Prevalencia de Helicobacter pylori en el agua de consumo humano de pacientes diagnosticados con cáncer gástrico Helicobacter pylori positivo en el Instituto Nacional de Enfermedades Neoplásicas 2015 - 2016

Evalúa la presencia de H. pylori en el agua de consumo humano de los pacientes diagnosticados con cáncer gástrico y que son H. pylori positivo. La población de estudio está conformada por 84 muestras de agua que corresponden a 84 pacientes con diagnóstico de cáncer gástrico. Se recolectan las muestras de agua, con un volumen de 2L., de cada domicilio. Se evalúa la presencia de los genes de factores de colonización: ureasa (ureA) y proteína de shock térmico (hspA), mediante la técnica de Reacción en cadena de las polimerasas cuantitativa (qPCR). De la población en estudio se observa que el 47.62 % son mujeres y el 52.38 % son varones. Todos los pacientes en estudio residen en Lima, pero el 70.24% nacieron en provincia y el 29.76% nacieron en Lima. La zona de Lima sur presenta la mayor cantidad de pacientes con diagnóstico de cáncer gástrico con un 28.57%, seguida de Lima norte y Lima este con 21.43% y 20.24% respectivamente. Se documenta que el 84.52% de los pacientes venían residiendo en sus hogares un tiempo mayor a 10 años, y sólo el 8.33% residían en su domicilio actual un tiempo no mayor a 5 años. De las 84 muestras de agua evaluadas, se observa una prevalencia de H. pylori, con al menos un resultado positivo en alguno de los dos factores de colonización evaluados, en el 11.90 % (10/84) del total de las muestras agua evaluadas, ubicándose 6 de ellas en la zona este de Lima.Tesi

Estudio comparativo sobre metodologías de flujo de potencia en sistemas de distribución

Este trabajo contiene un estudio comparativo entre diferentes metodologías de flujo de potencia para sistemas eléctricos de distribución. Inicialmente se realiza una descripción de cada una de las metodologías, posteriormente se realiza una serie de pruebas en las que se tiene en cuenta el tiempo de calculo, las iteraciones requeridas por cada método entre otros aspectos de interés. Finalmente se comparan las diferentes metodologías, para así determinar cual es la metodología mas apropiada para cada problema

EGR cylinder deactivation strategy to accelerate the warm-up and restart processes in a Diesel engine operating at cold conditions

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/14680874211039587[EN] The aftertreatment systems used in internal combustion engines need high temperatures for reaching its maximum efficiency. By this reason, during the engine cold start period or engine restart operation, excessive pollutant emissions levels are emitted to the atmosphere. This paper evaluates the impact of using a new cylinder deactivation strategy on a Euro 6 turbocharged diesel engine running under cold conditions (-7 degrees C) with the aim of improving the engine warm-up process. This strategy is evaluated in two parts. First, an experimental study is performed at 20 degrees C to analyze the effect of the cylinder deactivation strategy at steady-state and during an engine cold start at 1500 rpm and constant load. In particular, the pumping losses, pollutant emissions levels and engine thermal efficiency are analyzed. In the second part, the engine behavior is analyzed at steady-state and transient conditions under very low ambient temperatures (-7 degrees C). In these conditions, the results show an increase of the exhaust temperatures of around 100 degrees C, which allows to reduce the diesel oxidation catalyst light-off by 250 s besides of reducing the engine warm-up process in approximately 120 s. This allows to reduce the CO and HC emissions by 70% and 50%, respectively, at the end of the test.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Authors want to acknowledge the support of "Programa de Ayudas de Investigacion y Desarrollo (PAID-01-17) de la Universitat Politecnica de Valencia''.Galindo, J.; Dolz, V.; Monsalve-Serrano, J.; Bernal-Maldonado, MA.; Odillard, L. (2022). EGR cylinder deactivation strategy to accelerate the warm-up and restart processes in a Diesel engine operating at cold conditions. International Journal of Engine Research. 23(4):614-623. https://doi.org/10.1177/1468087421103958761462323

Advantages of using a cooler bypass in the low-pressure exhaust gas recirculation line of a compression ignition diesel engine operating at cold conditions

