2,597 research outputs found
A review of sample preparation and its influence on pH determination in concrete samples
If we are to monitor the chemical processes in cementitious materials, then pH assays in the pore solutions of cement pastes, mortars, and concretes are of key importance. However, there is no standard method that regulates the sample-preparation method for pH determination. The state-of-the-art of different methods for pH determination in cementitious materials is presented in this paper and the influence of sample preparation in each case. Moreover, an experimental campaign compares three different techniques for pH determination. Its results contribute to establishing a basic criterion to help researchers select the most suitable method, depending on the purpose of the research. A simple tool is described for selecting the easiest and the most economic pH determination method, depending on the objective; especially for researchers and those with limited experience in this field.Peer ReviewedPostprint (published version
A 2-set-up Routley-Meyer Semantics for the 4-valued Relevant Logic E4
The logic BN4 can be considered as the 4-valued logic of the relevant conditional and the logic E4, as the 4-valued logic of (relevant) entailment. The aim of this paper is to endow E4 with a 2-set-up Routley-Meyer semantics. It is proved that E4 is strongly sound and complete w.r.t. this semantics
Cultural Preservation of Ethnomedicine in Peru
In conjunction with the Minority Health & Health Disparities International Research Training program at San Diego State University, three Linfield students contributed to the ongoing Peru Ethnomedical Project in Trujillo, Peru by: Conducting surveys in two neighborhoods on the edge of the city; Creating a medicinal plant garden in the Chan Chan archaeological site museum.
Surveys conducted in Moche, Trujillo were part of a larger study supervised by anthropologists Douglas Sharon and Thomas Love. The research aims to evaluate the usage of medicinal plants in rural and urban Peruvian communities. Linfield’s contribution focused on the creation of the medicinal garden to serve as a community model and educational program. The overall purpose of the 2015 summer faculty collaborative project was to: Preserve the knowledge of these practices; Analyze the plant properties; Publish the information; Provide the community with a garden that reflects the commonly used plants; Educate new generations; Bring back and apply this knowledge in the Linfield community
Serotypes, intimin variants and other virulence factors of eae positive Escherichia coli strains isolated from healthy cattle in Switzerland. Identification of a new intimin variant gene (eae-η2)
BACKGROUND: Enteropathogenic Escherichia coli (EPEC) and Shigatoxin-producing Escherichia coli (STEC) share the ability to introduce attaching-and-effacing (A/E) lesions on intestinal cells. The genetic determinants for the production of A/E lesions are located on the locus of enterocyte effacement (LEE), a pathogenicity island that also contains the genes encoding intimin (eae). This study reports information on the occurrence of eae positive E. coli carried by healthy cattle at the point of slaughter, and on serotypes, intimin variants, and further virulence factors of isolated EPEC and STEC strains. RESULTS: Of 51 eae positive bovine E. coli strains, 59% were classified as EPEC and 41% as STEC. EPEC strains belonged to 18 O:H serotypes, six strains to typical EPEC serogroups. EPEC strains harbored a variety of intimin variants with eae-β1 being most frequently found. Moreover, nine EPEC strains harbored astA (EAST1), seven bfpA (bundlin), and only one strain was positive for the EAF plasmid. We have identified a new intimin gene (η2) in three bovine bfpA and astA-positive EPEC strains of serotype ONT:H45. STEC strains belonged to seven O:H serotypes with one serotype (O103:H2) accounting for 48% of the strains. The majority of bovine STEC strains (90%) belonged to five serotypes previously reported in association with hemolytic uremic syndrom (HUS), including one O157:H7 STEC strain. STEC strains harbored four intimin variants with eae-ε1 and eae-γ1 being most frequently found. Moreover, the majority of STEC strains carried only stx1 genes (13 strains), and was positive for ehxA (18 strains) encoding for Enterohemolysin. Four STEC strains showed a virulence pattern characteristic of highly virulent human strains (stx2 and eae positive). CONCLUSION: Our data confirm that ruminants are an important source of serologically and genetically diverse intimin-harboring E. coli strains. Moreover, cattle have not only to be considered as important asymptomatic carriers of O157 STEC but can also be a reservoir of EPEC and eae positive non-O157 STEC, which are described in association with human diseases
