Advanced Fibre Bragg Grating fabrication systems and devices

This thesis address the creation of fibre Bragg grating based sensors and the fabrication systems which are used to manufacture them. The information is presented primarily with experimental evidence, backed up with the current theoretical concepts. The issues involved in fabricating high quality fibre Bragg gratings are systematically investigated. Sources of errors in the manufacturing processes are detected, analysed and reduced to allow higher quality gratings to be fabricated. The use of chirped Moiré gratings as distributed sensors is explored, the spatial resolution is increased beyond that of any previous work and the use of the gratings as distributed load sensors is also presented. Chirped fibre Bragg gratings are shown to be capable of operating as in-situ wear sensors, capable of accurately measuring the wear or erosion of the surface of a material. Two methods of measuring the wear are compared, giving a comparison between an expensive high resolution method and a cheap lower resolution method. The wear sensor is also shown to be capable of measuring the physical size and location of damage induced on the surface of a material. An array method is demonstrated to provide a high survivability such that the array may be damaged yet operate with minimal degradation in performance

Effects of body size and temperature on population growth

For at least 200 years, since the time of Malthus, population growth has been recognized as providing a critical link between the performance of individual organisms and the ecology and evolution of species.We present a theory that shows how the intrinsic rate of exponential population growth, , and the carrying capacity, rmax K, depend on individual metabolic rate and resource supply rate. To do this, we construct equations for the metabolic rates of entire populations by summing over individuals, and then we combine these population-level equations with Malthusian growth. Thus, the theory makes explicit the relationship between rates of resource supply in the environment and rates of production of new biomass and individuals. These individual-level and population-level processes are inextricably linked because metabolism sets both the demand for environmental resources and the resource allocation to survival, growth, and reproduction. We use the theory to make explicit how and why exhibits its characteristic dependence on body size and rmax temperature. Data for aerobic eukaryotes, including algae, protists, insects, zooplankton, fishes, and mammals, support these predicted scalings for. The metabolic flux of energy and materials also rmax dictates that the carrying capacity or equilibrium density of populations should decrease with increasing body size and increasing temperature. Finally, we argue that body mass and body temperature, through their effects on metabolic rate, can explain most of the variation in fecundity and mortality rates. Data for marine fishes in the field support these predictions for instantaneous rates of mortality. This theory links the rates of metabolism and resource use of individuals to life-history attributes and population dynamics for a broad assortment of organisms, from unicellular organisms to mammals

Bending and orientational characteristics of long period gratings written in D-shaped optical fiber

Long period gratings (LPGs) were written into a D-shaped single-mode fiber. These LPGs were subjected to a range of curvatures, and it was found that as curvature increased, there was increasingly strong coupling to certain higher order cladding modes without the usual splitting of the LPGs stopbands. A bend-induced stopband yielded a spectral sensitivity of 12.55 nm · m for curvature and 2.2 × 10-2 nm°C-1 for temperature. It was also found that the wavelength separation between adjacent bend-induced stopbands varied linearly as a function of curvature. Blue and red wavelength shifts of the stopbands were observed as the sensor was rotated around a fixed axis for a given curvature; thus, in principle, this sensor could be used to obtain bending and orientational information. The behavior of the stopbands was successfully modeled using a finite element approach

Irish Ocean Climate and Ecosystem Status Report 2009

This report presents the results from the most comprehensive analysis to date of marine climate change in Irish waters. Using a variety of available datasets from Ireland and elsewhere, the status of Ireland's marine climate is described. These data sets are collected over varying time scales. The longest datasets extend back to the late 1950s while others have been initiated in the past 5-10 years. In some cases data have been put in a wider context by comparison with international data such as the HADSST sea surface temperature analysis and the Continuous Plankton Recorder (CPR) survey conducted by the Sir Alister Hardy Foundation for Ocean Science (SAHFOS). While the analysis to date has been considerable the brevity of some of the time series means that in 2009 we are relatively poorly equipped to make conclusions as to how climate change will affect Irish waters. This report describes key regulators of ocean climate around Ireland and examines relevant environmental datasets available in 2009. It therefore represents the current status of knowledge regarding the influence of climate on Ireland’s marine ecosystems and resources

