36,815 research outputs found
Interpreting and Implementing the Long Term Athlete Development Model: English Swimming Coaches’ Views on the (Swimming) LTAD in Practice
The LTAD (Long Term Athlete Development) model has come to represent a sports-wide set of principles that significantly influences national sports policy in England. However, little is known about its impact ‘on the ground.’ This study is concerned with how national sporting bodies have adapted the model to their specific requirements and how local interpretation and implementation of this is operationalized and delivered. Interpretation and implementation of the LTAD model used in English swimming was investigated through interviews with six elite and five non-elite swimming coaches in the north of England. While there were concerns with aspects of the Amateur Swimming Association (ASA) regulations governing competition for age-group swimmers, the major concern expressed by participants was with over-emphasizing volumes of training, leading to the neglect of technique
Pre-shuttle lidar system research
Included are the results of the initial phase of a simulation study in connection with photomultiplier tubes (PMT) and associated networks and an analytical study of atmospheric physics (including multiscattering) leading to modeling studies in connection with differential absorption lidar (DIAL) observations. This effort was in support of the ER-2 aircraft DIAL projects
Modal properties of unstable resonator semiconductor lasers with a lateral waveguide
The modal properties of unstable resonator lasers with a lateral waveguide have been analyzed, and an unstable resonator semiconductor laser with a real index lateral waveguide has been demonstrated. Output powers in excess of 400 mW were observed with a stable, highly coherent lateral field distribution. The incorporation of a lateral real index waveguide with the unstable resonator configuration results in an increase in the external quantum efficiency and the appearance of ripples in the lateral field distribution
Unstable resonator cavity semiconductor lasers
GaAs heterostructure lasers with unstable resonator cavities were demonstrated for the first time with both curved mirrors fabricated by etching. Typical output powers of 0.35 W were observed in a stable, highly coherent lateral mode. The laser operated stably in a single longitudinal mode over a large range of injection currents. The external quantum efficiency was 70% of that of a similar laser with both mirror facets cleaved implying good output coupling of the energy from the entire region
Predicting positive parity mesons from lattice QCD
We determine the spectrum of 1P states using lattice QCD. For the
and mesons, the results are in good agreement
with the experimental values. Two further mesons are expected in the quantum
channels and near the and thresholds. A
combination of quark-antiquark and meson-Kaon interpolating fields
are used to determine the mass of two QCD bound states below the
threshold, with the assumption that mixing with and
isospin-violating decays to are negligible. We predict a
bound state with mass GeV. With
further assumptions motivated theoretically by the heavy quark limit, a bound
state with GeV is predicted in the
channel. The results from our first principles calculation are compared to
previous model-based estimates.Comment: 5 pages, 2 figures; Final versio
Symmetries of hadrons after unbreaking the chiral symmetry
We study hadron correlators upon artificial restoration of the spontaneously
broken chiral symmetry. In a dynamical lattice simulation we remove the lowest
lying eigenmodes of the Dirac operator from the valence quark propagators and
study evolution of the hadron masses obtained. All mesons and baryons in our
study, except for a pion, survive unbreaking the chiral symmetry and their
exponential decay signals become essentially better. From the analysis of the
observed spectroscopic patterns we conclude that confinement still persists
while the chiral symmetry is restored. All hadrons fall into different chiral
multiplets. The broken U(1)_A symmetry does not get restored upon unbreaking
the chiral symmetry. We also observe signals of some higher symmetry that
includes chiral symmetry as a subgroup. Finally, from comparison of the \Delta
- N splitting before and after unbreaking of the chiral symmetry we conclude
that both the color-magnetic and the flavor-spin quark-quark interactions are
of equal importance.Comment: 12 pages, 14 figures; final versio
High Frequency Scattering from Arbitrarily Oriented Dielectric Disks
Calculations have been made of electromagnetic wave scattering from dielectric disks of arbitrary shape and orientation in the high frequency (physical optics) regime. The solution is obtained by approximating the fields inside the disk with the fields induced inside an identically oriented slab (i.e. infinite parallel planes) with the same thickness and dielectric properties. The fields inside the disk excite conduction and polarization currents which are used to calculate the scattered fields by integrating the radiation from these sources over the volume of the disk. This computation has been executed for observers in the far field of the disk in the case of disks with arbitrary orientation and for arbitrary polarization of the incident radiation. The results have been expressed in the form of a dyadic scattering amplitude for the disk. The results apply to disks whose diameter is large compared to wavelength and whose thickness is small compared to diameter, but the thickness need not be small compared to wavelength. Examples of the dependence of the scattering amplitude on frequency, dielectric properties of the disk and disk orientation are presented for disks of circular cross section
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