bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiac MRI for the Assessment of Myocardial Viability
Authors: Sandstede J. J. W. 
Published: November 2004

AbstractDiagnosis of myocardial viability after infarction focuses on the prediction of functional improvement of dysfunctional myocardium after revascularization therapy. Magnetic resonance imaging (MRI) provides morphological and functional approaches for the assessment of myocardial viability. The morphological approach is based on the detection of the ratio viable/non‐viable cells. The end‐diastolic wall thickness is an indirect parameter of this ratio, because thinned myocardium contains a reduced number of viable cells. This approach is easy to perform and has a high sensitivity, but a low specificity and can only be used 4 months after myocardial infarction due to infarct healing processes. Delayed enhancement allows for direct visualization of necrotic or scarred tissue. By measuring the transmural extent of delayed enhancement, the probability of mechanical improvement can precisely be given. Imaging of microvascular obstruction by first‐pass perfusion or delayed enhancement gives additional information on viability and patient prognosis. Low‐dose dobutamine‐stress as the functional approach has a good sensitivity with a high specificity for the prediction of wall motion improvement and may provide additional information in patients with transmural extent of delayed enhancement between 1 and 75%. In conclusion, cardiac MRI offers several clinically usable approaches for the assessment of myocardial viability and is about to become the method of choice in the near future.
Genetically decreasedCYP2A6and the risk of tobacco dependence: a prospective study of novice smokers
Authors: O’Loughlin J , Paradis G , Kim W , DiFranza J , Meshefedjian G , McMillan-Davey E , Wong S , Hanley J , Tyndale R F 
Published: November 2004

Objective:Case control studies in adults suggest that defective alleles in the gene that codes for the hepatic cytochrome P450 2A6 (CYP2A6) protect against nicotine dependence (ND) and higher levels of cigarette consumption. These two hypotheses were tested in young adolescents.Design:Self reports of tobacco use and ND symptoms were collected every 3–4 months in a prospective study of 1293 grade 7 students from a convenience sample of 10 schools.Subjects:281 smokers with genetic data were analysed; those who were not already tobacco dependent and who had inhaled (n  =  228) were followed 29.9 months on average, until they became dependent or were censored.Main outcome measures:The association between metabolic activity, represented byCYP2A6genotype, and conversion to dependence was analysed using Cox’s proportional hazards model.Results:During follow up 67 subjects (29.4%) became dependent. Relative toCYP2A6*1/*1, having 1–2 copies of the inactiveCYP2A6*2or*4variant was a strong risk factor for developing dependence (hazard ratio 2.8, 95% confidence 1.3 to 6.3). Subjects with 1–2 partially inactiveCYP2A6*9or*12variants were not at increased risk. Mean past-week cigarette consumption at the end of follow up (controlling for age, sex, and number of months since first inhalation) among dependent subjects was 29.1 among normal inactivators, compared to 17.2, and 12.7 among slower (1–2 copies of *9or *12), and slowest (1–2 copies of*2or*4) inactivators, respectively (p  =  0.09).Conclusion:Adolescents with 1–2 copies ofCYP2A6*2or *4are at substantially increased risk of becoming dependent but smoke less once dependent. Genetic risk for ND may need to be considered in the conceptualisation of tobacco control programmes for adolescents.
Industry sponsored youth smoking prevention programme in Malaysia: a case study in duplicity
Authors: Assunta M , Chapman S 
Published: November 2004

Objective:To review tobacco company strategies of using youth smoking prevention programmes to counteract the Malaysian government’s tobacco control legislation and efforts in conducting research on youth to market to them.Methods:Systematic keyword and opportunistic website searches of formerly private internal industry documents. Search terms included Malay, cmtm, jaycees, YAS, and direct marketing; 195 relevant documents were identified for this paper.Results:Industry internal documents reveal that youth anti-smoking programmes were launched to offset the government’s tobacco control legislation. The programme was seen as a strategy to lobby key politicians and bureaucrats for support in preventing the passage of legislation. However, the industry continued to conduct research on youth, targeted them in marketing, and considered the teenage market vital for its survival. Promotional activities targeting youth were also carried out such as sports, notably football and motor racing, and entertainment events and cash prizes. Small, affordable packs of cigarettes were crucial to reach new smokers.Conclusion:The tobacco industry in Malaysia engaged in duplicitous conduct in regard to youth. By buying into the youth smoking issue it sought to move higher on the moral playing field and strengthen its relationship with government, while at the same time continuing to market to youth. There is no evidence that industry youth smoking prevention programmes were effective in reducing smoking; however, they were effective in diluting the government’s tobacco control legislation.
A UNIFICATION ALGORITHM FOR THE λΠ-CALCULUS
Authors: PYM DAVID 
Published: November 2004

