409 research outputs found

    Cylindrical, periodic surface lattice — theory, dispersion analysis, and experiment

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    A two-dimensional surface lattice of cylindrical topology obtained via perturbing the inner surface of a cylinder is considered. Periodic perturbations of the surface lead to observation of high-impedance, dielectric-like media and resonant coupling of surface and non-propagating volume fields. This allows synthesis of tailored-for-purpose "coating" material with dispersion suitable, for instance, to mediate a Cherenkov type interaction. An analytical model of the lattice is discussed and coupled-wave equations are derived. Variations of the lattice dispersive properties with variation of parameters are shown, illustrating the tailoring of the structure's electromagnetic properties. Experimental results are presented showing agreement with the theoretical model

    Differences in intestinal size, structure, and function contributing to feed efficiency in broiler chickens reared at geographically distant locations

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    The contribution of the intestinal tract to differences in residual feed intake (RFI) has been inconclusively studied in chickens so far. It is also not clear if RFI-related differences in intestinal function are similar in chickens raised in different environments. The objective was to investigate differences in nutrient retention, visceral organ size, intestinal morphology, jejunal permeability and expression of genes related to barrier function, and innate immune response in chickens of diverging RFI raised at 2 locations (L1: Austria; L2: UK). The experimental protocol was similar, and the same dietary formulation was fed at the 2 locations. Individual BW and feed intake (FI) of chickens (Cobb 500FF) were recorded from d 7 of life. At 5 wk of life, chickens (L1, n = 157; L2 = 192) were ranked according to their RFI, and low, medium, and high RFI chickens were selected (n = 9/RFI group, sex, and location). RFI values were similar between locations within the same RFI group and increased by 446 and 464 g from low to high RFI in females and males, respectively. Location, but not RFI rank, affected growth, nutrient retention, size of the intestine, and jejunal disaccharidase activity. Chickens from L2 had lower total body weight gain and mucosal enzyme activity but higher nutrient retention and longer intestines than chickens at L1. Parameters determined only at L1 showed increased crypt depth in the duodenum and jejunum and enhanced paracellular permeability in low vs. high RFI females. Jejunal expression of IL1B was lower in low vs. high RFI females at L2, whereas that of TLR4 at L1 and MCT1 at both locations was higher in low vs. high RFI males. Correlation analysis between intestinal parameters and feed efficiency metrics indicated that feed conversion ratio was more correlated to intestinal size and function than was RFI. In conclusion, the rearing environment greatly affected intestinal size and function, thereby contributing to the variation in chicken RFI observed across locations

    Genome-wide association studies for feedlot and growth traits in cattle

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    A genome wide-association study for production traits in cattle was carried out using genotype data from the 10K Affymetrix (Santa Clara, CA) and the 50K Illumina (San Diego, CA) SNP chips. The results for residual feed intake (RFI), BW, and hip height in 3 beef breed types (Bos indicus, Bos taurus, and B. indicus × B. taurus), and for stature in dairy cattle, are presented. The aims were to discover SNP associated with all traits studied, but especially RFI, and further to test the consistency of SNP effects across different cattle populations and breed types. The data were analyzed within data sets and within breed types by using a mixed model and fitting 1 SNP at a time. In each case, the number of significant SNP was more than expected by chance alone. A total of 75 SNP from the reference population with 50K chip data were significant (P < 0.001) for RFI, with a false discovery rate of 68%. These 75 SNP were mapped on 24 different BTA. Of the 75 SNP, the 9 most significant SNP were detected on BTA 3, 5, 7, and 8, with P ≤ 6.0 × 10 . In a population of Angus cattle divergently selected for high and low RFI and 10K chip data, 111 SNP were significantly (P < 0.001) associated with RFI, with a false discovery rate of 7%. Approximately 103 of these SNP were therefore likely to represent true positives. Because of the small number of SNP common to both the 10K and 50K SNP chips, only 27 SNP were significantly (P < 0.05) associated with RFI in the 2 populations. However, other chromosome regions were found that contained SNP significantly associated with RFI in both data sets, although no SNP within the region showed a consistent effect on RFI. The SNP effects were consistent between data sets only when estimated within the same breed type

    Urban megaprojects and water justice in Southeast Asia: Between global economies and community transitions

