bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Interrupted Cutting by Temporal Finite Element Analysis
Authors: Bayly P. V. , Halley J. E. , Mann B. P. , Davies M. A.
Published: April 2003

Chatter in milling and other interrupted cutting operations occurs at different combinations of speed and depth of cut from chatter in continuous cutting. Prediction of stability in interrupted cutting is complicated by two facts: (1) the equation of motion when cutting is not the same as the equation when the tool is free; (2) no exact analytical solution is known when the tool is in the cut. These problems are overcome by matching the free response with an approximate solution that is valid while the tool is cutting. An approximate solution, not restricted to small times in the cut, is obtained by the application of finite elements in time. The complete, combined solution is cast in the form of a discrete map that relates position and velocity at the beginning and end of each element to the corresponding values one period earlier. The eigenvalues of the linearized map are used to determine stability. This method can be used to predict stability for arbitrary times in the cut; the current method is applicable only to a single degree of freedom. Predictions of stability for a 1-degree of freedom case are confirmed by experiment.
Machining Simulation of Ductile Iron and Its Constituents, Part 1: Estimation of Material Model Parameters and Their Validation
Authors: Chuzhoy L. , DeVor R. E. , Kapoor S. G. , Beaudoin A. J. , Bammann D. J.
Published: April 2003

A microstructure-level simulation model was recently developed to characterize machining behavior of heterogeneous materials. During machining of heterogeneous materials such as cast iron, the material around the machining-affected zone undergoes reverse loading, which manifests itself in permanent material softening. In addition, cracks are formed below and ahead of the tool. To accurately simulate machining of heterogeneous materials the microstructure-level model has to reproduce the effect of material softening on reverse loading (MSRL effect) and material damage. This paper describes procedures used to calculate the material behavior parameters for the aforementioned phenomena. To calculate the parameters associated with the MSRL effect, uniaxial reverse loading experiments and simulations were conducted using individual constituents of ductile iron. The material model was validated with reverse loading experiments of ductile iron specimens. To determine the parameters associated with fracture of each constituent, experiments and simulation of notched specimens are performed. During the validation stage, response of simulated ductile iron was in good agreement with the experimental data.
Surface Finish Enhancement in a Turning Operation via Adaptive STR Control of the Depth of Cut
Authors: Liasi E. , North W. P. T.
Published: April 2003

In this paper, an integrated model for a turning process (in the radial direction) is presented. Furthermore, properties of adaptive control and more specifically self-tuning regulators (STR) are discussed and a self-tuning regulator is designed based on LQG methods. The objective is to suppress the radial vibrations due to surface micro-hardness variations and hence improve the resulting surface finish. The effectiveness of the control system is evaluated by means of computer simulations—a case study is presented.
A Predictive Model for Variation in the Pitch Between Stamped Pilot Holes
Authors: Vallance R. Ryan , Kiani Sepehr
Published: April 2003

This paper presents an analytical model for predicting the variation in the pitch distance between pilot holes stamped with a progressive die. The model is useful in designing diesets since it relates pitch variation to dieset parameters such as the quantity of pilot pins, clearance in the stripper plate bearings, clearance about the punch, and clearance about the pilot pins. The efficacy of the predictive model is demonstrated with a sensitivity study of design parameters in an exemplary dieset used to stamp electrical contacts. Predictions from the model match previously measured variation within about twenty-four percent.
Cost-Effective Grinding of Zirconia Using the Dense Vitreous Bond Silicon Carbide Wheel
Authors: Shih Albert J. , Scattergood Ronald O. , Curry Adam C. , Yonushonis Thomas M. , Gust Darryl J. , Grant Marion B. , McSpadden Samuel B. , Watkins Thomas R.
Published: April 2003

Results of grinding zirconia using wheels with fine grain size SiC and dense vitreous bond are presented. Wheel wear results demonstrated that this type of SiC wheel could grind fully and partially stabilized zirconia (PSZ) very effectively. X-ray diffraction was used to analyze the percentage of monoclinic phase in the PSZ base material, ground surface, and debris. As expected, due to the stress- and temperature-induced phase transformation during grinding, the percentage of monoclinic phase on the ground surface was increased relative to the base material. However, X-ray diffraction showed no monoclinic phase in the PSZ debris. This suggests that, during grinding, the low thermal conductivity of zirconia and SiC, compared to that of diamond, facilitates heat retention in the chip and softens the work-material. This makes the efficient grinding of PSZ possible. Grinding temperature measurement results supported this hypothesis.
Using Reconfigurable Tooling and Surface Heating for Incremental Forming of Composite Aircraft Parts
Authors: Walczyk Daniel F. , Hosford Jean F. , Papazian John M.
Published: April 2003

The application of composites in the aircraft industry has increased significantly over the past few decades. With traditional composite laminate shaping, each layer is made to conform to the mold surface by hand before subsequent layers are added. This is a very labor- and time-intensive process. There is a great deal of interest in developing an automated process for forming composite parts with compound curvatures. The proposed composite forming process utilizes a computer-controlled, reconfigurable discrete element mold to incrementally form a compound curvature part shape from a flat lay-up, thereby facilitating process automation. An elastomeric interpolating layer, called an interpolator, is placed on top of the hemispherical forming ends of the die elements to prevent dimpling of the composite lay-up. The process employs vacuum to pull a single diaphragm (top), composite, and interpolator into contact with the mold surface. Through an experimental investigation, this new composites forming process with “active” tooling has been successfully demonstrated. Heating of the composite is accomplished by uncontained, forced convection using a matrix of heated air jets mounted above the composite. However, low-powered conduction is shown to be the best heating method in terms of both composite heating time and minimization of through-thickness temperature. Using vacuum to conform both the composite and the interpolator to the mold, and choosing sufficiently stiff diaphragm and interpolator materials, undimpled and wrinkle-free composite parts have been formed in an incremental fashion.
A 23,000-Year Record of Surface Water pH and
P
CO
2
in the Western Equatorial Pacific Ocean
Authors: Palmer M. R. , Pearson P. N.
Published: April 2003

