La tesis está conformada por tres papers, el primero titulado Some Strategic Aspects of Private Information: An Experimental Analysis, el segundo titulado Comportamiento Estratégico y Manipulabilidad en los Métodos de Preferencias Declaradas para la Valoración de Bienes sin Mercado. Tres Experimentos de Laboratorio, y el tercero titulado Mistakes and Reciprocity Promote Cooperation in Public Good Games: An agent-based Approach. El objetivo principal de la tesis es testar mediante herramientas experimentales y simulaciones las hipótesis de perfecta racionalidad y comportamiento estratégico en tres diferentes contextos. En el primero nos preocupamos por estudiar aspectos informacionales de juegos repetidos con información incompleta. El marco teórico es relativamente simple, un juego 2x2, con información incompleta que se repite infinitamente. Nos preguntamos si los jugadores que tienen información privada en la práctica toman ventaja de ello (comportamiento estratégico) y si los jugadores desinformados pueden adivinar el juego que están jugando cuando se les ha revelado información importante, tal como la teoría predice. En el segundo contexto, nos interesa testar el supuesto de manipulabilidad (strategy proffness) en los métodos de preferencias declaradas para la valoración de bienes sin mercado. Diseñamos tres experimentos de laboratorio para diferentes formatos de valoración de preferencias declaradas: un referéndum puro, un formato de valoración contingente y un conjunto de elección con tres alternativas. El tercero es un contexto en el que proponemos un modelo de evolución de la cooperación en bienes públicos, en ambientes en que agentes con diferentes grados de cooperación condicional actúan estratégicamente para decidir si cooperar o no. A diferencia de otros estudios donde el interés es comprender cómo emerge el altruismo o la reciprocidad, nosotros nos preocupamos por estudiar por qué la cooperación puede sobrevivir en esa clase de ambientes. / The thesis consists of three papers, the first entitled Some Strategic Aspects of Private Information: An Experimental Analysis, the second entitled Comportamiento Estratégico y Manipulabilidad en los Métodos de Preferencias Declaradas para la Valoración de Bienes sin Mercado. Tres Experimentos de Laboratorio, and the third entitled Mistakes and Reciprocity Promote Cooperation in Public Good Games: An agent-based Approach. The main objective of the thesis is to test, using experimental and simulation tools, the assumptions of perfect rationality and strategic behavior in three different contexts. In the first study we are concerned with informational aspects of repeated games with incomplete information. The theoretical framework is relatively simple, a 2x2 game with incomplete information that is infinitely repeated. We asked if players with private information, in practice, take advantage of it (strategic behavior), and if the uninformed players can guess the game they are playing when had been revealed important information, such as the theory predicts. In the second context, we want to test the assumption of manipulability (strategy proffness) in stated preference methods for valuing non-market goods. We designed three laboratory experiments for different formats of stated preferences: a pure referendum, a contingent valuation method and choice set with three alternatives. The third is a context in which we propose an evolution of cooperation model in public goods, in environments in which agents have different degrees of cooperation conditional and act strategically to deciding whether to cooperate or not. Unlike other studies where the interest is to understand how emerging altruism or reciprocity, we am interested in study why cooperation can survive in such environments.

En el trabajo se analizan las características estructurales básicas de las cooperativas bajo los postulados de la Teoría de la Agencia. Del análisis teórico y empírico se deducen una serie de deficiencias estructurales relacionadas con problemas de agencia. Se analizan los mecanismos de salvaguardia establecidos por estas entidades para intentar minorarlos, incorporando algunos nuevos que podrían ayudar algo más en su solución.

