492 research outputs found
Analysis of an Experimental Cortical Network: i) Architectonics of Visual Areas 17 and 18 After Neonatal Injections of Ibotenic Acid; Similarities with Human Microgyria
Lesions of cortical areas 17 and 18 have been produced in newborn kittens by local injections of the excitotoxin ibotenic acid (ibo). Twenty-four hours after an injection on postnatal days 2 or 3, the gray matter of areas 17 and 18 near the center of the injection appears completely destroyed, with the exception of a one-to-two cell-thick layer at the bottom of layer I. Intact migrating neurons and radial glia can be found light- and electron-microscopically in the region affected. During the following weeks a several hundred micron thick cortex reforms. In the adult, this cortex consists of superficial layers I, II and III as proven by cytoarchitectonics, continuity with the corresponding layers of the normal cortex and cellular composition. We believe that the recovery is due to completion of migration by neurons spared by the ibo injection. More severe destruction of cerebral cortex, i.e. complete loss of the neuronal layers or their reduction to a few cell-thick mantles can be obtained with ibo injections at the end of the second or, respectively, first postnatal week. Severity of lesion also depends on the dose of ibo injected. There are interesting similarities between the ibo-injured cortex and two human neocortical displasias: microgyria and ulegyria
Analysis of an Experimental Cortical Network: ii) Connections of Visual Areas 17 and 18 After Neonatal Injections of Ibotenic Acid
Lesions of cortical areas 17 and 18 were produced
in newborn kittens by local injections of
the excitotoxin ibotenic acid. In the adult this
results in a microcortex which consists of superficial
layers I, II and III, in the absence of granular
and infragranular layers. Horseradish peroxidase,
alone or wheat germ agglutinin conjugated,
was injected in the microcortex or in the
contralateral, intact areas 17 and 18. The microcortex
maintains several connections characteristic
of normal areas 17 and 18 of the cat. It receives
afferents from the dLGN, and several visual
areas of the ipsilateral and contralateral
hemisphere. However, it has lost its projections
to dLGN, superior colliculus, and, at least in
part, those to contralateral visual areas. Thus some parts of the microcortex receive from, but
do not project into, the corpus callosum. In addition,
the microcortex maintains afferents from
ipsilateral and contralateral auditory areas AI
and AII which are normally eliminated in development
Análisis multicriterio de preferencias sociales en gestión hídrica bajo la Directiva Marco del Agua
[EN] This work aims to contribute to the implementation of the WFD with regard to the selection of the measures for a sustainable and socially accepted water management. A multicriteria decision support exercise is applied to the Guadalquivir River Basin in order to test the applicability of the Analytic Hierarchy Process in the new WFD context. A survey was carried out in the context of a future enlargement of La Breña reservoir (Córdoba). This analysis aims to obtain the public’s weight of the criteria in water management, in order to assess the legitimacy of the reservoir enlargement, as well as other management measures. Results suggest that the AHP is an adequate tool for the WFD purposes and a useful complement for the cost-effectiveness analysis.[ES] Este trabajo pretende contribuir a la aplicación de la DMA en relación con la selección de medidas para el uso sostenible y socialmente aceptado del agua. Nuestro análisis está orientado a la obtención, mediante el proceso analítico jerárquico (AHP), de la valoración social de los criterios de gestión del agua en el Guadalquivir, analizando para ello la legitimidad de la ampliación del embalse de la Breña (Córdoba), además de la evaluación de otras posibles medidas de gestión del agua. Los resultados sugieren que el AHP constituye una herramienta adecuada para la implementación de la DMA, así como un complemento útil del análisis coste-eficacia.La financiación de la encuesta se llevó a cabo gracias a los fondos del proyecto CICYT 300083-AGR2006 financiado por el Ministerio de Ciencia y Tecnología. Agradecemos al Dr.José Antonio Gómez-Limón del área de Economía Agraria de la E.T.S. Ingenierías Agrarias de Palencia (Universidad de Valladolid) por sus consejos y ayuda en relación a este trabajo; así como a los revisores anónimos que han contribuido con sus comentarios a la mejora del mismo.Mesa, P.; Martín-Ortega, J.; Berbel, J. (2011). Multicriteria analysis of water management under the Water Framework Directive. Economía Agraria y Recursos Naturales - Agricultural and Resource Economics. 8(2):105-126. https://doi.org/10.7201/earn.2008.02.06SWORD1051268
Evalutaion of two different control charts (I and U) in the study of mutiresistant bacteria contact precautions dynamics in a non-endemicity hospital setting
Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil
Magnetotactic bacteria (MTB) synthesize magnetite and greigite crystals under low oxygen conditions in the water column or uppermost sediment (greigite‐producing bacteria are found below the oxic‐anoxic transition). Dissolved iron and oxygen contents in local environments are known to be limiting factors for the production and preservation of biogenic magnetite. Understanding the processes that link MTB to their living environments is fundamental to reconstructing past chemical variations in the water column and sediment, and for using the magnetic properties of biogenic magnetite as environmental proxy indicators. Previous studies have suggested that the frequently identified biogenic soft (BS) and biogenic hard (BH) magnetite types are associated with equant and more elongated morphologies, respectively, and that their abundance varies in accordance with sedimentary oxygen content, where MTB that produce the BH component live in less oxygenated environments. We test this hypothesis in a high‐resolution integrated environmental magnetic and geochemical study of surface sediments from Mamanguá Ría, SE Brazil. Based on magnetic and pore water profiles, we demonstrate that both the BS and BH components occur within microaerobic environments and that as sediment oxygen content decreases with depth, the BS component disappears before the BH component. With continued burial into the sulfidic diagenetic zone, both components undergo progressive dissolution, but the BH component is more resistant to dissolution than the BS component. Our observations confirm previous inferences about the relative stability of these phases and provide a firmer basis for use of these two types of biogenic magnetite as paleoenvironmental proxies.D. R. and L. J. acknowledge funding
from FAPESP grants 2012/212123 and
2011/22018‐3, respectively. F. A.
acknowledges funding from FAPERJ,
CNPq, and CAPES. A. P. R.
acknowledges funding from the
Australian Research Council (grants
DP140104544 and DP160100805)
Problematization Methodology and Convergent Healthcare Research: praxis proposal in research
Rethinking irrigation modernisation: Realising multiple objectives through the integration of fisheries
Irrigation has been, and will remain, instrumental in addressing water security (Sustainable Development Goal (SDG) 6), food insecurity (SDG 2) and poverty (SDG 1) goals. However, the global context in which irrigation takes place is changing rapidly. A call for healthier and more sustainable food systems is placing new demands on how irrigation is developed and managed. Growing pressures from competing water uses in the domestic and industrial sectors, as well increasing environmental awareness, mean irrigation is increasingly called on to perform better, delivering acceptable returns on investment and simultaneously improving food security, rural livelihoods and nutrition, as well as supporting environmental conservation. Better integration of fisheries (including aquaculture) in irrigation planning, investment and management can contribute to the modernisation of irrigation and the achievement of the multiple objectives that it is called on to deliver. A framework illustrating how fisheries can be better integrated with irrigation, and how the two can complement each other across a range of scales, from scheme to catchment and, ultimately, national level, is presented
Student responses to the introduction of case-based learning and practical activities into a theoretical obstetrics and gynaecology teaching programme
BACKGROUND: The fourth-year Obstetrics and Gynaecology course at our institution had previously been taught using theory classes alone. A new teaching model was introduced to provide a better link with professional practice. We wished to evaluate the impact of the introduction of case discussions and other practical activities upon students' perceptions of the learning process. METHODS: Small-group discussions of cases and practical activities were introduced for the teaching of a fourth-year class in 2003 (Group II; 113 students). Comparisons were made with the fourth-year class of 2002 (Group I; 108 students), from before the new programme was introduced. Students were asked to rate their satisfaction with various elements of the teaching programme. Statistical differences in their ratings were analysed using the chi-square and Bonferroni tests. RESULTS: Group II gave higher ratings to the clarity of theory classes and lecturers' teaching abilities (p < 0.05) and lecturers' punctuality (p < 0.001) than did Group I. Group II had greater belief that the knowledge assessment tests were useful (p < 0.001) and that their understanding of the subject was good (p < 0.001) than did Group I. Group II gave a higher overall rating to the course (p < 0.05) than did Group I. However, there was no difference in the groups' assessments of the use made of the timetabled hours available for the subject or lecturers' concern for students' learning. CONCLUSIONS: Students were very receptive to the new teaching model
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