1,440 research outputs found
Optimal Supervisory Policies and Depositor-Preferences Laws.
When supervisors have imperfect information about the soundness of banks, they may be unaware of insolvency problems that develop in the interval between on-site examinations. Supervising banks more often will alleviate this problem but will increase the costs of supervision. This paper analyzes the trade-offs that supervisors face between the cost of supervision and their need to monitor banks effectively. We first characterize the optimal supervisory policy, in terms of the time between examinations and the closure rule at examinations, and compare it with the policy of an independent supervisor. We then show that making this supervisor accountable for deposit insurance losses in general reduces the excessive forbearance of the independent supervisor and may also improve on the time between examinations. Finally, we extend our analysis to the impact of depositor-preference laws on supervisors' monitoring incentives and show that these laws may lead to conflicting effects on the time between examinations and closure policy vis-a-vis the social optimum.Deposit Insurance; Depositor Preference; Supervision.
Linearized force constants method for lattice dynamics in mixed semiconductors
A simple and accurate method of calculating phonon spectra in mixed
semiconductors alloys, on the basis of preliminarily (from first principles)
relaxed atomic structure, is proposed and tested for (Zn,Be)Se and (Ga,In)As
solid solutions. The method uses an observation that the interatomic force
constants, calculated ab initio for a number of microscopic configurations in
the systems cited, show a clear linear variation of the main (diagonal) values
of the interatomic force constants with the corresponding bond length. We
formulate simple rules about how to recover the individual 3x3 subblocks of the
force constants matrix in their local (bonds-related) coordinate systems and
how to transform them into a global (crystal cell-related) coordinate system.
Test calculations done for 64-atom supercells representing different
concentrations of (Zn,Be)Se and (Ga,In)As show that the phonon frequencies and
compositions of eigenvectors are faithfully reproduced in a linearized force
constants calculation, as compared to true ab initio calculations.Comment: to appear in the proceedings of the Phonons2007 conference (Paris,
July 2007
Using routine meteorological data to derive sky conditions
International audienceSky condition is a matter of interest for public and weather predictors as part of weather analyses. In this study, we apply a method that uses total solar radiation and other meteorological data recorded by an automatic station for deriving an estimation of the sky condition. The impetus of this work is the intention of the Catalan Meteorological Service (SMC) to provide the public with real-time information about the sky condition. The methodology for deriving sky conditions from meteorological records is based on a supervised classification technique called maximum likelihood method. In this technique we first need to define features which are derived from measured variables. Second, we must decide which sky conditions are intended to be distinguished. Some analyses have led us to use four sky conditions: (a) cloudless or almost cloudless sky, (b) scattered clouds, (c) mostly cloudy ? high clouds, (d) overcast ? low clouds. An additional case, which may be treated separately, corresponds to precipitation (rain or snow). The main features for estimating sky conditions are, as expected, solar radiation and its temporal variability. The accuracy of this method of guessing sky conditions compared with human observations is around 70% when applied to four sites in Catalonia (NE Iberian Peninsula). The agreement increases if we take into account the uncertainty both in the automatic classifier and in visual observations
Etude de la variabilité d'un agent pathogène, Xanthomonas campestris pv manihotis, par l'analyse factorielle multiple
International audienc
Lattice dynamics of mixed semiconductors (Be,Zn)Se from first-principles calculations
Vibration properties of Zn(1-x)Be(x)Se, a mixed II-VI semiconductor
haracterized by a high contrast in elastic properties of its pure constituents,
ZnSe and BeSe, are simulated by first-principles calculations of electronic
structure, lattice relaxation and frozen phonons. The calculations within the
local density approximation has been done with the Siesta method, using
norm-conserving pseudopotentials and localized basis functions; the benchmark
calculations for pure endsystems were moreover done also by all-electron WIEN2k
code. An immediate motivation for the study was to analyze, at the microscopic
level, the appearance of anomalous phonon modes early detected in Raman spectra
in the intermediate region (20 to 80%) of ZnBe concentration. This was early
discussed on the basis of a percolation phenomenon, i.e., the result of the
formation of wall-to-wall --Be--Se-- chains throughout the crystal. The
presence of such chains was explicitly allowed in our simulation and indeed
brought about a softening and splitting off of particular modes, in accordance
with experimental observation, due to a relative elongation of Be--Se bonds
along the chain as compared to those involving isolated Be atoms. The variation
of force constants with interatomic distances shows common trends in relative
independence on the short-range order.Comment: 11 pages, 10 figures, to be published in Phys. Rev.
Quadratic optimal functional quantization of stochastic processes and numerical applications
In this paper, we present an overview of the recent developments of
functional quantization of stochastic processes, with an emphasis on the
quadratic case. Functional quantization is a way to approximate a process,
viewed as a Hilbert-valued random variable, using a nearest neighbour
projection on a finite codebook. A special emphasis is made on the
computational aspects and the numerical applications, in particular the pricing
of some path-dependent European options.Comment: 41 page
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