bluuebunny/crossref_metadata_2025 huggingface dataset:
Melt Spinning of Bacterial Aliphatic Polyester Using Reactive Extrusion for Improvement of Crystallization
Authors: Vogel Roland , Tändler Bernhard , Voigt Dieter , Jehnichen Dieter , Häußler Liane , Peitzsch Lutz , Brünig Harald
Published: May 2007

This paper reports on an attempt to use reactive extrusion with peroxide as a comfortable pathway for improvement of the crystallization of poly(3‐hydroxybutyrate) in a melt spinning process. At first, rheological and thermal properties of the modified melts are determined in order to assess the effect of nucleation. Then spinning tests are carried out. Molecular weights and molecular weight distributions of the spun fibers are determined by chromatographic methods. Average crystallite size is measured by wide angle X‐ray scattering. Thermal and textile properties of the spun PHB fibers are also determined. An estimation of the improvement of the crystallization in the spinline and of the inhibition of the secondary crystallization in the fibers from the use of the described way of reactive extrusion is given.

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In Situ Micro‐Sized Gel‐Forming Injectable Implant Using Biodegradable Amphiphilic Graft Copolymer
Authors: Cho Kuk Young , Lee Seongnam , Park Jung‐Ki
Published: May 2007

A synthesized graft polymer is used as a biodegradable polymer for an in situ gel‐forming injectable implant system. The amphiphilic character of the polymer in the graft structure lowered the viscosity of the polymer solution, which enabled easy injection. A micro‐sized gel can be obtained with this system, which has not been found for previous in situ gel‐forming systems with poly[(D,L‐lactide)‐co‐glycolide] copolymer. In addition, a protein particle embedded gel exhibits good in vitro drug release performance as a result of the enhanced stability and shorter diffusion length.

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Embeddings in the Strong Reducibilities Between 1 and npm
Authors: Watson Phil
Published: May 2007

We consider the strongest (most restricted) forms of enumeration reducibility, those that occur between 1‐ and npm‐reducibility inclusive. By defining two new reducibilities (which we call n1‐ and ni‐reducibility) which are counterparts to 1‐ and i‐reducibility, respectively, in the same way that nm‐ and npm‐reducibility are counterparts to m‐ and pm‐reducibility, respectively, we bring out the structure (under the natural relation on reducibilities strong with respect to') of the strong reducibilities. By further restricting n1‐ and nm‐reducibility we are able to define infinite families of reducibilities which isomorphically embed the r. e. Turing degrees. Thus the many well‐known results in the theory of the r. e. Turing degrees have counterparts in the theory of strong reducibilities. We are also able to positively answer the question of whether there exist distinct reducibilities ≤y and ≤a between ≤e and ≤m such that there exists a non‐trivial ≤y‐contiguous ≤z degree.
Computability of String Functions Over Algebraic Structures Armin Hemmerling
Authors: Hemmerling Armin
Published: May 2007

We present a model of computation for string functions over single‐sorted, total algebraic structures and study some basic features of a general theory of computability within this framework. Our concept generalizes the Blum‐Shub‐Smale setting of computability over the reals and other rings. By dealing with strings of arbitrary length instead of tuples of fixed length, some suppositions of deeper results within former approaches to generalized recursion theory become superfluous. Moreover, this gives the basis for introducing computational complexity in a BSS‐like manner. Relationships both to classical computability and to Friedman's concept of eds computability are established. Two kinds of nondeterminism as well as several variants of recognizability are investigated with respect to interdependencies on each other and on properties of the underlying structures. For structures of finite signatures, there are universal programs with the usual characteristics. For the general case of not necessarily finite signature, this subject will be studied in a separate, forthcoming paper.
Predicate Modal Logics Do Not Mix Very Well
Authors: Gasquet Olivier
Published: May 2007

The problem of completeness for predicate modal logics is still under investigation, although some results have been obtained in the last few years (cf. [2, 3, 4, 7]). As far as we know, the case of multimodal logics has not been addressed at all. In this paper, we study the combination of modal logics in terms of combining their semantics. We demonstrate by a simple example that in this sense predicate modal logics are not so easily manipulated as propositional ones: mixing two Kripke‐complete predicate modal logics (one with the Barcan formula, and the other without) results in a Kripke‐incomplete system.
Quadrilaterizing an Orthogonal Polygon in Parallel
Authors: Dietel Jana , Hecker Hans‐Dietrich
Published: May 2007

We consider the problem of quadrilaterizing an orthogonal polygon P, that is to decompose P into nonoverlapping convex quadrangles without adding new vertices. In this paper we present a CREW‐algorithm for this problem which runs in O(log N) time using Θ(N/log N) processors if the rectangle decomposition of P is given, and Θ(N) processors if not. Furthermore we will show that the latter result is optimal if the polygon is allowed to contain holes.
Extending Independent Sets to Bases and the Axiom of Choice
Authors: Keremedis Kyriakos
Published: May 2007

We show that the both assertions “in every vector space B over a finite element field every subspace V ⊆ B has a complementary subspace S” and “for every family 𝒜 of disjoint odd sized sets there exists a subfamily ℱ={Fj:j ϵω} with a choice function” together imply the axiom of choice AC. We also show that AC is equivalent to the statement “in every vector space over ℚ every generating set includes a basis”.
S‐Storage Operators
Authors: Nour Karim
Published: May 2007

In 1990, J. L. Krivine introduced the notion of storage operator to simulate, for Church integers, the “call by value” in a context of a “call by name” strategy. In the present paper we define for every λ‐term S which realizes the successor function on Church integers the notion of S‐storage operator. We prove that every storage operator is an S‐storage operator. But the converse is not always true.
On Shattering, Splitting and Reaping Partitions
Authors: Halbeisen Lorenz
Published: May 2007

