High-performance switching architectures for optical networks

The need for high bandwidth, due to the explosion of new multi\-media-oriented IP-based services, as well as increasing broadband access requirements is leading to the need of flexible and highly reconfigurable optical networks. While transmission bandwidth does not represent a limit due to the huge bandwidth provided by optical fibers and Dense Wavelength Division Multiplexing (DWDM) technology, the electronic switching nodes in the core of the network represent the bottleneck in terms of speed and capacity for the overall network. For this reason DWDM technology must be exploited not only for data transport but also for switching operations. In this Ph.D. thesis solutions for photonic packet switches, a flexible alternative with respect to circuit-switched optical networks are proposed. In particular solutions based on devices and components that are expected to mature in the near future are proposed, with the aim to limit the employment of complex components. The work presented here is the result of part of the research activities performed by the Networks Research Group at the Department of Electronics, Computer Science and Systems (DEIS) of the University of Bologna, Italy. In particular, the work on optical packet switching has been carried on within three relevant research projects: the e-Photon/ONe and e-Photon/ONe+ projects, funded by the European Union in the Sixth Framework Programme, and the national project OSATE funded by the Italian Ministry of Education, University and Scientific Research. The rest of the work is organized as follows. Chapter 1 gives a brief introduction to network context and contention resolution in photonic packet switches. Chapter 2 presents different strategies for contention resolution in wavelength domain. Chapter 3 illustrates a possible implementation of one of the schemes proposed in chapter 2. Then, chapter 4 presents multi-fiber switches, which employ jointly wavelength and space domains to solve contention. Chapter 5 shows buffered switches, to solve contention in time domain besides wavelength domain. Finally chapter 6 presents a cost model to compare different switch architectures in terms of cost.

Percorsi di gender performance: fotografia tra arte e moda dagli anni Novanta ad oggi

My project explores and compares different forms of gender performance in contemporary art and visual culture according to a perspective centered on photography. Thanks to its attesting power this medium can work as a ready-made. In fact during the 20th century it played a key role in the cultural emancipation of the body which (using a Michel Foucault’s expression) has now become «the zero point of the world». Through performance the body proves to be a living material of expression and communication while photography ensures the recording of any ephemeral event that happens in time and space. My questioning approach considers the gender constructed imagery from the 1990s to the present in order to investigate how photography’s strong aura of realism promotes and allows fantasies of transformation. The contemporary fascination with gender (especially for art and fashion) represents a crucial issue in the global context of postmodernity and is manifested in a variety of visual media, from photography to video and film. Moreover the internet along with its digital transmission of images has deeply affected our world (from culture to everyday life) leading to a postmodern preference for performativity over the more traditional and linear forms of narrativity. As a consequence individual borders get redefined by the skin itself which (dissected through instant vision) turns into a ductile material of mutation and hybridation in the service of identity. My critical assumptions are taken from the most relevant changes occurred in philosophy during the last two decades as a result of the contributions by Jacques Lacan, Michel Foucault, Jacques Derrida, Gilles Deleuze who developed a cross-disciplinary and comparative approach to interpret the crisis of modernity. They have profoundly influenced feminist studies so that the category of gender has been reassessed in contrast with sex (as a biological connotation) and in relation to history, culture, society. The ideal starting point of my research is the year 1990. I chose it as the approximate historical moment when the intersection of race, class and gender were placed at the forefront of international artistic production concerned with identity, diversity and globalization. Such issues had been explored throughout the 1970s but it was only from the mid-1980s onward that they began to be articulated more consistently. Published in 1990, the book "Gender trouble: feminism and the subversion of identity" by Judith Butler marked an important breakthrough by linking gender to performance as well as investigating the intricate connections between theory and practice, embodiment and representation. It inspired subsequent research in a variety of disciplines, art history included. In the same year Teresa de Lauretis launched the definition of queer theory to challenge the academic perspective in gay and lesbian studies. In the meantime the rise of Third Wave Feminism in the US introduced a racially and sexually inclusive vision over the global situation in order to reflect on subjectivity, new technologies and popular culture in connection with gender representation. These conceptual tools have enabled prolific readings of contemporary cultural production whether fine arts or mass media. After discussing the appropriate framework of my project and taking into account the postmodern globalization of the visual, I have turned to photography to map gender representation both in art and in fashion. Therefore I have been creating an archive of images around specific topics. I decided to include fashion photography because in the 1990s this genre moved away from the paradigm of an idealized and classical beauty toward a new vernacular allied with lifestyles, art practices, pop and youth culture; as one might expect the dominant narrative modes in fashion photography are now mainly influenced by cinema and snapshot. These strategies originate story lines and interrupted narratives using models’ performance to convey a particular imagery where identity issues emerge as an essential part of fashion spectacle. Focusing on the intersections of gender identities with socially and culturally produced identities, my approach intends to underline how the fashion world has turned to current trends in art photography and in some case turned to the artists themselves. The growing fluidity of the categories that distinguish art from fashion photography represents a particularly fruitful moment of visual exchange. Varying over time the dialogue between these two fields has always been vital; nowadays it can be studied as a result of this close relationship between contemporary art world and consumer culture. Due to the saturation of postmodern imagery the feedback between art and fashion has become much more immediate and then increasingly significant for anyone who wants to investigate the construction of gender identity through performance. In addition to that a lot of magazines founded in the 1990s bridged the worlds of art and fashion because some of their designers and even editors were art-school graduates encouraging innovation. The inclusion of art within such magazines aimed at validating them as a form of art in themselves supporting a dynamic intersection for music, fashion, design and youth culture: an intersection that also contributed to create and spread different gender stereotypes. This general interest in fashion produced many exhibitions of and about fashion itself at major international venues such as the Victoria and Albert Museum in London, the Metropolitan Museum of Art and the Solomon R. Guggenheim Museum in New York. Since then this celebrated success of fashion has been regarded as a typical element of postmodern culture. Owing to that I have also based my analysis on some important exhibitions dealing with gender performance like "Féminin-Masculin" at the Centre Pompidou of Paris (1995), "Rrose is a Rrose is a Rrose. Gender performance in photography" at the Solomon R. Guggenheim Museum of New York (1997), "Global Feminisms" at the Brooklyn Museum (2007), "Female Trouble" at the Pinakothek der Moderne in München together with the workshops dedicated to "Performance: gender and identity" in June 2005 at the Tate Modern of London. Since 2003 in Italy we have had Gender Bender - an international festival held annually in Bologna - to explore the gender imagery stemming from contemporary culture. In few days this festival offers a series of events ranging from visual arts, performance, cinema, literature to conferences and music. Being aware that any method of research is neither race nor gender neutral I have traced these critical paths to question gender identity in a multicultural perspective taking account of the political implications too. In fact, if visibility may be equated with exposure, we can also read these images as points of intersection of visibility with social power. Since gender assignations rely so heavily on the visual, the postmodern dismantling of gender certainty through performance has wide-ranging effects that need to be analyzed. In some sense this practice can even contest the dominance of visual within postmodernism. My visual map in contemporary art and fashion photography includes artists like Nan Goldin, Cindy Sherman, Hellen van Meene, Rineke Dijkstra, Ed Templeton, Ryan McGinley, Anne Daems, Miwa Yanagi, Tracey Moffat, Catherine Opie, Tomoko Sawada, Vanessa Beecroft, Yasumasa Morimura, Collier Schorr among others.

