bluuebunny/crossref_metadata_2025 huggingface dataset:
A Toy “Magnetometer”
Authors: Cary A. , Mayfield E. , Mottmann J.
Published: September 2008

Everyone likes to play with toys and entertain themselves with devices built to amuse or mystify. The authors became intrigued with tabletop devices originally designed to demonstrate magnetic “levitation.” Toys of this type can be purchased commercially1 or assembled from a kit.2 We found that such an inexpensive device could be used to monitor the daily variations in the Earth's local magnetic field. A comparison of our daily observations with those of international geomagnetic observatories shows remarkably similar patterns of magnetic variation.
Acoustic measurements through analysis of binaural recordings of speech and music
Authors: Griesinger David
Published: September 2008

This paper will present and demonstrate some recent work on the measurement of acoustic properties from binaural recordings of live performances. It is found that models of the process of stream formation can be used to measure intelligibility, and, when combined with band-limited running cross-correlation, can be used to measure spaciousness and envelopment. Analysis of the running cross correlation during sound onsets can be used to measure the accuracy of azimuth perception. It is additionally found that the ease of detecting fundamental pitch from the upper partials of speech and music can be used as a measure of sound quality, particularly for solo instruments and singers.
Comparison of behavioral and auditory evoked potential (AEP) audiograms of a false killer whale (Pseudorca crassidens)
Authors: Yuen Michelle , Nachtigall Paul E. , Breese Marlee , Supin Alexander Ya.
Published: September 2008

Behavioral and auditory evoked potential (AEP) audiograms of a false killer whale were measured using the same subject and experimental conditions from 2001 to 2004. The objective was to compare and assess the validity of auditory thresholds collected by psychometric and electrophysiological techniques. Behavioral audiograms used 3-s pure-tone stimuli from 4 to 45 kHz. AEP audiograms used 20-ms sinusoidally amplitude-modulated (SAM) tone bursts from 4 to 45 kHz. Electrophysiological responses were received through gold disk electrodes mounted in rubber suction cups placed on the animals dorsal surface. Psychometric data were reliable and repeatable with the region of best sensitivity for the behavioral audiograms between 16 and 24 kHz, and with peak sensitivity at 20 kHz. The AEP measures produced thresholds that were consistent over time, with ranges of best sensitivity from 16 to 22.5 kHz and peak sensitivity at 22.5 kHz. Behavioral thresholds were lower than AEP thresholds. Signal type and duration differences may explain the discrepancies between thresholds obtained under the two conditions. These data indicated that behavioral and AEP techniques can be used successfully and interchangeably to measure cetacean hearing sensitivity. [Work supported by ONR.]
Surface ship underwater radiated flow noise
Authors: de Jong Christ A. F. , van Lier Leonard J. , Bosschers Johan
Published: September 2008

An increasing focus on naval operations in littoral waters and the advances in weapon and sensor capabilities are driving an increased interest in the control of the underwater signatures of naval platforms. The technology for the control of machinery and propeller noise is well advanced, but there is a short fall in knowledge of the mechanisms that govern the underwater radiated noise due to the flow along the hull and appendages, especially for surface ships. The United States and Netherlands Navies have started a joint technology research and development program on Mechanisms and Prediction of Surface Ship Radiated Flow Noise, running from 2004 until 2007. This paper gives an overview of the research program and a summary of the results of the initial studies that have been carried out to date. Several possible noise source mechanisms have been identified on the basis of a literature survey and the results of a series of underwater noise measurements on full-scale frigates. The objective of the program is to develop and validate scaling laws and theoretical models for predicting flow noise levels of surface ships.
The effects of the wind velocity fluctuations on the sound backscattering cross section in the stratified moving atmosphere
Authors: Ostashev Vladimir E. , Wilson D. Keith
Published: September 2008

Recent studies have shown that, in the case of strong diffraction, the relative contributions from wind velocity and temperature fluctuations to many statistical moments of a sound field propagating in a turbulent atmosphere are determined by the ratio of the normalized variances of wind velocity and temperature fluctuations, multiplied by factor 4. On the other hand, for weak diffraction, these relative contributions are determined by the ratio of the normalized structure–function parameters of wind velocity and temperature fluctuations, multiplied by factor 22/3. In this paper, we calculate the vertical profiles of both ratios for different turbulent regimes in unstable atmospheric boundary layers. Furthermore, vertical profiles of the ratio for weak diffraction are used to study the effects of the wind velocity fluctuations on the sound backscattering cross section in a stratified moving atmosphere. This study is important for acoustic remote sensing of the atmosphere by monostatic sodars which measure a signal proportional to the backscattering cross section. [Work supported in part by the U.S. Army Research Office under Contract No. DAAG55-98-1-0463, and an NRC-ETL Research Associateship.]
Intelligibility of Arabs’ production of English grammatical words
Authors: Mitleb Fares
Published: September 2008

