bluuebunny/crossref_metadata_2025 huggingface dataset:
SOLITARY WAVES, SOLITON BOUND STATES AND CHAOS IN A DISSIPATIVE KORTEWEG-DE VRIES EQUATION
Authors: NEKORKIN VLADIMIR I. , VELARDE MANUEL G.
Published: November 2004

Propagating dissipative (localized) structures like solitary waves, pulses or “solitons,” “bound solitons,” and “chaotic” wave trains are shown to be solutions of a dissipation-modified Korteweg-de Vries equation that in particular appears in Marangoni-Bénard convection when a liquid layer is heated from the air side and in the description of internal waves in sheared, stably stratified fluid layers.
EFFECTS OF MULTIPLICATIVE NOISE ON A STOCHASTIC SWIFT-HOHENBERG EQUATION
Authors: GARCÍA-OJALVO J. , SANCHO J.M.
Published: November 2004

A generalised stochastic Swift-Hohenberg equation is studied as an example of a pattern-forming system under the influence of fluctuations. An external fluctuation which is coupled to the order parameter is considered. Ordered structures appear in regions where the homogeneous situation is stable when only internal noise is present. These structures are analysed by studying the behavior of the mean value of the transmitted flux, its statistical variance and its linear relaxation time.
CHAOTIZATION OF IONIZATION WAVES IN A DISCHARGE PLASMA
Authors: PAPANYAN V.O. , GRIGORYAN YU. I.
Published: November 2004

Self-generated ionization waves (moving striations) in a rare gases discharge positive column were studied experimentally on the boundaries between regular and chaotic oscillations. When the current was slightly changed, sequences of period-doubling bifurcations in the local intensity of plasma radiation were observed, which condensed to the critical point of chaotization. The “window” of periodic motion inside the chaotic region, with new sequences of bifurcations which gave rise to chaos as well as sequences of inverted bifurcations (which take place at decreasing current), were detected and examined. Fundamental constants of the Feigenbaum scenario were measured at medium pressures, δ=4.6±0.1 and α=2.6±0.6, showing the quadratic nonlinearity of a logistic map. A brief theoretical survey of ionization waves showed that 1D and 2D maps may be derived from nonlinear hydrodynamic plasma equations.
HIERARCHY OF INSTABILITIES AND SOLITONS IN AN ACOUSTIC DISTRIBUTED SYSTEM WITH FEEDBACK
Authors: DOLINCHUK S.G. , ZADOROZHNII V.I. , FEDORCHENKO A.M.
Published: November 2004

We have considered the hierarchy of instabilities, the transition to chaos, and the periodic generation of three-wave solitons in an acoustic distributed system with additional feedback and pumping. At positive feedback only steady-state conditions are shown to be stable. Self-oscillations, period-doubling bifurcations, and transition from quasiperiodicity to chaos of parametrically coupled waves have been found at negative feedback. “Hard” excitation of the generator leads to the formation of solitons. Established effects have been studied on dependence with physical parameters of a TeO 2 crystal.
ACTION INTEGRALS AND ENERGY SURFACES OF THE KOVALEVSKAYA TOP
Authors: DULLIN HOLGER R. , JUHNKE MARCUS , RICHTER PETER H.
Published: November 2004

The different types of energy surfaces are identified for the Kovalevskaya problem of rigid body dynamics, on the basis of a bifurcation analysis of Poincaré surfaces of section. The organization of their foliation by invariant tori is qualitatively described in terms of Poincaré-Fomenko stacks. The individual tori are then analyzed for sets of independent closed paths, using a new algorithm based on Arnold’s proof of the Liouville theorem. Once these paths are found, the action integrals can be calculated. Energy surfaces are constructed in the space of action variables, for six characteristic values of energy. The data are presented in terms of color graphs that give an intuitive access to this highly complex integrable system.
RESONANCE PATTERNS IN ONE-DIMENSIONAL ARRAYS OF COUPLED NONLINEAR EXCITABLE SYSTEMS
Authors: PÉREZ-MUÑUZURI V. , ALONSO M. , CHUA L.O. , PÉREZ-VILLAR V.
Published: November 2004

Periodical signal transmission of waves through a one-dimensional array of coupled nonlinear electronic excitable cells have been investigated experimentally. Periodic wave trains give rise to a full devil’s staircase. The dependence of firing numbers defined for an excitable medium, on the amplitude and frequency of forcing, excitability of the medium, and coupling strength between cells is investigated. A nonmonotonic dependence between the locking range and the excitability has been observed for various n:m resonance regions, for different coupling strengths.
EXPERIMENTAL STUDY OF FORCED CHUA’S OSCILLATOR
Authors: ITOH MAKOTO , MURAKAMI HIROYUKI , CHUA LEON O.
Published: November 2004

Chua’s oscillator driven by an external current source is studied. Our experimental study reveals the following rich variety of interesting bifurcation phenomena: (a) period adding; (b) frequency entrainment of chaos; (c) torus breakdown to chaos; (d) chaotic attractors with strange geometrical patterns; (e) regularity of periodic windows; (f) coexistence of multiple attractors; (g) period-preserving bifurcations; (h) large-sized chaotic attractors; (i) intermittent behavior. Furthermore, some interesting applications of the forced Chua’s oscillators are suggested.
THREE-DIMENSIONAL 2-FRAMED TQFTS AND SURGERY
Authors: SAWIN STEPHEN F.
Published: November 2004

