bluuebunny/crossref_metadata_2025 huggingface dataset:
Endogenous Cytokinin Oscillations Control Cell Cycle Progression of Tobacco BY‐2 Cells
Authors: Hartig K. , Beck E.
Published: January 2005

Abstract: The significance of cytokinins for the progression of the cell cycle is well known. Cytokinins contribute to the control of the expression of D‐cyclins and other cell cycle genes, but knowledge as to how they affect the progression of the cell cycle is still limited. Highly synchronized tobacco BY‐2 cells with clearly defined cell cycle stages were employed to determine cytokinin patterns in detail throughout the entire cycle. Concentrations of trans‐zeatin, and of some other cytokinins, oscillated during the course of the cell cycle, increasing substantially at all four phase transitions and decreasing again to a minimum value during the course of each subsequent phase. Addition of exogenous cytokinins or inhibition of cytokinin biosynthesis promoted the progression of the cell cycle when the effects of these manipulations intensified the endogenous fluctuations, whereas the progression of the cycle was retarded when the amplitude of the fluctuations was decreased. The results show that the attainment of low concentrations of cytokinins is as important as the transient increases in concentration for a controlled progression from one phase of the cell cycle to the next. Cytokinin oxidase/dehydrogenase activity also showed fluctuations during the course of the cell cycle, the timing of which could at least partly explain oscillations of cytokinin levels. The activities of the enzyme were sufficient to account for the rates of cytokinin disappearance observed subsequent to a phase transition.
Specificity Patterns Indicate that Auxin Exporters and Receptors are the Same Proteins
Authors: Hössel D. , Schmeiser C. , Hertel R.
Published: January 2005

Abstract: A study of transport and action of synthetic auxin analogues can help to identify transporters and receptors of this plant hormone. Both aspects ‐ transportability and action on growth ‐ were tested with 2‐naphthoxyacetic acid (2‐NOA) and compared across several plant species. 2‐NOA stimulates elongation effectively at low concentrations in petioles of the gymnosperm Ginkgo biloba L., in hypocotyls or internodes of the dicot legumes, mung bean (Vigna mungo L.) and pea (Pisum sativum L.), in cotyledons of onion (Allium cepa L.) and in leaf bases of chive (Allium schoenoprasum L.), the latter two of the monocot order Asparagales. In contrast, elongation of coleoptile segments of maize (Zea mays L.) is poorly responsive to 2‐NOA. Significant auxin‐like transport of 2‐NOA was observed in segments of mung bean hypocotyls, pea internodes, and chive leaf bases, but not in segments of the grass coleoptiles. Thus, for the two assays, elongation and polar transportability, the same difference in ligand specificity was observed between the grass and all other species assayed. This finding supports the hypothesis that a common protein mediates auxin efflux as well as auxin action on elongation.
Changes in the Subcellular Distribution of Glutathione during Virus Infection in Cucurbita pepo (L.)
Authors: Zechmann B. , Zellnig G. , Müller M.
Published: January 2005

Abstract: Changes in the subcellular distribution and quantification of glutathione were studied with electron microscopic immunogold cytochemistry in Zucchini yellow mosaic virus (ZYMV)‐infected Styrian pumpkin plants (Cucurbita pepo L. ssp. pepo var. styriaca Greb.) two weeks after inoculation. The amount of gold particles bound to glutathione was statistically evaluated for different cell structures, including mitochondria, plastids, nuclei, peroxisomes, and cytosol. In general, ZYMV‐infected plants showed higher gold labelling density in intact mesophyll cells of the 5th (older leaves) and the youngest fully developed leaves (younger leaves), and decreased levels of glutathione within root tip cells when compared to the control. In general, within older and younger leaves the highest amount of gold particles was found in mitochondria and the lowest amount in plastids. In ZYMV‐infected older leaves, an increase in glutathione was found in peroxisomes (1.7‐fold), the cytosol (1.6‐fold), mitochondria (1.4‐fold), and nuclei (1.2‐fold), whereas glutathione levels in plastids did not differ significantly when compared to control cells. In ZYMV‐infected younger leaves elevated glutathione contents were found in the cytosol (3‐fold), nuclei (2.1‐fold), peroxisomes (1.8‐fold), and plastids (1.5‐fold), whereas mitochondria showed an insignificant decrease in glutathione levels in comparison to the control. In root tip cells of ZYMV‐infected plants the amount of gold particles bound to glutathione was decreased in all investigated cell structures by between 0.7‐ to 0.8‐fold. Additionally, total glutathione contents were determined in older and younger leaves using high‐performance liquid chromatography (HPLC), which revealed no significant differences between control and ZYMV‐infected leaves. The relevance of the results of both methods were compared and are discussed.
Molecular Relationships in Encephalartos (Zamiaceae, Cycadales) Based on Nucleotide Sequences of Nuclear ITS 1&2, Rbcl, and Genomic ISSR Fingerprinting
Authors: Treutlein J. , Vorster P. , Wink M.
Published: January 2005