Features of connected speech such as the use of weak forms of grammatical words in English are said to have an important role in the communication process between native and nonnative speakers. The present study is intended to describe how intelligible is the production of certain English grammatical words for British English listeners by Arabs. Six Arabs learning English and four British speakers produced 15 sentences with 17 grammatical words for the purpose of this study. Four native British listeners were asked to judge the stimuli they heard of certain grammatical words as either having a ‘‘strong’’ or ‘‘weak’’ form. They reported that Arabs’ production of strong forms was almost the same as that of native subjects. However, the Arab subjects failed to produce a high percentage of intelligible weak forms. Findings of this impressionistic study were then examined against the well-established approaches to the problem of foreign-accented speech. Our results seem to support claims about the interference of segmental knowledge onto features of connected speech since the first is generally given too much emphasis in the teaching of the target language to the extent that the latter is most neglected. [Research supported by Yarmouk University.]
Ultrasound contrast agents retain acoustic activity post phagocytosis by leukocytes
Authors: Dayton Paul , Chomas James , Ferrara Katherine , Lindner Jonathan , Coggins Matthew
Published: September 2008

It has been observed that ultrasound contrast microbubbles are phagocytosed intact by activated leukocytes in regions of inflammation. In order to determine if microbubbles remain acoustically active following phagocytosis, the physical responses of phagocytosed and free microbubbles to acoustic pulses were measured optically and acoustically. The rate of microbubble destruction at each acoustic pressure is lower for phagocytosed compared to free microbubbles. Destruction of phagocytosed microbubbles at −1600 kPa occasionally results in disruption of the leukocyte cell membrane. The phenomena of leukocyte destruction by insonified microbubbles was assessed with a high-speed imaging system and appeared to be due to rapid, extreme fluctuations in microbubble diameter (up to 300%) during pressure rarefaction. Analysis of the echoes returning from phagocytosed microbubbles demonstrated similarity to the nonlinear responses produced by free microbubbles. Primary radiation force is observed to displace phagocytosed microbubbles a distance of 100 μm (−240 kPa, 10 kHz PFR), thus providing further evidence of acoustic activity. It can be concluded that phagocytosed microbubbles maintain their susceptibility to acoustic descruction and can generate nonlinear echoes. These results indicate that contrast-enhanced ultrasound may be used to identify and assess regins of inflammation by detecting acoustic signals from microbubbles that are phagocytosed by activated leukocytes. For Biomedical Ultrasound/Bioresponse to Vibration Best Student Paper Award.
Aerodynamic sound from a high-speed modulated transitory wave: Application to screech
Authors: Powell Alan
Published: September 2008

Screech occurs in supersonic jets characterized by a periodic cell structure (cell length s) in which the jet velocity varies periodically in the downstream direction. The transitory wave (Mach number M, wavelength Λ) consequently becomes space-modulated, upsetting the otherwise high degree of cancellation and yielding a stationary phased array, resolvable into long and short propagating waves, of wavelengths Λs/(Λ−s) and Λs/(Λ+s). The radiation of the latter is comparatively very weak. The former radiates with a single peak in the upstream direction, maximizing with perfect reinforcement when Λ/s=(1+M), the peak shifting away from the axis for higher Mach numbers. Plausible assumptions yield realistic screech intensity estimates (that exceed those of the downstream radiation of the unmodulated wave). The first harmonic of the cell structure interacts with that of the transitory wave to produce another single directional maximum, at near normal to the jet direction, again in accordance with experiment. In this treatment the simplest of assumptions have been used. In particular, the cell structure has been taken to be fixed, whereas Schlieren photographs reveal that sometimes very large displacements occur. This nonlinear refinement is now being investigated.
Exact global boundary condition with reduced computational complexity for grid truncation in acoustic finite difference time domain simulations
Authors: Ergin A. Arif , Shanker Balasubramaniam , Michielssen Eric
Published: September 2008

The numerical analysis of transient acoustic radiation by and scattering from inhomogeneous bodies is often carried out using the finite difference time domain (FDTD) method. However, FDTD grids must be truncated with absorbing boundary conditions when the structure of interest resides in an unbounded medium. Local boundary conditions have to be imposed on a convex outer boundary, thereby often inflating the problem size. This drawback is alleviated if the grid is truncated using exact boundary conditions that rely on a retarded-time boundary integral (RTBI) [L. Ting and M. J. Miksis, J. Acoust. Soc. Am. 80, 1825–1827 (1986)]. Unfortunately, for a 3-D computational domain comprising of O(N3) FDTD cells, where N denotes the number of cells per unit length, the evaluation of the RTBI using classical methods requires O(N4) operations per time step, which renders the RTBI approach impractical. In this presentation, it will be shown that this computational bottleneck can be alleviated by employing the plane wave time domain algorithm [A. A. Ergin et al., J. Comput. Phys. 146, 157–180 (1998)] using which the RTBI can be evaluated in O(N2log2N) operations. Numerical results that demonstrate the efficacy and reduced complexity of the method will be presented.
Neural network-based ultrasonic C-scan imaging of austenitic structures
Authors: Petculescu Petre , Ciobanu Dorin
Published: September 2008

