1,876 research outputs found
Determinants of Japanese aid allocation: an econometric analysis
Economic self-interest and politico-strategic and humanitarian concerns motivate donor countries in their development assistance policies. A large amount of literature has pointed out that either economic self-interest or political self-interest played a pivotal role in the early phases of foreign aid programmes of many donors. Currently, almost all donors include humanitarian assistance in explaining their aid motives. We investigate how Japanese aid allocation policies have changed over the time and also identify empirically the major determinants of aid allocation. It is found from the empirical evidence that Japan takes national interest as well as recipient country needs into account in allocating their aid. The nature of Asian biasness in Japanese aid may continue given the high emphasis on national economic and security interests. Given the historical trend one can conclude that the same determinant factors may keep on playing vital roles in aid allocation decision-making at least for some years to come even though there has been an increased call for more assistance to poor region
Gravitational Lensing as a Probe of Quintessence
A large number of cosmological studies now suggest that roughly two-thirds of
the critical energy density of the Universe exists in a component with negative
pressure. If the equation of state of such an energy component varies with
time, it should in principle be possible to identify such a variation using
cosmological probes over a wide range in redshift. Proper detection of any time
variation, however, requires cosmological probes beyond the currently studied
range in redshift of 0.1 to 1. We extend our analysis to gravitational
lensing statistics at high redshift and suggest that a reliable sample of
lensed sources, out to a redshift of 5, can be used to constrain the
variation of the equation of state, provided that both the redshift
distribution of lensed sources and the selection function involved with the
lensed source discovery process are known. An exciting opportunity to catalog
an adequate sample of lensed sources (quasars) to probe quintessence is now
available with the ongoing Sloan Digital Sky Survey. Writing , we study the expected accuracy to which the equation of state
today and its rate of change can simultaneously be
constrained. Such a determination can rule out some missing-energy candidates,
such as classes of quintessence models or a cosmological constant.Comment: Accepted for publication in ApJ Letters (4 pages, including 4
figures
Sunyaev-Zeldovich Fluctuations from the First Stars?
WMAP's detection of high electron-scattering optical depth suggests
substantial star formation at high redshift z~17 +/- 5. On the other hand, the
recovered sigma_8 ~ 0.84 +/-0.04 disfavors a cluster Sunyaev-Zeldovich (SZ)
origin for the observed small-scale-CMB fluctuation excess, which generally
requires sigma_8 ~ 1.1. Here we consider the effects of high-redshift star
formation on the CMB. We derive a fairly model-independent relation between the
electron scattering optical depth and the number of ionizing photons emitted
per baryon, and use this to calibrate the amount of high-redshift supernova
activity. The resulting supernova remnants Compton cool against the CMB
creating a Compton-y distortion y ~ few x 10^-6, within observational bounds.
However they also create small-scale SZ fluctuations, which could be comparable
with SZ fluctuations from unresolved galaxy clusters. This raises the exciting
possibility that we have already detected signatures of the first stars not
just once, but twice, in the CMB.Comment: Fixed typo in Fig. 1 caption; few other minor change
Distances and Cosmology From Galaxy Cluster CMB Data
The measurement of angular diameter distance to galaxy clusters, through
combined Sunyaev-Zel'dovich (SZ) effect data with X-ray emission observations,
is now a well-known probe of cosmology. Using a combination of SZ data and a
map of the lensed CMB anisotropies by the galaxy cluster potential, we propose
an alternative geometric technique to measure distance information primarily
through cluster related multi-frequency CMB measurements. We discuss necessary
requirements to implement this measurement, potential errors including
systematic biases, and the extent to which cosmological parameters can be
extracted. While individual cluster distances are not likely to be precise,
with upcoming subarcminute resolution wide-area CMB observations, useful
information on certain cosmological parameters, such as the equation of state
of dark energy, can be obtained from a large sample of galaxy clusters.Comment: 4 pages, 2 figure
An indirect limit on the amplitude of primordial Gravitational Wave Background from CMB-Galaxy Cross Correlation
While large scale cosmic microwave background (CMB) anisotropies involve a
combination of the scalar and tensor fluctuations, the scalar amplitude can be
independently determined through the CMB-galaxy cross-correlation. Using
recently measured cross-correlation amplitudes, arising from the
cross-correlation between galaxies and the Integrated Sachs Wolfe effect in CMB
anisotropies, we obtain a constraint r < 0.5 at 68% confidence level on the
tensor-to-scalar fluctuation amplitude ratio. The data also allow us to exclude
gravity waves at a level of a few percent, relative to the density field, in a
low - Lambda dominated universe(Omega_Lambda~0.5). In future, joining
cross-correlation ISW measurements, which captures cosmological parameter
information, with independent determinations of the matter density and CMB
anisotropy power spectrum, may constrain the tensor-to-scalar ratio to a level
above 0.05. This value is the ultimate limit on tensor-to-scalar ratio from
temperature anisotropy maps when all other cosmological parameters except for
the tensor amplitude are known and the combination with CMB-galaxy correlation
allows this limit to be reached easily by accounting for degeneracies in
certain cosmological parameters.Comment: 5 Pages, 1 Figure, revised discussion on cosmic variance limits on
the tensor-to-scalar ratio from CMB, matches PRD accepted versio
Parameterization of Dark-Energy Properties: a Principal-Component Approach
Considerable work has been devoted to the question of how to best
parameterize the properties of dark energy, in particular its equation of state
w. We argue that, in the absence of a compelling model for dark energy, the
parameterizations of functions about which we have no prior knowledge, such as
w(z), should be determined by the data rather than by our ingrained beliefs or
familiar series expansions. We find the complete basis of orthonormal
eigenfunctions in which the principal components (weights of w(z)) that are
determined most accurately are separated from those determined most poorly.
