bluuebunny/crossref_metadata_2025 huggingface dataset:
SELECTING INDIVIDUALS IN TEAM SETTINGS: THE IMPORTANCE OF SOCIAL SKILLS, PERSONALITY CHARACTERISTICS, AND TEAMWORK KNOWLEDGE
Authors: MORGESON FREDERICK P. , REIDER MATTHEW H. , CAMPION MICHAEL A.
Published: August 2005

Although work is commonly organized around teams, there is relatively little empirical research on how to select individuals in team‐based settings. The goal of this investigation was to examine whether 3 of the most commonly used selection techniques for hiring into traditional settings (a structured interview, a personality test, and a situational judgment test) would be effective for hiring into team settings. In a manufacturing organization with highly interdependent teams, we examined the relationships between social skills, several personality characteristics (Conscientiousness, Extraversion, Agreeableness, and Emotional Stability), teamwork knowledge, and contextual performance. Results indicate that each of these constructs is bivariately related to contextual performance in a team setting, with social skills, Conscientiousness, Extraversion, and teamwork knowledge incrementally predicting contextual performance (with a multiple correlation of .48). Implications of these results for selection in team and traditional settings are discussed.
IDENTIFICATION OF SALMONELLA‐INOCULATED BEEF USING A PORTABLE ELECTRONIC NOSE SYSTEM
Authors: BALASUBRAMANIAN S. , PANIGRAHI S. , LOGUE C.M. , MARCHELLO M. , SHERWOOD J.S.
Published: August 2005

A commercially available Cyranose‐320TM (Cyrano Sciences, Pasadena, CA) conducting polymer–based electronic nose system was used to analyze the volatile organic compounds emanating from vacuum‐packaged beef strip loins (Longissimus Lamborum) that were repackaged simulating retail store conditions and stored at 4 and 10°C after inoculating them with Salmonella Typhimurium. Two statistical techniques, i.e., linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA), were used to develop classification models from the collected sensor signals. The models were developed for the captured signals, which were scaled and not scaled. The performances of the developed models were validated by two different methods, leave‐one‐out cross validation and bootstrapping. The developed models classified the meat samples based on the Salmonella population into “No Salmonella” (microbial counts < 0.7 log10 cfu/g) and “Salmonella” (microbial counts ≥ 0.7 log10 cfu/g). Overall, scaling the signals improved the classification accuracies obtained. The quadratic discriminant‐based classification models validated by the bootstrapping technique performed better than the LDA‐based models. For the meat samples stored at 10°C, the highest classification accuracy obtained by the QDA method with bootstrapping validation was 80.5% when the signals were scaled. For the samples stored at 4°C, the QDA method provided the highest classification accuracy of 87.3% using bootstrapping validation. The results obtained prove that the electronic nose system could identify meat samples contaminated with S. Typhimurium at a population concentration level of 0.7–2.6 log10 cfu/g.
QUANTIFICATION OF ATTACHMENT STRENGTH OF SELECTED FOODBORNE PATHOGENS BY THE BLOT SUCCESSION METHOD
Authors: KIM T. , SILVA J.L.
Published: August 2005

Attachment strength of selected foodborne pathogens (Listeria monocytogenes, Listeria innocua, Listeria grayii, Salmonella Typhimurium , and Escherichia coli O157:H7) were quantified using the blot succession method. E. coli O157:H7 and S. Typhimurium had higher removal exponents than Listeria species. Regardless of initial cell number, L. monocytogenes had the lowest removal exponent (0.27), being the most difficult to remove from the glass surface. The other Listeria spp. had exponents of 0.38–0.52 while S. Typhimurium and E. coli O157:H7 had exponents of 0.9 or higher. This method can serve to quantify attachment or detachment strength on food contact surfaces or digestive tracts.
Metachronal propagation of motoneurone burst activation in isolated spinal cord of newborn rat
Authors: Cazalets Jean‐René
Published: August 2005

