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Search Results: 1 - 10 of 467306 matches for " A Vincent "
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An Analysis and Computation of Optimum Earth Geographical Coverage for Global Satellite Communications  [PDF]
O. C. Eke Vincent, A. N. Nzeako
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.54042

This paper presents simple mathematical mobility models for configuration of Global interconnectivity with LEO satellite systems. The aim of this paper is to investigate on the performance measures of the satellite mobility models regarding optimum Global coverage arc length depending on the satellite locations relative to the four zones (quadrants) of the earth surface. A typical body of the satellite was positioned at a modified height of 780 Km from the earth surface and revolving round the earth in a circle of radius, 7160 Km was carefully studied and analytically parameterized enabling the generation of realistic instantaneous coverage arc lengths data. We compared the minimum required instantaneous arc lengths for the three mobility models that should cover the geographical coverage areas of the earth. The impact of the satellite movements relative to the earth locations was that the instantaneous coverage arc lengths were exponentially varying with time and continuously distributed within the four zones of the earth surface to provide continuous coverage around one polar orbit plane and assuming operations can continue down to an elevation angle of zero degree. The advantage of the derived mobility models is achieving almost 100% global coverage as a result of the dynamic behavior of the satellite playing an important role of providing instantaneous coverage arc lengths. This procedure also allows comparisons among different degrees of built-up zones of the earth surface as well as extra-polation to the different locations on the earth surface.

Kitobo Forest of Kenya, a unique hotspot of herpetofaunal diversity
Vincent Muchai,Beryl A. Bwong,Vincent Muchai
Acta Herpetologica , 2011,
Abstract: Herpetologically, the remoteness of Kitobo forest in south-eastern Kenya has partly contributed to it remaining virtually un-explored until 2007. Three surveys were conducted in December 2007, December 2009 and April 2010 aimed at generating a comprehensive list of the forest amphibians and reptiles. Using largely timed-species count method, 13 species of amphibians representing eight families and 32 reptiles belonging to 11 families were recorded. Overall species diversity was highest during the 2007 sampling. The richness and abundance of amphibians was highest during the April 2010 sampling period when the amount of rainfall was also highest. The results of species accumulation curves of the three sampling periods did not plateau demonstrating that more species occur in this forest. Pressure on this forest fragment from the adjacent local people is high which in addition to the annual floods threatens its long-term survival. For example the distribution and abundance of some forest associated species such as the tree frogs Leptopelis flavomaculatus and Hyperolius puncticulatus appear to fluctuate with flood events and may decline in future. Considering the forest associated herpetofanua recorded, Kitobo forest is zoogeographically assignable to the East African coastal forest biodiversity hotspot. The documentation of high species richness and diversity in this small forest fragment strongly highlight its biodiversity importance and place it among the most important sites for the conservation of reptiles and amphibians in Kenya.
La disputa por la mediación durante el kirchnerismo en Argentina
Vincent, Lucía;
CONfines de relaciones internacionales y ciencia política , 2011,
Abstract: nestor kirchner, the ex argentinean president, developed a unique and new way of relating with the press, totally divergent from the method that previous democratic governments used to have. through the analysis of kirchner' speeches, this article will illustrate in which way the president aimed to weaken the media, removing them from their position as the "forth power" and "objective mediators" between the government and the citizens. those transformations are due to the conditions in which he developed a speci?c type of leadership. those changes, also, had consequences in the political representation andin the current characteristics of the democratic system in argentina.
Hygrothermal Ageing Effects on the Static Fatigue Behaviour of a Glass Epoxy. Composite Damage Mechanisms Mapping Les effets du vieillissement hydrothermique sur le comportement en fatigue statique d'un composite verre / epoxy. Cartographie des mécanismes d'endommagement en fatigue statique
Chateauminois A.,Vincent L.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1995010
La disputa por la mediación durante el kirchnerismo en Argentina
Vincent, Lucía
CONfines de relaciones internacionales y ciencia política , 2011,
Abstract: El presidente argentino Néstor Kirchner construyó una estrategia propia de relación con la prensa diferente a la establecida por los gobiernos democráticos anteriores. A partir del análisis de sus discursos, el artículo busca demostrar cómo este presidente pretendió quitarle a los medios el lugar de “cuarto poder” y de “mediadores objetivos” entre el gobierno y la ciudadanía. Estas transformaciones se deberían a las condiciones de llegada de Kirchner al gobierno y a sus estrategias de construcción de un tipo específico de liderazgo. Estos cambios, además, tendrían consecuencias para la representación política y las características que asume la democracia argentina en la actualidad.Nestor Kirchner, the ex Argentinean President, developed a unique and new way of relating with the press, totally divergent from the method that previous democratic governments used to have. Through the analysis of Kirchner′ speeches, this article will illustrate in which way the president aimed to weaken the media, removing them from their position as the “forth power” and “objective mediators” between the government and the citizens. Those transformations are due to the conditions in which he developed a specific type of leadership. Those changes, also, had consequences in the political representation and in the current characteristics of the democratic system in Argentina.
Impurity impact ionization avalanche in p-type diamond
Vincent Mortet,A. Soltani
Physics , 2012, DOI: 10.1063/1.3662403
Abstract: Electrical conductivity of a highly boron doped chemical vapor deposited diamond thin film has been studied at different temperatures under high electric field conditions. Current-voltage characteristics have been measured using pulsed technique to reduce thermal effects. Experimental results evidence deep impurity impact ionization avalanche in p-type diamond up to room temperature.
Synthesis of N-Benzyl-3-anilinopropanamides and Cyclization to 4-Hydroxy-4-N-benzylamino-1,2,3,4-tetrahydroquinoline  [PDF]
Lami A. Nnamonu, Vincent C. Agwada, Chukwuemeka A. Nwadinigwe
International Journal of Organic Chemistry (IJOC) , 2013, DOI: 10.4236/ijoc.2013.34032

