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El análisis del sistema Daylight se realizó identificando tecnologías eficientes para canalizar la luz natural en áreas que dependan de la iluminación. Este análisis se basó en los datos de radiación solar total en los últimos cuatros años en el departamento de Lambayeque. Se utilizó fórmulas matemáticas que parten de las magnitudes de radiometría y fotometría para determinar valores de lumen por metro cuadrado correspondiente a la luz natural. Para el análisis de los valores obtenidos se trabajó en una plantilla de Microsoft Excel, los cuales se compararon con las normas técnicas de iluminación determinando el tipo de tecnología que más se adapta a las condiciones del área a iluminar. De esta manera, el sistema Daylight en los cuatro tipos de sistema tiene una eficiencia teórica en más del 80% para canalizar la luz del medio, demostrando ser eficientes en la variación de captación de luz de acuerdo al diámetro y longitud de los tubos solares y la ubicación geográfica. Al utilizar este tipo de sistemas se desarrollará tecnologías que ahorren energía de forma económica y respetuosa con el medio ambiente de las fuentes alternativas como es la iluminación natural, reduciendo costos de tarifa eléctrica y minimizando la dependencia energética de los combustibles fósiles como el petróleo, carbón, diesel, gas y de las hidroeléctricas, llevándonos a mejorar la eficiencia energética.

The goal of this dissertation was to develop application of ultrasonography as a decision-making tool in genetic improvement programs for channel catfish Ictalurus punctatus. A literature review on the use of ultrasonography in fish reproduction generated a comprehensive reference data set intended to benefit existing and potential users. It exposed the need for reporting of instrument control settings and standardization of fish handling and imaging procedures. These issues were addressed from the onset of this work by assessing more than 6,300 channel catfish ovaries by use of initial fish handling and imaging procedures developed (2004-2005) at the Louisiana State University Agricultural Center Aquaculture Research Station. The development of a standardized and systematic approach to interpretation of ultrasound images emphasized the interplay of technical and biological aspects of ultrasonography assessments. This showed the importance of the control settings and identified disruptive ultrasound artifacts to avoid for observation of the ovary and oocytes. A preliminary ultrasound imaging classification index for assessing ovarian development during the annual reproductive cycle was developed, used and evaluated. This led to the creation of seven well-defined, standardized ultrasound imaging classifications of channel catfish ovarian development based on the annual cycle. Histology of each ultrasound image in the classification index was included as a Reference Guide to provide insight into the processes observed during ultrasonography. Finally, the ultrasound imaging classification index was used for identification and selection of females for hormone-induced spawning in commercial hatchery production of F1 hybrids (channel catfish female x blue catfish male I. furcatus). In sum, this dissertation provides a systematic method of ultrasound imaging assessment of channel catfish ovarian development enabling progress towards standardization in the use of ultrasonography in fish reproduction.

The variety of life forms within a given species, ecosystem, biome or planet is known as biodiversity. Biodiversity can also be referred as species diversity and species richness. Understanding the drivers of biodiversity requires an understanding of intertwined biotic and abiotic factors, including climate patterns over the earth, primary productivity processes, e.g. photosynthetic pathways which change with climate and latitude; latitude, geology, soil science, ecology and behavioural science. Diversity of living organisms is not evenly distributed; instead it differs significantly across the globe as well as within regions. The aim of my study is to try to understand the diversity patterns of aquatic plants, using both information derived from previous studies and by collecting new data across the globe, allowing me to examine the underlying mechanisms driving biodiversity at regional and local scales. Both geographical location and local environmental factors were found to contribute to variation in macrophyte assemblage and alpha diversity (i.e. number of species in a locality), with important roles being played by local biotic interactions and abiotic environmental factors. Overall aquatic plants, or macrophytes, play a significant role in the ecology of large numbers of freshwater ecosystems worldwide. For the purpose of my study only calcareous steams, located in both temperate and tropical/subtropical regions were included. Such streams are common in catchments throughout the world because approximately one fifth of the earth’s surface is underlain by carbonate-containing rock. Overall my findings in Chapter 3 provide evidence that there is a high variation in macrophyte assemblages of calcareous rivers across the different countries included in my study, broadly agreeing with information from the literature. I found two large groups based on species assemblages across the different countries included, i.e. a subtropical/tropical and a temperate group. As demonstrated in different parts of Chapter 4, it is possible to identify different 4 diversity responses of macrophyte functional groups to environmental conditions, at local scale, in hardwater rivers. Width and flow were found to be significantly affecting the distribution patterns of diversity of free-floating and floating-leaved rooted species, whereas diversity of marginal species was significantly related to alkalinity and width, and floating-leaved rooted diversity was significantly related to alkalinity. Last but not least submerged species were related to shading. Chapter 5 shows that variation in richness and community structure for hardwater river macrophytes can be partly explained by environmental variation relative to spatial processes in the British Isles (temperate scenario) and in Zambia (tropical scenario). Among the environmental variables, climatic ones explained a great part of species richness and composition distribution for the British Isles. Conversely in Zambia spatial processes made the greatest contribution to variation in hardwater river macrophyte species richness and community structure. Moreover Chapter 6 illustrates how macrophyte species richness, measured as alpha-diversity in calcareous rivers, was at best only very weakly attributed to latitudinal gradient. This is most likely due to the effect of other physical, chemical and biotic variables overriding broader-scale influences on species richness, at more local scales.

