are adversely destroyed by seismographic activities, Sea creatures are destroyed by oil pollution and Means of livelihood of revering dwellers are often threatened by pollution. RECOMMENDATIONS After identifying how the pollution in the Gulf of Guinea region is increasing in relation to the increasing petroleum activities, I have come up with the following suggestions/recommendations. 1. AFRICAN UNION RESOLUTION The Organization of the Petroleum Exporting Countries (OPEC) in conjunction with the International Atomic Energy Agency (IAEA) should use their capacity to be able to influence the African Union (AU) to pass a resolution banning the illegal dumping of radioactive waste, Gas flaring and Costal bunkering in this part of the world. 2. RESEARCH AND INVESTIGATION The Organization of the Petroleum Exporting Countries, in conjunction with the United Nations Environmental Agency, the International Atomic Energy Agency and with the corporation of the African Union should send team of researchers to come and investigate this trend on petroleum pollution in the Gulf of Guinea region and proffer possible solutions in checking the menace.

  14. Managed European-Derived Honey Bee, Apis mellifera sspp, Colonies Reduce African-Matriline Honey Bee, A. m. scutellata, Drones at Regional Mating Congregations.

    PubMed

    Mortensen, Ashley N; Ellis, James D

    2016-01-01

    African honey bees (Apis mellifera scutellata) dramatically changed the South American beekeeping industry as they rapidly spread through the Americas following their introduction into Brazil. In the present study, we aimed to determine if the management of European-derived honey bees (A. mellifera sspp.) could reduce the relative abundance of African-matriline drones at regional mating sites known as drone congregation areas (DCAs). We collected 2,400 drones at six DCAs either 0.25 km or >2.8 km from managed European-derived honey bee apiaries. The maternal ancestry of each drone was determined by Bgl II enzyme digestion of an amplified portion of the mitochondrial Cytochrome b gene. Furthermore, sibship reconstruction via nuclear microsatellites was conducted for a subset of 1,200 drones to estimate the number of colonies contributing drones to each DCA. Results indicate that DCAs distant to managed European apiaries (>2.8 km) had significantly more African-matriline drones (34.33% of the collected drones had African mitochondrial DNA) than did DCAs close (0.25 km) to managed European apiaries (1.83% of the collected drones had African mitochondrial DNA). Furthermore, nuclear sibship reconstruction demonstrated that the reduction in the proportion of African matriline drones at DCAs near apiaries was not simply an increase in the number of European matriline drones at the DCAs but also the result of fewer African matriline colonies contributing drones to the DCAs. Our data demonstrate that the management of European honey bee colonies can dramatically influence the proportion of drones with African matrilines at nearby drone congregation areas, and would likely decreasing the probability that virgin European queens will mate with African drones at those drone congregation areas. PMID:27518068

  15. Patterns of sequence divergence and evolution of the S orthologous regions between Asian and African cultivated rice species.

    PubMed

    Guyot, Romain; Garavito, Andrea; Gavory, Frédérick; Samain, Sylvie; Tohme, Joe; Ghesquière, Alain; Lorieux, Mathias

    2011-01-01

    A strong postzygotic reproductive barrier separates the recently diverged Asian and African cultivated rice species, Oryza sativa and O. glaberrima. Recently a model of genetic incompatibilities between three adjacent loci: S(1)A, S(1) and S(1)B (called together the S(1) regions) interacting epistatically, was postulated to cause the allelic elimination of female gametes in interspecific hybrids. Two candidate factors for the S(1) locus (including a putative F-box gene) were proposed, but candidates for S(1)A and S(1)B remained undetermined. Here, to better understand the basis of the evolution of regions involved in reproductive isolation, we studied the genic and structural changes accumulated in the S(1) regions between orthologous sequences. First, we established an 813 kb genomic sequence in O. glaberrima, covering completely the S(1)A, S(1) and the majority of the S(1)B regions, and compared it with the orthologous regions of O. sativa. An overall strong structural conservation was observed, with the exception of three isolated regions of disturbed collinearity: (1) a local invasion of transposable elements around a putative F-box gene within S(1), (2) the multiple duplication and subsequent divergence of the same F-box gene within S(1)A, (3) an interspecific chromosomal inversion in S(1)B, which restricts recombination in our O. sativa×O. glaberrima crosses. Beside these few structural variations, a uniform conservative pattern of coding sequence divergence was found all along the S(1) regions. Hence, the S(1) regions have undergone no drastic variation in their recent divergence and evolution between O. sativa and O. glaberrima, suggesting that a small accumulation of genic changes, following a Bateson-Dobzhansky-Muller (BDM) model, might be involved in the establishment of the sterility barrier. In this context, genetic incompatibilities involving the duplicated F-box genes as putative candidates, and a possible strengthening step involving the

  16. Patterns of Sequence Divergence and Evolution of the S1 Orthologous Regions between Asian and African Cultivated Rice Species

    PubMed Central

    Gavory, Frédérick; Samain, Sylvie; Tohme, Joe; Ghesquière, Alain; Lorieux, Mathias

    2011-01-01

    A strong postzygotic reproductive barrier separates the recently diverged Asian and African cultivated rice species, Oryza sativa and O. glaberrima. Recently a model of genetic incompatibilities between three adjacent loci: S1A, S1 and S1B (called together the S1 regions) interacting epistatically, was postulated to cause the allelic elimination of female gametes in interspecific hybrids. Two candidate factors for the S1 locus (including a putative F-box gene) were proposed, but candidates for S1A and S1B remained undetermined. Here, to better understand the basis of the evolution of regions involved in reproductive isolation, we studied the genic and structural changes accumulated in the S1 regions between orthologous sequences. First, we established an 813 kb genomic sequence in O. glaberrima, covering completely the S1A, S1 and the majority of the S1B regions, and compared it with the orthologous regions of O. sativa. An overall strong structural conservation was observed, with the exception of three isolated regions of disturbed collinearity: (1) a local invasion of transposable elements around a putative F-box gene within S1, (2) the multiple duplication and subsequent divergence of the same F-box gene within S1A, (3) an interspecific chromosomal inversion in S1B, which restricts recombination in our O. sativa×O. glaberrima crosses. Beside these few structural variations, a uniform conservative pattern of coding sequence divergence was found all along the S1 regions. Hence, the S1 regions have undergone no drastic variation in their recent divergence and evolution between O. sativa and O. glaberrima, suggesting that a small accumulation of genic changes, following a Bateson-Dobzhansky-Muller (BDM) model, might be involved in the establishment of the sterility barrier. In this context, genetic incompatibilities involving the duplicated F-box genes as putative candidates, and a possible strengthening step involving the chromosomal inversion might participate to

  17. Regional trade and the nutrition transition: opportunities to strengthen NCD prevention policy in the Southern African Development Community

    PubMed Central

    Thow, Anne Marie; Sanders, David; Drury, Eliza; Puoane, Thandi; Chowdhury, Syeda N.; Tsolekile, Lungiswa; Negin, Joel

    2015-01-01

    Background Addressing diet-related non-communicable diseases (NCDs) will require a multisectoral policy approach that includes the food supply and trade, but implementing effective policies has proved challenging. The Southern African Development Community (SADC) has experienced significant trade and economic liberalization over the past decade; at the same time, the nutrition transition has progressed rapidly in the region. This analysis considers the relationship between regional trade liberalization and changes in the food environment associated with poor diets and NCDs, with the aim of identifying feasible and proactive policy responses to support healthy diets. Design Changes in trade and investment policy for the SADC were documented and compared with time-series graphs of import data for soft drinks and snack foods to assess changes in imports and source country in relation to trade and investment liberalization. Our analysis focuses on regional trade flows. Results Diets and the burden of disease in the SADC have changed since the 1990s in parallel with trade and investment liberalization. Imports of soft drinks increased by 76% into SADC countries between 1995 and 2010, and processed snack foods by 83%. South Africa acts as a regional trade and investment hub; it is the major source of imports and investment related to these products into other SADC countries. At the same time, imports of processed foods and soft drinks from outside the region – largely from Asia and the Middle East – are increasing at a dramatic rate with soft drink imports growing by almost 1,200% and processed snack foods by 750%. Conclusions There is significant intra-regional trade in products associated with the nutrition transition; however, growing extra-regional trade means that countries face new pressures in implementing strong policies to prevent the increasing burden of diet-related NCDs. Implementation of a regional nutrition policy framework could complement the SADC

  18. Phylogenetic analysis of the polyprotein coding region of an infectious South African bursal disease virus (IBDV) strain.

    PubMed

    Vukea, Phillia R; Willows-Munro, Sandi; Horner, Roger F; Coetzer, Theresa H T

    2014-01-01

    Infectious bursal disease virus (IBDV) causes Gumboro disease, which is highly contagious and immunosuppressive in young chickens. A virulent form of IBDV reached South Africa in 1989 and to date there has been little molecular information available for this strain. In this study, the polyprotein coding region of the South African strain SA-KZN95 was sequenced and analysed along with 52 representative sequences of other serotype I and II strains. We explored the relative impact of recombination on phylogenetic reconstruction using a multidimensional scaling approach. Phylogenetic analyses consistently placed the South African isolate within the very virulent IBDV clade. Selection analyses were also conducted to identify evolutionarily relevant amino acid residues. Previously, 19 residues in the polyprotein were shown to be potentially diagnostic for the different IBDV pathotypes. This study identified an additional two unique residues in the polyprotein which may be used as genetic signatures in future viral identifications. Better strain identification would aid in the development and application of vaccines. PMID:24291011

  19. Protocol to the African Charter on the Rights of Women: implications for access to abortion at the regional level.

    PubMed

    Ngwena, Charles G

    2010-08-01

    Article 14(2)(c) of the Protocol to the African Charter on the Rights of Women enjoins States Parties to take appropriate measures "to protect the reproductive rights of women by authorising medical abortion in cases of sexual assault, rape, incest, and where continued pregnancy endangers the mental and physical health of the mother or the life of the mother or the foetus." This paper considers the implications of Article 14 for access to safe, legal abortion. It is submitted that Article 14 has the potential to impact positively on regional abortion law, policy, and practice in 3 main areas. First, it takes forward the global consensus on combating abortion as a major public health danger. Second, it provides African countries with not just an incentive, but also an imperative for reforming abortion laws in a transparent manner. Third, if implemented in the context of a treaty that centers on the equality and non-discrimination of women, Article 14 has the potential to contribute toward transforming access to abortion from a crime and punishment model to a reproductive health model. PMID:20546748

  20. West African monsoon intraseasonal activity and its daily precipitation indices in regional climate models: diagnostics and challenges

    NASA Astrophysics Data System (ADS)

    Poan, E. D.; Gachon, P.; Dueymes, G.; Diaconescu, E.; Laprise, R.; Seidou Sanda, I.

    2016-02-01

    The West African monsoon intraseasonal variability has huge socio-economic impacts on local populations but understanding and predicting it still remains a challenge for the weather prediction and climate scientific community. This paper analyses an ensemble of simulations from six regional climate models (RCMs) taking part in the coordinated regional downscaling experiment, the ECMWF ERA-Interim reanalysis (ERAI) and three satellite-based and observationally-constrained daily precipitation datasets, to assess the performance of the RCMs with regard to the intraseasonal variability. A joint analysis of seasonal-mean precipitation and the total column water vapor (also called precipitable water—PW) suggests the existence of important links at different timescales between these two variables over the Sahel and highlights the relevance of using PW to follow the monsoon seasonal cycle. RCMs that fail to represent the seasonal-mean position and amplitude of the meridional gradient of PW show the largest discrepancies with respect to seasonal-mean observed precipitation. For both ERAI and RCMs, spectral decompositions of daily PW as well as rainfall show an overestimation of low-frequency activity (at timescales longer than 10 days) at the expense of the synoptic (timescales shorter than 10 days) activity. Consequently, the effects of the African Easterly Waves and the associated mesoscale convective systems are substantially underestimated, especially over continental regions. Finally, the study investigates the skill of the models with respect to hydro-climatic indices related to the occurrence, intensity and frequency of precipitation events at the intraseasonal scale. Although most of these indices are generally better reproduced with RCMs than reanalysis products, this study indicates that RCMs still need to be improved (especially with respect to their subgrid-scale parameterization schemes) to be able to reproduce the intraseasonal variance spectrum adequately.

  1. Urban African American Parents’ Messages about Violence: A Mixed Methods Study

    PubMed Central

    Lindstrom Johnson, Sarah; Finigan, Nadine; Bradshaw, Catherine; Haynie, Denise; Cheng, Tina L.

    2015-01-01

    Family socialization, which includes parental control and support, plays an important role in reducing the likelihood of adolescent involvement in conflict. This study examined the strategies that urban parents living in neighborhoods with high crime rates suggest to help their adolescent children avoid or deescalate conflict. Data come from 48 African American parent/adolescent dyads recruited through the youths’ middle school. Dyads responded to three video-taped scenarios depicting youth in potential conflict situations. Qualitative methods were used to identify 11 strategies parents suggested to help youth avoid or deescalate conflict. Although the majority of parents advocated for non-violent solutions, these same parents described situations in which their child may need to use violence. These findings have important implications for family-focused violence prevention programs. PMID:26726283

  2. How strong ist the impact of changing topography of the East African Rift System on regional climate?

    NASA Astrophysics Data System (ADS)

    Prömmel, Kerstin; Kaspar, Frank; Cubasch, Ulrich

    2010-05-01

    The evolution of the East African Rift System (EARS) leads to a topography change at the surface and the impact of this change on climate in this region can easily be analysed with climate models. In the present study both global and regional climate models are applied. The global climate model is the coupled atmosphere ocean general circulation model ECHO-G and the regional climate model is the non-hydrostatic CLM, which is the climate version of the numerical weather prediction model of the German Meterorological Service. At the lateral boundaries the regional model is driven by the simulations performed with the global model. Different topographical situations representing possible conditions in the past, are simulated with the global and the regional climate model. One assumption affects only the highest peaks of the EARS south of the Turkana Channel by reducing them to 1200 m. The other assumptions affect a much larger area covering the whole of Southern and Eastern Africa. Over this region topography is reduced by 25%, 50%, 75% and 95%. These different topography reductions have an impact on circulation and therefore also on moisture transport. This leads to changes in the precipitation patterns over Africa. One strong effect is the decrease in orographic precipitation windward of the mountains. Wetter conditions can be found over the east coast of Africa, where moisture is transported from the Indian Ocean farther into the continent due to the lower barrier. Both global and regional models show similar results on the continental scale, however the results of the regional model are much more detailed due to the higher horizontal resolution (50 km) compared to the global model (~350 km).

  3. Assessment of the Vulnerability of Water Resources to Seasonal Fires Across the Northern Sub-Saharan African Region

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles M.

    2010-01-01

    The northern sub-Saharan African (NSSA) region, extending from the southern fringes of the Sahara to the Equator, and stretching west to east from the Atlantic to the Indian ocean coasts, plays a prominent role in the distribution of Saharan dust and other airborne matter around the region and to other parts of the world, the genesis of global atmospheric circulation, and the birth of such major (and often catastrophic) events as hurricanes. Therefore, this NSSA region represents a critical variable in the global climate change equation. Recent satellite-based studies have revealed that the NSSA region has one of the highest biomass-burning rates per unit land area among all regions of the world. Because of the high concentration and frequency of fires in this region, with the associated abundance of heat release and gaseous and particulate smoke emissions, biomass-burning activity is believed to be a major driver of the regional carbon, energy, and water cycles. We acknowledge that the rainy season in the NSSA region is from April to September while biomass burning occurs mainly during the dry season (October to March). Nevertheless, these two phenomena are indirectly coupled to each other through a chain of complex processes and conditions, including land-cover and surface-albedo changes, the carbon cycle, evapotranspiration, drought, desertification, surface water runoff, ground water recharge, and variability in atmospheric composition, heating rates, and circulation. In this presentation, we will examine the theoretical linkages between these processes, discuss the preliminary results based on satellite data analysis, and provide an overview of plans for more integrated research to be conducted over the next few years.

  4. A test of the Lamendin method of age estimation in South African canines.

    PubMed

    Ackermann, Anja; Steyn, Maryna

    2014-03-01

    Age estimation in unknown adult skeletons remains a considerable problem in forensic anthropology. In 1992, Lamendin et al. published a non-destructive method of age estimation on single rooted teeth. With this method, periodontosis and root transparency are judged against root height, and these are then used in regression formulae to estimate age. The aim of this study was to test the accuracy of the Lamendin method on a large sample of canines of South Africans, and if necessary to adapt the formulae for this population. A sample of known sex, age and population group was used. This included 537 upper and lower canines from 498 skulls, and included black males, black females, white males and white females. The age of the individuals ranged from 20 to 90 years. The original formulae gave relatively poor results, and in an attempt to obtain better accuracy the formulae were adapted with the current data. Even after adaptation of the formulae, the highest correlation between estimated age and actual age remained low (R(2)=0.41), with mean errors ranging between 12 and 15 years. Periodontosis was better correlated with age than root transparency. The accuracy of the method was found to be much lower than what was originally published, but probably reflects biological reality and is on a par with other methods of adult age estimation. PMID:24445081

  5. Managed European-Derived Honey Bee, Apis mellifera sspp, Colonies Reduce African-Matriline Honey Bee, A. m. scutellata, Drones at Regional Mating Congregations

    PubMed Central

    Mortensen, Ashley N.; Ellis, James D.

    2016-01-01

    African honey bees (Apis mellifera scutellata) dramatically changed the South American beekeeping industry as they rapidly spread through the Americas following their introduction into Brazil. In the present study, we aimed to determine if the management of European-derived honey bees (A. mellifera sspp.) could reduce the relative abundance of African-matriline drones at regional mating sites known as drone congregation areas (DCAs). We collected 2,400 drones at six DCAs either 0.25 km or >2.8 km from managed European-derived honey bee apiaries. The maternal ancestry of each drone was determined by Bgl II enzyme digestion of an amplified portion of the mitochondrial Cytochrome b gene. Furthermore, sibship reconstruction via nuclear microsatellites was conducted for a subset of 1,200 drones to estimate the number of colonies contributing drones to each DCA. Results indicate that DCAs distant to managed European apiaries (>2.8 km) had significantly more African−matriline drones (34.33% of the collected drones had African mitochondrial DNA) than did DCAs close (0.25 km) to managed European apiaries (1.83% of the collected drones had African mitochondrial DNA). Furthermore, nuclear sibship reconstruction demonstrated that the reduction in the proportion of African matriline drones at DCAs near apiaries was not simply an increase in the number of European matriline drones at the DCAs but also the result of fewer African matriline colonies contributing drones to the DCAs. Our data demonstrate that the management of European honey bee colonies can dramatically influence the proportion of drones with African matrilines at nearby drone congregation areas, and would likely decreasing the probability that virgin European queens will mate with African drones at those drone congregation areas. PMID:27518068

  6. Assessing the performance of methods to detect and quantify African dust in airborne particulates.

    PubMed

    Viana, Mar; Salvador, Pedro; Artíñano, Begoña; Querol, Xavier; Alastuey, Andrés; Pey, Jorge; Latz, Achim J; Cabañas, Mercè; Moreno, Teresa; García dos Santos, Saúl; Herce, María Dolores; Diez Hernández, Pablo; Romero García, Dolores; Fernández-Patier, Rosalía

    2010-12-01

    African dust (AD) contributions to particulate matter (PM) levels may be reported by Member States to the European Commission during justification of exceedances of the daily limit value (DLV). However, the detection and subsequent quantification of the AD contribution to PM levels is complex, and only two measurement-based methods are available in the literature: the Spanish-Portuguese reference method (SPR), and the Tel Aviv University method (TAU). In the present study, both methods were assessed. The SPR method was more conservative in the detection of episodes (71 days identified as AD by SPR, vs 81 by TAU), as it is less affected by interferences with local dust sources. The mean annual contribution of AD was lower with the TAU method than with SPR (2.7 vs 3.5 ± 1.5 μg/m(3)). The SPR and TAU AD time series were correlated with daily aluminum levels (a known tracer of AD), as well as with an AD source identified by the Positive Matrix Factorization (PMF) receptor model. Higher r(2) values were obtained with the SPR method than with TAU in both cases (r(2) = 0.72 vs 0.56, y = 0.05x vs y = 0.06x with aluminum levels; r(2)=0.79 vs 0.43, y = 0.8x vs y = 0.4x with the PMF source). We conclude that the SPR method is more adequate from an EU policy perspective (justification of DLV exceedances) due to the fact that it is more conservative than the TAU method. Based on our results, the TAU method requires adaptation of the thresholds in the algorithm to refine detection of low-impact episodes and avoid misclassification of local events as AD. PMID:21049991

  7. Five linkage regions each harbor multiple type 2 diabetes genes in the African American subset of the GENNID Study.

    PubMed

    Hasstedt, Sandra J; Highland, Heather M; Elbein, Steven C; Hanis, Craig L; Das, Swapan K

    2013-06-01

    We previously localized type 2 diabetes (T2D)-susceptibility genes to five chromosomal regions through a genome-wide linkage scan of T2D and age of diagnosis (AOD) in the African American subset of the GENNID sample. To follow up these findings, we repeated the linkage and association analysis using genotypes on an additional 9203 fine-mapping single nucleotide polymorphisms (SNPs) selected to tag genes under the linkage peaks. In each of the five regions, we confirmed linkage and inferred the presence of ≥2 susceptibility genes. The evidence of multiple susceptibility genes consisted of: (1) multiple linkage peaks in four of the five regions; and (2) association of T2D and AOD with SNPs within ≥2 genes in every region. The associated genes included 3 previously reported to associate with T2D or related traits (GRB10, NEDD4L, LIPG) and 24 novel candidate genes, including genes in lipid metabolism (ACOXL) and cell-cell and cell-matrix adhesion (MAGI2, CLDN4, CTNNA2). PMID:23552671

  8. Assessment of uncertainties in the response of the African monsoon precipitation to land use change simulated by a regional model

    DOE PAGESBeta

    Hagos, Samson M.; Leung, Lai-Yung Ruby; Xue, Yongkang; Boone, Aaron; de Sales, Fernando; Neupane, Naresh; Huang, Maoyi; Yoon, Jin -Ho

    2014-02-22

    Land use and land cover over Africa have changed substantially over the last sixty years and this change has been proposed to affect monsoon circulation and precipitation. This study examines the uncertainties on the effect of these changes on the African Monsoon system and Sahel precipitation using an ensemble of regional model simulations with different combinations of land surface and cumulus parameterization schemes. Furthermore, the magnitude of the response covers a broad range of values, most of the simulations show a decline in Sahel precipitation due to the expansion of pasture and croplands at the expense of trees and shrubsmore » and an increase in surface air temperature.« less

  9. A Mixed Methods Study: African American Students' Performance Trends and Perceptions Towards Advanced Placement Literature Courses and Examinations

    ERIC Educational Resources Information Center

    Buford, Brandie J.

    2012-01-01

    The purpose of this mixed methods study was to describe the perceptions of African American students pertaining to their engagement in Advanced Placement English Literature and Composition course and Advanced Placement English Literature and Composition examination. A purposive sampling design was employed to select 12 participants from one urban…

  10. Sex-Role Egalitarian Attitudes and Gender Role Socialization Experiences of African American Men and Women: A Mixed Methods Paradigm

    ERIC Educational Resources Information Center

    Heard, Courtney Christian Charisse

    2013-01-01

    The purpose of this study was to assess the sex-role egalitarian attitudes and gender role socialization experiences of African American men and women. A sequential mixed-methods design was employed to research this phenomenon. The Sex-Role Egalitarianism Scale-Short Form BB (SRES-BB) was utilized to assess sex-role egalitarian attitudes (King…

  11. Childhood obesity perceptions among African American caregivers in a rural Georgia community: a mixed methods approach.

    PubMed

    Alexander, Dayna S; Alfonso, Moya L; Hansen, Andrew R

    2015-04-01

    Given the pivotal role of African American caregiver's perceptions of childhood obesity in rural areas, the inclusion of caregiver's perceptions could potentially reduce childhood obesity rates. The objective of the current study was to explore childhood obesity perceptions among African Americans in a rural Georgia community. This concurrent mixed methods study utilized two theoretical frameworks: Social Cognitive Theory and Social Ecological Model. Using a convenience sample, caregivers ages 22-65 years completed a paper-based survey (n = 135) and a face-to-face interview (n = 12) to explore perceptions of obesity risk factors, health complications, weight status, built environment features, and obesity prevention approaches. Descriptive statistics were generated and a six-step process was used for qualitative analysis. Participants commonly cited behavioral risk factors; yet, social aspects and appearance of the community were not considered contributing factors. Chronic diseases were reported as obesity health complications. Caregivers had a distorted view of their child's weight status. In addition, analysis revealed that caregivers assessed child's weight and height measurements by the child's appearance or a recent doctor visit. Environmental barriers reported by caregivers included safety concerns and insufficient physical activity venues and programs. Also, caregivers conveyed parents are an imperative component of preventing obesity. Although this study found caregivers were aware of obesity risk factors, health complications, built environment features, and prevention approaches their obesity perceptions were not incorporated into school or community prevention efforts. Findings suggest that children residing in rural areas are in need of tailored efforts that address caregiver perceptions of obesity. PMID:25218019

  12. Thriving, Managing, and Struggling: A Mixed Methods Study of Adolescent African Refugees’ Psychosocial Adjustment

    PubMed Central

    Weine, Stevan Merrill; Ware, Norma; Tugenberg, Toni; Hakizimana, Leonce; Dahnweih, Gonwo; Currie, Madeleine; Wagner, Maureen; Levin, Elise

    2013-01-01

    Objectives The purpose of this mixed method study was to characterize the patterns of psychosocial adjustment among adolescent African refugees in U.S. resettlement. Methods A purposive sample of 73 recently resettled refugee adolescents from Burundi and Liberia were followed for two years and qualitative and quantitative data was analyzed using a mixed methods exploratory design. Results Protective resources identified were the family and community capacities that can promote youth psychosocial adjustment through: 1) Finances for necessities; 2) English proficiency; 3) Social support networks; 4) Engaged parenting; 5) Family cohesion; 6) Cultural adherence and guidance; 7) Educational support; and, 8) Faith and religious involvement. The researchers first inductively identified 19 thriving, 29 managing, and 25 struggling youths based on review of cases. Univariate analyses then indicated significant associations with country of origin, parental education, and parental employment. Multiple regressions indicated that better psychosocial adjustment was associated with Liberians and living with both parents. Logistic regressions showed that thriving was associated with Liberians and higher parental education, managing with more parental education, and struggling with Burundians and living parents. Qualitative analysis identified how these factors were proxy indicators for protective resources in families and communities. Conclusion These three trajectories of psychosocial adjustment and six domains of protective resources could assist in developing targeted prevention programs and policies for refugee youth. Further rigorous longitudinal mixed-methods study of adolescent refugees in U.S. resettlement are needed. PMID:24205467

  13. Smoking Cessation Intervention Preferences Among Urban African Americans: A Mixed Methods Approach.

    PubMed

    Baker, Cathy J; Palmer, Sheena D; Lee, Chia-Wen Vianne

    2016-06-01

    African Americans suffer disproportionately from smoking-related morbidity and mortality and make more quit attempts but report less success in quitting. Smokers tend to identify more strongly with African American culture. Qualitative interviews were conducted to elicit perceptions toward smoking and intervention content. Seventy-one African American smokers recruited from community locations participated. The majority stated they would not use any cessation aids if trying to quit smoking, despite the availability of free nicotine replacement. Acculturative stress scores were significantly higher in younger participants and those with higher income. Higher African American acculturation did not predict smoking cessation intervention preference. Family and social relationships were cited as both reasons for wanting to quit and reasons for continuing to smoke. Based on these findings, interventions for urban African Americans should address household members continuing to smoke, social/family connections, stress management, and cultural identification in urban areas. PMID:26809884

  14. Methods for Comparing Nutrients in Beebread Made by Africanized and European Honey Bees and the Effects on Hemolymph Protein Titers

    PubMed Central

    Degrandi-Hoffman, Gloria; Eckholm, Bruce; Huang, Ming

    2015-01-01

    Honey bees obtain nutrients from pollen they collect and store in the hive as beebread. We developed methods to control the pollen source that bees collect and convert to beebread by placing colonies in a specially constructed enclosed flight area. Methods were developed to analyze the protein and amino acid composition of the pollen and beebread. We also describe how consumption of the beebread was measured and methods used to determine adult worker bee hemolymph protein titers after feeding on beebread for 4, 7 and 11 days after emergence. Methods were applied to determine if genotype affects the conversion of pollen to beebread and the rate that bees consume and acquire protein from it. Two subspecies (European and Africanized honey bees; EHB and AHB respectively) were provided with the same pollen source. Based on the developed methods, beebread made by both subspecies had lower protein concentrations and pH values than the pollen. In general, amino acid concentrations in beebread made by either EHB or AHB were similar and occurred at higher levels in beebread than in pollen. Both AHB and EHB consumed significantly more of the beebread made by AHB than by EHB. Though EHB and AHB consumed similar amounts of each type of beebread, hemolymph protein concentrations in AHB were higher than in EHB. Differences in protein acquisition between AHB and EHB might reflect environmental adaptations related to the geographic region where each subspecies evolved. These differences could contribute to the successful establishment of AHB populations in the New World because of the effects on brood rearing and colony growth. PMID:25867246

  15. The family planning movement within the African Region of the International Planned Parenthood Federation. Le mouvement pour la planification familiale dans la Region Afrique de la Federation Internationale pour la Planification Familiale.

    PubMed

    Sozi, M K

    1984-09-01

    The African Region of International Planned Parenthood Federation (IPPF) was established in 1971 to: encourage and sustain voluntary groups, provide information about family planning as a basic right, provide limited family planning services where acceptable and needed, and eventually influence change in public opinion so that governments could accept some responsibility for family planning programs. Today almost all of Anglophone Africa is covered by IPPF-funded activities, progress is being made in Francophone Africa, and Lusophone Africa is a target for the 1980s. National family planning associations and the IPPF have laid a firm foundation for family planning and raised its credibility to acceptable levels. However, both inadequate logistic infrastructures for the smooth flow of services and overcaution in adopting innovative methods such as community-based delivery systems to those not easily reached by coventional delivery systems have led service to lag behind demand. Leaders at all levels must join efforts to solve this dilemma. Family planning associations are the best suited channels for family planning work in the African Region, but they lack the capacity to cover all needs. As a result, these associations are shiftingg their efforts toward supplementing government work in this area. Although the government response has been far from uniform, governments have shown an ability to accommodate the operations of family planning organizations and have integrated family planning into national health services. Although 19 governments in the Region consider the fertility levels in their countries to be satisfactory and a few consider fertility too low, family planning is accepted as an instrument for the promotion of family welfare. The importance of national leadership in promoting and implementing family planning programs is increasingly recognized. Parliamentarians can formulate national policies favorable to family planning, promote awareness among their

  16. Differential magnetometer method applied to measurement of geomagnetically induced currents in Southern African power networks

    NASA Astrophysics Data System (ADS)

    Matandirotya, Electdom; Cilliers, Pierre. J.; Van Zyl, Robert R.; Oyedokun, David T.; Villiers, Jean

    2016-03-01

    Geomagnetically induced currents (GICs) in conductors connected to the Earth are driven by an electric field produced by a time-varying magnetic field linked to magnetospheric-ionospheric current perturbations during geomagnetic storms. The GIC measurements are traditionally done on the neutral-to-ground connections of power transformers. A method of inferring the characteristics of GIC in power lines using differential magnetic field measurements is presented. Measurements of the GIC in the power lines connected to a particular power transformer are valuable in the verification of the modeling of GIC in the power transmission network. The differential magnetometer method (DMM) is an indirect method used to estimate the GIC in a power line. With the DMM, low-frequency GIC in the power line is estimated from the difference between magnetic field recordings made directly underneath the power line and at some distance away, where the magnetic field of the GIC in the transmission line has negligible effect. Results of the first application of the DMM to two selected sites of the Southern African power transmission network are presented. The results show that good quality GIC measurements are achieved through the DMM using Commercially-Off-The-Shelf magnetometers.

  17. REGIONAL METHODS INITIATIVE RESEARCH PROJECTS AT HEASD

    EPA Science Inventory

    EPA Regional Laboratories are currently using high volume samplers with a combination of filter and sorbent vapor trap to collect large volume samples (250 liter/min for 24 hours) of semi-volatile organic compounds (SVOCs) and non-volatile organic compounds (NVOCs). These are su...

  18. REGIONAL METHODS INITIATIVE FOR ALKYLPHENOL ENDOCRINE DISRUPTERS

    EPA Science Inventory

    Nonylphenol and the ethoxylates are amenable to GC/MS analysis but the carboxylates are better analyzed using LC/MS. The Central Regional Laboratory (CRL) intends to do this with standards of known purity using a triple quadruple instrument. The purified standards will be used to...

  19. Addressing the Issue of Gender Equity in the Presidency of the University System in the Southern African Development Community (SADC) Region

    ERIC Educational Resources Information Center

    Guramatunhu-Mudiwa, Precious

    2010-01-01

    The Southern African Development Community (SADC) is a regional economic grouping of 15 countries whose common vision is to promote economic, social and political development and growth. Arguably, sustainable growth can be realized if there is equal access to all positions of power and influence in the area, but an investigation of 117…

  20. African horse sickness: The potential for an outbreak in disease-free regions and current disease control and elimination techniques.

    PubMed

    Robin, M; Page, P; Archer, D; Baylis, M

    2016-09-01

    African horse sickness (AHS) is an arboviral disease of equids transmitted by Culicoides biting midges. The virus is endemic in parts of sub-Saharan Africa and official AHS disease-free status can be obtained from the World Organization for Animal Health on fulfilment of a number of criteria. AHS is associated with case fatality rates of up to 95%, making an outbreak among naïve horses both a welfare and economic disaster. The worldwide distributions of similar vector-borne diseases (particularly bluetongue disease of ruminants) are changing rapidly, probably due to a combination of globalisation and climate change. There is extensive evidence that the requisite conditions for an AHS epizootic currently exist in disease-free countries. In particular, although the stringent regulations enforced upon competition horses make them extremely unlikely to redistribute the virus, there are great concerns over the effects of illegal equid movement. An outbreak of AHS in a disease free region would have catastrophic effects on equine welfare and industry, particularly for international events such as the Olympic Games. While many regions have contingency plans in place to manage an outbreak of AHS, further research is urgently required if the equine industry is to avoid or effectively contain an AHS epizootic in disease-free regions. This review describes the key aspects of AHS as a global issue and discusses the evidence supporting concerns that an epizootic may occur in AHS free countries, the planned government responses, and the roles and responsibilities of equine veterinarians. PMID:27292229

  1. QTL Mapping in Three Rice Populations Uncovers Major Genomic Regions Associated with African Rice Gall Midge Resistance

    PubMed Central

    Semagn, Kassa; Sow, Mounirou; Nwilene, Francis; Kolade, Olufisayo; Bocco, Roland; Oyetunji, Olumoye; Mitchell-Olds, Thomas; Ndjiondjop, Marie-Noëlle

    2016-01-01

    African rice gall midge (AfRGM) is one of the most destructive pests of irrigated and lowland African ecologies. This study aimed to identify the quantitative trait loci (QTL) associated with AfRGM pest incidence and resistance in three independent bi-parental rice populations (ITA306xBW348-1, ITA306xTOG7106 and ITA306xTOS14519), and to conduct meta QTL (mQTL) analysis to explore whether any genomic regions are conserved across different genetic backgrounds. Composite interval mapping (CIM) conducted on the three populations independently uncovered a total of 28 QTLs associated with pest incidence (12) and pest severity (16). The number of QTLs per population associated with AfRGM resistance varied from three in the ITA306xBW348-1 population to eight in the ITA306xTOG7106 population. Each QTL individually explained 1.3 to 34.1% of the phenotypic variance. The major genomic region for AfRGM resistance had a LOD score and R2 of 60.0 and 34.1% respectively, and mapped at 111 cM on chromosome 4 (qAfrGM4) in the ITA306xTOS14519 population. The meta-analysis reduced the number of QTLs from 28 to 17 mQTLs, each explaining 1.3 to 24.5% of phenotypic variance, and narrowed the confidence intervals by 2.2 cM. There was only one minor effect mQTL on chromosome 1 that was common in the TOS14519 and TOG7106 genetic backgrounds; all other mQTLs were background specific. We are currently fine-mapping and validating the major effect genomic region on chromosome 4 (qAfRGM4). This is the first report in mapping the genomic regions associated with the AfRGM resistance, and will be highly useful for rice breeders. PMID:27508500

  2. QTL Mapping in Three Rice Populations Uncovers Major Genomic Regions Associated with African Rice Gall Midge Resistance.

    PubMed

    Yao, Nasser; Lee, Cheng-Ruei; Semagn, Kassa; Sow, Mounirou; Nwilene, Francis; Kolade, Olufisayo; Bocco, Roland; Oyetunji, Olumoye; Mitchell-Olds, Thomas; Ndjiondjop, Marie-Noëlle

    2016-01-01

    African rice gall midge (AfRGM) is one of the most destructive pests of irrigated and lowland African ecologies. This study aimed to identify the quantitative trait loci (QTL) associated with AfRGM pest incidence and resistance in three independent bi-parental rice populations (ITA306xBW348-1, ITA306xTOG7106 and ITA306xTOS14519), and to conduct meta QTL (mQTL) analysis to explore whether any genomic regions are conserved across different genetic backgrounds. Composite interval mapping (CIM) conducted on the three populations independently uncovered a total of 28 QTLs associated with pest incidence (12) and pest severity (16). The number of QTLs per population associated with AfRGM resistance varied from three in the ITA306xBW348-1 population to eight in the ITA306xTOG7106 population. Each QTL individually explained 1.3 to 34.1% of the phenotypic variance. The major genomic region for AfRGM resistance had a LOD score and R2 of 60.0 and 34.1% respectively, and mapped at 111 cM on chromosome 4 (qAfrGM4) in the ITA306xTOS14519 population. The meta-analysis reduced the number of QTLs from 28 to 17 mQTLs, each explaining 1.3 to 24.5% of phenotypic variance, and narrowed the confidence intervals by 2.2 cM. There was only one minor effect mQTL on chromosome 1 that was common in the TOS14519 and TOG7106 genetic backgrounds; all other mQTLs were background specific. We are currently fine-mapping and validating the major effect genomic region on chromosome 4 (qAfRGM4). This is the first report in mapping the genomic regions associated with the AfRGM resistance, and will be highly useful for rice breeders. PMID:27508500

  3. University as Regional Development Agent: A Counterfactual Analysis of an African University

    ERIC Educational Resources Information Center

    Fongwa, Samuel N.; Wangenge-Ouma, Gerald

    2015-01-01

    The contribution of universities to regional development has in the last few decades gained significant currency. Inter alia, this contribution has been through steered national, regional, and institutional policies aimed at enhancing national development, good governance, human capital creation and innovation in an increasing knowledge-dependent…

  4. Factors Associated with African-American Freshmen and Non-African-American Freshmen Retention and Graduation at a Predominantly White, Regional University

    ERIC Educational Resources Information Center

    Owens, Robert L., II

    2009-01-01

    The purpose of this study was to examine further, the factors at a Predominantly White College or University (PWCU) that may affect the first-year retention and six-year graduation of African-American (AA) and non-AA students. Biographical and descriptive data was obtained for each student entering Tennessee Technological University (TTU) from the…

  5. Plate Kinematic model of the NW Indian Ocean and derived regional stress history of the East African Margin

    NASA Astrophysics Data System (ADS)

    Tuck-Martin, Amy; Adam, Jürgen; Eagles, Graeme

    2015-04-01

    Starting with the break up of Gondwana, the northwest Indian Ocean and its continental margins in Madagascar, East Africa and western India formed by divergence of the African and Indian plates and were shaped by a complicated sequence of plate boundary relocations, ridge propagation events, and the independent movement of the Seychelles microplate. As a result, attempts to reconcile the different plate-tectonic components and processes into a coherent kinematic model have so far been unsatisfactory. A new high-resolution plate kinematic model has been produced in an attempt to solve these problems, using seafloor spreading data and rotation parameters generated by a mixture of visual fitting of magnetic isochron data and iterative joint inversion of magnetic isochron and fracture zone data. Using plate motion vectors and plate boundary geometries derived from this model, the first-order regional stress pattern was modelled for distinct phases of margin formation. The stress pattern is correlated with the tectono-stratigraphic history of related sedimentary basins. The plate kinematic model identifies three phases of spreading, from the Jurassic to the Paleogene, which resulted in the formation of three main oceanic basins. Prior to these phases, intracontinental 'Karoo' rifting episodes in the late Carboniferous to late Triassic had failed to break up Gondwana, but initiated the formation of sedimentary basins along the East African and West Madagascan margins. At the start of the first phase of spreading (183 to 133 Ma) predominantly NW - SE extension caused continental rifting that separated Madagascar/India/Antarctica from Africa. Maximum horizontal stresses trended perpendicular to the local plate-kinematic vector, and parallel to the rift axes. During and after continental break-up and subsequent spreading, the regional stress regime changed drastically. The extensional stress regime became restricted to the active spreading ridges that in turn adopted trends

  6. Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra

    PubMed Central

    Dalton, Brian E.; Lu, Jessica; Leips, Jeff; Cronin, Thomas W.; Carleton, Karen L.

    2015-01-01

    Critical behaviors such as predation and mate choice often depend on vision. Visual systems are sensitive to the spectrum of light in their environment, which can vary extensively both within and among habitats. Evolutionary changes in spectral sensitivity contribute to divergence and speciation. Spectral sensitivity of the retina is primarily determined by visual pigments, which are opsin proteins bound to a chromophore. We recently discovered that photoreceptors in different regions of the retina, which view objects against distinct environmental backgrounds, coexpress different pairs of opsins in an African cichlid fish, Metriaclima zebra. This coexpression tunes the sensitivity of the retinal regions to the corresponding backgrounds and may aid detection of dark objects, such as predators. Although intraretinal regionalization of spectral sensitivity in many animals correlates with their light environments, it is unknown whether variation in the light environment induces developmentally plastic alterations of intraretinal sensitivity regions. Here, we demonstrate with fluorescent in situ hybridization and qPCR that the spectrum and angle of environmental light both influence the development of spectral sensitivity regions by altering the distribution and level of opsins across the retina. Normally M. zebra coexpresses LWS opsin with RH2Aα opsin in double cones of the ventral but not the dorsal retina. However, when illuminated from below throughout development, adult M. zebra coexpressed LWS and RH2Aα in double cones both dorsally and ventrally. Thus, environmental background spectra alter the spectral sensitivity pattern that develops across the retina, potentially influencing behaviors and related evolutionary processes such as courtship and speciation. PMID:26175094

  7. Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra.

    PubMed

    Dalton, Brian E; Lu, Jessica; Leips, Jeff; Cronin, Thomas W; Carleton, Karen L

    2015-08-01

    Critical behaviours such as predation and mate choice often depend on vision. Visual systems are sensitive to the spectrum of light in their environment, which can vary extensively both within and among habitats. Evolutionary changes in spectral sensitivity contribute to divergence and speciation. Spectral sensitivity of the retina is primarily determined by visual pigments, which are opsin proteins bound to a chromophore. We recently discovered that photoreceptors in different regions of the retina, which view objects against distinct environmental backgrounds, coexpress different pairs of opsins in an African cichlid fish, Metriaclima zebra. This coexpression tunes the sensitivity of the retinal regions to the corresponding backgrounds and may aid in detection of dark objects, such as predators. Although intraretinal regionalization of spectral sensitivity in many animals correlates with their light environments, it is unknown whether variation in the light environment induces developmentally plastic alterations of intraretinal sensitivity regions. Here, we demonstrate with fluorescent in situ hybridization and qPCR that the spectrum and angle of environmental light both influence the development of spectral sensitivity regions by altering the distribution and level of opsins across the retina. Normally, M. zebra coexpresses LWS opsin with RH2Aα opsin in double cones of the ventral but not the dorsal retina. However, when illuminated from below throughout development, adult M. zebra coexpressed LWS and RH2Aα in double cones both dorsally and ventrally. Thus, environmental background spectra alter the spectral sensitivity pattern that develops across the retina, potentially influencing behaviours and related evolutionary processes such as courtship and speciation. PMID:26175094

  8. Assessment of the petroleum, coal, and geothermal resources of the economic community of West African states (ECOWAS) region

    SciTech Connect

    Mattick, R.E.

    1982-01-01

    Approximately 85 percent of the land area of the ECOWAS (Economic Community of West African States) region is covered by basement rocks (igneous and highly metamorphosed rocks) or relatively thin layers of Paleozoic, Upper Precambrian, and Continental Intercalaire sedimentary rocks. These areas have little or no petroleum potential. The ECOWAS region can be divided into 13 sedimentary basins on the basis of analysis of the geologic framework of Africa. These 13 basins can be further grouped into 8 categories on the basis of similarities in stratigraphy, geologic history, and probable hydrocarbon potential. The author has attempted to summarize the petroleum potential within the geologic framework of the region. The coal discoveries can be summarized as follows: the Carboniferous section in the Niger Basin; the Paleocene-Maestrichtian, Maestrichtian, and Eocene sections in the Niger Delta and Benin; the Maestrichtian section in the Senegal Basin; and the Pleistocene section in Sierra Leone. The only proved commercial deposits are the Paleocene-Maestrichtian and Maestrichtian subbituminous coal beds of the Niger Delta. Some of the lignite deposits of the Niger Delta and Senegal Basin, however, may be exploitable in the future. Published literature contains limited data on heat-flow values in the ECOWAS region. It is inferred, however, from the few values available and the regional geology that the development of geothermal resources, in general, would be uneconomical. Exceptions may include a geopressured zone in the Niger Delta and areas of recent tectonic activity in the Benue Trough and Cameroon. Development of the latter areas under present economic conditions is not feasible.

  9. The impact of the African Great Lakes on the regional climate in a dynamically downscaled CORDEX simulation (COSMO-CLM)

    NASA Astrophysics Data System (ADS)

    Thiery, W.; Panitz, H.; van Lipzig, N.

    2013-12-01

    Owing to the strong contrast in albedo, roughness and heat capacity between land and water, lakes significantly influence the exchange of moisture, heat and momentum between the surface and the boundary layer. To investigate this two-way interaction, a correct representation of lakes within regional climate models is essential. To this end, the one-dimensional lake parameterisation scheme FLake was recently coupled to the regional climate model COSMO-CLM (CCLM). One region where lakes constitute a key component of the climate system is the African Great Lakes region. In this study, the CCLM CORDEX-Africa evaluation simulation is dynamically downscaled from 0.44° (50 km) to 0.0625° (7 km) over East-Africa. The performance of two lake modules within CCLM are compared for the period 1999-2008: the default FLake scheme and the alternative Community Land Model. Model results are evaluated in a three-step procedure. First, the atmospheric state variables near-surface temperature, precipitation, surface energy fluxes, fractional cloud cover and column precipitable water are evaluated using in-situ based and satellite-derived products. Second, a comprehensive set of in-situ water temperature profile observations serves to evaluate the temporal evolution of water temperatures at three sites: Lake Kivu (Ishungu), Lake Tanganyika's northern basin (Kigoma) and southern basin (Mpulungu). Finally, spatial variability of surface temperatures in Lake Kivu and Lake Tanganyika are evaluated on the basis of satellite-derived lake surface temperatures. Subsequently, the preferred model configuration is used to quantify and understand effects by lakes reported for other regions in the world, such as a dampened diurnal temperature range, enhanced evaporation, modified surface layer stability, increased downwind precipitation, stronger winds, and the formation of local circulation patterns. This is achieved through comparison to a model integration excluding lake effects.

  10. Assessment of Uncertainties in the Response of the African Monsoon Precipitation to Land Use Change in Regional Model Simulations

    NASA Astrophysics Data System (ADS)

    Hagos, S. M.; Leung, L.; Xue, Y.; Boone, A. A.; Huang, M.; Yoon, J.

    2013-12-01

    Land use and land cover over Africa have changed substantially over the last sixty years and this change has been proposed to affect monsoon circulation and precipitation. This study examines the uncertainties on the effect of these changes on the African Monsoon system and Sahel precipitation using an ensemble of regional model simulations with different combinations of land surface and cumulus parameterization schemes. Although the magnitude of the response covers a broad range of values, most of the simulations show a decline in Sahel precipitation due to the expansion of pasture and croplands at the expense of trees and shrubs and an increase in surface air temperature. The relationship between the model responses to land use change and the climatologies of the control simulations is also examined. Simulations that are climatologically too dry or too wet compared to observations and reanalyses have weak response to land use change because they are in moisture or energy limited regimes respectively. The ones that lie in between and therefore land-atmosphere interactions play a more significant role have stronger response to the land use and land cover changes. Much of the change in precipitation is related to changes in circulation, particularly to the response of the intensity and latitudinal position of the African Easterly Jet, which varies with the changes in meridional surface temperature gradients. The study highlights the need for measurements of the surface fluxes across the meridional cross-section of the Sahel to evaluate models and thereby allowing human impacts such as land use change on the monsoon to be projected more realistically.

  11. Assessment of uncertainties in the response of the African monsoon precipitation to land use change simulated by a regional model

    NASA Astrophysics Data System (ADS)

    Hagos, Samson; Leung, L. Ruby; Xue, Yongkang; Boone, Aaron; de Sales, Fernando; Neupane, Naresh; Huang, Maoyi; Yoon, Jin-Ho

    2014-11-01

    Land use and land cover (LULC) over Africa have changed substantially over the last 60 years and this change has been proposed to affect monsoon circulation and precipitation. This study examines the uncertainties of model simulated response in the African monsoon system and Sahel precipitation due to LULC change using a set of regional model simulations with different combinations of land surface and cumulus parameterization schemes. Although the magnitude of the response covers a broad range of values, most of the simulations show a decline in Sahel precipitation due to the expansion of pasture and croplands at the expense of trees and shrubs and an increase in surface air temperature. The relationship between the model responses to LULC change and the climatologists of the control simulations is also examined. Simulations that are climatologically too dry or too wet compared to observations and reanalyses have weak response to land use change because they are in moisture or energy limited regimes respectively. The ones that lie in between have stronger response to the LULC changes, showing a more significant role in land-atmosphere interactions. Much of the change in precipitation is related to changes in circulation, particularly to the response of the intensity and latitudinal position of the African Easterly Jet, which varies with the changes in meridional surface temperature gradients. The study highlights the need for measurements of the surface fluxes across the meridional cross-section of the Sahel to evaluate models and thereby allowing human impacts such as land use change on the monsoon to be projected more realistically.

  12. Comparison of methods to estimate physical activity and energy expenditure in African American children.

    PubMed

    Ramírez-Marrero, F A; Smith, B A; Sherman, W M; Kirby, T E

    2005-06-01

    Low levels of physical activity and high levels of obesity among children in the US is a public health concern. Accurate methods to estimate physical activity are needed to determine the efficacy of intervention programs and to explore relationships between daily physical activity and health status in children. The purpose of this study was to compare the simultaneous use of the Tritrac-R3D accelerometer (Tritrac), Yamax SW-200 Digiwalker step-counter (Digiwalker) and the Self Administered Physical Activity Checklist (SAPAC) to assess physical activity (PA) and energy expenditure (EE) in African-American children aged 7 to 10 years, using the doubly-labeled water (DLW) as the criterion method. Physical activity and energy expenditure were measured over seven consecutive days under free-living conditions. Resting metabolic rate and peak VO(2) were measured before the experimental period. There was no difference in physical activity energy expenditure (PAEE) measured by Tritrac or DLW (p > 0.05). Tritrac activity counts were highly correlated with DLW-PAEE (r = 0.81). High correlations between Digiwalker and DLW were observed when body weight was considered. A low correlation (r = 0.49) was observed between the physical activity energy expenditure by SAPAC and DLW. In conclusion, with some limitations the Tritrac and Digiwalker can provide useful and accurate information about PA and EE in 7- to 10-year-old children. PMID:15895319

  13. Mapping the African thunderstorm center in absolute units using Schumann resonance spectral decomposition method

    NASA Astrophysics Data System (ADS)

    Dyrda, Michal; Kulak, Andrzej; Mlynarczyk, Janusz

    2015-04-01

    Monitoring of the global lightning activity provides a very useful tool to study the global warming phenomenon and the other longer-scale climate changes induced by humans. The lightning activity is measured using various observational methods form space (optical satellite observations) as well as from the ground mostly by VLF /LF lightning detection networks, i.e. World Wide Lightning Location Network (WWLLN) or lightning detection network (LINET) in Europe. However, the global lightning activity measurements are possible only in the ELF range. Here we examine the African thunderstorm activity center, which is the most violent and active one. In a spherical damped resonator, such as the Earth-ionosphere cavity, the electromagnetic field is described by the solution of an inhomogeneous wave equation. For such equation the general solution can be expressed by the superposition of the solutions of the homogeneous equation, describing the resonance field, and the component, which is quite strong close to the source and weakens with source-observer separation. Thus, the superposition of the standing wave field with the field of traveling waves, which supply the energy from the lighting discharges to the global resonator, is a main reason for an asymmetric shape of the observational Schumann resonance (SR) power spectra, which highly deviate from the Lorentz curves. It is possible to separate this component from the signal using the spectrum decomposition method proposed by Kułak et al. [2006]. In our approach, we apply the inverse problem solution for determining the distance of the dominant lightning source. The distances to the thunderstorm centers are calculated using the analytical models for the electromagnetic waves propagation in the Earth-ionosphere cavity. Such forms of analytic solutions of the resonant field in the spherical cavity is the zonal harmonic series representation, described by Mushtak and Williams [2002] and we calculated the sets of such curves

  14. Comparative phylogeography of African rain forest trees: A review of genetic signatures of vegetation history in the Guineo-Congolian region

    NASA Astrophysics Data System (ADS)

    Hardy, Olivier J.; Born, Céline; Budde, Katarina; Daïnou, Kasso; Dauby, Gilles; Duminil, Jérôme; Ewédjé, Eben-Ezer B. K.; Gomez, Céline; Heuertz, Myriam; Koffi, Guillaume K.; Lowe, Andrew J.; Micheneau, Claire; Ndiade-Bourobou, Dyana; Piñeiro, Rosalía; Poncet, Valérie

    2013-07-01

    The biogeographic history of the African rain forests has been contentious. Phylogeography, the study of the geographic distribution of genetic lineages within species, can highlight the signatures of historical events affecting the demography and distribution of species (i.e. population fragmentation or size changes, range expansion/contraction) and, thereby, the ecosystems they belong to. The accumulation of recent data for African rain forests now enables a first biogeographic synthesis for the region. In this review, we explain which phylogeographic patterns are expected under different scenarios of past demographic change, and we give an overview of the patterns detected in African rain forest trees to discuss whether they support alternative hypotheses regarding the history of the African rain forest cover. The major genetic discontinuities in the region support the role of refugia during climatic oscillations, though not necessarily following the classically proposed scenarios. We identify in particular a genetic split between the North and the South of the Lower Guinean region. Finally we provide some perspectives for future study.

