Conceptual fit: A criterion for COTS selection

COTS systems selection consists in evaluating the user requirements with respect to characteristics of candidate systems, using a set of criteria. One criterion that has received little attention is what we call conceptual fit. The criterion assesses the fit between the conceptual structure of the user requirements and that of a system. We evaluate the fit in terms of the existing misfits. We formally define the notion of conceptual misfit and we present a method that determines the conceptual misfits between the user requirements and a set of candidate systems. The method consists in defining a superschema, the mapping of the conceptual schemas of the candidate systems and of the user requirements to that superschema, and the automatic computation of the existing conceptual misfits. The method has been formalized in UML/OCL. We have conducted an exploratory experiment with the aim of evaluating the feasibility, difficulty and usefulness of the method, with positive results. We believe that the conceptual fit criterion could be taken into account by almost all existing COTS selection methods.Preprin

A universal ontology-based approach to data integration

One of the main problems in building data integration systems is that of semantic integration. It has been acknowledged that the problem would not exist if all systems were developed using the same global schema, but so far, such global schema has been considered unfeasible in practice. However, in our previous work, we have argued that given the current state-of-the-art, a global schema may be feasible now, and we have put forward a vision of a Universal Ontology (UO) that may be desirable, feasible, and viable. One of the reasons why the UO may be desirable is that it might solve the semantic integration problem. The objective of this paper is to show that indeed the UO could solve, or at least greatly alleviate, the semantic integration problem. We do so by presenting an approach to semantic integration based on the UO that requires much less effort than other approaches.Peer ReviewedPostprint (published version

CO2 and nutrient-driven changes across multiple levels of organization in zostera noltii ecosystems

Increasing evidence emphasizes that the effects of human impacts on ecosystems must be investigated using designs that incorporate the responses across levels of biological organization as well as the effects of multiple stressors. Here we implemented a mesocosm experiment to investigate how the individual and interactive effects of CO2 enrichment and eutrophication scale-up from changes in primary producers at the individual (biochemistry) or population level (production, reproduction, and/ or abundance) to higher levels of community (macroalgae abundance, herbivory, and global metabolism), and ecosystem organization (detritus release and carbon sink capacity). The responses of Zostera noltii seagrass meadows growing in low-and high-nutrient field conditions were compared. In both meadows, the expected CO2 benefits on Z. noltii leaf production were suppressed by epiphyte overgrowth, with no direct CO2 effect on plant biochemistry or population-level traits. Multi-level meadow response to nutrients was faster and stronger than to CO2. Nutrient enrichment promoted the nutritional quality of Z. noltii (high N, low C : N and phenolics), the growth of epiphytic pennate diatoms and purple bacteria, and shoot mortality. In the low-nutrient meadow, individual effects of CO2 and nutrients separately resulted in reduced carbon storage in the sediment, probably due to enhanced microbial degradation of more labile organic matter. These changes, however, had no effect on herbivory or on community metabolism. Interestingly, individual effects of CO2 or nutrient addition on epiphytes, shoot mortality, and carbon storage were attenuated when nutrients and CO2 acted simultaneously. This suggests CO2-induced benefits on eutrophic meadows. In the high-nutrient meadow, a striking shoot decline caused by amphipod overgrazing masked the response to CO2 and nutrient additions. Our results reveal that under future scenarios of CO2, the responses of seagrass ecosystems will be complex and context-dependent, being mediated by epiphyte overgrowth rather than by direct effects on plant biochemistry. Overall, we found that the responses of seagrass meadows to individual and interactive effects of CO2 and nutrient enrichment varied depending on interactions among species and connections between organization levels.European Regional Development Fund through the COMPETE; Portuguese funds through the FCT project [PEst-C/MAR/LA0015/2011]

EU-Rent car rentals specification

EU-Rent is a widely known case study being promoted as a basis for demonstration of product capabilities. However, no in-depth case analysis neither specification has been developed. Therefore, it was considered interesting, useful and even necessary to develop a complete study of the case, which would lead to its whole specification. On the other hand, it was considered a good opportunity to test the application of some proposals, such as alternate mechanisms to define integrity constraints and derivation rules, as well as an alternative approach to model events.Postprint (published version

Axioma d'elecció. Equivalències i aplicacions

Es tracta d'estudiar l'axioma d'elecció i alguns dels molts enunciats equivalents, entendre i explicar les demostracions de les equivalències sempre que l'argument estigui a l'abast d'un estudiant acabant el grau de matemàtiques, i estudiar també els principals resultats que s'obtenen aplicant aquest axioma i les seves demostracions

Classical String Dynamics in Curved Backgrounds

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2014, Tutor: Jorge G. RussoIn this bachelor thesis, we study a rotating classical string embedded in the 5- dimensional Anti-de-Sitter spacetime (AdS5), through the analysis of the dynamics of the Polyakov action. We compute its energy E and spin S and discuss the dependence E(S). The function E(S) is explicitly derived in two limiting cases: the short string case (in which the length of the string is considerably smaller than the characteristic length of AdS5) and the long string case (in which it is considerably greater). In the former case, the dependence E(S) previously derived for a at space is recovered

Tumors benignes vs. tumors malignes

Entenem com a tumor el creixement anòmal, per excés, d’una massa de cèl·lules determinades, que poden ser com les cèl·lules normals de l’organisme o bé pot tractar-se de cèl·lules atípiques. La diferència essencial entre els tumors benignes i els malignes rau en la  capacitat dels malignes d’escampar-se per tot el cos, per la qual cosa, el pronòstic d’aquests és, en principi, pitjor que el dels benignes. Aquesta afirmació pot no ser del tot certa, ja que pot donar-se el cas de tumors malignes amb baixa malignitat i de fàcil tractament i en l’altra banda tindrem els tumors benignes difícils de localitzar i de tractar i que poden ser força invalidants, com seran aquells que afectin a estructures de vital importància (cor, cervell...).Mots clau: tumor, tumors benignes, tumors malignes. ResumenSe denomina tumor al crecimiento anómalo, por exceso, de una masa de células determinadas, que pueden ser como las del propio organismo o bien tratarse de células atípicas. La diferencia esencial entre tumor benigno y maligno estriba en la capacidad de los malignos de extenderse por todo el cuerpo, por lo que el pronóstico de éstos, en principio, es peor que en el caso de los benignos. Esta afirmación puede, en determinadas ocasiones, ser discutida, ya que puede darse el caso de tumores malignos con malignidad baja y tratamiento sencillo y, por otro lado, tumores benignos difíciles de localizar y tratar que pueden ser altamente invalidantes, como son los que afectan a estructuras de importancia vital (corazón, cerebro...). Palavras clave: tumor, tumores benignos, tumores malignos.AbstractTumor is the name of an abnormal growth, by excess, of a mass of certain cells, which can be as the body itself or being atypical cells. The essential difference between benign and malignant tumor lies in the ability of the malignant ones to spread throughout the body, so the prognosis of these, in principle, is worse than in the case of the benign ones. This statement can, on occasion, be discussed, as it may be the case of malignant tumors with low malignancy and simple treatment and on the other hand we have benign tumors difficult to locate and treat that can be highly disabling, as they will be affecting vital structures (heart, brain...) Key words: tumor, benign tumor, malignant tumor