Η διατριβή αναφέρεται στην μελέτη της σκέδασης κατά την διάδοση των υπερήχων μέσα σε σπογγώδες βόειο οστούν, και την μοντελοποίηση της έτσι ώστε να μας επιτρέπει να εκτιμήσουμε το πάχος των δοκίδων του σπογγώδους οστού. Αναπτύσσεται ένα πειραματικό μοντέλο οστεοπόρωσης, και μελετάται η επίδραση των μεταβολών της μικροδομής στην σκέδαση των υπερήχων. Oι υπέρηχοι αποτελούν μία διαφορετική μέθοδο εκτίμησης της ποιότητας του οστού δίνοντας πληροφορίες για την δομή του, επιπρόσθετα με την πυκνότητα. Η διάγνωση της οστεοπόρωσης στηρίζεται μέχρι σήμερα κυρίως στην εκτίμηση της πυκνότητας του οστού, με μετρήσεις της εξασθένισης και της ταχύτητας του υπερήχου. Μια άλλη προσέγγιση της εκτίμησης της ποιότητας του οστού γίνεται με την μελέτη της σκέδασης, η οποία μπορεί να δώσει πληροφορία για την ποιότητα και την αρχιτεκτονική δομή του σπογγώδους οστού. Η σκέδαση που υφίσταται ο υπέρηχος κατά την διάδοσή του στo σπογγώδες οστούν άρχισε να μελετάται το 2000 και έχει προσεγγισθεί με δύο μοντέλα. Το πρώτο θεωρεί διακριτές ανομοιογένειες του μέσου, και χρησιμοποιεί τις αναλυτικές λύσεις του Faran2 της διαφορικής διατομής σκέδασης από σφαιρικό η κυλινδρικό ελαστικό στερεό σώμα, γιά να περιγράψει την αλληλεπίδραση του υπέρηχου με το οστούν. To δεύτερο μοντέλο θεωρεί την διάδοση των υπερήχων σε τυχαία ανομοιογενές συνεχές μέσο και βασίζεται στην απόδειξη του Chernov, ότι η σκέδαση είναι ανάλογη του γινομένου της μέσης διακύμανσης της συμπιεστότητας και της συνάρτησης αυτοσυσχέτισης του μέσου. Στην παρούσα διδακτορική διατριβή για την μοντελοποίηση της σκέδασης κατά την διάδοση των υπερήχων στο βόειο σπογγώδες οστούν, χρησιμοποιήθηκε ένας συνδυασμός των δύο προσεγγίσεων. Οι σπουδαιότερες παραδοχές του μοντέλου είναι οι κάτωθι : • Υποθέτουμε ασθενή σκέδαση. • Υποθέτουμε ότι το δείγμα είναι στατιστικά ομογενές και ισότροπο. • Αγνοούνται τα φαινόμενα πολλαπλής σκέδασης, και • Δεν λαμβάνεται υπ’ όψιν η μετατροπή των διαμήκων κυμάτων σε διατμητικά. Οι παραδοχές του μοντέλου ικανοποιούνται από τα πειραματικά αποτελέσματα. Για την περιγραφή της μικροδομής του σπογγώδους οστού, χρησιμοποιήθηκαν δύο συναρτήσεις αυτοσυσχέτισης: μία τροποποιημένη Gaussian συνάρτηση πυκνού πληθυσμού για να ερμηνεύσει τις αρνητικές τιμές αυτοσυσχέτισης που παρατηρούνται μεταξύ δύο σημείων μέσα και έξω από μία ανομοιογένεια και αφορούν την πυκνότητα και την συμπιεστότητα, καθώς και το μεγάλο ποσοστό δοκίδων στην μονάδα του όγκου, και η συνάρτηση κατανομής μικρής συγκέντρωσης σφαιρών, για να εξηγήσει την ύπαρξη μεγάλων στο πλάτος δοκίδων με ελλειπτική ή σφαιρική τραχεία μορφή που συνεισφέρουν ένα ποσοστό στη σκέδαση. Για τα περισσότερα όμως δείγματα κανένα από τα δύο μοντέλα δεν ήταν επαρκές για να προσεγγίσει επ’ ακριβώς την συμπεριφορά του σπογγώδους οστού. Γι’ αυτόν τον λόγο προτάθηκε ένας συνδυασμός των δύο μοντέλων για να περιγράψει τα πειραματικά δεδομένα. Το αντίστροφο πρόβλημα της εκτίμησης του πάχους των δοκίδων του οστού αντιμετωπίσθηκε στην παρούσα διατριβή. Λόγω του εύρους της διακύμανσης του πάχους των δοκίδων στο βόειο σπογγώδες οστό, έγιναν διαγράμματα κατανομής του πάχους για κάθε δοκίμιο οστού και προσδιορίσθηκε το κυρίαρχο αντί για το μέσο πάχος δοκίδων, που έχει χρησιμοποιηθεί σε άλλες εργασίες. Η σύγκριση των πειραματικών μετρήσεων της διαφορικής διατομής σκέδασης 1800 με την θεωρητική πρόβλεψη, έδειξε ότι περισσότερες της μίας κυρίαρχες διαστάσεις δοκίδων συνεισφέρουν στην σκέδαση σε