Adequate locomotor and postural activity in mammals results from the coordinated activation of assemblies of spinal cord networks. In order to assess the global functioning of spinal circuitry, multisite recordings were made from an isolated spinal cord preparation of the newborn rat. Motor activity, elicited in a disinhibited network by bath‐applying strychnine (glycinergic blocker) and bicuculline (GABAergic blocker), consisted of slow spontaneous bursting. Under these conditions, the recorded bursts were coordinated in 1: 1 relationships at all segmental levels. For each cycle, a leading segment initiated the activity that then propagated in a metachronal way through adjacent segments along the length of spinal cord. There was both regional non‐linearity and directional asymmetry in this burst propagation: motor bursts propagated most rapidly in the thoracic spinal cord and the rostro‐caudal wave travelled faster than the caudo‐rostral one. Propagation involved both long projecting fibres and local intersegmental connections. These results suggest that the mammalian spinal cord contains propriospinal pathways subserving a metachronal transmission of motor information and that normally it may be involved in coordinating various parts of the body. The simple model developed here could be useful in unravelling more general mechanisms of neuronal circuit coupling.
Molecular mechanisms of regulation of fast‐inactivating voltage‐dependent transient outward K+ current in mouse heart by cell volume changes
Authors: Wang Guan‐Lei , Wang Ge‐Xin , Yamamoto Shintaro , Ye Linda , Baxter Heather , Hume Joseph R. , Duan Dayue
Published: August 2005

The Kv4.2/4.3 channels are the primary subunits that contribute to the fast‐inactivating, voltage‐dependent transient outward K+ current (Ito,fast) in the heart. Ito,fast is the critical determinant of the early repolarization of the cardiac action potential and plays an important role in the adaptive remodelling of cardiac myocytes, which usually causes cell volume changes, during myocardial ischaemia, hypertrophy and heart failure. It is not known, however, whether Ito,fast is regulated by cell volume changes. In this study we investigated the molecular mechanism for cell volume regulation of Ito,fast in native mouse left ventricular myocytes. Hyposmotic cell swelling caused a marked increase in densities of the peak Ito,fast and a significant shortening in phase 1 repolarization of the action potential duration. The voltage‐dependent gating properties of Ito,fast were, however, not altered by changes in cell volume. In the presence of either protein kinase C (PKC) activator (12,13‐dibutyrate) or phosphatase inhibitors (calyculin A and okadaic acid), hyposmotic cell swelling failed to further up‐regulate Ito,fast. When expressed in NIH/3T3 cells, both Kv4.2 and Kv4.3 channels were also strongly regulated by cell volume in the same voltage‐independent but PKC‐ and phosphatase‐dependent manner as seen in Ito,fast in the native cardiac myocytes. We conclude that Kv4.2/4.3 channels in the heart are regulated by cell volume through a phosphorylation/dephosphorylation pathway mediated by PKC and serine/threonine phosphatase(s). These findings suggest a novel role of Kv4.2/4.3 channels in the adaptive electrical and structural remodelling of cardiac myocytes in response to myocardial hypertrophy, ischaemia and reperfusion.
Activation of olfactory‐type cyclic nucleotide‐gated channels is highly cooperative
Authors: Nache Vasilica , Schulz Eckhard , Zimmer Thomas , Kusch Jana , Biskup Christoph , Koopmann Rolf , Hagen Volker , Benndorf Klaus
Published: August 2005

Cyclic nucleotide‐gated (CNG) ion channels play a key role in the sensory transduction of vision and olfaction. The channels are opened by the binding of cyclic nucleotides. Native olfactory CNG channels are heterotetramers of CNGA2, CNGA4, and CNGB1b subunits. Upon heterologous expression, only CNGA2 subunits can form functional homotetrameric channels. It is presently not known how the binding of the ligands to the four subunits is translated to channel opening. We studied activation of olfactory CNG channels by photolysis‐induced jumps of cGMP or cAMP, two cyclic nucleotides with markedly different apparent affinity. It is shown that at equal degree of activation, the activation time course of homotetrameric channels is similar with cGMP and cAMP and it is also similar in homo‐ and heterotetrameric channels with the same cyclic nucleotide. Kinetic models were globally fitted to activation time courses of homotetrameric channels. While all models containing equivalent binding sites failed, a model containing three binding sites with a ligand affinity high–low–high described the data adequately. Only the second binding step switches from a very low to a very high open probability. We propose a unique gating mechanism for homotetrameric and heterotetrameric channels that involves only three highly cooperative binding steps.
Neuropeptide Y bioavailability is suppressed in the hindlimb of female Sprague‐Dawley rats
Authors: Jackson Dwayne N. , Milne Kevin J. , Noble Earl G. , Shoemaker J. Kevin
Published: August 2005