The oceans play a major role in defining atmospheric carbon dioxide (CO
2
) levels, and although the geographical distribution of CO
2
uptake and release in the modern ocean is understood, little is known about past distributions. Boron isotope studies of planktonic foraminifera from the western equatorial Pacific show that this area was a strong source of CO
2
to the atmosphere between approximately 13,800 and 15,600 years ago. This observation is most compatible with increased frequency of La Niña conditions during this interval. Hence, increased upwelling in the eastern equatorial Pacific may have played an important role in the rise in atmospheric CO
2
during the last deglaciation.
Role of Polo-like Kinase
CDC5
in Programming Meiosis I Chromosome Segregation
Authors: Lee Brian H. , Amon Angelika
Published: April 2003

Meiosis is a specialized cell division in which two chromosome segregation phases follow a single DNA replication phase. The budding yeast Polo-like kinase Cdc5 was found to be instrumental in establishing the meiosis I chromosome segregation program. Cdc5 was required to phosphorylate and remove meiotic cohesin from chromosomes. Furthermore, in the absence of
CDC5
kinetochores were bioriented during meiosis I, and Mam1, a protein essential for coorientation, failed to associate with kinetochores. Thus, sister-kinetochore coorientation and chromosome segregation during meiosis I are coupled through their dependence on
CDC5
.
Microstructural Optimization of a Zeolite Membrane for Organic Vapor Separation
Authors: Lai Zhiping , Bonilla Griselda , Diaz Isabel , Nery Jose Geraldo , Sujaoti Khristina , Amat Miguel A. , Kokkoli Efrosini , Terasaki Osamu , Thompson Robert W. , Tsapatsis Michael , Vlachos Dionisios G.
Published: April 2003

A seeded growth method for the fabrication of high-permeance, high-separation-factor zeolite (siliceous ZSM-5, [Si
96
O
192
]-MFI) membranes is reported. The method consists of growing the crystals of an oriented seed layer to a well-intergrown film by avoiding events that lead to a loss of preferred orientation, such as twin overgrowths and random nucleation. Organic polycations are used as zeolite crystal shape modifiers to enhance relative growth rates along the desirable out-of-plane direction. The polycrystalline films are thin (∼1 micrometer) with single grains extending along the film thickness and with large in-plane grain size (∼1 micrometer). The preferred orientation is such that straight channels with an open diameter of ∼5.5 angstroms run down the membrane thickness. Comparison with previously reported membranes shows that these microstructurally optimized films have superior performance for the separation of organic mixtures with components that have small differences in size and shape, such as xylene isomers.
On the Origins of Morphological Complexity in Block Copolymer Surfactants
Authors: Jain Sumeet , Bates Frank S.
Published: April 2003

Amphiphilic compounds such as lipids and surfactants are fundamental building blocks of soft matter. We describe experiments with poly(
1,2
-butadiene-
b
-ethylene oxide) (PB-PEO) diblock copolymers, which form Y-junctions and three-dimensional networks in water at weight fractions of PEOintermediate to those associated with vesicle and wormlike micelle morphologies. Fragmentation of the network produces a nonergodic array of complex reticulated particles that have been imaged by cryogenic transmission electron microscopy. Data obtained with two sets of PB-PEOcompounds indicate that this type of self-assembly appears above a critical molecular weight. These block copolymers represent versatile amphiphiles, mimicking certain low molecular weight three-component (surfactant/water/oil) microemulsions, without addition of a separate hydrophobe.
Mantle Fault Zone Beneath Kilauea Volcano, Hawaii
Authors: Wolfe Cecily J. , Okubo Paul G. , Shearer Peter M.
Published: April 2003

Relocations and focal mechanism analyses of deep earthquakes (≥13 kilometers) at Kilauea volcano demonstrate that seismicity is focused on an active fault zone at 30-kilometer depth, with seaward slip on a low-angle plane, and other smaller, distinct fault zones. The earthquakes we have analyzed predominantly reflect tectonic faultingin the brittle lithosphere rather than magma movement associated with volcanic activity. The tectonic earthquakes may be induced on preexisting faults by stresses of magmatic origin, although background stresses from volcano loading and lithospheric flexure may also contribute.
Tubular Graphite Cones
Authors: Zhang Guangyu , Jiang Xin , Wang Enge
Published: April 2003

We report the synthesis of tubular graphite cones using a chemical vapor deposition method. The cones have nanometer-sized tips, micrometer-sized roots, and hollow interiors with a diameter ranging from about 2 to several tens of nanometers. The cones are composed of cylindrical graphite sheets; a continuous shortening of the graphite layers from the interior to the exterior makes them cone-shaped. All of the tubular graphite cones have a faceted morphology. The constituent graphite sheets have identical chiralities of a zigzag type across the entire diameter, imparting structural control to tubular-based carbon structures. The tubular graphite cones have potential for use as tips for scanning probe microscopy, but with greater rigidity and easier mounting than currently used carbon nanotubes.
Assembly of Cell Regulatory Systems Through Protein Interaction Domains
Authors: Pawson Tony , Nash Piers
Published: April 2003