Results of new studies of C-scan imaging on austenitic welds, used in conjunction with artificial neural network techniques, are reported. The C-scan technique provides high-resolution images of subsurface zones which are inaccessible by conventional A-scans. Based on the anisotrophy-induced perturbation of ultrasonic signals, the anisotropic regions in various steels were detected by C-scan imaging. C-scan images of both homogeneous samples of austenitic steels and heterogeneous samples of austenitic welds allowed the neural network-based ‘‘training‘‘ of the measurement and analysis system. The locations and approximate compositions of the various inhomogeneities present in the welds were determined. Image analysis was used to identify three austenitic structures (W.4541, W.6903 and HP 50) in the welds under study.
Recursive application of cross-correlation for extraction of sparse impulse trains from ultrasonic nondestructive evaluation data
Authors: Hanshaw Timothy C. , Hsu Chin S. , Daniels Jeffrey A. , Anderson Michael J.
Published: September 2008

The goal of Quantitative Nondestructive Evaluation is to determine numerical values for a specimen’s properties. In many cases, especially when the specimen is composed of thin layers, the material properties manifest themselves in a sparse train of impulses. This is the case for many state of the art hybrid materials. Signal processing techniques can be used to extract the desired impulse train from the ultrasonic data. In this paper, a cancellation method is used to recursively subtract a reference wavelet from the acoustic response of a test specimen in order to determine the desired impulse train of the specimen. The method was applied to acoustic data for a thin aluminum sheet. The resulting impulse train displayed enhanced fidelity as compared to the original wave form. Wave travel times and transmission coefficients thus obtained agree with expected values to within 6%.
Final consonant recognition in young children
Authors: Edwards Jan , Fox Robert A. , Rogers Catherine L.
Published: September 2008

Research has shown that typically developing children evidence gradual improvement with age on speech perception tasks. Studies have also shown that children with phonological disorder and specific language impairment perform more poorly than typically developing age peers on these same tasks. Previous research has mostly used synthetic speech stimuli, although it is known that additional attentional resources are required to process synthetic speech. Furthermore, most research has focused on identification or discrimination of word-initial consonants, rather than on consonants in other word positions. In our research, experimental paradigms were developed that use digitized natural speech, rather than synthetic speech, and focus on final rather than initial consonants, since final consonants tend to be acquired later in production. Results of a study with 15 typically developing 3- and 5-year olds will be presented. Familiar word pairs (cap versus cat and tap versus tack) were recorded, digitized, and presented at three different gates (up to 60 ms removed from final consonant closure). Values of d-prime were calculated for each gate, and an improvement in identification with age was found for the longer gates. Results will also be presented comparing 10 children with phonological disorder and age peers. [Research supported by NIDCD No. DC02932.]
Binaural equalization for loudspeaker systems
Authors: Wang Peng , Ser Wee
Published: September 2008

On-axis equalization methods for loudspeaker systems can be found everywhere. In these schemes, the axial impulse responses are taken as the objects to be equalized. However, the generated equalizers will display unsatisfactory off-axis distortions and different equalization effects at left and right ears. In this paper, a new criterion, which combines the considerations of the distortions at left and right ears and the binaural difference, is presented. A binaural equalization method applying this criterion is introduced and the comparison with normal on-axis equalization methods is also given.
Geoacoustic parameter estimation using a back-wave propagation technique
Authors: Dizaji Reza M. , Chapman N. Ross , Kirlin R. Lynn
Published: September 2008

The concept of back-wave propagation is developed as an inversion method to estimate ocean geoacoustic parameters where the source location is known. A phase-regulated technique is introduced to increase the sensitivity of the method for low-sensitive geoacoustic model parameters. In this procedure, a sensitivity factor is varied to enhance the phase changes due to model and environmental mismatch. It is shown that the spatial resolution of signal-energy concentrated at the true source location is increased when the sensitivity factor increases. This leads us to define a criterion based on spatial variance of signal energy around the true source location. This technique is applied to the real data from the Pacific Shelf experiment that was carried out in the shallow water off the West Coast of Vancouver Island in the Northeast Pacific Ocean. The inversion for estimating three ocean parameters including water depth, compressional speed of the first sediment layer, and sediment density is demonstrated. A way to reduce the three-dimensional search to three one-dimensional searches is proposed by exploiting the fact that the pressure field has different sensitivity with respect to these parameters. The replica or modeled fields used in this section are calculated using ORCA.
The effect of moisture on compressional and shear wave speeds in unconsolidated granular materials
Authors: Shields F. Douglas , Sabatier Jim , Wang Mark
Published: September 2008