  15. Simulation of the West African monsoon onset using the HadGEM3-RA regional climate model

    NASA Astrophysics Data System (ADS)

    Diallo, Ismaïla; Bain, Caroline L.; Gaye, Amadou T.; Moufouma-Okia, Wilfran; Niang, Coumba; Dieng, Mame D. B.; Graham, Richard

    2014-08-01

    The performance of the Hadley Centre Global Environmental Model version 3 regional climate model (HadGEM3-RA) in simulating the West African monsoon (WAM) is investigated. We focus on performance for monsoon onset timing and for rainfall totals over the June-July-August (JJA) season and on the model's representation of the underlying dynamical processes. Experiments are driven by the ERA-Interim reanalysis and follow the CORDEX experimental protocol. Simulations with the HadGEM3 global model, which shares a common physical formulation with HadGEM3-RA, are used to gain insight into the causes of HadGEM3-RA simulation errors. It is found that HadGEM3-RA simulations of monsoon onset timing are realistic, with an error in mean onset date of two pentads. However, the model has a dry bias over the Sahel during JJA of 15-20 %. Analysis suggests that this is related to errors in the positioning of the Saharan heat low, which is too far south in HadGEM3-RA and associated with an insufficient northward reach of the south-westerly low-level monsoon flow and weaker moisture convergence over the Sahel. Despite these biases HadGEM3-RA's representation of the general rainfall distribution during the WAM appears superior to that of ERA-Interim when using Global Precipitation Climatology Project or Tropical Rain Measurement Mission data as reference. This suggests that the associated dynamical features seen in HadGEM3-RA can complement the physical picture available from ERA-Interim. This approach is supported by the fact that the global HadGEM3 model generates realistic simulations of the WAM without the benefit of pseudo-observational forcing at the lateral boundaries; suggesting that the physical formulation shared with HadGEM3-RA, is able to represent the driving processes. HadGEM3-RA simulations confirm previous findings that the main rainfall peak near 10°N during June-August is maintained by a region of mid-tropospheric ascent located, latitudinally, between the cores of

  16. mtDNA control-region sequence variation suggests multiple independent origins of an "Asian-specific" 9-bp deletion in sub-Saharan Africans.

    PubMed Central

    Soodyall, H.; Vigilant, L.; Hill, A. V.; Stoneking, M.; Jenkins, T.

    1996-01-01

    The intergenic COII/tRNA(Lys) 9-bp deletion in human mtDNA, which is found at varying frequencies in Asia, Southeast Asia, Polynesia, and the New World, was also found in 81 of 919 sub-Saharan Africans. Using mtDNA control-region sequence data from a subset of 41 individuals with the deletion, we identified 22 unique mtDNA types associated with the deletion in Africa. A comparison of the unique mtDNA types from sub-Saharan Africans and Asians with the 9-bp deletion revealed that sub-Saharan Africans and Asians have sequence profiles that differ in the locations and frequencies of variant sites. Both phylogenetic and mismatch-distribution analysis suggest that 9-bp deletion arose independently in sub-Saharan Africa and Asia and that the deletion has arisen more than once in Africa. Within Africa, the deletion was not found among Khoisan peoples and was rare to absent in western and southwestern African populations, but it did occur in Pygmy and Negroid populations from central Africa and in Malawi and southern African Bantu-speakers. The distribution of the 9-bp deletion in Africa suggests that the deletion could have arisen in central Africa and was then introduced to southern Africa via the recent "Bantu expansion." PMID:8644719

  17. The Impact of the Atlantic Cold Tongue on West African Monsoon Onset in Regional Model Simulations for 1998-2002

    NASA Technical Reports Server (NTRS)

    Druyan, Leonard M.; Fulakeza, Matthew B.

    2014-01-01

    The Atlantic cold tongue (ACT) develops during spring and early summer near the Equator in the Eastern Atlantic Ocean and Gulf of Guinea. The hypothesis that the ACT accelerates the timing of West African monsoon (WAM) onset is tested by comparing two regional climate model (RM3) simulation ensembles. Observed sea surface temperatures (SST) that include the ACT are used to force a control ensemble. An idealized, warm SST perturbation is designed to represent lower boundary forcing without the ACT for the experiment ensemble. Summer simulations forced by observed SST and reanalysis boundary conditions for each of five consecutive years are compared to five parallel runs forced by SST with the warm perturbation. The article summarizes the sequence of events leading to the onset of the WAM in the Sahel region. The representation of WAM onset in RM3 simulations is examined and compared to Tropical Rainfall Measuring Mission (TRMM), Global Precipitation Climatology Project (GPCP) and reanalysis data. The study evaluates the sensitivity of WAM onset indicators to the presence of the ACT by analysing the differences between the two simulation ensembles. Results show that the timing of major rainfall events and therefore theWAM onset in the Sahel are not sensitive to the presence of the ACT. However, the warm SST perturbation does increase downstream rainfall rates over West Africa as a consequence of enhanced specific humidity and enhanced northward moisture flux in the lower troposphere.

  18. Mesoscale Modeling of Smoke Particles Distribution and Their Radiative Feedback over Northern Sub-Saharan African Region

    NASA Astrophysics Data System (ADS)

    Yue, Y.; Wang, J.; Ichoku, C. M.; Ellison, L.

    2015-12-01

    Stretching from southern boundary of Sahara to the equator and expanding west to east from Atlantic Ocean coasts to the India Ocean coasts, the northern sub-Saharan African (NSSA) region has been subject to intense biomass burning. Comprised of savanna, shrub, tropical forest and a number of agricultural crops, the extensive fires burn belt covers central and south of NSSA during dry season (from October to March) contributes to one of the highest biomass burning rate per km2 in the world. Due to smoke particles' absorption effects of solar radiation, they can modify the surface and atmosphere temperature and thus change atmospheric stability, height of the boundary layer, regional atmospheric circulation, evaporation rate, cloud formation, and precipitation. Hence, smoke particles emitted from biomass burning over NSSA region has a significant influence to the air quality, weather and climate variability. In this study, the first version of this Fire Energetics and Emissions Research (FEER.v1) emissions of several smoke constituents including light-absorbing organic carbon (OC) and black carbon (BC) are applied to a state-of-science meteorology-chemistry model as NOAA Weather Research and Forecasting Model with Chemistry (WRF-Chem). We analyzed WRF-Chem simulations of surface and vertical distribution of various pollutants and their direct radiative effects in conjunction with satellite observation data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar data with Orthogonal Polarization (CALIPSO) to strengthen the importance of combining space measured emission products like FEER.v1 emission inventory with mesoscale model over intense biomass burning region, especially in area where ground-based air-quality and radiation-related observations are limited or absent.

  19. Using community-based participatory mixed methods research to understand preconception health in African American communities of Arizona.

    PubMed

    Hussaini, Khaleel S; Hamm, Eric; Means, Toni

    2013-12-01

    The article discusses Arizona's strategic implementation and evaluation of the first time motherhood initiative grant (FTMI) to understand preconception health among African American men and women in Arizona. Longitudinal focus groups assessed whether African American men and women in the targeted areas comprehended and recalled the messages related to preconception health. Matched pre and posttests assessed community members' knowledge of preconception as well as physicians' perceptions on preconception health and care. Focus-group data were transcribed and coded by independent coders to conduct content analyses. Inter-rater reliability and agreement among coders, bivariate and multivariate statistics were conducted for quantitative matched pre and posttests data using SAS v9.2 (SAS Institute, Cary, NC). The social marketing campaign had limited impact in recall and comprehension of the preconception health message among African American men and women. Data from focus groups revealed that African American men and women perceived preconception health to be vital. And results from the pretest and posttests of community-based presentations, further supported this finding. Evidence from Grand Round presentations indicated that practitioners and health care providers had diverging views on preconception health. Use of community-based participatory mixed methods research can facilitate better understanding of the efficacy of strategic interventions such as FTMI and can provide valuable information on preconception health. Cost limitations often prohibit extensive evaluation of social marketing campaigns, hence, evaluators and researchers should assess the feasibility of conducting an efficacy study versus an effectiveness study in evaluating social marketing campaigns. PMID:23229170

  20. Source regions of whistlers detected in the American, African/European and Western Pacific sectors

    NASA Astrophysics Data System (ADS)

    Koronczay, David; Steinbach, Peter; Lichtenberger, Janos

    2016-04-01

    AWDANet is a recently completed network for automatic whistler detection and analysis. Here we investigate whistler measurements from its first years of operation, analyzing the time distribution of whistlers detected at various stations in Western Antarctica, Southern Africa, Europe and the Western Pacific region. Whistlers detected on the ground are thought to originate in their magnetic conjugate location, travelling through the plasmasphere before returning to the ground. We carry out a correlation analysis, comparing the occurrence of whistler events to lightning strokes using multiple lightning databases, including WWLLN (World Wide Lightning Location Network), to locate the events' source region. Our results can lead to a better understanding of the source regions and mechanisms of whistlers observed on the ground. This knowledge can improve their use as a tool to probe the plasmasphere.

  1. A Regional Stable Carbon Isotope Dendro-Climatology from the South African Summer Rainfall Area

    PubMed Central

    2016-01-01

    Carbon isotope analysis of four baobab (Adansonia digitata L.) trees from the Pafuri region of South Africa yielded a 1000-year proxy rainfall record. The Pafuri record age model was based on 17 radiocarbon dates, cross correlation of the climate record, and ring structures that were presumed to be annual for two of the trees. Here we present the analysis of five additional baobabs from the Mapungubwe region, approximately 200km west of Pafuri. The Mapungubwe chronology demonstrates that ring structures are not necessarily annually formed, and accordingly the Pafuri chronology is revised. Changes in intrinsic water-use efficiency indicate an active response by the trees to elevated atmospheric CO2, but this has little effect on the environmental signal. The revised Pafuri record, and the new Mapungubwe record correlate significantly with local rainfall. Both records confirm that the Medieval Warm Period was substantially wetter than present, and the Little Ice Age was the driest period in the last 1000 years. Although Mapungubwe is generally drier than Pafuri, both regions experience elevated rainfall peaking between AD 1570 and AD 1620 after which dry conditions persist in the Mapungubwe area until about AD 1840. Differences between the two records correlate with Agulhas Current sea-surface temperature variations suggesting east/west displacement of the temperate tropical trough system as an underlying mechanism. The Pafuri and Mapungubwe records are combined to provide a regional climate proxy record for the northern summer rainfall area of southern Africa. PMID:27427912

  2. A Regional Stable Carbon Isotope Dendro-Climatology from the South African Summer Rainfall Area.

    PubMed

    Woodborne, Stephan; Gandiwa, Patience; Hall, Grant; Patrut, Adrian; Finch, Jemma

    2016-01-01

    Carbon isotope analysis of four baobab (Adansonia digitata L.) trees from the Pafuri region of South Africa yielded a 1000-year proxy rainfall record. The Pafuri record age model was based on 17 radiocarbon dates, cross correlation of the climate record, and ring structures that were presumed to be annual for two of the trees. Here we present the analysis of five additional baobabs from the Mapungubwe region, approximately 200km west of Pafuri. The Mapungubwe chronology demonstrates that ring structures are not necessarily annually formed, and accordingly the Pafuri chronology is revised. Changes in intrinsic water-use efficiency indicate an active response by the trees to elevated atmospheric CO2, but this has little effect on the environmental signal. The revised Pafuri record, and the new Mapungubwe record correlate significantly with local rainfall. Both records confirm that the Medieval Warm Period was substantially wetter than present, and the Little Ice Age was the driest period in the last 1000 years. Although Mapungubwe is generally drier than Pafuri, both regions experience elevated rainfall peaking between AD 1570 and AD 1620 after which dry conditions persist in the Mapungubwe area until about AD 1840. Differences between the two records correlate with Agulhas Current sea-surface temperature variations suggesting east/west displacement of the temperate tropical trough system as an underlying mechanism. The Pafuri and Mapungubwe records are combined to provide a regional climate proxy record for the northern summer rainfall area of southern Africa. PMID:27427912

  3. Formation and maintenance of nocturnal low-level stratus over the southern West African monsoon region during AMMA 2006

    NASA Astrophysics Data System (ADS)

    Schuster, Robert; Fink, Andreas; Knippertz, Peter

    2013-04-01

    The southern parts of West Africa, from the coast to about 9°N, are frequently covered by an extensive deck of shallow, low (200 - 400 m above ground) stratus or stratocumulus clouds during the summer monsoon season as shown by recent studies based on ground observations and new satellite products. These clouds usually form at night in association with a nocturnal low-level jet (NLLJ) and can persist into the early afternoon hours until they are dissipated or replaced by fair-weather cumuli. Recent work suggests that the stratus deck and its effect on the surface radiation balance are unsatisfactorily represented in standard satellite retrievals and simulations by state-of-the-art climate models. Here we use high-resolution regional simulations with the Weather Research and Forecast (WRF) model and observations from the African Monsoon Multidisciplinary Analysis (AMMA) 2006 campaign to investigate (a) the spatiotemporal distribution, (b) the influence on the radiation balance, and (c) the detailed formation and maintenance mechanisms of the stratiform clouds. The model configuration used for this study has been determined following an extensive sensitivity study. The main conclusions are: (a) At least some configurations of WRF satisfactorily reproduce the diurnal cycle of the low cloud evolution. (b) The simulated stratus deck forms after sunset along the coast, spreads inland in the course of the night, and dissipates in the early afternoon. (c) The average surface net radiation balance in stratus-dominated regions is 35 W m-2 lower than in those with less clouds. (d) The cloud formation is related to a subtle balance between "stratogenic" upward (downward) fluxes of latent (sensible) heat caused by shear-driven turbulence below the NLLJ, cold advection from the ocean, forced lifting at the windward side of orography, and radiative cooling on one hand, and "stratolytic" dry advection and latent heating on the other hand. Future work should focus on the influence

  4. Integrating Oral Health with Non-Communicable Diseases as an Essential Component of General Health: WHO's Strategic Orientation for the African Region.

    PubMed

    Varenne, Benoit

    2015-05-01

    In the context of the emerging recognition of non-communicable diseases (NCDs), it has never been more timely to explore the World Health Organization (WHO) strategic orientations on oral health in the WHO African region and to raise awareness of a turning point in the search for better oral health for everyone. The global initiative against NCDs provides a unique opportunity for the oral health community to develop innovative policies for better recognition of oral health, as well as to directly contribute to the fight against NCDs and their risk factors. The WHO African region has led the way in developing the first regional oral health strategy for the prevention and control of oral diseases integrated with NCDs. The support of the international oral health community in this endeavor is urgently needed for making a success story of this initiative of integrating oral health into NCDs. PMID:25941239

  5. Regional method to assess offshore slope stability.

    USGS Publications Warehouse

    Lee, H.J.; Edwards, B.D.

    1986-01-01

    The slope stability of some offshore environments can be evaluated by using only conventional acoustic profiling and short-core sampling, followed by laboratory consolidation and strength testing. The test results are synthesized by using normalized-parameter techniques. The normalized data are then used to calculate the critical earthquake acceleration factors or the wave heights needed to initiate failure. These process-related parameters provide a quantitative measure of the relative stability for locations from which short cores were obtained. The method is most applicable to offshore environments of gentle relief and simple subsurface structure and is not considered a substitute for subsequent site-specific analysis. -from ASCE Publications Information

  6. The impact of the African Great Lakes on the regional climate in a dynamically downscaled CORDEX simulation

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Panitz, Hans-Jürgen; Davin, Edouard; van Lipzig, Nicole

    2014-05-01

    Owing to the strong contrast in albedo, roughness and heat capacity between land and water, lakes significantly influence the exchange of moisture, heat and momentum between the surface and the boundary layer. To investigate this two-way interaction, a correct representation of lakes within regional climate models is essential. To this end, the one-dimensional lake parameterisation scheme FLake was recently coupled to the regional climate model COSMO-CLM (CCLM). One region where lakes constitute a key component of the climate system is the African Great Lakes region. In this study, the CCLM CORDEX-Africa evaluation simulation is dynamically downscaled from 0.44° (50 km) to 0.0625° (7 km) over East-Africa, an unprecedented resolution for this region. The performance of different CCLM configurations are compared for the period 1999-2008: in particular, CCLM is tested for its sensitivity to the choice of the lake surface temperature description (SST, FLake, an improved version of FLake and Hostetler) and the land surface model (Terra and Community Land Model). Model results are evaluated in a three-step procedure. First, the atmospheric state variables near-surface temperature, precipitation, surface energy fluxes, fractional cloud cover and column precipitable water are evaluated using in-situ based and satellite-derived products. Second, a comprehensive set of in-situ water temperature profile observations serves to evaluate the temporal evolution of water temperatures at three sites: Lake Kivu (Ishungu), Lake Tanganyika's northern basin (Kigoma) and southern basin (Mpulungu). Finally, spatial variability of surface temperatures in Lake Kivu and Lake Tanganyika are evaluated on the basis of satellite-derived lake surface temperatures. Subsequently, the preferred model configuration is used to quantify and understand effects by lakes reported for other regions in the world, such as a dampened diurnal temperature range, enhanced evaporation, modified surface layer

  7. Regional differences in seasonal timing of rainfall discriminate between genetically distinct East African giraffe taxa.

    PubMed

    Thomassen, Henri A; Freedman, Adam H; Brown, David M; Buermann, Wolfgang; Jacobs, David K

    2013-01-01

    Masai (Giraffa tippelskirchi), Reticulated (G. reticulata) and Rothschild's (G. camelopardalis) giraffe lineages in East Africa are morphologically and genetically distinct, yet in Kenya their ranges abut. This raises the question of how divergence is maintained among populations of a large mammal capable of long-distance travel, and which readily hybridize in zoos. Here we test four hypotheses concerning the maintenance of the phylogeographic boundaries among the three taxa: 1) isolation-by-distance; 2) physical barriers to dispersal; 3) general habitat differences resulting in habitat segregation; or 4) regional differences in the seasonal timing of rainfall, and resultant timing of browse availability. We used satellite remotely sensed and climate data to characterize the environment at the locations of genotyped giraffes. Canonical variate analysis, random forest algorithms, and generalized dissimilarity modelling were employed in a landscape genetics framework to identify the predictor variables that best explained giraffes' genetic divergence. We found that regional differences in the timing of precipitation, and resulting green-up associated with the abundance of browse, effectively discriminate between taxa. Local habitat conditions, topographic and human-induced barriers, and geographic distance did not aid in discriminating among lineages. Our results suggest that selection associated with regional timing of events in the annual climatic cycle may help maintain genetic and phenotypic divergence in giraffes. We discuss potential mechanisms of maintaining divergence, and suggest that synchronization of reproduction with seasonal rainfall cycles that are geographically distinct may contribute to reproductive isolation. Coordination of weaning with green-up cycles could minimize the costs of lactation and predation on the young. Our findings are consistent with theory and empirical results demonstrating the efficacy of seasonal or phenologically dictated

  8. Regional Differences in Seasonal Timing of Rainfall Discriminate between Genetically Distinct East African Giraffe Taxa

    PubMed Central

    Thomassen, Henri A.; Freedman, Adam H.; Brown, David M.; Buermann, Wolfgang; Jacobs, David K.

    2013-01-01

    Masai (Giraffa tippelskirchi), Reticulated (G. reticulata) and Rothschild's (G. camelopardalis) giraffe lineages in East Africa are morphologically and genetically distinct, yet in Kenya their ranges abut. This raises the question of how divergence is maintained among populations of a large mammal capable of long-distance travel, and which readily hybridize in zoos. Here we test four hypotheses concerning the maintenance of the phylogeographic boundaries among the three taxa: 1) isolation-by-distance; 2) physical barriers to dispersal; 3) general habitat differences resulting in habitat segregation; or 4) regional differences in the seasonal timing of rainfall, and resultant timing of browse availability. We used satellite remotely sensed and climate data to characterize the environment at the locations of genotyped giraffes. Canonical variate analysis, random forest algorithms, and generalized dissimilarity modelling were employed in a landscape genetics framework to identify the predictor variables that best explained giraffes' genetic divergence. We found that regional differences in the timing of precipitation, and resulting green-up associated with the abundance of browse, effectively discriminate between taxa. Local habitat conditions, topographic and human-induced barriers, and geographic distance did not aid in discriminating among lineages. Our results suggest that selection associated with regional timing of events in the annual climatic cycle may help maintain genetic and phenotypic divergence in giraffes. We discuss potential mechanisms of maintaining divergence, and suggest that synchronization of reproduction with seasonal rainfall cycles that are geographically distinct may contribute to reproductive isolation. Coordination of weaning with green-up cycles could minimize the costs of lactation and predation on the young. Our findings are consistent with theory and empirical results demonstrating the efficacy of seasonal or phenologically dictated

  9. Crystal forms and surface textures of alluvial diamonds from the Western Region of the Central African Republic

    NASA Astrophysics Data System (ADS)

    Censier, C.; Tourenq, J.

    1995-06-01

    The most common crystal forms of the diamonds from the alluvial deposits in the Western Region of the Central African Republic were examined by scanning electron microscope (SEM) in an attempt to determine their geological history. The marks observed are related to two distinct periods in the geological history of the diamonds: the magmatic episode and their hydraulic transport. The effects of significant magmatic corrosion undergone by the diamonds during their ascent from the upper mantle are shown by the predominance of rhombododecahedral forms over octahedral forms and the frequent occurrence on the crystal faces of pyramidal depressions with triangular (111) or square (100) bases, as well as of V-shaped figures (111) or stepped figures (on the faces around the ternary axes). Some impact marks probably occurred during the explosive episode of kimberlite extrusion. Other impact marks, the marks of general wear, and the high proportion of gemstone-quality diamonds indicate the lengthy transport. They thus also indicate that the diamonds have undergone a prolonged geological history after the erosion of the kimberlite. This suggests that the kimberlite are separated from the Carnot Sandstone Formation by a considerable distance. The diamonds were stored in Albian-Maastrichtian rocks before they become concentrated in the Recent alluvium.

  10. Characterisation of GPS-TEC in the African equatorial and low latitude region and the regional evaluation of the IRI model

    NASA Astrophysics Data System (ADS)

    Adebiyi, S. J.; Adimula, I. A.; Oladipo, O. A.

    2016-06-01

    With the increasing application of Global Navigation Satellite System (GNSS) products and services, knowledge of the Total Electron Content (TEC) variation is vital, particularly in historically under-sampled regions. The ionospheric induced-error, which is the largest and most variable error source of GNSS applications, is proportional to TEC along the satellite-receiver path. Simultaneous Global Positioning System (GPS) measurements from six African equatorial and low latitude stations in the southern hemisphere are used to investigate the latitudinal variation of TEC over the region during the year 2013, a year of moderate solar activity. The analysis reveals some detailed features of seasonal, month-to-month and solar activity dependence of TEC. The seasonal variation of TEC revealed that the daytime and the pre-midnight values of TEC for stations located close to the geographic equator is considerably higher in equinoxes and June solstice compared to stations farther from the equator, however, the difference is insignificant during the December solstice. The month-to-month variation of TEC shows semi-annual symmetry/asymmetry in TEC values for stations closer/farther from the equator. TEC sensitivity to solar activity shows significant seasonal and latitudinal characteristics. Generally, a relatively good correlation exists between TEC and F10.7 for stations around the Equatorial Ionization Anomaly (EIA) region compared to those found at stations close to the equator. Beyond the EIA region, the correlation coefficients drop in all seasons. TEC predicted by the three topside options of the International Reference Ionosphere (IRI) 2012 model [i.e. the NeQuick (NeQ), IRI-2001 Corrected (IRI-01 Corr) and the IRI-2001 (IRI-01) options] exhibits latitudinal and seasonal characteristics. The NeQ option performed better than the other two options at stations located within the equatorial region in most of the months and seasons. Outside the EIA region, the IRI-01 Corr

  11. Evaluation of Methods for Measuring Soil Organic Carbon in West African Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased interest in implementing projects in the Sahel region of Africa for sequestration of atmospheric carbon dioxide in soil organic matter has intensified the need for methods that accurately measure soil C but are also suitable for use by often resource limited soil analysis laboratories in t...

  12. Assessing the Effects of Burned Areas on the Northern and Southern African Seasonal Climates: a Regional Modeling Study

    NASA Astrophysics Data System (ADS)

    De Sales, F.; Okin, G. S.; Xue, Y.; Dintwe, K.

    2015-12-01

    The occurrence of wildfires, whether natural or anthropogenic, is an important disturbance of the terrestrial ecosystems as it plays an essential role in shaping global and regional vegetation. This study presents an investigation of the impact of burned areas on the surface energy balance and precipitation in northern and southern Africa as simulated by a state-of-the-art regional modeling system. Mean burned area fraction derived from MODIS date-of-burning product was implemented in a set of WRF/SSiB2 simulations. Vegetation cover and LAI were degraded based on mean burned area fraction and survival rate for each vegetation land cover type. Additionally, ground darkening associated with ash and charcoal deposition was imposed by temporarily lowering the ground albedo after burning. Wildfire-induced vegetation and ground degradation increased the surface albedo by exposing the brighter bare ground of the region, which in turn caused a decrease in surface net radiation and evapotranspiration. Overall, post-fire land condition resulted in a decrease in precipitation over sub-Saharan Africa, associated with the weakening of the West African monsoon progression through the region. A decrease in atmospheric moisture flux convergence was observed in the burned areas, which played a dominant role in reducing precipitation. The areas with the largest precipitation impact were those covered by savannas and rainforests, where annual precipitation decreased by 3.8% and 3.3%, respectively. The resulting precipitation decrease and vegetation deterioration caused a drop in gross primary productivity in the region, which was strongest in late winter and early spring. This study suggests that the cooling and drying of atmosphere induced by the burned areas led to strengthening of subsidence during pre-onset and weakening of upward motion during onset and mature stages of the monsoon leading to a waning of convective instability and precipitation. Vertical air movement over the

  13. Assessment of the petroleum, coal, and geothermal resources of the Economic Community of West African States (ECOWAS) region

    USGS Publications Warehouse

    Mattick, R. E., (compiler)

    1982-01-01

    Approximately 85 percent of the land area of the ECOWAS (Economic Community of West African States) region is covered by basement rocks (igneous and highly metamorphosed rocks) or relatively thin layers of Paleozoic, Upper Precambrian, and 'Continental Intercalaire? sedimentary rocks. These areas have little or no petroleum potential. Areas of the ECOWAS region that have potential for petroleum production or potential for increased petroleum production include the narrow belt of sedimentary rocks that stretches along the continental margin from Mauritania to Nigeria and the Niger Delta and the Benue depression. The Senegal Basin, located on the continental margin of Mauritania, Senegal, Gambia, Guinea Bissau, and Guinea, has been intensely explored by the oil industry and most of the larger structures onshore and on the shelf probably have been tested by drilling with little or no resulting commercial production. Unless basic ideas pertaining to the petroleum geology of the Senegal Basin are revised, future discoveries are expected to be limited to small fields overlooked by industry at a time when petroleum prices were low. On the continental shelf of Sierra Leone and the continental shelf of northeast and central Liberia, the sedimentary rocks are relatively thin, and industry has shown little interest in the area. On the continental rise of these countries, however, the sedimentary section, deposited in a complex fault-block system, increases in thickness. A renewal of industry interest in this deep-water area will probably follow further development of deep-water production technology. A recent oil discovery on the continental slope off the Ivory Coast is expected to spur further exploration offshore of southeastern Liberia, Ivory Coast, Ghana, Togo, and Benin. This relatively unexplored area in the Gulf of Guinea has good possibilities .for the discovery of giant oil fields. Nigeria's oil development from the Niger Delta may have peaked, as 13 of 14 giant oil

  14. Tropical convective systems life cycle characteristics from geostationary satellite and precipitating estimates derived from TRMM and ground weather radar observations for the West African and South American regions

    NASA Astrophysics Data System (ADS)

    Fiolleau, T.; Roca, R.; Angelis, F. C.; Viltard, N.

    2012-12-01

    In the tropics most of the rainfall comes in the form of individual storm events embedded in the synoptic circulations (e.g., monsoons). Understanding the rainfall and its variability hence requires to document these highly contributing tropical convective systems (MCS). Our knowledge of the MCS life cycle, from a physical point of view mainly arises from individual observational campaigns heavily based on ground radar observations. While this large part of observations enabled the creation of conceptual models of MCS life cycle, it nevertheless does not reach any statistically significant integrated perspective yet. To overcome this limitation, a composite technique, that will serve as a Day-1 algorithm for the Megha-Tropiques mission, is considered in this study. this method is based on a collocation in space and time of the level-2 rainfall estimates (BRAIN) derived from the TMI radiometer onboard TRMM with the cloud systems identified by a new MCS tracking algorithm called TOOCAN and based on a 3-dimensional segmentation (image + time) of the geostationary IR imagery. To complete this study, a similar method is also developed collocating the cloud systems with the precipitating features derived from the ground weather radar which has been deployed during the CHUVA campaign over several Brazilian regions from 2010 up to now. A comparison of the MCSs life cycle is then performed for the 2010-2012 summer seasons over the West African, and South American regions. On the whole region of study, the results show that the temporal evolution of the cold cloud shield associated to MCSs describes a symmetry between the growth and the decay phases. It is also shown that the parameters of the conceptual model of MCSs are strongly correlated, reducing thereby the problem to a single degree of freedom. At the system scale, over both land and oceanic regions, rainfall is described by an increase at the beginning (the first third) of the life cycle and then smoothly decreases

  15. Mapping the earth conductivity-depth structure of African geomagnetic equatorial anomaly regions using solar quiet current variations

    NASA Astrophysics Data System (ADS)

    Ugbor, D. O.; Okeke, F. N.; Yumoto, K.

    2016-04-01

    The solar quiet day ionospheric (Sq) current variations observed in Abuja, Bangui and Addis Ababa were used to delineate the mantle conductivity-depth structure along the equatorial African regions. Spherical harmonic analysis (SHA) was employed in separating the internal and external field contributions to the Sq variations. For each of the paired external and internal coefficients of the SHA, we used transfer function to compute the conductivity-depth profile for the region. Strikingly, we observed increased electrical conductivity values in the Earth layers and deep depth penetration. The calculated average electrical conductivity values in Addis Ababa and Abuja are 0.087 Sm-1 and 0.104 Sm-1 at depths of 93 km and 121 km respectively. These values suddenly rose to 0.235 Sm-1 and 0.222 Sm-1 at depths of 440 km and 427 km respectively. In Bangui, the calculated average values are 0.092 Sm-1, 0.144 Sm-1, 0.312 Sm-1 and 0.466 Sm-1 at 96 km, 300 km, 834 km and 1228 km depths respectively. At the greatest depths of penetration of 1412 km, 1385 km and 1278 km in Addis Ababa, Abuja and Bangui, the electrical conductivity attained the highest values of 0.415 Sm-1, 0.467 Sm-1 and 0.515 Sm-1 respectively. Two most Earth conductive layers were discovered in the magnetic equatorial zone. These layers lie between the depth of about 100 and 400 km within the upper mantle and beyond 1200 km in the lower mantle. It can be inferred that the closer one goes towards the Earth magnetic equator; the deeper the Sq current can penetrate the Earth's interior.

  16. Methods for assessing movement path recursion with application to African buffalo in South Africa

    USGS Publications Warehouse

    Bar-David, S.; Bar-David, I.; Cross, P.C.; Ryan, S.J.; Knechtel, C.U.; Getz, W.M.

    2009-01-01

    Recent developments of automated methods for monitoring animal movement, e.g., global positioning systems (GPS) technology, yield high-resolution spatiotemporal data. To gain insights into the processes creating movement patterns, we present two new techniques for extracting information from these data on repeated visits to a particular site or patch ("recursions"). Identification of such patches and quantification of recursion pathways, when combined with patch-related ecological data, should contribute to our understanding of the habitat requirements of large herbivores, of factors governing their space-use patterns, and their interactions with the ecosystem. We begin by presenting output from a simple spatial model that simulates movements of large-herbivore groups based on minimal parameters: resource availability and rates of resource recovery after a local depletion. We then present the details of our new techniques of analyses (recursion analysis and circle analysis) and apply them to data generated by our model, as well as two sets of empirical data on movements of African buffalo (Syncerus coffer): the first collected in Klaserie Private Nature Reserve and the second in Kruger National Park, South Africa. Our recursion analyses of model outputs provide us with a basis for inferring aspects of the processes governing the production of buffalo recursion patterns, particularly the potential influence of resource recovery rate. Although the focus of our simulations was a comparison of movement patterns produced by different resource recovery rates, we conclude our paper with a comprehensive discussion of how recursion analyses can be used when appropriate ecological data are available to elucidate various factors influencing movement. Inter alia, these include the various limiting and preferred resources, parasites, and topographical and landscape factors. ?? 2009 by the Ecological Society of America.

  17. REGIONAL VULNERABILITY ASSESSMENT OF THE MID-ATLANTIC REGION: EVALUATION OF INTEGRATION METHODS AND ASSESSMENTS RESULTS

    EPA Science Inventory

    This report describes methods for quantitative regional assessment developed by the Regional Vulnerability Assessment (ReVA) program. The goal of ReVA is to develop regional-scale assessments of the magnitude, extent, distribution, and uncertainty of current and anticipated envir...

  18. Derivation of detrital rutile in the Yaoundé region from the Neoproterozoic Pan-African belt in southern Cameroon (Central Africa)

    NASA Astrophysics Data System (ADS)

    Stendal, Henrik; Toteu, Sadrack Félix; Frei, Robert; Penaye, Joseph; Njel, Urbain Olivier; Bassahak, Jean; Nni, Jean; Kankeu, Boniface; Ngako, Vincent; Hell, Joseph Victor

    2006-04-01

    Rutile, as an important component in alluvial or eluvial heavy mineral deposits, is known in southern Cameroon. These deposits are underlain by the Neoproterozoic low- to high-grade Yaoundé Group. Geochemical, thermometric, fluid inclusion and Pb isotopic studies of the rutile from alluvial and eluvial concentrates and from medium-grade micaschist from the nearby Yaoundé region permit the following conclusions: (1) alluvial and eluvial rutile of the Yaoundé region are derived from the degradation of metapelites, metamafic rocks and pegmatites of the nearby Yaoundé Group; (2) rutile in the Yaoundé Group formed during the Pan-African metamorphism, or was inherited as detrital rutile from a ˜900 Ma source. The study also shows that the rutile can be used to trace the history of the Pan-African belt north of the Congo craton.

  19. Association of Socioeconomic Status with Overall and Cause Specific Mortality in the Republic of Seychelles: Results from a Cohort Study in the African Region

    PubMed Central

    Stringhini, Silvia; Rousson, Valentin; Viswanathan, Bharathi; Gedeon, Jude; Paccaud, Fred; Bovet, Pascal

    2014-01-01

    Background Low socioeconomic status (SES) is consistently associated with higher mortality in high income countries. Only few studies have assessed this association in low and middle income countries, mainly because of sparse reliable mortality data. This study explores SES differences in overall and cause-specific mortality in the Seychelles, a rapidly developing small island state in the African region. Methods All deaths have been medically certified over more than two decades. SES and other lifestyle-related risk factors were assessed in a total of 3246 participants from three independent population-based surveys conducted in 1989, 1994 and 2004. Vital status was ascertained using linkage with vital statistics. Occupational position was the indicator of SES used in this study and was assessed with the same questions in the three surveys. Results During a mean follow-up of 15.0 years (range 0–23 years), 523 participants died (overall mortality rate 10.8 per 1000 person-years). The main causes of death were cardiovascular disease (CVD) (219 deaths) and cancer (142 deaths). Participants in the low SES group had a higher mortality risk for overall (HR = 1.80; 95% CI: 1.24–2.62), CVD (HR = 1.95; 1.04–3.65) and non-cancer/non-CVD (HR = 2.14; 1.10–4.16) mortality compared to participants in the high SES group. Cancer mortality also tended to be patterned by SES (HR = 1.44; 0.76–2.75). Major lifestyle-related risk factors (smoking, heavy drinking, obesity, diabetes, hypertension, hypercholesterolemia) explained a small proportion of the associations between low SES and all-cause, CVD, and non-cancer/non-CVD mortality. Conclusions In this population-based study assessing social inequalities in mortality in a country of the African region, low SES (as measured by occupational position) was strongly associated with overall, CVD and non-cancer/non-CVD mortality. Our findings support the view that the burden of non-communicable diseases may

  20. Low Prevalence of Liver Disease but Regional Differences in HBV Treatment Characteristics Mark HIV/HBV Co-Infection in a South African HIV Clinical Trial

    PubMed Central

    Ive, Prudence; MacLeod, William; Mkumla, Nompumelelo; Orrell, Catherine; Jentsch, Ute; Wallis, Carole L.; Stevens, Wendy; Wood, Robin; Sanne, Ian; Bhattacharya, Debika

    2013-01-01

    Background Hepatitis B virus (HBV) infection is endemic in South Africa however, there is limited data on the degree of liver disease and geographic variation in HIV/HBV coinfected individuals. In this study, we analysed data from the CIPRA-SA ‘Safeguard the household study’ in order to assess baseline HBV characteristics in HIV/HBV co-infection participants prior to antiretroviral therapy (ART) initiation. Methods 812 participants from two South African townships Soweto and Masiphumelele were enrolled in a randomized trial of ART (CIPRA-SA). Participants were tested for hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and HBV DNA. FIB-4 scores were calculated at baseline. Results Forty-eight (5.9%) were HBsAg positive, of whom 28 (58.3%) were HBeAg positive. Of those with HBV, 29.8% had an HBV DNA<2000 IU/ml and ALT<40 IU/ml ; 83.0% had a FIB-4 score <1.45, consistent with absent or minimal liver disease. HBV prevalence was 8.5% in Masiphumelele compared to 3.8% in Soweto (relative risk 2.3; 95% CI: 1.3–4.0). More participants in Masiphumelele had HBeAg-negative disease (58% vs. 12%, p = 0.002) and HBV DNA levels ≤2000 IU/ml, (43% vs. 6% p<0.007). Conclusion One third of HIV/HBV co-infected subjects had low HBV DNA levels and ALT while the majority had indicators of only mild liver disease. There were substantial regional differences in HBsAg and HbeAg prevalence in HIV/HBV co-infection between two regions in South Africa. This study highlights the absence of severe liver disease and the marked regional differences in HIV/HBV co-infection in South Africa and will inform treatment decisions in these populations. PMID:24324573

  1. A Mixed-Method Analysis of African-American Women's Attendance at an HIV Prevention Intervention

    ERIC Educational Resources Information Center

    Pinto, R. M.; McKay, M. M.

    2006-01-01

    Grounded in a model of service utilization, this study conceptualizes attendance of African-American women at an HIV prevention intervention as associated with influences across three ecological domains--individual, service (program), and social network. First, the texts of responses to semistructured, open-ended elicitation interviews were…

  2. Resisting Dominant Discourses: Implications of Indigenous, African Feminist Theory and Methods for Gender and Education Research

    ERIC Educational Resources Information Center

    Chilisa, Bagele; Ntseane, Gabo

    2010-01-01

    In this paper we explore tensions between Western gender theory and research, and post-colonial and indigenous feminist standpoints, which challenge us to re-define our roles as feminist-activist educators and researchers working with formerly colonised and historically marginalised communities. We discuss how African and Black feminist approaches…

  3. Health Risk Behaviors of African American Adolescents with Mild Mental Retardation: Prevalence Depends on Measurement Method.

    ERIC Educational Resources Information Center

    Pack, Robert P.; Browne, Dorothy; Wallander, Jan L.

    1998-01-01

    Health risk behaviors (substance use, violence, suicide, and car safety) of 194 African American urban adolescents with mild mental retardation were measured using either a confidential individual interview or an anonymous group survey. The survey methodology resulted in disclosure of more risk behaviors than the interview methodology. Elevated…

  4. A Researcher "Called" to "Taboo" Places?: A Burgeoning Research Method in African-Centered Education

    ERIC Educational Resources Information Center

    Shockley, Kmt G.

    2009-01-01

    This article presents a self-reflexive analysis of the complexities of conducting Afrocentric education research while living with a "double consciousness." Having been "called" to places that are considered to be "taboo" the author takes readers on a journey that begins in his busy mind and ends in on the African continent in a "rabbit hole."…

  5. Region change rate-driven seamline determination method

    NASA Astrophysics Data System (ADS)

    Pan, Jun; Wang, Mi; Li, Junli; Yuan, Shenggu; Hu, Fen

    2015-07-01

    This paper presents a novel method of seamline determination using region change rate (RCR) for orthoimage mosaicking. RCR is the change rate of the segmented region and is calculated based on the percentage of changed pixels in the segmented region. The presented method contains a two-level seamline optimization procedure to determine the final seamline using RCR. First, an object-level optimization based on image segmentation and change detection is executed to determine the allowed regions, i.e., the connected regions with minimized maximum RCR value through which seamlines are allowed to pass. This optimization is used to limit the maximum RCR along the seamline. Second, to determine the optimized seamline, pixel-level optimization is performed using Dijkstra's algorithm based on differential cost. Finally, experimental results from digital aerial orthoimages and comparisons with other methods demonstrate the potential of the presented method for seamline determination.

  6. Future water availability in North African dams simulated by high-resolution regional climate models

    NASA Astrophysics Data System (ADS)

    Tramblay, Yves; Jarlan, Lionel; Hanich, Lahoucine; Somot, Samuel

    2016-04-01

    In North Africa, the countries of Morocco, Algeria and Tunisia are already experiencing water scarcity and a strong interannual variability of precipitation. To better manage their existing water resources, several dams and reservoirs have been built on most large river catchments. The objective of this study is to provide quantitative scenarios of future changes in water availability for the 47 major dams and reservoirs catchments located in North Africa. An ensemble of regional climate models (RCM) with a spatial resolution of 12km, driven by different general circulation models (GCM), from the EuroCORDEX experiment have been considered to analyze the projected changes on temperature, precipitation and potential evapotranspiration (PET) for two scenarios (RCP4.5 and RCP8.5) and two time horizons (2040-2065 and 2065-2090). PET is estimated from RCM outputs either with the FAO-Penman-Monteith (PM) equation, requiring air temperature, relative humidity, net radiation and wind, or with the Hargreave Samani (HS) equation, requiring only air temperature. The water balance is analyzed by comparing the climatic demand and supply of water, considering that for most of these catchments groundwater storage is negligible over long time periods. Results indicated a future temperature increase for all catchments between +1.8° and +4.2°, depending on the emission scenario and the time period considered. Precipitation is projected to decrease between -14% to -27%, mainly in winter and spring, with a strong East to West gradient. PET computed from PM or HS formulas provided very similar estimates and projections, ranging between +7% to +18%. Changes in PET are mostly driven by rising temperatures and are greatest during dry summer months than for the wet winter season. Therefore the increased PET has a lower impact than declining precipitation on future water availability, which is expected to decrease by -19% to -33% on average.

  7. The African superswell

    NASA Technical Reports Server (NTRS)

    Nyblade, Andrew A.; Robinson, Scott W.

    1994-01-01

    Maps of residual bathymetry in the ocean basins around the African continent reveal a broad bathymetric swell in the southeastern Atlantic Ocean with an amplitude of about 500 m. We propose that this region of anomalously shallow bathymetry, together with the contiguous eastern and southern African plateaus, form a superswell which we refer to as the African superswell. The origin of the African superswell is uncertain. However, rifting and volcanism in eastern Africa, as well as heat flow measurements in southern Africa and the southeastern Atlantic Ocean, suggest that the superswell may be attributed, at least in part, to heating of the lithosphere.

  8. Seismic structure of the crust and lithospheric mantle of the southern African cratonic region

    NASA Astrophysics Data System (ADS)

    Youssof, M.; Thybo, H.; Artemieva, I. M.; Levander, A.

    2013-12-01

    We present a new seismic model for the structure of the crust and lithospheric mantle in southern Africa constrained by a joint study of seismic receiver functions and finite-frequency tomography, using the high-quality data from the South Africa Seismic Experiment (SASE). A) The crust has a highly heterogeneous structure with short wavelength variations in (i) thickness, (ii) composition (reflected in Vp/Vs-ratio calculated for all SASE stations), and (iii) Moho sharpness (which is quantified and mapped for the entire region) (Youssof et al., Tectonophysics, in review). By mapping these three parameters, we distinguish ~20 crustal blocks that do not everywhere coincide with surface tectonic features. Our RFs also demonstrate strong azimuthal anisotropy in the crust, with a typical crustal contribution to the total S-wave splitting of at least 30%. Spatial correlation of the S-wave polarization directions of crustal and mantle anisotropy indicates (i) the presence of three distinct Archean lithospheric terranes and (ii) coupling between the crust and lithospheric mantle in most of the study area, with a strong decoupling in western Kaapvaal where the crustal anisotropy is strongest. The similarity of anisotropy directions in the crust and mantle beneath much of the Kaapvaal craton indicates that (a) the seismic anisotropy originates at the time of cratonization and (b) the observed correspondence between the present direction of absolute plate motion (APM) and lithosphere anisotropy is coincidental. B) A new 3D high-resolution seismic model of the lithospheric mantle has been determined from finite frequency tomographic inversions of teleseismic P- and S- body wave data. The two velocity models are very similar in structure, but differ in the relative P- and S-wave velocity anomalies. We find that: 1) the fast lithospheric keels extends very deep, perhaps to depths of 300-350 km and 250 km beneath the Kaapvaal and Zimbabwe cratons, respectively, and 2) the Archean

  9. Schumann Resonance spectra decomposition method and studies of the locations of the African thunderstorm centres

    NASA Astrophysics Data System (ADS)

    Dyrda, Michal; Kulak, Andrzej; Mlynarczyk, Janusz; Ostrowski, Michal; Kubisz, Jerzy; Michalec, Adam; Nieckarz, Zenon

    2014-05-01

    The idea, that the global atmospheric electric circuit is driven by global lightning activity was introduced at the beginning of the last century. Today, the different observational methods are used from satellites to the radio observations performed in the extremely low frequency (ELF) range to evaluate local as well as global lightning activity, its spatial and temporal variability and influence on our planet and Earth's climate. The ground-based thunderstorms observations, particularly ELF, also allow the measurements of the dipole moment of discharges. Global lightning activity excites the Earth-ionosphere cavity and the produced electromagnetic radiation is responsible for generating the Schumann resonance (SR). The interaction of the standing and travelling waves leads to asymmetric shape of the observational SR power spectra picks, which was noticed by Kułak et al. (2006). They proposed a spectral decomposition method, what allows to separate the resonant field from the travelling wave contribution, which can be dominant at small distances from the sources. In such approach, one can apply the inverse problem solution for determining a distance of the dominant signal source. The distances to the thunderstorm centres are calculated using the numerical as well as the analytical models for the electromagnetic waves propagation in the Earth-ionosphere cavity. The ELF electromagnetic waves, recorded by Hylaty ELF station, located in South-East of Poland are used to derive the distances to the most powerful thunderstorm centres located in Africa and hence to obtain 1-D thunderstorm lightning activity maps. The observational data taken in January and August 2011 were binned in 10 minute intervals and SR power spectra were derived. Then a curve describing seven asymmetric SR maxima was fitted to the spectrum for each time interval. We use chi-squared test to compare the resulted decomposed power spectra with curves obtained within the considered numerical and

  10. Preventing cognitive decline in older African Americans with mild cognitive impairment: design and methods of a randomized clinical trial.

    PubMed

    Rovner, Barry W; Casten, Robin J; Hegel, Mark T; Leiby, Benjamin E

    2012-07-01

    Mild Cognitive Impairment (MCI) affects 25% of older African Americans and predicts progression to Alzheimer's disease. An extensive epidemiologic literature suggests that cognitive, physical, and/or social activities may prevent cognitive decline. We describe the methods of a randomized clinical trial to test the efficacy of Behavior Activation to prevent cognitive decline in older African Americans with the amnestic multiple domain subtype of MCI. Community Health Workers deliver 6 initial in-home treatment sessions over 2-3 months and then 6 subsequent in-home booster sessions using language, materials, and concepts that are culturally relevant to older African Americans during this 24 month clinical trial. We are randomizing 200 subjects who are recruited from churches, senior centers, and medical clinics to Behavior Activation or Supportive Therapy, which controls for attention. The primary outcome is episodic memory as measured by the Hopkins Verbal Learning Test-Revised at baseline and at months 3, 12, 18, and 24. The secondary outcomes are general and domain-specific neuropsychological function, activities of daily living, depression, and quality-of-life. The negative results of recent clinical trials of drug treatments for MCI and Alzheimer's disease suggest that behavioral interventions may provide an alternative treatment approach to preserve cognition in an aging society. PMID:22406101

  11. Response of Seasonal Atlantic Tropical Cyclone Activity to Suppression of African Easterly Waves in a Regional Climate Model

    NASA Astrophysics Data System (ADS)

    Patricola, C. M.; Saravanan, R.; Chang, P.

    2014-12-01

    Atlantic tropical cyclones and African easterly waves (AEWs) are strongly linked on the synoptic timescale, with about 85% of observed major Atlantic hurricanes originating from AEWs (e.g., Landsea et al. 1993). However, the influence of variability in AEWs on seasonal Atlantic tropical cyclone activity is not fully understood; a positive correlation between AEW activity and Atlantic tropical cyclone activity exists on the interannual timescale during just some periods of the observational record (e.g., Thorncroft and Hodges, 2001; Hopsch et al. 2007). This study investigates the impact of AEWs on seasonal Atlantic tropical cyclone activity using regional climate model simulations in which AEWs were either prescribed or removed through the lateral boundary condition (LBC). The control simulation (10-member ensemble) was run at 27 km resolution and used 6-hourly LBCs from the NCEP CFS Reanalysis and daily NOAA Optimum Interpolation (OI) V2 sea surface temperature (SST) from the year 2005. In the experiment AEWs were suppressed by filtering 2-10 day variability over tropical latitudes from the eastern LBC, located along the west coast of the Sahel. The difference in Atlantic tropical cyclone frequency was insignificant between the simulations in which AEWs were prescribed versus suppressed, indicating that AEWs are not necessary to maintain climatological tropical cyclone frequency even though tropical cyclones readily originate from these features. This further implies that seasonal Atlantic tropical cyclone frequency is uninfluenced by variability in AEWs, and that the value of AEW variability as a predictor of Atlantic tropical cyclones is limited to the weekly timescale. However in response to filtering AEWs, accumulated cyclone energy significantly increased by about 15% of the control simulation mean and the spatial pattern of track density shifted in association with changes in steering winds. This suggests the importance of AEWs in impacting tropical cyclone

  12. The relationship between African easterly waves and daily rainfall over West Africa: observations and regional climate simulations

    NASA Astrophysics Data System (ADS)

    Crétat, Julien; Vizy, Edward K.; Cook, Kerry H.

    2015-01-01

    The relationship between summer African easterly waves (AEWs) and daily rainfall is assessed in West Africa for 1998-2008 using various reanalyses, satellite-derived rainfall products, and a regional climate model (RCM) run at 90- and 30-km resolutions. 3-5 and 6-9 day AEWs are extracted by filtering daily 700 hPa meridional wind time series at 1°W and 11.5°N, and 1°W and 17.5°N, respectively. Both observed and simulated rainfall anomalies are of larger magnitude over West Africa during 3-5-d than 6-9-d AEWs. The RCM simulates larger rainfall rates in phase with the 3-5-d wave trough instead of ahead, unlike the observations, and overestimates the intensity and spatial coverage of rainfall associated with 6-9-d AEWs. The observed and simulated co-variability between 3-5-d (6-9-d) AEW activity and daily rainfall is strong (weak) and mostly located south (north) of 15°N. However, the RCM overestimates the spatial coverage of the AEW-rainfall relationship in the longitudinal (latitudinal) direction in the case of 3-5-d (6-9-d) AEWs. Observed and simulated daily intense rainfall events, extracted using a percentile threshold approach, are mostly located south of 15°N during summer. The observed relationship between their frequency of occurrence and active 3-5-d AEWs is maximal west of 8°E, while extends up to southern Chad in both RCM simulations. Their magnitude is also largely overestimated by the RCM, indicating an exaggerated coupling between the wave activity and the convection. Finally, observed and simulated 3-5-d AEWs establish the most favorable synoptic conditions for the development of intense rainfall events over West Africa.

  13. Holocene sea surface temperatures in the East African Coastal Current region and their relationship with North Atlantic climate

    NASA Astrophysics Data System (ADS)

    Kuhnert, Henning; Kuhlmann, Holger; Mohtadi, Mahyar; Pätzold, Jürgen

    2013-04-01

    The East African Coastal Current (EACC) is one of the western boundary currents of the Indian Ocean and represents the only pathway for southern water masses to enter the Arabian Sea. Today, sea surface temperatures (SST) in the western boundary currents region covary with those in large parts of the central tropical Indian Ocean. The latter play an important role in global climate by influencing the mean state of the North Atlantic Oscillation (NAO) and associated Atlantic SST anomalies (Hoerling et al., 2001). In the EACC region paleoclimate data are sparse and its Holocene temperature history is unexplored. We present data from a 5 m long sediment core retrieved off northern Tanzania where the EACC flows northward year-round. Proximity to the Pangani River mouth provides a steady sediment supply. We have reconstructed SST from Mg/Ca and stable oxygen isotope ratios (^18O) of the surface-dwelling planktonic foraminifera species Globigerinoides ruber (sensu stricto). Our record spans the time period from 9700 to 1400 years BP at an average temporal resolution of 40 years. The Holocene is characterized by a sequence of intervals representing cool, warm, cool, and intermediate SST, with boundaries at 7.8, 5.6, and 4.4 ka BP. SST anomalies relative to the series mean range from -0.6 to +0.75 ° C. This pattern strikingly resembles a Northwest Atlantic foraminiferal ^18O record (Cléroux et al., 2012), with warm Indian SST corresponding to low Atlantic foraminiferal ^18O (indicating low sea surface density). This matches the modern situation on the interdecadal time-scale, where a warm Indian Ocean leads to a shift of the NAO towards a positive mean state, which is accompanied by SST warming over much of the low- and mid-latitude western Atlantic and a displacement of the Gulf Stream path. We hypothesize that this mechanism also operates on millennial time-scales to explain the obvious similarities in the SST patterns observed in the Northwest Atlantic and western

  14. Elimination of mother-to-child transmission of HIV and syphilis: A dual approach in the African Region to improve quality of antenatal care and integrated disease control.

