Hydrogen photo-production by mixotrophic cultivation of chlamydomonas reinhardtii: Interaction between organic carbon and nitrogen

Hydrogen photo-production by a wild type and two engineered strains of Chlamydomonas reinhardtii was investigated. Growth rate values and hydrogen yields attained as the concentration of acetate and nitrogen vary were compared. In the analysis of microalgal growth, the interaction between organic carbon (acetate) and nitrogen (nitrate) was investigated by recourse to an experimental factorial design. This analysis evidenced the existence of a statistically significant interaction between organic carbon and nitrate. Hydrogen production was attained by cultivating microalgae previously grown in mixotrophic regime with sulphur deprived medium. The influence of varying the photobioreactor headspace on hydrogen production was investigated. This analysis revealed an increase in the hydrogen produced per unit volume of culture of about one order of magnitude when the headspace volume is modified from 100 to 350 mL. This result provides valuable indications on how to design and operate photobioreactors for hydrogen production optimization and was thoroughly discussed in terms of the metabolic pathways activated by sulphur depletion. ©2014, AIDIC Servizi S.r.l

Absenteeism, burnout and symptomatology of teacher stress: sex differences

Although numerous studies have been carried out confirming the high levels in the symptomatology of stress and depression in the teaching profession, research focusing on the sex differences in these problems has been both scarce and inconclusive. The objective of this study is to analyze the differences with regards to sex in the incidence of absenteeism, work-related stress, symptomatology of depression, level of burnout and psychiatric symptomatology. The sample consists of 71 teachers, 31 men and 40 women, all of them from Secondary Education. The tools used were the Questionnaire of Teacher Burnout (CBP-R), the Beck Depression Inventory (BDI), the Symptomatology Checklist-90-R (SCL-90-R) and a socio-demographic and work-situation questionnaire. Female teachers were expected to report higher level of absenteeism whereas their male counterparts were expected to show higher levels of symptomatology, burnout, particularly in Depersonalization, and similar levels of depressive symptoms are expected in both sexes. Results show sex differences only in Somatization, which mean was significantly higher in women than in men, and in the types of illness that caused sick leaves. In conclusion, this research support the results of other studies that have not found different patterns of stress, burnout and depression between female and male teachers

Humedal la macarena, Dosquebradas, propuesta de plan de acción comunitario

La presente investigación se realizó en el Humedal ubicado en el sector de los barrios La Macarena y el Limonar del Municipio de Dosquebradas, abordando el estudio desde la visión de un sistema socioecológico, partiendo desde el estudio de las variables y subvariables que conforman dicho sistema. nDespués del diagnóstico del sistema socioecológico y conociendo las interrelaciones entre sus diferentes variables y las percepciones de la comunidad, se hace la propuesta de plan de acción comunitario que contribuya con el reconocimiento del humedal por parte de la comunidad y la conservación del humedal La Macarena

Manual para el diseño de instalaciones eléctricas en edificios multifamiliares hasta de 3 pisos

El creciente interes a nivel nacional por la seguridad y la salud ocupacional ha motivado la generacion de normatividades estrictas en lo relacionado con un factor tan importante en la cadena productiva como lo son las instalaciones electricas. En Colombia la norma basica para el diseno y la construccion de dichas instalaciones es el CODIGO ELECTRICO COLOMBIANO o Norma ICONTEC NTC 2050. Esta norma esta basada en el \National Electrical Code. . NEC o Norma NFPA 70 de la \National Fire Protection Association. de los Estados Unidos de Norteamerica. En la realizacion del manual se tuvo en cuenta la normatividad de la Empresa de Energia de Pereira (E.P.P S.A E.S.P.) en lo que se refiere a los requerimientos necesarios para realizar el diseno electrico de edificios multifamiliares de hasta 3 pisos, incluyendo la alimentacion electrica, ubicacion de los tableros de medidores y planta de emergencia, de ser requerida por el propietario. Asi mismo se destaco la importancia que tiene el reglamento de instalaciones electricas (RETIE), cuyo objetivo es establecer medidas que garanticen la seguridad del usuario y la preservacion del medio ambiente. En consecuencia, el documento presentado a continuacion pretende convertirse en una herramienta que brinde ayuda a todas las personas directamente relacionadas con el uso de la Norma Tecnica Colombiana (NTC 2050) y el Reglamento Tecnico de Instalaciones Electrica (RETIE), entre los cuales se cuentan estudiantes, tecnicos, tecnologos e ingenieros electricistas. Se tuvo en cuenta tambien la evaluacion del nivel de riesgo con el fin de establecer si se hace el diseno de proteccion contra descargas atmosfericas de acuerdo a la norma tecnica colombiana NTC 4552-1,-2,-3

