bluuebunny/crossref_metadata_2025 huggingface dataset:
Girth and Independence Ratio
Authors: Hopkins Glenn , Staton William
Published: December 2010

Lower bounds are given for the independence ratio in graphs satisfying certain girth and maximum degree requirements. In particular, the independence ratio of a graph with maximum degree Δ and girth at least six is at least (2Δ − 1)/(Δ2 + 2Δ − 1). Sharper bounds are given for cubic graphs.
Nonclassical Orthogonal Polynomials as Solutions to Second Order Differential Equations
Authors: Littlejohn Lance L. , Shore Samuel D.
Published: December 2010

One of the more popular problems today in the area of orthogonal polynomials is the classification of all orthogonal polynomial solutions to the second order differential equation:

In this paper, we show that the Laguerre type and Jacobi type polynomials satisfy such a second order equation.
Natural Covers andR-Quotient Maps
Authors: Karnik S. M. , Willard S.
Published: December 2010

We extend the comprehensive treatment ofk-spaces and sequential spaces provided by Franklin's refined notion of a natural cover tokR-spaces andsR-spaces. For this purpose, an apparently unstudied class of maps of topological spaces, the class ofR-quotient maps, is introduced.
On the Ideal Equation I(B ∩ C) = IB∩IC
Authors: Anderson D. D.
Published: December 2010

Let R be an integral domain with quotient field K and let I be a nonzero ideal of R. We show (1) that I is invertible if and only if for every nonempty collection {Bα} of ideals of R and (2) that I is flat if and only if I(B ∩ C) = IB∩IC for each pair of ideals B and C of R.
On Uniform Convergence of Continuous Functions and Topological Convergence of Sets
Authors: Beer Gerald
Published: December 2010

Let X and Y be metric spaces. This paper considers the relationship between uniform convergence in C(X, Y) and topological convergence of functions in C(X, Y), viewed as subsets of X×Y. In general, uniform convergence in C(X, Y) implies Hausdorff metric convergence which, in turn, implies topological convergence, but if X and Y are compact, then all three notions are equivalent. If C([0, 1], Y) is nontrivial arid topological convergence in C(X, Y) implies uniform converger ce then X is compact. Theorem: Let X be compact and Y be loyally compact but noncompact. Then topological convergence in C(X, Y) implies uniform convergence if and only if X has finitely many components. We also sharpen a related result of Naimpally.
Regular Digraphs Containing a Given Digraph
Authors: Harary Frank , Karabed Razmik
Published: December 2010

Let the maximum degree d of a digraph D be the maximum of the set of all outdegrees and indegrees of the points of D. We prove that every digraph D of order P and maximum degree d has a d-regular superdigraph H with at most d + 1 more points, and that this bound, which is independent of p, is best possible.
Zero-Free Regions for Polynomials and Some Generalizations of Eneström-Kakeya Theorem
Authors: Aziz Abdul , Mohammad Q. G.
Published: December 2010

In this paper we shall use matrix methods to obtain several generalizations of a well known result of Eneström and Kakeya about the location of the zeros of polynomials. We shall also obtain zero-free regions of polynomials having complex coefficients. Finally we prove some results concerning the zeros of a class of polynomials.
On Some Recent Interactions Between Mathematics and Physics
Authors: Bott Raoul
Published: December 2010

It gives me quite extraordinary pleasure to have been asked to deliver the Jeffrey-Williams lecture of the Canadian Mathematical Society. The reasons are manifold. First of all Canada was my home for the most formative years of my life — from 16 to 23 — and was in fact the first country willing to take me on as an adopted son. I was of course born in Budapest, but in Europe the geographical accidents of birth are not taken seriously, rather I inherited my father's status and so managed to become stateless "by induction" so to speak.
Modular Parametrizations of Elliptic Curves
Authors: Zagier D.
Published: December 2010

Many — conjecturally all — elliptic curves E/ have a "modular parametrization," i.e. for some N there is a map φ from the modular curve X0(N) to E such that the pull-back of a holomorphic differential on E is a modular form (newform) f of weight 2 and level N. We describe an algorithm for computing the degree of φ as a branched covering, discuss the relationship of this degree to the "congruence primes" for f (the primes modulo which there are congruences between f and other newforms), and give estimates for the size of this degree as a function of N.
Metastable Immersion, Span and the Two-type of a Manifold
Authors: Glover Henry , Homer William
Published: December 2010

The existence of metastable immersion or span for space forms and homogeneous spaces is shown to depend only on the two-type of the space.
On Radicals of Submodules of Finitely Generated Modules
Authors: McCasland Roy L. , Moore Marion E.
Published: December 2010

The concept of the M-radical of a submoduleBof anR-moduleAis discussed (Ris a commutative ring with identity and A is a unitary fl-module). The M-radical ofBis defined as the intersection of all prime submodules of A containingB.The main result of the paper is that ifdenotes the ideal radical of (B:A), then M-radB =provided that A is a finitely generated multiplication module. Additionally, it is shown that if A is an arbitrary module,wherefor some
Connectedness Properties of Lattices
Authors: Vainio R.
Published: December 2010