The notion of 2-framed three-manifolds is defined. The category of 2-framed cobordisms is described, and used to define a 2-framed three-dimensional TQFT. Using skeletonization and special features of this category, a small set of data and relations is given that suffice to construct a 2-framed three-dimensional TQFT. These data and relations are expressed in the language of surgery.
A NOTE ON NON-CLASSICAL VIRTUAL KNOTS
Authors: KISHINO TOSHIMASA , SATOH SHIN
Published: November 2004

The first aim of this paper is to give an example of a virtual knot which vanishes all the known invariants and to show that it is a non-classical (in particular, non-trivial) knot. The second is to study some properties of the Z-polynomial of a virtual knot with virtual crossing number one and to show that there are infinitely many virtual knots with virtual crossing number two.
AN INTRODUCTORY GUIDE TO GREEN’S FUNCTION METHODS IN NUCLEAR MANY-BODY PROBLEMS
Authors: KUO T.T.S. , TZENG YIHARN
Published: November 2004

We present an elementary and fairly detailed review of several Green’s function methods for treating nuclear and other many-body systems. We first treat the single-particle Green’s function, by way of which some details concerning linked diagram expansion, rules for evaluating Green’s function diagrams and solution of the Dyson’s integral equation for Green’s function are exhibited. The particle-particle hole-hole (pphh) Green’s function is then considered, and a specific time-blocking technique is discussed. This technique enables us to have a one-frequency Dyson’s equation for the pphh and similarly for other Green’s functions, thus considerably facilitating their calculation. A third type of Green’s function considered is the particle-hole Green’s function. RPA and high order RPA are treated, along with examples for setting up particle-hole RPA equations. A general method for deriving a model-space Dyson’s equation for Green’s functions is discussed. We also discuss a method for determining the normalization of Green’s function transition amplitudes based on its vertex function. Some applications of Green’s function methods to nuclear structure and recent deep inelastic lepton-nucleus scattering are addressed.
BARYON MASSES IN COLOR DIELECTRIC MODEL
Authors: SAHU SARIRA
Published: November 2004

The non-scaling version of the Color Dielectric Model is used to calculate the SU(3) baryon octet and decuplet masses with the mean-field approximation and momentum projection method of Peierls and Yoccoz. Quantum mechanical treatment of the dielectric field is done by taking the coherent state approximation. For suitable set of parameters it is observed that the masses in the momentum projection method are in better agreement with the observed values than those of the mean-field ones.
KELVIN CIRCULATION IN A CRANKED ANISOTROPIC OSCILLATOR + BCS MEAN FIELD
Authors: ROSENSTEEL G. , GOODMAN A.L.
Published: November 2004

The Kelvin circulation vector is the hermitian kinematical observable that measures the true character of nuclear rotation. For a rotating deformed nucleus modeled by a selfconsistent cranked anisotropic oscillator mean field with BCS pairing, the expectation value of the Kelvin circulation operator depends upon the deformation and upon the strength of the pairing field. For zero pairing, the circulation acquires its rigid rotor value. As the pairing field increases, the circulation tends to zero, the irrotational flow limit. At critical values of the pairing field, the deformation and circulation make abrupt phase transitions.
PROPAGATOR MATRIX FOR PLANE WAVE REFLECTION FROM INHOMOGENEOUS ANISOTROPIC POROELASTIC SEAFLOOR
Authors: BADIEY M. , JAYA I. , CHENG A. H-D.
Published: November 2004

A propagator matrix method for the calculation of acoustic plane waves reflected from an inhomogeneous, anisotropic, poroelastic seafloor is presented. The matrix is integrated using an implicit technique. The results are first compared with homogeneous, isotropic poroelastic cases reported by Stoll and Kan1 for verification. Computations are then extended to the inhomogeneous and anisotropic cases of which no prior solutions were available.
ON GALERKIN METHODS FOR THE WIDE-ANGLE PARABOLIC EQUATION
Authors: AKRIVIS GEORGIOS D. , DOUGALIS VASSILIOS A. , KAMPANIS NIKOLAOS A.
Published: November 2004

We consider the third-order, wide-angle parabolic approximation of underwater acoustics in a medium with depth- and range-dependent speed of sound in the presence of dissipation and horizontal interfaces. We first discuss the theory of the existence and uniqueness of solutions to the problem and derive an energy estimate. We then discretize the problem in the depth variable using two types of Galerkin/finite element formulations that take into account the interface conditions, and in the range variable by the Crank–Nicolson and also a fourth-order accurate, implicit Runge–Kutta method. The resulting high-order numerical schemes are stable and convergent and are also shown to compare favorably with classical, implicit finite difference schemes in terms of computational effectiveness when applied to standard benchmark problems.
CHARACTERIZATION OF STOCHASTIC PROPAGATION AND SCATTERING VIA GABOR AND WAVELET TRANSFORMS
Authors: SIBUL L. H. , WEISS L. G. , DIXON T. L.
Published: November 2004

An application to remote acoustic sensing that remains unexploited is measuring acoustic scattering and spreading effects with wideband, coherent signal processing techniques. Such techniques allow distributed objects, such as a layer of scatterers due to bubbles or biological particles, and first order time variations in an ocean channel to be estimated. This paper presents narrowband and wideband methods for characterizing stochastic propagation and acoustic scattering in a time-varying ocean in terms of spreading functions. It is shown that the Gabor transform is the natural transform for estimating the narrowband spreading function, and the wavelet transform is the natural transform for estimating the wideband spreading function. Both techniques of characterization use a correlator processing structure in a monostatic transmitter/receiver configuration to estimate the spreading function.