The sequencing of complete genomes provides a list that includes the proteins responsible for cellular regulation. However, this does not immediately reveal what these proteins do, nor how they are assembled into the molecular machines and functional networks that control cellular behavior. The regulation of many different cellular processes requires the use of protein interaction domains to direct the association of polypeptides with one another and with phospholipids, small molecules, or nucleic acids. The modular nature of these domains, and the flexibility of their binding properties, have likely facilitated the evolution of cellular pathways. Conversely, aberrant interactions can induce abnormal cellular behavior and disease. The fundamental properties of protein interaction domains are discussed in this review and in detailed reviews on individual domains at
Science
's STKE at
http://www.sciencemag.org/cgi/content/full/300/5618/445/DC1
.
Dilemmas of a Divisive Concept
Authors: Cho Mildred , Grainger-Monsen Maren
Published: April 2003

Race
The Power of an Illusion. Larry Adelman, Executive Producer. California Newsreel, San Francisco. On PBS, Thursdays, 24 April to 8 May 2003. Companion Web site,
www.pbs.org/race

This three-part series on PBS examines the idea of race from the varied perspectives of science, history, and our social institutions.
A MOLECULAR MODEL POTENTIAL STUDY OF THE HOMO–LUMO GAP IN A LOW-DIMENSIONAL CRYSTAL
Authors: LETELIER JORGE RICARDO , TORO-LABBÉ ALEJANDRO , CHIU YING-NAN
Published: April 2003

We study the effect of some crystal vibrations on the electron distribution and the gap HOMO–LUMO in a linear chain of atoms where, the valence electrons move in a model potential constructed by combining atromic boxes. It is found that at the turning points, these two levels collapse together for a chain with an even number of atoms while for a chain with an odd number of atoms these two levels never touch each other.

The effect of some asymmetric crystal vibrations on the electron density distribution and the gap HOMO–LUMO is also analyzed for a low-dimensional solid whose repeating unit consists of a square arrangement of atoms where the valence electrons move in a CAB model potential.
MONTE CARLO INVESTIGATION OF THREE-EXPONENT SCALING IN THE 5D ISING MODEL
Authors: CHEON MOOKYUNG , CHANG IKSOO , STAUFFER DIETRICH
Published: April 2003

Simulations with up to 1125 spins confirm the prediction of Chen and Dohm of three different finite-size exponents for the spontaneous magnetization near the Curie point.
MONTE CARLO STUDY OF SURFACE REACTIONS: BIDIRECTIONAL MONOMER-DIMER REACTION ON MODIFIED SURFACES
Authors: PATRYKIEJEW A. , SAWCZUK J. , SOKOŁOWSKI S. , SZABELSKI P.
Published: April 2003

The Monte Carlo simulation method is used to study monomer-dimer bidirectional reactions on modified surfaces. The assumed model predicts that reaction leads to different products depending on the state of reacting molecules, which depends on the state of adjacent adsorbing sites. The model assumes that the catalyst surface is precovered by a certain amount of modifier, which partially deactivates the surface and changes the state of the adsorbed reactant species. It is demonstrated that the surface concentration of the modifier atoms and the topography of their distribution over the surface are both important factors which influence the behavior of systems considered in this paper. In particular, it has been found that the reaction direction, the reaction window location and its width depend strongly on the surface morphology. The results are in a good qualitative agreement with the experimentally observed changes in the direction of the methanol oxidation on the sulfur-modified Fe(100) catalyst.
THE OPTIMIZED MODEL OF MULTIPLE INVASION PERCOLATION
Authors: ZARA REGINALDO A. , ONODY ROBERTO N.
Published: April 2003

We study the optimized version of the multiple invasion percolation model. Some topological aspects as the behavior of the acceptance profile, coordination number and vertex type abundance were investigated and compared to those of the ordinary invasion. Our results indicate that the clusters show a very high degree of connectivity, spoiling the usual nodes-links-blobs geometrical picture.
THE EQUILIBRIUM OF A VELOCITY-VERLET TYPE ALGORITHM FOR DPD WITH FINITE TIME STEPS
Authors: GIBSON J. B. , CHEN K. , CHYNOWETH S.
Published: April 2003

Dissipative particle dynamics (DPD) originated as a tool for performing fluid dynamics simulations of complex fluids and amongst other things has been used to simulate dilute polymer solutions. The technique employed an Euler time-stepping technique up until recently, when a velocity-Verlet type algorithm was proposed. This paper presents a more accurate velocity-Verlet and analyses the equilibrium properties of this new technique for finite time-steps. An expression for the temperature in terms of the basic DPD parameters is derived for this scheme.
SWITCHING BOUNDARY CONDITIONS IN THE MANY-BODY DIFFUSION ALGORITHM
Authors: LUCZAK F. , BROSENS F. , DEVREESE J. T. , LEMMENS L. F.
Published: April 2003