κάθε δοκίμιο. Σημαντική γραμμική συσχέτιση (R2=0.8558) βρέθηκε μεταξύ εκτιμώμενου και μετρηθέντος πάχους δοκίδων. Η εξασθένιση των υπερήχων κατά την διέλευσή τους μέσα από βιολογικούς ιστούς, έχει δύο συνιστώσες: την απορρόφηση και τη σκέδαση. Η προβλεπόμενη από την συνάρτηση αυτοσυσχέτισης του πυκνού πληθυσμού εξασθένιση λόγω σκέδασης, παρουσιάζει μία ευρεία γραμμική περιοχή από 0.3 έως 0.9 MHz για συνεχή κατανομή σκεδαστών (100 έως 600 μm), που επαληθεύεται από τα πειραματικά δεδομένα, υποδεικνύοντας ότι η εξασθένιση που υφίσταται ο υπέρηχος κατά την διάδοσή του στο σπογγώδες οστούν, οφείλεται σε μεγαλύτερο βαθμό στην σκέδαση απ’ ότι στην απορρόφηση. Στο δεύτερο μέρος της διατριβής αναπτύσσεται ένα πειραματικό μοντέλο προσομοίωσης της οστεοπόρωσης. Η οστεοπόρωση είναι μία σοβαρή νόσος των οστών, που χαρακτηρίζεται από χαμηλή οστική μάζα και πυκνότητα, μεταβολή της μικροδομής του οστού με μείωση του πάχους των δοκίδων και αυξημένο κίνδυνο κατάγματος. Στόχος είναι η εκτίμηση της επίδρασης των μεταβολών της μικροδομής, και της πυκνότητας του σπογγώδους οστού στις ιδιότητες των υπερήχων κατά την διάδοση τους μέσω του οστού, για την κατασκευή “εργαλείων” διάγνωσης της οστεοπόρωσης. H προσομοίωση της οστεοπόρωσης επιτυγχάνεται με σταδιακή αφαίρεση των ανόργανων συστατικών (απασβεστοποίηση) με εμβάπτιση σε υδροχλωρικό οξύ. Η ηλεκτρονική μικροσκοπία και η ιστολογική χρώση δείχνουν ότι, σε κάθε στάδιο απασβεστοποίησης, οι δοκίδες του οστού αποτελούνται από ένα πυρήνα άθικτο και ένα εξωτερικό στρώμα πλήρως απασβεστοποιημένο, το πάχος του οποίου εξαρτάται από τον χρόνο εμβάπτισης. Mε την διαδικασία αυτή επιτυγχάνεται η σταδιακή μείωση του πάχους των δοκίδων και επομένως η μείωση της πυκνότητας. Το μοντέλο ασθενούς σκέδασης με συνδυασμό δύο συναρτήσεων αυτό-συσχέτισης (του πυκνού πληθυσμού και της σφαιρικής κατανομής) που αναπτύχθηκε στο πρώτο τμήμα της διατριβής, χρησιμοποιήθηκε γιά την εκτίμηση του πάχους των δοκίδων στα διαδοχικά στάδια απασβεστοποίησης. Η ακρίβεια της εκτίμησης βρέθηκε ότι αυξάνεται με το πάχος των δοκίδων. / Ultrasound is currently being assessed as an alternative method of evaluating bone quality, and provides information about structure in addition to density. Ultrasound velocity and broadband ultrasound attenuation (BUA) determination has been explorer as an alternative method for estimating bone density and osteopososis. An other approach is the ultrasound scattering which inform us for the quality and architecture of the bone. Two different approaches have been proposed to model backscattering from cancellous bone. A first approach with discrete homogeneites use the analytical model of Faran which provides an exact solution of the backscatter cross section by a spherical or a cylindrical solid elastic object, to describe the interaction of trabecular bone with the ultrasonic wave. The second approach is based on Cernov’s proof that scattering is proportional to the product of the mean compressibility fluctuation and the autocorrelation function integrated over volume. A combination of the two autocorrelation functions was required to closely approximate the backscatter from bovine cancellous bone. The main limitations of the model are the following : • Weak scattering • The assumption of statistical homogeneity over one sample • First order multiple scattering • They do not account for shear waves in the scatterers The main limitations are