The narrowband and wideband spreading functions characterize the distribution of scatterers in range and velocity (time and frequency) in a propagation channel. It is shown that the wideband formulation follows directly from a physical derivation. Moreover, wideband processing removes many of the narrowband restrictions and allows first order time variations, caused by inhomogeneities and relative motion in the ocean channel, to be processed. In addition, wideband techniques allow for increased time intervals and, therefore, increased energy transmission when the transmitter is peak-power-limited. Thus, weak scatterers that may have been unidentified with narrowband techniques may be identified with the wideband methods. Numerical examples for wideband characterization of a distributed scatterer are presented.
ROLE OF THE HE ATOM SURFACE POTENTIAL ON THE CU(001) PHONON DETERMINATION
Authors: FRANCHINI A. , SANTORO G. , BORTOLANI V. , BELLMAN A. , CVETKO D. , FLOREANO L. , MORGANTE A. , PELOI M. , TOMMASINI F. , ZAMBELLI T.
Published: November 2004

We present new measurements of He atom inelastic scattering from the (001) surface of Copper. Our results confirmed the recent data obtained in Gottingen and show that at large momentum transfer in the [Formula: see text] direction the intensity of the longitudinal resonance is larger than that of the Rayleigh wave. We interpret these results by evaluating the reflection coefficient in the Distorted Wave Born Approximation. By taking the He surface interaction potential as a sum of nonspherical pairwise potential we are able to explain quantitatively the behavior of the experimental spectra.
MONTE CARLO SIMULATION OF THE CRITICAL PROPERTIES OF QUASI-TWO-DIMENSIONAL QUANTUM HEISENBERG SYSTEMS
Authors: ROJDESTVENSKI I.V. , COTTAM M.G. , FAVORSKI I.A. , KUZNETSOVA T. , VORONTSOV-VELYAMINOV P.N.
Published: November 2004

The critical properties of spin S=1/2 isotropic Heisenberg ferromagnetic ultrathin films are investigated using the Handscomb Monte Carlo technique. We study a simple cubic lattice with nearest neighbor interactions, including the effects of different values for the interlayer and intralayer exchange parameters. The number of monolayers is taken as 1, 2, or 3, and also we examine the effects of dilution in one of the layers. Numerical calculations are presented for the critical behavior of the longitudinal susceptibility and the spin correlation range. The results are interpreted in terms of a two-dimensional type of critical behavior with renormalized (modified) exchange parameters.
DETERMINATION OF LINEAR-CHAIN MULTIPLE BOUND STATE RESONANCES IN REFLECTION HIGH-ENERGY ELECTRON DIFFRACTION
Authors: ZHAO T.C. , TONG S.Y. , IGNATIEV A.
Published: November 2004

Using the R-matrix dynamical theory of Reflection High-Energy Electron Diffraction (RHEED), we analyze the intensity anomalies commonly observed in RHEED rocking curves. Results for Ag(001) and Pt(111) show that the anomalies are associated with the trapping of particular components of the electron wave field inside the crystal by linear chain potential parallel to the surface. These pseudobound states correspond to minima in the total elastic flux of an ultrathin film (≤10 monolayer) and maxima in the inelastic flux. The discrete energy levels of the bound states in Ag(001) and Pt(111) are determined for the first time and the effect of such bound states on the rocking curves is discussed.
HOLOGRAPHIC INVERSION OF DIFFUSE ELECTRON DIFFRACTION INTENSITIES FOR THE Ni(001)/K STRUCTURE
Authors: HEINZ K. , WEDLER H.
Published: November 2004

At low temperatures many adsorbates arrange in lattice gas disorder on crystalline substrates. In a low energy electron diffraction (LEED) experiment this leads to diffuse intensities super-imposed on the sharp spots caused by the substrate. For the disordered adsorption system Ni(001)/K, we present two-dimensional intensity distributions as function of the electron energy and angle of incidence. They can be measured very fast (20 s per frame) and reliably using an automatic video based data acquisition technique. We show that diffuse intensity spectra DI(E) taken as function of energy for fixed surface parallel electron momentum transfer carry the information about the local adsorption structure. This is equivalent to conventional I(E) spectra taken for sharp spots. In the light of recent proposals it is shown that the diffuse single energy intensity pattern is not a hologram of the local structure because e.g. the reference wave is ill defined. However, the diffraction processes disturbing the pure reference wave cancel when the intensities of different energies are suitably averaged. It is demonstrated that the holographic reconstruction of real space information from such scanned energy data leads to reliable and well resolved atomic images. Full widths at half-maximum of such atomic images are not greater than 1 Å. Substrate atoms behind the reference atom in direction of the incident beam are imaged best. So, image reconstructions for different beam directions produce a full and high quality three-dimensional image of the local adsorption structure.
STRUCTURAL STUDIES OF MOLECULAR ADSORPTION AT SURFACES USING SCANNED-ENERGY MODE PHOTOELECTRON DIFFRACTION
Authors: WOODRUFF D.P.
Published: November 2004

