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Search Results: 1 - 10 of 5100 matches for " Natalia; Varela "
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El arte político de conciliar El Tema de las drogas en las relaciones entre Colombia y Estados Unidos. 1986-1994
Natalia Delgado Varela
Revista de Estudios Sociales , 2000,
Prevención del Dolor en Recién Nacidos de Término: Estudio Aleatorizado Sobre Tres Métodos Pain prevention in term neonates: randomised trial for three methods
Revista chilena de pediatría , 2010,
SnO2 Dense Ceramic Microwave Sintered with Low Resistivity  [PDF]
Leinig Antonio Perazolli, Gisane Gasparotto, Natalia Jaomaci, Miguel Ruiz, Maria Aparecida Zaghete Bertochi, Cesar Renato Foschini, Ederson Carlos Aguiar, José Arara Varela
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.35040
Abstract: The Hall-Héroult process is used for alumina reduction by the use of graphite anodes even though it involves a high emission of carbon dioxide (CO2) and several other organic compounds. Proposals have been made aiming at substituting graphite for a single-phase SnO2-based ceramic with low resistivity and chemical resistance to cryolite, which is characterized as an inconsumable anode, reducing pollutant emissions. To this end, a wide range of studies were carried out on SnO2-based ceramics modified with ZnO as a densification aid doped with the promoters of electrical conductivity such as Nb2O5, Al2O3 and Sb2O3 through a mixture of oxides and hybrid sintering in a microwave oven. The pressed pellets were sintered in a microwave oven up to 1050℃ under a constant heating rate of 10℃/min. After sintering, the density was determined by the Archimedes method, the phases were then characterized by X-ray diffraction, the microstructure and chemical composition resulting from the sintered SnO2-based ceramics were also investigated by field emission scanning electron microscopy (FE-SEM) coupled with an energy-dispersive X-ray spectroscopy (EDS) and the electrical properties were determined by the measurements of the electric field x current density. A single-phase ceramic was obtained with a relative density of above 90% and electrical resistivity of 6.1 Ω·cm at room temperature. The ceramics obtained in this study could be a potential candidate as an inconsumable anode to replace the current fused coke used in the reduction of alumina.
Arbitrage in General Equilibrium  [PDF]
Oscar Varela
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.34051
Abstract: Normal trade in goods assumes two sectors that co-exist for reasons such as comparative advantage and interact via trade. Arbitrage trade in goods assumes two markets that artificially exist and converge via trade. Restoration of the law of one price via arbitrage creates one sector out of two, and in general equilibrium, equalizes opportunity cost of resources used in production. Arbitrage does not occur in a vacuum, such that when the high (low) price of a good decreases (increases) in its artificially segmented market during arbitrage, the supply of the good falls (rises), the resources used intensively in that good earn lower (higher) returns, affecting security prices, and the supply of those resources in that good’s production fall (rise).
Prevención del dolor en recién nacidos de término: estudio aleatorizado sobre tres métodos
Bonetto,Germán; Salvatico,Estela; Varela,Natalia; Cometto,Cristina; Gómez,Patricia F; Calvo,Bernardo;
Archivos argentinos de pediatr?-a , 2008,
Abstract: introduction. every newborn infant is screened for hypothyroidism and phenilketonuria by blood sampling, during the first week of life, but there is not a simple and efficient method to reduce pain during the procedure. objectives. prospective randomised trial, to assess if the administration of oral glucose, paracetamol or emla, given individually, can reduce the pain caused in newborns by heel prick, in an outpatient setting. methods. double-blind study in which seventy six healthy newborns at term were randomly assigned to receive placebo, oral glucose, emla in the heel, or oral paracetamol. heel prick was performed to get a blood sample, and pain was measured by two independent observers, using two scales (nips and pipp). results. nips <4: placebo (9/19= 47%), glucose (16/19= 84%), paracetamol (8/19= 42%) and emla (12/19= 63%); pipp <8: placebo (9/19= 47%), oral glucose (12/19= 63%), paracetamol (5/19= 26%) and emla (8/19= 42%). with the use of oral glucose we found rar: 0.37 (ic 95% 0.09-0.64), rrr: 44% (ic 95% 6-67%), nnt: 2.7 (ic 95% 1.5-11). conclusions. the best results were obtained with the use of oral glucose, being statistically significant with only one of the scales. the administration of paracetamol or emla did not reduce pain. other complementary and/or combined methods, added to oral glucose, should be considered daily to diminish this painful experience in thousands of children.
Esperanza A. Varela,Gustavo A. Daneri,M. Natalia Paso Viola,M. Fernanda Negri
Mastozoolog?-a neotropical , 2010,
Abstract: Se realizó una revisión de los ejemplares de la Colección de Mamíferos Marinos del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". La misma indicó que del total de ejemplares catalogados (n=378), el 56.9% corresponde a Cetacea mientras que el 43.1% restante corresponde a Pinnipedia. Dentro de Cetacea la familia más representada es Delphinidae y el género con más ejemplares, Pontoporia (Pontoporidae); se reportan además, en forma complementaria, tres ejemplares tipo que no fueron listados en un trabajo previo. Dentro de los Pinnipedia, la familia mejor representada es Otariidae y el género con mayor número de ejemplares, Otaria.
