bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of mycotoxin profiles among cereal samples from eastern Canada
Authors: Campbell Harold , Choo Thin Meiw , Vigier Bernard , Underhill Lynne
Published: July 2002

The relative susceptibilities of major cereal species to mycotoxin contamination have rarely been studied in eastern Canada or elsewhere. The concentration of 13 mycotoxins in 673 corn (Zea mays L.), 99 wheat (Triticum aestivum L.), 116 barley (Hordeum vulgare L.), and 73 oat (Avena sativa L.) samples collected from eastern Canada from 1991 to 1998 crops were compared. Deoxynivalenol (DON) was found to be the most common mycotoxin in all four species. DON contamination was more frequent but less severe in corn than in wheat and barley, and it was least frequent and least severe in oats. Wheat and barley were equally susceptible to DON contamination. The DON content of 8.9% of the corn, 31.3% of the wheat, 22.4% of the barley, and 1.4% of the oat samples exceeded 1 mg·kg-1, the maximum tolerance level recommended for swine feed. Contamination with zearalenone, T-2, HT-2, diacetoxyscirpenol, ochratoxin A, nivalenol, fumonisins, 3-acetyl DON, or 15-acetyl DON was minor in eastern Canada and varied from species to species. Fusarenon X, 15-monoacetoxyscirpenol, and neosolaniol were not detected. Equally significant, approximately one third of the corn and barley samples were contaminated with two to seven mycotoxins. The presence of two or more mycotoxins could have additive or synergistic effects on the toxicity. Measures to reduce DON contamination are needed for corn, wheat, and barley.Key words: Fusarium, mycotoxins, corn, wheat, barley, oats.
Potential-field modeling of a Proterozoic half-graben near Blackwater Lake, Northwest Territories, Canada, and its implications for the Fort Simpson Magnetic Anomaly
Authors: MacLean B C , Miles W
Published: July 2002

A wedge of Proterozoic strata in the Blackwater Lake area of the Northwest Territories, Canada, is preserved below the sub-Cambrian unconformity in a half-graben associated with a large normal fault. Reflection seismic data define the shape of the wedge, but neither it nor drilling information is adequate for identifying the strata preserved within the half-graben. Although these data permit either Tweed Lake Assemblage (density D = 2730-2780 kg/m3) or MackenzieShaler Assemblage (D = 2580 kg/m3) as the half-graben fill, gravity and (to a lesser extent) magnetic modeling show Tweed Lake Assemblage (~1270 Ma) to be the more likely candidate. Inclusion of any appreciable amount of MackenzieShaler Assemblage in the half-graben produces too low a gravity response and is therefore rejected. The character of the Fort Simpson Magnetic Anomaly (FSA) differs north and south of the Liard Line (~N61°). North of the line and south of Great Bear Lake, the FSA consists of a collection of strong, short-wavelength features superimposed on a weak, long-wavelength magnetic trend. Modeling of one of the higher amplitude, short-wavelength anomalies shows that the sources lies in the upper Proterozoic section immediately below the sub-Cambrian unconformity and therefore is not directly related to a basement terrane boundary. The weaker and longer wavelength component of the FSA may, however, mark a terrane boundary, as is commonly interpreted. Neither the shallow (short-wavelength) component nor the deep (long-wavelength) component has been sampled by drilling north of the Liard Line. Where the FSA crosses the track of the Liard Line, it undergoes a left-lateral offset. South of the Liard Line, the FSA is stronger with more distinct boundaries but lacks the overprint of shorter wavelength features. There, two drill holes have determined the source of the anomaly to be a shallow granite intrusion whose age has been established by UPb analysis as 1845 Ma. The number and magnitude of the differences in the FSA bring into question the validity of carrying the feature northward across the Liard Line.
Seawater composition during deposition of Viséan evaporites in the Moncton Subbasin of New Brunswick as inferred from the fluid inclusion study of halite
Authors: Petrychenko Oleh , Peryt Tadeusz Marek , Roulston Brian
Published: July 2002

The Viséan evaporites of the Windsor Group in the Moncton Subbasin at the western limit of the Maritimes Basin of eastern Canada represent an important stratigraphic sequence to study in determining changes in the chemistry of marine brines. Seventeen samples of halite have been selected for fluid inclusion study. The chemical composition of inclusion brines was examined using the Petrichenko method of glass capillaries with applied ultramicroanalytical techniques. The results of the study indicate that the conditions of evaporite deposition in the Windsor Basin differed from those recorded in other Phanerozoic basins and that the history of the Windsor Basin brines was characterized by changes in the chemical composition of the brines. It was also found that there existed continual unfavourable conditions for the day-and-night zonality in chevron halite crystals and for the origin of relatively large (>50 µm) fluid inclusions and that the gas content was low not only during the deposition but also during the diagenesis of potash deposits. The chemical composition of the Viséan waters of the Moncton Subbasin at the beginning and end of deposition of the Windsor Group evaporite sequence was controlled by the predominating waters of nonmarine origin; during the potash deposition the controlling factor was chloride-type marine waters. In general, the geochemical data support the concept of Carboniferous evaporite basins with NaKMgCaCl-type brines.
An improved genetic linkage map for cowpea (Vigna unguiculataL.) Combining AFLP, RFLP, RAPD, biochemical markers, and biological resistance traits
Authors: Ouédraogo J T , Gowda B S , Jean M , Close T J , Ehlers J D , Hall A E , Gillaspie A G , Roberts P A , Ismail A M , Bruening G , Gepts P , Timko M P , Belzile F J
Published: July 2002