Abstract: The cycad genus Encephalartos is restricted to Africa and is threatened with extinction in most of its range. Total DNA was extracted from 51, i.e., 78 %, of the described species of Encephalartos. The accessions were sampled from the furthest western occurrence of the genus in Nigeria, via Sudan and Uganda, to southern South Africa. The sequences of nuclear ribosomal internal transcribed spacer regions 1 and 2 (ITS 1&2), the chloroplast encoded rbcL gene, and ISSR genomic fingerprinting were employed to resolve the molecular history and the relationships within the genus. Sequence alignment, as well as ISSR fingerprinting, data show low genetic variation among all analysed accessions, indicating diversification within the Pliocene/Pleistocene. ITS 1&2 data agree well with morphological and geographical characters and resolved three major genetic clusters with overlapping distribution ranges in eastern South Africa. This area, that contains the largest diversity of genotypes of Encephalartos, may have served as a Pliocene/Pleistocene refugium.
On the vortical structure in a round jet
Authors: Matsuda Tadashi , Sakakibara Jun
Published: January 2005

Turbulent vortical structures in a round free jet of water were experimentally visualized by using stereo particle image velocimetry (PIV). A laser light sheet illuminated a cross-sectional plane normal to the axis of the jet, and two charge-coupled device cameras captured particle images in the same region of interest but from different directions. The stereo-PIV algorithm had been applied to obtain two-dimensional, three-component (2D-3C) velocity distributions on various cross-sectional planes along the axis downstream. All nine components of the velocity gradient tensor were reconstructed from time-dependent 2D-3C velocity data by locally assuming Taylor’s frozen field hypothesis based on the convective velocity evaluated from the mean flow profile. Isosurfaces of the swirling strength λi revealed that the existence of a group of hairpinlike vortex structures was quite evident around the rim of the shear layer of the jet. The center of curvature of the head of the hairpin was typically observed around r∕b=1.5, and the azimuthal spacing between the legs of the hairpin was roughly 0.9b. A similar hairpin structure was estimated by linear stochastic estimation. The typical spacing between the legs of the estimated hairpin was 0.65b, which is generally constant over the range of Re=1500–5000.
The influence of intense control laser pulses on homodyne-detected rotational wave packet dynamics in O2 by degenerate four-wave mixing
Authors: Stavros Vasilios G. , Harel Elad , Leone Stephen R.
Published: January 2005

We illustrate how the preparation and probing of rotational Raman wave packets in O2 detected by time-dependent degenerate four-wave mixing (TD-DFWM) can be manipulated by an additional time-delayed control pulse. By controlling the time delay of this field, we are able to induce varying amounts of additional Rabi cycling among multiple rotational states within the system. The additional Rabi cycling is manifested as a change in the signal detection from homodyne detected to heterodyne detected, depending on the degree of rotational alignment induced. At the highest laser intensities, Rabi cycling among multiple rotational states cannot account for the almost complete transformation to a heterodyne-detected signal, suggesting a second mechanism involving ionization. The analysis we present for these effects, involving the formation of static alignment by Rabi cycling at moderate laser intensities and possibly ion gratings at the highest intensities, appears to be consistent with the experimental findings and may offer viable explanations for the switching from homodyne to heterodyne detection observed in similar DFWM experiments at high laser field intensities (>1013W∕cm2).
Multiphoton photodetachment of C60−
Authors: Patil S. H.
Published: January 2005

A model δ-function potential is considered for simulating the interaction of the attached electron in C60− with the fullerene environment. The analytical expressions for the energy eigenstates, and the Green’s function, are used to deduce the one-, two-, and three-photon photodetachment probabilities for C60−. Particularly interesting is the observation that the three-photon photodetachment is greatly enhanced by the bound states with energies close to the energies for resonant absorption of one and two photons, and a resonance in the l=3 state.
Time evolution studies of the electrostatic surface potential of low-temperature-grown GaAs using electrostatic force microscopy
Authors: Howell S. W. , Janes D. B.
Published: January 2005

An electrostatic force microscope was used to measure the electrostatic surface potential of low-temperature-grown GaAs (LTG:GaAs) before and after the removal of the native oxide layer. The surface potential of oxidized LTG:GaAs was found to be 450±50mV with respect to a bare Au reference. This was consistent with the known work function of Au and energy bands of LTG:GaAs. After removal of the oxide layer using a chemical etch, the surface potential of the LTG:GaAs was found to evolve as time passed. The observed transient behavior depended both on the environment and the particular chemical etchant used to remove the native surface oxide, with time constants ranging from approximately 1to10h. The behavior can be explained in terms of the decay of a charge sheet or dipole at the surface. The experiments provide insights into the surface electrical properties of LTG:GaAs and, indirectly, stoichiometric at critical stages of typical device fabrication processes.
Three-dimensional simulation of impingement of a liquid droplet on a flat surface in the Leidenfrost regime
Authors: Ge Yang , Fan L.-S.
Published: January 2005

The hydrodynamics and heat transfer phenomena of a liquid droplet impacting upon a hot flat surface are analyzed based on three-dimensional (3D) numerical simulation considering film-boiling behavior. The 3D level-set method is employed to portray the droplet surface variation during its deformation. The governing equations for the droplet and the surrounding gas phase are solved utilizing the finite-volume method with the arbitrary Lagrangian Eulerian technique. To account for the lubrication resistant effects of the vapor cushion formed by the film-boiling evaporation, a separate vapor flow model is developed to simulate the pressure and velocity distribution along the vapor layer between the droplet and the surface. The temperature fields in all phases and the local evaporation rate on the droplet surface are determined by using a full field heat transfer model. Both the water and n-heptane droplets impacting on the solid wall with different Weber numbers are investigated. The comparisons of the simulation results with the experimental results reported in the literatures are made to substantiate the model presented in this study. Specially, the spreading and recoiling motions of the impacting droplets are reproduced accurately for a wide range of the Weber number. The oscillation of the thickness of the vapor layer and the temperature distribution across the interface are also calculated and compared favorably with the experimental results. As the Weber number increases, the extent of the droplet spreading increases, but the residence time of the droplet on the surface is almost unchanged. Compared to the saturated impacts, the subcooled impact yields a thinner vapor layer and a higher heat transfer rate.
Dynamic characterization of hysteresis elements in mechanical systems. I. Theoretical analysis
Authors: Al-Bender F. , Symens W.
Published: January 2005

