1,144 research outputs found
The Largest Blueshifts of [O III] emission line in Two Narrow-Line Quasars
We have obtained optical intermediate resolution spectra (R = 3000) of the
narrow-line quasars DMS 0059-0055 and PG 1543+489. The [O III] emission line in
DMS 0059-0055 is blueshifted by 880 km/s relative to Hbeta. We also confirm
that the [O III] emission line in PG 1543+489 has a relative blueshift of 1150
km/s. These two narrow-line quasars show the largest [O III] blueshifts known
to date among type 1 active galactic nuclei (AGNs). The [O III] emission lines
in both objects are broad (1000 - 2000 km/s) and those in DMS 0059-0055 show
strong blue asymmetry. We interpret the large blueshift and the profile of the
[O III] lines as the result of an outflow interacting with circumnuclear gas.
Among type 1 AGNs with large blueshifted [O III], there is no correlation
between the Eddington ratios and the amount of [O III] blueshifts. Combining
our new data with published results, we confirm that the Eddington ratios of
the such AGNs are the highest among AGNs with the same black hole masses. These
facts suggest that the Eddington ratio is a necessary condition or the [O III]
blueshifts weakly depend on the Eddington ratio. Our new sample suggests that
there are possible necessary conditions to produce an outflow besides a high
Eddington ratio: large black hole mass (> 10^7 M_solar) or high mass accretion
rate (> 2 M_solar/yr) or large luminosity (lambda L_{lambda} (5100A) > 10^44.6
erg/s).Comment: Accepted for publication in The Astrophysical Journa
High Quality Factor Silicon Cantilever Driven by PZT Actuator for Resonant Based Mass Detection
A high quality factor (Q-factor) piezoelectric lead zirconat titanate (PZT)
actuated single crystal silicon cantilever was proposed in this paper for
resonant based ultra-sensitive mass detection. Energy dissipation from
intrinsic mechanical loss of the PZT film was successfully compressed by
separating the PZT actuator from resonant structure. Excellent Q-factor, which
is several times larger than conventional PZT cantilever, was achieved under
both atmospheric pressure and reduced pressures. For a 30 micrometer-wide 100
micrometer-long cantilever, Q-factor was measured as high as 1113 and 7279
under the pressure of 101.2 KPa and 35 Pa, respectively. Moreover, it was found
that high-mode vibration can be realized by the cantilever for the pursuit of
great Q-factor, while support loss became significant because of the increased
vibration amplitude at the actuation point. An optimized structure using
node-point actuation was suggested then to suppress corresponding energy
dissipation.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
Electron transport through Aharonov-Bohm interferometer with laterally coupled double quantum dots
We theoretically investigate electron transport through an Aharonov-Bohm
interferometer containing laterally coupled double quantum dots. We introduce
the indirect coupling parameter , which characterizes the strength of
the coupling via the reservoirs between two quantum dots.
indicates the strongest coupling, where only a single mode contributes to the
transport in the system. Two conduction modes exist in a system where
. The interference effects such as the Fano resonance and the
Aharonov-Bohm oscillation are suppressed as the absolute value of the parameter
decreases from 1. The linear conductance does not depend on the flux
when since it corresponds to independent coupling of the dots to the
reservoir modes.Comment: 15 pages, 13 figure
Transport and magnetic properties of Co-doped BaFe_{2}As_{2} epitaxial thin films
We report resistivity, Hall coefficient, current-voltage characteristics, and
magneto-optical imaging measurements of epitaxial Co-doped BaFe_{2}As_{2} thin
films deposited on MgO(001) substrate. The Hall resistivity of the films has a
substantial contribution arising from anomalous Hall effect of ferromagnetic
components. The critical current density (J_{c}) of the films is ~2 MA/cm^{2}
at low temperatures. Differential magneto-optical images of the remanent state
give similar J_{c} values and also exhibit presence of extended defects in the
film.Comment: 9 pages, 4 figure
Varying-coefficient modeling via regularized basis functions
We address the problem of constructing varying-coefficient models based on
basis expansions along with the technique of regularization. A crucial point in
our modeling procedure is the selection of smoothing parameters in the
regularization method. In order to choose the parameters objectively, we derive
model selection criteria from the viewpoints of information-theoretic and
Bayesian approach. We demonstrate the effectiveness of proposed modeling
strategy through Monte Carlo simulations and analyzing a real data set.Comment: 10 pages, 4 figure
Characteristics of Oxidative Storage Stability of Canola Fatty Acid Methyl Ester Stabilised with Antioxidants
The storage effects on the oxidation characteristics of fatty acid methyl ester of canola oil (CME) were investigated in this study.CME stabilised with two antioxidants, i.e.2,6-di-tert-bytyl-p-cresol (BHT) and 6,6-di-tert-butyl-2, 2'-methylendi-p-cresol (BPH), was stored at 20, 40 and 60°C.The oxidation stability data were measured by the Rancimat test method and it was found that both BHT and BPH addition increased the oxidation resistance of the CME. The results showed that when BPH or BHT was added at a concentration of 100 ppm, the oxidation induction period of the neat CME samples increased from 5.53 h to 6.93 hand 6.14 h, respectively. Comparing both antioxidants, BPH proved to be more effective in increasing the oxidation resistance when both antioxidants were added at the same concentration. Furthermore, the oxidation induction timedecreased linearly with the storage time. It was shown that the oxidation occurred rapidly in the first 8 weeks of storage. Later, a kinetic study was undertaken and first-order kinetics were applied to explain the oxidation characteristics of the CME added with antioxidants. This kinetic study focused on exploiting the activation energy values obtained from the Arrheniusequations. Also, the oxidation effects on other quality parameters, including acid value, peroxide value, kinematic viscosity, and water content, were examined
String Theoretical Interpretation for Finite N Yang-Mills Theory in Two-Dimensions
We discuss the equivalence between a string theory and the two-dimensional
Yang-Mills theory with SU(N) gauge group for finite N. We find a sector which
can be interpreted as a sum of covering maps from closed string world-sheets to
the target space, whose covering number is less than N. This gives an
asymptotic expansion of 1/N whose large N limit becomes the chiral sector
defined by D.Gross and W.Taylor. We also discuss that the residual part of the
partition function provides the non-perturbative corrections to the
perturbative expansion.Comment: 15 pages, no figures, LaTeX2e, typos corrected, final version to
appear in Modern Physics Letters
First Detection of 12CO (1--0) Emission from Two Narrow-Line Seyfert 1 Galaxies
In order to investigate how the growth of galactic bulges progresses with the
growth of central black holes (BHs), we observed molecular gas (fuel for the
coming star formation) in possibly young active galaxies, narrow-line Seyfert 1
galaxies (NLS1s). We present the results of radio observations of 12CO(1--0)
using the Nobeyama Millimeter Array (with 2--4 kpc spatial resolution) for two
FIR-bright NLS1s, yielding the first detection of their CO emission.
