bluuebunny/crossref_metadata_2025 huggingface dataset:
Annoyance caused by the sounds of a magnetic levitation train
Authors: Vos Joos
Published: March 2004

In a laboratory study, the annoyance caused by the passby sounds from a magnetic levitation (maglev) train was investigated. The listeners were presented with various sound fragments. The task of the listeners was to respond after each presentation to the question: “How annoying would you find the sound in the preceding period if you were exposed to it at home on a regular basis?” The independent variables were (a) the driving speed of the maglev train (varying from 100 to 400 km/h), (b) the outdoor A-weighted sound exposure level (ASEL) of the passbys (varying from 65 to 90 dB), and (c) the simulated outdoor-to-indoor reduction in sound level (windows open or windows closed). As references to the passby sounds from the maglev train (type Transrapid 08), sounds from road traffic (passenger cars and trucks) and more conventional railway (intercity trains) were included for rating also. Four important results were obtained. Provided that the outdoor ASELs were the same, (1) the annoyance was independent of the driving speed of the maglev train, (2) the annoyance caused by the maglev train was considerably higher than that caused by the intercity train, (3) the annoyance caused by the maglev train was hardly different from that caused by road traffic, and (4) the results (1)–(3) held true both for open or closed windows. On the basis of the present results, it might be expected that the sounds are equally annoying if the ASELs of the maglev-train passbys are at least 5 dB lower than those of the intercity train passbys. Consequently, the results of the present experiment do not support application of a railway bonus to the maglev-train sounds.
Caustic envelopes and cusp coordinates due to the reflection of a spherical wave from a layered sediment
Authors: Ainslie Michael A. , Robins Alvin J. , Simons Dick G.
Published: March 2004

A compilation of analytical formulas is presented, describing ray properties of a family of sediment sound speed profiles. The profiles are described as “generalized power law” profiles because they are generalizations of a similar family of simpler power law profiles considered in earlier work [M. A. Ainslie, J. Acoust. Soc. Am. 96, 2506–2515 (1994)]. Properties considered include ray paths, caustic envelopes, and cusp coordinates due to a point source in isovelocity water. For a few example cases the caustic shapes are illustrated by computing the pressure field using a normal mode program.
Acoustic waves generated by a laser line pulse in cylinders; Application to the elastic constants measurement
Authors: Pan Y. , Rossignol C. , Audoin B.
Published: March 2004

A model is proposed to predict acoustic waves generated in a transversely isotropic cylinder by a laser line pulse extended in beamwidth and time duration, and an application to elastic constants measurement is presented. Documented good agreements are observed in the comparison of experimental and theoretical normal displacements for aluminum cylinders under either ablation or thermoelastic generation. Bulk waves are identified and processed for the elastic constants measurement. The effects of source beamwidth and time duration on wave forms and on the elastic constants measurement are predicted by numerical simulations. For nondestructive evaluation applications using bulk waves, a radius of 0.3 mm appears as a minimum limit for the sample size using a laser source of 0.1 mm beamwidth and 20 ns time duration. Elastic constants of aluminum rods are experimentally measured with very good accuracy.
A three-dimensional model of vocal fold abduction/adduction
Authors: Hunter Eric J. , Titze Ingo R. , Alipour Fariborz
Published: March 2004

A three-dimensional biomechanical model of tissue deformation was developed to simulate dynamic vocal fold abduction and adduction. The model was made of 1721 nearly incompressible finite elements. The cricoarytenoid joint was modeled as a rocking–sliding motion, similar to two concentric cylinders. The vocal ligament and the thyroarytenoid muscle’s fiber characteristics were implemented as a fiber–gel composite made of an isotropic ground substance imbedded with fibers. These fibers had contractile and/or passive nonlinear stress–strain characteristics. The verification of the model was made by comparing the range and speed of motion to published vocal fold kinematic data. The model simulated abduction to a maximum glottal angle of about 31°. Using the posterior-cricoarytenoid muscle, the model produced an angular abduction speed of 405° per second. The system mechanics seemed to favor abduction over adduction in both peak speed and response time, even when all intrinsic muscle properties were kept identical. The model also verified the notion that the vocalis and muscularis portions of the thyroarytenoid muscle play significantly different roles in posturing, with the muscularis portion having the larger effect on arytenoid movement. Other insights into the mechanisms of abduction/adduction were given.
Computing fluid-coupled resonance frequencies, mode shapes, and damping loss factors using the singular value decomposition
Authors: Fahnline John B.
Published: March 2004

In many acoustic design problems, it would be useful to be able to compute fluid-coupled resonance frequencies, mode shapes, and their associated damping levels. Unfortunately, conventional eigenvalue solution procedures are either computationally inefficient, unreliable, or have limited applicability. Sophisticated methods for identifying modal parameters using the singular value decomposition have recently emerged in the area of experimental modal analysis, where the available data typically consists of velocity-to-force transfer functions for several drive point locations. In this paper, we show that these techniques can be applied to numerically generated frequency domain data and are even more effective because full matrices of transfer function data are available. This typically allows the modes to be completely separated from each other, such that the modal parameters can be identified using analytical formulas. Several benchmark example problems are solved numerically, including a rectangular cantilever plate, a baffled circular plate, and a baffled circular plate covered by an open-ended rigid-walled pipe.
Dynamic stability of a beam excited by a sequence of moving mass particles (L)
Authors: Mackertich Seroj
Published: March 2004