In this paper we show how the transposition, the basic operation of the permutation group, can be taken into account in a diffusion process of identical particles. Whereas in an earlier approach the method was applied to systems in which the potential is invariant under interchanging the Cartesian components of the particle coordinates, this condition on the potential is avoided here. In general, the potential introduces a switching of the boundary conditions of the walkers. These transitions modelled by a continuous-time Markov chain generate sample paths for the propagator as a Feynman–Kac functional. A few examples, including harmonic fermions with an anharmonic interaction, and the ground-state energy of ortho-helium are studied to elucidate the theoretical discussion and to illustrate the feasibility of a sign-problem-free implementation scheme for the recently developed many-body diffusion approach.
FIRST AND SECOND ORDER TRANSITIONS IN DILUTE O(n) MODELS
Authors: GUO WENAN , BLÖTE HENK W. J. , NIENHUIS BERNARD
Published: April 2003

We explore the phase diagram of an O (n) model on the honeycomb lattice with vacancies, using finite-size scaling and transfer-matrix methods. We make use of the loop representation of the O (n) model, so that n is not restricted to positive integers. For low activities of the vacancies, we observe critical points of the known universality class. At high activities the transition becomes first order. For n=0 the model includes an exactly known theta point, used to describe a collapsing polymer in two dimensions. When we vary n from 0 to 1, we observe a tricritical point which interpolates between the universality classes of the theta point and the Ising tricritical point.
ON A CONSERVATIVE LAVA FLOW AUTOMATON
Authors: MATOS J. A. O. , DUARTE J. A. M. S.
Published: April 2003

A simple lava flow automaton is discretized, three different variants are shown to exhibit a wide range of behavior, while some geometrical and shape characteristics are analysed. We respect, on an underlying square topology, equalization of lava height between nearest neighbors (whenever possible), and update the evolution in parallel. This model is a discretized version (as regards the lava level) of a very successful continuous height automaton, but with no local loss through cooling.
APPLICATION OF FINITE ELEMENT METHOD TO SOLVE 2D PROBLEMS RELATED TO NEMATIC SURFACE PROPERTIES
Authors: BARBERI R. , IOVANE M. , FERRERO C. , MOCELLA V.
Published: April 2003

This paper is devoted to numerical studies of two-dimensional problems concerning surface properties of nematic liquid crystals. We use a finite element method, based essentially on the classic variational approach, to find an approximate solution minimizing the Gibbs free energy of the nematic material under given boundary conditions. Three examples illustrate the performance and versatility of this analysis. Two cases are related to the macroscopic orientation induced by periodic boundary conditions: the first is a saw-toothed substrate in the micrometric range and the second is a microtextured surface. We analyze the bulk planar–homeotropic transition conditions for both of them. In the third case, we study the coupling between the spatial variation of the nematic director and that of the order parameter in the presence of surface-induced distortion.
TRANSFER-MATRIX STUDY OF NEGATIVE-FUGACITY SINGULARITY OF HARD-CORE LATTICE GAS
Authors: TODO SYNGE
Published: April 2003

A singularity on the negative-fugacity axis of the hard-core lattice gas is investigated in terms of numerical diagonalization of large-scale transfer matrices. For the hard-square lattice gas, the location of the singular point [Formula: see text] and the critical exponent ν are accurately determined by the phenomenological renormalization technique as -0.11933888188(1) and 0.416667(1), respectively. It is also found that the central charge c and the dominant scaling dimension xσ are -4.399996(8) and -0.3999996(7), respectively. Similar analyses for other hard-core lattice-gas models in two dimensions are also performed, and it is confirmed that the universality between these models does hold. These results strongly indicate that the present singularity belongs to the same universality class as the Yang–Lee edge singularity.
SOME HINTS ON OPEN READING FRAME STATISTICS — HOW ORF LENGTH DEPENDS ON SELECTION
Authors: GIERLIK AGNIESZKA , MACKIEWICZ PAWEŁ , KOWALCZUK MARIA , CEBRAT STANISŁAW , DUDEK MIROSŁAW R.
Published: April 2003

Coding sequences of DNA generate Open Reading Frames (ORFs) inside them with much higher frequency than random DNA sequences do, especially in the antisense strand. This is a specific feature of the genetic code. Since coding sequences are selected for their length, the generated ORFs are indirect results of this selection and their length is also influenced by selection. That is why ORFs found in any genome, even much longer ones than those spontaneously generated in random DNA sequences, should be considered as two different sets of ORFs: The first one coding for proteins, the second one generated by the coding ORFs. Even intergenic sequences possess greater capacity for generating ORFs than random DNA sequences of the same nucleotide composition, which seems to be a premise that intergenic sequences were generated from coding sequences by recombinational mechanisms.
EVALUATION OF A FULLY 3-D BPF METHOD FOR SMALL ANIMAL PET IMAGES ON MIMD ARCHITECTURES
Authors: BEVILACQUA A.
Published: April 2003