    PubMed

    Newman Owiredu, Morkor; Newman, Lori; Nzomo, Theresa; Conombo Kafando, Ghislaine; Sanni, Saliyou; Shaffer, Nathan; Bucagu, Maurice; Peeling, Rosanna; Mark, Jennifer; Diop Toure, Isseu

    2015-06-01

    The World Health Organization's (WHO) Strategic Framework for the Elimination of New HIV Infections among Children in Africa by 2015 identifies important synergies for the elimination of mother-to-child transmission of HIV and syphilis in terms of prevention interventions, implementation logistics and service delivery, monitoring and evaluation systems, and need for sustained political commitment. The WHO advocates the use of an integrated, rights-based dual approach with partnerships and collaboration to make the best use of available resources. Through a consultative approach, six countries in the African Region committed to dual elimination and developed and implemented action plans for this purpose. Where interest and commitment are high, this may also be possible and effective in other African countries. PMID:25963908

  15. The Paternal Landscape along the Bight of Benin – Testing Regional Representativeness of West-African Population Samples Using Y-Chromosomal Markers

    PubMed Central

    Larmuseau, Maarten H. D.; Vessi, Andrea; Jobling, Mark A.; Van Geystelen, Anneleen; Primativo, Giuseppina; Biondi, Gianfranco; Martínez-Labarga, Cristina; Ottoni, Claudio; Decorte, Ronny; Rickards, Olga

    2015-01-01

    Patterns of genetic variation in human populations across the African continent are still not well studied in comparison with Eurasia and America, despite the high genetic and cultural diversity among African populations. In population and forensic genetic studies a single sample is often used to represent a complete African region. In such a scenario, inappropriate sampling strategies and/or the use of local, isolated populations may bias interpretations and pose questions of representativeness at a macrogeographic-scale. The non-recombining region of the Y-chromosome (NRY) has great potential to reveal the regional representation of a sample due to its powerful phylogeographic information content. An area poorly characterized for Y-chromosomal data is the West-African region along the Bight of Benin, despite its important history in the trans-Atlantic slave trade and its large number of ethnic groups, languages and lifestyles. In this study, Y-chromosomal haplotypes from four Beninese populations were determined and a global meta-analysis with available Y-SNP and Y-STR data from populations along the Bight of Benin and surrounding areas was performed. A thorough methodology was developed allowing comparison of population samples using Y-chromosomal lineage data based on different Y-SNP panels and phylogenies. Geographic proximity turned out to be the best predictor of genetic affinity between populations along the Bight of Benin. Nevertheless, based on Y-chromosomal data from the literature two population samples differed strongly from others from the same or neighbouring areas and are not regionally representative within large-scale studies. Furthermore, the analysis of the HapMap sample YRI of a Yoruban population from South-western Nigeria based on Y-SNPs and Y-STR data showed for the first time its regional representativeness, a result which is important for standard population and forensic genetic applications using the YRI sample. Therefore, the uniquely

  16. The Paternal Landscape along the Bight of Benin - Testing Regional Representativeness of West-African Population Samples Using Y-Chromosomal Markers.

    PubMed

    Larmuseau, Maarten H D; Vessi, Andrea; Jobling, Mark A; Van Geystelen, Anneleen; Primativo, Giuseppina; Biondi, Gianfranco; Martínez-Labarga, Cristina; Ottoni, Claudio; Decorte, Ronny; Rickards, Olga

    2015-01-01

    Patterns of genetic variation in human populations across the African continent are still not well studied in comparison with Eurasia and America, despite the high genetic and cultural diversity among African populations. In population and forensic genetic studies a single sample is often used to represent a complete African region. In such a scenario, inappropriate sampling strategies and/or the use of local, isolated populations may bias interpretations and pose questions of representativeness at a macrogeographic-scale. The non-recombining region of the Y-chromosome (NRY) has great potential to reveal the regional representation of a sample due to its powerful phylogeographic information content. An area poorly characterized for Y-chromosomal data is the West-African region along the Bight of Benin, despite its important history in the trans-Atlantic slave trade and its large number of ethnic groups, languages and lifestyles. In this study, Y-chromosomal haplotypes from four Beninese populations were determined and a global meta-analysis with available Y-SNP and Y-STR data from populations along the Bight of Benin and surrounding areas was performed. A thorough methodology was developed allowing comparison of population samples using Y-chromosomal lineage data based on different Y-SNP panels and phylogenies. Geographic proximity turned out to be the best predictor of genetic affinity between populations along the Bight of Benin. Nevertheless, based on Y-chromosomal data from the literature two population samples differed strongly from others from the same or neighbouring areas and are not regionally representative within large-scale studies. Furthermore, the analysis of the HapMap sample YRI of a Yoruban population from South-western Nigeria based on Y-SNPs and Y-STR data showed for the first time its regional representativeness, a result which is important for standard population and forensic genetic applications using the YRI sample. Therefore, the uniquely

  17. Real-time tracking using trust-region methods.

    PubMed

    Liu, Tyng-Luh; Chen, Hwann-Tzong

    2004-03-01

    Optimization methods based on iterative schemes can be divided into two classes: line-search methods and trust-region methods. While line-search techniques are commonly found in various vision applications, not much attention is paid to trust-region ones. Motivated by the fact that line-search methods can be considered as special cases of trust-region methods, we propose to establish a trust-region framework for real-time tracking. Our approach is characterized by three key contributions. First, since a trust-region tracking system is more effective, it often yields better performances than the outcomes of other trackers that rely on iterative optimization to perform tracking, e.g., a line-search-based mean-shift tracker. Second, we have formulated a representation model that uses two coupled weighting schemes derived from the covariance ellipse to integrate an object's color probability distribution and edge density information. As a result, the system can address rotation and nonuniform scaling in a continuous space, rather than working on some presumably possible discrete values of rotation angle and scale. Third, the framework is very flexible in that a variety of distance functions can be adapted easily. Experimental results and comparative studies are provided to demonstrate the efficiency of the proposed method. PMID:15376885

  18. Method effects in survey and focus group findings: understanding smoking cessation in low-SES African American women.

    PubMed

    Manfredi, C; Lacey, L; Warnecke, R; Balch, G

    1997-12-01

    The same pool of African American women participated in a survey and in focus groups on motivation to quit smoking. Findings from the two studies were compared to explore potential method effects. Consistent with each method's basic purposes, the survey identified variation in study variables based on accepted theory and association patterns among such variables. The focus groups discovered themes and images salient to the participants and highlighted the situational contexts that gave meaning to smoking and smoking cessation. Survey method limitations included poor sensitivity to topic salience and contextual meanings and a deductive mode that channeled interpretation of results within the boundaries predefined by the study's theoretical framework. Focus group method limitations included an overfocus on the most dramatic and uncommon evidence and lack of systematic ways to identify explanations that may underlie the participants' overt expressions. Together, the multiple findings complemented and explained each other. PMID:9408791

  19. Using the ``blue spike'' to characterize biomass-burning sites during Southern African Regional Science Initiative (SAFARI) 2000

    NASA Astrophysics Data System (ADS)

    McCourt, M. L.; McMillan, W. W.; Ackerman, S.; Holz, R.; Revercomb, H. E.; Tobin, D.

    2004-10-01

    During several flights of the ER-2 while participating in the Southern African Regional Science Initiative (SAFARI 2000), the University of Wisconsin-Madison's Scanning High Resolution Interferometer Sounder (S-HIS) obtained spectra containing isolated fires within its field of view (FOV). These fire-laden FOVs contain a spectral feature caused by rotational hot band transitions of CO2 near 2400 cm-1. Because of its location on the blue side of the 4.3 μm band of CO2, this feature is commonly referred to as the "blue spike." Using this feature, we detected fires on four flights: 24 and 27 August and 6 and 7 September 2000. Fire locations are further verified by the ER-2 pilot's flight logs and elevated brightness temperatures in the thermal detectors of the MODIS Airborne Simulator (MAS) also on board the ER-2. Using line-by-line radiative transfer calculations (Genln2) with corrections for a fire's extreme high temperatures (HiTemp), we model S-HIS spectra for various scenes: background (cool surface and cool atmosphere), smoldering (warm surface and cool atmosphere), hot gas layer (cool surface and warm atmosphere), and fire (hot surface and hot atmosphere) cases. Using the controlled burn in the Timbavati Game Reserve on 7 September 2000 as a test case, we spectrally modeled the blue spike feature seen in the spectra obtained by S-HIS while the ER-2 flew over the fire. For this case, we found that ˜4.12 ± 0.05% of the FOV contained the hot gas layer while ˜0.23 ± 0.05% was actively burning. Originally viewed as a straightforward task of using the blue spike to characterize the fire temperature and size (fraction of S-HIS FOV), our analysis shows that numerous variables, including amount of carbon dioxide, amount of water vapor, and the temperature near the fire, play significant roles in the blue spike's shape and spectral position.

  20. World City/Regional City: Latinos and African-Americans in Chicago and St. Louis. JSRI Working Paper No. 46.

    ERIC Educational Resources Information Center

    Villanueva, Margaret; Erdman, Brian; Howlett, Larry

    This paper traces the effects of economic restructuring through comparative socioeconomic profiles of African American and Latinos in the Midwest, with a focus on Chicago and Kansas City. Globalization has been associated with deindustrialization, relocation of jobs to developing countries with cheaper labor, and expansion of the service sector. A…

  1. Numerical conformal mapping methods for exterior and doubly connected regions

    SciTech Connect

    DeLillo, T.K.; Pfaltzgraff, J.A.

    1996-12-31

    Methods are presented and analyzed for approximating the conformal map from the exterior of the disk to the exterior a smooth, simple closed curve and from an annulus to a bounded, doubly connected region with smooth boundaries. The methods are Newton-like methods for computing the boundary correspondences and conformal moduli similar to Fornberg`s method for the interior of the disk. We show that the linear systems are discretizations of the identity plus a compact operator and, hence, that the conjugate gradient method converges superlinearly.

  2. The VP2 variable region of African and German isolates of infectious bursal disease virus: comparison with very virulent, "classical" virulent, and attenuated tissue culture-adapted strains.

    PubMed

    Zierenberg, K; Nieper, H; van den Berg, T P; Ezeokoli, C D; Voss, M; Müller, H

    2000-01-01

    11 African and two German IBDV strains isolated in the mid '80s from field outbreaks in vaccinated and unvaccinated chicken flocks displayed features of very virulent (vv) IBDV strains. The sequence data of the VP2 variable region and phylogenetic analysis confirm that these strains can be grouped within vv IBDV strains which appeared at the same time on the three continents Africa, Asia, and Europe. Strain Cu-1wt, responsible for severe IBD outbreaks in Germany 13 years earlier, showed some relatedness to these strains, but also significant differences at the genomic level, even though this strain has also features of the vv IBDV strains. PMID:10664410

  3. Reduced-Median-Network Analysis of Complete Mitochondrial DNA Coding-Region Sequences for the Major African, Asian, and European Haplogroups

    PubMed Central

    Herrnstadt, Corinna; Elson, Joanna L.; Fahy, Eoin; Preston, Gwen; Turnbull, Douglass M.; Anderson, Christen; Ghosh, Soumitra S.; Olefsky, Jerrold M.; Beal, M. Flint; Davis, Robert E.; Howell, Neil

    2002-01-01

    The evolution of the human mitochondrial genome is characterized by the emergence of ethnically distinct lineages or haplogroups. Nine European, seven Asian (including Native American), and three African mitochondrial DNA (mtDNA) haplogroups have been identified previously on the basis of the presence or absence of a relatively small number of restriction-enzyme recognition sites or on the basis of nucleotide sequences of the D-loop region. We have used reduced-median-network approaches to analyze 560 complete European, Asian, and African mtDNA coding-region sequences from unrelated individuals to develop a more complete understanding of sequence diversity both within and between haplogroups. A total of 497 haplogroup-associated polymorphisms were identified, 323 (65%) of which were associated with one haplogroup and 174 (35%) of which were associated with two or more haplogroups. Approximately one-half of these polymorphisms are reported for the first time here. Our results confirm and substantially extend the phylogenetic relationships among mitochondrial genomes described elsewhere from the major human ethnic groups. Another important result is that there were numerous instances both of parallel mutations at the same site and of reversion (i.e., homoplasy). It is likely that homoplasy in the coding region will confound evolutionary analysis of small sequence sets. By a linkage-disequilibrium approach, additional evidence for the absence of human mtDNA recombination is presented here. PMID:11938495

  4. The second African Federation of Neurological Surgeons course in the East, Central, and Southern Africa region held in Dar es Salaam, Tanzania, January 2011.

    PubMed

    Kahamba, Joseph F; Assey, Anthony B; Dempsey, Robert J; Qureshi, Mahmood M; Härtl, Roger

    2013-01-01

    The second International African Federation of Neurological Surgeons course was organized on January 24 to 28, 2011, at the Seacliff Hotel and Muhimbili Orthopaedic Institute in Dar es Salaam, Tanzania. President Jakaya Mrisho Kikwete graced the official opening with high ranking government officials in attendance. The targeted participants were young neurosurgeons in the East, Central, and South African region. More than 80 surgeons, residents, and neurosurgical nurses came from Tanzania, Kenya, Uganda, Rwanda, Ethiopia, Zambia, and Zimbabwe. The objectives of the course were to teach and train young local surgeons in the essential-relevant for the region-and current techniques and management principles of brain and spinal diseases, acquire new skills through hands-on practical sessions, and share experiences. The course consisted of didactic sessions, practical aspects on spine internal fixation, cadaver dissections, and live microscopic and endoscopic surgery. Experienced faculty from different states of the United States, Spain, Turkey, India, Egypt, and Ethiopia facilitated the course. The objectives of the course were met with a favorable evaluation report. The collaboration and experience gained will be reinvested in organizing similar courses in the region. PMID:22120325

  5. On a method computing transient wave propagation in ionospheric regions

    NASA Technical Reports Server (NTRS)

    Gray, K. G.; Bowhill, S. A.

    1978-01-01

    A consequence of an exoatmospheric nuclear burst is an electromagnetic pulse (EMP) radiated from it. In a region far enough away from the burst, where nonlinear effects can be ignored, the EMP can be represented by a large-amplitude narrow-time-width plane-wave pulse. If the ionosphere intervenes the origin and destination of the EMP, frequency dispersion can cause significant changes in the original pulse upon reception. A method of computing these dispersive effects of transient wave propagation is summarized. The method described is different from the standard transform techniques and provides physical insight into the transient wave process. The method, although exact, can be used in approximating the early-time transient response of an ionospheric region by a simple integration with only explicit knowledge of the electron density, electron collision frequency, and electron gyrofrequency required. As an illustration of the method, it is applied to a simple example and contrasted with the corresponding transform solution.

  6. METHOD OF CONDUCTING A PERSON BETWEEN A SAFE REGION AND A DANGEROUS REGION

    DOEpatents

    Moulthrop, H.A.

    1957-11-12

    This invention relates to a method for conducting a person between a safe region and a dangerous or con taminated region so that he may work in the dangerous region without risk to himself or the hinderance of an attached tube, and without danger of contaminating the safe region. A safely suit in which a person is to work is connected by a thermoplastic tube, turned partially inside out, to a hole in the wall separating the dangerous region. The tube is sealed by pressure and separated into two parts at the seal, whereupon the person in the suit may move around freely in the dangerous area. When the person desires to exit the dangerous region, the parts of the tube are resealed, removing a portion of the tube at the seal, and the person leaves the hole whcre he entered, seals the tube to close the hole, and cuts his suit free from the tube. Bands of masking tape inside and outside of the tube at predetermined points simplify the pressure sealing of the tube at the desired points. This patent provides a simple, safe and economical method of freely working in a dangerous region.

  7. Diagnostic methods for African horsesickness virus using monoclonal antibodies to structural and non-structural proteins.

    PubMed

    Ranz, A I; Miguet, J G; Anaya, C; Venteo, A; Cortés, E; Vela, C; Sanz, A

    1992-11-01

    A panel of 32 hybridoma cell lines secreting monoclonal antibodies (MAbs) reactive with African horsesickness virus serotype 4 (AHSV-4) has been developed. Four of the MAbs recognized the major core antigen VP7, twenty recognized the outer capsid protein VP2 and eight reacted with the non-structural protein NS1. With the VP7-specific MAbs a rapid and sensitive double antibody sandwich immunoassay has been developed to detect viral antigen in infected Vero cells and in spleen tissue from AHSV-infected horses. The sensitivity of the assay is 10 ng viral antigen per 100 microliters. The NS1-specific MAbs allowed visualization by immunofluorescence of tubule-like structures in the cytoplasm of infected Vero cells. This can be very useful as a confirmatory diagnostic procedure. The antigenic map of the outer capsid VP2 protein with MAbs is also reported. PMID:1481354

  8. History and origin of the HIV-1 subtype C epidemic in South Africa and the greater southern African region

    PubMed Central

    Wilkinson, Eduan; Engelbrecht, Susan; de Oliveira, Tulio

    2015-01-01

    HIV has spread at an alarming rate in South Africa, making it the country with the highest number of HIV infections. Several studies have investigated the histories of HIV-1 subtype C epidemics but none have done so in the context of social and political transformation in southern Africa. There is a need to understand how these processes affects epidemics, as socio-political transformation is a common and on-going process in Africa. Here, we genotyped strains from the start of the epidemic and applied phylodynamic techniques to determine the history of the southern Africa and South African epidemic from longitudinal sampled data. The southern African epidemic’s estimated dates of origin was placed around 1960 (95% HPD 1956–64), while dynamic reconstruction revealed strong growth during the 1970s and 80s. The South African epidemic has a similar origin, caused by multiple introductions from neighbouring countries, and grew exponentially during the 1980s and 90s, coinciding with socio-political changes in South Africa. These findings provide an indication as to when the epidemic started and how it has grown, while the inclusion of sequence data from the start of the epidemic provided better estimates. The epidemic have stabilized in recent years with the expansion of antiretroviral therapy. PMID:26574165

  9. Mitochondrial DNA control region sequence variation suggests an independent origin of an {open_quotes}Asian-specific{close_quotes} 9-bp deletion in Africans

    SciTech Connect

    Soodyall, H.; Redd, A.; Vigilant

    1994-09-01

    The intergenic noncoding region between the cytochrome oxidase II and lysyl tRNA genes of human mitochondrial DNA (mtDNA) is associated with two tandemly arranged copies of a 9-bp sequence. A deletion of one of these repeats has been found at varying frequencies in populations of Asian descent, and is commonly referred to as an {open_quotes}Asian-specific{close_quotes} marker. We report here that the 9-bp deletion is also found at a frequency of 10.2% (66/649) in some indigenous African populations, with frequencies of 28.6% (20/70) in Pygmies, 26.6% (12/45) in Malawians and 15.4% (31/199) in southeastern Bantu-speaking populations. The deletion was not found in 123 Khoisan individuals nor in 209 western Bantu-speaking individuals, with the exception of 3 individuals from one group that was admixed with Pygmies. Sequence analysis of the two hypervariable segments of the mtDNA control region reveals that the types associated with the African 9-bp deletion are different from those found in Asian-derived populations with the deletion. Phylogenetic analysis separates the {open_quotes}African{close_quotes} and {open_quotes}Asian{close_quotes} 9-bp deletion types into two different clusters which are statistically supported. Mismatch distributions based on the number of differences between pairs of mtDNA types are consistent with this separation. These findings strongly support the view that the 9-bp deletion originated independently in Africa and in Asia.

  10. Comparative Transcriptomics of Eastern African Cichlid Fishes Shows Signs of Positive Selection and a Large Contribution of Untranslated Regions to Genetic Diversity

    PubMed Central

    Baldo, Laura; Santos, M.Emília; Salzburger, Walter

    2011-01-01

    The hundreds of endemic species of cichlid fishes in the East African Great Lakes Tanganyika, Malawi, and Victoria are a prime model system in evolutionary biology. With five genomes currently being sequenced, eastern African cichlids also represent a forthcoming genomic model for evolutionary studies of genotype-to-phenotype processes in adaptive radiations. Here we report the functional annotation and comparative analyses of transcriptome data sets for two eastern African cichlid species, Astatotilapia burtoni and Ophthalmotilapia ventralis, representatives of the modern haplochromines and ectodines, respectively. Nearly 647,000 expressed sequence tags were assembled in more than 46,000 contigs for each species using the 454 sequencing technology, largely expanding the current sequence data set publicly available for these cichlids. Total predicted coverage of their proteome diversity is approximately 50% for both species. Comparative qualitative and quantitative analyses show very similar transcriptome data for the two species in terms of both functional annotation and relative abundance of gene ontology terms expressed. Average genetic distance between species is 1.75% when all transcript types are considered including nonannotated sequences, 1.33% for annotated sequences only including untranslated regions, and decreases to nearly half, 0.95%, for coding sequences only, suggesting a large contribution of noncoding regions to their genetic diversity. Comparative analyses across the two species, tilapia and the outgroup medaka based on an overlapping data set of 1,216 genes (∼526 kb) demonstrate cichlid-specific signature of disruptive selection and provide a set of candidate genes that are putatively under positive selection. Overall, these data sets offer the genetic platform for future comparative analyses in light of the upcoming genomes for this taxonomic group. PMID:21617250

  11. A conserved African swine fever virus right variable region gene, l11L, is non-essential for growth in vitro and virulence in domestic swine.

    PubMed

    Kleiboeker, S B; Kutish, G F; Neilan, J G; Lu, Z; Zsak, L; Rock, D L

    1998-05-01

    The right variable region of the African swine fever virus (ASFV) genome is known to contain genes with functions involving virus virulence and host range in swine. A novel open reading frame, ORF l11L, which was absent in the non-pathogenic, cell culture-adapted European isolate BA71V, was identified in the pathogenic African isolate Malawi Lil-20/1. The location of l11L in the right variable region, together with its absence in BA71V, suggested that l11L may have a function in virus virulence and/or host range. Here, we show that the l11L gene is highly conserved among pathogenic African, European and Caribbean ASFV field isolates and that it exists either in a short form, encoding a protein of 77-78 amino acids (9.1 kDa) or in a longer form of 93-94 amino acids (11.1 kDa). The presence of two predicted membrane-spanning segments suggests that l11L is an integral membrane protein. RT-PCR analysis demonstrated that l11L mRNA is expressed late in the virus replication cycle. A recombinant l11L gene deletion mutant, deltal11L, was constructed from the ASFV isolate Malawi Lil-20/1 to examine gene function. Deletion of l11L did not affect virus replication in swine macrophage cell cultures nor virulence in domestic pigs, indicating that l11L is non-essential for growth in vitro and for virus virulence in domestic swine. PMID:9603334

  12. A review of regional mineral resource assessment methods.

    USGS Publications Warehouse

    Singer, D.A.; Mosier, D.L.

    1981-01-01

    Over 100 papers on regional mineral resource assessment of nonfuels are classified according to method(s) and form(s) of product in order to help identify possible methods for future assessments. Methods considered are: time-rate, crustal abundance, cumulative tonnage versus grade, simple subjective, complex subjective, Bayesian, frequency, trend, geometric probability, multiple regression, discriminant analysis, modified component, multivariate logistic, cluster analysis or pattern recognition, and simulation. Selection of an assessment method should be based on: 1) appropriateness of the product to the problem; 2) limitations in resources, such as information or time available for the assessment; 3) the level of uncertainty and acceptability of biases in the assessment; and 4) the need for verification of results and acceptance of the method. -Authors

  13. Regional deconvolution method for partial volume correction in brain PET

    NASA Astrophysics Data System (ADS)

    Rusinek, Henry; Tsui, Wai-Hon; de Leon, Mony J.

    2001-05-01

    Correction of PET images for partial volume effects (PVE) is of particular utility in studies of metabolism in brain aging and brain disorders. PVE is commonly corrected using voxel-by- voxel factors obtained from a high resolution brain mask (obtained from the coregistered MR scan), after convolution with the point spread function (PSF) of the imaging system. In a recently proposed regional deconvolution (RD) method, the observed regional activity is expressed as linear combinations of the true metabolic activity. The weights are obtained by integrating the PSF over the geometric extent of the brain regions. We have analyzed the accuracy of RD and two other PVE correction algorithms under a variety of conditions using simulated PET scans. Each of the brain regions was assigned a distribution of metabolic activity, with gray matter/white matter contrast representative of subjects in several age categories. Simulations were performed over a wide range of PET resolutions. The influence of PET/MR misregistration and heterogeneity of brain metabolism were also evaluated. Our results demonstrate the importance of correcting PET metabolic images for PVE. Without such correction, the regional brain activity values are contaminated with 30 - 40% errors. Under most conditions studied, the accuracy of RD and of the three- compartmental method were superior to the accuracy of the two- compartmental method. Our study provides the first demonstration of the feasibility of RD algorithm to provide accurate correction for a large number (n equals 109) of brain compartments. PVE correction methods appear to be promising tools in studies of metabolism in normal brain, brain aging, and brain disorders.

  14. A Polymorphism in the Regulatory Region of the CC-Chemokine Receptor 5 Gene Influences Perinatal Transmission of Human Immunodeficiency Virus Type 1 to African-American Infants

    PubMed Central

    Kostrikis, Leondios G.; Neumann, Avidan U.; Thomson, Bruce; Korber, Bette T.; McHardy, Paul; Karanicolas, Rose; Deutsch, Lisa; Huang, Yaoxing; Lew, Judy F.; McIntosh, Kenneth; Pollack, Henry; Borkowsky, William; Spiegel, Hans M. L.; Palumbo, Paul; Oleske, James; Bardeguez, Arlene; Luzuriaga, Katherine; Sullivan, John; Wolinsky, Steven M.; Koup, Richard A.; Ho, David D.; Moore, John P.

    1999-01-01

    There are natural mutations in the coding and noncoding regions of the human immunodeficiency virus type 1 (HIV-1) CC-chemokine coreceptor 5 (CCR5) and in the related CCR2 protein (the CCR2-64I mutation). Individuals homozygous for the CCR5-Δ32 allele, which prevents CCR5 expression, strongly resist HIV-1 infection. Several genetic polymorphisms have been identified within the CCR5 5′ regulatory region, some of which influence the rate of disease progression in adult AIDS study cohorts. We genotyped 1,442 infants (1,235 uninfected and 207 HIV-1 infected) for five CCR5 and CCR2 polymorphisms: CCR5-59353-T/C, CCR5-59356-C/T CCR5-59402-A/G, CCR5-Δ32, and CCR2-64I. The clinical significance of each genotype was assessed by measuring whether it influenced the rate of perinatal HIV-1 transmission among 667 AZT-untreated mother-infant pairs (554 uninfected and 113 HIV-1 infected). We found that the mutant CCR5-59356-T allele is relatively common in African-Americans (20.6% allele frequency among 552 infants) and rare in Caucasians and Hispanics (3.4 and 5.6% of 174 and 458 infants, respectively; P < 0.001). There were 38 infants homozygous for CCR5-59356-T, of whom 35 were African-Americans. Among the African-American infants in the AZT-untreated group, there was a highly significant increase in HIV-1 transmission to infants with two mutant CCR5-59356-T alleles (47.6% of 21), compared to those with no or one mutant allele (13.4 to 14.1% of 187 and 71, respectively; P < 0.001). The increased relative risk was 5.9 (95% confidence interval, 2.3 to 15.3; P < 0.001). The frequency of the CCR5-59356-T mutation varies between population groups in the United States, a low frequency occurring in Caucasians and a higher frequency occurring in African-Americans. Homozygosity for CCR5-59356-T is strongly associated with an increased rate of perinatal HIV-1 transmission. PMID:10559343

  15. Hydrologic regionalization using wavelet-based multiscale entropy method

    NASA Astrophysics Data System (ADS)

    Agarwal, A.; Maheswaran, R.; Sehgal, V.; Khosa, R.; Sivakumar, B.; Bernhofer, C.

    2016-07-01

    Catchment regionalization is an important step in estimating hydrologic parameters of ungaged basins. This paper proposes a multiscale entropy method using wavelet transform and k-means based hybrid approach for clustering of hydrologic catchments. Multi-resolution wavelet transform of a time series reveals structure, which is often obscured in streamflow records, by permitting gross and fine features of a signal to be separated. Wavelet-based Multiscale Entropy (WME) is a measure of randomness of the given time series at different timescales. In this study, streamflow records observed during 1951-2002 at 530 selected catchments throughout the United States are used to test the proposed regionalization framework. Further, based on the pattern of entropy across multiple scales, each cluster is given an entropy signature that provides an approximation of the entropy pattern of the streamflow data in each cluster. The tests for homogeneity reveals that the proposed approach works very well in regionalization.

  16. Understanding client satisfaction with HIV testing and counseling services: a mixed-methods study in four African countries.

    PubMed

    Osborn, Michelle; Obermeyer, Carla Makhlouf

    2016-06-01

    This paper uses mixed methods to provide comparative evidence across four African countries and identify those aspects of the testing experience that are the most important components of clients' satisfaction with services. We analyze data from three sources: a survey of clients at health facilities that included closed-ended questions about specific services and interactions around testing; responses to open-ended questions about testing experiences that were part of the same survey; and semi-structured interviews with a subsample of respondents who described their experience of testing and being diagnosed with HIV. High levels of reported satisfaction are found in both the survey and interview. The critical factors contributing to client satisfaction included: the three C's of testing-counseling, consent, and confidentiality, client-provider interactions, convenience of location, "good services", and reliable test results. PMID:26872848

  17. The West African monsoon: Contribution of the AMMA multidisciplinary programme to the study of a regional climate system.

    NASA Astrophysics Data System (ADS)

    Lebel, T.; Janicot, S.; Redelsperger, J. L.; Parker, D. J.; Thorncroft, C. D.

    2015-12-01

    The AMMA international project aims at improving our knowledge and understanding of the West African monsoon and its variability with an emphasis on daily-to-interannual timescales. AMMA is motivated by an interest in fundamental scientific issues and by the societal need for improved prediction of the WAM and its impacts on water resources, health and food security for West African nations. The West African monsoon (WAM) has a distinctive annual cycle in rainfall that remains a challenge to understand and predict. The location of peak rainfall, which resides in the Northern Hemisphere throughout the year, moves from the ocean to the land in boreal spring. Around the end of June there is a rapid shift in the location of peak rainfall between the coast and around 10°N where it remains until about the end of August. In September the peak rainfall returns equatorward at a relatively steady pace and is located over the ocean again by November. The fact that the peak rainfall migrates irregularly compared to the peak solar heating is due to the interactions that occur between the land, the atmosphere and the ocean. To gain a better understanding of this complex climate system, a large international research programme was launched in 2002, the biggest of its kind into environment and climate ever attempted in Africa. AMMA has involved a comprehensive field experiment bringing together ocean, land and atmospheric measurements, on timescales ranging from hourly and daily variability up to the changes in seasonal activity over a number of years. This presentation will focus on the description of the field programme and its accomplishments, and address some key questions that have been recently identified to form the core of AMMA-Phase 2.

  18. The West African monsoon: Contribution of the AMMA multidisciplinary programme to the study of a regional climate system.

    NASA Astrophysics Data System (ADS)

    Lebel, T.; Janicot, S.; Redelsperger, J. L.; Parker, D. J.; Thorncroft, C. D.

    2014-12-01

    The AMMA international project aims at improving our knowledge and understanding of the West African monsoon and its variability with an emphasis on daily-to-interannual timescales. AMMA is motivated by an interest in fundamental scientific issues and by the societal need for improved prediction of the WAM and its impacts on water resources, health and food security for West African nations. The West African monsoon (WAM) has a distinctive annual cycle in rainfall that remains a challenge to understand and predict. The location of peak rainfall, which resides in the Northern Hemisphere throughout the year, moves from the ocean to the land in boreal spring. Around the end of June there is a rapid shift in the location of peak rainfall between the coast and around 10°N where it remains until about the end of August. In September the peak rainfall returns equatorward at a relatively steady pace and is located over the ocean again by November. The fact that the peak rainfall migrates irregularly compared to the peak solar heating is due to the interactions that occur between the land, the atmosphere and the ocean. To gain a better understanding of this complex climate system, a large international research programme was launched in 2002, the biggest of its kind into environment and climate ever attempted in Africa. AMMA has involved a comprehensive field experiment bringing together ocean, land and atmospheric measurements, on timescales ranging from hourly and daily variability up to the changes in seasonal activity over a number of years. This presentation will focus on the description of the field programme and its accomplishments, and address some key questions that have been recently identified to form the core of AMMA-Phase 2.

  19. Flood regionalization: A hybrid geographic and predictor-variable region-of-influence regression method

    USGS Publications Warehouse

    Eng, K.; Milly, P.C.D.; Tasker, Gary D.

    2007-01-01

    To facilitate estimation of streamflow characteristics at an ungauged site, hydrologists often define a region of influence containing gauged sites hydrologically similar to the estimation site. This region can be defined either in geographic space or in the space of the variables that are used to predict streamflow (predictor variables). These approaches are complementary, and a combination of the two may be superior to either. Here we propose a hybrid region-of-influence (HRoI) regression method that combines the two approaches. The new method was applied with streamflow records from 1,091 gauges in the southeastern United States to estimate the 50-year peak flow (Q50). The HRoI approach yielded lower root-mean-square estimation errors and produced fewer extreme errors than either the predictor-variable or geographic region-of-influence approaches. It is concluded, for Q50 in the study region, that similarity with respect to the basin characteristics considered (area, slope, and annual precipitation) is important, but incomplete, and that the consideration of geographic proximity of stations provides a useful surrogate for characteristics that are not included in the analysis. ?? 2007 ASCE.

  20. African American Suicide

    MedlinePlus

    ... accounted for 83.8% of Caucasian elderly suicides. • Firearms were the predominant method of suicide among African ... per 100,000 annually. Source: Centers for Disease Control and Prevention. National Vital Statistics System. Mortality Data. ...

  1. A mixed methods study of health and social disparities among substance-using African American/Black men who have sex with men.

    PubMed

    Buttram, Mance E; Kurtz, Steven P

    2015-03-01

    African American/Black men who have sex with men (MSM) in the U.S. experience health and social disparities at greater rates than MSM of other races/ethnicities, including HIV infection and substance use. This mixed methods paper presents: 1) a quantitative examination of health and social disparities among a sample of substance-using African American/Black MSM (N=108), compared to Caucasian/White MSM (N=250), and 2) in-depth qualitative data from a subsample of African American/Black MSM (N=21) in order to contextualize the quantitative data. Findings indicate that compared to Caucasian/White MSM, African American/Black MSM experienced a wide range of health and social disparities including: substance use and dependence; buying, trading or selling sex; educational attainment; employment; homelessness; identifying as gay; HIV status; arrest history; social support; and satisfaction with one's living situation. Qualitative data suggests that structural interventions that address homophobia and the social environment would be likely to mitigate many of the health and social disparities experienced by African American/Black MSM. PMID:25960944

  2. The role of conflict minerals, artisanal mining, and informal trading networks in African intrastate and regional conflicts

    USGS Publications Warehouse

    Chirico, Peter G.; Malpeli, Katherine C.

    2014-01-01

    The relationship between natural resources and armed conflict gained public and political attention in the 1990s, when it became evident that the mining and trading of diamonds were connected with brutal rebellions in several African nations. Easily extracted resources such as alluvial diamonds and gold have been and continue to be exploited by rebel groups to fund their activities. Artisanal and small-scale miners operating under a quasi-legal status often mine these mineral deposits. While many African countries have legalized artisanal mining and established flow chains through which production is intended to travel, informal trading networks frequently emerge in which miners seek to evade taxes and fees by selling to unauthorized buyers. These networks have the potential to become international in scope, with actors operating in multiple countries. The lack of government control over the artisanal mining sector and the prominence of informal trade networks can have severe social, political, and economic consequences. In the past, mineral extraction fuelled violent civil wars in Sierra Leone, Liberia, and Angola, and it continues to do so today in several other countries. The significant influence of the informal network that surrounds artisanal mining is therefore an important security concern that can extend across borders and have far-reaching impacts.

  3. Using novel methods to examine stress among HIV-positive African American men who have sex with men and women.

    PubMed

    Glover, Dorie A; Williams, John K; Kisler, Kimberly A

    2013-06-01

    Biomarker composites (BCs) that objectively quantify psychosocial stress independent of self report could help to identify those at greatest risk for negative health outcomes and elucidate mechanisms of stress-related processes. Here, BCs are examined in the context of existing disease progression among HIV-positive African American men who have sex with men and women (MSMW) with high stress histories, including childhood sexual abuse. Participants (N = 99) collected 12-h overnight and morning urine samples for assay of cortisol and catecholamines (primary BC) and neopterin (an indicator of HIV disease progression). Data on cumulative psychosocial trauma history (severity, types, frequency, age at first incident), posttraumatic stress disorder (PTSD) symptoms, sexual risk behaviors, and a secondary BC consisting of routine health indicators (heart rate, blood pressure, body mass index, waist-to-hip ratio) were also collected. Lifetime trauma exposure was highly pervasive and significantly greater among those meeting a standard cutoff for PTSD caseness (24 %). After controlling for HIV factors (neopterin levels and years with disease), PTSD was a significant (p < .05) predictor of the primary, but not secondary BC. Those with PTSD also had significantly more sexual partners, sex without a condom, and exchange sex for money or drugs than those without PTSD. Specific trauma characteristics predicted PTSD severity and caseness independently and uniquely in regression models (p's < .05-.001). A primary BC appears sensitive to cumulative trauma burden and PTSD in HIV-positive African American MSMW, providing support for the use of BCs to quantify psychosocial stress and inform novel methods for examining mechanisms of stress influenced health behaviors and disease outcomes in at-risk populations. PMID:22538773

  4. Hard Bigotry, Low Expectations and Soft Support: Educating American African Boys in the United States with the Warrior Method

    ERIC Educational Resources Information Center

    Winbush, Raymond A.

    2013-01-01

    Educating American Africans boys has been a mixture of political rhetoric, educational pedagogy, and historical neglect. Although American African educators have produced several models for effectively educating Black boys, most of them are dismissed as too "radical" by White researchers who have little understanding or experience in…

  5. Teaching Them All: An Exploratory Mixed Methods Study of African American Students' Perceptions of Their Middle School's Culture

    ERIC Educational Resources Information Center

    Hankerson, Henry

    2009-01-01

    Research indicates school culture impacts student achievement. At Teach Them All Middle School (TTA), an achievement gap exists between African American and White students. The purpose of the current study was to examine the perceptions of African American students concerning the school culture at TTA. The research questions explored the…

  6. Mesoscale modeling and satellite observation of transport and mixing of smoke and dust particles over northern sub-Saharan African region

    NASA Astrophysics Data System (ADS)

    Yang, Zhifeng; Wang, Jun; Ichoku, Charles; Hyer, Edward; Zeng, Jing

    2013-11-01

    transport and vertical distribution of smoke and dust aerosols over the northern sub-Saharan African region are simulated in the Weather Research and Forecasting model with Chemistry (WRF-Chem), which uses hourly dynamic smoke emissions from the Fire Locating and Modeling of Burning Emissions database derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) fire products. Model performance for February 2008 is evaluated using MODIS true color images, aerosol optical depth (AOD) measurements from the Aerosol Robotic Network, MODIS AOD retrievals, and the Cloud-Aerosol Lidar data with Orthogonal Polarization (CALIOP) atmospheric backscattering and extinction products. Specification of smoke injection height of 650 m in WRF-Chem yields aerosol vertical profiles that are most consistent with CALIOP observations of aerosol layer height. Between the equator and 10°N, Saharan dust is often mixed with smoke near the surface, and their transport patterns manifest the interplay of trade winds, subtropical highs, precipitation associated with the Intertropical Convergence Zone, and the high mountains located near the Great Rift Valley region. At the 700 hPa level and above, smoke layers spread farther to the north and south and are often above the dust layers over the Sahel region. In some cases, transported smoke can also be mixed with dust over the Saharan region. Statistically, 5% of the CALIOP valid measurements in February 2007-2011 show aerosol layers either above or between the clouds, reinforcing the importance of the aerosol vertical distribution for quantifying aerosol impact on climate in the Sahel region.

  7. Noninvasive method of estimating human newborn regional cerebral blood flow

    SciTech Connect

    Younkin, D.P.; Reivich, M.; Jaggi, J.; Obrist, W.; Delivoria-Papadopoulos, M.

    1982-12-01

    A noninvasive method of estimating regional cerebral blood flow (rCBF) in premature and full-term babies has been developed. Based on a modification of the /sup 133/Xe inhalation rCBF technique, this method uses eight extracranial NaI scintillation detectors and an i.v. bolus injection of /sup 133/Xe (approximately 0.5 mCi/kg). Arterial xenon concentration was estimated with an external chest detector. Cerebral blood flow was measured in 15 healthy, neurologically normal premature infants. Using Obrist's method of two-compartment analysis, normal values were calculated for flow in both compartments, relative weight and fractional flow in the first compartment (gray matter), initial slope of gray matter blood flow, mean cerebral blood flow, and initial slope index of mean cerebral blood flow. The application of this technique to newborns, its relative advantages, and its potential uses are discussed.

  8. African Swine Fever in Uganda: Qualitative Evaluation of Three Surveillance Methods with Implications for Other Resource-Poor Settings

    PubMed Central

    Chenais, Erika; Sternberg-Lewerin, Susanna; Boqvist, Sofia; Emanuelson, Ulf; Aliro, Tonny; Tejler, Emma; Cocca, Giampaolo; Masembe, Charles; Ståhl, Karl

    2015-01-01

    Animal diseases impact negatively on households and on national economies. In low-income countries, this pertains especially to socio-economic effects on household level. To control animal diseases and mitigate their impact, it is necessary to understand the epidemiology of the disease in its local context. Such understanding, gained through disease surveillance, is often lacking in resource-poor settings. Alternative surveillance methods have been developed to overcome some of the hurdles obstructing surveillance. The objective of this study was to evaluate and qualitatively compare three methods for surveillance of acute infectious diseases using African swine fever in northern Uganda as an example. Report-driven outbreak investigations, participatory rural appraisals (PRAs), and a household survey using a smartphone application were evaluated. All three methods had good disease-detecting capacity, and each of them detected many more outbreaks compared to those reported to the World Organization for Animal Health during the same time period. Apparent mortality rates were similar for the three methods although highest for the report-driven outbreak investigations, followed by the PRAs, and then the household survey. The three methods have different characteristics and the method of choice will depend on the surveillance objective. The optimal situation might be achieved by a combination of the methods: outbreak detection via smartphone-based real-time surveillance, outbreak investigation for collection of biological samples, and a PRA for a better understanding of the epidemiology of the specific outbreak. All three methods require initial investments and continuous efforts. The sustainability of the surveillance system should, therefore, be carefully evaluated before making such investments. PMID:26664978

  9. WASCAL - West African Science Service Center on Climate Change and Adapted Land Use Regional Climate Simulations and Land-Atmosphere Simulations for West Africa at DKRZ and elsewhere

    NASA Astrophysics Data System (ADS)

    Hamann, Ilse; Arnault, Joel; Bliefernicht, Jan; Klein, Cornelia; Heinzeller, Dominikus; Kunstmann, Harald

    2014-05-01

    Changing climate and hydro-meteorological boundary conditions are among the most severe challenges to Africa in the 21st century. In particular West Africa faces an urgent need to develop effective adaptation and mitigation strategies to cope with negative impacts on humans and environment due to climate change, increased hydro-meteorological variability and land use changes. To help meet these challenges, the German Federal Ministry of Education and Research (BMBF) started an initiative with institutions in Germany and West African countries to establish together a West African Science Service Center on Climate Change and Adapted Land Use (WASCAL). This activity is accompanied by an establishment of trans-boundary observation networks, an interdisciplinary core research program and graduate research programs on climate change and related issues for strengthening the analytical capabilities of the Science Service Center. A key research activity of the WASCAL Competence Center is the provision of regional climate simulations in a fine spatio-temporal resolution for the core research sites of WASCAL for the present and the near future. The climate information is needed for subsequent local climate impact studies in agriculture, water resources and further socio-economic sectors. The simulation experiments are performed using regional climate models such as COSMO-CLM, RegCM and WRF and statistical techniques for a further refinement of the projections. The core research sites of WASCAL are located in the Sudanian Savannah belt in Northern Ghana, Southern Burkina Faso and Northern Benin. The climate in this region is semi-arid with six rainy months. Due to the strong population growth in West Africa, many areas of the Sudanian Savannah have been already converted to farmland since the majority of the people are living directly or indirectly from the income produced in agriculture. The simulation experiments of the Competence Center and the Core Research Program are

  10. Astronomy for African development

    NASA Astrophysics Data System (ADS)

    Govender, Kevindran

    2011-06-01

    In recent years there have been a number of efforts across Africa to develop the field of astronomy as well as to reap benefit from astronomy for African people. This presentation will discuss the case of the SALT (Southern African Large Telescope) Collateral Benefits Programme (SCBP) which was set up to ensure societal benefit from astronomy. With African society as the target, the SCBP has embarked on various projects from school level education to public understanding of science to socio-economic development, the latter mainly being felt in the rural communities surrounding the South African Astronomical Observatory (home to SALT). A development plan for ``Astronomy in Africa'' will also be discussed. This plan has been drawn up with input from all over Africa and themed ``Astronomy for Education''. The Africa case stands as a good example for the IYA cornerstone project ``Developing Astronomy Globally'' which focuses on developing regions.

  11. Methods for freshwater riverine input into regional ocean models

    NASA Astrophysics Data System (ADS)

    Herzfeld, M.

    2015-06-01

    The input of freshwater at the coast in regional models is a non-trivial exercise that has been studied extensively in the past. Several issues are of relevance; firstly, estuaries process water properties along their length, so that while freshwater may enter at the estuary head, it is no longer fresh at the mouth. Secondly, models create a numerical response that results in excessive upstream or offshore transport compared to what is typically observed. The cause of this has been traced to the lack of landward flow at the coast where freshwater is input. In this study we assess the performance of various methods of freshwater input in coarse resolution regional models where the estuary cannot be explicitly resolved, and present a formulation that attempts to account for upstream flow in the salt wedge and in-estuary mixing that elevates salinity at the mouth.

  12. An image fusion method based region segmentation and complex wavelets

    NASA Astrophysics Data System (ADS)

    Zhang, Junju; Yuan, Yihui; Chang, Benkang; Han, Yiyong; Liu, Lei; Qiu, Yafeng

    2009-07-01

    A fusion algorithm for infrared and visible light images based on region segmentation and the dual-tree complex wavelet transform. Before image segmentation, morphological top-hat filtering is firstly performed on the IR image and visual images respectively and the details of the luminous area are eliminated. Morphological bottom-hat filtering is then performed on the two kinds of images respectively and the details of the dark area are eliminated. Make the top-hat filtered image subtract the bottom-hat filtered image and obtain the enhanced images. Then the threshold method is used to segment the enhanced images. After image segmentation, the DTCWT coefficients from different regions are merged separately. Finally the fused image is obtained by performing inverse DTCWT. The evaluation results show the validity of the presented algorithm.

  13. Evaluating regional vulnerability to climate change: purposes and methods

    SciTech Connect

    Malone, Elizabeth L.; Engle, Nathan L.

    2011-03-15

    As the emphasis in climate change research, international negotiations, and developing-country activities has shifted from mitigation to adaptation, vulnerability has emerged as a bridge between impacts on one side and the need for adaptive changes on the other. Still, the term vulnerability remains abstract, its meaning changing with the scale, focus, and purpose of each assessment. Understanding regional vulnerability has advanced over the past several decades, with studies using a combination of indicators, case studies and analogues, stakeholder-driven processes, and scenario-building methodologies. As regions become increasingly relevant scales of inquiry for bridging the aggregate and local, for every analysis, it is perhaps most appropriate to ask three “what” questions: “What/who is vulnerable?,” “What is vulnerability?,” and “Vulnerable to what?” The answers to these questions will yield different definitions of vulnerability as well as different methods for assessing it.

  14. Using solar wind data to predict daily GPS scintillation occurrence in the African and Asian low-latitude regions

    NASA Astrophysics Data System (ADS)

    Carter, B. A.; Retterer, J. M.; Yizengaw, E.; Wiens, K.; Wing, S.; Groves, K.; Caton, R.; Bridgwood, C.; Francis, M.; Terkildsen, M.; Norman, R.; Zhang, K.

    2014-12-01

    The feasibility of predicting the daily occurrence of Global Positioning System scintillation events using forecasts of common geophysical indices to drive a physics-based model of the system is demonstrated over a 5 month period for the African and Asian longitude sectors. The output from the Wing Kp model, which uses solar wind data to predict the geomagnetic activity level up to 4 h in advance, was used to drive the National Center for Atmospheric Research thermosphere/ionosphere model, from which the strength of the Rayleigh-Taylor instability growth rate was calculated to determine the likelihood of scintillation. It is found that the physics-based model demonstrates superior skill to an empirical scintillation model (Wideband Model (WBMOD)) in forecasting scintillation suppression events during seasons when scintillation is common. However, neither of the models driven in this way possess the ability to forecast isolated scintillation events during transitional and off-peak seasons.

  15. The Thermal History of the East African Rift Lakes Region Since the Last Glacial Maximum Using TEX86 Paleothermometry

    NASA Astrophysics Data System (ADS)

    Berke, M. A.; Johnson, T. C.; Werne, J. P.; Schouten, S.; Sinninghe Damsté, J. S.

    2008-12-01

    We present preliminary results from a study using the TEX86 temperature proxy from sediments of East African Rift Lakes (including Lakes Turkana, Albert, and Malawi) to reconstruct the thermal history of tropical Africa for the last ~ 20,000 years at a subcentennial to multicentennial resolution. The TEX86 proxy, based on tetraether membrane lipids produced by lacustrine Crenarchaeota, has been shown to be successful at recording lake surface temperatures of some large lakes, including Lakes Malawi and Tanganyika, while providing unreasonable surface temperatures for lakes that receive a large input of soil material. The East African Rift Lakes are climatically sensitive, with the majority of water loss due to evaporation rather than outflow. Thus, they are useful for paleoclimate studies, being sensitive to even small changes in aridity. Temperature records from the northern and central basins of Lake Malawi agree well and fall within modern surface lake temperatures. A 2.5°C cooling is evident during the Younger Dryas in the northern basin record, with no response seen in the central basin. We are currently investigating mechanisms to explain why both records show a gradual cooling of 3°C during the late Holocene. Lake Albert shows an intriguing two-step cooling during the Younger Dryas, reaching temperatures 2.5°C lower than temperatures preceding or following this interval. The temperature record of Lake Turkana shows an interesting ~ 500 year cyclicity of low temperatures punctuated by abrupt warming events. Lakes Turkana and Albert show TEX86 paleotemperatures considerably lower (8°C cooler in Lake Albert and ~ 4°C cooler in Lake Turkana) than modern surface water temperatures. Although these records appear to fall in the range of temporal variability, these temperature discrepancies may indicate varying Crenarcheotal populations between lakes or other influencing factors.

  16. Tomography and Methods of Travel-Time Calculation for Regional Seismic Location

    SciTech Connect

    Myers, S; Ballard, S; Rowe, C; Wagoner, G; Antolik, M; Phillips, S; Ramirez, A; Begnaud, M; Pasyanos, M E; Dodge, D A; Flanagan, M P; Hutchenson, K; Barker, G; Dwyer, J; Russell, D

    2007-07-02

    We are developing a laterally variable velocity model of the crust and upper mantle across Eurasia and North Africa to reduce event location error by improving regional travel-time prediction accuracy. The model includes both P and S velocities and we describe methods to compute travel-times for Pn, Sn, Pg, and Lg phases. For crustal phases Pg and Lg we assume that the waves travel laterally at mid-crustal depths, with added ray segments from the event and station to the mid crustal layer. Our work on Pn and Sn travel-times extends the methods described by Zhao and Xie (1993). With consideration for a continent scale model and application to seismic location, we extend the model parameterization of Zhao and Xie (1993) by allowing the upper-mantle velocity gradient to vary laterally. This extension is needed to accommodate the large variation in gradient that is known to exist across Eurasia and North African. Further, we extend the linear travel-time calculation method to mantle-depth events, which is needed for seismic locators that test many epicenters and depths. Using these methods, regional travel times are computed on-the-fly from the velocity model in milliseconds, forming the basis of a flexible travel time facility that may be implemented in an interactive locator. We use a tomographic technique to improve upon a laterally variable starting velocity model that is based on Lawrence Livermore and Los Alamos National Laboratory model compilation efforts. Our tomographic data set consists of approximately 50 million regional arrivals from events that meet the ground truth (GT) criteria of Bondar et al. (2004) and other non-seismic constraints. Each datum is tested to meet strict quality control standards that include comparison with established distance-dependent travel-time residual populations relative to the IASPIE91 model. In addition to bulletin measurements, nearly 50 thousand arrival measurements were made at the national laboratories. The tomographic

  17. Effective method for detecting regions of given colors and the features of the region surfaces

    NASA Astrophysics Data System (ADS)

    Gong, Yihong; Zhang, HongJiang

    1994-03-01

    Color can be used as a very important cue for image recognition. In industrial and commercial areas, color is widely used as a trademark or identifying feature in objects, such as packaged goods, advertising signs, etc. In image database systems, one may retrieve an image of interest by specifying prominent colors and their locations in the image (image retrieval by contents). These facts enable us to detect or identify a target object using colors. However, this task depends mainly on how effectively we can identify a color and detect regions of the given color under possibly non-uniform illumination conditions such as shade, highlight, and strong contrast. In this paper, we present an effective method to detect regions matching given colors, along with the features of the region surfaces. We adopt the HVC color coordinates in the method because of its ability of completely separating the luminant and chromatic components of colors. Three basis functions functionally serving as the low-pass, high-pass, and band-pass filters, respectively, are introduced.