An improved genetic linkage map has been constructed for cowpea (Vigna unguiculata L. Walp.) based on the segregation of various molecular markers and biological resistance traits in a population of 94 recombinant inbred lines (RILs) derived from the cross between 'IT84S-2049' and '524B'. A set of 242 molecular markers, mostly amplified fragment length polymorphism (AFLP), linked to 17 biological resistance traits, resistance genes, and resistance gene analogs (RGAs) were scored for segregation within the parental and recombinant inbred lines. These data were used in conjunction with the 181 random amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP), AFLP, and biochemical markers previously mapped to construct an integrated linkage map for cowpea. The new genetic map of cowpea consists of 11 linkage groups (LGs) spanning a total of 2670 cM, with an average distance of 6.43 cM between markers. Astonishingly, a large, contiguous portion of LG1 that had been undetected in previous mapping work was discovered. This region, spanning about 580 cM, is composed entirely of AFLP markers (54 in total). In addition to the construction of a new map, molecular markers associated with various biological resistance and (or) tolerance traits, resistance genes, and RGAs were also placed on the map, including markers for resistance to Striga gesnerioides races 1 and 3, CPMV, CPSMV, B1CMV, SBMV, Fusarium wilt, and root-knot nematodes. These markers will be useful for the development of tools for marker-assisted selection in cowpea breeding, as well as for subsequent map-based cloning of the various resistance genes.Key words: Cowpea, AFLP, RAPD, resistance gene analogs, genetic linkage map.
Review of resistance factor for steel: data collection
Authors: Schmidt B J , Bartlett F M
Published: July 2002

Changes in the Canadian steel industry warrant a review of the steel resistance factor in CSA Standard S16 (formerly S16.1) "Limit states design of steel structures", originally calibrated in the landmark study by Kennedy and Gad Aly in 1980. This paper summarizes data collected in 1999 and 2000 to determine statistical descriptions of geometric and material properties of rolled W, WWF, and HSS shapes that represent current steel production. Distinct sub-populations have been encountered within a single grade of WWF or HSS material. The geometric properties of rolled W, WWF, and HSS shapes produced to CSA Standard G40.20 have not significantly changed from the values reported by Kennedy and Gad Aly. The statistical parameters for yield strength have improved significantly for HSS shapes, improved slightly for WWF shapes, and worsened slightly for rolled W shapes. Complete summaries of the statistical data are presented. In a companion paper, these data are used to review the resistance factor for steel.Key words: code calibration, geometric properties, reliability, steel, tensile strength, yield strength.
Antiviral activity of ovotransferrin discloses an evolutionary strategy for the defensive activities of lactoferrin
Authors: Giansanti Francesco , Rossi Paola , Massucci Maria Teresa , Botti Dario , Antonini Giovanni , Valenti Piera , Seganti Lucilla
Published: July 2002

Ovotransferrin (formerly conalbumin) is an iron-binding protein present in birds. It belongs to the transferrin family and shows about 50% sequence homology with mammalian serum transferrin and lactoferrin. This protein has been demonstrated to be capable of delivering iron to cells and of inhibiting bacterial multiplication. However, no antiviral activity has been reported for ovotransferrin, although the antiviral activity of human and bovine lactoferrins against several viruses, including human herpes simplex viruses, has been well established. In this report, the antiviral activity of ovotransferrin towards chicken embryo fibroblast infection by Marek's disease virus (MDV), an avian herpesvirus, was clearly demonstrated. Ovotransferrin was more effective than human and bovine lactoferrins in inhibiting MDV infection and no correlation between antiviral efficacy and iron saturation was found. The observations reported here are of interest from an evolutionary point of view since it is likely that the defensive properties of transferrins appeared early in evolution. In birds, the defensive properties of ovotransferrin remained joined to iron transport functions; in mammals, iron transport functions became peculiar to serum transferrin, and the defensive properties towards infections were optimised in lactoferrin.Key words: ovotransferrin, lactoferrin, Marek disease's virus, herpes simplex virus, evolution.
Bearing capacity and settlement of weak fly ash ground improved using lime  fly ash or stone columns
Authors: Zhou Cheng , Yin Jian-Hua , Ming Jing-Ping
Published: July 2002

An experimental study was conducted to evaluate the suitability of lime for the improvement of weak fly ash ground. In the study, a series of unconfined and confined compression tests were carried out on cylindrical samples in the laboratory and on cubic samples in the field, of Lime-FA (lime  fly ash) mixtures with various mixing contents of lime and curing times. Some samples were compressed under a soaking condition with water. A series of full-scale physical tests in the field and small-scale physical tests in the laboratory were conducted on a foundation (or rigid plate) on weak fly ash ground improved using Lime-FA or stone columns, which form a composite foundation. Some physical tests were carried out under a soaking condition. From the test and physical model study, it was found that the Lime-FA mixture has a larger shear strength than that of fly ash when the mixing content of lime is larger than 10%. When the weak fly ash ground is improved with Lime-FA columns, the bearing capacity of the fly ash ground is increased, and the settlement is reduced largely. However, when the ground is soaked under water, the corresponding shear strength of the Lime-FA mixture is decreased, the bearing capacity of the Lime-FA composite ground is decreased, and the settlement is increased. A plate loading test with soaking test on a layer of 1.15 m thick fly ash was also done in the laboratory. The test results show that the top fly ash layer is not suitable as a foundation soil layer and should be replaced with other granular soils, rather than simply compacted to a higher density, due to the negative impact of soaking. Results from the test program are presented and discussed.Key words: fly ash, lime, unconfined compressive strength, shear strength, bearing capacity, settlement, soaking.
Methanogenic potential of tailings samples from oil sands extraction plants
Authors: Fedorak Phillip M , Coy Debora L , Salloum Myrna J , Dudas Marvin J
Published: July 2002

