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Search Results: 1 - 10 of 430 matches for " Isidro; "
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Real quartic surfaces containing skew lines
Isidro Nieto
International Journal of Mathematics and Mathematical Sciences , 2004, DOI: 10.1155/s0161171204308112
Abstract: It is well known that there is an open three-dimensional subvariety Ms of the Grassmannian of lines in ℙ3 which parametrizes smooth irreducible complex surfaces of degree 4 which are Heisenberg invariant, and each quartic contains 32 lines but only 16 skew lines, being determined by its configuration of lines, are called a double 16. We consider here the problem of visualizing in a computer the real Heisenberg invariant quartic surface and the real double 16. We construct a family of points l∈Ms parametrized by a two-dimensional semialgebraic variety such that under a change of coordinates of l into its Plüecker, coordinates transform into the real coordinates for a line L in ℙ3, which is then used to construct a program in Maple 7. The program allows us to draw the quartic surface and the set of transversal lines to L. Additionally, we include a table of a group of examples. For each test example we specify a parameter, the viewing angle of the image, compilation time, and other visual properties of the real surface and its real double 16. We include at the end of the paper an example showing the surface containing the double 16.
Neuropathology and Neurochemistry of Nonmotor Symptoms in Parkinson's Disease
Isidro Ferrer
Parkinson's Disease , 2011, DOI: 10.4061/2011/708404
Abstract: Parkinson disease (PD) is no longer considered a complex motor disorder characterized by Parkinsonism but rather a systemic disease with variegated non-motor deficits and neurological symptoms, including impaired olfaction, autonomic failure, cognitive impairment, and psychiatric symptoms. Many of these alterations appear before or in parallel with motor deficits and then worsen with disease progression. Although there is a close relation between motor symptoms and the presence of Lewy bodies (LBs) and neurites filled with abnormal -synuclein, other neurological alterations are independent of the amount of -synuclein inclusions in neurons and neurites, thereby indicating that different mechanisms probably converge in the degenerative process. Involvement of the cerebral cortex that may lead to altered behaviour and cognition are related to several convergent factors such as (a) abnormal -synuclein and other proteins at the synapses, rather than LBs and neurites, (b) impaired dopaminergic, noradrenergic, cholinergic and serotoninergic cortical innervation, and (c) altered neuronal function resulting from reduced energy production and increased energy demands. These alterations appear at early stages of the disease and may precede by years the appearance of cell loss and cortical atrophy. 1. Introduction Parkinson disease (PD) is clinically characterized by a complex motor disorder known as parkinsonism and is manifested principally by resting tremor, slowness of initial movement, rigidity, and general postural instability. These symptoms are mainly due to the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to reduced dopaminergic input to the striatum and accompanied by adaptive responses in the internal and external globus pallidus, subthalamus, thalamus and substantia nigra pars reticularis. Round, hyaline neuronal cytoplasmic inclusions called Lewy bodies (LBs) and enlarged aberrant neurites and threads are found in the Parkinsonian substantia nigra [1, 2]. In addition to the substantia nigra, other nuclei are involved such as the locus ceruleus, reticular nuclei of the brain stem, and dorsal motor nucleus of the vagus, as well as the basal nucleus of Meynert, the amygdala and the CA2 area of the hippocampus. LBs and aberrant neurites are also found in these locations [1–7]. Similar lesions but extended to the cerebral neocortex are characteristic of a closely-related disease named Dementia with Lewy bodies (DLB) [8]. PD and DLB are therefore considered Lewy body diseases (LBDs). Neuropathology and clinical aspects of DLB
Indicadores de contenidos para la web académica iberoamericana
Aguillo, Isidro
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2005,
Abstract: Se ha realizado un análisis cibermétrico sobre las universidades iberoamericanas a partir de indicadores que describen su presencia en la web. El objetivo perseguido era demostrar tanto la idoneidad de estos indicadores en la evaluación de la actividad científica como ilustrar los patrones específicos del uso de la web para la comunicación científica en el sector académico iberoamericano. Entre finales de 2002 y principios de 2003 se han analizado los diferentes parámetros de los dominios universitarios iberoamericanos de acuerdo con datos obtenidos de los motores de búsqueda. Los resultados muestran que las grandes universidades, especialmente la Universidade de S o Paulo y la Universidad Nacional Autónoma de México (UNAM), obtienen valores destacados en todos los indicadores seleccionados. Por países, Brasil es el que coloca más instituciones entre las primeras. Hay que destacar que los datos de la web se corresponden con los obtenidos de las bases de datos bibliométricas, aunque las universidades con fuertes servicios de educación a distancia, como el Tecnológico de Monterrey, aparecen mejor en los indicadores de la web. La visibilidad de las instituciones académicas en la Web se está incrementando en la mayoría de los países iberoamericanos, aunque se debería aumentar significativamente el volumen de contenidos publicados y mejorar su interés internacional, aumentando los recursos científicos, en formatos ricos y en versión bilingüe incluyendo el inglés.A cybermetric analysis was