  18. African American Preschoolers' Language, Emergent Literacy Skills, and Use of African American English: A Complex Relation

    ERIC Educational Resources Information Center

    Connor, Carol McDonald; Craig, Holly K.

    2006-01-01

    Purpose: This study examined the relation between African American preschoolers' use of African American English (AAE) and their language and emergent literacy skills in an effort to better understand the perplexing and persistent difficulties many African American children experience learning to read proficiently. Method: African American…

  19. Improved semen collection method for wild felids: urethral catheterization yields high sperm quality in African lions (Panthera leo).

    PubMed

    Lueders, I; Luther, I; Scheepers, G; van der Horst, G

    2012-08-01

    For wild and domestic felids, electroejaculation (EE) is the most common semen collection method. However, the equipment is expensive, there is a risk of urine contamination and animals usually show strong muscular contraction despite general anesthesia. Accordingly, we tested the feasibility of a different approach using urethral catheterization (UC) in seven African lions, previously described for domestic cats only. After general anesthesia with the α2-agonist medetomidine (which also stimulates semen release into the urethra) and ketamine, a transrectal ultrasound was performed to locate the prostate. A commercial dog urinary catheter (2.6 or 3.3 mm in diameter) was advanced approximately 30 cm into the urethra to allow semen collection into the lumen of the catheter by capillary forces. After retraction, sperm volumes between of 422.86 ± 296.07 μl yielded motility of 88.83 ± 13.27% (mean ± SD) with a mean sperm concentration of 1.94 × 10(9)/ml. Here we describe a simple, field friendly and effective method to attain highly concentrated semen samples with excellent motility in lions and potentially other wild felid species as an alternative to electroejaculation. PMID:22538007

  20. High-resolution regional modeling of summertime transport and impact of African dust over the Red Sea and Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Kalenderski, Stoitchko; Stenchikov, Georgiy

    2016-06-01

    Severe dust outbreaks and high dust loading over Eastern Africa and the Red Sea are frequently detected in the summer season. Observations suggest that small-scale dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand these processes, we present here the first high-resolution modeling study of a dust outbreak in June 2012 developed over East Africa, the Red Sea, and the Arabian Peninsula. Using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) component, we identified several dust generating dynamical processes that range from convective to synoptic scales, including synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea, most of the dust transport occurs above 2 km height, whereas across the central and southern parts of the sea; dust is mostly transported below 2 km height. Dust is the dominant contributor (87%) to the aerosol optical depth, producing a domain average cooling effect of -12.1 W m-2 at the surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. Both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. Model results compare well with available ground-based and satellite observations but generally underestimate the observed maximum values of aerosol optical depth. The satellite-retrieved mean optical depth at some locations is underestimated by a factor of 2. A sensitive experiment suggests that these large local differences may result from poor characterization of dust emissions in some areas of the modeled domain. In this case study we successfully simulate the major fine-scale dust generating dynamical processes, explicitly resolving convection and haboob formation. The future

  1. DIETARY ASSESSMENT IN AFRICAN AMERICANS: METHODS USED IN THE JACKSON HEART STUDY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objectives: The dietary assessment methods used in the Jackson Heart Study (JHS) with the entire cohort and a subset of the cohort who participated in a diet and physical activity substudy (DPASS) are reported. These methods were employed to validate culturally explicit data collection instruments d...

  2. Sensitivity of Mesoscale Modeling of Smoke Direct Radiative Effect to the Emission Inventory: a Case Study in Northern Sub-Saharan African Region

    NASA Technical Reports Server (NTRS)

    Zhang, Feng; Wang, Jun; Ichoku, Charles; Hyer, Edward J.; Yang, Zhifeng; Ge, Cui; Su, Shenjian; Zhang, Xiaoyang; Kondragunta, Shobha; Kaiser, Johannes W.; Wiedinmyer, Christine; da Silva, Arlindo

    2014-01-01

    An ensemble approach is used to examine the sensitivity of smoke loading and smoke direct radiative effect in the atmosphere to uncertainties in smoke emission estimates. Seven different fire emission inventories are applied independently to WRF-Chem model (v3.5) with the same model configuration (excluding dust and other emission sources) over the northern sub-Saharan African (NSSA) biomass-burning region. Results for November and February 2010 are analyzed, respectively representing the start and end of the biomass burning season in the study region. For February 2010, estimates of total smoke emission vary by a factor of 12, but only differences by factors of 7 or less are found in the simulated regional (15degW-42degE, 13degS-17degN) and monthly averages of column PM(sub 2.5) loading, surface PM(sub 2.5) concentration, aerosol optical depth (AOD), smoke radiative forcing at the top-of-atmosphere and at the surface, and air temperature at 2 m and at 700 hPa. The smaller differences in these simulated variables may reflect the atmospheric diffusion and deposition effects to dampen the large difference in smoke emissions that are highly concentrated in areas much smaller than the regional domain of the study. Indeed, at the local scale, large differences (up to a factor of 33) persist in simulated smoke-related variables and radiative effects including semi-direct effect. Similar results are also found for November 2010, despite differences in meteorology and fire activity. Hence, biomass burning emission uncertainties have a large influence on the reliability of model simulations of atmospheric aerosol loading, transport, and radiative impacts, and this influence is largest at local and hourly-to-daily scales. Accurate quantification of smoke effects on regional climate and air quality requires further reduction of emission uncertainties, particularly for regions of high fire concentrations such as NSSA.

  3. Current status and future prospects of epidemiology and public health training and research in the WHO African region

    PubMed Central

    Nachega, Jean B; Uthman, Olalekan A; Ho, Yuh-Shan; Lo, Melanie; Anude, Chuka; Kayembe, Patrick; Wabwire-Mangen, Fred; Gomo, Exnevia; Sow, Papa Salif; Obike, Ude; Kusiaku, Theophile; Mills, Edward J; Mayosi, Bongani M; IJsselmuiden, Carel

    2012-01-01

    Background To date little has been published about epidemiology and public health capacity (training, research, funding, human resources) in WHO/AFRO to help guide future planning by various stakeholders. Methods A bibliometric analysis was performed to identify published epidemiological research. Information about epidemiology and public health training, current research and challenges was collected from key informants using a standardized questionnaire. Results From 1991 to 2010, epidemiology and public health research output in the WHO/AFRO region increased from 172 to 1086 peer-reviewed articles per annum [annual percentage change (APC) = 10.1%, P for trend < 0.001]. The most common topics were HIV/AIDS (11.3%), malaria (8.6%) and tuberculosis (7.1%). Similarly, numbers of first authors (APC = 7.3%, P for trend < 0.001), corresponding authors (APC = 8.4%, P for trend < 0.001) and last authors (APC = 8.5%, P for trend < 0.001) from Africa increased during the same period. However, an overwhelming majority of respondents (>90%) reported that this increase is only rarely linked to regional post-graduate training programmes in epidemiology. South Africa leads in publications (1978/8835, 22.4%), followed by Kenya (851/8835, 9.6%), Nigeria (758/8835, 8.6%), Tanzania (549/8835, 6.2%) and Uganda (428/8835, 4.8%) (P < 0.001, each vs South Africa). Independent predictors of relevant research productivity were ‘in-country numbers of epidemiology or public health programmes’ [incidence rate ratio (IRR) = 3.41; 95% confidence interval (CI) 1.90–6.11; P = 0.03] and ‘number of HIV/AIDS patients’ (IRR = 1.30; 95% CI 1.02–1.66; P < 0.001). Conclusions Since 1991, there has been increasing epidemiological research productivity in WHO/AFRO that is associated with the number of epidemiology programmes and burden of HIV/AIDS cases. More capacity building and training initiatives in epidemiology are required to promote research and address the public health challenges

  4. Patterns of GPS-TEC variation over low-latitude regions (African sector) during the deep solar minimum (2008 to 2009) and solar maximum (2012 to 2013) phases

    NASA Astrophysics Data System (ADS)

    Tariku, Yekoye Asmare

    2015-03-01

    Due to the unique geometry of the geomagnetic fields near the magnetic equator and low-latitude regions, the satellite communication system in the African sector is strongly influenced by the effects resulting from the accumulation of electrons in their ionosphere. Hence, this paper investigates the patterns of the vertical total electron content (VTEC) variation detected by the Global Positioning System (GPS) over low-latitude regions during a very low (2008 to 2009) and a high solar activity (2012 to 2013) phases. The study has been carried out by considering eight ground-based dual-frequency GPS receivers installed recently at different regions in Ethiopia. In this work, the diurnal, monthly, and seasonal variations in the GPS-VTEC have been analyzed. It has been found that the diurnal variability of VTEC has shown minimum values at around 0300 UT (0600 local time (LT)) and maximum values nearly between 1000 and 1300 UT (1300 and 1600 LT) during both the low and the high activity phases. Moreover, the maximum and minimum of monthly mean hourly VTEC values are observed in October and July, respectively, during both the low (2009) and the high solar activity (2012) phases. It has also been depicted that seasonal mean hourly VTEC values have shown maxima and minima in the March equinox and the June solstice, respectively, during both the low and the high solar activity phases.

  5. Methods for Identifying Neisseria meningitidis Carriers: A Multi-Center Study in the African Meningitis Belt

    PubMed Central

    Basta, Nicole E.; Stuart, James M.; Nascimento, Maria C.; Manigart, Olivier; Trotter, Caroline; Hassan-King, Musa; Chandramohan, Daniel; Sow, Samba O.; Berthe, Abdoulaye; Bedru, Ahmed; Tekletsion, Yenenesh K.; Collard, Jean-Marc; Jusot, Jean-François; Diallo, Aldiouma; Basséne, Hubert; Daugla, Doumagoum M.; Gamougam, Khadidja; Hodgson, Abraham; Forgor, Abudulai A.; Omotara, Babatunji A.; Gadzama, Galadima B.; Watkins, Eleanor R.; Rebbetts, Lisa S.; Diallo, Kanny; Weiss, Noel S.; Halloran, M. Elizabeth; Maiden, Martin C. J.; Greenwood, Brian

    2013-01-01

    Objective Detection of meningococcal carriers is key to understanding the epidemiology of Neisseria meningitidis, yet no gold standard has been established. Here, we directly compare two methods for collecting pharyngeal swabs to identify meningococcal carriers. Methods We conducted cross-sectional surveys of schoolchildren at multiple sites in Africa to compare swabbing the posterior pharynx behind the uvula (U) to swabbing the posterior pharynx behind the uvula plus one tonsil (T). Swabs were cultured immediately and analyzed using molecular methods. Results One thousand and six paired swab samples collected from schoolchildren in four countries were analyzed. Prevalence of meningococcal carriage was 6.9% (95% CI: 5.4-8.6%) based on the results from both swabs, but the observed prevalence was lower based on one swab type alone. Prevalence based on the T swab or the U swab alone was similar (5.2% (95% CI: 3.8-6.7%) versus 4.9% (95% CI: 3.6-6.4%) respectively (p=0.6)). The concordance between the two methods was 96.3% and the kappa was 0.61 (95% CI: 0.50-0.73), indicating good agreement. Conclusions These two commonly used methods for collecting pharyngeal swabs provide consistent estimates of the prevalence of carriage, but both methods misclassified carriers to some degree, leading to underestimates of the prevalence. PMID:24194921

  6. Use of handheld X-ray fluorescence as a non-invasive method to distinguish between Asian and African elephant tusks

    PubMed Central

    Buddhachat, Kittisak; Thitaram, Chatchote; Brown, Janine L.; Klinhom, Sarisa; Bansiddhi, Pakkanut; Penchart, Kitichaya; Ouitavon, Kanita; Sriaksorn, Khanittha; Pa-in, Chalermpol; Kanchanasaka, Budsabong; Somgird, Chaleamchat; Nganvongpanit, Korakot

    2016-01-01

    We describe the use of handheld X-ray fluorescence, for elephant tusk species identification. Asian (n = 72) and African (n = 85) elephant tusks were scanned and we utilized the species differences in elemental composition to develop a functional model differentiating between species with high precision. Spatially, the majority of measured elements (n = 26) exhibited a homogeneous distribution in cross-section, but a more heterologous pattern in the longitudinal direction. Twenty-one of twenty four elements differed between Asian and African samples. Data were subjected to hierarchical cluster analysis followed by a stepwise discriminant analysis, which identified elements for the functional equation. The best equation consisted of ratios of Si, S, Cl, Ti, Mn, Ag, Sb and W, with Zr as the denominator. Next, Bayesian binary regression model analysis was conducted to predict the probability that a tusk would be of African origin. A cut-off value was established to improve discrimination. This Bayesian hybrid classification model was then validated by scanning an additional 30 Asian and 41 African tusks, which showed high accuracy (94%) and precision (95%) rates. We conclude that handheld XRF is an accurate, non-invasive method to discriminate origin of elephant tusks provides rapid results applicable to use in the field. PMID:27097717

  7. Use of handheld X-ray fluorescence as a non-invasive method to distinguish between Asian and African elephant tusks.

    PubMed

    Buddhachat, Kittisak; Thitaram, Chatchote; Brown, Janine L; Klinhom, Sarisa; Bansiddhi, Pakkanut; Penchart, Kitichaya; Ouitavon, Kanita; Sriaksorn, Khanittha; Pa-in, Chalermpol; Kanchanasaka, Budsabong; Somgird, Chaleamchat; Nganvongpanit, Korakot

    2016-01-01

    We describe the use of handheld X-ray fluorescence, for elephant tusk species identification. Asian (n = 72) and African (n = 85) elephant tusks were scanned and we utilized the species differences in elemental composition to develop a functional model differentiating between species with high precision. Spatially, the majority of measured elements (n = 26) exhibited a homogeneous distribution in cross-section, but a more heterologous pattern in the longitudinal direction. Twenty-one of twenty four elements differed between Asian and African samples. Data were subjected to hierarchical cluster analysis followed by a stepwise discriminant analysis, which identified elements for the functional equation. The best equation consisted of ratios of Si, S, Cl, Ti, Mn, Ag, Sb and W, with Zr as the denominator. Next, Bayesian binary regression model analysis was conducted to predict the probability that a tusk would be of African origin. A cut-off value was established to improve discrimination. This Bayesian hybrid classification model was then validated by scanning an additional 30 Asian and 41 African tusks, which showed high accuracy (94%) and precision (95%) rates. We conclude that handheld XRF is an accurate, non-invasive method to discriminate origin of elephant tusks provides rapid results applicable to use in the field. PMID:27097717

  8. Late Pan-African granite emplacement during regional deformation, evidence from magnetic fabric and structural studies in the Hammamat-Atalla area, Central Eastern Desert of Egypt

    NASA Astrophysics Data System (ADS)

    Greiling, R. O.; de Wall, H.; Sadek, M. F.; Dietl, C.

    2014-11-01

    Field investigations, microstructural observations, and magnetic fabric analyses revealed a polyphase, late Pan-African deformational evolution in the Um Sheqila-Um Had (595 Ma) composite pluton and in the Hammamat and Atalla areas of the Central Eastern Desert of Egypt in Ediacaran times. Major stages are early shortening (NNW-SSE), subsequent strike-slip (NW-SE shear zones), and late shortening (NW-SE). Strain studies on pebbles and xenoliths together with AMS data show a predominance of shallow, NW-SE trending X axes or magnetic lineations, associated with steep, NW-SE striking magnetic foliations. Magnetic fabrics and microstructures indicate a tectonic fabric in the Um Sheqila-Um Had granitoid plutons, which is dominated by steep NW-SE striking foliations and shallow NW-SE trending lineations, similar to those in the high-angle Atalla Shear Zone. There is a change of lineation directions from ESE-WNW at Um Sheqila (oldest) to NW-SE to Um Had II (youngest). This pattern may indicate an influence of strike-slip and is also consistent with NE-SW compression. This holds also true for the asymmetry of the contact aureole, which is extended towards NW, parallel with the trend of the magnetic lineation. The character and orientation of the deformation pattern in the Um Sheqila-Um Had plutons and the Atalla Shear Zone is thus similar to the pattern of the late shortening phase. The intrusion of the Um Sheqila-Um Had granitoid rocks, therefore, took place before the late shortening stage, but postdates early deformation, which, according to published data, was associated with lithospheric thinning in the Central Eastern Desert. Therefore, these Pan-African plutons do not represent the earliest post-deformational intrusions but a late stage of syn-deformational magmatic activity. At a regional scale, this deformation with steep foliations and shallow lineations may also be related with lateral escape tectonics. The pluton emplacement, the importance of transcurrent

  9. Using apatite (U-Th)/He thermochronometry to resolve regional unroofing patterns across the interior of the southern African Plateau and implications for mantle dynamics

    NASA Astrophysics Data System (ADS)

    Stanley, J. R.; Flowers, R. M.

    2011-12-01

    plateau interior since Cretaceous time. The only published AHe data for southern Africa (Flowers and Schoene 2009) comes from across the Great Escarpment in the Barberton region of South Africa and Swaziland. Those results are also Cretaceous with dates clustering ~100 Ma. Our new data, when combined with the previously published results, complete a large scale, ~900 km long, transect of AHe data from the coastal plain across the Great Escarpment well into the interior of the plateau. This full dataset suggests an intriguing spatial variability in dates, and shows the promise of using AHe data to decipher unroofing patterns across the continent to help better understand the mantle processes responsible for the rise of the southern African Plateau.

  10. African bees to control African elephants

    NASA Astrophysics Data System (ADS)

    Vollrath, Fritz; Douglas-Hamilton, Iain

    2002-11-01

    Numbers of elephants have declined in Africa and Asia over the past 30 years while numbers of humans have increased, both substantially. Friction between these two keystone species is reaching levels which are worryingly high from an ecological as well as a political viewpoint. Ways and means must be found to keep the two apart, at least in areas sensitive to each species' survival. The aggressive African bee might be one such method. Here we demonstrate that African bees deter elephants from damaging the vegetation and trees which house their hives. We argue that bees can be employed profitably to protect not only selected trees, but also selected areas, from elephant damage.

  11. Newton's method with a model trust-region modification

    SciTech Connect

    Sorensen, D C

    1980-09-01

    A modified Newton method for unconstrained minimization is presented and analyzed. The modification is based upon the model trust region approach. This report contains a thorough analysis of the locally constrained quadratic minimizations that arise as subproblems in the modified Newton iteration. Several promising alternatives are presented for solving these subproblems in ways that overcome certain theoretical difficulties exposed by this analysis. Very strong convergence results are presented concerning the minimization algorithm. In particular, the explicit use of second-order information is justified by demonstrating that the iterates converge to a point that satisfies the second-order necessary conditions for minimization. With the exception of very pathological cases this convergence occurs whenever the algorithm is applied to problems with continuous second partial derivatives.

  12. Structural analysis of the Itapucumí Group in the Vallemí region, northern Paraguay: Evidence of a new Brasiliano/Pan-African mobile belt

    NASA Astrophysics Data System (ADS)

    Campanha, Ginaldo Ademar da Cruz; Warren, Lucas; Boggiani, Paulo César; Grohmann, Carlos Henrique; Cáceres, Alberto Arias

    The Neoproterozoic (Ediacaran) Itapucumí Group in northern Paraguay is composed of carbonate and siliciclastic rocks, including ooid grainstones, marls, shales and sandstones, containing Cloudina fossils in the eastern region. It is almost undeformed over the Rio Apa Cratonic Block but shows a strong deformational pattern at its western edge. A detailed structural analysis of the Itapucumí Group was conducted in the Vallemí Mine, along with a regional survey in other outcrops downstream in the Paraguay River and in the San Alfredo, Cerro Paiva and Sargento José E. López regions. In the main Vallemí quarry, the structural style is characterized by an axial-plane slaty cleavage in open to isoclinal folds, sometimes overturned, associated with N-S trending thrust faults and shear zones of E-vergence and with a low-grade chlorite zone metamorphism. The structural data presented here are compatible with the hypothesis of a newly recognized mobile belt on the western side of the Rio Apa Cratonic Block, with opposite vergence to that of the Paraguay Mobile Belt in Brazil. Both belts are related to the Late Brasiliano/Pan-African tectonic cycle with a Lower Cambrian deformation and metamorphism age. The deformation could be due to the late collision of the Amazonian Craton with the remainder of Western Gondwana or to the western active plate boundary related to the Pampean Belt. The structural and lithologic differences between the western Itapucumí Group in the Vallemí and Paraguay River region and the eastern region, near San Alfredo and Cerro Paiva, suggest that this group could be divided into two lithostratigraphic units, but more stratigraphic and geochronological analyses are required to confirm this possibility.

  13. Healthier home food preparation methods and youth and caregiver psychosocial factors are associated with lower BMI in African American youth.

    PubMed

    Kramer, Rebecca F; Coutinho, Anastasia J; Vaeth, Elisabeth; Christiansen, Karina; Suratkar, Sonali; Gittelsohn, Joel

    2012-05-01

    Obesity disproportionately affects African American (AA) children and adolescents and leads to an increased risk of adult chronic diseases. Eating few meals at home has been implicated as a cause of obesity among youth, but to our knowledge, previous studies have not specifically investigated this relationship in AA adolescents or looked at both the healthfulness and frequency of home meals in AA households. The objective of the present study was to investigate the relationship between home food preparation and adolescent BMI in a sample of 240 AA adolescents aged 10-15 y and their caregivers. Multiple linear regressions were used to model psychosocial characteristics, household factors, and adolescent and caregiver food preparation behaviors as predictors of adolescent BMI, and psychosocial and household factors as predictors of food preparation behavior. Adolescents in the sample had a mean BMI-for-age percentile of 70.4, and >90% of the sample families received at least one form of food assistance. Adolescent children of caregivers who used healthier cooking methods were more likely to use healthy cooking methods themselves (P = 0.02). Having more meals prepared by a caregiver was predictive of higher BMI-for-age percentile in adolescents (P = 0.02), but healthier cooking methods used by the caregiver was associated with reduced risk of adolescent overweight or obesity (P < 0.01). Meals prepared at home in AA households do not necessarily promote healthy BMI in youth. Family meals are a promising adolescent obesity prevention strategy, but it is important to target both frequency and healthfulness of meals prepared at home for effective health promotion in AA families. PMID:22457390

  14. Preliminary studies developing methods for the control of Chrysomya putoria, the African latrine fly, in pit latrines in The Gambia

    PubMed Central

    Lindsay, T C; Jawara, M; D'Alessandro, U; Pinder, M; Lindsay, S W

    2013-01-01

    Objective To explore ways of controlling Chrysomya putoria, the African latrine fly, in pit latrines. As pit latrines are a major source of these flies, eliminating these important breeding sites is likely to reduce village fly populations, and may reduce the spread of diarrhoeal pathogens. Methods We treated 24 latrines in a Gambian village: six each with (i) pyriproxyfen, an insect juvenile hormone mimic formulated as Sumilarv® 0.5G, a 0.5% pyriproxyfen granule, (ii) expanded polystyrene beads (EPB), (iii) local soap or (iv) no treatment as controls. Flies were collected using exit traps placed over the drop holes, weekly for five weeks. In a separate study, we tested whether latrines also function as efficient flytraps using the faecal odours as attractants. We constructed six pit latrines each with a built-in flytrap and tested their catching efficiency compared to six fish-baited box traps positioned 10 m from the latrine. Focus group discussions conducted afterwards assessed the acceptability of the flytrap latrines. Results Numbers of emerging C. putoria were reduced by 96.0% (95% CIs: 94.5–97.2%) 4–5 weeks after treatment with pyriproxyfen; by 64.2% (95% CIs: 51.8–73.5%) after treatment with local soap; by 41.3% (95% CIs = 24.0–54.7%) after treatment with EPB 3–5 weeks after treatment. Flytraps placed on latrines collected C. putoria and were deemed acceptable to local communities. Conclusions Sumilarv 0.5G shows promise as a chemical control agent, whilst odour-baited latrine traps may prove a useful method of non-chemical fly control. Both methods warrant further development to reduce fly production from pit latrines. A combination of interventions may prove effective for the control of latrine flies and the diseases they transmit. PMID:23198767

  15. A Novel Objective Method of Estimating the Age of Mandibles from African Elephants (Loxodonta africana Africana)

    PubMed Central

    Stansfield, Fiona J.

    2015-01-01

    The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa. Irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. Elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar progression. These ‘Age Reference Lines’ were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age. The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70–75 years. Methods to aid in molar identification and the sexing of found jaws were also identified. PMID:25970428

  16. A Novel Objective Method of Estimating the Age of Mandibles from African Elephants (Loxodonta africana Africana).

    PubMed

    Stansfield, Fiona J

    2015-01-01

    The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa. Irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. Elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar progression. These 'Age Reference Lines' were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age. The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70-75 years. Methods to aid in molar identification and the sexing of found jaws were also identified. PMID:25970428

  17. Flood Frequency of Unregulated Streams of Tennessee Using Regional-Regression Equations and the Region-of-Influence Method

    USGS Publications Warehouse

    Law, G.S.; Tasker, Gary D.

    2003-01-01

    The region-of-influence method and regional-regression equations are used to predict flood frequency of unregulated and ungaged rivers and streams of Tennessee. The prediction methods have been developed using strem-gage records from unregulated streams draining basins having 1-30% total impervious area. A computer application automates the calculation of the flood frequencies of the unregulated streams. Average deleted-residual prediction errors for the region-of-influence method are found to be slightly smaller than those for the regional regression methods.

  18. Geochemistry and isotopic evolution of the central African Domes, Bangweulu and Irumide regions: Evidence for cryptic Archean sources and a Paleoproterozoic continental arc

    NASA Astrophysics Data System (ADS)

    Debruyne, David; Van Wilderode, Jorik; Balcaen, Lieve; Vanhaecke, Frank; Muchez, Philippe

    2014-12-01

    The interregional cratonic relations between the Paleo- and Mesoproterozoic basement units surrounding the Neoproterozoic Central African Copperbelt are still largely unresolved, although they are regarded as major potential metal sources. This study focuses on the Domes region basement at depth below the Copperbelt and its relationship to the neighboring Bangweulu Block and its destabilized margin, the Irumide Belt. We applied an integrated whole rock petrochemical and Sm-Nd isotopic approach to major lithological units to assess the proposed mid-Proterozoic arc setting for the Domes basement inliers along with their relationship to the neighboring areas. The available petrochemical and isotopic data for the Paleoproterozoic eastern Domes granitoids and magmatic units in the SW Bangweulu Block is consistent with a continental arc setting. Moreover, the mid-Paleoproterozoic Nd isotope ratios preclude an island arc because they are significantly less radiogenic than the depleted mantle. Predominantly Archean and Early Paleoproterozoic depleted mantle model ages in all terranes indicate limited juvenile input during Paleo- and Mesoproterozoic magmatic phases. Finally, broadly similar model ages in the Domes inliers and the Bangweulu-Irumide region suggest a relationship between these terranes.

  19. Women's views on consent, counseling and confidentiality in PMTCT: a mixed-methods study in four African countries

    PubMed Central

    2012-01-01

    Background Ambitious UN goals to reduce the mother-to-child transmission of HIV have not been met in much of Sub-Saharan Africa. This paper focuses on the quality of information provision and counseling and disclosure patterns in Burkina Faso, Kenya, Malawi and Uganda to identify how services can be improved to enable better PMTCT outcomes. Methods Our mixed-methods study draws on data obtained through: (1) the MATCH (Multi-country African Testing and Counseling for HIV) study's main survey, conducted in 2008-09 among clients (N = 408) and providers at health facilities offering HIV Testing and Counseling (HTC) services; 2) semi-structured interviews with a sub-set of 63 HIV-positive women on their experiences of stigma, disclosure, post-test counseling and access to follow-up psycho-social support; (3) in-depth interviews with key informants and PMTCT healthcare workers; and (4) document study of national PMTCT policies and guidelines. We quantitatively examined differences in the quality of counseling by country and by HIV status using Fisher's exact tests. Results The majority of pregnant women attending antenatal care (80-90%) report that they were explained the meaning of the tests, explained how HIV can be transmitted, given advice on prevention, encouraged to refer their partners for testing, and given time to ask questions. Our qualitative findings reveal that some women found testing regimes to be coercive, while disclosure remains highly problematic. 79% of HIV-positive pregnant women reported that they generally keep their status secret; only 37% had disclosed to their husband. Conclusion To achieve better PMTCT outcomes, the strategy of testing women in antenatal care (perceived as an exclusively female domain) when they are already pregnant needs to be rethought. When scaling up HIV testing programs, it is particularly important that issues of partner disclosure are taken seriously. PMID:22236097

  20. A framework for process-based assessment of regional climate model experiments: applied to projections of southern African precipitation

    NASA Astrophysics Data System (ADS)

    James, Rachel; Washington, Richard; Jones, Richard

    2015-04-01

    There is a demand from adaptation planners for regional climate change projections, particularly the finer resolution data delivered by regional models. However, climate models are subject to important uncertainties, and their projections diverge substantially, particularly for precipitation. So how should decision makers know which futures to consider and which to disregard? Model evaluation is clearly a priority. The majority of studies seeking to assess the validity of projections are based on comparison of the models' twentieth century climatologies with observations or reanalysis. Whilst this work is very important, examination of the modelled mean state it is not sufficient to assess the credibility of modelled changes. Direct investigation of the mechanisms for change is also vital. In this study, a framework for process-based analysis of projections is presented, whereby circulation changes accompanying future responses are examined, and then compared to atmospheric dynamics during historical years in models and reanalyses. This framework has previously been applied to investigate a drying signal in West Africa, and will here be used to examine projected precipitation change in southern Africa. An ensemble of five global and regional model experiments will be employed, consisting of five perturbed versions of HadCM3 and five corresponding runs of HadRM3P (PRECIS), run over the CORDEX Africa domain. The global and regional model runs show contrasting future responses: there is a strong drying in the global models over southern Africa during the rainy season, but the regional models show drying over Madagascar and the south west Indian Ocean. Circulation changes associated with these projections will be presented as a first step towards understanding the mechanisms for change and the reasons for difference between the global and regional models. The interannual variability will also be examined and compared to reanalysis to explore how well the models

  1. Phylogeny of African cichlid fishes as revealed by molecular markers.

    PubMed

    Mayer, W E; Tichy, H; Klein, J

    1998-06-01

    The species flocks of cichlid fish in the three great East African Lakes, Victoria, Malawi, and Tanganyika, have arisen in each lake by explosive adaptive radiation. Various questions concerning their phylogeny have not yet been answered. In particular, the identity of the ancestral founder species and the monophyletic origin of the haplochromine cichlids from the East African lakes have not been established conclusively. In the present study, we used the anonymous nuclear DNA marker DXTU1 as a step towards answering these questions. A 280 bp-fragment of the DXTU1 locus was amplified by the polymerase chain reaction from East African lacustrine species, the East African riverine cichlid species Haplochromis bloyeti, H. burtoni and H. sparsidens, and other African cichlids. Sequencing revealed several indels and substitutions that were used as cladistically informative markers to support a phylogenetic tree constructed by the neighbor-joining method. The topology, although not supported by high bootstrap values, corresponds well to the geographical distribution and previous classification of the cichlids. Markers could be defined that: (i) differentiate East African from West African cichlids; (ii) distinguish the riverine and Lake Victoria/Malawi haplochromines from Lake Tanganyika cichlids; and (iii) indicate the existence of a monophyletic Lake Victoria cichlid superflock which includes haplochromines from satellite lakes and East African rivers. In order to resolve further the relationship of East African riverine and lacustrine species, mtDNA cytochrome b and control region segments were sequenced. The mtDNA-based trees support the notion of the monophyly of the Lake Victoria superflock but are ambiguous with respect to the phylogenetic position of the Lake Malawi flock. PMID:9675872

  2. Treatability and characterization of Natural Organic Matter (NOM) in South African waters using newly developed methods

    NASA Astrophysics Data System (ADS)

    Nkambule, T. I.; Krause, R. W. M.; Haarhoff, J.; Mamba, B. B.

    Managing the removal of Natural Organic Matter (NOM) or problematic components from water has become increasingly important. NOM is a heterogeneous mixture of organic compounds of human origin and derived from plant and microbial residues. The inadequate removal of NOM has a bearing on the capacity of the other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water. In addition the action of certain disinfection processes has been shown to lead to the formation of harmful disinfection by-products (DBPs). Owing to the complexity, in composition and structure, of NOM, the techniques currently employed for its characterization have a number of limitations, both in terms of quantification and removal of the NOM within short periods of time. The dissolved organic carbon (DOC), biodegradable dissolved organic carbon (BDOC) and Fluorescence Emission Excitation Matrices (FEEM) were used to characterize NOM from various water samples collected around South Africa. Characterization results gave an indication of the character of NOM present in all the water samples. FEEM and UV-Vis results indicated that most of the water samples were aromatic in nature, since they had high hydrophobic and humic acid-like materials content. Generally, the characterization data indicated a varying composition of NOM amongst the various sampling points. The polarity rapid assessment method (PRAM) was then employed as a rapid NOM characterization tool. The characterization under PRAM is based on preferential adsorption of dissolved organic matter (DOM) fractions onto solid phase extraction (SPE) sorbents. The PRAM also allows the separation of DOM into fractions by polarity, hence reducing the molecular heterogeneity of NOM and thus aiding the removal of specific NOM fractions from water. The PRAM provided a quick characterization of the NOM character. However, DOC quantification by the PRAM analysis was hindered by excessive carbon leaching

  3. Future changes in African temperature and precipitation in an ensemble of Africa-CORDEX regional climate model simulations

    NASA Astrophysics Data System (ADS)

    Kjellström, Erik; Nikulin, Grigory; Gbobaniyi, Emiola; Jones, Colin

    2013-04-01

    In this study we investigate possible changes in temperature and precipitation on a regional scale over Africa from 1961 to 2100. We use data from two ensembles of climate simulations, one global and one regional, over the Africa-CORDEX domain. The global ensemble includes eight coupled atmosphere ocean general circulation models (AOGCMs) from the CMIP5 project with horizontal resolution varying from about 1° to 3°, namely CanESM2, CNRM-CM5, HadGEM2-ES, NorESM1-M, EC-EARTH, MIROC5, GFDL-ESM2M and MPI-ESM-LR. In the regional ensemble all 8 AOGCMs are downscaled at the Rossby Centre (SMHI) by a regional climate model - RCA4 at 0.44° resolution. Two forcing scenarios are considered, RCP 4.5 and 8.5. The experimental setup allows us to illustrate how uncertainties in future climate change are related to forcing scenario and to forcing AOGCM at different time periods. Further, we investigate the benefit of the higher horizontal resolution in RCA4 by comparing the results to the coarser driving AOGCM data. The significance of the results is investigated by comparing to i) the model simulated natural variability, and, ii) the biases in the control period. Results dealing with changes in the seasonal cycle of temperature and precipitation are presented. We also address higher-order variability by showing results for changes in temperature extremes and for changes in intensity and frequency of extreme precipitation.

  4. Resolution dependence in simulating the African hydroclimate with the HadGEM3-RA regional climate model

    NASA Astrophysics Data System (ADS)

    Moufouma-Okia, W.; Jones, R.

    2015-02-01

    This study documents the effect of horizontal resolution on the ability of the Met Office third-generation Global Atmosphere Regional Climate Model (HadGEM3-RA), a regional atmospheric configuration of the HadGEM3 model, to simulate rainfall variability over Africa. It is based on six 20-year long RCM simulations driven by ERA-Interim reanalysis and performed at 12, 25, 50, 70, 90, and 150 km over the CORDEX-Africa domain. To gain further insight into model errors, we also compared the HadGEM3-RA's performance to that of the parent General Circulation Model using three different spatial resolutions (70, 100, and 150 km), and to HadRM3P—the current Met Office regional climate model. It is found that the 50 km resolution RCM reproduces reasonably the spatial and temporal features of rainfall variability across regions. These include the seasonal progression of the tropical rainbelt, its extent and location, the annual cycle and interannual variability. Although model biases vary across seasons and locations, a prominent feature is the over-prediction of rainfall totals over Central Africa, and underestimation of rainfall in coastal areas of the Guinea Gulf during boreal spring and autumn. HadGEM3-RA improves with increased horizontal resolution, but some model errors persist. Comparison with the parent global model simulations demonstrates generally a realistic and consistent behaviour over large scales—suggesting that the physical formulation is able to capture the key driving processes, but also confirms the benefit of increasing the model horizontal resolution. Despite the model errors, HadGEM3-RA rainfall shows superiority over that from HadRM3P, ERA-Interim and MERRA datasets—indicating that the associated dynamical features of HadGEM3-RA can complement the physical understanding gained from reanalyses. This article also highlights the challenges for evaluating climate models in data sparse regions where satellite derived rainfall and gridded observational

  5. 9 CFR 94.17 - Dry-cured pork products from regions where foot-and-mouth disease, rinderpest, African swine...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the Federal Meat Inspection Act (21 U.S.C. 601 et seq.) and regulations thereunder (9 CFR, chapter III... where foot-and-mouth disease, rinderpest, African swine fever, classical swine fever, or swine vesicular... RINDERPEST, FOOT-AND-MOUTH DISEASE, EXOTIC NEWCASTLE DISEASE, AFRICAN SWINE FEVER, CLASSICAL SWINE...

  6. 9 CFR 94.17 - Dry-cured pork products from regions where foot-and-mouth disease, rinderpest, African swine...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the Federal Meat Inspection Act (21 U.S.C. 601 et seq.) and regulations thereunder (9 CFR, chapter III... where foot-and-mouth disease, rinderpest, African swine fever, classical swine fever, or swine vesicular... RINDERPEST, FOOT-AND-MOUTH DISEASE, EXOTIC NEWCASTLE DISEASE, AFRICAN SWINE FEVER, CLASSICAL SWINE...

  7. 9 CFR 94.17 - Dry-cured pork products from regions where foot-and-mouth disease, rinderpest, African swine...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the Federal Meat Inspection Act (21 U.S.C. 601 et seq.) and regulations thereunder (9 CFR, chapter III... where foot-and-mouth disease, rinderpest, African swine fever, classical swine fever, or swine vesicular... RINDERPEST, FOOT-AND-MOUTH DISEASE, EXOTIC NEWCASTLE DISEASE, AFRICAN SWINE FEVER, CLASSICAL SWINE...

  8. 9 CFR 94.17 - Dry-cured pork products from regions where foot-and-mouth disease, rinderpest, African swine...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... (9 CFR, chapter III), including requirements that the pork or pork products be prepared only in... where foot-and-mouth disease, rinderpest, African swine fever, classical swine fever, or swine vesicular... RINDERPEST, FOOT-AND-MOUTH DISEASE, NEWCASTLE DISEASE, HIGHLY PATHOGENIC AVIAN INFLUENZA, AFRICAN SWINE...

  9. 9 CFR 94.17 - Dry-cured pork products from regions where foot-and-mouth disease, rinderpest, African swine...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the Federal Meat Inspection Act (21 U.S.C. 601 et seq.) and regulations thereunder (9 CFR, chapter III... where foot-and-mouth disease, rinderpest, African swine fever, classical swine fever, or swine vesicular... RINDERPEST, FOOT-AND-MOUTH DISEASE, EXOTIC NEWCASTLE DISEASE, AFRICAN SWINE FEVER, CLASSICAL SWINE...

  10. Africa-U.S. Higher Education Collaboration Initiative: Empowering African Higher Education for Africa's Transformation. A Discussion Paper for the Africa Region Post-Summit Workshop. Working Paper

    ERIC Educational Resources Information Center

    National Association of State Universities and Land-Grant Colleges, 2008

    2008-01-01

    This paper examines how higher education can contribute to Africa's transformation, reviews the challenges and priorities for higher education institution building, and introduces a proposed partnership program among African and U.S. higher education institutions to strengthen African higher education. In July of 2007 the National Association of…

  11. Methods for a longitudinal cohort of refugee children in a regional community in Australia

    PubMed Central

    Zwi, Karen; Rungan, Santuri; Woolfenden, Susan; Williams, Katrina; Woodland, Lisa

    2016-01-01

    Purpose Few studies explore the long-term health and well-being of refugee children. A longitudinal cohort of refugee children was created to determine health and well-being outcomes over time. This article describes the methodology used to conduct this study, including sample characteristics and effectiveness of recruitment and retention strategies. Participants Newly arrived refugee children settling in a regional part of Australia aged 6 months to 15 years were recruited between 2009 and 2013 and 85% were followed for an average of 31 months. Method and design General practitioners conducted health and pathology examinations shortly after arrival. Additional follow-up assessments were conducted by the research team at an average of 13 months after arrival for the first (year 2) and 31 months for the second (year 3) assessment. Children under 5 years had developmental and children aged 4–17 years had social–emotional screening. Families were assessed for risk and protective factors using a structured interview and the Social Readjustment Ratings Scale. Parent experience of the research was explored. Findings to date Eligibility criteria were met by 158 of 228 (69%) newly arrived children, 61 of whom (39%) were enrolled. Retention was 100% (n=61) at year 2 and 85% at year 3. The study sample was younger than and had an over-representation of African refugees as compared to the eligible population. Parents reported that the research was respectful. Future plans This study demonstrates that a longitudinal cohort study in refugee children is feasible and acceptable, and retention rates can be high. The establishment of this cohort provides the opportunity to analyse valuable data about the early settlement experience, risk and protective factors and long-term health and well-being outcomes in refugee children. These are necessary to identify refugee children in need of additional support and to guide future service delivery. PMID:27558902

  12. Balancing acts: A mixed methods study of the figured world of African American 7th graders in urban science classrooms

    NASA Astrophysics Data System (ADS)

    Cleveland-Solomon, Tanya E.

    What beliefs and cultural models do youth who are underrepresented in science have about the domain of science and about themselves as science learners? What do they imagine is possible for them in relation to science both now and in the future? In other words, what constitutes their figured world of science? This dissertation study, using a mixed methods design, offers new perspectives on the ways that underrepresented youth's unexamined assumptions or cultural models and resources may shape their identities and motivation to learn science. Through analyses of survey and interview data, I found that urban African American youths' social context, gender, racial identity, and perceptions of the science they had in school influenced their motivation to learn science. Analyses of short-term classroom observations and interviews suggested that students had competing cultural models that they used in their constructions of identities as science learners, which they espoused and adopted in relation to how well they leveraged the science-related cultural resources available to them. Results from this study suggested that these 7th graders would benefit from access to more expansive cultural models through access to individuals with scientific capital as a way to allow them to create fruitful identities as science learners. If we want to ensure that students from groups that are underrepresented in science not only have better outcomes, but aspire to and enter the science career pipeline, we must also begin to support them in their negotiations of competing cultural models that limit their ability to adopt science-learner identities in their classrooms. This study endeavored to understand the particular cultural models and motivational beliefs that drive students to act, and what types of individuals they imagine scientists and science workers to be. This study also examined how cultural models and resources influence identity negotiation, specifically the roles youths

  13. Redefining racial residential segregation and its association with physical activity among African Americans 50 years and older: a mixed methods approach.

    PubMed

    Armstrong-Brown, Janell; Eng, Eugenia; Hammond, Wizdom Powell; Zimmer, Catherine; Bowling, J Michael

    2015-04-01

    Physical inactivity is one of the factors contributing to disproportionate disease rates among older African Americans. Previous literature indicates that older African Americans are more likely to live in racially segregated neighborhoods and that racial residential segregation is associated with limited opportunities for physical activity. A cross-sectional mixed methods study was conducted guided by the concept of therapeutic landscapes. Multilevel regression analyses demonstrated that racial residential segregation was associated with more minutes of physical activity and greater odds of meeting physical activity recommendations. Qualitative interviews revealed the following physical activity related themes: aging of the neighborhood, knowing your neighbors, feeling of safety, and neighborhood racial identity. Perceptions of social cohesion enhanced participants' physical activity, offering a plausible explanation to the higher rates of physical activity found in this population. Understanding how social cohesion operates within racially segregated neighborhoods can help to inform the design of effective interventions for this population. PMID:24812201

  14. [Hand injuries caused by snake bites. Apropos of 9 cases treated in a West African regional hospital].

    PubMed

    Ribault, L

    1990-01-01

    The author reports 9 cases of snake bite hand injuries in a regional hospital in the ivory coast. This study presents a number of particular points: patients often consult quite late; the precarious hygiene induces microbia contamination; patients often have a very poor conception of their body schema, which sometimes creates problems of understanding during reeducation. Treatment consists of emergency debridement under antibiotic cover of Iselin's "emergency with delayed surgery". The good blood supply of the hand allows satisfactory functional results. PMID:1712571

  15. Nonlinear responses of southern African rainfall to forcing from Atlantic SST in a high-resolution regional climate model

    NASA Astrophysics Data System (ADS)

    Williams, C.; Kniveton, D.; Layberry, R.

    2009-04-01

    It is increasingly accepted that any possible climate change will not only have an influence on mean climate but may also significantly alter climatic variability. A change in the distribution and magnitude of extreme rainfall events (associated with changing variability), such as droughts or flooding, may have a far greater impact on human and natural systems than a changing mean. This issue is of particular importance for environmentally vulnerable regions such as southern Africa. The subcontinent is considered especially vulnerable to and ill-equipped (in terms of adaptation) for extreme events, due to a number of factors including extensive poverty, famine, disease and political instability. Rainfall variability is a function of scale, so high spatial and temporal resolution data are preferred to identify extreme events and accurately predict future variability. In this research, high resolution satellite derived rainfall data from the Microwave Infra-Red Algorithm (MIRA) are used as a basis for undertaking model experiments using a state-of-the-art regional climate model. The MIRA dataset covers the period from 1993-2002 and the whole of southern Africa at a spatial resolution of 0.1 degree longitude/latitude. Once the model's ability to reproduce extremes has been assessed, idealised regions of sea surface temperature (SST) anomalies are used to force the model, with the overall aim of investigating the ways in which SST anomalies influence rainfall extremes over southern Africa. In this paper, results from sensitivity testing of the regional climate model's domain size are briefly presented, before a comparison of simulated daily rainfall from the model with the satellite-derived dataset. Secondly, simulations of current climate and rainfall extremes from the model are compared to the MIRA dataset at daily timescales. Finally, the results from the idealised SST experiments are presented, suggesting highly nonlinear associations between rainfall extremes

  16. Larger genetic differences within africans than between Africans and Eurasians.

    PubMed Central

    Yu, Ning; Chen, Feng-Chi; Ota, Satoshi; Jorde, Lynn B; Pamilo, Pekka; Patthy, Laszlo; Ramsay, Michele; Jenkins, Trefor; Shyue, Song-Kun; Li, Wen-Hsiung

    2002-01-01

    The worldwide pattern of single nucleotide polymorphism (SNP) variation is of great interest to human geneticists, population geneticists, and evolutionists, but remains incompletely understood. We studied the pattern in noncoding regions, because they are less affected by natural selection than are coding regions. Thus, it can reflect better the history of human evolution and can serve as a baseline for understanding the maintenance of SNPs in human populations. We sequenced 50 noncoding DNA segments each approximately 500 bp long in 10 Africans, 10 Europeans, and 10 Asians. An analysis of the data suggests that the sampling scheme is adequate for our purpose. The average nucleotide diversity (pi) for the 50 segments is only 0.061% +/- 0.010% among Asians and 0.064% +/- 0.011% among Europeans but almost twice as high (0.115% +/- 0.016%) among Africans. The African diversity estimate is even higher than that between Africans and Eurasians (0.096% +/- 0.012%). From available data for noncoding autosomal regions (total length = 47,038 bp) and X-linked regions (47,421 bp), we estimated the pi-values for autosomal regions to be 0.105, 0.070, 0.069, and 0.097% for Africans, Asians, Europeans, and between Africans and Eurasians, and the corresponding values for X-linked regions to be 0.088, 0.042, 0.053, and 0.082%. Thus, Africans differ from one another slightly more than from Eurasians, and the genetic diversity in Eurasians is largely a subset of that in Africans, supporting the out of Africa model of human evolution. Clearly, one must specify the geographic origins of the individuals sampled when studying pi or SNP density. PMID:12019240

  17. Methods for comparing beebread made by Africanized and European honey bees and the effects on hemolymph protein titers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of genotype on the conversion of pollen to beebread and on the ability of bees to acquire protein from it was examined using European and Africanized honey bees (EHB and AHB respectively). Both subspecies were provided with the same pollen source. Pollen stored and converted to beebr...

  18. AN OVERVIEW OF DATA INTEGRATION METHODS FOR REGIONAL ASSESSMENT

    EPA Science Inventory

    One of the goals of the EPA's Regional Vulnerability Assessment (ReVA) project is to take diverse environmental data and develop objective criteria to evaluate environmental risk assessments at the regions: scale. The data include (but are not limited to) variables for forests, ...

  19. Seismic Anisotropy of the Lithosphere/Asthenosphere System Beneath the Rwenzori Region of the East-African Rift

    NASA Astrophysics Data System (ADS)

    Homuth, B.; Löbl, U.; Batte, A.; Link, K.; Kasereka, C.; Rumpker, G.

    2014-12-01

    We present results from a temporary seismic network of 32 broad-band stations located around the Rwenzori region of the Albertine rift at the border between Uganda and DR Congo. The study aims to constrain seismic anisotropy and mantle deformation processes in relation to the formation of the rift zone. Shear-wave splitting measurements from local and teleseismic earthquakes are used to investigate the seismic anisotropy in the crust and upper mantle beneath the Rwenzori region. At most stations, shear-wave splitting parameters obtained from individual earthquakes exhibit only minor variations with backazimuth. We therefore employ a joint inversion of SKS waveforms to derive hypothetical one-layer parameters. The corresponding fast polarizations are generally rift-parallel and the average delay time is about 1 s. On the other hand, shear phases from local events within the crust are characterized by an average delay time of 0.04 s. This observation suggests that the dominant source region for seismic anisotropy beneath the rift is located within the mantle. We use finite-frequency waveform modeling to test different models of anisotropy within the lithosphere/asthenosphere system of the rift. The results show that the rift-parallel fast polarizations are consistent with HTI anisotropy caused by magmatic intrusions or lenses located within the lithospheric mantle - as it would be expected during the early stages of continental rifting. Furthermore, the short-scale spatial variations in the fast polarizations observed in the southern part of the study area can be explained by effects due to sedimentary basins of low isotropic velocity in combination with a shift in the orientation of anisotropic fabrics in the upper mantle. A uniform anisotropic layer in relation to large-scale asthenospheric mantle flow is less consistent with the observed splitting parameters.

  20. Seismic anisotropy of the lithosphere/asthenosphere system beneath the Rwenzori region of the East-African Rift

    NASA Astrophysics Data System (ADS)

    Homuth, Benjamin; Löbl, Ulrike; Batte, Arthur; Link, Klemens; Kasereka, Celestine; Rümpker, Georg

    2014-05-01

    We present results from a temporary seismic network of 32 broad-band stations located around the Rwenzori region of the Albertine rift at the border between Uganda and DR Congo. The study aims to constrain seismic anisotropy and mantle deformation processes in relation to the formation of the rift zone. Shear-wave splitting measurements from local and teleseismic earthquakes are used to investigate the seismic anisotropy in the crust and upper mantle beneath the Rwenzori region. At most stations, shear-wave splitting parameters obtained from individual earthquakes exhibit only minor variations with backazimuth. We therefore employ a joint inversion of SKS waveforms to derive hypothetical one-layer parameters. The corresponding fast polarizations are generally rift-parallel and the average delay time is about 1 s. On the other hand, shear phases from local events within the crust are characterized by a bimodal pattern of fast polarizations and an average delay time of 0.04 s. This observation suggests that the dominant source region for seismic anisotropy beneath the rift is located within the mantle. We use finite-frequency waveform modeling to test different models of anisotropy within the lithosphere/asthenosphere system of the rift. The results show that the rift-parallel fast polarizations are consistent with HTI anisotropy caused by rift-parallel magmatic intrusions or lenses located within the lithospheric mantle - as it would be expected during the early stages of continental rifting. Furthermore, the short-scale spatial variations in the fast polarizations observed in the southern part of the study area can be explained by effects due to sedimentary basins of low isotropic velocity in combination with a shift in the orientation of anisotropic fabrics in the upper mantle. A uniform anisotropic layer in relation to large-scale asthenospheric mantle flow is less consistent with the observed splitting parameters.

  1. Scanning linear estimation: improvements over region of interest (ROI) methods

    NASA Astrophysics Data System (ADS)

    Kupinski, Meredith K.; Clarkson, Eric W.; Barrett, Harrison H.

    2013-03-01

    In tomographic medical imaging, a signal activity is typically estimated by summing voxels from a reconstructed image. We introduce an alternative estimation scheme that operates on the raw projection data and offers a substantial improvement, as measured by the ensemble mean-square error (EMSE), when compared to using voxel values from a maximum-likelihood expectation-maximization (MLEM) reconstruction. The scanning-linear (SL) estimator operates on the raw projection data and is derived as a special case of maximum-likelihood estimation with a series of approximations to make the calculation tractable. The approximated likelihood accounts for background randomness, measurement noise and variability in the parameters to be estimated. When signal size and location are known, the SL estimate of signal activity is unbiased, i.e. the average estimate equals the true value. By contrast, unpredictable bias arising from the null functions of the imaging system affect standard algorithms that operate on reconstructed data. The SL method is demonstrated for two different tasks: (1) simultaneously estimating a signal’s size, location and activity; (2) for a fixed signal size and location, estimating activity. Noisy projection data are realistically simulated using measured calibration data from the multi-module multi-resolution small-animal SPECT imaging system. For both tasks, the same set of images is reconstructed using the MLEM algorithm (80 iterations), and the average and maximum values within the region of interest (ROI) are calculated for comparison. This comparison shows dramatic improvements in EMSE for the SL estimates. To show that the bias in ROI estimates affects not only absolute values but also relative differences, such as those used to monitor the response to therapy, the activity estimation task is repeated for three different signal sizes.

  2. Regional assessment of lake ecological states using Landsat: A classification scheme for alkaline-saline, flamingo lakes in the East African Rift Valley

    NASA Astrophysics Data System (ADS)

    Tebbs, E. J.; Remedios, J. J.; Avery, S. T.; Rowland, C. S.; Harper, D. M.