Approximately 20% of Canada's oil supply now comes from the extraction of bitumen from the oil sands deposits in northeastern Alberta. The oil sands are strip-mined, and the bitumen is typically separated from sand and clays by an alkaline hot water extraction process. The rapidly expanding oil sands industry has millions of cubic metres of tailings for disposal and large areas of land to reclaim. There are estimates that the consolidation of the mature fine tails (MFT) in the settling ponds will take about 150 years. Some of the settling ponds are now evolving microbially produced methane, a greenhouse gas. To hasten consolidation, gypsum (CaSO4·2H2O) is added to MFT, yielding materials called consolidated or composite tailings (CT). Sulfate from the gypsum has the potential to stimulate sulfate-reducing bacteria (SRB) to out-compete methanogens, thereby stopping methanogenesis. This investigation examined three MFT and four CT samples from three oil sands extractions companies. Each was found to contain methanogens and SRB. Serum bottle microcosm studies showed sulfate in the CT samples stopped methane production. However, if the microcosms were amended with readily utilizable electron donors, the sulfate was consumed, and when it reached approximately 20 mg/L, methane production began. Some unamended microcosms were incubated for 372 days, with no methane production detected. This work showed that each MFT and CT sample has the potential to become methanogenic, but in the absence of exogenous electron donors, the added sulfate can inhibit methanogenesis for a long time.Key words: consolidated tailings, composite tailings, methanogens, oil sands, sulfate-reducing bacteria.
RELATING TWO-DIMENSIONAL RECONFIGURABLE MESHES WITH OPTICALLY PIPELINED BUSES
Authors: BOURGEOIS ANU G. , TRAHAN JERRY L.
Published: July 2002

Recently, researchers have proposed many models using reconfigurable optically pipelined buses. We present simulations for a number of these models and establish that they possess the same complexity, so that any of these models can simulate a step of one of the other models in constant time with a polynomial increase in size. Specifically, we determine the complexity of three optical models (the PR-Mesh, APPBS, and AROB) to be the same as the well known LR-Mesh and the CF-LR-Mesh.
UNARY LANGUAGE OPERATIONS, STATE COMPLEXITY AND JACOBSTHAL'S FUNCTION
Authors: PIGHIZZINI GIOVANNI , SHALLIT JEFFREY
Published: July 2002

In this paper we give the cost, in terms of states, of some basic operations (union, intersection, concatenation, and Kleene star) on regular languages in the unary case (where the alphabet contains only one symbol). These costs are given by explicitly determining the number of states in the noncyclic and cyclic parts of the resulting automata. Furthermore, we prove that our bounds are optimal. We also present an interesting connection to Jacobsthal's function from number theory.
THREE TOPICS ON PERIODIC ORBIT THEORY: A REVIEW
Authors: HURT NORMAN E.
Published: July 2002

In this paper three topics from periodic orbit theory are reviewed: the semiclassical eigenfunction hypothesis, Bowen's equidistribution theorem, and level attraction in Artin's billiards system. The common thread in each of these subjects is the Selberg trace formula and its application to periodic orbit theory á la Gutzwiller. The formal similarity between the Snirelman-Zelditch result and the semiclassical work of Helffer et al. is noted in the Appendix.
A RIGOROUS RENORMALIZATION GROUP METHOD FOR INTERFACES IN RANDOM MEDIA
Authors: BOVIER ANTON , KÜLSKE CHRISTOF
Published: July 2002

We prove the existence Gibbs states describing rigid interfaces in a disordered solid-on-solid (SOS) for low temperatures and for weak disorder in dimension D ≥ 4. This extends earlier results for hierarchical models to the more realistic models and proves a long-standing conjecture. The proof is based on the renormalization group method of Bricmont and Kupiainen originally developed for the analysis of low-temperature phases of the random field Ising model. In a broader context, we generalize this method to a class of systems with non-compact single-site state space.
BAKERS AND CATS: A REVIEW OF SIMPLE SYSTEMS IN QUANTUM CHAOLOGY
Authors: HURT NORMAN E.
Published: July 2002

Two simple systems, which have been studied recently in the context of quantum chaology, are reviewed in this paper: the baker’s map and the cat maps. Each system is reviewed in both its classical mechanical form and its quantum mechanical form. The algebraic formulation of the classical cat maps is surveyed. Recent results for the baker’s map and the cat maps regarding Gutzwiller’s trace formula, eigenvalue statistics, eigenfunction scarring, semiclassical approximations, log time and zeta function are presented.
NONCOMMUTATIVE GEOMETRY OF TILINGS AND GAP LABELLING
Authors: KELLENDONK JOHANNES
Published: July 2002

To a given tiling a noncommutative space and the corresponding C*-algebra are constructed. This includes the definition of a topology on the groupoid induced by translations of the tiling. The algebra is also the algebra of observables for discrete models of one or many particle systems on the tiling or its periodic identification. Its scaled ordered K0-group furnishes the gap labelling of Schrödinger operators. The group is computed for one-dimensional tilings and Cartesian products thereof. Its image under a state is investigated for tilings which are invariant under a substitution. The part of this image which is given by an invariant measure on the hull of the tiling is determined. The results from the Cartesian products of one-dimensional tilings point out that the gap labelling by means of the values of the integrated density of states is already fully determined by this measure.
3D SINGLETONS AND THEIR BOUNDARY 2D CONFORMAL FIELD THEORY
Authors: MICHÉA SÉBASTIEN
Published: July 2002