The effect of water vapor on the shear and compressional wave speeds in two different kinds of glass beads and in Ottawa sand has been measured. The nominal diameter of the glass beads was 125 μm and of the sand, 500 μm. The measurements were made as the water vapor was introduced slowly into the evacuated material. The vapor pressure isotherm for the beads made of titanium-barium glass was fit reasonably well by the simple BET theory. For the Ottawa sand the BET theory fit the vapor pressure isotherm if the surface area of the grains was assumed to be three times the area calculated, assuming all of the grains were spheres with a diameter of 500 μm. In these two materials the vapor had little effect on the wave speeds. For beads made of lime glass, however, the wave speeds approximately double with the introduction of water vapor, and the vapor pressure isotherm had the BET shape only if the saturated vapor pressure was assumed to be lowered by 20%. These results have been explained by assuming that a chemical reaction occurred between the lime glass and the water to form a gel. [Work supported by the USDA.]
Investigation of power flow in the midfrequency range for systems of colinear beams based on a hybrid finite-element formulation
Authors: Zhao Xi , Vlahopoulos Nickolas
Published: September 2008

A hybrid finite-element analysis (hybrid FEA) is employed for investigating power-flow characteristics for systems of colinear beams in the midfrequency range. The importance of capturing power reinjection and power reradiation effects in the solution is demonstrated. The dependency of the power-flow characteristics of a system in the midfrequency range on the rigidity, mass, and damping properties of its components is determined. Both the hybrid FEA and analytical solutions are employed for analyses in order to establish the viabilty of the hydrid FEA as a simulation technology in the midfrequency range. [Work supported by the Automotive Research Center established at the University of Michigan by the US Army Tank Automotive Command.]
Decoupling electrical and mechanical loss measurements in piezoelectric ceramic
Authors: Smith R. Lowell
Published: September 2008

Specimens of commercial piezoelectric ceramic material are commonly screened before use by observing their two-terminal impedance or admittance behavior as a function of frequency near the most prominent electromechanical structure resonance. Often a companion admittance measurement is made at 1 kHz, and interpreted in terms of the free capacitance and its associated dielectric loss tangent. Due to the strong electromechanical coupling of this class of materials, the low-frequency dissipation should be regarded as due to combined electrical and mechanical losses. This paper discusses an inductive tuning measurement strategy that permits substantially decoupled observations of the electrical and mechanical losses to be made. Motivation for the method is developed using standard equivalent circuit analogies, which also provide a useful means for interpreting two-terminal electrical measurements on the materials of interest. Such an approach is beneficial because linear piezoelectric materials such as lead zirconate titanate are not very lossy, and a low-frequency dissipation measurement typically does not yield a very precise loss tangent determination.
Characterization of time-varying responses to dynamic broadband spectra in primary auditory cortex
Authors: Simon Jonathan Z. , Depireux Didier A. , Klein David J. , Shamma Shihab A.
Published: September 2008

The neural encoding of time-varying, spectrally rich sounds (such as speech and music) in primary auditory cortex (AI) is still poorly understood. In this research, the time-varying responses of units in AI to dynamically and spectrally modulated noise are characterized. The most elementary form of these stimuli, a ‘‘moving ripple,’’ has a spectro-temporal envelope which is modulated sinusoidally in both spectral and temporal dimensions. More complex sounds have spectro-temporal envelopes decomposable into multiple sinusoidal components. Responses to both simple and complex stimuli allow independent measurements of the Spectro-Temporal Response Field (STRF). The STRF provides both a quantitative and intuitive measure of how a unit encodes dynamic sound features into its resultant time-varying spike train. The STRF is a linear response characteristic, but for a reasonably broad class of sounds, the STRF predicts the response of units to novel stimuli. Constraints on the structure of STRFs, such as whether they are separable (the vast majority appear to be quadrant-separable), are also constraints on the connectivity of the neuronal inputs. [Supported by grants from ONR, NIDCD, and NSF.]
Characterization of a 300-W linear actuator
Authors: Minner Brian , Mongeau Luc , Braun Jim
Published: September 2008

The linear parameters of a moving magnet electrodynamic actuator were measured using several different procedures. The methods employed included blocked carriage tests, regression of free decay of voltage and acceleration for known mass addition, regression of complex impedance data resulting from peak-averaged voltage/current transfer functions in swept sine tests, and solution of nonlinear equations for impedance and velocity/voltage relationships for three or four data point sets. It was found that the mechanical system parameters are strong functions of the motional amplitude, and that electrical system parameters are functions of frequency and amplitude. A brief review of the literature and a comparison of the methods and results will be presented. Simulated data will be used to benchmark the methods, enabling clearer interpretation of the results.
Sensing radiated acoustic power using smart sensors
Authors: Zou Dingguo , Crocker Malcolm J.
Published: September 2008