LetLbe a lattice andqa convergence structure (or a topology) finer than the interval topology ofL.In case of compact maximal chains and continuous lattice translations, the connected components of the space(L,q)are characterized using lattice conditions only. Moreover, lattice conditions ofLare related to connectedness conditions of the order convergence space (L,o).Throughout this note, maximal chain conditions and maximal chain techniques play an important role.
Embedding Partial Graph Designs, Block Designs, and Triple Systems with λ > 1
Authors: Colbournt C. J. , Hamm R. C. , Lindner C. C. , Lindner C. C. , Rodger C. A.
Published: December 2010

A general embedding technique for graph designs and block designs is developed, which transforms the embedding problem for partial designs with ƛ > 1 into the embedding problem for partial designs with ƛ = 1. Given an embedding technique for n-element partial block designs with ƛ = 1 into block designs with f(n) elements, the transformation produces a technique which embeds an «-element partial design with ƛ > 1 and block size k into a design with at most /(3k-1ƛn2) elements. For graph designs and block designs with k > 3, a finite embedding method results. For triple systems, a quadratic embedding technique is obtained immediately; the best previous result here was exponential. Finally, for partial triple systems, Mendelsohn triple systems, and directed triple systems, these quadratic embeddings are improved to linear using a colouring technique.
A General Formula on the Conjugate of the Difference of Functions
Authors: Hiriart-Urruty J.-B.
Published: December 2010

Given an arbitrary function g :X → (-∞, +∞] and a lowersemicontinuous convex function h:X → (-∞, +∞], we give the general expression of the conjugate (g — h)* of g - h in terms of g* and h*. As a consequence, we get Toland's duality theorem:
ON H-Sets and Open Filter Adherences(1)
Authors: Krystock Robert L.
Published: December 2010

The relationship between H-sets and open filter adhérences is considered. The open filter adhérences of an H-closed space are shown to be H-sets; and, a necessary and sufficient condition is given for an H-set S, of a Hausdorff space X, to be an open filter adherence. A necessary condition is determined for the existence of a minimal adherent set which contains S; and, in the case that X is H-closed, sufficient conditions are determined. As a related result, an H-closed space X is shown to be seminormal if every H-set of X possesses a neighborhood base consisting of regular open sets.
The Solution to a Problem of Grünbaum
Authors: Salamon Peter , Erdös Paul
Published: December 2010

The paper characterizes the set of all possible values for the number of lines determined by n points for n sufficiently large. For the lower bound of Kelly and Moser for the number of lines in a configuration with n — k collinear points is shown to be sharp and it is shown that all values between Mmin(k) and Mmax(k) are assumed with the exception of Mmax — 1 and Mmax — 3. Exact expressions are obtained for the lower end of the continuum of values leading down from In particular, the best value of c = 1 is obtained in Erdös’ previous expression for this lower end of the continuum.
Some Continued Fractions of Ramanujan and Meixner-Pollaczek Polynomials
Authors: Masson David R.
Published: December 2010

We examine the convergence and analytic properties of a continued fraction of Ramanujan and its connection to the orthogonal polynomials of Meixner-Pollaczek.
The Set of Finite Operators is Nowhere Dense
Authors: Herrero Domingo A.
Published: December 2010

A bounded linear operator A on a complex, separable, infinite dimensional Hilbert space is called finite if for each . It is shown that the class of all finite operators is a closed nowhere dense subset of
Bijective Proofs of Some n-Color Partition Identities
Authors: Agarwal A. K.
Published: December 2010

Using a technique of Agarwal and Andrews (1987), bijective proofs of some n-color partition identities discovered recently by the author, are given.
Blowing-Up and Whitney (a)-Regularity
Authors: Kuo Tzee-Char , Trotman David J. A. , Xin Li Pei
Published: December 2010

When a pair of adjacent C1 strata (X, Y) is Whitney (a)- regular at a point , there is, up to homeomorphism, just one germ at 0 of intersections S ∩ X where S is a Lipschitz transversal to Y at 0 (S is the graph of a Lipschitz map from The proof uses a blowing-up construction and a strong form of Verdier's (w)-regularity.
On a Result of Bruns
Authors: Kummer Martin , Churchill Richard C. , Rod David L.
Published: December 2010

Bruns' Theorem states that the classical integrals of the gravitational three-body problem generate all algebraic integrals. We show that the first step in his proof, together with Ziglin's non-integrability criterion for complex systems, can be used to prove the non-existence of energy independent algebraic integrals in certain real analytic systems. We also show that this aspect of Bruns' argument is purely algebraic: We offer a proof based on elementary differential algebraic methods.
Interpolation and Spectra of Regular LP-Space Operators
Authors: Saxe Karen
Published: December 2010

We consider the Banach algebra consisting of linear operators T which are defined on the simple functions and have bounded extensions Tp on LP for all values of p ∊ [1, ∞]. We show that the 'integral' operators in this algebra form a right ideal, and that each Tp associated to an integral T is regular. When the underlying measure is finite or special discrete we show further that every Tp is regular for every T in the algebra. Algebraic techniques together with interpolation results are then used to get relationships between the spectrum and the order spectrum of the associated Tp's.
Rings of Invariants and p-Sylow Subgroups
Authors: Campbell H. E. A. , Hughes I. , Pollack R. D.
Published: December 2010

