31 results on '"Vladimir, Rodriguez"'
Search Results
2. Nivel de ingresos y uso de tarjetas de crédito en Perú
- Author
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Vladimir Rodriguez Cairo, Raphael Ángel Saldaña Pacheco, and Johanna Marissa Yancari Cueva
- Subjects
acceso ,endeudamiento ,ingresos ,segmentos ,tarjeta de crédito ,Accounting. Bookkeeping ,HF5601-5689 ,Finance ,HG1-9999 - Abstract
Objetivo: Determinar si el nivel de ingreso explica el uso de tarjetas de crédito en el Perú. Método: Se utilizó un modelo Logit para estimar la probabilidad de uso de tarjetas de crédito en aquellos individuos que cuentan con una tarjeta. Resultados: Los ingresos tienen un efecto positivo y estadísticamente significativo en el uso de tarjetas de crédito; sin embargo, en algunos rubros, como en el gasto de alimentos, no se observan diferencias significativas en el uso de la tarjeta de crédito con relación a los ingresos laborales mensuales. Conclusión: La población con menores ingresos tiende a usar la tarjeta de crédito en igual proporción que los segmentos con mayores ingresos para determinados gastos. more...
- Published
- 2020
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- View/download PDF
Catalog
3. Políticas públicas y planificación estratégica en Perú
- Author
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Raphael Ángel Saldaña Pacheco, Noé Rodríguez Ascue, and Vladimir Rodriguez Cairo
- Subjects
política ,público ,intervención ,planificación ,estrategia ,Accounting. Bookkeeping ,HF5601-5689 ,Finance ,HG1-9999 - Abstract
El estudio permitió examinar la trascendencia de las políticas públicas y la planificación estratégica como herramientas esenciales para resolver problemas de la sociedad, así como para orientar la visión de país a la que se aspira. El alcance del estudio fue descriptivo y la técnica de investigación, la documentación. Se propone que, para el fortalecimiento del marco institucional del planeamiento estratégico en Perú, es necesario la constitucionalización del Sistema Nacional de Planeamiento Estratégico, a fin de fortalecer la autonomía del Centro Nacional de Planeamiento Estratégico como órgano rector totalmente técnico, independiente de las oscilaciones políticas. more...
- Published
- 2020
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4. Régimen constitucional de la moneda y estabilidad del nivel general de precios en Perú/Constitutional regime of the currency and stability of the general price level in Peru
- Author
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Cairo, Vladimir Rodriguez
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- 2020
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5. Economía conductual, paternalismo libertario y libertad de elegir
- Author
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Vladimir Rodriguez Cairo
- Subjects
economía conductual ,paternalismo ,libertad ,decisiones ,Accounting. Bookkeeping ,HF5601-5689 ,Finance ,HG1-9999 - Abstract
El artículo explica los fundamentos de la Economía Conductual también conocida como Psicología Económica o simplemente Psicología y Economía, la misma que a través de diseños experimentales y observacionales busca detectar errores que se cometen en la toma decisiones. En ese sentido, la Economía Conductual utiliza los conceptos y evidencia de la Psicología para mejorar el entendimiento del proceso de toma de decisiones económicas, analizando los motivos por los cuales las personas generalmente toman decisiones inadecuadas. Desde tal perspectiva, el Paternalismo Libertario, propuesto por Richard Thaler y Cass Sunstein, tiene como propósito diseñar políticas públicas para mantener o incrementar la libertad de elegir de las personas a efectos de mejorar las condiciones o contextos para la toma de decisiones adecuadas. more...
