Reasoning about Explanations for Negative Query Answers in DL-Lite

In order to meet usability requirements, most logic-based applications provide explanation facilities for reasoning services. This holds also for Description Logics, where research has focused on the explanation of both TBox reasoning and, more recently, query answering. Besides explaining the presence of a tuple in a query answer, it is important to explain also why a given tuple is missing. We address the latter problem for instance and conjunctive query answering over DL-Lite ontologies by adopting abductive reasoning; that is, we look for additions to the ABox that force a given tuple to be in the result. As reasoning tasks we consider existence and recognition of an explanation, and relevance and necessity of a given assertion for an explanation. We characterize the computational complexity of these problems for arbitrary, subset minimal, and cardinality minimal explanations

Integrating Faith in Family a Family-Centered Catechesis

The purpose of this pastoral project is to develop a catechesis directed toward families. The underlying principle of this pastoral project is that family catechesis is the work of the entire parish and that, as stated in the General Directory for Catechesis, family catechesis must proceed, accompany, and enrich all forms of catechesis. This project will be directed toward sixty families of Cristo Rey Parish in Austin, Texas during the Fall semester of 2001. It will consist of six, one and one-half hour sessions to families. The sessions, conducted in Spanish and English, will include experiences of prayer, large group discussions, family sharings and interactive activities, all with the emphasis on unity and communication. This project will be a collaborative effort of Fr. Larry Mattingly, pastor; Fr. Jayme Matthias, assistant pastor and resource person; Sr. Guadalupe Medina, youth minister; Sr. Sylvia Castillo, DRE; and myself, Sr. Emma Stefanoni, project coordinator

DUROTAXIS MODELLING FOR TISSUE ENGINEERING APPLICATIONS

Tissue Engineering is a very promising research field for the development of natural biological substitutes that restore damaged tissue functions. Cells play a crucial role in tissue regeneration and repair due to their characteristics of proliferation and differentiation, cell-to-cell interaction, biomolecular production and extracellular matrix formation. In particular cell migration is a phenomenon that is involved in different physiological processes such as morphogenesis, wound healing and new tissue deposition. In the absence of external guiding factors it is essentially a phenomenon that shares quite a few analogies with Brownian motion. The presence of biochemical or biophysical cues, on the other hand, can influence cell migration in terms of speed, direction and persistence, transforming it in a biased random movement. Recent studies have shown that cells, in particular fibroblasts, are able to recognize the mechanical properties of a substratum over which they move and that these properties direct the motion through a phenomenon called durotaxis. The aim of this thesis is to study this phenomenon for a better understanding of cell behaviour in durotaxis conditions and for Tissue Engineering applications. In order to do that, in the first part of the work a mathematical model for the description of durotaxis is presented. The model is based on a stochastic differential equation for the cell velocity which is derived from the Langevin equation: cell movement is affected by two forces, namely a deterministic one representing the dissipative effects of the system, and a stochastic one which is due to all the probabilistic processes that might affect cell motility (random fluctuations in motile sensing, response mechanisms, etc.). The original contribution of this work concerns the stochastic force, which has been modified to account for the directions of highest perceived local stiffness through a finite element scheme that reminds the cellular probing mechanism. Numerical simulations of the model provide individual cell tracks that can be qualitatively compared with experimental observations. The present model is solved for two important cases that are reported in literature and a comparison with experimental data obtained on PDMS substrata is presented. The degree of agreement is satisfactory thus the model could be utilized to quantify relevant parameters of cell migration as a function of substratum mechanical properties. The second part of the work is concerned on the study and development of a durotaxis-based substratum, able to guide cells in their migration and in particular, able to guide cells along straight path. It was proved, in fact, that a relation exist between the alignment of collagen produced by fibroblasts or others tissue cells and their migration. Thus, the idea is to obtain an aligned tissue made of new collagen, giving to the cells the conditions to move along straight-lines through the mechanical properties of the substratum. To realize this substratum Polyethylenglycole (PEG) was used. First, smooth PEG was synthesized and cell migration experiments was performed over it to better understand its response. Then a specific technique was developed to produce durotaxis-based PEG substrata, and preliminary experiments of cell adhesion over it were performed showing aligned adhesion of cells over them

Kinetics of electrochemical dissolution of metals in porous media

Metals embedded in porous media interact electrochemically with the liquid phase contained in the pores. A widespread form of this, adversely affecting the integrity of engineered structures, is corrosion of steel in porous media or in natural environments. While it is well documented that the rate of this electrochemical dissolution process can vary over several orders of magni- tude, understanding the underlying mechanisms remains a critical challenge hampering the development of reliable predictive models. Here we study the electrochemical dissolution kinetics of steel in meso-to-macro-porous media, using cement-based materials, wood and artificial soil as model systems. Our results reveal the dual role of the pore structure (that is, the influence on the electrochemical behaviour through transport limitations and an area effect, which is ultimately due to microscopic inho- mogeneity of the metal/porous material interface). We rationalize the observations with the theory of capillary condensation and propose a material-independent model to predict the corrosion rate

Green’ntropy: semantic web / pragmatic web e Officine per la Sostenibilità della Ricerca come motore per riattivare la riqualificazione energetica degli edifici pubblici

In questo “position paper” si rappresentano obbiettivi modelli e metodi per contribuire ad avviare una campagna attiva di ricerca e sensibilizzazione sociale basata sull’interazione attraverso reti sociali e reti di automi basata nel Parco della Ricerca Enea Casaccia. Viene fornita un’anticipazione di quello che vuole essere il progetto “Sistemi Aperti Sapienza”; viene poi fornita una descrizione delle motivazioni di partenza e della riflessione che ha generato questa idea progettuale. Poi vengono considerate le ragioni per la convergenza di partner, identificati nei principali organismi della ricerca nel nostro territorio, in una organizzazione regionale guidata e ospitata da ENEA per raggiungere più rapidamente gli obiettivi dichiarati. La proposta prevede l’ implementazione presso ENEA, di un “FabLab”, un laboratorio finalizzato alla realizzazione di prototipi virtuali / reali, ovvero progettati attraverso software di modellazione 3d e stampabili attraverso stampanti 3d dall’utilizzatore finale. Ciò avverrebbe sulla scorta di quanto sta rapidamente diffondendosi in Italia e nel mondo sull’esempio del Center for Bits and Atoms (CBA) - MIT di Boston fondato da Neil Gershenfeld. Il FabLab Casaccia dovrebbe essere realizzato come una delle previste Officine della Sostenibilità specializzata nella produzione di soluzioni per la riqualificazione energetica degli edifici, per l’ applicazione delle energie sostenibili, per la diffusione virale di educazione e consapevolezza energetica e ambientale. Questo progetto, è pensato come un contributo di Sapienza nell’ambito della partnership al progetto di riqualificazione del Parco ENEA finalizzato ad operare per l’applicazione, prevista entro il 2015, delle misure di riqualificazione degli edifici nel settore della Pubblica Amministrazione.Peer Reviewe