bluuebunny/crossref_metadata_2025 huggingface dataset:
Haro Strait geometry (flat bottom)
Authors: Tolstoy A.
Published: March 2006

This paper presents results which relate to the geometry of various examined Haro Strait scenarios. In particular, for each data scenario the source range, source depth, individual phone ranges, individual phone depths, and an average water depth may be determined based on the time domain signals alone. The time differences for each phone for (1) surface reflected minus direct arrivals, and (2) bottom reflected minus direct arrivals are used to estimate potential positions from elementary geometric considerations [similar to Michalopoulou, and Ma (unpublished)]. Nonuniqueness is still a nasty issue and is examined here. However, additional constraints on each scenario to guarantee realism, e.g., the array must be quasivertical with phones 6.25m apart with no extreme snaking of the array, sources can only be within certain ranges and depths, the top array phone depth and average water depths can only be within certain regimes, etc., eliminate many false solutions. Finally and convincingly, some of the optimal positions are “confirmed” by simulating the signals for the predicted geometries by means of a pulse PE (ramgeo) propagation code (courtesy of M. Collins) and then comparing those simulated signals with the observed data. Once the scenario geometry has been estimated, proper geoacoustic inversion for bottom properties can proceed via the SUB-RIGS method [Tolstoy, IEEE J. Ocean. Eng. 29, 59–77 (2004(b))]. These subsequent inversions will be discussed in a follow-up paper.
The relative roles of vowels and consonants in discriminating talker identity versus word meaning
Authors: Owren Michael J. , Cardillo Gina C.
Published: March 2006

Three experiments tested the hypothesis that vowels play a disproportionate role in hearing talker identity, while consonants are more important in perceiving word meaning. In each study, listeners heard 128 stimuli consisting of two different words. Stimuli were balanced for same/different meaning, same/different talker, and male/female talker. The first word in each was intact, while the second was either intact (Experiment 1), or had vowels (“Consonants-Only”) or consonants (“Vowels-Only”) replaced by silence (Experiments 2, 3). Different listeners performed a same/different judgment of either talker identity (Talker) or word meaning (Meaning). Baseline testing in Experiment 1 showed above-chance performance in both, with greater accuracy for Meaning. In Experiment 2, Talker identity was more accurately judged from Vowels-Only stimuli, with modestly better overall Meaning performance with Consonants-Only stimuli. However, performance with vowel-initial Vowels-Only stimuli in particular was most accurate of all. Editing Vowels-Only stimuli further in Experiment 3 had no effect on Talker discrimination, while dramatically reducing accuracy in the Meaning condition, including both vowel-initial and consonant-initial Vowels-Only stimuli. Overall, results confirmed a priori predictions, but are largely inconsistent with recent tests of vowels and consonants in sentence comprehension. These discrepancies and possible implications for the evolutionary origins of speech are discussed.
The effects of hearing loss on the contribution of high- and low-frequency speech information to speech understanding. II. Sloping hearing loss
Authors: Hornsby Benjamin W. Y. , Ricketts Todd A.
Published: March 2006

The speech understanding of persons with sloping high-frequency (HF) hearing impairment (HI) was compared to normal hearing (NH) controls and previous research on persons with “flat” losses [Hornsby and Ricketts (2003). J. Acoust. Soc. Am. 113, 1706–1717] to examine how hearing loss configuration affects the contribution of speech information in various frequency regions. Speech understanding was assessed at multiple low- and high-pass filter cutoff frequencies. Crossover frequencies, defined as the cutoff frequencies at which low- and high-pass filtering yielded equivalent performance, were significantly lower for the sloping HI, compared to NH, group suggesting that HF HI limits the utility of HF speech information. Speech intelligibility index calculations suggest this limited utility was not due simply to reduced audibility but also to the negative effects of high presentation levels and a poorer-than-normal use of speech information in the frequency region with the greatest hearing loss (the HF regions). This deficit was comparable, however, to that seen in low-frequency regions of persons with similar HF thresholds and “flat” hearing losses suggesting that sensorineural HI results in a “uniform,” rather than frequency-specific, deficit in speech understanding, at least for persons with HF thresholds up to 60–80dB HL.
Release from speech-on-speech masking by adding a delayed masker at a different location
Authors: Rakerd Brad , Aaronson Neil L. , Hartmann William M.
Published: March 2006

The amount of masking exerted by one speech sound on another can be reduced by presenting the masker twice, from two different locations in the horizontal plane, with one of the presentations delayed to simulate an acoustical reflection. Three experiments were conducted on various aspects of this phenomenon. Experiment 1 varied the number of masking talkers from one to three and the signal-to-noise (S∕N) ratio from −12to+4dB. Evidence of masking release was found for every combination of these variables tested. For the most difficult conditions (multiple maskers and negative S∕N) the amount of release was approximately 10dB. Experiment 2 varied the timing of leading and lagging masker presentations over a broad range, to include shorter delay times where room reflections of speech are rarely noticed by listeners and longer delays where reflections can become disruptive. Substantial masking release was found for all of the shorter delay times tested, and negligible release was found at the longer delays. Finally, Experiment 3 used speech-spectrum noise as a masker and searched for possible energetic masking release as a function of the lead-lag time delay. Release of up to 4dB was found whenever delays were 2ms or less. No energetic masking release was found at longer delays.
Stability analysis of active control of self-sustained pressure fluctuations due to flow over a cavity
Authors: Micheau P. , Chatellier Ludovic , Laumonier Janick , Gervais Yves
Published: March 2006

