oalib

OALib Journal期刊

ISSN: 2333-9721

费用:600人民币/ 99美元

投稿

时间不限

2017 ( 38 )

2016 ( 255 )

2015 ( 5142 )

2014 ( 6181 )

自定义范围…

匹配条件: “Félix Nieto Palomo” ,找到相关结果约145729条。
列表显示的所有文章,均可免费获取
第1页/共145729条
每页显示
Hemodynamic of abdominal aortic aneurysm (AAA) and morphometryc characterization as a possible indicator of rupture Hemodinámica de aneurismas de aorta abdominal (AAA) y caracterización morfométrica como posible indicador de ruptura
Guillermo Vilalta Alonso,Félix Nieto Palomo,Melchor Rodríguez Madrigal,Laurentiu Lipsa
Revista Cubana de Ingeniería , 2010, DOI: 10.1234/rci.v1i3.25
Abstract: The rupture of abdominal aortic aneurysm (AAA) represents an important clinical event combining structural modifications that provoke a weakening of the arterial wall, coupled with the hemodynamic pressure acting on them. In an effort to increase understanding about this complex phenomenon, this paper studies the influence of abdominal aortic aneurysm asymmetry in the patterns of the main hemodynamics factors. Flow simulation in four 3D virtual AAA models with different asymmetry ranging from 0.2 to 0.8 were carried out under realistic pulsatile conditions to assess and identify regions with disturbed patterns flow and how it modifies the velocities fields and hemodynamic stress on the inside of the aneurysmatic sac. An explanation of the vortex structure changes and stress distribution during cardiac pulse, it is presented. The results obtained shown that the asymmetry is one of the main factors that influence the AAA rupture. On the other hand, the basis to establish a novel method, based on the morphometry of the AAA, to determine a numerical indicator characterizing the evolution and the rupture risk of aneurysm, regardless of size, it is approached. It is outlined the initial results of the validation, its current limitations and the future steps to improve the method. La ruptura de aneurismas de aorta abdominal (AAA) representan un evento clínico muy importante resultante de las modificaciones estructurales de la pared arterial que provocan un debilitamiento de la pared arterial combinadas con las presiones hemodinámicas que actúan sobre esta. En un esfuerzo por aumentar la comprensión sobre este complejo fenómeno, en el presente trabajo se estudia la influencia del grado de asimetría de los aneurismas de aorta abdominal, en los patrones de comportamiento de los principales factores hemodinámicos. Para esto, se han evaluado 4 modelos geométricos no realistas de AAA con diferentes grados de asimetría, sometidos a un flujo pulsatil fisiológicamente realista, con el objetivo de evaluar e identificar las regiones donde ocurren las principales perturbaciones en los patrones de flujo y como ésta modifica los campos de velocidades y de tensiones hemodinámicas, en el interior del saco aneurismático. Se presenta una explicación de las modificaciones de las estructuras vorticales y de la distribución de tensiones durante el ciclo cardíaco, cuyos resultados confirman que la asimetría de los aneurismas de aorta abdominal es uno de los principales factores que influyen en su ruptura. Por otro lado, en el trabajo se abordan las bases para establecer un método
Modificaciones Hemodinámicas Asociadas a la Asimetría de Aneurismas de Aorta Abdominal y su Influencia en las Posibilidades de Ruptura
Nieto,Félix; Vilalta,Guillermo; Peréz,María á; Lipsa,Laurentiu M;
Información tecnológica , 2012, DOI: 10.4067/S0718-07642012000300017
Abstract: influence of abdominal aortic aneurysms asymmetry on the hemodynamics within the aneurysmatic sac is analyzed and its influence on the rupture potential is discussed. a numerical study by using four idealized geometric models, with different asymmetry degrees, is carried out. blood is modelled as a newtonian, homogeneous, incompressible and laminar flow with properties as typically used in the literature. the results showed that the flow inside of the aneurysmatic sac is highly disturbed with intense vortex structures travelling from proximal to distal ends, strongly influencing on the wall shear stress distribution. it have also been established that, despite that the aneurysm are asymmetric, this factor has low weight on aneurysm rupture.
Modificaciones Hemodinámicas Asociadas a la Asimetría de Aneurismas de Aorta Abdominal y su Influencia en las Posibilidades de Ruptura Hemodynamic Modifications Associated to Abdominal Aortic Aneurysm Asymmetry and its Influence on Rupture Potential