- Published
- 2018
- Full Text
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6. Libre comercio e integración comercial en la Alianza del Pacífico y la Comunidad Andina
- Author
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Raphael Ángel Saldaña Pacheco and Vladimir Rodriguez Cairo
- Subjects
comercio ,internacional ,integración ,alianza ,comunidad andina ,Accounting. Bookkeeping ,HF5601-5689 ,Finance ,HG1-9999 - Abstract
Objetivo: La investigación estableció el efecto del índice de libertad de comercio internacional sobre el nivel de integración comercial en la Alianza del Pacífico (AP) y la Comunidad Andina (CAN) durante el periodo 1970-2015. Método: El enfoque del estudio es cuantitativo porque se utilizaron procedimientos estadísticos, en estricto el coeficiente de correlación y el análisis de regresión. Resultados: De esta forma, uno de los principales resultados es que existe una relación positiva y estadísticamente significativa entre el índice de libertad de comercio internacional y el grado de integración comercial en la AP y la CAN, y esta es diferenciada entre los países miembros, tanto al interior de cada grupo como entre ellos. Sin embargo, a nivel agregado el efecto del índice de libertad de comercio internacional sobre el grado de integración comercial es mayor en la AP que en la CAN. Conclusiones: Se concluyó que la libertad de comercio internacional influyó en el nivel de integración comercial en la AP y la CAN. Sin embargo, este efecto no es suficiente para determinar el grado de integración comercial en la AP y la CAN. more...
- Published
- 2018
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7. CRÉDITOS DEL SISTEMA FINANCIERO AL SECTOR PRIVADO Y REGULACIÓN DEL MERCADO DE CRÉDITOS EN PERÚ
- Author
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Vladimir Rodriguez Cairo
- Subjects
stock ,créditos ,sistema financiero ,sector privado ,regulación ,mercado ,libertad de mercado ,Accounting. Bookkeeping ,HF5601-5689 ,Finance ,HG1-9999 - Abstract
El objetivo de la investigación es explicar por qué la libertad en el mercado de créditos incide positivamente en los créditos del sistema financiero al sector privado en el Perú, generando un aumento del stock de créditos al sector privado. A partir de dicho objetivo, se realizó un análisis descriptivo e inferencial sobre la relación entre las variables. Siendo así, se obtuvieron como principales resultados que la libertad en el mercado de créditos como componente de la regulación del mercado de créditos, influyó en el stock de créditos del sistema financiero al sector privado del país. De este modo, se concluyó que la libertad en el mercado de créditos favorece el stock de créditos y consiguientemente, contribuye a profundizar el sistema financiero. No obstante, la mayor libertad en el mercado de créditos es un aspecto esencial para aumentar los créditos al sector privado pero no es el único elemento. more...
- Published
- 2017
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8. Cirugía de revascularización miocárdica en la disfunción sistólica ventricular izquierda, una opción viable para nuestros pacientes.
- Author
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Vladimir Rodriguez Rodriguez
- Subjects
Internal medicine ,RC31-1245 ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
La cirugía de revascularización miocárdica (CRM) se ha convertido en el tratamiento de elección de los pacientes con CI extensa y función ventricular deprimida. En este contexto, los procedimientos de revascularización miocárdica ofrecen una doble expectativa: por un lado son capaces de preservar el miocardio funcional, y por otro permiten la recuperación total o parcial del músculo cardíaco viable. En estudios prospectivos y aleatorizados publicados en los años ochenta quedó demostrado que los pacientes con disfunción ventricular izquierda sometidos a CRM tienen mayor supervivencia y mejoría funcional que los que son tratados de manera conservadora y, además, que el beneficio de la CRM es tanto mayor cuanto peor es la función ventricular. Recientemente tuvimos acceso a una investigación publicada en la revista cubana de cardiología y cirugía cardiovascular titulada Disfunción sistólica ventricular izquierda y supervivencia posterior a cirugía de revascularización coronaria.Esta es la segunda publicación de los mismos autores en relación a este tema. En esta oportunidad, tan solo me gustaría comentar un poco respecto a los resultados y conclusiones de la citada publicación. more...
- Published
- 2017
9. Study of dielectric parameters and the internal electric field prediction in an individual wheat grain particle.
- Author
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Amauri Vidal Castrejon, Mario Vladimir Rodriguez Gonzalez, and Iryna Ponomaryova
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- 2015
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10. A hardware architecture for filtering irreducible testors.