This paper represents the radiated acoustic power from a vibrating structure as a quadratic form of the structural modal velocities. The weighting matrix is diagonalized by using the congruent transformation. A group of one-dimensional shaped smart sensors which can sense the acoustic power from the structure by filtering the combination of weighted vibration modes are designed. First, it was found that if the shaped function is chosen carefully, the measuring from a two-dimensional distributed parameter sensor using PVDF film is independent of the position. Then, the plate is vertically divided by some narrow strips. The narrow strips are assumed to be approximate one-dimensional plate. The one-dimensional shaped sensor equations can be used to measure a particular modal coordinate. The acoustic power can be obtained by weighting the measurements from multiple one-dimensional smart sensors. Finally, the approximate results are adjusted further by using the theoretical formulation.
Case studies of music facilities in schools
Authors: Siebein Gary W. , Gold Martin A.
Published: September 2008

Case studies of new music facilities in elementary through junior college school levels are presented with a focus on the design process. The study includes issues raised in establishing design criteria with architects and clients; acoustic space planning, organization, and other preliminary design issues; budget, design criterial, and material selection issues; acoustic models and prediction tools; background noise and noise control issues; sound system integration; constructed spaces and follow-up acoustical measurements; and client and user comments regarding the performance of the spaces. Each specific issue is presented within the context of built projects ranging in scope from elementary school practice rooms to a high school auditorium for a magnet performing arts school. The case studies present issues regarding the relationship between established acoustical design criteria, predict tools, architectural integrity, and budgetary constraints as determiners of successful spaces for listening.
Theory for sonoluminescence in cryogenic monatomic systems
Authors: Storey Brian D. , Tseng Howard , Szeri Andrew J.
Published: September 2008

Single-bubble sonoluminescence involves the focusing of acoustic energy by a single bubble to produce light. Most successful sonoluminescence experiments are conducted in liquid water around standard atmospheric conditions. Recent numerical work has shown that water vapor trapped in the interior limits the peak temperatures produced in the bubble interior. The water vapor has a low specific heat ratio reducing the amount of compression heating, and endothermic chemical reactions absorb much of the focused acoustic energy. To overcome these problems, a system of gaseous helium dissolved in liquid argon is investigated. In this system the bubble interior is always a monatomic gas, therefore compression heating is maximized. Regions of stability (with respect to shape perturbations and rectified diffusion) are determined for single bubbles. It is of interest to determine whether the peak temperatures achieved can be significantly increased relative to experiments in water. [This work was supported by NSF and LLNL.]
Initial metrics and pilot program results for measuring the performance of the Canadian construction industry
Authors: Rankin Jeff , Fayek Aminah Robinson , Meade Gerry , Haas Carl , Manseau André
Published: September 2008

A study has been initiated by the Canadian Construction Innovation Council to support the measurement of the performance of the Canadian construction industry. Metrics have been established to cover aspects of cost, time, scope, quality, safety, innovation, and sustainability. The metrics were piloted with industry partners and applied to institutional building and infrastructure projects. The metrics were selected in recognition of other national and international efforts in benchmarking and with a view of supporting analysis at the project, organization, and industry level. The experience gained through the pilot project indicates that the metrics are reasonably well understood in their definition. While the cost, time, scope, and safety information is readily available, as expected, the information for quality innovation and sustainability is not or requires more detailed in-person interviews of project participants to obtain a complete picture of project performance. The data analysis and presentation conducted to date indicates that a combination of radar charts and box plots works best as a means to communicate results. The result of the study to date is a standard set of metrics, and collection and reporting methods for the performance of the Canadian construction industry that are useful as the basis of a broad benchmarking program.
Experimental evaluation of accuracy of current practices in analysis and design of railway track sleepers
Authors: Sadeghi J. M.
Published: September 2008

This research investigates the accuracy of the assumptions made in the current method of analysis and design of railway track sleepers. This study consists of a comprehensive field investigation into the response of sleepers in a railway track system to static and dynamic loads. In the experiments, several load cells (load gauges) are installed under a rail seat and beneath a B70 concrete sleeper for the purpose of monitoring the response of the sleeper to vertical loads. The dynamic coefficients factor, the ratio of the rail seat load to the wheel load and the pressures between the sleeper and the ballast are measured. The results are used to evaluate the current approaches for the analysis and design of concrete sleepers, in particular those proposed by the Americans (AREMA) and Europeans (UIC). New models are proposed for the calculation of dynamic load factors, correlations between wheel loads and rail seat loads, and load distribution patterns beneath sleepers.
Development of a three-dimensional numerical model to solve shallow-water equations in compound channels
Authors: Jazizadeh F. , Zarrati A. R.
Published: September 2008

Velocity gradient between main channel and flood plains in compound channels leads to the formation of a large shear layer and secondary currents between these two subsections. These phenomena in the interaction region bring about a complex three-dimensional nature of the flow in compound channels. To cope with these flows, many numerical investigations have utilized three-dimensional formulations with advanced turbulence models. However, the free surface in many of these models is fixed and rigid-lid assumption has been used. In the present research, three-dimensional shallow water equations were used to calculate the flow field in compound channels. Three-dimensional equations were integrated in layers and were combined with the continuity equation. In this formulation, free-surface elevation was calculated without the need to solve any additional equations. Velocity and bed shear stress distribution and the stage–discharge relationship in compound channels with smooth and rough beds and with different relative depths were analyzed to verify this model, and satisfactory results were obtained.
Turbulence characteristics in skimming flows on stepped spillways
Authors: Carosi G. , Chanson H.
Published: September 2008