The pre-sliding–pre-rolling phase of friction behavior is dominated by rate-independent hysteresis. Many machine elements in common engineering use exhibit, therefore, the characteristic of “hysteresis springs,” for small displacements at least. Plain and rolling element bearings that are widely used in motion guidance of machine tools are typical examples. While the presence of a hysteresis element may mark the character of the resulting dynamics, little is to be found about this topic in the literature. The study of the nonlinear dynamics caused by such elements becomes imperative if we wish to achieve accurate control of such machines. In this Part I of the investigation, we examine a single-degree-of-freedom mass-hysteresis-spring system and show that, while the free response case is amenable to an exact solution, the more important case of forced response has no closed form solution and requires other methods of treatment. We consider harmonic-balance analysis methods (which are common analysis tools in engineering) suitable for frequency-domain treatment, in particular the approximate describing function (DF) method, and compare those results with “exact” numerical simulations. The DF method yields basically a linear equation with amplitude-dependent modal parameters. We find that agreement in the frequency response function, between DF and exact solution, is good for small excitation amplitudes and for very large amplitudes. Intermediate values, however, show high sensitivity to amplitude variations and, consequently, no regular solution is obtainable by either approach. This appears to be an inherent property of the system pointing to the need for developing further analysis methods. Experimental verification of the analysis outlined in this Part I is given in Part II of the paper.
Dynamic characterization of hysteresis elements in mechanical systems. II. Experimental validation
Authors: Symens W. , Al-Bender F.
Published: January 2005

The industrial demand for machine tools with ever increasing speed and accuracy calls for a closer look at the physical phenomena that are present at small movements of those machine’s slides. One of these phenomena, and probably the most dominant one, is the dependence of the friction force on displacement that can be described by a rate-independent hysteresis function with nonlocal memory. The influence of this highly nonlinear effect on the dynamics of the system has been theoretically analyzed in Part I of this paper. This part (II) aims at verifying these theoretical results on three experimental setups. Two setups, consisting of linearly driven rolling element guideways, have been built to specifically study the hysteretic friction behavior. The experiments performed on these specially designed setups are then repeated on one axis of an industrial pick-and-place device, driven by a linear motor and guided by commercial guideways. The results of the experiments on all the setups agree qualitatively well with the theoretically predicted ones and point to the inherent difficulty of accurate quantitative identification of the hysteretic behavior. They further show that the hysteretic friction behavior has a direct bearing on the dynamics of machine tools and its presence should therefore be carefully considered in the dynamic identification process of these systems.
Vacancy-type defects in Si-doped InN grown by plasma-assisted molecular-beam epitaxy probed using monoenergetic positron beams
Authors: Uedono A. , Chichibu S. F. , Higashiwaki M. , Matsui T. , Ohdaira T. , Suzuki R.
Published: January 2005

High-quality InN layers grown on sapphire substrates by plasma-assisted molecular-beam epitaxy were characterized using monoenergetic positron beams. The carrier concentrations of the films were controlled by Si doping (2.1×1018to1.4×1019cm−3), and the highest obtained Hall mobility was 1300cm2V−1s−1. The Doppler broadening spectra of the annihilation radiation and the lifetime spectra of positrons were measured as a function of the incident positron energy for undoped and Si-doped InN films. The line-shape parameter S increased with increasing carrier concentration, suggesting the introduction of vacancy-type defects by a Fermi-level effect. The major defect species were varied with carrier concentration, and its species were identified as In vacancies (VIn) or their related defects.
Fingering instability of a retracting solid film edge
Authors: Kan Wanxi , Wong Harris
Published: January 2005

A thin gold film under annealing on a silica substrate can develop “fingers” at the perimeter of the film. The perimeter retracts to leave behind longer fingers, which eventually pinch off to reduce the surface energy of the system. New fingers then form at the film edge and the process continues until the entire film disintegrates. To maintain the structure integrity of annealed thin films, this fingering instability must be understood. The retraction of a straight film edge via capillarity-driven surface diffusion has been analyzed in two dimensions by Wong et al.[Acta Mater. 48, 1719 (2000)]. They found that a retracting film is thickened at the edge followed by a valley before the film thickness becomes uniform. We study the three-dimensional linear stability of this two-dimensional film profile and find one unstable mode of perturbation. The growth rate of the perturbation is determined as a function of the wavelength of the perturbation and the speed of the receding edge. The results show that a straight film edge becomes wavy when perturbed. The wavelength λm of the fastest growing perturbation agrees with the distance between adjacent fingers observed in a gold-film experiment. Fingers can also form during annealing at the retracting edges of cracks in sapphire, and our predicted λm compares well with the measured finger spacing.
Pressure behavior of beryllium-acceptor level in gallium nitride
Authors: Teisseyre H. , Gorczyca I. , Christensen N. E. , Svane A. , Naranjo F. B. , Calleja E.
Published: January 2005