This paper is a continuation of recent work of Flato and Frønsdal on singletons in 1+2 anti De Sitter universe and their link with 2D conformal field theories on the boundary. More specifically we show that in this framework we can construct a 3D-singleton model in the bulk, the limit of which on the boundary of De Sitter space is a Gupta–Bleuler triplet for two commuting copies of the Witt algebra. We also generalize this result to the case of WZNW models.
KERNEL-KOHONEN NETWORKS
Authors: ANDRÁS PÉTER
Published: July 2002

We investigate the combination of the Kohonen networks with the kernel methods in the context of classification. We use the idea of kernel functions to handle products of vectors of arbitrary dimension. We indicate how to build Kohonen networks with robust classification performance by transformation of the original data vectors into a possibly infinite dimensional space. The resulting Kohonen networks preserve a non-Euclidean neighborhood structure of the input space that fits the properties of the data. We show how to optimize the transformation of the data vectors in order to obtain higher classification performance. We compare the kernel-Kohonen networks with the regular Kohonen networks in the context of a classification task.
C*-BUNDLES ASSOCIATED WITH GENERALIZED BRATTELI DIAGRAMS
Authors: O'UCHI MOTO
Published: July 2002

We study the inductive limit C*-algebras associated with generalized Bratteli diagrams. For this purpose we construct sequences of locally trivial C*-bundles associated with their diagrams and study the inclusions of C*-bundles. We give a complete condition to ensure locally trivial inclusions. Then we study generalized Bratteli diagrams arising from sequences of covering maps. We show that their inductive limit C*-algebras come from lower semi-continuous cross sections of C*-bundles. Using this, we prove that they are simple if the sequences of covering maps are minimal.
AUTOMATIC LOOP TRANSFORMATIONS AND PARALLELIZATION FOR JAVA
Authors: ARTIGAS PEDRO V. , GUPTA MANISH , MIKIFF SAMUEL P. , MOREIRA JOSÉ E.
Published: July 2002

This paper describes a prototype Java compiler that achieves performance levels approaching those of current state-of-the-art Fortran compilers on numerical codes. We present a new transformation called alias versioning that takes advantage of the simplicity of pointers in Java. This transformation, combined with other techniques that we have developed, enables the compiler to perform high order loop transformations and parallelization completely automatically. We believe that our compiler is the first to have such capabilities of optimizing numerical Java codes. By exploiting synergies between our compiler and the Array package for Java, we achieve between 80 and 100% of the performance of highly optimized Fortran code in a variety of benchmarks. Furthermore, automatic parallelization achieves speedups of up to 3.8 on four processors. Our compiler technology makes Java a serious contender for implementing numerical applications.
FOOTPRINTS OF A BROAD σ(600) IN WEAK-INTERACTION PROCESSES
Authors: POLOSA A. D. , TÖRNQVIST N. A. , SCADRON M. D. , ELIAS V.
Published: July 2002

We explore how chiral-symmetry constraints on weak-interaction matrix elements point toward the existence of an intermediate-state σ in several different weak-interaction processes. Particular attention is directed toward recent evidence for a σ within three-body nonleptonic weak decays.
THREE-DIMENSIONAL GONIHEDRIC SPIN SYSTEM
Authors: KOUTSOUMBAS G. , SAVVIDY G. K.
Published: July 2002

We perform Monte–Carlo simulations of a three-dimensional spin system with a Hamiltonian which contains only four-spin interaction term. This system describes random surfaces with extrinsic curvature – gonihedric action. We study the anisotropic model when the coupling constants βS for the space-like plaquettes and βT for the transverse-like plaquettes are different. In the two limits βS = 0 and βT = 0 the system has been solved exactly and the main interest is to see what happens when we move away from these points towards the isotropic point, where we recover the original model. We find that the phase transition is of first order for βT = βS ≈ 0.25, while away from this point it becomes weaker and eventually turns to a crossover. The conclusion which can be drawn from this result is that the exact solution at the point βS = 0 in terms of 2D-Ising model should be considered as a good zero-order approximation in the description of the system also at the isotropic point βS = βT and clearly confirms the earlier findings that at the isotropic point the original model shows a first-order phase transition.
RENORMALIZATION GROUP FLOWS IN THE DEFORMED ADS/CFT CORRESPONDENCE
Authors: EVANS NICK
Published: July 2002

In the AdS/CFT correspondence motion in the radial direction of the AdS space is identified with renormalization group flow in the field theory. For the N=4 Yang-Mills theory this motion is trivial. More interesting examples of renormalization group flow occur when the N=4 theory is deformed. Aspects of the flows are discussed for the N=4 theory on its moduli space, and deformed to N=2 in the infra-red within the context of 5d SUGRA. 10d lifts and brane probing are crucial tools for linking the spacetime backgrounds to the dual field theory.
Scale Invariance and the Ads/CFT Correspondence
Authors: AWAD ADEL M. , JOHNSON CLIFFORD V.
Published: July 2002

Using the AdS/CFT correspondence, we show that the Anti-de Sitter (AdS) rotating (Kerr) black holes in five and seven dimensions provide us with examples of non-trivial field theories which are scale, but not conformally invariant. This is demonstrated by our computation of the actions and the stress-energy tensors of the four and six dimensional field theories residing on the boundary of the boundary of these Kerr-AdS black holes spacetimes.
THE CLEO III DETECTOR
Authors:   Representing the CLEO Collaboration., PEDLAR TODD K.
Published: July 2002

