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Search Results: 1 - 10 of 586719 matches for " Néstor J López "
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Aterosclerosis en sujetos con periodontitis
López,Néstor J; Chamorro,Adriana; Llancaqueo,Marcelo;
Revista médica de Chile , 2011, DOI: 10.4067/S0034-98872011000600004
Abstract: background: chronic infl ammation and infections are involved in the development and progression of atherosclerotic vascular disease. aim: to evaluate the association between periodontitis and early atherosclerosis. material and methods: fifty-three subjects who received periodontal treatment and regular maintenance for at least 10 years, and 55 subjects with periodontitis but without a history of periodontal treatment were studied. carotid artery intima-media wall thickness (cimt) was measured with high-resolution b-mode ultrasonography. a blood sample was obtained to measure high sensitivity c-reactive protein, fibrinogen, lipoprotein cholesterol, leukocyte count and erythrocyte sedimentation rate. covariates included age, gender, smoking, level of education, body mass index and physical activity. the benzoyl-dl-arginine-naphthylamide (bana) test was used to determine the number of periodontal sites with periodontal pathogens. results: cimt value was significantly higher in subjects with periodontitis than those without it (0.775 ± 0.268 and 0.683 ± 0.131 mm respectively, p = 0.027). c-reactive protein, leukocyte count and percentage of sites with periodontal pathogens were also significantly higher in subjects with periodontitis. regression analysis identified age, periodontitis, and smoking as independent predictors of cimt. conclusions: these results suggest that untreated periodontitis is associated with early atherosclerotic carotid lesions and higher levels of infl ammatory markers.
Aterosclerosis en sujetos con periodontitis Association between atherosclerosis and periodontitis
Néstor J López,Adriana Chamorro,Marcelo Llancaqueo
Revista médica de Chile , 2011,
Abstract: Background: Chronic infl ammation and infections are involved in the development and progression of atherosclerotic vascular disease. Aim: To evaluate the association between periodontitis and early atherosclerosis. Material and Methods: Fifty-three subjects who received periodontal treatment and regular maintenance for at least 10 years, and 55 subjects with periodontitis but without a history of periodontal treatment were studied. Carotid artery intima-media wall thickness (CIMT) was measured with high-resolution B-mode ultrasonography. A blood sample was obtained to measure high sensitivity C-reactive protein, fibrinogen, lipoprotein cholesterol, leukocyte count and erythrocyte sedimentation rate. Covariates included age, gender, smoking, level of education, body mass index and physical activity. The benzoyl-DL-arginine-naphthylamide (BANA) test was used to determine the number of periodontal sites with periodontal pathogens. Results: CIMT value was significantly higher in subjects with periodontitis than those without it (0.775 ± 0.268 and 0.683 ± 0.131 mm respectively, p = 0.027). C-reactive protein, leukocyte count and percentage of sites with periodontal pathogens were also significantly higher in subjects with periodontitis. Regression analysis identified age, periodontitis, and smoking as independent predictors of CIMT. Conclusions: These results suggest that untreated periodontitis is associated with early atherosclerotic carotid lesions and higher levels of infl ammatory markers.
Efectos del tratamiento periodontal sobre los marcadores de inflamación sistémica en pacientes con riesgo de enfermedad cardiaca coronaria: Estudio piloto
López,Néstor J; Quintero,Antonio; Llancaqueo,Marcelo; Jara,Lilian;
Revista médica de Chile , 2009, DOI: 10.4067/S0034-98872009001000006
Abstract: background- studies investigating effects of periodontal treatment (pt) on markers of inflammation in healthy subjects show conflicting results. few studies have investigated the effects ofpt among subjects with coronary heart disease (chd) risk factors. aim: to report the results of a pilot prospective study on the effects of periodontal treatment on markers of inflammation among subjects with chd risk factors. material and methods: seventy three patients aged 53±6 years (25% males) with chronic periodontitis, dyslipidemia and other chd risk factors were subjected to pt consisting on root planning and oral metronidazol and amoxicillin for 7 days. periodontal clinical parameters, serum c-reactive protein (crp), fibrinogen levels and erythrocyte sedimentation rate (esr) were assessed before and at 6 weeks a?erpt. polymorphisms at the illa-889 andil1b+3954genes were also genotyped. results: after the treatment period, crp levels significantly increased from 3.6±3.7 mg/ l to 5.4±5.7 mg/l (p =0.001). no significant changes were observed in fibrinogen levels and esr. higher post-treatment crp levels were significantly associated with the composite polymorphic genotype at the illa-889 and il1b+3954 genes (p =0.0001), and extensive periodontitis (p =0.005). moderate alcohol consumption appeared as a protective factor for crp elevation (p =0.029). conclusions: the increase of the crp levels after pt in patients with cvd risk factors appeared associated with il-1 gene polymorphisms and extensive periodontitis.