Towards a transdisciplinary approach in the training of teachers: Creating procedures in learning and teaching in higher education
[EN] For decades we have been immersed in a constant change in our society, registered together with an increase in its degree of complexity. This greatly affects the currently prevailing educational axioms, making them obsolete, which implies, according to our hypothesis, the need for a process of revision and innovation of existing models. Our proposal starts from a bibliographic review of some existing proposals in innovation, to create a new pedagogical model based on polyhedral and transdisciplinary methodologies. At the same time, we offer a case study in a core subject of the first teacher training course at the Autonomous University of Barcelona. After the practical application of our transdisciplinary methodological theories, it has been possible to successfully collect evidence of a balanced interaction between disciplinary areas by students. The application of the innovations can become a frame of reference for higher education institutions interested in following this very important process of adaptation to social reality.The present work was carried out thanks to the financing of ‘Ajuts de recerca per a la millora de la formació inicial de mestres’ (ARMIF) of the AGAUR - Catalan Government, and the support of the Faculty of Sciences Education, Autonomous University of Barcelona.Saura-Mas, S.; Blanco-Romero, A.; Barrera, J. (2021). Towards a transdisciplinary approach in the training of teachers: Creating procedures in learning and teaching in higher education. En 7th International Conference on Higher Education Advances (HEAd'21). Editorial Universitat Politècnica de València. 773-781. https://doi.org/10.4995/HEAd21.2021.13037OCS77378
Relational Semantics for the Paraconsistent and Paracomplete 4-valued Logic PŁ4
The paraconsistent and paracomplete 4-valued logic PŁ4 is originally interpreted with a two-valued Belnap-Dunn semantics. In the present paper, PŁ4 is endowed with both a ternary Routley-Meyer semantics and a binary Routley semantics together with their respective restriction to the 2 set-up cases
The class of all 3-valued natural conditional variants of RM3 that are Plumwood Algebras
Valerie Plumwood introduced in "Some false laws of logic" a series of arguments on how the rules Exported Syllogism, Disjunctive Syllogism, Commutation, and Exportation are not acceptable. Based on this we define the class of Plumwood algebras - logical matrices that do not verify any of these theses. Afterwards we provide conditional variants of the characteristic matrix of the logic RM3 that are also Plumwood algebras. These matrices are given an axiomatization based on First Degree Entailment and are endowed with Belnap-Dunn Semantics. Finally we provide results of Soundness and Completeness in the strong sense for each of the defined variants
Relational Semantics for the Paraconsistent and Paracomplete 4-valued Logic PŁ4
[EN] The paraconsistent and paracomplete 4-valued logic PŁ4 is originally interpreted with a two-valued Belnap-Dunn semantics. In the present paper, PŁ4 is endowed with both a ternary Routley-Meyer semantics and a binary Routley semantics together with their respective restriction to the 2 set-up cases.SIMinisterio de Ciencia e Innovación (MCIN/AEI/ 10.13039/501100011033
Comportamientos excesivos e intermitentes: diferencias en el consumo de alcohol e ingesta en forma de atracón entre adultos jóvenes de áreas rurales y urbanas
Introduction: Drug abuse and binge eating have been characterized as part of the so-called intermittent excessive behaviors, which share common neurobiological pathways. University students come from very different areas to access higher education, for example, rural environments, where some habits, education, and recreational options differ from those of people who grew up in the city. Contextual cues are crucial in the development of drug addic-tion, but little is known about the role that the living area where individuals grew up has on the development of intermittent excessive behaviors, such as binge eating and binge drinking. Objective: The main aim of this study was to explore the prevalence and comorbidity of alcohol consumption and binge eating behaviors in young adults (18-30 years), considering the living area where they grew up. Method: For this purpose, the AUDIT and the Binge Eating Scale were employed in a sample of 2461 undergraduates. Results: The results showed a significant propor-tion presenting a risky alcohol consumption pattern and a reduced proportion of people presenting binge eating behaviors. Interestingly, in both cases, there was a significant