bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial patterns of internal migration: evidence for ethnic groups in Britain
Authors: Simpson Ludi , Finney Nissa
Published: December 2008

Internal migration is responsible for the changing geography of Britain's ethnic group populations. Although this changing geography is at the centre of heated debates of social policy, relatively little is known about the internal migration behaviour of different ethnic groups. This paper reviews existing evidence and analyses 1991 and 2001 Census data to provide an overview of patterns and trends in the geographies of migration for each ethnic group. It finds that counter‐urbanisation is common to all ethnic groups except Chinese. Both White and minority groups have on balance moved from the most non‐White areas in similar proportions, with some exceptions including White movement into the most concentrated Black areas, and Chinese movement towards its own urban concentrations. ‘White flight’ is not an appropriate term to describe White movement, nor to explain the growth of ethnically diverse urban areas. Copyright © 2009 John Wiley & Sons, Ltd.
Interconnection of the parameters obtained from the dielectric spectrum of CaF2 doped with ErF3 and YbF3 [Phys. Status Solidi B 245, No. 8, 1534–1537 (2008)]
Authors: Vassilikou‐Dova Aglaia , Katsika‐Tsigourakou Vassiliki
Published: December 2008

References [17] and [23] have to be completed in the paper published in Phys. Status Solidi B 245, 1534 (2008). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of piezoresistance effect in highly uniaxially strained p‐Si and n‐Si for current‐carrier mobility increase
Authors: Kolomoets Volodymyr , Baidakov Valentyn , Fedosov Anatolii , Gorin Andrii , Ermakov Valerii , Liarokapis Efthymios , Gromova Galina , Kazbekova B. , Taimuratova L. , Orasgulyev B.
Published: December 2008

Uniaxially strained channels occur in silicon p‐MOS transistors and n‐MOS transistors (IEDM Tech. Dig., pp. 61–64 (2002) and pp. 978–980 (2003) [1, 2]). Both longitudinal piezoresistance (PR) and transverse PR investigation in highly uniaxially strained p‐Si(B) and n‐Si(P) are presented. It is shown that the strong anisotropy of longitudinal PR and transverse PR are caused by the pressure‐induced change of isoenergetic surface shape, i.e. by the change of heavy‐hole effective mass and its anisotropy. In n‐Si the change of the longitudinal PR and transverse PR at X ∥ [100] is determined by both the change of the f‐transition probability with increasing pressure and the redistribution of electrons between the valleys with the effective mass m∥ (longitudinal PR) and m⊥ (transverse PR). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure and magnetic field effects on Pr1–xCax MnO3 thin films
Authors: Antonakos A. , Filippi M. , Auban‐Senzier P. , Lampakis D. , Pasquier C. R. , Prellier W. , Liarokapis E.
Published: December 2008

We report a systematic study of Pr1–x Cax MnO3 (x = 0.4 and 0.6) thin films grown on LaAlO3 (LAO) substrate (PCMO/LAO). X‐ray diffraction measurements have shown that the PCMO/LAO film is [101]‐oriented and under compressive strain due to the lattice mismatch. According to Raman spectroscopy the Jahn–Teller modes are suppressed under the application of pressure in the PCMO (x = 0.4) thin film. In particular, it was found that a pressure of 2 GPa suppresses the charge ordered state. Further high pressure measurements have confirmed that resistivity decreases linearly up to 2.4 GPa corresponding to a total reduction of about 35% in resistivity leading to a more conductive state on both concentrations. The temperature dependence of the resistivity has shown that the samples under pressure retain their semiconducting behavior. At ambient pressure the PCMO (x = 0.6) film shows a moderate magnetoresistance in the range 0–7 T and no metal to insulator transition (MIT). Raman spectroscopy confirmed that the application of a magnetic field of 1 T does not induce any remarkable changes on the electron–phonon interaction. Although, the hydrostatic pressure is not enough to induce a macroscopic metallic state, its effect is much greater than the one of the magnetic field. In addition, the effect of the 7 T magnetic field appears the same at ambient pressure and 2.5 GPa. Therefore the two effects of hydrostatic pressure and magnetic field do not seem to be coupled, at least up to the magnitudes studied. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tuning of the charge ordered state in the manganite thin films by internal or external strains
Authors: Antonakos A. , Filippi M. , Aydogdu G. H. , Prellier W. , Habermeier H.‐U. , Liarokapis E.
Published: December 2008

We have investigated methods for tuning the charge ordered state in the R1–x Cax MnO3 (R = La, Pr) manganite thin films grown on different substrates (SrTiO3 (STO), LaAlO3 (LAO), SrLaGaO4 (SLGO) and SrLaAlO4 (SLAO)). We have studied thin films of the Pr1–x Cax MnO3 manganite under hydrostatic pressure for various doping levels in order to induce a delocalization of carriers and destroy the charge ordered state (CO). It appears that both doping and the strains from the substrate can alter the CO state and tune the electrical properties of the compound. We have also proved that the application of an external hydrostatic pressure induces similar spectral modifications to doping in the Pr1–x Cax MnO3 (LCMO) thin films. By our systematic Raman studies under varying external (temperature and pressure) and internal (interfacial strains and doping) conditions, we investigate certain modes and extract direct information about the amount of the Jahn–Teller (JT) distortions, the CO state, and the strain or pressure induced phase separation in the manganite thin films. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐linear excitation and correlation studies of single InGaN quantum dots
Authors: Collins Daniel P. , Jarjour Anas F. , Taylor Robert A. , Hadjipanayi Maria , Oliver Rachel A. , Kappers Menno J. , Humphreys Colin J. , Tahraoui Abbes
Published: December 2008

