bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of the distorted wave Born approximation to predict scattering by inhomogeneous objects: Application to squid
Authors: Jones Benjamin A. , Lavery Andone C. , Stanton Timothy K.
Published: January 2009

A new method has been developed to predict acoustic scattering by weakly scattering objects with three-dimensional variability in sound speed and density. This variability can take the form of inhomogeneities within the body of the scatterer and/or geometries where the acoustic wave passes through part of the scattering body, into the surrounding medium, and back into the body. This method applies the distorted wave Born approximation (DWBA) using a numerical approach that rigorously accounts for the phase changes within a scattering volume. Ranges of validity with respect to material properties and numerical considerations are first explored through comparisons with modal-series-based predictions of scattering by fluid-filled spherical and cylindrical fluid shells. The method is then applied to squid and incorporates high resolution spiral computerized tomography (SCT) scans of the complex morphology of the organism. Target strength predictions based on the SCT scans are compared with published backscattering data from live, freely swimming and tethered squid. The new method shows significant improvement for both single-orientation and orientation-averaged scattering predictions over the DWBA-homogeneous-prolate-spheroid model.
Masking release for low- and high-pass-filtered speech in the presence of noise and single-talker interference
Authors: Oxenham Andrew J. , Simonson Andrea M.
Published: January 2009

Speech intelligibility was measured for sentences presented in spectrally matched steady noise, single-talker interference, or speech-modulated noise. The stimuli were unfiltered or were low-pass (LP) (1200Hz cutoff) or high-pass (HP) (1500Hz cutoff) filtered. The cutoff frequencies were selected to produce equal performance in both LP and HP conditions in steady noise and to limit access to the temporal fine structure of resolved harmonics in the HP conditions. Masking release, or the improvement in performance between the steady noise and single-talker interference, was substantial with no filtering. Under LP and HP filtering, masking release was roughly equal but was much less than in unfiltered conditions. When the average F0 of the interferer was shifted lower than that of the target, similar increases in masking release were observed under LP and HP filtering. Similar LP and HP results were also obtained for the speech-modulated-noise masker. The findings are not consistent with the idea that pitch conveyed by the temporal fine structure of low-order harmonics plays a crucial role in masking release. Instead, any reduction in speech redundancy, or manipulation that increases the target-to-masker ratio necessary for intelligibility to beyond around 0dB, may result in reduced masking release.
Behavioral responses of herring (Clupea harengus) to 1–2 and 6–7kHz sonar signals and killer whale feeding sounds
Authors: Doksæter Lise , Rune Godø Olav , Olav Handegard Nils , Kvadsheim Petter H. , Lam Frans-Peter A. , Donovan Carl , Miller Patrick J. O.
Published: January 2009

Military antisubmarine sonars produce intense sounds within the hearing range of most clupeid fish. The behavioral reactions of overwintering herring (Clupea harengus) to sonar signals of two different frequency ranges (1–2 and 6–7kHz), and to playback of killer whale feeding sounds, were tested in controlled exposure experiments in Vestfjorden, Norway, November 2006. The behavior of free ranging herring was monitored by two upward-looking echosounders. A vessel towing an operational naval sonar source approached and passed over one of them in a block design setup. No significant escape reactions, either vertically or horizontally, were detected in response to sonar transmissions. Killer whale feeding sounds induced vertical and horizontal movements of herring. The results indicate that neither transmission of 1–2kHz nor 6–7kHz have significant negative influence on herring on the received sound pressure level tested (127–197 and 139–209dBrms re 1μPa, respectively). Military sonars of such frequencies and source levels may thus be operated in areas of overwintering herring without substantially affecting herring behavior or herring fishery. The avoidance during playback of killer whale sounds demonstrates the nature of an avoidance reaction and the ability of the experimental design to reveal it.
Effects of obstruent consonants on fundamental frequency at vowel onset in English
Authors: Hanson Helen M.
Published: January 2009

When a vowel follows an obstruent, the fundamental frequency in the first few tens of milliseconds of the vowel is known to be influenced by the voicing characteristics of the consonant. This influence was re-examined in the study reported here. Stops, fricatives, and the nasal /m/ were paired with the vowels /i,ɑ/ to form CVm syllables. Target syllables were embedded in carrier sentences, and intonation was varied to produce each syllable in either a high, low, or neutral pitch environment. In a high-pitch environment, F0 following voiceless obstruents is significantly increased relative to the baseline /m/, but following voiced obstruents it closely traces the baseline. In a low-pitch environment, F0 is very slightly increased following all obstruents, voiced and unvoiced. It is suggested that for certain pitch environments a conflict can occur between gestures corresponding to the segmental feature [stiff vocal folds] and intonational elements. The results are different acoustic manifestations of [stiff] in different pitch environments. The spreading of the vocal folds that occurs during unvoiced stops in certain contexts in English is an enhancing gesture, which aids the resolution of the gestural conflict by allowing the defining segmental gesture to be weakened without losing perceptual salience.
The relationship between pitch discrimination and vocal production: Comparison of vocal and instrumental musicians
Authors: Nikjeh Dee A. , Lister Jennifer J. , Frisch Stefan A.
Published: January 2009

