bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Markov chain identity and monotonicity of the diffusion constants for a random walk in a heterogeneous environment
Authors: Roerdink J. B. T. M. 
Published: November 2008

AbstractWe consider a 2-dimensional square lattice which is partitioned into a periodic array of rectangular cells, on which a nearest neighbour random walk with symmetric increments is defined whose transition probabilities only depend on the relative position within a cell. On the basis of a determinantal identity proved in this paper, we obtain a result for finite Markov chains which shows that the diffusion constants for the random walk are monotonic functions of the individual transition probabilities. We point out the similarity of this monotonicity property to Rayleigh's Monotonicity Law for electric networks or, equivalently, reversible random walks.
Periodic orbits and fixed points of a C1 orientation-preserving embedding of D2
Authors: Gambaudo J. M. 
Published: November 2008

AbstractWe prove that any periodic orbit O of a C1 orientation-preserving embedding f of the 2-disc D2 is linked with a fixed point P in the sense that the corresponding periodic orbits {Φt(O)}t ≥ 0 and {Φt(P)}t ≥ 0 of any torus flow Φt suspending f are linked as knots in S3.
Characteristic classes of Galois representations
Authors: Kozlowski A. 
Published: November 2008

Let K be a field with char if K≠2 and let Ks denote the separable closure of K and GK the Galois group of the extension Ks/K. If K⊂L is a finite extension and ρ:GL↦Or(R) a (continuous) real representation of GL we have a map ρ:BGL→BO which is used to define Stiefel–Whitney classes wi(ρ) = ρ*(wi). In general if f is any element of H*(BO; ℤ/2) we denote by f(ρ) the characteristic class ρ*(f). Now letbe a genus (see e.g. [9]), for example the total Stiefel–Whitney class w = 1+w1+w2 + … Let K⊂L and ρ be as above and let denote the multiplicative transfer (see e.g. [3, 5, 2, 14, 15]). Our principal result is a generalization of theorem 1 of [3]
On the asymptotic normality of self-normalized sums
Authors: Griffin Philip S. , Mason David M. 
Published: November 2008

AbstractLet X1, …, Xn be a sequence of non-degenerate, symmetric, independent identically distributed random variables, and let Sn(rn) denote their sum when the rn largest in modulus have been removed. We obtain necessary and sufficient conditions for asymptotic normality of the studentized version of Sn(rn), and compare this to the condition for asymptotic normality of the scalar normalized version. In particular, when rn = r these conditions are the same, but when rn → ∞the former holds more generally.
Discontinuous homomorphisms from C*-algebras
Authors: Somerset D. W. B. 
Published: November 2008

AbstractA necessary and sufficient condition is given for a unital C*-algebra A to admit a discontinuous homomorphism into a Banach algebra which is continuous on its centre. The condition is that A must have a Glimm ideal G such that the C*-algebra A/G admits a discontinuous homomorphism into a Banach algebra.
On radial basis approximation on periodic grids
Authors: Buhmann Martin D. , Micchelli Charles A. 
Published: November 2008

A radial basis function approximation in n variables has the formwhere ø:ℝn → ℝ denotes the n-variate, spherically symmetric function associated with a prescribed radial basis function ø+:ℝ+ → ℝ, i.e. ø = ø+(‖ · ‖), the norm being Euclidean. The are real coefficients (often, approximants s above are considered where only finitely many λjs are non-zero), and is a fixed set of points in ℝn (of course, only the xj with non-zero coefficient λj affect s). Thus s is a linear combination of translates of a radially symmetric function which can be of global support, the simplest choice being , where c is a positive parameter. The latter is referred to as the multiquadric function and is usefull in applications.
Global bitangency properties of generic closed space curves
Authors: Ballesteros Juan J. Nuño , Romero Fuster M. Carmen 
Published: November 2008

AbstractWe study bitangency properties of space curves in general position from a global viewpoint. As a consequence we obtain some results on their total numbers of bitangent osculating planes and cross tangents, and prove that in the absence of both, the number of zero torsion points of a curve in general position is a multiple 4.
The algebra of differential forms on a full matric bialgebra
Authors: Sudbery A. 
Published: November 2008