Urban wastewater treatment plants produce a variety of residuals during their operation, the typology of which are in function of the design of the treatment process. The problem aborded in the present thesis refers to the sludge produced as a result of the treatment. After the banning of disposal to continental and/or marine waters, established at the EU through Directive 91/271 CEE and then in Spain trough Royal Decree [RD 11/95] those sludges should be object, essentially after treatment, of controlled using or disposition. Previously to the using or disposition a previous treatment can be required, that could be organic (essentially composting with other amendments), drying or other physic-chemical treatment, between those last alkaline stabilization. Alkaline stabilization can accomplish on a single step reduction or elimination of pathogen vectors, smell elimination and a reduction in the putrefaction potential. Its base is the alteration of the physic-chemical characteristics of the environment of the sludge by addition of alkaline material. One of the processes of inertization, object of the analysis proposed in the present thesis, is the treatment realized trough addition of calcium oxide. Essentially it is a physic-chemical treatment trough which it is possible to obtain a dry product with the addition of calcium oxide (quicklime) to the urban wastewater sludge. The result of the chemical reactions and water evaporation is oriented to obtain a dry product (10% humidity) as powder and with a reduction of mass in relation to the original wastewater sludge of about 40%. The realized work have been developed over the basis of the analysis of the technical, economical and environmental feasibility of the proposed alternative, using though normalized methodology on each of the different concrete aspects that are developed. A very important part of the experimental work which validates the technology under study has been developed at pilot plant level. Additionally, the proposed management alternative of the sludge includes using the inertized sludge as a secondary raw material in Portland cement clínker production, having been developed a industrial pilot test to validate the theoretical hypothesis been established. The thesis has been developed in the core of task 6b of Project Sostaqua in program CENIT, promoted by the Centro para el Desarrollo Tecnológico e Industrial (CDTI). This had as an objective the creation of new knowledge to contribute to the development of a sustainable water life cycle. Being the sludge part of that cycle, task 6b has intended demonstrate the feasibility of the treatment with addition of alkaline agents, in this case with addition of calcium oxide. Over the basis of the obtained results it has been considered that the proposed process constitutes a feasible alternative to the management of the urban wastewater sludge. Considering that this management it is a difficult task to abroad, due to the technical difficulties implied, it should be convenient to diversify the alternatives in order to have backup treatment capacity in order to avoid the final disposition to landfill.

