2,669 research outputs found

    Summary of Coral Cay Conservation's habitat mapping data from Utila, Honduras

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    IIThe coral reefs of Honduras are of vital national and international importance,both ecologically and economically, but are threatened because of rapid economicand population growth.? During work on Utila between 1999 and 2000 (the ?Bay Islands 2000? project),Coral Cay Conservation developed a programme of surveys, training andconservation education aimed at assessing the status of local reefs and improvingenvironmental awareness amongst neighbouring communities.? This summary report provides an overview of the habitat mapping data collectedby the Bay Islands 2000 project.? CASA provided software, hardware and skills, on a charitable basis to ensure thatthe data collected by CCC could be developed into a GIS, not only for mappingthe status of the coral reefs of Honduras, but also to provide analysis of the aerialextent of these reefs.? Data were collected within individual ?study areas?, to facilitate analysis at a rangeof spatial scales, and utilised the CCC standard baseline survey technique for therapid assessment of the characteristics of reef communities. The surveys,therefore, utilised a series of transects, perpendicular to the reef.? Baseline transects discriminated nine benthic and six geomorpholgical classeswhich indicates Utila has a high habitat diversity. Habitat diversity is importantsince the number of habitat types has been shown to be a good representation ofspecies biodiversity.? The nine benthic classes that were distinguished were all relatively coral poorbecause of a suite of relatively long-term local and regional factors, exacerbatedby the combination of Hurricane Mitch and coral bleaching in 1995 and 1998.? Damselfish were the most abundant reef associated fish recorded during baselinetransect surveys. Commercially important fish were less abundant that wouldnormally be expected in unfished systems.? A recurring pattern in the baseline transect data was the greater abundance anddiversity of fish in coral rich classes. However, although the link between fishabundance and coral cover was clear, not all species were necessarily mostabundant in the most coral rich areas.? Invertebrates were generally uncommon, partly because of fishing pressure, andthe abundances of many invertebrate taxa were correlated with coral cover.? A habitat map is presented within this report as an indication of the distribution ofhabitat types around Utila.? Using the map, estimates of areal extents of each benthic class and habitat type areinstructive. For example, there is only approximately 27 km2 of reefal habitatsaround Utila. Furthermore, the area supporting the most coral rich benthic classesis only approximately 4 km2 (15%). These statistics both highlight the damagecaused by the bleaching event and Hurricane Mitch and other anthropogenicimpacts and the need to conserve remaining coral rich areas.? If further reserves were to be created, it would be important to try to protect arange of reef and habitat types. For this reason, it appears that the Turtle HarbourWildlife Refuge is well placed since this areas includes a wide range of habitattypes. However, placement of reserves in Utila should favour relatively coral richhabitats over sand dominated areas.? This study led to six recommendations:Summary Utila habitat mapping reportIII? One or more agencies should collect additional ground-truthing data fromaround Utila to facilitate both classification of currently ?Unknown? polygonsand an accuracy assessment of the map.? Establish an integrated GIS and associated meta-database for Utila, includingdata from the Bay Islands 2000 project.? Examine the potential of using data collected by the Bay Islands 2000 projectas the basis of national habitat classification scheme and subsequent nationalhabitat map.? Continue to aim to establish one or more additional multiple use marineprotected areas around Utila, with an integrated monitoring programme tomeasure their efficacy, and strengthen the enforcement of regulations in theTurtle Harbour Wildlife Sanctuary. Establish regulations, and enforce existinglegislation, to minimise the detrimental effects of coastal development on reefhealth.? Additional marine reserves in Utila should integrate factors such as thepreference of many fish species for coral rich habitats and the protection ofareas incorporating a range of habitat types, including mangroves and seagrassbeds, in order to allow for nursery areas, ontogenetic shifts and species thatrely on non-coral rich habitats. The corollary of the preference of fish speciesfor coral rich habitats is to protect coral cover within the reserves.? The reef on the south coast of Utila appears to be a good candidate forprotection because it is relatively sheltered from storm and hurricane damage

    Maintaining Seed Quality of Maize and Wheat through Dry Chain Technology in Pakistan