AbstractWe construct a non-commutative analogue of the algebra of differential forms on the space of endomorphisms of a vector space, given a non-commutative algebra of functions and differential forms on the vector space. The construction yields a differential bialgebra which is a skew product of an algebra of functions and an algebra of differential forms with constant coefficients. We give necessary and sufficient conditions for such an algebra to exist, show that it is uniquely determined by the differential algebra on the vector space, and show that it is a non-commutative superpolynomial algebra in the matrix elements and their differentials (i.e. that it has the same dimensions of homogeneous components as in the classical case).
Subgroups and subrings of profinite rings
Authors: Abercrombie A. G. 
Published: November 2008

AbstractA profinite topological group is compact and therefore possesses a unique invariant probability measure (Haar measure). We shall see that it is possible to define a fractional dimension on such a group in a canonical way, making use of Haar measure and a natural choice of invariant metric. This fractional dimension is analogous to Hausdorff dimension in ℝ.It is therefore natural to ask to what extent known results concerning Hausdorff dimension in ℝ carry over to the profinite setting. In this paper, following a line of thought initiated by B. Volkmann in [12], we consider rings of a-adic integers and investigate the possible dimensions of their subgroups and subrings. We will find that for each prime p the ring of p-adic integers possesses subgroups of arbitrary dimension. This should cause little surprise since a similar result is known to hold in ℝ. However, we will also find that there exists a ring of a-adic integers possessing Borel subrings of arbitrary dimension. This is in contrast with the situation in ℝ, where the analogous statement is known to be false.
Hyperbolic Weingarten surfaces
Authors: Van-Brunt B. , Grant K. 
Published: November 2008

AbstractWeingarten surfaces which can be represented locally as solutions to second order hyperbolic partial differential equations are examined in this paper. In particular, the geometry of the families of curves corresponding to characteristics on these surfaces is investigated and the relationships of these curves with other curves on the surface such as asymptotic lines and lines of curvature are explored. It is shown that singularities in the lines of curvature, i.e. umbilic points, correspond to singularities in the families of characteristics, and that lines of curvature are non-characteristic curves. If there is a linear relation between the Gaussian and mean curvatures and real characteristics exist, then the characteristics form a Tchebychef net on the corresponding Weingarten surface.
Graphs with a locally linear group of automorphisms
Authors: Trofimov V. I. , Weiss R. M. 
Published: November 2008

Let Γ be an undirected graph, V(Γ) the vertex set of Γ and G a subgroup of aut(Γ). For each vertex x ↦ V(Γ), let Γx denote the set of vertices adjacent to x in Γ and the permutation group induced on Γx. by the stabilizer Gx. For each i ≥ 1, will denote the pointwise stabilizer in Gx of the set of vertices at distance at most i from x in Γ. Letfor each i ≥ 1 and any set of vertices x, y, …, z of Γ. An s-path (or s-arc) is an (s + 1)-tuple (x0, x1, … xs) of vertices such that xi ↦ Γxi–1 for 1 ≤ i ≤ s and xi ╪ xi–2 for 2 ≤ i ≤ s.
An oscillation theorem for self-adjoint differential systems and an index result for corresponding Riccati matrix differential equations
Authors: Kratz Werner 
Published: November 2008

AbstractThe main result of this paper is an oscillation theorem on linear self-adjoint differential systems and a corresponding eigenvalue problem. It establishes a formula between the number of focal points of a so-called conjoined basis of the differential system on a given compact interval and the number of eigenvalues which are less than the given eigenvalue parameter. It extends an earlier result of the author and generalizes an oscillation theorem of M. Morse. Among others the proof of the theorem requires a formula on the index of the difference of symmetric solutions of a corresponding Riccati matrix differential equation. This index formula is the other new result presented.
Global properties of locally spatially homogeneous cosmological models with matter
Authors: Rendall Alan D. 
Published: November 2008

