Moored current meter data at BBL dynamic structure studies of the North-West Africa shelf and continental slope

2002 ◽  
Author(s):  
T.A. Demidova ◽  
T.B. Tsybaneva
Keyword(s):  
West Africa ◽  
Continental Slope ◽  
Dynamic Structure ◽  
North West ◽  
The North ◽  
Moored Current Meter Data

The Ecology of epidemic Sleeping Sickness. I.—The Significance of Location

1951 ◽  
Vol 42 (2) ◽  
pp. 427-443 ◽  
Author(s):  
K. R. S. Morris
Keyword(s):  
West Africa ◽  
Intrinsic Value ◽  
Sleeping Sickness ◽  
Control Measures ◽  
Tsetse Flies ◽  
Linear Distribution ◽  
Trade Routes ◽  
North West ◽  
The North ◽  
Upper Volta

A combination of historical, geographical, and epidemiological studies has given sufficient insight into the ecology of sleeping sickness to enable the main factors influencing the development and spread of an epidemic to be traced.The evidence shows that in West Africa sleeping sickness is not primarily a disease of the forest, where tsetse flies are most abundant, but belongs essentially to the dry country in the north of the savanna woodland zone, where the earliest occurrences and severest outbreaks have been located.The first mention of sleeping sickness comes from the upper Niger and dates back to the 14th century. By the beginning of the present century intense though localised epidemics were devastating parts of the Mossi, Grounsi and Lobi country of the upper Volta rivers. At this time the disease was unknown on the coast and of sporadic occurrence only in the forest. A severe trans-Volta epidemic covering 60,000 square miles, developed between 1924 and 1940, but was confined to the north of the inland savanna zone with nothing comparable in the forest.The epidemic spread in three principal ways : (1) Outwards from original foci of infection because of the dynamic nature of the disease. This produced a concentration of infection around headwaters, a feature characteristic of advanced epidemics. (2) Through the agency of travellers, originally from north to south but subsequently in both directions : a rapid method of spread producing linear distribution of infection along trade routes. The tempo was greatly increased on the pacification and development of West Africa after 1900. (3) A gradual southward shift in the main epidemic zone appears to be resulting from a long-term change in the African climate which is combining with man's activities to produce a southerly extension of xerophytic vegetation types and a regression of forest.The most important spread was that caused by the trading caravans, more especially the cola traders, who have been coming down to the cola-nut areas in the Ashanti forest from the big markets on the Niger and Upper Volta since the 11th century. The caravans were formerly very large, up to one or two thousand strong, and were frequently made up of Mossi and Grounsi from the territory that was so heavily infected by the beginning of the present century. It is certain that a continuous introduction of infection would have been taking place into the forest ever since trypanosomiasis was prevalent in the north, that is for 100 years at least. And infection has been known in the forest for about that period, yet always to a mild degree, never reaching epidemic form. It has been sought for, because conditions in the forest, with the vector Glossina palpalis in contact with every village and path, appeared to be ideal for the transmission of infection and this drew the particular attention of the early workers from 1908 onwards. But the most that could be found was a threatened epidemic in north-west Ashanti, very significantly centering on the big cola markets which formed the termini for the northern traders.This historical evidence and the reasoning from epidemiology lead to the conclusion that conditions in the forest are not conducive to the development of epidemic sleeping sickness and that the low state of endemicity found there is maintained by the constant introduction of infection from the true epidemic areas in northern savanna.From this conclusion arises a practical point of the greatest importance. If the sources from which infection is introduced into the forest could be eliminated the disease there should eventually die out and the tsetse, from the human point of view, would be harmless. Tsetse control in the forest may prove difficult and expensive, and if it is attempted by clearing this might end in the literal destruction of the forest. Such measures would be hard to justify, so many other factors of possibly greater importance than trypanosomiasis are involved, both the intrinsic value of a forest for its products and the wider value through its influence on climate, soil and water.In formulating a plan for the control of sleeping sickness, the habits of both vectors, human as well as insect, should be considered. The tsetse plays a major role in the development of the high infection rates characterising the epidemic outbreaks in northern savanna ; the human vector distributes infection from these sources along trade routes and into the forest. The elimination of the disease at its source, in true epidemic centres, which can be most effectively accomplished by eradication of the tsetse, will check the distribution of infections to the secondary areas of lighter infection which could then be cleared up by quite minor control measures or might even disappear spontaneously.This plan is now in operation in the Gold Coast. The validity of the arguments on which it was based is being shown by the results that are already apparent : the high rates of reduction in the epidemic areas and the pronounced lowering of infection in neighbouring, uncontrolled areas, more particularly in the forest region of north-west Ashanti where it is entered by a trade route coming from the previously heavily infected country.

scholarly journals Characterization of groundrolls in the North-West of Niger Delta Nigeria, West Africa

2018 ◽  
Vol 27 (4) ◽  
pp. 541-552
Author(s):  
S.A. Ugwu ◽  
C.N. Nwankwo ◽  
J.O. Sule
Keyword(s):  
West Africa ◽  
Niger Delta ◽  
North West ◽  
The North

Social Administration of the Kru. A Preliminary Survey

Africa ◽  
1937 ◽  
Vol 10 (1) ◽  
pp. 75-96 ◽  
Author(s):  
H. Scudder Mekeel
Keyword(s):  
West Africa ◽  
West African ◽  
Preliminary Survey ◽  
The South ◽  
North West ◽  
North East ◽  
The North ◽  
Archaeological Work ◽  
Opening Paragraph ◽  
Physical Type

Opening ParagraphThe Kru, a West African Negro group, inhabit the central and southern part of Liberia. They are surrounded by the Basa peoples to the north-west, by the Grebo to the south-east and by the Putu to the north-east. The informant, Thomas Tarbour (Sieh Tagbweh), from whom the following material was derived, was a native of Grand Cess (Siglipo), a large coast town near the border of the Grebo country. The Kru, along with other related groups in that part of West Africa, have a tradition of having migrated from far to the north-east. The physical type is that of the short, stocky Bush negro. No archaeological work has been done in the region, and such ethnological material as has been collected is a mere beginning.