Let V be a vector space of dimension n over a field k of characteristic p. Let G ⊆ Gl(V) be a finite group with p-Sylow subgroup P. G and P act on the symmetric algebra R of V. Denote the respective rings of invariants by RG and Rp. We show that if Rp is Cohen-Macaulay (CM) so also is RG, generalizing a result of M. Hochster and J. A. Eagon. If P is normal in G and G is generated by P and pseudo-reflections, we show that if RG is CM so also is Rp. However, in general, RG may even be polynomial with Rp not CM. Finally, we give a procedure for determining a set of generators for RG given a set of generators for Rp.
Some Applications of a Theorem of Marcinkiewicz
Authors: Bullen P. S. , Vyborny R.
Published: December 2010

A classical theorem of Marcinkiewicz states that a function is Perron integrable iff it has one continuous major and one continuous minor function. Using an elaboration of this remarkable theorem three applications are made; to obtain a new proof of a recent characterization of the Perron integral, to proofs of some theorems on interchange of limits and integration and to extend classical existence theorems for ordinary differential equations.
Vertically of (-1)-Lines in Scrolls Over Smooth Surfaces
Authors: Lanteri Antonio
Published: December 2010

Let S be a smooth surface contained as an ample divisor in a smooth complex projective threefoldX, which is aP1-bundle, and assume thatinduces OP1(1) on the fibres ofX. The following fact is proven. The restriction toSof the bundle projection of X is exactly the reduction morphism of the pairprovided that this one is not a conic bundle. The proof is very simple and does not involve any consideration on the nefness of the adjoint bundleSome applications of the proof are given.
On Stratifications of Derived Module Categories
Authors: Wiedemann Alfred
Published: December 2010

Some structural results about quotients and tensor products of hereditary respectively quasi-hereditary algebras are presented. They are related to properties of stratifications of derived module categories. The concept of derived-simplicity for an algebra is introduced and studied.
A Probabilistic Approach to Gradient Estimates
Authors: Cranston M.
Published: December 2010

Suppose u is a harmonic function on a domain D and x, x' are in D. We estimate |u(x) — u(x')| using two Brownian motions started at x and x' and killed on exiting a cube Q ⊂ D. By selecting appropriate versions of the two Brownian motions, a classical gradient estimate for u is easily derived.
On the Complete Invariance Property in Some Uncountable Products
Authors: Koszmider Piotr
Published: December 2010

We consider uncountable products of nontrivial compact, convex subsets of normed linear spaces. We show that these products do not have the complete invariance property i.e. they include a nonempty, closed subset which is not a fixed point set (i.e. the set of all fixed points) for any continuous mapping from the product into itself. In particular we give an answer to W.Weiss' question whether uncountable powers of the unit interval have the complete invariance property.
Harmonic Spinors on Hyperbolic Space
Authors: Gaillard Pierre-Yves
Published: December 2010

The purpose for this short note is to describe the space of harmonic spinors on hyperbolicn-spaceHn. This is a natural continuation of the study of harmonic functions onHnin [Minemura] and [Helgason]—these results were generalized in the form of Helgason's conjecture, proved in [KKMOOT],—and of [Gaillard 1, 2], where harmonic forms onHnwere considered. The connection between invariant differential equations on a Riemannian semisimple symmetric spaceG/Kand homological aspects of the representation theory ofG, as exemplified in (8) below, does not seem to have been previously mentioned. This note is divided into three main parts respectively dedicated to the statement of the results, some reminders, and the proofs. I thank the referee for having suggested various improvements.
Cyclic Subgroup Separability of Generalized Free Products
Authors: Kim Goansu
Published: December 2010

We derive a criterion for a generalized free product of groups to be cyclic subgroup separable. We see that most of the known results for cyclic subgroup separability are covered by this criterion, and we apply the criterion to polygonal products of groups. We show that a polygonal product of finitely generated abelian groups, amalgamating cyclic subgroups, is cyclic subgroup separable.
Submanifolds with Nonparallel First Normal Bundle
Authors: Dajczer Marcos , Tojeiro Ruy
Published: December 2010

We provide a complete local geometric description of submanifolds of spaces with constant sectional curvature where the first normal spaces, that is, the subspaces spanned by the second fundamental form, form a vector subbundle of the normal bundle of low rank which is nonparallel in the normal connection. We also characterize flat submanifolds with flat normal bundle in Euclidean space satisfying the helix property.
On Commutativity and Strong Commutativity-Preserving Maps
Authors: Bell Howard E. , Daif Mohamad Nagy
Published: December 2010

If R is a ring and S ⊆ R, a mapping f:R —> R is called strong commutativity- preserving (scp) on S if [x, y] = [f(x),f(y)] for all x,y € S. We investigate commutativity in prime and semiprime rings admitting a derivation or an endomorphism which is scp on a nonzero right ideal.
Configurations de Particules et Espaces de Modules
Authors: Hurtubise J. C.
Published: December 2010

Cet article de survol est le résumé de la conférence Coxeter-James de l'auteur, prononcée à la réunion d'hiver 1993 de la Société Mathématique du Canada.

