bluuebunny/crossref_metadata_2025 huggingface dataset:
An analogue of problem 26 of P. Turán
Authors: Shi Y. G.
Published: April 2009

Explicit formulas for Cotes numbers of the Gaussian Hermite quadrature formula based on the zeros of thenth Chebyshev polynomial of the second kind and their asymptotic behaviour asn→ ∞ are given. This provides an answer to an analogue of Problem 26 of Tur´n.
Non differentiable symmetric duality
Authors: Mond Bertram , Schechter Murray
Published: April 2009

In this paper we construct dual pairs of problems, of both the Wolfe and Mond-Weir types, in which the objective contains a a support function and is therefore not differentiable. A special case which appears repeatedly in the literature is that in which the support function is the square root of a positive semidefinite quadratic form. This and other special cases can be readily generated from our result.
A selection theorem for weak upper semi-continuous set-valued mappings
Authors: Moors Warren B.
Published: April 2009

Let Φ be a set-valued mapping from a Baire space T into non-empty closed subsets of a Banach space X, which is upper semi-continuous with respect to the weak topology on X. In this paper, we give a condition on T which is sufficient to ensure that Φ admits a selection which is norm continuous at each point of a dense and Gδ subset of T. We also derive a variation of James' characterisation of weak compactness, which we use in conjunction with our selection theorem, to deduce some differentiability results for continuous convex functions defined on dual Banach spaces.
Set covering number for a finite set
Authors: Chang H.-C. , Prabhu N.
Published: April 2009

Given a finite setSof cardinalityN, the minimum number ofj-subsets ofSneeded to cover all ther-subsets ofSis called the covering numberC(N, j, r). While Erdös and Hanani's conjecture thatwas proved by Rödl, no nontrivial upper bound forC(N, j, r) was known for finiteN. In this note we obtain a nontrivial upper bound by showing that for finiteN,
Homomorphisms of near-rings of continuous real-valued functions
Authors: Magill K.D.
Published: April 2009

For any topological near-ring (which is not a ring) whose additive group is the additive group of real numbers, we investigate the near-ring of all continuous functions, under the pointwise operations, from a compact Hausdorff space into that near-ring. Specifically, we determine all the homomorphisms from one such near-ring of functions to another and we show that within a rather extensive class of spaces, the endomorphism semigroup of the near-ring of functions completely determines the topological structure of the space.
Superconvergence analysis of flux computations for nonlinear problems
Authors: Chow S.-S. , Lazarov R.D.
Published: April 2009

In this paper we consider the error estimates for some boundary-flux calculation procedures applied to two-point semilinear and strongly nonlinear elliptic boundary value problems. The case of semilinear parabolic problems is also studied. We prove that the computed flux is superconvergent with second and third order of convergence for linear and quadratic elements respectively. Corresponding estimates for higher order elements may also be obtained by following the general line of argument.
Field theory for function fields of singular plane quartic curves
Authors: Miura Kei
Published: April 2009

We study the structure of function fields of plane quartic curves by using projections. Taking a point P ∈ ℙ2, we define the projection from a curve C to a line l with the centre P. This projection induces and extension field k (C)/k (ℙ1). By using this fact, we study the field extension k (C)/k (ℙ1) from a geometrical point of view. In this note, we take up quartic curves with singular points.
A simple proof of the sum formula
Authors: Verona A. , Verona M. E.
Published: April 2009

In this note we present a simple, short proof of the sum formula for subdifferentials of convex functions.
Power graphs and semigroups of matrices
Authors: Kelarev A. V. , Quinn S. J. , Smolíková R.
Published: April 2009

Matrices provide essential tools in many branches of mathematics, and matrix semigroups have applications in various areas. In this paper we give a complete description of all infinite matrix semigroups satisfying a certain combinatorial property defined in terms of power graphs.
Strong Gröbner bases for polynomials over a principal ideal ring
Authors: Norton Graham H. , Sǎlǎgean Ana
Published: April 2009

Gröbner bases have been generalised to polynomials over a commutative ring A in several ways. Here we focus on strong Gröbner bases, also known as D-bases. Several authors have shown that strong Gröbner bases can be effectively constructed over a principal ideal domain. We show that this extends to any principal ideal ring. We characterise Gröbner bases and strong Gröbner bases when A is a principal ideal ring. We also give algorithms for computing Gröbner bases and strong Gröbner bases which generalise known algorithms to principal ideal rings. In particular, we give an algorithm for computing a strong Gröbner basis over a finite-chain ring, for example a Galois ring.
Another control condition in an iterative method for nonexpansive mappings
Authors: Xu Hong-Kun
Published: April 2009

We prove the convergence of an iterative method to a fixed point of a nonexpansive mapping in a uniformly smooth Banach space. We are able to relax one of the control conditions of P.L. Lions (1977).
Parallel surfaces in the real special linear gorup SL (2,ℝ)
Authors: Belkhelfa Mohamed , Dillen Franki , Inoguchi Jun-Ichi
Published: April 2009

Dedicated to Professor Koichi Ogiue on his sixtieth birthday

We show that the only parallel surfaces in SL (2,ℝ) are rotational surfaces with constant mean curvature.
A remark on the derivative of the one-dimensional Hardy-Littlewood maximal function
Authors: Tanaka Hitoshi
Published: April 2009