After a long shutdown in 1999, the CLEO Collaboration at Cornell University's Wilson Laboratory began taking data in 2000 using its third generation detector, CLEO III. Several improvements to the detector system have been made in order to take advantage of the possibility of unprecedented luminosities of well over 2×1033 expected from CESR, and to explore new territory in the physics of B mesons. These improvements include a new drift chamber, a four layer silicon vertex detector and a RICH detector. These features will be described, and its performance will be presented.
CMS SILICON STRIP DETECTORS
Authors:   For the CMS Tracker Collaboration., MY SALVATORE
Published: July 2002

Robust tracking is an essential tool to address the full range of physics which can be accessed at LHC. The CMS Collaboration has chosen the detector technology for the Si-licon Strip tracking system. Over the last few years considerable progress has been made in the understanding of the operation of silicon strip detector in the harsh environment of the LHC. An overview of recent results is given with particular emphasis on resistivity and crystal orientation of the substrate, strip capacitance and breakdown voltage.
GAIN AND THRESHOLD CONTROL OF SCINTILLATION COUNTERS IN THE CDF MUON UPGRADE FOR RUN II
Authors:   For the AMA Collaboration., BROMBERG C.
Published: July 2002

We describe a system for control and readout of scintillation conters, in the CDF Muon Upgrade for Run II, that use a miniature (low again) photomultiplier tube coupled to a high voltage generator. In the system, we mount on each counter an electronics module that amplifies counter signals, sets tube gain, discriminates signals, sets tube gain, discrimates signals with an adjustable threshold, and drives a light source. A 48 channel control unit distributes power, gain and thereshold settings, light source triggers, and receives counter signals on tristed pair cables, stretches and transmits the signals to remote time digitizers. Also, we describe a scintillation counter design that integrates the scintillator, filesn, and electronics modules into a sturdy packega.
FAST TRACK TRIGGERING FOR THE CDF II DETECTOR
Authors:   On behalf of the CDF Collaboration., BLOOM KENNETH
Published: July 2002

In the upcoming Fermilab Tevatron collider run, [Formula: see text] collisions will occur at 132 ns intervals, and the CDF II trigger system requires that information about drift chamber tracks be provided within 2.2 μs of every collision, so that tracking information can be used in conjunction with data from other detector components to trigger on physics objects with little background. We have developed a fast online track processor for locating high-momentum tracks in the chamber. The design is highly parallel, and is implemented in programmable logic devices. We describe the design of the system and performance tests.
FIRST RESULTS FROM THE PHOBOS EXPERIMENT AT THE RHIC COLLIDER
Authors:   For the PHOBOS Collaboration, KATZY JUDITH , Back B. B. , Baker M. D. , Barton D. S. , Betts R. R. , Bindel R. , Budzanowski A. , Busza W. , Carroll A. , Decowski M. P. , Garcia E. , George N. , Gulbrandsen K. , Gushue S. , Halliwell C. , Heintzelman G. A. , Henderson C. , Holyński R. , Hofman D. , Holzman B. , Johnson E. , Kane J. , Katzy J. , Kulinich P. , Kucewicz W. , Lin W. T. , McLeod D. , Manly S. , Michalowski J. , Mignerey A. , Muelmenstaedt J. , Nouicer R. , Olszewski A. , Pak R. , Park I. C. , Pernegger H. , Reed C. , Remsberg L. P. , Reuter M. , Roland C. , Roland G. , Rosenberg L. , Sarin P. , Sawicki P. , Skulski W. , Steadman S. G. , Stephans G. S. F. , Steinberg P. , Stodulski M. , Sukhanov A. , Tang J.-L. , Teng R. , Trzupek A. , Vale C. , van Nieuwenhuizen G. J. , Verdier R. , Wadsworth B. , Wolfs F. L. H. , Wosiek B. , Woźniak K. , Wuosmaa A. H. , Wysłouch B.
Published: July 2002

PHOBOS is one of the four experiments at the Relativistic Heavy Ion Collider that started colliding gold nuclei at a center of mass energy of √sNN = 56 and 130 GeV per pair of colliding nucleons in June 2000. The pseudorapidity density of primary charged particles in central collisions has been measured near mid-rapidity.
SYMMETRIES FOR STRONGLY INTERACTING HEAVY PARTICLES
Authors: WISE MARK B.
Published: July 2002

Strongly interacting theories with heavy particles can exhibit symmetries that are not manifest in the Lagrangian. Two examples are discussed. The first is Wigner spin–isospin symmetry for the strong interactions of nuclei. The second is heavy quark symmetry for the strong interactions of bottom and charm quarks.
SPACE TIME FOAM
Authors: GARATTINI REMO
Published: July 2002

In the context of a model of space-time foam, made by N wormholes we discuss the possibility of having a foam formed by different configurations. An equivalence between Schwarzschild and Schwarzschild-Anti-de Sitter wormholes in terms of Casimir energy is shown. An argument to discriminate which configuration could represent a foamy vacuum coming from Schwarzschild black hole transition frequencies is used. The case of a positive cosmological constant is also discussed. Finally, a discussion involving charged wormholes leads to the conclusion that they cannot be used to represent a ground state of the foamy type.
CASIMIR EFFECTS IN RENORMALIZABLE QUANTUM FIELD THEORIES
Authors: GRAHAM NOAH , JAFFE ROBERT L. , WEIGEL HERBERT
Published: July 2002