We recently reported that male, but not female, rats exhibit basal endogenous neuropeptide Y Y1‐receptor modulation of hindlimb vasculature. The lack of baseline endo‐genous Y1‐receptor control in females was evident despite the expression of Y1‐receptors and neuropeptide Y in hindlimb skeletal muscle tissue. The following study addressed the hypothesis that neuropeptide Y bioavailability is blunted in female rats under baseline conditions. It was further hypothesized that enhanced prejunctional autoinhibitory neuropeptide Y Y2‐receptor expression and/or proteolytic processing of released neuropeptide Y may persist in female rats. Using western blot analysis, it was observed that females had greater overall neuropeptide Y Y2‐receptor expression in skeletal muscle compared to males (P < 0.05). To address the prevalence/impact of baseline endogenous Y2‐receptor activation on neuropeptide Y release in hindlimb vasculature, an arterial infusion of BIIE0246 (specific non‐peptide Y2‐receptor antagonist; 170 μg kg−1) was carried out on female and male rats. Y2‐receptor blockade resulted in a decrease in hindlimb vascular conductance in females and males (P < 0.05). However, the BIIE0246‐induced decrease in vascular conductance was Y1‐receptor dependent in females, but not males (P < 0.05). In addition, compared to baseline, BIIE0246 infusion resulted in increased plasma neuropeptide Y concentration in females (P < 0.05), while there was no observable change in males. In a final experiment, systemic inhibition of proteolytic enzymes dipeptidylpeptidase IV (via 500 nm diprotin A) and aminopeptidase P (via 180 nm 2‐mercaptoethanol) elicited a Y1‐receptor‐dependent decrease in hindlimb vascular conductance in females (P < 0.05). It was concluded that our previously reported lack of basal endogenous Y1‐receptor activation in female hindlimb vasculature was (at least partially) due to prejunctional Y2‐receptor autoinhibition and proteolytic processing of neuropeptide Y.
Isolation and validation of human prepubertal skeletal muscle cells: maturation and metabolic effects of IGF‐I, IGFBP‐3 and TNFα
Authors: Grohmann Malcolm , Foulstone Emily , Welsh Gavin , Holly Jeff , Shield Julian , Crowne Elizabeth , Stewart Claire
Published: August 2005

We have developed a primary skeletal muscle cell culture model derived from normal prepubertal children to investigate the effects of insulin‐like growth factor‐I (IGF‐I), insulin‐like growth factor binding protein‐3 (IGFBP‐3) and tumour necrosis factor α (TNFα) on growth, differentiation and metabolism. Cells of myoblast lineage were characterized morphologically by desmin staining and differentiated successfully into multinucleated myotubes. Differentiation was confirmed biochemically by an increase in creatine kinase (CK) activity and IGFBP‐3 secretion over time. IGF‐I promoted whilst TNFα inhibited myoblast proliferation, differentiation and IGFBP‐3 secretion. IGF‐I partially rescued the cells from the inhibiting effects of TNFα. Compared to adult myoblast cultures, children's skeletal muscle cells demonstrated higher basal and day 7 CK activities, increased levels of IGFBP‐3 secretion, diminished IGF‐I/TNFα action and absence of the inhibitory effect of exogenous IGFBP‐3 on differentiation. Additional studies demonstrated that TNFα increased basal glucose transport via GLUT1, nitric oxide synthase and p38MAPK‐dependent mechanisms. These studies provide baseline data to study the interactivity effects of growth factors and cytokines on differentiation and metabolism in muscle in relation to important metabolic disorders such as obesity, type II diabetes or chronic wasting diseases.
Carbachol induces burst firing of dopamine cells in the ventral tegmental area by promoting calcium entry through L‐type channels in the rat
Authors: Zhang Lei , Liu Yudan , Chen Xihua
Published: August 2005

Enhanced activity of the central dopamine system has been implicated in many psychiatric disorders including schizophrenia and addiction. Besides terminal mechanisms that boost dopamine levels at the synapse, the cell body of dopamine cells enhances terminal dopamine concentration through encoding action potentials in bursts. This paper presents evidence that burst firing of dopamine cells in the ventral tegmental area was under cholinergic control using nystatin‐perforated patch clamp recording from slice preparations. The non‐selective cholinergic agonist carbachol excited the majority of recorded neurones, an action that was not affected by blocking glutamate and GABA ionotropic receptors. Twenty per cent of dopamine cells responded to carbachol with robust bursting, an effect mediated by both muscarinic and nicotinic cholinoceptors postsynaptically. Burst firing induced as such was completely dependent on calcium entry as it could be blocked by cadmium and more specifically the L‐type blocker nifedipine. In the presence of the sodium channel blocker tetrodotoxin, carbachol induced membrane potential oscillation that had similar kinetics and frequency as burst firing cycles and could also be blocked by cadmium and nifedipine. Direct activation of the L‐type channel with Bay K8644 induced strong bursting which could be blocked by nifedipine but not by depleting internal calcium stores. These results indicate that carbachol increases calcium entry into the postsynaptic cell through L‐type channels to generate calcium‐dependent membrane potential oscillation and burst firing. This could establish the L‐type channel as a target for modulating the function of the central dopamine system in disease conditions.
Response of Wall Hot-Film Gages With Longitudinal Diffusion and Heat Conduction to the Substrate
Authors: Tardu F. Sedat , Pham C. Thanh
Published: August 2005