Dedicated to Professor Kôzô Yabuta on the occasion of his 60th birthday

J. Kinnunen proved that of P > 1, d ≤ 1 and f is a function in the Sobolev space W1,P(Rd), then the first order weak partial derivatives of the Hardy-Littlewood maximal function ℳf belong to LP(Rd). We shall show that, when d = 1, Kinnunen's result can be extended to the case where P = 1.
Enriched accessible categories
Authors: Borceux Francis , Quinteriro Carmen
Published: April 2009

We consider category theory enriched in a locally finitely presentable symmetric monoidal closed category ν. We define the ν-filtered colimits as those colimits weighted by a ν-flat presheaf and consider the corresponding notion of ν-accessible category. We prove that ν-accessible categories coincide with the categories of ν-flat presheaves and also with the categories of ν-points of the categories of ν-presheaves. Moreover, the ν-locally finitely presentable categories are exactly the ν-cocomplete finitely accessible ones. To prove this last result, we show that the Cauchy completion of a small ν-category Cis equivalent to the category of ν-finitely presentable ν-flat presheaves on C.
A notion of limit for enriched categories
Authors: Borceux Francis , Kelly G.M.
Published: April 2009

For a V-category B, where V is a symmetric monoidal closed category, various limit-like notions have been recognized: ordinary limits (in the underlying category B0 ) preserved by the V-valued representable functors; cotensor products; ends; pointwise Kan extensions. It has further been recognized that, to be called complete, B should admit all of these; for which it suffices to demand the first two. Hitherto, however, there has been no single limit-notion of which all these are special cases, and particular instances of which may exist even when B is not complete or even cotensored. In consequence it has not been possible even to state, say, the representability criterion for a V-functor T: B → V, or even to define, say, pointwise Kan extensions into B, except for cotensored B. (It is somewhat as if, for ordinary categories, we had the notions of product and equalizer, but lacked that of general limit, and could not discuss pullbacks in the absence of products.) In this paper we provide such a general limit-notion for V-categories.
Autoclinisms and automorphisms of finite groups
Authors: Reimers Ratje , Tappe Jürgen
Published: April 2009

Let Γ be a family of isoclinic finite groups, and let acl(Γ) be the group of autoclinisms of Γ. In this paper we prove the following formula:

where the sum is taken over a complete system of stem groupsSin Γ. This result is due to P. Hall, who outlined a proof in his paper, “On groups of automorphisms” (J. reine angew. Math). 182 (1940), 194–204, using presentations, whereas in this paper we consider stem groups in terms of central extensions.
On certain non-archimedean functions analogous to complex analytic functions
Authors: Mahler Kurt
Published: April 2009

LetQpandKbe the rationalp–adic field and an algebraic extension ofQpof finite degree, respectively, and letIandIkbe the subsets ofQpand ofKconsisting of thep–adic integers of these fields.

It is known that the continuous functionsf:I→Qpcan be written as

where this series converges uniformly onI, and that such continuous functions need not be differentiable at any point. We here study continuous functionsF:IK→Kwhich for allXonIKare the sum of a uniformly convergent series

It is proved that such functionsF(X)have at every point ofIKderivatives of all orders. In the special case whenKis totally ramified, they cannot in general be developed into power series that converge everywhere onIK, but this is possible whenKis not totally ramified.
Existence theory for the complex nonlinear complementarity problem
Authors: Parida J. , Sahoo B.
Published: April 2009

The main result in this paper is an existence theorem for the following complex nonlinear complementarity problem: find z such that

where S is a polyhedral cone in Cn, S* the polar cone, and g is a mapping from Cn into itself. It is shown that the above problem has a unique solution if the mapping g is continuous and strongly monotone on the polyhedral cone S.
Entire functions having asymptotic functions
Authors: Fenton P.C.
Published: April 2009

It is shown that an entire function having k distinct entire asymptotic functions of order less than ¼ is of lower order ½k, mean type at least; further that if f is of lower order ½k, mean type, then its order is ½k.
An inverse mapping theorem for Sobolev chains and its application
Authors: Nghê Truong Công
Published: April 2009

The author combines the methods used by Yamamuro and Omori to define a differentiation in Sobolev chains and obtain an Inverse Mapping Theorem. He then uses this theorem to give a new proof for a result of Sunada on the local finite-dimensionality of the solution space of a non-linear elliptic differential operator with smooth coefficients.
Quadratic systems with a degenerate critical point
Authors: Coppel W. A.
Published: April 2009

It is shown that a quadratic system with a degenerate critical point has at most one limit cycle.
On a theorem of Sobczyk
Authors: Moltó Aníbal
Published: April 2009

In this paper the result of Sobczyk about complemented copies of c0 is extended to a class of Banach spaces X such that the unit ball of their dual endowed with the weak* topology has a certain topological property satisfied by every Corson-compact space. By means of a simple example it is shown that if Corson-compact is replaced by Rosenthal-compact, this extension does not hold. This example gives an easy proof of a result of Phillips and an easy solution to a question of Sobczyk about the existence of a Banach space E, c0 ⊂ E ⊂ l∞, such that E is not complemented in l∞ and c0 is not complemented in E. Assuming the continuum hypothesis, it is proved that there exists a Rosenthal-compact space K such that C(K) has no projectional resolution of the identity.
On improper integrals of products of logarithmic, power and Bessel functions
Authors: Chaudhry M. Aslam , Ahmad M.
Published: April 2009