satisfied from the experimental data Two simple scattering autocorrelation functions have been utilized to describe the microscopic structure of the random inhomogeneous medium: A modified Gaussian model has been considered to account for a large volume fraction of scatterers in the medium, the fluctuation in density and compressibility about the mean value, and the spherical distribution model because a number of larger plate-like scatterers with ellipsoid or roughly spherical shape may contribute to a portion of the scattering. The frequency dependence of the backscatter coefficient from bovine trabecular bone could not be discribed accurately either by scattering from a collection of randomly distributed identical scatterers or by a continuous model with a single dominant correlation length. This could be due to the tremendous variation in microarchitecture encountered in bovine trabecular bone. A combination of models was required to approximate the experimental data. The inverse problem to estimate the trabecular thickness of bone tissues has been addressed in this thesis. The estimates of correlation lengths from the combination of the two models were compared to trabecular thickness. Mean values of trabecular thickness display very large variation at both intraspecimen and interspecimen levels and cannot be used as estimates of the correlation length α. A significant contribution of this work is that interpretation of the correlation length was the dominant trabecular thickness, obtained from distribution graphs for each specimen. Significant linear correlation was found between predicted correlation length and measured trabecular thickness (R2=0.8558). In this study, it was found that the total attenuation by tissues is largely due to scattering processes than the attenuation due to absorption and the frequency dependence of attenuation due to scattering is linear for a densely populated distribution of scatterers from 100 to 600 μm, which have been measured in bovine cancellous bone, and in the range of frequencies 0.3-0.9 MHz. In the second part of this study a new experimental model was developed in order to simulate osteoporosis. Osteoporosis is a condition of reduced mass and density, change of bone 3D structure and increased fragility with a more pronounced effect on cancellous bone. Our purpose is the study of the ultrasonic frequency-depedent backscatter in dense bovine trabecular bone and the determination of a weak scattering model for the trabecular thickness which is relative to osteoporosis. The simulation of osteoporosis was developed in order to evaluate the effects of change of mineral content and microstructure on ultrasonic properties of cancellous bone with immersion in hydrocloric acid. Timed immersion in hydrochloric acid was used to selectively alter the mineral content. Scanning electron microscopy and histological staining of the acid-treated trabecular demonstrated a heterogeneous structure consisting of a mineralized core and a demineralized layer. Τhe accuracy of estimation was found to increase with trabcular thickness. A two-component model of weak scattering utilizing a combination of two autocorrelation functions (a densely populated model and a spherical distribution) to evaluate the trabecular thickness in various stages of decalcification. Τhe accuracy of estimation was found to increase with trabcular thickness.