We present a framework for the study of one–loop quantum corrections to extended field configurations in renormalizable quantum field theories. We work in the continuum, transforming the standard Casimir sum over modes into a sum over bound states and an integral over scattering states weighted by the density of states. We express the density of states in terms of phase shifts, allowing us to extract divergences by identifying Born approximations to the phase shifts with low order Feynman diagrams. Once isolated in Feynman diagrams, the divergences are canceled against standard counterterms. Thus regulated, the Casimir sum is highly convergent and amenable to numerical computation. Our methods have numerous applications to the theory of solitons, membranes, and quantum field theories in strong external fields or subject to boundary conditions.
THEORETICAL STUDY ON THE ORIGIN OF THE PSEUDOGAP
Authors: KAMIMURA HIROSHI , HAMADA TSUYOSHI , USHIO HIDEKI
Published: July 2002

In this paper we will show that the microscopic origins of the "high-energy" pseudogap and of the peculiar hole-concentration dependence of the electronic entropy correspond to a phase change between a phase consisting of the small Fermi surfaces and a phase with a large Fermi surface. In real materials, however, the phase change is not sharp due to the finite spin-correlation length for local antiferromagnetic ordering. Further we will show that the dopant hole carriers in cuprates behave like heavy fermions.
QUASI-LONG RANGE ORDER IN GLASS STATES OF IMPURE LIQUID CRYSTALS, MAGNETS, AND SUPERCONDUCTORS
Authors: FELDMAN D. E.
Published: July 2002

We consider glass states of several disordered systems: vortices in impure superconductors, amorphous magnets, and nematic liquid crystals in random porous media. All these systems can be described by the random-field or random-anisotropy O(N) model. Even arbitrarily weak disorder destroys long range order in the O(N) model. We demonstrate that at weak disorder and low temperatures quasi-long range order emerges. In quasi-long-range-ordered phases the correlation length is infinite and correlation functions obey power dependencies on the distance. In pure systems quasi-long range order is possible only in the lower critical dimension and only in the case of Abelian symmetry. In the presence of disorder this type of ordering turns out to be more common. It exists in a range of dimensions and is not prohibited by non-Abelian symmetries.
EXCITONS ON A 1D PERIODIC CONJUGATED POLYMER CHAIN: TWO ELECTRONIC STRUCTURES OF POLYDIACETYLENE CHAINS
Authors: LAPERSONNE-MEYER C.
Published: July 2002

Crystalline polydiacetylenes (PDA) provide a model system for conjugated polymers. Monomer crystals where the polymer content is very low give access to the electronic structure of a 1D straight periodic isolated chain. PDA are known to exist as crystals in two electronic structures, the so-called 'blue' and 'red' phases. In 3BCMU crystals, blue and red chains coexist, so that the electronic properties of both types of chains in the same environment can be compared. In both cases fluorescence originates from the 1 B u exciton state. The blue exciton lifetime is 140 fs, its fluorescence quantum yield is small (10-4) and the relaxation is dominated by non radiative processes via low lying A g states as in polyenes. On the contrary, for red chains the exciton state is highly fluorescent (quantum yield 0.30), its lifetime is 52 ps at 15 K, implying a short radiative lifetime <100 ps. Recent results on the temperature dependence of lifetime and fluorescence yield imply the presence of states, thermally accessible from the exciton state, but non radiant to the ground state. This is consistent with a non planar conformation of the chain.
OPTIMIZING THE SPEED OF A JOSEPHSON JUNCTION WITH DYNAMICAL MEAN FIELD THEORY
Authors: FREERICKS J. K. , NIKOLIĆ B. K. , MILLER P.
Published: July 2002

We review the application of dynamical mean-field theory to Josephson junctions and study how to maximize the characteristic voltage I c R n which determines the width of a rapid single flux quantum pulse, and thereby the operating speed in digital electronics. We study a wide class of junctions ranging from SNS, SCmS (where Cm stands for correlated metal), SINIS (where the insulating layer is formed from a screened dipole layer), and SNSNS structures. Our review is focused on a survey of the physical results; the formalism has been developed elsewhere.
EIGEN-FUNCTIONAL METHOD AND EIKONAL-TYPE EQUATIONS IN ONE-DIMENSIONAL STRONGLY CORRELATED ELECTRON SYSTEMS
Authors: LIU YU-LIANG
Published: July 2002

Using eigen-functional method, we study one-dimensional strongly correlated electron systems with large momentum (2k F and/or 4k F ) transfer term(s), and demonstrate that this kind of problems ends in to solve the Eikonal-type equations, and these equations are universal, and independent of whether or not the system is integrable. In contrast to usual perturbation theory, this method is valid not only for weak electron interaction, but also for strong electron interaction. Comparing with exact solution of some integrable models, it can give correct results in linearization approximation. This method can also be used to study electron-phonon interaction systems, and two coupled spin chain (or quantum wire) systems.
FULL-COLOR PHOTO- AND ELECTRO-LUMINESCENCE FROM HYDROGENATED AMORPHOUS SILICON CARBIDE FILMS PREPARED BY USING ORGANIC SOURCE
Authors: XU JUN , MA TIANFU , HUANG XIAOHUI , WANG LI , LI WEI , CHEN KUNJI
Published: July 2002

A series of hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films (0 < x ≤ 1) were grown by using an organic source, xylene (C8H10), instead of methane (CH4) in a conventional plasma enhanced chemical vapor deposition system. The optical band gap of these samples was altered over a wide range by changing the gas ratio of C8H10 to SiH4, the maximum value can be reached as high as 3.6eV. Photoluminescence (PL) measurements were carried out at room temperature by using a Xe lamp as an excitation light. It was found that the PL peak is blue shifted with increasing optical band gap. The xylene-based a-SiC:H electro-luminescence (EL) device structure was also fabricated and room temperature EL behavior was investigated. It was found that the EL peak depended on the band gap of a-C:H films and a stable emission can be obtained by using the suitable structure parameters.
HIGH-TEMPERATURE SUPERCONDUCTIVITY IN INTERCALATED MOLECULAR C60/CHX3(X=Cl, Br, I)
Authors: BILL A. , WINDIKS R. , DELLEY B. , KRESIN V. Z.
Published: July 2002

