266 research outputs found

    Sea lice (Copepoda: Caligidae) from South Africa, with descriptions of two new species of Caligus

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    Thirteen species of sea lice (family Caligidae) are reported from a range of elasmobranch and actinopterygian fishes caught off South Africa or obtained from public aquaria in South Africa. Two new species of Caligus Müller, 1785 are described: C. linearis n. sp. from Pomatomus saltatrix (Linnaeus) and C. tumulus n. sp. from Chrysoblephus cristiceps (Valenciennes). A supplementary description is provided for both sexes of Caligus tetrodontis Barnard, 1948 taken from Amblyrhynchotes honckenii (Bloch) and previous records of this parasite from South African fishes are critically reviewed. It is concluded that Caligus material from Arothron hispidus Linnaeus was previously misidentified as C. tetrodontis and is in urgent need of re-examination. Morphological and molecular observations on Caligus furcisetifer Redkar, Rangnekar & Murti, 1949 indicate that this copepod is phenotypically and genetically identical to Lepeophtheirus natalensis Kensley & Grindley, 1973, and the latter becomes a junior subjective synonym of C. furcisetifer. We include new geographical distribution records for Caligus longipedis Bassett-Smith, 1898, C. rufimaculatus Wilson, 1905 and Lepeophtheirus spinifer Kirtisinghe, 1937, extending into South African waters, as well as both new distribution and host records for Alebion gracilis Wilson, 1905, Caligus dakari van Beneden, 1892 and Lepeophtheirus acutus Heegaard, 1943. The molecular analysis confirmed the monophyly of the genus Caligus. The South African species of Caligus did not cluster together, but the two included South African species of Lepeophtheirus were recovered as sister taxa

    Implementation of Multi-standard Wireless Communication Receivers in a Heterogeneous Reconfigurable System-on-Chip

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    Future mobile terminals become multi-mode communication systems. In order to handle different standards, we propose to perform baseband processing in heterogeneous reconfigurable hardware. Not only the baseband processing but also error decoding differs for every communication system. We already proposed implementations of the baseband processing part of an OFDM receiver and a Wideband CDMA receiver in a heterogeneous reconfigurable system-on-chip. The system-on-chip contains processing elements of different granularities, which includes our coarse-grained reconfigurable MONTIUM architecture. Now, we also implemented an adaptive Viterbi decoder in the same coarse-grained MONTIUM architecture. The rate, constraint length and decision depth of the decoder can be adjusted to different communication systems. We show that the flexibility in the coarse-grained reconfigurable architecture is more than 200 times as energy-efficient compared to a general purpose solution but only 24 times less efficient compared to a dedicated solution

    Mapping Wireless Communication Algorithms onto a Reconfigurable Architecture

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    Future mobile communication systems have to be flexible while adapting to environmental conditions and user demands. These systems also have to be energy-efficient as they are used in battery-operated terminals. We expect that heterogeneous reconfigurable hardware can overcome the contradicting requirements in flexibility, energy-efficiency and performance. A coarse-grain reconfigurable processor, called MONTIUM, is presented. An overview of a wireless LAN communication system, HiperLAN/2, and a Bluetooth communication system will be given. Possible implementations of these systems in heterogeneous reconfigurable hardware are discussed. Performance figures of the implemented HiperLAN/2 baseband processing in the MONTIUM architecture are presented. The required performance can be obtained at low clock frequencies with small configuration overhead. The flexibility of the MONTIUM is shown, as the baseband processing of both HiperLAN/2 and Bluetooth is implemented on the same architecture

    Butterfly Eyespot Patterns: Evidence for Specification by a Morphogen Diffusion Gradient

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    In this paper we describe a test for Nijhout's (1978, 1980a) hypothesis that the eyespot patterns on butterfly wings are the result of a threshold reaction of the epidermal cells to a concentration gradient of a diffusing degradable morphogen produced by focal cells at the center of the future eyespot. The wings of the nymphalid butterfly, "Bacilus anynana," have a series of eyespots, each composed of a white pupil, a black disc and a gold outer ring. In earlier extirpation and transplantation experiments (Nijhout 1980a, French and Brakefield, 1995) it has been established that these eyespots are indeed organized around groups of signaling cells active during the first hours of pupal development. If these cells were to supply the positional information for eyespot formation in accordance with Nijhouts diffusion-degradation gradient model, then, when two foci are close together, the signals should sum, and this effect should be apparent in the detailed shape of the resulting pigment pattern. We give an equation for the form of the contours that would be obtained in this manner. We use this to test the morphogen gradient hypothesis on measurements of the outlines of fused eyespots obtained either by grafting focal cells close together, or by using a mutation ("Spotty") that produces adjacent fused eyespots. The contours of the fused patterns were found to satisfy our equation, thus corroborating Nijhouts hypothesis to the extent possible with this particular type of experiment

    Factoring: past deze creatie van het bedrijfsleven in het civielrechtelijk keurslijf?

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    Overview of the tool-flow for the Montium Processing Tile

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    This paper presents an overview of a tool chain to support a transformational design methodology. The tool can be used to compile code written in a high level source language, like C, to a coarse grain reconfigurable architecture. The source code is first translated into a Control Data Flow Graph (CDFG). A Control Dataflow Graph contains not only the dataflow operations (e.g. arithmetic or logical operations on data) but also control flow operations (e.g. operators for loop and if then else constructs). The CDFG is minimized using a set of behavior preserving transformations such as dependency analysis, common sub-expression elimination, etc. After applying graph clustering, scheduling and allocation transformations on this minimized graph, it can be mapped onto the target architecture

    Reconfigurable Turbo/Viterbi Channel Decoder in the Coarse-Grained Montium Architecture

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    Mobile wireless communication systems become multi-mode systems. These future mobile systems employ multiple wireless communication standards, which are different by means of algorithms that are used to implement the baseband processing and the channel decoding. Efficient implementation of multiple wireless standards in mobile terminals requires energy-efficient and flexible hardware. We propose to implement both the baseband processing and channel decoding in a heterogeneous reconfigurable system-on-chip. The system-on-chip contains many processing elements of different granularities, which includes our coarse-grained reconfigurable MONTIUM architecture. We already showed the feasibility to implement the baseband processing of OFDM and WCDMA based communication systems in the MONTIUM. In this paper we implemented two kinds of channel decoders in the same MONTIUM architecture: Viterbi and Turbo decoding

    DNA barcoding of the medically important freshwater snail 'Physa acuta' reveals multiple invasion events into Africa

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    The medically important freshwater snail Physa acuta is highly invasive and has been reported in several freshwater environments across Africa. To identify species and provide initial insights into the origins of P. acuta into African freshwater environments standard molecular barcoding analyses, using the mitochondrial cytochrome c oxidase subunit I gene (COI), was performed on P. acuta isolates from Angola, Burundi and South Africa. Phylogenetic analyses of isolates from Africa could not be distinguished from P. acuta populations from other countries. Comparisons of COI sequences between isolates of P. acuta showed there to be no geographically specific clusters and the African isolates were distributed across four distinct unrelated clades suggesting several independent invasion events. Haplotype analyses indicated that there were a high number of haplotypes with low variation between them, which led to significant differences in AMOVA analyses between countries. This was further evidence of multiple invasion events suggesting multiple novel haplotypes being continually and independently introduced to each country. This approach not only provides initial insight into the invasion of Africa by P. acuta but a molecular method to monitor and manage the use of an agent of biological control
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