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    Available online 1 April 2021Within the Southeast Asian context, urban megaprojects are often delivered in aquatic or semi-aquatic contexts, transforming local hydrological systems used for sanitation, agriculture, sustenance, resource use and cultural purposes by the local populations. This paper addresses a key knowledge gap on the impacts of urban mega-projects on water security and water-related human rights in Southeast Asia through a literature review, field observations and digital earth observation. Three case studies in Cambodia, Vietnam and Myanmar were used to develop a picture of urban megaproject impacts on urban water landscapes and the human rights of local communities. The paper adapts recent human rights frameworks developed specifically for megaproject life cycles and applies them to the selected urban megaproject case studies. The seven stages in the megaproject life cycle are linked with specific accountability measures for duty bearers. Current challenges and opportunities for the global urban development community are developed in relation to water justice and megaprojects. Further the question of a just urban transition is developed to mediate between megaproject proponents and local communities in the Global South.Scott Hawken, Behnaz Avazpour, Mike S. Harris, Atousa Marzban, Paul George Munr

    The VIMOS Public Extragalactic Redshift Survey - Searching for Cosmic Voids

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    The characterisation of cosmic voids gives unique information about the large-scale distribution of galaxies, their evolution and the cosmological model. We identify and characterise cosmic voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS) at redshift 0.55 < z < 0.9. A new void search method is developed based upon the identification of empty spheres that fit between galaxies. The method can be used to characterise the cosmic voids despite the presence of complex survey boundaries and internal gaps. We investigate the impact of systematic observational effects and validate the method against mock catalogues. We measure the void size distribution and the void-galaxy correlation function. We construct a catalogue of voids in VIPERS. The distribution of voids is found to agree well with the distribution of voids found in mock catalogues. The void-galaxy correlation function shows indications of outflow velocity from the voids

    Randomised controlled trial on whether advance knowledge of prostate-specific antigen testing improves participant reporting of unprotected sex

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    To determine whether the process of informing research participants that they would be tested for the presence of a biological marker of semen exposure would reduce bias in their reports of unprotected sex

    Integrating Integrated Water Management

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    © 2014, Thomas Telford Services Ltd. All rights reserved. The water cycle is a contiguous system interconnected with human activities. Management has tended to be fragmented across anthropocentrically defined disciplines, potentially generating unintended negative consequences. The ecosystem approach and the ecosystem services framework emphasise interlinked, albeit often overlooked, benefits that the natural environment provides for people. This enables recognition and avoidance of potential ‘negative externalities’, identification of solutions optimising benefits across multiple services, and participation of wider constituencies of stakeholders. Systemic, outcome-based approaches are inherently economically efficient, yielding greater cumulative benefits for lower transaction costs by working with natural processes. The ecosystem approach establishes geographical and socio-economic contexts for management ecosystem service outcomes, providing a broader context in which to nest established water resource management methods. The ecosystem approach can also be applied at different scales and to diverse societal activities, internalising into them the value of natural processes. It is amenable to integration into catchment-scale considerations, yet does not present these activities as subsidiary to river basin planning. The addition of ecosystem services for options appraisal in preexisting decision-support tools adapts them to better address multi-benefit goals. Shifts are required in the policy and economic environment, but engineers have an important role in promoting, applying and innovating multibenefit solutions

    New Policies, New Technologies: Modelling the Potential for Improved Smear Microscopy Services in Malawi

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    Background To quantify the likely impact of recent WHO policy recommendations regarding smear microscopy and the introduction of appropriate low-cost fluorescence microscopy on a) case detection and b) laboratory workload.Methodology/Principal Findings An audit of the laboratory register in an urban hospital, Lilongwe, Malawi, and the application of a simple modelling framework. The adoption of the new definition of a smear-positive case could directly increase case detection by up to 28%. Examining Ziehl-Neelsen (ZN) sputum smears for up to 10 minutes before declaring them negative has previously been shown to increase case detection (over and above that gained by the adoption of the new case definition) by 70% compared with examination times in routine practice. Three times the number of staff would be required to adequately examine the current workload of smears using ZN microscopy. Through implementing new policy recommendations and LED-based fluorescence microscopy the current laboratory staff complement could investigate the same number of patients, examining auramine-stained smears to an extent that is equivalent to a 10 minutes ZN smear examination.Conclusions/Significance Combined implementation of the new WHO recommendations on smear microscopy and LED-based fluorescence microscopy could result in substantial increases in smear positive case-detection using existing human resources and minimal additional equipment
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