    2015-08-01

    In situ reflectance measurements and Landsat satellite imagery were combined to develop an optical classification scheme for alkaline-saline lakes in the Eastern Rift Valley. The classification allows the ecological state and consequent value, in this case to Lesser Flamingos, to be determined using Landsat satellite imagery. Lesser Flamingos depend on a network of 15 alkaline-saline lakes in East African Rift Valley, where they feed by filtering cyanobacteria and benthic diatoms from the lakes' waters. The classification developed here was based on a decision tree which used the reflectance in Landsat ETM+ bands 2-4 to assign one of six classes: low phytoplankton biomass; suspended sediment-dominated; microphytobenthos; high cyanobacterial biomass; cyanobacterial scum and bleached cyanobacterial scum. The classification accuracy was 77% when verified against in situ measurements. Classified imagery and timeseries were produced for selected lakes, which show the different ecological behaviours of these complex systems. The results have highlighted the importance to flamingos of the food resources offered by the extremely remote Lake Logipi. This study has demonstrated the potential of high spatial resolution, low spectral resolution sensors for providing ecologically valuable information at a regional scale, for alkaline-saline lakes and similar hypereutrophic inland waters.

  3. Wild Termitomyces Species Collected from Ondo and Ekiti States Are More Related to African Species as Revealed by ITS Region of rDNA

    PubMed Central

    Oyetayo, Victor Olusegun

    2012-01-01

    Molecular identification of eighteen Termitomyces species collected from two states, Ondo and Ekiti in Nigeria was carried out using the internal transcribed spacer (ITS) region. The amplicons obtained from rDNA of Termitomyces species were compared with existing sequences in the NCBI GenBank. The results of the ITS sequence analysis discriminated between all the Termitomyces species (obtained from Ondo and Ekiti States) and Termitomyces sp. sequences obtained from NCBI GenBank. The degree of similarity of T1 to T18 to gene of Termitomyces sp. obtained from NCBI ranges between 82 and 99 percent. Termitomyces species from Garbon with ascension number AF321374 was the closest relative of T1 to T18 except T12 that has T. eurhizus and T. striatus as the closet relative. Phylogenetic tree generated with ITS sequences obtained from NCBI GenBank data revealed that T1 to T18 are more related to Termitomyces species indigenous to African countries such as Senegal, Congo, and Gabon. PMID:22649309

  4. Trend analysis of carbon monoxide distributions for changes in fire vs. anthropogenic sources in diverse African regions

    NASA Astrophysics Data System (ADS)

    Worden, H. M.; Worden, J. R.; Bloom, A. A.; Bowman, K. W.

    2015-12-01

    Satellite measurements of atmospheric carbon monoxide (CO) provide a signature for biomass burning and anthropogenic combustion-related pollution emissions. CO plays an important role in both air quality and climate as a precursor for tropospheric ozone and as a major sink of OH, the atmospheric "detergent" that affects the lifetime of methane and other pollutants. Worden et al., [2013] showed decreasing global CO values in time series of satellite total column CO measurements over the past decade. All of the satellite instruments that measure CO in the thermal infrared showed consistent inter-annual variability due to fires and possibly the global recession in late 2008. Observed decreases in CO over N. America and Europe were consistent with expected decreases in CO emissions inventories [Granier et al., 2011], however, the decrease is not uniform globally. In particular, Africa shows regions with smaller negative trends and potentially increasing trends in CO concentration. Here we examine trends for surface and total column CO concentrations in Africa over 2002-2014 using MOPITT V5J data. Our hypothesis is that temporal changes in CO will have different signatures related to anthropogenic and biomass burning emissions. We use singular value decomposition (SVD) with time series from different regions based on vegetation type and population density to diagnose the dominant trends and their potential drivers.

  5. Regional methods for mapping major faults in areas of uniform low relief, as used in the London Basin, UK

    NASA Astrophysics Data System (ADS)

    Haslam, Richard; Aldiss, Donald

    2013-04-01

    Most of the London Basin, south-eastern UK, is underlain by the Palaeogene London Clay Formation, comprising a succession of rather uniform marine clay deposits up to 150 m thick, with widespread cover of Quaternary deposits and urban development. Therefore, in this area faults are difficult to delineate (or to detect) by conventional geological surveying methods in the field, and few are shown on the geological maps of the area. However, boreholes and excavations, especially those for civil engineering works, indicate that faults are probably widespread and numerous in the London area. A representative map of fault distribution and patterns of displacement is a pre-requisite for understanding the tectonic development of a region. Moreover, faulting is an important influence on the design and execution of civil engineering works, and on the hydrogeological characteristics of the ground. This paper reviews methods currently being used to map faults in the London Basin area. These are: the interpretation of persistent scatterer interferometry (PSI) data from time-series satellite-borne radar measurements; the interpretation of regional geophysical fields (Bouguer gravity anomaly and aeromagnetic), especially in combination with a digital elevation model; and the construction and interpretation of 3D geological models. Although these methods are generally not as accurate as large-scale geological field surveys, due to the availability of appropriate data in the London Basin they provide the means to recognise and delineate more faults, and with more confidence, than was possible using traditional geological mapping techniques. Together they reveal regional structures arising during Palaeogene crustal extension and subsidence in the North Sea, followed by inversion of a Mesozoic sedimentary basin in the south of the region, probably modified by strike-slip fault motion associated with the relative northward movement of the African Plate and the Alpine orogeny. This

  6. Geochronology of the Birim Supergroup of the West African craton in the Wa-Bolé region of west-central Ghana: Implications for the stratigraphic framework

    NASA Astrophysics Data System (ADS)

    de Kock, G. S.; Armstrong, R. A.; Siegfried, H. P.; Thomas, E.

    2011-01-01

    The Birim rocks of the West African craton comprise belts of greenschist- to amphibolite-grade gneiss and schist, and subparallel basins of greenschist-grade phyllite of volcaniclastic and epiclastic origin, which were intruded by igneous rocks. The granitoids intruded between 2213 and 2060 Ma and overlap with the volcaniclastic units dated between 2211 and 2064 Ma. The simultaneous occurrence of the magmatic events and irregular distribution of the rock ages hamper the formulation of a stratigraphic succession. SHRIMP spot analyses were done on older cores, crystals and rims from 23 rocks from the Bolé-Wa region in west-central Ghana. The crystallization ages range from 2195 to 2118 Ma, the inherited ages from 2876 to 2130 Ma, and metamorphic ages from 2114 to 2090 Ma. Aided by metamorphic, structural and chemical studies an older geotectonic cycle (2195-2150 Ma), containing the Dole and Guropie Suite and Bolé Group, was established. These units were subjected to several orthogonal and shear deformation events. These events were followed by the contemporaneous Sawla calc-alkaline monzonitic plutonism (2132-2126 Ma) and deposition of the epiclastic Maluwe Group (2137-2125 Ma) of calc-alkaline felsic to tholeiitic volcanic origin. Deformation of the basin beds was succeeded by the intrusion of the Tanina Suite granitoids of 2122-2120 Ma, which, themselves, were deformed prior to 2119 Ma. At 2118 Ma syenite and gabbro intruded along conjugate extension fractures. The gabbro and syenite of the Wakawaka Suite were only affected by three events of brittle strike-slip faulting. The first had significant displacement along NNE- to NE-directed shear zones, while the latter only formed conjugate joint systems with limited transport. Palaeo- to Neoarchaean cores, the oldest yet reported in the Baoulé Mossi domain, are restricted to the gneissic Dole Suite biotite granites. The presence of Dole-, Guropie-, Sawla-, and Tanina-aged older cores and grains in younger rocks

  7. Association of polymorphisms at the ADIPOR1 regulatory region with type 2 diabetes and body mass index in a Brazilian population with European or African ancestry.

    PubMed

    Yeh, E; Kimura, L; Errera, F I V; Angeli, C B; Mingroni-Netto, R C; Silva, M E R; Canani, L H S; Passos-Bueno, M R

    2008-06-01

    Association studies between ADIPOR1 genetic variants and predisposition to type 2 diabetes (DM2) have provided contradictory results. We determined if two single nucleotide polymorphisms (SNP c.-8503G>A and SNP c.10225C>G) in regulatory regions of ADIPOR1 in 567 Brazilian individuals of European (EA; N = 443) or African (AfA; N = 124) ancestry from rural (quilombo remnants; N = 439) and urban (N = 567) areas. We detected a significant effect of ethnicity on the distribution of the allelic frequencies of both SNPs in these populations (EA: -8503A = 0.27; AfA: -8503A = 0.16; P = 0.001 and EA: 10225G = 0.35; AfA: 10225G = 0.51; P < 0.001). Neither of the polymorphisms were associated with DM2 in the case-control study in EA (SNP c.-8503G>A: DM2 group -8503A = 0.26; control group -8503A = 0.30; P = 0.14/SNP 10225C>G: DM2 group 10225G = 0.37; control group 10225G = 0.32; P = 0.40) and AfA populations (SNP c.-8503G>A: DM2 group -8503A = 0.16; control group -8503A = 0.15; P = 0.34/SNP 10225C>G: DM2 group 10225G = 0.51; control group 10225G = 0.52; P = 0.50). Similarly, none of the polymorphisms were associated with metabolic/anthropometric risk factors for DM2 in any of the three populations, except for HDL cholesterol, which was significantly higher in AfA heterozygotes (GC = 53.75 +/- 17.26 mg/dL) than in homozygotes. We conclude that ADIPOR1 polymorphisms are unlikely to be major risk factors for DM2 or for metabolic/anthropometric measurements that represent risk factors for DM2 in populations of European and African ancestries. PMID:18622492

  8. Multi-stage emerald formation during Pan-African regional metamorphism: The Zabara, Sikait, Umm Kabo deposits, South Eastern desert of Egypt

    NASA Astrophysics Data System (ADS)

    Grundmann, G.; Morteani, G.

    2008-02-01

    The genesis of gem-quality deep green emeralds of Zabara, Sikait and Umm Kabo (South Eastern Desert, Egypt) is to date a controversial topic. The emerald-bearing biotite schists and quartz lenses are interpreted alternatively as a product of (i) thrust-fault-shear zone - controlled large scale alkali-metasomatism driven by post-magmatic fluid flow or of (ii) a large scale interaction between syntectonic pegmatitic magma or hydrothermal fluids with pre-existing basic to ultrabasic rocks, or of (iii) a syn- to post-tectonic regional metamorphism and small scale blackwall metasomatism. Detailed microstructural and chemical analyses of the Egyptian emeralds and their host rocks show that three generations of beryl can be distinguished: a colourless pegmatitic beryl; a pale green Cr-poor beryl crystallized from pegmatite-related hydrothermal fluids; and a deep green Cr- and Mg-rich emerald. The crystallization of the Cr- and Mg-rich emerald was controlled by the very local availability of Cr, Mg and Be-rich metamorphic fluids during the Pan-African tectono-thermal event. Emerald-rich quartz lenses demonstrate that those fluids locally did mobilize quartz, too. The pale green emeralds found within the pegmatites in association with colourless beryl are the product of a mobilization of colourless pegmatitic beryl and/or phenakite by late pegmatitic fluids slightly enriched in Cr by an interaction with the Cr-rich country rocks. The late pegmatitic fluids are typically Na-rich as is demonstrated by the pervasive albitization of the pegmatites. The complex interplay of magmatic and regional metamorphic events during the genesis of the Egyptian emeralds/beryls makes it impossible through stable oxygen isotope data to relate their genesis to the one or the other event.

  9. Tyrosinase-positive oculocutaneous albinism in Southern African blacks: P gene-associated haplotypes suggest a major mutation in the 5{prime} region of the gene

    SciTech Connect

    Ramsay, M.; Stevens, G.; Beukering, J. van

    1994-09-01

    Tyrosinase-positive oculocutaneous albinism (ty-pos OCA) occurs with a prevalence of 1 in 3900 among Southern African (SA) blacks. The major contributors to morbidity and mortality are skin cancer and decreased visual acuity. Two distinct phenotypes occur, namely individuals with ephelides (darkly pigmented patches) and those without. There is complete concordance with regard to ephelus status among siblings. The disorder is linked to markers on chromosome 15q11.2-q12, and no obligatory cross-overs were observed with polymophic markers at the human homolog, P, of the mouse pink eyed dilute gene, p. Contrary to what has been shown for Caucasoid ty-pos OCA, this condition shows locus homogeneity among SA blacks. The P gene is an excellent candidate for ty-pos OCA and mutations in this gene will confirm its role in causing the common form of albinism in SA. Numerous P gene mutations have been described in other populations. In an attempt to detect mutations, the P gene cDNA was used to search for structural rearrangements or polymorphisms. Six polymorphisms (plR10/Scal, 912/Xbal, 912/HincII, 912/TaqI, 1412/TaqI [two systems] and 1412/HindIII) were detected with subclones of the P cDNA and haplotypes were determined in each family. None were clearly associated with an albinism-related rearrangement. However, strong linkage disequilibrium was observed with alleles at loci toward the 5{prime} region of the gene ({triangle}=0.65, 0.57 and 0.80 for the three polymorphisms detected with the 912 subclone), suggesting a major ty-pos OCA mutation in this region. Haplotype analysis provides evidence for a major mutation associated with the same haplotype in individuals with ephelides (8/12 OCA chromosomes) and those without ephelides (24:30). The presence of other ty-pos OCA associated haplotypes indicates several other less common mutations.

  10. African-American Student Achievement Research Project.

    ERIC Educational Resources Information Center

    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…

  11. Possible Climate Change/Variability and Human Impacts, Vulnerability of African Drought Prone Regions, its Water Resources and Capacity Building

    NASA Astrophysics Data System (ADS)

    Yew Gan, Thian; Huelsmann, Stephen; Qin, XiaoSheng; Lu, Xi Xi; Liong, Shie-Yui; Rutschmann, Peter; Disse, Markus; Koivusalo, Harri

    2016-04-01

    The climate, water resources and historical droughts of Africa, drought indices, vulnerability, impact of global warming and landuse to drought-prone regions in West, Southern, and Greater Horn of Africa, which have suffered recurrent severe droughts in the past are reviewed first. Recent studies detected warming and drying trends in Africa since the mid-20th century. Based on the 4th Assessment Report of the Intergovernmental Panel of Climate Change, and that of the 5th Coupled Model Intercomparison Project (CMIP5), both northern and southern Africa are projected to experience drying such as decreasing precipitation, runoff and soil moisture in the 21st Century and could become more vulnerable to impact of droughts. The daily maximum temperature is projected to increase up to 8oC (RCP8.5 of CMIP5), precipitation indices such as total wet day precipitation (PRCPTOT) and heavy precipitation days (R10mm) could decrease, while warm spell duration (WSDI) and consecutive dry days (CDD) could increase. Uncertainties of the above long-term projections, teleconnections to climate anomalies such as ENSO and Madden Julian Oscillation which could also affect water resources of Africa, and capacity building in terms of physical infrastructure and non-structural solutions, are also discussed. Given traditional climate and hydrologic data observed in Africa are generally limited, satellite data should also be exploited to fill in the data gap for Africa in future.

  12. Ionospheric F region effects observed in the American and African sectors during the intense geomagnetic storm of September-October 2012

    NASA Astrophysics Data System (ADS)

    De Jesus, Rodolfo; Gende, Mauricio; Fagundes, Paulo Roberto; Coster, Anthea; Bolaji, Segun; Kavutarapu, Venkatesh; De Abreu, Alessandro; Sobral, J. H. A.; Pillat, Valdir Gil; Batista, Inez S.

    This study presents an investigation of geomagnetic disturbance effects on the equatorial, low- and mid-latitude ionospheric F region over the American and African sectors during the intense geomagnetic storm (maximum Kp index of 6.7) that occurred on 30th September, 2012 and 1st October, 2012. In this study digital ionosonde and Global Positioning System (GPS) data are simultaneously utilized from 30th September to 3rd October 2012. The diurnal variability over this four day period observed from both the digital ionosonde and from ground based GPS units can be characterized as quiet, slightly disturbed, and strongly disturbed periods. This time period includes the sudden commencement of the storm (SCS), the main phase (MPS), and the recovery phase of the storm (RPS). During the period of investigation, ionospheric parameters F-region critical frequency (foF2) and minimum F-region virtual height ('hF) were obtained at Jicamarca, São Luís, Fortaleza, Palmas and Port Stanley at the following geographical coordinates, respectively: 12.0ºS 76.8ºW, 2.6ºS 44.2ºW, 3.8ºS 38ºW, 10.2ºS 48.8ºW and 51.6ºS 57.9ºW. In this study, we also used observations of 20 GPS stations located at Greenbelt (39.0ºN, 76.8ºW), Cambridge (38.6ºN, 76.1ºW), Virgin Islands (17.6ºN, 64.6ºW), Eusebio (03.9ºS, 38.4ºW), Iquitos (03.8ºS, 73.3 ºW), Arequipa (16.5ºS, 71.5ºW), Cachoeira Paulista (22.7ºS, 45.0ºW), Copiapo (27.4ºS, 70.4ºW), La Plata (34.9ºS, 57.9ºW), Concepcion (36.8ºS, 73.0ºW), Rio Grande (53.8ºS, 67.8ºW), Dakar (14.7ºN, 17.4ºW), Addis (09.0ºN, 38.8ºE), Cotonou (06.4ºN, 02.5ºE), Libreville (00.4ºN, 09.7ºE), Mbarara (00.6ºS, 30.7ºE), Lusaka (15.4ºS, 28.3ºE), Windhoek (22.6ºS, 17.1ºE), Springbok (29.7ºS, 17.9ºE) and Sutherland (32.4ºS, 20.8ºE). Vertical Total Electron Content (VTEC) and TEC fluctuations (ROT, rate of change of TEC) are calculated from GPS data using the measured Slant Total Electron Content (STEC) records from the 20 GPS

  13. Mitigation of Disasters Due to Severe Climate Events: from Policy to Practice,the West African Coastal Region Experience

    NASA Astrophysics Data System (ADS)

    Ediang, Okuku

    2016-07-01

    The distributive pattern of disaster due to severe climate events over the coast of West Africa especially Nigeria was examined using yearly mean disaster due to severe climatic events for the period of 30 years (1981-2010) from the marine stations in the coastal region of Nigeria. Graphical and isohyetal analyses were used to look into the patter of severe weather events over the area considered and to see if the severe weather events is increasing or not in the coast of West Africa especially the Nigerian coast and how to mitigate ,were policy relating to severe weather events are discussed. The paper conclude that due to the nature of coast of West Africa and Nigeria in particular, it enjoys longer severe weather events season than dry during the wet season, it is common to observe periods of enhanced or suppressed convective activity to persist over the wide areas for somedays. This paper also contributes to the wealth of knowledge already existing on Indigenous people play major roles in preserving the ecosystem especially during severe weather events . This has resulted in the recent calls for the integration of indigenous knowledge systems into global knowledge system strategies. Until now, integrating local knowledge systems into severe weather events and climate change concerns is not a completely new idea. A comprehensive review of literature using electronic and non-electronic databases formed the methodology. The paper conclude also by drawing the attention that by targeting Promoting indigenous people's participation in severe weather events and climate change issues is an important initiative towards adaptation and sustainable development in Africa and around the world. It is increasingly realized that the global knowledge system has dominated research, policies and programmes that address current severe weather events and climate change's challenges,mitigation and adaptation strategies.

  14. How Rainfall Variation Influences Reproductive Patterns of African Savanna Ungulates in an Equatorial Region Where Photoperiod Variation Is Absent.

    PubMed

    Ogutu, Joseph O; Owen-Smith, Norman; Piepho, Hans-Peter; Dublin, Holly T

    2015-01-01

    In high temperate latitudes, ungulates generally give birth within a narrow time window when conditions are optimal for offspring survival in spring or early summer, and use changing photoperiod to time conceptions so as to anticipate these conditions. However, in low tropical latitudes day length variation is minimal, and rainfall variation makes the seasonal cycle less predictable. Nevertheless, several ungulate species retain narrow birth peaks under such conditions, while others show births spread quite widely through the year. We investigated how within-year and between-year variation in rainfall influenced the reproductive timing of four ungulate species showing these contrasting patterns in the Masai Mara region of Kenya. All four species exhibited birth peaks during the putative optimal period in the early wet season. For hartebeest and impala, the birth peak was diffuse and offspring were born throughout the year. In contrast, topi and warthog showed a narrow seasonal concentration of births, with conceptions suppressed once monthly rainfall fell below a threshold level. High rainfall in the previous season and high early rains in the current year enhanced survival into the juvenile stage for all the species except impala. Our findings reveal how rainfall variation affecting grass growth and hence herbivore nutrition can govern the reproductive phenology of ungulates in tropical latitudes where day length variation is minimal. The underlying mechanism seems to be the suppression of conceptions once nutritional gains become insufficient. Through responding proximally to within-year variation in rainfall, tropical savanna ungulates are less likely to be affected adversely by the consequences of global warming for vegetation phenology than northern ungulates showing more rigid photoperiodic control over reproductive timing. PMID:26295154

  15. How Rainfall Variation Influences Reproductive Patterns of African Savanna Ungulates in an Equatorial Region Where Photoperiod Variation Is Absent

    PubMed Central

    Ogutu, Joseph O.; Owen-Smith, Norman; Piepho, Hans-Peter; Dublin, Holly T.

    2015-01-01

    In high temperate latitudes, ungulates generally give birth within a narrow time window when conditions are optimal for offspring survival in spring or early summer, and use changing photoperiod to time conceptions so as to anticipate these conditions. However, in low tropical latitudes day length variation is minimal, and rainfall variation makes the seasonal cycle less predictable. Nevertheless, several ungulate species retain narrow birth peaks under such conditions, while others show births spread quite widely through the year. We investigated how within-year and between-year variation in rainfall influenced the reproductive timing of four ungulate species showing these contrasting patterns in the Masai Mara region of Kenya. All four species exhibited birth peaks during the putative optimal period in the early wet season. For hartebeest and impala, the birth peak was diffuse and offspring were born throughout the year. In contrast, topi and warthog showed a narrow seasonal concentration of births, with conceptions suppressed once monthly rainfall fell below a threshold level. High rainfall in the previous season and high early rains in the current year enhanced survival into the juvenile stage for all the species except impala. Our findings reveal how rainfall variation affecting grass growth and hence herbivore nutrition can govern the reproductive phenology of ungulates in tropical latitudes where day length variation is minimal. The underlying mechanism seems to be the suppression of conceptions once nutritional gains become insufficient. Through responding proximally to within-year variation in rainfall, tropical savanna ungulates are less likely to be affected adversely by the consequences of global warming for vegetation phenology than northern ungulates showing more rigid photoperiodic control over reproductive timing. PMID:26295154

  16. Methods for Data-based Delineation of Spatial Regions

    SciTech Connect

    Wilson, John E.

    2012-10-01

    In data analysis, it is often useful to delineate or segregate areas of interest from the general population of data in order to concentrate further analysis efforts on smaller areas. Three methods are presented here for automatically generating polygons around spatial data of interest. Each method addresses a distinct data type. These methods were developed for and implemented in the sample planning tool called Visual Sample Plan (VSP). Method A is used to delineate areas of elevated values in a rectangular grid of data (raster). The data used for this method are spatially related. Although VSP uses data from a kriging process for this method, it will work for any type of data that is spatially coherent and appears on a regular grid. Method B is used to surround areas of interest characterized by individual data points that are congregated within a certain distance of each other. Areas where data are “clumped” together spatially will be delineated. Method C is used to recreate the original boundary in a raster of data that separated data values from non-values. This is useful when a rectangular raster of data contains non-values (missing data) that indicate they were outside of some original boundary. If the original boundary is not delivered with the raster, this method will approximate the original boundary.

  17. The evaluation of regional frequency analyses methods for nonstationary data

    NASA Astrophysics Data System (ADS)

    Nam, W.; Kim, S.; Kim, H.; Joo, K.; Heo, J.-H.

    2015-06-01

    Regional frequency analysis is widely used to estimate more reliable quantiles of extreme hydro-meteorological events. The stationarity of data is required for its application. This assumption tends to be violated due to climate change. In this paper, four nonstationary index flood models were used to analyze the nonstationary regional data. Monte Carlo simulation was used to evaluate the performances of these models for the generalized extreme value distribution with linearly time varying location parameter and constant scale and shape parameters. As a results, it was found that the index flood model with time-invariant index flood and time-variant growth curve could yield more statistically efficient quantile when record is long enough to show significant nonstationarity.

  18. African Aesthetics

    ERIC Educational Resources Information Center

    Abiodun, Rowland

    2001-01-01

    No single traditional discipline can adequately supply answers to the many unresolved questions in African art history. Because of the aesthetic, cultural, historical, and, not infrequently, political biases, already built into the conception and development of Western art history, the discipline of art history as defined and practiced in the West…

  19. Source regional contributions to PM2.5 in a megacity in China using an advanced source regional apportionment method.

    PubMed

    Tian, Ying-Ze; Chen, Gang; Wang, Hai-Ting; Huang-Fu, Yan-Qi; Shi, Guo-Liang; Han, Bo; Feng, Yin-Chang

    2016-03-01

    To quantify contributions of individual source categories from diverse regions to PM2.5, PM2.5 samples were collected in a megacity in China and analyzed through a newly developed source regional apportionment (SRA) method. Levels, compositions and seasonal variations of speciated PM2.5 dataset were investigated. Sources were determined by Multilinear Engine 2 (ME2) model, and results showed that the PM2.5 in Tianjin was mainly influenced by secondary sulphate & secondary organic carbon SOC (percent contribution of 26.2%), coal combustion (24.6%), crustal dust & cement dust (20.3%), secondary nitrate (14.9%) and traffic emissions (14.0%). The SRA method showed that northwest region R2 was the highest regional contributor to secondary sources, with percent contributions to PM2.5 being 9.7% for secondary sulphate & SOC and 6.0% for secondary nitrates; the highest coal combustion was from local region R1 (6.2%) and northwest R2 (8.0%); the maximum contributing region to crustal & cement dust was southeast region R4 (5.0%); and contributions of traffic emissions were relatively spatial homogeneous. The seasonal variation of regional source contributions was observed: in spring, the crustal and cement dust contributed a higher percentage and the R4 was an important contributor; the secondary process attributed an increase fraction in summer; the mixed coal combustion from southwest R5 enhanced in autumn. PMID:26766363

  20. Stability region maximization by decomposition-aggregation method. [Skylab stability

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.; Cuk, S. M.

    1974-01-01

    This work is to improve the estimates of the stability regions by formulating and resolving a proper maximization problem. The solution of the problem provides the best estimate of the maximal value of the structural parameter and at the same time yields the optimum comparison system, which can be used to determine the degree of stability of the Skylab. The analysis procedure is completely computerized, resulting in a flexible and powerful tool for stability considerations of large-scale linear as well as nonlinear systems.

  1. ‘Peace’ and ‘life worthwhile’ as measures of spiritual well-being in African palliative care: a mixed-methods study

    PubMed Central

    2013-01-01

    Background Patients with incurable, progressive disease receiving palliative care in sub-Saharan Africa experience high levels of spiritual distress with a detrimental impact on their quality of life. Locally validated measurement tools are needed to identify patients’ spiritual needs and evaluate and improve spiritual care, but up to now such tools have been lacking in Africa. The African Palliative Care Association (APCA) African Palliative Outcome Scale (POS) contains two items relating to peace and life worthwhile. We aimed to determine the content and construct validity of these items as measures of spiritual wellbeing in African palliative care populations. Methods The study was conducted at five palliative care services, four in South Africa and one in Uganda. The mixed-methods study design involved: (1) cognitive interviews with 72 patients, analysed thematically to explore the items’ content validity, and (2) quantitative data collection (n = 285 patients) using the POS and the Spirit 8 to assess construct validity. Results (1) Peace was interpreted according to the themes ‘perception of self and world’, ‘relationship to others’, ‘spiritual beliefs’ and ‘health and healthcare’. Life worthwhile was interpreted in relation to ‘perception of self and world’, ‘relationship to others’ and ‘identity’. (2) Conceptual convergence and divergence were also evident in the quantitative data: there was moderate correlation between peace and Spirit 8 spiritual well-being (r = 0.46), but little correlation between life worthwhile and Spirit 8 spiritual well-being (r = 0.18) (both p < 0.001). Correlations with Spirit 8 items were weak to moderate. Conclusions Findings demonstrate the utility of POS items peace and life worthwhile as distinct but related measures of spiritual well-being in African palliative care. Peace and life worthwhile are brief and simple enough to be integrated into routine practice and can be used to

  2. Method For Making Selected Regions Of A Substrate

    DOEpatents

    Fusaro, Jr., Robert Anthony; Bethel, Timothy Francis

    2003-07-15

    Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

  3. Method for masking selected regions of a substrate

    DOEpatents

    Fusaro, Jr., Robert Anthony; Bethel, Timothy Francis

    2010-05-04

    Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

  4. A new time-stepping method for regional climate models

    NASA Astrophysics Data System (ADS)

    Williams, P. D.

    2010-12-01

    The dynamical cores of many regional climate models use the Robert-Asselin filter to suppress the spurious computational mode of the leapfrog scheme. Unfortunately, whilst successfully eliminating the unwanted mode, the Robert-Asselin filter also weakly suppresses the physical solution and degrades the numerical accuracy. These two concomitant problems occur because the filter does not conserve the mean state, averaged over the three time slices on which it operates. This presentation proposes a simple modification to the Robert-Asselin filter, which does conserve the three-time-level mean state. When used in conjunction with the leapfrog scheme, the modification vastly reduces the artificial damping of the physical solution. Correspondingly, the modification increases the numerical accuracy for amplitude errors by two orders, yielding third-order accuracy. The modified filter may easily be incorporated into existing regional climate models, via the addition of only a few lines of code that are computationally very inexpensive. Results will be shown from recent implementations of the modified filter in various models. The modification will be shown to reduce model biases and to significantly improve the predictive skill. Magnitude of the complex amplification factor as a function of the non-dimensional time step, for leapfrog integrations. This quantity would be identical to 1 for a perfect numerical scheme. Clearly, the filter proposed here (case α=0.53) has much smaller numerical errors than the original Robert-Asselin filter (case α=1). Moreover, the proposed filter is trivial to implement and is no more computationally expensive. Taken from Williams (2009; Monthly Weather Review).

  5. Impact of anthropogenic and climatic changes on biomass and diversity of the Central African forests, from local to global scale: original methods for new results

    NASA Astrophysics Data System (ADS)

    Mortier, Frédéric; Gourlet-Fleury, Sylvie; Ouédraogo, Dakis; Picard, Nicolas; Rossi, Vivien

    2014-05-01

    Forests of the Congo Basin, the second most important remaining block of tropical moist forest in the world, are facing increasing anthropogenic pressure and climate change. Understanding the biomass and diversity dynamics under these pressures is one major challenge for African nations and international communities. This talk aims to present original methods to model, infer, and predict growth, biomass and diversity of Central African forests, as well as new results on the impacts of global change on those forests, at various scales. With respect to methods, we will present theoretical frameworks allowing (i) to model growth processes in species-rich ecosystems like tropical rain forests, (ii) to take into account uncertainties in biomass estimation. In terms of results, we will highlight at a local scale, how human activities as well as climatic variations would impact (i) the composition and diversity of forests, (ii) the dynamics of biomass and growth processes. At a global scale, we will demonstrate how environmental filtering controls the above ground biomass. The number of studies are currently increasing over the Congo Basin through several research projects led by our team (CoForTips, DynAfFor) and contributing to various international organization's programs (Cifor, FAO, Comifac, Ofac).

  6. Gas isotopic signatures (He, C, and Ar) in the Lake Kivu region (western branch of the East African rift system): Geodynamic and volcanological implications

    NASA Astrophysics Data System (ADS)

    Tedesco, D.; Tassi, F.; Vaselli, O.; Poreda, R. J.; Darrah, T.; Cuoco, E.; Yalire, M. M.

    2010-01-01

    On 17 January 2002, the city of Goma was partly destroyed by two of the several lava flows erupted from a roughly N-S oriented fracture system opened along the southern flank of Mount Nyiragongo (Democratic Republic of Congo), in the western branch of the East African rift system. A humanitarian and scientific response was promptly organized by international, governmental, and nongovernmental agencies coordinated by the United Nations and the European Union. Among the different scientific projects undertaken to study the mechanisms triggering this and possible future eruptions, we focused on the isotopic (He, C, and Ar) analysis of the magmatic-hydrothermal and cold gas discharges related to the Nyiragongo volcanic system, the Kivu and Virunga region. The studied area includes the Nyiragongo volcano, its surroundings, and peripheral areas inside and outside the rift. They have been subdivided into seven regions characterized by distinct 3He/4He (expressed as R/Rair) ratios and/or δ13C-CO2 values. The Nyiragongo summit crater fumaroles, whose R/Rair and δ13C-CO2 values are up to 8.73 and from -3.5‰ to -4.0‰ VPDB, respectively, show a clear mantle, mid-ocean ridge basalt (MORB)-like contribution. Similar mantle-like He isotopic values (6.5-8.3 R/Rair) are also found in CO2-rich gas emanations (mazukus) along the northern shoreline of Lake Kivu main basin, whereas the 13δC-CO2 values range from -5.3‰ to -6.8‰ VPDB. The mantle influence progressively decreases in (1) dissolved gases of Lake Kivu (2.6-5.5 R/Rair) and (2) the distal gas discharges within and outside the two sides of the rift (from 0.1 to 1.7 R/Rair). Similarly, δ13C-CO2 ratios of the peripheral gas emissions are lighter (from -5.9‰ to -11.6‰ VPDB) than those of the crater fumaroles. Therefore, the spatial distribution of He and C signatures in the Lake Kivu region is mainly produced by mixing of mantle-related (e.g., Nyiragongo crater fumaroles and/or mazukus gases) and crustal-related (e

  7. Regional homogenization of surface temperature records using robust statistical methods

    NASA Astrophysics Data System (ADS)

    Pintar, A. L.; Possolo, A.; Zhang, N. F.

    2013-09-01

    An algorithm is described that is intended to estimate and remove spurious influences from the surface temperature record at a meteorological station, which may be due to changes in the location of the station or in its environment, or in the method used to make measurements, and which are unrelated to climate change, similarly to [1]. The estimate of these influences is based on a comparison of non-parametric decompositions of the target series with series measured at other stations in a neighborhood of the target series. The uncertainty of the estimated spurious artifacts is determined using a statistical bootstrap method that accounts for temporal correlation structure beyond what is expected from seasonal effects. Our computer-intensive bootstrap procedure lends itself readily to parallelization, which makes the algorithm practicable for large collections of stations. The role that the proposed procedure may play in practice is contingent on the results of large-scale testing, still under way, using historical data.

  8. [Possible methods for evaluating bone density in the maxillofacial region].

    PubMed

    Koppány, Ferenc; Joób-Fancsaly, Arpád; Szabo, György

    2007-04-01

    Bone densitometry is a commonly used procedure in general medicine to measure the mineral content of the bone. The method helps in establishing an early diagnosis of metabolic diseases of the bone (especially osteoporosis), which decreases the incidence of pathological fractures in a high degree. Recent studies have shown that significant correlation can be found between the optical densitometric evaluations of the jaws and the densitometric figures of other bones of the skeleton (spine, hip). These results point out the possible role of the dentist in the early diagnosis of osteoporosis. The recent methods in general medicine are based on the measurement of photon and x-ray absorption followed by computerized analysis (single photon absorptiometry, single energy x-ray absorptiometry, dual photon absorptiometry, dual energy x-ray absorptiometry). Besides the previously mentioned techniques ultrasound attenuation detection (quantitative ultrasound) and computed tomographic approaches are also widely spread. Methods utilizing the developed panoramic x-ray films are also being used for densitometric evaluations. The results given by these measurements seem to be promising as a unique detection of the early signs of osteoporosis. PMID:17546899

  9. Genome-wide patterns of population structure and admixture in West Africans and African Americans.

    PubMed

    Bryc, Katarzyna; Auton, Adam; Nelson, Matthew R; Oksenberg, Jorge R; Hauser, Stephen L; Williams, Scott; Froment, Alain; Bodo, Jean-Marie; Wambebe, Charles; Tishkoff, Sarah A; Bustamante, Carlos D

    2010-01-12

    Quantifying patterns of population structure in Africans and African Americans illuminates the history of human populations and is critical for undertaking medical genomic studies on a global scale. To obtain a fine-scale genome-wide perspective of ancestry, we analyze Affymetrix GeneChip 500K genotype data from African Americans (n = 365) and individuals with ancestry from West Africa (n = 203 from 12 populations) and Europe (n = 400 from 42 countries). We find that population structure within the West African sample reflects primarily language and secondarily geographical distance, echoing the Bantu expansion. Among African Americans, analysis of genomic admixture by a principal component-based approach indicates that the median proportion of European ancestry is 18.5% (25th-75th percentiles: 11.6-27.7%), with very large variation among individuals. In the African-American sample as a whole, few autosomal regions showed exceptionally high or low mean African ancestry, but the X chromosome showed elevated levels of African ancestry, consistent with a sex-biased pattern of gene flow with an excess of European male and African female ancestry. We also find that genomic profiles of individual African Americans afford personalized ancestry reconstructions differentiating ancient vs. recent European and African ancestry. Finally, patterns of genetic similarity among inferred African segments of African-American genomes and genomes of contemporary African populations included in this study suggest African ancestry is most similar to non-Bantu Niger-Kordofanian-speaking populations, consistent with historical documents of the African Diaspora and trans-Atlantic slave trade. PMID:20080753

  10. Effects of the intense geomagnetic storm of September-October 2012 on the equatorial, low- and mid-latitude F region in the American and African sector during the unusual 24th solar cycle

    NASA Astrophysics Data System (ADS)

    de Jesus, R.; Fagundes, P. R.; Coster, A.; Bolaji, O. S.; Sobral, J. H. A.; Batista, I. S.; de Abreu, A. J.; Venkatesh, K.; Gende, M.; Abalde, J. R.; Sumod, S. G.

    2016-02-01

    The main purpose of this paper is to investigate the response of the ionospheric F layer in the American and African sectors during the intense geomagnetic storm which occurred on 30 September-01 October 2012. In this work, we used observations from a chain of 20 GPS stations in the equatorial, low- and mid-latitude regions in the American and African sectors. Also, in this study ionospheric sounding data obtained during 29th September to 2nd October, 2012 at Jicamarca (JIC), Peru, São Luis (SL), Fortaleza (FZ), Brazil, and Port Stanley (PST), are presented. On the night of 30 September-01 October, in the main and recovery phase, the h´F variations showed an unusual uplifting of the F region at equatorial (JIC, SL and FZ) and mid- (PST) latitude stations related with the propagations of traveling ionospheric disturbances (TIDs) generated by Joule heating at auroral regions. On 30 September, the VTEC variations and foF2 observations at mid-latitude stations (American sector) showed a long-duration positive ionospheric storm (over 6 h of enhancement) associated with large-scale wind circulations and equatorward neutral winds. Also, on 01 October, a long-duration positive ionospheric storm was observed at equatorial, low- and mid- latitude stations in the African sector, related with the large-scale wind circulations and equatorward neutral winds. On 01 and 02 October, positive ionospheric storms were observed at equatorial, low- and mid-latitude stations in the American sector, possibly associated with the TIDs and an equatorward neutral wind. Also, on 01 October negative ionospheric storms were observed at equatorial, low- and mid-latitude regions in the American sector, probably associated with the changes in the O/N2 ratio. On the night of 30 September-01 October, ionospheric plasma bubbles were observed at equatorial, low- and mid- latitude stations in the South American sector, possibly associated with the occurrence of geomagnetic storm.

  11. African horse sickness.

    PubMed

    Zientara, S; Weyer, C T; Lecollinet, S

    2015-08-01

    African horse sickness (AHS) is a devastating disease of equids caused by an arthropod-borne virus belonging to the Reoviridae family, genus Orbivirus. It is considered a major health threat for horses in endemic areas in sub-Saharan Africa. African horse sickness virus (AHSV) repeatedly caused large epizootics in the Mediterranean region (North Africa and southern Europe in particular) as a result of trade in infected equids. The unexpected emergence of a closely related virus, the bluetongue virus, in northern Europe in 2006 has raised fears about AHSV introduction into Europe, and more specifically into AHSV-free regions that have reported the presence of AHSV vectors, e.g. Culicoides midges. North African and European countries should be prepared to face AHSV incursions in the future, especially since two AHSV serotypes (serotypes 2 and 7) have recently spread northwards to western (e.g. Senegal, Nigeria, Gambia) and eastern Africa (Ethiopia), where historically only serotype 9 had been isolated. The authors review key elements of AHS epidemiology, surveillance and prophylaxis. PMID:26601437

  12. Graphical Methods for Separating Beam and Target Fragmentation Regions

    NASA Astrophysics Data System (ADS)

    Londergan, J. T.; Mathieu, V.; Szczepaniak, A. P.; Joint Physics Analysis Center Collaboration

    2015-10-01

    For reactions involving three or more final-state particles, graphical methods can help to elucidate the dominant reaction mechanism. Van Hove introduced a longitudinal phase space plot, which categorizes reaction products in terms of their longitudinal moments. We review the construction of such plots, and show how they are useful in separating beam and target fragmentation regimes. We summarize the information that can be obtained from Van Hove plots, and use these plots to analyze reactions with three or four strongly-interacting particles in the final state. As an example, we apply these methods to simulated data for the reaction π- + p -->π- + η (η ') + p . We show how cuts in the Van Hove plot can be utilized to isolate various two-body processes that contribute to this reaction. We also show how the dominant reaction processes change with the beam energy. VM and APS supported by US DOE, Grants DE-AC05-06OR23177 and DE-FG0287-ER40365; JTL by NSF-PHY-1205019.

  13. A regional method for craniofacial reconstruction based on coordinate adjustments and a new fusion strategy.

    PubMed

    Deng, Qingqiong; Zhou, Mingquan; Wu, Zhongke; Shui, Wuyang; Ji, Yuan; Wang, Xingce; Liu, Ching Yiu Jessica; Huang, Youliang; Jiang, Haiyan

    2016-02-01

    Craniofacial reconstruction recreates a facial outlook from the cranium based on the relationship between the face and the skull to assist identification. But craniofacial structures are very complex, and this relationship is not the same in different craniofacial regions. Several regional methods have recently been proposed, these methods segmented the face and skull into regions, and the relationship of each region is then learned independently, after that, facial regions for a given skull are estimated and finally glued together to generate a face. Most of these regional methods use vertex coordinates to represent the regions, and they define a uniform coordinate system for all of the regions. Consequently, the inconsistence in the positions of regions between different individuals is not eliminated before learning the relationships between the face and skull regions, and this reduces the accuracy of the craniofacial reconstruction. In order to solve this problem, an improved regional method is proposed in this paper involving two types of coordinate adjustments. One is the global coordinate adjustment performed on the skulls and faces with the purpose to eliminate the inconsistence of position and pose of the heads; the other is the local coordinate adjustment performed on the skull and face regions with the purpose to eliminate the inconsistence of position of these regions. After these two coordinate adjustments, partial least squares regression (PLSR) is used to estimate the relationship between the face region and the skull region. In order to obtain a more accurate reconstruction, a new fusion strategy is also proposed in the paper to maintain the reconstructed feature regions when gluing the facial regions together. This is based on the observation that the feature regions usually have less reconstruction errors compared to rest of the face. The results demonstrate that the coordinate adjustments and the new fusion strategy can significantly improve the

  14. Spatio-temporal characteristics of the Equatorial Ionization Anomaly (EIA) in the East African region via ionospheric tomography during the year 2012

    NASA Astrophysics Data System (ADS)

    Kassa, T.; Damtie, B.; Bires, A.; Yizengaw, E.; Cilliers, P.

    2015-01-01

    We present the characteristics of the EIA in the East African sector inferred from ground-based GPS receivers via ionospheric tomography during the year 2012. For the analysis, we developed and used a 2D ionospheric tomography imaging software based on Bayesian inversion approach. To reconstruct ionospheric electron density form slant Total Electron Content (sTEC) measurements, we selected a chain of ten ground-based GPS receivers with stations' codes and geomagnetic coordinates: ARMI (3.03 °S, 109.29 °E), DEBK (4.32 °N, 109.48 °E), ASOS (1.14 °N, 106.16 °E), NEGE (3.60 °S, 111.35 °E), SHIS (3.26 °N, 110.62 °E), ASAB (4.91 °N, 114.34 °E), SHEB (7.36 °N, 110.60 °E), EBBE (9.54 °S, 104.10 °E), DODM (16.03 °S, 109.04 °E) & NAMA (11.49 °N, 113.60 °E). The temporal, spatial and storm-time characteristics of the EIA and the hourly, day-to-day and seasonal variations of the maximum electron density of F2 region (NmF2) at 15.29°S geomagnetic latitude are presented. We found that the magnitude of the peak and the width/thickness of the EIA pronounced during the equinox and weakened during the solstice seasons at 2100 LT. It is also observed that the EIA persisted for longer time in equinox season than the solstice season. The spatial appearance of the northern and southern anomalies are observed starting from 6.12 ° N and 10 ° S respectively along geomagnetic latitude during equinox season. The EIA is localized between 180 km and 450 km along the altitude during December solstice. The analysis on the NmF2 demonstrated a significant dependence on local time, day and season of the year. We also investigated the storm response of the EIA for the magnetic storm of Day Of the Year (DOY) 274-276. It is observed that the disturbance dynamo related composition change (O/N2 ratio) resulted in a well-developed EIA with an increase in the peak and the width of the EIA at 2100 LT on DOY 275 (main phase of the storm) compared to 274 (initial phase of the storm

  15. An Analysis of Children's Drawings of What They Think Is inside Their Bodies: A South African Regional Study

    ERIC Educational Resources Information Center

    Dempster, Edith; Stears, Michèle

    2014-01-01

    The purpose of the study is to find out what a group of seven-year-old South African children understand of their internal anatomy. The research is based on the premise that young children obtain most of their science knowledge through personal experience. Drawings are used to determine the level of young children's knowledge of systems and…

  16. Technical Education and Vocational Training in Central Africa. Feasibility Survey of the Regional Development of Rapid Vocational Training: Cameroon, Central African Republic, Chad, and Gabon.

    ERIC Educational Resources Information Center

    Organization for Rehabilitation through Training, Geneva (Switzerland).

    This final report is the result of a survey requested by the United States Agency for International Development (USAID) and undertaken by the Organization for Rehabilitation through Training (ORT) of four countries (Cameroon, Chad, Central African Republic, and Gabon) and a conference on vocational training sponsored by the Economic and Customs…

  17. 9 CFR 94.8 - Pork and pork products from regions where African swine fever exists or is reasonably believed to...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ....) and regulations thereunder (9 CFR, chapter III, part 327), including requirements that the pork or...) Editorial Note: For Federal Register citations affecting § 94.8, see the List of CFR Sections Affected... where African swine fever exists or is reasonably believed to exist. 94.8 Section 94.8 Animals...

  18. 9 CFR 94.8 - Pork and pork products from regions where African swine fever exists or is reasonably believed to...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ....) and regulations thereunder (9 CFR, chapter III, part 327), including requirements that the pork or...) Editorial Note: For Federal Register citations affecting § 94.8, see the List of CFR Sections Affected... where African swine fever exists or is reasonably believed to exist. 94.8 Section 94.8 Animals...

  19. 9 CFR 94.8 - Pork and pork products from regions where African swine fever exists or is reasonably believed to...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ....C. 601 et seq.) and regulations thereunder (9 CFR, chapter III, part 327), including requirements... number 0579-0015) Editorial Note: For Federal Register citations affecting § 94.8, see the List of CFR... where African swine fever exists or is reasonably believed to exist. 94.8 Section 94.8 Animals...

  20. 9 CFR 94.8 - Pork and pork products from regions where African swine fever exists or is reasonably believed to...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ....) and regulations thereunder (9 CFR, chapter III, part 327), including requirements that the pork or...) Editorial Note: For Federal Register citations affecting § 94.8, see the List of CFR Sections Affected... where African swine fever exists or is reasonably believed to exist. 94.8 Section 94.8 Animals...

  1. 9 CFR 94.8 - Pork and pork products from regions where African swine fever exists or is reasonably believed to...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....) and regulations thereunder (9 CFR, chapter III, part 327), including requirements that the pork or...) Editorial Note: For Federal Register citations affecting § 94.8, see the List of CFR Sections Affected... where African swine fever exists or is reasonably believed to exist. 94.8 Section 94.8 Animals...

  2. Obesity and African Americans

    MedlinePlus

    ... 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 ...

  3. Hybrid region merging method for segmentation of high-resolution remote sensing images

    NASA Astrophysics Data System (ADS)

    Zhang, Xueliang; Xiao, Pengfeng; Feng, Xuezhi; Wang, Jiangeng; Wang, Zuo

    2014-12-01

    Image segmentation remains a challenging problem for object-based image analysis. In this paper, a hybrid region merging (HRM) method is proposed to segment high-resolution remote sensing images. HRM integrates the advantages of global-oriented and local-oriented region merging strategies into a unified framework. The globally most-similar pair of regions is used to determine the starting point of a growing region, which provides an elegant way to avoid the problem of starting point assignment and to enhance the optimization ability for local-oriented region merging. During the region growing procedure, the merging iterations are constrained within the local vicinity, so that the segmentation is accelerated and can reflect the local context, as compared with the global-oriented method. A set of high-resolution remote sensing images is used to test the effectiveness of the HRM method, and three region-based remote sensing image segmentation methods are adopted for comparison, including the hierarchical stepwise optimization (HSWO) method, the local-mutual best region merging (LMM) method, and the multiresolution segmentation (MRS) method embedded in eCognition Developer software. Both the supervised evaluation and visual assessment show that HRM performs better than HSWO and LMM by combining both their advantages. The segmentation results of HRM and MRS are visually comparable, but HRM can describe objects as single regions better than MRS, and the supervised and unsupervised evaluation results further prove the superiority of HRM.

  4. Structural analysis of the 5 prime flanking region of the. beta. -globin gene in African sickle cell anemia patients: Further evidence for three origins of the sickle cell mutation in Africa

    SciTech Connect

    Chebloune, Y.; Pagnier, J.; Trabuchet, G.; Faure, C.; Verdier, G.; Labie, D.; Nigon, V. )

    1988-06-01

    Haplotype analysis of the {beta}-globin gene cluster shows two regions of DNA characterized by nonrandom association of restriction site polymorphisms. These regions are separated by a variable segment containing the repeated sequences (ATTTT){sub n} and (AT){sub x}T{sub y}, which might be involved in recombinational events. Studies of haplotypes linked to the sickle cell gene in Africa provide strong argument for three origins of the mutation: Benin, Senegal, and the Central African Republic. The structure of the variable segment in the three African populations was studied by S1 nuclease mapping of genomic DNA, which allows a comparison of several samples. A 1080-base-pair DNA segment was sequenced for one sample from each population. S1 nuclease mapping confirmed the homogeneity of each population with regard to both (ATTTT){sub n} and (AT){sub x}T{sub y} repeats. The authors found three additional structures for (AT){sub x}T{sub y} correlating with the geographic origin of the patients. Ten other nucleotide positions, 5{prime} and 3{prime} to the (AT){sub x}T{sub y} copies, were found to be variable when compared to homologous sequences from human and monkey DNAs. These results allow us to propose an evolutionary scheme for the polymorphisms in the 5{prime} flanking region of the {beta}-globin gene. The results strongly support the hypothesis of three origins for the sickle mutation in Africa.

  5. A General Method to Estimate Earthquake Moment and Magnitude using Regional Phase Amplitudes

    SciTech Connect

    Pasyanos, M E

    2009-11-19

    This paper presents a general method of estimating earthquake magnitude using regional phase amplitudes, called regional M{sub o} or regional M{sub w}. Conceptually, this method uses an earthquake source model along with an attenuation model and geometrical spreading which accounts for the propagation to utilize regional phase amplitudes of any phase and frequency. Amplitudes are corrected to yield a source term from which one can estimate the seismic moment. Moment magnitudes can then be reliably determined with sets of observed phase amplitudes rather than predetermined ones, and afterwards averaged to robustly determine this parameter. We first examine in detail several events to demonstrate the methodology. We then look at various ensembles of phases and frequencies, and compare results to existing regional methods. We find regional M{sub o} to be a stable estimator of earthquake size that has several advantages over other methods. Because of its versatility, it is applicable to many more events, particularly smaller events. We make moment estimates for earthquakes ranging from magnitude 2 to as large as 7. Even with diverse input amplitude sources, we find magnitude estimates to be more robust than typical magnitudes and existing regional methods and might be tuned further to improve upon them. The method yields a more meaningful quantity of seismic moment, which can be recast as M{sub w}. Lastly, it is applied here to the Middle East region using an existing calibration model, but it would be easy to transport to any region with suitable attenuation calibration.