The effects of heat transfer into a substrate and axial diffusion are analyzed through numerical simulations in order to elucidate the frequency response of wall hot-film gages. The ratio of the conductivities of the substrate and fluid plays an important role in steady flows when it is larger than 5 and the Péclet number is smaller than 50. The equivalent film length increases considerably with the conductivity ratio, and it decreases when a thin film of low conductivity is sandwiched between the hot-film gage and the substrate, showing a net improvement of the heat transfer conditions. The frequency response in unsteady flows is highly attenuated in the presence of heat transfer into the substrate. The cutoff frequency is strongly dependent on the conductivity ratio. Improved response is obtained with the two-layer substrate configuration. It is further shown that axial diffusion considerably affects the frequency response when the shear and/or the streamwise length of the film are small.
Experimental Investigation of Natural Convection in an Asymmetrically Heated Vertical Channel with an Asymmetric Chimney
Authors: Manca Oronzio , Musto Marilena , Naso Vincenzo
Published: August 2005

An experimental investigation on air natural convection, in a vertical channel asymmetrically heated at uniform heat flux, with downstream unheated parallel extensions, is carried out. One extension is coplanar to the unheated channel wall and the distance between the extensions is equal to or greater than the channel gap (geometrically asymmetric chimney). Experiments are performed with different values of the wall heat flux, aspect ratio (Lh∕b), extension ratio (L∕Lh) and expansion ratio (B∕b). For the largest value of the aspect ratio (Lh∕b=10), the adiabatic extensions improve the thermal performance in terms of lower maximum wall temperature of the channel. Optimal configurations of the system with asymmetrical chimney are detected. Flow visualization shows a cold inflow in the channel-chimney system that penetrates down below the channel exit section. Maximum wall temperatures and channel Nusselt numbers are correlated to the channel Rayleigh number, Ra*, and to the geometrical parameters, in the ranges 3.0×102⩽Ra*B∕b⩽1.0105, 1.0⩽B∕b⩽3.0 and 1.0⩽L∕Lh⩽4.0 with Lh∕b=5.0 and 10.0.
An Experimental Study on the Effect of Gravitational Orientation on Flow Boiling of Water in 1054×197μm Parallel Minichannels
Authors: Kandlikar Satish G. , Balasubramanian Prabhu
Published: August 2005

Microchannels and minichannels are being considered for high heat flux applications under microgravity environment in space missions. An experimental study is undertaken to determine the effect of gravitational orientation on flow boiling characteristics of water in a set of six parallel minichannels, each 1054μm wide by 197μm deep and 63.5mm long with a hydraulic diameter of 333μm. Three orientations—horizontal, vertical downflow, and vertical upflow—are investigated under identical operating conditions of heat and mass fluxes. High-speed images are obtained to reveal the detailed two-phase flow structure and liquid-vapor interactions. The experimental data and high speed flow visualization indicate that compared to the horizontal case, the flow becomes less chaotic for the vertical upflow case, while the reversed flow becomes more pronounced in the vertical downflow case. The resulting increase in the backflow is responsible for channel-to-channel flow maldistribution and heat transfer degradation. From the heat transfer data it is concluded that the performance of the tested channels in a microgravity environment will be similar to the horizontal flow case.
Identification of Unknown Heating Elements Embedded in a Rectangular Package
Authors: Cheng Chin-Hsiang , Chang Mei-Hsia
Published: August 2005