The dynamic stability of an elastically supported Timoshenko beam exited by a continuous sequence of identical, mass particles attached to and traveling at a constant velocity across the beam has been investigated. The regions of dynamic stability are determined for different physical system parameters. Floquet theory is utilized to study the parametric regions of stability, which are displayed in graphical form.
A note on the concept of acoustic center
Authors: Jacobsen Finn , Barrera Figueroa Salvador , Rasmussen Knud
Published: March 2004

The acoustic center of a reciprocal transducer is defined as the point from which spherical waves seem to be diverging when the transducer is acting as a source. This paper examines various ways of determining the acoustic center of a source, including methods based on deviations from the inverse distance law and methods based on the phase response. The considerations are illustrated by experimental results for condenser microphones.
An approach to real-time magnetic resonance imaging for speech production
Authors: Narayanan Shrikanth , Nayak Krishna , Lee Sungbok , Sethy Abhinav , Byrd Dani
Published: March 2004

Magnetic resonance imaging (MRI) has served as a valuable tool for studying static postures in speech production. Now, recent improvements in temporal resolution are making it possible to examine the dynamics of vocal-tract shaping during fluent speech using MRI. The present study uses spiral k-space acquisitions with a low flip-angle gradient echo pulse sequence on a conventional GE Signa 1.5-T CV/i scanner. This strategy allows for acquisition rates of 8–9 images per second and reconstruction rates of 20–24 images per second, making veridical movies of speech production now possible. Segmental durations, positions, and interarticulator timing can all be quantitatively evaluated. Data show clear real-time movements of the lips, tongue, and velum. Sample movies and data analysis strategies are presented.
Frequency–domain wave equation and its time–domain solutions in attenuating media
Authors: Sushilov Nikolai V. , Cobbold Richard S. C.
Published: March 2004

Our purpose in this paper is to describe the wave propagation in media whose attenuation obeys a frequency power law. To achieve this, a frequency–domain wave equation was developed using previously derived causal dispersion relations. An inverse space and time Fourier transform of the solution to this algebraic equation results in a time–domain solution. It is shown that this solution satisfies the convolutional time–domain wave equation proposed by Szabo [J. Acoust. Soc. Am. 96, 491–500 (1994)]. The form of the convolutional loss operator contained in this wave equation is obtained. Solutions representing the propagation of both plane sinusoidal and transient waves propagating in media with specific power law attenuation coefficients are investigated as special cases of our solution. Using our solution, comparisons are made for transient one-dimensional propagation in a medium whose attenuation is proportional to frequency with recently obtained numerical solutions of Szabo’s equation. These show good agreement.
Forced response of a cylindrical waveguide with simulation of the wavenumber extraction problem
Authors: Damljanović Vesna , Weaver Richard L.
Published: March 2004

The steady state response of a cylindrical elastic waveguide of arbitrary cross section to a harmonic load is considered. The inverse problem of wavenumber extraction is simulated using finite element discretization of the cross section. The case of a concentrated lateral point load on a railroad rail is used for illustration, at a frequency of 202 Hz, corresponding to a frequency well below the first cutoff, but above the regime where simple strength of materials concepts are accurate. The work is conceived with a view towards applications in the nondestructive characterization of such beams by means of scanned laser vibrometry for measurement of lateral bending wavenumbers dependent on a contained static axial load. Simulations of such measurements are generated, and subjected to noise and to a variety of potential systematic errors. Linear and nonlinear least squares minimization of the residual between simulated measurements and fits show that the lateral bending wavenumber can be recovered accurately, with remarkable robustness, even in the presence of noise and systematic errors.
Experimental investigation of ultrasound propagation in turbulent, diffractive media
Authors: Andreeva T. A. , Durgin W. W.
Published: March 2004

Experimental study of the propagation of high-frequency acoustic waves in grid-generated turbulence in laboratory conditions by means of ultrasound technique is considered. The travel time and log-amplitude variance of acoustic waves are investigated as functions of travel distance and mean velocity. Experimental data were interpreted using theoretical analysis based on ray acoustics and Rytov approximation. The travel time shift in acoustic wave propagation in turbulent and undisturbed media is observed.
Computation of exhaust mixing noise using large-eddy simulation turbulence modeling and Lighthill's acoustic analogy
Authors: Schein David Brian
Published: March 2004

This research involves computational study of free, heated jet flow and resultant far-field sound performed using large-eddy simulation (LES) and Lighthill's acoustic analogy. A subgrid-scale model for small-scale compressible turbulence was developed using a combination of the popular Smagorinsky model and a deductive model. An existing software package for compressible flow field computation was substantially modified to perform temporal LES and aerosound simulations. Cases studied extend to large Reynolds number (Re), high subsonic (compressible) flow with realistic geometries more representative of aircraft engine exhausts than typically considered using direct numerical simulation (DNS). Flow-field fluctuations are stored over a period of time and used to calculate rms turbulence within the computational domain. The far-field sound and directivity is computed using the time-derivative form of Lighthill's source-integral result formulated in terms of quadrupole sources from the simulated flow field, which is integrated in time and contains the fluctuations set up by the time-varying stress tensor. A simulation for a WR19–4 turbofan engine exhaust (Re>106 based on exist velocity and diameter) is presented, and propagated jet noise results are compared with experimental acoustic data.