In this article we investigate the dual‐shattering cardinal ℌ, the dual‐splitting cardinal 𝔖 and the dual‐reaping cardinal 𝔎, which are dualizations of the well‐known cardinals 𝔥 (the shattering cardinal, also known as the distributivity number of P(ω)/fin), s (the splitting number) and 𝔠 (the reaping number). Using some properties of the ideal 𝔍 of nowhere dual‐Ramsey sets, which is an ideal over the set of partitions of ω, we show that add(𝔍) = cov(𝔍) = ℌ. With this result we can show that ℌ > ω1 is consistent with ZFC and as a corollary we get the relative consistency of ℌ > 𝔱 t, where t is the tower number. Concerning 𝔖 we show that cov(M) ⩽ 𝔖 𝔯 (where M is the ideal of the meager sets). For the dual‐reaping cardinal 𝔖 we get p 𝔖 ⩽ 𝔭 ⩽ 𝔯 (where 𝔭 is the pseudo‐intersection number) and for a modified dual‐reaping number 𝔖′ we get 𝔖′ ⩽ 𝔬 (where 𝔬 is the dominating number). As a consistency result we get 𝔖 < cov(𝔐).
Grasping Infinity by Finite Sets
Authors: Formato Ferrante , Gerla Giangiacomo
Published: May 2007

We show that the existence of an infinite set can be reduced to the existence of finite sets “as big as we will”, provided that a multivalued extension of the relation of equipotence is admitted. In accordance, we modelize the notion of infinite set by a fuzzy subset representing the class of (finite) wide sets.
Computability Over Structures of Infinite Signature
Authors: Hemmerling Armin
Published: May 2007

Continuing the paper [7], in which the Blum‐Shub‐Smale approach to computability over the reals has been generalized to arbitrary algebraic structures, this paper deals with computability and recognizability over structures of infinite signature. It begins with discussing related properties of the linear and scalar real structures and of their discrete counterparts over the natural numbers. Then the existence of universal functions is shown to be equivalent to the effective encodability of the underlying structure. Such structures even have universal functions satisfying the s‐m‐n theorem and related features. The real and discrete examples are discussed with respect to effective encodability. Megiddo structures and computational extensions of effectively encodable structures are encodable, too. As further variants of universality, universal functions with enumerable sets of program codes and such ones with constructible codes are investigated. Finally, the existence of m‐complete sets is shown to be independent of the effective encodability of structures, and the linear and scalar structures are discussed once more, under this aspect.
Choice Principles and Compactness Conditions
Authors: Banaschewski Bernhard
Published: May 2007

It is shown in Zermelo‐Fraenkel Set Theory that Cκ, the Axiom of Choice for κ‐indexed families of arbitrary sets, is equivalent to the condition that the frame envelope of any κ‐frame is κ‐Lindelöf, for any cardinal κ.
Other Proofs of Old Results
Authors: Kotlarski Henryk
Published: May 2007

We transform the proof of the second incompleteness theorem given in [3] to a proof‐theoretic version, avoiding the use of the arithmetized completeness theorem. We give also new proofs of old results: The Arithmetical Hierarchy Theorem and Tarski's Theorem on undefinability of truth; the proofs in which the construction of a sentence by means of diagonalization lemma is not needed.
Infinite Projection Properties
Authors: Delhommé Christian
Published: May 2007

A structure 𝔄 is κ‐projective if the projections are the only retraction of 𝔄κon its diagonal. We investigate projectivity with respect to infinite exponents.
Variants of Visibility and their Complexity
Authors: Schuchardt Dietmar , Hecker Hans‐Dietrich
Published: May 2007

First we give an overview about variants of visibility and related problems. Then we prove that some guarding and covering problems are NP‐hard for ortho‐polygons with holes, using a so‐called vertex cover technique.
An Algorithm for Simulating Equilibrium Adsorption Characteristics of Branched Copolymer Chains at Solid‐Liquid Interface
Authors: Austine Juedu , Mohite Lalaso V. , Juvekar Vinay A.
Published: May 2007

An algorithm is developed for simulating adsorption of tree type block‐branched copolymer chains, of arbitrary architecture, from dilute solutions to solid surfaces. A continuum form of the self‐consistent field (SCF) theory is used. The chain architecture is first represented by a convergent tree‐graph, which is then converted into a special type of the connectivity matrix. This matrix is used for computing the configurational statistics of the chains in the adsorbed layer. The crucial step in the algorithm is to compute the junction (branch point) probability weights. A stepwise procedure for computing these probability weights is described. The capability of the algorithm has been demonstrated using illustrative examples.

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Monte Carlo Simulation of Uniaxial Deformation of Polyethylene‐Like Polymer Glass: Role of Constraints and Deformation Protocol
Authors: Mulder Tim , Li Jing , Lyulin Alexey V. , Michels Matthias A. J.
Published: May 2007

The deformation of a glassy amorphous polymer has been simulated by Monte Carlo. A molecular model with constrained chemical bonds (rigid‐bond model) and one with chemical bonds represented by Gaussian springs (flexible‐bond model) have been compared. Furthermore, two different deformation protocols have been tested. Comparisons on the basis of stress–strain behavior, contributions of various interactions to stress and energy, evolution of density and distribution of dihedral angles, and of pair correlation functions show that both the introduction of constrained bonds and the deformation protocol influence the results dramatically. The results obtained using the flexible‐bond model, employing a deformation protocol in which all the monomers are displaced affinely with the box size, show the best agreement with experimental facts.