- Author
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Vladimir Rodriguez, José F. Martínez, Jesús Ariel Carrasco-Ochoa, Manuel Sabino Lazo-Cortés, René Cumplido, and Claudia Feregrino Uribe
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- 2014
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11. Cross-Laminated Timber: Status and Research Needs in Europe
- Author
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Omar Espinoza, Vladimir Rodriguez Trujillo, Maria Fernanda Laguarda Mallo, and Urs Buehlmann
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Cross-laminated timber (CLT) ,Engineered wood products ,Research needs ,Biotechnology ,TP248.13-248.65 - Abstract
In the 20 years since its invention in Europe, cross-laminated timber (CLT) has become a widely used construction material in parts of the old continent and has started to attract global attention. CLT possesses numerous advantages as a construction material, including its superior structural and environmental performance, as well as the speed and efficiency with which CLT buildings can be erected. In this study, European engineers were surveyed to learn about their current level of awareness of CLT, the major barriers to CLT adoption, and about the most pressing research needs to advance the use of CLT as a construction material. The study used a web-based survey with a convenience sample of 93 different kinds of timber and civil engineers and/or researchers, most of which belong to a European CLT research network. Results showed that participants think that, in general, the level of awareness about CLT among developers, construction managers, engineers, architects, and construction managers, is low. The majority of perceived barriers for CLT adoption involved its building code compatibility and the availability of technical information. The most pressing research needs for CLT development, according to respondents, are in the areas of structural performance and connections, moisture performance, and market research. more...
- Published
- 2015
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12. Theoretical Description of R–X⋯NH3 Halogen Bond Complexes: Effect of the R Group on the Complex Stability and Sigma-Hole Electron Depletion
- Author
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Juan Zurita, Vladimir Rodriguez, Cesar Zambrano, Jose Ramón Mora, Luis Rincón, and F. Javier Torres
- Subjects
sigma-hole ,halogen bond ,fermi-hole ,conditional pair density ,kullback–leibler divergence ,Organic chemistry ,QD241-441 - Abstract
In the present work, a number of R−X⋯NH3 (X = Cl, Br, and I) halogen bonded systems were theoretical studied by means of DFT calculations performed at the ωB97XD/6-31+G(d,p) level of theory in order to get insights on the effect of the electron-donating or electron-withdrawing character of the different R substituent groups (R = halogen, methyl, partially fluorinated methyl, perfluoro-methyl, ethyl, vinyl, and acetyl) on the stability of the halogen bond. The results indicate that the relative stability of the halogen bond follows the Cl < Br < I trend considering the same R substituent whereas the more electron-withdrawing character of the R substituent the more stable the halogen bond. Refinement of the latter results, performed at the MP2/6-31+G(d,p) level showed that the DFT and the MP2 binding energies correlate remarkably well, suggesting that the Grimme’s type dispersion-corrected functional produces reasonable structural and energetic features of halogen bond systems. DFT results were also observed to agree with more refined calculations performed at the CCSD(T) level. In a further stage, a more thorough analysis of the R−Br⋯NH3 complexes was performed by means of a novel electron localization/delocalization tool, defined in terms of an Information Theory, IT, based quantity obtained from the conditional pair density. For the latter, our in-house developed C++/CUDA program, called KLD (acronym of Kullback−Leibler divergence), was employed. KLD results mapped onto the one-electron density plotted at a 0.04 a.u. isovalue, showed that (i) as expected, the localized electron depletion of the Br sigma-hole is largely affected by the electron-withdrawing character of the R substituent group and (ii) the R−X bond is significantly polarized due to the presence of the NH3 molecule in the complexes. The afore-mentioned constitutes a clear indication of the dominant character of electrostatics on the stabilization of halogen bonds in agreement with a number of studies reported in the main literature. Finally, the cooperative effects on the [Br—CN]n system (n = 1−8) was evaluated at the MP2/6-31+G(d,p) level, where it was observed that an increase of about ~14.2% on the complex stability is obtained when going from n = 2 to n = 8. The latter results were corroborated by the analysis of the changes on the Fermi-hole localization pattern on the halogen bond zones, which suggests an also important contribution of the electron correlation in the stabilization of these systems. more...
