54,624 research outputs found
Single- and Multi-carrier Quadrature Amplitude Modulation: Principles and Applications for Personal Communications, WATM and Broadcasting: 2nd
No full textSingle- and Multi-carrier Quadrature Amplitude Modulation Principles and Applications for Personal Communications, WLANs and Broadcasting L. Hanzo Department of Electronics and Computer Science, University of Southampton, UK W. Webb Motorola, Arlington Heights, USA formerly at Multiple Access Communications Ltd, Southampton, UK T. Keller Ubinetics, Cambridge Technology Centre, Melbourn, UK formerly at Department of Electronics and Computer Science, University of Southampton, UK Motivated by the rapid evolution of wireless communication systems, this expanded second edition provides an overview of most major single- and multi-carrier Quadrature Amplitude Modulation (QAM) techniques commencing with simple QAM schemes for the uninitiated through to complex, rapidly-evolving areas, such as arrangements for wide-band mobile channels. Targeted at the more advanced reader, the multi-carrier modulation based second half of the book presents a research-orientated outlook using a variety of novel QAM-based arrangements. * Features six new chapters dealing with the complexities of multi-carrier modulation which has found applications ranging from Wireless Local Area Networks (WLAN) to Digital Video Broadcasting (DVB) * Provides a rudimentary introduction for readers requiring a background in the field of modulation and radio wave propagation * Discusses classic QAM transmission issues relevant to Gaussian channels * Examines QAM-based transmissions over mobile radio channels * Incorporates QAM-related orthogonal techniques, considers the spectral efficiency of QAM in cellular frequency re-use structures and presents a QAM-based speech communications system design study * Introduces Orthogonal Frequency Division Multiplexing (OFDM) over both Gaussian and wideband fading channels By providing an all-encompassing self-contained treatment of single- and multi- carrier QAM based communications, a wide range of readers including senior undergraduate and postgraduate students, practising engineers and researchers alike will all find the coverage of this book attractive
Jets Signal for Higgs Particle Detection at LHC
No full textA method using jets is investigated for detecting the Higgs boson at LHC in the mass range about 114 GeV/c^2, suggested by LEP experiments. Higgs bosons are produced in association with a tt̄ pair, and both t and t̄ decay semileptonically to reduce the QCD background. After appropriate cuts, the signal is compared with the main background, tt̄ + 2 jets. This estimate, using a reasonable approximation for the dominant background tt̄gg, suggests a 5.1σ effect. This method is seen to be complimentary to the two gamma signal. The tt̄Z channel, with Z decaying to l^+ l^−, may be used to reduce theoretical uncertainties in determining the tt̄H signal
Letter from Stephen T. Mather, U.S. National Park Service to Jesse L. Boyce
No full textLetter from the Director of the National Park Service, Stephen T. Mather, to Jesse L. Boyce informing him that immediate action is being taken to remove the TNT from the Grand Canyon
DNA fusion gene vaccination mobilizes effective anti-leukemic cytotoxic T lymphocytes from a tolerized repertoire
No full textThe majority of known human tumor-associated antigens derive from non-mutated self proteins. T cell tolerance, essential to prevent autoimmunity, must therefore be cautiously circumvented to generate cytotoxic T cell responses against these targets. Our strategy uses DNA fusion vaccines to activate high levels of peptide-specific CTL. Key foreign sequences from tetanus toxin activate tolerance-breaking CD4+ T cell help. Candidate MHC class Ibinding tumor peptide sequences are fused to the C terminus for optimal processing and presentation. To model performance against a leukemia-associated antigen in a tolerized setting, we constructed a fusion vaccine encoding an immunodominant CTL epitopederived from Friend murine leukemia virus gag protein (FMuLVgag) and vaccinated tolerant FMuLVgag-transgenic (gag-Tg) mice. Vaccination with the construct induced epitopespecificIFN-c-producing CD8+ T cells in normal and gag-Tg mice. The frequency and avidity of activated cells were reduced in gag-Tg mice, and no autoimmune injury resulted. However, these CD8+ T cells did exhibit gag-specific cytotoxicity in vitro and in vivo. Also, epitope-specific CTL killed FBL-3 leukemia cells expressing endogenous FMuLVgag antigen and protected against leukemia challenge in vivo. These results demonstrate a simple strategy to engage anti-microbial T cell help to activate epitope-specific polyclonal CD8+ T cell responses from a residual tolerized repertoire
Uma metáfora do Brasil: o Bem Amado e a teledramaturgia de Dias Gomes
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Sociologia Política.O Objetivo deste trabalho consiste em procurar analisar a rede de signos e símbolos, presente no pensamento social de Dias Gomes, acerca do tema da identidade nacional, detendo-se, principalmente, na análise de sua telenovela O Bem-Amado. Na história da teledramaturgia brasileira, o folhetim é paradigmático, por representar o momento de incorporação de temas relacionados à cultura brasileira. Concomitante a esse retrato do Brasil que as telenovelas passam a veicular, a partir do final da década de 60 e início da década de 70, observamos o progressivo crescimento da Rede Globo e sua consolidação enquanto rede de abrangência nacional e importante veículo de integração nacional