Furthermore, we show that keeping a few of the best-measured modes can be an
effective way of obtaining information about w(z).Comment: Unfeasibility of a truly model-independent reconstruction of w at z>1
illustrated. f(z) left out, and w(z) discussed in more detail. Matches the
PRL versio
Accounting Education in Australia and Japan: A Comparative Examination
In recent years there has been a great concern among governments, professional bodies and educators for changes in accounting education. It seems useful for planners of such changes to consider the methods of training accountants in different countries as one country can learn from the experiences of another. In the existing literature, however, there is a dearth of comparative studies on this area of education in different countries. This paper presents an analysis of accounting education in Australia and Japan highlighting the major differences in the two countries. The analysis reveals that accounting education in Australia places emphasis on financial accounting while the emphasis is on cost and management accounting in Japan. It also shows that being firm-specific through comprehensive in-house training the Japanese system is in a better position to produce accountants capable of adapting accounting systems to the different work situations which result from technological changes and automation
The Born and Lens-Lens Corrections to Weak Gravitational Lensing Angular Power Spectra
We revisit the estimation of higher order corrections to the angular power
spectra of weak gravitational lensing. Extending a previous calculation of
Cooray and Hu, we find two additional terms to the fourth order in potential
perturbations of large-scale structure corresponding to corrections associated
with the Born approximation and the neglect of line-of-sight coupling of two
foreground lenses in the standard first order result. These terms alter the
convergence (), the lensing shear E-mode (),
and their cross-correlation () power spectra on large angular
scales, but leave the power spectra of the lensing shear B-mode ()
and rotational () component unchanged as compared to previous
estimates. The new terms complete the calculation of corrections to weak
lensing angular power spectra associated with both the Born approximation and
the lens-lens coupling to an order in which the contributions are most
significant. Taking these features together, we find that these corrections are
unimportant for any weak lensing survey, including for a full sky survey
limited by cosmic variance.Comment: Added references, minor changes to text. 9 pages, 2 figure
Modifications to the Cosmic 21-cm Background Frequency Spectrum by Scattering via electrons in Galaxy Clusters
The cosmic 21-cm background frequency spectrum related to the spin-flip
transition of neutral Hydrogen present during and before the era of
reionization is rich in features associated with physical processes that govern
transitions between the two spin states. The intervening electrons in
foreground galaxy clusters inversely Compton scatter the 21-cm background
spectrum and modify it just as the cosmic microwave background (CMB) spectrum
is modified by inverse-Compton scattering. Towards typical galaxy clusters at
low redshifts, the resulting modification is a few tenths milli-Kelvin
correction to the few tens milli-Kelvin temperature of 21-cm signal relative to
that of the cosmic microwave background black body spectrum. The modifications
are mostly associated with sharp changes in the cosmic 21-cm background
spectrum such as due to the onset of a Lyman- radiation field or
heating of neutral gas. Though low frequency radio interferometers that are now
planned for 21-cm anisotropy measurements are insensitive to the mean 21-cm
spectrum, differential observations of galaxy clusters with these
interferometers can be utilized to indirectly establish global features in the
21-cm frequency spectrum. We discuss the feasibility to detect the spectrum
modified by clusters and find that for upcoming interferometers, while a
detection towards an individual cluster is challenging, one can average signals
over a number of clusters, selected based on the strength of the
Sunyave-Zel'dovich effect at high radio frequencies involving CMB scattering
alone, to establish the mean 21-cm spectrum.Comment: 6 pages, 3 figures, PRD in press; expanded and title changed from v1.
Final version in pres
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