carried out on Ibero-American universities, based on indicators describing their presence on the web. The objective was to demonstrate the adequacy of these indicators for evaluating scientific activity and to illustrate specific models of web usage for scientific communication in the academic sector in Ibero-America. Between the end of 2002 and the beginning of 2003, different parameters of the domains of Ibero-American universities were analysed, in accordance with data obtained from search engines. The results show that the large universities, especially the Universidade de S o Paulo and the Universidad Nacional Autónoma de México (UNAM), had high scores in all of the selected indicators. By country, Brazil had more institutions among the top scoring group. It should be noted that the web data was obtained from bibliometric databases and that universities with strong distance learning services, such as the Tecnológico de Monterrey, have better web indicator ratings. The visibility of academic institutions through their webs is on the increase in most Ibero-American count
Coneixent millor els cercadors
Aguillo, Isidro
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2008, DOI: 10.1344/105.000000315
Abstract:
Conociendo mejor los buscadores
Aguillo, Isidro
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2008, DOI: 10.1344/105.000000316
Abstract:
Indicadors de continguts per als webs acadèmics iberoamericans
Aguillo, Isidro
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2005,
Abstract: S ha dut a terme una anàlisi cibermètrica sobre les universitats iberoamericanes a partir d indicadors que en descriuen la presència en el web. L objectiu que es perseguia era demostrar tant la idone tat d aquests indicadors en l avaluació de l activitat científica com il lustrar els patrons específics de l ús del web per a la comunicació científica en el sector acadèmic iberoamericà. Entre la fi de 2002 i el comen ament de 2003 s han analitzat els diferents paràmetres dels dominis universitaris iberoamericans d acord amb dades obtingudes dels motors de cerca. Els resultats mostren que les grans universitats, especialment la Universidade de S o Paulo i la Universidad Nacional Autónoma de México (UNAM), obtenen valors destacats en tots els indicadors seleccionats. Per pa sos, el Brasil és el que col loca més institucions entre les primeres. Cal destacar que les dades web es corresponen amb les obtingudes de les bases de dades bibliomètriques, tot i que les universitats amb forts serveis d educació a distància, com ara el Tecnológico de Monterrey, apareixen millor en els indicadors web. La visibilitat de les institucions acadèmiques en els webs s està incrementant en la majoria dels pa sos iberoamericans, encara que no sols s hauria d augmentar significativament el volum de continguts publicats sinó també millorar-ne l interès internacional i augmentar-ne els recursos científics, en formats rics i en versió bilingüe, l anglès inclòs.A cybermetric analysis was carried out on Ibero-American universities, based on indicators describing their presence on the web. The objective was to demonstrate the adequacy of these indicators for evaluating scientific activity and to illustrate specific models of web usage for scientific communication in the academic sector in Ibero-America. Between the end of 2002 and the beginning of 2003, different parameters of the domains of Ibero-American universities were analysed, in accordance with data obtained from search engines. The results show that the large universities, especially the Universidade de S o Paulo and the Universidad Nacional Autónoma de México (UNAM), had high scores in all of the selected indicators. By country, Brazil had more institutions among the top scoring group. It should be noted that the web data was obtained from bibliometric databases and that universities with strong distance learning services, such as the Tecnológico de Monterrey, have better web indicator ratings. The visibility of academic institutions through their webs is on the increase in most Ibero-American countries. However, they must no
Rese a de "Le Démon des Origines. Démographie et Extrême Droit" de H. Le Bras.
Isidro Dubert
Revista de Investigaciones Políticas y Sociológicas (RIPS) , 1999,
Abstract:
VII Congreso de Indicadores de Ciencia y Tecnología de la RICYT
Aguillo, Isidro
Revista Espa?ola de Documentación Científica , 2007,
Abstract:
Los estudios sobre el socialismo temprano en Colombia: una versión de la izquierda
Vanegas Isidro
Anuario Colombiano de Historia Social y de la Cultura , 2000,
Abstract: Este ensayo indaga sobre los estudios acerca del socialismo en Colombia antes de 1930. Un tema que ha atraído a considerable número de investigadores y ha dado frutos en un amplia cantidad de trabajos. Al ser la izquierda un campo político fuertemente apegado a los debates doctrinarios, hila esta panorámica el supuesto de que existe una fuerte relación entre los avatares de la izquierda y la forma como ha reconstruido discursivamente sus propios orígenes, su desarrollo y sus vinculaciones con la sociedad colombiana.
LA EDUCACION Y LA CAPACITACION RURAL EN LA REGION ANDINA
Quevedo Camacho,Rafael Isidro;
Agroalimentaria , 2005,
Abstract: this article analyses the situation of rural training and educational programs at the rural areas of the andean region (south america). the focus is to identify main policy changes in the institutions that are involved in educational development. the article uses bibliography published by eclac, undp and official organizations from bolivia, colombia, ecuador and perú. the article concludes that in spite of past achievements, specially in the field of increasing the number of students, several problems persist. those must be addressed by a coordinated effort.
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