Efectos del tratamiento periodontal sobre los marcadores de inflamación sistémica en pacientes con riesgo de enfermedad cardiaca coronaria: Estudio piloto Effects of periodontal therapy on markers of systemic inflammation in patients with coronary heart disease risk
Néstor J López,Antonio Quintero,Marcelo Llancaqueo,Lilian Jara
Revista médica de Chile , 2009,
Abstract: Background- Studies investigating effects of periodontal treatment (PT) on markers of inflammation in healthy subjects show conflicting results. Few studies have investigated the effects ofPT among subjects with coronary heart disease (CHD) risk factors. Aim: To report the results of a pilot prospective study on the effects of periodontal treatment on markers of inflammation among subjects with CHD risk factors. Material and methods: Seventy three patients aged 53±6 years (25% males) with chronic periodontitis, dyslipidemia and other CHD risk factors were subjected to PT consisting on root planning and oral metronidazol and amoxicillin for 7 days. Periodontal clinical parameters, serum C-reactive protein (CRP), fibrinogen levels and erythrocyte sedimentation rate (ESR) were assessed before and at 6 weeks a erPT. Polymorphisms at the ILlA-889 andIL1B+3954genes were also genotyped. Results: After the treatment period, CRP levels significantly increased from 3.6±3.7 mg/ L to 5.4±5.7 mg/L (p =0.001). No significant changes were observed in fibrinogen levels and ESR. Higher post-treatment CRP levels were significantly associated with the composite polymorphic genotype at the ILlA-889 and IL1B+3954 genes (p =0.0001), and extensive periodontitis (p =0.005). Moderate alcohol consumption appeared as a protective factor for CRP elevation (p =0.029). Conclusions: The increase of the CRP levels after PT in patients with CVD risk factors appeared associated with IL-1 gene polymorphisms and extensive periodontitis.
Adolescentes en las aulas: la irrupción de la diferencia y el fin de la expansión educativa
López, Néstor;
Educa??o & Sociedade , 2012, DOI: 10.1590/S0101-73302012000300012
Abstract: the article begins by reviewing recent trends in the education of adolescents in latin america. specifically, the analysis is focused on to which extent the expansion of education since the early 1990's resulted in an important reduction of inequalities in the access to education and at the same time how the deceleration of the education process, that has been going on over the last five years, reinstalls the challenge of inequalities in the core of the educational agenda. the second part of the article suggests some hypothesis regarding the causes for this deceleration that may be seen in the universalization process of access to education. a special attention is paid to those hypothesis focusing on inequalities that result from the educational system's difficulties in operating in contexts of increasing cultural and identity diversity that clearly shows the persistence of multiple daily and common discriminatory practices at schools.
La educación en América Latina, entre el cambio social y la inercia institucional
Néstor López
Revista Galega de Economía , 2005,
Abstract: América latina viene de grandes cambios sociales, políticos, económicos y culturales, y una de las consecuencias de estas transformaciones es el asentamiento de situaciones de pobreza extrema y de exclusión. Frente a este nuevo contexto surge la pregunta sobre si no se estarán conformando escenarios sociales en los cuales no están garantizadas las condiciones mínimas para que las prácticas educativas tengan lugar. El trabajo aborda este interrogante, desarrollándolo en tono de ensayo a partir de la observación de situaciones de pobreza y de exclusión social en diversos países de la región. La conclusión es que, frente a la profundidad de los cambios ocurridos, la debilidad institucional de las escuelas y de los sistemas educativos de la región pone en riesgo la posibilidad de garantizar una educación de calidad para todos.