La théorie de Morse décrit les liens entre la topologie d'une variété et la topologie des points critiques d'une fonction sur cette variété. La fonctionnelle d'énergie pour les applications d'une surface dans une variété, dont les points critiques seront des applications harmoniques et parfois holomorphes, et la fonctionnelle de Yang-Mills pour des connections sur une variété de dimension quatre sont deux cas en dimension infinie pour lesquels la théorie de Morse ne tient pas. Néanmois, dans les deux cas, on peut récupérer une quantité étonnante d'information, pourvu qu'on stabilise par rapport à un degré ou une charge qui sont des données du problème. Les preuves recyclent des résultats de la théorie de l'homotopie des années '70, et les combinent à des idées de géométrie complexe pour donner de jolis modèles des espaces en cause en termes de "particules". Nous espérons donner un survol général et accessible des idées utilisées.
Characters and Point Evaluations
Authors: Ransford T. J.
Published: December 2010

We give a simple proof that, if X is a Lindelöf topological space, and A is an algebra of continuous real-valued functions on X which is inverse-closed, local and z-regular, then every character on A is a point evaluation. We also give a number of examples to illustrate both the applications of this theorem and its limitations.
α-Derivations
Authors: Redondo María Julia , Solotar Andrea
Published: December 2010

Let A be a commutative k-algebra with 1. We present a characterization of α-derivations, for α: A →> A a morphism of algebras, using α-Taylor series. When S = C[x,x-1,ξ] and α(x) = qx, α(ξ) = qξ, we compare the q-de Rham cohomology of the C-algebra S with the Hochschild homology of Dq, the algebra of q-difference operators on C[x,x-1], for q ∊ C, q ≠ 0,1.
La formule de Cauchy sur la longueur d’une courbe
Authors: Ayari S. , Dubuc S.
Published: December 2010

Pour toute courbe rectifiable du plan, nous démontrons la formule de Cauchy relative à sa longueur. La formule est donnée sous deux formes: comme intégrale de la variation totale des projections de la courbe dans les diverses directions et comme intégrale double du nombre de rencontres de la courbe avec une droite quelconque du plan.
On projective Z-frames
Authors: Dongsheng Zhao
Published: December 2010

This paper deals with the projective objects in the category of all Z-frames, where the latter is a common generalization of different types of frames. The main result obtained here is that a Z-frame is E-projective if and only if it is stably Z-continuous, for a naturally arising collection E of morphisms.
An Explicit Criterion for the Convexity of Quaternionic Numerical Range
Authors: So Wasin
Published: December 2010

Quaternionic numerical range is not always a convex set. In this note, an explicit criterion is given for the convexity of quaternionic numerical range.
An Oscillation Criterion for First Order Linear Delay Differential Equations
Authors: Philos CH. G. , Sficas Y. G.
Published: December 2010

A new oscillation criterion is given for the delay differential equation, whereand the functionTdefined byis increasing and such that. This criterion concerns the case where.
On Arithmetic Means of Sequences Generated by a Periodic Function
Authors: Fiorito Giovanni
Published: December 2010

In this paper we prove the convergence of arithmetic means of sequences generated by a periodic function φ(x), moreover if φ(x) satisfies a suitable symmetry condition, we prove that their limit is φ(0). Applications of previous results are given to study other means of sequences and the behaviour of a class of recursive series.
Topological Quantum Field Theory and Strong Shift Equivalence
Authors: Gilmer Patrick M.
Published: December 2010

Given a TQFT in dimensiond+ 1; and an infinite cyclic covering of a closed (d+ 1)-dimensional manifoldM, we define an invariant taking values in a strong shift equivalence class of matrices. The notion of strong shift equivalence originated in R. Williams’ work in symbolic dynamics. The Turaev-Viro module associated to a TQFT and an infinite cyclic covering is then given by the Jordan form of this matrix away from zero. This invariant is also defined if the boundary ofMhas anS1factor and the infinite cyclic cover of the boundary is standard. We define a variant of a TQFT associated to a finite groupGwhich has been studied by Quinn. In this way, we recover a link invariant due to D. Silver and S. Williams. We also obtain a variation on the Silver-Williams invariant, by using the TQFT associated toGin its unmodified form.
C*-Convexity and the Numerical Range
Authors: Magajna Bojan
Published: December 2010

If A is a prime C*-algebra, a ∈ A and λ is in the numerical range W(a) of a, then for each ε > 0 there exists an element h ∈ A such that . If λ is an extreme point of W(a), the same conclusion holds without the assumption that A is prime. Given any element a in a von Neumann algebra (or in a general C*-algebra) A, all normal elements in the weak* closure (the norm closure, respectively) of the C*-convex hull of a are characterized.
On the Number of Divisors of the Quadratic Form m2 + n2
Authors: Yu Gang
Published: December 2010

For an integer n, let d(n) denote the ordinary divisor function. This paper studies the asymptotic behavior of the sum

It is proved in the paper that, as x → ∞,

where A1 and A2 are certain constants and ε is any fixed positive real number.

The result corrects a false formula given in a paper of Gafurov concerning the same problem, and improves the error claimed by Gafurov.
Une classe d’hamiltoniens polynomiaux isochrones
Authors: Schuman Bertrand
Published: December 2010

Soit un hamiltonien isochrone du plan . On met en évidence une classe d’hamiltoniens isochrones qui sont des perturbations polynomiales de H0. On obtient alors une condition nécessaire d’isochronisme, et un critère de choix pour les hamiltoniens isochrones. On voit ce résultat comme étant une généralisation du caractère isochrone des perturbations hamiltoniennes homogènes considérées dans [L], [P], [S].
Very Ample Linear Systems on Blowings-Up at General Points of Projective Spaces
Authors: Coppens Marc
Published: December 2010

