462 research outputs found
Precise nondivergent analytic formulas for the radiative corrections to the beta energy spectrum in hyperon semileptonic decays over the entire Dalitz plot
Very accurate analytical expressions for the radiative corrections of
unpolarized hyperons semileptonic decays of charged and neutral baryons have
been obtained in the recent past. Some of these formulas contain logarithmic
singularities at the edges of the Dalitz plot for the three- and four-body
decays. These singularities are analyzed and integrated analytically to obtain
new divergentless formulas for the energy spectrum of the produced beta
particle. The new equations contain terms of the order alpha times the momentum
transfer, are applicable to any beta decay process and are suitable for a
model-independent experimental analysis.Comment: 22 pages, 4 figure
Desarrollo de semiconductores con estructuras tipo perovskitas para purificar el agua mediante oxidaciones avanzadas
En este trabajo se llevó a cabo la preparación a través del método sol-gel y la reacción en estado sólido de óxidos semiconductores pertenecientes a las familias del tipo perovskita simple, ABO3 y doble laminar, A2M2O7, como el NaTaO3, NaTaO3:A (A = La, Sm), y Sr2M2O7 (M = Ta, Nb), respectivamente. Éstos fueron probados en la reacción de degradación fotocatalítica de azul de metileno, cristal violeta y rojo alizarín S. En particular, la perovskita simple, NaTaO3:Sm, mostró la mejor eficiencia para la degradación de azul de metileno (t1/2 = 65 min), mientras que la perovskita doble laminar, Sr2Ta2O7, fue eficiente para degradar tanto el cristal violeta (t1/2 = 5 min), como el rojo alizarín S (t1/2 = 25 min). Para el caso del cristal violeta la eficiencia fue incluso mayor a la mostrada por la titania P25 Degussa. La eficiencia fotocatalítica mostrada por los óxidos tipo perovskita simple la hemos relacionado a la formación de su estructura cristalina y a los valores de área superficial específica, además del efecto favorable del dopante. Mientras que en el caso de los óxidos tipo perovskita laminar, la eficiencia se debió a la presencia de la fase cristalina y al pH del medio de reacción. Además, debido a que todos estos óxidos mostraron valores de Eg alrededor de 4.0 eV, su activida
Cambios en los ríos y cuencas de México en el siglo XX: la cuenca sabinos-zula en Jalisco
Water abundance in the Zula river basin was an importantreference for the establishment and growth of populationsin the towns of Arandas, Atotonilco el Alto, Tototlán andOcotlán. However, integration of municipalities into economicdevelopment during the second half of the 20th Centurytransformed the quality of the river watercourse. In the lastdecades, two of the principal changes that affect the Zulariver are: urban growth and the tequila industry boom. Theincrease in tequila’s popularity during the 1970s has made it adrink of global consumption, a process that was consolidatedwith the tequila designation of origin (TDO), and the creationof regulating organizations which allowed the vigilance andproductive protection of Agave tequilana Weber. Threedecades after the peak in national and international markets,the growing production of agave-tequila has transformed theenvironment of the Zula river basin. This document refers toRío Zula3, in Jalisco, México, to the changes that have occurredin the municipalities that make up the watercourse, and to theenvironmental factors that have impacted its basin during the20th Century.La abundancia de agua en la cuenca del río Zula fue un importantereferente para la instalación y crecimiento de los pobladoresde los pueblos de Arandas, Atotonilco el Alto, Tototlán yOcotlán. Sin embargo la integración de los municipios al desarrolloeconómico de la segunda mitad del siglo veinte transformóla calidad del cauce del río. En las últimas décadas dos de losprincipales cambios que impactan al río Zula son: el crecimientourbano y el auge de la industria tequilera. El incremento de lapopularidad del tequila en la década de los setenta lo ha convertidoen una bebida de consumo global, proceso que se consolidócon la denominación de origen tequila (DOT), y la creación deorganismos reguladores permitieron la vigilancia y protecciónproductiva del Agave tequilana weber. A tres décadas del augeen los mercados nacionales e internacionales, la creciente producciónde agave-tequila ha transformado el entorno ambientalde la cuenca del Río Zula. Este documento se refiere al RíoZula,3 en Jalisco, México, a los cambios que se dieron en losmunicipios que forman caudal, y a los impactors ambientales ensu cuenca durante el siglo XX