Beryllium is a promising dopant for obtaining an efficient p-type conductivity of GaN. A high-pressure study of the donor-acceptor-pair (DAP) photoluminescence line at 3.39eV in Be-doped GaN samples is reported, together with ab initio calculations of the electronic structure of GaN:Be under pressure. The analysis confirms the formation of a Be-acceptor state which is involved in the DAP photoluminescence. Different properties of the Mg- and the Be-acceptor states in GaN are found. The Be level is located ∼100–140meV lower in the band gap than that of Mg, and its pressure coefficient is lower by approximately 3–4meV∕GPa.
Cr-doped TiO2 anatase: A ferromagnetic insulator
Authors: Droubay T. , Heald S. M. , Shutthanandan V. , Thevuthasan S. , Chambers S. A. , Osterwalder J.
Published: January 2005

Epitaxial ferromagnetic films of Cr-doped TiO2 anatase (CrxTi1−xO2−x∕2) were grown on LaAlO3(001) using oxygen-plasma-assisted molecular-beam epitaxy. CrK-shell x-ray absorption near-edge spectroscopy shows that the formal oxidation state of Cr is +3 throughout the films, with no evidence for either elemental Cr or half-metallic CrO2. Cr is found to substitute for Ti in the lattice, with uniform distribution throughout the doped region of the film. The Cr-doped anatase films exhibit room-temperature ferromagnetism aligned in-plane, with a saturation magnetization of ∼0.6μB/Cr atom.
Experimental investigation of the shock wave interaction with a spherical gas inhomogeneity
Authors: Layes Guillaume , Jourdan Georges , Houas Lazhar
Published: January 2005

The interaction of a shock wave with a spherical gas inhomogeneity (soap bubble) is experimentally investigated using a high speed camera shadowgraph diagnostic. Negative, close to zero, and positive density jumps across the bubble interface are studied for weak incident shock waves. For each case, the bubble length and height evolutions have been determined, as well as the generated vortex diameter and pair spacing from only one run. We point out that in all cases, after the shock bubble compression phase, the bubble and surrounding gaseous mixing length is linear with time.
One-dimensional turbulence: Variable-density formulation and application to mixing layers
Authors: Ashurst Wm. T. , Kerstein Alan R.
Published: January 2005

One-dimensional turbulence (ODT), a method for one-dimensional stochastic simulation of turbulent flow, is generalized to incorporate variable-density effects. This formulation is used to investigate variable-density effects in planar mixing layers. Computed results are compared to direct numerical simulations of temporally developing mixing layers and to measurements performed in spatially developing mixing layers. Dependencies of mean flow structure and fluctuation statistics on the free-stream density ratio s are examined, including s values beyond the range of previous experimental and computational studies. For temporally developing mixing layers, the previously noted decrease of the layer growth rate as s deviates from unity is reproduced. For spatially developing mixing layers, dependence on s is sensitive to whether the high-speed or the low-speed stream is denser; by convention, the latter case corresponds to s>1. Experimental results indicating that layer growth is an increasing function of s have previously been interpreted on the basis of models that imply the continuation of this monotonic trend for all s. ODT reproduces the observed trend within the experimentally accessible range, but predicts a reversal of the trend slightly beyond that range and a subsequent decrease of the growth rate as s increases. This and related results suggest a closer analogy between the behaviors of temporally and spatially developing mixing layers than has previously been recognized. An experimental test of the predicted trend reversal in spatially developing mixing layers is proposed.
A Lagrangian stochastic model for dispersion in stratified turbulence
Authors: Das S. K. , Durbin P. A.
Published: January 2005

In this paper we discuss the development of a Lagrangian stochastic model (LSM) for turbulent dispersion of a scalar (species). Given any tensorally linear second-moment closure (SMC) turbulence model we show how to derive a mathematically equivalent set of stochastic differential equations (SDEs), i.e., the second-moment equations constructed from these SDEs are exactly the same (within a realizability constraint) as the given SMC. This set of equations forms the LSM. Both turbulence anisotropy and buoyancy effects are incorporated by this method. In order to achieve the correct critical Richardson number and to obtain the simplest Lagrangian formulation, a revised set of constants for the isotropization of production model is proposed. They improve agreement with experiments. The LSM is applied to homogeneous shear flow with varying degrees of stratification. Our model is shown to capture important physics associated with buoyant flows and we also parametrize our results. Finally the form of the current model is compared with a few of the well-known Lagrangian stochastic models.
A detailed spectroscopic study of an Italian fresco
Authors: Barilaro Donatella , Crupi Vincenza , Majolino Domenico , Barone Germana , Ponterio Rosina
Published: January 2005

In the present work we characterized samples of plasters and pictorial layers taken from a fresco in the Acireale Cathedral. The fresco represents the Coronation of Saint Venera, patron saint of this Ionian town. By performing a detailed spectroscopic analysis of the plaster preparation layer by Fourier-transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD), and of the painting layer by FTIR and confocal Raman microspectroscopy, scanning electron microscopy+energy dispersive x-ray spectroscopy, and XRD, we were able to identify the pigments and the binders present. In particular, Raman investigation was crucial to the characterization of the pigments thanks to the high resolution of the confocal apparatus used. It is worth stressing that the simultaneous use of complementary techniques was able to provide more complete information for the conservation of the artifact we studied.
Lattice dynamics and dielectric response of Mg-doped SrTiO3 ceramics in a wide frequency range
Authors: Tkach A. , Vilarinho P. M. , Kholkin A. L. , Pashkin A. , Samoukhina P. , Pokorny J. , Veljko S. , Petzelt J.
Published: January 2005

