15,221 research outputs found

    Bound-state/elementary-particle duality in the Higgs sector and the case for an excited 'Higgs' within the standard model

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    Though being weakly interacting, QED can support bound states. In principle, this can be expected for the weak interactions in the Higgs sector as well. In fact, it has been argued long ago that there should be a duality between bound states and the elementary particles in this sector, at least in leading order in an expansion in the Higgs condensate. Whether this remains true beyond the leading order is investigated using lattice simulations, and support is found. This provides a natural interpretation of peaks in cross sections as bound states. Unambiguously, this would imply the existence of (possibly very broad) resonances of Higgs and W and Z bound states within the standard model.Comment: 15 pages, 3 figures v2: added appendix with technical details, some minor improvement

    Attractive internal wave patterns

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    This paper gives background information for the fluid dynamics video on internal wave motion in a trapezoidal tank.Comment: 2 pg, movie at two resolutions _low(Low-resolution) and _hr(High-resolution

    Meridional trapping and zonal propagation of inertial waves in a rotating fluid shell

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    Inertial waves propagate in homogeneous rotating fluids, and constitute a challenging and simplified case study for the broader class of inertio-gravity waves, present in all geophysical and astrophysical media, and responsible for energetically costly processes as diapycnal and angular momentum mixing. However, a complete analytical description and understanding of internal waves in arbitrarily shaped enclosed domains, such as the ocean, or a planet liquid core, is still missing. In this work, the inviscid, linear inertial wave field is investigated by means of three dimensional ray tracing in spherical shell domains, having in mind possible oceanographic applications. Rays are here classically interpreted as representative of energy paths. But in contrast with previous studies, they are now launched with a non-zero initial zonal component allowing for a more realistic, localized forcing, and the development of azimuthal inhomogeneities. We find that meridional planes generally act in the shell geometry as attractors for ray trajectories. In addition, the existence of trajectories that are not subject to meridional trapping is here observed for the first time. Their dynamics was not captured by the previous purely meridional studies and unveils a new class of possible solutions for inertial motion in the spherical shell. Both observed behaviours shed some new light on possible mechanisms of energy localization, a key process that still deserves further investigation in our ocean, as well as in other stratified, rotating media

    Reducing russeting of organically grown Elstar to increase quality

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    Sales organisations indicated that opportunities for organic apples sales can increase when quality increases, in particular reducing the amount of russeting. The use of copper is probably the most important factor for russeting. Therefore a worst case scheme was compared with a scheme with reduced copper application. Furthermore, there was a particular interest in the effects on russeting of potassium bicarbonate (Armicarb) because this product might be an important element in a copper free fungicide scheme. Application of Armicarb was investigated on wet or dry canopy and effects of two different dosages were studied. All the schemes were compared with a worst case organic fungicide scheme with copper. The experiment was done on two year old Elstar trees because Elstar is the most important organically grown cultivar in the Netherlands. Effects of the schedules on russet and scab control were evaluated. At harvest no effects were found on scab. Between the different schemes with copper no differences were found in amount of russet. Only the highest dosage of Armicarb (10 kg/ha) and the schedules with Armicarb on a wet canopy gave more russet compared with the worst case scheme. Also effects on fruit rot were evaluated

    Prediction of disease progression, treatment response and dropout in chronic obstructive pulmonary disease (COPD).

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    Drug development in chronic obstructive pulmonary disease (COPD) has been characterised by unacceptably high failure rates. In addition to the poor sensitivity in forced expiratory volume in one second (FEV1), numerous causes are known to contribute to this phenomenon, which can be clustered into drug-, disease- and design-related factors. Here we present a model-based approach to describe disease progression, treatment response and dropout in clinical trials with COPD patients

    L-Band MMICs for Space-based SAR system

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    The design and performance of an L-Band GaAs chip-set is presented.The chip-set consists of a 6-bit attenuator circuit,a Low-Noise Amplifier (LNA)and a Multi Function Chip that is the combination of a 6-bit attenuator and 6-bit Phase shifter circuit.The chip-set is developed for the pre-flight engineering T/R (Transmit and Receive)modules currently in development with Astrium in a space-based SAR (Synthetic Aperture Radar)system.The MMICs are realised in the 0.25 µm PHEMT (PH25)technology of UMS.Only one iteration was needed for the MMICs in order to be fully compliant with the specifications

    Damping of quasi-2D internal wave attractors by rigid-wall friction

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    The reflection of internal gravity waves at sloping boundaries leads to focusing or defocusing. In closed domains, focusing typically dominates and projects the wave energy onto 'wave attractors'. For small-amplitude internal waves, the projection of energy onto higher wave numbers by geometric focusing can be balanced by viscous dissipation at high wave numbers. Contrary to what was previously suggested, viscous dissipation in interior shear layers may not be sufficient to explain the experiments on wave attractors in the classical quasi-2D trapezoidal laboratory set-ups. Applying standard boundary layer theory, we provide an elaborate description of the viscous dissipation in the interior shear layer, as well as at the rigid boundaries. Our analysis shows that even if the thin lateral Stokes boundary layers consist of no more than 1% of the wall-to-wall distance, dissipation by lateral walls dominates at intermediate wave numbers. Our extended model for the spectrum of 3D wave attractors in equilibrium closes the gap between observations and theory by Hazewinkel et al. (2008)
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