A short review is presented of the use of scanned-energy mode photoelectron diffraction for the quantitative determination of the local adsorption structure of molecular species on wellcharacterised metal surfaces. Some of the results [notably for NO and CO adsorption on Ni(111)] highlight the importance of such true quantitative methods relative to "fingerprinting" via vibrational spectroscopy which is shown to have led to incorrect local adsorption site assignments. The use of direct methods for approximate site identification, and chemical-shift photoelectron diffraction for studies of more complex coadsorption structures is described with the aid of specific applications to molecular fragmentation and geometrical reaction path determination. The prognosis for further development and application is discussed.
SEGREGATION EFFECTS IN THE OXYGEN/CYCLOHEXANE/Ni{111} COADSORPTION SYSTEM
Authors: COOPER E. , RAVAL R.
Published: November 2004

The coadsorption of cyclohexane and oxygen on Ni{111} at 110 K was studied using reflectionadsorption infrared spectroscopy (RAIRS). The effect of postdosed oxygen on the cyclohexane adlayer can be understood in terms of repulsive oxygen-cyclohexane interactions which lead to segregation and compression of the cyclohexane islands.
A TEMPERATURE-PROGRAMED DESORPTION STUDY OF THE ADSORPTION AND REACTIONS OF D2O ON SINGLE CRYSTAL SILICON SURFACES
Authors: FLOWERS M.C. , JONATHAN N.B.H. , MORRIS A. , WRIGHT S.
Published: November 2004

The adsorption of D 2O and subsequent desorption of D 2 and SiO from Si(100)-2×1 and Si(111)-7×7 single crystal surfaces have been investigated using the technique of temperatureprogramed desorption. It has been found that adsorption on Si(100)-2×1 is rapid and can be interpreted in terms of first-order Langmuir adsorption kinetics. In contrast, adsorption on the Si(111)-7×7 surface proceeds at a very much slower rate following an initial rapid uptake. It is found that the D 2 TPD peak arising from D 2 O exposure is very similar in shape, width, and desorption temperature to that from atomic deuterium exposure except that a small fraction of the adsorbed deuterium is retained to higher temperatures.
ORDERED AND DISORDERED Sb-RICH InSb(100) SURFACES STUDIED BY STM
Authors: JONES T.S. , McCONVILLE C.F. , LEIBSLE F.M. , RICHARDSON N.V.
Published: November 2004

Atomic resolution scanning tunneling microscopy (STM) has been used to study the asymmetric-(1×3) and c(4×4) Sb-terminated reconstructions of InSb(100). STM images show that these are examples of ordered and disordered reconstructions respectively. The c(4×4) structure involves the chemisorption of excess Sb onto an already Sb-terminated surface with the resultant formation of Sb-Sb bonds in the surface layer. The (1×3) structure, however, consists of short chains of individual Sb atoms in the top surface layer. The c(4×4) structure can be converted into the A-(1×3) by annealing to 500 K with the subsequent loss of Sb.
THE ROLE OF PRECURSOR STATES IN CATALYSIS
Authors: BOWKER MICHAEL
Published: November 2004

It is proposed that weakly held precursor states of catalytically significant molecules can play a pivotal role in some types of catalytic reactions. The concept of the 'diffusion circle' is introduced which is experimentally manifested as a much higher cross-section for reaction between an incoming molecule from the gas phase and an adsorbed species than would be expected. This can yield kinetics which are of the Rideal-Eley type, although the reaction event itself is more properly described as Langmuir-Hinshelwood.
THE EFFECT OF SURFACE TEMPERATURE IN THE FRAGMENTATION OF H2 AT SURFACES
Authors: GATES G.A. , HOLLOWAY S.
Published: November 2004

A model calculation is presented using quantum wave packets that examines the fragmentation of H 2 on a metal surface. We include two spatial dimensions in the calculation, the molecule-surface distance and the vibrational coordinate. Two electronic states are considered corresponding to molecular and atomic states. We have investigated the dynamics in our previous studies of this system which have shown that it is possible for quantum interference to occur giving rise to oscillations in the atomic fragmentation energy distributions. In these studies we have investigated the effect of potential topology and initial vibrational state on the atomic fragmentation. We now extend this model to include surface temperature by using a surface mass model which is analogous to a classical "cube" model. It is shown that including surface temperature does not wash out the interference and oscillations are still found. The temperature dependence of the atomic fragmentation probability is shown to be dependent on the potential topology.
DIPOLE ACTIVITY AND POLARISATION OF SURFACE PHONONS IN THIN IONIC FILMS
Authors: LEE M.B. , FREDERICK B.G. , APAI G.
Published: November 2004

Surface phonon spectra in ultrathin α- Al 2 O 3 films prepared on metallic substrates show excitation of modes in the frequency range of the surface dipole forbidden ω_-branches according to the dielectric theory of EELS. We compare calculations of the z-polarisation of the FuchsKliewer modes based on lattice dynamics with dielectric theory and semi-microscopic results for a simple NaCl lattice type thin film in the limit of k→0 appropriate to the dipolar-scattering regime. The form of the primary-beam-energy-dependence of the ω_-branch in thin α- Al 2 O 3 films is similar to the lattice dynamics prediction but is of much greater intensity. While the strong k-dependence may be attributed in part to significant z-polarisation of the ω_-branch, mixing with microscopic surface modes seems likely.
POSSIBLE EVIDENCE FOR A VALENCE BAND SATELLITE IN PHOTOEMISSION SPECTRA FROM Sc(0001)
Authors: PATCHETT A.J. , DHESI S.S. , BLYTH R.I.R. , BARRETT S.D.
Published: November 2004