Atomic substitutions in the SrTiO3 (ST) perovskite lattice are foreseen to modify the lattice vibration modes, which are apparently sensitive to the site at which the substitution occurs. In order to understand the effect of Mg substitution in the ST lattice, the dielectric properties of Sr1−xMgxTiO3 and SrTi1−yMgyO3−δ ceramics were investigated in radio frequency (rf), microwave, terahertz (THz), and infrared (IR) ranges. Micro-Raman spectroscopy and rf tunability measurements were also conducted on these samples. The micro-Raman spectra and the high-frequency dielectric properties of Sr1−xMgxTiO3, including rf tunability, do not differ considerably from the properties of undoped SrTiO3, confirming only slight (if any) incorporation of Mg into the Sr site of ST perovskite lattice. At the same time, Ti-site Mg doping results in significant stiffening of the soft lattice mode observed in IR reflectivity spectra. Dielectric permittivity and dielectric losses decrease in both rf and THz ranges accompanied by the decrease of the tunability, in accordance with the stiffened ferroelectric soft mode. The appearance in the Raman spectra of the forbidden polar modes TO4 at 545cm−1 and TO2 at 174cm−1 at room temperature and their strengthening on cooling, demonstrate the local loss of the inversion center and the breaking of the cubic symmetry by the substitution of Ti4+ by Mg2+ ions. These results confirm more favorable occupation of Mg at the Ti site of the ST lattice and show the possibility of using Ti-site Mg-doped ST as an active material for low-loss microwave waveguides and resonators.
Wave propagation of carbon nanotubes embedded in an elastic medium
Authors: Natsuki Toshiaki , Hayashi Takuya , Endo Morinobu
Published: January 2005

This paper presents analytical models of wave propagation in single- and double-walled carbon nanotubes, as well as nanotubes embedded in an elastic matrix. The nanotube structures are treated within the multilayer thin shell approximation with the elastic properties taken to be those of the graphene sheet. The double-walled nanotubes are coupled together through the van der Waals force between the inner and outer nanotubes. For carbon nanotubes embedded in an elastic matrix, the surrounding elastic medium can be described by a Winkler model. Tube wave propagation of both symmetrical and asymmetrical modes can be analyzed based on the present elastic continuum model. It is found that the asymmetrical wave behavior of single- and double-walled nanotubes is significantly different. The behavior is also different from that in the surrounding elastic medium.
Detection of the onset of nanocrystallization by calorimetric and magnetic measurements
Authors: Blázquez J. S. , Franco V. , Conde C. F. , Conde A. , Roth S.
Published: January 2005

It is generally accepted that measurements of the magnetic properties are more sensitive than measurements of the enthalpy changes in the detection of the onset of crystallization of ferromagnetic phases emerging from a paramagnetic amorphous alloy. In this work, it is shown that the formation of a very fine nanocrystalline microstructure can make this assumption incorrect. Under some circumstances, the nanocrystallization onset temperature obtained from magnetic techniques is higher than the one obtained from enthalpy changes. The phenomenon is explained in terms of the superparamagnetic behavior of the uncoupled nanocrystals at the very early stages of nanocrystallization.
Building Mass Customised Housing through Innovation in the Production System: Lessons from Japan
Authors: Barlow James , Ozaki Ritsuko
Published: January 2005

In the paper we address the way Japanese housebuilders have developed innovative approaches to supplying highly customised housing. We draw on notions of path dependency to explore the evolution of Japan's large-scale industrialised housing suppliers, the way they have differentiated themselves from local suppliers, and their possible future evolution. We first outline how structural conditions influence the business strategies adopted by housebuilders in general. We then consider the evolution of the Japanese mass customised housebuilding industry, the innovations it has introduced across its production system, and how these have been shaped by the structural conditions within which the industry operates. Finally, we draw conclusions on the role of path dependency in shaping Japan's mass customised housing sector.
Analysing Commuting Using Local Regression Techniques: Scale, Sensitivity, and Geographical Patterning
Authors: Lloyd Chris , Shuttleworth Ian
Published: January 2005

In this paper, two forms of local regression are employed in the analysis of relations between out-commuting distance and other socioeconomic variables in Northern Ireland. The two regression approaches used are moving window regression (MWR) and geographically weighted regression (GWR). For the first approach different window sizes are applied and changes in results assessed. For the second approach, a Gaussian kernel is used and its bandwidth varied. Seven independent variables are utilised, although a single variable (deprivation) provides the main analytical focus. Differences in results obtained with use of the two approaches are discussed. The relationship between window size or bandwidth size and observed spatial patterning is discussed and elucidated. The results support previous work that indicated severe limitations in using global regressions to examine relationships between socioeconomic variables. Also, the utility of comparing results obtained from MWR and GWR is assessed and the benefits of both approaches are outlined.
England's Multiethnic Educational System? A Classification of Secondary Schools
Authors: Johnston Ron , Wilson Deborah , Burgess Simon
Published: January 2005