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    Seed is inevitably deteriorated during storage and higher seed moisture content is the primary cause of this decline in seed quality. Dry Chain is a valuable tool, by using moisture proof hermetic containers to preserve seed quality throughout supply chain. This study evaluated and compared the performance of wheat and maize seed in different hermetic storage packaging (Super bag, Anaaji bag and drum) with conventionally used woven polypropylene bags after six months storage in ambient conditions. Seed moisture content was increased up to 11.53 and 13.55% in wheat and maize respectively when packed in polypropylene bags while it remained low (approximately 10 and 11.4% in wheat and maize respectively) when packed in hermetically sealed bags and drum. Germination was maintained in both cereal seeds stored in hermetically sealed Super bag, anaaji bag and drum while it reduced in polypropylene bags as compared to initial seed quality. Seed stored in polypropylene bag deteriorated quickly, which resulted in loss of seed vigour as indicated by higher malondialdehyde contents and electrical conductivity of seed leachates. It can be concluded that maintenance of seed dryness with hermetic storage is useful in preservation of seed quality and related attributes under high relative humidity environment

    Multi-objective optimisation for minimum quantity lubrication assisted milling process based on hybrid response surface methodology and multi-objective genetic algorithm

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    © 2019 by SAGE Publications Ltd.Parametric modelling and optimisation play an important role in choosing the best or optimal cutting conditions and parameters during machining to achieve the desirable results. However, analysis of optimisation of minimum quantity lubrication–assisted milling process has not been addressed in detail. Minimum quantity lubrication method is very effective for cost reduction and promotes green machining. Hence, this article focuses on minimum quantity lubrication–assisted milling machining parameters on AISI 1045 material surface roughness and power consumption. A novel low-cost power measurement system is developed to measure the power consumption. A predictive mathematical model is developed for surface roughness and power consumption. The effects of minimum quantity lubrication and machining parameters are examined to determine the optimum conditions with minimum surface roughness and minimum power consumption. Empirical models are developed to predict surface roughness and power of machine tool effectively and accurately using response surface methodology and multi-objective optimisation genetic algorithm. Comparison of results obtained from response surface methodology and multi-objective optimisation genetic algorithm depict that both measured and predicted values have a close agreement. This model could be helpful to select the best combination of end-milling machining parameters to save power consumption and time, consequently, increasing both productivity and profitability.Peer reviewedFinal Published versio

    Antigenotoxic and anticlastogenic potential of Agaricus bisporus against MMS induced toxicity in human lymphocyte cultures and in bone marrow cells of mice

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    The aim of the present study is to evaluate, for the first time, antigenotoxic potential of Agaricus bisporus against methyl methanesulphonate induced toxicity in human lymphocyte culture in vitro and in bone marrow cells of albino mice in vivo. The parameters studied included total aberrant cells and the frequencies of aberrations in the bone marrow cells at three exposure durations viz., 16, 24 and 32 h, and for the in vitro method using chromosomal aberrations, sister chromatid exchanges and replication indices as markers. The alcoholic extract of A. bisporus was taken in five increasing concentrations of 200, 250, 300, 350 and 400 mg/kg body weight for three in vivo exposure durations viz., 16, 24 and 32 h. Similarly, four doses of extracts viz., 150, 200, 250 and 300 lg/ ml of culture were taken for in vitro durations of 24, 48 and 72 h in the presence as well as the absence of S9-mix. The treatment reduced the total number of aberrant cells ranging from 10.0% to 46.15% and it reduced the total frequencies of aberrations ranging from 198 to 96 against very high aberrations i.e., 227 caused due to methyl methanesulphonate in vivo. The same trends were observed in the in vitro experiments i.e., it reduced chromosomal aberrations from (42.00%, 71.25%, and 83.00% to 20.00%, 39.50%, and 43.00%) at 24, 48, and 72 h of exposure respectively. However when experiments were carried out in the presence of liver S9 fraction, these values were respectively 52.38, 44.56, and 48.34% significant at <0.05 level, likewise it also reduced sister chromatid exchanges from 14.86 ± 1.44 down to 8.84 ±0.75 per cell, whereas the replication index got enhanced from 1.45 to 1.64