An Integrated Transmission-Media Noise Calibration Software For Deep-Space Radio Science Experiments

The thesis describes the implementation of a calibration, format-translation and data conditioning software for radiometric tracking data of deep-space spacecraft. All of the available propagation-media noise rejection techniques available as features in the code are covered in their mathematical formulations, performance and software implementations. Some techniques are retrieved from literature and current state of the art, while other algorithms have been conceived ex novo. All of the three typical deep-space refractive environments (solar plasma, ionosphere, troposphere) are dealt with by employing specific subroutines. Specific attention has been reserved to the GNSS-based tropospheric path delay calibration subroutine, since it is the most bulky module of the software suite, in terms of both the sheer number of lines of code, and development time. The software is currently in its final stage of development and once completed will serve as a pre-processing stage for orbit determination codes. Calibration of transmission-media noise sources in radiometric observables proved to be an essential operation to be performed of radiometric data in order to meet the more and more demanding error budget requirements of modern deep-space missions. A completely autonomous and all-around propagation-media calibration software is a novelty in orbit determination, although standalone codes are currently employed by ESA and NASA. The described S/W is planned to be compatible with the current standards for tropospheric noise calibration used by both these agencies like the AMC, TSAC and ESA IFMS weather data, and it natively works with the Tracking Data Message file format (TDM) adopted by CCSDS as standard aimed to promote and simplify inter-agency collaboration.

Optimal beam forming for laser beam propagation through random media

Focusing optical beams on a target through random propagation media is very important in many applications such as free space optical communica- tions and laser weapons. Random media effects such as beam spread and scintillation can degrade the optical system's performance severely. Compensation schemes are needed in these applications to overcome these random media effcts. In this research, we investigated the optimal beams for two different optimization criteria: one is to maximize the concentrated received intensity and the other is to minimize the scintillation index at the target plane. In the study of the optimal beam to maximize the weighted integrated intensity, we derive a similarity relationship between pupil-plane phase screen and extended Huygens-Fresnel model, and demonstrate the limited utility of maximizing the average integrated intensity. In the study ofthe optimal beam to minimize the scintillation index, we derive the first- and second-order moments for the integrated intensity of multiple coherent modes. Hermite-Gaussian and Laguerre-Gaussian modes are used as the coherent modes to synthesize an optimal partially coherent beam. The optimal beams demonstrate evident reduction of scintillation index, and prove to be insensitive to the aperture averaging effect.

Characterization Of Porous Media In Proton Exchange Membrane Fuel Cell Based on Percolation Studies

Water management in the porous media of proton exchange membrane (PEM) fuel cells, catalyst layer and porous transport layers (PTL) is confronted by two issues, flooding and dry out, both of which result in improper functioning of the fuel cell and lead to poor performance and degradation. The data that has been reported about water percolation and wettability within a fuel cell catalyst layer is limited to porosimetry. A new method and apparatus for measuring the percolation pressure in the catalyst layer has been developed. The experimental setup is similar to a Hele-Shaw experiment where samples are compressed and a fluid is injected into the sample. Pressure-Wetted Volume plots as well as Permeability plots for the catalyst layers were generated from the percolation testing. PTL samples were also characterizes using a Hele-Shaw method. Characterization for the PTLs was completed for the three states: new, conditioned and aged. This is represented in a Ce-t* plots, which show a large offset between new and aged samples.

Enhancing IEEE 802.11 Energy Efficiency for Continuous Media Applications

This paper proposes the Optimized Power save Algorithm for continuous Media Applications (OPAMA) to improve end-user device energy efficiency. OPAMA enhances the standard legacy Power Save Mode (PSM) of IEEE 802.11 by taking into consideration application specific requirements combined with data aggregation techniques. By establishing a balanced cost/benefit tradeoff between performance and energy consumption, OPAMA is able to improve energy efficiency, while keeping the end-user experience at a desired level. OPAMA was assessed in the OMNeT++ simulator using real traces of variable bitrate video streaming applications. The results showed the capability to enhance energy efficiency, achieving savings up to 44% when compared with the IEEE 802.11 legacy PSM.

An IEEE 802.11 energy efficient mechanism for continuous media applications

The widespread deployment of wireless mobile communications enables an almost permanent usage of portable devices, which imposes high demands on the battery of these devices. Indeed, battery lifetime is becoming one the most critical factors on the end-users satisfaction when using wireless communications. In this work, the optimized power save algorithm for continuous media applications (OPAMA) is proposed, aiming at enhancing the energy efficiency on end-users devices. By combining the application specific requirements with data aggregation techniques, {OPAMA} improves the standard {IEEE} 802.11 legacy Power Save Mode (PSM) performance. The algorithm uses the feedback on the end-user expected quality to establish a proper tradeoff between energy consumption and application performance. {OPAMA} was assessed in the OMNeT++ simulator, using real traces of variable bitrate video streaming applications, and in a real testbed employing a novel methodology intended to perform an accurate evaluation concerning video Quality of Experience (QoE) perceived by the end-users. The results revealed the {OPAMA} capability to enhance energy efficiency without degrading the end-user observed QoE, achieving savings up to 44 when compared with the {IEEE} 802.11 legacy PSM.

Can you see me thinking (about my answers)? Using eye-tracking to illuminate developmental differences in monitoring and control skills and their relation to performance

This study focuses on relations between 7- and 9-year-old children’s and adults’ metacognitive monitoring and control processes. In addition to explicit confidence judgments (CJ), data for participants’ control behavior during learning and recall as well as implicit CJs were collected with an eye-tracking device (Tobii 1750). Results revealed developmental progression in both accuracy of implicit and explicit monitoring across age groups. In addition, efficiency of learning and recall strategies increases with age, as older participants allocate more fixation time to critical information and less time to peripheral or potentially interfering information. Correlational analyses, recall performance, metacognitive monitoring, and controlling indicate significant interrelations between all of these measures, with varying patterns of correlations within age groups. Results are discussed in regard to the intricate relationship between monitoring and recall and their relation to performance.

