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Search Results: 1 - 10 of 404480 matches for " Federico; Márquez "
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Waterbird occurrence and abundance in the Strobel Plateau, Patagonia, Argentina
Lancelotti,Julio L.; Pozzi,Luciana M.; Márquez,Federico; Yorio,Pablo; Pascual,Miguel A.;
El hornero , 2009,
Abstract: the strobel plateau is a conspicuous and representative basaltic plateau ("meseta") in the patagonian steppe, argentina. this plateau is dotted with more than 1500 shallow lakes, which are regularly used by waterbirds and support one of the main breeding populations of the near threatened hooded grebe (podiceps gallardoi). we collected data on bird presence and abundance in 41 shallow lakes, covering a wide spectrum of the wetland environmental variability found in the area. we conducted six surveys from spring to fall between 2004 and 2006. we recorded a total of 18 waterbird species, which represent 5 different families. anatidae was the family most represented with 12 species, accounting for 85% of the observed waterbirds. waterbird distribution among lakes was variable, from 2.4% occupied lakes for wilson's phalarope (steganopus tricolor) and andean ruddy-duck (oxyura jamaicensis) to 80% for black-necked swan (cygnus melanocorypha), and abundance varied greatly both between species and seasons. the hooded grebe, in particular, was recorded in 14 lakes (1-81 individuals). six species were detected breeding in the area: hooded grebe, silvery grebe (podiceps occipitalis), flying steamer-duck (tachyeres patachonicus), crested duck (anas specularioides), upland goose (chloephaga picta), and white-winged coot (fulica leucoptera). the hooded grebe nested at four lakes, three of them not previously known to hold breeding birds. results point to the need of further studies on the dynamic nature of waterbird lake use to adequately assess the importance of the strobel plateau as waterbird habitat.
Distribución de esfuerzos en tramos protésicos fijos de cinco unidades con pilar intermedio: análisis biomecánico utilizando un modelo de elementos finitos
Márquez Córdoba,Carolina; Escobar Restrepo,Julio César; latorre Correa,Federico; Villarraga Ossa,Junes;
Revista Facultad de Odontología Universidad de Antioquia , 2011,
Abstract: introduction: the purpose of this study is to establish the mechanical behavior between rigid and non-rigid fixed dental prosthesis of five units with an intermediate abutment using the finite element analysis (fea). methods: non-metric dental traits were observed using the standard asudas and other authors, in total 165 non metric traits were examined. an x2 distribution test was used to identify significant differences. results: 31 traits showed statistical significant differences on both sides of the arches. results and conclusions: a five unit rigid model with 124.469 nodes and 76.215 elements and a non-rigid model with 125.130 nodes and 77.396 elements were designed. it consisted of trabecular bone, cortical bone, periodontal ligament, pulp, dentine, root, resinous cement, metal ceramic crowns and tube-lock adjustment (sterngold?, implamed attleboro ma). the fixed dental prosthesis included a central incisor, lateral incisor, canine, first and second upper premolars. a force of 200 n was applied with an oblique and vertical direction. the variables included in the model were modulus of elasticity, poissonás ratio and non-rigid adjustment. von misses stresses, main, maximum and minimum, were calculated for each group.
Aspectos de la biología poblacional en el campo de Anolis aquaticus, Sauria: Polychridae en Costa Rica
Cruz Márquez,José Manuel Mora,Federico Bola?os,Solanda Rea
Ecología Aplicada , 2005,
Abstract: Se estudió Anolis aquaticus (Taylor, 1956) en la quebrada La Palma de Puriscal (9o45 N, 84o27 O). Métodos de muestreo sistemáticos mensuales en captura, recaptura y medidas fueron desarrollados durante el estudio. El color de ambos sexos de los A. a. es marrón con bandas verde claro verticales en el cuerpo y la cola; cuando salieron de las grietas presentaron color marrón oscuro sin bandas. El macho es de mayor tama o que la hembra en las 13 regiones corporales medidas. Los machos mantienen en su territorio de una a tres hembras, las hembras no toleran el ingreso de otra hembra a su territorio. La proporción de sexo en la población, no varió de 1:1. Las hembras alcanzan la madurez sexual entre los 4 y 6 meses y los machos entre los 5 y 7 meses, después del nacimiento. Luego de un desove hembras menores de 64 mm de Longitud Hocico Ano (LHA), recuperan su peso fácilmente, mientras que hembras mayores de 64 mm de LHA, no lo recuperan, algunas no lo logran y mueren por inanición. Las tasas de crecimiento en LHA y peso, son aproximadamente iguales en ambos sexos adultos y difieren significativamente, de la, de los juveniles. Existe una sustancial diferencia entre las tasas de crecimiento de animales creciendo en cautiverio con los que crecen en condiciones naturales. En el porcentaje de reclutamiento, los sexos no son diferentes. Información es discutida más adelante.