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Monte Carlo Simulation of Controlled/Living Radical Polymerization in Emulsified Systems
Authors: Tobita Hidetaka , Yanase Fumihiko
Published: May 2007

A new MC simulation method is proposed for the controlled/living radical polymerization in a dispersed medium, assuming an ideal miniemulsion system. This tool is used to consider the effects of particle size on the polymerization rates and the molecular weight distributions. For NMP, the polymerization kinetics are basically governed by two conflicting factors, (i) the confined space effect that promotes the coupling reaction between a radical and a trapping agent and (ii) the isolation effect of radicals into different particles that suppresses the overall frequency of bimolecular termination. For RAFT polymerization, a significant rate enhancement by reducing the particle size could be observed only for the systems with fast fragmentation of adduct radicals.

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Rescuing America's public service
Authors: Light Paul
Published: May 2007

Merely raising the salary of public employees will not be adequate to attract young people to public service. Political scandal and campaign rhetoric critical of bureaucrats and public servants not only depress the appeal of career public service, but also discourage young people from public life In general. Even If salaries are raised and respect restored, public employment must offer meaningful challenge and room for advancement.
The politics of community
Authors: Mathews David
Published: May 2007

In this adaptation of his plenary remarks to the 94th National Conference on Government David Mathews, president and chief executive officer of the Kettering Foundation, identifies unique political instincts demonstrated by people who approach public involvement in unconventional ways, who have faith in the power of the community, and who work for the engagement of citizens in public decision making.
Small local governments as community builders
Authors: Sokolow Alvin D.
Published: May 2007

While small local governments lack the advantages of revenue base, adequate staff, and professionalization, the limitations of small size are replaced by its advantages: proximity to constituency, responsiveness, and flexibility. The external (federal) assistance of the 1970s helped bring about substantial local improvements and surety aided community‐building efforts. Nonetheless, major small‐town projects continue to be driven by local priorities and views; success of such efforts depends on the quality of local leadership and the leadership agenda itself, volunteer action, multiple assignments to public employees, and ad hoc‐but effective—administration.
Defining the public interest: Citizen participation in metropolitan and state policy making
Authors: Persons Georgia A.
Published: May 2007

The legitimacy of policy making at the regional level, as with policy making at more conventional levels of government, depends on the quality of representation. Citizen appointments and voluntary committees bypass the expense of the electoral process, but lack value when restricted to token advisory roles in potential conflict with other, “financially articulate” interests. Experience shows that lay citizen representatives can make sound decisions on the technical issues that typify regional problems, when information is properly shared. Regional entities must demonstrate the will to establish their legitimacy.
It's never too late to run — and win! the graying of women in local politics
Authors: Macmanus Susan A.
Published: May 2007

Older women are playing an increasingly significant role in Florida local politics. This phenomenon has implications for politics — both local and at other levels — nationwide. As the national age profile continues to resemble Florida's, intergenerational conflict may become the norm as a smaller group of working‐age taxpayers are expected to accept the policies of a less conservative population of retires and older politicians.
The dawn of public journalism
Authors: Fouhy Ed
Published: May 2007

How do the traditional news media maintain their relevance and appeal in an age of specialized “information‐on‐demand”? Public or civic journalism has been the answer in several media markets, involving partnerships among newspapers, television and radio broadcasters, and the communities they serve.
Federal policy and community involvement. Responding to national economic and social trends
Authors: Pisano Mark
Published: May 2007

If national policies can be implemented in ways that respect the integrity of regional communities and acknowledge the essential relationships among individuals in communities, American can be healed by advancing both social and economic interests.
An element‐wise, locally conservative Galerkin (LCG) method for solving diffusion and convection–diffusion problems
Authors: Thomas C. G. , Nithiarasu P.
Published: May 2007

An element‐wise locally conservative Galerkin (LCG) method is employed to solve the conservation equations of diffusion and convection–diffusion. This approach allows the system of simultaneous equations to be solved over each element. Thus, the traditional assembly of elemental contributions into a global matrix system is avoided. This simplifies the calculation procedure over the standard global (continuous) Galerkin method, in addition to explicitly establishing element‐wise flux conservation. In the LCG method, elements are treated as sub‐domains with weakly imposed Neumann boundary conditions. The LCG method obtains a continuous and unique nodal solution from the surrounding element contributions via averaging. It is also shown in this paper that the proposed LCG method is identical to the standard global Galerkin (GG) method, at both steady and unsteady states, for an inside node. Thus,
the method, has all the advantages of the standard GG method while explicitly conserving fluxes over each element.

Several problems of diffusion and convection–diffusion are solved on both structured and unstructured grids to demonstrate the accuracy and robustness of the LCG method. Both linear and quadratic elements are used in the calculations. For convection‐dominated problems, Petrov–Galerkin weighting and high‐order characteristic‐based temporal schemes have been implemented into the LCG formulation. Copyright © 2007 John Wiley & Sons, Ltd.
Thermally irreversible organic photochromic compounds for optical memory
Authors: Barachevsky V. A. , Strokach Yu. P. , Puankov Yu. A. , Krayushkin M. M.
Published: May 2007

For some photochromic compounds (58 diarylethenes and 9 fulgimides), the results of our spectral and kinetic studies are presented. Aiming at targeted synthesis of new photochromic compounds, the structure – photochromic behavior relationship (SPBR) for the synthesized compounds has been analyzed. The perspectives for application of these compounds in development of recording media for use in optical memory devices are outlined. Copyright © 2007 John Wiley & Sons, Ltd.
Relative stabilities and molecular structures of the isomeric enol ethers and carboxylic esters derived from α‐acetyl‐γ‐butyrolactone and α‐acetyl‐δ‐valerolactone
Authors: Taskinen Esko
Published: May 2007