Let Pn be the n-dimensional projective space over some algebraically closed field k of characteristic 0. For an integer t ≥ 3 consider the invertible sheaf O(t) on Pn (Serre twist of the structure sheaf). Let , the dimension of the space of global sections of O(t), and let k be an integer satisfying 0 < k ≤ N − (2n + 2). Let P1,…,Pk be general points on Pn and let π : X → Pn be the blowing-up of Pn at those points. Let Ei = π−1(Pi) with 1 ≤ i ≤ k be the exceptional divisor. Then M = π*(O(t)) ⊗ OX(−E1 — … — Ek) is a very ample invertible sheaf on X.
Obstruction à la linéarisation des champs de vecteurs polynomiaux
Authors: Cresson Jacky
Published: December 2010

On explicite une classe de champ de vecteurs polynomiaux non analytiquement lin éarisables à l'aide de la correction introduite par Écalle-Vallet. Notamment, on étend des résultats de Schuman sur la trivialit é des hamiltoniens homogàenes isochrones.
On the Essential Dimension of Some Semi-Direct Products
Authors: Ledet Arne
Published: December 2010

We give an upper bound on the essential dimension of the group over the rational numbers, when q is a prime power.
Tracially Quasidiagonal Extensions
Authors: Lin Huaxin
Published: December 2010

It is known that a unital simple C*-algebra A with tracial topological rank zero has real rank zero. We show in this note that, in general, there are unital C*-algebras with tracial topological rank zero that have real rank other than zero.

Let 0 → J → E → A → 0 be a short exact sequence of C*-algebras. Suppose that J and A have tracial topological rank zero. It is known that E has tracial topological rank zero as a C*-algebra if and only if E is tracially quasidiagonal as an extension. We present an example of a tracially quasidiagonal extension which is not quasidiagonal.
Optimization of Polynomial Functions
Authors: Marshall M.
Published: December 2010

This paper develops a refinement of Lasserre's algorithm for optimizing a polynomial on a basic closed semialgebraic set via semidefinite programming and addresses an open question concerning the duality gap. It is shown that, under certain natural stability assumptions, the problem of optimization on a basic closed set reduces to the compact case.
Congruence Class Sizes in Finite Sectionally Complemented Lattices
Authors: Grätzer G. , Schmidt E. T.
Published: December 2010

The congruences of a finite sectionally complemented lattice L are not necessarily uniform (any two congruence classes of a congruence are of the same size). To measure how far a congruence Θ of L is from being uniform, we introduce Spec Θ, the spectrum of Θ, the family of cardinalities of the congruence classes of Θ. A typical result of this paper characterizes the spectrum S = (mj | j < n) of a nontrivial congruence Θ with the following two properties:
Ramification des séries formelles
Authors: Laubie François
Published: December 2010

Let p be a prime number. Let k be a finite field of characteristic p. The subset X + X2k[[X]] of the ring k[[X]] is a group under the substitution law ○ sometimes called the Nottingham group of k, it is denoted by Rk. The ramification of one series γ ∈ Rk is caracterized by its lower ramification numbers: , as well as its upper ramification numbers:

By Sen's theorem, the um(γ) are integers. In this paper, we determine the sequences of integers (um) for which there exists γ ∈ Rk such that um(γ) = um for all integer m & 0.
An Integral Formula on Seifert Bundles
Authors: Fawaz Amine
Published: December 2010

We prove an integral formula on closed oriented manifolds equipped with a codimension two foliation whose leaves are compact.
An Inversion Formula of the Radon Transform on the Heisenberg Group
Authors: He Jianxun
Published: December 2010

In this paper we give an inversion formula of the Radon transform on the Heisenberg group by using the wavelets defined in [3]. In addition, we characterize a space such that the inversion formula of the Radon transform holds in the weak sense.
Continuous Adjacency Preserving Maps on Real Matrices
Authors: Rodman Leiba , Šemrl Peter , Sourour Ahmed R.
Published: December 2010

It is proved that every adjacency preserving continuous map on the vector space of real matrices of fixed size, is either a bijective affine tranformation of the form A ⟼ PAQ + R, possibly followed by the transposition if the matrices are of square size, or its range is contained in a linear subspace consisting of matrices of rank at most one translated by some matrix R. The result extends previously known theorems where the map was assumed to be also injective.
Vector Fields and the Cohomology Ring of Toric Varieties
Authors: Kaveh Kiumars
Published: December 2010

LetXbe a smooth complex projective variety with a holomorphic vector field with isolated zero setZ. From the results of Carrell and Lieberman there exists a filtrationF0⊂F1⊂ · · · ofA(Z), the ring of ℂ-valued functions onZ, such thatas graded algebras. In this note, for a smooth projective toric variety and a vector field generated by the action of a 1-parameter subgroup of the torus, we work out this filtration. Our main result is an explicit connection between this filtration and the polytope algebra ofX.
Non Abelian Twisted Reidemeister Torsion for Fibered Knots
Authors: Dubois Jérôme
Published: December 2010

In this article, we give an explicit formula to compute the non abelian twisted sign-determined Reidemeister torsion of the exterior of a fibered knot in terms of its monodromy. As an application, we give explicit formulae for the non abelian Reidemeister torsion of torus knots and of the figure eight knot.
Unimodular Roots of Special Littlewood Polynomials
Authors: Mercer Idris David
Published: December 2010

