Fitoplancton en costas occidentales de Baja California en dos temporadas distintas de 1998

Phytoplankton was studied in two different seasons of 1998 (March-April and December), during two cruises along the western coasts of Baja California, in three zones. Two different protocols for obtaining and studying phytoplankton were followed. In the March-April season, phytoplankton had relatively low species richness and was dominated in cell density (up to 93%) by coccolithophorids (mainly Emiliania huxleyi), together with nanoplanktonic centric and pennate diatoms, with abundances ranging from 5.4 103 to 1.2 105 cells L-1. In December, phytoplankton had higher species richness and was represented by larger, chain-forming diatom species, such as Pseudonitzschia delicatissima and P. pungens, which were widespread and numerically significant. There was a relative scarcity of coccolithophorids and thecate dinoflagellates, and densities were between 7 102 and 1.4 106 cells L-1. Hydrographic and oceanographic conditions in March-April were influenced by the occurrence of El Niño and the phytoplankton structure was found to be modified accordingly, with nanoplanktonic coccolithophorids and diatoms being significant contributors to the total abundance. In contrast, post-upwelling conditions might have favoured relatively high densities of Pseudonitzschia and other diatoms in December, 1998. Coccolithophorids have not been previously regarded as important contributors to the phytoplankton abundances in Baja California.Se estudió el fitoplancton en dos temporadas diferentes de 1998 (marzo-abril y diciembre), durante dos cruceros en tres zonas de las costas de Baja California. Se siguieron dos protocolos distintos para obtener y estudiar el fitoplancton. En marzo-abril, el fitoplancton tuvo una riqueza de especies baja y estuvo dominado en densidades celulares (de hasta 93%) por cocolitofóridos (principalmente Emiliania huxleyi), junto con diatomeas centrales y pennales nanoplanctónicas, con abundancias desde 5.4 103 to 1.2 105 cells L-1. Para diciembre, el fitoplancton incrementó la riqueza de especies y estuvo representado por diatomeas más grandes, formadoras de cadenas, que se distribuyeron ampliamente y fueron numéricamente importantes, como: Pseudonitzschia delicatissima y P. pungens, con relativa escasez de cocolitofóridos y dinoflagelados tecados, con densidades entre 7 102 and 1.4 106 cells L-1. Las condiciones oceanográficas en marzo-abril indicaron la presencia de El Niño y los resultados mostraron una estructura de fitoplancton modificada por ello, con una contribución importante de cocolitofóridos y diatomeas nanoplanctónicas a la abundancia total. En cambio, en diciembre, las condiciones de post-surgencia pudieron haber favorecido las relativas altas densidades de especies de Pseudonitzschia y otras diatomeas. Los cocolitofóridos no habían sido documentados previamente como contribuyentes importantes a la abundancia fitoplanctónica en Baja California

Rumo a uma caracterização da competência algébrica na formação de professores

El presente estudio, de tipo cualitativo y exploratorio, está centrado en discutir la competencia algebraica exhibida por futuros docentes de bachillerato. En el estudio participaron seis futuros profesores mexicanos que resolvieron dos tareas algebraicas, los datos recopilados se analizaron de acuerdo con los niveles de competencia articulados en tres acciones: resolver, interpretar y validar. Los resultados muestran que los participantes tienen una competencia algebraica en vías de desarrollo, al presentar dificultades para interpretar y validar su actividad matemática. Es fundamental un currículum de formación de profesores que ponga mayor énfasis en estas tres acciones para favorecer la competencia algebraica.competence evidenced by prospective high school teacher. Six prospective Mexican teachers participated in the study when solving two tasks of an algebraic nature, data collected analyzed according to the four competence levels articulated in three actions: solve, interpret and validate. Results show that the prospective teachers have algebraic competence in development process, because they have difficulties interpreting and validating their mathematical activity. Therefore, the mathematics teacher training curriculum must emphasize posing these three actions to favor algebraic competence.A presente pesquisa teve caráter qualitativa e exploratória discute a competência algébrica exposta por futuros professores do ensino médio. Seis futuros professores no México participaram do estudo ao resolver duas tarefas algébricas, os dados coletados foram analisados de acordo com os quatro níveis de competência articulados em três ações: resolver, interpretar e validar. Os resultados mostram que os futuros professores possuem competência algébrica em processo de desenvolvimento, pois apresentam dificuldades na ação de interpretar e validar sua atividade matemática. Portanto, o currículo de formação de professores de matemática deve enfatizar a proposição dessas três ações para favorecer a competência algébrica

