290 research outputs found

    Developing Walvis Bay Port into a logistics gateway for southern Africa: Issues, challenges and the potential implications for Namibia’s future

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    Many developing countries wish to become the ‘gateway’ to a region or part of a continent.One strategy involves encouraging logistics cluster development. These hubs support global supply chains and may enable the economic growth of the host country through the resulting trade, as well as providing direct and indirect employment opportunities during the build and subsequent operation of the hub. Namibia intends to develop the Port of Walvis Bay to be come the preferred gateway to southern Africa and the Southern African Development Community region. This article builds on research on Caribbean cluster potential and Namibian logistics to identify the potential benefits and impact on development, as well as the drawbacks and risks of such a strategy

    A One-Pass Extended Depth of Field Algorithm Based on the Over-Complete Discrete Wavelet Transform

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    In this paper we describe an algorithm for extended depth of field (EDF) imaging based on the over-complete discrete wavelet transform (OCDWT). We extend previous approaches by describing a, potentially real-time, algorithm that produces the EDF image after a single pass through the "stack" of focal plane images. In addition, we specifically study the effect of over-sampling on EDF reconstruction accuracy and show that a small degree of over-sampling considerably improves the quality of the EDF image

    Registration evaluation of dynamic breast MR images

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    The interpretation of dynamic contrast-enhanced breast MR images is predicated on the assumption of minimal voxel movement during the time course of the image acquisition. Misalignment of the dynamic image sequence as a result of movement during image acquisition can lead to potentially misleading diagnostic conclusions. In this paper a new methodology is presented for assessing the degree of in-plane (intra-slice) movement in a dynamic image sequence. The method is demonstrated on data from six subjects. The conclusion is that the method makes it possible to quantitatively qualify the accuracy of computed enhancement curves and more importantly to identify unacceptably poor registration

    Ecology, conservation, and phylogenetic position of the Madagascar Jacana Actophilornis albinucha

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    The Madagascar Jacana Actophilornis albinucha (Jacanidae) is an endemic shorebird found in the threatened wetlands of western Madagascar. This species is presumed to exhibit classical polyandry; however, few data are available to support that assumption. More generally, a lack of basic understanding of this species hinders conservation efforts. We conducted the most extensive study of the Madagascar Jacana to date, and report on its: 1) distribution, population size and density; 2) degree of sexual size dimorphism; and 3) phylogenetic position. The surveys were conducted at 54 lakes, between January and October in 2016. Madagascar Jacana were found at 22 lakes, and within these were distributed at a mean density of 3.5 ± 0.74 [SE] individuals per hectare of surveyed habitat. We estimate the global population size to be between 975 and 2 064 individuals, and habitat destruction appears to be the main threat to the species. Females were significantly larger than males, consistent with reports for other Jacanidae species. Using a mitochondrial DNA fragment, we expanded the Jacanidae genetic phylogeny, and confirmed that Madagascar Jacana is the sister species to the African Jacana Actophilornis africanus. Further studies are urgently needed to thoroughly re-assess the threat status and population trend of the Madagascar Jacana

    The Tully-Fisher relation of galaxies at z~0.85 in the DEEP2 survey

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    Local and intermediate redshift (z~0.5) galaxy samples obey well correlated relations between the stellar population luminosity and maximal galaxy rotation that define the Tully-Fisher (TF) relation. Consensus is starting to be reached on the TF relation at z~0.5, but work at significantly higher redshifts is even more challenging, and has been limited by small galaxy sample sizes, the intrinsic scatter of galaxy properties, and increasing observational uncertainties. We present here the TF measurements of 41 galaxies at relatively high redshift, spectroscopically observed with the Keck/DEIMOS instrument by the DEEP2 project, a survey which will eventually offer a large galaxy sample of the greatest depth and number yet achieved towards this purpose. The 'first-look' sample analyzed here has a redshift range of 0.75= 0.85 and an intrinsic magnitude range from M_B of -22.66 to -20.57 (Vega). We find that compared to local fiducial samples, a brightening of 1.5 magnitudes is observed, and consistent with passive evolutionary models.Comment: Accepted for publication in MNRAS. 2 tables, 4 figure

    Galaxy And Mass Assembly (GAMA) : refining the local galaxy merger rate using morphological information

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    KRVS acknowledges the Science and Technology Facilities Council (STFC) for providing funding for this project, as well as the Government of Catalonia for a research travel grant (ref. 2010 BE-00268) to begin this project at the University of Nottingham. PN acknowledges the support of the Royal Society through the award of a University Research Fellowship and the European Research Council, through receipt of a Starting Grant (DEGAS-259586).We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass-dependent merger fraction and merger rate using galaxy pairs and the CAS (concentration, asymmetry, and smoothness) structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to M* = 108 M⊙ with mass ratios of 4:1) the lower mass companion becomes highly asymmetric, whereas the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass-dependent major merger fraction is fairly constant at ∼1.3–2 per cent within 109.5 < M* < 1011.5 M⊙, and increases to ∼4 per cent at lower masses. When the observability time-scales are taken into consideration, the major merger rate is found to approximately triple over the mass range we consider. The total comoving volume major merger rate over the range 108.0 < M* < 1011.5 M⊙ is (1.2 ± 0.5) × 10−3 h370 Mpc−3 Gyr−1.Publisher PDFPeer reviewe
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