bluuebunny/crossref_metadata_2025 huggingface dataset:
Open subgroups of free abelian topological groups
Authors: Morris Sidney A. , Pestov Vladimir G.
Published: November 2008

We prove that any open subgroup of the free abelian topological group on a completely regular space is a free abelian topological group. Moreover, the free topological bases of both groups have the same covering dimension. The prehistory of this result is as follows. The celebrated Nielsen–Schreier theorem states that every subgroup of a free group is free, and it is equally well known that every subgroup of a free abelian group is free abelian. The analogous result is not true for free (abelian) topological groups [1,5]. However, there exist certain sufficient conditions for a subgroup of a free topological group to be topologically free [2]; in particular, an open subgroup of a free topological group on a kω-space is topologically free. The corresponding question for free abelian topological groups asked 8 years ago by Morris [11] proved to be more difficult and remained open even within the realm of kω-spaces. In the present paper a comprehensive answer to this question is obtained.
Hermitian–Einstein metrics and jumping lines forSp(n+1)-homogeneous bundles over ℙ2n+1
Authors: Vitter Al
Published: November 2008

Stable holomorphic vector bundles over complex projective space ℙnhave been studied from both the differential-geometric and the algebraic-geometric points of view.

On the differential-geometric side, the stability ofE-→ ℙncan be characterized by the existence of a unique hermitian–Einstein metric onE, i.e. a metric whose curvature matrix has trace-free part orthogonal to the Fubini–Study Kähler form of ℙn(see [6], [7], and [13]). Very little is known about this metric in general and the only explicit examples are the metrics on the tangent bundle of ℙnand the nullcorrelation bundle (see [9] and [10]).
Permutability in finite soluble groups
Authors: Ballester-Bolinches A. , Pérez-Ramos M. D.
Published: November 2008

Let G be a finite soluble group and let Σ be a Hall system of G. A subgroup U of G is said to be Σ-permutable if U permutes with every member of Σ. In [1; I, 4·29] it is proved that if U and V are Σ-permutable subgroups of G then so also are U ∩ V and 〈U, V〉.
The packing measure of self-affine carpets
Authors: Peres Yuval
Published: November 2008

We show that the seif-affine sets considered by McMullen [15] and Bedford [2] have infinite packing measure in their packing dimension θ except when all non-empty rows of the initial pattern have the same number of rectangles. More precisely, the packing measure is infinite in the gauge tθ|logt|−1 and zero in the gauge tθ|logt|−1−δ for any δ > 0.
The ideal lattices of the complex group rings of finitary special and general linear groups over finite fields
Authors: Hartley B. , Zalesskii A. E.
Published: November 2008

Letqbe a prime power, which will be fixed throughout the paper, letkbe a field, and letbe the field withqelements. LetGn(k)be the general linear groupGL(n, k), andSn(k)the special linear groupSL(n, k). The corresponding groups overwill be denoted simply byGnandSn. We may embedGn(k)inGn+1(k)via the map

Forming the direct limit of the resulting system, we obtain thestable general linear groupG∞(k) overk.
Continuity of homomorphisms and derivations from algebras of approximable and nuclear operators
Authors: Dales H. G. , Jarchow H.
Published: November 2008

1. Let be a Banach algebra. We say that homomorphisms from are continuous if every homomorphism from into a Banach algebra is automatically continuous, and that derivations from are continuous if every derivation from into a Banach -bimodule is automatically continuous.
Almost transitivity of some function spaces
Authors: Greim Peter , Jamison James E. , Kamińska Anna
Published: November 2008

The almost transitive norm problem is studied for Lp (μ, X), C(K, X) and for certain Orlicz and Musielak-Orlicz spaces. For example if p ≠ 2 < ∞ then Lp (μ) has almost transitive norm if and only if the measure μ is homogeneous. It is shown that the only Musielak-Orlicz space with almost transitive norm is the Lp-space. Furthermore, an Orlicz space has an almost transitive norm if and only if the norm is maximal. Lp (μ, X) has almost transitive norm if Lp(μ) and X have. Separable spaces with non-trivial Lp-structure fail to have transitive norms. Spaces with nontrivial centralizers and extreme points in the unit ball also fail to have almost transitive norms.
The self-affine carpets of McMullen and Bedford have infinite Hausdorff measure
Authors: Peres Yuval
Published: November 2008

We show that the self-affine sets considered by McMullen in [11] and by Bedford in [1] have infinite Hausdorff measure in their dimension, except in the (rare) cases where the Hausdorff dimension coincides with the Minkowski (≡ box) dimension. More precisely, the Hausdorff measure of such a self-affine set K is infinite in the gauge

(where γ is the Hausdorff dimension of K, and c > 0 is small). The Hausdorff measure of K becomes zero if 2 is replaced by any smaller number in the formula for the gauge ø.
Looking at bent wires – -codimension and the vanishing topology of parametrized curve singularities
Authors: Mond David
Published: November 2008

Projecting a knot onto a plane – or, equivalently, looking at it through one eye – one sees a more or less complicated plane curve with a number of crossings (‘nodes’); viewing it from certain positions, some other more complicated singularities appear. If one spends a little time experimenting, looking at the knot from different points of view, then provided the knot is generic, one can convince oneself that there is only a rather short list of essentially distinct local pictures (singularities) – see Fig. 3 below. All singularities other than nodes are unstable: by moving one's eye slightly, one can make them break up into nodes. For each type X the following two numbers can easily be determined experimentally:

1. the codimension in ℝ3 of the set View(X) of centres of projection (viewpoints) for which a singularity of type X appears, and

2. the maximum number of nodes n into which the singularity X splits when the centre of projection is moved.
Some properties of Hopf-type constructions
Authors: Arkowitz Martin , Silberbush Paul
Published: November 2008

If f: X × Y → Z is a map, then the classical Hopf construction associates to f a map hf: X * Y → ΣZ, where X * Y is the join of X and Y and ΣZ the suspension of Z. Since X * Y has the homotopy type of Σ(X Λ Y), the suspension of the smash product of X and Y, the homotopy class of hf can be regarded as an element Hf ↦ [Σ(X Λ Y), ΣZ]. Now elements of [Σ(X Λ Y), ] are in one to one correspondence with homotopy classes in the group [σ(X Λ Y), ΣZ] which are trivial on the suspension of the wedge Σ(X ≷ Y).
Reflexivity for a class of subspace lattices
Authors: Katsoulis E. G.
Published: November 2008

The complete lattice generated by a totally atomic CSL ℒ and the projection lattice of a von Neumann algebra ℛ, commuting with ℒ, is reflexive. From this it follows that the strongly closed lattice generated by any CSL ℒ and the projection lattice of a properly infinite von Neumann algebra ℛ, commuting with ℒ, is reflexive.
Full laminations in 3-manifolds
Authors: Hatcher A. , Oertel U.
Published: November 2008

Essential laminations in 3-manifolds, introduced in [GO], are a natural generalization of both incompressible surfaces and foliations without Reeb components. One of the main reasons why essential laminations are of particular interest is that many manifolds which contain no incompressible surfaces contain essential laminations. Indeed, there is some evidence that almost all irreducible manifolds with infinite fundamental group contain essential laminations [B1;D;GM;GO;H;N;R], the only known exceptions being Seifert manifolds [B2]. So essential laminations are potentially a quite powerful tool for studying non-Haken 3-manifolds.
Unstable homotopy classification of
Authors: Martino John , Priddy Stewart
Published: November 2008

For nilpotent spaces p-completion is well behaved and reasonably well understood. By p–completion we mean Bousfield–Kan completion with respect to the field Fp [BK]. For non-nilpotent spaces the completion process often has a chaotic effect, this is true even for small spaces. One knows, however, that the classifying space of a compact Lie group is Fp-good even though it is usually non-nilpotent.
The trace form for tame, abelian extensions of number fields
Authors: Taylor M. J.
Published: November 2008

Let N/K be a tame, abelian extension of number fields, whose Galois group is denoted by Γ. The basic object of study in this paper is the ring of integers of N, endowed with the trace form TN/K; the pair is then a Hermitian module (where we abbreviate ), and it restricts to a -Hermitian module (The reader is referred to Section 2 for the basics on Hermitian modules.) Ideally one would like to determine completely the class of this Hermitian module in K0H(ℤΓ), the Grothendieck group of ℤΓ-Hermitian modules modulo orthogonal sums; however, in general when Γ is even, one knows that even the ℚΓ-Hermitian module given by restricting (N, TN/K) is difficult to classify. (See for instance [S] and [F2].) To circumvent this difficulty we proceed in the following fashion, as suggested by the recent work of P. Lawrence (see [L]): let D = D(Γ) denote the anti-diagonal of Γ in Γ × Γ, that is to say

and let N(2) = (N⊗KN)D so that N(2) is a Galois algebra over K with Galois group Γ × Γ/D(Γ) ≅ Γ. Write for the trace form of N(2)/K, and define the -order it is then easy to see that is isomorphic as an -module to (see (3·1·6)). To be precise we ought really to write etc.; however, the base field will always be clear from the context.
Normal solutions of elliptic equations
Authors: Koskela Pekka
Published: November 2008

We extend a number of known criteria for normality of analytic and harmonic functions to the setting of solutions to elliptic partial differential equations. Some of the results hold for monotone Sobolev functions. We also discuss the boundary behaviour of monotone Sobolev functions.
Coefficient inequalities for analytic functions in H1
Authors: Wittmann Rainer
Published: November 2008

Improving earlier result of Hardy and Littlewood[1] and McGehee, Pigno and Smith[2] we show for analytic functions on the unit disc that
The lemma of the logarithmic derivative for subharmonic functions
Authors: Rudin Walter
Published: November 2008

The classical statement of the lemma in question [7], [3] is about meromorphic functions f on ℂ and says that

for all r > 0, with the possible exception of a set of finite Lebesgue measure. Here T(r, f) is the Nevanlinna characteristic of f. The lemma plays an important role in value distribution theory.
On the size of products of distances from prescribed points
Authors: Erdős Paul , Totik Vilmos
Published: November 2008

The following problem was raised in the 1993 Miklós Schweitzer Mathematical Contest (see [4]). Let E be any connected set in the plane of diameter greater than 4, and let Z1, Z2, …, be any sequence of points on the plane. Then there is a point X ε E for which infinitely many of the products X¯Z¯1 · X¯Z¯n are greater than 1. Furthermore, the same is not necessarily true if the diameter of E is 4.
-annihilated elements in H*(CP∞ × CP∞)
Authors: Crossley M. D.
Published: November 2008

