bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of cycling cadence on subsequent 3 km running performance in well trained triathletes
Authors: Bernard T , Vercruyssen F , Grego F , Hausswirth C , Lepers R , Vallier J-M , Brisswalter J 
Published: March 2003

Objectives:To investigate the effect of three cycling cadences on a subsequent 3000 m track running performance in well trained triathletes.Methods:Nine triathletes completed a maximal cycling test, three cycle-run succession sessions (20 minutes of cycling + a 3000 m run) in random order, and one isolated run (3000 m). During the cycling bout of the cycle-run sessions, subjects had to maintain for 20 minutes one of the three cycling cadences corresponding to 60, 80, and 100 rpm. The metabolic intensity during these cycling bouts corresponded approximately to the cycling competition intensity of our subjects during a sprint triathlon (> 80% V̇o2max).Results:A significant effect of the prior cycling exercise was found on middle distance running performance without any cadence effect (625.7 (40.1), 630.0 (44.8), 637.7 (57.9), and 583.0 (28.3) seconds for the 60 rpm run, 80 rpm run, 100 rpm run, and isolated run respectively). However, during the first 500 m of the run, stride rate and running velocity were significantly higher after cycling at 80 or 100 rpm than at 60 rpm (p<0.05). Furthermore, the choice of 60 rpm was associated with a higher fraction of V̇o2max sustained during running compared with the other conditions (p<0.05).Conclusions:The results confirm the alteration in running performance completed after the cycling event compared with the isolated run. However, no significant effect of the cadence was observed within the range usually used by triathletes.
Effect of wearing an ice cooling jacket on repeat sprint performance in warm/humid conditions
Authors: Duffield R , Dawson B , Bishop D , Fitzsimons M , Lawrence S 
Published: March 2003

Objective:To examine the effect of cooling the skin with an ice jacket before and between exercise bouts (to simulate quarter and half time breaks) on prolonged repeat sprint exercise performance in warm/humid conditions.Methods:After an initial familiarisation session, seven trained male hockey players performed two testing sessions (seven days apart), comprising an 80 minute intermittent, repeat sprint cycling exercise protocol inside a climate chamber set at 30°C and 60% relative humidity. On one occasion a skin cooling procedure was implemented (in random counterbalanced order), with subjects wearing an ice cooling jacket both before (for five minutes) and in the recovery periods (2 × 5 min and 1 × 10 min) during the test. Measures of performance (work done and power output on each sprint), heart rates, blood lactate concentrations, core (rectal) and skin temperatures, sweat loss, perceived exertion, and ratings of thirst, thermal discomfort, and fatigue were obtained in both trials.Results:In the cooling condition, chest (torso) skin temperature, thermal discomfort, and rating of thirst were all significantly lower (p<0.05), but no significant difference (p>0.05) was observed between conditions for measures of work done, power output, heart rate, blood lactate concentration, core or mean skin temperature, perceived exertion, sweat loss, or ratings of fatigue. However, high effect sizes indicated trends to lowered lactate concentrations, sweat loss, and mean skin temperatures in the cooling condition.Conclusions:The intermittent use of an ice cooling jacket, both before and during a repeat sprint cycling protocol in warm/humid conditions, did not improve physical performance, although the perception of thermal load was reduced. Longer periods of cooling both before and during exercise (to lower mean skin temperature by a greater degree than observed here) may be necessary to produce such a change.
Football boot insoles and sensitivity to extent of ankle inversion movement
Authors: Waddington G , Adams R 
Published: March 2003

Background:The capacity of the plantar sole of the foot to convey information about foot position is reduced by conventional smooth boot insoles, compared with barefoot surface contact.Objective:To test the hypothesis that movement discrimination may be restored by inserting textured replacement insoles, achieved by changing footwear conditions and measuring the accuracy of judgments of the extent of ankle inversion movement.Methods:An automated testing device, the ankle movement extent discrimination apparatus (AMEDA), developed to assess active ankle function in weight bearing without a balance demand, was used to test the effects of sole inserts in soccer boots. Seventeen elite soccer players, the members of the 2000 Australian Women’s soccer squad (34 ankles), took part in the study. Subjects were randomly allocated to start testing in: bare feet, their own football boots, own football boot and replacement insole, and on the left or right side. Subjects underwent six 50 trial blocks, in which they completed all footwear conditions. The sole inserts were cut to size for each foot from textured rubber “finger profile” sheeting.Results:Movement discrimination scores were significantly worse when subjects wore their football boots and socks, compared with barefoot data collected at the same time. The substitution of textured insoles for conventional smooth insoles in the football boots was found to restore movement discrimination to barefoot levels.Conclusions:The lower active movement discrimination scores of athletes when wearing football boots with smooth insoles suggest that the insole is one aspect of football boot and sport shoe design that could be modified to provide the sensory feedback needed for accurate foot positioning.
Radiation effect on MHD free-convective flow of a gas past a semi-infinite vertical plate with variable thermophysical properties for high-temperature differences
Authors: Aboeldahab E M , El Gendy M S 
Published: March 2003

