2,723 research outputs found
The Happer's puzzle degeneracies and Yangian
We find operators distinguishing the degenerate states for the Hamiltonian
at that was given by Happer
et al to interpret the curious degeneracies of the Zeeman effect for
condensed vapor of Rb. The operators obey Yangian commutation relations.
We show that the curious degeneracies seem to verify the Yangian algebraic
structure for quantum tensor space and are consistent with the representation
theory of .Comment: 8 pages, Latex fil
-band host galaxy contamination of TeV -ray blazar Mrk 501: effects of the aperture size and seeing
We simulated the -band contribution of the host galaxy of TeV -ray
BL Lac object Mrk 501 in different aperture sizes and seeing conditions . The
intensive observations were run with the 1.02 m optical telescope at Yunnan
Observatories from 2010 May 15 to 18. Based on the host subtraction data
presented in Nilsson et al. (2007), the subtraction of host galaxy
contamination results in significant seeing-brightness correlations. These
correlations would lead to illusive large amplitude variations at short
timescales, which will mask the intrinsic micro variability, thus gives rise to
difficulty in detecting the intrinsic micro variability. Both aperture size and
seeing condition influence the flux measurements, but aperture size impact the
result more significantly. Based on the parameters of elliptical galaxy
provided in Nilsson et al. (1999), we simulated the host contributions of Mrk
501 in the different aperture sizes and seeing conditions. Our simulation data
of the host galaxy obviously weaken these significant seeing-brightness
correlations for the host-subtracted brightness of Mrk 501, and can help us
discover the intrinsic short timescale micro variability. The pure nuclear flux
is 8.0 in \emph{R} band, i.e., AGN has a magnitude of
.Comment: accepted for publication in Research in Astronomy and Astrophysics, 8
figures, 6 table
On the external photon fields in Fermi bright blazars
The external Compton (EC) model is used to study the high energy emission of
some blazars, in which the external photon field is considered to dominate
inverse Compton radiation. We explore the properties of external photon field
through analyzing the FERMI LAT bright AGN sample within three months
detection. In the sample, assuming the high energy radiation of low synchrotron
peaked blazars from the EC process, we find that the external photon parameter
Uext/\nuext may not be a constant. Calculating synchrotron and inverse Compton
(IC) luminosity from the quasi-simultaneous broadband spectrum energy
distributions (SEDs), we find that they have an approximately linear relation.
This indicates that the ratio of external photon and magnetic energy density is
a constant in the comoving frame, implying that the Lorentz factor of the
emitting blob depends on external photon field and magnetic field. The result
gives a strong constraint on the jet dynamic model.Comment: 7 pages, 2 figure
The Role of Matrine and Mitogen-Ativated Protein Kinase/Extracellular Signal-Regulated Kinase Signal Transduction in the Inhibition of the Proliferation and Migration of Human Umbilical Veins Endothelial Cells Induced by Lung Cancer cells
Background and objective Matrine, one of the major alkaloid components of the traditional Chinese medicine Sophora roots, has a wide range of pharmacological effects including anti-inflammatory activities, growth inhibition and induction of cell differentiation and apoptosis. Motigen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) has found to be a crucial signaling pathway in endothelial cells. The aim of this study is to investigate the role of Matrine and MAPK/ERK signal transduction in the inhibition of the proliferation and migration of human umbilical veins endothelial cells (HUVECs) induced by lung cancer cells. Methods HUVECs were cultured with A549CM. Mat or PD98059 (i.e PD), specific inhibitor of MAPK/ERK, was added into the A549CM. The proliferation of the HUVECs was measured by cell counting. The migration of the HUVECs was observed by wound healing assay. The expression levels of ERK and p-ERK protein were detected by Western Blot analysis. Results On 24 hours after intervention, the A549CM significantly stimulated the proliferation, migration and expression of p-ERK of HUVECs. Compared with the A549CM group, Mat significantly inhibited the proliferation, migration and p-ERK expression of HUVECs induced by A549CM. While PD only decreased the proliferation and p-ERK expression of HUVECs induced by A549CM. PD had no effect in the migration of HUVECs. Conclusion The results demonstrated that Mat and PD98059 can effectively decrease proliferation and expression of p-ERK of HUVECs induced by A549CM. Furthermore Mat can also inhibit migration of HUVECs induced by A549CM that did not changed by PD98059. These data implied that suppressing MAPK/ERK signal transduction may play the crucial role in resisting lung cacinoma angiogenesis with Mat