Thesis advisor: William C. Meecham

Copies of this thesis written in English can be obtained from
N
-shell cluster in water: Multiple scattering and splitting of resonances
Authors: Le Bas Pierre-Yves , Luppé Francine , Conoir Jean-Marc , Franklin Hervé
Published: March 2004

Clusters of N thin parallel and identical shells (aligned or not) in water are considered. Assuming a harmonic plane wave is normally incident upon one cluster, the scattered-field classical expression is recalled, and then computed for different types of clusters, along with resonance spectra. The scattering S matrix is defined, and its unitarity property used to check the numerical results. All spectra are compared with that of a single shell, in the frequency range where resonances are due to an A-wave phase matching only. Whatever the cluster, each resonance of the single shell is seen to split into M different ones. The value of M depends on the number of shells, the distance between them, and the symmetries of the cluster. Apart from the very special case of aligned shells (M=2N), no simple law has been found to predict the value of M.
Measuring sperm whales from their clicks: Stability of interpulse intervals and validation that they indicate whale length
Authors: Rhinelander Marcus Q. , Dawson Stephen M.
Published: March 2004

Multiple pulses can often be distinguished in the clicks of sperm whales (Physeter macrocephalus). Norris and Harvey [in Animal Orientation and Navigation, NASA SP-262 (1972), pp. 397–417] proposed that this results from reflections within the head, and thus that interpulse interval (IPI) is an indicator of head length, and by extrapolation, total length. For this idea to hold, IPIs must be stable within individuals, but differ systematically among individuals of different size. IPI stability was examined in photographically identified individuals recorded repeatedly over different dives, days, and years. IPI variation among dives in a single day and days in a single year was statistically significant, although small in magnitude (it would change total length estimates by <3%). As expected, IPIs varied significantly among individuals. Most individuals showed significant increases in IPIs over several years, suggesting growth. Mean total lengths calculated from published IPI regressions were 13.1 to 16.1 m, longer than photogrammetric estimates of the same whales (12.3 to 15.3 m). These discrepancies probably arise from the paucity of large (12–16 m) whales in data used in published regressions. A new regression is offered for this size range.
Estimating lithology and fluid parameters from seismic data
Authors: Farrell Michael E.
Published: March 2004

A constrained inversion approach is presented for making quantitative estimates of lithology and fluid parameters using compressional wave reflection data (P-to-P) and converted wave reflection data (P-to-S). The method is horizon based, and requires the seismic amplitude information from multiple offsets at a particular zone of interest. Results are discussed from two specific cases. In the first example estimates of lithology are derived from only P-to-P reflection data, assuming the fluid properties are known. This turns out to be a well-posed problem with a unique solution, and is robust in the presence of additive random noise. In the second example both lithology and fluid parameters are estimated using a joint inversion of P-to-P and P-to-S seismic data. This is a much more difficult problem, and does not have a unique solution. However, by including realistic lithology and fluid constraints, good estimates of the parameters can be obtained. Furthermore, adding these constraints to the inversion of only P-to-P wave data also yields a good solution. This suggests that the constraints are more important than doing a joint inversion with the additional P-to-S data.
Predicting the surface wall pressure frequency spectra of submerged cylindrical bodies
Authors: Hwang Y. F. , Bonness W. K. , Hambric S. A.
Published: March 2004

This paper addresses the modeling of structural excitations caused by low speed turbulent boundary layer flows. When the Corcos-type cross-spectrum or its corresponding wavevector-frequency spectrum is used as the forcing function in a homogeneous turbulent flow, the point frequency spectrum is the common multiplier to the factors representing either the cross-spectral terms or the wavevector terms. The capability of accurately predicting the point frequency spectrum is the premise of obtaining an accurate cross-spectrum or wavevector-frequency spectrum. Several point-frequency spectral models have been evaluated against the measured data obtained from buoyancy propelled cylindrical bodies. It was found that predictions using the most recently published point-frequency spectral models by Smolyakov [Acoust. Phys. 46(3), 342–347; translated from Akusti. Zh. 46(3), 410–407 (2000)] and Goody [AIAA-2002-2565, 8th AIAA/CEAS Aeroacoustics Conference and Exhibit, Breckenridge, CO, (2002)] provide a reasonably good agreement with the measured data. [Work supported by ONR.]
Effects of Mosquito Genes on
Plasmodium
Development
Authors: Osta Mike A. , Christophides George K. , Kafatos Fotis C.
Published: March 2004