In this paper we have evaluated the integral . A new integral representation of the Euler constant is shown. Some special cases of the result are discussed and an open problem is posed.
Canonical point mappings in
Authors: Abdulhadi Zayid , Hengartner Walter
Published: April 2009

We give a complete characterisation of univalent logharmonic mappings from the domain D of such that has countable many components onto where pj is a singleton in C.
Bent polynomials over finite fields
Authors: Coulter Robert S. , Matthews Rex W.
Published: April 2009

The definition of bent is redefined for any finite field. Our main result is a complete description of the relationship between bent polynomials and perfect non-linear functions over finite fields: we show they are equivalent. This result shows that bent polynomials can also be viewed as the generalisation to several variables of the class of polynomials known as planar polynomials. An explicit method for obtaining large sets of not necessarily distinct maximal orthogonal systems using bent polynomials is given and we end with a short discussion on the existence of bent polynomials over finite fields.
Farthest points and monotone operators
Authors: Westphal U. , Schwartz T.
Published: April 2009

We apply the theory of monotone operators to study farthest points in closed bounded subsets of real Banach spaces. This new approach reveals the intimate connection between the farthest point mapping and the subdifferential of the farthest distance function. Moreover, we prove that a typical exception set in the Baire category sense is pathwise connected. Stronger results are obtained in Hilbert spaces.
A stable finite difference ansatz for higher order differentiation of non-exact data
Authors: Anderssen Bob , de Hoog Frank , Hegland Markus
Published: April 2009

If standard central difference formulas are used to compute second or third order derivatives from measured data even quite precise data can lead to totally unusable results due to the basic instability of the differentiation process. Here an averaging procedure is presented and analysed which allows the stable computation of low order derivatives from measured data. The new method first averages the data, then samples the averages and finally applies standard difference formulas. The size of the averaging set acts like a regularisation parameter and has to be chosen as a function of the grid size h.
Nilpotent quotients of fundamental groups of special 3-manifolds with boundary
Authors: Putinar Gabriela
Published: April 2009

We use a Betti number estimate of Freedman-Hain-Teichner to show that the maximal torsion-free nilpotent quotient of the fundamental group of a 3-manifold with boundary is eitherZorZ⊕Z. In particular we reobtain the Evans-Moser classification of 3-manifolds with boundary which have nilpotent fundamental groups.
Subnormality conditions in non-torsion groups
Authors: Kappe Luise-Charlotte , Traustason Gunnar
Published: April 2009

According to results of Heineken and Stadelmann, a non-torsion group is a 2-Baer group if and only if it is 2-Engel, and it has all subgroups 2-subnormal if and only if it is nilpotent of class 2. We extend some of these results to values ofngreater than 2. Any non-torsion group which is ann-Baer group is ann-Engel group. The converse holds forn= 3, and for allnin the case of metabelian groups. A non-torsion group without involutions having all subgroups 3-subnormal has nilpotency class 4, and this bound is sharp.
Homotopy invariant results on complete gauge spaces
Authors: Agarwal Ravi P. , Cho Yeol Je , O'Regan Donal
Published: April 2009

A fixed point theorem and two homotopy invariant results are presented for generalized contractive maps defined on complete gauge spaces.
Covering groups with subgroups
Authors: Bryce R.A. , Fedri V. , Serena L.
Published: April 2009

A group iscoveredby a collection of subgroups if it is the union of the collection. The intersection of an irredundant cover ofnsubgroups is known to have index bounded by a function ofn, though in general the precise bound is not known. Here we confirm a claim of Tompkinson that the correct bound is 16 whennis 5. The proof depends on determining all the ‘minimal’ groups with an irredundant cover of five maximal subgroups.
On regularity preservation in a semigroup
Authors: Hickey J.B.
Published: April 2009

We consider certain subsets of a semigroupS, defined mainly by conditions involving regularity preservation. In particular, theregular baseB(S) ofSmay be regarded as a generalisation of the zero ideal in a semigroup with zero; if it non-empty thenSisE-inversive. The other subsets considered are related in a natural way either to B(S) or to the set RP(S) of regularity-preserving elements inS. In a regular semigroup (equipped with the Hartwig-Nambooripad order) each of these subsets contains either minimal elements only or maximal elements only. The relationships between the subsets are discussed, and some characterisations of completely simple semigroups are obtained.
Baer-Levi semigroups of partial transformations
Authors: Pinto Fernanda A. , Sullivan R.P.
Published: April 2009

Let X be an infinite set and suppose א0 ≤ q ≤ |X|. The Baer-Levi semigroup on X is the set of all injective ‘total’ transformations α: X → X such that |X\Xα| = q. It is known to be a right simple, right cancellative semigroup without idempotents, its automorphisms are “inner”, and some of its congruences are restrictions of Malcev congruences on I(X), the symmetric inverse semigroup on X. Here we consider algebraic properties of the semigroup consisting of all injective ‘partial’ transformations α of X such that |X\Xα| = q: in particular, we descried the ideals and Green's relations of it and some of its subsemigroups.
Minimal surfaces in 3-dimensional solvable Lie groups II
Authors: Inoguchi Jun-Ichi
Published: April 2009