We compute the subring of H*(CP∞ × CP∞; ) annihilated by the Steenrod algebra, , p being an odd prime. By calculating the subring's structure as a GL(2, )-space we may obtain information about the modular representations of that group.
Singularity theory and equivariant bifurcation problems with parameter symmetry
Authors: Furter Jacques-Élie , Sitta Angela Maria , Stewart Ian
Published: November 2008

The study of equivariant bifurcation problems via singularity theory (Golubitsky and Schaeffer[8], Golubitsky, Stewart and Schaeffer[9]) has been mainly concerned with models exhibiting spontaneous symmetry-breaking. The solutions of such bifurcation problems lose symmetry as the parameters vary, but the equations that they satisfy retain the same symmetry throughout.
Two-generator arithmetic Fuchsian groups. II
Authors: Maclachlan C. , Rosenberger G.
Published: November 2008

An arithmetic Fuchsian group is necessarily of finite covolume and so of the first kind. From the structure theorem for finitely generated Fuchsian groups those of the first kind which can be generated by two elements are triangle groups, groups of signature (1;q;0) or (1; ; 1) or groups of signature (0;2,2,2,e;0) where e is odd 6. It is known that there are finitely many conjugacy classes of arithmetic groups with these signatures or indeed with any fixed signature 3, 15. In the case of non-cocompact groups, the arithmetic groups are conjugate to groups commensurable with the classical modular group and are easily determined. For the other groups described above the space of conjugacy classes of all such Fuchsian groups of fixed signature can be described in terms of the traces of a pair of generating elements and their product. In the case of triangle groups this space is a single point. This description has been utilized to determine all classes of triangle groups 13 and groups of signature (1;q;0) which are arithmetic 15. In this paper we determine all classes of groups of signature (0;2,2,2,e;0) with e odd which are arithmetic. The techniques involving traces used so profitably in 15 are not so fruitful in this case. Consequently we have in the main resorted to a quite different method which does not rely on having a precise description of the space of conjugacy classes and hence could be applicable to groups other than those which have rank 2. Extensive use is made of results of Borell on the structure of arithmetic Fuchsian groups which require detailed information on the number fields defining the quaternion algebras. Consequently, the results are given in terms of the quaternion algebra which is determined by its defining field and ramification set, and maximal orders in that quaternion algebra.
Asymptotic values of continuous functions in Euclidean space
Authors: Rippon P. J.
Published: November 2008

In this paper we generalize a result of Hayman 4, lemma 4 on asymptotic values of meromorphic functions, which can be stated as follows.
Representations related to CM elliptic curves
Authors: Boston Nigel , Ullom Stephen V.
Published: November 2008

In [10], Mazur showed that the p-adic lifts of a given absolutely irreducible representation are parametrized by a universal deformation ξ:Gℚ, S → GL2() where has the form . (Here Gℚ, S is the Galois group over ℚ of a maximal algebraic extension unramified outside a finite set S of rational primes.) In [1, 3, 10], situations were investigated where the universal deformation ring turned out to be ℚp[[T1T2, T3]] (i.e. r = 3, I = (0)). In [2], the tame relation of algebraic number theory led to more complicated universal deformation rings, ones whose prime spectra consist essentially of four-dimensional sheets.
On a hyperbolic 3-manifold with some special properties
Authors: Zimmermann B.
Published: November 2008

We present a closed hyperbolic 3-manifold M with some surprising properties. The universal covering group of M is a normal torsion-free subgroup of minimal index in one of the nine Coxeter groups G, generated by the reflections in the faces of one of the nine Lannér-tetrahedra (bounded tetrahedra in hyperbolic 3-space all of whose dihedral angles are of the form π/n with n ∈ ℕ see [1] or [3]). The corresponding Coxeter group G splits as a semidirect product G = π1M⋉A, where A is a finite subgroup of G, and G is the only one of the nine Coxeter groups associated to the Lannér-tetrahedra which admits such a splitting (this follows using results in [4]). We derive a presentation of π1M and show that the first homology group H1(M) of M is isomorphic to ℚ11. This is in sharp contrast to other torsion-free (non-normal) subgroups of finite index in Coxeter groups constructed in [1] which all have finite first homology (though it is known that they are all virtually ℚ-representable (see [5], p. 434). It follows from our computations that the Heegaard genus of M is 11, and that there exists a Heegaard splitting of M of genus 11 invariant under the action of the group I+(M) ≌ S5 ⊕ ℚ2 of orientation-preserving isometries of M (we compute this group in [4]), so that the Heegaard genus of M is equal to the equivariant Heegaard genus of the action of I+(M) on M. Moreover M is maximally symmetric in the sense of [4, 6]: the order 120 of the subgroup of index 2 in I+(M) which preserves both handle-bodies of the Heegaard splitting is the maximal possible order of a group of orientation-preserving diffeomorphisms of a handle-body of genus 11. (This maximal order is 12(g—1) for a handle-body of genus g; see [7].) By taking the coverings Mq of M corresponding to the surjections π1M→H1(M) ≌ ℚ11→(ℚq)11 for q ∈ ℕ, we obtain explicitly an infinite series of maximally symmetric hyperbolic 3-manifolds.
Quasifree representations of Clifford algebras
Authors: Robinson P. L.
Published: November 2008

Let V be an infinite-dimensional real Hilbert space with associated C* Clifford algebra C[V]. To any state σ of the C* algebra C[V] there corresponds a skew-adjoint operator C of norm at most unity on V such that

we refer to C as the covariance of the state σ.
The word problem for the bifree combinatorial strict regular semigroup
Authors: Auinger Karl
Published: November 2008