El present projecte de recerca pretén aportar evidencies empíriques que permetin conèixer millor el complex, i a vegades contradictori, debat entorn a com les companyies prenen les seves decisions d'endeutament. Per aquest motiu, en primer lloc s'ha realitzat un estudi bibliomètric sobre la recerca en economia financera, analitzant de manera detallada l'activitat científica que estudiava l'estructura de capital de l'empresa, així com la línia de recerca que més publicacions ha generat entre els anys 1995 i 2006.A partir del marc de referència proveït per l'estudi bibliomètric, s'ha analitzat l'impacte de les decisions de finançament, inversió i dividends sobre la creació de valor de les empreses. S'ha estudiat també els efectes que tenen sobre les decisions de finançament l'ús de diferents mètrics que medeixen el valor creat. Per això s'ha utilitzat una mostra de 205 empreses que pertanyen a l'índex S&P 500 entre els anys 1994 i 2004, i una anàlisi de dades de panell. Els resultats que s'han obtingut han permès concloure que les tres decisions financeres són rellevants en matèria de creació de valor. L'anàlisi realitzat ha considerat la presencia i absència de les oportunitats de creixement que presentaven cada una de les companyies. S'ha conclòs també que la influència de les decisions financeres varia en funció del mètric utilitzat per mesurar la creació de valor, i finalment s'ha presentat també el model basat en el market value added com aquell que recull millor la influència de les decisions financeres. La conclusió positiva de la influència de les decisions de finançament en matèria de creació de valor, ha motivat l'estudi de les dues principals teories explicatives de l'estructura de capital de l'empresa: teoria del trade-off i teoria de la jerarquització financera. Per realitzar aquest contrast s'ha utilitzat una mostra de 195 empreses del S&P 500 entre els anys 1997-2005 i una anàlisi de dades de panell. Els resultats obtinguts han permès concloure que les hipòtesis formulades per la teoria de la jerarquització financera troben una coincidència més gran, que no pas les formulades per la teoria del trade-off. Tot i això, la teoria de la jerarquització financera no té una capacitat explicativa plena al no poder aportar una explicació als resultats obtinguts per a algunes de les hipòtesis formulades.Per aquest motiu s'ha realitzar un apropament nou als plantejats fins ara a la literatura sobre l'estructura de capital de l'empresa, tractant de trobar un marc de referència que fos capaç d'explicar les decisions de finançament a través de les noves aportacions realitzades pel corporate governance. Aquesta disciplina fa un fort èmfasis en el paper que juguen els stakeholders en la manera de governar les companyies. A partir d'aquest marc conceptual, i de l'aportació de diferents publicacions que havien analitzat per separat de quina manera alguns stakeholders podien condicionar les decisions de finançament, s'ha presentat un nou acostament que pretén explicar les decisions de finançament a través de la influència dels stakeholders. Després d'analitzar una mostra de les 500 empreses europees més grans, pel que fa al volum de facturació, s'ha pogut contrastar positivament la influència dels directius, treballadors, competidors, clients i proveïdors, en les decisions de finançament. / El presente proyecto de investigación pretende aportar evidencias empíricas que permitan conocer mejor el complejo, y a veces contradictorio, debate en torno a cómo las compañías toman sus decisiones de endeudamiento. Por este motivo, en primer lugar se ha realizado un estudio bibliométrico sobre la investigación en economía financiera, analizando de manera pormenorizada la actividad científica que estudiaba la estructura de capital de la empresa así como la línea de investigación que más publicaciones ha generado entre los años 1995 y 2006.Tras establecer el marco de referencia provisto por el estudio bibliométrico, se ha analizado el impacto de las decisiones de financiación, inversión y dividendos sobre la creación de valor de las compañías. Se ha estudiado también los efectos que tienen sobre las decisiones financieras el uso de diferentes métricos que miden el valor creado. Para ello se ha utilizado una muestra de 205 empresas pertenecientes al índice S&P 500 entre los años 1994 y 2004 y un análisis de datos de panel. Los resultados obtenidos han permitido concluir que las tres decisiones financieras son relevantes en materia de creación de valor. Para ello se ha tenido en cuenta la presencia y ausencia de las oportunidades de crecimiento que presentaban cada una de las compañías. Se ha concluido también que la influencia de las decisiones financieras varía en función del métrico utilizado para medir la creación de valor, y finalmente se ha presentado el modelo basado en el market value added como aquel que recoge mejor la influencia de las decisiones financieras.La relevancia de las decisiones de financiación en materia de creación de valor ha conllevado el estudio de las dos principales teorías explicativas de la estructura de capital de la empresa: teoría del trade-off y teoría de la jerarquización financiera. Para ello se ha utilizado una muestra de 195 empresas del S&P 500 entre los años 1997 y 2005 y un análisis de datos de panel. Los resultados obtenidos han permitido concluir que las hipótesis formuladas por la teoría de la jerarquización financiera encuentran una mayor coincidencia con los resultados que las formuladas por la teoría del trade-off. Aún así, la teoría de la jerarquización no tiene una capacidad explicativa plena al no poder explicar los resultados obtenidos para todas las hipótesis planteadas.Por este motivo se ha buscado un acercamiento novedoso a la investigación de la estructura de capital, tratando de hallar un marco de referencia que explicara las decisiones de financiación a través de las nuevas aportaciones realizadas por el corporate governance. Esta disciplina hace un fuerte énfasis en el papel que los stakeholders desempeñan en la manera de gobernar las compañías. A partir de este marco conceptual, y la aportación de diferentes publicaciones que habían analizado por separado de qué manera algunos stakeholders podían condicionar las decisiones de financiación, se ha presentado una línea de investigación que pretende explicar las decisiones de financiación a través de la influencia de los stakeholders. Tras analizar una muestra de las 500 mayores empresas europeas, por volumen de ventas, se ha contrastado la influencia de los directivos, trabajadores, competidores, clientes y proveedores, en las decisiones de financiación. / This research project tries to contribute with empirical evidence in the complex debate of leverage decisions. First of all, we made a bibliometric study about Finance research between 1995 and 2006. After doing a general view of the main researched topics in finance, we focused on capital structureSecondly we present an empirical contrast among 205 companies of the S&P 500 between 1994 and 2004. This research is a study about the influence of the financial policies (investment, dividends and capital structure) on the value creation taking into account different value metrics. The obtained results allowed to conclude that these financial decisions are relevant on the matter of value creation. Our analysis take in to account the presence and absence of the growth opportunities of the companies studied. We also conclude that the influence of the financial decisions change in function of the metric used. After having considered different models base on several value metrics, we selected the model base on the Market Value Added as best collecting the influence of the financial decisions.Thirdly, we used a panel data analysis with a sample of 182 companies of the S&P 500 between 1997 and 2005 to compare two different financial theories on capital structure: Pecking order vs. trade-off. Our results show a better agreement with the pecking order hypothesis than the hypothesis formulated by the trade-off theory. However, some of our results cannot be explained by the pecking order theory.Finally, we present a new approach to the financing decisions based on the new contributions provided by the corporate governance. This new approach emphasizes the crucial role of the stakeholders in the corporate governance. Grounding on this conceptual framework and the existing literature that analyzes the independent effect of some of the stakeholders over the financing decisions, we present a new approach for considering the influence of the stakeholders altogether. After analyzing a sample of 500 European top selling companies, we conclude that the financing decisions are influenced by managers, workers, competitors, client and suppliers.