AbstractThe existence and nature of singularities in locally spatially homogeneous solutions of the Einstein equations coupled to various phenoraenological matter models is investigated. It is shown that, under certain reasonable assumptions on the matter, there are no singularities in an expanding phase of the evolution and that unless the spacetime is empty a contracting phase always ends in a singularity where at least one scalar invariant of the curvature diverges uniformly. The class of matter models treated includes perfect fluids, mixtures of non-interacting perfect fluids and collisionless matter.
Projection theorems for box and packing dimensions
Authors: Falconer K. J. , Howroyd J. D. 
Published: November 2008

AbstractWe show that if E is an analytic subset of ℝn thenfor almost all m–dimensional subspaces V of ℝn, where projvE is the orthogonal projection of E onto V and dimp denotes packing dimension. The same inequality holds for lower and upper box counting dimensions, and these inequalities are the best possible ones.
Cosmological solutions of the Vlasov-Einstein system with spherical, plane, and hyperbolic symmetry
Authors: Rein Gerhard 
Published: November 2008

AbstractThe Vlasov-Einstein system describes a self-gravitating, collisionless gas within the framework of general relativity. We investigate the initial value problem in a cosmological setting with spherical, plane, or hyperbolic symmetry and prove that for small initial data solutions exist up to a spacetime singularity which is a curvature and a crushing singularity. An important tool in the analysis is a local existence result with a continuation criterion saying that solutions can be extended as long as the momenta in the support of the phase-space distribution of the matter remain bounded.
On the lengths of Koszul homology modules and generalized fractions
Authors: Cuong N. T. , Minh N. D. 
Published: November 2008

Throughout this paper, let A be a Noetherian local ring with maximal ideal m and M a finitely generated A-module with d = dimAM ≥ 1. Denote by N the set of all positive integers.Let x = (x1, …, xd) be a system of parameters (s.o.p) for M and letWe consider the following two problems: (i) When is the length of Koszul homologya polynomial in n for all k = 0, …, d and n1; …, nd sufficiently large (n ≫ 0)?(ii) Is the length of the generalized fraction in a polynomial in n for n ≫ 0?
On the homotopy theory of sheaves of simplicial groupoids
Authors: Joyal André , Tierney Myles 
Published: November 2008

The aim of this paper is to contribute to the foundations of homotopy theory for simplicial sheaves, as we believe this is the natural context for the development of non-abelian, as well as extraordinary, sheaf cohomology.In [11] we began constructing a theory of classifying spaces for sheaves of simplicial groupoids, and that study is continued here. Such a theory is essential for the development of basic tools such as Postnikov systems, Atiyah-Hirzebruch spectral sequences, characteristic classes, and cohomology operations in extraordinary cohomology of sheaves. Thus, in some sense, we are continuing the program initiated by Illusie[7], Brown[2], and Brown and Gersten[3], though our basic homotopy theory of simplicial sheaves is different from theirs. In fact, the homotopy theory we use is the global one of [10]. As a result, there is some similarity between our theory and the theory of Jardine[8], which is also partially based on [10]
Invariant states and ergodic dynamical systems on W*-algebras
Authors: uczak Andrzej 
Published: November 2008

AbstractAn amenable semigroup of positive linear unital mappings on a W*-algebra is considered. Two main questions are dealt with: the existence of a normal faithful state invariant with respect to this semigroup and the description of ergodicity conditions. An explicit form of the ergodic projection, useful in treating the ergodicity problems, is also derived.
Geometric characterization of separable second-order differential equations
Authors: Martínez Eduardo , Cariñena José F. , Sarlet Willy 
Published: November 2008

AbstractWe establish necessary and sufficient conditions for the separability of a system of second-order differential equations into independent one-dimensional second-order equations. The characterization of this property is given in terms of geometrical objects which are directly related to the system and relatively easy to compute. The proof of the main theorem is constructive and thus yields a practical procedure for constructing coordinates in which the system decouples.
Some Properties of Dipole and Quadripole Radiation from Nuclei
Authors: Taylor H. M. 
Published: November 2008