A class of regular semigroups closed under taking direct products, regular subsemigroups and homomorphic images is ane(xistence)-variety of regular semigroups. The classof all combinatorial strict regular semigroups is thee-variety generated by the five element non-orthodox completely 0-simple semigroup and consists of all regular subdirect products of combinatorial completely 0-simple semigroups and/or rectangular bands. The bifree objecton the setXinis the natural concept of a ‘free object’ in the class.is generated by the setXand the set of formal inversesX′ under the two binary operations of multiplication · and forming the sandwich element ∧A. Henceis a homomorphic image of the absolutely free algebraof type 〈2, 2〉 generated by X ∪X′. In this paper we shall describe the associated congruence onF〈2, 2〉(X∪X′) and construct a model ofin terms of sets and binary relations. As an application, a model of the free strict pseudosemilattice on a setXis obtained.
On an equation connected with the theory of triode oscillations
Authors: Smith R. A.
Published: November 2008

This discussion is concerned with the periodic solutions of the differential equation

where the parameter k is small. The equation arises from an investigation of the forced oscillations of a simple electrical circuit (6) containing a triode. The function f(x) is derived from the current-voltage characteristic of the triode and it has a roughly ⊂-shaped graph, with a flat bottom and some slight asymmetry. For a regenerative circuit, we have f(0) < 0. Van der Pol (5) considered the equation with f (x) = x2 − 1, and he and later writers (1, 2, 4) have built up an extensive theory of triode oscillations for this ideal case. In practice, the graph of f(x) has a much flatter bottom than that of the function x2 − 1, and it was asked by Cartwright ((3), p. 214) whether this flattening would alter the qualitative behaviour of the circuit near resonance. The main part of this paper is an attempt to answer this question.
A dichotomy for infinite convolutions of discrete measures
Authors: Brown G. , Moran W.
Published: November 2008

Measures, μ which can be realized as an infinite convolution

where each measure μn is a discrete measure, arise naturally in many parts of analysis and number theory (see (15)). The basic property of these measures is ‘purity’; i.e. such a measure μ 1must be absolutely continuous, continuous and singular, or discrete.
Free S1-actions and involutions on homotopy seven spheres
Authors: Mayer K. H.
Published: November 2008

In this note the concept of modest vector bundle, defined in (5), is used to define an invariant for certain free S1-actions. This invariant is a rational function and classifies the equivalence classes of free S1-actions on homotopy seven spheres. In a similar way an invariant for free involutions is defined, which is a generalization of the Spin invariant defined in (4). Using this invariant and Hirzebruch's α-invariant it is possible to state conditions for a free involution of a homotopy seven sphere to be embedded in a free S1-action.
Separate approximate continuity implies measurability
Authors: Davies Roy O.
Published: November 2008

It is known that a real-valued function f of two real variables which is continuous in each variable separately need not be continuous in (x, y), but must be in the first Baire class (1). Moreover if f is continuous in x for each y and merely measurable in y for each x then it must be Lebesgue-measurable (7), and this result can be extended to more general product spaces (2). However, the continuum hypothesis implies that this result fails if continuity is replaced by approximate continuity, as can be seen from the proof of Theorem 2 of (2). This makes Mišik's question (5) very natural: is a function which is separately approximately continuous in both variables necessarily Lebesgue-measurable? Our main aim is to establish an affirmative answer. It will be shown that such a function must in fact be in the second Baire class, although not necessarily in the first Baire class (unlike approximately continuous functions of one variable (3)). Finally, we show that the existence of a measurable cardinal would imply that a separately continuous real function on a product of two topological finite complete measure spaces need not be product-measurable.
On the converse of Mertens' theorem
Authors: Jukes K. A.
Published: November 2008

Let (λm), (µn) (m, n = 0, 1, 2,…) satisfy

respectively. Let vp (p = 0, 1, 2, …) be the sequence (λm+µn) arranged in ascending order, equal sums λm+µn being considered as giving just one vp Then for given formal series Σam, Σbn the formal series C = Σ cp where

is called the general Dirichlet product of Σamand Σbn (see Hardy (2), p. 239). When λn = µn = n we have the Cauchy product. In the case λn = logm, µn = logn (m, n = 1, 2,…) we have vp =log p(p = 1, 2, …)and it is natural to call C the ordinary Dirichlet product.
On the invariants of a linear group of order 336
Authors: Mallows C. L. , Sloane N. J. A.
Published: November 2008

The polynomial invariants of a certain classical linear group of order 336 arise naturally in studying error-correcting codes over GF(7). An incomplete description of these invariants was given by Maschke in 1893. With the aid of the Poincaré series for this group, found by Edge in 1947, we complete Maschke's work by giving a unique representation for the invariants in terms of 12 basic invariants. A conjecture is made concerning the relationship between the Poincaré series and the degrees of the basic invariants for any linear group. A partial answer to this conjecture, due to E. C. Dade, is given.
On the Arf invariant of links
Authors: Wu Ying-Qing
Published: November 2008

In ([2], p. 310) the problem of relating the Arf invariant of a link to other link invariants, and finding practical ways of computing it, was raised. Murasugi gave a partial solution to this in [9]: if L has two components, then Arf(L), when defined, is given by

where l1, l2 are the components of L, and ΔL(t1, t2) denotes the Alexander polynomial of L.
The Temperature Dependence of the Photo-Electric Effect
Authors: Mitchell K.
Published: November 2008

The temperature dependence of the photo-electric effect with the image field is discussed, the result obtained agreeing with Fowler's T2 law near the threshold. Fowler's law is discussed, and shown to rest upon a mistake in the normalization of the free wave functions.

