Spectral parameter power series method for discontinuous coefficients

Let (a,b) be a finite interval and 1/p, q, r be functions from L1(a,b). We show that a general solution (in the weak sense) of the equation (pu')'+qu = zru on (a,b) can be constructed in terms of power series of the spectral parameter z. The series converge uniformly on [a,b] and the corresponding coefficients are constructed by means of a simple recursive procedure. We use this representation to solve different types of eigenvalue problems. Several numerical tests are discussed

Notes of Epistemology of the Images

This article has as its subject of analysis the images as they are perceived by the observer. As a heuristic symphony this work is a paradigmatic crossover of the phenomenology, the genetic epistemology and the hermeneutics, amalgamated by semiotics. In the first paragraph, a phenomenological reflection of the images is carried out, reaching a division between internal images and external images and between objective images and sign images. In the second paragraph, a genetic analysis of a thought in images is carried out, reaching a division of the sign images in signal images, index images, icon images, symbol images and sign images with its correspondingly levels of abstraction and societal. Finally, in the third paragraph, hermeneutics of the object images as a cultural unit or culturema is carried out. It ends by framing the present study in visual studies and highlighting their relevance in the context of visual culture

Sfumato De Las Imágenes De Mundo En Su Dinámica Actual. Contribuciones Humanísticas Para Una Suturación Narrativizante De La Coexistencia

This article presents an eidetic investigation that aimed at the production of a narrativizing sense of the coexistence which is presented as a humanistic contribution to the suturing of the conjunctural emptiness of it For this six eidetic dimensions were brought to the front that are part of the shared objective world and therefore are repetitive structures that make up the underlying continuity of the interruption of coexistence aspecting the latter Such dimensions in the mode of eidetic succession-tension between Apollo-Dionysus rational thought-magic thought paranoid schizoid position-depressive position polis-urbs death-birth and leisure-weariness are made up of various eidetic conjunctions-disjunctions developed in the text and they emerge from the continuity-dispute between images of the technical and psychic-cultural world with its correlative mass society and urban tribal society In turn the possibility of observing the historic dynamics of world images as continuity-dispute was made possible by the acquisition of the tense and distended perspectives of time respectively characteristic of the metaphysical world imag