Identifying yeats belonging to the Brettanomyces/Dekkera genera through the use of selective-differential media

The purpose of this work was to compare and optimise different selective and differential media to aid in isolating spoilage yeasts belonging to the Brettanomyces/Dekkera genera. Growth media containing selective and differential factors were employed. These were inoculated with strains of yeast representing Spanish oenological microbiota. Lastly, some of these isolation media were successfully applied in 24 types of wine with a high ethylphenol content, all of which were from the Haro Oenological Station (La Rioja, Spain). p-coumaric acid was determined using High performance liquid chromatography-photodiode-array detection-electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS); 4-ethylphenol by using Solid phase micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS); and the rest of the analysis was carried out using official OIV methodology. Actidione is the most effective selective factor for isolating Brettanomyces/Dekkera yeast genera. Other secondary selective factors (selective carbon sources, sorbic acid and ethanol as a microbicide agent) may be used successfully to eliminate potential false positivities; however, they slow growth and delay the time to obtain results.

Factores nutricionales que influyen sobre las variables productivas y el desarrollo del tracto gastrointestinal en pollitas comerciales rubias = Nutritional factors affecting productive performance and gastrointestinal tract traits in commercial brown-egg laying pullets

El objetivo general de esta Tesis doctoral fue estudiar la influencia de diversos factores nutricionales sobre los parámetros productivos y el desarrollo del tracto digestivo de pollitas rubias destinadas a la producción de huevos comerciales. Para alcanzar este objetivo se realizaron tres experimentos donde se estudió el cereal principal, el tamaño de partícula del cereal y el nivel de energía y la presentación de los piensos. En el experimento 1 se estudió la influencia del cereal (piensos con enzimas) y la presentación del pienso sobre los parámetros productivos y las características del tracto digestivo en 576 pollitas rubias de 1 a 120 d de edad. De 1 a 45 d de la edad, se utilizaron 4 piensos experimentales organizados de forma factorial con 2 cereales al 50% de inclusión (maíz vs. trigo) y 2 presentaciones del pienso (harina vs. gránulo de 2- mm de diámetro). Cada tratamiento se replicó 6 veces (24 pollitas por réplica). De 46 a 120 d de edad todas las dietas (maíz o trigo) se ofrecieron en harina y por tanto, la única diferencia entre tratamientos fue el cereal utilizado. De 1 a 120 d de edad, las pollitas que recibieron los piensos basados en maíz tuvieron una ganancia de peso vivo (PV) superior (P < 0,05) que las que recibieron los piensos basados en trigo, pero el índice de conversión (IC) fue similar para ambos grupos. De 1 a 45 d de edad, las pollitas alimentadas con gránulo consumieron más pienso (P < 0,001) y tuvieron una ganancia de peso superior (P < 0,001) que las pollitas alimentadas con harina. Gran parte de los efectos beneficiosos de la granulación sobre los parámetros productivos se mantuvieron al final de la prueba (120 d de edad). A los 45 d de edad, el peso relativo de la molleja (PR; g/kg PV) fue superior (P < 0,01) en pollitas alimentadas con maíz que en pollitas alimentadas con trigo. La alimentación en gránulo redujo el PR del tracto gastro intestinal (TGI) y de la molleja (P < 0,001), así como la longitud relativa (LR; cm/kg PV) del intestino delgado (P< 0.01) a ambas edades (45 y 120 d de edad). El tipo de cereal utilizado no afectó al pH del contenido de la molleja a 120 d de edad pero fué inferior (P < 0,01) en las pollitas que recibieron el pienso en harina de 1 a 45 d de la edad que en las que recibieron el pienso en gránulo. Se concluye que el trigo puede substituir al maíz en piensos para pollitas si se acepta una ligera reducción en la ganancia de peso. Asímismo, la alimentación en gránulo de 1 a 45 d de edad aumentó la ganancia de peso a esta edad y al final de la prueba, así como el pH de la molleja a 120 d de edad. La presentación del pienso en gránulo redujo el PR de la molleja y la LR del TGI a 120 d de edad. En el experimento 2 se utilizaron un total de 864 pollitas rubias Hy-Line de 1 d de edad para estudiar la influencia del cereal de la dieta (500 g de maíz o trigo/kg) y el tamaño de partícula del mismo (molienda con molino de martillos con un diámetro de criba de 6, 8, o 10-mm) sobre los parámetros productivos y las características del TGI de 1 a 120 d de edad. Cada uno de los 6 tratamientos se replicó 6 veces (24 pollitas por réplica). De 1 a 45 d de edad, la ganancia de PV aumentó (P< 0,001) y el IC se mejoró (P < 0,05) al reducir el tamaño de partícula del cereal, pero no se observaron diferencias en el periodo crecimiento de 45 a 120 d de edad. A los 45 d de vida, las pollitas alimentadas con maíz tendieron (P < 0,10) a tener un mayor PR del TGI y del proventrículo y una mayor LR del intestino delgado que las pollitas alimentadas con trigo. Asímismo, el PR del TGI a esta edad, aumentó (P < 0,05) a medida que aumentaba el tamaño de partícula del cereal utilizado. A los 120 d de edad, el tratamiento no afectó el PR de ninguno de los órganos del TGI ni al pH de la molleja. Sin embargo, la LR del intestino delgado fue superior (P < 0,05) para las pollitas alimentadas con trigo que para las pollitas alimentadas con maíz. La LR del TGI se redujó (P < 0,05) al aumentar el tamaño de partícula del cereal. Se concluye que el trigo puede incluirse 500 g/kg en piensos de pollitas de 1 a 120 días de edad y que el tamaño de partícula de los cereales afecta el crecimiento de las pollitas durante los primeros 45 d de vida, pero no después. Por lo tanto, se recomienda moler el cereal utilizado al inicio del período de recría (1 a 45 d de edad) con una criba de diámetro igual o inferior a 8 mm. En el experimento 3 se utilizaron un total de 1.152 pollitas rubias Hy-Line de 1 d de edad para estudiar la influencia del nivel de energía de la dieta y la presentación del pienso sobre la productividad y las características del TGI. De 1 a 45 d de edad se utilizaron 6 piensos organizados de forma factorial con 3 concentraciones energéticas (baja: 11,44 MJ; media: 12,05 MJ y alta: 12,66 MJ/kg) y 2 presentaciones del pienso (harina vs. gránulo). De 45 a 120 d todos los piensos experimentales se suministraron en forma de harina y por tanto, la única diferencia entre tratamientos fue el nivel de EMAn utilizado. Cada uno de los 6 tratamientos se replicó 8 veces y la unidad experimental fue la jaula con 24 pollitas. De 1 a 120 d de edad, la ganancia de PV y el IC mejoraron a medida que aumentó la EMAn del pienso (P < 0,001). Las pollitas alimentadas con gránulo de 1 a 45 d de edad comieron mas y tuvieron una ganancia de peso superior (P < 0,001) que las alimentadas con harina. En el global de la prueba, la ganancia de PV fue mayor (P < 0,01) para las pollitas alimentadas con piensos en gránulo. A los 45 d de edad, el PR de todos los segmentos del TGI estudiados fue inferior para las pollitas alimentadas con piensos de alta energía que para las pollitas alimentadas con piensos de media o baja energía. A 120 d de edad, el PR de la molleja fue superior (P < 0,01) para las pollitas alimentadas con piensos de baja energía que con los otros piensos. Sin embargo, la LR del TGI no se vió afectada por el nivel de energía de los piensos. A los 45 d de edad, la alimentación con gránulo redujo el PR del proventrículo (P < 0,05), de la molleja (P < 0,001) y del TGI (P < 0.001), así como la LR del intestino delgado (P < 0,05) y de los ciegos (P < 0,001). A pesar de que las pollitas solo recibieron los piensos en gránulo durante los primeros 45 d de vida, la alimentación con gránulos redujo el PR de la molleja y del proventrículo a 120 d de edad. Se concluye que la alimentación con gránulos durante los primeros 45 d de vida mejora el consumo de pienso y el PV de las pollitas a 120 d de edad. Un aumento del nivel de energía de la dieta de 12,0 a 12,7 MJ/kg mejora los parámetros productivos de 1 a 120 d de edad pero reduce el tamaño del proventrículo y de la molleja. En base de estos resultados concluimos que maíz y trigo con enzimas pueden utilizarse indistintamente en piensos para pollitas de 1 a 120 d de edad con sólo una ligera disminución del PV final con trigo. La granulación y la reducción del tamaño de partícula del cereal del pienso de primera edad (1 a 45 d de vida) y el uso de piensos de alta densidad energética, mejoran los PV a 120 d de edad. Por lo tanto, es recomendable moler los cereales con cribas de no más de 8-mm de diámetro. También, la granulación del pienso y el uso de piensos de alta energía (pobres en fibra bruta) pueden reducir el desarrollo del TGI especialmente de la molleja, lo que puede perjudicar el consumo posterior de pienso durante el inicio del ciclo de puesta. ABSTRACT The general objective of this Thesis was to study the effect of different nutritional factors on productive performance and the development of the gastrointestinal tract (GIT) of commercial brown egg-laying pullets from 1 to 120 d of age. In this respect, the influence of type and particle size of the cereal, and feed form, and energy content of the die,t were studied in 3 experiments. In experiment 1, the influence of the main cereal and feed form of the diet on performance and GIT traits was studied in 576 brown-egg laying pullets from 1 to 120 d of age. From 1 to 45 d of age, 4 diets arranged factorially with 2 cereals (maize vs. wheat) and 2 feed forms (mash vs. pellets) were used. Each treatment was replicated 6 times (24 pullets per replicate). From 46 to 120 d of age, all diets were offered in mash form and therefore, the only difference among diets was the cereal used. Cumulatively, pullets fed the maize diets had higher body weight (BW) gain (P< 0.05) but similar feed conversion ratio (FCR) than pullets fed the wheat diets. From 1 to 45 d of age, pullets fed pellets consumed more feed (P < 0.001) and had higher BW gain (P < 0.001) than pullets fed mash. Most of the beneficial effects of pelleting on productive performance of the birds were still evident at 120 d of age. At 45 d of age, gizzard relative weight (RW; g/kg BW) was higher (P < 0.01) in pullets fed maize than in pullets fed wheat. Feeding pellets reduced the RW of the GIT and the gizzard (P < 0.001) as well as the relative length (RL; cm/kg BW) of the small intestine (SI, P < 0.01) at both ages. The pH of the gizzard contents at 120 d of age was not affected by the main cereal of the diet, but was lower in pullets fed mash from 1 to 45 d of age (P < 0.01) than in pullets fed pellets. We conclude that wheat supplemented with enzymes can be used in substitution of maize in pullet diets with only a slight reduction in BW gain at 120 d of age. Also, feeding pellets from 1 to 45 d of age increased BW gain and pH of the gizzard, and reduced the RW of the gizzard and the RL of the GIT at 120 d of age. In experiment 2, a total of 864 brown-egg laying pullets was used to study the effects of the main cereal of the diet (500 g maize or wheat/kg) and particle size of the cereal (hammer milled to pass through a 6, 8, and 10-mm screen) on growth performance and GIT traits from 1 to 120 d of age. Each of the 6 treatments was replicated 6 times (24 pullets per replicate). Type of cereal did not affect pullet performance at any age. From 1 to 45 d of age, BW gain was increased (P < 0.001) and FCR was improved (P < 0.05) as the particle size of the cereal was reduced, but no effects were observed after this age. At 45 d of age, pullets fed maize tended (P < 0.10) to have a heavier RW of the GIT and proventriculus and a higher relative length (RL, cm/kg BW) of the SI than pullets fed wheat. Also at this age, the RW of the GIT increased (P < 0.05) with increases in particle size of the cereal. At 120 d of age, dietary treatment did not affect the RW of any of the organs studied or gizzard pH, but the RL of the SI was higher (P < 0.05) for pullets fed wheat than for pullets fed maize. Also, the RL of the SI was reduced (P < 0.05) as the particle size of the cereal increased. We conclude that 500 g wheat/kg can be included in pullet feeds from 1 to 120 d of age, and that particle size of the cereal affects pullet performance during the first 45 d of life but not thereafter. Therefore, it is recommended to grind the cereal used in this period with a screen size of no more than 8-mm. In experiment 3, a total of 1,152 one-day-old Hy-Line Brown egg laying pullets were used to study the influence of the energy content of the diet and feed form on productive performance and on several GIT traits. From 1 to 45 d of age, there were 6 diets arranged factorially with 3 concentrations of AMEn (low: 11.66 MJ/kg, medium: 12.05 MJ/kg and high: 12.66 MJ/kg) of the diet and 2 feed forms (mash vs. pellets). From 45 to 120 d all diets were fed in mash form and therefore, the only difference among treatments in this period was the energy content of the diets. Each of the 6 treatments was replicated 8 times and the experimental unit was formed by 24 pullets. Cumulatively, BW gain and FCR improved as the AMEn of the diet increased (P < 0.001). Also, pullets fed pellets from 1 to 45 d of age had higher feed intake and BW gain (P < 0.001) in this period and higher cumulative BW gain (P < 0.01) than pullets fed mash. At 45 d of age, the RWof all the segments of the GIT was lower for pullets fed the high- than for pullets fed the medium- or low- energy diets. At 120 d of age, the RW of the gizzard was higher (P < 0.01) for pullets fed the low energy diets than for pullets fed the other diets. However, the RL of the GIT was not affected by the energy content of the diet. Feeding pellets reduced the RW of the proventriculus (P < 0.05), gizzard (P < 0.001), and GIT (P < 0.001), as well as the RL of the small intestine (P < 0.05) and the ceaca (P < 0.001) at 45 d of age. The effects of feeding pellets on RW of gizzard and proventriculus were still evident at 120 d of age. We concluded that feeding pellets from 1 to 45 d of age improved feed intake and BW of pullets at 120 d of age and that an increase in the energy content of the diet increased pullet performance at all ages but reduced the RW of the proventriculus and gizzard. We conclude that maize and wheat can be used indistinctly in diets for egg laying pullets from 1 to 120 d of age, with only a slight reduction in final BW when wheat is used. Also, particle size of the cereal affects pullet performance during the first 45 d of life but not thereafter. Pelleting of the feeds, and grinding the cereal with a screen size of no more than 8-mm from 1 to 45 d of age, and the use of high density energy diets are recommended in order to achieve adequate target BW at 120 d of age. However, pelleting of the feed, very fine grinding, and the use of high AMEn diets might hinder the development of the GIT, especially that of the gizzard, which might affect feed intake of laying hens especially at the beginning of the production cycle.