We present a unification algorithm for the λΠ-calculus, the lambda calculus with first-order dependent function types. Our algorithm is an extension of Huet’s algorithm for the simply-typed lambda calculus to first-order dependent function types. In the simply-typed lambda calculus one attempts to unify a pair of terms of the same type; in the λΠ-calculus types are dependent on terms so one must unify not only terms, but their types as well. Accordingly, we identify a suitable notion of similarity of types, and only attempt to unify a pair of terms of similar type: if the types are not similar then they are not unifiable. Since Huet’s algorithm does not enumerate all of the unifiers of a given pair of terms, the strategy of first unifying pairs of types — by identifying suitable pairs of subterms for unification — is not complete. Accordingly, we must unify terms and their types simultaneously, taking care to maintain all of the conditions that are necessary to ensure the well-formedness of the resulting calculated substitution. Our notion of substitution is an algebraic one: substitutions are morphisms of λΠ-contexts. However, in order to define our algorithm we must work with psubstitutions and pcontexts — substitutions and contexts, respectively, in which variables are replaced by terms of similar, not β(η)-equal, type.
DATA SMOOTHING TECHNIQUES APPLIED TO PROTON MICROPROBE SCANS OF TELEOST HARD PARTS
Authors: WEST I.F. , COOTE G.E. , GAULDIE R.W. 
Published: November 2004

We use a proton microprobe to examine the distribution of elements in otoliths and scales of teleost (bony) fish. The elements of principal interest are calcium and strontium in otoliths and calcium and fluorine in scales. Changes in the distribution of these elements across hard structures may allow inferences about the life histories of fish. Otoliths and scales of interest are up to a centimeter in linear dimension and to reveal the structures of interest up to 200 sampling points are required in each dimension. The time needed to accumulate high X-ray counts at each sampling point can be large, particularly for strontium. To reduce microprobe usage we use data smoothing techniques to reveal changing patterns with modest X-ray count accumulations at individual data points. In this paper we review performance for revealing pattern at modest levels of X-ray count accumulations of a selection of digital filters (moving average smoothers), running median filters, robust locally weighted regression filters and adaptive spline filters.
High Spatial Resolution Using the Conventional Particle-Mesh Technique
Authors: BIEN R. , FUCHS B. , WIELEN R. 
Published: November 2004

The use of the particle-mesh technique has a long and successful history in the field of computer simulations of collisionless gravitational systems, such as galaxies. Since the method allows the treatment of large numbers of particles statistical noise has only a small effect. On the other hand, severe problems arise when high density peaks must be resolved. In order to master these difficulties we have worked out a procedure which is an extension of the standard particle-mesh code in three-dimensional Cartesian coordinates. The basic idea is simply to introduce additional grids and sub-grids in regions with steep density gradients such that the system of grids is re-arranged at each integration step. In this way we are able to simulate single and interacting galaxies. In the present paper a short review of some frequently used methods of galaxy simulations is given and our own method is outlined.
The Phases of Cyclohexane Predicted by MD Simulation
Authors: TREW A.S. , WILDING  , PAWLEY G.S. 
Published: November 2004