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- 2020
- Full Text
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13. Instrumento virtual con acceso local y remoto para practicas de Ingenieria del Control/Local and remote access virtual instrument for control engineering laboratory practice
- Author
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Anias, Orlando Regalon, Diez, Vladimir Rodriguez, Rodriguez, Milagros Diez, Prieto, Raul Baez, Rodriguez, Leisis Lopez, and Ballagas, Francisco Pacheco
- Published
- 2015
14. The Factor Structure of Exchange Rates Volatility: Global and Intermittent Factors
- Author
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Massimiliano Caporin, Carlos Vladimir Rodriguez-Caballero, and Esther Ruiz
- Published
- 2022
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15. Energy Security: Multidimensional Analysis for South American Countries
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Dheybi Cervan, Christian Vladimir Rodriguez Díaz, and Carlos Inga
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Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology - Published
- 2022
- Full Text
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16. Na⋯B bond in NaBH: An induced spin‐polarized bond
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F. Javier Torres, José R. Mora, Vladimir Rodriguez, and Luis Rincón
- Subjects
Delocalized electron ,Crystallography ,Materials science ,Spin polarization ,Electric field ,Electronic structure ,Physical and Theoretical Chemistry ,Valence electron ,Induced polarization ,Atomic and Molecular Physics, and Optics ,Electron localization function ,Ion - Abstract
The nature of the Na⋯B bond, in the recently synthesized NaBH 3- adduct, is analyzed on the light of the Na- propensity to polarize along the bond axis as a consequence of the electric field produced by the BH3 fragment. The observed induced polarization has two consequences: (i) the energetic stabilization of the Na- , and (ii) the split of its valence electrons into two opposite lobes along the bond axis. Additionally, an analysis of the electron localization is presented using the information content of the correlated conditional pair density that reveals a significant delocalization between one lobe of the polarized Na- anion and the BH3 fragment at the equilibrium distance. Our findings reported here complement previous works on this system. more...
- Published
- 2021
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17. Na⋯B bond in NaBH
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Luis, Rincón, Jose R, Mora, Vladimir, Rodriguez, and F Javier, Torres
- Abstract
The nature of the Na⋯B bond, in the recently synthesized NaBH
- Published
- 2021
18. Constitución y sociedad: una reflexión acerca de la crisis democrática y del constitucionalismo con especial referencia al caso colombiano
- Author
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Vladimir Rodriguez Sanabria
- Subjects
Geography, Planning and Development ,Development - Abstract
Desde sus albores, la democracia ha estado en una constante crisis y ello ha afectado tanto la manera de entender a las constituciones que se han instaurado en la reciente historia de occidente como al desarrollo del constitucionalismo. Esto ha significado que también entren en crisis los proyectos de Estado surgidos en el devenir histórico. En la actualidad, el desafío democrático radica en superar las dificultades de la dinámica política y, fundamentalmente, del populismo que ha hecho carrera en el continente latinoamericano y, más aún, en la realidad colombiana. Finalmente, se indica como manera de estudio, para el caso colombiano, el abordaje desde el contexto del lenguaje por cuanto permite descubrir las honduras y falencias del proyecto nacional y, con ello, alumbrar la explicación de la crisis democrática de nuestro país. more...
- Published
- 2020
- Full Text
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19. Theoretical Description of R-X⋯NH
- Author
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Juan, Zurita, Vladimir, Rodriguez, Cesar, Zambrano, Jose Ramón, Mora, Luis, Rincón, and F Javier, Torres
- Subjects
Models, Molecular ,conditional pair density ,Halogens ,fermi-hole ,Ammonium Compounds ,Static Electricity ,Electrons ,halogen bond ,Models, Theoretical ,Kullback–Leibler divergence ,sigma-hole ,Algorithms ,Article - Abstract
In the present work, a number of R–X⋯NH3 (X = Cl, Br, and I) halogen bonded systems were theoretical studied by means of DFT calculations performed at the ωB97XD/6-31+G(d,p) level of theory in order to get insights on the effect of the electron-donating or electron-withdrawing character of the different R substituent groups (R = halogen, methyl, partially fluorinated methyl, perfluoro-methyl, ethyl, vinyl, and acetyl) on the stability of the halogen bond. The results indicate that the relative stability of the halogen bond follows the Cl < Br < I trend considering the same R substituent whereas the more electron-withdrawing character of the R substituent the more stable the halogen bond. Refinement of the latter results, performed at the MP2/6-31+G(d,p) level showed that the DFT and the MP2 binding energies correlate remarkably well, suggesting that the Grimme’s type dispersion-corrected functional produces reasonable structural and energetic features of halogen bond systems. DFT results were also observed to agree with more refined calculations performed at the CCSD(T) level. In a further stage, a more thorough analysis of the R–Br⋯NH3 complexes was performed by means of a novel electron localization/delocalization tool, defined in terms of an Information Theory, IT, based quantity obtained from the conditional pair density. For the latter, our in-house developed C++/CUDA program, called KLD (acronym of Kullback–Leibler divergence), was employed. KLD results mapped onto the one-electron density plotted at a 0.04 a.u. isovalue, showed that (i) as expected, the localized electron depletion of the Br sigma-hole is largely affected by the electron-withdrawing character of the R substituent group and (ii) the R–X bond is significantly polarized due to the presence of the NH3 molecule in the complexes. The afore-mentioned constitutes a clear indication of the dominant character of electrostatics on the stabilization of halogen bonds in agreement with a number of studies reported in the main literature. Finally, the cooperative effects on the [Br—CN]n system (n = 1–8) was evaluated at the MP2/6-31+G(d,p) level, where it was observed that an increase of about ~14.2% on the complex stability is obtained when going from n = 2 to n = 8. The latter results were corroborated by the analysis of the changes on the Fermi-hole localization pattern on the halogen bond zones, which suggests an also important contribution of the electron correlation in the stabilization of these systems. more...