The problem addressed in this paper is the stability analysis of self-sustained pressure fluctuations due to low Mach number turbulent flow over a large shallow cavity in a wing-shaped model. In the studied configuration, sound pressure was generated by the instability of the mixing layer. An original active device, a vibrating surface located at the trailing edge, and an adjustable narrow-band controller were used to control the self-oscillation: to amplify it in an open loop, and to attenuate it in a closed loop. A complete analysis of the system based on the describing function analysis is presented. Experimental data, obtained in an Eiffel-type wind-tunnel compare favorably with the prediction of the model. With the active control, the instability is controlled: the pressure fluctuations measured in the cavity are attenuated to the ground level. Moreover, with the proposed model and the original device, the equivalent volume velocity of the unstable mixing layer and the acoustic feedback gain can be experimentally estimated.
Information entropy of humpback whale songs
Authors: Suzuki Ryuji , Buck John R. , Tyack Peter L.
Published: March 2006

The structure of humpback whale (Megaptera novaeangliae) songs was examined using information theory techniques. The song is an ordered sequence of individual sound elements separated by gaps of silence. Song samples were converted into sequences of discrete symbols by both human and automated classifiers. This paper analyzes the song structure in these symbol sequences using information entropy estimators and autocorrelation estimators. Both parametric and nonparametric entropy estimators are applied to the symbol sequences representing the songs. The results provide quantitative evidence consistent with the hierarchical structure proposed for these songs by Payne and McVay [Science 173, 587–597 (1971)]. Specifically, this analysis demonstrates that: (1) There is a strong structural constraint, or syntax, in the generation of the songs, and (2) the structural constraints exhibit periodicities with periods of 6–8 and 180–400 units. This implies that no empirical Markov model is capable of representing the songs’ structure. The results are robust to the choice of either human or automated song-to-symbol classifiers. In addition, the entropy estimates indicate that the maximum amount of information that could be communicated by the sequence of sounds made is less than 1bitpersecond.
A review of finite-element methods for time-harmonic acoustics
Authors: Thompson Lonny L.
Published: March 2006

State-of-the-art finite-element methods for time-harmonic acoustics governed by the Helmholtz equation are reviewed. Four major current challenges in the field are specifically addressed: the effective treatment of acoustic scattering in unbounded domains, including local and nonlocal absorbing boundary conditions, infinite elements, and absorbing layers; numerical dispersion errors that arise in the approximation of short unresolved waves, polluting resolved scales, and requiring a large computational effort; efficient algebraic equation solving methods for the resulting complex-symmetric (non-Hermitian) matrix systems including sparse iterative and domain decomposition methods; and a posteriori error estimates for the Helmholtz operator required for adaptive methods. Mesh resolution to control phase error and bound dispersion or pollution errors measured in global norms for large wave numbers in finite-element methods are described. Stabilized, multiscale, and other wave-based discretization methods developed to reduce this error are reviewed. A review of finite-element methods for acoustic inverse problems and shape optimization is also given.
A comparison of adaptive procedures for rapid and reliable threshold assessment and training in naive listeners
Authors: Amitay Sygal , Irwin Amy , Hawkey David J. C. , Cowan Justin A. , Moore David R.
Published: March 2006

In psychoacoustic studies there is often a need to assess performance indices quickly and reliably. The aim of this study was to establish a quick and reliable procedure for evaluating thresholds in backward masking and frequency discrimination tasks. Based on simulations, four procedures likely to produce the best results were selected, and data collected from 20 naive adult listeners on each. Each procedure used one of two adaptive methods (staircase or maximum-likelihood estimation, each targeting the 79% correct point on the psychometric function) and two response paradigms (3-interval, 2-alternative forced-choice AXB or 3-interval; 3-alternative forced-choice oddball). All procedures yielded statistically equivalent threshold estimates in both backward masking and frequency discrimination, with a trend to lower thresholds for oddball procedures in frequency discrimination. Oddball procedures were both more efficient and more reliable (test–retest) in backward masking, but all four procedures were equally efficient and reliable in frequency discrimination. Fitted psychometric functions yielded similar thresholds to averaging over reversals in staircase procedures. Learning was observed across threshold-assessment blocks and experimental sessions. In four additional groups, each of ten listeners, trained on the different procedures, no differences in performance improvement or rate of learning were observed, suggesting that learning is independent of procedure.
Interferometric studies of a piano soundboard
Authors: Moore Thomas R. , Zietlow Sarah A.
Published: March 2006

Electronic speckle pattern interferometry has been used to study the deflection shapes of a piano soundboard. A design for an interferometer that can image such an unstable object is introduced, and interferograms of a piano soundboard obtained using this interferometer are presented. Deflection shapes are analyzed and compared to a finite-element model, and it is shown that the force the strings exert on the soundboard is important in determining the mode shapes and resonant frequencies. Measurements of resonance frequencies and driving-point impedance made using the interferometer are also presented.
Dispersive surface waves along partially saturated porous media
Authors: Chao Gabriel , Smeulders D. M. J. , van Dongen M. E. H.
Published: March 2006