Intercalating polyatomic molecules into a superconductor strongly modifies its superconducting properties. A mechanism for a large increase in T c is proposed that explains recent experimental findings on C60/CHX3 (X=Cl, Br, I) . The increase of T c upon intercalation as well as upon Cl→Br substitution is described in terms of the additional contribution to pairing interaction arising from the coupling of holes (or electrons) to the vibrational manifold of the intercalated haloform molecules. We also present first optimization of the crystal structure and calculations of the band structure for neutral C60/CHCl3 .
THE SELF-FORCE OF A CHARGED PARTICLE IN CLASSICAL ELECTRODYNAMICS WITH A CUTOFF
Authors: FRENKEL J. , SANTOS R. B.
Published: July 2002

We discuss, in the context of classical electrodynamics with a Lorentz invariant cutoff at short distances, the self-force acting on a point charged particle. It follows that the electromagnetic mass of the point charge occurs in the equation of motion in a form consistent with special relativity. We find that the exact equation of motion does not exhibit runaway solutions or non-causal behavior, when the cutoff is larger than half of the classical radius of the electron.
Long Josephson Junctions Modulated by Defects and Superconducting Microdomains in YBCO Thin Films
Authors: Crescio E. , Gerbaldo R. , Ghigo G. , Gozzelino L. , Mezzetti E. , Minetti B.
Published: July 2002

The critical current Jc of superconducting films is about two order of magnitude larger than that of single crystals. The dependence of such Jc on field depends on the presence and distribution of defects. We speculate that High Temperature Superconducting (HTS) films can be modeled as an agglomeration of islands coupled via Josephson contacts and then considered as a network of Long Josephson Junctions (LJJ) between superconducting islands. In order to check this hypothesis we further developed a model firstly introduced by Fehrenbacher based on the modulation of critical current densities in LJJ by means of suitable distribution of defects. The defects act by modulating the coupling energy of the junction. Critical current densities are calculated in the case of periodic and random defect distributions.
Electrorheological Squeeze-Flow Shock Absorber
Authors: Khusid Boris , Acrivos Andreas , Khodorkovsky Yakov , Beltran Michael
Published: July 2002

We developed a squeeze-flow shock absorber and tested it under impact conditions typical of heavy-duty recoil mechanisms. In contrast to common shear-flow shock absorbers, here the volume of fluid driven by the piston does not flow through the regions of high electric field. Experiments on three commercially available "dry" ER fluids showed that only the Bayer fluid was able to exhibit electric-field-induced stresses under our test conditions. But the results which were obtained with this fluid illustrate the numerous advantages to be gained by utilizing a squeeze-flow shock absorber in advanced systems subjected to impact disturbances and destructive vibrations.
A New Type of Hydraulic Actuator Using Electrorheological Fluids
Authors: Wendt Eckhard , Büsing Klaus W.
Published: July 2002

Electrorheological Fluids (ERF) are usually used in semi active damping elements, e.g. shock absorbers or engine mounts because of their continuously controllable shear stress. A totally new field of application may be achieved, if an ERF is used as a hydraulic fluid and not only as a control medium. In this case a fundamental need is the capability to produce a volume flow by using normal hydraulic pumps, e.g. gear pumps. The ERF and the hydraulic components both must have a long lifetime without unusual wear. Bayer AG has developed an ERF based on soft crosslinked PU-particles dispersed in silicone oil. These ERF are characterised by a low basic viscosity, a high ER-effect and a moderate conductivity. Compared with previous ERF where hard inorganic particles were used, the new fluid is not abrasive. It is foremostly this characteristic which gives the possibility of using the ERF in hydraulic systems with high shear rates and high shear stresses. The usage of ERF as hydraulic fluid allows the construction of proportional valves without mechanically driven parts. The control of the pressure drop over the valves is realised directly by an electrical signal. It is possible to realise actuators with very fast response times since the reaction time of ERF is within milliseconds. For demonstration purpose Bayer AG has built an actuator which is controlled by an electrorheological valve-block. The calculation of the dimension of this actuator and the valves will be shown and the realised response time will be demonstrated.
Applications of Oscillatory Flow of Magnetic Fluid as Active Damper and Actuator
Authors: Kamiyama Shinichi
Published: July 2002

Study on the control of vibration of a spring-mass system attached to a piston immersed in a magnetic fluid by controlling the applied magnetic field is conducted theoretically and experimentally to develop the magnetic fluid active damper and actuator.
RESISTIVE ANOMALIES AT NEAR 250 K IN Hg-Ca-Cu-O AND Fe-S SYSTEMS
Authors: YOM S. S. , PARK JONG-KU , KIM G. H. , KIM H. S. , LEE J. Y. , CHOI E. S. , PARK Y. W.
Published: July 2002

High pressure synthesized samples of nominal composition of Ca 2-x Hg x CuO y with x=0.10~0.20 under reductive synthesis condition showed stable and reproducible resistivity onset transition at 225~254 K accompanied by rapid drop of thermoelectric power without accompanying magnetic susceptibility transition. Fe 1-x S ( x =0) by mechanical alloying method showed resistivity anomaly and thermal hysteresis at 150~180 K. These resistive anomalies may be phase transition of unknown origin rather than an indication of superconductivity.
HIGH Tc SUPERCONDUCTIVITY: SYMMETRIES AND REFLECTIONS
Authors: ZHANG SHOU-CHENG
Published: July 2002

