65 research outputs found

    Amanita wadulawitu (Basidiomycota), a new species from Western Australia, and an expanded description of A. kalamundae

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    A new species of Amanita Pers. is documented from Western Australia. Amanita wadulawitu L.E.McGurk, E.M.Davison & E.L.J.Watkin is described from the Perth IBRA subregion. Amanita kalamundae O.K.Mill. is redescribed to include additional collections, drawing attention to the presence of clamp connections in the lamellae and at the base of basidia. A BLASTn search has shown that there are no exact matches of the nuclear ribosomal internal transcribed spacer (ITS) region of either species in GenBank

    Neotypification and redescription of Amanita preissii (Basidiomycota), and reconsideration of the status of A. griseibrunnea

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    Amanita preissii (Fr.) Sacc. is redescribed. Re-examination of collections of A. griseibrunnea O.K.Mill. show that they do not differ significantly from A. preissii and the two species are combined. This species is common in the Perth IBRA subregion. Sequence data from the nuclear ribosomal internal transcribed spacer (ITS) region, 28S nuclear ribosomal large subunit rRNA (28S) region, RNA polymerase II (RPB2) region, β-tubulin region and translation elongation factor 1-α (EF1-α) region have been deposited in GenBank

    Integration of WiFi ToF Positioning System in the Open, Flexible and Adaptive WiSHFUL Architecture

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    We integrate a prototype WiFi Time-of-Flight (ToF) ranging and po- sitioning system in the WiSHFUL software platforms and hardware radios for experimental prototyping. Users can have access to ToF measurements as well as computed positions through uni ed pro- gramming interfaces that make possible to investigate innovative positioning and networking solutions

    Amanita drummondii and A. quenda (Basidiomycota), two new species from Western Australia, and an expanded description of A. walpolei

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    Three species of Amanita Pers. are documented from Western Australia. Amanita drummondii E.M.Davison is described from the south-west region; it appears to be widespread but infrequent. Amanita quenda E.M.Davison is described from the Perth Metropolitan area. Amanita walpolei O.K.Mill. is redescribed to include additional collections, drawing attention to the presence of clamp connections in all tissues. A BLASTn search has shown that there are no exact matches of the nuclear ribosomal internal transcribed spacer (ITS) region of each species with those in GenBank

    Mission impossible? The paradoxes of stretch goal setting

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    © 2016, © The Author(s) 2016. Stretch goal setting is a process involving multiple and nested paradoxes. The paradoxical side of stretch is attractive because it holds great promise yet dangerous because it triggers processes that are hard to control. Paradoxes are not readily managed by assuming a linear relation between the here and now and the intended future perfect. Before adopting stretch goal setting, managers should thus be prepared for the tensions and contradictions created by nested or interwoven paradoxes. Achieving stretch goals can be as difficult for the managers seeking to direct the process as for designated delegates. While the increasing popularity of stretch goal setting is understandable, its unexpected consequences must be taken into account. The inadequate use of stretch goals can jeopardize the social sustainability of organizations as well as their societal support systems

    Channel quality estimation and impairment mitigation in 802.11 networks

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    Link Level Measurements of a Wireless University Community Network

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    Multihop wireless mesh networks can provide Internet access over a wide area with minimal infrastructure expenditure. At the University of Rome Tor Vergata, we have performed an extensive measurements campaign. We have deemed crucial to lead an experimental evaluation per Mesh Link of a typical university outdoor channel because, at the best of our knowledge, no adequate model is present in the literature. Furthermore some results are fuzzy and conflicting, as quasi-independence of packet loss with respect of received signal strength (see e.g. [4]). A deeper explanation may turn into a simple characterization of the Mesh Link. Our activity has been dedicated to low level measurements which, gathered from the PHY and MAC Management Information Base (MIB) statistics, allow us to take into account channel quality, interference, and transmission/collision effectiveness. The testbed implementation is based on 802.11 a/b/g wireless interfaces that use the Atheros 5213 chipset, which are driven by the open-source Multiband Atheros Driver for Wifi (MADWiFi) [2], and we have hacked in order to extract a large amount of statistics to be used in the Mesh routing operation. The available technology enables the comparison of 802.11b PHY implementation, based on barker code at the transmitter and RAKE demodulator at the receiver, with 802.11a/g systems, where the OFDM modulator has the enormous advantage of robustness to multipath, which is commonly considered as the main reason of packet loss in outdoor channels. On the other hand 802.11b, as well as the DSSS-OFDM mode of 802.11g, may exploit the longer PHY PLCP preamble (192 µ sec) for th

    Diagonal space time Hadamard codes with erasure decoding algorithm

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    A major challenge in the area of space time (ST) codes is to find codes suitable for efficient decoding, thus overcoming the problem of many existing ST code designs which require maximum-likelihood (ML) decoding. A solution could be to apply single-input single-output (SISO) channel codes and theory over temporal channel fading to the multi-input single-output (MISO) code construction and classical suboptimum decoding methods. For these purposes, an ST code construction which allows the use of efficient decoding algorithms is described. We propose a concatenated code, where the inner code is the diagonal ST Hadamard (D-STH) code with Paley constructions and the outer code is an algebraic block code, such as a Reed-Solomon (RS) code. As a decoding method, we investigate a bounded minimum distance (BMD) with erasure decoding algorithm. A simple method to achieve the optimum threshold for deciding on an erased symbol is derived. Using this, the proposed concatenated scheme is able to exploit almost all of the spatial diversity of the system

    Location-aware MAC scheduling in industrial-like environment

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    We consider an environment strongly affected by the presence of metallic objects, that can be considered representative of an indoor industrial environment with metal obstacles. This scenario is a very harsh environment where radio communication has notorious difficulties, as metallic objects create a strong blockage component and surfaces are highly reflective. In this environment, we investigate how to dynamically allocate MAC resources in time to static and mobile users based on context awareness extracted from a legacy WiFi positioning system. In order to address this problem, we integrate our WiFi ranging and positioning system in the WiSHFUL architecture and then define a hypothesis test to declare if the link is in line-of-sight (LOS) or non-line-of-sight (NLOS) based on angular information derived from ranging and position information. We show that context information can help increase the network throughput in the above industrial-like scenario
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