Phase changes in cyclohexane have been studied by MD simulation on the AMT DAP computer, using a zero-pressure technique to simulate clusters of 512 molecules. This work builds upon a previous study [1] in which we performed MD calculations on a smaller sample and found a phase intermediate between the experimentally determined low temperature crystalline structure (C2/c) and the high temperature plastic one (Fm3m). This new phase had not been observed experimentally in the bulk at ambient pressure [2]. We determined the intermediate structure to be rhombohedral with a space group of [Formula: see text]. A subsequent neutron diffraction study of cyclohexane at high pressures (< 5) kbar has permitted the identification of two orthorhombic phases [3] which occur for deuterated cyclohexane. In addition, for very small sample sizes another, as yet unidentified, phase has been observed at ambient pressure [4]: clear evidence that there are differences between the crystal structure in the bulk and in small clusters. We therefore decided to extend our earlier work in order to investigate the behaviour of the phase as a function of sample size. Using a larger sample we find behaviour much closer to that seen in the bulk material. The rhombohedral structure is still observed but over a very much reduced temperature range and the transition temperatures are closer to those seen experimentally. Although -we cannot identify the structure observed by Bosio and Dumas [4] with that simulated it is clear that there is an obvious parallel with the behaviour of the model. A further study of this system is underway.
SEMICLASSICAL CHAOS IN AN x4 ANHARMONIC OSCILLATOR
Authors: ANDERSON J.T. 
Published: November 2004

The Zaslavskii criterion for quantum chaos is applied to a quartic anharmonic oscillator with dissipation and an external force term in the semiclassical approximation. The semiclassical equilibrium states and integral invariants are related to quantum states in terms of the ratio of h to the semiclassical action. Semiclassical chaos is found to occur with the destruction of integral invariants and equilibrium states but the quantum states are not destroyed.
EXPERIMENTAL DETERMINATION OF THE QUARK MIXING ANGLES
Authors: CASTRO G. LÓPEZ 
Published: November 2004

We review the current status of the determination of the quark mixing angles |Vqq′|, where q=u, c; q′=d, s, b. We consider essentially exclusive decay processes, taking into account the main sources of uncertainties, the available calculations of flavor symmetry breaking for hadronic matrix elements and the possibilities of improvement offered by new experimental results. In some cases we provide full expressions for |Vqq′| in terms of measurable decay properties, which can be useful for new experimental data. Finally, we discuss briefly the effects on the unitarity tests of the Cabibbo-Kobayashi-Maskawa matrix when we consider recent corrections to the determination of |Vud|.
NONPERTURBATIVE APPROACHES TO DETERMINING THE BEHAVIOR OF THE GLUON PROPAGATOR AND QUARK PROPAGATOR IN QUANTUM CHROMODYNAMICS BY SCHWINGER-DYSON EQUATIONS
Authors: HÄDICKE A. 
Published: November 2004

The attempts to describe the behavior of the gluon propagator and quark propagator by using truncated Schwinger-Dyson equations and Slavnov-Taylor identities are reviewed. Special attention is paid to the problem of infrared behavior of Green’s functions. The most important attempts to calculate the gluon propagator using the axial as well as the covariant gauge are critically discussed. Furthermore, an approach concerning the gluon propagator is presented, with the background-field method as its basis. All the calculations confirm more or less the existence of an infrared singularity in the gluon propagator of the form q−4 in momentum space. The calculations to determine the behavior of the dynamical mass function of quarks, where the results concerning the gluon propagator are taken into account, show that chiral symmetry is dynamically broken. Furthermore, it turns out that there is no polelike singularity in the quark propagator. These results agree with the expectations from the confinement philosophy.
THERMAL DEPINNING AND “MELTING” OF THE FLUX-LINE LATTICE IN HIGH-Tc SUPERCONDUCTORS
Authors: BRANDT ERNST HELMUT 
Published: November 2004