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087420914725[EN] The low efficiency of the after-treatment systems during the cold start period of the internal combustion engines leads to excessive pollutant emissions levels. To reduce the nitrogen oxide emissions at these conditions, it could be necessary to use the high- and low-pressure exhaust gas recirculation strategies, even operating at low temperatures. This article evaluates the impact of using a low-pressure exhaust gas recirculation cooler bypass in a Euro 6 turbocharged diesel engine running under cold conditions (-7 degrees C). A new compact line fitted with a bypass system for the cooler is used with the aim of accelerating the engine warm-up process as compared to the original low-pressure exhaust gas recirculation line. The system is evaluated following two strategies, first performing exhaust gas recirculation without bypass and then performing exhaust gas recirculation bypassing the cooler. The results show that the activation the low-pressure exhaust gas recirculation from the engine cold start leads to a significant nitrogen oxide emissions reduction. Moreover, the bypass activation leads to increase the engine intake temperature, reducing the engine warm-up time and the CO emissions due to better combustion efficiency. However, the activation of the low-pressure exhaust gas recirculation at low temperatures could produce condensation and fouling deposits on the engine components affecting their life span. These phenomena are visualized using endoscope cameras in order to identify the condensation time and the final conditions of the elements. In addition, a chemical analysis of some condensates collected during the experiments and a comparison versus other species found in the literature is presented.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by the "Programa de Ayudas de Investigacion y Desarrollo (PAID-01-17) de la Universitat Politecnica de Valencia.''Galindo, J.; Dolz, V.; Monsalve-Serrano, J.; Bernal-Maldonado, MA.; Odillard, L. (2021). Advantages of using a cooler bypass in the low-pressure exhaust gas recirculation line of a compression ignition diesel engine operating at cold conditions. International Journal of Engine Research. 22(5):1624-1635. https://doi.org/10.1177/1468087420914725S1624163522

Impacts of the exhaust gas recirculation (EGR) combined with the regeneration mode in a compression ignition diesel engine operating at cold conditions

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/14680874211013986[EN] Internal combustion engines working at cold conditions lead to the production of excessive pollutant emissions levels. The use of the exhaust gas recirculation could be necessary to reduce the nitrogen oxides emissions, even at these conditions. This paper evaluates the impact of using the high-pressure exhaust gas recirculation strategy while the diesel particulate filter is under active regeneration mode on a Euro 6 turbocharged diesel engine running at low ambient temperature (-7 degrees C). This strategy is evaluated under 40 h of operation, 20 of them using the two systems in combination. The results show that the activation of the high-pressure exhaust gas recirculation during the particulate filter regeneration process leads to a 50% nitrogen oxides emissions reduction with respect to a reference case without exhaust gas recirculation. Moreover, the modification of some engine parameters compared to the base calibration, as the exhaust gas recirculation rate, the main fuel injection timing and the post injection quantity, allows to optimize this strategy by reducing the carbon monoxide emissions up to 60%. Regarding the hydrocarbons emissions and fuel consumption, a small advantage could be observed using this strategy. However, the activation of the high-pressure exhaust gas recirculation at low temperatures can produce fouling deposits and condensation on the engine components (valve, cooler, intake manifold, etc.) and can contribute to reach saturation conditions on the particulate filter. For these reasons, the regeneration efficiency is followed during the experiments through the filter status, concluding that the use of low high-pressure exhaust gas recirculation rates in combination with the regeneration mode also allows to clean the soot particles of the particulate filter. These soot depositions are visualized and presented at the end of this work with a brief analysis of the soot characteristics and a quantitative estimation of the total soot volume produced during the experimental campaign.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Authors want to acknowledge the support of "Programa de Ayudas de Investigacion y Desarrollo (PAID-01-17) de la Universitat Politecnica de Valencia.''Galindo, J.; Dolz, V.; Monsalve-Serrano, J.; Bernal-Maldonado, MA.; Odillard, L. (2021). Impacts of the exhaust gas recirculation (EGR) combined with the regeneration mode in a compression ignition diesel engine operating at cold conditions. International Journal of Engine Research. 22(12):3548-3557. https://doi.org/10.1177/14680874211013986S35483557221

New technological trends and their impact on the professional training of public accountant

El Contador Público se enfrenta a los retos de adaptarse a un entorno de en permanente cambios, razón por la que esta investigación reflexiona sobre las tendencias tecnológicas y su influencia en la formación de la contaduría pública. Siguiendo una metodología cienciométrica se recupera, analiza y sintetiza la información de diferentes autores que estudiaron el impacto de las nuevas tendencias en la profesión y cómo serían los retos en un futuro para este profesional. Las reflexiones dan cuenta que los sistemas operativos robotizados desplazan al contador público, por esto la pertinencia y fortaleza de la formación profesional en términos de competencias tecnológicas y de manejo, análisis e interpretación de la información contable, visualizando la profesión desde un enfoque más estratégico que táctico que contribuya a las organizaciones a través de la gestión de la contabilidad y la información para la toma de decisiones.Public accountants face the challenges of adapting to an ever-changing environment, which is why this research reflects on technological trends and their influence on public accounting education. Following a scientometric methodology, information from different authors who have studied the impact of new trends on the profession and the future challenges for this professional is recovered, analysed and synthesised. The reflections show that robotised operating systems are displacing the public accountant, hence the relevance and strength of professional training in terms of technological competencies and the handling, analysis and interpretation of accounting information, visualising the profession from a more strategic than tactical approach that contributes to organisations through the management of accounting and information for decision-making