Metal Content in Small Pelagic Fish in the North-West Africa

2019 ◽  
Vol 35 (2) ◽  
pp. 643-653 ◽  
Author(s):  
Enrique Lozano-Bilbao ◽  
Yanira Díaz ◽  
Gonzalo Lozano ◽  
Alba Jurado-Ruzafa ◽  
Arturo Hardisson ◽  
...  
Keyword(s):  
West Africa ◽  
Metal Content ◽  
Pelagic Fish ◽  
Small Pelagic Fish ◽  
North West ◽  
The North

Development stage and season influence in the metal content of small pelagic fish in the North-West Africa

Chemosphere ◽  
2020 ◽  
Vol 261 ◽  
pp. 127692
Author(s):  
Enrique Lozano-Bilbao ◽  
Alba Jurado-Ruzafa ◽  
Gonzalo Lozano ◽  
Sebastián Jiménez ◽  
Arturo Hardisson ◽  
...  
Keyword(s):  
West Africa ◽  
Metal Content ◽  
Development Stage ◽  
Pelagic Fish ◽  
Small Pelagic Fish ◽  
North West ◽  
The North

XV.—On some Cretaceous Brachiopoda and Mollusca from Angola, Portuguese West Africa

1917 ◽  
Vol 51 (3) ◽  
pp. 561-580 ◽  
Author(s):  
R. Bullen Newton
Keyword(s):  
West Africa ◽  
Important Paper ◽  
North West ◽  
Limited Knowledge ◽  
Railway Company ◽  
The North ◽  
Small Collection ◽  
The Subject

The following notes have been prepared as the result of a study of a small collection of fossils belonging chiefly to the Pelecypoda and Gastropoda, which were obtained by Professor J. W. Gregory, F.R.S., from the Cretaceous rocks of the neighbourhood of Lobito Bay, situated to the north of Benguella, in the province of Angola. At first sight the specimens appeared to be of too unsatisfactory a character for determination, on account of their fragmentary condition, besides often consisting of natural casts. From a closer examination, however, it has been possible to trace some details of structure which have afforded clues to the identification of certain genera and species, a record of which will assist in extending our present limited knowledge of the Cretaceous conchology of this region of Africa. During the progress of these researches, a few further specimens from the same locality were added to Professor Gregory's collection, having been specially obtained by Mr E. Robins, of the Benguella Railway Company. So far as the literature of the subject is concerned, we appear to be indebted to the memoirs of Professor Paul Choffat of Lisbon for most of our information on the Cretaceous fauna of Angola, although reference should also be made to a small and important paper by M. Stanislas Meunier issued in 1888, which contains the earliest known figures of Cretaceous mollusca (Cephalopoda) from Angola, consisting of Schloenbachia inflata, J. Sowerby, Desmoceras cuvervillei, Stan. Meun., Hamites virgulatus, Brongniart, and H. tropicalis, Stan. Meun. These specimens, obtained from the limestones of Lobito Bay, north of Benguella, were considered to be of Albian age, the forms of S. inflata being regarded as identical with a variety of that species which had been figured by Szajnocha from the Elobi Islands, situated off the north-west territory of the French Congo.

scholarly journals Factors and criteria of the morphostructural zoning and the main types of morphostructures of the North-West of the Black Sea

2019 ◽  
pp. 68-82
Author(s):  
А. А. Pasynkov ◽  
B. A. Vakhrushev
Keyword(s):  
Continental Slope ◽  
Black Sea ◽  
Deep Sea ◽  
Wave Action ◽  
The Black Sea ◽  
North West ◽  
The North ◽  
Research Techniques ◽  
Morphostructural Zoning

The principles of morphostructural zoning are presented on the example of the North-West of the Black Sea. Research techniques and criteria for distinguishing the morphostructural regions are discussed. In the morphostructural province of the Black Sea the following subprovinces were identified: shelf under conditions of active and passive wave action, continental slope with non-wave accumulation, deep-sea depression. Fragment of the map of morphostructural zoning of the North-West of the Black Sea at 1:500 000 scale is presented. Main morphogenetic types of morphostructures of the shelf, continental slope and deep sea basin of the Black sea are given. The characteristics of the selected morphostructural taxa are described.

Some features of the northwest African margin and magnetic quiet zone

1980 ◽  
Vol 294 (1409) ◽  
pp. 87-96 ◽  
Keyword(s):  
West Africa ◽  
Continental Slope ◽  
Oceanic Crust ◽  
Seismic Data ◽  
Cape Verde ◽  
Sharp Boundary ◽  
North West ◽  
Continental Rise ◽  
Layered Rock ◽  
Seismic Lines

A smooth basement reflector drilled in D.S.D.P. / IPOD Site 367 as basalt extends throughout much of the magnetic quiet zone off North West Africa. Multichannel seismic lines show structures and layered rock complexes locally beneath this basalt reflector. Under the continental slope of Senegal and Mauritania, the basement reflexion is no longer distinguished beneath a Cretaceous carbonate front. Refraction profiles between the Cape Verde Rise and Mauritania and from Conception Bank to Morocco establish the existence of a 7.1 km/s layer at a depth of 14 km. Off Mauritania the smooth basement seems to merge with this layer. Diapiric salt basins existing under the continental rise are only resolved as velocity layers off Mauritania. No sharp boundary from continental to oceanic crust was deduced from the seismic data.

Sign in / Sign up

Export Citation Format

Share Document