Félix Nieto,Guillermo Vilalta,María á Peréz,Laurentiu M Lipsa
Información Tecnológica , 2012,
Abstract: Se analiza la influencia de la asimetría de los aneurismas de aorta abdominal en la dinámica del flujo sanguíneo en el interior del saco aneurismático y se discute cómo este comportamiento puede influir en el potencial de ruptura de los aneurismas. Para ello se realiza un estudio numérico empleando cuatro modelos geométricos idealizados con diferente grado de asimetría. La sangre es modelada como Newtoniana, homogénea, incompresible y laminar con propiedades semejantes a los valores que típicamente se emplean en la literatura. Los resultados mostraron que el flujo en el interior del saco aneurismático es altamente perturbado con intensas estructuras de vórtices que viajan desde el extremo proximal al distal, ejerciendo una gran influencia en la distribución superficial de las tensiones tangenciales. También se ha establecido que, a pesar que los aneurismas son asimétricos, este factor tiene un peso ponderado bajo en las posibilidades de ruptura de los aneurismas. Influence of abdominal aortic aneurysms asymmetry on the hemodynamics within the aneurysmatic sac is analyzed and its influence on the rupture potential is discussed. A numerical study by using four idealized geometric models, with different asymmetry degrees, is carried out. Blood is modelled as a newtonian, homogeneous, incompressible and laminar flow with properties as typically used in the literature. The results showed that the flow inside of the aneurysmatic sac is highly disturbed with intense vortex structures travelling from proximal to distal ends, strongly influencing on the wall shear stress distribution. It have also been established that, despite that the aneurysm are asymmetric, this factor has low weight on aneurysm rupture.
Factores Pronósticos en la Peritonitis
Magalys de la Caridad álvarez B.,Marcos D. Iraola F.,Pedro R. Nieto P.,Félix Molina D.
Medicrit : Revista de Medicina Crítica , 2006, DOI: 10.5413/mrmc.2006.32.65
Abstract: Objetivo. Conocer los factores pronósticos de muerte y la validez del índice de Peritonitis de Mannheimer (IPM) como índice pronóstico en la peritonitis. Dise o. Estudio prospectivo observacional. Materiales y métodos. Entre el primero de enero y el treinta de junio de 1997, fueron admitidos en la UCI 336 pacientes de los cuales 38 (11.3%) tenían diagnóstico de peritonitis. Se confeccionó un modelo de recolección de datos que se ajustaba a los objetivos del estudio y que incluía el IPM, el Therapeutic Intervention Scoring System (TISS) y el índice de Disfunción Orgánica Múltiple (IDOM). Resultados. La mayoría de los pacientes tenían peritonitis secundaria (84.2%) y el resto abscesos intraabdominales (15.8%). En el análisis univariado sólo dos factores se relacionaron significativamente con la muerte, la necesidad de ventilación mecánica (OR: 17.4; IC 95%: 1.17-545.8; p=0.02) y el hecho de que la peritonitis fuera causada por úlcera gástrica (OR: 33.0; IC 95%: 1.35-1714.2; p=0.02). Al comparar los valores medios entre fallecidos y vivos se encontró diferencias significativas en la edad (55.0 ± 2.94 vs 34.6 ± 14.7; p=0.01), TISS al ingreso (27.0 ± 2.94 vs 19.4 ± 6.51; p=0.02), TISS al egreso (30.7 ± 2.5 vs 8.0 ± 1.9; p=0.00) y en el IDOM (8.0 ±2.6 vs 1.0 vs 1.4 ± 1.4; p=0.00). El IPM mostró una sensibilidad de 50%, una especificidad de 73.3% con un valor predictivo positivo de 18% y un valor predictivo negativo de 92.6%. Conclusiones. La ventilación mecánica y la úlcera gástrica resultaron en el análisis univariado los factores pronósticos significativos para la predicción de la muerte; el IPM demostró tener una alta especificidad, sin embargo mostró una baja sensibilidad. Palabras clave: Peritonitis; Mortalidad; Factores Pronósticos; índice de Peritonitis de Mannheimer.
Ruptura de aneurismas de aorta abdominal. Herramienta informática para su predicción
Vilalta-Alonso,Guillermo; Nieto,Félix; Vilalta-Alonso,José A.; Vaquero,Carlos; Lipsa,Laurentiu M.; Rodríguez-Madrigal,Melchor;
Ingenier?-a Mec??nica , 2011,
