252 research outputs found
Effects of Water Immersion on the Internal Power of Cycling
Purpose Water immersion adds additional drag and metabolic demand for limb movement with respect to air, but its effect on the internal metabolic power (Ėint) of cycling is unknown. We aimed at quantifying the increase in Ėint during underwater cycling with respect to dry conditions at different pedaling rates. Methods Twelve healthy subjects (four women) pedaled on a waterproof cycle ergometer in an experimental pool that was either empty (DRY) or filled with tap water at 30.8°C ± 0.6°C (WET). Four different pedal cadences (fp) were studied (40, 50, 60, and 70 rpm) at 25, 50, 75, and 100 W. The metabolic power at steady state was measured via open circuit respirometry, and Ėint was calculated as the metabolic power extrapolated for 0 W. Results The Ėint was significantly higher in WET than in DRY at 50, 60, and 70 rpm (81 ± 31 vs 32 ± 30 W, 167 ± 35 vs 50 ± 29 W, 311 ± 51 vs 81 ± 30 W, respectively, all P 0.99). Ėint increased with the third power of fp both in WET and DRY (R2 = 0.49 and 0.91, respectively). Conclusions Water drag increased Ėint, although limbs unloading via the Archimedes' principle and limbs shape could be potential confounding factors. A simple formula was developed to predict the increase in mechanical power in dry conditions needed to match the rate of energy expenditure during underwater cycling: 44 fp3 - 7 W, where fp is expressed in Hertz
Pulsating sdB Stars: A New Approach to Probing their Interiors
Horizontal branch stars should show significant differential rotation with
depth. Models that assume systematic angular momentum exchange in the
convective envelope and local conservation of angular momentum in the core
produce HB models that preserve a rapidly rotating core. A direct probe of core
rotation is available. The nonradial pulsations of the EC14026 stars frequently
show rich pulsation spectra. Thus their pulsations probe the internal rotation
of these stars, and should show the effects of rapid rotation in their cores.
Using models of sdB stars that include angular momentum evolution, we explore
this possibility and show that some of the sdB pulsators may indeed have
rapidly rotating cores.Comment: 8 pages, 3 figures; paper presented at Keele Workshop on Extreme
Horizontal Branch Stars and Related Objects, June 2003 (ed. Pierre Maxsted
Internal rotation of subdwarf B stars: limiting cases and asteroseismological consequences
Observations of the rotation rates of horizontal branch (HB) stars show
puzzling systematics. In particular, cooler HB stars often show rapid rotation
(with velocities in excess of 10 km/s), while hotter HB stars typically show
much smaller rotation velocities. Simple models of angular momentum evolution
of stars from the main sequence through the red giant branch fail to explain
these effects. In general, evolutionary models in all cases preserve a rapidly
rotating core. The observed angular velocities of HB stars require that some of
the angular momentum stored in the core reaches the surface.
To test the idea that HB stars contain such a core, one can appeal to
detailed computations of trace element abundences and rotational mixing.
However, a more direct probe is available to test these limiting cases of
angular momentum evolution. Some of the hottest horizontal branch stars are
members of the pulsating sdB class. They frequently show rich pulsation spectra
characteristic of nonradially pulsating stars. Thus their pulsations probe the
internal rotation of these stars, and should show the effects of rapid rotation
in their cores. Using models of sdB stars that include angular momentum
evolution, we explore this possibility and show that some of the sdB pulsators
may indeed have rapidly rotating cores.Comment: accepted for publication in The Astrophysical Journa
Self-paced aerobic exercise performance is attenuated following four hours cold water immersion
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Hydration Status Response to Bolus Frequency and Volume Intake During Exercise in Heat
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Initializing BSQ with Open-Source ICCING
While it is well known that there is a significant amount of conserved
charges in the initial state of nuclear collisions, the production of these due
to gluon splitting has yet to be thoroughly investigated. The ICCING (Initial
Conserved Charges in Nuclear Geometry) algorithm reconstructs these quark
distributions, providing conserved strange, baryon, and electric charges, by
sampling a given model for the splitting function over
the initial energy density, which is valid at top collider energies, even when
. The ICCING algorithm includes fluctuations in the gluon longitudinal
momenta, a structure that supports the implementation of dynamical processes,
and the c++ version is now open-source. A full analysis of parameter choices on
the model has been done to quantify the effect these have on the underlying
physics. We find there is a sustained difference across the different charges
that indicates sensitivity to hot spot geometry
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