Let γ : [0, 1] → [0, 1] be a continuous curve such that γ(0) = (0, 0), γ(1) = (1, 1), and γ(t) ∈ (0, 1) for all t ∈ (0, 1). We prove that, for each n ∈ N, there exists a sequence of points Ai, 0 ≤ i ≤ n + 1, on γ such that A0 = (0, 0), An+1 = (1, 1), and the sequences π1( −−−−→ AiAi+1) and π2( −−−−→ AiAi+1), 0 ≤ i ≤ n, are positive and the same up to order, where π1, π2 are projections on the a...

We use quantile regressions to estimate whether the relation between school quality and performance on standardized tests differs at different points in the conditional distribution of ‘test score gains’. Previous work has focused only on average school quality effects.  1998 Elsevier Science S.A.

A well known principle says that the number of lattice points in a bounded subsets S of Euclidean space is about the ratio of the volume and the lattice determinant, subject to some relatively mild conditions on S. In the literature one finds two different types of such conditions; one asserts the Lipschitz parameterizability of the boundary ∂S, and the other one is based on intersection proper...

In this paper we study three aspects of (P(M)/ ∼), the set of Murray-von Neumann equivalence classes of projections in a von Neumann algebra M. First we determine the topological structure that (P(M)/ ∼) inherits from the operator topologies on M. Then we show that there is a version of the center-valued trace which extends the dimension function, even whenM is not σ-finite. Finally we prove th...

Recently, the interest in semifields has increased due to the discovery of several new families and progress in the classification problem. Commutative semifields play an important role since they are equivalent to certain planar functions (in the case of odd characteristic) and to modified planar functions in even characteristic. Similarly, commutative semifields are equivalent to relative dif...

In the scattering theory framework, we point out a connection between the spectrum of the scattering matrix of two operators and the spectrum of the difference of spectral projections of these operators.

We examine investment behavior when firms face costs in the access to external funds. We find that despite the existence of liquidity constraints, standard investment regressions predict that cash flow is an important determinant of investment only if one ignores q. Conversely, we also obtain significant cash flow effects even in the absence of financial frictions. These findings provide suppor...

The factors determining the layer-specific termination of hippocampal afferents are not known. Previous studies have suggested that the laminated termination of afferent fiber systems is caused by their sequential ingrowth during development. Here we have tested this temporal hypothesis of fiber segregation by an in vitro confrontation system in which the sequential arrival of entorhinal and co...

Transposed-letter effects (e.g., jugde activates judge) pose serious models for models of visual-word recognition that use position-specific coding schemes. However, even though the evidence of transposed-letter effects with nonword stimuli is strong, the evidence for word stimuli is scarce and inconclusive. The present experiment examined the effect of neighborhood frequency during normal sile...

Some standard formulas are collected on curvature in Riemannian geometry, using coordinates. (There are, as far as I know, no new results). Many examples are given, in particular for manifolds with constant curvature, including many well-known map projections of the sphere and several well-known representations of hyperbolic space, but also some lesser known.