BS-SEM evaluation of the tisular interactions between cortical bone and calcium-phosphate covered titanium implants

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes

BS-SEM evaluation of the tisular interactions between cortical bone and calcium-phosphate covered titanium implants

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes

BS-SEM evaluation of the tisular interactions between cortical bone and calcium-phosphate covered titanium implants

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes

Growth and magnetic characterization of Co nanoparticles obtained by femtosecond pulsed laser deposition.

We present a detailed study on the morphology and magnetic properties of Co nanostructures deposited onto oxidized Si substrates by femtosecond pulsed laser deposition. Generally, Co disks of nanometric dimensions are obtained just above the ablation threshold, with a size distribution characterized by an increasingly larger number of disks as their size diminishes, and with a maximum disk size that depends on the laser power density. In Au/Co/Au structures, in-plane magnetic anisotropy is observed in all cases, with no indication of superparamagnetism regardless of the amount of material or the laser power density. Magnetic force microscopy observations show coexistence of single-domain and vortex states for the magnetic domain structure of the disks. Superconducting quantum interference device magnetometry and x-ray magnetic circular dichroism measurements point to saturation magnetization values lower than the bulk, probably due to partial oxidation of the Co resulting from incomplete coverage by the Au capping layer.

On bilateral agreements: just a matter of matching

This paper aims at assessing the importance of the initial technological endowments when firms decide to establish a technological agreement. We propose a Bertrand duopoly model where firms evaluate the advantages they can get from the agreement according to its length. Allowing them to exploit a learning process, we depict a strict connection between the starting point and the final result. Moreover, as far as learning is evaluated as an iterative process, the set of initial conditions that lead to successful ventures switches from a continuum of values to a Cantor set.

Interactions between product and labour market reforms

Labour market reforms face very often opposition from the employed workers, because it normally reduces their wages. Also product market regulations are regularly biased towards too much benefitting the firms. As a result there remain many frictions in both the labour and product markets that hinder an optimal functioning of the economy. These issues have recently received a lot of attention in the economics literature and scholars have been looking for politically viable reforms in both markets. However, despite its potential importance, there has been done virtually no research on the interaction between reforms in product and labour markets. We find that when combining reforms, the opposition for reforms decreases considerably. This is because there exist complementarities and the gains in total welfare can be more evenly distributed over the interest groups. Moreover, the interaction of reforms offers a way out for the so-called 'sclerosis' effect.

Empleo de óptica adaptativa y fluorescencia en un oftalmoscopio laser de barrido para el registro de células

Estudio elaborado a partir de una estancia en la Universidad de Rochester, Estados Unidos, de octubre del 2006 a enero del 2007. La estancia realizada en la Universidad de Rochester estuvo orientada al aprendizaje en profundidad del oftalmoscopio láser de barrido. El oftalmoscopio láser de barrido emplea una técnica confocal con la finalidad de visualizar diferentes estructuras retinianas en seres vivos. El instrumento diseñado y desarrollado en el Centro de Ciencias de la Visión incorpora un sistema de óptica adaptativa y fluorescencia. La óptica adaptativa aplicada en este oftalmoscopio tiene como objetivo corregir las aberraciones existentes en el ojo y así permitir observar detalles de la retina que de otra forma se verían emborronados. De esta forma se consigue alcanzar valores de resolución muy cercanos a los impuestos por difracción. Por otro lado el uso de fluorescencia tiene por objetivo el permitir la visualización de células y estructuras que, de no ser teñidas, son transparentes a la luz y visible. Esta técnica se ha estado utilizando principalmente en primates y ratas, aunque actualmente también se están llevando a cabo medidas de células de epitelio pigmentario en seres humanos ya que el pigmento contenido en estas células permite la aplicación de la fluorescencia sin necesidad de utilizar tinción.

MB-MDR: Model-Based Multifactor Dimensionality Reduction for detecting interactions in high-dimensional genomic data

L’anàlisi de l’efecte dels gens i els factors ambientals en el desenvolupament de malalties complexes és un gran repte estadístic i computacional. Entre les diverses metodologies de mineria de dades que s’han proposat per a l’anàlisi d’interaccions una de les més populars és el mètode Multifactor Dimensionality Reduction, MDR, (Ritchie i al. 2001). L’estratègia d’aquest mètode és reduir la dimensió multifactorial a u mitjançant l’agrupació dels diferents genotips en dos grups de risc: alt i baix. Tot i la seva utilitat demostrada, el mètode MDR té alguns inconvenients entre els quals l’agrupació excessiva de genotips pot fer que algunes interaccions importants no siguin detectades i que no permet ajustar per efectes principals ni per variables confusores. En aquest article il•lustrem les limitacions de l’estratègia MDR i d’altres aproximacions no paramètriques i demostrem la conveniència d’utilitzar metodologies parametriques per analitzar interaccions en estudis cas-control on es requereix l’ajust per variables confusores i per efectes principals. Proposem una nova metodologia, una versió paramètrica del mètode MDR, que anomenem Model-Based Multifactor Dimensionality Reduction (MB-MDR). La metodologia proposada té com a objectiu la identificació de genotips específics que estiguin associats a la malaltia i permet ajustar per efectes marginals i variables confusores. La nova metodologia s’il•lustra amb dades de l’Estudi Espanyol de Cancer de Bufeta.

