123 research outputs found
Emissive Mechanism on Spectral Variability of Blazars in High Frequencies
The new results of the evolution of the synchrotron peak for Mrk 421 are
mostly likely related to the particle acceleration process. In order to account
for the above results, we present a model of blazar variability during the
flare in which the emission comes from accelerating electrons. A diffusion
advection equation of the electron energy distribution is derived to calculate
the spectrum and light curve of synchrotron radiation. We present that the
observed shifts of the synchrotron peak moving to higher energies during the
flare are caused by shock acceleration. The observed relation between changes
in the fluxes at specified frequency ranges and shifts of the peak position is
fitted to constrain the physical parameters of the dissipation region.Comment: 24 pages, 6 figures, Paper submitted to Ap
The new model of fitting the spectral energy distributions of Mkn 421 and Mkn 501
The spectral energy distribution (SED) of TeV blazars has a double-humped
shape that is usually interpreted as Synchrotron Self Compton (SSC) model. The
one zone SSC model is used broadly but cannot fit the high energy tail of SED
very well. It need bulk Lorentz factor which is conflict with the observation.
Furthermore one zone SSC model can not explain the entire spectrum. In the
paper, we propose a new model that the high energy emission is produced by the
accelerated protons in the blob with a small size and high magnetic field, the
low energy radiation comes from the electrons in the expanded blob. Because the
high and low energy photons are not produced at the same time, the requirement
of large Doppler factor from pair production is relaxed. We present the fitting
results of the SEDs for Mkn 501 during April 1997 and Mkn 421 during March 2001
respectively.Comment: 5 pages, 1 figures, 1table. accepted for publication in Sciences in
China --
Albumin-associated free fatty acids induce macropinocytosis in podocytes
Podocytes are specialized epithelial cells in the kidney glomerulus that play important structural and functional roles in maintaining the filtration barrier. Nephrotic syndrome results from a breakdown of the kidney filtration barrier and is associated with proteinuria, hyperlipidemia, and edema. Additionally, podocytes undergo changes in morphology and internalize plasma proteins in response to this disorder. Here, we used fluid-phase tracers in murine models and determined that podocytes actively internalize fluid from the plasma and that the rate of internalization is increased when the filtration barrier is disrupted. In cultured podocytes, the presence of free fatty acids (FFAs) associated with serum albumin stimulated macropinocytosis through a pathway that involves FFA receptors, the Gβ/Gγ complex, and RAC1. Moreover, mice with elevated levels of plasma FFAs as the result of a high-fat diet were more susceptible to Adriamycin-induced proteinuria than were animals on standard chow. Together, these results support a model in which podocytes sense the disruption of the filtration barrier via FFAs bound to albumin and respond by enhancing fluid-phase uptake. The response to FFAs may function in the development of nephrotic syndrome by amplifying the effects of proteinuria
Electron Cooling Experiments in CSR
The six species heavy ion beam was accumulated with the help of electron
cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility
in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters
of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u
129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force
was measured in different condition.Comment: 5 pages 11 figure
A mathematical and computational review of Hartree-Fock SCF methods in Quantum Chemistry
We present here a review of the fundamental topics of Hartree-Fock theory in
Quantum Chemistry. From the molecular Hamiltonian, using and discussing the
Born-Oppenheimer approximation, we arrive to the Hartree and Hartree-Fock
equations for the electronic problem. Special emphasis is placed in the most
relevant mathematical aspects of the theoretical derivation of the final
equations, as well as in the results regarding the existence and uniqueness of
their solutions. All Hartree-Fock versions with different spin restrictions are
systematically extracted from the general case, thus providing a unifying
framework. Then, the discretization of the one-electron orbitals space is
reviewed and the Roothaan-Hall formalism introduced. This leads to a exposition
of the basic underlying concepts related to the construction and selection of
Gaussian basis sets, focusing in algorithmic efficiency issues. Finally, we
close the review with a section in which the most relevant modern developments
(specially those related to the design of linear-scaling methods) are commented
and linked to the issues discussed. The whole work is intentionally
introductory and rather self-contained, so that it may be useful for non
experts that aim to use quantum chemical methods in interdisciplinary
applications. Moreover, much material that is found scattered in the literature
has been put together here to facilitate comprehension and to serve as a handy
reference.Comment: 64 pages, 3 figures, tMPH2e.cls style file, doublesp, mathbbol and
subeqn package
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