Numerical results for the velocity and attenuation of surface wave modes in fully permeable liquid/partially saturated porous solid plane interfaces are reported in a broadband of frequencies (100Hz–1MHz). A modified Biot theory of poromechanics is implemented which takes into account the interaction between the gas bubbles and both the liquid and the solid phases of the porous material through acoustic radiation and viscous and thermal dissipation. This model was previously verified by shock wave experiments. In the present paper this formulation is extended to account for grain compressibility. The dependence of the frequency-dependent velocities and attenuation coefficients of the surface modes on the gas saturation is studied. The results show a significant dependence of the velocities and attenuation of the pseudo-Stoneley wave and the pseudo-Rayleigh wave on the liquid saturation in the pores. Maximum values in the attenuation coefficient of the pseudo-Stoneley wave are obtained in the 10–20kHz range of frequencies. The attenuation value and the characteristic frequency of this maximum depend on the liquid saturation. In the high-frequency limit, a transition is found between the pseudo-Stoneley wave and a true Stoneley mode. This transition occurs at a typical saturation below which the slow compressional wave propagates faster than the pseudo-Stoneley wave.
Relationship between Nusselt number and the thermoviscous (Rott) functions
Authors: Liu Jin , Garrett Steven L.
Published: March 2006

The characterization of the thermal properties of regenerator materials has traditionally been studied by measurement of the heat transport of a gas passing through a regenerator flanked by two heat exchangers. The results for heat transfer between the gas and regenerator are typically expressed as a nondimensional Nusselt number. The newer thermoacoustic perspective, developed over the past two decades by Swift and his collaborators, has characterized the thermal properties of regenerators through the thermoviscous function used by Rott in the 1960s. This paper derives the relation between those two perspectives. The complex Nusselt number for oscillatory flow is calculated in terms of the thermoviscous f function. The asymptomatic results of the real part of the complex Nusselt number at zero frequency converge to the steady (direct current) result and at high frequency it matched qualitatively with the limit derived by other researchers interested in the behavior of heat exchangers used in oscillating flows.
Three-dimensional underwater sound pressure field due to sonic boom
Authors: Moody Douglas M.
Published: March 2006

Over 35years ago, a theory was developed by Sawyers [K. N. Sawyers, J. Acoust. Soc. Am. 44, 523–524 (1968)] to predict the underwater sound pressure field due to loading of the water surface with an idealized sonic boom. In Sawyers’ theory, the sonic-boom N wave was taken to be uniform and of infinite extent in the cross-track direction, i.e., the horizontal direction perpendicular to the direction of motion. The resulting prediction is thus two-dimensional, depending only on the in-track position and the depth into the water. The current paper presents a generalization of Sawyers’ theory from two to three spatial dimensions. Three sample problems are solved, with one of the results showing that the three-dimensional method correctly reproduces Sawyers’ two-dimensional results when the surface disturbance is uniform in crosstrack. Results from the final problem provide actual predictions of underwater sound generated by a cruise missile flying at an altitude of 20feet and a speed of 2500ft∕s.
Auditory brainstem response in a harbor porpoise show lack of automatic gain control for simulated echoes
Authors: Beedholm Kristian , Miller Lee A. , Blanchet Marie-Anne
Published: March 2006

The auditory brainstem response (ABR) response to simulated echolocation clicks was studied in a harbor porpoise, Phocoena phocoena, to determine the relationship between the animal’s perceived echo strength and the simulated target distance. In one experiment the click level at the listening post was kept constant while delay was changed, in another, the level was varied to approximate spreading losses. Results of both experiments indicate that there is no automatic gain control in the hearing system of this harbor porpoise.
Low-frequency sound scattering by internal waves in the ocean
Authors: Voronovich Alexander G. , Ostashev Vladimir E.
Published: March 2006

In this paper, long-range propagation of low-frequency sound through an ocean waveguide with random inhomogeneities in the sound speed is studied. Closed equations for the mean field and correlation function of the sound field are derived using the Chernov method. These equations can be considered as a generalization of equations derived by Dozier and Tappert [J. Acoust. Soc. Am. 63, 353–365 (1978)], which accounts for 3D effects and cross-modal correlations. The equations derived in this paper in a general form are similar to the equations obtained by many other authors. However, without simplifications these equations are difficult to solve even numerically due to high dimension of the matrices appearing in the equations. Some simplifications of the equations for the mean field and correlation function are suggested that account for narrowness of the angular spectrum of the scattered acoustic field and which make these equations amenable for numerical implementation. To study solutions of the simplified equations, they are additionally averaged along the sound propagation path. This allows us to obtain some analytical results. Using the theory developed, the horizontal coherence length of the sound field is estimated for the GM spectrum of internal waves.
Effects of auditory feedback on fricatives produced by cochlear-implanted adults and children: Acoustic and perceptual evidence
Authors: Bharadwaj Sneha V. , Tobey Emily A. , Assmann Peter F. , Katz William F.
Published: March 2006