Auditory pitch discrimination and vocal pitch accuracy are fundamental abilities and essential skills of a professional singer; yet, the relationship between these abilities, particularly in trained vocal musicians, has not been the subject of much research. Difference limens for frequency (DLFs) and pitch production accuracy (PPA) were examined among 20 vocalists, 21 instrumentalists, and 21 nonmusicians. All were right-handed young adult females with normal hearing. Stimuli were harmonic tone complexes simulating piano tones and represented the mid-frequency of the untrained female vocal range, F0=261.63–392Hz (C4–G4). DLFs were obtained by an adaptive psychophysical paradigm. Vocal pitch recordings were analyzed to determine PPA. Musicians demonstrated superior pitch discrimination and production accuracy compared to nonmusicians. These abilities did not distinguish instrumentalists and vocalists. DLF and PPA were significantly correlated with each other only for musicians with instrumental training; however, PPA was most consistent with minimal variance for vocalists. It would appear that a relationship between DLF and PPA develops with musical training, and these abilities can be differentially influenced by the type of specialty training.
The prolate spheroidal wave functions as invariants of the time reversal operator for an extended scatterer in the Fraunhofer approximation
Authors: Robert Jean-Luc , Fink Mathias
Published: January 2009

The decomposition of the time reversal operator, known by the French acronym DORT, is widely used to detect, locate, and focus on scatterers in various domains such as underwater acoustics, medical ultrasound, and nondestructive evaluation. In the case of point-scatterers, the theory is well understood: The number of nonzero eigenvalues is equal to the number of scatterers, and the eigenvectors correspond to the scatterers Green’s function. In the case of extended objects, however, the formalism is not as simple. It is shown here that, in the Fraunhofer approximation, analytical solutions can be found and that the solutions are functions called prolate spheroidal wave-functions. These functions have been studied in information theory as a basis of band-limited and time-limited signals. They also arise in optics. The theoretical solutions are compared to simulation results. Most importantly, the intuition that for an extended objects, the number of nonzero eigenvalues is proportional to the number of resolution cell in the object is justified. The case of three-dimensional objects imaged by a two-dimensional array is also dealt with. Comparison with previous solutions is made, and an application to super-resolution of scatterers is presented.
Three-dimensional propagation and scattering around a conical seamount
Authors: Luo Wenyu , Schmidt Henrik
Published: January 2009

A three-dimensional (3D) propagation and scattering model is developed for an offset acoustic source in an ocean with axisymmetric bathymetry. Based on the same theoretical foundation as the formulation presented by Taroudakis [M. I. Taroudakis, “A coupled-mode formulation for the solution in the presence of a conical sea-mount,” J. Comput. Acoust. 4, 101–121 (1996)], the present approach combines a spectral decomposition in azimuth with a coupled-mode theory for two-way, range-dependent propagation. However, the earlier formulations were severely limited in terms of frequency, size, and geometry of the seamount, the seabed composition, and the distance between the source and the seamount, and were therefore severely limited in regard to realistic seamount problems. Without changing the fundamental theoretical foundation, the present approach applies a number of modifications to the numerical formulation, leading to orders of magnitude in numerical efficiency for realistic problems. Further, by using a standard normal mode model for determining the fundamental modal solutions and coupling matrices, and by applying a simple superposition principle, the computational requirements are made independent of the distance between the seamount and the source and receivers, and dependent only on the geometry of the seamount and the source frequency. Therefore, realistic propagation and scattering scenarios can be modeled, including effects of seamount roughness and realistic sedimentary structure.
Benchmark problems for acoustic scattering from elastic objects in the free field and near the seafloor
Authors: Zampolli Mario , Jensen Finn B. , Tesei Alessandra
Published: January 2009

Results from a workshop organized in 2006 to assess the state of the art in target scatter modeling are presented. The problem set includes free-field scenarios as well as scattering from targets that are proud, half-buried, or fully buried in the sediment. The targets are spheres and cylinders, of size O(1m), which are insonified by incident plane waves in the low-frequency band 0.1–10kHz. In all cases, the quantity of interest is the far-field target strength. The numerical techniques employed fall within three classes: (i) finite-element (FE) methods and (ii) boundary-element (BE) techniques, with different approaches to computing the far field via discretizations of the Helmholtz–Kirchhoff integral in each case, and (iii) semianalytical methods. Reference solutions are identified for all but one of the seven test problems considered. Overall, FE- and BE-based models emerge as those being capable of treating a wider class of problems in terms of target geometry, with the FE method having the additional advantage of being able to deal with complex internal structures without much additional effort. These capabilities are of value for the study of experimental scenarios, which can essentially be envisioned as variations of the problem set presented here.
Identification of synthetic vowels based on selected vocal tract area functions
Authors: Bunton Kate , Story Brad H.
Published: January 2009