Statistical Origin of Constituent-Quark Scaling in the QGP hadronization
Nonextensive statistics in a Blast-Wave model (TBW) is implemented to
describe the identified hadron production in relativistic p+p and
nucleus-nucleus collisions. Incorporating the core and corona components within
the TBW formalism allows us to describe simultaneously some of the major
observations in hadronic observables at the Relativistic Heavy-Ion Collider
(RHIC): the Number of Constituent Quark Scaling (NCQ), the large radial and
elliptic flow, the effect of gluon saturation and the suppression of hadron
production at high transverse momentum (pT) due to jet quenching. In this
formalism, the NCQ scaling at RHIC appears as a consequence of non-equilibrium
process. Our study also provides concise reference distributions with a least
chi2 fit of the available experimental data for future experiments and models.Comment: 4 pages, 3 figures; added two tables, explained a little bit more on
TBW_p
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IV. H Time Lags and Implications for Super-Eddington Accretion
We have completed two years of photometric and spectroscopic monitoring of a
large number of active galactic nuclei (AGNs) with very high accretion rates.
In this paper, we report on the result of the second phase of the campaign,
during 2013--2014, and the measurements of five new H time lags out of
eight monitored AGNs. All five objects were identified as super-Eddington
accreting massive black holes (SEAMBHs). The highest measured accretion rates
for the objects in this campaign are , where
,
is the mass accretion rates, is the Eddington luminosity and
is the speed of light. We find that the H time lags in SEAMBHs are
significantly shorter than those measured in sub-Eddington AGNs, and the
deviations increase with increasing accretion rates. Thus, the relationship
between broad-line region size () and optical luminosity at
5100\AA, , requires accretion rate as an additional
parameter. We propose that much of the effect may be due to the strong
anisotropy of the emitted slim-disk radiation. Scaling by
the gravitational radius of the black hole, we define a new radius-mass
parameter () and show that it saturates at a critical accretion rate of
, indicating a transition from thin to slim
accretion disk and a saturated luminosity of the slim disks. The parameter
is a very useful probe for understanding the various types of accretion onto
massive black holes. We briefly comment on implications to the general
population of super-Eddington AGNs in the universe and applications to
cosmology.Comment: 53 pages, 12 figures, 7 tables, accepted for publication in The
Astrophysical Journa
ICA-SVM combination algorithm for identification of motor imagery potentials
Mental tasks such as motor imagery in synchronization with a cue which result event related desynchronization (ERD) and event related synchronization (ERS) are usually studied in brain-computer interface (BCI) system. In this paper we analyze and classify the ERD/ERS response evoked by the motor imagery of left hand, right hand, foot and tongue. The signals were spatially filtered by Independent Component Analysis (ICA) before calculating the power spectral density (PSD) for related electrodes, and then the Support Vector Machine (SVM) was adopted to recognise the different imagery pattern according to ERD/ERS feature for the signals. The results showed that the combination of ICA-based signal extraction algorithm and SVM-based classification method was an effective tool for the identification of motor imagery potentials, with the highest accuracy rate of 91.4% and 77.6% for the lowest. © 2010 IEEE.published_or_final_versionThe 2010 IEEE International Conference on Computational Intelligence for Measurement Systems and Applications (CIMSA), Taranto, Apulia, Italy, 6-8 September 2010. In Proceedings of IEEE-CIMSA, 2010, p. 92-9
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