Distribución de esfuerzos en tramos protésicos fijos de cinco unidades con pilar intermedio: análisis biomecánico utilizando un modelo de elementos finitos Stress distribution on a five unit fixed partial prosthesis with intermediate abutment: biomechanical analysis using a finite element model
Carolina Márquez Córdoba,Julio César Escobar Restrepo,Federico latorre Correa,Junes Villarraga Ossa
Revista Facultad de Odontología Universidad de Antioquia , 2011,
Abstract: INTRODUCCIóN: el presente estudio pretendió determinar el comportamiento mecánico entre tramos protésicos rígidos y no rígidos de una prótesis fija de cinco unidades con pilar intermedio utilizando el análisis de elementos finitos (AEF). MéTODOS: se dise ó un modelo rígido de cinco unidades con 124,469 nodos y 76,215 elementos y un modelo no rígido con 125,130 nodos y 77,396 elementos, conformados por hueso esponjoso, hueso cortical, ligamento periodontal, pulpa, dentina, raíz, cemento resinoso, coronas metal-cerámica y ajuste tuve-lock (Sterngold , Implamed Attleboro MA). El tramo protésico comprendió un incisivo central, un incisivo lateral, un canino, un primer premolar y un segundo premolar superior. Se aplicó una fuerza de 200 N con dirección oblicua y vertical. Las variables incluidas en el modelado fueron módulo de elasticidad, razón de Poisson y el ajuste no rígido. Fueron calculados los esfuerzos von Misses, máximos principales y mínimos principales para cada grupo. RESULTADOS Y CONCLUSIONES: el análisis del comportamiento mecánico indicó que en el tramo protésico rígido hubo mejor distribución de los esfuerzos en relación con el modelo no rígido. El comportamiento de cada grupo indicó que el modelo rígido transmitió menos esfuerzo a la raíz y al hueso subyacente. La influencia de poner un ajuste no se justificaría según los resultados de este estudio. INTRODUCTION: the purpose of this study is to establish the mechanical behavior between rigid and non-rigid fixed dental prosthesis of five units with an intermediate abutment using the finite element analysis (FEA). METHODS: non-metric dental traits were observed using the Standard ASUDAS and other authors, in total 165 non metric traits were examined. An x2 distribution test was used to identify significant differences. Results: 31 traits showed statistical significant differences on both sides of the arches. RESULTS AND CONCLUSIONS: a five unit rigid model with 124.469 nodes and 76.215 elements and a non-rigid model with 125.130 nodes and 77.396 elements were designed. It consisted of trabecular bone, cortical bone, periodontal ligament, pulp, dentine, root, resinous cement, metal ceramic crowns and tube-lock adjustment (Sterngold , Implamed Attleboro MA). The fixed dental prosthesis included a central incisor, lateral incisor, canine, first and second upper premolars. A force of 200 N was applied with an oblique and vertical direction. The variables included in the model were modulus of elasticity, Poissonás ratio and non-rigid adjustment. Von Misses stresses, main, maximum and minimum, were
Nitrógeno y fósforo totales de los ríos tributarios al sistema lago de Maracaibo, Venezuela
Rivas,Zulay; Sánchez,José; Troncone,Federico; Márquez,Rómulo; Ledo de Medina,Hilda; Colina,Marinela; Gutiérrez,Elizabeth;
Interciencia , 2009,
Abstract: nitrogen and phosphorus are primary nutrients, common constituents of fertilizers, detergents, and domestic and industrial wastewater discharges. these unloadings to rivers and subsequently to lake maracaibo cause nutrient and mineral enrichment, producing a secondary eutrophication on rivers and detained waters at deltas. lake maracaibo system is a basin of extraordinary importance because of its energetic resources, biodiversity and the wide number of aquatic organisms, which represents an important economic source for the country. however, activities being developed on the basin such as agricultural, cattle raising, mining and industrials, have modified the physical, chemical and biological characteristics of both water and soil generating an accelerated eutrophication process, as well as, the appearance of dense populations of the aquatic weed lemna obscura, generating social, environmental and economic impacts. the following river basins were evaluated: limón, palmar, santa ana, catatumbo, escalante, chama, motatán, misoa, machango and pueblo viejo. these rivers contribute with 80% of the freshwater to the lake maracaibo system, being the catatumbo river contribution 60% of the volume. total nitrogen and total phosphorus average of rivers that drain to the lake, was 1.20 and 0.84 mgl-1, respectively, contributing significantly with the process of eutrophication, that combined with the expansion of the agricultural borders, have caused deforestation, erosion and contamination, altering landscape and water availability, as well as an important increase of nutrients in lake maracaibo.