An intense photoemission feature is observed at a binding energy of ~10 eV in the UV photoemission spectra from the (0001) surfaces of bulk single crystals of rare-earth metals. This emission cannot be explained in terms of ground state electronic structure and we have been unable to attribute its existence to the presence of contamination of the surface. We present some evidence that may indicate its origin lies in the creation, by the photoemission process, of a metastable two-hole final state.
STRUCTURAL AND ELECTRICAL STABILITY OF METAL CONTACTS TO MBE GROWN CdTe LAYERS
Authors: DEVINE P. , MATTHEWS G.W. , SANDS D. , SCOTT C.G. , YOUSAF M. , BLOMFIELD C.J. , DHARMADASA I.M. , GREGORY G.C.
Published: November 2004

The properties of ohmic and rectifying contacts to CdTe epilayers have been studied with a view to establishing a contacting technology with sufficient reliability and stability for use in the fabrication of a variety of CdTe-based devices involving single and multilayer structures grown by MBE. In the case of n-type CdTe layers, evaporated gold has been found to yield Schottky barriers with initial height in excess of 0.9 eV but re-examination after a period of a few weeks at room temperature (or a much shorter time at elevated temperatures) has revealed a significant decline in the barrier height. Associated changes in the electrical properties of the semiconductor layers in the vicinity of the contact interface have been explored using C-V depth profiling measurements and these have been correlated with changes in the chemical structure observed by means of SIMS imaging techniques. In particular, a significant reduction in the uncompensated shallow donor density just below the metal-semiconductor interface has been found to be accompanied by an out diffusion of Te and Cd to the surface of the metal contact.
CHEMISORPTION OF Sb ON III-V(110) SURFACES
Authors: SRIVASTAVA G.P.
Published: November 2004

We present a self-consistent pseudopotential study of the atomic geometry, electronic states, and chemisorption of ordered one and two monolayers of Sb on III-V(110) surfaces. For the first monolayer the Sb atoms chemisorb most strongly in the epitaxially continued layer structure (ECLS). The calculated interface atomic geometry agrees well with LEED and X-ray standing wave analyses, and the interface states in the bulk band gap agree with recent photoemission data. For ordered two monolayers in the ECLS the interface shows a metal-like density of states in the band gap.
DISSOCIATIVE CHEMISORPTION OF H2(D2) AT Fe(110)
Authors: WIGHT A. , HODGSON A. , WORTHY G. , BUTLER D. , HAYDEN B.E.
Published: November 2004

The dissociative chemisorption of H2(D2) at a Fe(110) surface has been studied as a function of translational energy ET, internal energy Ei, incident angle θi, and surface temperature Ts. Adsorption is activated, the sticking probability increasing steadily with translational energy with no evidence of a threshold for dissociation. Within experimental error there is no isotope effect or surface temperature dependence (180 K<Ts<400 K). Using seeded beams at constant translational energy, sticking on a clean surface is insensitive to the internal state distribution of the incident molecules, consistent with a barrier to dissociative chemisorption in the entrance channel. For translational energies below 0.2 eV sticking deviates from normal energy scaling, momentum parallel to the surface strongly inhibiting dissociative chemisorption. Dissociaton is interpreted in terms of a localised surface site for dissociative chemisorption at low energies.
Implications of Gene Networks for Understanding Resilience and Vulnerability in the Kidney Branching Program
Authors: Sampogna Rosemary V. , Nigam Sanjay K.
Published: November 2004

Branching morphogenesis in the kidney is tightly regulated. Whereas disruption of certain pathways produces catastrophic effects, numerous instances exist in which mutation of ostensibly key molecules has minimal apparent phenotypic consequence. We suggest how the network structure of gene interactions in the branching program might explain these findings as well as apparant discrepancies between in vivo and in vitro studies. Emerging genetic, cell-biological, and microarray data should help test and/or clarify these ideas.
Pulse Pressure and Coronary Atherosclerosis Progression in Postmenopausal Women
Authors: Nair Girish V. , Waters David , Rogers William , Kowalchuk Glen J. , Stuckey Thomas D. , Herrington David M.
Published: November 2004

Pulse pressure, an index of large artery stiffness, has been associated with coronary events. However, mechanisms for this association remain unclear. In this study, we examined the relationship between pulse pressure and the progression of coronary atherosclerosis and the effects of hormone replacement therapy (HRT) on pulse pressure in postmenopausal women with angiographically confirmed coronary disease followed for 3.2 years in the Estrogen Replacement in Atherosclerosis (ERA) trial. In the ERA trial, 309 postmenopausal women (mean age 66±7 years) with coronary disease were randomized to estrogen, estrogen plus progestin, or placebo, and followed for 3.2 years. Ten standardized epicardial segments were measured for minimal diameter values at baseline and follow-up using quantitative coronary angiography. For this study, mixed-model analysis of covariance was used to: (1) test the association between pulse pressure and change in mean minimum diameter (MMD) adjusted for baseline MMD and (2) the effect of HRT on follow-up pulse pressure. After adjustment for potential confounders, there was a significant graded increase in progression of coronary stenosis with increasing quartiles of baseline pulse pressure (
P
test for trend=0.0001). The progression rate in women with the highest quartile of baseline pulse pressure was 5-fold higher than in women in the lowest quartile (
P
<0.01). In postmenopausal women with coronary disease, increased levels of baseline pulse pressure are associated with subsequent progression of coronary atherosclerosis in postmenopausal women. HRT had no detectable effect on pulse pressure.
Knowing Evil When You See It: Uses for the Rhetoric of Evil in International Relations
Authors: Casebeer William D.
Published: November 2004

