The validity of the orthographic depth hypothesis (ODH) was examined in Hebrew by employing pointed (shallow) and unpointed (deep) print. Experiments 1 and 2 revealed larger frequency effects and larger semantic priming effects in naming with unpointed print than with pointed print. In Experiments 3 and 4, subjects were presented with Hebrew consonantal strings that were followed by vowel marks appearing at stimulus onset asynchronies ranging from 0 ms (simultaneous presentation) to 300 ms from the onset of consonant presentation. Subjects were inclined to wait for the vowel marks to appear even though the words could be named unequivocally using lexical phonology. These results suggested that prelexical phonology was the default strategy for readers in shallow orthographies, providing strong support for the ODH.
Pradeep Dubey and Abraham Neyman. 1994. “An Axiomatic Approach to the Equivalence Phenomenon.” In Game-Theoretic Methods in General Equilibrium Analysis, edited by Jean-Francois Mertens and Sylvain Sorin, 77: Pp. 137--143. Dordrecht / Boston / London: Kluwer Academic Publishers.
Four axioms are placed on a correspondence from smooth, non-atomic economies to their allocations. We show that the axioms categorically determine the (coincident) competitive-core-value correspondence. Thus any solution is equivalent to the above three if, and only if, it satisfies the axioms. In this sense our result is tantamount to an "equivalence principle." At the same time, our result implies that the three solutions themselves are determined by the axioms and so serves as an axiomatic characterization of the well-known competitive (or core, or value) correspondence.
Abraham Neyman. 1994. “Values of Games with a Continuum of Players.” In Game-Theoretic Methods in General Equilibrium Analysis, edited by Jean-Francois Mertens and Sylvain Sorin, Pp. 67--79. Amsterdam: Kluwer Academic Publishers.
A general method for studying transition state spectroscopy and dynamics in hydrogen atom transfer reactions is presented. This approach is based on the time-dependent self-consistent field (TDSCF) approximation and is applied to a study of the CIHCl- photodetachment experiments of Metz et al. [Metz et al., J. Chem. Phys. 88, 1463 (1988)]. Comparison of results of exact time-dependent and TDSCF calculations are made for collinear and three-dimensional (J=0) approximations for the quantum dynamics. When ClHCl is constrained to be collinear, the TDSCF calculation overcorrelates the motions in the R atom displacement and ClCl extension coordinates. This results in relatively poor agreement with the exact result for many properties of the wavefunction. in contrast, when the system is propagated in the three vibrational coordinates of the system, the transition state dynamics are effectively overmuch more rapidly. Consequently, the TDSCF approximation yields results of very good quantitative accuracy over the time required for most of the wave function to decay off of the transition state. Comparison is also made between the wave function that results from the exact propagation and from TDSCF when the wave function in the ClCl stretch coordinate is approximated by a Gaussian wave packet. Here the magnitude of the overlap between the two TDSCF wave functions in the H atom coordinates, for quantum and semiclassical propagations of the wave function in the ClCl distance Coordinate, is greater than 0.98 over the time of the propagations. These TDSCF calculations are repeated fbi a wave function that is approximated by a product of a two-dimensional wave function in the hydrogen atom coordinates and a one-dimensional wave function in the ClCl extension coordinate and even better quantitative agreement with the exact propagation is achieved. The success of this method for studying ClHCl gives us confidence that TDSCF will provide a general powerful tool for studies of hydrogen and proton transfer reactions in large systems.
The authors analyze a duopoly model where firms first choose locations on a line segment and then choose quantities in the second stage. Pure strategy quantity equilibria fail to exist for locations close together. For low transport costs, near agglomeration occurs and the firms choose locations where pure strategy quantity equilibria exist. As transport costs rise, firms become less direct competitors as they move away from the center of the market. Coauthors are James F. Klein, Eytan Sheshinski, and Steven M. Slutsky. We analyse a duopoly model where firms first choose locations on a line segment and then choose quantities in the second stage. Pure strategy quantity equilibria fail to exist for locations close together. For low transport costs, near agglomeration occurs and the firms choose locations where pure strategy quantity equilibria exist. As transport costs rise, firms become less direct competitors as they move away from the centre of the market. Coauthors are James F. Klei
We analyse a duopoly model where firms first choose locations on a line seqment and then choose quantities in the second stage. Pure strategy quantity equilibria fail to exist for locations close together. For low transport costs, near agglomeration occurs and the firms choose locations where pure strategy quantity equilibria exist. As transport costs rise, firms become less direct competitors as they move away from the centre of the market. /// La concurrence par les quantités dans un modèle spatial. Les auteurs analysent un modèle de duopole où les firmes choisissent d'abord leur localisation le long d'un segment linéaire et puis, dans un second temps, les quantités qu'elles désirent produire. On montre qu'il n'est pas possible d'établir l'existence d'équilibres pour de pures stratégies de quantités quand il s'agit de localisations trop rapprochées. Quand les coûts de transport sont faibles, il y a presqu' agglomération et les firmes choisissent des localisations telles que des équi
The structure and stability of clusters of a boron atom with one to eight H-2 molecules is investigated. For the simplest BH2 clusters, the lowest ab initio adiabatic potentials for o-H-2 and p-H-2 interacting with a boron atom are used. For the larger clusters (n=2-8), the p-Hz is treated as a sphere, and the total potential is taken to be the sum of pairwise additive B-H-2 and H-2-H-2 interactions which include, in the former case, an anisotropy due to the orientation of the unpaired B 2p electron. This electronic interaction is considerably more attractive when H-2 approaches the B atom in a plane perpendicular to the orientation of the 2p orbital. The local and global minima on these potential surfaces were located and diffusion quantum Monte Carlo simulations were used to determine the energies and properties of the ground state wave functions for these B-(H-2)(n) clusters. For the B(H-2) cluster, a comparison is made with the results of variational calculations.
