7,694 research outputs found
Controllable Goos-H\"{a}nchen shifts and spin beam splitter for ballistic electrons in a parabolic quantum well under a uniform magnetic field
The quantum Goos-H\"{a}nchen shift for ballistic electrons is investigated in
a parabolic potential well under a uniform vertical magnetic field. It is found
that the Goos-H\"{a}nchen shift can be negative as well as positive, and
becomes zero at transmission resonances. The beam shift depends not only on the
incident energy and incidence angle, but also on the magnetic field and Landau
quantum number. Based on these phenomena, we propose an alternative way to
realize the spin beam splitter in the proposed spintronic device, which can
completely separate spin-up and spin-down electron beams by negative and
positive Goos-H\"{a}nchen shifts.Comment: 6 pages, 6 figure
Experimental Investigation of Longitudinal Space-Time Correlations of the Velocity Field in Turbulent Rayleigh-B\'{e}nard Convection
We report an experimental investigation of the longitudinal space-time
cross-correlation function of the velocity field, , in a cylindrical
turbulent Rayleigh-B\'{e}nard convection cell using the particle image
velocimetry (PIV) technique. We show that while the Taylor's frozen-flow
hypothesis does not hold in turbulent thermal convection, the recent elliptic
model advanced for turbulent shear flows [He & Zhang, \emph{Phys. Rev. E}
\textbf{73}, 055303(R) (2006)] is valid for the present velocity field for all
over the cell, i.e., the isocorrelation contours of the measured
have a shape of elliptical curves and hence can be related to
via with and
being two characteristic velocities. We further show that the fitted is
proportional to the mean velocity of the flow, but the values of are
larger than the theoretical predictions. Specifically, we focus on two
representative regions in the cell: the region near the cell sidewall and the
cell's central region. It is found that and are approximately
the same near the sidewall, while at cell center.Comment: 16 pages, 15 figures, submitted to J. Fluid Mec
Effect of Salvia miltiorrhiza Bge extract on liver cirrhosis in rats
Purpose: To explore the effects of Salvia miltiorrhiza Bge.extract(SMBE) on diethylnitrosamine(DEN)- induced liver cirrhosis in rats.Methods: SMBE was obtained by extracting dried Salvia miltiorrhiza Bge. in water. Liver cirrhosis was induced in Wistar rats by injecting diethylnitrosamine in abdominal cavity once a week for 8 weeks. Concurrently, rats received either daily oral SMBE (SMBE group) or saline (control group). Clinical biochemical assessments, oxidative stress tests (malondialdehyde [MDA], superoxide dismutase [SOD]) were performed at 4 and 8 weeks after beginning DEN.Results: Compared to the control group, both plasma alanine transaminase (ALT, 245.6 ± 8.5 U/L) and aspartate aminotransferase (AST, 205.7 ± 5.1 U/L) were significantly lower in SMBE group after 8 weeks (p < 0.01 for both ALT and AST). SMBE group exhibited significantly lower MDA (0.41 ± 0.04 μmol/L) levels and higher SOD(0.53 ± 0.05 U/mg protein) activity than control at 8 weeks after commencing DEN (p < 0.01 for both MDA and SOD).Conclusion: SMBE has significant ameliorative effect on DEN-induced liver cirrhosis in rats. Antioxidant and anti-apoptotic effects of SMBE appear to be involved in these beneficial effects.Keywords: Salvia miltiorrhiza, Liver cirrhosis, Anti-oxidant, Anti-apoptotic, Diethylnitrosamine, Biochemical parameter
Revisiting the as a hadronic molecule and its strong decays
Recently, the Belle collaboration measured the ratios of the branching
fractions of the newly observed excited state. They did not
observe significant signals for the decay, and reported an upper limit for the ratio of the three
body decay to the two body decay mode of . In
this work, we revisit the newly observed from the molecular
perspective where this resonance appears to be a dynamically generated state
with spin-parity from the coupled channels interactions of the and in -wave and in -wave. With
the model parameters for the -wave interaction, we show that the ratio of
these decay fractions reported recently by the Belle collaboration can be
easily accommodated.Comment: Published version. Published in Eur.\ Phys.\ J.\ C {\bf 80}, 361
(2020
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