Urban heat island research in Phoenix, Arizona: Theoretical contributions and policy applications
No full textabstract: This review investigates the possible reasons and motivations underpinning the large body of work, as well as summarizing specific themes, approaches, and theoretical contributions arising from such study.Corresponding Author:
Winston T. L. Chow
Arizona State University
[email protected]
Common mycorrhizal network may not facilitate plant species coexistence under very low fertility conditions
No full textHere, we assessed if the establishment of a common mycorrhizal network (CMN) could facilitate plant species coexistence and improve plant productivity. For that we conducted a mesocosms experiment to grow serradella (Ornithopus sativus Brot., a nitrogen fixing legume) and maize (Zea mays L., a C4 grass). Besides the native arbuscular mycorrhizal inoculum, we further inoculated the mesocosms with a commercial mixture of arbuscular mycorrhizal fungal spores. The establishment of a CMN (and of plant roots) was prevented by physically disrupting a potential connection between the two plant species every week. After 12 weeks of growth in a greenhouse, we measured foliar SPAD values, harvested the plants and analyzed plant biomass and mycorrhizal traits, soil organic matter and water content. Although not always significant, disturbance increased plant biomass and density, and leaf SPAD values. Also, disturbance increased the percentage of hyphae in serradella roots and tended to increase all mycorrhizal components for both species. While there were no differences in soil organic matter concentration between treatments, there was an
increase in relation to the original soil mixture. Contrary to our hypothesis, our results suggest that frequently disturbing the CMN (and plant roots) had a positive effect on plant productivity possibly by preventing plant species competition. Moreover, the increase in soil organic matter observed in all treatments highlights the crucial role that vegetation cover plays in controlling soil degradation and desertification in drylands, and in stimulating soil function and resilience
Gaussian decay for a difference of traces of the Schrödinger semigroup associated to the isotropic harmonic oscillator
No full textThis paper deals with the derivation of a sharp estimate on the difference of traces of the one-parameter Schrödinger semigroup associated to the quantum isotropic harmonic oscillator. Denoting by H_∞,κ the self-adjoint realization in L 2 (R d ), d ∈ {1, 2, 3} of the Schrödinger operator −(1/2)∆ + (1/2)κ^2*|x|^2, κ > 0 and by H_L,κ, L > 0 the Dirichlet realization in L^2(Λ^d_L) where Λ^d_L := {x ∈ R^d : −L/2 0 has a Gaussian decay in L for L sufficiently large. L The estimate we derive is sharp in the sense that its behavior when κ ↓ 0 and t ↓ 0 is similar to the one given by Tr_(L^2(R^d))*e^(−tH_∞,κ) = (2sinh((κ/2)*t))^(−d). Further, we give a simple application within the framework of quantum statistical mechanics
Economies of Scale in Queues With Sources Having Power-Law Large Deviation Scalings.
No full textWe analyse the queue Q L at a multiplexer with L sources which may display long-range dependence. This includes, for example, sources modelled by fractional Brownian Motion (fBM). The workload processes W due to each source are assumed to have large deviation properties of the form P [W t =a(t) ? x] ß e \Gammav(t)K(x) for appropriate scaling functions a and v, and ratefunction K. Under very general conditions, lim L!1 L \Gamma1 log P [Q L ? Lb] = \GammaI (b) provided the offered load is held constant, where the shape function I is expressed in terms of the cumulant generating functions of the input traffic. For power-law scalings v(t) = t v , a(t) = t a (such as occur in fBM) we analyse the asymptotics of the shape function: lim b!1 b \Gammau=a i I(b) \Gamma ffi b v=a j = u for some exponent u and constant depending on the sources. This demonstrates the economies of scale available through the multiplexing of a large number of such sources, by comparison with ..
Dimensional Crossover, the Renormalization Group and Finite Size Scaling
No full textIn this paper we review some of our recent investigations into dimensional crossover using renormaiization group arguments. We consider field theory on E = R^d × B where B is a compact space of “size” L. By employing an L dependent renormalization we obtain renormalization group equations that interpolate between the two limits L = ∞ and L = 0, the latter being equivalent to the absence of B. We consider two distinct cases: one where the interpolation is between two renormalizable theories and another where it is between a non-renormalizable theory and a renormalizable one. In the former we find that the correlation functions depend only on the scaling variable L/ξ_L where ξ_L is the correlation length on E. This is finite size scaling. The scaling variable becomes tL^(1/ν) when L/ξ_L → ∞, ξ_L → ∞, and tL^(1/ν') when ξ_L → ∞ for fixed L. Here ν and ν' are the correlation length exponents of the L = ∞ and L = 0 systems respectively and t is the mass parameter on E. The results of this paper have many applications in statistical mechanics and particle physics, e.g. liquid helium in wafer geometries, finite temperature field theory and Kaluza Klein theories
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