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Search Results: 1 - 10 of 225738 matches for " R. Prieto "
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The State of the Art in Pulmonary Vein Stenosis - Diagnosis & Treatment
Lourdes R. Prieto
Journal of Atrial Fibrillation , 2010, DOI: 10.4022/jafib.v1i10.558
Abstract: Pulmonary vein stenosis is a rare but serious complication of pulmonary vein isolation to treat atrial fibrillation. Pulmonary vein angioplasty/stenting has emerged as the treatment of choice for significantly stenotic veins. Guidelines for post ablation evaluation of the pulmonary veins, including the timing and method of surveillance for possible stenosis, the criteria for intervention, the technical aspects of intervention, and finally the surveillance post intervention, are still being developed. The relatively high rate of restenosis after intervention in a subset of patients remains a great challenge. A better understanding of the pathophysiology underlying this syndrome is needed to appropriately answer many of the remaining questions. The goal of this manuscript is to describe what has been learned about this complication and its treatment from a relatively large experience in a single institution over the past decade, and provide a comprehensive review of the existing literature in order to shed as much light on the subject as is possible, while at the same time exposing the areas that need further study.
Documentary evidence for changing climatic and anthropogenic influences on the Bermejo Wetland in Mendoza, Argentina, during the 16th–20th century
M. R. Prieto ,F. Rojas
Climate of the Past (CP) & Discussions (CPD) , 2012,
Abstract: This paper examines the processes underlying changes to the once-extensive Bermejo Wetland, east of the city of Mendoza, Argentina (32°55' S, 68°51' W). Historical documents and maps from the 16th to 20th century are used to reconstruct environmental shifts. Historical documents indicate periods of increased snowfall in the adjacent Andes mountains, as well as high flow volumes in the Mendoza River. Data from georeferenced maps, the first from 1802 and the last from 1903, reflect the changes in the surface area of the wetland. The combined data sets show pulses of growth and retraction, in which major expansions coincided with more intense snowstorms and increased flow in the Mendoza River, which in turn influenced socio-economic activities. The wetland became progressively drier during the 19th century, before drying up completely around 1930, due in part to the construction of drainages and channels.
Study on the structure and composition of aortic valve calcific deposits. etiological aspects  [PDF]
R. M. Prieto, I. Gomila, O. S?hnel, A. Costa-Bauza, O. Bonnin, F. Grases
Journal of Biophysical Chemistry (JBPC) , 2011, DOI: 10.4236/jbpc.2011.21003
Abstract: The structures and chemical compositions of valve calcific deposits were investigated. The deposits was chosen arbitrarily and subjected to chemical analysis, observation with scanning microscope, semi-quantitative determination of Ca, Mg, Na, K, P and C elements by energy dispersive X-ray, X-ray diffraction and Fourier transform infrared spectroscopy carried out. These deposits were found to have non-uniform internal structures composed of layers of a structureless aspidinic inorganic material, substantial amounts of voluminous organic material and in a few samples small spheres were also present. Two groups of deposits with distinctly different chemical compositions were identified: one group with a low Ca/P molar ratio (1.59) and the other group with a high (1.82) Ca/P molar ratio. The deposits belonging to the group with a low Ca/P molar ratio contain higher concentration of magnesium and consist of increased amount of amorphous calcium phosphate. The deposits with a high Ca/P molar ratio contain low concentration of magnesium and consist predominantly of carbonated hydroxyapatite. The inorganic material was identified as a poorly crystalline carbonate hydroxyapatite containing molecular water of the average formula Ca9.1Mg0.4(Na,K)(PO4)5.8(CO3)0.3(OH)2. The actual chemical composition of the apatitic solid phase varies not only from deposit to deposit but also within the same deposit. The non-uniform internal structure of the deposits, the occasional presence of spherical particles and the variable point composition of the individual deposits indicate that their formation did not proceed under more or less constant conditions.
Photocatalytic Degradation of Toluene in Air Using a Fluidized Bed Photoreactor
O. Prieto,J. Fermoso,R. Irusta
International Journal of Photoenergy , 2007, DOI: 10.1155/2007/32859
Abstract: The photocatalytic degradation of toluene in air was carried out on particles of TiO2 in a photocatalytic reactor that had been developed to study the treatment of organic pollutants in a gaseous phase. Hypothetically, the fluidized bed technology of this reactor could make it possible to increase the mass transfer coefficients in comparison with those of conventional photoreactors. The photocatalytic particles used were prepared by mixing TiO2 (Degussa P25) and starch in a methanol solution. The XRD and SEM results of these aggregates confirm the titanium dioxide (Degussa P25) characteristics, such as the presence of anatase on the particle surface and spongy and wrinkled morphology. Toluene concentrations varied from 0.9 to 199 ppmv, and all the experiments were carried out with a flow rate of 300 NL/h. Toluene conversions from 77% to 100% were obtained in the range studied. In this work, the regeneration processes of deactivated TiO2 photocatalysts have been investigated using FT-IR and GC/MS techniques. Benzoic acid, benzaldehyde, and benzyl alcohol were the three major intermediate products identified.