Malaria parasites must complete a complex developmental cycle in an
Anopheles
mosquito vector before transmission to a vertebrate host. Sexual development of the parasite in the midgut is initiated in the lumen immediately after the mosquito ingests infected blood, and the resulting ookinetes must traverse the surrounding epithelial layer before transforming into oocysts. The innate immune system of the mosquito is activated during midgut invasion, but to date, no evidence has been published identifying mosquito immune genes that affect parasite development. Here, we show by gene silencing that an
Anopheles gambiae
leucine rich-repeat protein acts as an antagonist and two C-type lectines act as protective agonists on the development of
Plasmodium
ookinetes to oocysts.
Structure-Based Assembly of Protein Complexes in Yeast
Authors: Aloy Patrick , Böttcher Bettina , Ceulemans Hugo , Leutwein Christina , Mellwig Christian , Fischer Susanne , Gavin Anne-Claude , Bork Peer , Superti-Furga Giulio , Serrano Luis , Russell Robert B.
Published: March 2004

Images of entire cells are preceding atomic structures of the separate molecular machines that they contain. The resulting gap in knowledge can be partly bridged by protein-protein interactions, bioinformatics, and electron microscopy. Here we use interactions of known three-dimensional structure to model a large set of yeast complexes, which we also screen by electron microscopy. For 54 of 102 complexes, we obtain at least partial models of interacting subunits. For 29, including the exosome, the chaperonin containing TCP-1, a 3′-messenger RNA degradation complex, and RNA polymerase II, the process suggests atomic details not easily seen by homology, involving the combination of two or more known structures. We also consider interactions between complexes (cross-talk) and use these to construct a structure-based network of molecular machines in the cell.
Envelope-Constrained Neutralization-Sensitive HIV-1 After Heterosexual Transmission
Authors: Derdeyn Cynthia A. , Decker Julie M. , Bibollet-Ruche Frederic , Mokili John L. , Muldoon Mark , Denham Scott A. , Heil Marintha L. , Kasolo Francis , Musonda Rosemary , Hahn Beatrice H. , Shaw George M. , Korber Bette T. , Allen Susan , Hunter Eric
Published: March 2004

Heterosexual transmission accounts for the majority of human immunodeficiency virus–1 (HIV-1) infections worldwide, yet the viral properties that determine transmission fitness or outgrowth have not been elucidated. Here we show, for eight heterosexual transmission pairs, that recipient viruses were monophyletic, encoding compact, glycan-restricted envelope glycoproteins. These viruses were also uniquely sensitive to neutralization by antibody from the transmitting partner. Thus, the exposure of neutralizing epitopes, which are lost in chronic infection because of immune escape, appears to be favored in the newly infected host. This reveals characteristics of the envelope glycoprotein that influence HIV-1 transmission and may have implications for vaccine design.
Atomic-Resolution Measurement of Oxygen Concentration in Oxide Materials
Authors: Jia C. L. , Urban K.
Published: March 2004

Using high-resolution imaging at negative spherical aberration of the objective lens in an aberration-corrected transmission electron microscope, we measure the concentration of oxygen in Σ3{111} twin boundaries in BaTiO
3
thin films at atomic resolution. On average, 68% of the boundary oxygen sites are occupied, and the others are left vacant. The modified Ti
2
O
9
group unit thus formed reduces the grain boundary energy and provides a way of accommodating oxygen vacancies occurring in oxygen-deficient material by the formation of a nanotwin lamellae structure. The atomically resolved measurement technique offers the potential for studies on oxide materials in which the electronic properties sensitively depend on the local oxygen content.
Quantum Optimally Controlled Transition Landscapes
Authors: Rabitz Herschel A. , Hsieh Michael M. , Rosenthal Carey M.
Published: March 2004

A large number of experimental studies and simulations show that it is surprisingly easy to find excellent quality control over broad classes of quantum systems. We now prove that for controllable quantum systems with no constraints placed on the controls, the only allowed extrema of the transition probability landscape correspond to perfect control or no control. Under these conditions, no suboptimal local extrema exist as traps that would impede the search for an optimal control. The identified landscape structure is universal for all controllable quantum systems of the same dimension when seeking to maximize the same transition probability, regardless of the detailed nature of the system Hamiltonian. The presence of weak control field noise or environmental decoherence is shown to preserve the general structure of the control landscape, but at lower resolution.
Actin Polymerization-Driven Molecular Movement of mDia1 in Living Cells
Authors: Higashida Chiharu , Miyoshi Takushi , Fujita Akiko , Oceguera-Yanez Fabian , Monypenny James , Andou Yoshikazu , Narumiya Shuh , Watanabe Naoki
Published: March 2004

mDia1, a Rho effector, belongs to the Formin family of proteins, which shares the conserved tandem FH1-FH2 unit structure. Formins including mDia1 accelerate actin nucleation while interacting with actin filament fast-growing ends. Here our single-molecule imaging revealed fast directional movement of mDia1 FH1-FH2 for tens of microns in living cells. The movement of mDia1 FH1-FH2 was blocked by actin-perturbing drugs, and the speed of mDia1 FH1-FH2 movement appeared to correlate with actin elongation rates. In vitro, mDia1 FH1-FH2 associated persistently with the growing actin barbed end. mDia1 probably moves processively along the growing end of actin filaments in cells, and Formins may be a molecular motility machinery that is independent from motor proteins.
The Structural Organization of the Readily Releasable Pool of Synaptic Vesicles
Authors: Rizzoli Silvio O. , Betz William J.
Published: March 2004

The defining morphological feature of chemical synapses is the vesicle cluster in the presynaptic nerve terminal. It has generally been assumed that vesicles closest to release sites are recruited first during nerve activity. We tested this by selectively labeling the “readily releasable” pool, those vesicles released first during physiological stimulation. The readily releasable vesicles were not clustered close to the presynaptic membrane but instead were dispersed almost randomly throughout the vesicle cluster. Thus, vesicles are not recruited according to proximity to release sites but are mobilized differently, perhaps by being peeled from the surface of the cluster.
Visions of the Milky Way
Authors: Bignami Giovanni F.
Published: March 2004

Via Lactea
. by Francesco Bertola. Biblos, Cittadella, Italy, 2003. 215 pp. €39.95. ISBN 88-88064-22-2.