Radiation effects in the presence of a uniform transverse magnetic field on the free-convective steady laminar boundary-layer flow, past a semi-infinite vertical plate, for high-temperature differences are studied. The fluid density and the thermal conductivity are assumed to vary linearly with temperature. The fluid viscosity is assumed to vary as a reciprocal of a linear function of temperature. The nonlinear boundary-layer equations, governing the problem under consideration, are solved numerically by applying an efficient numerical technique based on the shooting method. The effects of the magnetic field M, the temperature ratio parameter θw, the thermal conductivity parameter S, the viscositytemperature parameter θr, and the radiation parameter N are examined on the velocity and temperature distributions as well as the coefficient of heat flux and the shearing stress at the plate. PACS No.: 44.40+a
Effect of cobalt 60 and 1 MeV electron irradiation on silicon photodiodes/solar cells
Authors: Saad A M 
Published: March 2003

Using 1060 krad doses of cobalt 60 gamma radiation, the effect of simulated space radiation on 1 mm2 active area silicon photodiodes with a sapphire window is studied. The diodes will be used to control the laser output of a space experiment in geostationary orbit. The effect of 1 MeV electron irradiation with various fluences on 100 mm2 silicon photodiodes/solar cells, which were used to control the attitude of a satellite in space, is also studied here. Fluences ranging from 3 x 1014 to 1 x 1015 cm2 of 1 MeV energy, caused a decrease in the short-circuit current, i.e., increasing the percentage of deterioration from 12% to 20% at a room-temperature measurement. Exposure to the gamma irradiation yields almost no degradation for the electro-optical performance of the devices. The manufacturing processes of the detectors and their electro-optical IV characteristics such as fill factor, responsivity, and dark current are presented here. Electro-optical tests were also done at intermediate levels of irradiation. High stability and high quality of the photodiodes were achieved prior to and after irradiation. PACS No.: 84.60J
The light-front Hamiltonian and BRST formulations of a two-dimensional AbelianHiggs model
Authors: Kulshreshtha U 
Published: March 2003

The Hamiltonian and BRST formulations of an AbelianHiggs model in one-space one-time dimensions are investigated in the light-front frame under some specific gauge choices. PACS Nos.: 03.65+, 03.70+k, 11.10lm, 11.10Ef, and 11.30Rd
Hamiltonian and BRST formulations of a gauge-invariant chiral Schwinger model with the Faddeevian regularization
Authors: Kulshreshtha U 
Published: March 2003

The Hamiltonian and BRST formulations of a gauge-invariant chiral Schwinger model with the Faddeevian regularization due to Mukhopadhyay and Mitra in one-space one-time dimensions (obtained by the inclusion of an appropriate WessZumino term in the action of the originally gauge-noninvariant model due to Mitra) are investigated under some specific gauge choices in the usual instant form of dynamics (on the hyperplanes x0 = constant). The physical contents of the original gauge-noninvariant theory are recovered from that of this gauge-invariant theory under a special choice of gauge, and the quantum equivalence of the two quantized theories is established. PACS Nos.: 03.65+, 03.70+, 11.10lm, 11.10Ef, and 11.30Rd
MHD free convection flow of a micropolar fluid past a vertical porous plate
Authors: Helmy K A , Idriss H F , Kassem S E 
Published: March 2003