Il rachide è stato suddiviso in tre colonne da Denis: anteriore e centrale comprendono la metà anteriore del corpo vertebrale, la metà posteriore e l’inizio dei peduncoli, mentre la colonna posteriore comprende l’arco e i peduncoli stessi. In caso di resezione o lesione della colonna anteriore e media è indicata la ricostruzione. Diverse tecniche e materiali possono essere usati per ricostruire il corpo vertebrale. Innesti vascolarizzati, autograft, allograft sono stati usati, così come impianti sintetici di titanio o materiale plastico come il PEEK (Poly etere etere ketone). Tutti questi materiali hanno vantaggi e svantaggi in termini di proprietà intrinseche, resistenza meccanica, modulo di elasticità, possibilità di trasmissione malattie, capacità di fondersi con l’osso ospite o meno. Le soluzioni più usate sono le cage in titanio o carbonio, il PMMA ( Poli methil metacrilato), gli innesti ossei massivi. Si è effettuato uno studio di coorte retrospettivo paragonando due gruppi di pazienti oncologici spinali trattati da due chirurghi esperti in un centro di riferimento, con vertebrectomia e ricostruzione della colonna anteriore: un gruppo con cage in carbonio o titanio, l’altro gruppo con allograft massivo armato di innesto autoplastico o mesh in titanio. Si sono confrontati i risultati in termini di cifosi segmenterai evolutiva, fusione ossea e qualità di vita del paziente. Il gruppo delle cage in carbonio / titanio ha avuto risultati leggermente migliori dal punto di vista biomeccanico ma non statisticamente significativo, mentre dal punto di vista della qualità di vita i risultati sono stati migliori nel gruppo allograft. Non ci sono stati fallimenti meccanici della colonna anteriore in entrambi i gruppi, con un Fu tra 12 e 60 mesi. Si sono paragonati anche i costi delle due tecniche. In conclusione l’allogar è una tecnica sicura ed efficace, con proprietà meccaniche solide, soprattutto se armato con autograft o mesi in titanio. / According to Denis the spine can be subdivided in 3 columns: anterior and central made by the anterior half and posterior half of the vertebral body, and posterior column made by the pedicles and posterior arch. Reconstruction of large anterior and middle column defects is indicated in a number of pathological entities including tumor, infection, trauma and post traumatic deformity, usually after a previous partial or total vertebral body resection. Several substitutes and techniques are available for the functional restoration of the vertebral column. Vascularized bone transfers, autografts, allografts or xenografts have been used, as well as metal, plastic or ceramic implants. All of these bear potential advantages and drawbacks in terms of associated morbidity of graft harvesting, disease transmission, mechanical failure, implant incorporation and over all long term outcome. The most frequently used solutions are: PMMA, Titanium Mesh Cages, Carbon Fiber Stackable cages, Massive allografts. a retrospective cohort study has been done comparing two groups of oncologic spine patients treated by 2 surgeons with vertebrectomy and anterior reconstruction: one group with cages, the other with allograft. We have compared results in terms of post surgical kyphosis and its worsening in time, fusion of the graft, quality of life. Results have been slightly better in the cage group but with no statistical relevance. No mechanical failure of the anterior column in both groups with a FU range from 12 to 60 months. A cost comparison has also been made. In conclusion we have realized allograft are a safe and cheap alternative to carbon fiber cages, with strong mechanical properties above all if helped by small titanium cages or rib autograft inside.

No description available.