Recently recorded 17O NMR spectra of compounds studied in a previous work (Taskinen E. Acta Chem. Scand. 1985; B39: 489–494) dealing with the thermodynamics of isomerization of the enol ethers of α‐acetyl‐γ‐butyrolactone reveal an error in compound identification, caused by an unexpected isomerization reaction during the synthetic procedure. Thus, acid‐catalyzed treatment of the lactone with HC(OR)3 in the respective alcohol ROH is shown to lead initially to the desired enol ethers which, however, are gradually isomerized to a mixture of the enol ethers and an ester of 2‐methyl‐4,5‐dihydrofuran‐3‐carboxylic acid. As a result, only one of the two isomeric compounds detected in the previous equilibration study was the expected enol ether (the thermodynamically more stable E isomer) of α‐acetyl‐γ‐butyrolactone, while the other, dominating species was the respective carboxylic ester. In the present work, the evidence provided by the 17O NMR spectra is presented, and the relative stabilities of the isomeric compounds are discussed on the basis of computational enthalpy data. The treatment is also extended to the respective isomeric compounds derived from α‐acetyl‐δ‐valerolactone. Copyright © 2007 John Wiley & Sons, Ltd.
Kinetics and mechanism of the reaction of an arenediazonium ion with hydrophilic aminocarboxylic acids in aqueous buffered solution
Authors: Fernández‐Alonso Alejandra , Bravo‐Díaz Carlos
Published: May 2007

The reaction of 4‐nitrobenzenediazonium ion, 4NBD, with the aminocarboxylic acids (AA) glycine and serine was studied under acidic conditions by using Linear Sweep Voltammetry (LSV), which allows simultaneous monitoring of 4NBD loss and product formation. Voltammograms of the reaction mixture are complex, showing up to five reduction peaks. The reduction peaks at Ep = −0.5 and −1.0 V, not detected in the absence of AA, are associated to products formed in the course of the reaction. The variation of their peak current, ip, with time shows a complex behavior; that of ip (Ep = −1.0 V) follows a biphasic profile with ip increasing with time up to a maximum after which a decrease is detected, suggestive of formation and subsequent decomposition of a transient intermediate, meanwhile ip (Ep = −0.5 V) increases with time after an induction period. The peaks at Ep = −0.1 and −0.8 V are associated to the reduction of the diazonium group of 4NBD and, in the presence of AA ([AA] >>> [4NBD]), their peak currents decrease exponentially with time following clean first‐order kinetics for more than 3t1/2. The variation of kobs with [AA] at a given pH is linear with an intercept equal to zero and that of log(kobs) with pH at constant [AA] is also linear. Kinetic evidence is consistent with a reaction mechanism involving an irreversible, rate‐limiting bimolecular step which leads to the formation of an unstable triazene, which further decomposes yielding 4‐nitroaniline among other reaction products. Copyright © 2007 John Wiley & Sons, Ltd.
Acid assisted proton transfer in 4‐[(4‐R‐phenylimino)methyl]pyridin‐3‐ols: NMR spectroscopy in solution and solid state, X‐ray and UV studies and DFT calculations
Authors: Perona Almudena , Sanz Dionisia , Claramunt Rosa M. , Pinilla Elena , Torres M. Rosario , Elguero José
Published: May 2007

The behaviour of Schiff bases of 3‐hydroxy‐4‐pyridincarboxaldehyde and 4‐R‐anilines (RH, CH3, OCH3, Br, Cl, NO2) in acid media has been described. 1H, 13C, 15N‐NMR chemical shifts allow to establish the protonation site and its influence on the hydroxyimino/oxoenamino tautomerism. DFT calculations, electronic spectra and X‐ray diffraction are in agreement with the NMR conclusions. Copyright © 2007 John Wiley & Sons, Ltd.
Low‐temperature controlled free‐radical polymerization of vinyl monomers in the presence of a novel cyclic dixanthate under γ‐ray irradiation
Authors: Hua Daoben , Ge Xueping , Tang Jing , Zhu Xiulin , Bai Ruke , Pan Caiyuan
Published: May 2007

The free‐radical polymerization of methyl acrylate (MA) has been studied in the presence of a novel cyclic dixanthate under γ‐ray irradiation (80 Gy min−1) at room temperature (∼28 °C), −30 °C, and −76 °C respectively. The resultant polymers have controlled molecular weights and relatively narrow molecular weight distributions, especially at low temperatures (i.e., −30 and −76 °C). The polymerization control may be associated with the temperature: the lower the temperature is, the more control there is. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis of poly(methyl acrylate) (PMA) samples shows that there are at least three distributions: [3‐(MA)n‐H]+ cyclic polymers, [3‐(MA)n‐THF‐H]+, and [3‐(MA)n‐(THF)2‐H]+ linear PMAs. The relative content of the cyclic polymers markedly increases at a lower temperature, and this may be related to the reduced diffusion rate and the suppressed chain‐transfer reaction at the low temperature. It is evidenced that the good control of the polymerization at the low temperature may be associated with the suppressed chain‐transfer reaction, unlike reversible addition–fragmentation chain transfer polymerization. In addition, styrene bulk polymerizations have been performed, and gel permeation chromatography traces show that there is only one cyclic dixanthate moiety in the polymer chain. This article is the first to report the influence of a low temperature on controlled free‐radical polymerizations. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2847–2854, 2007
High‐quality SiO2/GaN interface for enhanced operation field‐effect transistor
Authors: Niiyama Yuki , Shinagawa Tatsuyuki , Ootomo Shinya , Kambayashi Hiroshi , Nomura Takehiko , Yoshida Seikoh
Published: May 2007