Acoustic analyses and perception experiments were conducted to determine the effects of brief deprivation of auditory feedback on fricatives produced by cochlear implant users. The words /si/ and /ʃi/ were recorded by four children and four adults with their cochlear implant speech processor turned on or off. In the processor-off condition, word durations increased significantly for a majority of talkers. These increases were greater for children compared to adults, suggesting that children may rely on auditory feedback to a greater extent than adults. Significant differences in spectral measures of /ʃ/ were found between processor-on and processor-off conditions for two of the four children and for one of the four adults. These talkers also demonstrated a larger /s/-/ʃ/ contrast in centroid values compared to the other talkers within their respective groups. This finding may indicate that talkers who produce fine spectral distinctions are able to perceive these distinctions through their implants and to use this feedback to fine tune their speech. Two listening experiments provided evidence that some of the acoustic changes were perceptible to normal-hearing listeners. Taken together, these experiments indicate that for certain cochlear-implant users the brief absence of auditory feedback may lead to perceptible modifications in fricative consonants.
Imaging nonlinear scatterers applying the time reversal mirror
Authors: Ulrich T. J. , Johnson P. A. , Sutin A.
Published: March 2006

Nonlinear elastic wave spectroscopy (NEWS) has been shown to exhibit a high degree of sensitivity to both distributed and isolated nonlinear scatterers in solids. In the case of an isolated nonlinear scatterer such as a crack, by combining the elastic energy localization of the time reversal mirror with NEWS, it is shown here that one can isolate surfacial nonlinear scatterers in solids. The experiments presented here are conducted in a doped glass block applying two different fixed frequency time-reversed signals at each focal point and scanning over a localized nonlinear scatterer (a complex crack). The results show a distinct increase in nonlinear response, via intermodulation distortion, over the damaged area. The techniques described herein provide the means to discriminate between linear and nonlinear scatterers, and thus to ultimately image and characterize damaged regions.
Sound attenuation by small spheroidal particles due to visco-inertial coupling
Authors: Babick Frank , Richter Andreas
Published: March 2006

The sound attenuation at ultrasonic frequencies caused by small spheroidal particles in a fluid is examined with regard to the size parameters that determine the shape of the attenuation spectrum. Our investigations are based on a coupled phase model for spheroids with arbitrary orientation, thus facilitating the calculation of average attenuation for a given orientation distribution. Since the model just considers the visco-inertial coupling, its applicability is restricted to small solid particles with high density contrast. The calculated attenuation spectra of mono-sized, randomly aligned spheroidal particles are compared with the attenuation spectra of mono-sized spheres. When the latter approximate the former to a reasonable degree the size of the spheres is called attenuation equivalent diameter. It is shown that the concept of attenuation equivalent diameter can be applied only to slightly elongated prolates. Oblates and very stretched prolates yield considerably broader attenuation spectra than mono-sized spheres. While for oblates and for slightly elongated prolates the characteristic frequency of the attenuation spectrum is determined by the volume specific surface, no such attenuation determining size parameter could be identified for very stretched prolates.
Effects of reverberation and masking on speech intelligibility in cochlear implant simulations
Authors: Poissant Sarah F. , Whitmal Nathaniel A. , Freyman Richard L.
Published: March 2006

Two experiments investigated the impact of reverberation and masking on speech understanding using cochlear implant (CI) simulations. Experiment 1 tested sentence recognition in quiet. Stimuli were processed with reverberation simulation (T=0.425, 0.266, 0.152, and 0.0s) and then either processed with vocoding (6, 12, or 24 channels) or were subjected to no further processing. Reverberation alone had only a small impact on perception when as few as 12 channels of information were available. However, when the processing was limited to 6 channels, perception was extremely vulnerable to the effects of reverberation. In experiment 2, subjects listened to reverberated sentences, through 6- and 12-channel processors, in the presence of either speech-spectrum noise (SSN) or two-talker babble (TTB) at various target-to-masker ratios. The combined impact of reverberation and masking was profound, although there was no interaction between the two effects. This differs from results obtained in subjects listening to unprocessed speech where interactions between reverberation and masking have been shown to exist. A speech transmission index (STI) analysis indicated a reasonably good prediction of speech recognition performance. Unlike previous investigations, the SSN and TTB maskers produced equivalent results, raising questions about the role of informational masking in CI processed speech.
Accurate imaging of the current and temperature structures in coastal oceans by acoustic data assimilation
Authors: Yamamoto Tokuo , Kaneko Arata
Published: March 2006

Both ocean observations and models have limitations. To eliminate the limitations, the idea of data assimilation has been tried in recent years but the results still have been very limited. We have made reciprocal transmissions of 2.5-kHz sound signals along six paths in the Japanese Inland Sea. An extensive ADCP survey was made during this acoustic transmission experiment for the ground truth. The acoustic data were directly inverted for imaging the current and temperature structures. The acoustic data were also assimilated into a Princeton ocean model (POM) using a Kalman filter. The acoustic data assimilation produced very accurate structures of current and temperature, while the direct inversions produced inaccurate and distorted structures. The time interval of data assimilation controls the accuracy of data assimilation technique.
DESIGN CONSIDERATIONS FOR INTEGRATED MODULATOR DRIVERS IN SILICON GERMANIUM TECHNOLOGY
Authors: PAVAN SHANTHI , TARSIA MAURICE , KUDSZUS STEFFEN , PRITZKAU DAVID
Published: March 2006

We present design considerations for high speed high swing differential modulator drivers in SiGe BiCMOS technology. Trade-offs between lumped and distributed designs, and linear and limiting amplifiers are examined. The design of a 6 V output modulator driver is discussed in detail. The driver features a unique bias generation and distribution circuit that enables low power-supply operation. Simulation results and measurements are given.
Compact low-noise pulse generating lasers with repetition rates of 10 to 50 GHz
Authors: Spühler G. J. , Krainer L. , Zeller S. C. , Erny Ch. , Paschotta R. , Weingarten K. J. , Keller U.
Published: March 2006