We call α(z) = a0 + a1z + · · · + an–1zn–1 a Littlewood polynomial if aj = ±1 for all j. We call α(z) self-reciprocal if α(z) = zn–1α(1/z), and call α(z) skewsymmetric if n = 2m + 1 and am+j = (–1)jam–j for all j. It has been observed that Littlewood polynomials with particularly high minimum modulus on the unit circle in ℂ tend to be skewsymmetric. In this paper, we prove that a skewsymmetric Littlewood polynomial cannot have any zeros on the unit circle, as well as providing a new proof of the known result that a self-reciprocal Littlewood polynomial must have a zero on the unit circle.
A K3 Surface Associated With Certain Integral Matrices Having Integral Eigenvalues
Authors: van Luijk Ronald
Published: December 2010

In this article we will show that there are infinitely many symmetric, integral 3× 3 matrices, with zeros on the diagonal, whose eigenvalues are all integral. We will do this by proving that the rational points on a certain non-Kummer, singular K3 surface are dense. We will also compute the entire Néron–Severi group of this surface and find all low degree curves on it.
Artinian Local Cohomology Modules
Authors: Lorestani Keivan Borna , Sahandi Parviz , Yassemi Siamak
Published: December 2010

Let R be a commutative Noetherian ring, α an ideal of R and M a finitely generated R-module. Let t be a non-negative integer. It is known that if the local cohomology module is finitely generated for all i < t, then is finitely generated. In this paper it is shown that if is Artinian for all i < t, then need not be Artinian, but it has a finitely generated submodule N such that /N is Artinian.
Developing a theory of sport-based entrepreneurship
Authors: Ratten Vanessa
Published: December 2010

Entrepreneurship is an integral part of sport but less is known about how different types of entrepreneurship facilitate innovation. The aim of this paper is to develop a theory of sports-based entrepreneurship that incorporates different sub-categories of entrepreneurship such as social, technological and international. Specifically, the article connects the entrepreneurship and sport management literatures by proposing a theory of sport-based entrepreneurship, which can be used as a theoretical framework for future research. In addition, the paper provides a unique insight for sports practitioners and public policy planners wanting to focus on entrepreneurial ways to manage sport-based organizations.
A model for improving board performance: The case of a national sport organisation
Authors: Ferkins Lesley , Mcdonald Gael , Shilbury David
Published: December 2010

The transition of many sport organisations from being predominantly volunteer-administered and anchored in an amateur ethos to professionally managed entities has created unique challenges for the governance of sport. This paper provides a contribution to the governance literature through the presentation of a situational case where a four-stage model, drawn from an action research approach, has been used for developing a board's strategic capability and subsequent improvement in organisational performance. Action research is founded on the premise that change and research are not mutually exclusive and that dual foci on improving practice and developing theory are possible (Coghlan & Brannick, 2001). Utilising a national sport organisation (NSO) in New Zealand the study developed and tested a structured model for improving board functioning and, specifically, strategic contribution. While the case to which the model has been applied is an NSO, the model and the subsequent reflections have value for non-profit as well as commercial entities particularly with regard to a greater understanding of the mechanisms associated with balancing the performance and conformance roles of the board.
Characterization of high-resolution aerosol mass spectra of primary organic aerosol emissions from Chinese cooking and biomass burning
Authors: He L.-Y. , Lin Y. , Huang X.-F. , Guo S. , Xue L. , Su Q. , Hu M. , Luan S.-J. , Zhang Y.-H.
Published: December 2010

Abstract. Aerosol mass spectrometry has proved to be a powerful tool to measure submicron particulate composition with high time resolution. Factor analysis of mass spectra (MS) collected worldwide by aerosol mass spectrometer (AMS) demonstrates that submicron organic aerosol (OA) is usually composed of several major components, such as oxygenated (OOA), hydrocarbon-like (HOA), biomass burning (BBOA), and other primary OA. In order to help interpretation of component MS from factor analysis of ambient OA datasets, AMS measurements of different primary sources is required for comparison. Such work, however, has been very scarce in the literature, especially for high resolution MS (HR-MS) measurements, which performs improved characterization by separating the ions of different elemental composition at each m/z in comparison with unit mass resolution MS (UMR-MS) measurements. In this study, primary emissions from four types of Chinese cooking (CC) and six types of biomass burning (BB) were simulated systematically and measured using an Aerodyne High-Resolution Time-of-Flight AMS (HR-ToF-AMS). The MS of the CC emissions show high similarity, with m/z 41 and m/z 55 being the highest signals; the MS of the BB emissions also show high similarity, with m/z 29 and m/z 43 being the highest signals. The MS difference between the CC and BB emissions is much bigger than that between different CC (or BB) types, especially for the HR-MS. The O/C ratio of OA ranges from 0.08 to 0.13 for the CC emissions and from 0.18 to 0.26 for the BB emissions. The UMR ions of m/z 43, m/z 44, m/z 57, and m/z 60, usually used as tracers in AMS measurements, were examined for their HR-MS characteristics in the CC and BB emissions. In addition, the MS of the CC and BB emissions are also compared with component MS from factor analysis of ambient OA datasets observed in China, as well as with other AMS measurements of primary sources in the literature. The MS signatures of cooking and biomass burning emissions revealed in this study can be used as important reference for factor analysis of ambient OA datasets, especially for the relevant studies in East Asia.
Robust extraction of baseline signal of atmospheric trace species using local regression
Authors: Ruckstuhl A. F. , Henne S. , Reimann S. , Steinbacher M. , Buchmann B. , Hueglin C.
Published: December 2010