The interface quality in GaN metal–oxide–semiconductor (MOS) capacitors was dramatically improved by annealing after SiO2 deposition. The interface state density (Dit) of samples annealed at 900–1000 °C was estimated to be ∼2 × 1011 cm–2 eV–1 at 0.2 eV under the conduction band based on the calculation of the Terman method. Using this SiO2, it is expected that GaN MOSFETs can be operated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ZnO nanocrystallites obtained by oxidation of zinc arachidate – arachidic acid composite multilayers
Authors: Singh Sukhvinder , Srinivasa R. S. , Talwar S. S. , Major S. S.
Published: May 2007

ZnO nanocrystallites were prepared by the oxidation of Zinc Arachidate–Arachidic Acid (ZnA–AA) composite multilayers grown on quartz and freshly cleaved mica substrates. Control of zinc content in the multilayers was achieved by the manipulation of the subphase pH and the variation in the number of monolayers transferred. FTIR studies of multilayers show a gradual decrease in ZnA content as the subphase pH is reduced. X‐ray reflection studies show the presence of a single layered structure in all the as‐deposited multilayers transferred at different subphase pH. These observations suggest molecular level mixing of ZnA and arachidic acid molecules. The precursor multilayers were oxidized in the temperature range of 100–700 °C. The formation of ZnO is confirmed by UV–Visible spectroscopy. Atomic force micrographs show that the oxidation treatment resulted in either large agglomerates of ZnO nanocrystallites or isolated nanocrystallites, depending on the zinc content of the precursor multilayers. Typically, 7 monolayers ZnA–AA transferred at subphase pH of 5.0 on mica and oxidized at 700 °C resulted in uniformly distributed, isolated and nearly mono‐dispersed nanocrystallites of size 11 ± 3 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A nano‐scale architecture for constant time image processing
Authors: Eshaghian‐Wilner M. M. , Khitun Alex , Navab Shiva , Wang Kang L.
Published: May 2007

In this paper, we study a nano‐scale highly parallel computing architecture for image processing: a reconfigurable mesh that is interconnected with ferromagnetic spin‐wave buses. In this architecture, information is encoded into the phase of the spin‐wave, and interommunications are performed without any charge transfer. This spin‐wave reconfigurable mesh, while requiring the same number of switches as standard reconfigurable mesh, is capable of simultaneously transmitting multiple waves on each of the spin‐wave paths using different frequencies. Moreover, in this architecture, the superposition characteristic of spin‐waves allows concurrent writes if all the requesting processors write a “1”. Employing these parallel features, we present three constant time image processing applications for this architecture. We show that given anN1/2×N1/2image, using aN×Nspin‐wave reconfigurable mesh, in constant time, all figures. can be labelled, and the nearest neighbour, and the convex hull of a single figure can be found. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic analysis of a random walk on a hypercube with many dimensions
Authors: Diaconis Persi , Graham R. L. , Morrison J. A.
Published: May 2007

In nearest neighbor random walk on an n‐dimensional cube a particle moves to one of its nearest neighbors (or stays fixed) with equal probability. the particle starts at 0. How long does it take to reach its stationary distribution? in fact, this occurs surprisingly rapidly. Previous analysis has shown that the total variation distance to stationarity is large if the number of steps N is < 1/4n log n and close to 0 if N > 1/4n log n. This paper derives an explicit expression for the variation distance as n → ∞ in the transition region N ˜ 1/4n log n. This permits the first careful evaluation of a cutoff phenomenon observed in a wide variety of Markov chains. the argument involves Fourier analysis to express the probability as a contour integral and saddle point approximation. the asymptotic results are in good agreement with numerical results for n as small as 100.
The transitive closure of a random digraph
Authors: Karp Richard M.
Published: May 2007

In a random n‐vertex digraph, each arc is present with probability p, independently of the presence or absence of other arcs. We investigate the structure of the strong components of a random digraph and present an algorithm for the construction of the transitive closure of a random digraph. We show that, when n is large and np is equal to a constant c greater than 1, it is very likely that all but one of the strong components are very small, and that the unique large strong component contains about Θ2n vertices, where Θ is the unique root in [0, 1] of the equation 1 − x − e−ex = 0. Nearly all the vertices outside the large strong component line in strong components of size 1. Provided that the expected degree of a vertex is bounded away from 1, our transitive closure algorithm runs in expected time O(n). for all choices of n and p, the expected execution time of the algorithm is O(w(n) (n log n)4/3), where w(n) is an arbitrary nondecreasing unbounded function. To circumvent the fact that the size of the transitive closure may be Ω(n2) the algorithm presents the transitive closure in the compact form (A × B)U C, where A and B are sets of vertices, and C is a set of arcs.
Quasi‐random hypergraphs
Authors: Chung F. R. K. , Graham R. L.
Published: May 2007

We introduce an equivalence class of varied properties for hypergraphs. Any hypergraph possessing any one of these properties must of necessity possess them all. Since almost all random hypergraphs share these properties, we term these properties quasi‐random. With these results, it becomes quite easy to show that many natural explicit constructions result in hypergraphs which imitate random hypergraphs in a variety of ways.
Competition graphs and clique dimensions
Authors: Füredi Zoltán
Published: May 2007