Content analysis of the effects of palliative care learning on the perception by nursing students of dying and dignified death
Background: Providing care for dying people and the death of patients are stressing situations faced by nursing students during their clinical practice. Learning about palliative care improves the management of emotions and the ability to cope when caring for patients in end-of-life processes. However, there is little knowledge on the effect of this learning on the students' perceptions of their own death. Objectives: To determine the effect of a palliative care course on the thoughts of nursing students about their own death. Design: A qualitative, descriptive, and comparative study was conducted based on content analysis, administering an open-ended questionnaire on dying and death at the start and end of a palliative care course. Participants: The study included 85 volunteers studying Palliative Care in the second year of their Nursing Degree at the University of Granada (Spain). Results: Students described their perceptions in more detail after the course, with more numerous code citations, and their post-course responses evidenced a reduction in anxiety about their own death and an increased recognition of the need to respect the decisions of patients for a dignified death. Conclusions: Palliative care learning modifies the perception by nursing students of their own death and their understanding of a dignified death, which may enhance the care they deliver to patients at the end of life
Study, mechanical characterization and mathematical modeling of compatible SEBS blends for industrial applications in orthopedics and childcare
"This is an Accepted Manuscript of an article published by Taylor & Francis in Polymer-Plastics Technology and Engineering on JUL 15 2013, available online:www.tandfonline.com/doi/full/10.1080/03602559.2013.763363"In this work, a system of compatible blends based on two
commercial grades of a thermoplastic elastomer, styrene-ethylene/
butylene-styrene (SEBS), with extreme Shore A hardness values
(5 and 90), was studied in order to obtain a range of different
performance blends for orthopedic and childcare applications, where
usually liquid silicone rubber is used. Mechanical properties of
different blends were obtained, and Equivalent Box Model (EBM)
was used for the prediction of the mechanical behavior. The results
show good agreement between the theoretical model and experimental
data of new blends of SEBS.The authors thank "Ministerio de Ciencia y Tecnologia", Ref: DPI2007-66849-C02-02 and Generalitat Valenciana FPA/2010/027 for financial support.Juárez Varón, D.; García Sanoguera, D.; Ferrándiz Bou, S.; Peydro, MA.; Balart Gimeno, RA. (2013). Study, mechanical characterization and mathematical modeling of compatible SEBS blends for industrial applications in orthopedics and childcare. Polymer-Plastics Technology and Engineering. 52(9):862-868. https://doi.org/10.1080/03602559.2013.763363S862868529Xiao, D., Mo, Y., & Choi, M. M. F. (2003). A hand-held optical sensor for dissolved oxygen measurement. Measurement Science and Technology, 14(6), 862-867. doi:10.1088/0957-0233/14/6/323Sagripanti, J.-L., & Bonifacino, A. (1996). Comparative sporicidal effect of liquid chemical germicides on three medical devices contaminated with spores of Bacillus subtilis. 