3,760 research outputs found
Nonexistence of self-similar singularities for the 3D incompressible Euler equations
We prove that there exists no self-similar finite time blowing up solution to
the 3D incompressible Euler equations. By similar method we also show
nonexistence of self-similar blowing up solutions to the divergence-free
transport equation in . This result has direct applications to the
density dependent Euler equations, the Boussinesq system, and the
quasi-geostrophic equations, for which we also show nonexistence of
self-similar blowing up solutions.Comment: This version refines the previous one by relaxing the condition of
compact support for the vorticit
Asymmetry in fatigue and recovery in ferroelectric Pb(Zr,Ti)O3 thin-film capacitors
We investigate the fatigue and refreshment by dc-electrical field of the
electrical properties of Pt/Pb(Ti,Zr)O/Pt ferroelectric capacitors. We find
an asymmetry in the refreshment, that is, the fatigued state can be refreshed
by application of negative high dc-voltage to the top electrode, but no
refreshment is measured by positive dc-voltage application. We also find that
the fatigue can be prevented by driving the capacitor asymmetrically.Comment: 4 pages, 5 figure
Silibinin induces apoptosis via calpain-dependent AIF nuclear translocation in U87MG human glioma cell death
<p>Abstract</p> <p>Background</p> <p>Silibinin, a natural polyphenolic flavonoid, has been reported to induce cell death in various cancer cell types. However, the molecular mechanism is not clearly defined. Our previous study showed that silibinin induces glioma cell death and its effect was effectively prevented by calpain inhibitor. The present study was therefore undertaken to examine the role of calpain in the silibinin-induced glioma cell death.</p> <p>Methods</p> <p>U87MG cells were grown on well tissue culture plates and cell viability was measured by MTT assay. ROS generation and △ψ<sub>m </sub>were estimated using the fluorescence dyes. PKC activation and Bax expression were measured by Western blot analysis. AIF nuclear translocation was determined by Western blot and immunocytochemistry.</p> <p>Results</p> <p>Silibinin induced activation of calpain, which was blocked by EGTA and the calpain inhibitor Z-Leu-Leu-CHO. Silibinin caused ROS generation and its effect was inhibited by calpain inhibitor, the general PKC inhibitor GF 109203X, the specific PKC<sub>δ </sub>inhibitor rottlerin, and catalase. Silibinin-induce cell death was blocked by calpain inhibitor and PKC inhibitors. Silibinin-induced PKC<sub>δ </sub>activation and disruption of △ψ<sub>m </sub>were prevented by the calpain inhibitor. Silibinin induced AIF nuclear translocation and its effect was prevented by calpain inhibitor. Transfection of vector expressing microRNA of AIF prevented the silibinin-induced cell death.</p> <p>Conclusions</p> <p>Silibinin induces apoptotic cell death through a calpain-dependent mechanism involving PKC, ROS, and AIF nuclear translocation in U87MG human glioma cells.</p
On the global well-posedness for the Boussinesq system with horizontal dissipation
In this paper, we investigate the Cauchy problem for the tridimensional
Boussinesq equations with horizontal dissipation. Under the assumption that the
initial data is an axisymmetric without swirl, we prove the global
well-posedness for this system. In the absence of vertical dissipation, there
is no smoothing effect on the vertical derivatives. To make up this
shortcoming, we first establish a magic relationship between
and by taking full advantage of the structure of the
axisymmetric fluid without swirl and some tricks in harmonic analysis. This
together with the structure of the coupling of \eqref{eq1.1} entails the
desired regularity.Comment: 32page
Strong lensing constraints on the velocity dispersion and density profile of elliptical galaxies
We use the statistics of strong gravitational lensing from the CLASS survey
to impose constraints on the velocity dispersion and density profile of
elliptical galaxies. This approach differs from much recent work, where the
luminosity function, velocity dispersion and density profile were typically
{\it assumed} in order to constrain cosmological parameters. It is indeed
remarkable that observational cosmology has reached the point where we can
consider using cosmology to constrain astrophysics, rather than vice versa. We
use two different observables to obtain our constraints (total optical depth
and angular distributions of lensing events). In spite of the relatively poor
statistics and the uncertain identification of lenses in the survey, we obtain
interesting constraints on the velocity dispersion and density profiles of
elliptical galaxies. For example, assuming the SIS density profile and
marginalizing over other relevant parameters, we find 168 km/s < sigma_* < 200
km/s (68% CL), and 158 km/s < sigma_* < 220 km/s (95% CL). Furthermore, if we
instead assume a generalized NFW density profile and marginalize over other
parameters, the slope of the profile is constrained to be 1.50 < beta < 2.00
(95% CL). We also constrain the concentration parameter as a function of the
density profile slope in these models. These results are essentially
independent of the exact knowledge of cosmology. We briefly discuss the
possible impact on these constraints of allowing the galaxy luminosity function
to evolve with redshift, and also possible useful future directions for
exploration.Comment: Uses the final JVAS/CLASS sample, more careful choice of ellipticals,
added discussion of possible biases. Final results essentially unchanged.
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Observations of bunch lengthening effects in the APS 7-GeV storage ring
Measurements of the bunch length and horizontal beam size at a dispersive point in the lattice versus single-bunch current have been done on the Advanced Photo Source (APS) 7-GeV storage ring. These data are relevant to issues (limits) of obtaining high peak currents for storage-ring-based FELs. Bunch lengths from {sigma}{sub {tau}} {approx} 25 to 70 ps were measured using a Hamamatsu C5680 dual-sweep streak camera. Additional complementary data on energy spread deduced from horizontal beam size at a dispersive point in the lattice were also tracked versus single-bunch current. Both optical synchrotron radiation (OSR) and x-ray synchrotron radiation (XSR) techniques were used. For the set of data taken at a synchrotron frequency of 1.2 kHz (indicating rf gap voltage {<=} 6 MV), the significant bunch lengthening without a comparable horizontal size change ({Delta}E growth) is consistent with the potential well distortion model rather than the predictions of a microwave instability calculation. With higher rf gap voltage, peak currents up to 400 A were observed. A bunch-lengthening effect in multibunch mode was also observed as the stored-beam current approached the available rf power limit
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