Here it is proved that for almost all simple graphs over n vertices one needs Ω(n4/3(log n)−4/3) extra vertices to obtain them as a double competition graph of a digraph. on the other hand O(n5/3) extra vertices are always sufficient. Several problems remain open.
On the height of randomm‐ary search trees
Authors: Devroye Luc
Published: May 2007

A randomm‐ary seach tree is constructed from a random permutation of 1,…,n. A law of large numbers is obtained for the heightHnof these trees by applying the theory of branching random walks. in particular, it is shown thatHn/logn→γin probability asn→∞ where γ = γ(m) is a constant depending uponmonly. Interestingly, asm→∞, γ(m) is asymptotic to 1/logm, the coefficient of lognin the asymptotic expression for the height of the completem‐ary search tree. This proves that for largem, randomm‐ary search trees behave virtually like completem‐ary trees.
Random walks in a convex body and an improved volume algorithm
Authors: Lovász L. , Simonovits M.
Published: May 2007

We give a randomized algorithm usingO(n7log2n) separation calls to approximate the volume of a convex body with a fixed relative error. The bound isO(n6log4n) for centrally symmpetric bodies and for polytopes with a polynomial number of facets, andO(n5log4n) for centrally symmetric polytopes with a polynomial number of facets. We also give anO(n6logn) algorithm to sample a point from the uniform distribution over a convex body. Several tools are developed that may be interesting on their own. We extend results of Sinclair–Jerrum [43] and the authors [34] on the mixing rate of Markov chains from finite to arbitrary Markov chains. We also analyze the mixing rate of various random walks on convex bodies, in particular the random walk with steps from the uniform distribution over a unit ball. © 1993 John Wiley & Sons, Inc.
The largest connected component in a random mapping
Authors: Jaworski Jerzy , Mutafchiev Ljuben
Published: May 2007

A random mapping (T; q) of a finite set V = {1, 2,…,n} into itself assigns independently to each i ϵ V its unique image j = TT(i)E V with probability q for i = j and with probability \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{1 - q}}{{n - 1}} $\end{document} for j ≠ i. The purpose of the article is to determine the asymptotic behaviour of the size of the largest connected component of the random digraph GT(q) representing thes mapping as n–x, regarding all possible values of the parameter q = q(n). © 1994 John Wiley & Sons, Inc.
Can you feel the double jump?
Authors: Shelah Saharon , Spencer Joel
Published: May 2007

When p = c/n and c goes from less than one to greater than one, the random graph G(n, p) experiences the double jump. The first order language is too weak to recognize this change while there are properties expressable in the second order monadic language for which the change is clear. © 1994 John Wiley & Sons, Inc.
Changes of leadership in a random graph process
Authors: Erdös Paul , Łuczak Tomasz
Published: May 2007

Let be a random graph process in which in each step we add to a graph a new edge, chosen at random from all available pairs. Define the leader of G(n, M) as either the unique largest component or, if G(n, M) contains many components of the maximum size, the one from the largest components which emerged first during the process. We show that the longest period between two changes of leaders in the random graph process is, with probability tending to 1 as n →∞, of the order of n/log log n/log n. © 1994 John Wiley & Sons, Inc.
Selbsterregte Schlagschwingungen von Drehflügeln bei hohem Fortschrittsgrad
Authors: Hohenemser Kurt H.
Published: May 2007

Die hier gegebene Theorie beschränkt sich auf den Fall von starren Blättern und gibt daher nur einen qualitativen Einblick in den Mechanismus der selbsterregten Schlagschwingung von Drehflügeln bei hohem Fortschrittsgrad. Der Einfluß der Hauptparameter und der Typus der Schlagbewegung wird jedoch erfaßt.
Stresses in thin aeolotropic disks rotating about normal axes
Authors: Gupta A. M. Sen
Published: May 2007

In this paper two problems of rotating aeolotropic disks are considered. The first problem deals with steady rotation of an orthotropic elliptic plate whose axes are not coincident with the directions of the lines of elastic symmetry in the plate, while the second is concerned with the steady rotation of a composite circular disk which is partly isotropic and partly cylindrically aeolotropic.
The motion of an infinite cylinder in rotating non‐Newtonian liquid
Authors: Jain M. K.
Published: May 2007

The two dimensional motion of an infinite cylinder is discussed in a rotating non‐Newtonian liquid by introducing second order terms in the stress‐strain velocity relations of classical hydrodynamics. It is shown here that Taylor's result for an inviscid liquid are not effected even if viscosity and cross‐viscosity are taken into consideration.
Stresses In an Infinite Slab due to a Nucleus of Thermoelastic Strain in it .
Authors: Sharma Brahma Dev
Published: May 2007

In this paper stresses in an infinite slab due to a nucleus of thermoelastic strain situated at a point inside it have been found.
Über homogene lineare Ungleichungssysteme
Authors: Burger E.
Published: May 2007

Es wird ein Verfahren zur Lösung eines homogenen linearen Ungleichungssystems angegeben, welches darauf beruht, daß sich leicht explizit beschreiben läßt, wie sich der Lösungskegel eines solchen Ungleichungssystems ändert, Wenn eine neue Ungleichung hinzutritt. Die Beschreibung der Lösungskegel erfolgt dabei in einer Weise, die für den Fall, daß der Kegel keinen nichttrivialen linearen Teilraum enthält, in die bekannte Darstellung eines solchen Kegels durch seine extremen Strahlen übergeht.
Über Randwertprobleme bei Häuten und dünnen Schalen im Membranspannungszustand
Authors: Behlendorff Erika
Published: May 2007