“Desempeño laboral y su incidencia dentro de las ventajas competitivas en las microempresas comerciales del Cantón la Maná, Provincia de Cotopaxi, año 2020.”

The role of micro-enterprises in business activity is fundamental, it has the potential for self-development, self-sufficiency and growth. The problem arose from the empirical management of microenterprises, lack of knowledge about the importance of quality job performance, the low rate of training, the academic level of the owners and the impact it generates on the competitive advantages of a business, the general objective of this project was to analyze the incidence of job performance on the competitive advantages of commercial microenterprises of La Maná canton; in order to fulfill this purpose, bibliographic and field research was used, among the methods the theoretical method was used: logical historical , deductive, synthetic analytical and empirical method: expert assessment, in addition descriptive and correctional research was used. It was taken as a base the population universe of 3,830 commercial micro enterprises and 1,668 collaborators of the urban sector, applying the calculation of the sampling by strata it was possible to obtain a sample of 150 proprietors and 143 collaborators to whom the surveys were applied whose instrument was the questionnaire that was validated. The most relevant findings indicated that there is a relationship of 0.628 according to the factors of work performance (work environment, organizational culture, incentives, work satisfaction, competence, education, knowledge and experience) and competitive advantage (leadership by cost, differentiation, concentration), demonstrating that work performance is of vital importance to obtain competitive advantages. It is concluded that work performance has an impact on competitive advantages. In view of the results found, the creation of generic competitive advantages was proposed in order to improve profitability conditions and reduce costs in strategic products.El papel de las microempresas en la economía local y nacional es fundamental, tiene posibilidades de autodesarrollarse, autoabastecerse y de crecimiento. La problemática surgió frente al manejo empírico de las microempresas, falta de conocimiento sobre la importancia del desempeño laboral de calidad, el bajo índice de capacitaciones, el nivel académico de los propietarios, la investigación tuvo como objetivo analizar la incidencia del desempeño laboral en las ventajas competitivas de las microempresas comerciales del Cantón La Maná, con la finalidad de cumplir este propósito se recurrió a la investigación bibliográfica y de campo, entre los métodos se empleó el método teórico: histórico lógico, deductivo, analítico sintético y el método empírico: valoración por expertos, además se utilizó la investigación descriptiva y correccional. Se tomó como base el universo poblacional de 3.830 microempresas comerciales y 1.668 colaboradores del sector urbano, aplicando el cálculo del muestreo por estratos se logró obtener una muestra de 150 propietarios y 143 colaboradores a los cuales se aplicó las encuestas cuyo instrumento fue el cuestionario que fue validado. Los hallazgos más relevantes indicaron que existe una relación de 0,628 de acuerdo a los factores de desempeño laboral (ambiente laboral, cultura organizacional, incentivos, satisfacción laboral, competencia educación, conocimiento y experiencia) y ventaja competitiva (liderazgo por costo, diferenciación, concentración), demostrando que es de vital importancia el desempeño laboral para obtener ventajas competitivas. Se concluye que el desempeño laboral tiene incidencia en las ventajas competitivas. Frente a los resultados encontrados se planteó la creación de ventajas competitivas genéricas con la finalidad de mejorar las condiciones de rentabilidad y reducir los costos en productos estratégicos

Development of methods of extraction of oil in the production line of Biodiesel from Microalgae