Los moradores de Gorgona: Protagonistas de unparadigma penitenciario en Colombia, 1959-1975
López Néstor
Anuario Colombiano de Historia Social y de la Cultura , 2006,
Abstract: El artículo expone las circunstancias sociales y políticas en que fue aprobada lacreación de un penal insular, la Isla Prisión de Gorgona, con claros fines políticos,entre ellos, segregar a los criminales supuestamente más peligrosos de la violenciabipart
A Ground-based Optical Transmission Spectrum of WASP-6b
Andrés Jordán,Néstor Espinoza,Markus Rabus,Susana Eyheramendy,David K. Sing,Jean-Michel Désert,Gáspár á. Bakos,Jonathan J. Fortney,Mercedes López-Morales,Pierre F. L. Maxted,Amaury H. M. J. Triaud,Andrew Szentgyorgyi
Physics , 2013, DOI: 10.1088/0004-637X/778/2/184
Abstract: We present a ground based optical transmission spectrum of the inflated sub-Jupiter mass planet WASP-6b. The spectrum was measured in twenty spectral channels from 480 nm to 860nm using a series of 91 spectra over a complete transit event. The observations were carried out using multi-object differential spectrophotometry with the IMACS spectrograph on the Baade telescope at Las Campanas Observatory. We model systematic effects on the observed light curves using principal component analysis on the comparison stars, and allow for the presence of short and long memory correlation structure in our Monte Carlo Markov Chain analysis of the transit light curves for WASP-6. The measured transmission spectrum presents a general trend of decreasing apparent planetary size with wavelength and lacks evidence for broad spectral features of Na and K predicted by clear atmosphere models. The spectrum is consistent with that expected for scattering that is more efficient in the blue, as could be caused by hazes or condensates in the atmosphere of WASP-6b. WASP-6b therefore appears to be yet another massive exoplanet with evidence for a mostly featureless transmission spectrum, underscoring the importance that hazes and condensates can have in determining the transmission spectra of exoplanets.
Process for the Obtention of Coumaric Acid from Coumarin: Analysis of the Reaction Conditions  [PDF]
Néstor N. López-Castillo, Alma D. Rojas-Rodríguez, Brenda M. Porta, M. Javier Cruz-Gómez
Advances in Chemical Engineering and Science (ACES) , 2013, DOI: 10.4236/aces.2013.33025
Abstract:

Coumaric acid can be obtained from basic hydrolysis of coumarin, through a reaction process consisting on opening the lactone ring and cis-trans isomerization. Parameters such as reaction time, temperature, NaOH concentration, solvent and reaction atmosphere, have been thoroughly studied and analyzed, in order to determine the appropriate conditions for the maximum conversion efficiency of coumarin into coumaric acid. Experimental results show that the best conditions are a 1 hour reaction time, at 160, with a 20% sodium hydroxide aqueous solution, and in an inert reaction atmosphere.

Chemical Treatment to Recover Molybdenum and Vanadium from Spent Heavy Gasoil Hydrodesulfurization Catalyst  [PDF]
Alma Delia Rojas-Rodríguez, Orlando Flores-Fajardo, Fabiola Selene Alcántar González, Néstor Noé López Castillo, Modesto Javier Cruz Gómez
Advances in Chemical Engineering and Science (ACES) , 2012, DOI: 10.4236/aces.2012.23050
Abstract: Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its vanadium concentration. Most of these catalysts are usually supported on alumina containing a variable percentage of elements such as nickel or molybdenum. Hence these catalysts contain environmentally critical, and economically valuable metals such as molyb denum, vanadium, and, nickel. In this paper, a spent HDS catalyst was treated with caustic soda solution. Parameters such as temperature, time, and NaOH solution concentration have been studied thoroughly, in order to settle the appropriate conditions for the maximum recovery of molybdenum and vanadium. Under the best leaching conditions (20 %w NaOH, room temperature, 2 h) about 95% recovery of Mo and V was achieved, and the recovery of nickel obtained was of 99% in the form of NiAlO4.
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