We review the main results obtained with our recently introduced passively fundamental mode-locked Er : Yb :glass lasers mainly in the context of telecom applications, and we discuss their key enablers. Specifically, we focus on the aspects of the lasers for application in the time-domain for optical time-division multiplexing and in the wavelength domain for dense wavelength-division-multiplexing.
QUANTUM NUMBER PROJECTIONS OF NUCLEAR DEFORMED STATES
Authors: OUDIH M. R. , FELLAH M. , ALLAL N. H. , BENHAMOUDA N.
Published: March 2006

We combine the exact particle-number projection method with the method of Peierls-Yoccoz in order to build the simultaneous eigen-functions of the particle number and the angular momentum operators. In the axial symmetry case, the general expression of the system energy resulting from this double projection is derived. In order to overcome the complexity of the method, the calculations are performed within the Gaussian overlap approximation. It turns out that, on the one hand, the double projection introduces a non–negligible correction of the energy of the system, and on the other hand, this correction is sensitive to the deformation. Future calculations have to therefore include an evaluation of the equilibrium deformation.
CHIRAL SYMMETRY BREAKING AND STABILITY OF QUARK DROPLETS
Authors: YASUI S. , HOSAKA A.
Published: March 2006

We discuss the stability of strangelets — quark droplets with strangeness — in the Nambu–Jona-Lasinio model supplemented by a boundary condition for quark confinement. Effects of dynamical chiral symmetry breaking are considered properly inside quark droplets of arbitrary baryon number. We obtain the energy per baryon number of quark droplets with baryon number from one to thousands. It is shown that strangelets are not the ground states as compared with nuclei, though they can be locally stable.
ON PRODUCTION OF SOME NEUTRAL MESONS IN PION-INDUCED REACTIONS AT HIGH ENERGIES AND AT LARGE TRANSVERSE MOMENTA
Authors: DE BHASKAR , BISWAS S. K. , BHATTACHARYYA S.
Published: March 2006

The measured data on production of π0 and η mesons at large transverse momenta in high energy π-P and π-Be interactions have here been analyzed with the help of a newly-developed phenomenological model, called Combinational Approach(CA). The results so obtained on the basis of the CA are seen to be in fair agreement with the measured data. Furthermore, the results so obtained have been compared with both some previous measuremnts by the same group and some models of the standard variety type, e.g., PYTHIA, HERWIG.
EVAPORATION OF SYMMETRIC NUCLEAR MATTER IN WEAKLY CURVED SPACE
Authors: NAZARENKO A. V.
Published: March 2006

Symmetric nuclear matter, described by the linear Walecka model, is considered in conformally flat space-time. The dependence of the critical parameters of liquid-gas phase transition on magnitude of the conformal step-like factor is investigated.
MAGIC NUMBERS FROM NEW SYSTEMATICS
Authors: BASU CHINMAY
Published: March 2006

A new systematics from the separation energy of deuteron is used to examine the magicity of stable as well as nuclei towards dripline.
ADDING PROBABILITIES AND RULES TO OWL LITE SUBSETS BASED ON PROBABILISTIC DATALOG
Authors: NOTTELMANN HENRIK , FUHR NORBERT
Published: March 2006

This paper proposes two probabilistic extensions of variants of the OWL Lite description language, which are essential for advanced applications like information retrieval. The first step follows the axiomatic approach of combining description logics and Horn clauses: Subsets of OWL Lite are mapped in a sound and complete way onto Horn predicate logics (Datalog variants). Compared to earlier approaches, a larger fraction of OWL Lite can be transformed by switching to Datalog with equality in the head; however, some OWL Lite constructs cannot be transformed completely into Datalog. By using probabilistic Datalog, the new probabilistic OWL Lite subsets (both with support for Horn rules) are defined, and the semantics are given by the semantics of the corresponding probabilistic Datalog program. As inference engines for probabilistic Datalog are available, description logics and information retrieval systems can easily be combined.
UNCERTAINTY OF HUMAN ERROR AND FUZZY APPROACH TO HUMAN RELIABILITY ANALYSIS
Authors: KIM B. J. , BISHU RAM R.
Published: March 2006

Human error is regarded as a critical factor in catastrophic accidents such as disasters at nuclear power plants, air plane crashes, or derailed trains. Several taxonomies for human errors and methodologies for human reliability analysis (HRA) have been proposed in the literature. Generally, human errors have been modeled on the basis of probabilistic concepts with or without the consideration of cognitive aspects of human behaviors. Modeling of human errors through probabilistic approaches has shown a limitation on quantification of qualitative aspects of human errors and complexity of attributes from circumstances involved. The purpose of this paper is to investigate the methodologies for human reliability analysis and introduce a fuzzy logic approach to the evaluation of human interacting system's reliability. Fuzzy approach could be used to estimate human error effects under ambiguous interacting environments and assist in the design of error free work environments.
A LOWER BOUND FOR THE NODE-PAIR RELIABILITY OF NETWORK SYSTEMS WITH SMALL DISTANCES BETWEEN ADJACENT NODES
Authors: MALINOWSKI JACEK
Published: March 2006

