4,554 research outputs found

    On receiver design for an unknown, rapidly time-varying, Rayleigh fading channel

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    Risk to pollinators from anthropogenic electro-magnetic radiation (EMR): evidence and knowledge gaps

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    Worldwide urbanisation and use of mobile and wireless technologies (5G, Internet of Things) is leading to the proliferation of anthropogenic electromagnetic radiation (EMR) and campaigning voices continue to call for the risk to human health and wildlife to be recognised. Pollinators provide many benefits to nature and humankind, but face multiple anthropogenic threats. Here, we assess whether artificial light at night (ALAN) and anthropogenic radiofrequency electromagnetic radiation (AREMR), such as used in wireless technologies (4G, 5G) or emitted from power lines, represent an additional and growing threat to pollinators. A lack of high quality scientific studies means that knowledge of the risk to pollinators from anthropogenic EMR is either inconclusive, unresolved, or only partly established. A handful of studies provide evidence that ALAN can alter pollinator communities, pollination and fruit set. Laboratory experiments provide some, albeit variable, evidence that the honey bee Apis mellifera and other invertebrates can detect EMR, potentially using it for orientation or navigation, but they do not provide evidence that AREMR affects insect behaviour in ecosystems. Scientifically robust evidence of AREMR impacts on abundance or diversity of pollinators (or other invertebrates) are limited to a single study reporting positive and negative effects depending on the pollinator group and geographical location. Therefore, whether anthropogenic EMR (ALAN or AREMR) poses a significant threat to insect pollinators and the benefits they provide to ecosystems and humanity remains to be established

    Bringing radio into America's homes: marketing new technology in the Great Depression

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    We examine the early marketing and distribution of entertainment radio sets. Manufacturers used distribution networks to both maximize profits and create barriers to entry. Lacking the market power of auto manufacturers, they developed cooperative strategies with authorized distributors and dealers. Dealers often complained about the costly activities manufacturers required of them. However, these underpinned the dominant quality and branding competition model of the 1920s, while the Depression-era switch to a simpler radio format, sold on price, proved catastrophic for the specialist retailer

    Data retrieval in MIMO systems and the effects of correlation on the channel capacity

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    Multiple-input multiple-output (MIMO) antenna design as used in communication is today, easily the most important field in the wireless field; as capacities of data are increased based on the inherent capability of the technology, without an increase in spectrum bandwidth.This thesis analyses the ways through which data sent over some channel from a number of transmitters are recovered at the intended receivers; Maximum likelihood (ML) and Zero-forcing (ZF), are used for the data decoding; how effective these retrieval processes are and the imminent effects of correlation on the bit error rates as variants of signal to noise ratio, on the retrieved data capacities of the MIMO channels created, are all examined.This is simply very important as wireless systems continue to impact on lives globally.To drive the point home, the MIMO technology as it relates to this thesis is explicitly dissected to attempt a sound understanding of its modus operandi
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