The formation of HCl molecules in collisions of H atoms with Cl(Ar)12 Clusters is studied by classical trajectory calculations as a function of the cluster temperature. At sufficiently low impact energy (E = 10 kJ/mol) a pronounced threshold effect with temperature is observed: In the solidlike regime of the cluster (T less-than-or-equal-to 40 K) there is strong screening of the Cl atom by the icosahedral Ar solvation shell preventing H+Cl association. In the liquidlike phase of the aggregate (T almost-equal-to 45 K) a sharp onset of reactivity is found with a reactive cross section of 11.4 x 10(-20) m2.
Transitions induced by lattice motions between different electronic states of an F(P-2) atom in solid Kr are studied by molecular dynamics simulations. Hopping between potential surfaces is used in modelling the electronic transitions. Calculations for an initially prepared p-orbital orientation, with the lattice at T=25 K, show (1) the decay of orbital orientation at short times (t less than or equal to 40 fs) is well described by a model of random, uncorrelated surface hopping events; (2) the probability of orbital reorientation events is highly correlated with lattice cage distortions of a particular symmetry type, and weakly correlated with cage radial breathing motions; (3) the rate of electronic transitions is nearly constant in time at thermal conditions.
CdxA is a homeobox gene of the caudal type that was previously shown to be expressed in the endoderm-derived gut epithelium during early embryogenesis. Expression of the CDXA protein was studied during intestine morphogenesis from stage 11 (13 somites) to adulthood in the chicken. The CDXA protein can be detected during all stages of gut closure, from stage 11 to 5 days of incubation, and is mainly localized to the intestinal portals, the region where the splanchnopleure is undergoing closure. In this region, which represents the transition between the open and closed gut, the CDXA protein is restricted to the endoderm-derived epithelium. At about day 5 of incubation, the process of formation of the previllous ridges begins, which marks the beginning of the morphogenesis of the villi. From this stage to day 11 expression of CDXA is localized to the epithelial lining of the intestine. In parallel, a gradual increase in CDXA protein expression begins in the mesenchyme that is close in proximity to the CDXA-positive endoderm. Maximal CDXA levels in the mesenchyme are observed at day 9 of incubation. During days 10 and 11 CDXA levels in the mesenchyme remain constant, and by day 12 CDXA becomes undetectable in these cells and the epithelium again becomes the main site of expression. From day 12 of incubation until adulthood the CDXA protein is present in the intestinal epithelium. Until day 18 of incubation expression can be detected along the whole length of the villus with a stronger signal at the tip. With hatching the distribution along the villi changes so that the main site of CDXA protein expression is at the base of the villi and in the crypts. The transient expression of CDXA in the mesenchyme between days 5 and 11 may be related to the interactions taking place between the mesenchyme and the epithelium that ultimately result in the axial specification of the alimentary canal and the differentiation of its various epithelia. The main CDXA spatial distribution during morphogenesis suggests a tight linkage to the formation and differentiation of the intestinal epithelium itself. CDXA appears to play a role in the morphogenetic events leading to closure of the alimentary canal. During previllous ridge formation the CDXA protein is transiently expressed in the mesenchymal cells thought to provide instructive interactions for the regionalization and differentiation of the gut epithelium.(ABSTRACT TRUNCATED AT 400 WORDS)
A new mechanism for inducing bulk asymmetry and second order optical nonlinearity in polymer-dye systems is described. An anisotropic distribution of charges is established inside the medium resulting from the application of high voltage via an asymmetric electrode structure. The nonlinearity induced via this mechanism is perpendicular to the externally applied electric field. It is proven that the nonlinearity induced by charge injection cannot arise from dipolar alignment of molecules, but rather results from the nonlinearity of charged dye dimers in a bulk charge gradient.