A randomized, double blind, cross-over, placebo-controlled clinical trial to assess the effects of Candesartan on the insulin sensitivity on non diabetic, non hypertense subjects with dysglyce mia and abdominal obesity. "ARAMIA"
Patricio López-Jaramillo, Lina P Pradilla, Vicente Lahera, Federico Sieger, Christian F Rueda-Clausen, Gustavo A Márquez
Trials , 2006, DOI: 10.1186/1745-6215-7-28
Abstract: A randomized, double blind, cross-over, placebo-controlled, clinical trial was designed to assess the effects of Candesartan (up to 32 mg/day during 6 months) on the Homeostasis Model Assessment (HOMA) index, lipid profile, protrombotic state, oxidative stress and plasma levels of inflammatory markers. The participants will be recruited in the "Fundación Cardiovascular de Colombia". Subjects who fullfil selection criteria will receive permanent educational, nutritional and exercise support during their participation in the study. After a 15 days-run-in period with placebo and life-style recommendations, the patients who have a treatment compliance equal or greater than 80% will be randomlly assigned to one of the treatment groups. Group A will receive Candesartan during 6 months and placebo during 6 months. Group B will receive placebo during the first 6 months, and then, Candesartan during the last 6 months. Control visits will be programed monthly and all parameters of interest will be evaluated every 6 months.Treatment with Candesartan, could improve the HOMA index, the response to the oral glucose tolerance test and reduce the plasma levels of adipoquines, oxidative stress and prothrombotic markers, in non diabetic, non hypertense subjects with dysglycemia and abdominal obesity, recruited from a population at high risk of developing insulin resistance. These effects are independent of the changes in arterial blood pressure. Trial registration: NCT00319202During the second half of the 20th century the prevalence of type-2 diabetes mellitus (DM2) has increased dramatically all over the world [1]. It has been estimated that more than 171 million people suffer from this disease and that this number could increase to 366 million by 2030, of which 298 million would be from developing countries [2]. Currently, in Latin America, the DM2 prevalence ranges from 1.2% to 8%, and it is expected to increase to 38% during the next 10 years [3]. This epidemic has been related w
Nanomaterials for Drugs Delivery  [PDF]
Francisco Márquez, Carmen Morant
Soft Nanoscience Letters (SNL) , 2014, DOI: 10.4236/snl.2014.43007
Abstract:

As expected for years, nanotechnology has revolutionized engineering, biology, chemistry, physics and medicine of today. These disciplines are evolving thanks to the ongoing development of new materials and applications. Nanomedicine, as application of nanotechnology in the field of health care, has undergone unprecedented development. Some of these changes have real applications as, for example, the use of nanoparticles in MRI imaging, in hyperthermia, in immunotherapy, or to improve the bioavailability of drugs, among others [1]-[3].

When a drug is administered to a patient, the blood distributes it throughout the body. In the case of very localized diseases (i.e. tumors), only a small fraction of the drug reaches the target. Chemotherapy is one of the most aggressive treatment options used in some types of cancer, and is usually administered intravenously. In this type of therapy, the drug circulates throughout the body, reaching and destroying healthy and cancerous tissues, producing side effects throughout the body, sometimes with serious consequences for the health of the patient (nephrotoxicity, cardiotoxicity, peripheral neuropathy, anemia, etc.). Among the many applications of nanotechnology, the fabrication of nanostructures capable of safely transporting these drugs is seen as a strategy for reducing these side effects. Nanoparticles are able to carry and release the drug in the right place and with the required dose, greatly reducing the problems associated with direct treatment with these drugs.