Positron Emission Tomography (PET) images can be reconstructed using Fourier transform methods. This paper describes the performance of a fully 3-D Backprojection-Then-Filter (BPF) algorithm on the Cray T3E machine and on a cluster of workstations. PET reconstruction of small animals is a class of problems characterized by poor counting statistics. The low-count nature of these studies necessitates 3-D reconstruction in order to improve the sensitivity of the PET system: by including axially oblique Lines Of Response (LORs), the sensitivity of the system can be significantly improved by the 3-D acquisition and reconstruction. The BPF method is widely used in clinical studies because of its speed and easy implementation. Moreover, the BPF method is suitable for on-time 3-D reconstruction as it does not need any sinogram or rearranged data. In order to investigate the possibility of on-line processing, we reconstruct a phantom using the data stored in the list-mode format by the data acquisition system. We show how the intrinsically parallel nature of the BPF method makes it suitable for on-line reconstruction on a MIMD system such as the Cray T3E. Lastly, we analyze the performance of this algorithm on a cluster of workstations.
ONE DIMENSIONAL nARY DENSITY CLASSIFICATION USING TWO CELLULAR AUTOMATON RULES
Authors: CHAU H. F. , SIU L. W. , YAN K. K.
Published: April 2003

Suppose each site on a one-dimensional chain with periodic boundary condition may take on any one of the states 0,1,…,n-1; can you find out the most frequently occurring state using cellular automaton? Here, we prove that while the above density classification task cannot be resolved by a single cellular automaton, this task can be performed efficiently by applying two cellular automaton rules in succession.
UNIVERSALITY CLASS FOR BOOTSTRAP PERCOLATION WITH m=3 ON THE CUBIC LATTICE
Authors: BRANCO N. S. , SILVA CRISTIANO J.
Published: April 2003

We study the m = 3 bootstrap percolation model on a cubic lattice, using Monte Carlo simulation and finite-size scaling techniques. In bootstrap percolation, sites on a lattice are considered occupied (present) or vacant (absent) with probability p or 1-p, respectively. Occupied sites with less than m occupied first-neighbors are then rendered unoccupied; this culling process is repeated until a stable configuration is reached. We evaluate the percolation critical probability, pc, and both scaling powers, yp and yh, and, contrary to previous calculations, our results indicate that the model belongs to the same universality class as usual percolation (i.e., m=0). The critical spanning probability, R(pc), is also numerically studied for systems with linear sizes ranging from L=32 up to L=480; the value we found, R(pc)=0.270±0.005, is the same as for usual percolation with free boundary conditions.
ANTIGEN RECOGNITION AND EVOLUTION IN A BIT-STRING POPULATION MODEL
Authors: CASTIGLIONE FILIPPO
Published: April 2003

We present a simple model of selection and mutation of cell populations in the immune system. This is based on generic assumptions and in this respect it resembles a model for evolution in simple ecosystems. In this case the selection acts by means of the affinity function representing the ability of a certain class of lymphocytes to recognize a foreign antigen. Carrying out some analytical and numerical studies we determine the critical values for the parameters ruling the selection and mutation.
ON BOUNDARY CONDITIONS IN THE FINITE VOLUME LATTICE BOLTZMANN METHOD ON UNSTRUCTURED MESHES
Authors: PENG GONGWEN , XI HAOWEN , CHOU SO-HSIANG
Published: April 2003

Boundary conditions in a recently-proposed finite volume lattice Boltzmann method are discussed. Numerical simulations for simple shear flow indicate that the extrapolation and the half-covolume techniques for the boundary conditions are workable in conjunction with the finite volume lattice Boltzmann method for arbitrary meshes.
AN INTEGRATION SCHEME FOR REACTION–DIFFUSION MODELS
Authors: NITTI MASSIMO , TORCINI ALESSANDRO , RUFFO STEFANO
Published: April 2003

A detailed description and validation of a recently developed integration scheme is here reported for one- and two-dimensional reaction–diffusion models. As paradigmatic examples of this class of partial differential equations the complex Ginzburg–Landau and the Fitzhugh–Nagumo equations have been analyzed. The novel algorithm has precision and stability comparable to those of pseudo-spectral codes, but is more convenient to be employed for systems with large linear extention L. As for finite-difference methods, the implementation of the present scheme requires only information about the local enviroment and this allows us to treat systems with very complicated boundary conditions.
MINIMIZING STORAGE IN IMPLEMENTATIONS OF THE OVERLAP LATTICE-DIRAC OPERATOR
Authors: NEUBERGER HERBERT
Published: April 2003

The overlap lattice-Dirac operator contains the sign function ∊(H). Recent practical implementations replace ∊(H) by a ratio of polynomials, H Pn(H2)/Qn(H2), and require storage of 2n+2 large vectors. Here I show that one can use only four large vectors at the cost of executing the core conjugate algorithm twice. The slow-down might be less than by a factor of 2, depending on the architecture of the computer one uses.
ON THE PHYSICAL APPLICATION OF SIMULATED ANNEALING ALGORITHM
Authors: LI SHU-YOU , DU ZHI-HUI , WU MENG-YUE , ZHU JING , LI SAN-LI
Published: April 2003

A high-performance general program is presented to deal with the multi-parameter optimization problems in physics. Considering the requirements of physical application, some small but significant modifications were made on the conventional simulated annealing algorithm. A parallel realization was suggested to further improve the performance of the program. Mathematical and physical examples were taken to test the feasibility and the efficiency of the program. The source code is available from the authors free of charge.
THE CLUSTER PROCESSOR: NEW RESULTS
Authors: BLÖTE HENK W. J. , SHCHUR LEV. N. , TALAPOV ANDREI L.
Published: April 2003