Specific aims The aim is to improve the treatment of the bone losses at the metacarpal bones level (both diaphysis and epiphysis) combining microsurgery, tissue engineering and biomaterials, so to minimize the donor side morbidity and optimize healing and outcomes. Methods Pre-operative controlateral X-ray or 3-D CT to allow custom-made HA scaffolds. Cement as temporary spacer in acute lesion and monitoring of infective risks. Treatment of the bone loss recurring to pre-fabricated or custom-made HA scaffolds, adding platelet gel or growth factor OP1. Stable synthesis. Control group with auto/omografts. Outcome indices: % of bone-union; finger TAM, Kapandji, DASH score; NMR and Scintigraphy at 180 days for revascularisation and bio-substitution of the scaffold. Preliminary results The authors just treated 6 patients, 4 males and 2 females, with an average age of 38.5 yrs, affected by segmental bone losses at the hand and wrist, recurring to pre-fabricated not vascularised scaffolds. In all cases the synthesis was performed with angular stability plates and a stable synthesis achieved. All patients have been controlled at a mean follow-up of 10.5 months (from 2 to 16 ). In all case but one the bone-scaffold osteo-integration was achieved at an average of 38 days at the hand, and 46 days at the wrist. The outcome studies, according to the DASH score, finger TAM, and Kapandji, were good and excellent in 5 cases, poor in one.

Reconstruction of bone is needed for high bone loss due to congenital deformities, trauma or neoplastic diseases. Commonly, orthopaedic surgical treatments are autologus or allogenic bone implant or prosthetic implant. A choice to the traditional approaches could be represented by tissue engineering that use cells (and/or their products) and innovative biomaterials to perform bone substitutes biologically active as an alternative to artificial devices. In the last years, there was a wide improvement in biology on stem cells potential research and in biomedical engineering through development of new biomaterials designed to resemble the physiological tissues. Tissue engineering strategies and smart materials aim together to stimulate in vivo bone regeneration. This approaches drive at restore not only structure integrity and/or function of the original tissue, but also to induce new tissue deposition in situ. An intelligent bone substitute is now designed like not only a scaffold but also as carrier of regeneration biomolecular signals. Biomimetics has helped to project new tissue engineered devices to simulate the physiological substrates architecture, such extracellular matrix (ECM), and molecular signals that drive the integration at the interface between pre-existing tissue and scaffold. Biomimetic strategies want to increase the material surface biological activity with physical modifications (topography) o chemical ones (adhesive peptides), to improve cell adhesion to material surface and possibly scaffold colonization. This study evaluated the effects of biomimetic modifications of surgical materials surface, as poly-caprolattone (PCL) and titanium on bone stem cells behaviour in a marrow experimental model in vitro. Two biomimetic strategies were analyzed; ione beam irradiation, that changes the surface roughness at the nanoscale, and surface functionalization with specific adhesive peptides or Self Assembled Monolayers (SAMs). These new concept could be a mean to improve the early (cell adhesion, spreading..) and late phases (osteoblast differentiation) of cell/substrate interactions.

No description available.

Controlled delivery of anticancer drugs through osteotropic nanoparticles (NP) is a novel approach for the adjuvant therapy of osteolytic bone metastases. Doxorubicin (DXR) is widely used in chemotherapy, although its activity is restricted by dose-dependent cardiotoxicity and marrow toxicity. However, its efficacy can be improved when specific targeting at the tumor site is obtained. The aim of this study was to obtain osteotropic biodegradable NP by nanoprecipitation of a copolymer between poly(D,L-lactide-co-glycolide) (PLGA) and an osteotropic bisphosphonate, sodium alendronate (ALE). NP were subsequently characterised for their chemical-physical properties, biocompatibility, and the ability to inhibit osteoclast-mediated bone resorption, and then loaded with DXR. The effectiveness of NP-loaded DXR was investigated through in vitro and in vivo experiments, and compared to that of free DXR. For the in vitro analysis, six human cell lines were used as a representative panel of bone tumors, including breast and renal adenocarcinoma, osteosarcoma and neuroblastoma. The in vitro uptake and the inhibition of tumor cell proliferation were verified. To analyse the in vivo activity of NP-loaded DXR, osteolytic bone metastases were induced through the intratibial inoculation in BALB/c-nu/nu mice of a human breast cancer cell line, followed by the intraperitoneal administration of the free or NP-loaded DXR. In vitro, aAll of the cell lines were able to uptake both free and NP-loaded drug, and their proliferation was inhibited up to 80% after incubation either with free or NP-loaded DXR. In addition, in vivo experiments showed that NP-loaded DXR were also able to reduce the incidence of bone metastases, not only in comparison with untreated mice, but also with free DXR-treated mice. In conclusion, this research demonstrated an improvement in the therapeutic effect of the antineoplastic drug DXR, when loaded to bone-targeted NP conjugated with ALE. Osteotropic PLGA-ALE NP are suitable to be loaded with DXR and offer as a valuable tool for a tissue specific treatment of skeletal metastases.