Bertola's survey of the art, legend, and science of the Milky Way features 60 depictions of the celestial arc from the past two millennia.
Mental illness in people who kill strangers: longitudinal study and national clinical survey
Authors: Shaw Jenny , Amos Tim , Hunt Isabelle M , Flynn Sandra , Turnbull Pauline , Kapur Navneet , Appleby Louis
Published: March 2004

Objectives To establish changes over time in the frequency of homicides committed by strangers, and to describe the personal and clinical characteristics of perpetrators of stranger homicides.

Design Longitudinal study and national clinical survey.

Participants People convicted of homicide in England and Wales between 1996 and 1999 and whether the victim was known to the perpetrator.

Setting England and Wales.

Main outcome measure Characteristics of perpetrators of homicides according to whether victims were strangers or not.

Results Stranger homicides increased between 1967 and 1997, both in number and as a proportion of all homicides. No increase was found, however, in the number of perpetrators placed under a hospital order after homicide, whether all homicides or stranger homicides only. 358 of 1594 (22%) homicides were stranger homicides. In these cases the perpetrator was more likely to be male and young. The method of killing was more likely to be by hitting, kicking, or pushing (36% (130 of 358) for victims who were strangers to the perpetrator compared with 14% (145 of 1074) for victims who were known). Perpetrators were less likely to have a history of mental disorder (34%, n = 80 ν 50%, n = 142), a history of contact with mental health services (16%, 37 of 234 ν 24%, 200 of 824), and psychiatric symptoms at the time of the offence (6%, n = 14 ν 18%, n = 143). They were more likely to have a history of drug misuse (47%, n = 93 ν 37%, n = 272); alcohol (56%, n = 94 ν 41%, n = 285) or drugs (24% n = 44 ν 12%, n = 86) were more likely to have contributed to the offence.

Conclusions Stranger homicides have increased, but the increase is not the result of homicides by mentally ill people and therefore the “care in the community” policy. Stranger homicides are more likely to be related to alcohol or drug misuse by young men.
A NOTE ON SPECTRAL ZETA FUNCTIONS OF QUANTUM GROUPS
Authors: KUROKAWA NOBUSHIGE , WAKAYAMA MASATO
Published: March 2004

We study analytic properties of spectral zeta functions associated to actions of the quantum group SUq(2) such as Z(s, SUq(2)), the zeta function corresponding to the regular representation introduced in [15]. As an application, we show the special value ζ(3) of the Riemann zeta function ζ(s) is given in terms of the classical limit of Z(s, SUq(2)). We further discuss a spectral zeta function [Formula: see text] associated with the so-called model of the representations of [Formula: see text] and show a presence of its series of "trivial" zeros, which is noteworthy.
SYMPLECTIC STABILITY, ANALYTIC STABILITY IN NON-ALGEBRAIC COMPLEX GEOMETRY
Authors: TELEMAN ANDREI
Published: March 2004

We give a systematic presentation of the stability theory in the non-algebraic Kählerian geometry. We introduce the concept of "energy complete Hamiltonian action". To an energy complete Hamiltonian action of a reductive group G on a complex manifold one can associate a G-equivariant maximal weight function and prove a Hilbert criterion for semistability. In other words, for such actions, the symplectic semistability and analytic semistability conditions are equivalent.
TOWER PROBLEM ON FINITE ÉTALE COVERINGS OF SMOOTH PROJECTIVE 3-FOLDS
Authors: FUJIMOTO YOSHIO
Published: March 2004

Let {fn: Xn→Xn+1}n=1,2,… be an infinite tower of nonisomorphic finite étale coverings between smooth projective 3-folds Xn's with κ(Xn)=2. Then, for each n, a suitable finite étale covering [Formula: see text] of Xn is isomorphic to the direct product of a smooth algebraic surface Sn of general type and an elliptic curve En, which is mutually isogeneous to each other.
A CONVEX SUBMODEL WITH APPLICATION TO SYSTEM DESIGN
Authors: SALMERÓN JAVIER , MARÍN ÁNGEL
Published: March 2004

In this paper, we present an algorithm to solve a particular convex model explicitly. The model may massively arise when, for example, Benders decomposition or Lagrangean relaxation-decomposition is applied to solve large design problems in facility location and capacity expansion. To attain the optimal solution of the model, we analyze its Karush–Kuhn–Tucker optimality conditions and develop a constructive algorithm that provides the optimal primal and dual solutions. This approach yields better performance than other convex optimization techniques.
POSITIVE SENSITIVITY ANALYSIS IN LINEAR PROGRAMMING
Authors: PARK CHAN-KYOO , KIM WOO-JE , LEE SANGWOOK , PARK SOONDAL
Published: March 2004

Positive sensitivity analysis (PSA) is a sensitivity analysis method for linear programming that finds the range of perturbations within which positive value components of a given optimal solution remain positive. Its main advantage is that it is applicable to both an optimal basic and nonbasic optimal solution.

