A simple theoretical, quantitative approach to help understand the titration of weak acids and bases

What happens at the very beginning of the titration of a weak acid or base is a question sometimes asked by undergraduate students when introduced to the concept of buffer solution. To attempt to answer this question, a simple quantitative approach is developed, which also allows explaining more general properties of the weak acid or weak base titration process, while serving as well as an introduction to the theoretical, quantitative treatment of this subject. Using this approach, it can be shown that, at the beginning of the titration, the reaction between a weak acid (base) and a strong base (acid) does not occur on a one to one ratio when very small amounts of the strong base (acid) are added.

The very early universe

The universe at very early times, before the GUT era, is discussed. The entropy problem is described. The horizon and flatness problems are subsumed into the general problem of finding plausible models of the physics of the Planck era or the era immediately after it. An outline of inflationary cosmology is given, including quantitative treatment of a scalar inflaton field, treated in both a classical and quantum approach, in order to find the average dynamics and the spectrum of perturbations, respectively.

Admissibility in Probabilistic Argumentation

argumentation is a prominent reasoning framework. It comes with a variety of semantics, and has lately been enhanced by probabilities to enable a quantitative treatment of argumentation. While admissibility is a fundamental notion in the classical setting, it has been merely reflected so far in the probabilistic setting. In this paper, we address the quantitative treatment of argumentation based on probabilistic notions of admissibility in a way that they form fully conservative extensions of classical notions. In particular, our building blocks are not the beliefs regarding single arguments. Instead we start from the fairly natural idea that whatever argumentation semantics is to be considered, semantics systematically induces constraints on the joint probability distribution on the sets of arguments. In some cases there might be many such distributions, even infinitely many ones, in other cases there may be one or none. Standard semantic notions are shown to induce such sets of constraints, and so do their probabilistic extensions. This allows them to be tackled by SMT solvers, as we demonstrate by a proof-of-concept implementation. We present a taxonomy of semantic notions, also in relation to published work, together with a running example illustrating our achievements.

Influencia de la implicación familiar en los deberes escolares en Educación Primaria. Percepción de la comunidad educativa en centros de la Región de Murcia

Este trabajo tiene como objetivo identificar las percepciones de la comunidad educativa del segundo tramo de Educación Primaria de centros de la Región de Murcia sobre la influencia que tiene la implicación familiar en la realización de los deberes escolares. La recogida de información se ha llevado a cabo mediante tres cuestionarios estructurados, elaborados ad hoc y destinados a cada uno de los grupos participantes. Tales grupos han estado conformados por 259 estudiantes, 81 docentes y 163 familias. El diseño de la investigación y la naturaleza de la información han requerido un tratamiento cuantitativo de carácter descriptivo, mediante un estudio de encuesta. Previamente al análisis de los resultados, también se ha estudiado la consistencia interna y la validez de constructo de las escalas de los cuestionarios en torno a la dimensión implicación familiar y deberes escolares. Entre los resultados se evidencia la existencia de una percepción positiva por parte de toda la comunidad hacia la participación de los progenitores en las tareas escolares, ya que piensan que dicha colaboración aporta grandes beneficios a los estudiantes. This study aims to identify the perceptions of the educational community of the Region of Murcia on the influence of family involvement in homework. The collection of information has been carried out through three structured questionnaires, elaborated ad hoc and intended for each of the participating groups. These groups have been formed by 259 students, 81 teachers and 163 families. Consequently, the participants add up to a total of 503. The design of the research and the nature of the information have required a quantitative treatment of a descriptive-comparative nature. Before the analysis of the results, the internal consistency and construct validity of the scales of the questionnaires around the dimension of family involvement and homework have also been studied. The results show the existence of a positive perception by the whole community towards the participation of parents in school tasks, since they think that this collaboration brings great benefits to schoolchildren.

Third-Century Inflation Reassessed

The conventional view of inflation in the Roman world, based on evidence from Roman Egypt, is that prices were steady from the middle of the first century AD until around AD 274, other than a doubling of prices between AD 160 and 190. By a quantitative treatment of the data for all available prices, and indicators of prices, this paper shows that this picture is broadly correct for wheat, but that prices for other goods increased throughout the period from AD 160 to 270. This pattern suggests that there were two co-existing market sectors. One for wheat, where prices appear to have been impacted by state action, and another where other commodities were left to find their own market level within a relatively free market.

QSAR by Minimal Topological Difference[s]: Post-Modern Perspectives

In the context of reconsidering the Quantitative Structure-Activity Relationship (QSAR) methods at the economical level, namely the optimization rules of OECD, the present review unfolds the key features of Minimal Sterical, Monte-Carlo and Minimal Topological Difference (MTD) methods, developed for quantitative treatment of the relations between biological activity of organic chemical compounds (drugs, pesticides, and so on) and their structures. The initial Minimal Steric Difference (MSD) is completed by the three-dimensional variant of the MTD method, being the last one referred to here, while the main principles of validating and guiding a viable QSAR method verified by the analytical-automated MTD, thus enlarging the perspectives of understanding the chemical-biological interaction at the level of ligand-receptor sites, cavity, and walls, with a true service to the future adaptive molecular design.