The exact mechanism for non‐linear sub‐bandgap excitation of single InGaN quantum dots (QDs) has been investigated using interferometric autocorrelation techniques based around a near‐infrared (NIR) excitation laser. We identify unambiguously the heavily favoured two‐photon absorption (TPA) as being crucial in the observed background reduction for such Nitride structures and compare systematically the relative merits of both the linear (blue) and non‐linear (NIR) excitation regimes on several apertures of a masked sample. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of piezoelectric fields on excitonic complexes in InGaN quantum dots
Authors: Sebald K. , Kalden J. , Herlufsen S. , Lohmeyer H. , Tessarek C. , Yamaguchi T. , Figge S. , Hommel D. , Gutowski J.
Published: December 2008

We present an analysis of the optical properties of single InGaN quantum dots (QDs) grown by MOVPE. The samples were structured into mesas by focused‐ion‐beam etching and investigated by micro‐photoluminescence measurements. The QDs are characterized by the high temperature stability of their emission up to 150 K. Furthermore, the polarization of individual QD emission lines was analyzed giving an insight into their geometrical shape. Time‐resolved microphotoluminescence measurements on the excitonic and biexcitonic transition of a single quantum dot yields a radiative recombination lifetime of 2.06 ns for the exciton. The data can be fitted by a simple model for cascaded emission confirming the expected refilling of the excitonic state by biexcitonic recombination. In addition, the influence of piezoelectric fields on the exciton and biexciton emission and on their binding energy in single QDs was investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characteristics of chirped quantum dot superluminescent diodes
Authors: Bae H. C. , Park H. L. , You Y. C. , Han I. K. , Kim J. S.
Published: December 2008

We compared the superluminescent diodes (SLDs) of two types in order to see the effect of embedding another quantum dots (QDs) layer. The insertion of another QDs layer showed a new possibility for a wider spectrum. In addition, through comparing two kinds of SLD structures, the peak positions of the ground state and excited state were observed to be affected differently by band‐filling, thermal effect, and the overlap of tails of excited state (ES) gain, according to the wafer structure, and the effect of the cap layer is superior to the carrier non‐uniformity. We also revealed the temperature sensitivity of carriers in QDs through measuring characteristic temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering by porous structures with InAs quantum dots
Authors: Milekhin Alexander , Ursaki Veacheslav , Sirbu Lilian , Toropov Alexander , Tiginyanu Ion , Zahn Dietrich R. T.
Published: December 2008

In this paper we search for the possibilities of introducing porosity in InAs/AlAs/GaAs multilayer quantum dot structures as an additional tool for the modification of their phonon spectrum. Raman spectroscopy is used as a primary method of investigation of quantum dot phonon spectrum. Introduction of porosity in quantum dot structures leads to alteration of optical phonon frequencies in quantum dots due to relaxation of built‐in mechanical strain in quantum dots and appearance of Froehlich modes. Magnification of the Raman replicas by optical phonons in quantum dots is explained by multiple light reflection in the porous structure. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Line broadening of excitonic complexes in self‐assembled GaAs/AlGaAs single quantum dots
Authors: Abbarchi M. , Mastrandrea C. , Kuroda T. , Vinattieri A. , Mano T. , Koguchi N. , Sakoda K. , Gurioli M.
Published: December 2008

We present a detailed experimental study of the line broadening of the different excitonic complexes inside single GaAs/AlGaAs quantum dots. The investigated nanostructures are self assembled quantum dots (QDs), strain free nanocrystals grown by Modified Droplet Epitaxy technique. They show a typical PL spectrum with a triplet structure and by time correlated spectroscopy each contribution can be unambiguously assigned to neutral exciton, biexciton and trion.

By high resolution spectroscopy, we have studied the line broadening for several single GaAs/AlGaAs QDs. The measured linewidth is found to vary between several tens to few hundreds of meV and we attribute this to spectral diffusion. The striking feature of the PL spectrum is that the trion and the biexciton line are always sharper with respect to the neutral exciton (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High resolution spectroscopy of self‐assembled single GaAs/AlGaAs quantum dots
Authors: Abbarchi M. , Mastrandrea C. , Kuroda T. , Vinattieri A. , Mano T. , Koguchi N. , Sakoda K. , Gurioli M.
Published: December 2008

In this contribution we report the results of polarization resolved, high resolution photoluminescence spectroscopy of single lattice‐matched, GaAs/Al0:3Ga0:7As quantum dots. The investigated samples are self assembled, strain free nanocrystals grown by Modifed Droplet Epitaxy technique. The lack of strain reflects in a nominal lack of piezoelectric field making such nanostructures potentially highly symmetric and suitable systems as polarization entangled photon sources.