The first purpose of this paper is to present some properties of PSA that are useful for establishing the relationship between PSA and sensitivity analysis using optimal bases, and between PSA and sensitivity analysis using the optimal partition. We examine how the range of PSA varies according to the optimal solution used for PSA, and discuss the relationship between the ranges of PSA using different optimal solutions. The second purpose is to clarify the relationship between PSA and sensitivity analysis using an optimal basis, and the relationship between PSA and sensitivity analysis using the optimal partition. We show that sensitivity analysis using the optimal partition is a special case of PSA, and its properties can be derived from the properties of PSA. The comparison among the three sensitivity analysis methods will lead to a better understanding of the difference among sensitivity analysis methods.
METAHEURISTICS FOR THE MIXED SHOP SCHEDULING PROBLEM
Authors: LIU S. Q. , ONG H. L.
Published: March 2004

In this paper, three metaheuristics are proposed for solving a class of job shop, open shop, and mixed shop scheduling problems. We evaluate the performance of the proposed algorithms by means of a set of Lawrence's benchmark instances for the job shop problem, a set of randomly generated instances for the open shop problem, and a combined job shop and open shop test data for the mixed shop problem. The computational results show that the proposed algorithms perform extremely well on all these three types of shop scheduling problems. The results also reveal that the mixed shop problem is relatively easier to solve than the job shop problem due to the fact that the scheduling procedure becomes more flexible by the inclusion of more open shop jobs in the mixed shop.
A POSTERIOR COMPETITIVENESS FOR LIST SCHEDULING ALGORITHM ON MACHINES WITH ELIGIBILITY CONSTRAINTS
Authors: HWANG HARK-CHIN , CHANG SOO Y. , HONG YUSHIN
Published: March 2004

We consider the on-line problem of scheduling n independent jobs on m identical machines under the machine eligibility constraints, where each job has its own specified subset of machines which are eligible for processing it. We investigate a greedy algorithm LS and prove its posterior competitiveness ratio is [Formula: see text], where λ is the number of machines eligible for processing the job with the latest completion time.
A METHOD FOR GENERATING ALL THE EFFICIENT SOLUTIONS OF A 0-1 MULTI-OBJECTIVE LINEAR PROGRAMMING PROBLEM
Authors: JAHANSHAHLOO G. R. , LOTFI F. HOSSEINZADEH , SHOJA N. , TOHIDI G.
Published: March 2004

In this paper, a method using the concept of l1-norm is proposed to find all the efficient solutions of a 0-1 Multi-Objective Linear Programming (MOLP) problem. These solutions are specified without generating all feasible solutions. Corresponding to a feasible solution of a 0-1 MOLP problem, a vector is constructed, the components of which are the values of objective functions. The method consists of a one-stage algorithm. In each iteration of this algorithm a 0-1 single objective linear programming problem is solved. We have proved that optimal solutions of this 0-1 single objective linear programming problem are efficient solutions of the 0-1 MOLP problem. Corresponding to efficient solutions which are obtained in an iteration, some constraints are added to the 0-1 single objective linear programming problem of the next iteration. Using a theorem we guarantee that the proposed algorithm generates all the efficient solutions of the 0-1 MOLP problem. Numerical results are presented for an example taken from the literature to illustrate the proposed algorithm.
Basic Mechanisms of Cardiac Impulse Propagation and Associated Arrhythmias
Authors: KLÉBER ANDRÉ G. , RUDY YORAM
Published: March 2004

Kléber, André G., and Yoram Rudy. Basic Mechanisms of Cardiac Impulse Propagation and Associated Arrhythmias. Physiol Rev 84: 431–488, 2004; 10.1152/physrev.00025.2003.—Propagation of excitation in the heart involves action potential (AP) generation by cardiac cells and its propagation in the multicellular tissue. AP conduction is the outcome of complex interactions between cellular electrical activity, electrical cell-to-cell communication, and the cardiac tissue structure. As shown in this review, strong interactions occur among these determinants of electrical impulse propagation. A special form of conduction that underlies many cardiac arrhythmias involves circulating excitation. In this situation, the curvature of the propagating excitation wavefront and the interaction of the wavefront with the repolarization tail of the preceding wave are additional important determinants of impulse propagation. This review attempts to synthesize results from computer simulations and experimental preparations to define mechanisms and biophysical principles that govern normal and abnormal conduction in the heart.
Protease-Activated Receptors: Contribution to Physiology and Disease
Authors: OSSOVSKAYA VALERIA S. , BUNNETT NIGEL W.
Published: March 2004

