6,938 research outputs found

    A new world survey expression for cosmic ray vertical intensity vs. depth in standard rock

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    The cosmic ray data on vertical intensity versus depth below 10 to the 5th power g sq cm is fitted to a 5 parameter empirical formula to give an analytical expression for interpretation of muon fluxes in underground measurements. This expression updates earlier published results and complements the more precise curves obtained by numerical integration or Monte Carlo techniques in which the fit is made to an energy spectrum at the top of the atmosphere. The expression is valid in the transitional region where neutrino induced muons begin to be important, as well as at great depths where this component becomes dominant

    Quantum wideband traveling-wave analysis of a degenerate parametric amplifier

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    We develop a wideband traveling-wave formalism for analyzing quantum mechanically a degenerate parametric amplifier. The formalism is based on spatial differential equations-spatial Langevin equations-that propagate temporal Fourier components of the field operators through the nonlinear medium. In addition to the parametric nonlinearity, the Langevin equations include absorption and associated fluctuations, dispersion (phase mismatching), and pump quantum fluctuations. We analyze the dominant effects of phase mismatching and pump quantum fluctuations on the squeezing produced by a degenerate parametric amplifier

    Workplace learning, contextuality and cultural texts : a case study of Taylorism in incoming customer service call centres

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    University of Technology, Sydney. Faculty of Education.The relationship between workplace contextuality and workplace learning is part of an ongoing academic, educational discourse. While enlightening in general terms, this thesis represents original research focusing more specifically on workplace learning in incoming customer service call centres. Investigating references to “revitalised Taylorism” in general terms, and “an engineering model” in specific call centre terms, the research confirms that at the core of call centre contextuality lies the adaptation of F.W. Taylor’s late 19th century Scientific Management philosophy and the call centre model for efficiency performance management. Over the passage of time this Taylorist adaptation in contemporary call centres practices grounds an argument to view incoming customer service centres as a unique ethnographical and cultural business community shaped by past practices and artifacts, folk knowledge and enduring behavioural patterns. These in turn shape workplace learning frames of reference “embodied in the signs, symbols, and language or the semiotics of culture” (Merriam & Associates 2002, p.236). The main body of the research then focuses on workplace pedagogy. It proposes that workplace artifacts become embodied in cultural texts (such as written curricula, oral/aural storytelling, semiotic language and semiotic displays) which act as teaching and learning conduits. Specific artifacts and cultural texts are examined from the perspective of Korczynski’s claim (in Deery & Kinnie 2002) that call centre performance management and measurement are infused with two logics, that of cost- efficiency and customer-orientation. The originality of the research lies in two key areas of contribution. The first is the rigour applied to situating workplace contextuality as a framework within which understandings of workplace learning can be interpreted. The second, as a consequence, is a fresh approach to workplace learning, and one which legitimises the workplace as an ethnographic, cultural community which teaches and learns through cultural texts. Examining workplace learning from this perspective raises the profile of workplace artifacts, socialisation and semiotics (including semiotic language) as significant workplace learning conduits. The thesis challenges existing understandings which act to constrain a broader interpretation of learning agencies such as literacy, culture, semiotics and texts in assigning relevant workplace meaning and knowledge constructs in their frames of reference

    Eimeria tenella protein trafficking: differential regulation of secretion versus surface tethering during the life cycle

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    Eimeria spp. are intracellular parasites that have a major impact on poultry. Effective live vaccines are available and the development of reverse genetic technologies has raised the prospect of using Eimeria spp. as recombinant vectors to express additional immunoprotective antigens. To study the ability of Eimeria to secrete foreign antigens or display them on the surface of the sporozoite, transiently transfected populations of E. tenella expressing the fluorescent protein mCherry, linked to endogenous signal peptide (SP) and glycophosphatidylinositol-anchor (GPI) sequences, were examined. The SP from microneme protein EtMIC2 (SP2) allowed efficient trafficking of mCherry to cytoplasmic vesicles and following the C-terminal addition of a GPI-anchor (from surface antigen EtSAG1) mCherry was expressed on the sporozoite surface. In stable transgenic populations, mCherry fused to SP2 was secreted into the sporocyst cavity of the oocysts and after excystation, secretion was detected in culture supernatants but not into the parasitophorous vacuole after invasion. When the GPI was incorporated, mCherry was observed on the sporozites surface and in the supernatant of invading sporozoites. The proven secretion and surface exposure of mCherry suggests that antigen fusions with SP2 and GPI of EtSAG1 may be promising candidates to examine induction of protective immunity against heterologous pathogens

    An almost Poisson structure for the generalized rigid body equations

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    In this paper we introduce almost Poisson structures on Lie groups which generalize Poisson structures based on the use of the classical Yang-Baxter identity. Almost Poisson structures fail to be Poisson structures in the sense that they do not satisfy the Jacobi identity.In the case of cross products of Lie groups, we show that an almost Poisson structure can be used to derive a system which is intimately related to a fundamental Hamiltonian integrable system — the generalized rigid body equations

