5,606 research outputs found

    Environmental, developmental, and genetic factors controlling root system architecture

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    A better understanding of the development and architecture of roots is essential to develop strategies to increase crop yield and optimize agricultural land use. Roots control nutrient and water uptake, provide anchoring and mechanical support and can serve as important storage organs. Root growth and development is under tight genetic control and modulated by developmental cues including plant hormones and the environment. This review focuses on root architecture and its diversity and the role of environment, nutrient, and water as well as plant hormones and their interactions in shaping root architecture

    Wide-angle elastic scattering and color randomization

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    Baryon-baryon elastic scattering is considered in the independent scattering (Landshoff) mechanism. It is suggested that for scattering at moderate energies, direct and interchange quark channels contribute with equal color coefficients because the quark color is randomized by soft gluon exchange during the hadronization stage. With this assumption, it is shown that the ratio of cross sections Rp‾p/ppR_{\overline{p} p/ p p} at CM angle θ=900\theta = 90^0 decreases from a high energy value of R_{\pbar p / pp} \approx 1/2.7, down to R_{\pbar p / pp} \approx 1/28, compatible with experimental data at moderate energies. This sizable fall in the ratio seems to be characteristic of the Landshoff mechanism, in which changes at the quark level have a strong effect precisely because the hadronic process occurs via multiple quark scatterings. The effect of color randomization on the angular distribution of proton-proton elastic scattering and the cross section ratio Rnp/ppR_{np/pp} is also discussed.Comment: 18 pages, latex2e, 4 uuencoded figures, include

    Schiff Theorem and the Electric Dipole Moments of Hydrogen-Like Atoms

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    The Schiff theorem is revisited in this work and the residual PP- and TT-odd electron--nucleus interaction, after the shielding takes effect, is completely specified. An application is made to the electric dipole moments of hydrogen-like atoms, whose qualitative features and systematics have important implication for realistic paramagnetic atoms.Comment: 3 pages. Contribution to PANIC05, Particles and Nuclei International Conference, Santa Fe, New Mexico, Oct. 24-28, 200

    Constraints on T-Odd, P-Even Interactions from Electric Dipole Moments

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    We construct the relationship between nonrenormalizable,effective, time-reversal violating (TV) parity-conserving (PC) interactions of quarks and gauge bosons and various low-energy TVPC and TV parity-violating (PV) observables. Using effective field theory methods, we delineate the scenarious under which experimental limits on permanent electric dipole moments (EDM's) of the electron, neutron, and neutral atoms as well as limits on TVPC observables provide the most stringent bounds on new TVPC interactions. Under scenarios in which parity invariance is restored at short distances, the one-loop EDM of elementary fermions generate the most severe constraints. The limits derived from the atomic EDM of 199^{199}Hg are considerably weaker. When parity symmetry remains broken at short distances, direct TVPC search limits provide the least ambiguous bounds. The direct limits follow from TVPC interactions between two quarks.Comment: 43 pages, 9 figure

    Nucleon Structure and Parity-Violating Electron Scattering

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    We review the area of strange quark contributions to nucleon structure. In particular, we focus on current models of strange quark vector currents in the nucleon and the associated parity-violating elastic electron scattering experiments from which vector- and axial-vector currents are extractedComment: 40 pages including 7 figures; review article to be published in Int. J. Mod. Phys.

    Film cooling following injection through inclined circular tubes

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    Film cooling following air injection through inclined flat plate holes into turbulent boundary laye

    The Vector Analyzing Power in Elastic Electron-Proton Scattering

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    We compute the vector analyzing power (VAP) for the elastic scattering of transversely polarized electrons from protons at low energies using an effective theory of electrons, protons, and photons. We study all contributions through second order in E/ME/M, where EE and MM are the electron energy and nucleon mass, respectively. The leading order VAP arises from the imaginary part of the interference of one- and two-photon exchange amplitudes. Sub-leading contributions are generated by the nucleon magnetic moment and charge radius as well as recoil corrections to the leading-order amplitude. Working to O(E/M)2{\cal O}(E/M)^2, we obtain a prediction for AnA_n that is free of unknown parameters and that agrees with the recent measurement of the VAP in backward angle epep scattering.Comment: 24 pages, 11 figures. Typos fixe

    A glimpse behind the organisational curtain: A dramaturgical analysis exploring the ways healthcare staff engage with online patient feedback ‘front’ and ‘backstage’ at three hospital Trusts in England

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    Healthcare staff are encouraged to use feedback from their patients to inform service and quality improvement. Receiving patient feedback via online channels is a relatively new phenomenon that has rarely been conceptualised. Further, the implications of a wide, varied and unknown(able) audience being able to view and interact with online patient feedback are yet to be understood. We applied a theoretical lens of dramaturgy to a large ethnographic dataset, collected across three NHS Trusts during 2019/2020. We found that organisations demonstrated varying levels of ‘preparedness to perform’ online, from invisibility through to engaging in public conversation with patients within a wider mission for transparency. Restrictive ‘cast lists’ of staff able to respond to patients was the hallmark of one organisation, whereas another devolved responding responsibility amongst a wide array of multidisciplinary staff. The visibility of patient-staff interactions had the potential to be culturally disruptive, dichotomously invoking either apprehensions of reputational threat or providing windows of opportunity. We surmise that a transparent and conversational feedback response frontstage aligns with the ability to better prioritise backstage improvement. Legitimising the autonomous frontstage activity of diverse staff groups may help shift organisational culture, and gradually ripple outwards a shared responsibility for transparent improvement

    PCN10 ARE FURTHER STUDIES OF BREAST CANCER TUMOR MARKERS TO DETECT RECURRENCE WORTHWHILE? A VALUE OF RESEARCH ANALYSIS

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    Cuello, Ramon (escultor)Primer pla de l'obra. Davant de la casa on vivia l'escultor a Sants hi havia hagut una fonda on paraven les diligències que unien l'interior de Catalunya amb el port de Barcelona. De metall, mesura 2,58 x 0,80 x 0,80 metres

    Photon Shot Noise Dephasing in the Strong-Dispersive Limit of Circuit QED

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    We study the photon shot noise dephasing of a superconducting transmon qubit in the strong-dispersive limit, due to the coupling of the qubit to its readout cavity. As each random arrival or departure of a photon is expected to completely dephase the qubit, we can control the rate at which the qubit experiences dephasing events by varying \textit{in situ} the cavity mode population and decay rate. This allows us to verify a pure dephasing mechanism that matches theoretical predictions, and in fact explains the increased dephasing seen in recent transmon experiments as a function of cryostat temperature. We investigate photon dynamics in this limit and observe large increases in coherence times as the cavity is decoupled from the environment. Our experiments suggest that the intrinsic coherence of small Josephson junctions, when corrected with a single Hahn echo, is greater than several hundred microseconds.Comment: 5 pages, 4 figures; includes Supporting Online Material of 6 pages with 5 figure
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