This book provides a highly practical treatment of Glancing Angle Deposition (GLAD), a thin film fabrication technology optimized to produce precise nanostructures from a wide range of materials. ...GLAD provides an elegant method for fabricating arrays of nanoscale helices, chevrons, columns, and other porous thin film architectures using physical vapour deposition processes such as sputtering or evaporation. The book gathers existing procedures, methodologies, and experimental designs into a single, cohesive volume which will be useful both as a ready reference for those in the field and as a definitive guide for those entering it. It covers: * Development and description of GLAD techniques for nanostructuring thin films * Properties and characterization of nanohelices, nanoposts, and other porous films * Design and engineering of optical GLAD films including fabrication and testing, and chiral films * Post-deposition processing and integration to optimize film behaviour and structure * Deposition systems and requirements for GLAD fabrication * A patent survey, extensive relevant literature, and a survey of GLAD's wide range of material properties and diverse applications.
Determining diet is a key prerequisite for understanding species interactions, food web structure and ecological dynamics. In recent years, there has been considerable development in both the ...methodology and application of novel and more traditional dietary tracing methods, yet there is no comprehensive synthesis that systematically and quantitatively compares the different approaches.
Here we conceptualise diet tracing in ecology, provide recommendations for method selection, and illustrate the advantages of method integration. We summarise empirical evidence on how different methods quantify diet mixtures, by contrasting estimates of dietary proportions from multiple methods applied to the same consumer‐resource datasets, or from experimental studies with known diet compositions.
Our data synthesis revealed an urgent need for more experiential comparisons among the dietary methods. The comparison of diet quantifications from field observations showed that different techniques aligned well in cases with less than six diet items, but diverged considerably when applied to more complex diet mixtures.
Efforts are ongoing to further advance dietary estimation, including how reliably compound specific stable isotope analyses and fatty acid profiles can quantify more prey items than bulk stable isotope analyses. Similarly, DNA analyses, which can depict trophic interactions at a higher resolution than any other method, are generating new ways to better quantify diets and differentiate among life‐stages of prey. Such efforts, combined with more empirical testing of each dietary method and establishment of open data repositories for dietary data, promise to greatly advance community and ecosystem ecology.
Bayesian mixing model analyses of resource and consumer stable isotope composition are commonly used to infer elemental, energetic, and trophic pathways in aquatic and terrestrial food webs. However, ...the outputs of these models may be biased towards prior or null generalist assumptions, but the magnitude of this potential bias is unknown. I conducted a series of experiments to determine how this bias is affected by the geometry and end-member uncertainty of resource polygons. These experiments showed that bias is mostly due to isotopic overlap between resources and is very strongly cor related in a sigmoid manner with the normalized surface area of stable isotope resource polygons. The normalized surface area, a classic signal to noise ratio in bivariate space, is calculated by scaling the x and y ordinates by the mean standard deviations (SD) for δ13C and δ15N, respectively. When equilateral 3-resource polygons have a surface area <3.4 SD², the outputs of Bayesian mixing models primarily reflect the prior generalist assumption. The back-calculated bias for 85 recently published triangular polygons averaged 50 ± 28% (± SD). Analyses of regular resource polygons with 4 to 6 resources required 3.1 to 8.0 times larger normalized surface areas to constrain bias. Furthermore, polygons with 4 or more resources gave poor outcomes for minor diet components. There was a strong bias for resources similar, and against resources dissimilar, to the dominant resource. Overall, Bayesian methods applied to underdetermined models and poorly resolved data very often give results that are highly biased towards centrist and generalist solutions.
Wind is a critical driving force in hydrodynamic and water quality modeling of large shallow lakes, and is characterized by the wind drag coefficient Cd, representing the momentum transfer at the ...air‐water interface. Contemporary empirical formulae for Cd estimation were derived over oceans and some of which are solely wind velocity U10 dependent. These formulae were previously found to be inadequate in inland lake models often resulting in the water velocity underestimation. To address this problem, a physical scale experiment was designed, in which Cd was measured using a wind profile and eddy covariance methodology. A new wind‐induced wave‐dependent Cd parameterization was also established and validated in two lake studies. The driving force was modified by the wave‐dependent Cd formula in a hydrodynamic model of the shallow Upper Klamath Lake (UKL), OR, USA. The experimental Cd was negatively correlated to the wind velocity up until the critical U10 = 1.6 m s−1 which was 1.0~3.1 times previous empirical extrapolations at light winds. The variation partitioning results showed that wave parameters contributed to more than 30% of Cd variation combined with wind parameters. The modified wind stress field was spatially heterogeneous and the modeled water velocity was closer to the observations at two sites. Significant main circulation and outer bank circulation were modeled accompanied by higher surface vorticity, compared to the original UKL model. Overall, the wave‐dependent Cd formula provided an improvement of the surface flow field in the UKL model and will improve the management of the lake ecosystems.