- Published
- 2019
20. A valence bond perspective of the reaction force formalism
- Author
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José R. Mora, Luis Rincón, Vladimir Rodriguez, F. Javier Torres, and Cesar H. Zambrano
- Subjects
Physics ,Crystallography ,Formalism (philosophy of mathematics) ,010304 chemical physics ,Reaction ,Reaction step ,0103 physical sciences ,Valence bond theory ,Reaction path ,Physical and Theoretical Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences - Abstract
The reaction force formalism represents a convenient approach to analyze the course of a reaction step. From this analysis, the reaction path can be separated in a number of regions that are associated to either structural changes or electronic reorganization. This empirical observation is rationalized in this work on the basis of a simple two-state valence bond correlation diagram. We demonstrate that the ratio between the integrated reaction force and the region of interest ($$w_{\text{ii}}/w_{\text{i}}$$ for the forward reaction and $$w_{\text{iii}}/w_{\text{iv}}$$ for the backward reaction) increases with the ratio between the quantum mechanical resonance energy and the energy required to reach the crossing point at the transition state, we call to this ratio the strength of the resonance. This observation means that the size of the transition region (region ii and iii), that includes the transition state, depends on the strength of the resonance, and the structural zones (region i and iv), that are regions associated with the pure valence bond state curves (no resonance). We propose a simple analytical relationship for $$w_{\text{ii}}/w_{\text{i}}$$ and $$w_{\text{iii}}/w_{\text{iv}}$$ based on three parameters: (i) the quantum mechanical resonance energy, (ii) the energy of the reaction and (iii) the overlap between the VB structures at the transition state. The previous conclusions were supported by a reaction force analysis of a $${\text{S}}_{N}2$$ reactions, $${\text{X}}^{-} + {\text{CH}}_{3}{-}{\text{Y}} \rightarrow {{\text{X}}{-}{\text{CH}}}_{3} + {\text{Y}}^{-} ({\text{X}} = {\text{F}}, {\text{Cl}}, {\text{Br}})$$. The valence bond parameters for these reactions are estimated from empirical considerations. A very good agreement is found between the computed reaction force ratios and the predicted one. more...