The growth of micro-organisms in foods is different from that in axenic liquid culture in laboratory media. In natural environments, including food, micro-organisms generally grow in mixed culture and in close proximity to each other, because of which antagonistic or synergistic interactions can occur. To elucidate the behaviour of bacteria within food matrices an understanding of the food structure is required, as foods are complex ecosystems on the micrometer scale. Most processed foods are emulsions and as such are highly structured heterogeneous environments. Antibody-linked probes can be used for the immuno-location of micro-organisms or their products within food matrices to demonstrate the sites at which growth occurs and elucidate the possible bacterial interactions with food components. The aim of the project was to raise antibodies to spoilage Pseudomonas species and to use the developed antibody-linked probes to follow psychrotrophic spoilage Pseudomonas within heterogeneous foods. By using antibody-linked probes the natural spoilage of milk and milk products can be followed along traditional lines examining extrinsic parameters but with the additional benefit that the major spoilage organisms can be located within the mixed natural flora. The use of antibodies in this way facilitated the study of a defined natural population and surmounted any adaptive problems associated with introduced organisms. An oil-in-water near-foodgrade model was developed to investigate the growth of Pseudomonas as it overcame some of the technical problems of using natural cream. Pseudomonas species, which grew as colonies within the near-food-grade model, were visualised using fluorescently-labeled antibody-linked probes. Pseudomonas used to raise the antisera were isolated from psychrotrophically spoiled food and characterised together with isolates retrieved from the environment. The phenotypic characterisation of Pseudomonas using classical biochemical tests and API 20NE test strips (BioMerieux) did not produce definitive identifications of the unknown isolates. Nutritional screening of the Pseudomonas isolates using commercially produced standardised test microtitration plates (Biolog MicroPlate TM), that contained 95 carbon sources, was carried out. The data produced from the test microtitration plates were analysed using numerical taxonomic methods. The relatedness of the Pseudomonas isolates was strongly influenced by the source from which the test isolates originated and did not definitively identify all of the unknown isolates tested. Molecular techniques, ribotyping and amplified ribosomal DNA restriction analysis (ARDRA), based on the genomic fingerprinting of the 16S rRNA gene were evaluated to aid the definitive identification of the Pseudomonas isolates but needed a more extensive data base to be useful. The difficulties encountered in phenotypically identifying food and environmentally isolated Pseudomonas species stems from the fact that the Pseudomonas genus is now classified according to its ribosomal DNA homology. The classification of the species within the Pseudomonas genus is still under review. Robust phenotypic criteria for the identification of all the species within the genus have not to date been defined. In this study, the association of phenotype with environmental source of isolation (whether characterised by nutritional studies or by antibody cross-reaction) demonstrates clearly that more appropriate phenotypic characterisation is required to allow identification schemes to reflect the underlying phylogeny of this group.

This thesis presents a novel set of guidelines to convert between simulation modelling approaches, namely, Ordinary differential Equations (ODEs), System Dynamics (SD) and Agent-based Modelling and Simulation (ABMS). In our literature review we identify a gap in establishing translation techniques between these approaches. We therefore focus our research in developing these techniques and assessing the impact of these conversions in the simulation outcomes. In particular, our interest lies in investigating our techniques applied to simulation problems for the immune system, as we wish to aid immunologists with the choice of the most appropriate approach for a certain problem. The aims of this thesis are therefore defined as: (1) with no explicit guidelines available from the literature, we want to develop, test and validate our own set of guidelines for converting between approaches: from ODE models to SD, from SD to ABMS and from ABMS to SD; and (2) we seek to discuss the merits of SD and ABMS for Immunology to assist researchers with the choice between both approaches. The assessment of the effectiveness of the conversion guidelines is achieved by using a case study approach involving six cases of established mathematical models describing immunological phenomena. These case studies are chosen by considering aspects such as the behaviour of the entities of the model (whether they are static or interact with other entities and whether they have spatial representation or not), the type of hypothesis to be tested, the empirical embeddedness of real data, population sizes, number of elements involved and the modelling effort. In order to conduct our conversion for the case studies, we first convert their original ODE model into an SD model, and then perform the translation from SD to ABMS. For the last three case studies, we also test the conversion guidelines from ABMS to SD. Evidence from the experiments reveal that for all cases it was possible to obtain equivalent approaches by using the conversion guidelines developed. However, outcome differences occur given the intrinsic characteristics of each simulation modelling paradigm. By observing these differences we could conclude that (1) SD is incapable of reflecting exactly the same variability as that obtained from the agent-based simulation, as it is a deterministic approach; (2) SD variables change continuously in time and therefore population numbers over time might be different from those obtained by the agent-based simulation; (3) as the number of different agents and behaviours increase, the corresponding SD becomes very intricate and difficult to develop and understand; (4) there are cases where it is preferable not to convert from ABMS to SD, as the agent-based model is easier to conceptualise and implement; (5) For other circumstances, ABMS outcomes are the same as those produced by the ODEs and SD, with the disadvantage to be more resource consuming in terms of computational memory and processing capacity; and (6) For some cases SD is less informative than ABMS, as it does not produce multiple scenarios or variations over the course of more than one run within the same parameters.