Management of Hypertension in the Elderly Patient at Abidjan Cardiology Institute (Ivory Coast)

Background. Since the treatment of hypertension is beneficial for the elderly, we have undertaken this study that aims to evaluate the management of hypertension in elderly patient in Côte d'Ivoire. Methods. A retrospective study was conducted among 854 hypertensive elderly patients of Abidjan Cardiology Institute who were followed for a minimum of one year, between January 2000 and December 2009. Results. The patients mean age was 73.1 ± 5.3 years, and 59% were women. At the first presentation, it was mostly systolic-diastolic hypertension (51.8%) and isolated systolic hypertension (38.5%). Mean blood pressure was 169.4 ± 28.4 mmHg for systolic, 95.3 ± 15.7 mmHg for diastolic, and 74.1 ± 22.8 mmHg for pulse pressure. Pulse pressure was ≥60 mmHg in 80.4%. According to the European Guidelines stratification of the cardiovascular risk-excess attributable to high blood pressure, 82.1% of the sample had a very high added risk. The pharmacological therapy was prescribed in 93.5%. More than 66% of patients were receiving ≥2 antihypertensive drugs including fixed-dose combination drugs. The most common agents used were diuretics (63.5%) followed by angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in 61.3%. The most common agents used for monotherapy were calcium antagonists. When ≥2 drugs were used, diuretics and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers were the most common. Blood pressure control was achieved in 42.6%. Conclusion. The control of elderly hypertension can be effective in Sub-Saharan Africa. He required at least two antihypertensive drugs to meet the recommended blood pressure target

Improvement of yam’s productivity by using human urine as fertilizer

L’alimentation des populations et la gestion des excréta constituent un défi majeur pour les pays en développement, notamment la Côte d’Ivoire. Il y a donc une nécessité d’améliorer les conditions de vie de cette population en exploitant les opportunités économiques qu’offrent les déchets, notamment l’urine. Dans ce sens, une étude sur la valorisation de l’urine en culture d’igname (Dioscorea cayenensis-rotundata) a été effectuée sur deux campagnes agricoles. Cette étude avait pour objectifs d’une part, d’évaluer les effets de l’urine sur la croissance, le développement et le rendement de l’igname et d’autre part, d’envisager les possibilités de stabiliser la production d’igname sur une même surface vu son exigence en fertilisant. Ainsi, un essai avec trois traitements (fertilisation à l’urine, fertilisation à l’engrais chimique et un témoin) a permis de montrer que les urines ont un effet significatif sur les paramètres de croissance (l’indice foliaire et la matière sèche totale) et le rendement en tubercules frais d’igname. En outre, la réplication du même essai sur le même site avec les mêmes traitements a montré que la production de l’igname demeure stable quand le sol est fertilisé à l’urine. L’urine est à promouvoir en culture d’igname pour préserver les végétations encore primaires et celles en friche vu sa forte demande et ses exigences en fertilisant

A new method to determine the diet of pygmy hippopotamus in Taï National Park, Côte d’Ivoire