Simulation of the spatial Ca2+ dynamics in cardiac cells

59 páginas. Maestría en Ingeniería de Procesos.En años recientes se ha verificado que el metabolismo mitocondrial y la dinámica de Ca2+ se encuentran acoplados de forma compleja, lo cual se debe a la capacidad de la mitocondria de captar, almacenar y liberar iones Ca2+, así como a la activación del metabolismo energético por el Ca2+ mitocondrial. En los cardiomiocitos (células cardiacas), la alta demanda energética y la regulación del Ca2+ sobre el acople excitacióncontracción, vuelven determinante la interrelación entre los procesos antes mencionados. Incluso, el problema de la dinámica de Ca2+ y el metabolismo mitocondrial se ha definido como uno de los campos centrales en la fisiología y patología cardiacas. En este sentido, los métodos experimentales han enfrentado grandes dificultades para medir Ca2+ mitocondrial dinámico dentro de la estructura celular de los cardiomiocitos, lo que ha llevado a resultados experimentales controversiales. En el presente trabajo, la relación entre la dinámica de Ca2+ y el metabolismo mitocondrial se abordó mediante un enfoque de modelado y simulación. Además, dado que los cardiomiocitos presentan incrementos de Ca2+ altamente heterogéneos, por su estructura celular, la investigación se centró en el aspecto espacial. Así, la hipótesis de investigación es que, en los miocitos cardiacos, la localización de la mitocondria con respecto al espacio diádico determina los cambios en la dinámica de calcio y el metabolismo mitocondrial. En una primera etapa, se utilizó un modelo recientemente publicado (Wacquier et al., 2016) que describe la interrelación entre la señalización del Ca2+ y el metabolismo mitocondrial en células no excitables para desarrollar un modelo mitocondrial (MM) capaz de reproducir las características particulares de la mitocondria en las células cardiacas. En la segunda etapa se utilizó un enfoque de modelado compartamental con el fin de tomar en cuenta los aspectos espaciales, y se obtuvo un modelo acoplado (CM) integrado por el MM y un modelo de miocito ventricular humano (Grandi, Pasqualini, and Bers, 2010). Finalmente, el nuevo modelo integral se utilizó para demostrar que la posición de la mitocondria tiene un efecto significativo en la dinámica del Ca2+ y el metabolismo mitocondrial, lo anterior se realizó mediante el análisis de tres escenarios que corresponden distribuciones e interacciones particulares entre la mitocondria y los compartimentos intracelulares del modelo de célula cardiaca.It is well known that mitochondrial metabolism is linked to Ca2+ dynamics in a complex manner. This relation underlies on the capacity of mitochondria to uptake, release and storage Ca2+ as well as on the activation of the energetic metabolism by mitochondrial Ca2+. In cardiomyocytes (cardiac cells) this interplay becomes very important because of both the high energy demand (tissue-characteristic) and the regulation of excitationcontraction coupling by Ca2+. Ca2+ dynamics and mitochondrial metabolism has been defined as a key issue in cardiac physiology and pathology. However, experimental methods have strong limitations due to the difficulties in measuring dynamic mitochondrial Ca2+ in the intricated cellular structure of cardiomyocytes, leading to controversial experimental results. In the present project the relationship between Ca2+ dynamics and mitochondrial metabolism was addressed by modelling and simulation approach. Since in cardiomyocytes, Ca2+ increases are highly heterogeneous due to the cell structure, spatial aspects are considered as a main aspect. In fact, the working hypothesis is that the location of mitochondria with respect to Ca2+ channels plays a crucial role in determining the kinetics of Ca2+ changes and metabolism. As a first step, a previous model that properly describes the coupling between Ca2+ signalling and mitochondrial metabolism in a non-excitable cells (Wacquier et al., 2016) was used as a base to develop a new mitochondrial model (MM) able to account for the particular features of mitochondria in cardiac cells. In a second step, a compartmental modelling approach was used to account for the spatial aspects, so a coupled model (CM) was developed with the MM inside a model of a human ventricular myocyte (Grandi, Pasqualini, and Bers, 2010). Finally, the whole new model was used to prove that mitochondrial position has significant effect on Ca2+ dynamics and mitochondrial metabolism through the design of three scenarios corresponding to particular distributions and interactions between mitochondria and other intracellular compartments of the cardiac cell model

Returns to schooling in the portuguese economy: a reassessment

This paper provides an overview of the evolution of private returns to schooling in the Portuguese economy along the 1986-2013 period. We estimate the returns separately for men and women, at the mean and along the conditional wage distribution. Returns to schooling are found to be high, particularly for women, and to increase along the distribution. The magnitude of the returns increased throughout the 1986-2013 period, but particularly in the 1990s. We also provide estimates of the relative wage premium associated with specific levels of educational attainment and find that they are highest for tertiary education. In the first decades under analysis, relative wage premia associated with the 9th grade stand above those estimated for secondary education, whereas in the most recent period these differences are negligible.info:eu-repo/semantics/publishedVersio

tieval: An Evaluation Framework for Temporal Information Extraction Systems

Temporal information extraction (TIE) has attracted a great deal of interest over the last two decades, leading to the development of a significant number of datasets. Despite its benefits, having access to a large volume of corpora makes it difficult when it comes to benchmark TIE systems. On the one hand, different datasets have different annotation schemes, thus hindering the comparison between competitors across different corpora. On the other hand, the fact that each corpus is commonly disseminated in a different format requires a considerable engineering effort for a researcher/practitioner to develop parsers for all of them. This constraint forces researchers to select a limited amount of datasets to evaluate their systems which consequently limits the comparability of the systems. Yet another obstacle that hinders the comparability of the TIE systems is the evaluation metric employed. While most research works adopt traditional metrics such as precision, recall, and $F_1$, a few others prefer temporal awareness -- a metric tailored to be more comprehensive on the evaluation of temporal systems. Although the reason for the absence of temporal awareness in the evaluation of most systems is not clear, one of the factors that certainly weights this decision is the necessity to implement the temporal closure algorithm in order to compute temporal awareness, which is not straightforward to implement neither is currently easily available. All in all, these problems have limited the fair comparison between approaches and consequently, the development of temporal extraction systems. To mitigate these problems, we have developed tieval, a Python library that provides a concise interface for importing different corpora and facilitates system evaluation. In this paper, we present the first public release of tieval and highlight its most relevant features.Comment: 10 page