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Search Results: 1 - 10 of 118110 matches for " Maria del Mar Maldonado "
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Electrochemical Capacitance DNA Sensing at Hairpin-Modified Au Electrodes
Joel Rivera-Gandía,Maria del Mar Maldonado,Yarimar De La Torre-Meléndez,Edwin O. Ortiz-Quiles,Nella M. Vargas-Barbosa,Carlos R. Cabrera
Journal of Sensors , 2011, DOI: 10.1155/2011/735279
Abstract: An interfacial capacitance measurement electrochemical technique has been used for the sensing of self-assembled DNA hairpin probes (M. tuberculosis and B. anthracis) attached to Au electrodes. The double-layer capacitance ( ) was determined with electrochemical perturbations from 0.2?V to 0.5?V versus Ag/AgCl at a Au/M. tuberculosis DNA hairpin probe at surface coverage Au electrodes. The capacitance study was done at pH 7, which was necessary to maintain the M. tuberculosis and B. anthracis DNA probes closed during the electrochemical perturbation. Detailed experimental analysis carried out by repetitively switching the electrochemical potential between 0.2 and 0.5?V (versus Ag/AgCl) strongly supports the use of capacitance measurements as a tool to detect the hybridization of DNA targets. A large change in the capacitance deference between 0.2 and 0.5?V was observed in the DNA hybridization process. Therefore, no fluorophores or secondary transducers were necessary to sense a DNA target for both DNA hairpins. 1. Introduction The behavior of DNA attached onto metallic and nonmetallic surfaces via self-assembly with various chemistries (e.g., Au-S) may have applications in biomedical devices. For example, single-stranded DNA (ssDNA) self-assembled on a metallic interface such as gold [1, 2] or on nonmetals such as carbon nanotubes [3] and diamond [4–6] has potential use in DNA microarrays [7]. In addition, detection of DNA hybridization has been possible with techniques using different types of reporting, including fluorescence [8–11], chronocoulometry [12–14], surface plasmon resonance (SPR) [15, 16], colloidal labeling [17–19], and polarization modulation infrared reflection absorption spectroscopy [20]. Electroactive molecules can also be used to monitor the electron transfer mechanism during the hybridization process [21]. Here, we present a nonfaradaic electrochemical method based on capacitive measurement to sense DNA hairpin modification and hybridization. A nucleic acid probe has been developed to recognize specific DNA targets in solution [22]. These probes, called molecular beacons, are DNA hairpins with a fluorophore-quencher pair, which is completely unable to fluoresce when the two components are in close proximity (i.e., closed molecular beacon). When the molecular beacon spontaneously changes its conformation (like during hybridization), the fluorophore attached to one end of the molecule is no longer quenched as the quencher moves away. The capacity of this DNA hairpin has shown to discriminate between alleles with high specificity when
Assessment of Lipid Quality and Composition of Commercial Infant Milk Formulas in Mexico: Emphasis on Trans Fatty Acid Isomers  [PDF]
Ayala-Moreno María del Rosario, Fernández-Callejas José María Salvador, Maldonado-Hernández Jorge
Food and Nutrition Sciences (FNS) , 2016, DOI: 10.4236/fns.2016.74029
Abstract: Objective: To assess the lipid quality focusing on trans fatty acids (TFA) content of standardized milk formulas marketed in Mexico for infants aged from 0 to 36 months. Material and Methods: A total of 27 infant formulas from eight different leading brands were analyzed. Nine of them belonged to stage 1 (age < 6 months), nine to stage 2 (age 6 to 12 months) and eight to stage 3 (age > 12 months). Acquired products were treated by duplicate for extraction of total lipid content with the modified Folch method before their expiration date. Fatty acids were esterified in an alkaline medium followed by an acid-catalyzed esterification. Analysis was performed on a gas chromatograph (5890 Series II; Hewlett-Packard, USA) with a flame ionization detector. Results: Thirty-four fatty acids (C8 to C22) were identified. Most products complied with ESPHAGAN compositional requirements. Only one product exceeded the suggested limit (>3%) for TFA. Long chain polyunsaturated fatty acids (LC-PUFAs) content was consistently meager (≈78%), with low amounts of arachidonic (<0.35%) and docosahexaenoic acids (<0.2%).Conclusion: Most milk formulas complied with ESPHAGAN global recommendations. The content of TFA and LC-PUFAs was scarce in the majority of samples.