Plain Language Summary
As a critical driving force in large shallow lakes, wind parameterization is of great importance for accurate hydrodynamic modeling. Previous wind‐dependent wind drag formulae over oceans usually generate large underestimates of water velocity in lakes. We thus propose a new wave‐dependent Cd parameterization based on an experimental study to improve the Cd parameterization in lakes. The Cd measurements were compared and confirmed by two typical methodologies of wind profile and eddy covariance. The newly derived wave‐dependent Cd parameterization was validated in two lake studies and adapted to a hydrodynamic model of the Upper Klamath Lake, OR, USA. Results showed an improved representation of the wind stress field, surface water velocity, and surface circulation. Our work should therefore be useful when using mechanistic models to manage hydrodynamics and water quality in large shallow lakes.
Key Points
A wave‐dependent Cd formula was developed based on an experimental study, indicating a negative correlation of Cd with U10 at light winds
Spatial heterogeneity of the wind stress field and surface circulation was identified in lake hydrodynamic modeling
The adaptation of Cd parameterization in a hydrodynamic model was improved through the wave‐dependent Cd formula
Lipids in Aquatic Ecosystems provides a comprehensive summary of the most recent literature on the role of lipids in aquatic systems from many world experts. Essential fatty acids (EFAs), or omega-3 ...and omega-6 fatty acids as they are known in the popular press, have garnered considerable attention in the technical and popular literature during the last decade. Lipids are important energy storage molecules in most organisms. However, equally or even more important, specific lipids (e.g. EFAs) play critical roles in a wide range of physiological processes such as regulating the structural properties of cell membranes and serving as precursors to eicosanoid signaling molecules (i.e. prostaglandins, prostacyclins, the thromboxanes and the leukotrienes). It is well established the EFAs have important impacts on human health, and it is widely agreed that the classic 'Western diet' is particularly imbalanced vis-à-vis foods containing omega-3 versus omega-6 fatty acids. But beyond the specialist literature, it is not widely known that the most physiologically important long chain, polyunsaturated omega-3 fatty acids, i.e. eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are produced de novo principally by aquatic algae. Furthermore, within aquatic ecosystems these molecules may be synthesized from precursor fatty acid molecules and/or concentrated as they are conveyed to animals consumed by humans. For example, in salmonid fish DHA and EPA constitute ~40% of total fatty acids, whereas in typical marine and freshwater phytoplankton EPA and DHA account for between 2% and 20% of total fatty acids. In humans, EPA and DHA play key roles in heart health, immune and inflammatory responses, visual acuity as well being major components of neurological tissues such as the brain and spinal cord. This realization has prompted great concern in the fisheries management community that the world's natural supply of EPA and DHA is being overexploited. There is also concern th
The ecological success of shallow water reef-building corals has been linked to the symbiosis between the coral host and its dinoflagellate symbionts (herein 'symbionts'). As mixotrophs, symbiotic ...corals depend on nutrients 1) transferred from their photosynthetic symbionts (autotrophy) and 2) acquired by host feeding on particulate organic resources (heterotrophy). However, coral species differ in the extent to which they depend on heterotrophy for nutrition and these differences are typically poorly defined. Here, a multi-tracer fatty acid approach was used to evaluate the trophic strategies of three species of common reef-building coral (Galaxea fascicularis, Pachyseris speciosa, and Pocillopora verrucosa) whose trophic strategies had previously been identified using carbon stable isotopes. The composition and various indices of fatty acids were compared to examine the relative contribution of symbiont autotrophy and host heterotrophy in coral energy acquisition. A linear discriminant analysis (LDA) was used to estimate the contribution of polyunsaturated fatty acids (PUFA) derived from various potential sources to the coral hosts. The total fatty acid composition and fatty acid indices revealed differences between the more heterotrophic (P. verrucosa) and more autotrophic (P. speciosa) coral hosts, with the coral host G. fascicularis showing overlap with the other two species and greater variability overall. For the more heterotrophic P. verrucosa, the fatty acid indices and LDA results both indicated a greater proportion of copepod-derived fatty acids compared to the other coral species. Overall, the LDA estimated that PUFA derived from particulate resources (e.g., copepods and diatoms) comprised a greater proportion of coral host PUFA in contrast to the lower proportion of symbiont-derived PUFA. These estimates provide insight into the importance of heterotrophy in coral nutrition, especially in productive reef systems. The study supports carbon stable isotope results and demonstrates the utility of fatty acid analyses for exploring the trophic strategies of reef-building corals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Brett, M.R., 2021. How important is coastal tourism for island