Αντικείμενο αυτής της διπλωματικής εργασίας είναι η ανάλυση των εξελίξεων και των μελλοντικών προοπτικών με βάση ερευνητικά δεδομένα στη χρήση των δικτύων υψηλής τάσης για τηλεπικοινωνιακούς σκοπούς. / Purpose of this paper is the analysis of the development and the future perspectives based on research information and papers on the use of high voltage network for telecommunication reasons.

This thesis is a compilation and a cataloging a series of original artworks decorative type, for murals in different techniques, which have been linked to the inputs of the buildings that support, shape and own part of the architectural ensemble. Currently, this documentation is not closed or completed; new issues have appeared which deserve being catalogued in the future. Fieldwork is the starting point of this investigation, together with a great number of documentary sources, such as artist biographies, catalogs of related works as well as a thorough study of the artistic techniques employed in these works. To understand this type of artistic works is necessary to investigate a series of historical backgrounds. It is also necessary to know the hottest artists and their social, historical and cultural environment, having discovered between these artists collective groupings. Apart from the works to be studied, those located in the lobbies and hallways of private homes, I have contributed with other works from the same period which can be found at the entrance and common areas of public sector buildings. Besides, this research should also contribute to make people feel aware of how important the conservation and protection of our heritage is by recognizing its historic values, no matter how old is. This research is divided into the following three thematic sections: • The first block belongs to the introductory part of a historical nature, which studies the origin of pieces, their classification, cataloging and historical context, and a brief reference to those which have disappeared. It is sub-classified into public and private works. This block comes with a large graphic documentation, support data analysis and a variety of documentary sources. • The second part deals with the artists who created the works that formed this study, from the distant past to the present. This section includes a brief mention of their biographies and the groups these artists belonged to in the mid-twentieth century to explain the reasons that led to these style of works and their common features. • The third section contains a comprehensive study on plastic graphic techniques used to create these pieces, a difficult task because it was conducted in an era of experimental research of artistic techniques. This has led to more freedom in plastic art nowadays. • Finally, the reader would find several sections in Annexes related to these subjects, for example reports on analyzed items, diagrams, chronological axis, maps, and so on. To conclude the thesis, we have reached a number of general conclusions: • The decorative painting has been in the city of Murcia throughout history, and still today we find existing samples, we confirm this. • Far from the pictorial program major commissions, civil and religious, until the twentieth century that were common, comes a new type of job, the individual and private sphere, as well as at the institutional level. • The theme developed is varied, have also used different artistic trends such as figuration, abstraction, cubism and impressionist forms, among others. • These decorative and artistic achievements have used various mural painting techniques and media. • Many artists were the architects of this type of decorations, some had in common the same artistic interests, reaching thereby form a number of groups. • We know that you know works may appear today, but we must make clear the possibility of a successful expansion of this research present here • At the end of this work we have followed knowing data, as some unknown authorship. Thus this thesis is open to research, with the intention to continue researching and cataloging these works. / Trata de una recopilación y catalogación de una serie de obras artísticas originales de tipo decorativo, a modo de murales en variadas técnicas, que han quedado vinculadas a las entradas de los edificios que las sustentan y configuran así parte del propio conjunto arquitectónico. Actualmente esta catalogación no está cerrada ni