Winter Nitrate and Phosphate levels in the Western Irish Sea in 1991

This study of nitrate, phosphate and salinity levels in the western Irish Sea indicates that the distribution of nutrient levels can be explained by taking into account the known physical and hydrological features of the area. There is a clear inverse relationship between nitrate and salinity data with nitrate levels decreasing rapidly moving offshore. The distribution of phosphate levels is more complex and appears to be influenced by multiple point source inputs and inflows from the Celtic Sea

Friendships in children with Williams syndrome : parent and child perspectives

Although children with Williams syndrome (WS) are strongly socially motivated, many have friendship difficulties. The parents of 21 children with WS and 20 of the children themselves participated in a semi-structured interview about the children's friendships. Parents reported that their child had difficulties sustaining friendships and low levels of interaction with peers. Barriers to friendships included difficulties with play and self-regulating behaviour. However, there was within-group variability, with a small number of children reported to have strong friendships. While parents reported friendship challenges, all of the children named at least one friend, and most said that they had never felt excluded by their peers. Future research is needed to determine optimal ways to support children with WS in their friendships

The Cost of Sex: Quantifying Energetic Investment in Gamete Production by Males and Females

The relative energetic investment in reproduction between the sexes forms the basis of sexual selection and life history theories in evolutionary biology. It is often assumed that males invest considerably less in gametes than females, but quantifying the energetic cost of gamete production in both sexes has remained a difficult challenge. For a broad diversity of species (invertebrates, reptiles, amphibians, fishes, birds, and mammals), we compared the cost of gamete production between the sexes in terms of the investment in gonad tissue and the rate of gamete biomass production. Investment in gonad biomass was nearly proportional to body mass in both sexes, but gamete biomass production rate was approximately two to four orders of magnitude higher in females. In both males and females, gamete biomass production rate increased with organism mass as a power law, much like individual metabolic rate. This suggests that whole-organism energetics may act as a primary constraint on gamete production among species. Residual variation in sperm production rate was positively correlated with relative testes size. Together, these results suggest that understanding the heterogeneity in rates of gamete production among species requires joint consideration of the effects of gonad mass and metabolism

Equal fitness paradigm explained by a trade-off between generation time and energy production rate

Most plant, animal and microbial species of widely varying body size and lifestyle are nearly equally fit as evidenced by their coexistence and persistence through millions of years. All organisms compete for a limited supply of organic chemical energy, derived mostly from photosynthesis, to invest in the two components of fitness: survival and production. All organisms are mortal because molecular and cellular damage accumulates over the lifetime; life persists only because parents produce offspring. We call this the equal fitness paradigm. The equal fitness paradigm occurs because: (1) there is a trade-off between generation time and productive power, which have equal-but-opposite scalings with body size and temperature; smaller and warmer organisms have shorter lifespans but produce biomass at higher rates than larger and colder organisms; (2) the energy content of biomass is essentially constant, ~22.4 kJ g−1 dry body weight; and (3) the fraction of biomass production incorporated into surviving offspring is also roughly constant, ~10–50%. As organisms transmit approximately the same quantity of energy per gram to offspring in the next generation, no species has an inherent lasting advantage in the struggle for existence. The equal fitness paradigm emphasizes the central importance of energy, biological scaling relations and power–time trade-offs in life history, ecology and evolution

Amplified surface temperature response of cold, deep lakes to inter-annual air temperature variability

Summer lake surface water temperatures (LSWTs) have previously been shown to respond more rapidly to climatic warming compared to local summer surface air temperatures (SATs). In a global- scale analysis, we explore the factors underpinning the observation of an amplified response of summer LSWT to SAT variability using 20 years of satellite-derived temperatures from 144 lakes. We demonstrate that the degree of amplification in inter-annual summer LSWT is variable, and is greater for cold lakes (e.g. high latitude and high altitude), which are characterised by a short warming season, and deep lakes, that exhibit long correlation timescales of temperature anomalies due to increased thermal inertia. Such lakes are more likely to display responses in excess of local inter-annual summer SAT variability. Climatic modification of LSWT has numerous consequences for water quality and lake ecosystems, so quantifying this amplified response at a global scale is important