The purpose of this study was to determine the degree to which synthetic vowel samples based on previously reported vocal tract area functions of eight speakers could be accurately identified by listeners. Vowels were synthesized with a wave-reflection type of vocal tract model coupled to a voice source. A particular vowel was generated by specifying an area function that had been derived from previous magnetic resonance imaging based measurements. The vowel samples were presented to ten listeners in a forced choice paradigm in which they were asked to identify the vowel. Results indicated that the vowels [i], [æ], and [u] were identified most accurately for all of speakers. The identification errors of the other vowels were typically due to confusions with adjacent vowels.
Reflection of underwater sound from surface waves
Authors: Tindle Chris T. , Deane Grant B. , Preisig James C.
Published: January 2009

A tank experiment has been conducted to measure reflection of underwater sound from surface waves. Reflection from a wave crest leads to focusing and caustics and results in rapid variation in the received waveform as the surface wave moves. Theoretical results from wavefront modeling show that interference of three surface reflected eigenrays for each wave crest produces complicated interference waveforms. There is good agreement between theory and experiment even on the shadow side of caustics where there are two surface reflected arrivals but only one eigenray.
Lexical and indexical cues in masking by competing speech
Authors: Helfer Karen S. , Freyman Richard L.
Published: January 2009

Three experiments were conducted using the TVM sentences, a new set of stimuli for competing speech research. These open-set sentences incorporate a cue name that allows the experimenter to direct the listener’s attention to a target sentence. The first experiment compared the relative efficacy of directing the listener’s attention to the cue name versus instructing the subject to listen for a particular talker’s voice. Results demonstrated that listeners could use either cue about equally well to find the target sentence. Experiment 2 was designed to determine whether differences in intelligibility among talkers’ voices that were noted when three utterances were presented together persisted when each talker’s sentences were presented in steady-state noise. Results of experiment 2 showed only minor intelligibility differences between talkers’ utterances presented in noise. The final experiment considered how providing accurate and inaccurate information about the target talker’s voice influenced speech recognition performance. This voice cue was found to have minimal effect on listeners’ ability to understand the target utterance or ignore a masking voice.
T
-matrix methods in acoustic scattering
Authors: Waterman P. C.
Published: January 2009

Some further refinements are described for the T-matrix approach to acoustic scattering. From the structure of the matrices involved, one can infer the Rayleigh limit explicitly for objects having no density contrast. One finds TRay=iR−R2, where the R-matrix involves integrals of the regular spherical wave functions over the object’s surface. The index of refraction and loss factor can be chosen as desired, and energy balance and reciprocity requirements are found to be met. The derivation can be extended to obtain the Rayleigh expansion, effectively describing T as a series in ascending powers of the ratio of object size to wavelength. In trial cases, the series converges throughout the Rayleigh region and somewhat beyond. Bodies of high aspect ratio are also considered, where difficulties arise due to precision loss during numerical integration. Loss ranges from 4 or 5 significant figures (2:1 spheroid) to 22 figures (40:1 spheroid) or more. A class of surfaces has been found for which this problem can be avoided, however, enabling one to treat a variety of body shapes up to aspect ratios of 100:1 with no difficulty.
Psychophysical and physiological measures of electrical-field interaction in cochlear implants
Authors: Hughes Michelle L. , Stille Lisa J.
Published: January 2009

The primary purpose of this study was to determine whether the electrically evoked compound action potential (ECAP) can be used to predict psychophysical electrical-field interaction patterns obtained with simultaneous stimulation of intracochlear electrodes. The second goal was to determine whether ECAP patterns are affected by recording location because differences might influence the relation between ECAP and psychophysical measures. The third goal was to investigate whether symmetrical threshold shifts are produced with phase inversion of the interaction stimulus. Nine adults with Advanced Bionics cochlear implants participated. ECAP and psychophysical thresholds were obtained for basal, middle, and apical probe electrodes in the presence of a subthreshold interaction stimulus delivered simultaneously to each of seven to eight interaction electrodes per probe. The results showed highly significant correlations between ECAP and psychophysical threshold shifts for all nine subjects, which suggests that the ECAP can adequately predict psychophysical electrical-field interaction patterns for subthreshold stimuli. ECAP thresholds were significantly higher for recordings from the basal (versus apical) side of the probe, which suggests that recording location may affect relations between ECAP and psychophysical measures. Interaction stimulus phase inversion generally produced symmetrical threshold shifts for psychophysical measures but not for half of ECAP measures.
Speech recognition by bilateral cochlear implant users in a cocktail-party setting
Authors: Loizou Philipos C. , Hu Yi , Litovsky Ruth , Yu Gongqiang , Peters Robert , Lake Jennifer , Roland Peter
Published: January 2009