The aim of this study is to present a novel inverse heat transfer method, which incorporates an automatic-filter scheme with the conjugate gradient method, for identifying shapes and temperatures of heating elements embedded in a rectangular package. In this report, shapes of the heating elements are visualized by using node-matrix images. A group of unknown heating elements with different shapes, positions, and temperatures are nondestructively identified simply based on the data of the upper surface temperature of the rectangular package. Effects of temperature measurement uncertainty, grid size, and number of measurement points on the top surface on the identification accuracy are evaluated. Results show that the geometric and thermal conditions of the embedded heating elements can be predicted precisely by using the present approach. The approach is found to be stable and insensitive to the temperature measurement uncertainty, and, without overwhelming mathematical manipulation, the form of objective function becomes flexible.
Loudness predicts prominence: Fundamental frequency lends little
Authors: Kochanski G. , Grabe E. , Coleman J. , Rosner B.
Published: August 2005

We explored a database covering seven dialects of British and Irish English and three different styles of speech to find acoustic correlates of prominence. We built classifiers, trained the classifiers on human prominence/nonprominence judgments, and then evaluated how well they behaved. The classifiers operate on 452 ms windows centered on syllables, using different acoustic measures. By comparing the performance of classifiers based on different measures, we can learn how prominence is expressed in speech. Contrary to textbooks and common assumption, fundamental frequency (f0) played a minor role in distinguishing prominent syllables from the rest of the utterance. Instead, speakers primarily marked prominence with patterns of loudness and duration. Two other acoustic measures that we examined also played a minor role, comparable to f0. All dialects and speaking styles studied here share a common definition of prominence. The result is robust to differences in labeling practice and the dialect of the labeler.
Age-related differences in weighting and masking of two cues to word-final stop voicing in noise
Authors: Nittrouer Susan
Published: August 2005

Because laboratory studies are conducted in optimal listening conditions, often with highly stylized stimuli that attenuate or eliminate some naturally occurring cues, results may have constrained applicability to the “real world.” Such studies show that English-speaking adults weight vocalic duration greatly and formant offsets slightly in voicing decisions for word-final obstruents. Using more natural stimuli, Nittrouer [J. Acoust. Soc. Am. 115, 1777–1790 (2004)] found different results, raising questions about what would happen if experimental conditions were even more like the real world. In this study noise was used to simulate the real world. Edited natural words with voiced and voiceless final stops were presented in quiet and noise to adults and children (4to8years) for labeling. Hypotheses tested were (1) Adults (and perhaps older children) would weight vocalic duration more in noise than in quiet; (2) Previously reported age-related differences in cue weighting might not be found in this real-world simulation; and (3) Children would experience greater masking than adults. Results showed: (1) no increase for any age listeners in the weighting of vocalic duration in noise; (2) age-related differences in the weighting of cues in both quiet and noise; and (3) masking effects for all listeners, but more so for children than adults.
Using auditory-visual speech to probe the basis of noise-impaired consonant–vowel perception in dyslexia and auditory neuropathy
Authors: Ramirez Joshua , Mann Virginia
Published: August 2005

Both dyslexics and auditory neuropathy (AN) subjects show inferior consonant–vowel (CV) perception in noise, relative to controls. To better understand these impairments, natural acoustic speech stimuli that were masked in speech-shaped noise at various intensities were presented to dyslexic, AN, and control subjects either in isolation or accompanied by visual articulatory cues. AN subjects were expected to benefit from the pairing of visual articulatory cues and auditory CV stimuli, provided that their speech perception impairment reflects a relatively peripheral auditory disorder. Assuming that dyslexia reflects a general impairment of speech processing rather than a disorder of audition, dyslexics were not expected to similarly benefit from an introduction of visual articulatory cues. The results revealed an increased effect of noise masking on the perception of isolated acoustic stimuli by both dyslexic and AN subjects. More importantly, dyslexics showed less effective use of visual articulatory cues in identifying masked speech stimuli and lower visual baseline performance relative to AN subjects and controls. Last, a significant positive correlation was found between reading ability and the ameliorating effect of visual articulatory cues on speech perception in noise. These results suggest that some reading impairments may stem from a central deficit of speech processing.
Acoustic characteristics of Mandarin esophageal speech
Authors: Liu Hanjun , Wan Mingxi , Wang Supin , Wang Xiaodong , Lu Chunmei
Published: August 2005

The present study attempted to investigate the acoustic characteristics of Mandarin laryngeal and esophageal speech. Eight normal laryngeal and seven esophageal speakers participated in the acoustic experiments. Results from acoustic analyses of syllables ∕ma∕and ∕ba∕ indicated that, F0, intensity, and signal-to-noise ratio of laryngeal speech were significantly higher than those of esophageal speech. However, opposite results were found for vowel duration, jitter, and shimmer. Mean F0, intensity, and word per minute in reading were greater but number of pauses was smaller in laryngeal speech than those in esophageal speech. Similar patterns of F0 contours and vowel duration as a function of tone were found between laryngeal and esophageal speakers. Long-time spectra analysis indicated that higher first and second formant frequencies were associated with esophageal speech than that with normal laryngeal speech.
Frequency shift of a rotating mass-imbalance immersed in an acoustic fluid
Authors: Novascone Stephen R. , Weinberg David M. , Anderson Michael J.
Published: August 2005