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Plastics, Rubber and Composites, 29(5), 229-234. doi:10.1179/146580100101541003Lopez, L. M., Cosgrove, A. B., Hernandez-Ortiz, J. P., & Osswald, T. A. (2007). Modeling the vulcanization reaction of silicone rubber. Polymer Engineering & Science, 47(5), 675-683. doi:10.1002/pen.20698Bose, S., Mukherjee, M., & Das, C. K. (2009). Silicone Rubber Compatibilized Syndiotactic Polystyrene and Thermotropic Liquid Crystalline Polymer (Vectra A950) Blend. Polymer-Plastics Technology and Engineering, 48(2), 158-163. doi:10.1080/03602550802577346Vijayalakshmi, N., Reddy, M. M., Naidu, S. V., Ramanjappa, T., & Appalanaidu, P. (2008). Immiscibility of Silicone Rubber and Polymethylmethacrylate. International Journal of Polymeric Materials and Polymeric Biomaterials, 57(7), 709-716. doi:10.1080/00914030801891302Wang, J., Feng, L., Chao, X., & Feng, Y. (2012). Performance of Room Temperature Vulcanized (RTV) Silicone Rubber-Based Composites: DBDPO/RTV and DBDPE/Sb2O3/RTV. Polymer-Plastics Technology and Engineering, 51(12), 1245-1250. doi:10.1080/03602559.2012.699130Wu, C., Li, W., Gao, D., & Jia, M. (2009). Study of Resistance of Silicone Resin to Heat and Irradiation. Polymer-Plastics Technology and Engineering, 48(10), 1094-1100. doi:10.1080/03602550903147213Ahmad, Z., Kumar, K. D., Saroop, M., Preschilla, N., Biswas, A., Bellare, J. R., & Bhowmick, A. K. (2009). Highly transparent thermoplastic elastomer from isotactic polypropylene and styrene/ethylene-butylene/styrene triblock copolymer: Structure-property correlations. Polymer Engineering & Science, 50(2), 331-341. doi:10.1002/pen.21540Barbe, A., Bökamp, K., Kummerlöwe, C., Sollmann, H., Vennemann, N., & Vinzelberg, S. (2005). Investigation of modified SEBS-based thermoplastic elastomers by temperature scanning stress relaxation measurements. Polymer Engineering & Science, 45(11), 1498-1507. doi:10.1002/pen.20427Masoomi, M., Katbab, A. A., & Nazockdast, H. (2006). Reduction of Noise from Disc Brake Systems Using Composite Friction Materials Containing Thermoplastic Elastomers (TPEs). Applied Composite Materials, 13(5), 305-319. doi:10.1007/s10443-006-9018-7Puskas, J. E., Foreman-Orlowski, E. A., Lim, G. T., Porosky, S. E., Evancho-Chapman, M. M., Schmidt, S. P., … Lovejoy, K. (2010). A nanostructured carbon-reinforced polyisobutylene-based thermoplastic elastomer. Biomaterials, 31(9), 2477-2488. doi:10.1016/j.biomaterials.2009.12.003Reddy, S., Arzt, E., & del Campo, A. (2007). Bioinspired Surfaces with Switchable Adhesion. Advanced Materials, 19(22), 3833-3837. doi:10.1002/adma.200700733Xu, J., Zhang, A., Zhou, T., Cao, X., & Xie, Z. (2007). A study on thermal oxidation mechanism of styrene–butadiene–styrene block copolymer (SBS). Polymer Degradation and Stability, 92(9), 1682-1691. doi:10.1016/j.polymdegradstab.2007.06.008Chow, W. S., & Neoh, S. S. (2009). Mechanical, Morphological and Thermal Properties of Polycarbonate/SEBS-G-MA/Montmorillonite Nanocomposites. Polymer-Plastics Technology and Engineering, 49(1), 62-68. doi:10.1080/03602550903283034Hong, X., Nie, G., Lin, Z., & Rong, J. (2012). Structure and Properties of PPO/PP Blends Compatibilized by Triblock Copolymer SEBS and SEPS. Polymer-Plastics Technology and Engineering, 51(10), 971-976. doi:10.1080/03602559.2012.671422Savadekar, N. R., & Mhaske, S. T. (2010). The Effect of Vulcanized Thermoplastics and SEBS on the Impact Strength of PPT. Polymer-Plastics Technology and Engineering, 49(15), 1499-1505. doi:10.1080/03602559.2010.496426Taşdemir, M., Ersoy, S., & Uluğ, E. (2012). Effects of HIPS on the Sound Absorption and Impedance Ratio of SEBS/HIPS/CaCO3Polymer Composites. Polymer-Plastics Technology and Engineering, 51(9), 954-958. doi:10.1080/03602559.2012.680563Taşdemir, M., & Uluğ, E. (2012). 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The concept of death in children aged from 9 to 11 years: Evidences through inductive and deductive analysis of drawings
The objective of the research was to analyze children’s conceptualization of death through drawings, using a mixed approach, which combines deductive and inductive qualitative analysis. The sample consisted of 99 children aged 9–11 years, who were asked to elaborate a drawing about their idea of death and to explain it to the researchers. Drawings were coded basing on Tamm and Granqvist’s model (deductive analysis) and codes and categories were created and modified (inductive analysis). Three main categories were identified in the analysis and four sub-categories were modified and/or created: causes of death, good death, anxiety-fear and symbolization
La influencia del estrés y el optimismo sobre la calidad de sueño de mujeres con cáncer de mama
