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
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
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
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
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).
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
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
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)
- …