Abstract. The identification of atmospheric trace species measurements that are representative of well-mixed background air masses is required for monitoring atmospheric composition change at background sites. We present a statistical method based on robust local regression that is well suited for the selection of background measurements and the estimation of associated baseline curves. The bootstrap technique is applied to calculate the uncertainty in the resulting baseline curve. The non-parametric nature of the proposed approach makes it more flexible than other commonly used statistical data filtering methods. Application to carbon monoxide (CO) measured from 1996 to 2009 at the high alpine site Jungfraujoch (Switzerland, 3580 m a.s.l.) demonstrates the feasibility and usefulness of the proposed approach. The determined average annual change for the 1996 to 2009 period as estimated from filtered annual mean CO concentrations is −2.1 ± 1.3 ppb/yr. For comparison, the linear trend of unfiltered CO measurements at Jungfraujoch for this time period is −2.9 ± 1.5 ppb/yr.
Controls over aboveground forest carbon density on Barro Colorado Island, Panama
Authors: Mascaro J. , Asner G. P. , Muller-Landau H. C. , van Breugel M. , Hall J. , Dahlin K.
Published: December 2010

Abstract. Despite the importance of tropical forests to the global carbon cycle, ecological controls over landscape-level variation in live aboveground carbon density (ACD) in tropical forests are poorly understood. Here, we conducted a spatially comprehensive analysis of ACD variation for a mainland tropical forest – Barro Colorado Island, Panama (BCI) – and tested site factors that may control such variation. We mapped ACD over 98% of BCI (~1500 ha) using airborne Light Detection and Ranging (LiDAR), which was well-correlated with ground-based measurements of ACD in Panamanian forests of various ages (r2 = 0.77, RMSE = 29 Mg C ha−1, P < 0.0001). We used multiple regression to examine controls over LiDAR-derived ACD, including slope angle, bedrock, soil texture, and forest age. Collectively, these variables explained 14% of the variation in ACD at 30-m resolution, and explained 33% at 100-m resolution. At all resolutions, slope (linked to underlying bedrock variation) was the strongest driving factor; standing carbon stocks were generally higher on steeper slopes, where erosion rates tend to exceed weathering rates, compared to gentle slopes, where weathering in place produces deep, oxic soils. This result suggests that physiography may be more important in controlling ACD variation in Neotropical forests than currently thought. Although BCI has been largely undisturbed by humans for a century, past land-use over approximately half of the island still influences ACD variation, with younger forests (80–130 years old) averaging ~15% less carbon storage than old-growth forests (>400 years old). If other regions of relatively old tropical secondary forests also store less carbon aboveground than primary forests, the effects on the global carbon cycle could be substantial and difficult to detect with satellite monitoring.
Interannual variations of the terrestrial water storage in the Lower Ob' Basin from a multisatellite approach
Authors: Frappart F. , Papa F. , Güntner A. , Werth S. , Ramillien G. , Prigent C. , Rossow W. B. , Bonnet M.-P.
Published: December 2010

Abstract. Temporal variations of surface water volume over inundated areas of the Lower Ob' Basin in Siberia, one of the largest contributor of freshwater to the Arctic Ocean, are estimated using combined observations from a multisatellite inundation dataset and water levels over rivers and floodplains derived from the TOPEX/POSEIDON (T/P) radar altimetry. We computed time-series of monthly maps of surface water volume over the common period of available T/P and multisatellite data (1993–2004). The results exhibit interannual variabilities similar to precipitation estimates and river discharge observations. This study also presents monthly estimates of groundwater and permafrost mass anomalies during 2003–2004 based on a synergistic analysis of multisatellite observations and hydrological models. Water stored in the soil is isolated from the total water storage measured by GRACE when removing the contributions of both the surface reservoir, derived from satellite imagery and radar altimetry, and the snow estimated by inversion of GRACE measurements. The time variations of groundwater and permafrost are then obtained when removing the water content of the root zone reservoir simulated by hydrological models.
Selective Artificial Receptors Based on Micropatterned Surface‐Imprinted Polymers for Label‐Free Detection of Proteins by SPR Imaging
Authors: Lautner Gergely , Kaev Jevgeni , Reut Jekaterina , Öpik Andres , Rappich Jörg , Syritski Vitali , Gyurcsányi Róbert E.
Published: December 2010

A novel concept to generate micropatterned surface‐imprinted polymers (SIPs) for protein recognition by using standard photolithographic technology is introduced. Avidin‐imprinted poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) conducting polymer microbands are prepared directly on surface plasmon resonance (SPR) chips, which enable convenient label‐free monitoring of the binding events. The novel surface‐imprinted microstructures bind avidin, the template protein, with dissociation constants in the submicromolar range (125 nM). The SIPs have an avidin binding capacity approximately one order of magnitude higher than the corresponding nonimprinted polymers and are able to discriminate among functional homologues of avidin, i.e., neutravidin, extravidin, and streptavidin.
Adrenarche in comparative perspective
Authors: Campbell Benjamin
Published: December 2010

Objectives: To addresses the hypothesis that human adrenarche is associated with extended juvenile brain development by comparing the timing of adrenal androgen production, brain development and lactation in a larger comparative mammalian context.

Methods: Findings from published literature are used to compare the developmental timing of adrenal androgens, brain glucose utilization and lactation in rats, rhesus macaques and humans.