The rhetoric of evil has been a mainstay in international affairs, although President Bush’s use of the phrase ‘axis of evil’ has elevated its prominence. Few, however, have attempted an analytically defensible definition of evil as it relates to international events. I attempt this, identifying commonalities that unite historical deployment of the term: an evaluation of evil cuts across the traditional ethical axes of evaluation of ‘person’ (virtue theory), ‘nature of action’ (deontology), and ‘consequence’ (utilitarianism). This analysis will help identify possible roles that the concept of evil plays in our international linguistic economy and what purposes it serves. I briefly discuss these roles (motivational, counterforce, divisional, and evaluational). Clarifying the meaning of the term evil and its usage in global political discourse will highlight the pitfalls that accompany the use of such rhetoric in international relations, which include forestalling possibilities of redemptive reform.
The Enduring Dilemmas of Realism in International Relations
Authors: Guzzini Stefano
Published: November 2004

The present article argues that the discipline of international relations is bound to repeat its rounds of debates about realism as long as the underlying dynamic intrinsic to the realist tradition is not understood. Whereas present debates tend to criticize contemporary realists for going astray (an unhappy conjuncture, as it were), this article claims that there exists a systematic theoretical problem with the way realist theorizing has developed within international relations, and consisting of two fundamental dilemmas. The first or ‘identity dilemma’, the choice between distinctiveness and determinacy, results from the characteristics of the central concept ‘power’ — realists either keep a distinct and single micro–macro link through concepts of power/influence which provides indeterminate explanations or they improve their explanations, but must do so by relaxing their assumptions, thereby losing distinctiveness. The second or ‘conservative dilemma’, the choice between tradition and justification, results from the fact that realism is a form of practical knowledge, which needs some form of justification other than the recourse to mere tradition. Hence, realists either update the practical knowledge of a shared diplomatic culture while losing scientific credibility or, reaching for logical persuasiveness, cast their maxims in a scientific mould which distorts the realist tradition. Realism in international relations is fated to return to these dilemmas until it abandons its own identity as derived from the ‘first debate’ between realism and idealism. By doing so, however, it would be free to join a series of metatheoretical and theoretical research avenues which it has so far left to other schools of thought.
Catching the State Off Guard
Authors: Eisenstadt Todd A.
Published: November 2004

This article seeks to understand which model of electoral management body (EMB) best regulates campaign finance excesses in a hard case for EMB independence, Mexico’s one-party state during democratization (1977–2003). One would expect that the ombudsman model, where the electoral court is more autonomous from the party-state than EMB models in which the executive supervises elections directly or indirectly, would be the strongest regulatory body. However, I report that, contrarily, the indirect executive supervision EMB has rendered much more autonomous, anti-government decisions. The conclusion I draw is that the contexts in which formal institutions operate may be as important as the institutions themselves. Depoliticized electoral justice, even in the hard case of electoral courts in a fraud-marred one-party system, was largely attained, but under the ‘ombudsman’ institutional model which preceded the electoral courts’ formal incorporation into the judicial branch in the mid-1990s. It took informal political conditions – alternation in power and acceptance of this 2000 electoral watershed by the former ruling party – and a related change in the relationship with their nominators, to resume and accelerate the insulation of electoral case law from the magistrates’ nominator, the president. The achievement of true electoral court autonomy in Mexico is best evidenced through its monitoring of party finance.
Modeling of cell signaling pathways in macrophages by semantic networks
Authors: Hsing Michael , Bellenson Joel L , Shankey Conor , Cherkasov Artem
Published: November 2004

Background

Substantial amounts of data on cell signaling, metabolic, gene regulatory and other biological pathways have been accumulated in literature and electronic databases. Conventionally, this information is stored in the form of pathway diagrams and can be characterized as highly "compartmental" (i.e. individual pathways are not connected into more general networks). Current approaches for representing pathways are limited in their capacity to model molecular interactions in their spatial and temporal context. Moreover, the critical knowledge of cause-effect relationships among signaling events is not reflected by most conventional approaches for manipulating pathways.

Results

We have applied a semantic network (SN) approach to develop and implement a model for cell signaling pathways. The semantic model has mapped biological concepts to a set of semantic agents and relationships, and characterized cell signaling events and their participants in the hierarchical and spatial context. In particular, the available information on the behaviors and interactions of the PI3K enzyme family has been integrated into the SN environment and a cell signaling network in human macrophages has been constructed. A SN-application has been developed to manipulate the locations and the states of molecules and to observe their actions under different biological scenarios. The approach allowed qualitative simulation of cell signaling events involving PI3Ks and identified pathways of molecular interactions that led to known cellular responses as well as other potential responses during bacterial invasions in macrophages.

