210 research outputs found

    Local Positioning Services on IEEE 802.11 Networks

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    This paper deals with localization services in IEEE 802.11 networks, for indoor environment. The proposed solution processes the Time Of Arrival of location packets sent by a Mobile Terminal, that makes access in a IEEE 802.11 network. A set of Location Supporting Nodes and a Location Support Server composes an indoor location services architecture. A fully compatible IEEE 802.11 Localization Services protocol supporting data exchange related to both TOA measurement and processing is reported. Simulation results show the method efficiency in both IEEE 802.11 PCF and DCF modes. Assessment of the maximum number of users for which location services can be provided is also reported. Since high localization accuracy requires large bandwidth, a broadband antenna for LSN and LSS was designed. The related results are reported in the second part of the paper. The antenna works at 5.0 GHz (centre frequency) in broadband mode and is matched on the wireless operating frequencies with a percentage more than 8% (1:1.5 VSWR)

    Extrafloral-nectar based partner manipulation in plant-ant relationship

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    Plant–ant interactions are generally considered as mutualisms, with both parties gaining benefits from the association. It has recently emerged that some of these mutualistic associations have, however, evolved towards other forms of relationships and, in particular, that plants may manipulate their partner ants to make reciprocation more beneficial, thereby stabilizing the mutualism. Focusing on plants bearing extrafloral nectaries, we review recent studies and address three key questions: (i) how can plants attract potential partners and maintain their services; (ii) are there compounds in extrafloral nectar that could mediate partner manipulation; and (iii) are ants susceptible to such compounds? After reviewing the current knowledge on plant–ant associations, we propose a possible scenario where plant-derived chemicals, such as secondary metabolites, known to have an impact on animal brain, could have evolved in plants to attract and manipulate ant behaviour. This new viewpoint would place plant–animal interaction in a different ecological context, opening new ecological and neurobiological perspectives of drug seeking and use

    Experimental Detection of Entanglement with Polarized Photons

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    We report on the first experimental realization of the entanglement witness for polarization entangled photons. It represents a recently discovered significant quantum information protocol which is based on few local measurements. The present demonstration has been applied to the so-called Werner states, a family of ''mixed'' quantum states that include both entangled and non entangled states. These states have been generated by a novel high brilliance source of entanglement which allows to continuously tune the degree of mixedness

    The Libyan collections in FI (Herbarium Centrale Italicum and Webb Herbarium) and studies on the Libyan Flora by R. Pampanini - Part 2

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    This work is the continuation of Part 1, published in 2015, and comprises the reconstruction of the original collections of new taxa described by R. Pampanini and other botanists and, where possible, typification of the new names and taxonomical updating. The material studied for the most part concerns Libyan specimens held in the FI and FI-W herbaria but in some case also K, LD, MPU, P, PAD, PAL, ULT. Other material, which Pampanini studied in Florence was subsequently conserved in other herbaria. Specimens belonging to 21 families have been examined, from the Najadaceae to Zygophyllaceae. As well as typification, bibliographical data have been provided for those already typified. In this second part, a total of 113 names have been indexed and 91 typified, taking the names validly published in the entire work to 353, of which 286 are typified. Also on this occasion, we have provided taxonomic updates for each taxon. The Conclusions present a synthetic sum of the taxa still recognised taxonomically (entirely, in new combinations, or with a new status) in recent works on the Flora of N. Africa, in general revisions of various systematic groups, or reconsidered by the authors of this present work. We have also investigated the phyto-geographic origins of the taxa [according to the dominions proposed by Quézel (1978) for N. Africa]. Finally we have very briefly indicated the presence of material of the R. Pampanini collections (for Cyrenaica, together with R. E. G. Pichi Sermolli in 1934) in the most important herbaria. The paragraph "Addenda et Corrigenda" has been added to the final part of the treatise and relates chiefly to taxa omitted from the first part, either on account of new information or as a result of errors which came to light after publication

    Notulae to the Italian alien vascular flora: 4

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    In this contribution, new data concerning the Italian distribution of alien vascular flora are presented. It includes new records and exclusions for Italy or for Italian administrative regions of taxa in the genera Cedrus, Cenchrus, Citrus, Cyrtomium, Diospyros, Elaeagnus, Erigeron, Iris, Oenothera, Pavonia, Phytolacca, Styphnolobium, and Verbena. Furthermore, a new combination in the genus Amaranthus is proposed

    Notulae to the Italian alien vascular flora: 2

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    In this contribution, new data concerning the Italian distribution of alien vascular flora are presented. It includes new records, exclusions and confirmations for Italy or for Italian administrative regions for taxa in the genera Ageratum, Aster, Buddleja, Cedrus, Centranthus, Cephalotaxus, Clerodendrum, Cotoneaster, Cyperus, Honorius, Lantana, Ligustrum, Morus, Muscari, Oenothera, Opuntia, Platycladus, Plumbago, Pseudotsuga, Sedum, Sporobolus, Stachys, Ulmus and Yucca. A nomen novum, Stachys talbotii, is proposed as a replacement name for Sideritis purpurea

    Notulae to the Italian alien vascular flora: 2

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    In this contribution, new data concerning the Italian distribution of alien vascular flora are presented. It includes new records, exclusions and confirmations for Italy or for Italian administrative regions for taxa in the genera Ageratum, Aster, Buddleja, Cedrus, Centranthus, Cephalotaxus, Clerodendrum, Cotoneaster, Cyperus, Honorius, Lantana, Ligustrum, Morus, Muscari, Oenothera, Opuntia, Platycladus, Plumbago, Pseudotsuga, Sedum, Sporobolus, Stachys, Ulmus and Yucca. A nomen novum, Stachys talbotii, is proposed as a replacement name for Sideritis purpurea
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