Results: Comparison of the timing of androstenedione and progesterone production with developmental patterns of cortical glucose utilization and the timing of lactation in laboratory rats suggest that the rise and fall of adrenal hormone production centered on weaning plays a role in synaptogenesis during lactation as well as post weaning synaptic pruning. Comparison of the timing of cortical glucose utilization, DHEAS production and weaning in rhesus macaques also suggests that postnatally elevated levels of DHEAS may be related to patterns of synaptic formation and pruning centered on weaning. In contrast among humans, peak cortical glucose utilization occurs well after weaning and the rise in adrenal androgen production coincides with declining cortical glucose utilization with the onset of the juvenile stage.

Conclusions: Compared to rats and macaque, in humans the energetic demands of brain development and increased production of adrenal androgens are divorced from the timing of lactation, while the timing of adrenarche and brain development are still associated. Thus the neuroprotective effects of DHEAS may protect synaptic plasticity in metabolically active parts of the brain starting approximately at the age of 7, promoting prolonged development of the human prefrontal cortex. Am. J. Hum. Biol., 2011. © 2010 Wiley‐Liss, Inc.
Comparative genetic approaches to the evolution of human brain and behavior
Authors: Vallender Eric J.
Published: December 2010

With advances in genomic technologies, the amount of genetic data available to scientists today is vast. Genomes are now available or planned for 14 different primate species and complete resequencing of numerous human individuals from numerous populations is underway. Moreover, high‐throughput deep sequencing is quickly making whole genome efforts within the reach of single laboratories allowing for unprecedented studies. Comparative genetic approaches to the identification of the underlying basis of human brain, behavior, and cognitive ability are moving to the forefront. Two approaches predominate: inter‐species divergence comparisons and intra‐species polymorphism studies. These methodological differences are useful for different time scales of evolution and necessarily focus on different evolutionary events in the history of primate and hominin evolution. Inter‐species divergence is more useful in studying large scale primate, or hominoid, evolution whereas intra‐species polymorphism can be more illuminating of recent hominin evolution. These differences in methodological utility also extend to studies of differing genetic substrates; current divergence studies focus primarily on protein evolution whereas polymorphism studies are substrate ambivalent. Some of the issues inherent in these studies can be ameliorated by current sequencing capabilities whereas others remain intractable. New avenues are also being opened that allow for the incorporation of novel substrates and approaches. In the post‐genomic era, the study of human evolution, specifically as it relates to the brain, is becoming more complete focusing increasingly on the totality of the system and better conceptualizing the entirety of the genetic changes that have lead to the human phenotype today. Am. J. Hum. Biol., 2011. © 2010 Wiley‐Liss, Inc.
Effect of boric acid and heat treatment for the formation of poly(vinyl alcohol)/iodine complex films iodinated at solution before casting
Authors: Shin Eun Joo , Lyoo Won Seok , Lee Yang Hun
Published: December 2010

This study examined the role of boric acid and the effect of heat treatment on PVA‐iodine polarizing films prepared in the solution state before casting (IBC) of PVA/iodine/boric acid films. The films were prepared by casting aqueous solutions of 10 wt % poly(vinyl alcohol) (PVA) containing boric acid with 0, 0.1, 0.3, and 0.5 mol/l of I2/KI aqueous solution, and I2/KI(1 : 2) with 5 wt % of PVA. The effect of boric acid and heat treatment on the durability of the IBC PVA polarizing sheet films was investigated by UV–vis absorption spectroscopy. Boric acid was found to be essential for the complex formation in PVA/iodine solutions at relatively low I2/KI concentrations and high temperatures. The strength of the complex peak at ∼ 600 nm in UV–vis absorption spectra increased with increasing boric acid concentration. With increasing heating temperature over 90°C the intensity of the peak at 600 nm corresponding to the complex decreased due to the evaporation of I2 decomposed from I5−, but the peak at 355 nm corresponding to free I2·I3− was remained unchanged. From heat treatment at 150°C, the intensity of the peak at 600 nm decreased but the intensity of the complex peak (600 nm) of the sample with 0.5 mol/l boric acid was unaffected. The transmittance and degree of polarization for the films increased and decreased with increasing heat treatment time under heat and a humid atmosphere, respectively. However, this tendency decreased with increasing boric acid concentration and heat treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Women's experiential journey toward voluntary childlessness: An interpretative phenomenological analysis
Authors: Shaw Rachel Louise
Published: December 2010

Voluntary childlessness is a relatively novel yet growing phenomenon. This idiographic study explored three women's experiential journeys toward voluntary childlessness. Semi‐structured interviews were carried out and analysed using Interpretative Phenomenological Analysis. Themes identified were: Owning the choice to be childless, social expectations, and models of mothering. Despite defining ‘voluntary childlessness’ as an unequivocal decision, the women's experiential accounts revealed an intrinsic fluidity in their journeys toward childlessness. Factors including beliefs in equality, independence and career aspirations competed with constructs of mothering/motherhood, partnership and choice to create a complex tapestry of contributory factors in these women's childlessness. The findings question the notion of choice and particularly women's ownership of that choice. The journeys toward childlessness these women shared reveal a synthesis of agentic decision‐making, personal histories and challenging lifestyle choices bound up within an existential need to be a woman. More research is needed to determine the place of voluntary childlessness within society. Copyright © 2010 John Wiley & Sons, Ltd.