Ossovskaya, Valeria S., and Nigel W. Bunnett. Protease-Activated Receptors: Contribution to Physiology and Disease. Physiol Rev 84: 579–621, 2004; 10.1152/physrev.00028.2003.—Proteases acting at the surface of cells generate and destroy receptor agonists and activate and inactivate receptors, thereby making a vitally important contribution to signal transduction. Certain serine proteases that derive from the circulation (e.g., coagulation factors), inflammatory cells (e.g., mast cell and neutrophil proteases), and from multiple other sources (e.g., epithelial cells, neurons, bacteria, fungi) can cleave protease-activated receptors (PARs), a family of four G protein-coupled receptors. Cleavage within the extracellular amino terminus exposes a tethered ligand domain, which binds to and activates the receptors to initiate multiple signaling cascades. Despite this irreversible mechanism of activation, signaling by PARs is efficiently terminated by receptor desensitization (receptor phosphorylation and uncoupling from G proteins) and downregulation (receptor degradation by cell-surface and lysosomal proteases). Protease signaling in tissues depends on the generation and release of proteases, availability of cofactors, presence of protease inhibitors, and activation and inactivation of PARs. Many proteases that activate PARs are produced during tissue damage, and PARs make important contributions to tissue responses to injury, including hemostasis, repair, cell survival, inflammation, and pain. Drugs that mimic or interfere with these processes are attractive therapies: selective agonists of PARs may facilitatehealing, repair, and protection, whereas protease inhibitors and PAR antagonists can impede exacerbated inflammation and pain. Major future challenges will be to understand the role of proteases and PARs in physiological control mechanisms and human diseases and to develop selective agonists and antagonists that can be used to probe function and treat disease.
Neural Processing of Amplitude-Modulated Sounds
Authors: JORIS P. X. , SCHREINER C. E. , REES A.
Published: March 2004

Joris, P. X., C. E. Schreiner, and A. Rees. Neural Processing of Amplitude-Modulated Sounds. Physiol Rev 84: 541–577, 2004; 10.1152/physrev.00029.2003.—Amplitude modulation (AM) is a temporal feature of most natural acoustic signals. A long psychophysical tradition has shown that AM is important in a variety of perceptual tasks, over a range of time scales. Technical possibilities in stimulus synthesis have reinvigorated this field and brought the modulation dimension back into focus. We address the question whether specialized neural mechanisms exist to extract AM information, and thus whether consideration of the modulation domain is essential in understanding the neural architecture of the auditory system. The available evidence suggests that this is the case. Peripheral neural structures not only transmit envelope information in the form of neural activity synchronized to the modulation waveform but are often tuned so that they only respond over a limited range of modulation frequencies. Ascendingthe auditory neuraxis, AM tuning persists but increasingly takes the form of tuning in average firing rate, rather than synchronization, to modulation frequency. There is a decrease in the highest modulation frequencies that influence the neural response, either in average rate or synchronization, as one records at higher and higher levels along the neuraxis. In parallel, there is an increasing tolerance of modulation tuning for other stimulus parameters such as sound pressure level, modulation depth, and type of carrier. At several anatomical levels, consideration of modulation response properties assists the prediction of neural responses to complex natural stimuli. Finally, some evidence exists for a topographic ordering of neurons according to modulation tuning. The picture that emerges is that temporal modulations are a critical stimulus attribute that assists us in the detection, discrimination, identification, parsing, and localization of acoustic sources and that this wide-ranging role is reflected in dedicated physiological properties at different anatomical levels.
Mouse Models of Insulin Resistance
Authors: NANDI ANINDITA , KITAMURA YUKARI , KAHN C. RONALD , ACCILI DOMENICO
Published: March 2004

Nandi, Anindita, Yukari Kitamura, C. Ronald Kahn, and Domenico Accili. Mouse Models of Insulin Resistance. Physiol Rev 84: 623–647, 2004; 10.1152/physrev.00032.2003.—Insulin resistance plays a key role in the pathogenesis of several human diseases, including diabetes, obesity, hypertension, and cardiovascular diseases. The predisposi-tion to insulin resistance results from genetic and environmental factors. The search for gene variants that predispose to insulin resistance has been thwarted by its genetically heterogeneous pathogenesis. However, using techniques of targeted mutagenesis and transgenesis in rodents, investigators have developed mouse models to test critical hypotheses on the pathogenesis of insulin resistance. Moreover, experimental crosses among mutant mice have shed light onto the polygenic nature of the interactions underlying this complex metabolic condition.
VELVET: An Adaptive Hybrid Architecture for Very Large Virtual Environments
Authors: Oliveira Jauvane C. de , Georganas Nicolas D.
Published: March 2004

Collaborative virtual environment (CVE) concepts have been used in many systems in the past few years. Applications of such technology range from military combat simulations to various civilian commercial applications. The architectures available today provide support for a number of users, but they fail if too many users are together in a small “space” in the virtual world. This paper introduces VELVET, an adaptive hybrid architecture that allows a greater number of users to interact through a CVE. This is accomplished through an adaptive filtering scheme based on multicasting. VELVET also supports small groups of users, but its use in large environments shows the greatest potential, better handling local concentrations of activity than region-, cell-, orlocale-based approaches. VELVET introduces a novel adaptive area of interest management that supports heterogeneity amongst the various participants. This allows users in a supercomputer with high-speed networking to successfully collaborate with others in not-so-powerful systems behind a slow dial-up connection.
Can We Sell a Virtual Object in a Virtual Society? (E-commerce Evaluations in PAW^2, A Personal Agent-Oriented Virtual Society
Authors: Matsuda Kouichi
Published: March 2004

