135 research outputs found
Laboratory experiments for intense vortical structures in turbulence velocity fields
Vortical structures of turbulence, i.e., vortex tubes and sheets, are studied using one-dimensional velocity data obtained in laboratory experiments for duct flows and boundary layers at microscale Reynolds numbers from 332 to 1934. We study the mean velocity profile of intense vortical structures. The contribution from vortex tubes is dominant. The radius scales with the Kolmogorov length. The circulation velocity scales with the rms velocity fluctuation. We also study the spatial distribution of intense vortical structures. The distribution is self-similar over small scales and is random over large scales. Since these features are independent of the microscale Reynolds number and of the configuration for turbulence production, they appear to be universal
On Landau's prediction for large-scale fluctuation of turbulence energy dissipation
Kolmogorov's theory for turbulence in 1941 is based on a hypothesis that
small-scale statistics are uniquely determined by the kinematic viscosity and
the mean rate of energy dissipation. Landau remarked that the local rate of
energy dissipation should fluctuate in space over large scales and hence should
affect small-scale statistics. Experimentally, we confirm the significance of
this large-scale fluctuation, which is comparable to the mean rate of energy
dissipation at the typical scale for energy-containing eddies. The significance
is independent of the Reynolds number and the configuration for turbulence
production. With an increase of scale r above the scale of largest
energy-containing eddies, the fluctuation becomes to have the scaling r^-1/2
and becomes close to Gaussian. We also confirm that the large-scale fluctuation
affects small-scale statistics.Comment: 9 pages, accepted by Physics of Fluids (see http://pof.aip.org
Vortex Tubes in Turbulence Velocity Fields at Reynolds Numbers 300-1300
The most elementary structures of turbulence, i.e., vortex tubes, are studied
using velocity data obtained in a laboratory experiment for boundary layers
with microscale Reynolds numbers 295-1258. We conduct conditional averaging for
enhancements of a small-scale velocity increment and obtain the typical
velocity profile for vortex tubes. Their radii are of the order of the
Kolmogorov length. Their circulation velocities are of the order of the
root-mean-square velocity fluctuation. We also obtain the distribution of the
interval between successive enhancements of the velocity increment as the
measure of the spatial distribution of vortex tubes. They tend to cluster
together below about the integral length and more significantly below about the
Taylor microscale. These properties are independent of the Reynolds number and
are hence expected to be universal.Comment: 8 pages, to appear in Physical Review
New Spectral State of Supercritical Accretion Flow with Comptonizing Outflow
Supercritical accretion flows inevitably produce radiation-pressure driven
outflows, which will Compton up-scatter soft photons from the underlying
accretion flow, thereby making hard emission. We perform two dimensional
radiation hydrodynamic simulations of supercritical accretion flows and
outflows, incorporating such Compton scattering effects, and demonstrate that
there appears a new hard spectral state at higher photon luminosities than that
of the slim-disk state. In this state, as the photon luminosity increases, the
photon index decreases and the fraction of the hard emission increases. The
Compton -parameter is of the order of unity (and thus the photon index will
be ) when the apparent photon luminosity is (with
being the Eddington luminosity) for nearly face-on sources. This
explains the observed spectral hardening of the ULX NGC1313 X-2 in its
brightening phase and thus supports the model of supercritical accretion onto
stellar mass black holes in this ULX.Comment: 15 pages, 4 figures, accepted for publication in PAS
Analysis of gastrin receptor gene expression in proliferating cells in the neck zone of gastric fundic glands using laser capture microdissection
AbstractGastrin stimulates proliferation of progenitor cells in the neck zone of gastric fundic mucosa. However, whether it directly enhances this proliferation through its receptors remains unclear. We investigated the expression of gastrin receptors in neck zone proliferating cells in rat gastric fundic glands using a reverse transcription polymerase chain reaction (RT-PCR) coupled with laser capture microdissection and in situ RT-PCR. Gastrin receptor expression was identified in c-fos-expressing cells located in the neck zone, and results of the RT-PCR analysis argued against contamination by other cells, such as enterochromaffin-like, parietal or D cells. Supporting this finding, gastrin receptor gene expression was identified in the neck zone as well as base glands by in situ RT-PCR. Therefore, it is suggested that proliferating cells in the neck zone are stimulated directly by gastrin via their gastrin receptors
Dimerization of MLL fusion proteins and FLT3 activation synergize to induce multiple-lineage leukemogenesis
Probability density function of turbulent velocity fluctuation
The probability density function (PDF) of velocity fluctuations is studied
experimentally for grid turbulence in a systematical manner. At small distances
from the grid, where the turbulence is still developing, the PDF is
sub-Gaussian. At intermediate distances, where the turbulence is fully
developed, the PDF is Gaussian. At large distances, where the turbulence has
decayed, the PDF is hyper-Gaussian. The Fourier transforms of the velocity
fluctuations always have Gaussian PDFs. At intermediate distances from the
grid, the Fourier transforms are statistically independent of each other. This
is the necessary and sufficient condition for Gaussianity of the velocity
fluctuations. At small and large distances, the Fourier transforms are
dependent.Comment: 7 pages, 8 figures in a PS file, to appear in Physical Review
Characterization and long-term persistence of immune response following two doses of an AS03A-adjuvanted H1N1 influenza vaccine in healthy Japanese adults
Backgroun
Probability density function of turbulent velocity fluctuations in rough-wall boundary layer
The probability density function of single-point velocity fluctuations in
turbulence is studied systematically using Fourier coefficients in the
energy-containing range. In ideal turbulence where energy-containing motions
are random and independent, the Fourier coefficients tend to Gaussian and
independent of each other. Velocity fluctuations accordingly tend to Gaussian.
However, if energy-containing motions are intermittent or contaminated with
bounded-amplitude motions such as wavy wakes, the Fourier coefficients tend to
non-Gaussian and dependent of each other. Velocity fluctuations accordingly
tend to non-Gaussian. These situations are found in our experiment of a
rough-wall boundary layer.Comment: 6 pages, to appear in Physical Review
トクシマシ ゼンリツセンガン ケンシン ノ ゲンキョウ ト カダイ : ダイ2ホウ カコ 3ネンカン ノ ヒカク ケントウ
The aim of this study is to clarify the usefulness of PSA screening to detect prostate cancer subclinically in Tokushima City. Mass screening of serum PSA measurement only was started from 2002 in Tokushima City. Three years’ results are reported and analyzed in this paper.
In 2002 to 2004,(9099,9345,10680) men over 55 years old were measured serum PSA level with annual check of health condition at various outpatient clinics in Tokushima City. The men with high PSA levels were recommended to visit the urologist for further examinations. By the urologists the men with high PSA levels were diagnosed by careful urologic procedures including DRE, TRUS, accurate prostatic biopsy and more.
In (801,606,727) men, PSA levels were over normal range, and (455,257,358) men visited urologic clinics for further examinations. Careful examinations were performed and prostatic biopsies were done in (233,121,141) men. Finally, the prostate cancers were found out in (121,60,59) men and these men were entered suitable medical treatments immediately. Accordingly, (1.34%,0.64%,0.55%) of (9099,9345,10680) men with PSA measurements were diagnosed as prostate cancers. In the group of prostate cancer, patient number of early cancer group (Stage B) were (80:66.1%,42:70.0%,50:84.7%),which means that prostate cancers found out by PSA screening might be early curable cancers in many cases.
These 3 years’ results indicate that PSA screening is a very useful modality to find out early prostate cancers and contribute the decrease of prostate cancer death in Tokushima City in the future
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