Unlike prior studies with bilateral cochlear implant users which considered only one interferer, the present study considered realistic listening situations wherein multiple interferers were present and in some cases originating from both hemifields. Speech reception thresholds were measured in bilateral users unilaterally and bilaterally in four different spatial configurations, with one and three interferers consisting of modulated noise or competing talkers. The data were analyzed in terms of binaural benefits including monaural advantage (better-ear listening) and binaural interaction. The total advantage (overall spatial release) received was 2–5dB and was maintained with multiple interferers present. This advantage was dominated by the monaural advantage, which ranged from 1to6dB and was largest when the interferers were mostly energetic. No binaural-interaction benefit was found in the present study with either type of interferer (speech or noise). While the total and monaural advantage obtained for noise interferers was comparable to that attained by normal-hearing listeners, it was considerably lower for speech interferers. This suggests that bilateral users are less capable of taking advantage of binaural cues, in particular, under conditions of informational masking. Furthermore, the use of noise interferers does not adequately reflect the difficulties experienced by bilateral users in real-life situations.
Sex differences in distortion-product and transient-evoked otoacoustic emissions compared
Authors: McFadden Dennis , Martin Glen K. , Stagner Barden B. , Maloney Mindy M.
Published: January 2009

Although several studies have documented the existence of sex differences in spontaneous otoacoustic emissions (SOAEs) and transient-evoked OAEs (TEOAEs) in humans, less has been published about sex differences in distortion-product OAEs (DPOAEs). Estimates of sex and ear differences were extracted from a data set of OAE measurements previously collected for other purposes. In accord with past findings, the sex differences for TEOAEs were substantial for both narrowband and wideband measures. By contrast, the sex differences for DPOAEs were about half the size of those for TEOAEs. In this sample, the ear differences were small for TEOAEs in both sexes and absent for DPOAEs. One implication is that the cochlear mechanisms underlying DPOAEs appear to be less susceptible to whatever influences are responsible for producing sex differences in TEOAEs and SOAEs in humans. We discuss the possibility that differences in the effective level of the stimuli may contribute to these outcomes.
Critical bands and critical ratios in animal psychoacoustics: An example using chinchilla data
Authors: Yost William A. , Shofner William P.
Published: January 2009

This paper suggests that critical ratios obtained in noise-masked tone studies are not good indicators of critical bandwidths obtained in both human and nonhuman animal subjects. A probe-tone detection study using chinchilla subjects suggests that they may be broadband processors in detection tasks as opposed to human subjects who use narrow-band, critical-band processing. If chinchilla and other nonhuman animal subjects are wideband processors, this can partially explain why their critical ratios are significantly greater than those measured in human subjects. Thus, large critical ratios obtained for nonhuman animals may indicate processing inefficiency rather than wide critical bands.
Threshold fine structure affects amplitude modulation perception
Authors: Heise Stephan J. , Mauermann Manfred , Verhey Jesko L.
Published: January 2009

Modulation detection thresholds of a sinusoidally amplitude-modulated tone were measured for two different positions of the low-level carrier relative to the fine structure of the threshold in quiet. Modulation detection thresholds were higher for a carrier at a fine-structure minimum than for a carrier at a fine-structure maximum, regardless of whether the carriers had the same sound pressure level or the same sensation level. This indicates that even for small variations of the carrier frequency, the sensitivity to amplitude modulation can vary substantially due to the frequency characteristics of the threshold in quiet.
Immunohistochemical evidence of local production of catecholamines in cells of the muscle origins at the lateral and medial humeral epicondyles: of importance for the development of tennis and golfer’s elbow?
Authors: Zeisig E , Ljung B-O , Alfredson H , Danielson P
Published: January 2009

Background:

Tennis elbow (TE) is a painful condition affecting the common extensor origin at the lateral humeral epicondyle. Colour Doppler examination has shown increased blood flow at this site and the sensory, and sympathetic innervation patterns have been delineated. However, it is not known whether there is local production of catecholamines and/or acetylcholine in this tissue, which is the case in patellar and Achilles tendinopathies.

Objective:

To investigate the possible presence of local production of catecholamines and acetylcholine in non-neuronal cells (fibroblasts) in connective tissue at the muscle origin at the lateral humeral epicondyle in patients with TE.

Design:

Immunohistochemical studies were performed on biopsies taken from the extensor origin in patients with TE and in pain-free controls. For reference purpose, biopsies from the flexor origin in patients with golfer’s elbow (GE) were also studied.

Patients:

Seven patients with TE and four patients with GE. Six healthy asymptomatic individuals served as controls.

Method:

Immunohistochemistry, using antibodies detecting synthesising enzymes for catecholamines (tyrosine hydroxylase; TH) and acetylcholine (choline acetyltransferase; ChAT).

Results:

TH-like immunohistochemical reactions were seen in fibroblasts in four of the seven patients with TE and two of the four patients with GE. No such reactions were detected in controls (0/6). No ChAT reactions were seen in any of the investigated specimens.