In view of the latest developments in computer and network technology, research organizations and companies have proposed several distributed systems that realize a 3D multiuser virtual shared environment. Within that framework, we have developed PAW^2 (Personal Agent World), a personal agent-oriented virtual society that built upon the avatar-and-text-communication Community Place system and exposed it to the Internet. PAW^2 is a virtual society that improves upon existing virtual environments by providing autonomous personal agents that interact with users in a virtual environment with a social infrastructure. It is publicly accessible on the Internet.

In this paper, we report and discuss the results of e-commerce evaluations of the use of PAW^2 on the Internet. The underlying hypothesis for these evaluations was that defining the value of a virtual object in a virtual society makes it possible for that object to be sold for money like real goods. The evaluation consisted of selling a virtual item to approximately eighty thousand registered PAW^2 users over a period of approximately two months. The results of the evaluations showed that, in a virtual society, a virtual object that adds functions to a personal agent and can be used as an avatar accessory can be sold like real goods.
Effects of Handling Real Objects and Self-Avatar Fidelity on Cognitive Task Performance and Sense of Presence in Virtual Environments
Authors: Lok Benjamin , Naik Samir , Whitton Mary , Brooks Frederick P.
Published: March 2004

Immersive virtual environments (VEs) provide participants with computer-generated environments filled with virtual objects to assist in learning, training, and practicing dangerous and/or expensive tasks. But does having every object being virtual inhibit the interactivity and level of immersion? If participants spend most of their time and cognitive load on learning and adapting to interacting with virtual objects, does this reduce the effectiveness of the VE?

We conducted a study that investigated how handling real objects and self-avatar visual fidelity affects performance and sense of presence on a spatial cognitive manual task. We compared participants' performance of a block arrangement task in both a real-space environment and several virtual and hybrid environments. The results showed that manipulating real objects in a VE brings task performance closer to that of real space, compared to manipulating virtual objects. There was no signifi-cant difference in reported sense of presence, regardless of the self-avatar's visual fidelity or the presence of real objects.
Embodiment and Spatial Behavior in Virtual Environments: Comments on Durlach et al. (2000)
Authors: Arnold Paul , Farrell Martin J.
Published: March 2004

Durlach et al. (2000) outlined a research program for the use of virtual environments (VEs) to train spatial abilities, and have invited comments. Our perspective is that some of the problems facing researchers in VE navigation, and also perceptual-motor skills, stem from the possibility that psychological processes that underlie navigation and motor skills in real and in virtual environments may be somewhat different. VE users may then have to make use of different strategies and abilities to those that they would normally use to manually manipulate and to navigate around the world. We suggest that such differences may arise because, when performing VE motor skills and navigation, the subject is effectively disembodied.
Force modelling of the crankshaft pin grinding process
Authors: Walsh A P , Baliga B , Hodgson P D
Published: March 2004

A force model was developed for crankshaft pin grinding to predict the forces generated during grinding. The force model developed builds on the authors' previously developed model, which predicted the out-of-roundness in crankshaft pin grinding. The model includes key grinding variables, such as the work removal parameter (WRP), system stiffness and Young's modulus to determine the end forces produced. The model also includes the important geometrical relationships that are unique to this type of grinding. The model was verified using an experiential set-up involving sophisticated strain gauge force measurements on a commercial Landis CP grinding machine, with close correlation between the results and the model.
Flowrate and heat transfer considerations for oxidation catalysts
Authors: McCullough G , Douglas R , Spence S , Cunningham G
Published: March 2004

This paper presents the results of a study into the effects of flowrate and heat transfer in oxidation catalysts. The analysis was performed using a validated two-dimensional catalyst model, which has been designed to predict the behaviour of an oxidation catalyst during transient warm-up and light-off conditions. It is only during the simulation of transient conditions that the true effects of changes to the flowrate and heat loss to the substrate and surrounding materials can be observed. In addition, the two-dimensional design of the model used allows the reaction intensities to be viewed throughout the catalyst and gives the opportunity to examine these effects in both the radial and axial directions.

The study has shown that the heat loss from the upstream section of exhaust pipe not only reduces the rate of increase of the feed gas temperature but also removes heat from the outer edges of the catalyst and delays the onset of reactions in these areas. Consequently, the importance of insulating the upstream exhaust pipe and the catalyst housing is demonstrated.

It is also shown that increasing the thermal conductivity of the substrate reduces the light-off temperature by transporting heat to the cooler regions more rapidly. Increasing the void fraction of the substrate also has a signiflcant effect on the light-off temperature as less heat is absorbed from the feed gas. Finally, it is shown that increasing the flowrate, or space velocity, of the gas increases the resulting light-off temperature. For the conditions simulated, it was seen that increasing the flowrate by one order of magnitude increased the light-off temperature by only 13 °C. However, emissions breakthrough was seen to occur at a space velocity around 164 000 h 1.