Holocene East African monsoonal variations recorded in wave-dominated clastic paleo-shorelines of Lake Abhe, Central Afar region (Ethiopia & Djibouti)

Geomorphology ◽  
2021 ◽  
pp. 107896
Author(s):  
Carlo Mologni ◽  
Laurent Bruxelles ◽  
Mathieu Schuster ◽  
Gourguen Davtian ◽  
Clément Ménard ◽  
...  
Keyword(s):  
2021 ◽  
Author(s):  
Carlo Mologni ◽  
Laurent Bruxelles ◽  
Fabien Arnaud ◽  
Pierre Sabatier ◽  
Anne-Lise Develle ◽  
...  

<p>Throughout the last 14 ka, tropical Africa experienced significant hydrological changes that were mainly driven by the orbital precession cycle, which controls the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that long-term monsoon humid oscillations (African Humid Period / AHP ~14 – ~6 ka) were punctuated by centennial-scale episodes of hyperaridity. However, the abrupt or gradual aridification modalities since the end of the AHP and the modalities of the centennial-scale episodes, as well as their impacts on past and current environments are still debated.</p><p>The Lake Abhe basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater originating in the Ethiopian Highlands, and represents a hydro-sedimentary system sensitive to hydro-climatic changes in East Africa. Today it is characterized by residual lakes (Gamari and Afambo lakes) and a hyper-arid climate, while during the AHP, the Abhe basin was occupied by a Mega-lake and by humid environmental conditions. Holocene climatic disruptions drastically changed the landscapes and ways of life along this basin.  </p><p>The aim of this study is to describe, interpret and estimate the impact of hydro-climatic oscillations on the evolution of Lake Abhe’s littoral lacustrine environments and palaeolandscapes since the AHP from different viewpoints.</p><p>Indeed, this research combines paleoclimatological and geomorphological studies based on a new set of <sup>14</sup>C ages on two lacustrine cores and on several morpho-sedimentary outcrops spanning the Early to Late Holocene. Our results allow us to: <strong>a</strong>) refine the temporal occurrence and the hydrological modalities of the AHP including short-term arid episodes linked to Younger Dryas and 8.2 ka North Atlantic events; <strong>b</strong>) recognise some paleo-shoreline geomorphic features linked to lake level fluctuations, as well as the development littoral pedological horizons and the activation/shutdown of the perilacustrine fluvial network during humid and arid events; <strong>c</strong>) track these changes until the present day, and discuss their evolution scenario in the near future.</p><p>Comparing with other regional climatic records, we show how Lake Abhe basin was highly reactive to East African monsoonal regimes, and how current hydrological changes could impact its environments.      </p>


2013 ◽  
Vol 339 ◽  
pp. 16-29 ◽  
Author(s):  
Thomas H. Darrah ◽  
Dario Tedesco ◽  
Franco Tassi ◽  
Orlando Vaselli ◽  
Emilio Cuoco ◽  
...  

2012 ◽  
Vol 49 (1) ◽  
pp. 43-58 ◽  
Author(s):  
Raymond Coish ◽  
Jonathan Kim ◽  
Nathan Morris ◽  
David Johnson

Metamorphosed mafic rocks from west-central Vermont crop out in tectonic slices of the Stowe Formation within the Rowe–Hawley Belt of New England. The rocks include greenstone and amphibolite, which are interpreted to have been basaltic flows and gabbroic intrusions, respectively. Even though the rocks have been metamorphosed to greenschist or amphibolite facies, their igneous origins can be deciphered through careful use of geochemistry. Three geochemical types have been identified. Type 1 and 2 samples have geochemical characteristics similar to those found in mid-ocean ridge basalts (MORB), except that they have slightly elevated light rare-earth element (LREE) concentrations and are higher in Nb/Y ratios. Their Nb/Y ratios are similar to basalts found in Iceland and parts of the Afar region of the East African Rift. Types 1 and 2 are similar to metabasalts of the Caldwell and Maquereau formations in southern Quebec. The less-common type 3 samples have highly enriched LREE and are high in Nb/Y and Zr/Y ratios, similar to some alkali basalts from Afar and Iceland. Detailed analysis of the geochemistry suggests that greenstones and amphibolite from the Stowe Formation formed as basaltic eruptions during very late stages in rifting of the Rodinian continent that eventually led to formation of the Iapetus Ocean. This interpretation is consistent with tectonic models of the Vermont and Quebec Appalachians.


Author(s):  
P. Evers ◽  
C. Schutte ◽  
C. D. Dettman

S.rodhaini (Brumpt 1931) is a parasite of East African rodents which may possibly hybridize with the human schistosome S. mansoni. The adult male at maturity measures approximately 3mm long and possesses both oral and ventral suckers and a marked gynaecophoric canal. The oral sucker is surrounded by a ring of sensory receptors with a large number of inwardly-pointing spines set into deep sockets occupying the bulk of the ventral surface of the sucker. Numbers of scattered sensory receptors are found on both dorsal and ventral surfaces of the head (Fig. 1) together with two conspicuous rows of receptors situated symmetrically on each side of the midline. One row extends along the dorsal surface of the head midway between the dorsal midline and the lateral margin.


2017 ◽  
Vol 2 (11) ◽  
pp. 73-78
Author(s):  
David W. Rule ◽  
Lisa N. Kelchner

Telepractice technology allows greater access to speech-language pathology services around the world. These technologies extend beyond evaluation and treatment and are shown to be used effectively in clinical supervision including graduate students and clinical fellows. In fact, a clinical fellow from the United States completed the entire supervised clinical fellowship (CF) year internationally at a rural East African hospital, meeting all requirements for state and national certification by employing telesupervision technology. Thus, telesupervision has the potential to be successfully implemented to address a range of needs including supervisory shortages, health disparities worldwide, and access to services in rural areas where speech-language pathology services are not readily available. The telesupervision experience, potential advantages, implications, and possible limitations are discussed. A brief guide for clinical fellows pursuing telesupervision is also provided.


2008 ◽  
Vol 16 (2) ◽  
pp. 121-150 ◽  
Author(s):  
ALDO CHIRCOP ◽  
DAVID DZIDZORNU ◽  
JOSE GUERREIRO ◽  
CATARINA GRILO
Keyword(s):  

2020 ◽  
pp. 3-17
Author(s):  
Peter Nabende

Natural Language Processing for under-resourced languages is now a mainstream research area. However, there are limited studies on Natural Language Processing applications for many indigenous East African languages. As a contribution to covering the current gap of knowledge, this paper focuses on evaluating the application of well-established machine translation methods for one heavily under-resourced indigenous East African language called Lumasaaba. Specifically, we review the most common machine translation methods in the context of Lumasaaba including both rule-based and data-driven methods. Then we apply a state of the art data-driven machine translation method to learn models for automating translation between Lumasaaba and English using a very limited data set of parallel sentences. Automatic evaluation results show that a transformer-based Neural Machine Translation model architecture leads to consistently better BLEU scores than the recurrent neural network-based models. Moreover, the automatically generated translations can be comprehended to a reasonable extent and are usually associated with the source language input.


2016 ◽  
Author(s):  
Y. Y. Foo ◽  
R. D. Tewari ◽  
K. C. Kok ◽  
A. Elrufai ◽  
H. Elbaloula ◽  
...  

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