As British society has become increasingly multiethnic and multicultural, debate has grown regarding the advantages and disadvantages of ethnically segregated schools, with regard both to educational achievement and to multicultural accommodation. Compared with issues regarding the class composition of schools, however, little work has been done on the degree of ethnic segregation in schools, let alone its impact. The authors use a recently developed classification procedure to identify the degree of ethnic segregation in England's secondary schools in 2001, using a database that gives every student's ethnic identity. It is shown that, although there is considerable segregation for members of ethnic minority groups in London and a small number of other urban areas, elsewhere there is much more exposure of members of those groups to White students; White students are much more segregated, however. In general, the level of segregation in schools is greater than the residential segregation of the various ethnic groups.
A new Löwenheim-Skolem theorem
Authors: Foreman Matthew , Todorcevic Stevo
Published: January 2005

This paper establishes a refinement of the classical Löwenheim-Skolem theorem. The main result shows that any first order structure has a countable elementary substructure with strong second order properties. Several consequences for Singular Cardinals Combinatorics are deduced from this.
The baseleaf preserving mapping class group of the universal hyperbolic solenoid
Authors: Odden Chris
Published: January 2005

Given a closed surface

X
X

, the covering solenoid

X

∞

\mathbf {X}_\infty

is by definition the inverse limit of all finite covering surfaces over 

X
X

. If the genus of

X
X

is greater than one, then there is only one homeomorphism type of covering solenoid; it is called the universal hyperbolic solenoid. In this paper we describe the topology of

Γ
(

X

∞

)

\Gamma (\mathbf {X}_\infty )

, the mapping class group of the universal hyperbolic solenoid. Central to this description is the notion of a virtual automorphism group. The main result is that there is a natural isomorphism of the baseleaf preserving mapping class group of

X

∞

\mathbf {X}_\infty

onto the virtual automorphism group of

π
1

(
X
,
∗
)

\pi _1(X,*)

. This may be regarded as a genus independent generalization of the theorem of Dehn, Nielsen, Baer, and Epstein that the pointed mapping class group

Γ
(
X
,
∗
)

\Gamma (X,*)

is isomorphic to the automorphism group of

π
1

(
X
,
∗
)

\pi _1(X,*)

.
Finite quotients of rings and applications to subgroup separability of linear groups
Authors: Hamilton Emily
Published: January 2005

In this paper we apply results from algebraic number theory to subgroup separability of linear groups. We then state applications to subgroup separability of free products with amalgamation of hyperbolic

3
3

-manifold groups.
Threefolds with vanishing Hodge cohomology
Authors: Zhang Jing
Published: January 2005

We consider algebraic manifolds

Y
Y

of dimension 3 over

C

\mathbb {C}

with

H
i

(
Y
,

Ω
Y
j

)
=
0

H^i(Y, \Omega ^j_Y)=0

for all

j
≥
0

j\geq 0

and

i
>
0

i>0

. Let

X
X

be a smooth completion of

Y
Y

with

D
=
X
−
Y

D=X-Y

, an effective divisor on

X
X

with normal crossings. If the

D
D

-dimension of

X
X

is not zero, then

Y
Y

is a fibre space over a smooth affine curve

C
C

(i.e., we have a surjective morphism from

Y
Y

to

C
C

such that the general fibre is smooth and irreducible) such that every fibre satisfies the same vanishing condition. If an irreducible smooth fibre is not affine, then the Kodaira dimension of

X
X

is

−
∞

-\infty

and the

D
D

-dimension of

X
X

is 1. We also discuss sufficient conditions from the behavior of fibres or higher direct images to guarantee the global vanishing of Hodge cohomology and the affineness of

Y
Y

.
Generalized spherical functions on reductive 𝑝-adic groups
Authors: Huang Jing-Song , Tadić Marko
Published: January 2005

Let

G
G

be the group of rational points of a connected reductive

p
p

-adic group and let

K
K

be a maximal compact subgroup satisfying conditions of Theorem 5 from Harish-Chandra (1970). Generalized spherical functions on

G
G

are eigenfunctions for the action of the Bernstein center, which satisfy a transformation property for the action of

K
K

. In this paper we show that spaces of generalized spherical functions are finite dimensional. We compute dimensions of spaces of generalized spherical functions on a Zariski open dense set of infinitesimal characters. As a consequence, we get that on that Zariski open dense set of infinitesimal characters, the dimension of the space of generalized spherical functions is constant on each connected component of infinitesimal characters. We also obtain the formula for the generalized spherical functions by integrals of Eisenstein type. On the Zariski open dense set of infinitesimal characters that we have mentioned above, these integrals then give the formula for all the generalized spherical functions. At the end, let as mention that among others we prove that there exists a Zariski open dense subset of infinitesimal characters such that the category of smooth representations of

G
G

with fixed infinitesimal character belonging to this subset is semi-simple.
Mansfield’s imprimitivity theorem for full crossed products
Authors: Kaliszewski S. , Quigg John
Published: January 2005

For any maximal coaction

(
A
,
G
,
δ
)

(A,G,\delta )

and any closed normal subgroup

N
N

of

G
G

, there exists an imprimitivity bimodule

Y

G

/

N

G

(
A
)

Y_{G/N}^G(A)

between the full crossed product

A

×
δ

G

×

δ
^

|

N

A\times _\delta G\times _{\widehat \delta |}N

and

A

×

δ

|

G

/

N

A\times _{\delta |}G/N

, together with

Inf
⁡

δ
^

|

^

−

δ

dec

\operatorname {Inf}\widehat {\widehat \delta |}-\delta ^{\text {dec}}

compatible coaction

δ
Y

\delta _Y

of

G
G

. The assignment
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis upper A comma delta right-parenthesis right-arrow from bar left-parenthesis upper Y Subscript upper G slash upper N Superscript upper G Baseline left-parenthesis upper A right-parenthesis comma delta Subscript upper Y Baseline right-parenthesis">