The stepped spillway design is characterized by an increase in the rate of energy dissipation on the chute associated with a reduction of the size of the downstream energy dissipation system. This study presents a thorough investigation of the air–water flow properties in skimming flows with a focus on the turbulent characteristics. New measurements were conducted in a large-size facility (θ = 22°; step height, h = 0.1 m) with several phase-detection intrusive probes. Correlation analyses were applied to estimate the integral turbulent length and time scales. The skimming flow properties presented some basic characteristics that were qualitatively and quantitatively in agreement with previous air–water flow measurements in skimming flows. Present measurements showed some relatively good correlation between turbulence intensities Tuand turbulent length and time scales. These measurements also illustrated large turbulence levels and large turbulent time and length scales in the intermediate region between the spray and bubbly flow regions.
Structural behaviour and design criteria of under-deck cable-stayed bridges and combined cable-stayed bridges. Part 2: Multispan bridges.
Authors: Ruiz-Teran A. M. , Aparicio A. C.
Published: September 2008

This paper deals with the application of under-deck cable-staying systems and combined cable-staying systems to prestressed concrete road bridges with multiple spans of medium length. Schemes using under-deck cable-staying systems are not suitable for continuous bridges, as they are not efficient under traffic live load and only allow for the compensation of permanent load. However, combined cable-staying systems are very efficient for continuous bridges and enable the design of very slender decks (1/100th of span) where the amount of materials used is halved in comparison with conventional schemes without stay cables. In this paper, the substantial advantages provided by combined cable-staying systems for continuous bridges (such as high structural efficiency, varied construction possibilities, both economic and aesthetical benefits, and landscape integration) are set out. Finally, design criteria are included.
Optimization of regional waste management systems based on inexact semi-infinite programming
Authors: He L. , Huang G.H.
Published: September 2008

This study proposes an inexact semi-infinite programming (ISIP) method for dealing with engineering optimization problems. The ISIP problem is solved by dividing it into two interactive linear programming subproblems and then solved by conventional simplex method, respectively. The method is applied to a system for identifying optimal regional waste management strategies under uncertainty. The results indicate that the generated strategies obtained though ISIP would not increase the complexity in decision-making processes. Compared to interval linear programming (ILP), ISIP has the advantages of (i) better reflecting the association of the total system revenue with gas and power prices, (ii) generating more reliable solutions with a lower risk of system failure due to the possible constraints violation, and (iii) providing a more flexible management strategy since the capital availability can be adjusted with the variations in gas prices. Although only a hypothetical but representative system is applied in this study, the proposed ISIP method may be applicable to many other systems where the complex uncertainties in parameters should be taken into account.
Development of an index assignment procedure compatible with the regional seismicity in the province of Quebec for the rapid visual screening of existing buildings
Authors: Karbassi Amin , Nollet Marie-José
Published: September 2008

In the context of the seismic vulnerability evaluation of buildings, the score assignment method can be used as the first step of a multiphase procedure aimed at identifying hazardous buildings that must then be analysed in greater detail. Because the existing Canadian rapid visual screening procedure has not been updated since 1992, a new procedure is proposed based on a set of vulnerability indices for different cities in the province of Quebec. A seismicity level (low, moderate, or high) is attributed to each city using the spectral acceleration response values included in the 2005 edition of National building code of Canada (NBCC) and the criteria proposed in FEMA 310 Handbook for the seismic evaluation of buildings - a prestandard. The structural vulnerability indices (SVIs) are calculated using the recently improved nonlinear static analysis procedure in FEMA 440, Improvement of nonlinear static seismic analysis procedures for each seismicity level. The NBCC 2005 reference soil class C is considered in the calculation of the SVIs, and index modifiers for the building height, irregularities, and design and construction year. The application of these indices to the estimation of the probable damage distribution in building inventories is discussed at the end.
Introduced predators and cavity-nesting seabirds: unexpected low level of interaction at breeding sites
Authors: Ruffino L. , Bourgeois K. , Vidal E. , Icard J. , Torre F. , Legrand J.
Published: September 2008

The mechanisms by which introduced predators and long-lived seabirds interact and even coexist are still poorly known. Here, the interactions between the widely introduced black rat ( Rattus rattus (L., 1758)) and an endemic Mediterranean cavity-nesting seabird, the yelkouan shearwater ( Puffinus yelkouan (Acerbi, 1827)), were for the first time investigated for a set of 60 suitable breeding cavities throughout the entire breeding cycle of this seabird. Our results pointed out that rat visits to cavities were significantly higher when shearwaters had left the colony for their interbreeding exodus. Among the set of suitable breeding cavities, yelkouan shearwaters preferentially selected the deepest and the most winding cavities for breeding. Very few rat visits were recorded at the shearwater-occupied cavities and no predation event was recorded. These intriguing results reveal a low level of interaction between introduced black rats and yelkouan shearwaters, which may have facilitated their long-term coexistence for thousands of years on some Mediterranean islands.
Genetic structure of raccoons in eastern North America based on mtDNA: implications for subspecies designation and rabies disease dynamics
Authors: Cullingham C. I. , Kyle C. J. , Pond B. A. , White B. N.
Published: September 2008

