11,817 research outputs found
The basic analytics of access to financial services
Access to financial services, or rather the lack thereof, is often indiscriminately decried as a problem in many developing countries. The authors argue that the"problem of access"should rather be analyzed by identifying different demand and supply constraints. They use the concept of an access possibilities frontier, drawn for a given set of state variables, to distinguish between cases where a financial system settles below the constrained optimum, cases where this constrained optimum is too low, and-in credit services-cases where the observed outcome is excessively high. They distinguish between payment and savings services and fixed intermediation costs, on the one hand, and lending services and different sources of credit risk, on the other hand. The authors include both supply and demand side frictions that can lead to lower access. The analysis helps identify bankable and banked population, the binding constraint to close the gap between the two, and policies to prudently expand the bankable population. This new conceptual framework can inform the debate on adequate policies to expand access to financial services and can serve as the basis for an informed measurement of access.Banks&Banking Reform,Economic Theory&Research,Markets and Market Access,Access to Markets,Financial Intermediation
Experimental Lagrangian Acceleration Probability Density Function Measurement
We report experimental results on the acceleration component probability
distribution function at to probabilities of less than
. This is an improvement of more than an order of magnitude over past
measurements and allows us to conclude that the fourth moment converges and the
flatness is approximately 55. We compare our probability distribution to those
predicted by several models inspired by non-extensive statistical mechanics. We
also look at acceleration component probability distributions conditioned on a
velocity component for conditioning velocities as high as 3 times the standard
deviation and find them to be highly non-Gaussian.Comment: submitted for the special issue of Physica D: "Anomalous
Distributions" 11 pages, 6 figures revised version: light modifications of
the figures and the tex
Unilateral acute idiopathic maculopathy: angiography, optical coherence tomography and microperimetry findings
Unilateral acute idiopathic maculopathy (UAIM) is an uncommon inflammatory disease of the retinal pigment epithelium (RPE) that affects young adults. The variability of clinical features of UAIM makes the diagnosis cumbersome. We report on a 25-year-old man with sudden loss of visual acuity (VA) and a central scotoma in his right eye. Fluorescein angiography localised the lesion in the RPE. Microperimetry revealed a central scotoma extending beyond the lesion margins with complete recovery of retinal sensitivity over weeks. Optical coherence tomography at presentation showed a thickened RPE. We are unaware of previous reports of UAIM studied by microperimetry and could find no reference to it in a computerised search using MEDLINE
The energy of waves in the photosphere and lower chromosphere: III. Inversion setup for Ca II H spectra in local thermal equilibrium
The Ca II H line is one of the strongest lines in the solar spectrum and
provides continuous information on the solar atmosphere from the photosphere to
the lower chromosphere. We describe an inversion approach that reproduces
observed Ca II H spectra assuming LTE. We developed an inversion strategy based
on the SIR code. The approach uses a two-step procedure with an archive of
pre-calculated spectra to fit the line core and a subsequent iterative
modification to improve the fit in the line wing. Simultaneous spectra in the
630nm range can optionally be used to fix the continuum temperature. The method
retrieves 1D temperature stratifications neglecting lateral radiative
transport. LOS velocities are included by an empirical approach. An archive of
about 300.000 pre-calculated spectra is more than sufficient to reproduce the
line core of observed Ca II H spectra both in quiet Sun and in active regions.
The final thermodynamical stratifications match observed and best-fit spectra
to a level of about 0.5 (1) % of Ic in the line wing (core). Inversion schemes
based on pre-calculated spectra allow one a reliable and relatively fast
retrieval of solar properties from observed chromospheric spectra. The approach
can be easily extended to an 1D NLTE case by a simple exchange of the
pre-calculated archive spectra.Comment: 15 pages, 15 figures, accepted for publication in A&A. The animation
will only be provided in the A&A online sectio
The energy of waves in the photosphere and lower chromosphere: IV. Inversion results of Ca II H spectra
Most static 1D atmosphere models in the quiet Sun predict a rise of the gas
temperature at chromospheric layers, but numerical simulations only yield an
increase in the brightness temperature. We investigate the thermal structure in
the solar chromosphere as derived from an LTE inversion of Ca II H spectra in
QS and active regions. We investigate the temperature stratifications on
differences between magnetic and field-free regions in the QS, and between QS
and ARs. We determine the energy content of individual calcium bright grains
(BGs). The rms temperature fluctuations are below 100 K in the photosphere and
200-300 K in the chromosphere. The average temperature stratification in the QS
does not exhibit a clear chromospheric temperature rise, opposite to the AR
case. We find an energy content of about 7*10E18 J for BGs that repeat with a
cadence of about 160 secs. The precursors of BGs have a vertical extent of
about 200 km and a horizontal extent of about 1 Mm. The comparison of observed
with synthetic NLTE profiles confirms that the solar chromosphere in the QS
oscillates between an atmosphere in radiative equilibrium and one with a
moderate chromospheric temperature rise. Two-dimensional x-z temperature maps
exhibit nearly horizontal canopy-like structures with a few Mm extent around
photospheric magnetic field concentrations at a height of about 600 km. The
large difference between QS regions and ARs, and the better match of AR and
non-LTE reference spectra suggest that magnetic heating processes are more
important than commonly assumed. The temperature fluctuations in QS derived by
the LTE inversion do not suffice on average to maintain a stationary
chromospheric temperature rise. The spatially and vertically resolved
information on the temperature structure allows one to investigate in detail
the topology and evolution of the thermal structure in the lower solar
atmosphere.Comment: 16 pages, 16 figures + 1 page Appendix, accepted by A&
Fusion excitation function revisited
We report on a comprehensive systematics of fusion-evaporation and/or
fusion-fission cross sections for a very large variety of systems over an
energy range 4-155 A.MeV. Scaled by the reaction cross sections, fusion cross
sections do not show a universal behavior valid for all systems although a high
degree of correlation is present when data are ordered by the system mass
asymmetry.For the rather light and close to mass-symmetric systems the main
characteristics of the complete and incomplete fusion excitation functions can
be precisely determined. Despite an evident lack of data above 15A.MeV for all
heavy systems the available data suggests that geometrical effects could
explain the persistence of incomplete fusion at incident energies as high as
155A.MeV.Comment: 8 pages, 5 figures, contribution to the NN2012 Proceeding
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