A new method for computing a lower bound of the node-pair reliability of network systems modeled by random graphs with sequentially ordered nodes is presented. It is based on the analysis of the tree structure constructed in order to find all minimal paths connecting two distinguished nodes of the system under consideration. The algorithm is particularly efficient for graphs with small distances between adjacent nodes, where the distance between two nodes is defined as the absolute value of the difference between the nodes' numbers. The presented method can be applied if both nodes and edges are subject to failure. That is important in view of the fact that many algorithms computing network reliability are designed for graphs whose nodes are not failure-prone. Moreover, the method can be applied for directed as well as undirected graphs. The algorithm's numerical complexity depends on 2·rG - 1, where rG is the maximal distance between any two adjacent nodes. It occurs that for rG = 2 the exact value of a network system's reliability can be computed by means of a simple recursive procedure. The results of both (approximate and exact) methods are compared to demonstrate the lower bound's accuracy.
REFACTORIZATION'S IMPACT ON SOFTWARE RELIABILITY
Authors: JÓŹWIAK IRENEUSZ , KOWALCZYK MAKSYMILIAN , PIOTROWICZ ANDRZEJ
Published: March 2006

Software refactorization is a process of changing program's source code structure without changing its functionality. The purpose of the refactorization is to make program's source code easier to understand and maintain, which in turn influence the fact that in a long term such code should have fewer errors (be more reliable). In recent years many works described refactorization, but till now there are no researches, which would assess long term influence of refactoring on reliability. In this work we try to depict our fundamental study on software systems reliability improvement in context of refactoring. We tried to find the answer to the question: What are benefits of using refactorization as far as reliability is concerned?
Age-related loss of associations between acute exercise-induced IL-6 and oxidative stress
Authors: Sacheck Jennifer M. , Cannon Joseph G. , Hamada Koichiro , Vannier Edouard , Blumberg Jeffrey B. , Roubenoff Ronenn
Published: March 2006

IL-6 mediates many aspects of the exercise-induced acute-phase response, including upregulation of antioxidant defenses. Moreover, IL-6 synthesis is regulated in part by oxidative stress. This investigation tested the hypothesis that an IL-6-mediated acute-phase response after exercise provides negative-feedback protection against exercise-induced oxidative stress. Healthy young ( n = 16, 26.4 ± 1.8 yr) and older men ( n = 16, 71.1 ± 2.0 yr) ran downhill for 45 min at 75% maximal oxygen consumption before and after a 12-wk period of supplementation with vitamin E (1,000 IU/day) or placebo. Circulating IL-6 and soluble IL-6 receptors, peripheral mononuclear cell production of IL-6, and IL-6 transcripts in muscle were measured before and within a 72-h time window after each acute exercise bout. At all time points plasma IL-6, IL-6 bioavailability, and C-reactive protein were higher in the older men; yet in response to exercise, young and older subjects experienced similar increases in these factors. Although the magnitude of postexercise changes in acute-phase variables was independent of age, correlations among plasma, mononuclear cell, and muscle IL-6 and oxidative stress were evident only in young men ( R2= 0.64, 0.35, and 0.33, respectively). These changes in circulating IL-6 were closely associated with a prooxidant state ( R2= 0.47), whereas muscle IL-6 mRNA correlated with an antioxidant state ( R2= 0.65). Supplementation with vitamin E did not affect exercise-induced responses or differences between the young and old men in a consistent manner. Therefore, oxidative stress is linked to the acute-phase response after exercise in young men, but not in older men who had elevated acute-phase reactants, suggesting that further research is warranted to determine the basis for these differences.
Increased NF-κB activity in fibroblasts lacking the vitamin D receptor
Authors: Sun Jun , Kong Juan , Duan Yingli , Szeto Frances L. , Liao Anne , Madara James L. , Li Yan Chun
Published: March 2006

1,25-Dihydroxyvitamin D [1,25(OH)2D3] is known to have anti-inflammatory activity; however, the molecular mechanism remains poorly defined. Here we show that the nuclear vitamin D receptor (VDR) is directly involved in the regulation of NF-κB activation, a pathway essential for inflammatory response. In mouse embryonic fibroblasts (MEFs) derived from VDR−/−mice, the basal level of κB inhibitor (IκB) α protein was markedly decreased compared with VDR+/−MEFs; however, degradation of IκBα and its phosphorylation in response to TNF-α treatment or Salmonella infection were not altered in VDR−/−cells, neither were the levels of IκB kinase-α and IκB kinase-β proteins. Consistent with IκBα reduction, p65 accumulation in the nucleus was markedly increased in unstimulated VDR−/−cells. In addition, the physical interaction between VDR and p65 was absent in VDR−/−MEFs, which may free p65 and increase its activity. Consequently, these alterations combined led to a marked increase in nuclear p65 DNA binding and NF-κB transcriptional activity; consistently, induction of IL-6 by TNF-α or IL-1β was much more robust in VDR−/−than in VDR+/−cells, indicating that VDR−/−cells are more susceptible to inflammatory stimulation. Therefore, cells lacking VDR appear to be more proinflammatory due to the intrinsic high NF-κB activity. The reduction of IκBα in VDR−/−MEFs may be partially explained by the lack of VDR-mediated stabilization of IκBα by 1,25(OH)2D3. This is supported by the observation that IκBα degradation induced by TNF-α was inhibited by 1,25(OH)2D3in VDR+/−cells, but not in VDR−/−cells. Taken together, these data suggest that VDR plays an inhibitory role in the regulation of NF-κB activation.
Parallel Processing in Retinal Ganglion Cells: How Integration of Space-Time Patterns of Excitation and Inhibition Form the Spiking Output
Authors: Roska Botond , Molnar Alyosha , Werblin Frank S.
Published: March 2006