A systematic study of the reaction of 1-chloromethyl-4-(2-trichlorosilylethyl)-benzene (coupling agent) with the surface SiOH groups of glass for times from 15 min to 48 h, followed by stilbazole chromophore precursor deposition/quaternization, is reported. Second harmonic generation characteristics of these thin film materials indicate that a 15 min coupling agent reaction attains approximately 65% of full surface coverage (based on χzzz(2)) of benzylic chloride moieties, but that 24 h is the optimal time for maximum coverage. The surface-anchored chromophoric chloride salts in such materials undergo facile ion exchange with iodide, p-aminobenzenesulphonate, and ethyl orange, leading to enhancements in χzzz(2) of up to 50%.
Self-assembled monolayers of ω-mercaptocarboxylic acids, HS(CH2)nCO2H (n = 1, 2, 5, 10), on mercury film (MF) and gold electrodes have been used for the very sensitive and selective anal. of ultralow levels of cadmium(II). The authors find that shorter ω-mercaptocarboxylic acids provide superior sensitivity. Other parameters that govern the sensitivity and selectivity of this system have been examd. in detail. Optimizing these factors resulted in a detection limit of 4 × 10-12 M (0.45 ppt). The method has been verified by detg. cadmium in std. solns. and it has been successfully applied to the anal. of cadmium in seawater. [on SciFinder(R)]
We study the two-dimensional (2-D) structural and thermodynamic changes in smectic-A/lamellar phases of self-assembling surfactant systems, in which the rim associated with a bilayer edge has a preferred curvature. This property was not considered in previous studies of 2-D aggregation, where an infinite bilayer emerges already at very low concentrations. A lattice Hamiltonian is used to describe the bending energy of the rim: An occupied lattice site corresponds to a minimum, disklike, micelle, and a bending energy penalty is associated with corners and straight edges depending on the value of the spontaneous curvature. When the spontaneous radius of curvature of the rim is small and the bending modulus is large, we find that the `'condensation'' transition-i.e., the `'collapse'' of the finite aggregates into a continuous bilayer-is postponed to high concentrations. At low concentrations the bending energy leads to an effective repulsive interaction between the aggregates, which in turn can result in ordered (modulated) structures for not too large ratios of thermal energy to bending energy (which is the expected situation in most systems of interest). Our model should be applicable to the systems of decylammonium chloride and cesium perflourooctanoate studied by Boden and co-workers (NMR and conductivity measurements) and Zasadzinski and co-workers (freeze fracture), where monodisperse micellar disks are observed to layer in stacked planes. In the latter system a 2-D order of disk-shaped aggregates appears within the smectic-A layers, which is also consistent with our theory. Experimental studies of the structural evolution under further condensation of the system are not yet available.
The role of solvent effects in association reactions is studied in atom-cluster collisions. Classical trajectory studies of the systems H+Cl(Ar)(n) (n = 1,12) are used to investigate the influence of size, structure, and internal energy of the `'microsolvation'' on the H+Cl association reaction. The following effects of solvating the chlorine in an Ar, cluster are found. (1) In the H+ClAr system there is a large `'third body'' effect. The single solvent atom stabilizes the newly formed HCl molecule by removing some of its excess energy. The cross section found at low energies is a substantial fraction of the gas-kinetic cross section. The molecule is produced in highly excited vibrational-rotational states. (2) Some production of long-lived HCl...Ar complexes, with lifetimes of 1 ps and larger, is found for the H+ClAr collisions. Weak coupling stemming from the geometry of the cluster is the cause for long life times. These resonance states decay into HCl+Ar. (3) At low collision energy (E = 10 kJ/mol) for H+Cl(Ar)(12), the H+Cl association shows a sharp threshold effect with cluster temperature. For temperatures T greater than or equal to 45 K the cluster is liquidlike, and the reaction probability is high. For T less than or equal to 40 K the cluster is solidlike, and there is no reactivity. This suggests the potential use of reactions as a signature for the meltinglike transition in clusters. (4) At high collision energies (E = 100 kJ/mol) H atoms can penetrate also the solidlike Cl(Ar)(12) cluster. At this energy, the solid-liquid phase change is found not to increase the reaction probability.
Linear Measures, the Gini Index and the Income-Equality Tradeoff
with I. Gilboa
This paper provides an axiomatization of linear inequality measures representing binary relations on the subspace of income profiles having identical total income. Interpreting the binary relation as a policymaker's preference, we extend the axioms to the whole space and find that they characterize linear social evaluation functions. The axiomatization seems to suggest that a policymaker who has a linear measure of inequality on a subspace should have a linear evaluation on the whole space. An extension of the preferences reflected in the Gini index to the whole space is represented by a linear combination of total income and the Gini index. Journal of Economic Literature Classification numbers: D30, D31, D60, D63, D81