- Published
- 2019
- Full Text
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21. FRI0067 ANXIETY AND DEPRESSION IN A PREGNANCY AND RHEUMATIC DISEASES CLINIC
- Author
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Janett Riega-Torres, Dionicio Ángel Galarza-Delgado, Jairo Vladimir Rodriguez Hinojosa, Lorena Pérez Barbosa, María Eugenia Corral Trujillo, and Cassandra Michele Skinner Taylor
- Subjects
medicine.medical_specialty ,Pregnancy ,business.industry ,medicine.disease ,Hospital Anxiety and Depression Scale ,Rheumatology ,Quality of life ,Rheumatoid arthritis ,Fibromyalgia ,Internal medicine ,medicine ,Anxiety ,medicine.symptom ,business ,Depression (differential diagnoses) - Abstract
Background: Preconceptional psychologic evaluation allows the identification of risks factors for perinatal disorders. Anxiety (13.4%) and depression (41.5%) has been reported in rheumatic diseases1. Hospital Anxiety and Depression Scale (HADS) is used to evaluate anxiety and depression in patients with chronic diseases2. Objectives: To describe the frequency of anxiety and depression disorders among preconceptional patients in a Pregnancy and Rheumatic Diseases Clinic. Methods: An observational, cross-sectional, and descriptive study was conducted in the Rheumatology Consultation of Hospital Universitario “Dr. Jose Eleuterio Gonzalez” in Monterrey, Mexico. We included 100 women aged between 18 and 39 years in the preconceptional stage of the Pregnancy and Rheumatic Diseases Clinic. HADS, which is divided in two subscales, one for anxiety and one for depression, indicating a disorder when a score ≥11 was applied. To evaluate Rheumatoid Arthritis (RA) a Disease Activity Score (DAS28) was used, for Systemic Lupus Erythematous (SLE) a Systemic Lupus Erythematous Disease Activity index (SLEDAI) was performed, and others (Sjogren’s syndrome, dermatomyositis and fibromyalgia) were evaluated with the Global Quality of Life (GQL). To analyze differences among groups, Gamma coefficient was used. It was considered a statistically significant p Results: One hundred women in childbearing age were included, with a mean age of 34.48 (SD 18.33) years. RA was diagnosed in 48%, SLE in 37%, and others in 15%. We found a mean HADS total score of 11.73 (7.29), in the anxiety subscale 6.94 (4.027), and depression subscale 4.79 (4.026). A significant correlation between SLE and a high HADS score was observed (Table 1). Conclusion: In order to have a safe pregnancy, an early intervention to assess the psychiatric status is required in patients with rheumatic diseases. References: [1] Quintana, J.M., Padierna, A., Esteban, C., Arostegui, I., Bilbao, A., & Ruiz, !. (2003). Evaluation of the psuchometric characteristics of the Spanish version of the Hospital Anxiety and Depression Scale. Acta Scandinavica, 107(3), 216-221. [2] Zigmond, A. S., & Snaith, R. P. (1983). The hospital Anxiety and depresion scale. Acta psychiatrica scandinavica, 67(6), 361-370. Disclosure of Interests: None declared more...
- Published
- 2019
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22. Theoretical study of the mechanism of 2,5-diketopiperazine formation during pyrolysis of proline
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José R. Mora, Vladimir Rodriguez, Cristian Cervantes, and Luis Rincón
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chemistry.chemical_classification ,010304 chemical physics ,Chemistry ,Biophysics ,Biomass ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,2,5-Diketopiperazine ,0104 chemical sciences ,Amino acid ,chemistry.chemical_compound ,0103 physical sciences ,Organic chemistry ,Proline ,Physical and Theoretical Chemistry ,Molecular Biology ,Pyrolysis - Abstract
In biomass pyrolysis reactions, the wide range of products obtained (some of them environmentally harmful) usually depends on the temperature and the content of amino acids, this fact results in ge... more...
- Published
- 2019
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23. Rehabilitation of heavily damaged beam-column connections with CFRP wrapping and SFRM casing
- Author
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Edgar Tapia-Hernández, Vladimir Rodriguez, Sergio M. Alcocer, and Héctor Guerrero
- Subjects
Carbon fiber reinforced polymer ,Materials science ,business.industry ,0211 other engineering and technologies ,Full scale ,Soil Science ,020101 civil engineering ,02 engineering and technology ,Structural engineering ,Dissipation ,Geotechnical Engineering and Engineering Geology ,0201 civil engineering ,Cracking ,Beam column ,Mortar ,Effective stiffness ,business ,Casing ,021101 geological & geomatics engineering ,Civil and Structural Engineering - Abstract
Results of an experimental testing program on two beam-column connections at full scale are presented. Specimens were first tested without initial damage. After that, rehabilitation was conducted using two different techniques, namely: externally bonded carbon fiber reinforced polymer and ultra-high performance mortar reinforced with steel fibers. Specimens were then re-tested. Different loading protocols were used on each specimen to assess their impact on the load-deformation capacity. Such protocols were displacement-controlled and applied quasi-statically. Performance of the specimens, before and after rehabilitation, is presented and discussed in terms of strength and drift capacity, energy dissipation, equivalent viscous damping, effective stiffness, cracking, and visual damage. Interesting findings, useful for the rehabilitation of concrete structures after strong earthquake ground motions, are presented. more...