Corresponding molecular--gas masses M(H2) of (1-3) X 109 Msun are the 2nd and
4th largest ones among NLS1s. By estimating dynamical masses and bulge masses
M(bulge) for these two NLS1s using CO channel map and CO line widths, we found
M(H2) amount to 0.13--0.35 of these masses. Taking account the star formation
efficiency (~ 0.1), the increase in M(bulge) in those NLS1s in the near future
(~< 10^{7.5} yr) is expected not to be a huge fraction (1--5% of the
preexisting stars). Bulge growth may have finished before BH growth, or
bulge--BH coevolution may proceed with many, occasional discrete events, where
one coevolution event produces only a small amount of mass growth of BHs and of
bulges. We also discuss the ratios of star-formation rate--to--gas accretion
rate onto BHs, finding that two NLS1s have very small ratios (~ 1) compared
with the M(bulge)/M(BH) ratios found in active and inactive galaxies (~ 700).
This huge difference suggests either the non-overlapped coevolution, long star
formation duration or temporarily high accretion rate during NLS1 phase.Comment: 29 pages, 8 figures, Accepted for publication in The Astrophysical
Journa
Geometric Approach to Lyapunov Analysis in Hamiltonian Dynamics
As is widely recognized in Lyapunov analysis, linearized Hamilton's equations
of motion have two marginal directions for which the Lyapunov exponents vanish.
Those directions are the tangent one to a Hamiltonian flow and the gradient one
of the Hamiltonian function. To separate out these two directions and to apply
Lyapunov analysis effectively in directions for which Lyapunov exponents are
not trivial, a geometric method is proposed for natural Hamiltonian systems, in
particular. In this geometric method, Hamiltonian flows of a natural
Hamiltonian system are regarded as geodesic flows on the cotangent bundle of a
Riemannian manifold with a suitable metric. Stability/instability of the
geodesic flows is then analyzed by linearized equations of motion which are
related to the Jacobi equations on the Riemannian manifold. On some geometric
setting on the cotangent bundle, it is shown that along a geodesic flow in
question, there exist Lyapunov vectors such that two of them are in the two
marginal directions and the others orthogonal to the marginal directions. It is
also pointed out that Lyapunov vectors with such properties can not be obtained
in general by the usual method which uses linearized Hamilton's equations of
motion. Furthermore, it is observed from numerical calculation for a model
system that Lyapunov exponents calculated in both methods, geometric and usual,
coincide with each other, independently of the choice of the methods.Comment: 22 pages, 14 figures, REVTeX
Reduction of quantum systems on Riemannian manifolds with symmetry and application to molecular mechanics
This paper deals with a general method for the reduction of quantum systems
with symmetry. For a Riemannian manifold M admitting a compact Lie group G as
an isometry group, the quotient space Q = M/G is not a smooth manifold in
general but stratified into a collection of smooth manifolds of various
dimensions. If the action of the compact group G is free, M is made into a
principal fiber bundle with structure group G. In this case, reduced quantum
systems are set up as quantum systems on the associated vector bundles over Q =
M/G. This idea of reduction fails, if the action of G on M is not free.
However, the Peter-Weyl theorem works well for reducing quantum systems on M.
When applied to the space of wave functions on M, the Peter-Weyl theorem
provides the decomposition of the space of wave functions into spaces of
equivariant functions on M, which are interpreted as Hilbert spaces for reduced
quantum systems on Q. The concept of connection on a principal fiber bundle is
generalized to be defined well on the stratified manifold M. Then the reduced
Laplacian is well defined as a self-adjoint operator with the boundary
conditions on singular sets of lower dimensions. Application to quantum
molecular mechanics is also discussed in detail. In fact, the reduction of
quantum systems studied in this paper stems from molecular mechanics. If one
wishes to consider the molecule which is allowed to lie in a line when it is in
motion, the reduction method presented in this paper works well.Comment: 33 pages, no figure
- …