    Cross-correlations between volume change and price change

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    In finance, one usually deals not with prices but with growth rates RR, defined as the difference in logarithm between two consecutive prices. Here we consider not the trading volume, but rather the volume growth rate R~\tilde R, the difference in logarithm between two consecutive values of trading volume. To this end, we use several methods to analyze the properties of volume changes R~|\tilde R|, and their relationship to price changes R|R|. We analyze 14,98114,981 daily recordings of the S\&P 500 index over the 59-year period 1950--2009, and find power-law {\it cross-correlations\/} between R|R| and R~|\tilde R| using detrended cross-correlation analysis (DCCA). We introduce a joint stochastic process that models these cross-correlations. Motivated by the relationship between R| R| and R~|\tilde R|, we estimate the tail exponent α~{\tilde\alpha} of the probability density function P(R~)R~1α~P(|\tilde R|) \sim |\tilde R|^{-1 -\tilde\alpha} for both the S\&P 500 index as well as the collection of 1819 constituents of the New York Stock Exchange Composite index on 17 July 2009. As a new method to estimate α~\tilde\alpha, we calculate the time intervals τq\tau_q between events where R~>q\tilde R>q. We demonstrate that τˉq\bar\tau_q, the average of τq\tau_q, obeys τˉqqα~\bar \tau_q \sim q^{\tilde\alpha}. We find α~3\tilde \alpha \approx 3. Furthermore, by aggregating all τq\tau_q values of 28 global financial indices, we also observe an approximate inverse cubic law.Comment: 7 pages, 5 figure

    An Optimal Control Formulation for Inviscid Incompressible Ideal Fluid Flow

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    In this paper we consider the Hamiltonian formulation of the equations of incompressible ideal fluid flow from the point of view of optimal control theory. The equations are compared to the finite symmetric rigid body equations analyzed earlier by the authors. We discuss various aspects of the Hamiltonian structure of the Euler equations and show in particular that the optimal control approach leads to a standard formulation of the Euler equations -- the so-called impulse equations in their Lagrangian form. We discuss various other aspects of the Euler equations from a pedagogical point of view. We show that the Hamiltonian in the maximum principle is given by the pairing of the Eulerian impulse density with the velocity. We provide a comparative discussion of the flow equations in their Eulerian and Lagrangian form and describe how these forms occur naturally in the context of optimal control. We demonstrate that the extremal equations corresponding to the optimal control problem for the flow have a natural canonical symplectic structure.Comment: 6 pages, no figures. To appear in Proceedings of the 39th IEEEE Conference on Decision and Contro

    Viral proteins expressed in the protozoan parasite Eimeria tenella are detected by the chicken immune system

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    BACKGROUND: Eimeria species are parasitic protozoa that cause coccidiosis, an intestinal disease commonly characterised by malabsorption, diarrhoea and haemorrhage that is particularly important in chickens. Vaccination against chicken coccidiosis is effective using wild-type or attenuated live parasite lines. The development of protocols to express foreign proteins in Eimeria species has opened up the possibility of using Eimeria live vaccines to deliver heterologous antigens and function as multivalent vaccine vectors that could protect chickens against a range of pathogens. RESULTS: In this study, genetic complementation was used to express immunoprotective virus antigens in Eimeria tenella. Infectious bursal disease virus (IBDV) causes Gumboro, an immunosuppressive disease that affects productivity and can interfere with the efficacy of poultry vaccination programmes. Infectious laryngotracheitis virus (ILTV) causes a highly transmissible respiratory disease for which strong cellular immunity and antibody responses are required for effective vaccination. Genes encoding the VP2 protein from a very virulent strain of IBDV (vvVP2) and glycoprotein I from ILTV (gI) were cloned downstream of 5’Et-Actin or 5’Et-TIF promoter regions in plasmids that also contained a mCitrine fluorescent reporter cassette under control of the 5’Et-MIC1 promoter. The plasmids were introduced by nucleofection into E. tenella sporozoites, which were then used to infect chickens. Progeny oocysts were sorted by FACS and passaged several times in vivo until the proportion of fluorescent parasites in each transgenic population reached ~20 % and the number of transgene copies per parasite genome decreased to < 10. All populations were found to transcribe and express the transgene and induced the generation of low titre, transgene-specific antibodies when used to immunise chickens. CONCLUSIONS: E. tenella can express antigens of other poultry pathogens that are successfully recognised by the chicken immune system. Nonetheless, further work has to be done in order to improve the levels of expression for its future use as a multivalent vaccine vector. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1756-2) contains supplementary material, which is available to authorized users

    Reducing The Gender Gap In The Physics Classroom

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    We investigate if the gender gap in conceptual understanding in an introductory university physics course can be reduced by using interactive engagement methods that promote in-class interaction, reduce competition, foster collaboration, and emphasize conceptual understanding. To this end we analyzed data from the introductory calculus-based physics course for non-majors at Harvard University taught traditionally or using different degrees of interactive engagement. Our results show that teaching with certain interactive strategies not only yields significantly increased understanding for both males and females, but also reduces the gender gap. In the most interactively taught courses, the pre-instruction gender gap was gone by the end of the semester. (c) 2006 American Association of Physics Teachers

    Improved Streaming Algorithms for Weighted Matching, via Unweighted Matching

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    We present a (4 + epsilon) approximation algorithm for weighted graph matching which applies in the semistreaming, sliding window, and MapReduce models; this single algorithm improves the previous best algorithm in each model. The algorithm operates by reducing the maximum-weight matching problem to a polylog number of copies of the maximum-cardinality matching problem. The algorithm also extends to provide approximation guarantees for the more general problem of finding weighted independent sets in p-systems (which include intersections of p matroids and p-bounded hypergraph matching)
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