Effect of type of dietary carbohydrates on digestion, intestinal barrier and growth performance in 25-d weaned rabbits

Los objetivos globales de esta tesis han sido estudiar el efecto que los carbohidratos de la dieta ejercen sobre los rendimientos productivos, la barrera intestinal, y la digestión de animales destetados a 25 días de edad. Además se ha estudiado cuál es el mejor periodo para determinar la digestibilidad fecal tras el destete a esta edad. En el primer experimento se estudió el efecto de la fibra neutro detergente soluble (FNDS) sobre la barrera intestinal, digestión, microbiota intestinal y rendimientos productivos de gazapos en gazapos en la fase post-destete. Se diseñaron tres piensos isonutritivos en los que la única fuente de variación fueron los niveles de fibra soluble. A partir de una dieta control (AH) con 103 g/kg de materia seca de FNDS y alfalfa como fuente principal de fibra, se sustituyó la mitad de esta alfalfa por una mezcla de pulpa de remolacha y pulpa de manzana (75:25) en el pienso B-AP y por una mezcla de cascarilla y concentrado de proteína de soja (88:12) en el pienso OH, obteniéndose 131 y 79 g/kg de FNDS sobre materia seca, respectivamente. Los conejos se destetaron a 25 días y fueron alimentados con los piensos experimentales hasta los 35 días de edad, momento en el que se sacrificaron para la determinación de la digestibilidad ileal aparente (DIA) de la materia seca (MS), proteína bruta (PB) y almidón, la morfología de la mucosa, y actividad enzimática en el yeyuno, el tejido linfoide asociado a la mucosa, así como la microbiota intestinal. Para la determinación de la morfología de la mucosa se utilizaron adicionalmente 19 animales lactantes de 35 días de edad. Para el estudio de la tasa de mortalidad, se utilizaron 118 animales más por tratamiento que recibieron los piensos experimentales durante las dos semanas post-destete y posteriormente un pienso comercial hasta los 60 días de edad. Los animales recibieron durante todo el experimento medicación en el agua de bebida (100 ppm de apramicina sulfato y 120 ppm de tilosina tartrato). El nivel de fibra soluble mejoró los parámetros que se utilizaron para la caracterización del estado de la barrera intestinal. Los conejos alimentados con el mayor nivel de FNDS en el pienso presentaron una mayor longitud de los villi (P=0.001), un mayor ratio longitud villi/profundidad de las criptas (8.14; P=0.001), una mayor actividad disacaridásica (8671 μmol de glucosa/g de proteína; P=0.019), así como una mayor digestibilidad ileal (96.8%; P=0.002), observándose una reducción en el flujo ileal de almidón a medida que se incrementó el nivel de fibra soluble en el pienso (1,2 vs 0,5 g/d; P=0.001). Los animales lactantes a 35 días de edad presentaron un ratio longitud de villi/profundidad de las criptas menor que el observado en aquéllos alimentados con el pienso B-AP (6.70), pero superior al de los piensos AH y OH. Niveles inferiores de NDFS tendieron (P=0.074) a incrementar la respuesta inmune de tipo celular (linfocitos CD8+). El pienso también afectó a la producción de IL2 (CD25+; P=0.029; CD5+CD25+; P=0.057), pero sin llegar a establecerse una clara relación con el nivel de fibra soluble. La diversidad de la microbiota intestinal no se vio afectada por el pienso (P ≥ 0.38). Los animales alimentados con las piensos B-AP y AH presentaron una reducción en la frecuencia de detección de Clostridium perfringens tanto en íleon (P=0.062) como en ciego (4.3 vs. 17.6%, P =0.047), comparado con el pienso OH. Además la tasa de mortalidad (118 gazapos/pienso) disminuyó de 14.4% en el pienso OH a 5.1% en el pienso B-AP. Entre los 32 y los 35 días de edad se determinó la digestibilidad fecal aparente (14/pienso) de la materia seca (MS), energía bruta (EB), proteína bruta (PB), fibra neutro detergente (FND), fibra ácido detergente (FAD) y almidón. Este grupo, junto con otros nueve animales por tratamiento se utilizaron para determinar el peso del estómago y el ciego, la concentración cecal de ácidos grasos volátiles (AGV) y amoniaco (NH3), así como las tasas de similitud de la microbiota intestinal. Además se estudiaron los rendimientos productivos (35 animales/tratamiento) de los gazapos durante todo el período de cebo, consumiendo los piensos experimentales desde el destete hasta los 35 días y posteriormente un pienso comercial hasta los 60 días de edad. Niveles crecientes de FNDS mejoraron la digestibilidad fecal de la materia seca (MS) y energía (P<0.001). La inclusión FNDS aumentó de manera lineal el peso del contenido cecal (P=0.001) y el peso del aparato digestivo completo (P=0.008), y en los días previos al sacrificio disminuyó de manera lineal el consumo medio diario (P=0.040). Se observó además, una disminución lineal (P≤0.041) del pH del estómago. No se encontró relación entre el pH, la concentración y proporciones molares de AGV y el nivel de FNDS. El pienso pareció tener un efecto, incluso superior al de la madre, sobre la tasa de similitud de la microbiota, y los efectos fueron mayores a nivel cecal que ileal. La eficacia alimenticia aumentó de manera lineal en un 12% entre piensos extremos tras el destete (25- 39d) y en un 3% en el período global de cebo con niveles mayores de NDFS. El consumo medio diario durante la fase post-destete y durante todo el período de cebo, tendió a aumen tar (P≤0.079) con niveles mayores de FNDS, sin embargo no se apreció efecto sobre la ganancia media diaria (P≥0.15). En conclusión, el incremento del nivel de fibra soluble en el pienso parece resultar beneficioso para la salud del animal ya que mejora la integridad de la mucosa, y reduce la frecuencia de detección de potenciales patógenos como C. perfringens y Campylobacter spp. Conforme a estos resultados, debería tenerse en cuenta el contenido en fibra soluble en la formulación de piensos de conejos en la fase post-destete. El objetivo del segundo experimento fue determinar el efecto de la fuente de almidón sobre la digestión, la microbiota intestinal y los rendimientos productivos en conejos destetados con 25 días de edad. Se formularon tres piensos isonutritivos en los que se modificaron las principales fuentes de almidón: trigo crudo, trigo cocido y una combinación de trigo y arroz cocido. Dos grupos de 99 y 193 animales se destetaron con 25 días de edad. El primero de ellos se utilizó para la determinación de los parámetros productivos conforme al mismo protocolo seguido en el experimento anterior. El segundo de los grupos se utilizó para la determinación de la digestibilidad fecal de 32 a 35 d, la digestibilidad ileal aparente (DIA) a 35 d, la morfología de la mucosa intestinal, los parámetros de fermentación cecal; así como, la caracterización de la microbiota intestinal. Se utilizaron además dos grupos adicionales de animales 384 (medicados) y 177 (no medicados) para estudiar el efecto de la suplementación con antibióticos en el agua de bebida sobre la mortalidad. El procesado térmico del trigo mejoró ligeramente la digestibilidad ileal del almidón (P=0.020) pero no modificó el flujo final de almidón que alcanzó el ciego, observándose una mayor frecuencia de detección de Campylobacter spp. y Ruminococcus spp. en ciego (P≤0.023), pero sin cambios a nivel ileal. El procesado térmico del trigo no afectó tampoco a los parámetros productivos, la mortalidad, la digestibilidad ileal y fecal o la morfología de la mucosa. La sustitución parcial del trigo cocido por arroz cocido, penalizó la digestibilidad ileal del almidón (P=0.020) e incrementó el flujo ileal de este nutriente al ciego (P=0.007). Sin embargo no afectó a la mortalidad, pese a que se detectaron cambios en la microbiota tanto a nivel ileal como cecal, disminuyendo la frecuencia de detección de Campylobacter spp. (en íleon y ciego), Helicobacter spp. (en íleon) y Ruminococcus spp (en ciego) e incrementando Bacteroides spp. (en ciego) (P≤0.046). El empleo de arroz cocido en las piensos post-destete no tuvieron efectos sobre los parámetros productivos, la mortalidad, la digestibilidad ileal y fecal a excepción del almidón, o la morfología de la mucosa. La suplementación con antibiótico redujo la fre cuencia de detección de la mayoría de las bacterias estudiadas (P≤0.048), sobre todo para Campylobacter spp., Clostridium perfringens y Propionibacterium spp. (P≤0.048), observándose un efecto mayor a nivel ileal que cecal, lo que se asoció a la bajada significativa (P<0.001) de la mortalidad. En conclusión, los resultados de este experimento indican que la fuente de almidón afecta a la microbiota intestinal pero no influiye sobre la salud del animal. En relación al procesado, el uso de trigo cocido junto con arroz cocido no mejora los resultados obtenidos con trigo duro, si bienserían necesarios más experimentos que confirmaran este punto. El último de los experimentos se centró en un aspecto metodológico. Dado que, los conejos destetados presentan un patrón digestivo diferente al de un animal adulto resultado de su inmadurez digestiva, el objetivo buscado era tratar de determinar el mejor procedimiento para la determinación de la digestibilidad fecal en los gazapos en la fase post-destete. Para tal fin se utilizaron 15 animales/tratamiento de tres camadas diferentes que se destetaron con 25 días, suministrándoles un pienso comercial de crecimiento-cebo. Se registró el consumo medio diario y la excreción diaria de heces desde el día 25 hasta el día 40 de edad para la determinación de la digestibilidad de la MS. La camada afectó al consumo medio diario y la excreción de heces (P=0.013 y 0.014, respectivamente), observándose una tendencia (P=0.061) en la digestibilidad. La edad afectó (P<0.001) a todos estos factores, incrementándose de manera más evidente la excreción que la ingestión de materia seca en la primera semana de vida, para aumentar de forma paralela a partir de la segunda. La correlación entre el consumo medio diario fue mayor con la excreción de heces del mismo día que con la del día siguiente, por lo que se utilizó el primero para la determinación de la digestibilidad de la MS (MSd). La MSd disminuyó de manera lineal hasta los 32 días de edad (2.17±0.25 unidades porcentuales por día), mientras que permaneció constante desde los 32 a los 40 días (69.4±0.47%). Por otro lado, la desviación estándar de la MSd se redujo cuando se incrementó el período de recogida de 2 a 6 días en un 54%. Conforme a los resultados obtenidos, se puede concluir que no es aconsejable comenzar las pruebas de digestibilidad antes de los 32 días de edad y que el número de animales necesario para detectar diferencias significativas entre tratamientos dependerá del período de recogida de heces. ABSTRACT The global aim of this thesis has been to study the effect of dietary carbohydrates on growth, performance, digestion and intestinal barrier in 25-d weaned rabbits. In addition there has also been studied which is the best period to determine the fecal digestibility after weaning. The first experiment focused on the effect of Neutral Detergent Soluble Fibre (NDSF) on gut barrier function, digestion, intestinal microbiota and growth performance n rabbits in the post-weaning period. Three isonutritive diets which only varied in the levels of soluble fiber were formulated such as it described as follows: a control diet (AH) containing 103 g of neutral detergent soluble fiber, including alfalfa as main source of fiber, was replaced by a mixture of beet and apple pulp (75-25) in the B-AP diet and, by a mix of oat hulls and soybean protein concentrate (88:12) in the OH diet, resulting 131 and 79 g of NDFS/kg of dry matter, respectively. Rabbits, weaned at 25 days of age, were fed the experimental diets up to 35 days of age, moment in which they were slaughtered for apparent ileal digestibility (AID) of dry matter (DM), crude protein (CP) and starch, mucosa morphology, sucrose activity, characterization of lamina propria lymphocytes and intestinal microbiota. To assess mucosal morphology, 19 suckling 35-d-old rabbits were also used. For mortality study, besides these animals, 118 additional rabbits per treatment were fed the experimental diets for two weeks period and thereafter received a commercial diet until 60 days of age. Rabbits were water medicated during the whole experimental period (100 ppm de apramicine sulphate and 120 ppm of tylosine tartrate). Level of soluble fiber improved all the parameters used for the characterization of the intestinal barrier condition. Villous height of the jejunal mucosa increased with dietary soluble fiber (P=0.001). Villous height of jejunal mucosa increased with dietary soluble fiber (P = 0.001). Rabbits fed the highest level of soluble fiber (BA-P diet) showed the highest villous height/crypth depth ratio (8.14; P = 0.001), sucrase specific activity (8671 μmol glucose/ g protein; P = 0.019), and the greatest ileal starch digestibility (96.8%; P = 0.002). The opposite effects were observed in rabbits fed decreased levels of soluble fiber (AH and OH diets; 4.70, 5,848 μmol of glucose/g of protein, as average, respectively). The lowest ileal starch digestibility was detected for animal fed OH diet (93.2%). Suckling rabbits of the same age showed a lower villous height/crypt depth ratio (6.70) compared with the B-AP diet group, but this ration was higher that the AH or OH diet groups. Lower levels of soluble fiber tended (P = 0.074) to increase the cellular immune response (CD8+ lymphocytes). Diet affected IL-2 production (CD25+, P = 0.029; CD5+CD25+, P = 0.057), with no clear relationship between soluble fiber and IL-2. The intestinal microbiota biodiversity was