In recent years, there have been continuous improvements in the design and development of new tailor-made drug delivery systems [4], including hollow magnetic nanoparticles, liposomal structures, dendrimers, nanoporous silicon, etc. These structures can be obtained with different molecular weights (in the case of polymers), structures, shapes, and even with the appropriate functional groups for interaction at the desired positions. However, a great effort is still required to solve many of the current problems [5], including toxicity, aggregation, solubility and stability in the human body, physiological processes of elimination, identification of targets by highly specific receptors, controlled drug release over time, etc.

Nanomaterials for Sensor Applications  [PDF]
Francisco Márquez, Carmen Morant
Soft Nanoscience Letters (SNL) , 2015, DOI: 10.4236/snl.2015.51001
Abstract: Recently, a large part of the advances in nanotechnology have been directed towards the development of high-speed electronics, more efficient catalysts, and sensors. This latter group of applications has great relevance and unprecedented development potential for the coming years.So far, some of the main objectives for the development of sensors have focused on making more sensitive, effective and specific sensing devices.The improvement of these systems and the increase of specificity are clearly associated with a decrease in size of the components, which can lead to obtaining more rapid action, almost in real time. Nanomaterials currently used in sensor development include a long list of nanostructured systems, as for example: metal nanotubes, nanowires, nanofibers, nanocomposites, nanorods, nanoparticles, nanostructured polymers, and different allotropes of carbon as carbon nanotubes, graphene or fullerenes, among others.
Electron Confinement Effect of Laser Dyes within Dendritic Structures  [PDF]
Francisco Márquez, María José Sabater
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2011, DOI: 10.4236/jeas.2011.11001
Abstract: Dendrimers are a novel class of nanometric-size macromolecules with a regular tree-dimensional like array of branch units.1,2 Their synthetic availability in a wide range of sizes combined with their peculiar architecture makes them versatile building blocks for a wide range of potential applications.3 Some years ago, Meijer and co-workers reported that the modification of terminal amine functionalities of a fifth generation poly(propyleneimine) dendrimer (DAB-dendr-(NH2)64) with bulky substituents, (typically N-t-BOC protected phenylalanine), results in the formation of the so-called “dendritic box” (DAB-dendr-(NH-t-BOC-L-Phe)64).4 Within this macromolecular structure it is possible to encapsulate a variety of guest molecules due to the existence of internal cavities in the core. The photophysical properties of the guests can be modulated by the innovative electron confinement effect. In this respect, we wish to report that the emission frequency of organic dyes can be easily modulated by encapsulation in a dendritic box. The emission bands of dye molecules incorporated into a dendrimer can effectively be red shifted with respect to their emission in solution and contrary to other confined spaces of considerable hardness, the magnitude of this shifting can be regulated under appropriate experimental conditions. This peculiar effect could have unprecedented applications in the development of supramolecular devices relating to the frequency tuning of organic laser dyes.
PPAR and Local Renin-Angiotensin Systems in Cardiovascular and Metabolic Diseases Associated with Obesity: A Unifying Hypothesis  [PDF]
Gustavo Márquez-Salom, Javier Diez
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2013, DOI: 10.4236/ojemd.2013.35A001
Abstract:

Recent research has revealed roles for the PPAR family of transcription factors in the modulation of the RAAS. In particular, PPARα and PPARγ have been shown to control the transcription of renin in several tissues and influence the activity of local renin-angiotensin-systems coupling vascular and metabolic functions and contributing to their modulation. In this conceptual framework, PPAR and local RAS participate in the pathophysiology of blood pressure elevation, as well as in organ and tissue damage, and disturbances of glucose and lipid metabolism associated with cardiovascular diseases and obesity. The understanding of these mechanisms here discussed and their adequate pharmacological manipulation enlarge the potential to intervene pathological processes that connect the obesity with associate diseases and could alert about the adverse effects of some PPAR agonists on involved organs.

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