This research was funded by “Fond des donations” of the University of Neuchâtel and the “Willy Müller Award” of the Centre Suisse de Recherches Scientifiques en Côte d’Ivoire.Diet determination of endangered species is an essential element in defining successful conservation strategies and optimising captive breeding programmes. In this study, we developed a new diet identification system, derived from standard faecal analysis, to determine the diet of an elusive and endangered herbivore, the pygmy hippopotamus (Choeropsis liberiensis). We collected faecal samples from 10 free-ranging individuals covering a combined home range area of about 50 km2 in Taï National Park, Côte d’Ivoire. In subsequent laboratory analyses, we extracted a large number of leaf epidermis fragments from spatially separated faecal samples and compared them with a reference plant database. Using Multiple Correspondence Analysis (MCA) of epidermis fragments combined with direct visual inspection, we identified the most frequently consumed plant species, which revealed that pygmy hippopotami qualified as intermediate feeders. Their diet was based on at least seven species of monocotyledonae, dicotyledonae and fern groups, with a preference for a small number of other plant species. We evaluate the merit of our method and discuss our findings for developing effective conservation and captive breeding strategies in an endangered species with a wild population of less than 2500 adult individuals.PostprintPeer reviewe

The challenge of improving soil fertility in yam cropping systems of West Africa

Published online: 21 Nov 2017Yam (Dioscorea spp.) is a tuber crop grown for food security, income generation, and traditional medicine. This crop has a high cultural value for some of the groups growing it. Most of the production comes from West Africa where the increased demand has been covered by enlarging cultivated surfaces while the mean yield remained around 10 t tuber ha−1. In West Africa, yam is traditionally cultivated without input as the first crop after a long-term fallow as it is considered to require a high soil fertility. African soils, however, are being more and more degraded. The aims of this review were to show the importance of soil fertility for yam, discuss barriers that might limit the adoption of integrated soil fertility management (ISFM) in yam-based systems in West Africa, present the concept of innovation platforms (IPs) as a tool to foster collaboration between actors for designing innovations in yam-based systems and provide recommendations for future research. This review shows that the development of sustainable, feasible, and acceptable soil management innovations for yam requires research to be conducted in interdisciplinary teams including natural and social sciences and in a transdisciplinary manner involving relevant actors from the problem definition, to the co-design of soil management innovations, the evaluation of research results, their communication and their implementation. Finally, this research should be conducted in diverse biophysical and socio-economic settings to develop generic rules on soil/plant relationships in yam as affected by soil management and on how to adjust the innovation supply to specific contexts

Evaluación De La Influencia De Las Condiciones De Fondo De Pozo En El Deterioro De Un Acero API P110, En Ambientes Simulados Del Proceso De Combustión In Situ, Por Gravimetría Y EIS

RESUMEN Dada la gran cantidad de consumo del petróleo como recurso energético, tiene por consecuencia una diminución en el crudo existente a nivel mundial, la explotación del crudo pesado surge como nueva alternativa de extracción que se deja a un lado debido a las dificultades asociadas a su procesamiento. Por lo tanto el proceso de combustión in situ, es un método de extracción que facilita la producción de este tipo de crudo, pues generan un aumento en la producción a expensas de un aumento de los costos asociados a mantenimiento, pues a las condiciones operacionales se favorecen fenómenos como la corrosión de los diferentes materiales involucrados en el proceso, pues están expuestos a atmosferas de sulfuro de hierro (H2S), entre otros gases; a temperaturas y presiones elevadas, lo cual promueve la corrosión y los fenómenos de Sulfide stress cracking. Adicionalmente, los materiales se ven afectados por la acidez y la cantidad de impurezas presentes en el crudo. Por lo anterior se evaluó el comportamiento del acero API P110 expuesto a crudo pesado con diferentes contenidos de azufre (0.5 - 1.5 % en peso), TAN (2.28 - 6.84 g KOH/g crudo) a elevadas temperaturas (190 -250 °C) y presiones (8.96x106 - 11.72x106 Pa), ya que se pueden presentar estas condiciones en el proceso de extracción por combustión in situ en fondos de pozo. Se encontró que el principal mecanismo de corrosión en estas condiciones es la corrosión por sulfidación cuyos principales productos de corrosión son el FeS y óxido de hierro (Fe3O4)