Conclusions:

There is evidence of local, non-neuronal production of catecholamines, but not acetylcholine, in fibroblasts in the tissue at the muscle origin at the lateral and medial epicondyles in patients with TE and GE, respectively, which might have an influence on blood vessel regulation and pain mechanisms in these conditions.
Drug-induced cutaneous pathology
Authors: Ramdial P K , Naidoo D K
Published: January 2009

Drug-induced cutaneous rashes, whether confined to the skin or part of a systemic disease, are characterised by a spectrum of inflammatory disease patterns that include perivascular dermatitis, nodular and diffuse dermatitis, vesiculobullous lesions, pustular eruptions, sclerodermoid reactions, vasculitis, folliculitis/perifolliculitis and panniculitis. While a single drug can elicit a range of reaction patterns, no reaction pattern is specific for a particular drug. Although the temporal link between initiation of drug therapy and the onset of the drug rash is critical to the diagnosis, drug reactions may also occur during the course of chronic drug ingestion. Clues to the drug-induced nature of the cutaneous eruption include the presence of overlapping histological reaction patterns and incongruent clinical and histopathological features. While eosinophils are an important tell-tale sign of a drug-induced reaction, they may also be conspicuous in skin rashes devoid of a drug association. Furthermore, eosinophils may be sparse or absent in some drug exanthems. Heightened awareness of the mimicry of a wide spectrum of cutaneous pathology by an ever-increasing range of therapeutic agents is pivotal to the diagnosis of drug-induced skin pathology.
A transfer coefficient method for rock slope toppling
Authors: Liu C.H. , Jaksa M.B. , Meyers A.G.
Published: January 2009

A common block toppling mode is adopted for analysing toppling stability of rock slopes. A transfer coefficient method is developed based on Goodman and Bray’s kinematic model, by introducing two parameters: the transfer coefficient and equivalent toppling weight, which, given the geometrical and geotechnical parameters of the slope, can be determined as functions of the relative position of the block to the slope crest. Accounting for the case that the block base is not normal to the dominant discontinuities, the arithmetic is extended. The method describes a concise relationship between the normal force of the blocks and their weight represented by their equivalent toppling weight. The analysis process is formulated and easily implemented. A spreadsheet procedure is presented and a typical case is illustrated. It is demonstrated that the transfer coefficient method provides a considerably straightforward means for analysing block toppling of rock slopes and is computationally very efficient.
Direct measurement of matric suction in triaxial tests on early-age cemented paste backfill
Authors: Simms Paul , Grabinsky Murray
Published: January 2009

Hydration occurring in cemented paste backfill (CPB) is shown to generate matric suction through self-desiccation. This complicates determination of the water-retention curve and mechanical properties during curing, which are important in stope design, and renders problematic the use of axis-translation testing procedure to control suctions in strength testing. An alternative is to monitor suction directly during testing. To this end, a miniature tensiometer is inserted into the base of a triaxial cell. A series of unconfined and confined tests are performed on early-age (less than two weeks old) CPB. The observed behaviour is similar to that observed in weakly cemented soils, showing a distinct tendency to dilate during shearing.
A geophysical and geotechnical study to determine the hydrological regime of the Central Manitoba gold mine tailings deposit
Authors: Sherriff Barbara L. , Ferguson Ian J. , Gupton Michael W. , VanGulck Jamie F. , Sidenko Nikolay , Priscu Caius , Pérez-Flores Marco , Gómez-Treviño Enrique
Published: January 2009

Extraction of gold from quartz–carbonate shear zones has left a barren deposit of tailings at Central Manitoba mine, which remains unchanged after 70 years. In this study, the shape of the basin, the groundwater and surface water flow regime, and the electrical conductivity of the tailings have been delineated using a combination of geotechnical, geophysical, and geochemical techniques. Groundwater and surface water flow from the north–south-fractured bedrock outwards to the east and west. A component of upward groundwater movement in the deposit is due to evaporation in hot, dry summers, limited recharge from precipitation, and the tailings basin being a local groundwater discharge zone. Electromagnetic surveys indicate that the thickness of the tailings and underlying peat bog material increases from ∼1 m at the south of the tailings to ∼5 m at the north. The surveys provided an effective way of mapping the spatial distribution of acidic pore fluids and associated increased salinity. Zones of acidification, occurring mainly on the south side of the tailings, support the hypothesis that acidification is due to differential settling during the initial discharge of carbonate and sulfide minerals.
Development of a technically defensible soil gas sampling strategy for vapour intrusion assessments
Authors: Wong Tai T. , Agar John G.
Published: January 2009

Soil vapour intrusion is now commonly evaluated as part of human health risk assessments at contaminated sites where buildings or other structures are located in close proximity to volatile organic chemicals (VOCs) in subsurface soils and groundwater. Investigation of the vapour intrusion pathway often requires that VOC concentrations in the soil gas adjacent to buildings and structures be characterized as part of the risk assessment process. This paper presents the design of a new soil gas monitoring well and a sampling procedure that effectively eliminate concerns about soil gas sample dilution due to short-circuiting of atmospheric air and help to ensure the collection of representative soil gas samples. The results of a parametric numerical modelling study that was applied to address the air short-circuiting issue and the technical rationale for the new soil gas monitoring well (SGMW) design are presented in this paper along with recommended soil gas sampling procedures in various soil conditions. The SGMW design rationale and methodology outlined in this paper considered the effects of soil moisture content and permeability, the depth to the sampling screen interval, and the soil gas sample extraction rate.
Impact of three silvicultural treatments on weevil incidence, growth, phenology, and branch-level dynamics of Pinus strobus from large and small populations
Authors: Major John E. , Mosseler Alex , Barsi Debby C. , Clouthier Amanda , Campbell Moira
Published: January 2009