The two methods of analysing experimental results due to Fowler and Du Bridge are also discussed, and it is shown that in general the latter should give the more reliable results.

The author wishes to repeat his thanks to Prof. R. H. Fowler and to Mr A. H. Wilson for their constant interest in the work.
The Application of the Electron Lens to Cloud Chamber Photography
Authors: Davies W. T. , O'Ceallaigh C.
Published: November 2008

During the course of a cloud chamber investigation of the occurrence of rare events accompanying the passage of fast β-particles through matter, it was found* that existing methods of introducing high-energy electrons into the chamber were unsatisfactory. Electrons of sufficiently high energy could only be obtained from sources which emit, in addition, a large amount of γ-radiation. Absorption of this γ-radiation in the walls and gas of the chamber resulted in the ejection of numbers of stray electrons, whose presence rendered the observation of the fast β-ray tracks a matter of some difficulty.
Terminating comprehensions
Authors: Reade Chris
Published: November 2008

List terminators are discussed as a new form of qualifier in list comprehensions for early termination of a list. The semantics of list terminators is expressed in terms of an optimal translation of list comprehensions (cf. Wadler, 1987) because it makes direct use of a continuation list.
New dimensions in heap profiling
Authors: Runciman Colin , Röjemo Niklas
Published: November 2008

First-generation heap profilers for lazy functional languages have proved to be effective tools for locating some kinds of space faults, but in other cases they cannot provide sufficient information to solve the problem. This paper describes the design, implementation and use of a new profiler that goes beyond the two-dimensional ‘who produces what’ view of heap cells to provide information about their more dynamic and structural attributes. Specifically, the new profiler can distinguish between cells according to their eventual lifetime, or on the basis of the closure retainers by virtue of which they remain part of the live heap. A bootstrapping Haskell compiler (nhc) hosts the implementation: among examples of the profiler's use we include self-application to nhc. Another example is the original heap-profiling case study clausify, which now consumes even less memory and is much faster.
Error analysis of boundary integral methods
Authors: Sloan Ian H.
Published: November 2008

Many of the boundary value problems traditionally cast as partial differential equations can be reformulated as integral equations over the boundary. After an introduction to boundary integral equations, this review describes some of the methods which have been proposed for their approximate solution. It discusses, as simply as possible, some of the techniques used in their error analysis, and points to areas in which the theory is still unsatisfactory.
Aspects of the numerical analysis of neural networks
Authors: Ellacott S.W.
Published: November 2008

This article starts with a brief introduction to neural networks for those unfamiliar with the basic concepts, together with a very brief overview of mathematical approaches to the subject. This is followed by a more detailed look at three areas of research which are of particular interest to numerical analysts.

The first area is approximation theory. IfKis a compact set in ℝn, for somen, then it is proved that a semilinear feedforward network with one hidden layer can uniformly approximate any continuous function inC(K) to any required accuracy. A discussion of known results and open questions on the degree of approximation is included. We also consider the relevance of radial basis functions to neural networks.

The second area considered is that of learning algorithms. A detailed analysis of one popular algorithm (the delta rule) will be given, indicating why one implementation leads to a stable numerical process, whereas an initially attractive variant (essentially a form of steepest descent) does not. Similar considerations apply to the backpropagation algorithm. The effect of filtering and other preprocessing of the input data will also be discussed systematically.

Finally some applications of neural networks to numerical computation are considered.
IN THE EYE OF THE BEHOLDER
Authors: Krysan Maria , Farley Reynolds , Couper Mick P.
Published: November 2008

There is a lively debate about the causes of racial residential segregation. Counter to the racial-proxy hypothesis (Harris 1999, 2001), we argue that race,per se, continues to be influential when Whites make housing decisions. Using a survey-based experiment, we ask: Does information about neighborhood racial composition influence how Whites judge the quality of that neighborhood, quite apart from the actual characteristics of the homes located in it? A random sample of adults aged twenty-one and older in the Chicago and Detroit metropolitan areas watched videos embedded in a face-to-face interview. These videos portrayed neighborhoods ranging from lower working class to upper class. All respondents saw the same neighborhoods but were randomly assigned to see either (1) White residents, (2) Black residents, or (3) a mix of both White and Black residents. Respondents then evaluated the neighborhoods in terms of housing cost, property upkeep, safety, trajectory of housing values, and quality of the schools. Results show that Whites who saw White residents rated the neighborhood more positively on four of five dimensions than did Whites who saw the identical neighborhood with Black residents; racially mixed neighborhoods fell in between. In addition, Whites who endorsed negative stereotypes about Blacks were more likely to give low evaluations to neighborhoods with Black residents than were Whites who did not endorse stereotypes.
Zusammenhänge zwischen Händigkeit und motorischen und kognitiven Leistungen im Kindesalter
Authors: Krombholz Heinz
Published: November 2008