(
A
,
δ
)
↦
(

Y

G

/

N

G

(
A
)
,

δ
Y

)

(A,\delta )\mapsto (Y_{G/N}^G(A),\delta _Y)

implements a natural equivalence between the crossed-product functors “

×
G
×
N

{}\times G\times N

” and “

×
G

/

N

{}\times G/N

”, in the category whose objects are maximal coactions of

G
G

and whose morphisms are isomorphism classes of right-Hilbert bimodule coactions of

G
G

.
Coisotropic and polar actions on complex Grassmannians
Authors: Biliotti Leonardo , Gori Anna
Published: January 2005

The main result of the paper is the complete classification of the compact connected Lie groups acting coisotropically on complex Grassmannians. This is used to determine the polar actions on the same manifolds.
Small deviations of weighted fractional processes and average non–linear approximation
Authors: Lifshits Mikhail , Linde Werner
Published: January 2005

We investigate the small deviation problem for weighted fractional Brownian motions in

L
q

L_q

–norm,

1
≤
q
≤
∞

1\le q\le \infty

. Let

B
H

B^H

be a fractional Brownian motion with Hurst index

0
>
H
>
1

0>H>1

. If

1

/

r
:=
H
+
1

/

q

1/r:=H+1/q

, then our main result asserts
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="limit Underscript epsilon right-arrow 0 Endscripts epsilon Superscript 1 slash upper H Baseline log double-struck upper P left-parenthesis double-vertical-bar rho upper B Superscript upper H Baseline double-vertical-bar Subscript upper L Sub Subscript q Subscript left-parenthesis 0 comma normal infinity right-parenthesis Baseline greater-than epsilon right-parenthesis equals minus c left-parenthesis upper H comma q right-parenthesis dot double-vertical-bar rho double-vertical-bar Subscript upper L Sub Subscript r Subscript left-parenthesis 0 comma normal infinity right-parenthesis Superscript 1 slash upper H Baseline comma">

lim

ε
→
0

ε

1

/

H

log
⁡

P

(

‖

ρ

B
H

‖

L
q

(
0
,
∞
)

>
ε

)

=
−
c
(
H
,
q
)
⋅

‖

ρ

‖

L
r

(
0
,
∞
)

1

/

H

,

\lim _{\varepsilon \to 0} \varepsilon ^{1/H}\log \mathbb {P}\left ({\left \|{\rho \,B^H}\right \|_{L_q(0,\infty )}>\varepsilon } \right ) = -c(H,q)\cdot \left \|{\rho }\right \|_{L_r(0,\infty )}^{1/H},

\]
provided the weight function

ρ
\rho

satisfies a condition slightly stronger than the

r
r

–integrability. Thus we extend earlier results for Brownian motion, i.e. 

H
=
1

/

2

H=1/2

, to the fractional case. Our basic tools are entropy estimates for fractional integration operators, a non–linear approximation technique for Gaussian processes as well as sharp entropy estimates for

l
q

l_q

–sums of linear operators defined on a Hilbert space.
Solving the Korteweg-de Vries equation by its bilinear form: Wronskian solutions
Authors: Ma Wen-Xiu , You Yuncheng
Published: January 2005

A broad set of sufficient conditions consisting of systems of linear partial differential equations is presented which guarantees that the Wronskian determinant solves the Korteweg-de Vries equation in the bilinear form. A systematical analysis is made for solving the resultant linear systems of second-order and third-order partial differential equations, along with solution formulas for their representative systems. The key technique is to apply variation of parameters in solving the involved non-homogeneous partial differential equations. The obtained solution formulas provide us with a comprehensive approach to construct the existing solutions and many new solutions including rational solutions, solitons, positons, negatons, breathers, complexitons and interaction solutions of the Korteweg-de Vries equation.
Toric residue and combinatorial degree
Authors: Soprounov Ivan
Published: January 2005

Consider an

n
n

-dimensional projective toric variety

X
X

defined by a convex lattice polytope

P
P

. David Cox introduced the toric residue map given by a collection of

n
+
1

n+1

divisors

(

Z
0

,
…
,

Z
n

)

(Z_0,\dots ,Z_n)

on

X
X

. In the case when the

Z
i

Z_i

are

T

\mathbb {T}

-invariant divisors whose sum is

X
∖

T

X\setminus \mathbb {T}

, the toric residue map is the multiplication by an integer number. We show that this number is the degree of a certain map from the boundary of the polytope

P
P

to the boundary of a simplex. This degree can be computed combinatorially. We also study radical monomial ideals

I
I

of the homogeneous coordinate ring of

X
X

. We give a necessary and sufficient condition for a homogeneous polynomial of semiample degree to belong to

I
I

in terms of geometry of toric varieties and combinatorics of fans. Both results have applications to the problem of constructing an element of residue one for semiample degrees.
Existence and asymptotic behavior for a singular parabolic equation
Authors: Dávila Juan , Montenegro Marcelo
Published: January 2005