Subspecific designations are useful for wildlife management when they represent real barriers to gene flow. In this study, we assess genetic partitioning of mitochondrial DNA control region variation to determine if the structuring is congruent with morphologically defined subspecies of the common raccoon (Procyon lotor (L., 1758)). Mitochondrial control region sequences were analyzed within and among four subspecies ( Procyon lotor elucus Bangs, 1898, Procyon lotor lotor (L., 1758), Procyon lotor hirtus Nelson and Goldman, 1930, and Procyon lotor varius Nelson and Goldman, 1930) that occur along the eastern seaboard of North America through to the central United States. This identified 76 haplotypes, 59 of which were specific to one of the four ranges, while only 1 haplotype was wide-spread. Phylogenetic analysis revealed three distinct lineages: one found primarily in Florida, one along the eastern seaboard, and the third predominantly to the west of the Mississippi River. These lineages likely diverged during the Pleistocene, as a result of rising sea levels creating barriers to gene flow. The range of P. l. elucus is still primarily one lineage supporting the subspecific designation; however, there is considerable lineage mixing across the ranges of P. l. hirtus, P. l. lotor, and P. l. varius, suggesting that they be synonymized to P. l. lotor. While some of these subspecies designations are not supported, we have found that landscape attributes affect gene flow, which can be of use in informing rabies management.
Foraging strategies of wolverines within a predator guild
Authors: van Dijk Jiska , Andersen Tommy , May Roel , Andersen Reidar , Andersen Roy , Landa Arild
Published: September 2008

Within the predator guild, wolverines ( Gulo gulo (L., 1758)) have evolved as generalist predators and scavengers on prey killed by other predators. The recovery of wolves ( Canis lupus L., 1758) in the boreal forests of southern Norway during the late 1990s may have triggered consequent recolonization by wolverines through increased carcass availability. We investigated winter foraging behavior of wolverines in the boreal forest with regard to wolf, lynx ( Lynx lynx (L., 1758)), and red fox ( Vulpes vulpes (L., 1758)) presence. We followed 55 wolverine tracks in the snow from at least nine individuals for a total of 237 km during the winters of 2003–2004. We documented 19 moose ( Alces alces (L., 1758)) and 4 bird carcasses, and no successful hunts. Wolverines did not follow guild species trails directly to carcasses; however, they did change their movement patterns after red fox encounters. While wolverines were more active at higher elevations, the probability of encountering a wolf was higher at lower elevations, suggesting a spatial separation between wolverines and wolves. Although wolverines seem to depend on wolf for carrion during winter, they did not use wolf trails to find carcasses. This may indicate that wolverines reduce risk of intraguild predation by avoiding direct confrontation with wolves.
The case of the blood-covered egg: ectoparasite abundance in an arctic goose colony
Authors: Harriman V. B. , Alisauskas R. T. , Wobeser G. A.
Published: September 2008

Since 1991, blood-covered eggs have been noted in nests of Ross’s ( Chen rossii (Cassin, 1861)) and lesser snow ( Chen caerulescens caerulescens (L., 1758)) geese at the Karrak Lake colony, Nunavut, Canada. Fleas ( Ceratophyllus vagabundus vagabundus (Boheman, 1866)) were subsequently observed to be associated with goose nests containing eggs covered with dried blood. We examined prevalence of blood presence on goose eggs and extent of egg coverage with blood in goose nests from 2001 to 2004. Flea abundance in nests was estimated in 2003 and 2004, and was strongly correlated with the proportion of goose egg surface covered by blood, suggesting that degree of blood coverage was a suitable index of flea abundance. Extent of blood fluctuated annually and was correlated with both host characteristics and host habitat factors. Nest bowls used by geese in previous years contained more fleas than did new nest bowls, and fleas were more abundant in older areas of the colony. Flea abundance increased with goose clutch size and was highest in rock and birch habitats. Ceratophyllus vagabundus vagabundus appears to be a new parasite of geese at Karrak Lake; flea abundance may change in response to increased availability of favorable habitat, which is expected if local climate warms.
Genetic and growth differences in the outcrossings between two clonal strains of the self-fertilizing mangrove killifish
Authors: Nakamura Yukino , Suga Koushirou , Sakakura Yoshitaka , Sakamoto Takashi , Hagiwara Atsushi
Published: September 2008