This is a talk given at the Symposium "Symmetries and Reflections", dedicated to Prof. C. N. Yang's retirement. In this talk, I shall reflect on my personal interaction with Prof. Yang since my graduate career at SUNY Stony Brook, and his profound impact on my understanding of theoretical physics. I shall also review the SO(5) theory of high T c superconductivity and show how my collaboration with Prof. Yang in 1990 lead to the foundation of this idea.
HIGH-TEMPERATURE SUPERCONDUCTIVITY CAUSED BY CIRCULAR POLARIZED ZERO-POINT OSCILLATION
Authors: SUGAHARA MASANORI , BOGOLUBOV NICKOLAI N.
Published: July 2002

A new model is proposed on the recently found non-cuprate high temperature superconductivity in crystal with 2D conduction plane which is composed of the planar connection of many circular localized orbits. Our findings are as follows:

(i) the ground state of the doped 2D particle system in zero point oscillation is similar to the particle state in very strong magnetic field,

(ii) Laughlin state with filling factor ν = 1/2 is the most stable state of the 2D particle system,

(iii) the superposition of many fluctuating Laughlin states in pure crystal gives a coherent state with superfluidity.

(iv) This model gives an estimation of the upper limit of the superconductivity transition temperature: [Formula: see text] for fcc C 60, and [Formula: see text] for Ag β Pb 6 CO 9, which are close to observation.
QUANTUM FLUCTUATION OF TWO-MODE SQUEEZED THERMAL VACUUM STATES AND THE THERMAL WIGNER OPERATOR STUDIED BY VIRTUE OF <η| REPRESENTATION
Authors: FAN HONGYI , WANG HUI
Published: July 2002

Based on the <η| representation in Thermo Field Dynamics3 we introduce the thermal Wigner operator, with which we reach the conclusion that due to the thermal effect the quantum fluctuation of two-mode squeezed vacuum state increases by a factor cosh 2θ, where tanh θ = exp (-ℏω/2kT). We also mathematically analyse the formalism of Thermo Field Dynamics in the context of entanglement theory.
PASSIVATION OF GaSb SINGLE CRYSTAL SURFACES STUDIED BY PHOTOLUMINESCENCE
Authors: DIAZ-REYES J. , CORONA-ORGANICHE E. , HERRERA-PEREZ J. L. , MENDOZA-ALVAREZ J. G.
Published: July 2002

GaSb single crystals are the ideal substrates for the growth of InGaAsSb and AlGaAsSb heterostructures to fabricate optoelectronic devices in the medium infrared. GaSb surfaces are highly reactive to oxidation, the oxides grown on their surface have poor conductivity (~ 10-2 Ω-1 cm -l) and it produces high surface leak currents; so, the search for passivation layers to prevent such leak currents is crucial for the development of reliable and optimized devices. Different approaches to passivation films were developed; mixtures of H 2 O 2 + citric acid and H 2 O 2 + tartaric acid were used for anodic oxidation. Also, SiO 2 films deposited by a sol-gel process were used as passivation layers. In order to test the performance of these layers, the low temperature photoluminescence (PL) spectroscopy was measured in all samples. The PL spectra show a shift of the main emission peak to lower energies and an increase in the PL intensity for a factor of up to 9, indicating that a passivation process is taking place in the GaSb surface. These spectra and the origin of the changes in the PL spectra are discussed.
USE OF IBA TECHNIQUES TO CHARACTERIZE HIGH VELOCITY THERMAL SPRAY COATINGS
Authors: TROMPETTER W. , MARKWITZ A. , HYLAND M.
Published: July 2002

Spray coatings are being used in an increasingly wide range of industries to improve the abrasive, erosive and sliding wear of machine components. Over the past decade industries have moved to the application of supersonic high velocity thermal spray techniques. These coating techniques produce superior coating quality in comparison to other traditional techniques such as plasma spraying. To date the knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. The aim of this research is to improve our understanding of these materials through the use of IBA techniques in conjunction with other materials analysis techniques. Samples were prepared by spraying a widely used commercial NiCr powder onto substrates using a HVAF (high velocity air fuel) thermal spraying technique. Detailed analysis of the composition and structure of the power particles revealed two distinct types of particles. The majority was NiCr particles with a significant minority of particles composing of SiO 2/ CrO 3. When the particles were investigated both as raw powder and in the sprayed coating, it was surprising to find that the composition of the coating meterial remained unchanged during the coating process despite the high velocity application.
APPLICATIONS OF THE HOPFIELD–LITTLE NEURAL NETWORKS
Authors: ANDRECUT MIRCEA
Published: July 2002

We show that the Hopfield–Little neural networks can be successfully used for solving arbitrary set of linear equations by computing the Moore–Penrose generalized inverse of matrices. Also, an application for character recognition is described.
INTRODUCING ALGORITHM DESIGN TECHNIQUES IN UNDERGRADUATE DIGITAL IMAGE PROCESSING COURSES
Authors: SANCHEZ ANGEL , VELEZ JOSE F. , MORENO ANA BELEN , ESTEBAN JOSE L.
Published: July 2002

This paper documents the development and first offering of an undergraduate course in Digital Image Processing at the Rey Juan Carlos University, Madrid (Spain). The paper describes how the appropriate introduction of main Algorithm Design Techniques can successfully assist the students to achieve a comprehensive understanding of image operations and related algorithms. Image processing problems offer a natural way to present real world problems where the students can use their algorithmic knowledge. Furthermore, image processing solutions are needed from a methodological development and require efficient well-designed algorithms. This paper presents an effort in the integration of Algorithm Design Techniques in a Digital Image Processing course with a very practical scope.