Terrestrial laser scanning for landslides deformation monitoring

Within last few years a new type of instruments called Terrestrial Laser Scanners (TLS) entered to the commercial market. These devices brought a possibility to obtain completely new type of spatial, three dimensional data describing the object of interest. TLS instruments are generating a type of data that needs a special treatment. Appearance of this technique made possible to monitor deformations of very large objects, like investigated here landslides, with new quality level. This change is visible especially with relation to the size and number of the details that can be observed with this new method. Taking into account this context presented here work is oriented on recognition and characterization of raw data received from the TLS instruments as well as processing phases, tools and techniques to do them. Main objective are definition and recognition of the problems related with usage of the TLS data, characterization of the quality single point generated by TLS, description and investigation of the TLS processing approach for landslides deformation measurements allowing to obtain 3D deformation characteristic and finally validation of the obtained results. The above objectives are based on the bibliography studies and research work followed by several experiments that will prove the conclusions.

The determinants of university patenting: Do incentives matter?

In recent years various studies have examined the factors that may explain academic patents. Existing analyses have also underlined the substantial differences to be found in European countries in the institutional framework that defines property rights for academic patents. The objective of this study is to contribute to the empirical literature on the factors explaining academic patents and to determine whether the incentives that universities offer researchers contribute towards explaining the differences in academic patenting activity. The results of the econometric analysis for the Spanish universities point towards the conclusion that the principal factor determining the patents is funding of R&D while royalty incentives to researchers do not appear to be significant.

Disentangling the Housing Satisfaction Puzzle: Does Homeownership Really Matter?

There is a general consensus that homeownership has beneficial effects for both individuals and society in many outcomes. However, research regarding the effect of homeownership on individuals' subjective well-being remains inconclusive. In this paper, for the first time, we provide empirical evidence for the link between homeownership and housing satisfaction using panel data. We use the eight waves of the European Community Household Panel (ECHP) covering the period 1994-2001. We observe that renters who become homeowners not only experience a significant increase in housing satisfaction, but also after changing their tenure status, they obtain a different utility from the same housing context. This evidence might provide support to the hypothesis that a share of the differences in the perceived utility derived from housing can be attributed to (un)fulfilled expectations or aspirations regarding homeownership. Keywords: Housing satisfaction, subjective well-being, homeownership, fixed-effects, housing aspirations JEL classification: D1, R2.

Narrating urban entrepreneurship: a matter of imagineering?

The battle between cities with regard to their creative possibilities has evolved into a process of multiplying ever-new images and variegated stories of urban attractiveness and success. Engineering “cool” images and “hot” stories about one’s city is now a central endeavor in the narratives of urban policy-making that center more and more on the idea of the entrepreneurial city. The making of an entrepreneurial image is enacted through various narrative genres that lie somewhere between place making and place marketing, between branding and boosting, between restoration and revanchism, between iconic architecture and mega-spectacle. This “imagineering” is not only part of the way cities try to (re)present themselves as entrepreneurial to various audiences through a real “image inflation” (Zukin, 2008, p. xii) but is 1 Forthcoming in: B. Lange,.A. Kalandides, B. Stoeber, I. Wellmann (Hrsg.) (2009): Governance der Kreativwirtschaft. Diagnosen und Handlungsoptionen. Transcript-Verlag, Bielefeld. 2 also inscribed in the various ways urban creativity and entrepreneurship can be studied, researched and imagined. In this chapter we aim to differentiate the political narratives of the entrepreneurial city as we emphasize the need to understand the politics of narration and make a plea for critical reflexivity in our forms of researching and theorizing. We will thus try to investigate how the politics of narration is intertwined with the narration of political concepts and will argue that the narrating of urban entrepreneurship can raise very different images and discourses of city life beyond those that are currently engineered. We will distinguish between a grand narrative, a counter-narrative, and an assemblage of more ambivalent little narratives, which we call prosaic narration. While the distinction between these three types might be seen as a bit too simple and “straight”, we believe that by juxtaposing these different forms of narration and alternating between them, we can help problematize the engineering of the city as entrepreneurial and imagine alternative views both of city life and of what is understood as its creativity.