On Increasing Network Lifetime in Body Area Networks Using Global Routing with Energy Consumption Balancing
Gill R. Tsouri,Alvaro Prieto,Nikhil Argade
Sensors , 2012, DOI: 10.3390/s121013088
Abstract: Global routing protocols in wireless body area networks are considered. Global routing is augmented with a novel link cost function designed to balance energy consumption across the network. The result is a substantial increase in network lifetime at the expense of a marginal increase in energy per bit. Network maintenance requirements are reduced as well, since balancing energy consumption means all batteries need to be serviced at the same time and less frequently. The proposed routing protocol is evaluated using a hardware experimental setup comprising multiple nodes and an access point. The setup is used to assess network architectures, including an on-body access point and an off-body access point with varying number of antennas. Real-time experiments are conducted in indoor environments to assess performance gains. In addition, the setup is used to record channel attenuation data which are then processed in extensive computer simulations providing insight on the effect of protocol parameters on performance. Results demonstrate efficient balancing of energy consumption across all nodes, an average increase of up to 40% in network lifetime corresponding to a modest average increase of 0.4 dB in energy per bit, and a cutoff effect on required transmission power to achieve reliable connectivity.
Hemangioblastoma of the lateral ventricle: case report and review of the literature
Prieto,R.; Roda,J.M.;
Neurocirugía , 2005, DOI: 10.4321/S1130-14732005000100009
Abstract: we report a unique case of hemangioblastoma of the lateral ventricle in a 73 year-old man with cognitive deficits and fluent dysphasia. he harboured an intraventricular tumor, placed at the trigone of the left lateral ventricle. the tumor was successfully excised, by means of a temporal craniotomy. the patient became mute in the immediate postoperative with restoration of speech within a few days. the literature has been reviewed and only three other similar cases have been reported. discovery of lesions in such unusual location should raise a high degree of suspicion for von hippel- lindau disease.
BIT y la Constitución colombiana de 1991: internacionalización de la economía dentro de un Estado Social de Derecho
Prieto-Ríos,Enrique Alberto;
Estudios Socio-Jurídicos , 2011,
Abstract: a discussion of the twenty years of the constitution from today's perspective necessarily implies an analysis of the opening, internationalization and insertion of the colombian economy in the global markets and its effects on the nation's economy and on society. this article discusses the development of bilateral investment agreements (bits, or appri by its acronym in spanish), within the framework of the colombian constitution of 1991 and the importance given by the colombian government to these treaties as a tool for economic, technological and scientific development. in this sense, this paper begins by analyzing the treaties and their development in the international scene. then it focuses on the bits in colombia in the light of constitutional court jurisprudence and rulings on the matter. special emphasis is made on the issue of expropriation of foreign investments in colombia under the constitution of 1991, the contradiction between the constitution and the bits, and the solution given to the controversy by colombian congress. lastly, the article makes a theoretical critique on the effectiveness and necessity of these treaties for colombian society.
Historia de la vegetación en relación con la evolución geomorfológica de las llanuras costeras del este de la provincia de Buenos Aires durante el Holoceno
Vilanova,Isabel; Prieto,Aldo R.; Stutz,Silvina;
Ameghiniana , 2006,
Abstract: changes in vegetation communities of the eastern coastal plains of buenos aires province during the holocene were reconstructed based on the comparison of palynological records from two radiocarbon dated cores located north (t9-1, 36° 45' s; 56° 37' w) and south (la lagunita, 37° 43' s; 57° 21' w) of villa gesell headland. between 5,400 and 3,300 14c yr b.p. pollen records suggest the development of similar mosaics of halophytic-psammophytic communities at both sites, on tidal plains related to littoral barriers prograding simultaneously to the north and south of the villa gesell headland during the regressive event when sea level was stabilized. the poaceae/chenopodiaceae index (pci) fluctuations suggest environmental instability as a consequence of barriers changes. from ca . 3,300 14c yr b.p. vegetation communities changed and differentiated at both sides of villa gesell headland simultaneously with the stabilization of the environments during the sea level regression, as it is reflected by a change in pci with similar values and sign. to the north, at ca . 3,300 14c yr b.p. the mosaic of halophytic-psammophytic communities from environments associated to the barrier was replaced by a community placed on stabilized sand dunes associated with the advance toward the north of beach ridges of the barrier. to the south, at ca . 2,500 14c yr b.p. halophytic communities dominated by chenopodiaceae were established reaching a higher development in a sheltered salt marsh and coastal lagoon environment, delimited by the rapid southwest progradation of the barrier.
Estudios arqueológicos en el Río Desaguadero (Mendoza)
Chiavazza,Horacio; Prieto,María del R;
Runa , 2008,
Abstract: by means of archaeological studies developed in the western margin of the desaguadero river, in the limit between the provinces of mendoza and san luis, it is investigated about the prehispanic occupational characteristics in humedal locating that is inserted within a arid environment the northeast plain of mendoza.
Antisense oligonucleotides and the rational design of new antitumor drugs Los oligonucleótidos antisentido y el dise o racional de nuevos fármacos antitumorales
J. Prieto,R. Hernández-Alcoceba
Revista Espa?ola de Enfermedades Digestivas , 2005,
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