concluida, pues a día de hoy siguen apareciendo nuevos ejemplares que merecen ser registrados en un futuro. El trabajo de campo es el detonante de esta investigación, acompañándolo de numerosas fuentes documentales, como biografías de artistas, catálogos de obras relacionadas, así como un minucioso estudio de las técnicas artísticas empleadas en dichas obras. Para entender este tipo de obras artísticas es necesario investigar una serie de antecedentes históricos. También es necesario conocer a los artistas del momento así como su contexto social, histórico y cultural, habiendo descubierto agrupaciones colectivas entre estos artistas. A parte de las obras a analizar, las situadas en los vestíbulos y zaguanes de las viviendas particulares, se han complementado con otras obras de la misma época, que están situadas en las entradas y en los espacios comunes de edificios de ámbito público. En parte, otro de los objetivos de este estudio de investigación, debería ser sensibilizar y concienciar al ciudadano de la importancia de la tarea de conservación y protección del patrimonio, del valor que tienen al presente y que pueden llegar a tener esta serie de obras en un futuro, y en conclusión, de saber valorar y reconocer su pasado histórico artístico aunque sea relativamente reciente. El trabajo de investigación aquí presente, se encuentra dividido en tres bloques temáticos, relacionados entre sí: El primer bloque pertenece a la parte introductora de carácter histórico, donde se estudia el origen de las piezas, su clasificación, catalogación y contexto histórico, así como una breve alusión a diferentes obras ya desaparecidas. Se encuentra subdividido entre obras de ámbito público y obras de ámbito privado. Este bloque viene acompañado de numerosa documentación gráfica, análisis de datos y apoyo en diversas fuentes documentales. El segundo bloque trata sobre los artistas creadores de las obras que comprenden el estudio de investigación, desde los más lejanos en el tiempo hasta los contemporáneos nuestros. Este bloque abarca una breve mención de sus biografías, las cuales nos relatan su vida y su trayectoria artística. También incluye este bloque las diferentes agrupaciones de dichos artistas, de tipo reivindicativo en su mayoría, las cuales surgieron sobre todo a mediados del siglo XX. Estudiando las razones que dieron lugar a este tipo de obras y sus características comunes. El tercer bloque contiene un amplio apartado dedicado a las técnicas grafico plásticas con las que se realizaron estas piezas, siendo muy variado debido a que se realizaron en una época de investigación experimental de las técnicas artísticas, que es el antecedente que ha dado lugar a que hoy podamos tener una mayor libertad en cuanto a la técnica plástica en el arte de hoy. Trata de un estudio de dichas técnicas y soportes, avalado por diferentes fuentes documentales. Finalmente en los anexos, encontraremos varios apartados relacionados con el tema a analizar. Así como los informes de las piezas analizadas, esquemas para una mayor comprensión, ejes cronológicos, mapas donde aparece la ubicación de las piezas, etc. Para concluir la tesis doctoral, hemos llegado a una serie de conclusiones generales: La pintura decorativa ha estado presente en la ciudad de Murcia a lo largo de la historia, y todavía hoy encontramos muestras vigentes, que nos lo confirman. Lejos de los grandes encargos de programas pictóricos, civiles y religiosos, que hasta el siglo XX eran habituales, nace un nuevo tipo de encargo, el particular y de ámbito privado, así como en el ámbito institucional. La temática desarrollada es variada, también se han utilizado diferentes tendencias artísticas, como la figuración, la abstracción, las formas cubistas e impresionistas, entre otras. En estas realizaciones decorativas y artísticas se han utilizado variadas técnicas pictóricas murales y soportes. Fueron muchos artistas los artífices de este tipo de decoraciones, algunos tenían en común las mismas inquietudes artísticas, llegando a formar por ello una serie de colectivos. Sabemos que pueden aparecer obras que desconocemos a día de hoy, pero hay que dejar claro la posibilidad de una fructífera expansión de esta investigación aquí presente Al cierre de este trabajo hemos seguido conociendo datos, como alguna autoría desconocida. Por ello esta Tesis Doctoral queda abierta a la investigación, con la intención de seguir investigando y catalogando este tipo de obras.