difference between groups, where rural students were more vulnerable to risky alcohol consumption and to developing maladaptive eating patternsIntroducción: La adicción a drogas y los atracones de comida se han caracterizado recientemente como parte de los llamados comportamientos excesivos e intermitentes, ya que comparten vías neurobiológicas comunes. Una tercera parte de los estudiantes universitarios proviene de entornos rurales, donde algunos hábitos, educación y opciones recreativas difieren de las de las personas que han crecido en la ciudad. El contexto es un factor crucial en el desarrollo de la adicción a las drogas, sin embargo, la relación del abuso de alcohol junto con atracones de comida y la influencia del entorno de origen en estos comportamientos ha sido poco estudiada. Objetivo: El objetivo princi-pal de este estudio fue explorar la prevalencia y comorbilidad de las conductas de consumo de alcohol y atracones en adultos jóvenes (18-30 años), teniendo en cuenta el lugar de residencia donde crecieron. Método: Para ello se emplearon el AUDIT y la escala de trastorno por atracón (Binge Eating Scale) en una muestra de 2461 estudian-tes universitarios. Resultados: Los resultados mostraron que una proporción significativa presentaba un patrón de consumo de alcohol de riesgo y una proporción reducida presentaba conductas de atracón. Se hallaron diferencias significativas, donde los estudiantes rurales fueron más vulnerables al consumo de riesgo de alcohol y al desarrollo de patrones alimentarios desadaptativo
Bioreceptivity optimisation of concrete substratum to stimulate biological colonisation
The lack of green areas in cities is caused by the increase in population and the urbanisation process. However, an increasing interest in city greenery was observed since the beginning of twentieth century. Several benefits are associated with green areas from a social, economic and ecologic point of view. Consequently, the solution to increase the urban green spaces lies in their inclusion on structures¿ surfaces. In that sense, a number of different technologies were developed which can be grouped into green walls and green roofs. Unfortunately, existing systems for both green walls and green roofs present several disadvantages in terms of installation and maintenance costs, low level of integration with the structure, extra loads, limitations in their use in rehabilitation projects, and others.
The general objective of this dissertation is to provide a first approach to the possibility of using a structure surface as biological substratum. This was treated considering two different research lines. The first research line includes the modification of the chemical and physical properties of the cementitious material, which will be used as substratum. Then, the second issue is the evaluation of materials¿ bioreceptivity under both laboratory and environmental conditions.
Regarding the material, chemical properties were firstly studied. pH was taken as a priority from the diversity of involved chemical properties. In that sense, two different ways to obtain a low pH cementitious material were studied. First, it was attempted to reduce the pH of the most common hydraulic binder, Ordinary Portland Cement (OPC). Then, the characterisation of Magnesium Phosphate Cement (MPC) as a hydraulic binder of naturally low pH was carried out. Insufficient reduction in the pH of OPC was obtained and properties such as flexural and compressive strength were highly affected. In contrast, positive results were obtained regarding the use of MPC as hydraulic binder for the specific purpose to be used as a biological substratum.
Regarding the physical properties, porosity and roughness were the main properties considered. For that purpose, modifications were made to the composition of different samples, by means of modifying the hydraulic binder, granular skeleton, the water to cement ratio and the amount of cement paste. The methodology used for the estimation of the optimal cement paste content worked well for OPC specimens although MPC responded differently. The characterisation of the twenty-three initial materials¿ bioreceptivities provided significantly different results. Consequently, six different mix designs were selected to be exposed to colonisation.
Afterwards, the evaluation of the materials¿ bioreceptivity in terms of colonisation was studied under both laboratory and environmental conditions. Regarding the experimental program under laboratory conditions, an accelerated laboratory test was carried out to evaluate the behavior of different specimens when they were exposed to colonization. Magnesium Phosphate Cement specimens obtained better results than OPC mortars for algal colonisation under those particular conditions.