Biomineralisation is the process by which living things produce hard mineral tissues with unique physical properties. The study of this process can help us produce biomimetic materials, reproducing such properties, with the study of nucleation and crystallisation of the materials being particularly important. I have used molecular simulation techniques to help gain a greater understanding of these processes, focussing particularly on identifying the conformations and solid phases available to nanoparticles of two biomineral compounds. The bones and teeth of mammals are made largely of calcium phosphates. I have used metadynamics to study nanoparticles of tricalcium phosphate (TCP) and have identified high and lower order configurations. To facilitate this work I reviewed the extant empirical potentials for calcium phosphate systems, selecting the most appropriate for TCP. Calcium carbonate, found in examples throughout the animal kingdom, has three crystalline polymorphs relevant to biomineralisation: calcite, aragonite and vaterite. While nanoparticles of calcite have been extensively studied the other polymorphs have been neglected to date. In this work I present a technique for predicting crystalline morphologies for all three polymorphs across a range of sizes, and compare the energetic ordering. In water the energetic ordering of the nanoparticles is heavily dependent on nanoparticle size. Furthermore, I present work calculating the surface enthalpies of a variety of calcium carbonate surfaces, many of which are negative. It appears that entropic penalty of ordered water is key to understanding the stability of nanocrystals. Also presented is an application of the nudged elastic band method to study transitions between nanoparticle crystal conformations. Between all three crystal polymorphs the nanoparticles passed through an amorphous region of phase space. These results have also been used to evaluate order parameters for use in metadynamics simulations.

This thesis examines the colony size structure and taxonomic composition of coral communities from eight regions of the Indian Ocean approximately 10 years after thermal stress-induced mass mortality events. Coral community composition and population structure differed widely within and between regions, reflecting the different climatic and anthropogenic impacts experienced by each over the past decade. Coral communities in most areas started from a similarly depleted condition but after 1998 their recovery trajectories varied significantly, reflecting different surviving adult communities and continuing, different local stressors; some have remained highly depleted, while others have shown marked recovery. Profound differences between coral communities at intra and inter-regional spatial scales are identified and related to diversity and taxonomic composition, colony abundance, surface area, size frequency distributions, and population demographic parameters within taxa. These are analysed through multivariate techniques and univariate graphical representations to illustrate the significantly different size frequency distributions, taxonomic composition, taxonomic richness and dominance patterns at different spatial scales. A novel technique is assessed for surveying juvenile coral communities, using ultraviolet light, which causes new, growing tissue to fluoresce. This method significantly increases detected juveniles, with important consequences to size frequency patterns and to some previously published views on juvenile densities. The surveying methodologies used are far more revealing than most commonly-used conventional benthic assessments such as intercept surveys, cover values and diversity, which rarely capture discriminatory information on overall composition of coral communities, let alone the structure of populations within them. These colony size-based studies of individual genera are extremely sensitive for interpreting spatial and temporal variations in reefs and greatly enhance understanding of coral reef condition and complexity. The spatial differences demonstrate the applicability of the methods for advising reef management, specifically in identifying areas where ecological resilience is impeded by recruitment failure. Long-term consequences of changes in coral communities may include reduced ecological functional redundancy, reduced structural complexity, reduced carbonate accretion and reef growth, and impaired recovery potential.

No description available.