  6. A comparative evaluation of PCR- based methods for species- specific determination of African animal trypanosomes in Ugandan cattle

    PubMed Central

    2013-01-01

    Background In recent years, PCR has been become widely applied for the detection of trypanosomes overcoming many of the constraints of parasitological and serological techniques, being highly sensitive and specific for trypanosome detection. Individual species-specific multi-copy trypanosome DNA sequences can be targeted to identify parasites. Highly conserved ribosomal RNA (rRNA) genes are also useful for comparisons between closely related species. The internal transcribed spacer regions (ITS) in particular are relatively small, show variability among related species and are flanked by highly conserved segments to which PCR primers can be designed. Individual variations in inter-species length makes the ITS region a useful marker for identification of multiple trypanosome species within a sample. Methods Six hundred blood samples from cattle collected in Uganda on FTA cards were screened using individual species-specific primers for Trypanosoma congolense, Trypanosoma brucei and Trypanosoma vivax and compared to a modified (using eluate extracted using chelex) ITS-PCR reaction. Results The comparative analysis showed that the species-specific primer sets showed poor agreement with the ITS primer set. Using species-specific PCR for Trypanozoon, a prevalence of 10.5% was observed as compared to 0.2% using ITS PCR (Kappa = 0.03). For Trypanosoma congolense, the species-specific PCR reaction indicated a prevalence of 0% compared to 2.2% using ITS PCR (Kappa = 0). For T. vivax, species-specific PCR detected prevalence of 5.7% compared to 2.8% for ITS PCR (Kappa = 0.29). Conclusions When selecting PCR based tools to apply to epidemiological surveys for generation of prevalence data for animal trypanosomiasis, it is recommended that species-specific primers are used, being the most sensitive diagnostic tool for screening samples to identify members of Trypanozoon (T. b. brucei s.l). While ITS primers are useful for studying the prevalence of trypanosomes

  7. A comparison of the oral and silent reading methods of standardized science test delivery on the performance level of fifth-grade African American students

    NASA Astrophysics Data System (ADS)

    Merenda, Gloria Louise

    This study compared two methods of standardized test administration, oral delivery using an audio tape and the standard silent reading by the student, on the performance level (test score) and science understanding (right answer/right reason) of urban fifth grade African American students. The effect of reading ability, special needs, and socioeconomic status were also examined as possible confounding variables. A randomized post-test only control group design was used with data for the sample (N = 106) collected from student files at two Detroit Public Schools, which included the Michigan Education Assessment Program (MEAP) reading and science scores. In addition, face-to-face interviews were completed with a small subsample to determine reasoning for selecting their answers. Six hypotheses were developed to determine if there were significant differences in science performance level and understanding in fifth grade urban African American students when the standardized science test, MEAP, Area Specific Portions, Physical Science and Earth/Space Science, were delivered orally, using the audio tape, and silently, which is the present standard delivery method. Significant differences in scores were found favoring the oral over the silent test group. A significant association was also found for reading and science MEAP scores, with students who had higher scores on the reading test achieving higher scores on the science test. Although socioeconomic status did not appear to result in differential outcomes among the students, a significant interaction was found between test administration type and socioeconomic status. The conclusion that was reached was that students who have difficulty in reading the printed material could benefit from having standardized tests administered orally (except for reading tests).

  8. Parameter estimation method and updating of regional prediction equations for ungaged sites in the desert region of California

    USGS Publications Warehouse

    Barth, Nancy A.; Veilleux, Andrea G.

    2012-01-01

    The U.S. Geological Survey (USGS) is currently updating at-site flood frequency estimates for USGS streamflow-gaging stations in the desert region of California. The at-site flood-frequency analysis is complicated by short record lengths (less than 20 years is common) and numerous zero flows/low outliers at many sites. Estimates of the three parameters (mean, standard deviation, and skew) required for fitting the log Pearson Type 3 (LP3) distribution are likely to be highly unreliable based on the limited and heavily censored at-site data. In a generalization of the recommendations in Bulletin 17B, a regional analysis was used to develop regional estimates of all three parameters (mean, standard deviation, and skew) of the LP3 distribution. A regional skew value of zero from a previously published report was used with a new estimated mean squared error (MSE) of 0.20. A weighted least squares (WLS) regression method was used to develop both a regional standard deviation and a mean model based on annual peak-discharge data for 33 USGS stations throughout California’s desert region. At-site standard deviation and mean values were determined by using an expected moments algorithm (EMA) method for fitting the LP3 distribution to the logarithms of annual peak-discharge data. Additionally, a multiple Grubbs-Beck (MGB) test, a generalization of the test recommended in Bulletin 17B, was used for detecting multiple potentially influential low outliers in a flood series. The WLS regression found that no basin characteristics could explain the variability of standard deviation. Consequently, a constant regional standard deviation model was selected, resulting in a log-space value of 0.91 with a MSE of 0.03 log units. Yet drainage area was found to be statistically significant at explaining the site-to-site variability in mean. The linear WLS regional mean model based on drainage area had a Pseudo- 2 R of 51 percent and a MSE of 0.32 log units. The regional parameter

  9. African Outreach Workshop 1974.

    ERIC Educational Resources Information Center

    Schmidt, Nancy J.

    This report discusses the 1974 African Outreach Workshop planned and coordinated by the African Studies Program at the University of Illinois at Urbana-Champaign. Its major aim was to assist teachers in developing curriculum units on African using materials available in their local community. A second aim was for the African Studies Program to…

  10. Using a Mixed Methods Sequential Design to Identify Factors Associated with African American Mothers' Intention to Vaccinate Their Daughters Aged 9 to 12 for HPV with a Purpose of Informing a Culturally-Relevant, Theory-Based Intervention

    ERIC Educational Resources Information Center

    Cunningham, Jennifer L.

    2013-01-01

    The purpose of this sequential, explanatory mixed methods research study was to understand what factors influenced African American maternal intentions to get their daughters aged 9 years to 12 years vaccinated in Alabama. In the first, quantitative phase of the study, the research questions focused on identifying the predictive power of eleven…

  11. The relative contribution of viral and bacterial sexually transmitted infections on HIV acquisition in southern African women in the Methods for Improving Reproductive Health in Africa study.

    PubMed

    Venkatesh, K K; van der Straten, A; Cheng, H; Montgomery, E T; Lurie, M N; Chipato, T; Ramjee, G; Blanchard, K; Padian, N S; Mayer, K H; de Bruyn, G

    2011-04-01

    We assess the relative contribution of viral and bacterial sexually transmitted infections (STIs) on HIV acquisition among southern African women in a nested case-control study within the Methods for Improving Reproductive Health in Africa (MIRA) trial. Cases were women with incident HIV infection; controls were HIV-uninfected at the time of case seroconversion selected in a 1 to 3 case to control ratio (risk-set sampling), matched on study site and time of follow-up. Conditional logistic regression models were used to calculate adjusted odds ratios (AORs) and population-attributable fractions (PAF). Among 4948 enrolled women, we analysed 309 cases and 927 controls. The overall HIV incidence rate was 4.0 per 100 women-years. The incidence of HIV infection was markedly higher in women who had prevalent Herpes simplex virus type 2 (HSV-2) (AOR: 2.14; 95% confidence interval [CI]: 1.55-2.96), incident HSV-2 (AOR: 4.43; 95% CI: 1.77-11.05) and incident Neisseria gonorrhoeae (AOR: 6.92; 95% CI: 3.01-15.90). The adjusted PAF of HIV incidence for prevalent HSV-2 was 29.0% (95% CI: 16.8-39.3), for incident HSV-2 2.1% (95% CI: 0.6-3.6) and for incident N. gonorrhoeae 4.1% (95% CI: 2.5-5.8). Women's greatest risk factors for HIV acquisition were incident bacterial and viral STIs. Women-centred interventions aimed at decreasing HIV incidence in young African women need to address these common co-morbid conditions. PMID:21515755

  12. The Nurturant Fathering Scale: A Confirmatory Factor Analysis with an African American Sample of College Students

    ERIC Educational Resources Information Center

    Doyle, Otima; Pecukonis, Edward; Harrington, Donna

    2011-01-01

    Objective: The objective of this study was to test the factor structure of the "Nurturant Fathering Scale" (NFS) among an African American sample in the mid-Atlantic region that have neither Caribbean heritage nor immigration experiences but who do have diverse family structures (N = 212). Method: A confirmatory factor analysis (CFA) was conducted…

  13. A Connectivity-Based Eco-Regionalization Method of the Mediterranean Sea

    PubMed Central

    Berline, Léo; Rammou, Anna-Maria; Doglioli, Andrea; Molcard, Anne; Petrenko, Anne

    2014-01-01

    Ecoregionalization of the ocean is a necessary step for spatial management of marine resources. Previous ecoregionalization efforts were based either on the distribution of species or on the distribution of physical and biogeochemical properties. These approaches ignore the dispersal of species by oceanic circulation that can connect regions and isolates others. This dispersal effect can be quantified through connectivity that is the probability, or time of transport between distinct regions. Here a new regionalization method based on a connectivity approach is described and applied to the Mediterranean Sea. This method is based on an ensemble of Lagrangian particle numerical simulations using ocean model outputs at 1/12° resolution. The domain is divided into square subregions of 50 km size. Then particle trajectories are used to quantify the oceanographic distance between each subregions, here defined as the mean connection time. Finally the oceanographic distance matrix is used as a basis for a hierarchical clustering. 22 regions are retained and discussed together with a quantification of the stability of boundaries between regions. Identified regions are generally consistent with the general circulation with boundaries located along current jets or surrounding gyres patterns. Regions are discussed in the light of existing ecoregionalizations and available knowledge on plankton distributions. This objective method complements static regionalization approaches based on the environmental niche concept and can be applied to any oceanic region at any scale. PMID:25375212

  14. Evolution of the primate beta-globin gene region: nucleotide sequence of the delta-beta-globin intergenic region of gorilla and phylogenetic relationships between African apes and man.

    PubMed

    Perrin-Pecontal, P; Gouy, M; Nigon, V M; Trabuchet, G

    1992-01-01

    A 6.0-kb DNA fragment from Gorilla gorilla including the 5' part of the beta-globin gene and about 4.5 kb of its upstream flanking region was cloned and sequenced. The sequence was compared to the human, chimpanzee, and macaque delta-beta intergenic region. This analysis reveals four tandemly repeated sequences (RS), at the same location in the four species, showing a variable number of repeats generating both intraspecific (polymorphism) and interspecific variability. These tandem arrays delimit five regions of unique sequence called IG for intergenic. The divergence for these IG sequences is 1.85 +/- 0.22% between human and gorilla, which is not significantly different from the value estimated in the same region between chimpanzee and human (1.62 +/- 0.21%). The CpG and TpA dinucleotides are avoided. CpGs evolve faster than other sequence sites but do not confuse phylogenetic inferences by producing parallel mutations in different lineages. About 75% of CpG doublets have become TpG or CpA since the common ancestor, in agreement with the methylation/deamination pattern. Comparison of this intergenic region gives information on branching order within Hominoidea. Parsimony and distance-based methods when applied to the delta-beta intergenic region provide evidence (although not statistically significant) that human and chimpanzee are more closely related to each other than to gorilla. CpG sites are indeed rich in information by carrying substitutions along the short internal branch. Combining these results with those on the psi eta-delta intergenic region, shows in a statistically significant way that chimpanzee is the closest relative of human. PMID:1556740

  15. Detection of a novel recombinant strain of norovirus in an African-descendant community from the Amazon region of Brazil in 2008.

    PubMed

    Fumian, Tulio M; Aragão, Glicélia C; Mascarenhas, Joana D'Arc P; Kaiano, Jane H; Siqueira, Jones Anderson M; Soares, Luana S; Linhares, Alexandre C; Gabbay, Yvone B

    2012-12-01

    Noroviruses, a major cause of acute gastroenteritis outbreaks worldwide, are constantly evolving. This ability is reflected in the speed and efficiency with which these viruses spread and remain in the human population. The present study reports the detection of a novel recombination event among norovirus genotypes in Brazil in 2008. A strain detected in a stool sample from a child with norovirus-associated gastroenteritis, residing in an African-descendant semi-closed community of Pará State, was characterized as a novel intergenotype recombinant, GII.7/GII.20, as determined by partial sequencing and SimPlot analysis. PMID:22872050

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

    ERIC Educational Resources Information Center

    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…

  17. Nasal aperture shape evaluation between black and white South Africans.

    PubMed

    McDowell, Jennifer L; L'Abbé, Ericka N; Kenyhercz, Michael W

    2012-10-10

    The purpose of this study was to combine morphoscopic and metric analyses to assess variation in nasal aperture size and shape of black and white South Africans. Thirteen landmarks were digitized from the bony nasal region of 152 crania using an electromechanic instrument for geometric morphometric (general procrustes analysis) and craniometric analyses. Elliptical Fourier analysis was used to assess shape of the nasal aperture via outlines applied through photographs. Both principal component and discriminant function analyses were applied to these statistical methods. Black South Africans were classified 95-96% correctly and white South Africans were classified 91-94% correctly. In a four-way analysis of sex and ancestry, classification accuracy ranged from 56 to 70%. Most misclassifications were between the sexes within each group which suggests an absence of sexual dimorphism. This study found that there is quantifiable variation in shape of the nasal aperture between black and white South African groups using all three statistical methods. In forensic application, standard craniometrics can be used to accurately classify an unknown person. PMID:22727267

  18. West African crude production diversifies

    SciTech Connect

    Aalund, L.

    1983-06-01

    Nigeria, with its seven crude-oil export streams, dominated West African production and accounted for over 70% of the depressed 1.8 million b/d output from the region last year. However, during the 1970s a flurry of new producing fields, primarily off the African coast, diversified production among a number of countries and touched off a wave of oil activity. The Journal takes a close look at the quality of West African oil in this installment of assays on world export crudes. This issue covers, in alphabetical order, Bonny Light (Nigeria) to Espoir (Ivory Coast). A following issue will wrap up West Africa by presenting assays on crudes from Forcados Blend (Nigeria) to Zaire Crude (Zaire).

  19. An adaptive subspace trust-region method for frequency-domain seismic full waveform inversion

    NASA Astrophysics Data System (ADS)

    Zhang, Huan; Li, Xiaofan; Song, Hanjie; Liu, Shaolin

    2015-05-01

    Full waveform inversion is currently considered as a promising seismic imaging method to obtain high-resolution and quantitative images of the subsurface. It is a nonlinear ill-posed inverse problem, the main difficulty of which that prevents the full waveform inversion from widespread applying to real data is the sensitivity to incorrect initial models and noisy data. Local optimization theories including Newton's method and gradient method always lead the convergence to local minima, while global optimization algorithms such as simulated annealing are computationally costly. To confront this issue, in this paper we investigate the possibility of applying the trust-region method to the full waveform inversion problem. Different from line search methods, trust-region methods force the new trial step within a certain neighborhood of the current iterate point. Theoretically, the trust-region methods are reliable and robust, and they have very strong convergence properties. The capability of this inversion technique is tested with the synthetic Marmousi velocity model and the SEG/EAGE Salt model. Numerical examples demonstrate that the adaptive subspace trust-region method can provide solutions closer to the global minima compared to the conventional Approximate Hessian approach and the L-BFGS method with a higher convergence rate. In addition, the match between the inverted model and the true model is still excellent even when the initial model deviates far from the true model. Inversion results with noisy data also exhibit the remarkable capability of the adaptive subspace trust-region method for low signal-to-noise data inversions. Promising numerical results suggest this adaptive subspace trust-region method is suitable for full waveform inversion, as it has stronger convergence and higher convergence rate.

  20. Characteristics of African easterly waves associated with tropical cyclogenesis in the Cape Verde Islands region in July-August-September of 2004-2008

    NASA Astrophysics Data System (ADS)

    Arnault, Joël; Roux, Frank

    2011-04-01

    The most common synoptic-scale disturbances related to cyclogenesis over the tropical north Atlantic Ocean are African easterly waves (AEWs) that originated from the northern African continent. However, most of these waves do not evolve in tropical depressions, storms, or hurricanes. The reasons why only few AEWs develop and the necessary conditions for cyclogenetic evolution are still the subject of intense debate. Tropical cyclogenesis occurring near the Cape Verde Islands in the eastern tropical Atlantic is investigated here with five seasons (July-August-September of 2004-2008) of European Centre for Medium-Range Weather Forecasts analyses, Meteosat-9 images, and National Hurricane Center (National Oceanic and Atmospheric Administration, National Centers for Environmental Prediction) "best track" archives. The nine named storms that first reached tropical depression intensity east of 30°W, and two among six which developed between 30 and 40°W, during these five years evolved from intense AEW troughs, associated with low-level cyclonic circulation, weak mid-level anticyclonic Saharan flow to the east, and deep convection near the center of cyclonic vorticity. The cyclogenetic evolution of three AEW troughs, which verified these conditions but failed to develop into named storms, was probably inhibited by unusually dry environment and strong vertical wind shear. The fate of other AEW troughs, which did not satisfy the necessary conditions, is also discussed.

  1. HLA-E coding and 3' untranslated region variability determined by next-generation sequencing in two West-African population samples.

    PubMed

    Castelli, Erick C; Mendes-Junior, Celso T; Sabbagh, Audrey; Porto, Iane O P; Garcia, André; Ramalho, Jaqueline; Lima, Thálitta H A; Massaro, Juliana D; Dias, Fabrício C; Collares, Cristhianna V A; Jamonneau, Vincent; Bucheton, Bruno; Camara, Mamadou; Donadi, Eduardo A

    2015-12-01

    HLA-E is a non-classical Human Leucocyte Antigen class I gene with immunomodulatory properties. Whereas HLA-E expression usually occurs at low levels, it is widely distributed amongst human tissues, has the ability to bind self and non-self antigens and to interact with NK cells and T lymphocytes, being important for immunosurveillance and also for fighting against infections. HLA-E is usually the most conserved locus among all class I genes. However, most of the previous studies evaluating HLA-E variability sequenced only a few exons or genotyped known polymorphisms. Here we report a strategy to evaluate HLA-E variability by next-generation sequencing (NGS) that might be used to other HLA loci and present the HLA-E haplotype diversity considering the segment encoding the entire HLA-E mRNA (including 5'UTR, introns and the 3'UTR) in two African population samples, Susu from Guinea-Conakry and Lobi from Burkina Faso. Our results indicate that (a) the HLA-E gene is indeed conserved, encoding mainly two different protein molecules; (b) Africans do present several unknown HLA-E alleles presenting synonymous mutations; (c) the HLA-E 3'UTR is quite polymorphic and (d) haplotypes in the HLA-E 3'UTR are in close association with HLA-E coding alleles. NGS has proved to be an important tool on data generation for future studies evaluating variability in non-classical MHC genes. PMID:26187162

  2. Speed-up matching method with navigation data for UAV remote sensing images of coastal region

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Jiang, Gangwu; Di, Yanan

    2015-08-01

    UAV remote sensing platform can obtain images of target regions quickly. It has distinct advantages in the detection of oil spill, the emergency response of searching and rescuing, the survey of coastal regions, etc. However, the existing UAV images are difficult to meet the needs of rapid processing, because the amount of their data is too large and the traditional processing methods take too much time in the matching stage. This paper designs a speed-up matching algorithm which utilizes navigation data in UAV to get the elements of exterior orientation. The algorithm is based on the collinearity equation with the flat terrain in the coastal regions. Those elements can be used to compute the original homography matrix and overlapping regions. After extracting interest points by SURF algorithm, the matching method only chooses some points in overlapping regions for matching stage. The algorithm can improve the matching speed , and also can decrease mismatching to improve the accuracy.

  3. An Improved Anchor Shot Detection Method Using Fitness of Face Location and Dissimilarity of Icon Region

    NASA Astrophysics Data System (ADS)

    Keum, Ji-Soo; Lee, Hyon-Soo; Hagiwara, Masafumi

    In this letter, we propose an improved anchor shot detection (ASD) method in order to effectively retrieve anchor shots from news video. The face location and dissimilarity of icon region are used to reduce false alarms in the proposed method. According to the results of the experiment on several types of news video, the proposed method obtained high anchor detection results compared with previous methods.

  4. On evaluating the robustness of spatial-proximity-based regionalization methods

    NASA Astrophysics Data System (ADS)

    Lebecherel, Laure; Andréassian, Vazken; Perrin, Charles

    2016-08-01

    In absence of streamflow data to calibrate a hydrological model, its parameters are to be inferred by a regionalization method. In this technical note, we discuss a specific class of regionalization methods, those based on spatial proximity, which transfers hydrological information (typically calibrated parameter sets) from neighbor gauged stations to the target ungauged station. The efficiency of any spatial-proximity-based regionalization method will depend on the density of the available streamgauging network, and the purpose of this note is to discuss how to assess the robustness of the regionalization method (i.e., its resilience to an increasingly sparse hydrometric network). We compare two options: (i) the random hydrometrical reduction (HRand) method, which consists in sub-sampling the existing gauging network around the target ungauged station, and (ii) the hydrometrical desert method (HDes), which consists in ignoring the closest gauged stations. Our tests suggest that the HDes method should be preferred, because it provides a more realistic view on regionalization performance.

  5. Digital Sequences and a Time Reversal-Based Impact Region Imaging and Localization Method

    PubMed Central

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-01-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half. PMID:24084123

  6. Digital sequences and a time reversal-based impact region imaging and localization method.

    PubMed

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-01-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half. PMID:24084123

  7. Barriers to Hospice Use among African Americans: A Systematic Review

    ERIC Educational Resources Information Center

    Washington, Karla T.; Bickel-Swenson, Denise; Stephens, Nathan

    2008-01-01

    The present review was undertaken to explore recent evidence in the professional literature pertaining to use of hospice services by African Americans. The article addresses the research methods that have been used to study African American hospice use, obstacles to African American participation in hospice that have been identified, and…

  8. Oral Cancer in African Americans: Addressing Health Disparities

    ERIC Educational Resources Information Center

    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…

  9. A method for detecting IBD regions simultaneously in multiple individuals--with applications to disease genetics.

    PubMed

    Moltke, Ida; Albrechtsen, Anders; Hansen, Thomas V O; Nielsen, Finn C; Nielsen, Rasmus

    2011-07-01

    All individuals in a finite population are related if traced back long enough and will, therefore, share regions of their genomes identical by descent (IBD). Detection of such regions has several important applications-from answering questions about human evolution to locating regions in the human genome containing disease-causing variants. However, IBD regions can be difficult to detect, especially in the common case where no pedigree information is available. In particular, all existing non-pedigree based methods can only infer IBD sharing between two individuals. Here, we present a new Markov Chain Monte Carlo method for detection of IBD regions, which does not rely on any pedigree information. It is based on a probabilistic model applicable to unphased SNP data. It can take inbreeding, allele frequencies, genotyping errors, and genomic distances into account. And most importantly, it can simultaneously infer IBD sharing among multiple individuals. Through simulations, we show that the simultaneous modeling of multiple individuals makes the method more powerful and accurate than several other non-pedigree based methods. We illustrate the potential of the method by applying it to data from individuals with breast and/or ovarian cancer, and show that a known disease-causing mutation can be mapped to a 2.2-Mb region using SNP data from only five seemingly unrelated affected individuals. This would not be possible using classical linkage mapping or association mapping. PMID:21493780

  10. A generic method for hydrological drought identification across different climate regions

    NASA Astrophysics Data System (ADS)

    van Huijgevoort, M. H. J.; Hazenberg, P.; van Lanen, H. A. J.; Uijlenhoet, R.

    2012-02-01

    The identification of hydrological drought at global scale has received considerable attention during the last decade. However, climate-induced variation in runoff across the world makes such analyses rather complicated. This especially holds for the drier regions of the world (both cold and warm), where for a considerable period of time, zero runoff can be observed. In the current paper, we present a method that enables to identify drought at global scale across climate regimes in a consistent manner. The method combines the characteristics of the classical variable threshold level method that is best applicable in regions with non zero runoff most of the time, and the consecutive dry days (period) method that is better suited for areas where zero runoff occurs. The newly presented method allows a drought in periods with runoff to continue in the following period without runoff. The method was demonstrated by identifying droughts from discharge observations of four rivers situated within different climate regimes, as well as from simulated runoff data at global scale obtained from an ensemble of five different land surface models. The identified drought events obtained by the new approach were compared to those resulting from application of the variable threshold level method or the consecutive dry period method separately. Results show that, in general, for drier regions, the threshold level method overestimates drought duration, because zero runoff periods were included in a drought, according to the definition used within this method. The consecutive dry period method underestimates drought occurrence, since it cannot identify droughts for periods with runoff. The developed method especially shows its relevance in transitional areas, because in wetter regions, results were identical to the classical threshold level method. By combining both methods, the new method is able to identify single drought events that occur during positive and zero runoff periods

  11. A generic method for hydrological drought identification across different climate regions

    NASA Astrophysics Data System (ADS)

    van Huijgevoort, M. H. J.; Hazenberg, P.; van Lanen, H. A. J.; Uijlenhoet, R.

    2012-08-01

    The identification of hydrological drought at global scale has received considerable attention during the last decade. However, climate-induced variation in runoff across the world makes such analyses rather complicated. This especially holds for the drier regions of the world (both cold and warm), where, for a considerable period of time, zero runoff can be observed. In the current paper, we present a method that enables to identify drought at global scale across climate regimes in a consistent manner. The method combines the characteristics of the classical variable threshold level method that is best applicable in regions with non-zero runoff most of the time, and the consecutive dry days (period) method that is better suited for areas where zero runoff occurs. The newly presented method allows a drought in periods with runoff to continue in the following period without runoff. The method is demonstrated by identifying droughts from discharge observations of four rivers situated within different climate regimes, as well as from simulated runoff data at global scale obtained from an ensemble of five different land surface models. The identified drought events obtained by the new approach are compared to those resulting from application of the variable threshold level method or the consecutive dry period method separately. Results show that, in general, for drier regions, the threshold level method overestimates drought duration, because zero runoff periods are included in a drought, according to the definition used within this method. The consecutive dry period method underestimates drought occurrence, since it cannot identify droughts for periods with runoff. The developed method especially shows its relevance in transitional areas, because, in wetter regions, results are identical to the classical threshold level method. By combining both methods, the new method is able to identify single drought events that occur during positive and zero runoff periods

  12. Cardiovascular disease, diabetes and established risk factors among populations of sub-Saharan African descent in Europe: a literature review

    PubMed Central

    Agyemang, Charles; Addo, Juliet; Bhopal, Raj; de Graft Aikins, Ama; Stronks, Karien

    2009-01-01

    Background Most European countries are ethnically and culturally diverse. Globally, cardiovascular disease (CVD) is the leading cause of death. The major risk factors for CVD have been well established. This picture holds true for all regions of the world and in different ethnic groups. However, the prevalence of CVD and related risk factors vary among ethnic groups. Methods This article provides a review of current understanding of the epidemiology of vascular disease, principally coronary heart disease (CHD), stroke and related risk factors among populations of Sub-Sahara African descent (henceforth, African descent) in comparison with the European populations in Europe. Results Compared with European populations, populations of African descent have an increased risk of stroke, whereas CHD is less common. They also have higher rates of hypertension and diabetes than European populations. Obesity is highly prevalent, but smoking rate is lower among African descent women. Older people of African descent have more favourable lipid profile and dietary habits than their European counterparts. Alcohol consumption is less common among populations of African descent. The rate of physical activity differs between European countries. Dutch African-Suriname men and women are less physically active than the White-Dutch whereas British African women are more physically active than women in the general population. Literature on psychosocial stress shows inconsistent results. Conclusion Hypertension and diabetes are highly prevalent among African populations, which may explain their high rate of stroke in Europe. The relatively low rate of CHD may be explained by the low rates of other risk factors including a more favourable lipid profile and the low prevalence of smoking. The risk factors are changing, and on the whole, getting worse especially among African women. Cohort studies and clinical trials are therefore needed among these groups to determine the relative

  13. Increasing the value of health research in the WHO African Region beyond 2015—reflecting on the past, celebrating the present and building the future: a bibliometric analysis

    PubMed Central

    Uthman, Olalekan A; Wiysonge, Charles Shey; Ota, Martin O; Nicol, Mark; Hussey, Gregory D; Ndumbe, Peter M; Mayosi, Bongani M

    2015-01-01

    Objective To assess the profile and determinants of health research productivity in Africa since the onset of the new millennium. Design Bibliometric analysis. Data collection and synthesis In November 2014, we searched PubMed for articles published between 2000 and 2014 from the WHO African Region, and obtained country-level indicators from World Bank data. We used Poisson regression to examine time trends in research publications and negative binomial regression to explore determinants of research publications. Results We identified 107 662 publications, with a median of 727 per country (range 25–31 757). Three countries (South Africa, Nigeria and Kenya) contributed 52% of the publications. The number of publications increased from 3623 in 2000 to 12 709 in 2014 (relative growth 251%). Similarly, the per cent share of worldwide research publications per year increased from 0.7% in 2000 to 1.3% in 2014. The trend analysis was also significant to confirm a continuous increase in health research publications from Africa, with productivity increasing by 10.3% per year (95% CIs +10.1% to +10.5%). The only independent predictor of publication outputs was national gross domestic product. For every one log US$ billion increase in gross domestic product, research publications rose by 105%: incidence rate ratio (IRR=2.05, 95% CI 1.39 to 3.04). The association of private health expenditure with publications was only marginally significant (IRR=1.86, 95% CI 1.00 to 3.47). Conclusions There has been a significant improvement in health research in the WHO African Region since 2000, with some individual countries already having strong research profiles. Countries of the region should implement the WHO Strategy on Research for Health: reinforcing the research culture (organisation); focusing research on key health challenges (priorities); strengthening national health research systems (capacity); encouraging good research practice (standards); and consolidating linkages

  14. Double tracer autoradiographic method for sequential evaluation of regional cerebral perfusion

    SciTech Connect

    Matsuda, H.; Tsuji, S.; Oba, H.; Kinuya, K.; Terada, H.; Sumiya, H.; Shiba, K.; Mori, H.; Hisada, K.; Maeda, T. )

    1989-01-01

    A new double tracer autoradiographic method for the sequential evaluation of altered regional cerebral perfusion in the same animal is presented. This method is based on the sequential injection of two tracers, {sup 99m}Tc-hexamethylpropyleneamine oxime and N-isopropyl-({sup 125}I)p-iodoamphetamine. This method is validated in the assessment of brovincamine effects on regional cerebral perfusion in an experimental model of chronic brain ischemia in the rat. The drug enhanced perfusion recovery in low-flow areas, selectively in surrounding areas of infarction. The results suggest that this technique is of potential use in the study of neuropharmacological effects applied during the experiment.

  15. Research on electrocardiogram baseline wandering correction based on wavelet transform, QRS barycenter fitting, and regional method.

    PubMed

    Song, Jinzhong; Yan, Hong; Li, Yanjun; Mu, Kaiyu

    2010-09-01

    Baseline wandering in electrocardiogram (ECG) is one of the biggest interferences in visualization and computerized detection of waveforms (especially ST-segment) based on threshold decision. A new method based on wavelet transform, QRS barycenter fitting and regional method was proposed in this paper. Firstly, wavelet transform as a coarse correction was used to remove the baseline wandering, whose frequency bands were non-overlapping with that of ST-segment. Secondly, QRS barycenter fitting was applied as a detailed correction. The third, the regional method was used to transfer baseline to zero. Finally, the method in this paper was proved to perform better than filtering and function fitting methods in baseline wandering correction after the long-term ST database (LTST) verification. In addition, the proposed method is simple and easy to carry out, and in current use. PMID:20882381

  16. Assessment of geothermal energy potential by geophysical methods: Nevşehir Region, Central Anatolia

    NASA Astrophysics Data System (ADS)

    Kıyak, Alper; Karavul, Can; Gülen, Levent; Pekşen, Ertan; Kılıç, A. Rıza

    2015-03-01

    In this study, geothermal potential of the Nevşehir region (Central Anatolia) was assessed by using vertical electrical sounding (VES), self-potential (SP), magnetotelluric (MT), gravity and gravity 3D Euler deconvolution structure analysis methods. Extensive volcanic activity occurred in this region from Upper Miocene to Holocene time. Due to the young volcanic activity Nevşehir region can be viewed as a potential geothermal area. We collected data from 54 VES points along 5 profiles, from 28 MT measurement points along 2 profiles (at frequency range between 320 and 0.0001 Hz), and from 4 SP profiles (total 19 km long). The obtained results based on different geophysical methods are consistent with each other. Joint interpretation of all geological and geophysical data suggests that this region has geothermal potential and an exploration well validated this assessment beyond doubt.

  17. Detecting Sex-Biased Gene Flow in African-Americans through the Analysis of Intra- and Inter-Population Variation at Mitochondrial DNA and Y- Chromosome Microsatellites

    PubMed Central

    Battaggia, C; Anagnostou, P; Bosch, I; Brisighelli, F; Destro-Bisol, G; Capocasa, M

    2012-01-01

    This study reports on variations at the mitochondrial DNA (mtDNA) hypervariable region 1 (HVR-1) and at seven Y-chromosome microsatellites in an African-American population sample from Chicago, IL, USA. Our results support the hypothesis that the population studied had undergone a European male-biased gene flow. We show that comparisons of intra-and inter-population diversity parameters between African-Americans, Europeans and Africans may help detect sex-biased gene flow, providing a complement to quantitative methods to estimate genetic admixture. PMID:24052726

  18. 1-D seismic velocity model and hypocenter relocation using double difference method around West Papua region

    SciTech Connect

    Sabtaji, Agung E-mail: agung.sabtaji@bmkg.go.id; Nugraha, Andri Dian

    2015-04-24

    West Papua region has fairly high of seismicity activities due to tectonic setting and many inland faults. In addition, the region has a unique and complex tectonic conditions and this situation lead to high potency of seismic hazard in the region. The precise earthquake hypocenter location is very important, which could provide high quality of earthquake parameter information and the subsurface structure in this region to the society. We conducted 1-D P-wave velocity using earthquake data catalog from BMKG for April, 2009 up to March, 2014 around West Papua region. The obtained 1-D seismic velocity then was used as input for improving hypocenter location using double-difference method. The relocated hypocenter location shows fairly clearly the pattern of intraslab earthquake beneath New Guinea Trench (NGT). The relocated hypocenters related to the inland fault are also observed more focus in location around the fault.

  19. Rationale, Design and Methods of the Ecological Study of Sexual Behaviors and HIV/STI among African American Men Who Have Sex with Men in the Southeastern United States (The MARI Study)

    PubMed Central

    Hickson, DeMarc A.; Truong, Nhan L.; Smith-Bankhead, Neena; Sturdevant, Nikendrick; Duncan, Dustin T.; Schnorr, Jordan; Gipson, June A.; Mena, Leandro A.

    2015-01-01

    Background This paper describes the rationale, design, and methodology of the Ecological Study of Sexual Behaviors and HIV/STI among African American Men Who Have Sex with Men (MSM) in the Southeastern United States (U.S.; known locally simply as the MARI Study). Methods Participants are African American MSM aged 18 years and older residing in the deep South. Results Between 2013 and 2015, 800 African American MSM recruited from two study sites (Jackson, MS and Atlanta, GA) will undergo a 1.5-hour examination to obtain anthropometric and blood pressure measures as well as to undergo testing for sexually transmitted infections (STI), including HIV. Intrapersonal, interpersonal, and environmental factors are assessed by audio computer-assisted self-interview survey. Primary outcomes include sexual risk behaviors (e.g., condomless anal sex) and prevalent STIs (HIV, syphilis, gonorrhea, and Chlamydia). Conclusion The MARI Study will typify the HIV environmental 'riskscape' and provide empirical evidence into novel ecological correlates of HIV risk among African American MSM in the deep South, a population most heavily impacted by HIV. The study's anticipated findings will be of interest to a broad audience and lead to more informed prevention efforts, including effective policies and interventions, that achieve the goals of the updated 2020 U.S. National HIV/AIDS Strategy. PMID:26700018

  20. Numerical study of a matrix-free trust-region SQP method for equality constrained optimization.

    SciTech Connect

    Heinkenschloss, Matthias; Ridzal, Denis; Aguilo, Miguel Antonio

    2011-12-01

    This is a companion publication to the paper 'A Matrix-Free Trust-Region SQP Algorithm for Equality Constrained Optimization' [11]. In [11], we develop and analyze a trust-region sequential quadratic programming (SQP) method that supports the matrix-free (iterative, in-exact) solution of linear systems. In this report, we document the numerical behavior of the algorithm applied to a variety of equality constrained optimization problems, with constraints given by partial differential equations (PDEs).

  1. Indirect boundary element method to simulate elastic wave propagation in piecewise irregular and flat regions

    NASA Astrophysics Data System (ADS)

    Perton, Mathieu; Contreras-Zazueta, Marcial A.; Sánchez-Sesma, Francisco J.

    2016-06-01

    A new implementation of indirect boundary element method allows simulating the elastic wave propagation in complex configurations made of embedded regions that are homogeneous with irregular boundaries or flat layers. In an older implementation, each layer of a flat layered region would have been treated as a separated homogeneous region without taking into account the flat boundary information. For both types of regions, the scattered field results from fictitious sources positioned along their boundaries. For the homogeneous regions, the fictitious sources emit as in a full-space and the wave field is given by analytical Green's functions. For flat layered regions, fictitious sources emit as in an unbounded flat layered region and the wave field is given by Green's functions obtained from the discrete wavenumber (DWN) method. The new implementation allows then reducing the length of the discretized boundaries but DWN Green's functions require much more computation time than the full-space Green's functions. Several optimization steps are then implemented and commented. Validations are presented for 2-D and 3-D problems. Higher efficiency is achieved in 3-D.

  2. Intensity of play behavior as a potential measure of welfare: A novel method for quantifying the integrated intensity of behavior in African elephants.

    PubMed

    Vicino, Greg A; Marcacci, Emily S

    2015-01-01

    To the authors' knowledge there is currently no discrete index to measure the integrated intensity of a play bout in mammals, despite the potential for using intensity and duration of play bouts as a measure of physical activity and welfare. This study was developed to test an equation that quantified the intensity and duration of play bouts in a particularly gregarious mammal, African elephants (Loxodonta africana) housed at the San Diego Zoo Safari Park in Escondido, CA. To quantify these behaviors, we created a scale of intensity and a subsequent equation that produces an index value, giving each unique bout a score. A compilation of these scores provides a range of intensity of play behavior that is a representative value for that particular herd at that point in time, and thus a database to which later bouts can be compared. It can be argued that play behavior is an indicator of positive welfare, and if quantifiable, it is our belief that it can be used as an additional measure of positive welfare in zoo housed animals. Here we present the methods and technique used to calculate a standardized Integrated Play Index (IPI) that has potential for use in other socially living species that are known to exhibit play behavior. PMID:26251201

  3. “I Just Can’t Do It Anymore” Patterns of Physical Activity and Cardiac Rehabilitation in African Americans with Heart Failure: A Mixed Method Study

    PubMed Central

    McCarthy, Margaret; Katz, Stuart D.; Schipper, Judith; Dickson, Victoria Vaughan

    2015-01-01

    Physical activity and cardiac rehabilitation (CR) are components of heart failure (HF) self-care. The aims of this study were to describe patterns of physical activity in African Americans (n = 30) with HF and to explore experience in CR. This was a mixed method, concurrent nested, predominantly qualitative study. Qualitative data were collected via interviews exploring typical physical activity, and CR experience. It was augmented by quantitative data measuring HF severity, self-care, functional capacity and depressive symptoms. Mean age was 60 ± 15 years; 65% were New York Heart Association (NYHA) class III HF. Forty-three percent reported that they did less than 30 min of exercise in the past week; 23% were told “nothing” about exercise by their provider, and 53% were told to do “minimal exercise”. A measure of functional capacity indicated the ability to do moderate activity. Two related themes stemmed from the narratives describing current physical activity: “given up” and “still trying”. Six participants recalled referral to CR with one person participating. There was high concordance between qualitative and quantitative data, and evidence that depression may play a role in low levels of physical activity. Findings highlight the need for strategies to increase adherence to current physical activity guidelines in this older minority population with HF. PMID:27417807

  4. Black African Traditional Mathematics

    ERIC Educational Resources Information Center

    Zaslavsky, Claudia

    1970-01-01

    Discusses the traditional number systems and the origin of the number names used by several African peoples living south of the Sahara. Also included are limitations in African mathematical development, and possible topics for research. (RP)

  5. seqlm: an MDL based method for identifying differentially methylated regions in high density methylation array data

    PubMed Central

    Kolde, Raivo; Märtens, Kaspar; Lokk, Kaie; Laur, Sven; Vilo, Jaak

    2016-01-01

    Motivation: One of the main goals of large scale methylation studies is to detect differentially methylated loci. One way is to approach this problem sitewise, i.e. to find differentially methylated positions (DMPs). However, it has been shown that methylation is regulated in longer genomic regions. So it is more desirable to identify differentially methylated regions (DMRs) instead of DMPs. The new high coverage arrays, like Illuminas 450k platform, make it possible at a reasonable cost. Few tools exist for DMR identification from this type of data, but there is no standard approach. Results: We propose a novel method for DMR identification that detects the region boundaries according to the minimum description length (MDL) principle, essentially solving the problem of model selection. The significance of the regions is established using linear mixed models. Using both simulated and large publicly available methylation datasets, we compare seqlm performance to alternative approaches. We demonstrate that it is both more sensitive and specific than competing methods. This is achieved with minimal parameter tuning and, surprisingly, quickest running time of all the tried methods. Finally, we show that the regional differential methylation patterns identified on sparse array data are confirmed by higher resolution sequencing approaches. Availability and Implementation: The methods have been implemented in R package seqlm that is available through Github: https://github.com/raivokolde/seqlm Contact: rkolde@gmail.com Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27187204

  6. A method for estimating solid organ donor potential by organ procurement region.

    PubMed Central

    Christiansen, C L; Gortmaker, S L; Williams, J M; Beasley, C L; Brigham, L E; Capossela, C; Matthiesen, M E; Gunderson, S

    1998-01-01

    OBJECTIVES: This study sought to develop a methodology for estimating potential solid organ donors and measuring donation performance in a geographic region based on readily available data on the hospitals in that region. METHODS: Medical records were reviewed in a stratified random sample of 89 hospitals from 3 regions to attain a baseline of donor potential. Data on a range of hospital characteristics were collected and tested as predictors of donor potential through the use of hierarchical Poisson regression modeling. RESULTS: Five hospital characteristics predicted donor potential: hospital deaths, hospital Medicare case-mix index, total hospital staffed beds, medical school affiliation, and trauma center certification. Regional estimates were attained by aggregating individual hospital estimates. Confidence intervals for these regional estimates indicated that actual donations represented from 28% to 44% of the potential in the regions studied. CONCLUSIONS: This methodology accurately estimates organ donor potential within 3 geographic regions and lays the foundation for evaluating organ donation effectiveness nationwide. Additional research is needed to test the validity of the model in other geographic regions and to further explore organ donor potential in hospitals with fewer than 50 beds. PMID:9807530

  7. The African Connection

    ERIC Educational Resources Information Center

    Oguntoyinbo, Lekan

    2012-01-01

    From student and faculty exchanges to joint research projects, U.S. universities maintain a broad spectrum of collaborative relationships with African universities. It's unclear how many U.S. colleges and universities have partnerships with African universities. The African Studies Association, an organization of scholars, doesn't keep that kind…

  8. A coronary artery segmentation method based on multiscale analysis and region growing.

    PubMed

    Kerkeni, Asma; Benabdallah, Asma; Manzanera, Antoine; Bedoui, Mohamed Hedi

    2016-03-01

    Accurate coronary artery segmentation is a fundamental step in various medical imaging applications such as stenosis detection, 3D reconstruction and cardiac dynamics assessing. In this paper, a multiscale region growing (MSRG) method for coronary artery segmentation in 2D X-ray angiograms is proposed. First, a region growing rule incorporating both vesselness and direction information in a unique way is introduced. Then an iterative multiscale search based on this criterion is performed. Selected points in each step are considered as seeds for the following step. By combining vesselness and direction information in the growing rule, this method is able to avoid blockage caused by low vesselness values in vascular regions, which in turn, yields continuous vessel tree. Performing the process in a multiscale fashion helps to extract thin and peripheral vessels often missed by other segmentation methods. Quantitative evaluation performed on real angiography images shows that the proposed segmentation method identifies about 80% of the total coronary artery tree in relatively easy images and 70% in challenging cases with a mean precision of 82% and outperforms others segmentation methods in terms of sensitivity. The MSRG segmentation method was also implemented with different enhancement filters and it has been shown that the Frangi filter gives better results. The proposed segmentation method has proven to be tailored for coronary artery segmentation. It keeps an acceptable performance when dealing with challenging situations such as noise, stenosis and poor contrast. PMID:26748040

  9. A Method to Create Regional Mechanical Dyssynchrony Maps from Short-Axis Cine SSFP Images

    PubMed Central

    Suever, Jonathan D.; Fornwalt, Brandon K.; Neuman, Lee R.; Delfino, Jana G.; Lloyd, Michael S.; Oshinski, John N.

    2013-01-01

    Purpose To develop a robust method to assess regional mechanical dyssynchrony from cine short-axis MR images. Cardiac resynchronization therapy (CRT) is an effective treatment for patients with heart failure and evidence of left-ventricular (LV) dyssynchrony. Patient response to CRT is greatest when the LV pacing lead is placed in the most dyssynchronous segment. Existing techniques for assessing regional dyssynchrony require difficult acquisition and/or postprocessing. Our goal was to develop a widely applicable and robust method to assess regional mechanical dyssynchrony. Materials and Methods Using the endocardial boundary, radial displacement curves (RDCs) were generated throughout the LV. Cross-correlation was used to determine the delay time between each RDC and a patient-specific reference. Delay times were projected onto the AHA 17-segment model creating a regional dyssynchrony map. Our method was tested in 10 normal individuals and 10 patients enrolled for CRT (QRS>120ms, NYHA III-IV, EF<35%). Results Delay times over the LV were 23.9±33.8ms and 93.1±99.9ms (p<0.001) in normal subjects and patients, respectively. Inter-observer reproducibility for segment averages was 6.8±39.3ms and there was 70% agreement in identifying the latest contracting segment. Conclusion We have developed a method that can reliably calculate regional delay times from cine SSFP images. Maps of regional dyssynchrony could be used to identify the latest-contracting segment to assist in CRT lead implantation. PMID:24123528

  10. Connection method of separated luminal regions of intestine from CT volumes

    NASA Astrophysics Data System (ADS)

    Oda, Masahiro; Kitasaka, Takayuki; Furukawa, Kazuhiro; Watanabe, Osamu; Ando, Takafumi; Hirooka, Yoshiki; Goto, Hidemi; Mori, Kensaku

    2015-03-01

    This paper proposes a connection method of separated luminal regions of the intestine for Crohn's disease diagnosis. Crohn's disease is an inflammatory disease of the digestive tract. Capsule or conventional endoscopic diagnosis is performed for Crohn's disease diagnosis. However, parts of the intestines may not be observed in the endoscopic diagnosis if intestinal stenosis occurs. Endoscopes cannot pass through the stenosed parts. CT image-based diagnosis is developed as an alternative choice of the Crohn's disease. CT image-based diagnosis enables physicians to observe the entire intestines even if stenosed parts exist. CAD systems for Crohn's disease using CT volumes are recently developed. Such CAD systems need to reconstruct separated luminal regions of the intestines to analyze intestines. We propose a connection method of separated luminal regions of the intestines segmented from CT volumes. The luminal regions of the intestines are segmented from a CT volume. The centerlines of the luminal regions are calculated by using a thinning process. We enumerate all the possible sequences of the centerline segments. In this work, we newly introduce a condition using distance between connected ends points of the centerline segments. This condition eliminates unnatural connections of the centerline segments. Also, this condition reduces processing time. After generating a sequence list of the centerline segments, the correct sequence is obtained by using an evaluation function. We connect the luminal regions based on the correct sequence. Our experiments using four CT volumes showed that our method connected 6.5 out of 8.0 centerline segments per case. Processing times of the proposed method were reduced from the previous method.

  11. A robust method for handling low density regions in hybrid simulations for collisionless plasmas

    SciTech Connect

    Amano, Takanobu Higashimori, Katsuaki; Shirakawa, Keisuke

    2014-10-15

    A robust method to handle vacuum and near vacuum regions in hybrid simulations for space and astrophysical plasmas is presented. The conventional hybrid simulation model dealing with kinetic ions and a massless charge-neutralizing electron fluid is known to be susceptible to numerical instability due to divergence of the whistler-mode wave dispersion, as well as division-by-density operation in regions of low density. Consequently, a pure vacuum region is not allowed to exist in the simulation domain unless some ad hoc technique is used. To resolve this difficulty, an alternative way to introduce finite electron inertia effect is proposed. Contrary to the conventional method, the proposed one introduces a correction to the electric field rather than the magnetic field. It is shown that the generalized Ohm's law correctly reduces to Laplace's equation in a vacuum which therefore does not involve any numerical problems. In addition, a variable ion-to-electron mass ratio is introduced to reduce the phase velocity of high frequency whistler waves at low density regions so that the stability condition is always satisfied. It is demonstrated that the proposed model is able to handle near vacuum regions generated as a result of nonlinear self-consistent development of the system, as well as pure vacuum regions set up at the initial condition, without losing the advantages of the standard hybrid code.

  12. New data on African health professionals abroad

    PubMed Central

    Clemens, Michael A; Pettersson, Gunilla

    2008-01-01

    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. PMID:18186916

  13. Entropy and generalized least square methods in assessment of the regional value of streamgages

    USGS Publications Warehouse

    Markus, M.; Vernon, Knapp H.; Tasker, Gary D.

    2003-01-01

    The Illinois State Water Survey performed a study to assess the streamgaging network in the State of Illinois. One of the important aspects of the study was to assess the regional value of each station through an assessment of the information transfer among gaging records for low, average, and high flow conditions. This analysis was performed for the main hydrologic regions in the State, and the stations were initially evaluated using a new approach based on entropy analysis. To determine the regional value of each station within a region, several information parameters, including total net information, were defined based on entropy. Stations were ranked based on the total net information. For comparison, the regional value of the same stations was assessed using the generalized least square regression (GLS) method, developed by the US Geological Survey. Finally, a hybrid combination of GLS and entropy was created by including a function of the negative net information as a penalty function in the GLS. The weights of the combined model were determined to maximize the average correlation with the results of GLS and entropy. The entropy and GLS methods were evaluated using the high-flow data from southern Illinois stations. The combined method was compared with the entropy and GLS approaches using the high-flow data from eastern Illinois stations. ?? 2003 Elsevier B.V. All rights reserved.

  14. Regional blood flows measured in Mongolian gerbil by a modified microsphere method.

    PubMed

    Matsumoto, M; Kimura, K; Fujisawa, A; Matsuyama, T; Asai, T; Uyama, O; Yoneda, S; Abe, H

    1982-06-01

    Regional blood flow to major organs and regional cerebral blood flow were determined in seven anesthetized male gerbils by a modified microsphere method. Carbonized microspheres, 15 micrometers in diameter and labeled with 85Sr or 141Ce, were injected into the left ventricle by cardiac puncture through the closed thorax, and reference samples of known volume were withdrawn from tail-artery cannula. No significant hemodynamic alterations were observed during microsphere administration, and extraction of 15-micrometers microspheres by the pulmonary or systemic capillary beds was nearly 100%. The adequacy of mixing of microspheres in the left ventricle was also validated. The absolute regional blood flow to various organs and regional cerebral blood flow were expressed in terms of milliliters per minute per gram tissue weight, and the values mostly agreed with those reported previously in rats. The results indicate that the reference sample method can be applied to the gerbil. This method should allow the gerbil, which is an animal widely used in stroke research, to be conveniently used for hemodynamic studies when organ blood flow and regional cerebral blood flow are necessary. PMID:7091359

  15. Non-Reflecting Regions for Finite Difference Methods in Modeling of Elastic Wave Propagation in Plates

    NASA Technical Reports Server (NTRS)

    Kishoni, Doron; Taasan, Shlomo

    1994-01-01

    Solution of the wave equation using techniques such as finite difference or finite element methods can model elastic wave propagation in solids. This requires mapping the physical geometry into a computational domain whose size is governed by the size of the physical domain of interest and by the required resolution. This computational domain, in turn, dictates the computer memory requirements as well as the calculation time. Quite often, the physical region of interest is only a part of the whole physical body, and does not necessarily include all the physical boundaries. Reduction of the calculation domain requires positioning an artificial boundary or region where a physical boundary does not exist. It is important however that such a boundary, or region, will not affect the internal domain, i.e., it should not cause reflections that propagate back into the material. This paper concentrates on the issue of constructing such a boundary region.

  16. Indirect boundary element method to simulate elastic wave propagation in piecewise irregular and flat regions

    NASA Astrophysics Data System (ADS)

    Perton, Mathieu; Contreras-Zazueta, Marcial A.; Sánchez-Sesma, Francisco J.

    2016-04-01

    A new implementation of IBEM allows simulating the elastic wave propagation in complex configurations made of embedded regions that are or homogeneous with irregular boundaries or flat layers. In an older implementation, each layer of a flat layered region would have been treated as a separated homogeneous region without taking into account the flat boundary information. For both types of regions, the scattered field results from fictitious sources positioned along their boundaries. For the homogeneous regions, the fictitious sources emit as in a full-space and the wave field is given by analytical Green's functions. For flat layered regions, fictitious sources emit as in an unbounded flat layered region and the wave field is given by Green's functions obtained from the Discrete Wave Number (DWN) method. The new implementation allows then reducing the length of the discretized boundaries but DWN Green's functions require much more computation time than the full space Green's functions. Several optimization steps are then implemented and commented. Validations are presented for 2D and 3D problems. Higher efficiency is achieved in 3D.

  17. Large-scale regional comparisons of ecosystem processes: Methods and approaches

    NASA Astrophysics Data System (ADS)

    Legendre, Louis; Niquil, Nathalie

    2013-01-01

    Large-scale regional marine ecosystems can be compared for various processes that include their structure and biodiversity, functioning, services, and effects on biogeochemical processes. The comparisons can proceed from data up, or from conceptual models down, or from a combination of models and data. This study proposes a typology of methods and approaches that are currently used, or could possibly be used for making large-scale ecosystem comparisons. The various methods and approaches are illustrated with examples drawn from the literature.

  18. Combined autofluorescence and Raman spectroscopy method for skin tumor detection in visible and near infrared regions

    NASA Astrophysics Data System (ADS)

    Zakharov, V. P.; Bratchenko, I. A.; Artemyev, D. N.; Myakinin, O. O.; Khristoforova, Y. A.; Kozlov, S. V.; Moryatov, A. A.

    2015-07-01

    The combined application of Raman and autofluorescence spectroscopy in visible and near infrared regions for the analysis of malignant neoplasms of human skin was demonstrated. Ex vivo experiments were performed for 130 skin tissue samples: 28 malignant melanomas, 19 basal cell carcinomas, 15 benign tumors, 9 nevi and 59 normal tissues. Proposed method of Raman spectra analysis allows for malignant melanoma differentiating from other skin tissues with accuracy of 84% (sensitivity of 97%, specificity of 72%). Autofluorescence analysis in near infrared and visible regions helped us to increase the diagnostic accuracy by 5-10%. Registration of autofluorescence in near infrared region is realized in one optical unit with Raman spectroscopy. Thus, the proposed method of combined skin tissues study makes possible simultaneous large skin area study with autofluorescence spectra analysis and precise neoplasm type determination with Raman spectroscopy.