Conclusions

We concluded from our results that the semantic network is an effective method to model cell signaling pathways. The semantic model allows proper representation and integration of information on biological structures and their interactions at different levels. The reconstruction of the cell signaling network in the macrophage allowed detailed investigation of connections among various essential molecules and reflected the cause-effect relationships among signaling events. The simulation demonstrated the dynamics of the semantic network, where a change of states on a molecule can alter its function and potentially cause a chain-reaction effect in the system.
Enhanced Dupuytren's disease fibroblast populated collagen lattice contraction is independent of endogenous active TGF-β2
Authors: Tse Raymond , Howard Jeffrey , Wu Yan , Gan Bing Siang
Published: November 2004

Background

Dupuytren's disease (DD) is a debilitating fibro-proliferative disorder of the hand characterized by the appearance of fibrotic lesions (nodules and cords) leading to flexion contractures of the fingers and loss of hand function. Although the molecular mechanism of DD is unknown, it has been suggested that transforming growth factor-β2 (TGF-β2) may play an important role in the underlying patho-physiology of the disease. The purpose of this study was to further explore this hypothesis by examining the effects of TGF-β2 on primary cell cultures derived from patient-matched disease and normal palmar fascia tissue using a three-dimensional collagen contraction assay.

Methods

Fibroblast-populated collagen lattice (FPCL) contraction assays using primary cell cultures derived from diseased and control fascia of the same DD patients were studied in response to exogenous TGF-β2 and neutralizing anti-TGF-β2 antibodies.

Results

Contraction of the FPCLs occurred significantly faster and to a greater extent in disease cells compared to control cells. The addition of TGF-β2 enhanced the rate and degree of collagen contraction in a dose-dependent fashion for both control and diseased cells. Neutralizing anti-TGF-β2 antibodies abolished exogenous TGF-β2 stimulated collagen contraction, but did not inhibit the enhanced basal collagen contraction activity of disease FPCL cultures.

Conclusions

Although exogenous TGF-β2 stimulated both disease and control FPCL contraction, neutralizing anti-TGF-β2 antibodies did not affect the elevated basal collagen contraction activity of disease FPCLs, suggesting that the differences in the collagen contraction activity of control and disease FPCL cultures are not due to differences in the levels of endogenous TGF-β2 activity.
Omega-3 fatty acids and major depression: A primer for the mental health professional
Authors: Logan Alan C
Published: November 2004

Omega-3 fatty acids play a critical role in the development and function of the central nervous system. Emerging research is establishing an association between omega-3 fatty acids (alpha-linolenic, eicosapentaenoic, docosahexaenoic) and major depressive disorder. Evidence from epidemiological, laboratory and clinical studies suggest that dietary lipids and other associated nutritional factors may influence vulnerability and outcome in depressive disorders. Research in this area is growing at a rapid pace. The goal of this report is to integrate various branches of research in order to update mental health professionals.
Methodology for evaluating Insite: Canada's first medically supervised safer injection facility for injection drug users
Authors: Wood Evan , Kerr Thomas , Lloyd-Smith Elisa , Buchner Chris , Marsh David C , Montaner Julio SG , Tyndall Mark W
Published: November 2004

Many Canadian cities are experiencing ongoing infectious disease and overdose epidemics among injection drug users (IDUs). In particular, Human Immunodeficiency Virus (HIV) and hepatitis C Virus (HCV) have become endemic in many settings and bacterial and viral infections, such as endocarditis and cellulitis, have become extremely common among this population. In an effort to reduce these public health concerns and the public order problems associated with public injection drug use, in September 2003, Vancouver, Canada opened a pilot medically supervised safer injecting facility (SIF), where IDUs can inject pre-obtained illicit drugs under the supervision of medical staff. The SIF was granted a legal exemption to operate on the condition that its impacts be rigorously evaluated. In order to ensure that the evaluation is appropriately open to scrutiny among the public health community, the present article was prepared to outline the methodology for evaluating the SIF and report on some preliminary observations. The evaluation is primarily structured around a prospective cohort of SIF users, that will examine risk behavior, blood-borne infection transmission, overdose, and health service use. These analyses will be augmented with process data from within the SIF, as well as survey's of local residents and qualitative interviews with users, staff, and key stakeholders, and standardised evaluations of public order changes. Preliminary observations suggest that the site has been successful in attracting IDUs into its programs and in turn helped to reduce public drug use. However, each of the indicators described above is the subject of a rigorous scientific evaluation that is attempting to quantify the overall impacts of the site and identify both benefits and potentially harmful consequences and it will take several years before the SIF's impacts can be appropriately examined.
Assessment of possible impact of a health promotion program in Korea from health risk trends in a longitudinally observed cohort
Authors: Park J , Jee SH , Edington DW
Published: November 2004

Background

Longitudinally observed cohort data can be utilized to assess the potential for health promotion and healthcare planning by comparing the estimated risk factor trends of non-intervened with that of intervened. The paper seeks (1) to estimate a natural transition (patterns of movement between states) of health risk state from a Korean cohort data using a Markov model, (2) to derive an effective and necessary health promotion strategy for the population, and (3) to project a possible impact of an intervention program on health status.