The present work is concerned with the unsteady flow of an incompressible, viscous, conducting micropolar fluid, through a porous medium, over an infinite plate that is started into motion in its own plane by an impulse. A uniform magnetic field acts in a direction perpendicular to the plate. The governing equations are solved using a state space approach and the inversion of the Laplace transform is carried out, using a numerical approach. The technique is applied to a heated-plate problem and to a problem pertaining to a plate under uniform heating. Numerical results concerning temperature (for both problems), velocity, and microrotation are given and are illustrated graphically. PACS Nos.: 47.00, 65.00, 47.50, 76.00
A theoretical model analysis of the sudden narrow temperature-layer formation observed in the ALOHA-93 Campaign
Authors: Hur H , Huang T Y , Zhao Z , Karunanayaka P , Tuan T F 
Published: March 2003

The behavior of temperature and wind profiles observed on 21 October 1993 in the ALOHA-93 Campaign is theoretically and numerically analyzed. A sudden temperature rise took place in a very narrow vertical region (34 km) at about 87 km. Simultaneously observed radar wind profiles and mesospheric airglow wave structures that show a horizontal phase speed of 35 m/s and a period of about half an hour strongly suggest that a critical level may occur in the proximity of that altitude and that the energy dissipation due to the interaction of the gravity wave with the critical level causes the temperature rise. The numerical model used is a solution to the gravity wave  mean-flow interaction in the critical layer, including a simple cooling mechanism and a wave-energy dissipation simulated by the "optical model" technique. The solutions for the temperature variations so obtained show good agreement with the observed temperature profiles at different times, providing a quantitative explanation for the temperature inversion layer as a phenomenon of gravity wave  critical layer interaction. PACS Nos.: 91.10V, 94.10D
High quantum efficiency of UV-enhanced silicon photodiodes
Authors: Saad A M 
Published: March 2003

High quantum efficiency UV-enhanced (P+nn+) silicon photodiodes have been developed using ion implantation, rapid thermal processing, and a thin silicon dioxide film as an antireflection/passivation layer. The unbiased devices have internal quantum efficiency in excess of 350% at a wavelength equal to 250 nm. The devices are stable, have very low dark current at a reverse bias voltage of 1 V and high responsivity. Analysis of the dopant concentration versus junction depth using a sheet resistance technique was done in this work. PACS Nos.: 85.60Gz, 85.60Bt, 85.60DW
Some further analogies between the Bak-Sneppen model for biological evolution and the spring-block earthquake model
Authors: Chimal-Eguía J C , Chavoya-Aceves O , Angulo-Brown F 
Published: March 2003

In recent years, a great deal of attention has been devoted to so-called self-organized critical (SOC) systems, which are open, extended systems that organize themselves into steady metastable states without any temporal- or spatial-predominant scale (except those imposed by the finite size of the system). The SOC concept has been used to describe the statistical properties of several physical systems through numerical models based on cellular automaton. In particular, Bak and Sneppen proposed a SOC model for biological evolution at the level of entire species or faunas that exhibit punctuated equilibrium behavior. On the other hand, Olami, Feder and Christensen suggested that a two-dimensional spring-block earthquake model can explain some properties of real seismicity. In this paper, we show that there exist several further interesting analogies between these SOC models, besides those remarked on by other authors. Both of them exhibit punctuated equilibrium in the long term, which leads us to suggest an equivalent characterization of seismic and "evolutionary" provinces through the long-term slopes of the stair-shaped graphs of cumulative activity in the course of time. PACS Nos.: 91.30P, 05.65, 87.23
The exact evolution of the time-dependent driven damped harmonic oscillator with time-dependent mass and frequency
Authors: Liang M , Yuan B , Zhong K 
Published: March 2003

Under a new quantization scheme, the exact wave functions of the time-dependent driven damped harmonic oscillator with time-dependent mass and frequency are obtained. The wave functions are shape-unchanging wave packet with the center moving along the classical trajectory. The total phase of the wave function is explicitly expressed as the sum of the dynamical phase and the geometrical phase. PACS Nos.: 03.65-w, 05.40-a
Analysis of pionnucleus interactions in the framework of a multistring model
Authors: Dhamija S , Kaur M , Dahiya S 
Published: March 2003

A multistring model implemented through Monte Carlo code, modified-FRITIOF is used to analyse the data from π Em interactions at high energies. The model is based on the concept of classical strings, and using the method of longitudinal excitation as a means of string formation, the subsequent string fragmentation follows the Lund fragmentation scheme. The analysis gives interesting comparison between the data and the model predictions. PACS No.: 25.70
Canonical perturbation theory for highly excited dynamics
Authors: Joyeux M , Sugny D 
Published: March 2003