An integral representation formula in terms of the normal Gauss map for minimal surfaces in 3-dimensional solvable Lie groups with left invariant metric is obtained.
On additivity of centralisers
Authors: Eremita Daniel , Ilišević Dijana
Published: April 2009

Let R be a ring and let M be a bimodule over R. We consider the question of when a map φ: R → M such that φ(ab) = φ(a)b for all a, b ∈ R is additive.
Commutator rings
Authors: Mesyan Zachary
Published: April 2009

A ring is called a commutator ring if every element is a sum of additive commutators. In this note we give examples of such rings. In particular, we show that given any ring R, a right R-module N, and a nonempty set Ω, EndR(⌖ΩN) and EndR(ΠΩN) are commutator rings if and only if either Ω is infinite or EndR(N) is itself a commutator ring. We also prove that over any ring, a matrix having trace zero can be expressed as a sum of two commutators.
On the interpolation of bivariate polynomials related to the Diffie-Hellman mapping
Authors: Kiltz Eike , Winterhof Arne
Published: April 2009

We obtain lower bounds on degree and weight of bivariate polynomials representing the Diffie-Hellman mapping for finite fields and the Diffie-Hellman mapping for elliptic curves over finite fields. This complements and improves several earlier results. We also consider some closely related bivariate mappings called P-Diffie-Hellman mappings introduced by the first author. We show that the existence of a low degree polynomial representing a P-Diffie-Hellman mapping would lead to an efficient algorithm for solving the Diffie-Hellman problem. Motivated by this result we prove lower bounds on weight and degree of such interpolation polynomials, as well.
The asymptotic growth of integer solutions to the Rosenberger equations
Authors: Baragar Arthur , Umeda Kensaku
Published: April 2009

Zagier showed that the number of integer solutions to the Markoff equation with components bounded by T grows asymptotically like C(log T)2, where C is explicity computable. Rosenberger showed that there are only a finite number of equations ax2 + by2 + cz2 = dxyz with a, b, and c dividing d, and for which the equation admits an infinite number of integer solutions. In this paper, we generalise Zagier's techniques so that they may be applied to the Rosenberger equations. We also apply these techniques to the equations ax2 + by2 + cz2 = dxyz + 1.
Unbounded principal eigenfunctions and the logistic equation onRN
Authors: Dong Wei , Du Yihong
Published: April 2009

We consider the logistic equation − Δu=a(x)u−b(x)upon all ofRNwith possibly unbounded coefficients near infinity. We show that under suitable growth conditions of the coefficients, the behaviour of the positive solutions of the logistic equation can be largely determined. We also show that certain linear eigenvalue problems on all ofRNhave principal eigenfunctions that become unbounded near infinity at an exponential rate. Using these results, we finally show that the logistic equation has a unique positive solution under suitable growth restrictions for its coefficients.
n-th derivative characterisations, mean growth of derivatives and F(p, q, s)
Authors: Rättyä J.
Published: April 2009

Various n-th derivative characterisations involving different kinds of oscillations of F(p,q,s) functions are established, and the mean growth of derivatives of F(p,q,s) functions is considered. Moreover, inclusion relations between certain analytic function spaces are discussed.
Existence and multiplicity results for quasilinear elliptic equations
Authors: Dong Wei
Published: April 2009

The goal of this paper is to study the multiplicity of positive solutions of a class of quasilinear elliptic equations. Based on the mountain pass theorems and sub-and supersolutions argument forp-Laplacian operators, under suitable conditions on nonlinearityf(x, s), we show the follwing problem:, where Ω is a bounded open subset ofRN, N≥ 2, with smooth boundary, λ is a positive parameter and ∆pis thep-Laplacian operator withp> 1, possesses at least two positive solutions for large λ.
On a system of nonlinear partial differential equations
Authors: Bonfoh A. Sanih
Published: April 2009

We consider a generalised Cahn-Hilliard system with elasticity based on constitutives laws proposed by Gurtin, with a logarithmic free energy. We obtain some results on the existence and uniqueness of solutions.
On Arithmetic Functions of Finite Groups
Authors: Das Ashish Kumar
Published: April 2009

The object of this paper is to develop and study group theoretic analogues of some of the fundamental concepts and results of arithmetic functions of positive integers.
Stability of contact metric manifolds and unit vector fields of minimum energy
Authors: Perrone D. , Vergori L.
Published: April 2009

In this paper we obtain criteria of stability for ηEinstein k-contact manifolds, for Sasakian manifolds of constant ϕ-sectional curvature and for 3-dimensional Sasakian manifolds. Moreover, we show that a stable compact Einstein contact metric manifold M is Sasakian if and only if the Reeb vector field ξ minimises the energy functional. In particular, the Reeb vector field of a Sasakian manifold M of constant ϕ-holomorphic sectional curvature +1 minimises the energy functional if and only if M is not simply connected.
On the Powers of Some Transcendental Numbers
Authors: Dubickas Artūras
Published: April 2009

We construct a transcendental number α whose powers αn!,n= 1, 2, 3,…, modulo 1 are everywhere dense in the interval [0, 1]. Similarly, for any sequence of positive numbers δ = (δn)∞n=1, we find a transcendental number α = α(δ) such that the inequality {αn} < δnholds for infinitely manyn∈ N, no matter how fast the sequence δ converges to zero. Finally, for any sequence of real numbers (rn)∞n=1and any sequence of positive numbers (δn)∞n=1, we construct an increasing sequence of positive integers (qn)∞n=1and a number α > 1 such that ‖αqn– τn‖ < δnfor each n ≥ 1.
Certain inequalities for submanifolds in (K,μ)-contact space forms
Authors: Arslan Kadri , Ezentas Ridvan , Mihai Ion , Murathan Cengizhan , Özgür Cihan
Published: April 2009

Chen (1999) established a sharp relationship between the Ricci curvature and the squared mean curvature for a submanifold in a Riemanian space form with arbitrary codimension. Matsumoto (to appear) dealt with similar problems for sub-manifolds in complex space forms.