Our goal was to understand how patterns of excitation and inhibition, interacting across arrays of ganglion cells in space and time, generate the spiking output pattern for each ganglion cell type. We presented the retina with a 1-s flashed square, 600 μm on a side, and measured patterns of excitation and inhibition over an 1,800-μm–wide region encompassing many ganglion cells. Excitatory patterns of on ganglion cells resembled rectified versions of the voltage patterns of on bipolar cells. Inhibitory patterns in on ganglion cells resembled the rectified versions of voltage patterns of off bipolar cells. off ganglion cells received off excitation and on inhibition. Many ganglion cells also received an additional wide field transient inhibition derived from the activity of both on and off bipolar cells. Ganglion cell spiking was suppressed in those space-time regions dominated by inhibition. We classified each ganglion cell type by correlating its space-time patterns with its dendritic morphology. These studies suggest the bipolar and amacrine cell circuitry underlying the interplay between on and off signals that generate spiking patterns in ganglion cells. They reveal a surprising synergistic interaction between excitation and inhibition in most ganglion cells.
qPCR-DAMS: a database tool to analyze, manage, and store both relative and absolute quantitative real-time PCR data
Authors: Jin Nili , He Keyu , Liu Lin
Published: March 2006

Quantitative real-time PCR is an important high-throughput method in the biomedical sciences. However, existing software has limitations in handling both relative and absolute quantification. We designed quantitative PCR data analysis and management system (qPCR-DAMS), a database tool based on Access 2003, to deal with such shortcomings by the addition of integrated mathematical procedures. qPCR-DAMS allows a user to choose among four methods for data processing within a single software package: 1) ratio relative quantification, 2) absolute level, 3) normalized absolute expression, and 4) ratio absolute quantification. qPCR-DAMS also provides a tool for multiple reference gene normalization. qPCR-DAMS has three quality control steps and a data display system to monitor data variation. In summary, qPCR-DAMS is a handy tool for real-time PCR users.
TheMYCNEnigma: Significance ofMYCNExpression in Neuroblastoma
Authors: Tang Xao X. , Zhao Huaqing , Kung Bing , Kim David Y. , Hicks Sakeenah L. , Cohn Susan L. , Cheung Nai-Kong , Seeger Robert C. , Evans Audrey E. , Ikegaki Naohiko
Published: March 2006

MYCN amplification strongly predicts adverse outcome of neuroblastoma. However, the significance of MYCN expression in the clinical and biological behavior of neuroblastoma has been unclear. To address this question, we first examined the expression of MYCN in combination with TrkA (a favorable prognostic indicator of neuroblastoma) in 91 primary neuroblastoma by quantitative reverse transcription-PCR and investigated the relationship among patient survival, MYCN, and TrkA expressions. Three subsets of neuroblastoma were defined based on MYCN and TrkA expression. Neuroblastoma expressing the highest level of MYCN but little TrkA were MYCN-amplified cases, which had a 5-year survival of 9.3%. Interestingly, MYCN and TrkA expression showed a linear correlation (r = 0.5664, P < 0.00005) in neuroblastoma lacking MYCN amplification, and the 5-year survival of neuroblastoma patients with low MYCN and low TrkA expressions was 63.7%, whereas those with high expression of both had a 5-year survival of 88.1% (P < 0.00005). This nonlinear distribution of disease outcome relative to MYCN expression in neuroblastoma explains why MYCN expression is not predictive of neuroblastoma disease outcome by dichotomous division of the neuroblastoma cohort. However, high-level MYCN expression is associated with favorable outcome in neuroblastoma lacking MYCN amplification. Furthermore, forced expression of MYCN significantly suppresses growth of neuroblastoma cells lacking MYCN amplification by inducing apoptosis and enhancing favorable neuroblastoma gene expression. Collectively, these data suggest that high-level MYCN expression in neuroblastoma lacking MYCN amplification results in a benign phenotype. Thus, the high MYCN expression confers the opposite biological consequence in neuroblastoma, depending on whether or not MYCN is amplified. (Cancer Res 2006; 66(5): 2826-33)
Interleukin-23–Expressing Bone Marrow–Derived Neural Stem-Like Cells Exhibit Antitumor Activity against Intracranial Glioma
Authors: Yuan Xiangpeng , Hu Jinwei , Belladonna Maria L. , Black Keith L. , Yu John S.
Published: March 2006

