72 research outputs found
Efficiency of Commercial Banks in Sub-Saharan Africa: A Comparative Analysis of Domestic and Foreign Banks
Utilizing the stochastic frontier approach, this study conducts a comparative analysis of profit efficiency and cost inefficiency of commercial banks operating in 29 sub-Saharan African (SSA) countries by bank ownership (domestic bank, SSA foreign bank or non-SSA foreign bank), as well as by the bank size during 2000-07. Tobit regressions are employed to assess the impact of environmental factors on the efficiency of commercial banks. The key findings of this empirical analysis suggest that foreign banks tend to outperform domestic banks in terms of profit efficiency. In terms of efficiency by bank size, the smaller the bank, the more profit efficient the bank will be; medium or relatively large banks tend to be the most cost efficient.banking, stochastic frontier, Tobit regression, Africa
Efficiency of commercial banks in sub-Saharan Africa: A comparative analysis of domestic and foreign banks
Utilizing the stochastic frontier approach, this study conducts a comparative analysis of profit efficiency and cost inefficiency of commercial banks operating in 29 sub-Saharan African (SSA) countries by bank ownership (domestic bank, SSA foreign bank or non-SSA foreign bank), as well as by the bank size during 2000-07. Tobit regressions are employed to assess the impact of environmental factors on the efficiency of commercial banks. The key findings of this empirical analysis suggest that foreign banks tend to outperform domestic banks in terms of profit efficiency. In terms of efficiency by bank size, the smaller the bank, the more profit efficient the bank will be; medium or relatively large banks tend to be the most cost efficient
Spectral Evolution of the Unusual Slow Nova V5558 Sgr
We report on the spectral evolution of the enigmatic, very slow nova V5558
Sgr, based on the low-resolution spectra obtained at the Fujii-Bisei
Observatory and the Bisei Astronomical Observatory, Japan during a period of
2007 April 6 to 2008 May 3. V5558 Sgr shows a pre-maximum halt and then several
flare-like rebrightenings, which is similar to another very slow nova V723 Cas.
In our observations, the spectral type of V5558 Sgr evolved from the He/N type
toward the Fe II type during the pre-maximum halt, and then toward the He/N
type again. This course of spectral transition was observed for the first time
in the long history of the nova research. In the rebrightening stage after the
initial brightness maximum, we could identify many emission lines accompanied
by a stronger absorption component of the P-Cygni profile at the brightness
maxima. We found that the velocity of the P-Cygni absorption component measured
from the emission peak decreased at the brightness maxima. Furthermore, we
compared the spectra of V5558 Sgr with V723 Cas, and other novae which
exhibited several rebrightenings during the early phase.Comment: 8 pages, 7figures, accepted for publication in PAS
The Hydrogen Burning Turn-off of RS Ophiuchi 2006
We report a coordinated multi-band photometry of the RS Oph 2006 outburst and
highlight the emission line free y-band photometry that shows a mid-plateau
phase at y ~ 10.2 mag from day 40 to day 75 after the discovery followed by a
sharp drop of the final decline. Such mid-plateau phases are observed in other
two recurrent novae, U Sco and CI Aql, and are interpreted as a bright disk
irradiated by the white dwarf. We have calculated theoretical light curves
based on the optically thick wind theory and have reproduced the observed light
curves including the mid-plateau phase and the final sharp decline. This final
decline is identified with the end of steady hydrogen shell-burning, which
turned out the day ~80. This turnoff date is consistent with the end of a
supersoft X-ray phase observed with Swift. Our model suggests a white dwarf
mass of 1.35 \pm 0.01 M_\sun, which indicates that RS Oph is a progenitor of
Type Ia supernovae. We strongly recommend the y-filter observation of novae to
detect both the presence of a disk and the hydrogen burning turn-off.Comment: to appear in ApJL, 4 pages including 4 figure
Optical and Near-Infrared Photometry of Nova V2362 Cyg : Rebrightening Event and Dust Formation
We present optical and near-infrared (NIR) photometry of a classical nova,
V2362 Cyg (= Nova Cygni 2006). V2362 Cyg experienced a peculiar rebrightening
with a long duration from 100 to 240 d after the maximum of the nova. Our
multicolor observation indicates an emergence of a pseudophotosphere with an
effective temperature of 9000 K at the rebrightening maximum. After the
rebrightening maximum, the object showed a slow fading homogeneously in all of
the used bands for one week. This implies that the fading just after the
rebrightening maximum ( less or equal 1 week ) was caused by a slowly shrinking
pseudophotosphere. Then, the NIR flux drastically increased, while the optical
flux steeply declined. The optical and NIR flux was consistent with blackbody
radiation with a temperature of 1500 K during this NIR rising phase. These
facts are likely to be explained by dust formation in the nova ejecta. Assuming
an optically thin case, we estimate the dust mass of 10^(-8) -- 10^(-10)
M_solar, which is less than those in typical dust-forming novae. These results
support the senario that a second, long-lasting outflow, which caused the
rebrightening, interacted with a fraction of the initial outflow and formed
dust grains.Comment: 6 pages, 4 figures, 2010, PASJ, 62, 1103--1108, in pres
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