Our goal was to quantify tree- and branch-level components of growth response to three silvicultural treatments (STs), and weevil incidence in white pine ( Pinus strobus L.) from large, central populations in Ontario (ON) versus small, isolated populations in Newfoundland (NL). Light levels were 100%, 42.0%, and 20.4% transmittance for the full-sun, intermediate-shade, and high-shade STs. After 8 years, the overall incidence of weevil infestation was 42.1%, 23.4%, and 13.7% for the full-sun, intermediate-shade, and high-shade STs, respectively (P < 0.001). Weevil impact on total height and volume averaged –13.2% and –11.8%. Analysis of dominant lateral shoots showed that ON populations had 32% longer shoots than the NL populations. Bud set difference was a primary determinant of shoot-length growth differences between regions: Julian days 171 and 184 for the NL and ON populations, respectively. The primary determining factors related to shoot length were the number of needle bundles and region, driven by light levels and day length, respectively, and the internode length, probably through inbreeding effects. Total height and diameter showed a positive curvilinear relationship to light level. To maximize fitness, NL conservation strategies should also now consider introducing adaptive trait variation in the context of anticipated climate change.
Epiphytic bryophytes in Canarian subtropical montane cloud forests: the importance of the time since disturbance and host identity
Authors: Patiño Jairo , González-Mancebo Juana M. , Fernández-Palacios José M.
Published: January 2009

The aim of this study was to determine the short- and medium-term effects of forestry practices on epiphytic bryophyte communities growing on whole trees of three host species ( Erica arborea L., Laurus novocanariensis Rivas-Mart., Lousa, Fern. Prieto, E. Días, J.C. Costa & C. Aguilar, Myrica faya Aiton) in subtropical montane cloud forests on La Palma (Canary Islands, Spain). Specifically, we investigated differences in temporal and spatial shifts of species composition and richness of phylogenetic groupings among host species. The most common harvest method in the study area is clear-cutting. Four different postharvest successional stages (8, 15, 25, and 60 years after harvest) were studied. Temporal bryophyte species turnover varied according to host species. Most of the later-successional bryophytes with narrower ecological requirements had low abundances on L. novocanariensis; this host experienced a gradual increase of epiphytic richness along the chronosequence. Temporal changes for E. arborea and M. faya were different; they showed increasing richness during the second period (15–25 years) followed by a drop in richness during the last period (25–60 years), and early-successional species dominated throughout the chronosequence. We conclude that the protection of “old-growth stands” containing trees of selected species can contribute to the survival of epiphytic bryophytes in managed cloud-forest landscapes.
Differences in wood decay by Heterobasidion parviporum in cloned Norway spruce (Picea abies)
Authors: Puentes Rodriguez Y. , Zubizarreta Gerendiain A. , Pappinen A. , Peltola H. , Pulkkinen P.
Published: January 2009

In forest breeding, growth has been used as the main selection trait in Norway spruce (Picea abies L. Karst.), whereas wood properties or resistance to pathogens have been taken as secondary traits. We aimed to investigate, in laboratory conditions, the rate of wood decay caused by Heterobasidion parviporum (Fr.) Niemelä & Korhonen (strains 5 and 7) in 20 Norway spruce clones. We also studied if, on average, growth, wood density, and fibre properties differed in the most and least decayed clones as well as from pith to bark. After 6 months of incubation, strain 7 effected significantly higher wood decay than strain 5 (mean 16.9% and 1.7%, respectively). The difference between the five most decayed and five least decayed clones by strain 7 was also statistically significant (P < 0.05). Moreover, regardless of clone or strain, the wood decay was highest near the pith and lowest near the bark, which is the opposite for wood density and fibre length and width. However, neither wood density nor fibre properties explained, statistically, the differences in average wood decay and decay from pith to bark. On the other hand, we could identify clones that simultaneously provided high wood quantity and relatively high wood density and low decay rate.
Intensity of precommercial crop tree release increases diameter growth and survival of upland oaks
Authors: Ward Jeffrey S.
Published: January 2009

In 1988, seven study areas were established in Connecticut to examine the effects of precommercial crop tree release on development of sapling red oaks ( Quercus rubra L.) (n = 1250). Crown class at canopy closure, competition from adjacent trees for growing space and limited resources, and interaction of these factors were major determinants of survival, upper canopy persistence, and diameter growth over the 18 year period studied. Complete release from competition of neighboring trees, but not partial release, increased survival of intermediate and codominant stems. Complete release did not increase survival of oaks in the dominant crown class. Few intermediate and no suppressed oaks ascended into the upper canopy without crop tree release. Complete release doubled the proportion of codominant trees that remained in the upper canopy and increased the proportion of intermediates that ascended into the upper canopy. Complete release increased 18 year diameter growth only for dominant and codominant oaks. Because precommercial crop tree release simultaneously increases the probability that high-quality stems of desired species will be present in the mature stands and increases the diameter growth of those stems, this technique should be considered in stands with low oak densities.
Boreal forest provenance tests used to predict optimal growth and response to climate change: 2. Black spruce
Authors: Thomson Ashley M. , Riddell Claire L. , Parker William H.
Published: January 2009

