18,190 research outputs found

    Human Schistosome Infection and Allergic Sensitisation

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    Several field studies have reported an inverse relationship between the prevalence of helminth infections and that of allergic sensitisation/atopy. Recent studies show that immune responses induced by helminth parasites are, to an extent, comparable to allergic sensitisation. However, helminth products induce regulatory responses capable of inhibiting not only antiparasite immune responses, but also allergic sensitisation. The relative effects of this immunomodulation on the development of protective schistosome-specific responses in humans has yet to be demonstrated at population level, and the clinical significance of immunomodulation of allergic disease is still controversial. Nonetheless, similarities in immune responses against helminths and allergens pose interesting mechanistic and evolutionary questions. This paper examines the epidemiology, biology and immunology of allergic sensitisation/atopy, and schistosome infection in human populations

    The Green Entrepreneur: Visionary, Maverick or Opportunist?

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    Given the importance of green entrepreneurs in the transition towards a truly sustainable society, this paper proposes frameworks for investigating the motives of entrepreneurs who set up green businesses. Different perceptions of 'green' are explored and although the paper focuses particularly on 'green-green' businesses, the scope for investigation encompasses all possible forms of green start-ups. The main approach taken in the paper is to review the literature on entrepreneurs generally, and approaches to classifying entrepreneurs with a view to gaining useful insights for the green context. An exploratory typology of green entrepreneurs is proposed, which has been adapted and developed from Thompson's four dimensions of entrepreneurship (1998). The terms 'ethical maverick', 'ad hoc environpreneur', 'visionary champion' and 'innovative opportunist' are coined to describe different motives or orientations of the green entrepreneur. Frameworks are proposed to investigate the motives of, and influences on, green entrepreneurs. The ultimate aim is to gain insights for policy makers and educators into ways to foster green entrepreneurship.entrepreneurship, sustainability, green, start-ups, motivation, typology

    \u3ci\u3eWANDERSONG\u3c/i\u3e (RUBIACEAE), A NEW GENUS FROM THE GREATER ANTILLES

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    A revision of Chione DC. (Rubiaceae) has excluded two species, C. exserta (DC.) Urb. and C. seminervis Urb. & Ekman, from the genus on the basis of morphology. The designation Colleteria D.W. Taylor was proposed to house these species, but it was invalidly published. The new genus Wandersong D.W. Taylor is here erected to accommodate these two species. The new combinations Wandersong exserta (DC.) D.W. Taylor and Wandersong seminervis (Urb. & Ekman) D.W. Taylor are here effected under this new generic name. The new genus name Wandersong D.W. Taylor honors two Andersons, Dr. Gregory J. Anderson and Dr. William R. Anderson, for their outstanding and influential achievements in the field of botany. The name Wandersong is constructed with the surname Anderson shared between the first initials of these two botanists

    Determinants of Red Meat Trade Flows

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    International Relations/Trade,

    Matrix embeddings on flat R3R^3 and the geometry of membranes

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    We show that given three hermitian matrices, what one could call a fuzzy representation of a membrane, there is a well defined procedure to define a set of oriented Riemann surfaces embedded in R3R^3 using an index function defined for points in R3R^3 that is constructed from the three matrices and the point. The set of surfaces is covariant under rotations, dilatations and translation operations on R3R^3, it is additive on direct sums and the orientation of the surfaces is reversed by complex conjugation of the matrices. The index we build is closely related to the Hanany-Witten effect. We also show that the surfaces carry information of a line bundle with connection on them. We discuss applications of these ideas to the study of holographic matrix models and black hole dynamics.Comment: 41 pages, 3 figures, uses revtex4-1. v2: references added, corrected an error in attribution of idea

    Theory and Implementation of RF-Input Outphasing Power Amplification

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    Conventional outphasing power amplifier systems require both a radio frequency (RF) carrier input and a separate baseband input to synthesize a modulated RF output. This work presents an RF-input/RF-output outphasing power amplifier that directly amplifies a modulated RF input, eliminating the need for multiple costly IQ modulators and baseband signal component separation as in previous outphasing systems. An RF signal decomposition network directly synthesizes the phase- and amplitude-modulated signals used to drive the branch power amplifiers (PAs). With this approach, a modulated RF signal including zero-crossings can be applied to the single RF input port of the outphasing RF amplifier system. The proposed technique is demonstrated at 2.14 GHz in a four-way lossless outphasing amplifier with transmission-line power combiner. The RF decomposition network is implemented using a transmission-line resistance compression network with nonlinear loads designed to provide the necessary amplitude and phase decomposition. The resulting proof-of-concept outphasing power amplifier has a peak CW output power of 93 W, peak drain efficiency of 70%, and performance on par with a previously-demonstrated outphasing and power combining system requiring four IQ modulators and a digital signal component separator

    An RF-input outphasing power amplifier with RF signal decomposition network

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    This work presents an outphasing power amplifier that directly amplifies a modulated RF input. The approach eliminates the need for multiple costly IQ modulators and baseband signal component separation found in conventional outphasing power amplifier systems, which have previously required both an RF carrier input and a separate baseband input to synthesize a modulated RF output. A novel RF signal decomposition network enables direct RF-input / RF-output outphasing by directly synthesizing the phase- and amplitude-modulated RF signals that drive the branch PAs from the modulated RF input waveform. The technique is demonstrated at 2.14 GHz in a four-way lossless outphasing amplifier system with transmission-line-based power combiner. The resulting proof-of-concept outphasing power amplifier has a peak CW output power of 95 W, and peak drain efficiency of 72%
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