Abstract: the rupture of abdominal aortic aneurysm (aaa) represents an important clinical event due to its high mortality rate. currently the criteria to decide on the treatment of aaa patients are the peak transverse diameter and the growth rate which can be considered insufficient because they have not a reasonable physical base. the foundations for the design of pc software to predict, with sufficient accuracy to be clinically relevant, the risk of aaa rupture on patient-specific basis are defined in this paper. the software consists of 3 modules which are designed for processing all patient-specific information and integrate them through a model that interrelates the different nature (biological, structural and geometric) and scales (temporal and dimensional) biomechanical factors, in order to calculate a numerical and patient-specific indicator of the rupture risk. this tool should be an auxiliary element to physician in making decision on appropriate treatment decisions for patients with aneurysm.
Megalithic Constructions Discovered in the Azores, Portugal  [PDF]
António Félix Rodrigues
Archaeological Discovery (AD) , 2015, DOI: 10.4236/ad.2015.32006
Abstract: The oldest cave art known is of prehistoric origin, dating back to approximately 40,000 years ago in both Asia and Europe. The megalithic constructions in Western Europe and the Mediterranean Region took place mainly in the Neolithic and continued until the Chalcolithic and Bronze Age. The Azores Islands did not seem to have been occupied before the arrival of the Portuguese navigators in the XVth century. Because of that, it was not expected that megalithic structures would be found, or structures that resembled megalithic tombs and rock art in the Azores Islands, geographically located in the Center of the North Atlantic, at 1500 km west of Lisbon (Portugal) and about 1900 km southeast of Newfoundland (Canada). These findings seem to be, historically, a paradox. In a first moment, an oral presentation was made about these findings by the author at the 16th Annual Mediterranean Studies Association Congress, and after that, a field trip took place with the archeologists present at the stated Congress. The perplexity was the dominant conduct of the guests, and some hypotheses that certain archaeologists mentioned were evolved versions which had not been empirically corroborated. Afterwards, new findings were registered at Grota do Medo site, helping to make clear that larger stones had been used to construct structures or monuments. The rock art surrounding the megalithic constructions in the Azores also has similarities with those found in Europe. If these findings belong to the Bronze Age or Iron Age, it can reopen new scientific questions about ancient mid-Atlantic crossings. The present article tries to establish ties among the megalith constructions found in the Azores with those known in Europe.
Are ‘Endurance’ Alleles ‘Survival’ Alleles? Insights from the ACTN3 R577X Polymorphism
Carmen Fiuza-Luces,Jonatan R. Ruiz,Gabriel Rodríguez-Romo,Catalina Santiago,Félix Gómez-Gallego,Thomas Yvert,Amalia Cano-Nieto,Nuria Garatachea,María Morán,Alejandro Lucia
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017558
Abstract: Exercise phenotypes have played a key role for ensuring survival over human evolution. We speculated that some genetic variants that influence exercise phenotypes could be associated with exceptional survival (i.e. reaching ≥100years of age). Owing to its effects on muscle structure/function, a potential candidate is the Arg(R)577Ter(X) polymorphism (rs1815739) in ACTN3, the structural gene encoding the skeletal muscle protein α-actinin-3. We compared the ACTN3 R577X genotype/allele frequencies between the following groups of ethnically-matched (Spanish) individuals: centenarians (cases, n = 64; 57 female; age range: 100–108 years), young healthy controls (n = 283, 67 females, 216 males; 21±2 years), and humans who are at the two end-points of exercise capacity phenotypes, i.e. muscle endurance (50 male professional road cyclists) and muscle power (63 male jumpers/sprinters). Although there were no differences in genotype/allele frequencies between centenarians (RR:28.8%; RX:47.5%; XX:23.7%), and controls (RR:31.8%; RX:49.8%; XX:18.4%) or endurance athletes (RR:28.0%; RX:46%; XX:26.0%), we observed a significantly higher frequency of the X allele (P = 0.019) and XX genotype (P = 0.011) in centenarians compared with power athletes (RR:47.6%; RX:36.5%;XX:15.9%). Notably, the frequency of the null XX (α-actinin-3 deficient) genotype in centenarians was the highest ever reported in non-athletic Caucasian populations. In conclusion, despite there were no significant differences with the younger, control population, overall the ACTN3 genotype of centenarians resembles that of world-class elite endurance athletes and differs from that of elite power athletes. Our preliminary data would suggest a certain ‘survival’ advantage brought about by α-actinin-3 deficiency and the ‘endurance’/oxidative muscle phenotype that is commonly associated with this condition.