Among the many readings of this painter, I try to draw up a narrative reading of his work, taking into account the Jewish tradition in which both his biography and his artistic work were deeply involved. Once I have discussed this point in the first part of my doctoral thesis, I suggest the possibility of developing a hermeneutic narrative in painting, with the help of other contributions. Chagall is an artist who passes on and expresses experiences, recreates moments of his childhood, constantly expressing love for his hometown, Vitebsk; he narrates building and making fiction of images and pictorial metaphors / Dentro de las muchas lecturas de este pintor, intento hacer una lectura narrativa de su obra, teniendo en cuenta su integración en la tradición judía en cuya atmósfera pervive tanto su biografía como su producción artística. Una vez trabajado este primer espacio concreto de mi tesis, insinúo la posibilidad de elaborar con más ayudas y otras colaboraciones una hermenéutica narrativa en pintura. Chagall es un artista que transmite experiencias, recrea momentos de su infancia, trasmitiendo constantemente el amor a su pueblo natal, Vitebsk; narra construyendo y ficcionando imágenes y metáforas pictóricas

El objetivo fundamental de esta Tesis es describir y monitorizar el efecto de diversas concentraciones de ácido nítrico en la degradación del color de once pigmentos de uso común en obras de arte pictóricas. Así mismo se busca conocer cuál es el efecto de los parámetros tiempo de exposición y temperatura ambiental. Finalmente se efectúa una comparación entre la degradación del color inducida por ácido nítrico y la que provocan el ozono y el ambiente real urbano. El cambio de color de los pigmentos se valora de manera cuantitativa, cualitativa y gráfica, siguiendo el sistema CIELAB. Para la consecución de estos objetivos se han efectuado una serie de experimentos de laboratorio y ensayos de campo. En el laboratorio se han recreado diferentes condiciones ambientales controladas de exposición por medio de un sistema dinámico de exposición para el ácido nítrico y el ozono respectivamente. Los resultados experimentales muestran que todos los pigmentos expuestos al ácido nítrico, al ozono y al ambiente real urbano sufren variaciones en su color original en dependencia del tiempo durante el que las muestras están sometidas a la acción del ácido nítrico, la concentración del ácido nítrico y la temperatura ambiental. El cambio es diferente según la naturaleza de cada uno de los pigmentos, por lo que es razonable pensar que otros colorantes estrechamente relacionados con los de este estudio sean sensibles al ácido nítrico de una manera similar. / The main objective of this Thesis is to describe and detail the effect of different concentrations of nitric acid in the fading of eleven pigments commonly used in art works. Likewise the study try to know what is the effect of the parameters time of exposure and environmental temperature on fading. Finally we made a comparison between color degradation induced by nitric acid and which cause the ozone and the real urban environment. Fading is valued using the CIELAB system quantitatively, qualitatively and graphically. Different laboratory experiments and field trials have been carried on for the achievement of these objectives. In the laboratory, several controlled environmental conditions of exposure have been recreated ,by the use of a dynamic system of exposure to nitric acid and ozone respectively. Results show that all the pigments exposed to nitric acid, ozone and to a real urban environment suffer variations in its original color, depending on time during the samples are exposed to the action of nitric acid, concentration of nitric acid and temperature. Fading is different according to the nature of each pigment, so it is reasonable to think that other pigments closely related of the ones studied are sensitive to nitric acid in a similar way.