In this article we obtain sharp relationships between the Ricci curvature and the squared mean curvature for submanifolds in (K, μ)-contact space forms.
On slant curves in Sasakian 3-manifolds
Authors: Cho Jong Taek , Inoguchi Jun-Ichi , Lee Ji-eun
Published: April 2009

A classical theorem by Lancret says that a curve in Euclidean 3-space is of constant slope if and only if its ratio of curvature and torsion is constant. In this paper we study Lancret type problems for curves in Sasakian 3-manifolds.
A note on a discrete analytic function
Authors: Harman C.J.
Published: April 2009

An unsolved problem in discrete analytic function theory has been to find a suitable analogue of the function . An analogue z(α), of the function zα, is found here for discrete analytic functions of the first kind (or monodiffric functions). This function resolves a conjecture of Isaacs in the negative, and at the same time it introduces multi-valued functions into the discrete analytic theory.
Matrix quadratic equations
Authors: Coppel W.A.
Published: April 2009

Matrix quadratic equations have found the most diverse applications. The present article gives a connected account of their theory, and contains some new results and new proofs of known results.
Varieties of topological groups III
Authors: Morris Sidney A.
Published: April 2009

This paper continues the invèstigation of varieties of topological groups. It is shown that the family of all varieties of topological groups with any given underlying algebraic variety is a class and not a set. In fact the family of all β-varieties with any given underlying algebraic variety is a class and not a set. A variety generated by a family of topological groups of bounded cardinal is not a full variety.

The varieties V(R) and V(T) generated by the additive group of reals and the circle group respectively each with its usual topology are examined. In particular it is shown that a locally compact Hausdorff abelian group is in V(T) if and only if it is compact. Thus V(R) properly contains V(T).

It is proved that any free topological group of a non-indiscrete variety is disconnected. Finally, some comments are made on topologies on free groups.
An asymptotic result for a subcritical branching process with immigration
Authors: Pakes A. G.
Published: April 2009

Under weak hypotheses, the geometric ergodicity of the states of a subcritical branching process with immigration is demonstrated by obtaining an asymptotic representation of the transition probabilities.
On the sharpness of a limiting case of the Sobolev imbedding theorem
Authors: Hempel J. A. , Morris G. R. , Trudinger N. S.
Published: April 2009

A refinement of the Sobolev imbedding theorem, due to Trudinger, is shown to be optimal in a natural sense.
On finite groups admitting automorphisms with nilpotent fixed-point group
Authors: Ward J.N.
Published: April 2009

Let p denote a prime, G a finite p′-group and A an elementary atelian group of operators on G. Suppose that A has order p3 and that if w ∈ A# then CG(w) is nilpotent. It is proved that G is nilpotent.
Risk of damage to tomato crops by the generalist zoophytophagous predatorNesidiocoris tenuis(Reuter) (Hemiptera: Miridae)
Authors: Arnó J. , Castañé C. , Riudavets J. , Gabarra R.
Published: April 2009

Nesidiocoris tenuis(Reuter) (Hem. Miridae) is a native zoophytophagous predator of the Mediterranean region, and its populations colonize tomato crops when they are not heavily treated with insecticides. This generalist predator has a high capacity for controlling insect pests, and it is currently commercially produced and released in some areas to controlBemisia tabaci(Gennadius) (Hem. Aleyrodidae). However, its status as a pest and/or as beneficial is controversial. Therefore, the aim of this study was to evaluate the risk of damage to tomatoes in extreme conditions of prey scarcity, as well as high predator populations. Three predator densities were tested in a greenhouse cage experiment during a summer tomato crop. The crop did not display any negative effect caused by the predators during the first six weeks of interaction, independently of the density released. However, subsequently, the effect was dramatic, both on the vegetative growth of the plant and on the production of fruits. The reduction in vegetative growth was located at truss eight and it was expressed mainly by a lower number of leaves and a shorter length of the shoot above the truss. There was a significant reduction of yield with a lower number of fruits collected and a smaller mean weight, although this was not observable until truss seven. It seems that feeding on the plant by this mirid bug competed with the vegetative growth and fruiting processes of the plant in the extreme conditions of prey shortage maintained in our experiment.
Host use and crop impacts of Oribius Marshall species (Coleoptera: Curculionidae) in Eastern Highlands Province, Papua New Guinea
Authors: Wesis P. , Niangu B. , Ero M. , Masamdu R. , Autai M. , Elmouttie D. , Clarke A. R.
Published: April 2009