1. The purpose of this paper is to examine in detail the types of radiation emitted by a quantum mechanical system (representing a nucleus) when the radiating particle changes its azimuthal quantum number l by two, one, or nought. We assume that the radiating particle is spinless* and that it moves in a field possessing central symmetry, so that the particle may be described by a wave function ψn,l,m which factorizes into radial and angular parts,We assume secondly that the nucleus has a finite radius aN of the order of 10−12 cm., that is to say that π(r) = 0 for r > aN.
Functional programming for business students
Authors: Molyneux Phil 
Published: November 2008

AbstractA functional language, Miranda, is being used on an introductory programming course for business students. This paper describes the rationale for such a course and choice of language. An application in the area of operations management, which is used in teaching, is given as an example of the benefits of using a functional language in this area. The reaction of the students and staff to this (for them) new paradigm of programming is described. Some conclusions are drawn for computing education for non-specialists.
Improving intervals
Authors: Jackson W. Ken , Burton F. Warren 
Published: November 2008

AbstractWe show how improving values (Burton, 1991) can be extended to handle both upper and lower bounds. The result is a new data type, called improving intervals. We give a simple implementation of improving intervals that uses a list of successively tighter bounds to represent a value. A program using improving intervals can be evaluated as a parallel program using speculative evaluation. The utility of improving intervals is demonstrated through two programs: parallel alpha-beta and parallel branch-and-bound
A Debugger for Standard ML
Authors: Tolmach Andrew , Appel Andrew W. 
Published: November 2008

AbstractWe have built a portable, instrumentation-based, replay debugger for the Standard ML of New Jersey compiler. Traditional ‘source-level’ debuggers for compiled languages actually operate at machine level, which makes them complex, difficult to port, and intolerant of compiler optimization. For secure languages like ML, however, debugging support can be provided without reference to the underlying machine, by adding instrumentation to program source code before compilation. Because instrumented code is (almost) ordinary source, it can be processed by the ordinary compiler. Our debugger is thus independent from the underlying hardware and runtime system, and from the optimization strategies used by the compiler. The debugger also provides reverse execution, both as a user feature and an internal mechanism. Reverse execution is implemented using a checkpoint and replay system; checkpoints are represented primarily by first-class continuations.
Prototyping a parallel vision system in Standard ML
Authors: Michaelson Greg , Scaife Norman 
Published: November 2008

AbstractThe construction of a parallel vision system from Standard ML prototypes is presented. The system recognises 3D objects from 2D scenes through edge detection, grouping of edges into straight lines and line junction based model matching. Functional prototyping for parallelism is illustrated through the development of the straight line detection component. The assemblage of the whole system from prototyped components is then considered and its performance discussed.
A confluent reduction for the λ-calculus with surjective pairing and terminal object
Authors: Curien Pierre-Louis , Cosmo Roberto Di 
Published: November 2008

AbstractWe exhibit confluent and effectively weakly normalizing (thus decidable) rewriting systems for the full equational theory underlying cartesian closed categories, and for polymorphic extensions of it. The λ-calculus extended with surjective pairing has been well-studied in the last two decades. It is not confluent in the untyped case, and confluent in the typed case. But to the best of our knowledge the present work is the first treatment of the lambda calculus extended with surjective pairing and terminal object via a confluent rewriting system, and is the first solution to the decidability problem of the full equational theory of Cartesian Closed Categories extended with polymorphic types. Our approach yields conservativity results as well. In separate papers we apply our results to the study of provable type isomorphisms, and to the decidability of equality in a typed λ-calculus with subtyping.
Representing demand by partial projections
Authors: Launchbury John , Baraki Gebreselassie 
Published: November 2008

AbstractThe projection-based strictness analysis of Wadler and Hughes is elegant and theoretically satisfying except in one respect: the need for lifting. The domains and functions over which the analysis is performed need to be transformed, leading to a less direct correspondence between analysis and program than might be hoped for. In this paper we shall see that the projection analysis may be reformulated in terms of partial projections, so removing this infelicity. There are additional benefits of the formulation: the two forms of information captured by the projection are distinguished, and the operational significance of the range of the projection fits exactly with the theory of unboxed types.
Stability for time-dependent differential equations
Authors: Kreiss Heinz-Otto , Lorenz Jens 
Published: November 2008