Zusammenfassung. In einer Längsschnittstudie wurden die Entwicklung der Händigkeit bei Kindergartenkindern (153 Jungen und 170 Mädchen) und deren Zusammenhänge mit motorischen und kognitiven Leistungen analysiert. Die Händigkeit wurde aufgrund der relativen Geschicklichkeit beider Hände bestimmt. Im Untersuchungszeitraum lässt sich keine Veränderung des Anteils von Rechtshändern (84.8%), Linkshändern (9.8%) und Ambidextern (5.4 %) nachweisen, Jungen sind häufiger linkshändig oder beidhändig als Mädchen. Der Anteil von Linkshändern bei Erstgeborenen, die ein höheres Risiko für Hirnschädigungen aufweisen, ist nicht höher als bei Nachgeborenen. Etwa 16 Prozent der Kinder, vor allem Linkshänder und Ambidexter, aber auch Rechtshänder, wechselten im Untersuchungszeitraum ihre Händigkeit. Linkshändigkeit oder Beidhändigkeit gehen nicht mit verminderten kognitiven oder motorischen Leistungen einher, allerdings erzielten Kinder, die im Untersuchungszeitraum ihre Händigkeit wechselten, schlechtere feinmotorische und kognitive Leistungen als Kinder mit konstanter Händigkeit.
Munchausen Syndrome by Proxy: A Dilemma for Diagnosis
Authors: Sendín Bande Concepción , García-Alba Carmen
Published: November 2008

Very little is yet known about the etiology, epidemiology, and long-term impact of Munchausen syndrome by proxy (MSBP). However, on reviewing the literature, there is an increasing interest in this unusual but serious pathology, which appears almost always in children and poses many clinical and forensic dilemmas for diagnosis and management. We present a MSBP case-study of a mother (54 years old) and her son (13 years old), through their Rorschach tests (Comprehensive System; Exner, 2000 ) and the Research Diagnostic Criteria Family-History interview (FH-RDC; Endicott, Andreasen & Spitzer, 1989 ). The main objectives were (1) to compare psychological evaluation data with DSM-IV-TR criteria for Personality Disorder (PD), and (2) to describe MSBP psychopathological manifestations on both records. Since it is a case-study, Rorschach variables were analyzed in two ways: (1) parametric variables were standardized with respect to the norms for each age and then zscores were used, and (2) nonparametric variables and some formulations were dichotomized in order to use the critical scores proposed by Exner (2000 ). Results confirm the presence of a PD in the mother. In the boy, they indicate that we could expect a development toward a PD or an increase of his isolation and his perceptual-cognitive disarray, with a possible long-term split of his frail psychic balance.
Short‐term relationship of total electron content with geomagnetic activity in equatorial regions
Authors: Wang X. , Sun Q. , Eastes R. , Reinisch B. , Valladares C. E.
Published: November 2008

The short‐term relationship between equatorial ionosphere and geomagnetic activity is examined. Hourly averages of the total electron content (TEC) and critical frequency of theF2layer (foF2) are compared with theDstindex, a proxy for equatorial geomagnetic activity, at three local times (0700–0800, 1200–1300, and 1600–1700 LT) from March 1998 to August 1999. Owing to the geomagnetic latitude and local times used, positive storms, almost exclusively, are observed (cf. Prölss, 1995). WhilefoF2measurements over an extended period (∼10 years) have been studied (Matsushita, 1959) and TEC andfoF2are coupled, TEC measurements can provide a significantly better signal‐to‐noise ratio. At timescales of 2–3, 3–5, 5–9, and 9–11 days, there are significant correlations (∼0.4 at local noon, when all the data are included) between TEC andDst. These correlations increase from morning to afternoon. By comparison, correlations betweenfoF2andDstare significantly smaller, ∼0.2 (near the noise level) at local noon. Even during geomagnetically quiet times (Dst> −20), a clear correlation (0.21, which exceeds the 95% confidence level by 0.05) is seen between TEC andDstat the shortest timescale examined. As geomagnetic activity increases, the correlations increase rapidly. For example, when moderate levels of geomagnetic activity (Dst> −50) are included for observations at local noon, distinct correlations (∼0.3) are seen and persist for all but the longest timescale; with higher levels of geomagnetic activity included, there are distinct correlations at all the timescales examined. The presence of a significant correlation at quiet conditions and persistence of the correlation at moderate levels of activity are both unexpected.
Diasporic Governmentality: On the Gendered Limits of Migrant Wage-Labour in Portugal
Authors: Fikes Kesha
Published: November 2008

This essay explores the meaning of diasporic practice as it has been applied within the contemporary Black Atlantic context. The general focus of this topic has been visible or performative practices that have broad audiences, ranging from diasporic members to the sociopolitically included or the privileged citizen. Moreover, the objects or products of diasporic practice are largely understood to be aesthetic; the literature has highlighted music, dance, art, and religion, for instance. In this essay I argue that a taken-for-granted prerequisite of a hierarchized viewing audience misses passing moments of negotiation that occur in silence or within disciplined exchanges among persons who we identify as diasporic. These practices build community in very powerful ways but may not leave lasting traces or archives; they have to do with fleeting displays of affect such as rage, shame, joy, etc. The ethnographic focus is African immigrant women's constrained work schedules in Lisbon and the ways their labour-time textures the types of community – building practices in which they engage on a daily basis. I address how gendered configurations of migrant labour-time -a condition for governmentality – influence the diasporic process by which a form of racial identification is assumed in the context of Portugal.
The Comic Side of Gender Trouble and Bert Williams’ Signature Act
Authors: Stephens Michelle Ann
Published: November 2008