The populations of the only known self-fertilizing vertebrate Kryptolebias marmoratus (Poey, 1880) (formerly known as Rivulus marmoratus Poey, 1880; Cyprinodontiformes: Aplocheilidae) usually consist of different homozygous lineages; however, heterozygous individuals are found occasionally and ratios of homozygosity and heterozygosity in populations are dependent on the proportion of males. However, it is still unclear what impact male-mediated genetic diversity has on the phenotype of K. marmoratus. To clarify this, we attempted outcrossing between male and hermaphrodite of two different clonal strains with different life-history traits using artificial insemination, and examined the genotypes and growth of the hybrid F2 generation. We detected genetic differences between the two clonal strains using amplified fragment length polymorphism (AFLP) analysis with 3 primer combinations, and then obtained 11 AFLP markers. From a total of 31 artificial inseminations with two clonal strains, 1 of 13 hatched fish clearly indicated heterozygosity. The hybrid F2 generations were also heterozygous. Moreover, the growths of the hybrid F2 generation were intermediate of the parental strains from days 0 to 30. Therefore, outcrossing changes genetic architecture and the new genotypes potentially result in new phenotypes of the subsequent generations of K. marmoratus. It may also play a role in adaptation to new environments and the facilitation of local adaptation.
Movement patterns, habitat selection, and corridor use of a typical woodland-dweller species, the European pine marten (Martes martes), in fragmented landscape
Authors: Pereboom Vincent , Mergey Marina , Villerette Nicolas , Helder Rémi , Gerard Jean-François , Lodé Thierry
Published: September 2008

Woodland fragmentation through land consolidation practices (the merging of small fields by the removal of separating structures like hedgerows) is recognised as a major threat to biodiversity in Europe. While its impact on the occurrence of species has frequently been the object of focus, its impact on the movements of individuals has rarely been studied. We used paths of radio-tracked European pine martens ( Martes martes (L., 1758)), a forest-dwelling species, with fixes taken at 3 min intervals to determine their habitat use in fragmented landscape. Our results differ from those generally reported in the literature. Monitored individuals were not confined to large forests, and made additional use of small wood plots and hedgerows. Indeed, individuals moved faster in forests than in all other habitat types, which suggests that martens preferentially foraged in small woods, edges, and hedgerows. Roads and buildings were not avoided; fields, however, were avoided, although they did not act as barriers. Martens stayed close to forest cover when venturing into open ground, which suggests that although not restricted to forests, pine martens exhibit a certain dependence on the presence of trees in the vicinity.
Modelling the partially unknown distribution of wall lizards (Podarcis) in North Africa: ecological affinities, potential areas of occurrence, and methodological constraints
Authors: Kaliontzopoulou A. , Brito J. C. , Carretero M. A. , Larbes S. , Harris D. J.
Published: September 2008

Species distribution modelling (SDM) is a powerful tool to investigate various biological questions with a spatial component, but is also sensitive to presence-data characteristics, particularly data precision and clustering. Here, we investigate the effect of these two factors on SDM using Maxent as the modelling technique and wall lizards (genus Podarcis Wagler, 1830) from North Africa as a model system. Podarcis are not ubiquitous in Africa as they are in Europe, but their ecological and distributional characteristics in this area are poorly known. Our results show that the most important environmental factors related to the distribution of this genus in North Africa are humidity, habitat type, and temperature. The areas of potential distribution predicted by models based on data sets with different precision and clustering characteristics show high relatedness to coastal areas and mountain ranges and extend to areas were presence records for these lizards are lacking. Our comparison of models based on different data sets indicates that finer scale models, even if based on fewer presence locations, outperform coarser scale ones. Data clustering does not have a negative effect on model performance, but is rather overcome by sample-size effects. Similar approaches may be of general application to other stenoic species for which available locations are scarce in comparison with the extension of the study area.
Population structure and stock identification of chum salmon (Oncorhynchus keta) from British Columbia determined with microsatellite DNA variation
Authors: Beacham Terry D. , Spilsted Brian , Le Khai D. , Wetklo Michael
Published: September 2008

Variation at 14 microsatellite loci was surveyed in 205 populations of chum salmon ( Oncorhynchus keta (Walbaum in Artedi, 1792)) from British Columbia to determine population structure and the possible application of microsatellites to estimate stock composition of chum salmon in mixed-stock fisheries. The genetic differentiation index (FST) over all populations and loci was 0.016, with individual locus values ranging from 0.006 to 0.059. Sixteen regional stocks were defined in British Columbia for stock identification applications. Analysis of simulated fishery samples suggested that accurate and precise regional estimates of stock composition should be produced when the microsatellites were used to estimate stock compositions. The main stocks that constitute the October 2007 samples of migrating chum salmon through Johnstone Strait in southern British Columbia were Fraser River (45%–64%), southern British Columbia mainland (22%), and east coast Vancouver Island (13%–28%), within the range of those to be expected in samples from Johnstone Strait. Microsatellites have the ability to provide fine-scale resolution of stock composition in British Columbia coastal fisheries.