We prove global existence of nonnegative solutions to the singular parabolic equation
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="u Subscript t Baseline minus normal upper Delta u plus chi Subscript left-brace u greater-than 0 right-brace Baseline left-parenthesis minus u Superscript negative beta Baseline plus lamda f left-parenthesis u right-parenthesis right-parenthesis equals 0">

u
t

−
Δ
u
+

χ

{
u
>
0
}

(
−

u

−
β

+
λ
f
(
u
)
)
=
0

u_t -\Delta u + \chi _{ \{ u>0 \} } ( -u^{-\beta } + \lambda f(u) )=0

in a smooth bounded domain

Ω
⊂

R

N

\Omega \subset \mathbb {R}^N

with zero Dirichlet boundary condition and initial condition

u
0

∈
C
(
Ω
)

u_0 \in C(\Omega )

,

u
0

≥
0

u_0 \geq 0

. In some cases we are also able to treat

u
0

∈

L
∞

(
Ω
)

u_0 \in L^\infty (\Omega )

. Then we show that if the stationary problem admits no solution which is positive a.e., then the solutions of the parabolic problem must vanish in finite time, a phenomenon called “quenching”. We also establish a converse of this fact and study the solutions with a positive initial condition that leads to uniqueness on an appropriate class of functions.
Percolation–like scaling exponents for minimal paths and trees in the stochastic mean field model
Authors: Aldous David J.
Published: January 2005

In the mean field (or random link) model there arenpoints and inter-point distances are independent random variables. For 0 <ℓ< ∞ and in then→ ∞ limit, letδ(ℓ) = 1/ntimes the maximum number of steps in a path whose average step-length is ≤ℓ. The functionδ(ℓ) is analogous to thepercolation functionin percolation theory: there is a critical valueℓ*= e−1at whichδ(·) becomes non-zero, and (presumably) a scaling exponentβin the senseδ(ℓ) ≈ (ℓ−ℓ*)β. Recently developed probabilistic methodology (in some sense a rephrasing of the cavity method developed in the 1980s by Mézard and Parisi) provides a simple, albeit non-rigorous, way of writing down such functions in terms of solutions of fixed-point equations for probability distributions. Solving numerically gives convincing evidence thatβ= 3. A parallel study withtreesandconnected edge-setsin place of paths gives scaling exponent 2, while the analogue for classical percolation has scaling exponent 1. The new exponents coincide with those recently found in a different context (comparing optimal and near-optimal solutions of the mean-field travelling salesman problem (TSP) and the minimum spanning tree (MST) problem), and reinforce the suggestion that scaling exponents determine universality classes for optimization problems on random points.
Effects of Bragg peak profiles and nanoparticle sizes on the real-space pair distribution function
Authors: Jeong Il-Kyoung , Graf M. J. , Heffner R. H.
Published: January 2005

A study of the effects of Bragg peak profiles and nanoparticle size broadening on the real-space pair distribution function (PDF) is presented, using `synthetic' powder diffraction data. Bragg peak profiles from both asymmetric time-of-flight (TOF) spallation neutron data and symmetric synchrotron X-ray data are considered. Due to their asymmetric peak profiles, the TOF data cause artificial shifts of the PDF peak positions towards higher pair distances. Coupled with this effect is a broadening of the PDF peak widths due to aQ-dependent spectrometer resolution, making reliable refinement of thermal parameters difficult. These effects become more pronounced as theQresolution becomes worse. By contrast, the symmetric X-ray powder diffraction data do not cause a systematic shift of the PDF peak positions, and the broadening of the PDF peak widths has a relatively minor effect on the extraction of the thermal parameters. Finally, nanoparticle size broadening of the asymmetric neutron TOF powder diffraction data causes a shift of the PDF peak positions towards lowerrvalues and smears the PDF intensities from one atomic shell to another.
A `static' high-resolution X-ray diffractometer
Authors: Fewster Paul F.
Published: January 2005

This new diffractometer utilizes angular and spatial aspects to create a motionless high-resolution X-ray diffractometer that will collect good quality data within one second. The instrument is configured specifically for different materials, but when set the sample to be analysed need only be placed approximately on a mount prior to data collection. By appropriate use of reciprocal space, the wavelength dispersion is limited, and by using real space the spatial resolution can create data of high angular resolution. The components of the diffractometer rely on a solid-state position-sensitive detector. The quality of the scattering profile is found to be essentially independent of the exact orientation of the sample. The scattering profile is simulated to include the spectral contribution and all the components of the diffractometer. The experimental profiles and the resulting model, through simulation, are compared with those from a conventional high-resolution diffractometer for an InGaAs structure and a SiGe structure.
CURVIS: a program to study and analyse crystallographic structures and phase transitions
Authors: Piotto Stefano , Nesper Reinhard
Published: January 2005

The visualization of scientific data is, nowadays, of extreme importance. Phase transitions, the topology of a crystallographic system, the electron density distribution inside a lattice or the changes in crystal structure during phase transitions cannot be fully investigated without the help of proper visualization. The programCURVIS(downloadable free of charge upon request) was developed as a tool for investigating crystal structures and occurring transitions. In this tool, some features are implemented to analyse, display and manage the three-dimensional structure of crystals and single molecules. More importantly,CURVIScan generate and handle hyperbolic surfaces in three dimensions, and provide specific routines to perform calculations of curvature and energy of such surfaces. The most important features are (i) file format conversion (with assignment of the atom types and atomic charges), (ii) surface calculation and (iii) curvature and surface-energy analysis.