We present a progress report on the Cluster Processor, a special-purpose computer system for the Wolff simulation of the three-dimensional Ising model, including an analysis of simulation results obtained thus far. These results allow, within narrow error margins, a determination of the parameters describing the phase transition of the simple-cubic Ising model and its universality class. For an improved determination of the correction-to-scaling exponent, we include Monte Carlo data for systems with nearest-neighbor and third-neighbor interactions in the analysis.
AVALANCHE DYNAMICS AND TRADING FRICTION EFFECTS ON STOCK MARKET RETURNS
Authors: IORI GIULIA
Published: April 2003

We propose a model with heterogeneous interacting traders which can explain some of the stylized facts of stock market returns. A generalized version of the Random Field Ising Model (RFIM) is introduced to describe trading behavior. Imitation effects, which induce agents to trade, can generate avalanches in trading volume and large gaps in demand and supply. A trade friction is introduced which, by responding to price movements, creates a feedback mechanism on future trading and generates volatility clustering.
INFLUENCE OF FINITE CAPITAL IN THE CONT–BOUCHAUD-MODEL FOR MARKET FLUCTUATIONS
Authors: LIEBREICH J.
Published: April 2003

Introducing a finite capital of the shareholders in the Cont–Bouchaud-model leads to a partially realistic wealth distribution for middle positions in the wealth hierarchy. However, the number of poor shareholders is too small and the capitals of the wealthiest ones are too low. Also variation of the simulation time, of the activity and consideration of the fundamentalists' influence does not give data in agreement with reality.
SLOW DYNAMICS AT QUANTUM PHASE TRANSITIONS
Authors: YOUNG A. P.
Published: April 2003

This paper discusses how slow dynamics can occur in the vicinity of quantum phase transitions. In addition to critical slowing down, there are two additional sources of slow dynamics. Firstly, even for a pure system, there is a phase coherence time which diverges as the temperature tends to zero. This is hard to see from numerical studies in imaginary time and real time dynamics are needed. Secondly, in random systems, Griffiths–McCoy singularities occur at low temperature because of rare regions which are "locally in the wrong phase" due to of statistical fluctuations in the random interactions. These are particularly strong for systems with discrete, e.g., Ising, symmetry. The form of Griffiths–McCoy singularities in real time is not understood.
DROPLETS AND DOMAIN WALLS IN 2D EDWARDS–ANDERSON MODEL
Authors: KAWASHIMA NAOKI
Published: April 2003

A heuristic optimization algorithm is developed based on the renormalization group idea and applied to the Edwards–Anderson model in two dimensions with symmetric Gaussian bond distribution. Droplets are forced to excite by the boundary condition. We find that the droplets have nontrivial fractal dimension not only for its surface but also for its volume, in contrast to what has been implicitly assumed in conventional droplet arguments.
COMPUTER SIMULATION OF BIOLOGICAL MACROMOLECULES IN GENERALIZED ENSEMBLES
Authors: HANSMANN ULRICH H. E.
Published: April 2003

For many years the emphasis in protein-folding simulations has been laid as to how to predict the three-dimensional structure of proteins. Only recently has there be a shift in interest towards the thermodynamics of folding. We show that generalized-ensemble techniques are well suited to study both questions for realistic protein models.
ON THE FRACTAL MODEL OF THE POROUS LAYER FORMATION
Authors: AROUTIOUNIAN V. M. , GHULINYAN M. Zh.
Published: April 2003

In the present paper, a fractal model of a porous layer formation is proposed. The consideration of the time-dependent pore growth process has allowed us to calculate such important parameters of porous matrix as the formed surface area, and surface and volume porosity values. We have theoretically shown that the formed surface area strongly depends on the difference between the pore size growth velocities parallel and perpendicular to the surface, i.e. the crystallographic orientation of the material surface. The volume and surface porosity values as well as the formed porous surface area are linear functions on the anodization current density. These results are in rather good agreement with other theoretical and experimental data.
EXACT SOLUTION OF SLOWLY VARYING ENVELOPE APPROXIMATION EQUATIONS FOR PLANE WAVE PROPAGATION OF LIGHT IN LOSSY ISOTROPIC NONLINEAR MEDIUM
Authors: PRAKASH HARI , CHANDRA NARESH , PRAKASH RANJANA
Published: April 2003

Nonlinear coupled differential equations for Stokes parameters for plane wave propagation of light in an isotropic medium having third-order nonlinearity are obtained in slowly varying envelope approximation and solved exactly for arbitrary linear and nonlinear losses. Numerical solution in general and analytic solutions in special cases exist. Vibration ellipse is seen to rotate and change in shape. Only plane and circular polarizations are stable and others change. This change is large when absorption is mainly nonlinear, and for purely nonlinear absorption, polarization tends asymptotically to either plane or circular. An example of analytic exact solution is discussed.
ENERGY DEPENDENCE OF DYNAMICAL INSTABILITY IN ONE-DIMENSIONAL LENNARD–JONES SYSTEM
Authors: OKABE TSUNEYASU , YAMADA HIROAKI
Published: April 2003

We have reported energy dependence of maximal Lyapunov exponent in one-dimensional Lennard–Jones (LJ) system in previous papers [Int. J. Mod. Phys.B12, 901 (1998); Mod. Phys. Lett.B12, 615 (1998)]. The existence of the plateau region, in which the energy dependence is insensitive, has been shown as a remarkable feature of the LJ system, different from FPU and soft-core system. In this paper, we investigate the details of the characteristics of dynamical property in the plateau region, by means of Lyapunov spectra and distribution of local maximal Lyapunov exponents.
Finite-Temperature Effects in Bose-Einstein Condensates
Authors: Burnett Keith
Published: April 2003