Es wird gezeigt, daß sich eine positive gekrümmte dünne Schale dann und nur dann im momentlosen Spannungszustand befinden kann, wenn zwischen Flächenbelastung und Randschubspannung drei Verträglichkeitsbedingungen erfüllt sind. Diese lassen sich nach den von W. Haack und G. Hellwig für die Untersuchung von Randwertproblemen elliptischer Differentialgleichungssysteme entwickelten Methoden explizite angeben.
Stress distribution in a thin aeolotropic strip due to a nucleus of strain
Authors: Choudhury Pritindu
Published: May 2007

Mittels Fourier‐Transformation werden die Spannungen ermittelt, die sich in dünnen aeolotropen Streifen als Folge eines Dehnungszentrums in der Mitte zwischen den geraden Enden des Streifens ergeben.
Stresses in certain thin elastic plates rotating about normal axes
Authors: Gupta A. M. Sen
Published: May 2007

In this paper a direct method for solving problems of certain thin elastic plates having curvilinear boundaries and rotating steadily about normal axes is developed. To illustrate the method the problem of a rotating thin plate having a regular curvilinear polygonal boundary, in general, is solved. Discussions of the corresponding problems of thin plates with some simpler types of boundaries are given in detail.
Numerische Integration von gewöhnlichen Differentialgleichungen durch Interpolation nach Hermite
Authors: Quade W.
Published: May 2007

Vermöge Hermitescher Interpolation werden Polynome konstruiert, die dem Richtungsfeld der Differential‐gleichung y′ = f(x, y) angepaßt sind. Aus solchen Polynomen werden durch Anwendung von Methoden der Approximationstheorie Formeln für die numerische Integration von y′ = f(x, y) erzeugt. Die auf diese Weise erhaltenen Interpolations‐ und Extrapolationsverfahren zeichnen sich durch große Genauigkeit aus.
Die Deutung bestimmter ebener Eigenspannungszustände als Membranspannungen
Authors: Hieke Max
Published: May 2007

Die Nichterfüllung der Kompatibilitätsbedingungen kann als Krümmung des geometrischen Raumes gedeutet werden. Eine Darstellung dieser Auslegung ist im Raume unmöglich. Bei zweidimensionalen Formänderungsproblemen, die den Verträglichkeitsbedingungen in der Ebene nicht genügen kann man die Flächen‐elemente in einigen Fällen auf angebbare Weise spannungslos aneinandersetzen. Man muß nur die Membran geeignet krümmen.
Differenzenverfahren für die 1. Randwertaufgabe mit krummlinigen Rändern bei Δu(x, y) = r(x, y, u)
Authors: Albrecht J. , Uhlmann U.
Published: May 2007

Es werden finite Gleichungen aufgestellt für die 1. Randwertaufgabe bei der Differentialgleichung Δu(x, y) = r (x, y, u), und zwar insbesondere für randnahe Rechenpunkte bei krummlinigen Rändern. Man erhält so für die praktische Anwendung wichtige Verallgemeinerungen der bekannten gewöhnlichen Differenzenverfahren und der Mehrstellenverfahren. Für vier‐, sechs‐ und achteckige Sterne wird jeweils eine vollständige Übersicht über alle Möglichkeiten des Taylor‐Abgleichs gegeben.
Retarded Flow Past a Semi‐Infinite Plane. Solution of a Non‐Linear Ordinary Differential Equation
Authors: Meksyn D.
Published: May 2007

The partial differential equation of the laminar boundary‐layer for the function f(ξ, η), where ξ and η are taken along and normal to the boundary, f(ξ, η) being associated with the stream function of the boundary‐layer, can be reduced to a non‐linear ordinary differential equation in \documentclass{article}\pagestyle{empty}\begin{document}$ a(\xi) = \left({\frac{{\partial ^2 f}}{{\partial \eta ^2}}} \right)_{\eta = 0} $\end{document} [i. e. a(ξ) is proportional to the viscous force]; this equation can be solved step by step.

In the present paper the equation in a(ξ) is solved in power series of ξ, for the case of a retarded flow past a semi‐infinite plane. The main difficulty of the solution is that the equation in a(ξ) is divergent.

To find the value of a(ξ), corresponding to the convergent equation from which the divergent equation is obtained, use is made of Euler's transformation.
Die Totalreflexion einer kugelförmigen Kompressionsfront an der Trennungsebene zweier elastischer Medien
Authors: Hasselmann K.
Published: May 2007

Es werden sämtliche bei der Totalreflexion auftretenden Stoßfronten — einschließlich der v. Schmidtschen Kopfwellen — ermittelt. Durch Änderung der Bezeichnung erhält man gleichzeitig die Totalreflexion einer harmonischen Kugelwelle. Das Problem wird in der akustischen Näherung (kleine Störfelder) behandelt.
Einige gemischte Randbedingungen anisotroper Platten
Authors: Brilla Jozef
Published: May 2007

Es wird eine unendliche elastische anisotrope Halbplatte y > 0 mit gemischten Randbedingungen untersucht. Die Halbplatte ist am Rande abwechselnd eingespannt und frei drehbar gelagert. Mit Hilfe der allgemeinen Lösung einer unendlichen anisotropen Halbplatte mit am Rande gegebenen ersten Ableitungen der Durchbiegung, die mittels des Verfahrens der Fourierintegrale gegeben ist, wird eine singuläre Integralgleichung für diese Randbedingungen abgeleitet. Nach der Zurückführung des Problems auf die Hilbert‐Riemannsche, Aufgabe werden die allgemeine Lösung für n Abschnitte des frei drehbar gelagerten Randes und die Lösungen für verschiedene Belastungsfälle der Halbplatte mit einem frei drehbar gelagerten Abschnitt des Randes untersucht.
Geometrische Untersuchungen über Nomogramme für elliptische Integrale erster Gattung und Jacobische elliptische Funktionen II
Authors: Reutter F. , Reutter F.
Published: May 2007