not affected by diets (P ≥ 0.38). Animals fed B-AP and AH diets had a reduced cecal frequency of detection compatible with Campylobacter spp. (20.3 vs. 37.8, P = 0.074), and Clostridium perfringens (4.3 vs. 17.6%, P = 0.047), compared with the OH diet group. Moreover, the mortality rates decreased from 14.4 (OH diet) to 5.1% (B-AP diet) with the increased presence of soluble fiber in the diet. Between 32 and 35 days of age, faecal apparent digestibility of dry matter (DM), gross energy (GE), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and starch was determined (14/diet). This group, plus another nine rabbits/diet were used to determine weight of stomach and caecum and their contents, cecal fermentation traits and similarity rate (SR) of intestinal microbiota. Besides, growth performance parameters (35 rabbits/diet) were studied during the whole fattening period, in animals consuming the experimental feed after the weaning up to 35 days of age and later on a commercial diet up animals reached 60 days of age. Increasing levels of Neutral Detergent Soluble Fiber improved faecal dry matter and energy digestibility (P<0.001). NDSF inclusion improved linearly weight of the caecal content (P=0.001) and the total gastrointestinal tract (P=0.008), and in the previous days to slaughter a linear decrease of daily feed intake in diet with highest level of soluble fiber was also observed. Stomach pH decreased linearly with increasing levels of NDFS (P≤0.041). No relation between NDSF level on pH, concentration and molar proportion of VFA was found. Treatments appeared to influence the similarity rate of microbiota, even higher to mother effect. These effects were higher in ileum than in caecum. A linear positive effect of feed efficiency was observed, which increased around 12% in the two weeks post-weaning (25-39d) and 3% in the whole fattening period between extreme diets with highest levels of soluble fiber. Average daily feed intake during the two weeks after weaning and in the whole fattening period, tended (P≤0.079) to increase with highest levels of NDSF; although there were no effect on daily weight gain (≥0.15). In conclusion, an increase of soluble fiber in the feed seems to be beneficial for animal health, due to improve mucose integrity and reduce detection frequency of those poten tial pathogens like C. perfringens and Campylobacter spp. According to these results, level of soluble fiber should be taking care in feed rabbit formulation in the post-weaning period. The objective of the second experiment was to determine the effect of source of starch on digestion, intestinal microbiota and growth performance in twenty-five-day old weaned rabbits. To accomplish with this aim three iso-nutritive diets were formulated with different source of starch: raw wheat, boiled wheat and a combination of boiled wheat and boiled rice. Two groups of 99 and 193 rabbits were weaned at 25 days of age. The first group was used for growth performance determination following the same protocol than in previous experiment. The second group was used to determine faecal digestibility from 32 to 35 d, apparent ileal digestibility (AID) at 35 d, jejunal mucosa morphology, caecal fermentation traits and characterization of intestinal microbiota. For mortality, two additional groups of 384 (medicated) and 177 (not medicated) were used in order to study the effect of antibiotic water supply supplementation. Heat processing of starch slightly improved ileal digestibility of starch (P=0.020) but did not modify the flow of starch to the caecum. An increase in frequency of detection of Campylobacter spp. y Ruminococcus spp. was observed in the caecum (P≤0.023), with no changes at ileal level. Heat processing of wheat did not modify growth performance, mortality, ileal or faecal digestibility and mucosa morphology. Partial substitution of boiled wheat for boiled rice in the diet impaired ileal starch digestibility (P=0.020) and increased the ileal flow of this nutrient to the caecum (P=0.007). However, it did not affect mortality rate, although changes in the ileal and caecal intestinal microbiota were detected, decreasing the frequency of detection of Campylobacter spp. (both ileum and caecum), Helicobacter spp. (at ileum) and Ruminococcus spp (at caecum) and increasing the Bacteroides spp. (at caecum) (P≤0.046). The effect of boiled rice supplementation did not alter growth performance, mortality, ileal or faecal digestibility of other nutrients than starch, and mucosa morphology. Medication of rabbits reduced the ileal frequency of detection of most bacteria studied (P≤0.048), especially for Campylobacter spp., Clostridium perfringens y Propionibacterium spp. (P≤0.048), resulting the effect higher at ileal than caecal level and relating it with a strong reduction of mortality rate (P<0.001). In conclusion, the results of this experiment make think that the source of starch affects the intestinal microbiota but they do not seem to influence animal health. In relation to the effect of heat processed the use of cooked wheat or cooked rice it does not seem to im prove the results obtained with hard wheat, but there would be necessary more experiments that were confirming this point. The last experiment focused on a methodological aspect. Considering that, weaned rabbits have a different digestive pattern than older animals due to their digestive immaturity; the fixed objective was to determine the best procedure for faecal digestibility determination in young rabbits in the post-weaning period. Fifteen rabbits from 5 different litters were weaned at 25 days of age and fed with a commercial feed. Feed intake and faeces excretion were recorded daily from 25 to 40 days of age for dry matter digestibility (DMd) determination. Litter affected daily DM intake and excretion (P=0.013 y 0.014, respectively) and tended to affect DMd (P=0.061). Age affected all these factors (P<0.001), but ingestion increased slowly than dry matter excretion during the first week buth they evolved similarly in the second week. The correlation between daily feed intakes was higher with the faeces excretion of the day than with faeces excretion of the next day, and the first values were used to determine daily DMd. The DMd decreased linearly from weaning to 32 d of age (2.17±0.25 percentage units per day), whereas from 32 to 40 d remained constant (69.4±0.47%). On the other hand, average standard deviation of DMd decreased by 54% when the length of collection period increased from 2 to 6d. Consequently to the obtained results, it could be concluded that it would not be advisable to start digestibility trials before the 32 days of age and that the number of animals required to detect a significant difference among means would depend on the collection period.