In high-Tc superconductors (HTSC) the thermal fluctuation of the vortex lattice (VL) may become large since the vortex lattice is soft due to the strong overlap of the vortex fields and since the temperature T can be high. It was thus argued that the three-dimensional (3D) vortex lattice is thermally entangled and may “melt”. This type of transition and the consequences of melting are not clear as yet since the always present pinning of the vortex cores by material inhomogeneities may cause similar disorder. In HTSC the pinning energy may become comparable with kBT because the coherence length ξ (vortex radius) is small and T may be high. Therefore, thermally activated depinning competes with possible effects of “flux melting”, and the “irreversibility line” in the B-T-plane (B=magnetic field) should better be called “depinning line”. Due to the diffusive character of flux motion the depinning line of a given experiment, a line of constant flux diffusivity D(T, B), depends on the frequency or sweep rate, on the size and shape of the superconductor, and on the field orientation; it is thus not a material property alone. In this review it is argued that theories predicting “new phases of vortex matter” (flux solid, flux liquid, vortex plasma, vortex glass, and hexatic vortex glass) may be improved by replacing the 2D straight-vortex interaction by the correct 3D interaction between all vortex segments. This interaction (a) facilitates vortex crossing and reconnection, (b) reduces the elastic energy of short-wavelength tilt by a very large factor (non-local elasticity), and (c) yields the correct reduction of the tilt energy by the crystal anisotropy. The non-local elasticity of the VL is reviewed and a general solution of the anisotropic London theory for arbitrary vortex arrangements is given. A very useful phenomenological theory of layered superconductors is the Lawrence-Doniach model, which defines a 2D Ginzburg-Landau function in each layer. The point vortices in the layers interact with each other magnetically and, between neighboring layers, by Josephson coupling. At sufficiently large fields their thermal fluctuation is quasi-2D and, at an in general different field, their pinning becomes 2D.
APPLICATIONS OF ULTRAFAST LASER SPECTROSCOPY TO THE STUDY OF SEMICONDUCTOR PHYSICS
Authors: OCKMAN NATHAN , WANG WUBAO , ALFANO R.R. 
Published: November 2004

This article reviews the application of some of the principal methods of picosecond and femtosecond laser spectroscopy to the investigation of the dynamics of carriers, phonons and surface structure in semiconductors. The measurement of the temporal evolution of photoinduced luminescence, absorption, reflection and scattering in semiconductors makes it possible to obtain the lifetimes of photogenerated electrons, holes, excitons and phonons in both the bulk and quantum wells and superlattice structures. The information produced by these studies is necessary for the basic understanding of the underlying physics of semiconductors. In addition, the parameters obtained from these studies are needed for evaluating ultrafast transport, switching, photoconductive response and imaging in semiconductor materials, which will determine their limitations for use in high-speed and high-frequency devices and computers. For measuring time resolved luminescence, the principal techniques used, namely, the streak camera, the optical Kerr gate and the up-conversion gate are thoroughly discussed. Several pump and probe methods are described for the determination of time resolved absorption, reflection and Raman scattering. For absorption measurements where the probe wavelength differs from the pump, the former is generated in nonlinear media by means of stimulated Raman scattering and the supercontinuum for the UV and visible regions and by parametric and difference frequency generation for the near- and mid-IR. Nonlinear optics techniques considered are degenerate and nondegenerate four-wave mixing and transient grattings among which photon echoes yield the momentum relaxation of hot electrons. Coherent anti-Stokes Raman scattering (CARS) and phase conjugate Raman scattering (PC) are described to determine phonon dephasing times and the nonlinear susceptibility, χ3.
Lattice Effects in Flux Phases
Authors: Douçot B. 
Published: November 2004

The uniform flux phases of the t-J model are studied using a slave boson representation. The gaussian fluctuations around the mean field saddle point are calculated. A key feature is the cancellation of Hall conductances of the spinons and the holons, in the limit of small doping. This cancellation leads to a pole in the global electromagnetic response function, in a mechanism which is very similar to anyon superconductivity. Our main focus has been to evaluate the Hall conductance of the global system as a function of frequency and wave vector. Using various examples, we show that because of the cancellation of the two Hall conductances in the static and long wave-length limit, the behaviour of the global system is very sensitive to lattice effects. For instance, P. Wiegmann has found that the global Hall conductance vanishes in the static and long wave length limit, if one uses the response functions for the two dimensional continuous system. However, a direct calculation of the response functions starting from the Hofstadter spectrum leads to a finite Hall conductance in the absence of an external field. We show how this formalism can be used to calculate the local magnetic field which muons are expected to measure. The electric field of the muons induces a finite Hall current which in turn creates a finite magnetic field at the muon sites. Screening of the magnetic field by the Meissner effect has been taken into account and dielectric screening as well. Preliminary results indicate that the predicted fields are approximately one order of magnitude larger than the upper bound from experimental results obtained by the Vancouver group.
TESTING ON A HIGH SPEED ELECTRO-RHEOLOGICAL CLUTCH
Authors: JOHNSON A. R. , BULLOUGH W. A. , FIROOZIAN R. , HOSSEINI-SIANAKI A. , MAKIN J. , XIAO S. 
Published: November 2004