- Published
- 2021
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24. Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter
- Author
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Shumilova, Oleksandra Zak, Dominik Datry, Thibault von Schiller, Daniel Corti, Roland Foulquier, Arnaud Obrador, Biel Tockner, Klement Allan, Daniel C. Altermatt, Florian Arce, María Isabel Arnon, Shai Banas, Damien Banegas‐Medina, Andy Beller, Erin Blanchette, Melanie L. Blanco‐Libreros, Juan F. Blessing, Joanna Gonçalves Boëchat, Iola Boersma, Kate Bogan, Michael T. Bonada, Núria Bond, Nick R. Brintrup, Kate Bruder, Andreas Burrows, Ryan Cancellario, Tommaso Carlson, Stephanie M. Cauvy‐Fraunié, Sophie Cid, Núria Danger, Michael de Freitas Terra, Bianca De Girolamo, Anna Maria del Campo, Ruben Dyer, Fiona Elosegi, Arturo Faye, Emile Febria, Catherine Figueroa, Ricardo Four, Brian Gessner, Mark O. Gnohossou, Pierre Gómez Cerezo, Rosa Gomez‐Gener, Lluís Graça, Manuel A.S. Guareschi, Simone Gücker, Björn Hwan, Jason L. Kubheka, Skhumbuzo Langhans, Simone Daniela Leigh, Catherine Little, Chelsea J. Lorenz, Stefan Marshall, Jonathan McIntosh, Angus Mendoza‐Lera, Clara Meyer, Elisabeth Irmgard Miliša, Marko Mlambo, Musa C. Moleón, Marcos Negus, Peter Niyogi, Dev Papatheodoulou, Athina Pardo, Isabel Paril, Petr Pešić, Vladimir Rodriguez‐Lozano, Pablo Rolls, Robert J. Sanchez‐Montoya, Maria Mar Savić, Ana Steward, Alisha Stubbington, Rachel Taleb, Amina Vander Vorste, Ross Waltham, Nathan Zoppini, Annamaria Zarfl, Christiane more...
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biofilms, leaching, leaf litter, rewetting, sediments, temporary rivers - Abstract
Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events. more...
- Published
- 2019
25. GROWTH, WAR, AND PANDEMICS: EUROPE IN THE VERY LONG-RUN.
- Author
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de la Escosura, Leandro Prados and Vladimir Rodriguez-Caballero, Carlos
- Published
- 2020
26. FRI0067 ANXIETY AND DEPRESSION IN A PREGNANCY AND RHEUMATIC DISEASES CLINIC
- Author
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Skinner Taylor, Cassandra Michele, primary, Barbosa, Lorena Pérez, additional, Trujillo, María Eugenia Corral, additional, Riegatorres, Janett Carmen, additional, Galarza-Delgado, Dionicio Ángel, additional, and Hinojosa, Jairo Vladimir Rodriguez, additional more...
- Published
- 2019
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27. Experimental tests of precast reinforced concrete beam-column connections
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Héctor Guerrero, J. Alberto Escobar, Vladimir Rodriguez, Felipe Bennetts, Sergio M. Alcocer, and Manuel Suarez
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business.industry ,Computer science ,0211 other engineering and technologies ,Full scale ,Soil Science ,Stiffness ,020101 civil engineering ,02 engineering and technology ,Structural engineering ,Deformation (meteorology) ,Dissipation ,Geotechnical Engineering and Engineering Geology ,0201 civil engineering ,Precast concrete ,Bending stiffness ,Benchmark (computing) ,medicine ,medicine.symptom ,business ,Joint (geology) ,021101 geological & geomatics engineering ,Civil and Structural Engineering - Abstract
In the reinforced concrete (RC) precast industry there is great concern about the seismic behavior of connections that emulate monolithic ones. Therefore, an experimental program was developed to examine the seismic performance of a particular RC precast connection type frequently used in industrial applications in comparison to monolithic connections. Tests were conducted on full scale. This paper presents and discusses the main results. Comparisons of a benchmark monolithic connection and six precast beam-column joints are presented. Precast connections were fabricated using different detailing, various levels of joint confinement, and post-tensioning. Test results are compared in terms of strength and deformation capacity, energy dissipation, and stiffness degradation. A relation between effective beam stiffness and inter-storey drift is found and compared to cracked stiffness modification factors recommended by design codes. Two effective stiffness models for reinforced concrete beams are proposed. Conclusions relevant to the precast construction industry have been formulated. Results show an acceptable performance of the tested precast system for seismic applications. more...