Height, diameter, and survival data were obtained from 20 range-wide black spruce ( Picea mariana (Mill.) BSP) provenance trials established from 1973 to 1977. Population response functions based on February minimum temperatures were developed for 23 Ontario and Great Lakes states provenances to predict climate values maximizing height growth for individual seed sources. Site transfer functions based on February maximum temperatures and May maximum temperatures were developed for five test sites to predict climate values maximizing height growth for test locations. Contour lines representing optimal performance were fitted to current (1961–1990) and future (2041–2070) climate grids. For black spruce seed sources from the east of Lake Superior and Lake Huron, optimal height growth was achieved between 45° and 47°N; for the western sources optimal performance moved north between 46° and 48°N. In eastern Ontario, height growth of northern sources may increase with transfer to warmer environments and with future temperature increases. Central sources are currently growing at or close to optimum and will be negatively affected by increased future temperatures. Southern sources may currently benefit from transfer to cooler environments, and the effects of global warming may cause significant height growth loss and the potential extirpation of local populations.
FERMION FAMILY NUMBER AND THE Z–Z′ MIXING IN THE 3-3-1 MODEL WITH RIGHT-HANDED NEUTRINOS
Authors: COGOLLO D. , DINIZ H. , DE S. PIRES C. A. , RODRIGUES DA SILVA P. S.
Published: January 2009

Theoretical consistency of the 3-3-1 model with right-handed neutrinos demands that the number of family of fermions be exactly equal to three. In this brief report we show that such theoretical requirement results in a clean and severe bound on the Z–Z′ mixing angle: -3.979×10-3<ϕ<1.309×10-4 with 90% CL.
ADDENDUM: TELEPARALLEL ENERGY–MOMENTUM DISTRIBUTION OF LEWIS–PAPAPETROU SPACETIMES
Authors: SHARIF M. , JAMIL AMIR M.
Published: January 2009

In a recent paper,1 we missed some components of the contorsion tensor due to the minor error. When we insert the correction and use all the components, the final result becomes more comprehensive. Here we put the corrections and obtain the corresponding results.
DECONFINEMENT AND THERMODYNAMICS IN 5D HOLOGRAPHIC MODELS OF QCD
Authors: GÜRSOY UMUT
Published: January 2009

We review 5D holographic approaches to finite temperature QCD. Thermodynamic properties of the "hard-wall" and the "soft-wall" models are derived. Various non-realistic features in these models are rectified by the setup of improved holographic QCD, that we review here.
THE RELATIVISTIC BOUND AND SCATTERING STATES OF THE ECKART POTENTIAL WITH A PROPER NEW APPROXIMATE SCHEME FOR THE CENTRIFUGAL TERM
Authors: WEI GAO-FENG , DONG SHI-HAI , BEZERRA V. B.
Published: January 2009

The approximately analytical bound and scattering state solutions of the arbitrary l wave Klein–Gordon equation for mixed Eckart potentials are obtained through a proper new approximation to the centrifugal term. The normalized analytical radial wave functions of the l wave Klein–Gordon equation with the mixed Eckart potentials are presented and the corresponding energy equations for bound states and phase shifts for scattering states are derived. It is shown that the energy levels of the continuum states reduce to those of the bound states at the poles of the scattering amplitude. Two special cases — for the s wave and for l = 0 and β = 0 — are also studied, briefly.
DELAY-DEPENDENT STABILITY CRITERION FOR BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS WITH INTERVAL TIME-VARYING DELAYS
Authors: PARK JU H. , KWON O. M.
Published: January 2009

In the letter, the global asymptotic stability of bidirectional associative memory (BAM) neural networks with delays is investigated. The delay is assumed to be time-varying and belongs to a given interval. A novel stability criterion for the stability is presented based on the Lyapunov method. The criterion is represented in terms of linear matrix inequality (LMI), which can be solved easily by various optimization algorithms. Two numerical examples are illustrated to show the effectiveness of our new result.
PRIORITY BASED WIRELESS COMMUNICATIONS FOR HEALTH MONITORING ON HIGHWAYS
Authors: DURRESI ARJAN , DURRESI MIMOZA , BAROLLI LEONARD
Published: January 2009

We propose to use Inter Vehicle Communications as part of a distributed system for ubiquitous health monitoring of patients. The biomedical data will be collected by wearable health diagnostic devices, which include various types of sensors. When patients are traveling on highways, we propose to transmit the measured biomedical data towards the corresponding Health Monitoring Centers via an Inter Vehicle Communication Network, which will guarantee the needed reliability, especially in areas where other wireless communications are not available. In particular, it is important that the Inter Vehicle Communication Network provides different priorities to various types of messages, depending on their urgency. We extend, a previously proposed inter vehicle hierarchical routing protocol, with priority scheduling to provide the needed priority services. We study various scheduling techniques and compare their effects on the service.
DATA DISSEMINATION METHODS FOR TIME-CONSTRAINT APPLICATIONS IN MOBILE AD HOC NETWORKS
Authors: HARA TAKAHIRO , MADRIA SANJAY KUMAR
Published: January 2009