The high resolution, polarization resolved photoluminescence from isolated emitters present a clear linearlypolarized fine spectral splitting between the neutral exciton and biexciton lines while charged complexes are completely degenerate. By measuring the fine structure splitting and the line broadening of the excitonic photoluminescence we get new insights on the overlap of the opposite polarized lines (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cathodoluminescence of ZnSiOx nanocomposite films prepared on Si substrates
Authors: Kim Young‐Hwan , Cho Woon‐Jo , Kim Seong‐Il
Published: December 2008

Optoelectronic materials compatible with silicon substrates are important from the viewpoint of practical applications for silicon photonics. ZnO nanocrystals were fabricated directly on Si substrates by tuning both of the composition and postannealing conditions of ZnSiOx composite films deposited by sputtering Si and ZnO targets simultaneously. The high‐resolution TEM analysis showed that ZnSiOx nanocomposite film containing ZnO nanocrystals could be obtained by postannealing the ZnSiOx film with Zn/Si ratio = ∼1.6 at 700 °C. In this film, ZnO nanocrystals with a size of ∼5 nm, which could be identified as ZnO from electron diffraction pattern, were densely distributed in the amorphous matrix. This film exhibited a stronger and broader cathodoluminescence emission ranging from 350 nm to 550 nm compared to that of ZnO film fabricated with the same deposition conditions. These results lead to a practical application of ZnO nanocrystals to optoelectronic devices using Si substrates. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lithographic quantum dot for sensitive infrared photon detection
Authors: An Zhenghua , Ueda Takeji , Komiyama Susumu , Hirakawa Kazuhiko , Shen Xuechu
Published: December 2008

Semiconductor quantum dots (QDs) with discrete energy levels provide a promising solution for infrared photon detection. A lithographically defined QD with split conduction subbands has been utilized as a photo‐active floating gate in a phototransistor structure. Electrons inside the QD are excited by incident infrared photons via intersubband transition and thereby tunnel out of the QD, lowering its electrostatic potential. As a consequence, photo‐signal arises as an electrical current increment in the phototransistor channel. It has been found that this though simple scheme exhibits a high sensitivity which is sufficient for detecting individual infrared photons (λ ∼ 14 μm).

With continuous detection operation, more electrons are driven out of the QD. Eventually, the system approaches saturation due to over‐bended energy band profiles, therefore degrading the photo‐sensitivity. To alleviate this photo‐saturation effect, the QD electrostatic potential is controlled through a tuneable electrostatic potential barrier. Under illumination, the interplay between photo‐excitation and the potential barrier justifies the QD charge states, electrostatic potential and hence the channel current. It is found that, when the QD potential is externally lifted‐up, the device photo‐response can be enhanced clearly. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ramsey numbers of sparse hypergraphs
Authors: Conlon David , Fox Jacob , Sudakov Benny
Published: December 2008

We give a short proof that any k‐uniform hypergraph H on n vertices with bounded degree Δ has Ramsey number at most c(Δ,k)n, for an appropriate constant c(Δ,k). This result was recently proved by several authors, but those proofs are all based on applications of the hypergraph regularity method. Here we give a much simpler, self‐contained proof which uses new techniques developed recently by the authors together with an argument of Kostochka and Rödl. Moreover, our method demonstrates that, for k ≥ 4,

where the tower is of height k and the constant c depends on k. It significantly improves on the Ackermann‐type upper bound that arises from the regularity proofs, and we present a construction which shows that, at least in certain cases, this bound is not far from best possible. Our methods also allows us to prove quite sharp results on the Ramsey number of hypergraphs with at most m edges. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2009
Beyond the horizon
Authors: Timm Dianne M. , Junco Reynol
Published: December 2008

Student affairs professionals have an obligation and an opportunity to support students moving through the college‐years stages of psychosocial development by helping them use technology in appropriate ways.
The essential elements of team‐based learning
Authors: Michaelsen Larry K. , Sweet Michael
Published: December 2008

TBL is a collection of practices that support one another for powerful instructional effect. This chapter describes the building blocks of team‐based learning and the steps necessary to put them into place.
Soil respiration curves as soil fertility indicators in perennial central Amazonian plantations treated with charcoal, and mineral or organic fertilisers
Authors: Steiner Christoph , de Arruda Murilo Rodrigues , Teixeira Wenceslau G. , Zech Wolfgang
Published: December 2008

We assessed substrate‐induced respiration and soil chemical properties in order to study the influence of charcoal, nitrogen and phosphorus fertilisation on two different perennial crops in a confounded factorial design on a highly weathered Amazonian upland soil. Each plantation tested three different factors in three different levels making up 27 (33) treatment combinations. Whereas the banana plantation received mineral fertilisation in addition to charcoal applications (3rdfactor), the guarana (Paullinia cupana) plantation was fertilised organically using chicken manure and bone meal as the corresponding factors. Charcoal increased pH, total nitrogen, availability of sodium, zinc, manganese, copper and soil humidity, and decreased aluminium availability and acidity in the mineral‐fertilised plantation only. This caused a significant increase in basal respiration and microbial efficiency in terms of carbon dioxide release per microbial carbon in the soil. The microbial biomass, efficiency and population growth after substrate addition was significantly increased with increasing levels of organic fertiliser amendments. We conclude that charcoal is a valuable component especially in inorganic‐fertilised agricultural systems. Copyright © 2008 John Wiley & Sons, Ltd
Diagnosis, occurrence and seed transmission studies of viruses infecting four Centrosema species in Nigeria
Authors: Odedara OO , Hughes J d'A , Ayo‐John EI
Published: December 2008