This article proposes an unified presentation of recent results dealing with canonical perturbation theory (also called the contact transformation method in the quantum mechanical context), which shows how the theory is best handled for investigating the highly excited dynamics of small molecules. The following systems are successively addressed: (i) semi-rigid molecules (one electronic surface, one minimum), (ii) floppy molecules (one electronic surface, several minima), and (iii) non-BornOppenheimer dynamics (several interacting electronic surfaces). The perturbative Hamiltonians obtained from the proposed procedures are checked against exact calculations performed on ab initio surfaces (HCP and HCN) and model Hamiltonians. PACS No.: 31.15Md
Ar K X-ray production in slow, highly charged Ar q+(q = 818) + Ar collisions
Authors: Tawara H , Richard P 
Published: March 2003

In the present work, mechanisms of Ar K X-ray production have been investigated under low-energy Arq+ + Ar collisions in a wide range of the ion-charge states. Ar K X-rays have been observed as a function of the collision energy over (0.753.75)q keV/u and of the charge state over q = 816 of projectile Arq+ ions. If the L-shell vacancies become available (q = 9), Ar K X-ray yields are found to be enhanced roughly three orders of magnitude, compared with Ar8+ ions with no L-shell vacancy; to show some threshold; and to tend to quickly saturate at higher collision energies. The present analysis, based on the energy correlation diagrams of the quasi-molecules, suggests that Ar K X-rays originate entirely from target Ar atoms through promotion via the rotational coupling between 2pσ 2pπ molecular orbitals. Furthermore, the observed cross sections are found to increase nonlinearly with the projectile Arq+ ion charge q (q = 9). This can be understood because of the combined effects of two contributions: (i) the increased number of the L-shell vacancies of projectile Arq+ ions and (ii) the enhanced fluorescence yields of target Ar atom. In addition, Ar K X-rays have been observed under 2.5q keV/u Ar17+ and Ar18+ + Ar collisions and found to originate from the decay of K-shell vacancies initially present in the projectile Ar ions through electron capture into their highly excited states, followed by cascade down to the ground states. For the first time, though very weak, the X-rays due to the two-electronone-photon transition, namely, K αα lines, have also been observed in bare Ar18+ ion collisions. PACS Nos.: 34.70+e, 32.80Rm
Integral-equation analysis of the kinetic-ballooning modes in tokamaks
Authors: Hirose A , Elia M 
Published: March 2003

The existence of kinetic-ballooning modes in the regime that is stable against the ideal MHD (magnetohydrodynamic) mode has been confirmed by nonlocal analysis based on integral-equation formalism. In contrast to the previous results based on differential-shooting codes, the kinetic-ballooning mode in the second stability regime does not require a finite ion-temperature gradient. PACS Nos.: 52.35Kt, 52.55Fa
Dielectronic recombination-rate coefficients to excited states of Be-like oxygen and dielectronic satellite lines
Authors: Murakami I , Safronova U I , Kato T 
Published: March 2003

We calculate energy levels, radiative transition probabilities, and autoionization rates for Be-like oxygen (O4+) including 1s2 2lnl' (n = 28, l [Formula: see text] n  1) and 1s23l' nl (n = 36, l [Formula: see text] n  1) states by the multiconfigurational HartreeFock method (Cowan code) and the perturbation theory Z-expansion method (MZ code). The state selective dielectronic recombination-rate coefficients to excited states of Be-like oxygen are obtained, which are useful for modeling O V spectral lines in a recombining plasma. Configuration mixing plays an important role for the principal quantum number, n, distribution of the dielectronic recombination-rate coefficients for 2snl (n [Formula: see text] 5) levels at low electron temperature. The orbital angular momentum quantum number, l, distribution of the rate coefficients shows a peak at l = 4. The total dielectronic recombination-rate coefficient is derived as a function of electron temperature. The dielectronic satellite lines are also obtained. PACS Nos.: 34.80Lx, 32.80Dz, 32.30Jc, 31.10+z
Visible spectrum of highly charged ions: The forbidden optical lines of Kr, Xe, and Ba ions in the Ar I to Kr I isoelectronic sequence
Authors: López-Urrutia J.R. Crespo , Beiersdorfer P , Widmann K , Decaux V 
Published: March 2003