Objetivo: El objetivo de este estudio fue determinar la influencia del estrés y el optimismo sobre la calidad de sueño de mujeres con cáncer de mama. Método: Diseño trasversal correlacional. Los instrumentos utilizados fueron el Índice de Calidad del Sueño de Pittsburgh, la Escala de Estrés Percibido y la Escala de Orientación de Vida. Participaron 60 pacientes con cáncer de mama en estadios tempranos, sin metástasis, con una media de edad de 51,4 (±9,3) años. Resultados: Las pacientes obtuvieron una media de 7,5 (±4,4) del Índice de calidad de sueño global, en donde a mayor puntaje indica una mala calidad de sueño, una media de 24,5 (±9,5) para estrés y una media 37,6 (±5,5) para optimismo. Se obtuvo una correlación positiva y significativa entre el estrés y calidad de sueño global (r =0,349, p=0.006), y una correlación negativa y significativaentre optimismo y calidad de sueño (r =-0,524, p=0,001). El optimismo predice la calidad de sueño global en un 25,8%. Conclusión: En mujeres con cáncer de mama en estadios tempranos, la relación entre variables indica que a mayor estrés menor calidad de sueño, menor duración del dormir y más alteraciones de sueño. En cuanto a la variable de optimismo, indica que, a mayor optimismo, mayor calidad subjetiva de sueño, mayor duración, menor latencia de sueño y menos alteraciones del dormir. Por lo tanto, se concluye que, en mujeres con cáncer de mama, el estrés reduce la calidad de sueño mientras que el optimismo la beneficia directamente
Synthesis of TiB2-Ni3B Nanocomposite Powders by Mechanical Alloying
Combination of good oxidation resistance, thermal stability, hardness and high strength are great interest properties in engineering and, that are possible to obtain with the Ni-Ti-B ternary system. Mechanical alloying (MA) is an alternative method and cheapest for the synthesis of this kind of metal-ceramic materials with respect to the traditional melt and quench process. The transformation sequence of all the mixtures reported the formation of (ɣ Ni) phase with a nodular morphology and identified the additional presence of the TiB2 phase (needle morphology), which was more evident with the increase of titanium content (M2 and M3 mixtures) after 24 h of milling. Thermal activation of the milled powders showed the nucleation and growth of the Ni3B (O boride) and TiB2 (Hex) as the main phases after heat treatment, where the TiB2 phase (thin flakes morphology) was nucleated onto Ni3B matrix. Ternary alloy by MA took place under a metastable equilibrium, offering the possibility to form glassy alloys for compositions, which are not accessible by melting or quenching techniques
Damage Assessment on Buildings Following the 19th September 2017 Puebla, Mexico Earthquake
Understanding seismic risk enables efficient resource allocation in the effort to increase the resilience of our cities and communities. Field reconnaissance and data collection following disasters document the damaging effects of earthquakes to enable lessons and wisdom to accumulate from past events. An important aim of such field data analysis is establishing a better understanding of building performance such as causes of building failures. These lessons provide essential basis to improve our design codes, develop regulations and policies, to increase building resilience by addressing the infrastructure vulnerability. Currently, to make use of the datasets from around the world, significant effort is required to decode the data which often have unique local and regional context and bias. The struggle begins at data collection where there is a lack of consistent methodology and definitions that can adequately cover the regional nuance. This manuscript proposes a new paper-based tool which addresses the need for a global yet detailed universal methodology for building damage assessment post-earthquakes. The new form is based on the GEM taxonomy v2.0 and the European Macroseismic Scale EMS-98. The recent Mexican earthquake from the 19 September 2017 led to significant building damage in the capital Mexico City and the state of Morelos. A team from New Zealand assessed damage throughout the capital and tested the new paper form in Calle La Morena. The street case study presents a novel visualization of the damage data and buildings characteristics which highlights the correlation between the damage and the building features. It is hoped that this kind of illustration will lead to better comprehension of the damage drivers
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