nations? An assessment of African and Indian Ocean islands. Journal of Coastal Research, 37(3), 568–575. Coconut Creek (Florida), ISSN ...0749-0208. Coastal tourism is an important component of the global tourism industry, particularly for island nations where the tourism sector often exceeds 40% of gross domestic product. For African island and Indian Ocean island nations, the tourism sector's economic contribution has not received as much attention. This paper analyses the economic contribution of tourism to the economies of African island nations and analyzes tourism statistics from the World Travel and Tourism Council annual reports. Tourism is a major economic factor for the island nations and is concentrated in the coastal zone. The data indicates that islands with larger and more diversified economies performed better in terms of tourism receipts than did islands with less developed economies. The results show that the average per capita income on the islands is more than six-fold greater than the average for the African continent. To test the importance of the coastal zone, tourist infrastructure was mapped on two African island nations, Mauritius and the Seychelles. Given the predominance of tourist infrastructure in the coastal zone, and the importance of tourism to the economies of many of the African island nations, a rise in sea-level even of 0.5 to 1 meters poses a serious threat to the existence of these island nations.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Terrestrial organic matter inputs have long been thought to play an important role in aquatic food web dynamics. Results from recent whole lake ¹³C addition experiments suggest terrestrial ...particulate organic carbon (t-POC) inputs account for a disproportionate portion of zooplankton production. For example, several studies concluded that although t-POC only represented almost equal to20% of the flux of particulate carbon available to herbivorous zooplankton, this food source accounted for almost equal to50% of the C incorporated by zooplankton. We tested the direct dietary impact of t-POC (from the leaves of riparian vegetation) and various phytoplankton on Daphnia magna somatic growth, reproduction, growth efficiency, and lipid composition. By itself, t-POC was a very poor quality resource compared to cryptophytes, diatoms, and chlorophytes, but t-POC had similar food quality compared to cyanobacteria. Small additions of high quality Cryptomonas ozolinii to t-POC-dominated diets greatly increased Daphnia growth and reproduction. When offered alone, t-POC resulted in a Daphnia growth efficiency of 5 ± 1%, whereas 100% Cryptomonas and Scenedesmus obliquus diets resulted in growth efficiencies of 46 ± 8% (± SD) and 36 ± 3%, respectively. When offered in a 50:50 mixed diet with Cryptomonas or Scenedesmus, the t-POC fraction resulted in a partial growth efficiency of 22 ± 9% and 15 ± 6%, respectively. Daphnia that obtained 80% of their available food from t-POC assimilated 84% of their fatty acids from the phytoplankton component of their diet. Overall, our results suggest Daphnia selectively allocate phytoplankton-derived POC and lipids to enhance somatic growth and reproduction, while t-POC makes a minor contribution to zooplankton production.
Colorimetric sensing, where environmental changes are transduced into visual color changes, provides an intuitively simple yet powerful detection mechanism that is well‐suited to the realization of ...low‐cost and low‐power sensors. A new approach in colorimetric sensing exploits the structural colour of photonic crystals (PCs) to create new color‐changing materials, however much work is still required to simultaneously achieve optimized sensor response and low‐cost, scalable nanofabrication. This work responds to these challenges by designing, fabricating and evaluating a mesoporous PC sensor optimized to exhibit as large as possible color‐shift in response to small changes in relative humidity (RH). A novel design optimization is achieved by employing a colorimetric framework that translates simulated/measured spectral quantities into numeric color values directly related to color perception. The sensor design is then realized using a mesoporous TiO2 PC, fabricated using glancing angle deposition (GLAD). The GLAD technique is a bottom‐up, single‐step nanofabrication method providing the nanoscale precision required to successfully realize the optimized PC design. The PC sensor is shown to be highly sensitive and stable: the PC structural‐color changes visibly due to RH changes smaller than 1%, and the response is stable over hundreds of hours of sensor operation. Additionally, measurements and simulations are used to reveal the important link between the PC optical modes, pore geometry, and sensor response which will be useful in future PC sensor experiments. The combination of bottom‐up nanofabrication with visible color‐based sensing, coupled with the useful design methodology, will lead to further developments in low‐cost, widely deployable optical sensors.
The structural color of mesoporous photonic crystals (PCs) is highly sensitive to environmental changes, making them ideally suited as optical sensors. Here, this effect is exploited in the nanofabrication and characterization of an optimized PC design for humidity sensing. The sensor performance is excellent and the new quantitative analysis methods developed will be useful for future color‐based sensor design.
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