Today’s data rates in wired networks can reach 100 Gbit/s using optical fiber while data rates in wireless networks are much lower - tens of Mbit/s for 3G mobile communication and 480 Mbit/s for ultra-wideband (UWB) short range wireless communications. This difference in data rates can mainly be explained by the limited allowed frequency spectrum, the nature of the radio signal and the high requirements imposed on all hardware designed for high speed and wideband wireless communications. However, the demand on wireless commercial applications at competitive costs is growing. The first step in regulations allowing higher data rates for wireless communications was taken in 2002, when the Federal Communication Commission (FCC) in USA released unlicensed the 3.1-10.6 GHz frequency band restricting only the power level (maximum mean equivalent isotropic radiated power density of a UWB transmitter is -41.3 dBm/MHz) in the band 3.1-10.6 GHz. But Europe, Japan and recently China have put additional restrictions on the 3.1-4.8 GHz band. The restrictions address the problems that have raised from the coexistence and colocation of the UWB systems with other narrowband wireless systems. Thus, the 6-9 GHz band combined with an increased modulation order scheme is of large interest. Operating at higher frequency and wider bandwidth than today’s communication technologies, with the general task of maximizing the wireless data rate while keeping the power consumption low, requires new communication system solutions and new circuit design approaches. These new solutions also require understanding of many multi-disciplinary areas which until the recent past were not directly related: from classic analog circuit design to microwave design, from modulation techniques to radio system architecture. In this thesis, new design techniques for wide bandwidth circuits above 3 GHz are presented. After focusing on ultra-wideband low-noise amplifier (UWB LNA) design for low-power and low-cost applications, the practical implementation and measurement of a 3.1-4.8 GHz UWB LNA is addressed. Passive distributed components of microstrip transmission lines are intensively used and their contribution to the UWB LNA performance is studied. In order to verify the design methodology while extending it to the UWB radio front-end, the UWB LNA is integrated on the same substrate with a pre-selecting filter with the frequency multiplexing function. In this way, the concept of frequencytriplexed UWB front-end is demonstrated for the Mode 1 multi-band UWB bandwidth 3.1-4.8 GHz. Using the proposed receiver front-end topology, better receiver sensitivity and selective operation can be achieved. The later part of the thesis investigates ultra-wideband 6-9 GHz receiver and transmitter front-end topologies for Gbit/s data rates and low power consumption. To capture the advantages offered by distributed passive components, both the transmitter and receiver use the six-port correlator as the core of a passive mixer. Modelling and design of the 6-9 GHz UWB front-end transceiver include different receiver topologies and different modulation schemes. Finally, the 7.5 GHz UWB transceiver front-end is implemented and evaluated. Measurement results confirm the large potential of the six-port UWB front-end to achieve multiple Gbit/s data rates. This may open for future solutions to meet the continuous challenge of modern communication systems: higher data rates at low power consumption and low cost.

Alumina-zirconia thin films have been deposited using dual magnetron sputtering. Film growth was performed at relatively low-to-medium temperatures, ranging from ~300°C to 810 °C. Different substrates were applied, including silicon (100), and industrially relevant materials, such as WC-Co hardmetal. Both radio-frequency sputtering and direct-current magnetron sputtering were utilised to achieve a range of film compositions. The influence of sputtering target was investigated; both ceramics and metals were used as sputtering sources. Microstructural characterisation was performed with a range of electron microscopy and x-ray diffraction techniques which show that the pure zirconia was deposited in the monoclinic phase. Reduced mobility of depositing species, as in the case of direct-current sputtering, yielded preferred crystallographic orientation in the {100} directions. The initial nucleation layer consisted of the metastable tetragonal zirconia phase. This phase could be grown over film thicknesses ~1 μm through the addition of ~3 at.% Al under similar low mobility conditions. For cases of higher mobility, as obtained through radio-frequency sputtering, the metastable cubic zirconia phase formed in the film bulk for alumina-zirconia nanocomposites. A combination of two mechanisms is suggested for the stabilisation of metastable zirconia phases: oxygen-deficiency and aluminium segregations with resultant restraint on the zirconia lattice. The sputter deposition process was investigated through energy resolved mass spectrometry in the case of radio-frequency sputtering; the sputter deposition flux contained a mixture of metallic ions, metaloxygen clusters, and oxygen ions. The presence of metal-oxygen clusters was found to be important in oxygen-stoichiometry and thus the phase selection of the resultant film. The energy distributions were similar when comparing sputtering from ceramic and metallic targets. A mass-balance model has also been developed for the transport phenomena and reactions of particles in reactive sputtering of two targets in a two-gas scenario for the alumina-zirconia system. Addition of nitrogen to the working gas was found to eliminate the hysteresis in the target poisoning for oxygen reactive sputtering. The higher reactivity of oxygen contributed to a higher oxygen content in resultant films compared to the oxygen content in the oxy-nitride working gas. The model was thus shown to be successful for tuning depositions in the alumina-zirconia oxy-nitride system.