9,970 research outputs found
Education, Utilitarianism, and Equality of Opportunity
We analyze in this paper the impact of different policies on the investment of the families in the education of their children. Families make decisions on the level of human capital of their offsprings regarding the future income that this capital entails (under the assumption that higher education levels yield higher expected income). The families' optimal investment in education depends on their preferences (summarized by their time discount and risk aversion parameters) and their circumstances (initial wealth, parents' education, and children' natural abilities). The public authority designs a balanced tax/subsidy scheme in order to maximize aggregate welfare. We compare the case of a purely utilitarian planner with one that cares about the equality of opportunity.Equality of Opportunity, Investment in Education, Policy design
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
THE THREE MUSKETEERS: FOUR CLASSICAL SOLUTIONS TO BANKRUPTCY PROBLEMS
This paper provides a comparative analysis of some classical solutions to bankruptcy problems from an axiomatic viewpoint. These rules are the constrained equal-awards rule, the constrained equal-losses rule, the proportional rule and the Talmud rule. The purpose of this study is to facilitate the understanding of their differences and to clarify the type of situations in which each of these rules is better.Bankruptcy problems, proportional solution, equal-awards solution
Teaching students about chemical elements using daily-life contexts
Learning the names and symbols for chemical elements is a task that students often find dull, although it is of crucial importance for understanding chemistry. In this respect, the use of games or similar play activities could make the learning experience more enjoyable. This paper presents the results of a study in which two tasks involving play (TIPs) and based on daily-life contexts (football and the home) were used to teach the names and symbols of chemical elements. The experimental group comprised 38 year-10 students who studied this topic through a teaching unit built around the TIPs. A control group of 67 year-10 students followed a traditional teaching approach to the same topic. The effectiveness of the TIPs was assessed using three items, administered pre- and post-test, that explored students’ knowledge about metallic and non-metallic elements and their ability to identify them in their everyday environment. Following the TIP-based teaching unit, students in the experimental group gave a higher percentage of appropriate answers, with the Wilcoxon test indicating significant post-test differences for all three items. However, the Kolgomorov-Smirnov test indicated that the experimental and control groups only differed significantly at post-test in their ability to give the names and symbols of non-metals, with the experimental group performing better. Memorising the names and symbols of chemical elements is a complex task for students, and identifying their presence in everyday environments appears to be particularly difficult. However, the results suggest that the use of TIPs linked to daily-life contexts could help students with their learning of this topic.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech. Proyecto ‘I+D Excelencia’ EDU2013-41952-
Saturnino Rivera Manescáu y el museo arqueológico de Valladolid
Se repasa en este artÃculo la trayectoria de Saturnino Rivera Manescáu como director del Museo Arqueológico de Valladolid, investigador y profesor universitario entre los años veinte y cincuenta del siglo XX. Su trabajo abrió las posibilidades del Museo como institución al servicio tanto de los ciudadanos como de los profesionales de la ArqueologÃa. Desarrolló además de manera especial la colaboración entre el Museo y la Universidad en el ámbito de los estudios de ArqueologÃa e Historia del Arte.The paper reviews the Saturnino Rivera's work between twenties and fifties years, in XXth century, as director of the Archaeological Museum of Valladolid, researcher and university professor. His task opened the possibility of the museum to serve citizens and archaeologists. He specially developed the cooperation of Museum and University in archaeological and artistic studies
Down-regulation of a pectin acetylesterase gene modifies strawberry fruit cell wall pectin stracture and increases fruit firmness
Antisense-mediated down-regulation of several fruit-specific genes has previously demonstrated how the cell wall disassembly in strawberry fruit is mediated by a series of enzymes that act sequentially (Posé et al. 2011). An interesting example, the silencing of the polygalacturonase gene FaPG1, was also related with a significant increase of the post-harvest strawberry fruit firmness (Posé et al. 2013). Our research group has isolated a pectin acetylesterase gene, FaPAE1, which expression is enhanced during strawberry ripening. The main goal of this work was to elucidate the role of the degree of acetylation in cell wall integrity and fruit firmness through the antisense-mediated down-regulation of FaPAE1 in strawberry plants. Several transgenics lines were generated and 5 of them produced fruits 5-15% firmer than controls. Cell wall from ripe fruits was isolated from two independent transgenic lines and a control line, and sequentially extracted with different solvents (PAW, H2O, CDTA, Na2CO3). Modifications in fraction yield, its sugar composition and the degree of acetylation in each fraction were determined. Higher amounts of CDTA and Na2CO3 fractions were obtained in transgenic fruits, suggesting a decreased pectin solubilization as results of FaPAE1 silencing. Accordingly, the degree of acetylation of the Na2CO3-soluble pectins was greater in the transgenic lines than the control, but the opposite result was found in pectins from the CDTA fraction. These results suggest that PAE is preferentially active in pectis that are tightly bound to the cellulose-hemicellulose network and its activity could reduce the complexity of the cell wall structure, allowing that other hydrolytic enzymes could access the pectin chains. Thus, the increased fruit firmness observed in the transgenic FaPAE1 lines could be attributed to the direct effect of the silencing of the PAE enzyme and also to the indirect effect that the increase of the degree of acetylation of pectins has on the activity of other enzymes involved in the cell wall degradation.