The design of a prototype ER clutch and its associated test facility have been described and sample results from the initial test programme are presented. The ER clutch shows considerable promise and outperforms various magnetic devices. Further clutch and ER fluid developments should increase these advantages. The test facility described provides a quick method for obtaining a wide range of important fluid properties from a single small quantity of fluid in a single test facility operating under realistic engineering conditions. The results reported emphasize the need for continuing ER fluid development to increase the ER shear stress, to reduce the viscosity of the ER fluid, to reduce the electronic to ER shear stress time delay, and to improve the durability of ER fluids.
COMBINING IMAGE PROCESSING OPERATORS AND NEURAL NETWORKS IN A FACE RECOGNITION SYSTEM
Authors: FLOCCHINI PAOLA , GARDIN FRANCESCO , MAURI GIANCARLO , PENSINI MARIA PIA , STOFELLA PAOLO 
Published: November 2004

This paper describes a system able to recognize human faces from different perspectives, and which have different expressions. It possibly presents some kind of noise in their representation. The problem of face recognition has been approached using a complex architecture based on a hierarchy of neural networks, with a particular self-referencing structure. The system, in fact, is structured as a tree in which nodes correspond to neural networks, each one having different tasks. Each leaf is a recognition module composed by some networks with different characteristics depending on the different preprocessing operators used. These networks are coordinated by a supervisor in a self-referencing structure. During the training phase, the supervisor, called Meta-Net, observes the behaviour of recognition nets and learns which net is more able in which task, while during the test phase it decides, given an input image, which weights to assign to each network and modifies their output in order to obtain the final result. This architecture shows a high generalization capability and allows the recognition of images with different kinds of noise better than what each single network can do, as confirmed by a preliminary experimental evaluation.
DESIGN OF TWO-LEVEL PIPELINED SYSTOLIC ARRAY AND ITS APPLICATION TO IMAGE
Authors: JEN CHEIN-WEI , LIU CHI-MIN 
Published: November 2004

Two-level pipelined systolic array can attain parallelism down to lower levels and provide much higher throughput and computational speed than conventional ones. This paper presents a design procedure starting from an algorithm representation, called Dependence Graph (DG). Arrays with different performances can be obtained by applying the various linear transformation matrices on DG. Image resampling is a process for image construction and display. It has important applications in image processing or in digital TV. In this paper, two design considerations are applied to build high-performance VLSI image resampler. First, two-level pipelined systolic array is designed to maximize parallelism and also make VLSI implementation highly feasible. Second, a modified two-pass resampling scheme is devised to reduce the amount of required storage and increase the concurrency between two passes of resampling. This image resampler can get a throughput of one pixel per clock period being smaller than the latency of an adder. The requirement for storage is only several line buffers.
GLOBAL BIFURCATION ANALYSIS OF THE DOUBLE SCROLL CIRCUIT
Authors: KOMURO M. , TOKUNAGA R. , MATSUMOTO T. , CHUA L. O. , HOTTA A. 
Published: November 2004

An in-depth analysis is made of the global 2-parameter bifurcation structures of the double scroll circuit in terms of their homoclinic, heteroclinic, and periodic orbits. Many fine details are uncovered via a 3-dimensional "unfolding" of the 2-parameter bifurcation structures. Major findings are: (i) The parameter sets which give rise to the homoclinic and heteroclinic orbits (homoclinic and heteroclinic bifurcation sets) studied in this paper are found to be all connected to each other via only one family of periodic orbits. (ii) Moreover, the structure of the windows of this family essentially determines the global structure of the periodic windows of the double scroll circuit. These bifurcation analyses are accomplished by deriving first the relevant bifurcation equations in exact analytic form and then solving these nonlinear equations by iterations. No numerical integration formula for differential equations are used.