Finally, specimens were also evaluated under environmental conditions, since these may significantly differ from laboratory conditions. Furthermore, two different inclinations and three different locations were studied. Significant differences were observed between inclinations (horizontal and vertical) and between locations with different contamination levels (Barcelona city, Natural Park of Montseny and Ghent city). Better results were obtained with horizontal specimens in terms of predominant genus diversity as well as quantitative level of colonisation. Moreover, specimens located in urban areas (Barcelona city) showed also better results. However, the environmental experimental programs should be continued over a longer time span to reach more conclusive results.La ausencia de espacios verdes en las ciudades es consecuencia del constante incremento poblacional y el proceso de urbanización. Sin embargo, existe un interés social creciente en aumentarlos desde inicios del siglo XX. Los beneficios asociados pueden englobarse en tres niveles: social, económico y ecológico. Por ello, la incorporación de elementos vegetales en los edificios se ha visto, principalmente, como una alternativa en aquellas ciudades con escasez de espacios disponibles para la construcción de áreas verdes. En este sentido, diversos sistemas han sido desarrollados tanto a nivel de fachadas como de cubiertas vegetales. Desafortunadamente, los sistemas existentes presentan diversos inconvenientes, los cuales se refieren a los costes de instalación y mantenimiento, a la baja integración entre los elementos naturales y la estructura, la carga adicional que conlleva y, en algunos casos, la limitación en su uso, entre otros.
El objetivo general de la presente tesis es demostrar que es posible utilizar el propio material cementicio como soporte biológico, para lo cual se han considerado dos líneas principales: modificar de forma controlada el material cementicio en base a sus propiedades químicas y físicas y, evaluar la bioreceptividad del soporte en muestras colonizadas.
En lo referente al material, primero se abordaron las propiedades químicas, fijándose como prioritario reducir el pH, para lo cual se abordaron dos vías: incorporación de ácidos en morteros en base a cemento Portland y, empleo de cementos en base a fosfato de magnesio. Las reducciones de pH alcanzadas para el cemento Portland no fueron significativas y sí, en cambio, la afectación a nivel de resistencias fue elevada. Por contra, los resultados obtenidos para el cemento en base a fosfato de magnesio fueron positivos, sin efectos secundarios.
Respecto a las propiedades físicas, se han considerado la porosidad y la rugosidad. Para la modificación controlada de estas propiedades se realizaron cambios entre dosificaciones en cuanto al tipo de cemento, al esqueleto granular, a la relación agua-cemento y a la cantidad de pasta de cemento. La metodología usada para la estimación de la cantidad de pasta de cemento funcionó correctamente para el mortero de cemento Portland. Sin embargo, el mortero en base a cemento de fosfato de magnesio presentó particularidades que hicieron cambiar los criterios de selección. Veintitrés tipos de mortero de diferente bioreceptividad fueron caracterizados y los resultados obtenidos permitieron reducir dicho número a seis, los cuales fueron expuestos a colonización.
En el proceso de evaluación del crecimiento biológico, las muestras fueron expuestas tanto a condiciones controladas de laboratorio, mediante un ensayo acelerado, como a condiciones ambientales, habiéndose obtenido los mejores resultados para las muestras en base al cemento de fosfato de magnesio. Finalmente, las muestras fueron expuestas a colonización ambiental, ya que los resultados podrían diferir considerablemente. Además de evaluarse los diferentes grados de bioreceptividad de las muestras entre sí, también se evaluó la influencia de la inclinación
(horizontal y vertical) así como de la localización comparando tres emplazamientos (Barcelona ciudad, parque natural del Montseny y Gante ciudad). Diferencias significativas fueron observadas entre muestras con diferente inclinación así como entre las localizaciones con diferente grado de contaminación ambiental. Las muestras horizontales presentaron mejores resultados a nivel de diversidad y cuantificación. Y, además, las muestras colocadas en zonas urbanas obtuvieron mejores resultados que aquellas en emplazadas en una zona no contaminada. Sin embargo, los resultados muestran la necesidad de más investigación en condiciones ambientales así como por periodos más prolongado
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