Solid solubility of MgO in the calcium silicates of portland clinker. The effect of CaF2
Martínez, S.,Puertas, F.,Palomo, A.
Materiales de Construccion , 1992,
Abstract: The solid solubility of MgO in the calcium silicates of portland clinker has been determined by XRD and XDS. The influence that the presence of CaF2 has on said solubility has also been verified. The solid solution limit of MgO in C3S at 1275 oC lies at about 1.0% wt, where the triclinic form II stabilizes. The presence of CaF2 does not alter the maximum value of the MgO solubilized in that silicate, although there does take place the stabilization of the triclinic polymorph II at lower MgO contents (between 0.3 - 0.6% wt). The maximum amount of solubilized MgO in βC2 at 1.050 oC lies around 0.5% wt. This value does not change by the presence of CaF2. Se ha determinado por DRX y EDX la solubilidad sólida del MgO en los silicatos cálcicos del clínker portland. Se ha comprobado, así mismo la influencia que sobre dicha solubilidad tiene la presencia de CaF2. El límite de disolución sólida del MgO en el C3S a 1.275o C se sitúa alrededor del 1,0% en peso, estabilizándose la forma triclínica II. La presencia de CaF2 no altera el valor máximo de MgO solubilizado en este silicato, aunque si se produce la estabilización del polimorfo triclínico II a contenidos menores de MgO (entre 0,3 – 0,6% en peso). La cantidad máxima de MgO solubilizado en e/ βC2S a 1.050 oC se sitúa en torno al 0,5% en peso. Este valor no se ve modificado por la presencia de CaF2.
El valor de la propiedad intelectual en los países en desarrollo
Rozanski,Félix;
Interciencia , 2003,
Abstract: summary the agreement on trade-related aspects of intellectual property rights (trips), in force since 1995, operating under the orbit of the world trade organization (wto), constitutes a global milestone in the development of intellectual property protection under its different forms. this is particularly evident in the latin american countries, where it is necessary to update the norms regulating these rights. as the cooperation between science and the private sector is gaining ground, in comparison with the former model in which public funding of scientific activities was almost exclusive, the adequate protection of intellectual property becomes increasingly relevant also for the scientific sector. scientific findings in order to become patentable require an invention, product or process, that must be new, involve an inventive step, and be capable of industrial application. another form of protection, different and independent of patents is the protection of undisclosed information. public policies that favor intellectual property protection are more related to achieve growth promoting innovation, application and transfer of technology, and quality improvement.
CO-CONSTRUCCIONES EN ESPA?OL: ?COOPERACIóN POR MEDIO DE UNA INTERRUPCIóN?
Burgos,Félix Manuel;
Forma y Función , 2007,
Abstract: this article proposes a review of the co-construction phenomena, understood as the realization of a syntactic unit throughout the contribution of two participants during a conversation. it analyzes 81 cases from spanish casual conversations in cali, colombia . taking into consideration different explanations given as causes of this phenomenon, three variables are proposed to confirm these hypotheses on the studied examples. these variables correspond to: 1. a conversational interaction perspective, where shared cognitive models by the participants are taken into account (lerner, 1991). 2 a syntactic approximation, where the grammatical characteristics of the components are analyzed (ford y thompson, 1996), y 3. a prosodic approach focused in interrupted units (helasvuo, 2004). it is proposed that the theses suggested as causes of the co-construction appearance do have incidence in the studied examples. however, it is shown that in general these units cannot be explained by an isolated cause, but for multiple factors, where syntax and prosody are combined. finally, it is proposed that what at first sight could be considered a conflictive fact of the conversation, an interruption, is a conversational cooperation act.
第1页/共145729条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.