Una búsqueda hacia el saber creativo : Los procesos creativos y comunicativos en pos del aprendizaje significativo en la Institución Educativa Gustavo Arango Garrido

Dado el interés por investigar los fenómenos de la comunicación y la creatividad en el aula de clase, este trabajo de grado realiza un recorrido investigativo en la Institución Educativa Suroriental (sede Gustavo Arango Garrido), en donde a través de la recolección de la información, se obtienen datos claves que apuntan al desarrollo de una estrategia que aspira a fortalecer los procesos comunicativos y creativos en pos del aprendizaje significativo de los estudiantes. Por lo tanto, el presente trabajo pretende sentar una visión desde el estudiante como protagonista de su proceso de aprendizaje, al poder explorar sus posibilidades creativas y comunicativas a partir de las mediaciones que lo rodean.Given the interest to investigate the phenomena of communication and creativity in the classroom, this degree project makes a research tour in the Institución Educativa Suroriental (sede Gustavo Arango Garrido), where through the collection of information, key data is obtained that aimed to the development of a strategy that hopes to strengthen communication and creative processes in pursuit of meaningful learning for students. Therefore, this paper seeks to establish a view about the student as the protagonist of the learning process, where he is able to explore his creative and communication possibilities from the mediations that surround him

A time-dependent multi-layered mathematical model of filtration and solute exchange, the revised Starling principle and the Landis experiments

Cell oxygenation and nutrition is vitally important for human and animal life. Oxygen and nutrients are transported by the blood stream and cross microvessel walls to penetrate the cell's membrane. Pathological alterations in the transport of oxygen, and other nutrition elements, across microvessel walls may have serious consequences to cell life, possibly leading to localized cell necrosis. We present a transient model of plasma filtration and solute transport across microvessel walls by coupling flow and transport equations, the latter being non-linear in solute concentration. The microvessel wall is modeled through the superimposition of two or more membranes with different physical properties, representing key structural elements. With this model, the combined effect of the endothelial cells, the glycocalyx and other coating membranes specific of certain microvessels, can be analyzed. We investigate the role of transient external pressures in the study of trans-vascular filtration and solute exchange during the drop of blood capillary pressure due to the pathological decrease of blood volume called hypovolaemia, as well as hemorrhage. We discuss the advantage of using a multi-layered model, rather than a model considering the microvessel wall as a single and homogeneous membrane

The Clinical Eye: A Need to Improve the Teaching of Semiology in Undergraduate Medical Education

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Adaptation and psychometric properties of the school engagement and contextual factors questionnaires for Covid-19 and post Covid-19 context

School engagement has been demonstrated to be a relevant aspect in promoting students' successful trajectories, a commitment that in its turn is influenced by contextual factors (family, teachers, and peers). Having instruments to measure these constructs allows decisions to be made to improve student retention, especially relevant in the context of uncertainty caused by covid-19. The aim of the study was to adapt and analyze the psychometric properties of questionnaires used to measure school engagement and contextual factors in the context of the pandemic with elementary school students in Chile. After adaptation of the instruments, through expert evaluation and focus groups with students, they were administered to 579 students in seventh and eighth grade (mean age = 12.79, 52% were boys), and to 334 students in fifth and sixth grade (mean age = 11.35, 38% were boys) in Chile. Confirmatory factor analyses showed that the two versions of the school engagement measurement instrument had an adequate fit with the original model of three correlated factors, cognitive, affective, and behavioral commitment. Similarly, these two versions of the instrument measuring the contextual factors had a good fit with the original model of three correlated factors, family, teachers, and peers. In addition, both versions of both questionnaires presented appropriate levels of internal consistency