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- 2019
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28. A valence bond study of the activation of methyl halides bonds by electric fields
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Gerardo Armijos-Capa, Paúl Pozo-Guerrón, F. Javier Torres, José R. Mora, Luis Rincón, and Vladimir Rodriguez
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Materials science ,010405 organic chemistry ,Bond ,Halide ,010402 general chemistry ,01 natural sciences ,Dissociation (chemistry) ,0104 chemical sciences ,Computer Science Applications ,Crystallography ,Computational Theory and Mathematics ,Electric field ,Valence bond theory ,Physical and Theoretical Chemistry - Abstract
In the present work, the activation of methyl halides bonds under experience of an external electric field (EEF) is explained from the Valence Bond theory perspective. The dissociation mechanism of C–X bonds (X [Formula: see text] Cl, Br, I) influenced by a homogeneous and a heterogeneous field placed parallel to the bond axis is presented. For all examples, an increase in the electric field strength have similar consequences: (i) the decrease of the energy depth along the dissociation path, (ii) an increase of the equilibrium interatomic distance (at high EEFs), and (iii) the transition from a homolytic to a heterolytic dissociation after some field magnitude. These general behaviors are explained through the curve crossing between the ionic and the covalent structure at some field strength. more...
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- 2019
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29. Study of dielectric parameters and the internal electric field prediction in an individual wheat grain particle
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Iryna Ponomaryova, Mario Vladimir Rodriguez Gonzalez, and Amauri Vidal Castrejon
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Permittivity ,Vacuum permittivity ,Materials science ,Condensed matter physics ,Electric field ,Dielectric heating ,Electric susceptibility ,Electronic engineering ,Physics::Optics ,Relative permittivity ,Dielectric loss ,Dielectric - Abstract
The importance of dielectric parameters measurements of grain crops and insects is discussed in this work. The dielectric parameters behavior defines parameters such as external electric field and frequency that are necessary for grain disinfestation by radiofrequency and microwave. The beneficial frequencies are defined especially in a range 80-100MHz when the dielectric loss factor of insects exceeds 7 times that of wheat. A mathematical model is applied to one individual seed of grain of ellipsoidal shape. The calculations in MATLAB R2013a help to predict that less relative dielectric permittivity allows more energy absorption by the seed from the external electric field. more...
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- 2015
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30. Study of dielectric parameters and the internal electric field prediction in an individual wheat grain particle.
- Author
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Castrejon, Amauri Vidal, Gonzalez, Mario Vladimir Rodriguez, and Ponomaryova, Iryna
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- 2015
- Full Text
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31. Cross-Laminated Timber: Status and Research Needs in Europe.
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Espinoza, Omar, Trujillo, Vladimir Rodriguez, Laguarda Mallo, Maria Fernanda, and Buehlmann, Urs
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LAMINATED wood construction ,ENGINEERED wood industry ,CONSTRUCTION materials ,CONSTRUCTION laws - Abstract
In the 20 years since its invention in Europe, cross-laminated timber (CLT) has become a widely used construction material in parts of the old continent and has started to attract global attention. CLT possesses numerous advantages as a construction material, including its superior structural and environmental performance, as well as the speed and efficiency with which CLT buildings can be erected. In this study, European engineers were surveyed to learn about their current level of awareness of CLT, the major barriers to CLT adoption, and about the most pressing research needs to advance the use of CLT as a construction material. The study used a web-based survey with a convenience sample of 93 different kinds of timber and civil engineers and/or researchers, most of which belong to a European CLT research network. Results showed that participants think that, in general, the level of awareness about CLT among developers, construction managers, engineers, architects, and construction managers, is low. The majority of perceived barriers for CLT adoption involved its building code compatibility and the availability of technical information. The most pressing research needs for CLT development, according to respondents, are in the areas of structural performance and connections, moisture performance, and market research. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
- Full Text
- View/download PDF
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