867 research outputs found
Kredibilitas Customer Service Dan Citra Perusahaan
: This study aims to analyse the relationship between credibility of customer service and corporate image by using explanatory with quantitative approach as the method. The total number of participants was 100. They are customers who have complaint or critique to the customer service about their service or other issues. It is found that there is a strong correlation between customer service and corporate image (r=0,743 or 74,3%). Sex, age, and education are the factors that determine this correlation
X-Ray Fluctuations from Locally Unstable Advection-Dominated Disks
The response of advection-dominated accretion disks to local disturbances is
examined by one-dimensional numerical simulations. It is generally believed
that advection-dominated disks are thermally stable. We, however, find that any
disurbance added onto accretion flow at large radii does not decay so rapidly
that it can move inward with roughly the free-fall velocity. Although
disturbances continue to be present, the global disk structure will not be
modified largely. This can account for persistent hard X-ray emission with
substantial variations observed in active galactic nuclei and stellar black
hole candidates during the hard state. Moreover, when the disturbance reaches
the innermost parts, an acoustic wave emerges, propagating outward as a shock
wave. The resultant light variation is roughly (time) symmetric and is quite
reminiscent of the observed X-ray shots of Cygnus X-1.Comment: plain TeX, 11 pages, without figures; to be published in ApJ Lette
Variability of Active Galactic Nuclei from the Optical to X-ray Regions
Some progress in understanding AGN variability is reviewed. Reprocessing of
X-ray radiation to produce significant amounts of longer-wavelength continua
seems to be ruled out. In some objects where there has been correlated X-ray
and optical variability, the amplitude of the optical variability has exceeded
the amplitude of X-ray variability. We suggest that accelerated particles
striking material could be linking X-ray and optical variability (as in
activity in the solar chromosphere). Beaming effects could be significant in
all types of AGN. The diversity in optical/X-ray relationships at different
times in the same object, and between different objects, might be explained by
changes in geometry and directions of motion relative to our line of sight.
Linear shot-noise models of the variability are ruled out; instead there must
be large-scale organization of variability. Variability occurs on
light-crossing timescales rather than viscous timescales and this probably
rules out the standard Shakura-Sunyaev accretion disk. Radio-loud and
radio-quiet AGNs have similar continuum shapes and similar variability
properties. This suggests similar continuum origins and variability mechanisms.
Despite their extreme X-ray variability, narrow-line Seyfert 1s (NLS1s) do not
show extreme optical variability.Comment: Invited talk given at Euro Asian Astronomical Society meeting in
Moscow, June 2002. 20 pages, 4 figures. References update
Three years of Fermi GBM Earth Occultation Monitoring: Observations of Hard X-ray/Soft Gamma-Ray Sources
The Gamma ray Burst Monitor (GBM) on board Fermi has been providing
continuous data to the astronomical community since 2008 August 12. In this
paper we present the results of the analysis of the first three years of these
continuous data using the Earth occultation technique to monitor a catalog of
209 sources. From this catalog, we detect 99 sources, including 40 low-mass
X-ray binary/neutron star systems, 31 high-mass X-ray binary neutron star
systems, 12 black hole binaries, 12 active galaxies, 2 other sources, plus the
Crab Nebula, and the Sun. Nine of these sources are detected in the 100-300 keV
band, including seven black-hole binaries, the active galaxy Cen A, and the
Crab. The Crab and Cyg X-1 are also detected in the 300-500 keV band. GBM
provides complementary data to other sky-monitors below 100 keV and is the only
all-sky monitor above 100 keV. Up-to-date light curves for all of the catalog
sources can be found at http://heastro.phys.lsu.edu/gbm/.Comment: 24 pages, 12 figures, accepted for publication in ApJ
Discovery of TUG-770: a highly potent free fatty acid receptor 1 (FFA1/GPR40) agonist for treatment of type 2 diabetes
Free fatty acid receptor 1 (FFA1 or GPR40) enhances glucose-stimulated insulin secretion from pancreatic β-cells and currently attracts high interest as a new target for the treatment of type 2 diabetes. We here report the discovery of a highly potent FFA1 agonist with favorable physicochemical and pharmacokinetic properties. The compound efficiently normalizes glucose tolerance in diet-induced obese mice, an effect that is fully sustained after 29 days of chronic dosing
First Results from Fermi GBM Earth Occultation Monitoring: Observations of Soft Gamma-Ray Sources Above 100 keV
The NaI and BGO detectors on the Gamma-ray Burst Monitor (GBM) on Fermi are
now being used for long-term monitoring of the hard X-ray/low energy gamma-ray
sky. Using the Earth occultation technique as demonstrated previously by the
BATSE instrument on the Compton Gamma-Ray Observatory, GBM can be used to
produce multiband light curves and spectra for known sources and transient
outbursts in the 8 keV to 1 MeV energy range with its NaI detectors and up to
40 MeV with its BGO detectors. Over 85% of the sky is viewed every orbit, and
the precession of the Fermi orbit allows the entire sky to be viewed every ~26
days with sensitivity exceeding that of BATSE at energies below ~25 keV and
above ~1.5 MeV. We briefly describe the technique and present preliminary
results using the NaI detectors after the first two years of observations at
energies above 100 keV. Eight sources are detected with a significance greater
than 7 sigma: the Crab, Cyg X-1, SWIFT J1753.5-0127, 1E 1740-29, Cen A, GRS
1915+105, and the transient sources XTE J1752-223 and GX 339-4. Two of the
sources, the Crab and Cyg X-1, have also been detected above 300 keV.Comment: 13 pages, 9 figures, submitted to Ap
Rms-flux relation of Cyg X-1 with RXTE: dipping and nondipping cases
The rms (root mean square) variability is the parameter for understanding the
emission temporal properties of X-ray binaries (XRBs) and active galactic
nuclei (AGN).
The rms-flux relation with Rossi X-ray Timing Explorer (RXTE) data for the
dips and nondip of black hole Cyg X-1 has been investigated in this paper. Our
results show that there exist the linear rms-flux relations in the frequency
range 0.1-10 Hz for the dipping light curve. Moreover, this linear relation
still remains during the nondip regime, but with the steeper slope than that of
the dipping case in the low energy band. For the high energy band, the slopes
of the dipping and nondipping cases are hardly constant within errors. The
explanations of the results have been made by means of the ``Propagating
Perturbation'' model of Lyubarskii (1997).Comment: 15 pages, 12 figures, Accepted for publication in Astrophysics &
Space Scienc
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