In mobile ad hoc networks (MANETs), data replication is essential for improving data availability. In our previous work, we proposed a few updated data dissemination methods to refresh old replicas efficiently in MANETs. These methods disseminate updated data items every time when owners of original data items update the items or every time two mobile hosts are newly connected with each other and this causes heavy traffic in the entire network. In this paper, we assume applications that periodically execute read operations with strict deadlines to data items and propose several alternative updated data dissemination methods. These methods reduce the traffic for data dissemination while keeping a high success ratio for read operations.
DESIGN OF FUZZY BASED MULTI-CONSTRAINED ROUTING PROTOCOL AND THE PERFORMANCE EVALUATION
Authors: ZUO JING , CHI XUEFEN , GUAN LIN , LI HONGXIA , AWAN IRFAN
Published: January 2009

Single-constrained QoS routing protocols have inherent defects when applied into wireless ad hoc networks. Due to a single constraint parameter is only considered, they can't always cope with the problems caused by the uncertainty of ad hoc networks well. They are not robust enough. In order to overcome the drawbacks of single-constrained QoS routing protocols and improve the Quality of Service (QoS) of ad hoc networks, this paper proposed a multi-constrained QoS routing protocol based on fuzzy logic. It is developed from Dynamic Source Routing (DSR). The proposed protocol is service-aware in the sense that it considers the QoS required by different types of services and takes different network state parameters as the constraint conditions for fuzzy based routing system. New route discovery procedure and novel route maintenance mechanism are designed to support corresponding QoS requirements. Speed of packets sending is also adjusted adaptively referring to the outputs of the proposed fuzzy system. Performance of the fuzzy based DSR protocol is measured and evaluated under different conditions. Simulation results show that the improved protocol has better QoS guarantee capabilities compared to single-constrained QoS routing protocols for large-scale networks in terms of lower delay, smoother delay variation and lower packet loss rate.
AN EFFICIENT NEIGHBOR-AWARE PROTOCOL FOR SNET FORMATION
Authors: SHELTAMI TAREK R.
Published: January 2009

A wireless mobile sensor network is a collection of wireless mobile hosts forming nodes that are communicating without the aid of any centralized administration or standard support services. Nodes are classified as sensor nodes and router. Some nodes act both as sensors and routers. While traditional MAC protocols must balance between throughput, delay, and fairness concerns, WSN MAC protocols place an emphasis on energy efficiency as well. Schedule-based MAC protocols have been proposed for WSN. A common theme through all these protocols is putting radios to a low-power "sleep mode" either periodically or whenever possible when a node is neither receiving nor transmitting. In this paper, we propose a novel cluster-based infrastructure creation protocol, namely: the Neighbor-Aware Clusterhead (NAC). We investigate the performance of the NAC protocol under different sleep scheduling protocols and compare it against another cluster-based protocol. In NAC protocol nodes are synchronized with their clusterheads and are allowed to go sleep mode in order to conserve their energy without degrading the performance of the network. The network is divided into clusters managed by a clusterhead. The simulation results show that NAC protocol has a good potential to be a good candidate protocol for SNET.
RESIDENTIAL SEGREGATION BY HILL-CLIMBING AGENTS ON THE POTENTIAL LANDSCAPE
Authors: SHIN JAE KYUN , FOSSETT MARK
Published: January 2009

Ethnic residential segregation is common in urban areas and is especially pronounced in metropolitan areas of the US. Many factors contribute to these residential patterns. The potential role of ethnic preferences has received increasing attention in recent years, but the development of theoretical models has been limited in many respects. This study seeks to extend the understanding of the possible role of ethnic preferences by investigating an agent-based model that introduces the concept of spatial potential — the desirability of particular spatial locations — as a competing preference. The distribution of spatial potential is varied from convex to concave distributions on the city landscape to investigate the resulting impact on patterns of segregation. Three types of zones are identified in the model city, namely the minority ghetto, the majority ring, and the integrated ring. The present model is considered to be an example of a discrete dynamic system that is characterized by its random move condition and its definition on the grid system. Insights from analytic approaches are explored in the context of the new dynamics to gain a better understanding of the emergent patterns of the system.
CENTRALITY AND PERIPHERALITY IN FILTERED GRAPHS FROM DYNAMICAL FINANCIAL CORRELATIONS
Authors: POZZI F. , DI MATTEO T. , ASTE T.
Published: January 2009

Minimum spanning trees and planar maximally filtered graphs are generated from correlations between the 300 most-capitalized NYSE stocks' daily returns, computed dynamically over moving windows of sizes between 1 and 12 months, in the period from 2001 to 2003. We study how different economic sectors differently populate the various regions of these graphs. We find that the financial sector is always at the center whereas the periphery is shared among different sectors. Four extremes are observed: stocks well-connected and central; stocks well-connected but at the same time peripheral; stocks poorly-connected but central; stocks poorly-connected and peripheral. Two principal components of centrality measures are individuated. The economic meaning of this hierarchical disposition is discussed.