In this article we discuss aspects of fluctuations and correlations that arise in the theory of trapped condensates at finite temperature. This requires us to look at both thermal and quantum fluctuations in the field that describes the condensates. We discuss ways in which these effects can be observed in experiments.
The Theory of Atom Lasers
Authors: Ballagh R. J. , Savage C. M.
Published: April 2003

We review the current theory of atom lasers. A tutorial treatment of second quantisation and the Gross-Pitaevskii equation is presented, and basic concepts of coherence are outlined. The generic types of atom laser models are surveyed and illustrated by specific examples. We conclude with detailed treatments of the mechanisms of gain and output coupling.
Vortices and Solitons in Bose-Condensates
Authors: Drummond P. D.
Published: April 2003

The new science of nonlinear atom optics and atom lasers is evolving rapidly. There are similarities between many related areas in modern photonic and atom optics, particularly at the mean-field level. In both cases we can often use classical nonlinear wave equations to describe classical solitons, vortices, and other nonlinear structure. Atom-molecular coupling can be used to play the role of second-harmonic generation. This leads to novel types of soliton. In addition, quantum effects at low densities are likely to be readily observable.
ON-LINE VISUALIZATION AND NAVIGATION OF THE GLOBAL WEB STRUCTURE
Authors: HUANG MAO LIN , EADES PETER , LAI WEI
Published: April 2003

The current generation of web browsers, such as Netscape and Microsoft Explorer, excites people because of the structure of hyper-documents that provides users with an effective and convenient way to move in cyberspace. This is done through clicking on a series of hyperlinks embedded in hyper-documents. However, this arrangement does not give users a visual "map" to guide them in their web journey. It does not provide sense of "space" while the user is exploring the (cyber) space; instead it only gives a series of lists.

This is mainly because of the difficulty of constructing such a huge, complex, and dynamic map with an (virtually) unlimited number of nodes and edges. Because the whole web is partially unknown, it is difficult for mapmaker to draw the map. Further, the computation of the overall geometrical structure of such a huge map (with millions or perhaps billions of nodes) is impossible as most visualization algorithms have super-linear time complexity and only scale to a few hundred nodes.

Most existing visualization techniques and current research interests emphasize "site mapping". That is, they try to find an effective way of constructing a structured geometrical map for one web site (a local map). This can only guide the user through a very limited region of cyberspace, and does not help users in their overall journey through the cyberspace.

In this paper, we look at the whole journey through the cyberspace as one graph; a huge and partially unknown graph. We use our new on-line exploratory visualization technique [7] to maintain and display a subset of this huge graph incrementally. The Visual Web Browser consists of three major components: a fast accessible linkage server, a filtering mechanism, and an on-line exploratory visualization. The framework of these components provides the user with a dynamic graphical map for guiding the web journey.
A VISUAL SYSTEM SUPPORTING SOFTWARE REUSE IN THE BANKING LEGACY SYSTEM CONTEXT
Authors: COSTAGLIOLA GENNARO , FRANCESE RITA , SCANNIELLO GIUSEPPE
Published: April 2003

Banking legacy systems intensively exchange messages in electronic format. Such systems are, for their nature, difficult to update and maintain. As a consequence, the introduction of new types of messages is a hard task. Adding new functionalities requires custom coding and software reuse is seen as a key to obtain a better time-to-market factor, risk and cost reduction. In this paper we describe the architecture and part of the implementation of the SI.RE. Visual System, an Interbanking Network Information System that lets us generate gateways for the exchange of electronic messages among banking legacy systems and supports software reuse. In particular, the SI.RE visual system contains a Visual Programming Environment that allows us to obtain a rapid development of the message handling functions. This environment implements a Visual Programming Language UVG that allows a programmer to reuse COBOL routines.
PRODUCTS OF COMMUTATORS IN FREE GROUPS
Authors: AKHAVAN-MALAYERI MEHRI , RHEMTULLA AKBAR
Published: April 2003

Let F be the free group of rank 2, generated by x and y, and let w(x, y) ∈ F′ be a non-trivial word. We give elementary algebraic proofs and algorithms to (1) express [x, y]n as a product of [n/2] + 1 commutators and show this is the best possible; (2) show that (w(x, y))2 cannot be written as one w-word and if g ≠ 1 ∈ w(F) then show that the minimal number of w-words required to express gn as their product tends to infinity with n. Other results for free groups of higher rank are also presented.
Endoscopic Excision with CO2 Laser for the Treatment of Glottic Carcinomas
Authors: Chevalier Dominique , Fayoux Pierre , François Jérome
Published: April 2003

Endoscopic treatment of glottic carcinomas has received increasing attention since its introduction. It is an alternative to irradiation and external surgery. Despite good functional and oncological results, an endoscopic approach is not always indicated. Bad exposure of the larynx or of the tumour is the most important limitation of this technique. T1 glottic carcinomas are frequently treated by endoscopy. T2 glottic carcinomas have to be carefully evaluated before choosing the endoscopic approach. When properly indicated, oncologic results are similar with both techniques.
Risk of Late Fatal Secondary Hemorrhage in Laser Surgery of the Larynx
Authors: Kremer B. , Rinkel R.N.P.M. , Eckel H.E. , Schlöndorff G.
Published: April 2003