Using the turn of the century blackface performer Bert Williams as a case study, this essay explores how we might think about black male performativity in the New World as a historical formation, one that extends both over the time of modernity and across the space of diaspora. I draw from contemporary theories of circum-atlantic performance and black feminist studies of the impact of slavery on black racial and gendered identities, to argue that performance affords a unique window into how blackness is constructed in a space between the black male performer and his equally racialized New World audience. The essay theorizes a notion of key black male performances as ‘signature acts’, then explores discussions of minstrelsy by other black American writers such as Ralph Ellison, Ishmael Reed, and the black British writer Caryl Phillips. Using Fanon's notions of triple-consciousness in tandem with Brechtian and Freudian theories of alienated performances and jokes, the essay concludes with a brief analysis of some of the gendered significations in lyrics from Bert Williams’ first musical comedy and then also in a novel about the performer by Caryl Phillips.
Simultaneous light emissions from two different types of fluorophores in diblock copolymer micellar films
Authors: Peng Juan , Chen Minjie , Qiu Feng , Yang Yuliang , Sohn Byeong-Hyeok , Kim Dong Ha
Published: November 2008

We report a simple strategy to realize simultaneous light emissions from a single layer of poly(styrene-block-2-vinyl pyridine) (PS-b-P2VP) copolymer micelles incorporated with a fluorescent dye in the P2VP core and a conjugated polymer in the PS corona. The fluorescence resonance energy transfer between the dye and the conjugated polymer is effectively inhibited due to the isolation of micelles. This study may offer an effective way to facilitate the ongoing exploration of white light emission in optics and optoelectronics.
Structural, electronic, and optical properties of a prototype columnar discotic liquid crystal
Authors: Cinacchi Giorgio , Colle Renato , Parruccini Pietro , Tani Alessandro
Published: November 2008

Structural, electronic, and optical properties calculated for an isolated infinite column of hexakis-hydroxy-triphenylene (HAT0) molecules are presented. This system is intended as a prototype model of columnar discotic liquid crystals since HAT0 is the first member of the discogenic hexakis-n-alkyloxy-triphenylenes (HATn) series; the single-column approximation can be adopted in view of the peculiar nanoseparation of the columns characteristic of these mesophases. Structural optimization of the system has been performed using Car–Parrinello molecular dynamics techniques. Kohn–Sham orbitals, density of states, and electronic energies have been calculated on the optimized structure of the infinite column and implemented in the quantum expression of the transverse dielectric function. The optical absorption spectrum calculated from the dielectric function has been discussed in comparison to a measured absorption spectrum of HAT5 in columnar discotic liquid crystal phase. Optical absorption spectra of short columns of a few HAT0 molecules arranged as in the infinite column have been calculated using the ZINDO method. These spectra are in good agreement with measured absorption spectra of HAT5 and HAT6 in organic solvents, a fact that supports the proposed columnar arrangement of the discotic molecules in these solvents. We also give an estimate of the electronic transport properties of a small column of HAT0 molecules by calculating with the nonequilibrium Green’s function method, the current/voltage characteristic of a model system in which a few HAT0 molecules have been inserted between two gold electrodes under the bias of an external potential.
Exciton scattering approach for branched conjugated molecules and complexes. I. Formalism
Authors: Wu Chao , Malinin Sergey V. , Tretiak Sergei , Chernyak Vladimir Y.
Published: November 2008

We develop a formalism for the exciton scattering (ES) approach to calculation of the excited state electronic structure of branched conjugated polymers with insignificant numerical expense. The ES approach attributes electronic excitations in quasi-one-dimensional molecules to standing waves formed by the scattering of quantum quasiparticles. We derive the phenomenology from the microscopic description in terms of many-electron excitations. The presented model can be used to compute both excited state frequencies and transition dipoles in large molecules after the ES ingredients are extracted from smaller molecular fragments.
Magnetic properties and nonmagnetic phases formation in (Fe/Si)n films
Authors: Varnakov S. N. , Komogortsev S. V. , Ovchinnikov S. G. , Bartolomé J. , Sesé J.
Published: November 2008

The magnetization of Fe/Si multilayers, grown by thermal evaporation in an ultrahigh vacuum system, was investigated at high temperatures. Magnetization and its temperature dependence up to a high temperature of 800 K depend on individual Fe layer thickness dFe. This dependence is the result of the formation of an Fe–Si interface layer (nonmagnetic phase) during the synthetic procedure. The fraction of this Fe–Si nonmagnetic phase is estimated versus dFe. At temperatures higher than 400 K an irreversible decrease in the magnetization occurs. A quantitative analysis of this irreversible behavior is proposed in terms of an exponential diffusion-like kinetic equation for the reaction that produces the Fe–Si nonmagnetic phase. The coefficients of the rate equation are the activation energy Ea and the prefactor D0, which have been determined for different dFe.
The trigger sequence in the GCN4 leucine zipper: α-helical propensity and multistate dynamics of folding and dimerization
Authors: Chapagain Prem P. , Liu Yanxin , Gerstman Bernard S.
Published: November 2008