In a survey to detect viruses affecting Centrosema species in two agroecological zones in Nigeria (the derived and northern guinea savanna zones: DSZ and NGSZ), enzyme‐linked immunosorbent assay of leaf samples of four species (C. brasilianum, C. pascuorum, C. pubescens and C. macrocarpum) revealed infections of two Potyviruses – Bean common mosaic virus and Cowpea aphid‐borne mosaic virus – and three Comoviruses – Cowpea mosaic virus, Cowpea severe mosaic virus and Bean pod mottle virus. Other viruses detected included: a Carmovirus, Cowpea mottle virus; a Cucumovirus, Cucumber mosaic virus (CMV); a Sobemovirus, Southern bean mosaic virus; and a Tobamovirus known as Tobacco mosaic virus (TMV). While no viruses were detected in leaf samples of C. brasilianum and C. pubescens collected from NGSZ, leaf samples of the same species collected from DSZ were highly infected, with the former being infected with seven viruses and the latter with all nine viruses tested for. Seed transmission studies of these viruses in Centrosema species showed CMV to be the most frequently detected, followed by TMV, and four different viruses were found in seeds of C. brasilianum in DSZ. The paper discusses the implications of these results for cropping of Centrosema legumes. Copyright © 2008 John Wiley & Sons, Ltd
First‐trimester maternal serum pregnancy‐associated plasma protein‐A and pre‐eclampsia
Authors: Poon L. C. Y. , Maiz N. , Valencia C. , Plasencia W. , Nicolaides K. H.
Published: December 2008

Objectives

To examine the relationship between low maternal serum pregnancy‐associated plasma protein‐A (PAPP‐A) and uterine artery pulsatility index (UtA‐PI) at 11 + 0 to 13 + 6 weeks with subsequent development of pre‐eclampsia (PE).

Methods

UtA‐PI and serum PAPP‐A were measured in women attending for routine care at 11 + 0 to 13 + 6 weeks of gestation. In the population, 156 (1.9%) women developed PE, including 32 (0.4%) in whom delivery was before 34 weeks (early PE) and 124 (1.5%) with delivery at 34 weeks or more (late PE); 7895 (98.1%) women had no PE. Regression analysis was used to examine which of the factors amongst maternal characteristics, log PAPP‐A multiples of the median (MoM) and log UtA‐PI MoM contributed to the prediction of PE.

Results

The median PAPP‐A MoM was 1.002 (interquartile range (IQR), 0.685–1.411) in the unaffected group, 0.555 (IQR, 0.463–0.922) in early PE and 0.911 (IQR, 0.580–1.247) in late PE. Serum PAPP‐A was below the 5th centile in 21.9% of early PE and 6.5% of late PE cases. The PAPP‐A‐related patient‐specific risk for PE was strongly influenced by maternal characteristics. There was a significant association between log UtA‐PI MoM and log PAPP‐A MoM (P = 0.001), and the detection rate of screening for PE by maternal variables and UtA‐PI was not improved by inclusion of PAPP‐A. Regression analysis was used to establish tables that allow modification of the maternal history and PAPP‐A‐related patient‐specific risk for PE by the measurement of UtA‐PI.

Conclusions

Low PAPP‐A is a marker for subsequent development of PE. The PAPP‐A‐related patient‐specific risk for PE can be modified by the measurement of UtA‐PI. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
A Bayesian Nonparametric Approach to Test Equating
Authors: Karabatsos George , Walker Stephen G.
Published: December 2008

A Bayesian nonparametric model is introduced for score equating. It is applicable to all major equating designs, and has advantages over previous equating models. Unlike the previous models, the Bayesian model accounts for positive dependence between distributions of scores from two tests. The Bayesian model and the previous equating models are compared through the analysis of data sets famous in the equating literature. Also, the classical percentile-rank, linear, and mean equating models are each proven to be a special case of a Bayesian model under a highly-informative choice of prior distribution.
Evaluation of endosonography as a new diagnostic tool for feline pancreatitis
Authors: Schweighauser Ariane , Gaschen Frédéric , Steiner Jörg , Allenspach Karin , Francey Thierry , Gaschen Lorrie
Published: December 2008

The purpose of this study was to evaluate endosonography (EUS) as a potential diagnostic tool for feline pancreatitis. Eleven healthy cats and six cats diagnosed with pancreatitis based on an increased serum feline pancreatic lipase immunoreactivity (fPLI) concentration were included. Transabdominal ultrasound (AUS) and EUS were performed in all cats. The widths of both pancreatic limbs and echogenicity and homogenicity were assessed by AUS and EUS. Finally, findings from both modalities were subjectively compared. In the healthy cats, the right pancreatic limb was significantly smaller on EUS compared to AUS. Also, subjectively, general visualization of the normal pancreas was superior with EUS and, the pancreatic margins and parenchyma could be resolved better with EUS in all sick patients. In this study, EUS findings did not alter the diagnosis in six cats with pancreatitis when compared to AUS. However, EUS may be useful in cases where AUS fails due to obesity, hyperechoic mesentery, or excessive intestinal gas.
Regulatory capitalism and the reassertion of the public interest
Authors: Levi-Faur David
Published: December 2008

Neoliberalism has not led to the retreat of the state but instead to the restructuring of the state. This has led to new forms of governance where regulation represents the expanding part of government, and where the various modes of governance compete and sometimes are synthesized into global forms of regulation. It will be discussed where such forms have emerged, and where they are yet to emerge. In this new order, best described as regulatory capitalism, the regulatory state meets the regulatory society and actors’ demand for and supply of regulation is ever expanding. Rule- making, monitoring and enforcement are becoming increasingly important for democratic policy making. It is being asserted that varieties of regulatory capitalism are produced by the interaction of varying degrees of civil- and state-regulation and variations in the composition of the networks that serve as the backbone that transform autonomous jurisdictions to interdependent ones. Accordingly the paper distinguishes between Corporatists, Pluralist, Command & Control and Laissez-Faire forms of regulatory capitalism.
The paradox of television privatization: When more is less
Authors: Feigenbaum Harvey B
Published: December 2008