Museus i educació: noves perspectives
Maria del Mar Oliver Barceló
Observar , 2009,
Abstract: El llibre ressenyat sorgí de les presentacions realitzades en les 3es Jornades d’Investigació en Educació i Museus celebrades en el MuVIM de València el desembre de 2008. Diversos grups de recerca universitaris exposaren les seves propostes sobre diferents aspectes de la didàctica en el museu, entre els quals destaca la cooperació entre aquesta institució, la universitària i l’escolar. El present text pretén proporcionar una visió crítica i global del projecte i destacar-ne les aportacions més notables. The reviewed book is the result of the 3rd Conference on Research in Education and Museums held in the MuVIM of Valencia in December 2008. Some university research groups exposed their ideas about diferent aspects of the teaching at museum, among which they stress the cooperation between this institution, universities and schools. The present text intends to provide a critical and global vision of the project, and emphasize its most outstanding contributions.
Asymptotics for a free-boundary model in price formation
Maria del Mar Gonzalez,Maria Pia Gualdani
Mathematics , 2008,
Abstract: We study the asymptotics for large time of solutions to a one dimensional parabolic evolution equation with non-standard measure-valued right hand side, that involves derivatives of the solution computed at a free boundary point. The problem is a particular case of a mean-field free boundary model proposed by Lasry-Lions on price formation and dynamic equilibria. The main step in the proof is based on the fact that the free boundary disappears in the linearized problem, thus can be treated as a perturbation through semigroup theory. This requires a delicate choice for the function spaces since higher regularity is needed near the free boundary. We show global existence for solutions with initial data in a small neighborhood of any equilibrium point, and exponential decay towards a stationary state. Moreover, the family of equilibria of the equation is stable, as follows from center manifold theory.
Gestión del conocimiento y crecimiento en la Pyme manufacturera de Aguascalientes (México)
Maldonado Guzmán,Gonzalo; Martínez Serna,María del Carmen; García Ramírez,Ricardo;
Cuadernos de Administración (Universidad del Valle) , 2012,
Abstract: within a constantly changing market and an uncertain environment for business, knowledge has become one of the valued intangible resources appreciated by firms. for this, more and more firms are applying managerial strategies to promote the development of knowledge, both tacit and implicit, in such a way that allows them to achieve expected success. also, an important number of companies, mainly small and medium-sized enterprises, are getting involved with knowledge management as part of their daily activities, seeking to improve higher growth. thus, the value of knowledge is increasing, to such a measure that firms are hiring the most brilliant minds in each specialty. in this sense, this paper aims to analyze the relationship between knowledge management and growth, starting from a sample of 125 smes from the state of aguascalientes (mexico). the results obtained show that knowledge management has positive and significant effects on the growth of smes, which can constitute a competitive advantage.
Development of a Brief Scale for Social Support: Reliability and validity in Puerto Rico
Guillermo Bernal,Mildred M. Maldonado Molina,María R. Scharrón del Río
International Journal of Clinical and Health Psychology , 2003,
Abstract: El apoyo social es una interacción humana en la que recursos sociales, emocionales, instrumentales y recreacionales son intercambiados. Este fenómeno social está asociado al estrés, la depresión y a los problemas de salud mental. Este estudio instrumental presenta el desarrollo y evaluación de un Cuestionario de Apoyo Social (CAS) como parte de un estudio más amplio que pretende desarrollar instrumentos psicosociales válidos y confiables en el contexto puertorrique o. El CAS fue dise ado para evaluar la necesidad de apoyo emocional, interpersonal y material. También la satisfacción con el apoyo recibido fue evaluado. Cuatrocientos sesenta y cuatro estudiantes puertorrique os de la Universidad de Puerto Rico participaron en este estudio. Los resultados demostraron una consistencia interna de 0,68 para los siete reactivos de necesidad y de 0,89 para los dos reactivos de satisfacción con el apoyo recibido. Las dimensiones principales de la escala fueron analizadas utilizando un análisis confirmatorio de factores (CFA, por sus siglas en inglés). Varios modelos fueron dise ados basados en el CFA y comparados. Los datos apoyaron un modelo de tres factores con siete reactivos a escala de necesidad de apoyo social. El aspecto multidimensional del constructo de apoyo social (necesidad emocional, interpersonal, instrumental) fue apoyado por los datos. El uso de esta escala breve para evaluar apoyo social es discutido.
