Search results for "africa"

Eight-Membered Rings With Two Heteroatoms 1,2

2022

The chapter titled “Eight-membered Rings with two Heteroatoms 1,2” deals with heterocine rings with two heteroatoms in a 1,2 relationship, namely 1,2-diazocine, 2H-1,2-oxazocine, 2H-1,2-thiazocine, 1,2-dioxocin, 1,2-oxathiocin and 1,2-dithiocin. This article covers the literature from 2007 to 2019 and reports the chemistry of uncondensed derivatives, heterocines fused to carbocycles and heterocycles, as well as bridged heterocines. As usual, in the case that a particular section is not mentioned, it means that no chemistry has been reported. In this article, the “Biosynthesis” paragraph was additionally introduced, since in the latest years the contribution of Nature to the synthesis of dih…

Anthropoid versus strepsirhine status of the African Eocene primates Algeripithecus and Azibius: craniodental evidence.

2009

Recent fossil discoveries have demonstrated that Africa and Asia were epicentres for the origin and/or early diversification of the major living primate lineages, including both anthropoids (monkeys, apes and humans) and crown strepsirhine primates (lemurs, lorises and galagos). Competing hypotheses favouring either an African or Asian origin for anthropoids rank among the most hotly contested issues in paleoprimatology. The Afrocentric model for anthropoid origins rests heavily on the >45 Myr old fossil Algeripithecus minutus from Algeria, which is widely acknowledged to be one of the oldest known anthropoids. However, the phylogenetic position of Algeripithecus with respect to other p…

The aspect of nationality and performance in a mountain ultra-marathon-the ‘Swiss Alpine Marathon’

2012

Eichenberger E, Knechtle B, Rust CA, Lepers R, Rosemann T, Onywera VO. The aspect of nationality and performance in a mountain ultra-marathon - the ‘Swiss Alpine Marathon’ J. Hum. Sport Exerc. Vol. 7, No. 4, pp. 748-762, 2012. Runners from East Africa and especially from Kenya dominate middle- and longdistance running races worldwide. The aim of the present study was to investigate the participation and performance trends regarding the nationality of runners in a mountain ultra-marathon held in partially high alpine terrain. We hypothesized that Kenyan runners, living and training in the Great Rift Valley, a predominantly hilly, mountainous and altitudinous region like the Alps, would domin…

Performance of Kenyan athletes in mountain versus flat marathon running - An example in Switzerland

2013

Harm, C., Knechtle, B., Rust, A.C., Rosemann, T., Lepers, R. & Onywera, V. (2013). Performance of Kenyan athletes in mountain versus flat marathon running - An example in Switzerland. J. Hum. Sport Exerc., 8(4), pp.881-893. The purpose of this study was to compare running performance of Kenyans in a flat city marathon and a mountain marathon in Switzerland. Running times of top three overall Kenyan runners were compared with running times of top three overall runners of other nations in a mountain and a flat marathon held in Switzerland between 2003 and 2011. In the mountain marathon top three male Kenyans achieved with 199±23min the 11th fastest running time behind athletes from Italy (177…

Participation and performance trends of East-African runners in Swiss half-marathons and marathons held between 2000 and 2010.

2013

Abstract Background This study examined the changes in participation, performance and age of East African runners competing in half-marathons and marathons held in Switzerland between 2000 and 2010. Methods Race times, sex, age and origin of East African versus Non-African finishers of half-marathon and marathon finishers were analyzed. Results Across time, the number of Kenyan and Ethiopian finishers remained stable (P > 0.05) while the number of Non-African finishers increased for both women and men in both half-marathons and marathons (P < 0.05). In half-marathons, the top ten African women (71 ± 1.4 min) and top three (62.3 ± 0.6 min) and top ten (62.8 ± 0.4 min) African men were …

Carbon isotope stratigraphy, magnetostratigraphy, and 40Ar/39Ar age of the Cretaceous South Atlantic coast, Namibe Basin, Angola

2014

This publication results from Projecto PaleoAngola, an international cooperative research effort among the contributing authors and their institutions, funded by the National Geographic Society, the Petroleum Research Fund of the American Chemical Society, Sonangol E.P., Esso Angola, Fundacao Vida of Angola, LS Films, Maersk, Damco, Safmarine, ISEM at SMU, The Royal Dutch Embassy in Luanda, TAP Airlines, Royal Dutch Airlines, The Saurus Institute, and the Perot Museum of Nature and Science. JS was additionally funded by Yale University and the Alfred Kordelin Foundation. We dedicate this contribution to the late Kalunga Lima, our friend and colleague in Projecto PaleoAngola. We thank Margar…

Errors and uncertainties introduced by a regional climate model in climate impact assessments: example of crop yield simulations in West Africa

2015

16 pages; International audience; The challenge of estimating the potential impacts of climate change has led to an increasing use of dynamical downscaling to produce fine spatial-scale climate projections for impact assessments. In this work, we analyze if and to what extent the bias in the simulated crop yield can be reduced by using the Weather Research and Forecasting (WRF) regional climate model to downscale ERA-Interim (European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis) rainfall and radiation data. Then, we evaluate the uncertainties resulting from both the choice of the physical parameterizations of the WRF model and its internal variability. Impact assessments w…

2017

Summary Objectives Neisseria meningitidis is the major cause of seasonal meningitis epidemics in the African meningitis belt. In the changing context of a reduction in incidence of serogroup A and an increase in incidence of serogroups W and C and of Streptococcus pneumoniae , a better understanding of the determinants driving the disease transmission dynamics remains crucial to improving bacterial meningitis control. Methods The literature was searched to provide a multi-disciplinary overview of the determinants of meningitis transmission dynamics in the African meningitis belt. Results Seasonal hyperendemicity is likely predominantly caused by increased invasion rates, sporadic localized …

Data from: Fine-scale spatial genetic dynamics over the life-cycle of the tropical tree Prunus africana

2014

Studying fine-scale spatial genetic patterns across life stages is a powerful approach to identify ecological processes acting within tree populations. We investigated spatial genetic dynamics across five life stages in the insect-pollinated and vertebrate-dispersed tropical tree Prunus africana in Kakamega Forest, Kenya. Using six highly polymorphic microsatellite loci, we assessed genetic diversity and spatial genetic structure (SGS) from seed rain and seedlings, and different sapling stages to adult trees. We found significant SGS in all stages, potentially caused by limited seed dispersal and high recruitment rates in areas with high light availability. SGS decreased from seed and early…

Exposing Empirical Links between COVID-19 Situation Report and Available Data: The Case of Nigeria

2020

Ever since the index case of COVID-19 was announced in Nigeria, the number of confirmed cases has gradually increased to 46,140 (about 4.5% of total confirmed cases in Africa) as the time of writing this article. This seemingly low number of confirmed cases has provoked heated debates among researchers. This cross-sectional study explores the Nigerian COVID-19 report to expose some links between the number of confirmed cases, testing, and some environmental conditions. The findings reveal that there is no state in Nigeria which has up to 12 confirmed cases per 10,000 population. That means, the number of confirmed COVID-19 cases is less than 0.15% of the population of people across each sta…