Methods

The observed transition of health risk states in a Korean employee cohort was utilized to estimate the natural flow of aggregated health risk states from eight health risk measures using Markov chain models. In addition, a reinforced transition was simulated, given that a health promotion program was implemented for the cohort, to project a possible impact on improvement of health status. An intervened risk transition was obtained based on age, gender, and baseline risk state, adjusted to match with the Korean cohort, from a simulated random sample of a US employee population, where a health intervention was in place.

Results

The estimated natural flow (non-intervened), following Markov chain order 2, showed a decrease in low risk state by 3.1 percentage points in the Korean population while the simulated reinforced transition (intervened) projected an increase in low risk state by 7.5 percentage points. Estimated transitions of risk states demonstrated the necessity of not only the risk reduction but also low risk maintenance.

Conclusions

The frame work of Markov chain efficiently estimated the trend, and captured the tendency in the natural flow. Given only a minimally intense health promotion program, potential risk reduction and low risk maintenance was projected.
Rate of first recorded diagnosis of autism and other pervasive developmental disorders in United Kingdom general practice, 1988 to 2001
Authors: Smeeth Liam , Cook Claire , Fombonne Professor Eric , Heavey Lisa , Rodrigues Laura C , Smith Peter G , Hall Andrew J
Published: November 2004

Background

There has been concern that the incidence of autism and other pervasive developmental disorders (PDDs) is increasing. Previous studies have been smaller, restricted to autism (excluding other pervasive developmental disorders such as Asperger's syndrome), included boys only, or have not been based on a national sample. We investigated time trends in the rates of diagnosis of pervasive developmental disorders.

Methods

We analysed the rates of first diagnosis of pervasive developmental disorders among people registered with a practice contributing to the United Kingdom General Practice Research Database during the period 1988 to 2001. We included 1410 cases from over 14 million person-years of observation. The main outcome measures were rates of diagnosis of pervasive developmental disorders by year of diagnosis, year of birth, gender and geographical region.

Results

The rate increased progressively from 0.40/10,000 person-years (95% CI 0.30 to 0.54) in 1991 to 2.98/10,000 (95% CI 2.56 to 3.47) in 2001. A similar change occurred in the age standardised incidence ratios, from 35 (95% CI: 26–47) in 1991 to 365 (95% CI: 314–425) in 2001. The temporal increase was not limited to children born during specific years nor to children diagnosed in a specific time period. The rate of diagnosis of PDDs other than autism rose from zero for the period 1988–1992 to 1.06/10,000 person-years in 2001. The rate of diagnosis of autism also increased but to a lesser extent. There was marked geographical variation in rates, with standardised incidence ratios varying from 66 for Wales to 141 for the South East of England.

Conclusions

Better ascertainment of diagnosis is likely to have contributed to the observed temporal increase in rates of diagnosis of PDD, but we cannot exclude a real increase.
Is immunotherapy an effective treatment for Alzheimer's disease?
Authors: Licastro Federico , Caruso Calogero
Published: November 2004

Immunotherapy in patients with Alzheimer's disease (AD) is rapidly becoming a hot topic of modern geriatric and clinical gerontology. Current views see immunization with Aβ peptide, the amyloidogenic protein found in senile plaque of AD patient's brains, or the infusion of preformed antibody specific for human Aβ, as possible therapeutic approaches to improve the cognitive status in the disease. Animal models of the disease have provided positive results from both approaches. Thus, an initial clinical trial using immunization with human Aβ in AD patients was started, but then shortly halted because of an unusually high incidence (6%) of meningoencephalitis. A long and currently ongoing debate in the scientific community about the pro or contra of vaccination or passive immunization with Aβ in AD is thereafter started. Here, the authors would like to stress few points of concern regarding these approaches in clinical practice.
Thermochemical processing using powder metal fuels of radioactive and hazardous waste
Authors: Ojovan M. I. , Lee W. E. , Sobolev I. A. , Dmitriev S. A. , Karlina O. K. , Klimov V. L. , Petrov G. A. , Semenov C. N.
Published: November 2004

An overview of thermochemical treatment technologies (TTTs) for radioactive and toxic wastes is given. TTTs have been developed for pretreatment (e.g. decontamination), treatment and conditioning of specific wastes such as mixed, organic or chlorine-containing radioactive waste and contaminated soils. TTTs use powder metal fuels (PMFs) specifically formulated for the waste composition, which react with some of the waste components. Thermochemical processing can be carried out in a self-sustaining regime and enables ecologically safe processing of wastes without complex and expensive equipment. It leads to almost total confinement of contaminants in a mineral or glass composite end-product with minimal release of hazardous components and radionuclides in the off-gas.
Effect of high mass fluxes on heat and mass transfer through a flat surface
Authors: Kar S , Chen X. D.
Published: November 2004

In the present case study, a highly idealized situation of an incompressible fluid flowing horizontally over a flat surface, consisting of a volatile liquid in a saturated state undergoing vaporization, is considered. The problem is similar to that reported by Bird et al. [1], but allowance is made for cases in which heat and mass transfer is sufficiently high to make it necessary to allow for significant temperature and concentration variations in the boundary layer. The situation that is taken into consideration here is similar to the one analysed by Bird et al. [1]. The present approach yields a lower bound estimate of the heat and mass transfer coefficient, and it is anticipated that the experimental values (though extremely difficult to find until now) will lie in-between the predictions given by Bird et al. [1] and the present results. The case study aims to develop suitable correction factors for the heat and mass transfer coefficients when the mass flux at the interface is high.