We present experimental data on visible transitions in highly charged ions observed in the Lawrence Livermore National Laboratory (LLNL) electron beam ion traps, including results from lines within the ground-state configuration and the first excited configuration. Measurements of lines produced by Kr (q = 11+ to 22+), Xe (q = 18+ to 35+), and Ba (q = 28+ to 36+) ions, corresponding mainly to 3sl 3pm 3dn configurations, were carried out. The ionization stages were determined experimentally by sweeping the electron beam energy over the ionization threshold of each species. We propose possible identifications for the lines with the help of simple atomic structure calculations. However, most observed lines remained unidentified, demonstrating that the understanding of visible spectra from highly charged ions, even if obtained under nearly "ideal" experimental conditions, is still in its infancy. These spectral data may be useful for the diagnostics of magnetically confined plasmas and may set the stage for future measurements of radiative lifetimes. In our experiments, we used the emission from visible lines to image the intersection of the electron beam with a beam of neutral atoms injected into the trap at a right angle as well as the ion cloud in the trap. Under some conditions, the diameter of the ion cloud may be an order of magnitude larger than that of the electron beam. PACS Nos.: 32.30Jc, 39.30+w, 52.59Rz
Laser-frequency stabilization using a lock-in amplifier
Authors: Weel M , Kumarakrishnan A 
Published: March 2003

We describe how a lock-in amplifier can be used in a feedback loop to lock the frequency of a laser to an atomic transition in 85Rb. A simple physical explanation is presented to describe the shape of the feedback signal generated by the "lock in" and the dependence of this signal on the phase of the reference signal. We also present a mathematical model of the feedback signal. Using the output of the lock in as feedback, we show that the laser frequency can be stabilized to a few MHz. The experiment is relatively simple to set up and could easily be adapted as an undergraduate laboratory experiment. PACS No.: 42.60Mi
The rotating-saddle trap: a mechanical analogy to RF-electric-quadrupole ion trapping?
Authors: Thompson R I , Harmon T J , Ball M G 
Published: March 2003

The rotating-saddle potential ball-bearing trap has long been used as a mechanical analogue to explain the operating principles of the Paul-type RF-electric-quadrupole ion trap. This paper outlines the shortcomings of this analogy, as well as explaining how and why this system remains an excellent tool for explaining ion-trap operation. The basic theory of the operating principles of the rotating-saddle trap is provided, which, unlike the Paul Trap is analytically solvable in the friction-free regime. In addition, some extensions to this theory are presented to examine such effects as friction. These results are compared with the equivalent results for Paul-Trap theory, as well as to experimental results measured with a rotating-saddle trap constructed at the University of Calgary. The technical details of this trap, an excellent tool for either lecture demonstrations or teaching laboratory experiments, are also presented, as well as some comments on building such a trap. PACS Nos.: 45.50-j, 01.50Pa, 32.80Pj
Measurement of radiative lifetimes in Sm II
Authors: Scholl T J , Holt R A , Masterman D , Rivest R C , Rosner S D , Sharikova A 
Published: March 2003

We have measured the radiative lifetimes of 82 levels of Sm II using the beam-laser method. The levels studied had term energies up to ~29 600 cm1 and lifetimes in the range 9190 ns. Experimental uncertainty was less than 7%, with a typical value of 1.6%. We have used these lifetimes to update transition probabilities for 35 transitions in the wavelength range 363771 nm, which are useful for stellar abundance determinations. PACS Nos.: 32.70Cs, 95.30Ky
Precise atomic lifetime measurements with stored ion beams and ion traps
Authors: Träbert E 
Published: March 2003

For many years, atomic lifetime measurements on multiply-charged ions have been done almost exclusively by beam-foil spectroscopy. For low ion charges, however, spin-changing "intercombination" transitions have a rate that renders them too slow for traditional fast-beam techniques. Here ion traps and fast-ion beams have been combined in the concept of heavy-ion storage rings. These devices have permitted not only an extension of intercombination lifetime measurements down to singly charged ions, but they also facilitated similar measurements on electric-dipole forbidden transitions. The electron-beam ion trap (EBIT) complements the storage-ring work for work on highly charged ions. Achievements, technical issues, and prospects are outlined. PACS Nos.: 32.70Cs, 32.30Jc, 34.50Fa