  19. Automatic segmentation method of striatum regions in quantitative susceptibility mapping images

    NASA Astrophysics Data System (ADS)

    Murakawa, Saki; Uchiyama, Yoshikazu; Hirai, Toshinori

    2015-03-01

    Abnormal accumulation of brain iron has been detected in various neurodegenerative diseases. Quantitative susceptibility mapping (QSM) is a novel contrast mechanism in magnetic resonance (MR) imaging and enables the quantitative analysis of local tissue susceptibility property. Therefore, automatic segmentation tools of brain regions on QSM images would be helpful for radiologists' quantitative analysis in various neurodegenerative diseases. The purpose of this study was to develop an automatic segmentation and classification method of striatum regions on QSM images. Our image database consisted of 22 QSM images obtained from healthy volunteers. These images were acquired on a 3.0 T MR scanner. The voxel size was 0.9×0.9×2 mm. The matrix size of each slice image was 256×256 pixels. In our computerized method, a template mating technique was first used for the detection of a slice image containing striatum regions. An image registration technique was subsequently employed for the classification of striatum regions in consideration of the anatomical knowledge. After the image registration, the voxels in the target image which correspond with striatum regions in the reference image were classified into three striatum regions, i.e., head of the caudate nucleus, putamen, and globus pallidus. The experimental results indicated that 100% (21/21) of the slice images containing striatum regions were detected accurately. The subjective evaluation of the classification results indicated that 20 (95.2%) of 21 showed good or adequate quality. Our computerized method would be useful for the quantitative analysis of Parkinson diseases in QSM images.

  20. A new method to obtain uniform distribution of ground control points based on regional statistical information

    NASA Astrophysics Data System (ADS)

    Ma, Chao; An, Wei; Deng, Xinpu

    2015-10-01

    The Ground Control Points (GCPs) is an important source of fundamental data in geometric correction for remote sensing imagery. The quantity, accuracy and distribution of GCPs are three factors which may affect the accuracy of geometric correction. It is generally required that the distribution of GCP should be uniform, so they can fully control the accuracy of mapping regions. In this paper, we establish an objective standard of evaluating the uniformity of the GCPs' distribution based on regional statistical information (RSI), and get an optimal distribution of GCPs. This sampling method is called RSIS for short in this work. The Amounts of GCPs in different regions by equally partitioning the image in regions in different manners are counted which forms a vector called RSI vector in this work. The uniformity of GCPs' distribution can be evaluated by a mathematical quantity of the RSI vector. An optimal distribution of GCPs is obtained by searching the RSI vector with the minimum mathematical quantity. In this paper, the simulation annealing is employed to search the optimal distribution of GCPs that have the minimum mathematical quantity of the RSI vector. Experiments are carried out to test the method proposed in this paper, and sampling designs compared are simple random sampling and universal kriging model-based sampling. The experiments indicate that this method is highly recommended as new GCPs sampling design method for geometric correction of remotely sensed imagery.

  1. REGIONAL METHODS INITIATIVE: DEVELOPMENT OF LARGE RIVER BIOASSESSMENT PROTOCOLS (LRBP) FOR BENTHIC MACROINVERTEBRATES

    EPA Science Inventory

    We are developing the Large River Bioassessment Protocol (LRBP) for assessment of benthic macroinvertebrate assemblages. This multi-habitat method is currently being used in support of a REMAP project for probabilistic assessment of large rivers in USEPA Region 5. Six rivers, r...

  2. A summary of methods for the collection and analysis of basic hydrologic data for arid regions

    USGS Publications Warehouse

    Rantz, S.E.; Eakin, T.E.

    1971-01-01

    This report summarizes and discusses current methods of collecting and analyzing the data required for a study of the basic hydrology of arid regions. The fundamental principles behind these methods are no different than those that apply to studies of humid regions, but in arid regions the infrequent occurrence of precipitation, the great variability of the many hydrologic elements, and the inaccessibility of most basins usually make it economically infeasible to use conventional levels of instrumentation. Because of these economic considerations hydrologic studies in arid regions have been commonly of the reconnaissance type; the more costly detailed studies are generally restricted to experimental basins and to those basins that now have major economic significance. A thorough search of the literature and personal communication with workers in the field of arid-land hydrology provided the basis for this summary of methods used in both reconnaissance and detailed hydrologic studies. The conclusions reached from a consideration of previously reported methods are interspersed in this report where appropriate.

  3. Combined Methods for Quantifying Uncertainty of Regional Climate Change for Use in Policy and Resources Management

    NASA Astrophysics Data System (ADS)

    Mearns, L. O.; Tebaldi, C.

    2006-12-01

    Over tha past few years, methods for quantifying uncertainty in regional climate change have seen an upswing in development, and this was greatly facilitated by the creation of a relatively large multi-member ensemble of coupled climate model runs for the Fourth Assessment of the IPCC. Usually the rationale for developing such probabilistic methods is for use by impacts researchers, policy makers, and resource managers, to aid in their decision making. While these developments have been welcome, it is clear that probabilisitc information developed in a Bayesian framework, alone will not suffice for providng levels of confidence in the future projections. While some of the methods have attempted to weight the members of multi-model ensembles by evaluating how well the models reproduce current climate, so far these methods have been overly simplistic. It may well be that qualitative information regarding the model's reproduction of critical processes that determine the climate of a particular region needs to be considered along with probabilistic information. We discuss how these different types of information (qualitative process-based and probability density functions) could be combined to provide a more complete assessment of how confident we should be regarding regional cliamte change. measure of uncertainty for regional scale climate change.

  4. Seismic attenuation tomography of the Tonga-Fiji region using phase pair methods

    NASA Astrophysics Data System (ADS)

    Roth, Erich G.; Wiens, Douglas A.; Dorman, Leroy M.; Hildebrand, John; Webb, Spahr C.

    1999-03-01

    The anelastic structure of the region surrounding the Tonga slab and Lau back arc spreading center in the southwest Pacific is studied using data from 12 broadband island stations and 30 ocean bottom seismographs. Two differential attenuation methods determine δt* over the frequency band 0.1 to 3.5 Hz for earthquakes in the Tonga slab. The S-P method measures the difference in spectral decay between P and S waves arriving at the same station. The P-P method measures the difference in spectral decay for P waves with different paths through the upper mantle. Eight hundred sixty phase pairs are used to invert for two-dimensional 1/Qα structure using a nonnegative least squares algorithm. A grid search method determines the Qα/Qβ ratio most compatible with both the S-P and P-P differential measurements. The highest attenuation (Qα = 90) is found within the upper 100 km beneath the active portions of the Lau Basin extending westward to the Lau Ridge. These regions probably delineate the source region for the back arc spreading center magmas, expected to be within the upper 100 km based on petrological considerations. The high attenuation regions also correlate well with zones of low P wave velocity determined by regional velocity tomography. Somewhat lower attenuation is found beneath the Fiji Plateau than beneath the Lau Basin. The entire back arc is characterized by a gradual decrease in attenuation to a depth of 300 to 400 km. The slab is imaged as a region of low attenuation (Qα > 900) material. A Qα/Qβ ratio of 1.75 provides the best fit between the S-P and P-P data sets upon inversion. Spectral stacking shows no frequency dependence within the frequency band analyzed.

  5. High birthweights among infants of north African immigrants in Belgium.

    PubMed Central

    Buekens, P; Masuy-Stroobant, G; Delvaux, T

    1998-01-01

    OBJECTIVES: This study examined birthweights of North African immigrants in Belgium. METHODS: Analyses focused on Belgian single live birth certificates from 1981 to 1988. RESULTS: Low-birthweight (< 2500 g) rates were 3.1% among 34,686 newborns of North African origin and 4.8% among 804,286 newborns of Belgian origin. The entire North African birthweight distribution was shifted toward higher birthweights than the Belgian distribution. Low frequencies of low birthweights among North Africans were still observed after marital status, occupation of the father, and parity had been taken into account. CONCLUSIONS: Despite their low socioeconomic status, North African immigrants have high birthweights. PMID:9585752

  6. Determination of recent horizontal crustal movements and deformations of African and Eurasian plates in western Mediterranean region using geodetic-GPS computations extended to 2006 (from 1997) related to NAFREF and AFREF frames.

    NASA Astrophysics Data System (ADS)

    Azzouzi, R.

    2009-04-01

    Determination of recent horizontal crustal movements and deformations of African and Eurasian plates in western Mediterranean region using geodetic-GPS computations extended to 2006 (from 1997) related to NAFREF and AFREF frames. By: R. Azzouzi*, M. Ettarid*, El H. Semlali*, et A. Rimi+ * Filière de Formation en Topographie Institut Agronomique et Vétérinaire Hassan II B.P. 6202 Rabat-Instituts MAROC + Département de la Physique du Globe Université Mohammed V Rabat MAROC This study focus on the use of the geodetic spatial technique GPS for geodynamic purposes generally in the Western Mediterranean area and particularly in Morocco. It aims to exploit this technique first to determine the geodetic coordinates on some western Mediterranean sites. And also this technique is used to detect and to determine movements cross the boundary line between the two African and Eurasian crustal plates on some well chosen GPS-Geodynamics sites. It will allow us also to estimate crustal dynamic parameters of tension that results. These parameters are linked to deformations of terrestrial crust in the region. They are also associated with tectonic constraints of the study area. The usefulness of repeated measurements of these elements, the estimate of displacements and the determination of their temporal rates is indisputable. Indeed, sismo-tectonique studies allow a good knowledge of the of earthquake processes, their frequency their amplitude and even of their prediction in the world in general and in Moroccan area especially. They allow also contributing to guarantee more security for all most important management projects, as projects of building great works (dams, bridges, nuclear centrals). And also as preliminary study, for the most important joint-project between Europe and Africa through the Strait of Gibraltar. For our application, 23 GPS monitoring stations under the ITRF2000 reference frame are chosen in Eurasian and African plates. The sites are located around the

  7. TOGETHER Project to Increase Understanding of the HIV Epidemic Among Sub-Saharan African Migrants: Protocol of Community-Based Participatory Mixed-Method Studies

    PubMed Central

    Vuylsteke, Bea; Manirankunda, Lazare; Deblonde, Jessika; Kint, Ilse; Namanya, Fiona; Fransen, Katrien; Colebunders, Robert; Laga, Marie; Adobea, Dorothy; Nöstlinger, Christiana

    2016-01-01

    Background Sub-Saharan African Migrants (SAM) are the second largest group affected by HIV/AIDS in Belgium and the rest of Western Europe. Increasing evidence shows that, more than previously thought, SAM are acquiring HIV in their host countries. This calls for a renewed focus on primary prevention. Yet, knowledge on the magnitude of the HIV epidemic among SAM (HIV prevalence estimates and proportions of undiagnosed HIV infections) and underlying drivers are scarce and limit the development of such interventions. Objective By applying a community-based participatory and mixed-methods approach, the TOGETHER project aims to deepen our understanding of HIV transmission dynamics, as well as inform future primary prevention interventions for this target group. Methods The TOGETHER project consists of a cross-sectional study to assess HIV prevalence and risk factors among SAM visiting community settings in Antwerp city, Belgium, and links an anonymous electronic self-reported questionnaire to oral fluid samples. Three formative studies informed this method: (1) a social mapping of community settings using an adaptation of the PLACE method; (2) a multiple case study aiming to identify factors that increase risk and vulnerability for HIV infection by triangulating data from life history interviews, lifelines, and patient files; and (3) an acceptability and feasibility study of oral fluid sampling in community settings using participant observations. Results Results have been obtained from 4 interlinked studies and will be described in future research. Conclusions Combining empirically tested and innovative epidemiological and social science methods, this project provides the first HIV prevalence estimates for a representative sample of SAM residing in a West European city. By triangulating qualitative and quantitative insights, the project will generate an in-depth understanding of the factors that increase risk and vulnerability for HIV infection among SAM. Based on this

  8. Institutionalization of African traditional medicine in health care systems in Africa.

    PubMed

    Kofi-Tsekpo, Mawuli

    2004-01-01

    best practices and the most useful medicines are made available in the most affordable manner. Every country in the African region would be expected to adopt a method of incorporation that would be suitable: integrative, inclusive, or tolerant, as the case may be. It is an undeniable fact that we cannot afford to sit on the fence. All the stakeholders stand to gain a great deal in the development and promotion of African traditional medicine. In particular, all the practitioners in the present allopathic health care system will gain professionally as well as economically as they will have access to an additional culture-friendly system with which to provide services to the people. All the stakeholders must join hands in the effort to institutionalize the appropriate African traditional medicine in the health care systems in order to provide the health services that are urgently needed in the communities. PMID:17298111

  9. Development of a suspension microarray for the genotyping of African swine fever virus targeting the SNPs in the C-terminal end of the p72 gene region of the genome.

    PubMed

    Leblanc, N; Cortey, M; Fernandez Pinero, J; Gallardo, C; Masembe, C; Okurut, A R; Heath, L; van Heerden, J; Sánchez-Vizcaino, J M; Ståhl, K; Belák, S

    2013-08-01

    African swine fever virus (ASFV) causes one of the most dreaded transboundary animal diseases (TADs) in Suidae. African swine fever (ASF) often causes high rates of morbidity and mortality, which can reach 100% in domestic swine. To date, serological diagnosis has the drawback of not being able to differentiate variants of this virus. Previous studies have identified the 22 genotypes based on sequence variation in the C-terminal region of the p72 gene, which has become the standard for categorizing ASFVs. This article describes a genotyping assay developed using a segment of PCR-amplified genomic DNA of approximately 450 bp, which encompasses the C-terminal end of the p72 gene. Complementary paired DNA probes of 15 or 17 bp in length, which are identical except for a single nucleotide polymorphism (SNP) in the central position, were designed to either individually or in combination differentiate between the 22 genotypes. The assay was developed using xMAP technology; probes were covalently linked to microspheres, hybridized to PCR product, labelled with a reporter and read in the Luminex 200 analyzer. Characterization of the sample was performed by comparing fluorescence of the paired SNP probes, that is, the probe with higher fluorescence in a complementary pair identified the SNP that a particular sample possessed. In the final assay, a total of 52 probes were employed, 24 SNP pairs and 4 for general detection. One or more samples from each of the 22 genotypes were tested. The assay was able to detect and distinguish all 22 genotypes. This novel assay provides a powerful novel tool for the simultaneous rapid diagnosis and genotypic differentiation of ASF. PMID:22776009

  10. Selective breeding: the future of TB management in African buffalo?

    PubMed

    le Roex, N; Berrington, C M; Hoal, E G; van Helden, P D

    2015-09-01

    The high prevalence of bovine tuberculosis (BTB) in African buffalo (Syncerus caffer) in regions of southern African has a negative economic impact on the trade of animals and animal products, represents an ecological threat to biodiversity, and poses a health risk to local communities through the wildlife-cattle-human interface. Test and cull methods may not be logistically feasible in many free-range wildlife systems, and with the presence of co-existing BTB hosts and the limited effectiveness of the BCG vaccine in buffalo, there is a need for alternative methods of BTB management. Selective breeding for increased resistance to BTB in buffalo may be a viable method of BTB management in the future, particularly if genetic information can be incorporated into these schemes. To explore this possibility, we discuss the different strategies that can be employed in selective breeding programmes, and consider the implementation of genetic improvement schemes. We reflect on the suitability of applying this strategy for enhanced BTB resistance in African buffalo, and address the challenges of this approach that must be taken into account. Conclusions and the implications for management are presented. PMID:25985909

  11. Guide for Regional Integrated Assessments: Handbook of Methods and Procedures, Version 5.1. Appendix 1

    NASA Technical Reports Server (NTRS)

    Rosenzweig, Cynthia E.; Jones, James W.; Hatfield, Jerry; Antle, John; Ruane, Alex; Boote, Ken; Thorburn, Peter; Valdivia, Roberto; Porter, Cheryl; Janssen, Sander; Mutter, Carolyn

    2015-01-01

    The purpose of this handbook is to describe recommended methods for a trans-disciplinary, systems-based approach for regional-scale (local to national scale) integrated assessment of agricultural systems under future climate, bio-physical and socio-economic conditions. An earlier version of this Handbook was developed and used by several AgMIP Regional Research Teams (RRTs) in Sub-Saharan Africa (SSA) and South Asia (SA)(AgMIP handbook version 4.2, www.agmip.org/regional-integrated-assessments-handbook/). In contrast to the earlier version, which was written specifically to guide a consistent set of integrated assessments across SSA and SA, this version is intended to be more generic such that the methods can be applied to any region globally. These assessments are the regional manifestation of research activities described by AgMIP in its online protocols document (available at www.agmip.org). AgMIP Protocols were created to guide climate, crop modeling, economics, and information technology components of its projects.

  12. An algorithmic method for functionally defining regions of interest in the ventral visual pathway.

    PubMed

    Julian, J B; Fedorenko, Evelina; Webster, Jason; Kanwisher, Nancy

    2012-05-01

    In a widely used functional magnetic resonance imaging (fMRI) data analysis method, functional regions of interest (fROIs) are handpicked in each participant using macroanatomic landmarks as guides, and the response of these regions to new conditions is then measured. A key limitation of this standard handpicked fROI method is the subjectivity of decisions about which clusters of activated voxels should be treated as the particular fROI in question in each subject. Here we apply the Group-Constrained Subject-Specific (GSS) method for defining fROIs, recently developed for identifying language fROIs (Fedorenko et al., 2010), to algorithmically identify fourteen well-studied category-selective regions of the ventral visual pathway (Kanwisher, 2010). We show that this method retains the benefit of defining fROIs in individual subjects without the subjectivity inherent in the traditional handpicked fROI approach. The tools necessary for using this method are available on our website (http://web.mit.edu/bcs/nklab/GSS.shtml). PMID:22398396

  13. Detection Method of Skin Region by Near-IR Spectrum Multi-Band

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasuhiro; Yamamoto, Kazuhiko; Kato, Kunihito; Andoh, Michinori; Kojima, Shinichi

    Many active safety technologies for the driver support system are developing. Most of the traffic accidents are caused by driver's inattentive or drowsy. We are developing a driver support system that protects from traffic accidents by these causes. Our purpose is to detect the driver's face region by using a camera. A lot of face detection methods are proposed, but there is not a technique addressing every environment inside the car. For example, skin color segmentation can not detect the skin region in the night, because it has to light up the driver by bright light. In this paper, we propose a skin detection method by the unique reflection characteristics of the materials. Our method is very simple algorithm. We developed a skin detection system, and confirmed effectiveness by the evaluation experiment in indoor environment, and showed the effectiveness by a driving experiment in the night.

  14. An exploratory GIS-based method to identify and characterise landscapes with an elevated epidemiological risk of Rhodesian human African trypanosomiasis

    PubMed Central

    2012-01-01

    Background Specific land cover types and activities have been correlated with Trypanosoma brucei rhodesiense distributions, indicating the importance of landscape for epidemiological risk. However, methods proposed to identify specific areas with elevated epidemiological risk (i.e. where transmission is more likely to occur) tend to be costly and time consuming. This paper proposes an exploratory spatial analysis using geo-referenced human African trypanosomiasis (HAT) cases and matched controls from Serere hospital, Uganda (December 1998 to November 2002) to identify areas with an elevated epidemiological risk of HAT. Methods Buffers 3 km from each case and control were used to represent areas in which village inhabitants would carry out their daily activities. It was hypothesised that the selection of areas where several case village buffers overlapped would enable the identification of locations with increased risk of HAT transmission, as these areas were more likely to be frequented by HAT cases in several surrounding villages. The landscape within these overlap areas should more closely relate to the environment in which transmission occurs as opposed to using the full buffer areas. The analysis was carried out for each of four annual periods, for both cases and controls, using a series of threshold values (number of overlapping buffers), including a threshold of one, which represented the benchmark (e.g. use of the full buffer area as opposed to the overlap areas). Results A greater proportion of the overlap areas for cases consisted of seasonally flooding grassland and lake fringe swamp, than the control overlap areas, correlating well with the preferred habitat of the predominant tsetse species within the study area (Glossina fuscipes fuscipes). The use of overlap areas also resulted in a greater difference between case and control landscapes, when compared with the benchmark (using the full buffer area). Conclusions These results indicate that the overlap

  15. A practical salient region feature based 3D multi-modality registration method for medical images

    NASA Astrophysics Data System (ADS)

    Hahn, Dieter A.; Wolz, Gabriele; Sun, Yiyong; Hornegger, Joachim; Sauer, Frank; Kuwert, Torsten; Xu, Chenyang

    2006-03-01

    We present a novel representation of 3D salient region features and its integration into a hybrid rigid-body registration framework. We adopt scale, translation and rotation invariance properties of those intrinsic 3D features to estimate a transform between underlying mono- or multi-modal 3D medical images. Our method combines advantageous aspects of both feature- and intensity-based approaches and consists of three steps: an automatic extraction of a set of 3D salient region features on each image, a robust estimation of correspondences and their sub-pixel accurate refinement with outliers elimination. We propose a region-growing based approach for the extraction of 3D salient region features, a solution to the problem of feature clustering and a reduction of the correspondence search space complexity. Results of the developed algorithm are presented for both mono- and multi-modal intra-patient 3D image pairs (CT, PET and SPECT) that have been acquired for change detection, tumor localization, and time based intra-person studies. The accuracy of the method is clinically evaluated by a medical expert with an approach that measures the distance between a set of selected corresponding points consisting of both anatomical and functional structures or lesion sites. This demonstrates the robustness of the proposed method to image overlap, missing information and artefacts. We conclude by discussing potential medical applications and possibilities for integration into a non-rigid registration framework.

  16. A method for correcting regional bias in SMOS global salinity products

    NASA Astrophysics Data System (ADS)

    Tong, Xiaolin; Wang, Zhenzhan; Li, Qingxia

    2015-07-01

    Soil Moisture and Ocean Salinity (SMOS) Level 3 (L3) sea surface salinity (SSS) products are provided by the Barcelona Expert Centre (BEC). Strong biases were observed on the SMOS SSS products, thus the data from the Centre Aval de Traitement des Données SMOS (CATDS) were adjusted for biases using a large-scale correction derived from observed differences between the SMOS SSS and World Ocean Atlas (WOA) climatology data. However, this large-scale correction method is not suitable for correcting the large gradient of salinity biases. Here, we present a method for the correction of SSS regional bias of the monthly L3 products. Based on the stable characteristics of the large SSS biases from month to month in some regions, corrected SMOS SSS maps can be obtained from the monthly mean values after removing the regional biases. The accuracy of the SMOS SSS measurements is greatly improved, especially near the coastline, at high latitudes, and in some open ocean regions. The SMOS and ISAS SSS data are also compared with Aquarius SSS to verify the corrected SMOS SSS data. The correction method presented here only corrects annual mean biases. The measurement accuracy of the SSS may be improved by considering the influence of atmospheric and ocean circulation in different seasons and years.

  17. Regional analysis of annual maximum rainfall using TL-moments method

    NASA Astrophysics Data System (ADS)

    Shabri, Ani Bin; Daud, Zalina Mohd; Ariff, Noratiqah Mohd

    2011-06-01

    Information related to distributions of rainfall amounts are of great importance for designs of water-related structures. One of the concerns of hydrologists and engineers is the probability distribution for modeling of regional data. In this study, a novel approach to regional frequency analysis using L-moments is revisited. Subsequently, an alternative regional frequency analysis using the TL-moments method is employed. The results from both methods were then compared. The analysis was based on daily annual maximum rainfall data from 40 stations in Selangor Malaysia. TL-moments for the generalized extreme value (GEV) and generalized logistic (GLO) distributions were derived and used to develop the regional frequency analysis procedure. TL-moment ratio diagram and Z-test were employed in determining the best-fit distribution. Comparison between the two approaches showed that the L-moments and TL-moments produced equivalent results. GLO and GEV distributions were identified as the most suitable distributions for representing the statistical properties of extreme rainfall in Selangor. Monte Carlo simulation was used for performance evaluation, and it showed that the method of TL-moments was more efficient for lower quantile estimation compared with the L-moments.

  18. A Method for Systematic Assessment of Intrinsically Disordered Protein Regions by NMR.

    PubMed

    Goda, Natsuko; Shimizu, Kana; Kuwahara, Yohta; Tenno, Takeshi; Noguchi, Tamotsu; Ikegami, Takahisa; Ota, Motonori; Hiroaki, Hidekazu

    2015-01-01

    Intrinsically disordered proteins (IDPs) that lack stable conformations and are highly flexible have attracted the attention of biologists. Therefore, the development of a systematic method to identify polypeptide regions that are unstructured in solution is important. We have designed an "indirect/reflected" detection system for evaluating the physicochemical properties of IDPs using nuclear magnetic resonance (NMR). This approach employs a "chimeric membrane protein"-based method using the thermostable membrane protein PH0471. This protein contains two domains, a transmembrane helical region and a C-terminal OB (oligonucleotide/oligosaccharide binding)-fold domain (named NfeDC domain), connected by a flexible linker. NMR signals of the OB-fold domain of detergent-solubilized PH0471 are observed because of the flexibility of the linker region. In this study, the linker region was substituted with target IDPs. Fifty-three candidates were selected using the prediction tool POODLE and 35 expression vectors were constructed. Subsequently, we obtained 15N-labeled chimeric PH0471 proteins with 25 IDPs as linkers. The NMR spectra allowed us to classify IDPs into three categories: flexible, moderately flexible, and inflexible. The inflexible IDPs contain membrane-associating or aggregation-prone sequences. This is the first attempt to use an indirect/reflected NMR method to evaluate IDPs and can verify the predictions derived from our computational tools. PMID:26184172

  19. Fine-Mapping in African Americans of Eight Recently Discovered Genetic Loci for Plasma Lipids: The Jackson Heart Study

    PubMed Central

    Keebler, Mary E.; Deo, Rahul C.; Surti, Aarti; Konieczkowski, David; Guiducci, Candace; Burtt, Noel; Buxbaum, Sarah G.; Sarpong, Daniel F.; Steffes, Michael W.; Wilson, James G.; Taylor, Herman A.; Kathiresan, Sekar

    2011-01-01

    Background Genome-wide association studies in cohorts of European descent have identified novel genomic regions as associated with lipids, but their relevance in African Americans remains unclear. Methods and Results We genotyped 8 index SNPs and 488 tagging SNPs across 8 novel lipid loci in the Jackson Heart Study, a community-based cohort of 4605 African Americans. For each trait, we calculated residuals adjusted for age, sex, and global ancestry and performed multivariable linear regression to detect genotype-phenotype association with adjustment for local ancestry. To explore admixture effects, we conducted stratified analyses in individuals with a high probability of 2 African ancestral alleles or at least 1 European allele at each locus. We confirmed 2 index SNPs as associated with lipid traits in African Americans, with suggestive association for 3 more. However, the effect sizes for 4 of the 5 associated SNPs were larger in the European local ancestry subgroup compared to the African local ancestry subgroup, suggesting that the replication is driven by European ancestry segments. Through fine-mapping, we discovered 3 new SNPs with significant associations, two with consistent effect on triglyceride levels across ancestral groups: rs636523 near DOCK7/ANGPTL3 and rs780093 in GCKR. African LD patterns did not assist in narrowing association signals. Conclusions We confirm that 5 genetic regions associated with lipid traits in European-derived populations are relevant in African Americans. To further evaluate these loci, fine-mapping in larger African American cohorts and/or resequencing will be required. PMID:20570916

  20. Development of West African Rainy Seasons (Invited)

    NASA Astrophysics Data System (ADS)

    Cook, K. H.

    2013-12-01

    The development of West African rainy seasons in the observed climatology can be understood in terms of two factors: continentality, i.e., the shape and placement of the African continent, and solar forcing. First, the observed features of the West African spring and summer precipitation climatology that distinguish it from the precipitation climatology of the tropical Atlantic to the east and Central/Eastern Africa to the west are presented. These include a lingering of the precipitation maximum along the Guinean coast in June and the apparent sudden movement of the precipitation maximum into the Sahel in early July. Then, these distinguishing features of the West Africa precipitation climatology are explained in terms of the regional dynamics and, finally, related to continentality and solar forcing through the roles of the African easterly jet, land surface temperature, and seasonally-varying SSTs.

  1. Regional frequency analysis of extreme rainfalls using partial L moments method

    NASA Astrophysics Data System (ADS)

    Zakaria, Zahrahtul Amani; Shabri, Ani

    2013-07-01

    An approach based on regional frequency analysis using L moments and LH moments are revisited in this study. Subsequently, an alternative regional frequency analysis using the partial L moments (PL moments) method is employed, and a new relationship for homogeneity analysis is developed. The results were then compared with those obtained using the method of L moments and LH moments of order two. The Selangor catchment, consisting of 37 sites and located on the west coast of Peninsular Malaysia, is chosen as a case study. PL moments for the generalized extreme value (GEV), generalized logistic (GLO), and generalized Pareto distributions were derived and used to develop the regional frequency analysis procedure. PL moment ratio diagram and Z test were employed in determining the best-fit distribution. Comparison between the three approaches showed that GLO and GEV distributions were identified as the suitable distributions for representing the statistical properties of extreme rainfall in Selangor. Monte Carlo simulation used for performance evaluation shows that the method of PL moments would outperform L and LH moments methods for estimation of large return period events.

  2. Regional cerebral blood flow in schizophrenics. Tests using the xenon Xe 133 inhalation method

    SciTech Connect

    Ariel, R.N.; Golden, C.J.; Berg, R.A.; Quaife, M.A.; Dirksen, J.W.; Forsell, T.; Wilson, J.; Graber, B.

    1983-03-01

    Measurements of intrahemispheric and bilateral regional cerebral blood flow (CBF) for gray and white matter were compared in 29 schizophrenic patients and 22 normal controls, using the xenon Xe 133 inhalation method. Results showed significantly lower CBF values for all brain regions in the schizophrenic group, and post hoc comparisons showed relatively greater reduced gray-matter CBF values in the anterior areas of the brain. There was also a left-hemisphere frontal loss similar to that reported previously, although it was in the context of a generalized loss in anterior functioning. Interhemispheric comparison within both groups showed no differences between homologous regions for gray matter, and greater white-matter CBF values in the right hemisphere than in the left hemisphere. The findings support a hypothesis of a bilateral anterior deficit in schizophrenia.

  3. Segmentation method of eye region based on fuzzy logic system for classifying open and closed eyes

    NASA Astrophysics Data System (ADS)

    Kim, Ki Wan; Lee, Won Oh; Kim, Yeong Gon; Hong, Hyung Gil; Lee, Eui Chul; Park, Kang Ryoung

    2015-03-01

    The classification of eye openness and closure has been researched in various fields, e.g., driver drowsiness detection, physiological status analysis, and eye fatigue measurement. For a classification with high accuracy, accurate segmentation of the eye region is required. Most previous research used the segmentation method by image binarization on the basis that the eyeball is darker than skin, but the performance of this approach is frequently affected by thick eyelashes or shadows around the eye. Thus, we propose a fuzzy-based method for classifying eye openness and closure. First, the proposed method uses I and K color information from the HSI and CMYK color spaces, respectively, for eye segmentation. Second, the eye region is binarized using the fuzzy logic system based on I and K inputs, which is less affected by eyelashes and shadows around the eye. The combined image of I and K pixels is obtained through the fuzzy logic system. Third, in order to reflect the effect by all the inference values on calculating the output score of the fuzzy system, we use the revised weighted average method, where all the rectangular regions by all the inference values are considered for calculating the output score. Fourth, the classification of eye openness or closure is successfully made by the proposed fuzzy-based method with eye images of low resolution which are captured in the environment of people watching TV at a distance. By using the fuzzy logic system, our method does not require the additional procedure of training irrespective of the chosen database. Experimental results with two databases of eye images show that our method is superior to previous approaches.

  4. A New Evaluation Method for Groundwater Quality Applied in Guangzhou Region, China: Using Fuzzy Method Combining Toxicity Index.

    PubMed

    Liu, Fan; Huang, Guanxing; Sun, Jichao; Jing, Jihong; Zhang, Ying

    2016-02-01

    Groundwater quality assessment is essential for drinking from a security point of view. In this paper, a new evaluation method called toxicity combined fuzzy evaluation (TCFE) has been put forward, which is based on the fuzzy synthetic evaluation (FSE) method and the toxicity data from Agency for Toxic Substances and Disease Registry. The comparison of TCFE and FSE in the groundwater quality assessment of Guangzhou region also has been done. The assessment results are divided into 5 water quality levels; level I is the best while level V is the worst. Results indicate that the proportion of level I, level II, and level III used by the FSE method was 69.33% in total. By contrast, this proportion rose to 81.33% after applying the TCFE method. In addition, 66.7% of level IV samples in the FSE method became level I (50%), level II (25%), and level III (25%) in the TCFE method and 29.41% of level V samples became level I (50%) and level III (50%). This trend was caused by the weight change after the combination of toxicity index. By analyzing the changes of different indicators' weight, it could be concluded that the better-changed samples mainly exceeded the corresponding standards of regular indicators and the deteriorated samples mainly exceeded the corresponding standards of toxic indicators. The comparison between the two results revealed that the TCFE method could represent the health implications of toxic indicators reasonably. As a result, the TCFE method is more scientific in view of drinking safety. PMID:26803098

  5. Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

    SciTech Connect

    Lestari, Titik; Nugraha, Andri Dian

    2015-04-24

    Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA’s) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 – April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

  6. Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

    NASA Astrophysics Data System (ADS)

    Lestari, Titik; Nugraha, Andri Dian

    2015-04-01

    Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA's) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 - April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

  7. Attenuation correction with region growing method used in the positron emission mammography imaging system

    NASA Astrophysics Data System (ADS)

    Gu, Xiao-Yue; Li, Lin; Yin, Peng-Fei; Yun, Ming-Kai; Chai, Pei; Huang, Xian-Chao; Sun, Xiao-Li; Wei, Long

    2015-10-01

    The Positron Emission Mammography imaging system (PEMi) provides a novel nuclear diagnosis method dedicated for breast imaging. With a better resolution than whole body PET, PEMi can detect millimeter-sized breast tumors. To address the requirement of semi-quantitative analysis with a radiotracer concentration map of the breast, a new attenuation correction method based on a three-dimensional seeded region growing image segmentation (3DSRG-AC) method has been developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuity property of the segmentation result makes this new method free of activity variation of breast tissues. The threshold value chosen is the key process for the segmentation method. The first valley in the grey level histogram of the reconstruction image is set as the lower threshold, which works well in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution determination. Attenuation correction also improves the probability of detecting small and early breast tumors. Supported by Knowledge Innovation Project of The Chinese Academy of Sciences (KJCX2-EW-N06)

  8. Line segment confidence region-based string matching method for map conflation

    NASA Astrophysics Data System (ADS)

    Huh, Yong; Yang, Sungchul; Ga, Chillo; Yu, Kiyun; Shi, Wenzhong

    2013-04-01

    In this paper, a method to detect corresponding point pairs between polygon object pairs with a string matching method based on a confidence region model of a line segment is proposed. The optimal point edit sequence to convert the contour of a target object into that of a reference object was found by the string matching method which minimizes its total error cost, and the corresponding point pairs were derived from the edit sequence. Because a significant amount of apparent positional discrepancies between corresponding objects are caused by spatial uncertainty and their confidence region models of line segments are therefore used in the above matching process, the proposed method obtained a high F-measure for finding matching pairs. We applied this method for built-up area polygon objects in a cadastral map and a topographical map. Regardless of their different mapping and representation rules and spatial uncertainties, the proposed method with a confidence level at 0.95 showed a matching result with an F-measure of 0.894.

  9. Radionuclide ventriculography: evaluation of automated and visual methods for regional wall motion analysis

    SciTech Connect

    Steckley, R.A.; Kronenberg, M.W.; Born, M.L.; Rhea, T.C.; Bateman, J.E.; Rollo, F.D.; Friesinger, G.C.

    1982-01-01

    Regional wall motion (RWM) abnormalities are sensitive indicators of left ventricular (LV) dysfunction, but quantitation of RWM with gated radionuclide ventriculography (RVG) has been limited, particularly in the left anterior oblique (LAO) projection. Regional LV performance was studied in 18 patients undergoing LAO RVG immediately prior to contrast ventriculography (CVG). Wall motion was analyzed by semiautomated and visual methods using several coordinate systems. For semiautomated methods, RVG and CVG wall motion were closely related in the two 90 degrees polar sectors at the apex and posterior wall (r . .85) and in the five 45 degrees polar sectors from midseptum through posterior wall (r . .82). The basal sectors on RVG had weak relationship to CVG, due to adjacent vascular structures. Semiautomated and visual grades for polar sectors on both CVG and RVG were closely related (r . .88- .94). Measured regional wall motion on LAO RVG compared favorably with near-simultaneous CVG in nonoverlapping portions of the LV and allowed objective quantitation of regional LV performance.

  10. Radionuclide ventriculography: evaluation of automated and visual methods for regional wall motion analysis

    SciTech Connect

    Steckley, R.A.; Kronenberg, M.W.; Born, M.L.; Rhea, T.C.; Bateman, J.E.; Rollo, F.D.; Friesinger, G.C.

    1982-01-01

    Regional wall motion (RWM) abnormalities are sensitive indicators of left ventricular (LV) dysfunction, but quantitation of RWM with gated radionuclide ventriculography (RVG) has been limited, particularly in the left anterior oblique (LAO) projection. Regional LV performance was studied in 18 patients undergoing LAO RVG immediately prior to contrast ventriculography (CVG). Wall motion was analyzed by semiautomated and visual methods using several coordinate systems. For semiautomated methods, RVG and CVG wall motion were closely related in the two 90/sup 0/ polar sectors at the apex and posterior wall r = .850 and in the five 45/sup 0/ polar sectors from midseptum through posterior wall (r = .82). The basal sectors on RVG had weak relationships to CVG, due to adjacent vascular structures. Semiautomated and visual grades for polar sectors on both CVG and RVG were closely related (r = .88-.94). Measured regional wall motion on LAO RVG compared favorably with near-simultaneous CVG in nonoverlapping portions of the LV and allowed objective quantitation of regional LV performance.

  11. A filtering method for signal equalization in region-of-interest fluoroscopy.

    PubMed

    Robert, Normand; Komljenovic, Philip T; Rowlands, J A

    2002-05-01

    A method to significantly reduce the exposure area product in fluoroscopy using a pre-patient region-of-interest (ROI) attenuator is presented. The attenuator has a thin central region and a gradually increasing thickness away from the center. It is shown that the unwanted brightening artifact caused by the attenuator can be eliminated by attenuating the low spatial frequencies in the detected image using digital image processing techniques. An investigation of the best image processing method to correct for the presence of the attenuator is undertaken. The correction procedure selected is suitable for use with real-time image processors and the ROI attenuator can be permitted to move during image acquisition. Images of an anthropomorphic chest phantom acquired in the presence of the ROI attenuator using an x-ray image intensifier/video chain are corrected to illustrate the clinical feasibility of our approach. PMID:12033570

  12. Empowering Women for Development through Community-Driven Sustainable Programmes: A Response to Traditional Patriarchal Power in the Southern African Region

    ERIC Educational Resources Information Center

    Braimoh, Dele; Lekoko, Rebecca; Alade, Eunice B.

    2004-01-01

    In the Southern Africa region, the act of prejudice against women mostly occurs where patriarchal power reigns. This type of power is felt in areas such as inheritance right, division of labour, access to political and economic resources and legal and social matters. Other areas of discrimination against women include access to educational and…

  13. H.U.B city steps: methods and early findings from a community-based participatory research trial to reduce blood pressure among african americans

    PubMed Central

    2011-01-01

    Background Community-based participatory research (CBPR) has been recognized as an important approach to develop and execute health interventions among marginalized populations, and a key strategy to translate research into practice to help reduce health disparities. Despite growing interest in the CBPR approach, CBPR initiatives rarely use experimental or other rigorous research designs to evaluate health outcomes. This behavioral study describes the conceptual frameworks, methods, and early findings related to the reach, adoption, implementation, and effectiveness on primary blood pressure outcomes. Methods The CBPR, social support, and motivational interviewing frameworks are applied to test treatment effects of a two-phased CBPR walking intervention, including a 6-month active intervention quasi experimental phase and 12-month maintenance randomized controlled trial phase to test dose effects of motivational interviewing. A community advisory board helped develop and execute the culturally-appropriate intervention components which included social support walking groups led by peer coaches, pedometer diary self-monitoring, monthly diet and physical activity education sessions, and individualized motivational interviewing sessions. Although the study is on-going, three month data is available and reported. Analyses include descriptive statistics and paired t tests. Results Of 269 enrolled participants, most were African American (94%) females (85%) with a mean age of 43.8 (SD = 12.1) years. Across the 3 months, 90% of all possible pedometer diaries were submitted. Attendance at the monthly education sessions was approximately 33%. At the 3-month follow-up 227 (84%) participants were retained. From baseline to 3-months, systolic BP [126.0 (SD = 19.1) to 120.3 (SD = 17.9) mmHg; p < 0.001] and diastolic BP [83. 2 (SD = 12.3) to 80.2 (SD = 11.6) mmHg; p < 0.001] were significantly reduced. Conclusions This CBPR study highlights implementation factors and signifies

  14. Dynamic modeling of tourism by stochastic method: a case of the Beijing-Tianjin-Hebei region

    NASA Astrophysics Data System (ADS)

    Dai, Juan; Zhang, Shihui; Xue, Chongsheng

    2009-10-01

    As an efficient way to stimulate the growth of economy, tourism is promoted by most counties allover the world, and has become one of the world's largest and fastest-growing industries. Essentially, tourism is a spatiotemporal system, with tourist attractions located in different geographic areas and tourist flows exchanging between different geographic regions. In this paper, we present a dynamic model for the simulation of tourism and tourist's activities in the context of GIS and stochastic method, using a case of the Beijing-Tianjin-Hebei region. The model is developed on stochastic method and multiple geospatial data sources. In the model, the spatiotemporal behavior of tourist on the Earth's Surface is governed by the evolution rules, which are extracted from the researches on tourist's activities and executed via stochastic method and multiple geospatial data. By means of the model, we simulate the tourism in the Beijing-Tianjin- Hebei region, and find that there is good correspondence between the tourist arrivals calculated with the model and those obtained from the tourism statistics. This shows that the animated dynamic modeling of tourism based on geospatial data can be used as an indicator of the tourism in the realistic world, and is also can be embedded in the GIS applications.

  15. A Novel Method for Identification and Quantification of Consistently Differentially Methylated Regions

    PubMed Central

    Hsiao, Ching-Lin; Hsieh, Ai-Ru; Lian, Ie-Bin; Lin, Ying-Chao; Wang, Hui-Min; Fann, Cathy S. J.

    2014-01-01

    Advances in biotechnology have resulted in large-scale studies of DNA methylation. A differentially methylated region (DMR) is a genomic region with multiple adjacent CpG sites that exhibit different methylation statuses among multiple samples. Many so-called “supervised” methods have been established to identify DMRs between two or more comparison groups. Methods for the identification of DMRs without reference to phenotypic information are, however, less well studied. An alternative “unsupervised” approach was proposed, in which DMRs in studied samples were identified with consideration of nature dependence structure of methylation measurements between neighboring probes from tiling arrays. Through simulation study, we investigated effects of dependencies between neighboring probes on determining DMRs where a lot of spurious signals would be produced if the methylation data were analyzed independently of the probe. In contrast, our newly proposed method could successfully correct for this effect with a well-controlled false positive rate and a comparable sensitivity. By applying to two real datasets, we demonstrated that our method could provide a global picture of methylation variation in studied samples. R source codes to implement the proposed method were freely available at http://www.csjfann.ibms.sinica.edu.tw/eag/programlist/ICDMR/ICDMR.html. PMID:24818602

  16. Quantification of Rifaximin in Tablets by Spectrophotometric Method Ecofriendly in Ultraviolet Region

    PubMed Central

    2016-01-01

    Rifaximin is an oral nonabsorbable antibiotic that acts locally in the gastrointestinal tract with minimal systemic adverse effects. It does not have spectrophotometric method ecofriendly in the ultraviolet region described in official compendiums and literature. The analytical techniques for determination of rifaximin reported in the literature require large amount of time to release results and are significantly onerous. Furthermore, they use toxic reagents both for the operator and environment and, therefore, cannot be considered environmentally friendly analytical techniques. The objective of this study was to develop and validate an ecofriendly spectrophotometric method in the ultraviolet region to quantify rifaximin in tablets. The method was validated, showing linearity, selectivity, precision, accuracy, and robustness. It was linear over the concentration range of 10–30 mg L−1 with correlation coefficients greater than 0.9999 and limits of detection and quantification of 1.39 and 4.22 mg L−1, respectively. The validated method is useful and applied for the routine quality control of rifaximin, since it is simple with inexpensive conditions and fast in the release of results, optimizes analysts and equipment, and uses environmentally friendly solvents, being considered a green method, which does not prejudice either the operator or the environment. PMID:27429835

  17. A novel method for estimating the number of species within a region.

    PubMed

    Shtilerman, Elad; Thompson, Colin J; Stone, Lewi; Bode, Michael; Burgman, Mark

    2014-03-22

    Ecologists are often required to estimate the number of species in a region or designated area. A number of diversity indices are available for this purpose and are based on sampling the area using quadrats or other means, and estimating the total number of species from these samples. In this paper, a novel theory and method for estimating the number of species is developed. The theory involves the use of the Laplace method for approximating asymptotic integrals. The method is shown to be successful by testing random simulated datasets. In addition, several real survey datasets are tested, including forests that contain a large number (tens to hundreds) of tree species, and an aquatic system with a large number of fish species. The method is shown to give accurate results, and in almost all cases found to be superior to existing tools for estimating diversity. PMID:24500169

  18. A novel method for estimating the number of species within a region

    PubMed Central

    Shtilerman, Elad; Thompson, Colin J.; Stone, Lewi; Bode, Michael; Burgman, Mark

    2014-01-01

    Ecologists are often required to estimate the number of species in a region or designated area. A number of diversity indices are available for this purpose and are based on sampling the area using quadrats or other means, and estimating the total number of species from these samples. In this paper, a novel theory and method for estimating the number of species is developed. The theory involves the use of the Laplace method for approximating asymptotic integrals. The method is shown to be successful by testing random simulated datasets. In addition, several real survey datasets are tested, including forests that contain a large number (tens to hundreds) of tree species, and an aquatic system with a large number of fish species. The method is shown to give accurate results, and in almost all cases found to be superior to existing tools for estimating diversity. PMID:24500169

  19. African and non-African admixture components in African Americans and an African Caribbean population.

    PubMed

    Murray, Tanda; Beaty, Terri H; Mathias, Rasika A; Rafaels, Nicholas; Grant, Audrey Virginia; Faruque, Mezbah U; Watson, Harold R; Ruczinski, Ingo; Dunston, Georgia M; Barnes, Kathleen C

    2010-09-01

    Admixture is a potential source of confounding in genetic association studies, so it becomes important to detect and estimate admixture in a sample of unrelated individuals. Populations of African descent in the US and the Caribbean share similar historical backgrounds but the distributions of African admixture may differ. We selected 416 ancestry informative markers (AIMs) to estimate and compare admixture proportions using STRUCTURE in 906 unrelated African Americans (AAs) and 294 Barbadians (ACs) from a study of asthma. This analysis showed AAs on average were 72.5% African, 19.6% European and 8% Asian, while ACs were 77.4% African, 15.9% European, and 6.7% Asian which were significantly different. A principal components analysis based on these AIMs yielded one primary eigenvector that explained 54.04% of the variation and captured a gradient from West African to European admixture. This principal component was highly correlated with African vs. European ancestry as estimated by STRUCTURE (r(2)=0.992, r(2)=0.912, respectively). To investigate other African contributions to African American and Barbadian admixture, we performed PCA on approximately 14,000 (14k) genome-wide SNPs in AAs, ACs, Yorubans, Luhya and Maasai African groups, and estimated genetic distances (F(ST)). We found AAs and ACs were closest genetically (F(ST)=0.008), and both were closer to the Yorubans than the other East African populations. In our sample of individuals of African descent, approximately 400 well-defined AIMs were just as good for detecting substructure as approximately 14,000 random SNPs drawn from a genome-wide panel of markers. PMID:20717976

  20. Genome-wide Ancestry Association Testing Identifies a Common European Variant on 6q14.1 as a Risk Factor for Asthma in African Americans

    PubMed Central

    Torgerson, Dara G.; Capurso, Daniel; Ampleford, Elizabeth J.; Li, Xingnan; Moore, Wendy C.; Gignoux, Christopher R.; Hu, Donglei; Eng, Celeste; Mathias, Rasika A.; Busse, William W.; Castro, Mario; Erzurum, Serpil C.; Fitzpatrick, Anne M.; Gaston, Benjamin; Israel, Elliot; Jarjour, Nizar N.; Teague, W. Gerald; Wenzel, Sally E.; Rodríguez-Santana, José R.; Rodríguez-Cintrón, William; Avila, Pedro C.; Ford, Jean G.; Barnes, Kathleen C.; Burchard, Esteban G.; Howard, Timothy D.; Bleecker, Eugene R.; Meyers, Deborah A.; Cox, Nancy J.; Ober, Carole; Nicolae, Dan L.

    2012-01-01

    Background Genetic variants that contribute to asthma susceptibility may be present at varying frequencies in different populations, which is an important consideration and advantage for performing genetic association studies in admixed populations. Objective To identify asthma-associated loci in African Americans. Methods We compared local African and European ancestry estimated from dense single nucleotide polymorphism (SNP) genotype data in African American adults with asthma and non-asthmatic controls. Allelic tests of association were performed within the candidate regions identified, correcting for local European admixture. Results We identified a significant ancestry association peak on chromosomes 6q. Allelic tests for association within this region identified a SNP (rs1361549) on 6q14.1 that was associated with asthma exclusively in African Americans with local European admixture (OR=2.2). The risk allele is common in Europe (42% in the HapMap CEU) but absent in West Africa (0% in the HapMap YRI), suggesting the allele is present in African Americans due to recent European admixture. We replicated our findings in Puerto Ricans and similarly found that the signal of association is largely specific to individuals who are heterozygous for African and non-African ancestry at 6q14.1. However, we found no evidence for association in European Americans or in Puerto Ricans in the absence of local African ancestry, suggesting that the association with asthma at rs1361549 is due to an environmental or genetic interaction. Conclusion We identified a novel asthma-associated locus that is relevant to admixed populations with African ancestry, and highlight the importance of considering local ancestry in genetic association studies of admixed populations. PMID:22607992

  1. Tree-ring δ18O in African mahogany (Entandrophragma utile) records regional precipitation and can be used for climate reconstructions

    NASA Astrophysics Data System (ADS)

    van der Sleen, Peter; Groenendijk, Peter; Zuidema, Pieter A.

    2015-04-01

    The availability of instrumental climate data in West and Central Africa is very restricted, both in space and time. This limits the understanding of the regional climate system and the monitoring of climate change and causes a need for proxies that allow the reconstruction of paleoclimatic variability. Here we show that oxygen isotope values (δ18O) in tree rings of Entandrophragma utile from North-western Cameroon correlate to precipitation on a regional to sub-continental scale (1930-2009). All found correlations were negative, following the proposed recording of the 'amount effect' by trees in the tropics. The capacity of E. utile to record the variability of regional precipitation is also confirmed by the significant correlation of tree-ring δ18O with river discharge data (1944-1983), outgoing longwave radiation (a proxy for cloud cover; 1974-2011) and sea surface salinity in the Gulf of Guinea (1950-2011). Furthermore, the high values in the δ18O chronology from 1970 onwards coincide with the Sahel drought period. Given that E. utile presents clear annual growth rings, has a wide-spread distribution in tropical Africa and is long lived (> 250 years), we argue that the analysis of oxygen isotopes in growth rings of this species is a promising tool for the study of paleoclimatic variability during the last centuries in West and Central Africa.

  2. Method for high-accuracy reflectance measurements in the 2.5-microm region.

    PubMed

    Richter, Rudolf; Müller, Andreas

    2003-02-20

    Reflectance measurement with spectroradiometers in the solar wavelength region (0.4-2.5 microm) are frequently conducted in the laboratory or in the field to characterize surface materials of artificial and natural targets. The spectral surface reflectance is calculated as the ratio of the signals obtained over the target surface and a reference panel, yielding a relative reflectance value. If the reflectance of the reference panel is known, the absolute target reflectance can be computed. This standard measurement technique assumes that the signal at the radiometer is due completely to reflected target and reference radiation. However, for field measurements in the 2.4-2.5-microm region with the Sun as the illumination source, the emitted thermal radiation is not a negligible part of the signal even at ambient temperatures, because the atmospheric transmittance, and thus the solar illumination level, is small in the atmospheric absorption regions. A new method is proposed that calculates reflectance values in the 2.4-2.5-microm region while it accounts for the reference panel reflectance and the emitted radiation. This technique needs instruments with noise-equivalent radiances of 2 orders of magnitude below currently commercially available instruments and requires measurement of the surface temperatures of target and reference. If the reference panel reflectance and temperature effects are neglected, the standard method yields reflectance errors up to 0.08 and 0.15 units for 7- and 2-nm bandwidth instruments, respectively. For the new method the corresponding errors can be reduced to approximately 0.01 units for the surface temperature range of 20-35 degrees C. PMID:12617226

  3. Influence of CYP2C9 Genotype on warfarin dose among African American and European Americans.

    PubMed

    Limdi, Na; Goldstein, Ja; Blaisdell, Ja; Beasley, Tm; Rivers, Ca; Acton, Rt

    2007-05-01

    BACKGROUND: Cytochrome P4502C9 (CYP2C9) plays a vital role in drug metabolism. There has been an increased effort to identify polymorphisms within the gene and determine their clinical consequences. However, most of these efforts have focused on populations of European descent. Herein we report the influence of CYP2C9 genotype on warfarin dose among European American and African American patients. We also identify two new mutations; one in the coding region and one in the non-coding region of the CYP2C9 gene. METHODS: Patients (≥20 years of age) are enrolled after obtaining medical, lifestyle and concomitant medication history. Changes in International Normalized Ratio (INR), warfarin dose, co-medications, diet, physical activity and the occurrence of complications are documented. CYP2C9 genotype was determined using PCR-RFLP and pyrosequencing. Differences in genotype frequencies and HWE assumptions were assessed using χ(2) statistics and exact tests. The genotype dose association was evaluated using multivariable linear regression. RESULTS: This report includes 490 patients (mean age 60.6 ± 15.6, 51.3% men). African American patients comprise 48.9% of the cohort with mean follow-up of 13.5 (±10.6) months. Both the CYP2C9 *2 and *3 allele were more frequent in European Americans (11.24%, 5.1%) compared to African Americans (1.1% and 1.8%). CYP2C9 *5 (0.9%), *6 (0.4%), and *11 (1.1%) variants were only observed in African Americans. The variant genotype is more frequent among European Americans compared to African Americans (29.8% vs. 9.73%, p<0.0001). Warfarin dose was significantly related to CYP2C9 genotype (p<0.0001) both in univariate and multivariate analyses. Multivariable race-specific analyses highlight the contribution of CYP2C9 genotype among European American but not among African American patients. CONCLUSION: The variant CYP2C9 genotype is more frequent among European Americans compared to African Americans. Among African Americans the variant

  4. Using the Method of Water Poverty Index (WPI) to Evaluate the Region Water Security

    NASA Astrophysics Data System (ADS)

    Fu, Q.; Kachanoski, G.