The argument of this article is that privatization of the audiovisual sector has had unintended consequences. The proliferation of private television channels has fragmented advertising markets and created incentives for the increasing importation of cheap American programming. This phenomenon is evident despite the fact that the demand for such programming is eclipsed by audience preferences to see their own cultures on the small screen. Thus the paradox of television privatization is that, in cultural terms, it has led to less, rather than more, consumer choice. While the debates about Americanization have mostly dwelled on the loss of cultural diversity, the consequences for the domination of American popular culture have not only been the erosion of national identities, but also the transformation of local politics as people's political perceptions become increasingly affected by American political reference points and categories.
A theorem on approximation of irrational numbers by simple continued fractions
Authors: Tong Jingcheng
Published: December 2008

Let ξ be an irrational number with simple continued fraction expansion ξ= [a0;a1,a2,…], Pn/qn be its nth convergent, . The following two theorems were proved by Müller [9] and rediscovered by Bagemihl and McLaughlin [1]:

Theorem 1.For n>1,
A note on central idempotents in group rings II
Authors: Coelho Sônia P. , Milies C. Polcino
Published: December 2008

Let G be a group and K a field. We shall denote by U(KG) the group of units of the group ring of G over K. Also, if X is a group, T(X) will denote the torsion subset of X, i.e., the set of all elements of finite order in X.

Group theoretical properties of U(KG) have been studied intensively in recent years and it has been found that some conditions about U(KG) imply that T = T(G) must be a subgroup of G and that every idempotent of KT must be central in KG.
Groups with restriction on their infinite subnormal subgroups
Authors: Heineken Hermann
Published: December 2008

A groupGis called aBn-group, if all its subnormal subgroups are of defectn. If allinfinitesubnormal subgroups ofGhave defectn, we say thatGis anIBngroup. DeGiovanni and Franciosi [2] have considered solubleIBngroups and characterized them.
Localizations of essential extensions
Authors: Goodearl K. R. , Jordan D. A.
Published: December 2008

In an earlier paper [4] we considered the question of whether an injective module E over a noncommutative ring R remains injective after localization with respect to a denominator set X in R. A related question is whether, given an essential extension N of an R-module M, the localization N[X–1] must be an essential extension of M[X–1]. In [1] it is shown that if R is left noetherian and X is central in R, then localization at X preserves both injectivity and essential extensions of left R-modules and, hence, preserves injective hulls and minimal injective resolutions.
Boundary behaviour of harmonic functions and solutions of parabolic systems
Authors: Watson N. A.
Published: December 2008

In [1], Calderón proved that, if u is a harmonic function on Rn × ]0, ∞[, and at each point ξ of a subset E of Rn, u is bounded in some cone with vertex (ξ, 0), then u has a nontangential limit at almost every point of E × {0}. The main result of this note is a stronger version of this theorem, in which the hypotheses remain unchanged but the nontangential limits in the conclusion are replaced by limits through the more general approach regions first considered by Nagel and Stein in [7].
Convolution operators with trigonometric spline kernels
Authors: Goodman T. N. T. , Lee S. L.
Published: December 2008

The Bernstein polynomials are algebraic polynomial approximation operators which possess shape preserving properties. These polynomial operators have been extended to spline approximation operators, the Bernstein-Schoenberg spline approximation operators, which are also shape preserving like the Bernstein polynomials [8].
Further elementary techniques using the miracle octad generator
Authors: Curtis R. T.
Published: December 2008

In this paper we describe various techniques, some of which are already used by devotees of the art, which relate certain maximal subgroups of the Mathieu group M24, as seen in the MOG, to matrix groups over finite fields. We hope to bring out the wealth of algebraic structure underlying the device and to enable the reader to move freely between these matrices and permutations. Perhaps the MOG was mis-named as simply an “octad generator”; in this paper we intend to show that it is in reality a natural diagram of the binary Golay code.
Rings characterized by their right ideals or cyclic modules
Authors: Van Huynh Dinh , Dung Nguyen V. , Smith Patrick F.
Published: December 2008

It is well known that a ring R is semiprime Artinian if and only if every right ideal is an injective right R-module. In this paper we shall be concerned with the following general question: given a ring R all of whose right ideals have a certain property, what implications does this have for the ring R itself? In practice, it is not necessary to insist that all right ideals have the property, usually the maximal or essential right ideals will suffice. On the other hand, Osofsky proved that a ring R is semiprime Artinian if and only if every cyclic right R-module is injective. This leads to the second general question: given a ring R all of whose cyclic right R-modules have a certain property, what can one say about R itself?
On pseudo-finite near-fields which have finite dimension over the centre
Authors: Fuchs Peter
Published: December 2008

In [1] J. Ax studied a class of fields with similar properties as finite fields called pseudo-finite fields. One can prove that pseudo-finite fields are precisely the infinite models of the first-order theory of finite fields. Similarly a near-field F is called pseudo-finite if F is an infinite model of the first-order theory of finite near-fields. The structure theory of these near-fields has been initiated by U. Feigner in [5].
Metric spaces and ideals of functions
Authors: Kaufman R.
Published: December 2008