Los combustibles de tercera generación se producen con biomasa diferente a la utilizada para los biocombustibles de primera y segunda generación, su obtención está basada en tecnologías emergentes que prometen una gran cantidad de combustible por unidad de área y menores costos de producción. El aceite proveniente de las microalgas ha aparecido en los últimos años como una potencial fuente de biodiesel debido a que el contenido de aceite de muchas especies de microalgas supera al contenido de aceite de todas las fuentes vegetales cultivadas actualmente, varios métodos de extracción de lípidos han sido evaluados en microalgas con el fin de hacer fácil, eficiente, económico y amigable con el ambiente el proceso de extracción. En este estudio, se presenta una revisión de los métodos de extracción de aceite que se han utilizado en la obtención de lípidos provenientes de microalgas a nivel de laboratorio (métodos de extracción con solventes químicos, shock osmótico, extracción con fluidos supercríticos, autoclavado, extracción con ultrasonido, extracción asistida con microondas, extracción mediante destrucción mecánica, extracción enzimática), así como una metodología de extracción con solventes químicos elaborada por los autores en el marco de proyectos apoyados por el Ministerio de Agricultura y Desarrollo Rural, la Corporación Instituto de Morrosquillo, el Instituto Colombiano del Petróleo ICP-ECOPETROL, la Universidad Industrial de Santander y el Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo CYTED.Abstract: Third generation biofuels are produced from different sources of biomass than the biomass sources used for first and second generation biofuels production, third generation biofuels production are based in emerging technologies that ensures high fuel production per area unit and lower production costs. Microalgae oil appears as a promising biodiesel source due to their oil content is bigger than oil content of other vegetal sources currently used. Several extraction methods has been evaluated on microalgae biomass for make easy, efficient, cheap and environmentally friendly the oil extraction process. In this review, some microalgae oil extraction techniques are discussed (chemical solvent extraction methods, osmotic shock, supercritical fluid extraction, autoclaving, ultrasound extraction, microwave assisted extraction, mechanical cell destruction, enzymatic extraction), such as a chemical solvent extraction methodology proposed by the authors in the developing of projects supported by the Colombian Agriculture & rural development ministry, the Instituto de Morrosquillo Corporation, the Colombian Petroleum Institute ICP-ECOPETROL, the Industrial University of Santander, and the Latinamerican Science & Technology Development Programme CYTED

Pro+: Automated protrusion and critical shear stress estimates from 3D point clouds of gravel beds

The dimensionless critical shear stress (τ*c) needed for the onset of sediment motion is important for a range of studies from river restoration projects to landscape evolution calculations. Many studies simply assume a τ*c value within the large range of scatter observed in gravel-bedded rivers because direct field estimates are difficult to obtain. Informed choices of reach-scale τ*c values could instead be obtained from force balance calculations that include particle-scale bed structure and flow conditions. Particle-scale bed structure is also difficult to measure, precluding wide adoption of such force-balance τ*c values. Recent studies have demonstrated that bed grain size distributions (GSD) can be determined from detailed point clouds (e.g. using G3Point open-source software). We build on these point cloud methods to introduce Pro+, software that estimates particle-scale protrusion distributions and τ*c for each grain size and for the entire bed using a force-balance model. We validated G3Point and Pro+ using two laboratory flume experiments with different grain size distributions and bed topographies. Commonly used definitions of protrusion may not produce representative τ*c distributions, and Pro+ includes new protrusion definitions to better include flow and bed structure influences on particle mobility. The combined G3Point/Pro+ provided accurate grain size, protrusion and τ*c distributions with simple GSD calibration. The largest source of error in protrusion and τ*c distributions were from incorrect grain boundaries and grain locations in G3Point, and calibration of grain software beyond comparing GSD is likely needed. Pro+ can be coupled with grain identifying software and relatively easily obtainable data to provide informed estimates of τ*c. These could replace arbitrary choices of τ*c and potentially improve channel stability and sediment transport estimates

Preventive antibiotic therapy in the placement of immediate implants: a systematic review

Immediate implants present a high risk of early failure. To avoid this, preventive antibiotics (PAs) are prescribed; however, their inappropriate administration leads to antimicrobial resistance. The present study aims to clarify whether the prescription of PAs reduces the rate of early failure of immediate implants and to establish guidelines to avoid the overprescription of these drugs. An electronic search of the MEDLINE database (via PubMed), Web of Science, Scopus, LILACS and OpenGrey was carried out. The criteria described in the PRISMA® statement were used. The search was temporarily restricted from 2010 to 2021. The risk of bias was analysed using the SIGN Methodological Assessment Checklist for Systematic Reviews and Meta-Analyses and the JBI Prevalence Critical Appraisal Tool. After searching, eight studies were included that met the established criteria. With the limitations of this study, it can be stated that antibiotic prescription in immediate implants reduces the early failure rate. Preoperative administration of 2–3 g amoxicillin one hour before surgery followed by 500 mg/8 h for five to seven days is recommended. It is considered prudent to avoid the use of clindamycin in favour of azithromycin, clarithromycin or metronidazole in penicillin allergy patients until further studies are conducted