Im Anschluß an Teil I werden hier insbesondere Untersuchungen über die zweckmäßige Formgebung von Nomogrammen elliptischer Funktionen angestellt.
The Use of Poisson's Ratio in Studying Certain Non‐Homogeneous Elastic Inclusions
Authors: Knops R. J.
Published: May 2007

The elastic field is established for non‐homogeneous inclusions bonded to a non‐homogeneous, arbitrarily stressed matrix whose Poisson's ratio but not shear modulus is different to those of the inclusions. The procedure adopted examines the difference in the unperturbed and perturbed states of the matrix and enables the discontinuities in the stresses and strains to be found. Incompressible media are discussed and show that slight modifications are required to the theory. A new problem is solved for the single ellipsoidal inclusion and relations with other topics are noted.
Über den beginnenden plastischen Zustand bei unter innerem Überdruck stehenden Rohren
Authors: Németi Ladislaus
Published: May 2007

Es wird eine neue Bedingung für zulässige Beanspruchungen der über die Elastizitätsgrenze beanspruchten Bauteile vorgeschlagen. Und zwar soll die größte auftretende bleibende Verformung die Belastungsgrenze bestimmen. Als Anwendung wird das unter innerem Überdruck stehende Rohr untersucht und der Begriff einer praktisch brauchbaren ideellen Spannung eingeführt.
Über Geradenhüllbahnen einer Konchoidenbewegung
Authors: Bereis R.
Published: May 2007

In nachstehender Arbeit werden Geradenhüllbahnen bei Konchoidenbewegungen betrachtet, also bei jenen ebenen Zwangsläufen, bei denen eine Gerade der Gangebene während des ganzen Bewegungsablaufes durch einen festen Punkt der Rastebene gleitet. Die Eigenschaften der Geradenhüllbahnen werden durch räumliche Betrachtung mit Hilfe der Netzprojektion abgeleitet. Schließlich werden Aussagen über Geradenhüllbahnen bei speziellen Getrieben gemacht, insbesondere bei der Kurbelschleife und bei dem Schleifschieber.
Schiffswellen als Beispiel für die Wellenausbreitung in anisotropen, dispergierenden Medien
Authors: Becker E.
Published: May 2007

Die Geometrie der Wellenbilder, die man z. B. auf der freien Oberfläche eines Stromes schwerer Flüssigkeit bei punktförmiger, harmonischer Störung beobachten kann, werden durch Zurückführung auf allgemeine Gesetzmäßigkeiten der Wellenausbreitung in anisotropen, dispergierenden Medien erklärt. Hierbei wird an Begriffsbildungen angeknüpft, wie sie in ähnlicher Form u. a. aus der Optik anisotroper Medien bekannt sind.
Interactions between fat crystal networks and sodium caseinate at the sunflower oil‐water interface
Authors: Ogden Leanne G. , Rosenthal Andrew J.
Published: May 2007

A Couette‐type torsion wire surface shear viscometer was used to measure the apparent interfacial shear viscosity of pH 7 (I=0.05 M) buffered solutions of sodium caseinate in contact with sunflower oil. The sunflower oil contained 1% fat crystals in either the β or β′ polymorphic form, or was crystal free. In all cases, the fat crystals increased the interfacial shear viscosity synergistically, with the β′ crystals causing the biggest increase. Substituting the protein for a small‐molecule surfactant (Tween‐40) showed that this was not simply due to the protein lowering the interfacial tension. Sedimentation studies of the different fat crystal slurries suggested that the extent of the interfacial shear viscosity increase was related to the strength of crystal‐crystal interactions in the oil phase. It seems likely that when protein is present at the interface, it fixes the adsorbed layer of fat crystals to the cross‐linked protein film at the interface. When this film was sheared, the strength of the crystal‐crystal interactions in the oil phase became important. However, when Tween‐40 was in the aqueous phase instead of the protein, the crystal‐crystal interactions were not relevant, presumably because the Tween‐40 interfacial film simply flowed around the adsorbed crystals
Effect of fatty acid positional distribution and triacylglycerol composition on lipid by‐products formation during heat treatment: I. polymer formation
Authors: Martin J. C. , Dobarganes M. C. , Nour M. , Marquez‐Ruiz G. , Christie W. W. , Lavillonnière F. , Sébédio J.L
Published: May 2007

Effects of the fatty acid positional distribution and of the triacylglycerol (TG) composition on polymerization of TG during heat treatment were studied. Diacid TG molecules, acylated only with linoleic acid or linolenic acid along with palmitic acid, and positioned either in the central position (PLP and PLnP, respectively) or in one of the two outer positions (PPL and PPLn, respectively) were synthesized. Monoacid TG, i.e., trilinolein and trilinolenin, were also synthesized and mixed with tripalmitin in a 1:2 ratio. These model TG were also compared to TG models that consisted of a canola oil and its randomized counterpart, whose fatty acid positional distribution and TG composition were determined by means of high‐performance liquid chromatography (HPLC). After heating, the polymer content and composition were evaluated by HPLC‐size exclusion chromatography. Both pure TG and the canola oil models showed that acylation of polyunsaturated acids in the central position was protective against polymerization, although the effect was mainly observed with linolenic acid. The synthetic‐TG study showed that the monoacid TG species exhibited higher sensitivity toward polymerization than the diacid species. The slight differences in the TG species between both canola oils did not allow observation of such a relationship with regard to TG composition.