In each metric space (X, d) there is defined the space LipXof complex-valued, bounded, and uniformly Lipschitzian functions. In the algebra LipX, it is natural to ask for ideals closed in various notions of convergence, and also to identify the invertible elements. In particular, are the invertible elements exactly those with no zero inX? Wiener's Tauberian Theorem in Fourier analysis is the first and most remarkable example of this harmonious state of affairs. A moment's reflection confirms that, for the algebra LipX, this is true only for compact metric spacesX, the trivial examples in our investigation. We therefore introduce a type of convergence weaker than convergence in norm; it has already proved useful in some problems in descriptive set theory and reflects in a subtle way the metric properties ofX. A sequence (fn) in LipX converges stronglytog, writtens– limfn=g, if ∥fn∥≦Cin the Banach space LipXand limfn(x)=g(x)for each elementxofX. In Section 3 we explain how this is really a type of convergence in the dual space of a certain Banach space. This brings us to the edge of some recondite questions about iterated (or even transfinite) limits, and we have adhered to the notion of strong limits to avoid these questions. To illustrate the differences between these two approaches, we mention this problem: which maximal ideals of LipXare closed with respect to strong convergence of sequences? This isnotthe problem studied in Section 1.
Invariant subspace theorems for amenable groups
Authors: Lau A. T. , Paterson A. L. T. , Wong J. C. S.
Published: December 2008

In [5], Ky Fan proved the following remarkable amenability “invariant subspace” theorem:

Let G be an amenable group of continuous, invertible linear operators acting on a locally convex space E. Let H be a closed subspace of finite codimension n in E and X⊂E be such that:

(i) H and X are G-invariant;

(ii) (e + H) ∩X is compact convex for all e ∈ E;

(iii) X contains an n-dimensional subspace V of E. Then there exists an n-dimensional subspace of E contained in X and invariant under G.
Vanishing l1-sums of the Poisson kernel, and sums with positive coefficients
Authors: Bonsall F. F. , Walsh D.
Published: December 2008

For z in D and ζ in ∂D, we denote by pz(ζ) the Poisson kernel (1 − │z│2)│1 − z̄ζ−2 for the open unit disc D. We ask for what countable sets {an:n∈ℕ} of points of D there exist complex numbers λn with

by which we mean that the series converges to zero in the norm of L1(∂D).
Atomic spaces and spectra
Authors: Adams J. F. , Kuhn N. J.
Published: December 2008

1. The subject-matter of this paper is in some sense known; but we will try to organise, explain and reprove it, and to give examples.
A Schur-Cohn theorem for matrix polynomials
Authors: Dym Harry , Young Nicholas
Published: December 2008

Let N(λ) be a square matrix polynomial, and suppose det N is a polynomial of degree d. Subject to a certain non-singularity condition we construct a d by d Hermitian matrix whose signature determines the numbers of zeros of N inside and outside the unit circle. The result generalises a well known theorem of Schur and Cohn for scalar polynomials. The Hermitian “test matrix” is obtained as the inverse of the Gram matrix of a natural basis in a certain Krein space of rational vector functions associated with N. More complete results in a somewhat different formulation have been obtained by Lerer and Tismenetsky by other methods.
Asymptotic distribution of Liusternik-Schnirelman eigenvalues for elliptic nonlinear operators
Authors: Moscatelli V. B. , Thompson M.
Published: December 2008

Asymptotic formulae are given for the distribution of Liusternik-Schnirelman eigenvalues of certain pairs of nonlinear functionals generalising the usual Weyl theory for linear pairs of elliptic operators. In particular an application is made to the von Kármán theory of buckled plates.
Measure valued solutions of asymptotically homogeneous semilinear hyperbolic systems in one space variable
Authors: Demengel F. , Rauch J.
Published: December 2008

We study systems which in characteristic coordinates have the form

where A is a k × k diagonal matrix with distinct real eigenvalues. The nonlinearity F is assumed to be asymptotically homogeneous in the sense, that it is a sum of two terms, one positively homogeneous of degree one in u and a second which is sublinear in u and vanishes when u = 0. In this case, F(t, x, u(t)) is meaningful provided that u(t) is a Radon measure, and, for Radon measure initial data there is a unique solution (Theorem 2.1).

The main result asserts that if μn is a sequence of initial data such that, in characteristic coordinates, the positive and negative parts of each component, , converge weakly to μ±, then the solutions coverge weakly and the limit has an interesting description given by a nonlinear superposition principle.

Simple weak converge of the initial data does not imply weak convergence of the solutions.
Bilateral Laplace multipliers on spaces of distributions
Authors: Schiavone S. E.
Published: December 2008

A bilateral Laplace multiplier theory, based on Rooney's class , is developed for certain operators defined on the Fréchet spaces Dp,μ. The theory is applied to Riesz fractional integrals associated with the one-dimensional wave operator.
The exponent of certain finite p-groups
Authors: York I. O.
Published: December 2008

In this paper, for R a commutative ring, with identity, of characteristic p, we look at the group G(R) of formal power series with coefficients in R, of the form

and the group operation being substitution. The results obtained give the exponent of the quotient groups Gn(R) of this group, n∈ℕ.
The length of the continued fraction expansion for a class of rational functions in
Authors: Knopfmacher Arnold
Published: December 2008