Substituted 3-anilinopropanamides were converted to N-benzyl derivatives via uncatalyzed amine exchange reaction with benzylamine in up to 41% yield. Unprotected aniline nitrogen had been observed to inhibit facile cyclization. An attempt was therefore made to protect the N by acetylation prior to cyclization. During this process, facile ring closure occurred in the methoxy series to give 4-hydroxy-4-N-benzylamino-1,2,3,4-tetrahydroquinolines in up to 69% yield.



Intrathecal IgG synthesis in relapsing-remitting multiple sclerosis (MS) is decreased by natural human alpha interferon  [PDF]
William A. Sheremata, Alan Sazant, Vincent Riesgo, Alex Burns
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.47A3001
Abstract: Intrathecal IgG synthesis (IT IgG Syn) is an established biomarker used for the diagnosis of multiple sclerosis (MS). Earlier studies used this biomarker to assess the impact of 2 different synthetic forms of interferon alpha (IFN-α) in chronic progressive MS. Unexpectedly, IT IgG synthesis was increased by this treatment. For the first time, we have assessed this parameter in relapsing-remitting patients to measure the impact of natural IFN-α treatment in a doseranging study in six dosage groups (5, 10, 15, 20, 25, & 30 MIU). We have found that IFN-α normalized IT IgG Synthesis at 12 weeks treatment for all dosage groups. Two weeks after stopping IFN-α results rose slightly. At 52 weeks, 28 weeks after stopping IFN-a results revealed cessation of IT IgG Synthesis in half of the patients (15, 20, 25 MIU weekly). These results reflect different outcomes for relapsing-remitting patients vs. chronic progressive patients. They may, however, reflect differences in the biological properties of the interferon products used. An optimal range of dosage with natural human IFN-α dosage for MS is suggested by the results.
The Impact of 3D Printing Technology to the Nigerian Manufacturing GDP  [PDF]
Vincent A. Balogun, Omonigho B. Otanocha, Akii O. Ibhadode
Modern Mechanical Engineering (MME) , 2018, DOI: 10.4236/mme.2018.82010
Abstract: 3D printing can spur manufacturing rebirth in Nigeria and the World in general. There are many areas where 3D printing is creating significant change, particularly in designing and prototyping of new products, in the arts, and in visualizing abstract concepts. This is a step change from conventional manufacturing processes to rapid prototyping and layer manufacturing. This report has defined rapid prototyping, rapid manufacturing and the current technologies available to fabricate 3D components. In addition to this, it provides a brief overview of the current contributions of the Edo University Iyamho (EUI) in collaboration with the Federal University of Petroleum Resources, to sustain manufacturing research initiatives towards the development of locally fabricated 3D printer and the possible future Additive Manufacturing in Nigeria. It is anticipated that this work will benefit the Nigerian academic, research institutes, industries, thus, enhance the GDP contribution of the manufacturing sector in Nigeria.
The Secret Life of the Anthrax Agent Bacillus anthracis: Bacteriophage-Mediated Ecological Adaptations
Raymond Schuch, Vincent A. Fischetti
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006532
Abstract: Ecological and genetic factors that govern the occurrence and persistence of anthrax reservoirs in the environment are obscure. A central tenet, based on limited and often conflicting studies, has long held that growing or vegetative forms of Bacillus anthracis survive poorly outside the mammalian host and must sporulate to survive in the environment. Here, we present evidence of a more dynamic lifecycle, whereby interactions with bacterial viruses, or bacteriophages, elicit phenotypic alterations in B. anthracis and the emergence of infected derivatives, or lysogens, with dramatically altered survival capabilities. Using both laboratory and environmental B. anthracis strains, we show that lysogeny can block or promote sporulation depending on the phage, induce exopolysaccharide expression and biofilm formation, and enable the long-term colonization of both an artificial soil environment and the intestinal tract of the invertebrate redworm, Eisenia fetida. All of the B. anthracis lysogens existed in a pseudolysogenic-like state in both the soil and worm gut, shedding phages that could in turn infect non-lysogenic B. anthracis recipients and confer survival phenotypes in those environments. Finally, the mechanism behind several phenotypic changes was found to require phage-encoded bacterial sigma factors and the expression of at least one host-encoded protein predicted to be involved in the colonization of invertebrate intestines. The results here demonstrate that during its environmental phase, bacteriophages provide B. anthracis with alternatives to sporulation that involve the activation of soil-survival and endosymbiotic capabilities.
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