400 research outputs found
Time to exhaustion at estimated functional threshold power in road cyclists of different performance levels
This study assessed the functional threshold power and the time to exhaustion estimated from the Allen & Coggan test and verify whether performance level has an influence on this parameter
Quantum Hall Spherical Systems: the Filling Fraction
Within the newly formulated composite fermion hierarchy the filling fraction
of a spherical quantum Hall system is obtained when it can be expressed as an
odd or even denominator fraction. A plot of as a function
of for a constant number of particles (up to N=10001) exhibits structure
of the fractional quantum Hall effect. It is confirmed that
for all particle-hole conjugate systems, except systems with , and
.Comment: 3 pages, Revtex, 7 PostScript figures, submitted to Phys. Rev. B
Rapid Communicatio
The Composite Fermion Hierarchy: Condensed States of Composite Fermion Excitations?
A composite Fermion hierarchy theory is constructed in a way related to the
original Haldane picture by applying the composite Fermion (CF) transformation
to quasiparticles of Jain states. It is shown that the Jain theory coincides
with the Haldane hierarchy theory for principal CF fillings. Within the Fermi
liquid approach for few electron systems on the sphere a simple interpretation
of many-quasiparticle spectra is given and provides an explanation of failure
of CF hierarchy picture when applied to the hierarchical state.Comment: 6 pages, Revtex, 4 figures in PostScript, submitted to Phys. Rev.
Let
Characteristics of pedaling muscle stiffness among cyclists of different performance levels
Background and Objectives: The aim of the present study was to compare the impact of an incremental exercise test on muscle stiffness in the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and gastrocnemius (GL) among road cyclists of three performance levels. Materials and Methods: The study group consisted of 35 cyclists grouped according to their performance level; elite (n = 10; professional license), sub-elite (n = 12; amateur license), and recreational (n = 13; cyclosportive license). Passive muscle stiffness was assessed using myometry before and after an incremental exercise test. Results: There was a significant correlation between time and category in the vastus lateralis with stiffness increases in the sub-elite (p = 0.001, Cohen’s d = 0.88) and elite groups (p = 0.003, Cohen’s d = 0.72), but not in the recreational group (p = 0.085). Stiffness increased over time in the knee extensors (RF, p < 0.001; VL, p < 0.001), but no changes were observed in the knee flexors (GL, p = 0.63, BF, p = 0.052). There were no baseline differences among the categories in any muscle. Conclusions: Although the performance level affected VL stiffness after an incremental exercise test, no differences in passive stiffness were observed among the main muscles implicated in pedaling in a resting state. Future research should assess whether this marker could be used to differentiate cyclists of varying fitness levels and its potential applicability for the monitoring of training load. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Mid-Infrared Ethane Emission on Neptune and Uranus
We report 8- to 13-micron spectral observations of Neptune and Uranus from
the NASA Infrared Telescope Facility spanning more than a decade. The
spectroscopic data indicate a steady increase in Neptune's mean atmospheric
12-micron ethane emission from 1985 to 2003, followed by a slight decrease in
2004. The simplest explanation for the intensity variation is an increase in
stratospheric effective temperature from 155 +/- 3 K in 1985 to 176 +/- 3 K in
2003 (an average rate of 1.2 K/year), and subsequent decrease to 165 +/- 3 K in
2004. We also detected variation of the overall spectral structure of the
ethane band, specifically an apparent absorption structure in the central
portion of the band; this structure arises from coarse spectral sampling
coupled with a non-uniform response function within the detector elements. We
also report a probable direct detection of ethane emission on Uranus. The
deduced peak mole fraction is approximately an order of magnitude higher than
previous upper limits for Uranus. The model fit suggests an effective
temperature of 114 +/- 3 K for the globally-averaged stratosphere of Uranus,
which is consistent with recent measurements indicative of seasonal variation.Comment: Accepted for publication in ApJ. 16 pages, 10 figures, 2 table
Silicate Emission in the TW Hydrae Association
The TW Hydrae Association is the nearest young stellar association. Among its
members are HD 98800, HR 4796A, and TW Hydrae itself, the nearest known
classical T Tauri star. We have observed these three stars spectroscopically
between 3 and 13 microns. In TW Hya the spectrum shows a silicate emission
feature that is similar to many other young stars with protostellar disks. The
11.2 micron feature indicative of significant amounts of crystalline olivine is
not as strong as in some young stars and solar system comets. In HR 4796A, the
thermal emission in the silicate feature is very weak, suggesting little in the
way of (small silicate) grains near the star. The silicate band of HD 98800
(observed by us but also reported by Sylvester and Skinner (1996)) is
intermediate in strength between TW Hya and HR 4796.Comment: 22 pages, 11 figures, LaTeX2e and AAS LaTeX macros v5.0. Accepted for
publication in A
First beam test of Laser Engineered Surface Structures (LESS) at cryogenic temperature in CERN SPS accelerator
Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the elec-tron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression.Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the electron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression
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