A study is made of the length L(h, k) of the continued fraction algorithm for h/k where h and k are co-prime polynomials in a finite field. In addition we investigate the sum of the degrees of the partial quotients in this expansion for h/k, h, k in . The above continued fraction is determined by means of the Euclidean algorithm for the polynomials h, k in .
Reflexive ideals and injective modules over Noetherian v-H orders
Authors: Brown K. A. , Haghany A. , Lenagan T. H.
Published: December 2008

The class of prime Noetherian v-H orders is a class of Noetherian prime rings including the commutative integrally closed Noetherian domains, and the hereditary Noetherian prime rings, and designed to mimic the latter at the level of height one primes. We continue recent work on the structure of indecomposable injective modules over Noetherian rings by describing the structure of such a module E over a prime Noetherian v-H order R in the case where the assassinator P of E is a reflexive prime ideal. This description is then applied to a problem in torsion theory, so generalising work of Beck, Chamarie and Fossum.
Representable divisibility semigroups
Authors: Bosbach Bruno
Published: December 2008

By a divisibility semigroup we mean an algebra (S,., ∧) satisfying (Al) (S,.) is a semigroup; (A2) (S, ∧) is a semilattice; (A3).

A divisibility semigroup is called representable if it admits a subdirect decomposition into totally ordered factors.

In this paper various types of representable divisibility semigroups are investigated and characterized, admitting a representation in general or even a special decomposition, like subdirect sums of archimedean factors, for instance.
Totally geodesic surfaces in hyperbolic 3-manifolds
Authors: Reid Alan W.
Published: December 2008

In this paper we investigate totally geodesic surfaces in hyperbolic 3-manifolds. In particular we show that if M is a compact arithmetic hyperbolic 3-manifold containing an immersion of a totally geodesic surface then it contains infinitely many commensurability classes of such surfaces. In addition we show for these M that the Chern-Simons invariant is rational.

We also show, that unlike the figure-eight knot complement in S3, many knot complements in S3 do not contain an immersion of a closed totally geodesic surface.
Existence of solutions of extremal problems in H1
Authors: Nakazi Takahiko
Published: December 2008

An essentially bounded function on the unit circle gives a continuous linear functional on the Hardy space H1. In this paper we study when there exists at least one function which attains its norm. We apply the results to an interpolation problem, Hankel operators and a characterization of exposed points of the closed unit ball of H1.
Subnormal subgroups of En(R) have no free, non-abelian quotients, when n≧3
Authors: Mason A. W.
Published: December 2008

It is known that for certain rings R (for example R = ℤ, the ring of rational integers) the group GL2(R) contains subnormal subgroups which have free, non-abelian quotients. When such a subgroup has finite index it follows that every countable group is embeddable in a quotient of GL2(R). (In this case GL2(R) is said to be SQ-universal.) In this note we prove that the existence of subnormal subgroups of GL2(R) with this property is a phenomenon peculiar to “n = 2”.

For a large class of rings (which includes all commutative rings) it is shown that, for all , no subnormal subgroup of En(R) has a free, non-abelian quotient, when n≧3. (En(R) is the subgroup of GLn(R) generated by the elementary matrices.) In addition it is proved that, if is an SRt-ring, for some t ≧ 2, then no subnormal subgroup of GLn(R) has a free, non-abelian quotient, when n ≧ max (t, 3). From the above these results are best possible since ℤ is an SR3 ring.
On the maximal monotonicity and the range of the sum of nonlinear maximal monotone operators
Authors: Webb J. R. L. , Zhao Weiyu
Published: December 2008

Conditions are given on two maximal monotone (multivalued) operators A and B which ensure that A + B is also maximal. One condition used is that ∥Bx∥≦k(∥x∥)Ax| +d|(A + B)x| + c(∥x∥) for every x∈D(A)⊆D(B), where 0≦k(r)<1, and c(r)≧0 are nondecreasing functions, and 0≦d≦1 is a constant. Here, for a set C, |C| denotes inf{∥y∥:y∈C}. This extends the well known result which has d = 0 (and is used in the proof here). The second part of the paper uses similar hypotheses to give conditions under which the range of the sum, R(A + B), has the same interior and same closure as the sum of the ranges, R(A) + R(B).
Subsemigroups of free products of semigroups
Authors: Renshaw James
Published: December 2008

Given amalgams of semigroups [U; Ti] and [U;Si] with U⊆Ti⊆Si, it was proved by Howie in [6] that need not be embedded in . We use the homological techniques developed by Renshaw in [7, 9] and study three new conditions each of which imply the embeddability of the above free products.
Approximation and spectral properties of periodic spline operators
Authors: Lee S. L. , Tang W. S.
Published: December 2008

We consider discrete convolution operators whose range is the k-dimensional space spanned by the translates of a single function. Examples of include the space of trigonometric polynomials, periodic polynomial splines and trigonometric splines. The eigenfunctions of these operators corresponding to the nonzero eigenvalues are independent of α, and they form an orthogonal basis for . The limiting behaviour of as α, k→∞, is also considered. The corresponding limiting semigroups are computed explicitly.
Similarité entre l'algèbre de Volterra et un quotient d'algèbre uniforme
Authors: Koua Konin
Published: December 2008

Two commutative Banach algebras A and B are said to be similar if there exists a Banach algebra D such that [xD]− = D for some x in D, and two one-to-one continuous homomorphisms φ:D→A and ψ:D→B such that φ(D) is a dense ideal of A and ψ(D) a dense ideal of B.