A problem of emotion and cognition is considered within a unified theory of cognition. There is a strong case for modern cognitive models to take arousal component of emotion into account because of its significant influence on performance (e.g. the inverted-U effect). Several hypotheses have been proposed to explain this effect, but they have not been integrated into cognitive architectures. Based on the analysis of the ACT-R (Anderson & Lebiere, 1998) cognitive architecture the mechanisms that can be used to model this effect are identified. Then a model of the classical Yerkes and Dodson experiment is introduced. The model matches the data by modifying several parameters, particularly noise and goal value in the conflict resolution strategy. Thus, the model supports the idea that the character of decision making changes for different arousal and motivational states. The effect of these changes on learning is analysed using information theory. In particular, randomness in behaviour due to a noise increase leads to a faster entropy reduction. Thus, noise can improve learning in the initial stage of problem exploration or upon changes in the environment. Furthermore, dynamic motivation can optimise the expenditure of effort. Therefore, emotion may play an important role in adaptation of cognitive processes. It is argued that the current conflict resolution mechanism in ACT-R does not explain the dynamics suggested by the model. A new theory and algorithm are proposed that use posterior estimation of expected costs. There are three main contributions of the thesis: 1) Ways of including the effects of emotion and motivation into cognitive models; 2) The analysis of the role of emotion in learning and intelligence; and 3) The introduction of a new machine learning algorithm suitable for applications not only in cognitive modelling, but in other areas of computer science.

Olive Mill Wastewater (OMW), by-product of oil industry, is a dark liquid with a characteristic fetid smell, bitter taste and bright appearance / having a high pollution potential, creating serious problems in countries producing olive oil. Azotobacter chroococcum as a Nitrogen-fixing bacteria can bioremediate OMW, by degrading its toxic constituents. With the help of this detoxification process OMW can be used as biofertilizer. In this study, the dynamics of growth and nitrogen fixation at different physiological conditions and nutrient requirements of A. chroococcum in chemically defined N-free medium was determined. These parameters were cultivation conditions such as pH, temperature and aeration and some additives such as inorganic salts, boric acid and nitrogen. Consequently, the maximum cell concentration were obtained when A. chroococcum was grown at neutral pH, 35&amp / #61616 / C, 150 rpm and in medium supplemented with manganese salt at 0.01% concentration. The maximum nitrogen fixation products were attained when A. chroococcum was grown under the same conditions except at pH 8. Further, bioremediation of OMW by A. chroococcum was examined. When A. chroococcum was cultivated in OMW containing basal medium at 10% OMW concentration, a cell density 12 times higher than in the OMW free medium was achieved. Also, it was found to have maximum increase in extracellular protein concentration (112 mg/l) at 10% OMW containing medium and maximum increase in ammonia concentration (9.05 mg/l) at 5% OMW containing medium.

Growth and survival of L. innocua and TAC in artificially inoculated Turkish White Cheese during manufacturing and storage periods, with respect to different level of contamination of L. innocua were investigated. Cheese products were manufactured by the short-set procedure in pilot-plant-sized vats, as in AO&Ccedil / dairy factory. Pasteurized cow&rsquo / s milk was inoculated with L. innocua for obtaining the initial loads of 3.84 and 7.12 log CFU/ml. Bacterial load of inoculated milk, whey, post-ripened curd and post-salted cheese was determined during processing at 20&plusmn / 5&ordm / C. Cheeses were stored in 16% saline solution at 4 &plusmn / 2&ordm / C for up to 45 days. Samples were taken from each treatment and analysed on 5, 10, 15, 20, 30 and 45 days. Total decrease of L. innocua in Turkish White Cheese with each inoculum dose was approximately 2 logs during the storage period. L. innocua values were also compared with TAC values. The results had shown that, if pasteurization is not as sufficient as to kill this bacteria in contaminated raw milk, or if there is post-process contamination, Listeria can survive during the manufacture and storage, although they decrease in number. Storage (ripening) period for consumption of cheeses should be at least 90 and 178 days, in low and high inoculum dose, respectively. Physico-chemical properties of cheese as pH, acidity, salt, fat, moisture contents during storage period were determined. Salt concentration, pH value and storage temperature had a cumulative bactericidal effect on microorganisms. In this respect, effect of implementing HACCP method on reducing the Listerial contamination of Turkish White Cheese was determined for checking the quality problems in a cheese plant and for directing the companies as a guide.