Estudio del fenómeno Social Media en la pequeña empresa del sector TIC español

En un mundo en el que cada vez son más las personas que utilizan Internet para llevar a cabo sus comunicaciones y relaciones, tanto a nivel personal como profesional, las Redes Sociales se han convertido en una herramienta, para muchos imprescindible, de interacción social. A lo largo de este proyecto se realizará un análisis exhaustivo de las características del ya conocido como Fenómeno Social Media, para posteriormente centrar toda la atención en las ventajas y desventajas de dicha actividad en el ámbito empresarial. Dado que hasta el momento no se ha encontrado ningún otro estudio que trate el Fenómeno Social Media en la Pequeña Empresa del sector TIC español, el objetivo principal del proyecto se centra en conocer la influencia que las Redes Sociales están generando en la estrategia empresarial de dicho sector de empresas, cuyas características y particularidades hacen de ellas un modelo de negocio único y diferente y cuyo número se ha visto incrementado en los últimos años, debido quizás, a la situación de crisis que atraviesa el país. Para ello, se analizarán las ventajas e inconvenientes que se derivan de su uso, como afecta a la creación de valor, y, finalmente, cual es el nivel de implicación y/o inversión que la Pequeña Empresa ha adoptado al respecto. Dentro de este marco, se pretende realizar un énfasis especial en el concepto de cocreación de valor y sus variantes (Crowdsourcing, Open Innovation e Innovación Orientada por las Personas), que permita determinar el grado de importancia del usuario como generador de valor. Posteriormente, en la parte práctica, se llevará a cabo un amplio estudio de mercado, a partir de una encuesta online realizada a un conjunto de empresas, cuidadosamente seleccionadas de entre más de 100.000 compañías, según su sector de actividad, número de empleados y volumen de negocios anual, y cuyos resultados serán analizados con la intención de obtener una visión clara del comportamiento global de las empresas seleccionadas. Por último, tomaremos de referencia las dos últimas publicaciones anuales del “Observatorio sobre el uso de las Redes Sociales en las Pymes españolas” (2011 y 2013), estudios dedicados íntegramente a Redes Sociales y Pymes, y cuya información, junto con los resultados obtenidos de nuestro estudio, nos permitirán determinar la tendencia actual y futura, y en consecuencia, obtener las conclusiones oportunas que nos permitan dar respuesta a las cuestiones planteadas durante la realización del proyecto, y determinar si nos encontramos o no ante una verdadera fuente de éxito empresarial. ABSTRACT. In a world where more and more people are using the Internet to perform their communications and relationships, both personally and professionally, Social Networks have become a social interaction tool, indispensable for many people. Throughout this project we will perform a thorough analysis of the characteristics of the Social Media Phenomenon, focusing on the advantages and disadvantages of such activity in a business scope. Given that we have not found no study on the Social Media Phenomenon in Small Business of the Spanish ICT sector, the main objective of this project is to establish the influence that Social Networks are generating in the business strategy of this business sector, the characteristics and peculiarities that make them a unique and different business model and whose number has increased in recent years, perhaps due to the crisis the country is facing. To do this, we will discuss the advantages and disadvantages derived from its use, how it affects value creation, and finally, what is the level of involvement and / or investment that the Small Business has taken in this regard. In this context, we intend to make a special emphasis on the concept of value co-creation and its variants (Crowdsourcing, Open Innovation and People Oriented Innovation), to determine the degree of importance of the user to value generator. Subsequently, on the practical section, out a comprehensive market study will be carried, based on an online test to a group of enterprises, carefully selected from more than 100,000 companies, according to their sector of activity, number of employees and annual turnover, and the results will be analyzed with the intention to get a clear view of the selected company's overall performance. Finally, we will take as reference the last two annual publications of the "Observatory on the use of Social Networks in Spanish SMEs" (2011 and 2013), entirely dedicated to Social Media and SMEs studies, and whose information, together with the results obtained in our study will allow us to determine the current and future trends, and consequently, obtain the appropriate conclusions to respond to the raised questions throughout the project, and determine whether or not they are a real source of business success.

Dopamine signaling is essential in cognitive process and motor performance

La dopamina es uno de los principales neurotransmisores del sistema nervioso central y desempeña un papel esencial en diferentes funciones: neuroendocrinas, motivacionales/emocionales y, especialmente, motoras y cognitivas. Las funciones de la dopamina están media-das en gran medida por la estimulación de sus principales receptores D1 (D1R) y D2 (D2R). En esta tesis hemos estudiado el papel que ambos receptores desempeñan en los procesos de apren-dizaje y memoria, así como la regulación que ejercen sobre las neuronas estriatales TH-immunoreactivas (TH-ir) y su posible implicación en la respuesta motora. Para abordar este proyecto hemos utilizado ratones knock-out para el receptor D1 (Drd1a-/-) y D2 (Drd2-/-) ya que no existen compuestos farmacológicos capaces de diferenciar eficazmente entre receptores dopaminérgicos de la misma familia. Además, para el estudio de las neuronas TH-ir realizamos lesiones con 6-OHDA a ratones que posteriormente recibieron un tratamiento crónico con L-DOPA, siendo este el mecanismo más eficaz para inducir la expresión de las neuronas TH-ir objeto de nuestro estudio. Para completar todo ello realizamos test conductuales que evalúan respuesta motora, como el test del cilindro, y diferentes tipos de aprendizaje y me-moria para los cuales utilizamos test específicos. Entre estos test se encuentran: los laberintos de Barnes y Morris para memoria espacial, evitación activa/pasiva y condicionamiento del mie-do para el aprendizaje asociativo, y el reconocimiento de objetos para la memoria de reconoci-miento...

Electrocatalytic Performance of SiO2-SWCNT Nanocomposites Prepared by Electroassisted Deposition

Composite materials made of porous SiO2 matrices filled with single-walled carbon nanotubes (SWCNTs) were deposited on electrodes by an electroassisted deposition method. The synthesized materials were characterized by several techniques, showing that porous silica prevents the aggregation of SWCNT on the electrodes, as could be observed by transmission electron microscopy and Raman spectroscopy. Different redox probes were employed to test their electrochemical sensing properties. The silica layer allows the permeation of the redox probes to the electrode surface and improves the electrochemical reversibility indicating an electrocatalytic effect by the incorporation of dispersed SWCNT into the silica films.