Objectives: Since 1979, a number of publications have appeared regarding complications of laser surgery of the larynx. Most publications focus on complications such as accidental burns, rouse of the ventilation tube, anesthesiologic problems, edema of the mucosa, and abnormal scar formation. Secondary hemorrhage has played a subordinate role and cases demanding postoperative treatment have only been reported sporadically. All cases occurred within the first postoperative week, and no case resulting in death has been reported. The aim of the article is to draw attention to the fact that after laser surgery of the larynx, late lethal secondary hemorrhage may occur. Material and Patients: We review the literature and describe a patient in whom a lethal secondary hemorrhage occurred 10 days after laser supraglottic laryngectomy. The case is analyzed and similarities to hemorrhages associated with tonsillectomy and laser surgery of the lingual tonsil are shown. Results and Conclusions: The risk of very late severe secondary hemorrhage after laryngeal laser surgery is considered to be very seldom and comparable with that after tonsillectomy. Due to the increase in laser application in the treatment of laryngeal carcinoma, secondary hemorrhage may be encountered. Consequences for preoperative information and postoperative control of the patients have to be discussed.
Accuracy of Histological Examination following Endoscopic CO2 Laser-Assisted Laryngectomy
Authors: Remacle M. , Delos M. , Lawson G. , Jamart J.
Published: April 2003

We reviewed 242 cordectomy or supraglottic laryngectomy cases operated since 1989. The vocal fold epithelium removed during subepithelial cordectomy with diagnostic intent or biopsies of the operative site after tumor resection underwent frozen section examination. However, the surgical specimen never underwent frozen section analysis. Conventionally, the histopathologist examined the margin area free of laser coagulation. Using the Acuspot micromanipulator alone, coagulation depth was less than or equal to 100 µm; with the Acublade, it was less then 20 µm. Of 181 frozen sections, 154 (85.1%) had negative margins, 23 (12.7%) had positive margins and 1 (0.6%) had moderate dysplasia of the section margin. Reading was inconclusive in 2 cases (1.1%) and impossible in 1 (0.6%). The second examination of the margins during examination of the surgical specimen did not reveal false-positive or false-negative results. Of the 23 patients with positive resection margins at frozen section analysis, 8 (34.8%) underwent immediate and more extensive cordectomy. Frozen section analysis is reliable and cost-effective in oncology for endoscopic partial laryngectomy.
Oxaliplatin–5-Fluorouracil and Ionizing Radiation
Authors: Magné Nicolas , Fischel Jean Louis , Formento Patricia , Etienne Marie-Christine , Dubreuil Alain , Marcié Serge , Lagrange Jean-Léon , Milano Gérard
Published: April 2003

Objectives and Methods: The association oxaliplatin (OXA)–5-fluorouracil/folinic acid (FUFA) is currently a standard first-line treatment for advanced colorectal cancer. The main objective of this experimental study was to examine the cytotoxic effects resulting from the addition of ionizing radiation (Rγ) to the combination OXA-FUFA on 2 human colon cancer cell lines (SW403, p53 wild type and WiDr, p53 mutated). A clinically relevant drug sequence was used consisting in OXA during 2 h followed by FUFA over 24 h. The impact of the position of radiation (1 and 4 Gy) was tested: radiation 2 h before drug application, in the middle of the drug application or 24 h after the drug application. Results: Both cell lines exhibited similar dose response curves to Rγ alone, WiDr being more radio-sensitive than SW403 (IC50: 4.8 Gy and 7 Gy, respectively). The effects of Rγ-drug combinations were assessed using a conventional isobolographic method and by computing a potentiation factor (F) defined as the ratio of IC50 drug combinations/IC50 drug combinations combined with Rγ. The results from both calculation methods concurred: the combination of OXA-FUFA with Rγ led to additive-antagonistic effects for the p53 mutated cell line (WiDr), whatever the sequence. In contrast, for the p53 wild type cell line (SW403), additive-synergistic effects were observed with, in this case, an optimal position for Rγ occurring when applied before or at mid-drug application. Conclusions: These results could be taken into consideration for an optimal design of clinical protocols associating Rγ and OXA-FUFA.
The Importance of Paternal Family History in Hereditary Breast Cancer Is Underappreciated by Health Care Professionals
Authors: Yong May Chin , Zhou Xuelian Jamie , Lee Soo Chin
Published: April 2003

Objectives: Cancer genetics clinics have been established in many major oncology centers worldwide in recent years. For such specialized clinics to fulfill their function, primary care physicians need to identify high-risk patients for referral. Methods: We conducted a survey to evaluate the level of awareness of breast cancer risk factors and hereditary breast cancer among health care providers and patients. Results: 284 health care professionals, 221 medical students, 104 breast cancer patients and 177 cancer-free women participated in the study. Less than half of the patients with breast cancer were aware of their risk for another breast cancer or of the increased breast cancer risk of their sisters and daughters. Less than one quarter of the health care professionals and medical students knew the importance of paternal family history in the evaluation for hereditary breast cancer. Only about half of the health care professionals and medical students and less than one third of the breast cancer patients and cancer-free women knew about genetic testing and prophylactic mastectomy as options for women at risk for hereditary breast cancer. Conclusions: Health care providers and medical students lack basic genetic knowledge and are not aware of emerging diagnostic and preventive options for hereditary breast cancer. Inclusion of cancer genetics in the continuing medical education of health care providers is important to promote such awareness.