We investigate the importance of the trigger sequence in the folding and dimerization of the GCN4 leucine zipper. We examine the role of the enhanced propensity of the amino acids in the trigger sequence to form an α-helix. Using computer simulations, we calculate heat capacities, free energy profiles, and the probability for successful dimerization as a function of the strength of the α-helical propensity of the trigger sequence. Our results elucidate the experimentally observed importance of the trigger sequence for dimerization and why it is not necessary for the trigger to have a specific “consensus” sequence of amino acids. We also find that a stronger trigger sequence not only increases the probability for dimerization but also changes the dimerization dynamics by introducing multiple intermediate states.
Luminescence quenching in low doped polymer light-emitting diodes
Authors: Chen Zhifeng , Wang Hui , Li Aizhen , Shen Yong , Wang Yaxue , Zhang Wei , Yu Hancheng , Huang Jinwang , Lai Tianshu , Ji Liangnian
Published: November 2008

Transient luminescent dynamics in low doped porphyrin side-chain polymer film, poly(porphyrin acrylate-styrene) (P[(por)A-S]), were measured by using time-resolved photoluminescence spectroscopic technology. At relative higher intrachain porphyrin comonomer concentration (0.27%), the transient luminescence relaxation becomes more rapid with the increase in the interchain polymer concentration, resulting in low luminescence efficiency. The origin has been analyzed according to the Förster-type bimolecular annihilation theory. However, at the porphyrin comonomer concentration (0.1%), the luminescence relaxation of the P[(por)A-S] film becomes faster with the decrease in the interchain polymer concentration, inducing lower luminescence efficiency. The luminescence quenching has been analyzed according to the theory of MM+ force field and exciton rotational diffusion. The theoretical analyses are in good agreement with the experimental results.
Low temperature boron and phosphorus activation in amorphous germanium using Ni- and Co-induced crystallization and its application for three-dimensional integrated circuits
Authors: Park Jin-Hong , Tada Munehiro , Kapur Pawan , Saraswat Krishna C.
Published: November 2008

In this work, we present very low temperature boron (B) and phosphorus (P) activation technique in amorphous (α)-Ge using nickel (Ni)- and cobalt (Co)-induced crystallization. Ni and Co not only crystallize an α-Ge film, they also facilitate activation of the respective B and P atoms in the α-Ge during the crystallization process at temperatures as low as 360 °C. The feasibility of the low temperature activation technique has been demonstrated for a Ge gate electrode in a Si P-channel metal-oxide-semiconductor field-effect transistor using Schottky Ni (or Co) silicide source/drain.
Carrier recombination mechanisms in nitride single quantum well light-emitting diodes revealed by photo- and electroluminescence
Authors: Grzanka S. , Franssen G. , Targowski G. , Czernecki R. , Khachapuridze A. , Makarowa I. , Wiśniewska R. , Mensz P. , Perlin P. , Suski T.
Published: November 2008

Light emission of nitride single quantum well light-emitting diodes operating in the range from 395 to 440 nm, grown by metal-organic vapor phase epitaxy, was investigated by means of photoluminescence (PL) and electroluminescence (EL) spectroscopies as functions of temperature and current injection level. The indium content of the active layers was varied via the growth temperature, which ranged from 770 to 810 °C. It was found that samples with higher indium contents (grown at lower temperatures) exhibit larger luminescence full widths at half maximum (FWHMs) and higher EL intensities. The larger FWHM points to a larger amplitude of the potential profile fluctuations, which suggests that these fluctuations may be useful for the increase in the device output power. In agreement with this result, the performed examination by PL measurements shows large thermal stability of the luminescence intensity for the lowest growth temperature sample. On the other hand, a nontrivial dependence of thermal stability on growth temperature suggests the additional involvement of different nonradiative recombination center concentrations in the individual samples, for example, because of dissimilar substrate qualities.
Theoretical calculations of the carrier induced refractive index change in tensile-strained InGaAsP for use in 1550 nm semiconductor optical amplifiers
Authors: Connelly Michael J.
Published: November 2008

Nonlinear polarization rotation (NPR) in semiconductor optical amplifiers (SOAs) has applications in all-optical signal processing. Modeling NPR in a SOA requires knowledge of the carrier density induced refractive index change. The tensile-strained bulk SOA has attracted much interest due to its relative ease of fabrication and commercial devices are now available. In this letter we determine the polarization dependent refractive index change in such a SOA, with an InGaAsP active region, operating in the 1550 nm region and investigate its dependence on carrier density and wavelength.
Correlations between structural and electrical properties of nitrided SiOx thin films used as power metal oxide semiconductor field effect transistor gate dielectric
Authors: Fazio E. , Neri F. , Camalleri G. Curró M. , Calí D.
Published: November 2008

Correlations between the interface states and trap densities, in particular, the defect types that may be more or less strongly involved in power vertically diffused metal oxide semiconductor reliability performances, and the fine interface chemistry of the Ox–N–Siy bonds have been studied. The oxide preparation process is extracted from an STMicroelectronics proprietary standard for low voltage vertically diffused power metal oxide semiconductor field effect transistors with logic level gate driving. The oxynitride films were grown in N2O environment at temperatures equal to or higher than 900 °C and optionally subjected to a 1000 °C short annealing. Informations about the sample stoichiometry and the nitrogen bonding configurations were obtained by means of x-ray photoelectron spectroscopy. The results show that some peculiar linear and antilinear correlations exist between carrier traps across the oxide or at its interface and the amount of specific nitrogen bonding configurations. In particular, the role of the substitutional N(–SiO3)x bond as a marker of the electrical quality of Si/SiO2 interface is highlighted.