Vitamin B12 and Folic Acid Imbalance Modifies NK Cytotoxicity, Lymphocytes B and Lymphoprolipheration in Aged Rats
Teresa Partearroyo,Natalia úbeda,Ana Montero,María Achón,Gregorio Varela-Moreiras
Nutrients , 2013, DOI: 10.3390/nu5124836
Abstract: Different vitamin B 12 and folic acid concentrations could exacerbate the immune response. The aim was to evaluate different dietary folic acid and vitamin B 12 levels on the immune response in aged rats. Male Sprague Dawley aged rats were assigned to three folic acid groups (deficient, control, supplemented) each in absence of vitamin B 12 for 30 days. Several parameters of innate and acquired immune responses were measured. Serum and hepatic folate levels increased according to folic acid dietary level, while vitamin B 12 levels decreased. There was a significant decrease in natural killer cell-mediated cytotoxicity in the spleen for the vitamin B 12 deficient diet and folic acid control diet groups. Significant changes in CD45 lymphocyte subsets were also observed according to dietary imbalance. Lymphoproliferative response to concanavalin A and phytohemagglutinin did not differ significantly between groups. The spleen response to lipopolysaccharide increased significantly, but was unmodified for the other organs. An imbalance between dietary vitamin B 12 and folic acid concentrations alters some immunological parameters in aged rats. Therefore, the ratio between folate and vitamin B 12 could be as important as their absolute dietary concentrations.
Effect of Stacking Fault Energy on the Mechanism of Texture Formation during Alternating Bending of FCC Metals and Alloys  [PDF]
Natalia Shkatulyak
International Journal of Nonferrous Metallurgy (IJNM) , 2013, DOI: 10.4236/ijnm.2013.22005

Alternating bending shear stresses lead to the formation of twin orientations in the texture of FCC materials with middle and low stacking fault energy (SFE). Only in the stainless steel with a low SFE during alternating bending with different number of cycles components of shear texture {111}; {hkl}<110>; {001}<110> were formed. Copper (middle SFE), along with orientations of twinning and cubic texture formed orientation of deformation {135}<211>. During alternating bending of aluminum (high SFE), a dynamic recovery occurred. The share of initial cubic texture increases with the increase of number of cycles of alternating bending and reaches its maximum after three cycles. Share of component of texture Goss increased slightly. The most significant change of the microstructure and texture occurred during the first 3 - 5 cycles

Pseudo Jahn-Teller Effect in Puckering and Planarization of Heterocyclic Compounds  [PDF]
Natalia Gorinchoy
International Journal of Organic Chemistry (IJOC) , 2018, DOI: 10.4236/ijoc.2018.81010
Abstract: The goal of this brief partly review paper is to summarize the results of the works published over the last few years regarding the origin of the out-of-plane distortions (puckering) of heterocyclic compounds. In all the papers devoted to this problem, it is shown that the instability of planar configurations of heterocyclic molecules leading to symmetry breaking and distortions is induced by the pseudo Jahn-Teller effect (PJTE). Special attention in this work is paid to the mechanism of suppression and enhancement of the PJTE distortions of heterocycles by oxidation, reduction, and chemical substitutions. It is demonstrated that oxidation of 1,4-dithiine containing compounds leads to suppression of the PJTE and to restoration of their planar nuclear configurations. An example of a dibenzo[1,2]dithiine molecule is used to demonstrate the mechanism of enhancement of the PJTE by reduction. It is shown that the reduction of the neutral C12H8S2 molecule up to the dianion (C12H8S2)2- enhances the PJTE, followed by the S-S bond cleavage and significant structural distortions of the system. The change of the PJTE by chemical substitutions, accompanied either by puckering or by planarization of heterocyclic compounds, is discussed using as examples 1,4-ditinine and its S-oxygenated derivatives.
System and Policy in the Planning of Higher Education in Mexico  [PDF]
Gonzalo Varela-Petito
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326148
Abstract: In higher education in Mexico, the tension between institutional practice and the directives of government authority produces a scenario of uncertainty. In recent decades the government has used planning mechanisms in an attempt to induce a more solid direction all round. Such a policy tries to assert itself in generic criteria such as the opening of opportunities by increasing student enrollment numbers and the radius of social recruitment. It does not relinquish the maxim of educational achievement and quality of service. Nevertheless, given the interinstitutional complexity of the system, it is hard to ensure that these would bring about significant corrections in the short term. The crux of the matter lies in the resolution of the ties between the government and the Higher Education Institutions (HEIs), indeed, between centralization and autonomy. One escape route from this tension has been the parallel growth of the private higher education sub-system, but in relation to the public sector the approach of official policy has been to advance evaluations as a means of information and control.
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