Oribius species are small flightless weevils endemic to the island of New Guinea and far northern Cape York, Australia. The adults feed externally on leaves, developing fruit and green bark, but their impact as pests and general host use patterns are poorly known. Working in Eastern Highlands Province, Papua New Guinea, we carried out structured host use surveys, farmer surveys, shade-house growth trials and on-farm and on-station impact trials to: (i) estimate the host range of the local Oribius species; (ii) understand adult daily activity patterns; (iii) elucidate feeding habits of the soil dwelling larvae; and (iv) quantify the impacts of adult feeding damage. Oribius inimicus and O. destructor accounted for nearly all the Oribius species encountered locally, of these two O. inimicus was the most abundant. Weevils were collected from 31 of 33 plants surveyed in the Aiyura Valley, and a combination of farmer interviews and literature records provided evidence for the beetles being pestiferous on 43 crops currently or previously grown in the Highlands. Adult weevils had a distinct diurnal pattern of being in the upper plant canopy early in the morning and, to a lesser extent, again late in the afternoon. For the remainder of the day, beetles resided within the canopy, or possibly off the plant. Movement of adults between plants appeared frequent. Pot trials confirmed the larvae are root feeders. Quantified impact studies showed that the weevils are damaging to a range of vegetable and orchard crops (broccoli, capsicum, celery, French bean, Irish potato, lettuce, orange and strawberry), causing average yield losses of around 30–40%, but up to 100% on citrus. Oribius weevils pose a significant and, apparently, growing problem for Highland's agriculture.
SOUTH AFRICAN TERRITORIAL SEGREGATION: NEW DATA ON AFRICAN FARM PURCHASES, 1913–1936
Authors: FEINBERG HARVEY M. , HORN ANDRÉ
Published: April 2009

By using new sources and a complementary historical and geo-analytical approach, this article illustrates that the Natives Land Act (no. 27 of 1913) failed to stop Africans from buying land. New evidence demonstrates that African land ownership outside the reserves in the Transvaal actually increased after 1913. This evidence leads to a deeper questioning of the extent to which the South African government was able to impose rural territorial segregation by 1936 and reveals the limits of white power in the early Union period.
Does Corporate Governance Matter to Bondholders?
Authors: Klock Mark S. , Mansi Sattar A. , Maxwell William F.
Published: April 2009

We examine the relation between the cost of debt financing and a governance index that contains various antitakeover and shareholder protection provisions. Using firm-level data from the Investors Research Responsibility Center for the period 1990–2000, we find that antitakeover governance provisions lower the cost of debt financing. Segmenting the data into firms with the strongest management rights (strongest antitakeover provisions) and firms with the strongest shareholder rights (weakest antitakeover provisions), we find that strong antitakeover provisions are associated with a lower cost of debt financing while weak antitakeover provisions are associated with a higher cost of debt financing, with a difference of about 34 basis points between the two groups. Overall, the results suggest that antitakeover governance provisions, although not beneficial to stockholders, are viewed favorably in the bond market.
Dividend Smoothing and Debt Ratings
Authors: Aivazian Varouj A. , Booth Laurence , Cleary Sean
Published: April 2009

We find that firms that regularly access public debt (bond) markets are more likely to pay a dividend and subsequently follow a dividend smoothing policy than firms that rely exclusively on private (bank) debt. In particular, firms with bond ratings follow a traditional Lintner (1956) style dividend smoothing policy, where the influence of the prior dividend payment is very strong and the current dividend is relatively insensitive to current earnings. In contrast, firms without bond ratings flow through more of their earnings as dividends and display very little dividend smoothing behavior. In effect, they seem to follow a residual dividend policy.
Chapter 11: Duration, Outcome, and Post-Reorganization Performance
Authors: Denis Diane K. , Rodgers Kimberly J.
Published: April 2009

We find that among firms that file Chapter 11 those that are smaller have better operating performance, and are in higher operating margin industries spend less time in Chapter 11. Firms are more likely to emerge as going concerns and to achieve positive post reorganization profitability if they significantly reduce assets and liabilities while in Chapter 11. Higher pre-bankruptcy industry-adjusted operating margins and improvements in margin are associated with post-reorganization profitability but do not impact the decision to reorganize. These results reveal characteristics and actions associated with successful reorganizations and, furthermore, suggest that Chapter 11 allows promising firms to successfully reorganize.
Horses and Rabbits? Trade-Off Theory and Optimal Capital Structure
Authors: Ju Nengjiu , Parrino Robert , Poteshman Allen M. , Weisbach Michael S.
Published: April 2009

This paper examines optimal capital structure choice using a dynamic capital structure model that is calibrated to reflect actual firm characteristics. The model uses contingent claim methods to value interest tax shields, allows for reorganization in bankruptcy, and maintains a long-run target debt to total capital ratio by refinancing maturing debt. Using this model, we calculate optimal capital structures in a realistic representation of the traditional trade-off model. In contrast to previous research, the calculated optimal capital structures do not imply that firms tend to use too little leverage in practice. We also estimate the costs borne by a firm whose capital structure deviates from its optimal target debt to total capital ratio. The costs of moderate deviations are relatively small, suggesting that a policy of adjusting leverage infrequently is likely to be reasonable for many firms.
Learning with Information Capacity Constraints
Authors: Peng Lin
Published: April 2009