In this paper we review results on asymptotic stability of stationary states of PDEs. After scaling, our normal form is ut = Pu + ε f(u, ux,…) + F(x, t), where the (vector-valued) function u(x, t) depends on the space variable x and time t. The differential operator P is linear, F(x, t) is a smooth forcing, which decays to zero for t → ∞, and εf(u, …) is a nonlinear perturbation. We will discuss conditions that ensure u → 0 for t → ∞ when |ε| is sufficiently small. If this holds, we call the problem asymptotically stable.While there are many approaches to show asymptotic stability, we mainly concentrate on the resolvent technique. However, comparisons with the Lyapunov technique will also be given. The emphasis on the resolvent technique is motivated by the recent interest in pseudospectra.
CAN'T BUY ME WHITENESS
Authors: Pearson Jay A. 
Published: November 2008

AbstractA basic tenet of public health is that there is a robust relationship between socioeconomic status and health. Researchers widely accept that persons at average or median levels of socioeconomic status have better health compared to those at lower levels—with a detectable, if diminishing, gradient at even higher levels of socioeconomic status. The research on which this tenet is based, however, focuses largely on Whites, especially on White men. Yet according to the full range of extant findings, the magnitude and in some cases the direction of this relationship vary considerably for other demographic groups.I argue that the failure to clearly qualify study conclusions when they are restricted to the study of Whites impedes our understanding of the varying relationship between socioeconomic status and health for different demographic groups. Such an impediment is particularly harmful when considering health inequalities among populations defined by race and ethnicity. Frameworks and models based on traditional socioeconomic measures may mask heterogeneity, overestimate the benefits of material resources, underestimate psychosocial and physical health costs of resource acquisition for some groups, and overlook the value of alternative sociocultural orientations. These missed opportunities have grave consequences: large racial/ethnic health disparities persist while the health disadvantages of Black Americans continue to grow in key aspects. A new knowledge base is needed if racial/ethnic health disparities are to be eliminated, including new guiding theoretical frameworks, reinterpretations of existing research, and new empirical research. This article aims to initiate discussion on all three dimensions.
THE INFLUENCE OF AFRICAN AMERICANS ON CONGRESS
Authors: Tien Charles , Levy Dena 
Published: November 2008

AbstractIn this paper we approach, from a different angle than previous research, the question of whether gains in descriptive representation for African Americans result in losses in substantive representation. By looking at how the presence of African Americans has changed Congress over time, we assess the long-term impact of electing more African Americans to Congress on substantive representation. Specifically, we content analyze House floor debates on civil rights legislation, from 1957 to 1991, and find that Black members have influenced how White members talk about civil rights.
Continuous Local Intra-Arterial Infusion of Anticoagulants for Digit Replantation and Treatment of Damaged Arteries
Authors: Fukui Akihiro , Maeda Masami , Sempuku Takeo , Tamai Susumu , Mizumoto Shigeru , Inada Yūji 
Published: November 2008

From May 1958 to May 1987, 428 upper extremities were replanted, with an overall survival rate of 87.4 percent. With the aim of increasing the survival rate a new method was tried. Unlike conventional continuous intravenous infusion, a Teflon catheter (28 gauge) was inserted into the proximal main artery of the anastomosed artery, and a daily dose of 80 ml comprising 240,000 U of urokinase, 40 μg of prostaglandin E,, 10,000 U (maximum) of heparin, and low molecular weight dextran was administered by means of continuous infusion for the 10 consecutive days, during which arterial thrombosis is likely to occur.Thirteen cases (replantations and damaged digital arteries) survived without any re-operation for arterial thrombus. There were statistically significant differences (p < 0.025) in platelet count, fibrinogen, and AT III preoperatively and three days postoperatively. There were also statistically significant differences (p < 0.05) in prothrombin time, partial thromboplastin time, and clotting time between pre-operative measurements and those taken four and 15 hr postoperative, but those data remained within normal range. No abnormalities were present in the arteries through which the catheter was inserted, as validated by postoperative digital subtraction angiography.