    Overview of the JET results in support to ITER

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    The 2014–2016 JET results are reviewed in the light of their significance for optimising the ITER research plan for the active and non-active operation. More than 60 h of plasma operation with ITER first wall materials successfully took place since its installation in 2011. New multi-machine scaling of the type I-ELM divertor energy flux density to ITER is supported by first principle modelling. ITER relevant disruption experiments and first principle modelling are reported with a set of three disruption mitigation valves mimicking the ITER setup. Insights of the L–H power threshold in Deuterium and Hydrogen are given, stressing the importance of the magnetic configurations and the recent measurements of fine-scale structures in the edge radial electric. Dimensionless scans of the core and pedestal confinement provide new information to elucidate the importance of the first wall material on the fusion performance. H-mode plasmas at ITER triangularity (H = 1 at βN ~ 1.8 and n/nGW ~ 0.6) have been sustained at 2 MA during 5 s. The ITER neutronics codes have been validated on high performance experiments. Prospects for the coming D–T campaign and 14 MeV neutron calibration strategy are reviewed.European Commission (EUROfusion 633053

    On the Analysis of Cellular Networks with Caching and Coordinated Device-to-Device Communication

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    In this paper, we develop a comprehensive analytical framework for cellular networks that are enhanced with coordinated device-to-device (D2D) communication, where the D2D devices are equipped with content caching capabilities. The base station (BS) coordinates the D2D communication by establishing a D2D link between the requesting user and the nearest D2D helper within the same cell if the latter contains the requested content, otherwise, the BS serves the user itself. The motivation behind restricting D2D pairs within a macro cell is to make coordinated D2D communication realizable as the BS can keep track of the content of the devices without the increased overhead of inter-BS coordination. This approach is similar to LTE direct, where D2D pairing is managed by the BS. We model the locations of BS and D2D helpers using a homogeneous Poisson point process (HPPP). The distribution of the distance between the tagged user and its neighboring D2D helper within the cell is derived using disk approximation for the Voronoi cell, which is shown to be reasonably accurate. We fully characterize the cellular and D2D coverage and the link spectral efficiency of such a network. Our results reveal that cache enabled D2D communication becomes more effective as the requesting user moves away from the BS and high performance gains can be achieved compared to conventional cellular networks, especially when the popularity distribution is skewed and most popular files are requested

    EFFECT OF NON-ENZYMATIC ANTIOXIDANTS IN EXTENDER ON POST-THAW QUALITY OF BUFFALO (BUBALUS BUBALIS) BULL SPERMATOZOA

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    The objective of the present study was to determine the effect of non-enzymatic antioxidants (vitamin C or E) in tris-citric acid buffer (TCA) on post-thaw quality of buffalo (Bubalus bubalis) bull spermatozoa. Split pooled buffalo bull ejaculates were diluted in TCA egg yolk glycerol extender containing either vitamin C (TCAC), vitamin E (TCAE) or without antioxidant (TCAN) at 37°C. Extended semen was cooled to 4C in 2 h and equilibrated for 4 h at 4C. Cooled semen was then filled in 0.5 ml straws at 4C and frozen in programmable cell freezer. Thawing of semen was performed at 37°C for 30 seconds. Sperm motility, plasma membrane integrity and sperm morphology (acrosome integrity, head, mid-piece and tail abnormalities) of each semen sample were evaluated. Percentage of post-thaw spermatozoal motility assessed visually at 0 and 6 h and the post-thaw percentage of spermatozoa with intact plasma membranes at 0 h were higher (P<0.05) with TCAC and TCAE compared to control. However, the differences in both these parameters between the former two groups was non significant. The post-thaw percentage of spermatozoa with normal acrosomes was higher (P<0.05) in TCAE extender than control. Mean sperm abnormalities in samples cryopreserved with extender having TCAC, TCAE or TCAN were similar (P>0.05). In conclusion, non-enzymatic antioxidants, particularly vitamin E, in the tris citric acid extender may improve the quality of frozen-thawed buffalo bull spermatozoa

    Effective link quality estimation as a means to improved end-to-end packet delivery in high traffic mobile ad hoc networks

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    Accurate link quality estimation is a fundamental building block in quality aware multi hop routing. In an inherently lossy, unreliable and dynamic medium such as wireless, the task of accurate estimation becomes very challenging. Over the years ETX has been widely used as a reliable link quality estimation metric. However, more recently it has been established that under heavy traffic loads ETX performance gets significantly worse. We examine the ETX metric's behavior in detail with respect to the MAC layer and UDP data; and identify the causes of its unreliability. Motivated by the observations made in our analysis, we present the design and implementation of our link quality measurement metric xDDR – a variation of ETX. This article extends xDDR to support network mobility. Our experiments show that xDDR substantially outperforms minimum hop count, ETX and HETX in terms of end-to-end packet delivery ratio in static as well as mobile scenarios.</p
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