Motivated by the fact that investors have limited time and attention to process information, this paper provides a continuous-time equilibrium model to analyze the effects of a capacity constraint in the learning process of a representative investor, who optimally allocates her information capacity across multiple sources of uncertainty. Consequently, the cross-sectional structure of information and the resulting asset price dynamics are determined endogenously. The model provides implications on both consumption behavior and the cross-sectional differences in price informativeness in terms of supply of information, speed of price adjustments to fundamental shocks, and price reactions to firm disclosures.
Multifactor Evaluation of Style Rotation
Authors: Wang Kevin Q.
Published: April 2009

A growing literature documents that various strategies of rotating across equity styles generate significant returns. However, the conventional risk adjustment regression is problematic in evaluating the gains from style rotation. I propose a weight-based multifactor risk adjustment approach as a solution. When interpreted as a performance attribution procedure, this approach extends Sharpe's (1992) classic method by emphasizing factor loading rotation. I use a logit-based timing strategy to show that the conventional procedure produces misleading results and the new method leads to the opposite conclusion.
IPO Pricing with Bookbuilding and a When-Issued Market
Authors: Aussenegg Wolfgang , Pichler Pegaret , Stomper Alex
Published: April 2009

We study IPO pricing in Germany to determine whether when-issued trading provides information that is useful for setting IPO offer prices, and whether such trading supplants bookbuilding as a source of information. We find that when-issued trading reveals relevant information for pricing IPOs, and that, once when-issued trading has begun, bookbuilding is not a source of costly information for pricing. But bookbuilding does not appear to be fully supplanted as a source of pricing information. We find evidence consistent with bookbuilding being used to gather information prior to the onset of when-issued trading.
Order Consolidation, Price Efficiency, and Extreme Liquidity Shocks
Authors: Barclay Michael J. , Hendershott Terrence , Jones Charles M.
Published: April 2009

We show that the consolidation of orders is important for producing efficient prices, especially during times of high liquidity demand. The NYSE's centralized opening call market performs better than Nasdaq's decentralized opening process on typical trading days. The NYSE is much better than Nasdaq on witching days when index arbitrage activity subjects S&P 500 stocks to large, predictable, and mostly informationlessorder flow around quarterly futures contract expirations. Nasdaq opening price efficiency improves to NYSE levels once Nasdaq initiates a consolidated opening call in November 2004, but prices on the decentralized Nasdaq remain less efficient at other times of day.
Cookie Cutter vs. Character: The Micro Structure of Small Business Lending by Large and Small Banks
Authors: Cole Rebel A. , Goldberg Lawrence G. , White Lawrence J.
Published: April 2009

The informational opacity of small businesses makes them an interesting area for the study of banks' lending practices and procedures. We use data from a survey of small businesses to analyze the micro level differences in the loan approval processes of large and small banks. We provide evidence that large banks ($1 billion or more in assets) employ standard criteria obtained from financial statements in the loan decision process, whereas small banks rely to a greater extent on information about the character of the borrower. These cookie-cutter and character approaches are compatible with the incentives and environments facing large and small banks.
The Impact of Mutual Fund Family Membership on Investor Risk
Authors: Elton Edwin J. , Gruber Martin J. , Green T. Clifton
Published: April 2009

Many investors confine their mutual fund holdings to a single fund family either for simplicity or through restrictions placed by their retirement savings plan. We find evidence that mutual fund returns are more closely correlated within than between fund families. As a result, restricting investment to one fund family leads to a greater total portfolio risk than diversifying across fund families. We examine the sources of this increased correlation and find that it is due primarily to common stock holdings, but is also more generally related to families having similar exposures to economic sectors or industries. Fund families also show a propensity to focus on high or low risk strategies, which leads to a greater dispersion of risk across restricted investors. An investor considering adding an additional fund, either in the same family or outside the family, would need to believe the inside fund offered an extra 50 to 70 basis points to have the same Sharpe ratio.
Why Do Controlling Families of Public Firms Sell Their Remaining Ownership Stake?
Authors: Klasa Sandy
Published: April 2009

I investigate what leads controlling families of publicly traded firms to sell their remaining ownership stake. The sale of a controlling stake is best explained in the context of theories of the firm related to optimal risk bearing, the separation of ownership and management expertise, the CEO succession process, and the monitoring provided by outside blockholders. A timing explanation is only marginally supported. The sale of a controlling stake is not explained by insufficient financial resources to fully invest in growth opportunities. This study offers insights into the final stage of the process in which entrepreneurs sequentially sell their firm to outside parties and also identifies the nature of costs of concentrated ownership.
Discounting and Clustering in Seasoned Equity Offering Prices
Authors: Mola Simona , Loughran Tim
Published: April 2009

An analysis of 4,814 SEOs during 1986–1999 indicates that the average offering ofnew shares is priced at a discount of 3% from the closing price on the day before the issue. Discounts have risen steadily over time, sharply increasing the indirect costs of issuing seasoned equity. There is evidence of increased clustering of offer prices at integers, and of greater importance in the analyst coverage provided by underwriters. Adjusting for other factors, we find that issues with integer offer prices, and underwriters with highly regarded analysts, are increasingly associated with larger discounts. The rise in discounts is consistent with an increased ability of investment bankers to extract rents from issuing firms.
Competitive Equilibrium with Debt
Authors: Zhdanov Alexei
Published: April 2009