    2008-12-01

    Water security is a widely concerned issue in the world nowadays. A new method, water poverty index (WPI), has been used to evaluate the regional water security. Twelve state farms in Heilongjiang Province, Northeastern China were selected to evaluate water security status based on the data of 2006 by using WPI and mean deviation grading method. The method of WPI includes five key indexes, such as resources(R), access (A), capacity(C), utilization (U) and environment (E). Each key index includes several sub-indexes. According to the results of WPI, the grade of each farm has been calculated by using the method of mean deviation grading. Thus, the radar images can be protracted of each farm. From the radar images, the conclusions can be drawn that the WPI values of Farms 853 and Hongqiling were in very safe status, while that of Farm Raohe was in safe status, those of Farms Youyi, 597, 852, 291 and Jiangchuan were in moderate safe status, that of Farm Beixing was in low safe status and those of Farms Shuangyashan, Shuguang and Baoshan were in unsafe status. The results from this study can provide basic information for decision making on rational use of water resources and regulations for regional water safety guarantee system.

  5. Regional Characterization of Soil Properties via a Combination of Methods from Remote Sensing, Geophysics and Geopedology

    NASA Astrophysics Data System (ADS)

    Meyer, Uwe; Fries, Elke; Frei, Michaela

    2016-04-01

    Soil is one of the most precious resources on Earth. Preserving, using and enriching soils are most complex processes that fundamentally need a sound regional data base. Many countries lack this sort of extensive data or the existing data must be urgently updated when land use recently changed in major patterns. The project "RECHARBO" (Regional Characterization of Soil Properties) aims at the combination of methods from remote sensing, geophysics and geopedology in order to develop a new system to map soils on a regional scale in a quick and efficient manner. First tests will be performed on existing soil monitoring districts, using newly available sensing systems as well as established techniques. Especially hyperspectral and infrared data measured from satellites or airborne platforms shall be combined. Moreover, a systematic correlation between hyperspectral imagery and gamma-ray spectroscopy shall be established. These recordings will be compared and correlated to measurements upon ground and on soil samples to get hold of properties such as soil moisture, soil density, specific resistance plus analytic properties like clay content, anorganic background, organic matter etc. The goal is to generate a system that enables users to map soil patterns on a regional scale using airborne or satellite data and to fix their characteristics with only a limited number of soil samples.

  6. A wavelet-based method to exploit epigenomic language in the regulatory region

    PubMed Central

    Nguyen, Nha; Vo, An; Won, Kyoung-Jae

    2014-01-01

    Motivation: Epigenetic landscapes in the regulatory regions reflect binding condition of transcription factors and their co-factors. Identifying epigenetic condition and its variation is important in understanding condition-specific gene regulation. Computational approaches to explore complex multi-dimensional landscapes are needed. Results: To study epigenomic condition for gene regulation, we developed a method, AWNFR, to classify epigenomic landscapes based on the detected epigenomic landscapes. Assuming mixture of Gaussians for a nucleosome, the proposed method captures the shape of histone modification and identifies potential regulatory regions in the wavelet domain. For accuracy estimation as well as enhanced computational speed, we developed a novel algorithm based on down-sampling operation and footprint in wavelet. We showed the algorithmic advantages of AWNFR using the simulated data. AWNFR identified regulatory regions more effectively and accurately than the previous approaches with the epigenome data in mouse embryonic stem cells and human lung fibroblast cells (IMR90). Based on the detected epigenomic landscapes, AWNFR classified epigenomic status and studied epigenomic codes. We studied co-occurring histone marks and showed that AWNFR captures the epigenomic variation across time. Availability and implementation: The source code and supplemental document of AWNFR are available at http://wonk.med.upenn.edu/AWNFR. Contact: wonk@mail.med.upenn.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24096080

  7. Methods for assessing hydrogeological similarity and for classification of groundwater systems on the regional scale

    NASA Astrophysics Data System (ADS)

    Haaf, Ezra; Barthel, Roland

    2015-04-01

    Conducting groundwater modelling and resource analysis on the regional scale is often complicated by the scarcity and uneven distribution of observations over space and time, the uncertainty of structures, inputs and processes as well as the inherent heterogeneity and variability of hydrogeological conditions. In order to improve modelling and prediction of poorly-observed groundwater systems, information could be transferred from similar, but more well-explored and better understood systems analogous to PUB (Prediction in ungauged catchments). To achieve this, the overarching goal of this study is to develop an approach to statistically extract relevant information on structure and state from observed and well characterized locations in order to derive a classification scheme of functionally similar groups. At the core of the approach will be the classification of (i) static hydrogeological characteristics (such as aquifer geometry and hydraulic properties) (ii) dynamic changes of the boundary conditions (such as recharge) and (iii) dynamic groundwater system responses (groundwater head and chemical parameters) as well as the systematic use of the dependencies of system responses on explanatory factors. With a classification framework in place, insight can be gained into the behavior of less well-observed groundwater systems and underlying processes can be better understood. Furthermore, it is expected that regional conceptual models can be checked without the need of numerical groundwater models as well as that missing values in time series can be filled. Apart from illustrating the general approach and the main ideas of groundwater systems classification, we show a number of promising methods that can be used to establish a classification framework for groundwater systems assessment. The focus at the current stage is on finding relevant statistical methods that can be used for identifying and quantifying similarities/dissimilarities of groundwater hydrographs

  8. Rain-induced emission pulses of NOx and HCHO from soils in African regions after dry spells as viewed by satellite sensors

    NASA Astrophysics Data System (ADS)

    Zörner, Jan; Penning de Vries, Marloes; Beirle, Steffen; Veres, Patrick; Williams, Jonathan; Wagner, Thomas

    2014-05-01

    Outside industrial areas, soil emissions of NOx (stemming from bacterial emissions of NO) represent a considerable fraction of total NOx emissions, and may even dominate in remote tropical and agricultural areas. NOx fluxes from soils are controlled by abiotic and microbiological processes which depend on ambient environmental conditions. Rain-induced spikes in NOx have been observed by in-situ measurements and also satellite observations. However, the estimation of soil emissions over broad geographic regions remains uncertain using bottom-up approaches. Independent, global satellite measurements can help constrain emissions used in chemical models. Laboratory experiments on soil fluxes suggest that significant HCHO emissions from soil can occur. However, it has not been previously attempted to detect HCHO emissions from wetted soils by using satellite observations. This study investigates the evolution of tropospheric NO2 (as a proxy for NOx) and HCHO column densities before and after the first rain fall event following a prolonged dry period in semi-arid regions, deserts as well as tropical regions in Africa. Tropospheric NO2 and HCHO columns retrieved from OMI aboard the AURA satellite, GOME-2 aboard METOP and SCIAMACHY aboard ENVISAT are used to study and inter-compare the observed responses of the trace gases with multiple space-based instruments. The observed responses are prone to be affected by other sources like lightning, fire, influx from polluted air masses, as well measurement errors in the satellite retrieval caused by manifold reasons such as an increased cloud contamination. Thus, much care is taken verify that the observed spikes reflect enhancements in soil emissions. Total column measurements of H2O from GOME-2 give further insight into the atmospheric state and help to explain the increase in humidity before the first precipitation event. The analysis is not only conducted for averages of distinct geographic regions, i.e. the Sahel, but also

  9. An Evaluation of Two Hydrograph Separation Methods of Potential Use in Regional Water Quality Assessment

    SciTech Connect

    Huff, D.D.

    1999-01-01

    Streamflow data are more useful for evaluating hydrologic model results and studying water quality once baseflow and storm runoff have been separated. However, it is important to select an appropriate hydrograph separation method. They examined tow methods and evaluated their conceptual basis, ease of application, cost of data processing, and acceptability of results. they chose the quick flow hydrograph separation method, which is in use at the Coweeta Hydrologic Laboratory, because it gives acceptable results and is easy and inexpensive to use. For regional assessment, they anticipate that the Coweeta program will be useful as an aid in developing general quantitative relationships between changes in land use and the associated changes in surface runoff yield and water quality degradation.

  10. Effect of background and transport dose on the results of the personal dose equivalent Hp(10) measurements in photon fields obtained during the intercomparison 2013 of the African region.

    PubMed

    Arib, M; Herrati, A; Dari, F; Lounis-Mokrani, Z

    2015-12-01

    As part of the intercomparison on the measurement of personal dose equivalent Hp(10), jointly organised by the International Atomic Energy Agency and the Algerian Secondary Standard Dosimetry Laboratory, for the African region, up to 12 dosemeters were added to the packages of the 28 participants to evaluate the background and transport dose (BGTD), received by the dosemeters before and after their irradiation at the SSDL (environmental irradiations, scanning process at the airports, etc.). Out of the 28 participants, only 17 reported the corresponding BGTD measured values, which lied between 0.03 and 0.8 mSv. The mean measured value of BG was (0.25±0.14) mSv, which is significantly high compared with the lowest dose value used in the intercomparison exercise. The BGTD correction shifted the overall results of the intercomparison from an overestimation of dose (∼8 % before applying BGT dose correction) to an underestimation of dose (-9 % after correction). The measurement protocol and the detailed analysis of the results and applied corrections are discussed in this paper. PMID:25433048

  11. Grid-Search Location Methods for Ground-Truth Collection from Local and Regional Seismic Networks

    SciTech Connect

    Schultz, C A; Rodi, W; Myers, S C

    2003-07-24

    The objective of this project is to develop improved seismic event location techniques that can be used to generate more and better quality reference events using data from local and regional seismic networks. Their approach is to extend existing methods of multiple-event location with more general models of the errors affecting seismic arrival time data, including picking errors and errors in model-based travel-times (path corrections). Toward this end, they are integrating a grid-search based algorithm for multiple-event location (GMEL) with a new parameterization of travel-time corrections and new kriging method for estimating the correction parameters from observed travel-time residuals. Like several other multiple-event location algorithms, GMEL currently assumes event-independent path corrections and is thus restricted to small event clusters. The new parameterization assumes that travel-time corrections are a function of both the event and station location, and builds in source-receiver reciprocity and correlation between the corrections from proximate paths as constraints. The new kriging method simultaneously interpolates travel-time residuals from multiple stations and events to estimate the correction parameters as functions of position. They are currently developing the algorithmic extensions to GMEL needed to combine the new parameterization and kriging method with the simultaneous location of events. The result will be a multiple-event location method which is applicable to non-clustered, spatially well-distributed events. They are applying the existing components of the new multiple-event location method to a data set of regional and local arrival times from Nevada Test Site (NTS) explosions with known origin parameters. Preliminary results show the feasibility and potential benefits of combining the location and kriging techniques. They also show some preliminary work on generalizing of the error model used in GMEL with the use of mixture

  12. A multi-method analysis of cyclone activity in the Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Trigo, Isabel F.; Liberato, Margarida L. R.; Nissen, Katrin; Pinto, Joaquim G.; Lionello, Piero; Trigo, Ricardo M.; Ulbrich, Sven; Ulbrich, Uwe; Ordóñez, Paulina

    2013-04-01

    The Mediterranean Basin is a particularly active region in terms of cyclone formation and development. The geographical features of the area, including its location between the mid-latitudes and the sub-tropics, the almost closed sea and the mountain ranges near the coast play an important role determining the dominant meteorological characteristics of the region. This study revisits monthly climatologies of Mediterranean storms through the analysis of databases obtained from multiple methods for cyclone identification and tracking. Within the context of the IMILAST project, these methodologies were all applied to fields provided by ERA-Int reanalysis, available 6-hourly and at 0.75° x 0.75° spatial resolution. They consist of a set of objective criteria to identify cyclone signatures near the surface, through the search for minima in mean sea level pressure or 1000 hPa geopotential height, or for vorticity maxima at 850 hPa. The tracking is then performed through the analysis of centres identified in consecutive time slots and imposing a set of a priory conditions on the maximum velocity admissible for mid-latitude cyclones. The distributions of cyclone characteristics obtained from the different databases are analysed focusing on system duration, intensity and velocity. The spatial distributions and density of cyclone centres are also compared among the different storm-track databases, with particular emphasis on the location of the most active regions in terms of cyclogenesis. These are generally well defined in the Mediterranean region, being mostly determined by orographic features mentioned above and land-sea temperature gradients. As such, methodologies tend to agree in the areas that favour cyclone formation, particularly during winter months, while discrepancies among methods tend to be mostly related to number of detections. Finally, we make a critical analysis of some of the options/criteria within each methodology that favour or not the identification

  13. Acceptability of a Community-Based Outreach HIV-Testing Intervention Using Oral Fluid Collection Devices and Web-Based HIV Test Result Collection Among Sub-Saharan African Migrants: A Mixed-Method Study

    PubMed Central

    Manirankunda, Lazare; Platteau, Tom; Albers, Laura; Fransen, Katrien; Vermoesen, Tine; Namanya, Fiona; Nöstlinger, Christiana

    2016-01-01

    Background Late human immunodeficiency virus (HIV) diagnosis is common among sub-Saharan African migrants. To address their barriers to HIV testing uptake and improve timely HIV diagnoses and linkage to care, the outreach HIV testing intervention, “swab2know,” was developed. It combined a community-based approach with innovative testing methods: oral fluid self-sampling and the choice between Web-based HIV test result collections using a secured website or post-test counseling at a sexual health clinic. The sessions included an informational speech delivered by a physician of sub-Saharan African origin and testimonies by community members living with HIV. Objectives The objectives of this study were to evaluate the intervention’s acceptability among sub-Saharan African migrants and its potential to reach subgroups at higher risk for HIV infection and to identify facilitators and barriers for HIV testing uptake. Methods This mixed-method study combined qualitative (participant observations and informal interviews with testers and nontesters) and quantitative data (paper–pencil survey, laboratory data, and result collection files). Data were analyzed using a content analytical approach for qualitative and univariate analysis for quantitative data. Results A total of 10 testing sessions were organized in sub-Saharan African migrant community venues in the city of Antwerp, Belgium, between December 2012 and June 2013. Overall, 18.2% of all people present (N=780) underwent HIV testing; 29.8% of them tested for HIV for the first time, 22.3% did not have a general practitioner, and 21.5% reported 2 or more sexual partners (last 3 months). Overall, 56.3% of participants chose to collect their HIV test results via the protected website. In total, 78.9% collected their results. The qualitative analysis of 137 participant observation field notes showed that personal needs and Internet literacy determined the choice of result collection method. Generally, the oral

  14. Application of GIS and remote sensing methods to the paleohydrography of the Paso del Norte region

    NASA Astrophysics Data System (ADS)

    Kennedy, John F.

    The purpose of this project is to use geographic information system (GIS) and remote sensing methods to investigate the paleohydrology of the Paso del Norte region during the latest pluvial event. During the research I gathered the best available geologic and hydrographic data sets and integrated these data within a GIS in order to create a digital paleohydrologic database for the region. In particular, I used the GIS to reconstruct the hydrography (i.e. streams, lakes, and watershed boundaries) that existed as a results of increased precipitation and a decrease in temperature in the recent geologic past. The existence of the pluvial lakes had an impact on ground-water and surface-water flow systems in this region. The results of my research are presented as two papers ready for peer-review publication submission and a third paper that is a previously published work. (1) Using GIS and Remote Sensing to Reconstruct Late Quaternary and Early Holocene Paleo-Hydrography Using Climate Data and Modern Topography---an Example from the Southwestern US. This paper describes the methods used to create a paleo-hydrography system for the Paso del Norte region, and the development of a water-balance equation that estimates the inputs and outputs of this system. (2) Estimating Water-Balance Equation for Playas in the Tularosa Basin of Southern New Mexico. This paper describes the calibration and testing of the GIS model presented in the first paper. Before it can be applied to paleohydrologic systems, it must be shown to reasonably approximate playa systems in the region under current conditions. Water balances were calculated for several playas and their associated drainages. (3) The Hydrogeologic Framework of Basin-Fill Aquifers and Associated Ground-water flow Systems in Southwestern New Mexico---An Overview. The paper is an overview of work done by many hydrogeologists in the Paso del Norte region; however, the primary source of most of our current knowledge is based on the

  15. Adaptive region of interest method for analytical micro-CT reconstruction.

    PubMed

    Yang, Wanneng; Xu, Xiaochun; Bi, Kun; Zeng, Shaoqun; Liu, Qian; Chen, Shangbin

    2011-01-01

    The real-time imaging is important in automatic successive inspection with micro-computerized tomography (micro-CT). Generally, the size of the detector is chosen according to the most probable size of the measured object to acquire all the projection data. Given enough imaging area and imaging resolution of X-ray detector, the detector is larger than specimen projection area, which results in redundant data in the Sinogram. The process of real-time micro-CT is computation-intensive because of the large amounts of source and destination data. The speed of the reconstruction algorithm can't always meet the requirements of real-time applications. A preprocessing method called adaptive region of interest (AROI), which detects the object's boundaries automatically to focus the active Sinogram regions, is introduced into the analytical reconstruction algorithm in this paper. The AROI method reduces the volume of the reconstructing data and thus directly accelerates the reconstruction process. It has been further shown that image quality is not compromised when applying AROI, while the reconstruction speed is increased as the square of the ratio of the sizes of the detector and the specimen slice. In practice, the conch reconstruction experiment indicated that the process is accelerated by 5.2 times with AROI and the imaging quality is not degraded. Therefore, the AROI method improves the speed of analytical micro-CT reconstruction significantly. PMID:21422587

  16. A method for the quantitative evaluation of SAR distribution in deep regional hyperthermia.

    PubMed

    Baroni, C; Giri, M G; Meliadó, G; Maluta, S; Chierego, G

    2001-01-01

    The Specific Absorption Rate (SAR) distribution pattern visualization by a matrix of E-field light-emitting sensors has demonstrated to be a useful tool to evaluate the characteristics of the applicators used in deep regional hyperthermia and to perform a quality assurance programme. A method to quantify the SAR from photographs of the sensor array--the so-called 'Power Stepping Technique'--has already been proposed. This paper presents a new approach to the quantitative determination of the SAR profiles in a liquid phantom exposed to electromagnetic fields from the Sigma-60 applicator (BSD-2000 system for deep regional hyperthermia). The method is based on the construction of a 'calibration curve' modelling the light-output of an E-field sensor as a function of the supplied voltage and on the use of a reference light source to 'normalize' the light-output readings from the photos of the sensor array, in order to minimize the errors introduced by the non-uniformity of the photographic process. Once the calibration curve is obtained, it is possible, with only one photo, to obtain the quantitative SAR distribution in the operating conditions. For this reason, this method is suitable for equipment characterization and also for the control of the repeatability of power deposition in time. PMID:11587076

  17. A METHOD FOR DATA-DRIVEN SIMULATIONS OF EVOLVING SOLAR ACTIVE REGIONS

    SciTech Connect

    Cheung, Mark C. M.; DeRosa, Marc L.

    2012-10-01

    We present a method for performing data-driven simulations of solar active region formation and evolution. The approach is based on magnetofriction, which evolves the induction equation assuming that the plasma velocity is proportional to the Lorentz force. The simulations of active region (AR) coronal field are driven by temporal sequences of photospheric magnetograms from the Helioseismic Magnetic Imager instrument on board the Solar Dynamics Observatory (SDO). Under certain conditions, the data-driven simulations produce flux ropes that are ejected from the modeled AR due to loss of equilibrium. Following the ejection of flux ropes, we find an enhancement of the photospheric horizontal field near the polarity inversion line. We also present a method for the synthesis of mock coronal images based on a proxy emissivity calculated from the current density distribution in the model. This method yields mock coronal images that are somewhat reminiscent of images of ARs taken by instruments such as SDO's Atmospheric Imaging Assembly at extreme ultraviolet wavelengths.

  18. Evaluation of surface geophysical methods for collection of hydrogeologic data in the Nebraska Sand Hills region

    USGS Publications Warehouse

    Ellis, M.J.; Hiergesell, R.A.

    1985-01-01

    The practicality of using surface geophysical methods for obtaining geohydrologic data in the Nebraska Sand Hills region was studied during the summer of 1984. Seismic refraction and electrical-resistivity equipment were used, because an evaluation of geohydrologic data indicated that results of surveys made with this equipment probably would yield the most useful data. The study area, which included parts of Garfield, Holt, and Wheeler Counties, was selected because it is geohydrologically representative of the eastern part of the Sand Hills region, and because sufficient geohydrologic data were available for use in evaluating the results of geophysical surveys. Geophysical methods were evaluated for their ability to consistently detect selected geohydrologic horizons. These horizons in descending order, are: the water table, the top of Quaternary silt beds, the top of Quaternary sand and gravel beds , the top of the Tertiary Ogallala Formation, and the top of the Cretaceous Pierre Shale. The top of the Pierre Shale generally is the base of the aquifer, which consists of all of the 500 to 700 ft of overlying deposits. Evaluations of the geophysical data indicate that seismic refraction surveys are best suited for determining the depth to the water table, but are not effective in studying beds below the water table. Vertical electrical soundings provided data on the depth to water table and the top of the silt beds. Available geohydrologic data, however, indicate that with some changes in data collection or interpretation techniques, it may be possible to obtain information on the top of the sand and gravel deposits, the top of the Ogallala Formation, and the top of the Pierre Shale with vertical electrical soundings. Use of either geophysical method could enhance the results of geohydrologic investigations in the Nebraska Sand Hills region. (Author 's abstract)

  19. 16 Extraordinary African Americans.

    ERIC Educational Resources Information Center

    Lobb, Nancy

    This collection for children tells the stories of 16 African Americans who helped make America what it is today. African Americans can take pride in the heritage of these contributors to society. Biographies are given for the following: (1) Sojourner Truth, preacher and abolitionist; (2) Frederick Douglass, abolitionist; (3) Harriet Tubman, leader…

  20. African Studies Computer Resources.

    ERIC Educational Resources Information Center

    Kuntz, Patricia S.

    African studies computer resources that are readily available in the United States with linkages to Africa are described, highlighting those most directly corresponding to African content. Africanists can use the following four fundamental computer systems: (1) Internet/Bitnet; (2) Fidonet; (3) Usenet; and (4) dial-up bulletin board services. The…

  1. African Literature as Celebration.

    ERIC Educational Resources Information Center

    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)

  2. Educating African American Males

    ERIC Educational Resources Information Center

    Bell, Edward E.

    2010-01-01

    Background: Schools across America spend money, invest in programs, and sponsor workshops, offer teacher incentives, raise accountability standards, and even evoke the name of Obama in efforts to raise the academic achievement of African American males. Incarceration and college retention rates point to a dismal plight for many African American…

  3. Africans Away from Home.

    ERIC Educational Resources Information Center

    Clarke, John Henrik

    Africans who were brought across the Atlantic as slaves never fully adjusted to slavery or accepted its inevitability. Resistance began on board the slave ships, where many jumped overboard or committed suicide. African slaves in South America led the first revolts against tyranny in the New World. The first slave revolt in the Caribbean occurred…

  4. Keeping African Masks Real

    ERIC Educational Resources Information Center

    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…

  5. African American Men and College: Understanding How They Succeed

    ERIC Educational Resources Information Center

    Gilkey, Eschelle

    2012-01-01

    Scope and Method of Study: This study used qualitative methods to discover the reasons and factors these African American men persisted to degree completion, while the large majority of this group fail. The participants for this study were eight African American males who have successfully graduated from an accredited, predominantly white…

  6. A Numerical Method for Obtaining Monoenergetic Neutron Flux Distributions and Transmissions in Multiple-Region Slabs

    NASA Technical Reports Server (NTRS)

    Schneider, Harold

    1959-01-01

    This method is investigated for semi-infinite multiple-slab configurations of arbitrary width, composition, and source distribution. Isotropic scattering in the laboratory system is assumed. Isotropic scattering implies that the fraction of neutrons scattered in the i(sup th) volume element or subregion that will make their next collision in the j(sup th) volume element or subregion is the same for all collisions. These so-called "transfer probabilities" between subregions are calculated and used to obtain successive-collision densities from which the flux and transmission probabilities directly follow. For a thick slab with little or no absorption, a successive-collisions technique proves impractical because an unreasonably large number of collisions must be followed in order to obtain the flux. Here the appropriate integral equation is converted into a set of linear simultaneous algebraic equations that are solved for the average total flux in each subregion. When ordinary diffusion theory applies with satisfactory precision in a portion of the multiple-slab configuration, the problem is solved by ordinary diffusion theory, but the flux is plotted only in the region of validity. The angular distribution of neutrons entering the remaining portion is determined from the known diffusion flux and the remaining region is solved by higher order theory. Several procedures for applying the numerical method are presented and discussed. To illustrate the calculational procedure, a symmetrical slab ia vacuum is worked by the numerical, Monte Carlo, and P(sub 3) spherical harmonics methods. In addition, an unsymmetrical double-slab problem is solved by the numerical and Monte Carlo methods. The numerical approach proved faster and more accurate in these examples. Adaptation of the method to anisotropic scattering in slabs is indicated, although no example is included in this paper.

  7. Validate the universal pattern decomposition method using satellite data acquired over the Three Gorges region

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Fujiwara, N.; Furumi, S.; Muramatsu, K.; Daigo, M.; Zhang, L.

    2005-10-01

    The universal pattern decomposition method (UPDM) has been successfully applied to simulated data for Landsat/ETM+, Terra/MODIS, ADEOS-II/GLI and 92 bands-CONTINUE sensors using ground-measured data. This paper validates the UPDM using MODIS and ETM+ data acquired over the Three Gorges region of China. The reduced 2 values of selected area D, that with the smallest terrain influences, are 0.000409 (MODIS) and 0.000181 (ETM+), and the average linear regression factor between MODIS and ETM+ is 1.0077, with rms 0.0082. The results demonstrated that the UPDM coefficients are sensor-independent.

  8. Diabetes in African Americans

    PubMed Central

    Marshall, M

    2005-01-01

    African Americans have a high risk for type 2 diabetes. Genetic traits, the prevalence of obesity, and insulin resistance all contribute to the risk of diabetes in the African American community. African Americans have a high rate of diabetic complications, because of poor glycaemic control and racial disparities in health care in the USA. African Americans with diabetes may have an atypical presentation that simulates type 1 diabetes, but then their subsequent clinical course is typical of type 2 diabetes. Culturally sensitive strategies, structured disease management protocols, and the assistance of nurses, diabetic educators, and other health care professionals are effective in improving the outcome of diabetes in the African American community. PMID:16344294

  9. African American Faculty Expressing Concerns: Breaking the Silence at Predominantly White Research Oriented Universities

    ERIC Educational Resources Information Center

    Ross, Henry H.; Edwards, Willie J.

    2016-01-01

    A Delphi method was used with a panel of 24 African American faculty employed at 43 predominantly white doctoral extensive universities to arrive at a group consensus on a list of concerns that African American faculty in general experienced or held. Using the Delphi method a panel of African American faculty initially worked from a list of eight…

  10. Comparison of GPS-TEC with IRI-2012 TEC over African equatorial and low latitude regions during the period of 2012-2013

    NASA Astrophysics Data System (ADS)

    Tariku, Yekoye Asmare

    2015-10-01

    This paper presents the performance of the latest version of the International Reference Ionosphere (IRI-2012) model in estimating the Vertical Total Electron Content (VTEC) variation over equatorial and low latitude East Africa regions during the period of 2012-2013. This has been conducted by comparing the ground-based Global Positioning System (GPS) VTEC inferred from nine dual frequency GPS receivers installed at different regions in the continent. In this work, the diurnal, monthly and seasonal variation in the measured VTEC have been analyzed and compared with the VTEC obtained from IRI-2012 model. It is depicted that the lowest diurnal peaks of the modeled and measured VTEC values are observed in the June solstice months, whereas the highest values are observed in the equinoctial months. The variability of the diurnal GPS-VTEC is also found to be minimal nearly at 03:00 UT and maximal mostly between 09:00 and 14:00 UT. Moreover, the maximum and minimum monthly mean hourly measured VTEC values inferred from both the Arba Minch and Entebbe stations are observed in October and July, respectively. Similarly, the highest and the lowest seasonal mean hourly measured VTEC values are observed in the September equinox and in the June solstice, respectively. The model predictions generally follow the diurnal variations of the measured VTEC, with minimum value at predawn hours and maximum at noontime hours (10:00-13:00 UT). It has been shown that the model better estimates the diurnal VTEC values mostly just after midnight hours (00:00-03:00 UT). Good agreements between the modeled and measured monthly and seasonal mean hourly VTEC values obtained from Arba Minch station are also observed in the equinoctial months. But, for the Entebbe station, the modeled monthly and seasonal VTEC values are larger than the corresponding measured VTEC values by about 75% and 60%, respectively. In addition, there are large discrepancies observed between the diurnal measured and modeled

  11. Globally convergent trust-region methods for self-consistent field electronic structure calculations.

    PubMed

    Francisco, Juliano B; Martínez, José Mario; Martínez, Leandro

    2004-12-01

    As far as more complex systems are being accessible for quantum chemical calculations, the reliability of the algorithms used becomes increasingly important. Trust-region strategies comprise a large family of optimization algorithms that incorporates both robustness and applicability for a great variety of problems. The objective of this work is to provide a basic algorithm and an adequate theoretical framework for the application of globally convergent trust-region methods to electronic structure calculations. Closed shell restricted Hartree-Fock calculations are addressed as finite-dimensional nonlinear programming problems with weighted orthogonality constraints. A Levenberg-Marquardt-like modification of a trust-region algorithm for constrained optimization is developed for solving this problem. It is proved that this algorithm is globally convergent. The subproblems that ensure global convergence are easy-to-compute projections and are dependent only on the structure of the constraints, thus being extendable to other problems. Numerical experiments are presented, which confirm the theoretical predictions. The structure of the algorithm is such that accelerations can be easily associated without affecting the convergence properties. PMID:15634038

  12. An analysis of region-of-influence methods for flood regionalization in the Gulf-Atlantic Rolling Plains

    USGS Publications Warehouse

    Eng, K.; Tasker, Gary D.; Milly, P.C.D.

    2005-01-01

    Region-of-influence (RoI) approaches for estimating streamflow characteristics at ungaged sites were applied and evaluated in a case study of the 50-year peak discharge in the Gulf-Atlantic Rolling Plains of the southeastern United States. Linear regression against basin characteristics was performed for each ungaged site considered based on data from a region of influence containing the n closest gages in predictor variable (PRoI) or geographic (GRoI) space. Augmentation of this count based cutoff by a distance based cutoff also was considered. Prediction errors were evaluated for an independent (split-sampled) dataset. For the dataset and metrics considered here: (1) for either PRoI or GRoI, optimal results were found when the simpler count based cutoff, rather than the distance augmented cutoff, was used; (2) GRoI produced lower error than PRoI when applied indiscriminately over the entire study region; (3) PRoI performance improved considerably when RoI was restricted to predefined geographic subregions.

  13. Regional Comparisons of Coastal Sediment Contamination Detected by a Biomarker (P450 HRGS; EPA Method 4425)

    SciTech Connect

    Anderson, Jack W.; Hartwell, S I.; Hameedi, M J.

    2005-01-01

    Pollution investigations by the Center for Coastal Assessment and Monitoring of the National Oceanic and Atmospheric Administration (NOAA) have been conducted since 1984 and have incorporated extensive biological and chemical analyses. Since 1993, one of the suites of biological tests utilized in these studies has been the biomarker P450HRGS, which is more recently referred to as EPA Method 4425. Extracts of sediments are applied to a human cell line with a reporter gene at the CYP1A1 site. Light produced by the extracts is a function of the concentrations and potencies of those compounds with an affinity for Ah-receptor (polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], dioxins/furans). These compounds are carcinogenic, can produce chronic toxicity, and those containing chlorine are persistent and bioaccumulated. Nineteen coastal regions and 1309 samples from the three U.S. coasts have been evaluated as part of the NOAA investigations. The stratified random sampling approach used by NOAA provides estimates of the areas (km2) of each region containing levels of the compounds above thresholds. From analysis of the data base, sediments with concentrations at or below 11 ?g benzo[a]pyrene equivalents (B[a]PEq)/g would not be expected to produce effects on the benthos. At 32 ?g B[a]PEq/g and above there is the potential for impacts on the biota, and above 60 ?g/g, the degradation of the benthic community has been observed. Several of the regional surveys found no samples at or above 60 ?g B[a]PEq/g, but 60% of the samples from New York Harbor (280 km2) were above this level. Analyses of data from Puget Sound and Chesapeake Bay demonstrate an increase in samples above 32 ?g B[a]PEq/g in more populated and industrial regions. A targeted investigation of the distribution of the three important classes of compounds identified by Method 4425 would be more cost effective by first screening samples by this method before expending substantial funds in

  14. Obtaining optic disc center and pixel region by automatic thresholding methods on morphologically processed fundus images.

    PubMed

    Marin, Diego; Gegundez-Arias, Manuel E; Suero, Angel; Bravo, Jose M

    2015-02-01

    Development of automatic retinal disease diagnosis systems based on retinal image computer analysis can provide remarkably quicker screening programs for early detection. Such systems are mainly focused on the detection of the earliest ophthalmic signs of illness and require previous identification of fundal landmark features such as optic disc (OD), fovea or blood vessels. A methodology for accurate center-position location and OD retinal region segmentation on digital fundus images is presented in this paper. The methodology performs a set of iterative opening-closing morphological operations on the original retinography intensity channel to produce a bright region-enhanced image. Taking blood vessel confluence at the OD into account, a 2-step automatic thresholding procedure is then applied to obtain a reduced region of interest, where the center and the OD pixel region are finally obtained by performing the circular Hough transform on a set of OD boundary candidates generated through the application of the Prewitt edge detector. The methodology was evaluated on 1200 and 1748 fundus images from the publicly available MESSIDOR and MESSIDOR-2 databases, acquired from diabetic patients and thus being clinical cases of interest within the framework of automated diagnosis of retinal diseases associated to diabetes mellitus. This methodology proved highly accurate in OD-center location: average Euclidean distance between the methodology-provided and actual OD-center position was 6.08, 9.22 and 9.72 pixels for retinas of 910, 1380 and 1455 pixels in size, respectively. On the other hand, OD segmentation evaluation was performed in terms of Jaccard and Dice coefficients, as well as the mean average distance between estimated and actual OD boundaries. Comparison with the results reported by other reviewed OD segmentation methodologies shows our proposal renders better overall performance. Its effectiveness and robustness make this proposed automated OD location and

  15. Haplotype kernel association test as a powerful method to identify chromosomal regions harboring uncommon causal variants.

    PubMed

    Lin, Wan-Yu; Yi, Nengjun; Lou, Xiang-Yang; Zhi, Degui; Zhang, Kui; Gao, Guimin; Tiwari, Hemant K; Liu, Nianjun

    2013-09-01

    For most complex diseases, the fraction of heritability that can be explained by the variants discovered from genome-wide association studies is minor. Although the so-called "rare variants" (minor allele frequency [MAF] < 1%) have attracted increasing attention, they are unlikely to account for much of the "missing heritability" because very few people may carry these rare variants. The genetic variants that are likely to fill in the "missing heritability" include uncommon causal variants (MAF < 5%), which are generally untyped in association studies using tagging single-nucleotide polymorphisms (SNPs) or commercial SNP arrays. Developing powerful statistical methods can help to identify chromosomal regions harboring uncommon causal variants, while bypassing the genome-wide or exome-wide next-generation sequencing. In this work, we propose a haplotype kernel association test (HKAT) that is equivalent to testing the variance component of random effects for distinct haplotypes. With an appropriate weighting scheme given to haplotypes, we can further enhance the ability of HKAT to detect uncommon causal variants. With scenarios simulated according to the population genetics theory, HKAT is shown to be a powerful method for detecting chromosomal regions harboring uncommon causal variants. PMID:23740760

  16. Development and application of methods for regional scaling and normalization in life-cycle impact assessment

    SciTech Connect

    Tolle, D.A.

    1995-12-31

    Life-cycle impact assessment (LCIA) is a technical, quantitative and/or qualitative method to classify, characterize, and valuate potential impacts on human health, ecosystems, and natural resources, based on the environmental burdens identified in a life-cycle inventory. Research described here for two LCIAs included development and application of regional scaling methods for the following 5 of 14 relevant impact categories: Suspended (PM{sub 10}) particulate effects, water use, acid deposition, smog creation, and eutrophication. Normalization is recommended after characterization, because aggregated sums per impact category need to be expressed in equivalent terms before assigning valuation weight factors. The normalization approach described here involves determination of factors that represent the total, geographically-relevant impact for a given impact category. The goal for the 14 normalization factors developed and applied to two LCIAS, was to make them scientifically defensible, while utilizing existing data on emission or resource extraction quantities for three spatial perspectives. Data on the total environmental burden for each inventory item under a given impact category were obtained for normalization factors. Since the boundaries of the two LCIAs were primarily in the US, the data for the regional or local impact category perspectives were restricted to appropriate areas in the US. Normalization factors were developed and applied in the two LCIAs for 11 impact categories involving chemical emissions, water use, solid waste volume, and resource extraction/production land use.

  17. A Method Of Evaluating A Subsurface Region Using Gather Sensitive Data Discrimination

    DOEpatents

    Lazaratos, Spyridon K.

    2000-01-11

    A method of evaluating a subsurface region by separating/enhancing a certain type of seismic event data of interest from an overall set of seismic event data which includes other, different types of seismic event data is disclosed herein. In accordance with one feature, a particular type of gather is generated from the seismic event data such that the gather includes at least a portion of the data which is of interest and at least a portion of the other data. A series of data discrimination lines are incorporated into the gather at positions and directions which are established in the gather in a predetermined way. Using the data discrimination lines, the data of interest which is present in the gather is separated/enhanced with respect to the other data within the gather. The separated data may be used for example in producing a map of the particular subterranean region. In accordance with another feature, the gather is selected such that the incorporated discrimination lines approach a near parallel relationship with one another. Thereby, the data is transformed in a way which causes the discrimination lines to be parallel with one another, resulting in reduced frequency distortion accompanied by improved accuracy in the separation/enhancement of data. In accordance with still another feature, the disclosed data separation/enhancement method is compatible with an iterative approach.

  18. Detection of sarcocystis parasites in retail beef: a regional survey combining histological and genetic detection methods.

    PubMed

    Pritt, Bobbi; Trainer, Thomas; Simmons-Arnold, Linda; Evans, Mark; Dunams, Detiger; Rosenthal, Benjamin M

    2008-10-01

    Sarcocystis spp. are parasitic protists acquired when undercooked, cyst-laden meat is consumed. While both Sarcocystis hominis and S. cruzi encyst in beef, only S. hominis is pathogenic to humans. In this study, we used histological methods and novel molecular techniques to determine the regional prevalence and identity of Sarcocystis spp. in retail beef. Of 110 samples, 60 supported amplification of parasite rRNA by PCR. All 41 sequenced representatives were identified as S. cruzi. To compare detection methods, 48 samples were then examined in parallel by histology and PCR, and 16 and 26 samples, respectively, were positive. Five samples positive by initial histologic sections were not amplified by PCR. Fifteen PCR-positive samples did not contain sarcocysts on initial histologic section, but additional sections from these samples revealed sarcocysts in an additional 12 samples. When combined, histology with additional sections and PCR detected 31 positive specimens of the 48 total specimens. We found no evidence of human pathogen S. hominis and confirm that cattle pathogen S. cruzi is highly prevalent in this regional sample. PCR assays may increase the detection sensitivity of Sarcocystis spp. and contribute diagnostic precision. PMID:18939769

  19. Haplotype Kernel Association Test as a Powerful Method to Identify Chromosomal Regions Harboring Uncommon Causal Variants

    PubMed Central

    Lin, Wan-Yu; Yi, Nengjun; Lou, Xiang-Yang; Zhi, Degui; Zhang, Kui; Gao, Guimin; Tiwari, Hemant K.; Liu, Nianjun

    2014-01-01

    For most complex diseases, the fraction of heritability that can be explained by the variants discovered from genome-wide association studies is minor. Although the so-called ‘rare variants’ (minor allele frequency [MAF] < 1%) have attracted increasing attention, they are unlikely to account for much of the ‘missing heritability’ because very few people may carry these rare variants. The genetic variants that are likely to fill in the ‘missing heritability’ include uncommon causal variants (MAF < 5%), which are generally untyped in association studies using tagging single-nucleotide polymorphisms (SNPs) or commercial SNP arrays. Developing powerful statistical methods can help to identify chromosomal regions harboring uncommon causal variants, while bypassing the genome-wide or exome-wide next-generation sequencing. In this work, we propose a haplotype kernel association test (HKAT) that is equivalent to testing the variance component of random effects for distinct haplotypes. With an appropriate weighting scheme given to haplotypes, we can further enhance the ability of HKAT to detect uncommon causal variants. With scenarios simulated according to the population genetics theory, HKAT is shown to be a powerful method for detecting chromosomal regions harboring uncommon causal variants. PMID:23740760

  20. The use of satellite data assimilation methods in regional NWP for solar irradiance forecasting

    NASA Astrophysics Data System (ADS)

    Kurzrock, Frederik; Cros, Sylvain; Chane-Ming, Fabrice; Potthast, Roland; Linguet, Laurent; Sébastien, Nicolas

    2016-04-01

    As an intermittent energy source, the injection of solar power into electricity grids requires irradiance forecasting in order to ensure grid stability. On time scales of more than six hours ahead, numerical weather prediction (NWP) is recognized as the most appropriate solution. However, the current representation of clouds in NWP models is not sufficiently precise for an accurate forecast of solar irradiance at ground level. Dynamical downscaling does not necessarily increase the quality of irradiance forecasts. Furthermore, incorrectly simulated cloud evolution is often the cause of inaccurate atmospheric analyses. In non-interconnected tropical areas, the large amplitudes of solar irradiance variability provide abundant solar yield but present significant problems for grid safety. Irradiance forecasting is particularly important for solar power stakeholders in these regions where PV electricity penetration is increasing. At the same time, NWP is markedly more challenging in tropic areas than in mid-latitudes due to the special characteristics of tropical homogeneous convective air masses. Numerous data assimilation methods and strategies have evolved and been applied to a large variety of global and regional NWP models in the recent decades. Assimilating data from geostationary meteorological satellites is an appropriate approach. Indeed, models converting radiances measured by satellites into cloud properties already exist. Moreover, data are available at high temporal frequencies, which enable a pertinent cloud cover evolution modelling for solar energy forecasts. In this work, we present a survey of different approaches which aim at improving cloud cover forecasts using the assimilation of geostationary meteorological satellite data into regional NWP models. Various approaches have been applied to a variety of models and satellites and in different regions of the world. Current methods focus on the assimilation of cloud-top information, derived from infrared

  1. Genetic risk variants in African Americans with multiple sclerosis

    PubMed Central

    Isobe, Noriko; Gourraud, Pierre-Antoine; Harbo, Hanne F.; Caillier, Stacy J.; Santaniello, Adam; Khankhanian, Pouya; Maiers, Martin; Spellman, Stephen; Cereb, Nezih; Yang, SooYoung; Pando, Marcelo J.; Piccio, Laura; Cross, Anne H.; De Jager, Philip L.; Cree, Bruce A.C.; Hauser, Stephen L.

    2013-01-01

    Objectives: To assess the association of established multiple sclerosis (MS) risk variants in 3,254 African Americans (1,162 cases and 2,092 controls). Methods: Human leukocyte antigen (HLA)-DRB1, HLA-DQB1, and HLA-A alleles were typed by molecular techniques. Single nucleotide polymorphism (SNP) genotyping was conducted for 76 MS-associated SNPs and 52 ancestry informative marker SNPs selected throughout the genome. Self-declared ancestry was refined by principal component analysis of the ancestry informative marker SNPs. An ancestry-adjusted multivariate model was applied to assess genetic associations. Results: The following major histocompatibility complex risk alleles were replicated: HLA-DRB1*15:01 (odds ratio [OR] = 2.02 [95% confidence interval: 1.54–2.63], p = 2.50e-07), HLA-DRB1*03:01 (OR = 1.58 [1.29–1.94], p = 1.11e-05), as well as HLA-DRB1*04:05 (OR = 2.35 [1.26–4.37], p = 0.007) and the African-specific risk allele of HLA-DRB1*15:03 (OR = 1.26 [1.05–1.51], p = 0.012). The protective association of HLA-A*02:01 was confirmed (OR = 0.72 [0.55–0.93], p = 0.013). None of the HLA-DQB1 alleles were associated with MS. Using a significance threshold of p < 0.01, outside the major histocompatibility complex region, 8 MS SNPs were also found to be associated with MS in African Americans. Conclusion: MS genetic risk in African Americans only partially overlaps with that of Europeans and could explain the difference of MS prevalence between populations. PMID:23771490

  2. Video shot boundary detection using region-growing-based watershed method

    NASA Astrophysics Data System (ADS)

    Wang, Jinsong; Patel, Nilesh; Grosky, William

    2004-10-01

    In this paper, a novel shot boundary detection approach is presented, based on the popular region growing segmentation method - Watershed segmentation. In image processing, gray-scale pictures could be considered as topographic reliefs, in which the numerical value of each pixel of a given image represents the elevation at that point. Watershed method segments images by filling up basins with water starting at local minima, and at points where water coming from different basins meet, dams are built. In our method, each frame in the video sequences is first transformed from the feature space into the topographic space based on a density function. Low-level features are extracted from frame to frame. Each frame is then treated as a point in the feature space. The density of each point is defined as the sum of the influence functions of all neighboring data points. The height function that is originally used in Watershed segmentation is then replaced by inverting the density at the point. Thus, all the highest density values are transformed into local minima. Subsequently, Watershed segmentation is performed in the topographic space. The intuitive idea under our method is that frames within a shot are highly agglomerative in the feature space and have higher possibilities to be merged together, while those frames between shots representing the shot changes are not, hence they have less density values and are less likely to be clustered by carefully extracting the markers and choosing the stopping criterion.

  3. Investigation Into the Humaneness of Slaughter Methods for Guinea Pigs (Cavia porcelus) in the Andean Region.

    PubMed

    Limon, Georgina; Gonzales-Gustavson, Eloy A; Gibson, Troy J

    2016-01-01

    Guinea pigs (Cavia porcelus) are an important source of nonhuman animal protein in the Andean region of South America. Specific guidelines regarding the welfare of guinea pigs before and during slaughter have yet to be developed. This study critically assessed the humaneness of 4 different stunning/slaughter methods for guinea pigs: cervical neck dislocation (n = 60), electrical head-only stunning (n = 83), carbon dioxide (CO2) stunning (n = 21), and penetrating captive bolt (n = 10). Following cervical neck dislocation, 97% of guinea pigs had at least 1 behavioral or cranial/spinal response. Six percent of guinea pigs were classified as mis-stunned after electrical stunning, and 1% were classified as mis-stunned after captive bolt. Increased respiratory effort was observed during CO2 stunning. Apart from this finding, there were no other obvious behavioral responses that could be associated with suffering. Of the methods assessed, captive bolt was deemed the most humane, effective, and practical method of stunning guinea pigs. Cervical neck dislocation should not be recommended as a slaughter method for guinea pigs. PMID:26963642

  4. Investigation Into the Humaneness of Slaughter Methods for Guinea Pigs (Cavia porcelus) in the Andean Region

    PubMed Central

    Limon, Georgina; Gonzales-Gustavson, Eloy A.; Gibson, Troy J.

    2016-01-01

    Guinea pigs (Cavia porcelus) are an important source of nonhuman animal protein in the Andean region of South America. Specific guidelines regarding the welfare of guinea pigs before and during slaughter have yet to be developed. This study critically assessed the humaneness of 4 different stunning/slaughter methods for guinea pigs: cervical neck dislocation (n = 60), electrical head-only stunning (n = 83), carbon dioxide (CO2) stunning (n = 21), and penetrating captive bolt (n = 10). Following cervical neck dislocation, 97% of guinea pigs had at least 1 behavioral or cranial/spinal response. Six percent of guinea pigs were classified as mis-stunned after electrical stunning, and 1% were classified as mis-stunned after captive bolt. Increased respiratory effort was observed during CO2 stunning. Apart from this finding, there were no other obvious behavioral responses that could be associated with suffering. Of the methods assessed, captive bolt was deemed the most humane, effective, and practical method of stunning guinea pigs. Cervical neck dislocation should not be recommended as a slaughter method for guinea pigs. PMID:26963642

  5. Y chromosome lineages in men of west African descent.

    PubMed

    Torres, Jada Benn; Doura, Menahem B; Keita, Shomarka O Y; Kittles, Rick A

    2012-01-01

    The early African experience in the Americas is marked by the transatlantic slave trade from ∼1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called "Grain Coast" of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men from DC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30-40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sex-biased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations. PMID:22295064

  6. Y Chromosome Lineages in Men of West African Descent

    PubMed Central

    Keita, Shomarka O. Y.; Kittles, Rick A.

    2012-01-01

    The early African experience in the Americas is marked by the transatlantic slave trade from ∼1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called “Grain Coast” of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men from DC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30–40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sex-biased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations. PMID:22295064

  7. Prospects of electromagnetic methods application for evaluation of deep geothermal resources of intraplate regions

    NASA Astrophysics Data System (ADS)

    Pushkarev, P.; Khmelevskoy, V.; Golubtsova, N.

    2013-12-01

    Due to increase of demand for energy resources and development of technologies of their extraction, the number of regions, where geothermal resources are used, is growing. These resources were used in the areas with surface indications of geothermal activity, but now geothermal energy is exploited in the regions with no such indications and, which is more important, where deep temperatures are lower in most cases. Hereafter, usage of the Earth's deep heat may become effective everywhere, including intraplate regions and, in particular, cratons. However, here the depth of boreholes, required to reach temperatures 250 - 350 0C, making electricity production possible, should be about 10 km. Geothermal resources can be divided to hydrothermal and petrothermal. The former are connected with thermal groundwater. As soon as some groundwater deposits were depleted, recharge of reservoirs using reinjection boreholes was applied. Petrothermal resources are connected with deep hot dry rocks of intraplate regions, for their exploitation closed-loop petrothermal circulation systems (PCS) can be used. In such a system water is pumped into injecting well(s), gets hot in the reservoir, created by means of hydrofracturing, and is pumped out from exploitation well(s). When choosing a location for a PCS, the main criterion is proximity to a consumer of energy and, especially, of hot water for heating. However, efficiency of choice depends on structure, state and thermal regime of the interiors and can be increased by application of geophysical methods, including electromagnetic (EM). In general, application of EM methods is possible at three stages: 1) Regional studies, when zones of probable increase of deep temperatures are revealed; 2) Detailed explorations, near-surface and deep, in the area, selected for PCS construction; 3) Monitoring, for imaging of the reservoir during its creation and exploitation. Here we will concentrate on the first stage. The depth range of our interest

  8. Grid-Search Location Methods for Ground-Truth Collection From Local and Regional Seismic Networks

    SciTech Connect

    William Rodi; Craig A. Schultz; Gardar Johannesson; Stephen C. Myers

    2005-05-13

    This project investigated new techniques for improving seismic event locations derived from regional and local networks. The technqiues include a new approach to empirical travel-time calibration that simultaneously fits data from multiple stations and events, using a generalization of the kriging method, and predicts travel-time corrections for arbitrary event-station paths. We combined this calibration approach with grid-search event location to produce a prototype new multiple-event location method that allows the use of spatially well-distributed events and takes into account correlations between the travel-time corrections from proximate event-station paths. Preliminary tests with a high quality data set from Nevada Test Site explosions indicated that our new calibration/location method offers improvement over the conventional multiple-event location methods now in common use, and is applicable to more general event-station geometries than the conventional methods. The tests were limited, however, and further research is needed to fully evaluate, and improve, the approach. Our project also demonstrated the importance of using a realistic model for observational errors in an event location procedure. We took the initial steps in developing a new error model based on mixture-of-Gaussians probability distributions, which possess the properties necessary to characterize the complex arrival time error processes that can occur when picking low signal-to-noise arrivals. We investigated various inference methods for fitting these distributions to observed travel-time residuals, including a Markov Chain Monte Carlo technique for computing Bayesian estimates of the distribution parameters.

  9. Assessing the performance of regional landslide early warning models: the EDuMaP method

    NASA Astrophysics Data System (ADS)

    Calvello, M.; Piciullo, L.

    2015-10-01

    The paper proposes the evaluation of the technical performance of a regional landslide early warning system by means of an original approach, called EDuMaP method, comprising three successive steps: identification and analysis of the Events (E), i.e. landslide events and warning events derived from available landslides and warnings databases; definition and computation of a Duration Matrix (DuMa), whose elements report the time associated with the occurrence of landslide events in relation to the occurrence of warning events, in their respective classes; evaluation of the early warning model Performance (P) by means of performance criteria and indicators applied to the duration matrix. During the first step, the analyst takes into account the features of the warning model by means of ten input parameters, which are used to identify and classify landslide and warning events according to their spatial and temporal characteristics. In the second step, the analyst computes a time-based duration matrix having a number of rows and columns equal to the number of classes defined for the warning and landslide events, respectively. In the third step, the analyst computes a series of model performance indicators derived from a set of performance criteria, which need to be defined by considering, once again, the features of the warning model. The proposed method is based on a framework clearly distinguishing between local and regional landslide early warning systems as well as among correlation laws, warning models and warning systems. The applicability, potentialities and limitations of the EDuMaP method are tested and discussed using real landslides and w