13,340 research outputs found
The pulsed air gust generator Final report
Wind tunnel simulation of jet pulsing apparatus for controlled gust
The irrationality of a number theoretical series
Denote by the sum of the -th powers of the divisors of ,
and let . We prove that Schinzel's
conjecture H implies that is irrational, and give an unconditional proof
for the case
Determination of the critical current density in the d-wave superconductor YBCO under applied magnetic fields by nodal tunneling
We have studied nodal tunneling into YBa2Cu3O7-x (YBCO) films under magnetic
fields. The films' orientation was such that the CuO2 planes were perpendicular
to the surface with the a and b axis at 450 form the normal. The magnetic field
was applied parallel to the surface and perpendicular to the CuO2 planes. The
Zero Bias Conductance Peak (ZBCP) characteristic of nodal tunneling splits
under the effect of surface currents produced by the applied fields. Measuring
this splitting under different field conditions, zero field cooled and field
cooled, reveals that these currents have different origins. By comparing the
field cooled ZBCP splitting to that taken in decreasing fields we deduce a
value of the Bean critical current superfluid velocity, and calculate a Bean
critical current density of up to 3*10^7 A/cm2 at low temperatures. This
tunneling method for the determination of critical currents under magnetic
fields has serious advantages over the conventional one, as it avoids having to
make high current contacts to the sample.Comment: 8 pages, 2 figure
Quantum transport of slow charge carriers in quasicrystals and correlated systems
We show that the semi-classical model of conduction breaks down if the mean
free path of charge carriers is smaller than a typical extension of their
wavefunction. This situation is realized for sufficiently slow charge carriers
and leads to a transition from a metallic like to an insulating like regime
when scattering by defects increases. This explains the unconventional
conduction properties of quasicrystals and related alloys. The conduction
properties of some heavy fermions or polaronic systems, where charge carriers
are also slow, present a deep analogy.Comment: 4 page
Point sets that minimize -edges, 3-decomposable drawings, and the rectilinear crossing number of
There are two properties shared by all known crossing-minimizing geometric
drawings of , for a multiple of 3. First, the underlying -point set
of these drawings has exactly -edges, for all . Second, all such drawings have the points divided into three
groups of equal size; this last property is captured under the concept of
3-decomposability. In this paper we show that these properties are tightly
related: every -point set with exactly -edges for
all , is 3-decomposable. As an application, we prove that the
rectilinear crossing number of is 9726.Comment: 14 page
Short-term reliability of inflammatory mediators and response to exercise in the heat.
Prospective application of serum cytokines, lipopolysaccharide (LPS), and heat shock proteins (eHSPs) requires reliable measurement of these biomarkers that can signify exercise-induced heat stress in hot conditions. To accomplish this, both short-term (7 day) reliability (at rest, n = 12) and the acute responsiveness of each biomarker to exercise in the heat (pre and post 60-min cycling, 34.5°C and 70% RH, n = 20) were evaluated. Serum was analysed for the concentration of C-reactive protein (CRP), interleukin-6 (IL-6), heat shock protein 72 (eHSP72), immunoglobulin M (IgM) and LPS. Testâretest reliability was determined as the coefficient of variation (CV). Biomarkers with the least short-term within-participant variation were IL-6 (19%, ±20%; CV, ±95% confidence limits (CL)) and LPS (23%, ±13%). Greater variability was observed for IgM, eHSP72 and CRP (CV range 28â38%). IL-6 exhibited the largest increase in response to acute exercise (95%, ±11%, P = < 0.001) and although CRP had a modest CV (12%, ±7%), it increased substantially post-exercise (P = 0.02, ES; 0.78). In contrast, eHSP72 and LPS exhibited trivial changes post-exercise. It appears variation of common inflammatory markers after exercise in the heat is not always discernible from short-term (weekly) variation
Evidence for a Young Stellar Population in NGC 5018
Two absorption line indices, Ca II and Hdelta/FeI4045, measured from high
resolution spectra are used with evolutionary synthesis models to verify the
presence of a young stellar population in NGC 5018. The derived age of this
population is about ~2.8 Gyr with a metallicity roughly solar and it completely
dominates the integrated light of the galaxy near 4000 A.Comment: 13 pages, 7 figures (figs 3-7 are color figures), to be published in
the May 2000 issue of the Astrophysical Journa
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