We prove in this paper that the Volterra algebra is similar to A0/e-z A0 where A0 is the commutative uniform, separable Banach algebra of all continuous functions on the closed right-hand half plane , analytic on H and vanishing at infinity. We deduce from this result that multiplication by an element of A0/e-z A0 is a compact mapping.
Multiplicity results for semilinear elliptic boundary value problems in Besov and Triebel-Lizorkin spaces
Authors: Päivärinta L. , Runst T.
Published: December 2008

The paper deals with superlinear elliptic boundary value problems depending on a parameter. Given appropriate hypotheses concerning the asymptotic behaviour of the nonlinearity, we prove lower bounds on the number of solutions. The results generalize a theorem due to Lazer and McKenna within the framework of quasi-Banach spaces of Besov and Triebel-Lizorkin spaces.
Some observations on algorithms of the Gauss-Borchardt type
Authors: Peetre Jaak
Published: December 2008

A one parameter family of algorithms is studied, which contains both the arithmetic-geometric mean of Gauss and its generalization by Borchardt, recently studied by J. and P. Borwein. We prove that the presence of an asymptotic formula for such an algorithm is, in view of the Poisson summation formula, equivalent to the vanishing of certain integrals. In the case of Gauss and Borchardt the latter involve theta functions. Finally, we investigate the question of convergence of the algorithm for complex values, thereby generalizing the corresponding result of Gauss.
On large deviations in Hilbert space
Authors: Cutland Nigel J.
Published: December 2008

Nonstandard methods and a flat integral representation are used to give a simple and intuitive proof of the large deviation principle for a Gaussian measure on a separable Hilbert space.
Aspherical relative presentations
Authors: Bogley W. A. , Pride S. J.
Published: December 2008

A geometric hypothesis is presented under which the cohomology of a groupGgiven by generators and defining relators can be computed in terms of a groupHdefined by a subpresentation. In the presence of this hypothesis, which is framed in terms of spherical pictures, one has thatHis naturally embedded inG, and that the finite subgroups ofGare determined by those ofH. Practical criteria for the hypothesis to hold are given. The theory is applied to give simple proofs of results of Collins-Perraud and of Kanevskiĭ. In addition, we consider in detail the situation whereGis obtained fromHby adjoining a single new generatorxand a single defining relator of the formxaxbxεc, wherea, b, c ∈ Hand |ε| = 1.
A spectral mapping theorem for some representations of compact abelian groups
Authors: Takahasi Sin-Ei , Inoue Jyunji
Published: December 2008

We show that if G is a compact abelian group and U is a weakly continuous representation of G by means of isometries on a Banach space X, then holds for each measure µ in reg(M(G)), where π(µ) denotes the generalized convolution operator in B(X) defined by , σ the usual spectrum in B(X), sp(U) the Arveson spectrum of U, the Fourier-Stieltjes transform of µ and reg(M(G)) the largest closed regular subalgebra of the convolution measure algebra M(G) of G. reg(M(G)) contains all the absolutely continuous measures and discrete measures.
On the moduli of continuity ofHpfunctions with 0<p<1
Authors: Pavlović Miroslav
Published: December 2008

We prove two inequalities which relate theLpmodulus of continuity ofn-th order, ωn(f,·)p, of anHpfunctionfwith thep-th mean values of then-th derivativef(n). Using these inequalities we extend classical results of Hardy and Littlewood [5], Gwiliam [4], Zygmund [13] and Taibleson [12] as well as a recent result of Oswald [6].
A decomposition property of weak Lî
Authors: Peck N. T.
Published: December 2008

Let be a set of disjointly supported, positive functions in the Banach envelope of weak L1. We prove that each fi can be written as ei + gi where ei and gi, are disjointly supported and satisfy these additional properties: the ei's are isometrically the basis in the envelope norm; the envelope norm of a linear combination of the gi's is equal to the envelope norm of the corresponding combination of the fi's.
Oscillations in a nonautonomous delay logistic difference equation
Authors: Philos Ch. G.
Published: December 2008

Consider the nonautonomous delay logistic difference equation

where (pn)n≧0is a sequence of nonnegative numbers, (ln)n≧0is a sequence of positive integers with limn→∞(n−ln) = ∞ andKis a positive constant. Only solutions which are positive forn≧0 are considered. We established a sharp condition under which all solutions of (E0) are oscillatory about the equilibrium pointK. Also we obtained sufficient conditions for the existence of a solution of (E0) which is nonoscillatory aboutK.
Continuous dependence results for a class of evolution inclusions
Authors: Papageorgiou Nikolaos S.
Published: December 2008

In this paper we examine the dependence of the solutions of an evolution inclusion on a parameter λ We prove two dependence theorems. In the first the parameter appears only in the orientor field and we show that the solution set depends continuously on it for both the Vietoris and Hausdorff topologies. In the second the parameter appears also in the monotone operator. Using the notion of G-convergence of operators we prove that the solution set is upper semicontinuous with respect to the parameter. Both results make use of a general existence theorem which we also prove in this paper. Finally, we present two examples. One from control theory and the other from partial differential inclusions.
Left ideals and 0-primitivity in matrix near-rings
Authors: Meyer J. H.
Published: December 2008

Maximal left ideals in matrix rings were studied by Stone [10]. Similar results are not necessarily valid in the general near-ring case and one of the objectives of this paper is to study these differences. Furthermore, although much is known about 2-primitivity in general matrix near-rings (Van der Walt [11]), quite the opposite is true for 0-primitivity and the other objective of this paper is to present some results on 0-primitivity in matrix near-rings in certain restricted cases.