Neural progenitor-like cells have been isolated from bone marrow and the cells have the ability of tracking intracranial tumor. However, the capacity of the cells to deliver molecules for activating immune response against intracranial tumor and the identity of cellular and molecular factors that are involved in such immune responses have yet to be elucidated. Here, we isolated neural stem-like cells from the bone marrow of adult mice. The isolated cells were capable of producing progenies of three lineages, neurons, astrocytes, and oligodendrocytes, in vitro and tracking glioma in vivo. By genetically manipulating bone marrow–derived neural stem-like cells (BM-NSC) to express a recently discovered cytokine, interleukin (IL)-23, the cells showed protective effects in intracranial tumor-bearing C57BL/6 mice. Depletion of subpopulation lymphocytes showed that CD8+ T cells were critical for the antitumor immunity of IL-23–expressing BM-NSCs and that CD4+ T cells and natural killer (NK) cells participated in the activity. Furthermore, the IL-23–expressing BM-NSC-treated survivors were resistant to the same tumor rechallenge associated with enhanced IFN-γ, but not IL-17, expression in the brain tissue. Taken together, these data suggest that IL-23–expressing BM-NSCs can effectively induce antitumor immunity against intracranial gliomas. CD8+ T cells are critical for such antitumor activity; in addition, CD4+ T cells and NK cells are also involved. (Cancer Res 2006; 66(5): 2630-8)
Haploinsufficiency of the Hmga1 Gene Causes Cardiac Hypertrophy and Myelo-Lymphoproliferative Disorders in Mice
Authors: Fedele Monica , Fidanza Vincenzo , Battista Sabrina , Pentimalli Francesca , Klein-Szanto Andres J.P. , Visone Rosa , De Martino Ivana , Curcio Antonio , Morisco Carmine , Del Vecchio Luigi , Baldassarre Gustavo , Arra Claudio , Viglietto Giuseppe , Indolfi Ciro , Croce Carlo M. , Fusco Alfredo
Published: March 2006

The HMGA1 protein is a major factor in chromatin architecture and gene control. It plays a critical role in neoplastic transformation. In fact, blockage of HMGA1 synthesis prevents rat thyroid cell transformation by murine transforming retroviruses, and an adenovirus carrying the HMGA1 gene in the antisense orientation induces apoptotic cell death in anaplastic human thyroid carcinoma cell lines, but not in normal thyroid cells. Moreover, both in vitro and in vivo studies have established the oncogenic role of the HMGA1 gene. In this study, to define HMGA1 function in vivo, we examined the consequences of disrupting the Hmga1 gene in mice. Both heterozygous and homozygous mice for the Hmga1-null allele show cardiac hypertrophy due to the direct role of HMGA1 on cardiomyocytic cell growth regulation. These mice also developed hematologic malignancies, including B cell lymphoma and myeloid granuloerythroblastic leukemia. The B cell expansion and the increased expression of the RAG1/2 endonuclease, observed in HMGA1-knockout spleen tissues, might be responsible for the high rate of abnormal IgH rearrangements observed in these neoplasias. Therefore, the data reported here indicate the critical role of HMGA1 in heart development and growth, and reveal an unsuspected antioncogenic potential for this gene in hematologic malignancies. (Cancer Res 2006; 66(5): 2536-43)
Tumor-Derived Cyr61(CCN1) Promotes Stromal Matrix Metalloproteinase-1 Production and Protease-Activated Receptor 1–Dependent Migration of Breast Cancer Cells
Authors: Nguyen Nga , Kuliopulos Athan , Graham Roger A. , Covic Lidija
Published: March 2006

Matrix metalloproteinases (MMPs) play a central role in remodeling the tumor-stromal microenvironment. We recently determined that stromal-derived MMP-1 also acts as a signaling molecule by cleaving protease-activated receptor 1 (PAR1) to cause breast cancer cell migration and invasion. Here, we show that ectopic PAR1 expression induces expression of the angiogenic factor Cyr61(CCN1) in breast cancer cells. The tumor-derived Cyr61 acts as an invasogenic signaling molecule that induces MMP-1 expression in adjacent stromal fibroblasts. Gene silencing of Cyr61 in breast cancer cells suppresses MMP-1 induction in stromal fibroblasts resulting in a major loss in migration of the cancer cells toward the fibroblasts. Cyr61-dependent loss of migration was complemented by exogenous MMP-1 and required the presence of the functional PAR1 receptor on the breast cancer cells. These results suggest that interrupting tumor-stromal cell communication by targeting Cyr61 may provide an alternative therapeutic approach for the treatment of invasive breast cancer. (Cancer Res 2006; 66(5): 2658-65)
N-myc Can Substitute for Insulin-Like Growth Factor Signaling in a Mouse Model of Sonic Hedgehog–Induced Medulloblastoma
Authors: Browd Samuel R. , Kenney Anna M. , Gottfried Oren N. , Yoon Joon Won , Walterhouse David , Pedone Carolyn A. , Fults Daniel W.
Published: March 2006

Medulloblastoma is a malignant brain tumor that arises in the cerebellum in children, presumably from granule neuron precursors (GNP). Advances in patient treatment have been hindered by a paucity of animal models that accurately reflect the molecular pathogenesis of human tumors. Aberrant activation of the Sonic hedgehog (Shh) and insulin-like growth factor (IGF) pathways is associated with human medulloblastomas. Both pathways are essential regulators of GNP proliferation during cerebellar development. In cultured GNPs, IGF signaling stabilizes the oncogenic transcription factor N-myc by inhibiting glycogen synthase kinase 3β–dependent phosphorylation and consequent degradation of N-myc. However, determinants of Shh and IGF tumorigenicity in vivo remain unknown. Here we report a high frequency of medulloblastoma formation in mice following postnatal overexpression of Shh in cooperation with N-myc. Overexpression of N-myc, alone or in combination with IGF signaling mediators or with the Shh target Gli1, did not cause tumors. Thus, Shh has transforming functions in addition to induction of N-myc and Gli1. This tumor model will be useful for testing novel medulloblastoma therapies and providing insight into mechanisms of hedgehog-mediated transformation. (Cancer Res 2006; 66(5): 2666-72)