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 $y$-parameter is of the order of unity (and thus the photon index will be $\sim 2$) when the apparent photon luminosity is ${\sim}30L_{\rm E}$ (with $L_{\rm E}$ 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

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