590 research outputs found
On Some Myths about Sequenced Common-valued Auctions
Equilibria are constructed for classes of game models of sequenced second-price auctions having identical common-valued objects. In some of these the equilibrium price falls on average, and in others the seller loses on average by committing to announce publicly something that he knows. Both of these possibilities are surprisesPublicad
A generalized least squares estimation method for VARMA models. (Revised edition).
In this paper a new generalized least squares procedure for estimating VARMA models is proposed. This method differs from existing ones in explicitly considering the stochastic structure of the approximation error that arises when lagged innovations are replaced with lagged residuals obtained from a long VAR. Simulation results indicate that this method improves the accuracy of estimates with small and moderate sample sizes, and increases the frequency of identifying small nonzero parameters, with respect to both Double Regression and exact maximum likelihood estimation procedures
On the Unification of Process Semantics: Logical Semantics
We continue with the task of obtaining a unifying view of process semantics
by considering in this case the logical characterization of the semantics. We
start by considering the classic linear time-branching time spectrum developed
by R.J. van Glabbeek. He provided a logical characterization of most of the
semantics in his spectrum but, without following a unique pattern. In this
paper, we present a uniform logical characterization of all the semantics in
the enlarged spectrum. The common structure of the formulas that constitute all
the corresponding logics gives us a much clearer picture of the spectrum,
clarifying the relations between the different semantics, and allows us to
develop generic proofs of some general properties of the semantics.Comment: In Proceedings SOS 2011, arXiv:1108.279
(5RS,10SR,15RS)-Trimethyltruxene1
The title molecule, C30H24, was prepared as a possible precursor to buckminsterfullerene cages. The two enantiomers adopt the anti configuration, with one S/R and two R/S methyl groups, one anti to the other two. The truxene framework is slightly non-planar: with respect to the central six-ring mean plane, the three methyl C atoms are 1.377 (3), −1.475 (3) and 1.515 (3) Å distant, whereas the respective proximate peripheral six-ring mean planes make dihedral angles of 6.27 (6), 3.45 (7) and −7.37 (7)°
(5SR,10SR,15SR)-Trimethyl 5H,10H,15H-diindeno[1,2-a:1′,2′-c]fluorene-5,10,15-tricarboxylate 0.167-hydrate
The title compound, C33H24O6·0.17H2O, which is commonly known as (SR,SR,SR)-trimethyl 1,10,19-truxentricarboxylate, crystallizes as a hydrate with the water molecule encapsulated between three ester groups by O—H⋯O hydrogen bonding to two of them. The water molecule site is not fully occupied in the crystal studied, with a refined site occupancy of 0.167 (5). The 27-atom ring system is approximately planar, with a maximum deviation of 0.148 (1) Å, and the three ester substituents are all on the same side of this plane
Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region
International audienceWe report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company) covering the range from 300?1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain) of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Ångström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behaviour of these estimations in each area of study
Self-similar Radiation from Numerical Rosenau-Hyman Compactons
The numerical simulation of compactons, solitary waves with compact support,
is characterized by the presence of spurious phenomena, as numerically-induced
radiation, which is illustrated here using four numerical methods applied to
the Rosenau-Hyman K(p,p) equation. Both forward and backward radiations are
emitted from the compacton presenting a self-similar shape which has been
illustrated graphically by the proper scaling. A grid refinement study shows
that the amplitude of the radiations decreases as the grid size does,
confirming its numerical origin. The front velocity and the amplitude of both
radiations have been studied as a function of both the compacton and the
numerical parameters. The amplitude of the radiations decreases exponentially
in time, being characterized by a nearly constant scaling exponent. An ansatz
for both the backward and forward radiations corresponding to a self-similar
function characterized by the scaling exponent is suggested by the present
numerical results.Comment: To be published in Journal of Computational Physic
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