* Posé et al. (2011). Genes, Genomes and Genomics, 5 (Special Issue 1):40-48
* Posé et al. (2013). Plant Physiology, 150: 1022-1032
We acknowledge support from the Spanish Ministry of Economy and competitivity and Feder EU Funds (grant reference AGL2011-24814), FPI fellowships support for SP (BES-2006-13626) and CP (BES-2009027985), and grant "Ramón y Cajal" support for AJMA (RYC-2011-08839).Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Identification of students' mental models about the milk transformation in yogurt
A review of the scientific literature reveals that there are still few researches on the conceptions of secondary school students about chemical reactions involving microorganisms, especially those related to the mental models that students use in their explanations. This paper describes a study concerning the different mental models related to the milk transformation into yogurt with 83 students from a Spanish secondary school of 8th and 9th grade (13-16 years) developed in the framework of a research that intends to use the elaboration of this product as a context for the teaching and learning of chemical reactions
through modeling approaches. In order to identify the mental models of the students, in this paper we consider the milk transformation into yogurt as a process in which its main components are: the entities involved (milk and bacteria), the interaction between them and the result (yogurt). A simplified school model of this process would involve students considering that bacteria use the sugar in milk to transform it into lactic acid through a chemical reaction to obtain the necessary energy. Using this scheme in interaction
with the students' answers, the underlying mental models were identified. Although almost half of the students showed great difficulties explaining the process, five models have been identified. Students often consider the milk transformation into yogurt primarily as a physical process of agglutination or change of state. These models are far from a school model of reference in which the bacteria have a fundamental role in the transformation of milk into yogurt by a chemical reaction.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Parametric assessment of a building active façade by means of a combined metallic sandwich panel with an unglazed solar collector
The building sector has a poor performance in terms of energy efficiency and is looking for alternatives to reduce the use of fossil fuels on building use stage. Renewables are unlimited and solar thermal energy is a technology with a demonstrated potential. The façade is a key element able to harness renewable energy coming from the sun becoming in an Active Solar Thermal Façade (ASTF). The main purpose of this study is the development of a parametric study using a numerical model to analyze the behavior of an unglazed solar collector. Thus, evaluating different design and meteorological parameters to show their influence on the heat transfer and the efficiency. The study shows that solar irradiation and mass flow are the most influential on thermal difference. However, for the efficiency ambient temperature and inlet temperature both are the most influencing ones. In brief, a set of parameters have a significant influence on the behavior of the ASTF that are fully governed by environmental conditions. Nevertheless, there are some other parameters that can be controlled during the operation. The challenge is to make a continuous configuration of this adaptable values depending on the external situation to achieve a higher performance for the ASTF
Intrinsicidad, relacionalidad y la reconstrucción del problema del individualismo.
Sc defiende la posibilidad de reconstruir la polémica acerca del individualismo en términos del contraste entre propiedades relacionales y propiedades no-relacionales. Como paso previo, se comparan dos análi sts de la noción de propiedad intrÃnseca, el primero basado en la no-reÃa cionalidad y el segundo ("lewisiano") basado en la noción de duplicado.Wc argue tbr the possibility of reconstructing the issue of indivi dualism ¡o tcrms of the eontrast between relational and nonrelational pro perties. As a previous step, two analyses of the notion of intrinsie pro perty are compared, the first based on nonrelationality and the second (inspired in D. Lewis) based on the notion of duplicate. Este trabalo ha sido realizado con la ayuda de una Beca Postdoctoral de la Fimndación Caja MadrkL y dentro del Proyecto de lmwestigación PB9S-0495-COS-04. financiado por el M FC. Vc'rsioncs umiteriores del mismo Fueron presentadas en el Seminario Co;tmpwitelano dc fulosofio ..`l oolÃtico t Santiago de Compostela. 17--2--00). en el CSIC (Madrid, 22--3--00) y en el III to,,r,'u'.so dc la SLMII.E (San Sebastián, 27-4-00). Agradezco a Manuel (iameiatiarpiniero. Conchin MartÃnez, Lrmi s Fernández MurenÃ, Lorenzo Peña, José Miguel Sagiii lÃo, Javier Vi lanova y Luis Vi legas sus val osos comentarios y Sugerencias. Xii m 2/MM)>. n¿i a. 23, pags. 105--127 Scm½uo t'ubl¡cacioae.s UniveHiad (?ornplumcnse. Madrid /4k/ugt /3b,.yufic~ Si &~,ca. de 1.06 Antonio Blanco Salguciro kley words: lntrinsicality, relationality, individualism, metaphysics of mea ning. 1
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