El impacto del compromiso organizacional en la orientación al mercado
Adriana Eugenia Ramos ávila,María del Carmen Martínez Serna,Gonzalo Maldonado Guzmán
Investigación y Ciencia de la Universidad Autónoma de Aguascalientes , 2009,
Abstract: Tener un conocimiento claro sobre el compromiso organizacional y la orientación al mercado, proporciona a las organizaciones un buen entendimiento de las necesidades de los trabajadores, clientes, competencia y ambiente del mercado, lo que conlleva como consecuencia un mejor desempe o de la organización. En este sentido, este estudio investiga la influencia potencial del compromiso organizacional en la orientación al mercado en el sistema público de educación superior. Los datos requeridos para este estudio fueron recolectados a través de entrevistas personales utilizando una muestra de 300 profesores de una universidad pública del centro de México. Los resultados obtenidos muestran que el compromiso organizacional tiene un impacto positivo en la orientación al mercado cultural, y ésta a su vez tiene un impacto positivo en la orientación al mercado conductual.
La influencia de la gestión del conocimiento en el nivel de competitividad de la Pyme manufacturera de Aguascalientes
Gonzalo Maldonado Guzmán,María del Carmen Martínez Serna,Ricardo García Ramírez
Investigación y Ciencia de la Universidad Autónoma de Aguascalientes , 2012,
Abstract: En un ambiente de negocios incierto y en una nueva era de la economía que caracteriza al siglo XXI, la adquisición de mayores ventajas competitivas y el incremento en el nivel de competitividad se ha convertido en una de las principales prioridades de las empresas, principalmente de las peque as y medianas. Para lograr estas metas las organizaciones tienen que mejorar la gestión del conocimiento, ya que el nivel de competitividad depende de la capacidad de desarrollar y gestionar el conocimiento. Por ello, a partir de una muestra de 125 empresas manufactureras del Estado de Aguascalientes, este estudio analiza la relación entre la gestión del conocimiento y el nivel de competitividad. Los resultados obtenidos muestran que existe una fuerte influencia de la gestión del conocimiento en el nivel de competitividad de las peque as y medianas empresas.
La maximización del capital humano en la industria del mueble de Espa a
Gonzalo Maldonado Guzmán,María del Carmen Martínez Serna
Investigación y Ciencia de la Universidad Autónoma de Aguascalientes , 2010,
Abstract: Actualmente, el capital humano aparece en la literatura como uno de los activos más importantes de las organizaciones, especialmente de los gestores encargados del área de la logística, quienes han recibido una atención especial en los estudios realizados. Así, este trabajo de investigación tiene como objetivo principal analizar los efectos que ejerce la maximización del capital humano encargado del área de la logística en el desempe o de las empresas que integran la industria del mueble de Espa a. El análisis empírico se llevó a cabo para una muestra de 322 empresas productoras de muebles con veinte o más trabajadores. Los resultados obtenidos indican que tanto la experiencia como las habilidades y la formación tienen un impacto positivo en el desempe o, mismo que resulta beneficiado en la capacidad directiva de los gestores de la industria del mueble.
Owls May Use Faeces and Prey Feathers to Signal Current Reproduction
Vincenzo Penteriani, Maria del Mar Delgado
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003014
Abstract: Background Many animals communicate by marking focal elements of their home range with different kinds of materials. Visual signaling has been demonstrated to play a previously unrecognized role in the intraspecific communication of eagle owls (Bubo bubo), in both territorial and parent-offspring contexts. Visual signals may play a role in a variety of circumstances in this crepuscular and nocturnal species. Methodology/Principal Findings Here, we report that a large amount of extremely visible white faeces and prey feathers appear during the breeding season on posts and plucking sites in proximity to the nest, potentially representing a way for eagle owls to mark their territory. We present descriptive and experimental evidence showing that faeces and prey remains could act as previously unrecognized visual signals in a nocturnal avian predator. This novel signaling behavior could indicate the owls' current reproductive status to potential intruders, such as other territorial owls or non-breeding floaters. Faeces and prey feather markings may also advertise an owl's reproductive status or function in mate-mate communication. Conclusions/Significance We speculate that faeces marks and plucking may represent an overlooked but widespread method for communicating current reproduction to conspecifics. Such marking behavior may be common in birds, and we may now be exploring other questions and mechanisms in territoriality.
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