This paper studies the interaction among financing, entry, and exit decisions of firms in a competitive industry subject to aggregate uncertainty. In contrast to Fries, Miller, and Perraudin (1997), I do not assume that a firm in default leaves the industry immediately. The implications on the optimal leverage ratios and equilibrium credit spreads are discussed. By incorporating the effect of competition, I show that the model results in significantly higher credit spreads than those predicted by traditional single firm models. Dynamic capital structure strategies in a competitive industry are also examined. The model renders a number of empirical predictions regarding leverage ratios and credit spreads of firms in a competitive industry.
Rayleigh–Taylor and Richtmyer–Meshkov instabilities of flat and curved interfaces
Authors: KRECHETNIKOV R.
Published: April 2009

In this work we discuss a non-trivial effect of the interfacial curvature on the stability of uniformly and suddenly accelerated interfaces, such as liquid rims. The new stability analysis is based on operator and boundary perturbation theories and allows us to treat the Rayleigh–Taylor and Richtmyer–Meshkov instabilities as a single phenomenon and thus to understand the interrelation between these two fundamental instabilities. This leads, in particular, to clarification of the validity of the original Richtmyer growth rate equation and its crucial dependence on the frame of reference. The main finding of this study is the revealed and quantified influence of the interfacial curvature on the growth rates and the wavenumber selection of both types of instabilities. Finally, the systematic approach taken here also provides a generalization of the widely accepted ad hoc idea, due to Layzer (Astrophys. J., vol. 122, 1955, pp. 1–12), of approximating the potential velocity field near the interface.
Estimating intermittency in three-dimensional Navier–Stokes turbulence
Authors: GIBBON J. D.
Published: April 2009

The issue of why computational resolution in Navier–Stokes turbulence is hard to achieve is addressed. Under the assumption that the three-dimensional Navier–Stokes equations have a global attractor it is nevertheless shown that solutions can potentially behave differently in two distinct regions of space–time$\mathbb{S}$±where$\mathbb{S}$−is comprised of a union of disjoint space–time ‘anomalies’. If$\mathbb{S}$−is non-empty it is dominated by large values of |∇ω|, which is consistent with the formation of vortex sheets or tightly coiled filaments. The local number of degrees of freedom±needed to resolve the regions in$\mathbb{S}$±satisfies$\mathcal{N}^{\pm}(\bx,\,t)\lessgtr 3\sqrt{2}\,\mathcal{R}_{u}^{3},$, whereu=uL/ν is a Reynolds number dependent on the local velocity fieldu(x,t).
THE CONSTRUCTION OF NATURE IN THE MUSIC OF E. J. MOERAN
Authors: Huss Fabian Gregor
Published: April 2009

It is generally accepted that many composers of the British musical renaissance were strongly stimulated and influenced by nature, but questions such as how and why this influence actually worked, how it manifests itself in the music, how variously composers perceived and reacted to nature, and how ‘nature’ might be defined in the first place (particularly as expressed in a work of art) seem less clear. Although discussions of nature's influence on art have been attempted for centuries, only recently have commentators begun analyzing the exact function of nature in its various guises in the inspiration, creation and shaping of music. Concepts of nature itself differ widely for both composers and musicologists; while ‘nature’ (as a social, cultural or personal construct) in early 20th-century British music tended to be rural, idealized and rustic, it may more generally be understood as the material world in its entirety. Thus Vaughan Williams's London Symphony is just as valid ‘nature music’ as the Sea and Pastoral Symphonies that came before and after.
On topological algebra sheaves
Authors: Kyriazis Athanasios
Published: April 2009

Given two topological algebra sheaves, we seek that their tensor product be an (algebra) sheaf of the same type. We further study the latter sheaf in connection with the set of morphisms which are defined on it. As an application, we finally consider fundamental notions and results related to algebras of holomorphic functions in the framework of topological algebra sheaves.
On closed graph and implicit function theorems for multifunctions
Authors: Chou C. C. , Huang L. R. , Ng K. F.
Published: April 2009

We give several general implicit function and closed graph theorems for ser-valued functions. Let Z be a normed space,X, Ymetric spaces withXcomplete. Letf: X ⇉ Z,F: X × Y⇉ Z be multifunctions withz0∈ f(x0) ∩ F(x0, y0) such thatfis open at (x0, y0) andf‘approximates’Fin an appropriate sense. Suppose thatf−1(z) is closed,F(x, y)is compact for eachx, yandzand suppose thatF(x0, ·) is lower semi-continuous aty0. ThenF(·,y) is of closed graph ‘locally’, is open atx0, and there exists a functionx(·) withx(y)→x0fory→y0such thatz0∈F(x(y), (y))for allyneary0. A more general form dealing with the non-linear rate situation is also established.
Isometries of Hilbert space valued function spaces
Authors: Randrianantoanina Beata
Published: April 2009

Let X be a (real or complex) rearrangement-invariant function space on Ω (where Ω = [0, 1] or Ω ⊆ N) whose norm is not proportional to the L2-norm. Let H be a separable Hilbert space. We characterize surjective isometries of X (H). We prove that if T is such an isometry then there exist Borel maps a: Ω → + K and σ: Ω → Ω and a strongly measurable operator map S of Ω into B (H) so that for almost all ω, S(ω) is a surjective isometry of H, and for any f ∈ X(H), T f(ω) = a(ω)S(ω)(f(σ(ω))) a.e. As a consequence we obtain a new proof of the characterization of surjective isometries in complex rearrangement-invariant function spaces.