In this paper, we describe a physical mechanism that relates a measurable behavior of a rigid oscillator device to the physical properties of a surrounding acoustic medium. The device under consideration is a rotating mass imbalance within an enclosed shell that is immersed in an unbounded acoustic fluid. It is assumed that the rotating mass imbalance is driven by an electromagnetic motor excited by a given dc voltage. If nonlinearities are ignored, the steady-state operational frequency of such a device is determined by a balance between the applied electromagnetic and opposing frictional torque on the rotating mass imbalance. If nonlinearities are retained, it is shown that under certain circumstances, the surrounding acoustic medium exerts an additional time-averaged opposing torque on the rotating mass imbalance that reduces the operational frequency of the device. Consequently, the operational frequency of the device becomes linked to the physical properties of the surrounding medium. Analytical calculations showed that the dissipative impedance of an acoustic fluid caused the opposing torque. The shift in frequency is proportional to the dissipative impedance and the square of the rotating mass eccentricity, but inversely proportional the total mass of the device and the damping effect of the dc motor.
Experimental investigation of targeted energy transfers in strongly and nonlinearly coupled oscillators
Authors: McFarland D. Michael , Kerschen Gaetan , Kowtko Jeffrey J. , Lee Young S. , Bergman Lawrence A. , Vakakis Alexander F.
Published: August 2005

Our focus in this study is on experimental investigation of the transient dynamics of an impulsively loaded linear oscillator coupled to a lightweight nonlinear energy sink. It is shown that this seemingly simple system exhibits complicated dynamics, including nonlinear beating phenomena and resonance captures. It is also demonstrated that, by facilitating targeted energy transfers to the nonlinear energy sink, a significant portion of the total input energy can be absorbed and dissipated in this oscillator.
Tactual display of consonant voicing as a supplement to lipreading
Authors: Yuan Hanfeng , Reed Charlotte M. , Durlach Nathaniel I.
Published: August 2005

This research is concerned with the development and evaluation of a tactual display of consonant voicing to supplement the information available through lipreading for persons with profound hearing impairment. The voicing cue selected is based on the envelope onset asynchrony derived from two different filtered bands (a low-pass band and a high-pass band) of speech. The amplitude envelope of each of the two bands was used to modulate a different carrier frequency which in turn was delivered to one of the two fingers of a tactual stimulating device. Perceptual evaluations of speech reception through this tactual display included the pairwise discrimination of consonants contrasting voicing and identification of a set of 16 consonants under conditions of the tactual cue alone (T), lipreading alone (L), and the combined condition (L+T). The tactual display was highly effective for discriminating voicing at the segmental level and provided a substantial benefit to lipreading on the consonant-identification task. No such benefits of the tactual cue were observed, however, for lipreading of words in sentences due perhaps to difficulties in integrating the tactual and visual cues and to insufficient training on the more difficult task of connected-speech reception.
Word recognition in noise at higher-than-normal levels: Decreases in scores and increases in masking
Authors: Dubno Judy R. , Horwitz Amy R. , Ahlstrom Jayne B.
Published: August 2005

Under certain conditions, speech recognition in noise decreases above conversational levels when signal-to-noise ratio is held constant. The current study was undertaken to determine if nonlinear growth of masking and the subsequent reduction in “effective” signal-to-noise ratio accounts for this decline. Nine young adults with normal hearing listened to monosyllabic words at three levels in each of three levels of a masker shaped to match the speech spectrum. An additional low-level noise equated audibility by producing equivalent masked thresholds for all subjects. If word recognition was determined entirely by signal-to-noise ratio and was independent of overall speech and masker levels, scores at a given signal-to-noise ratio should remain constant with increasing level. Masked pure-tone thresholds measured in the speech-shaped maskers increased linearly with increasing masker level at lower frequencies but nonlinearly at higher frequencies, consistent with nonlinear growth of upward spread of masking that followed the peaks in the spectrum of the speech-shaped masker. Word recognition declined significantly with increasing level when signal-to-noise ratio was held constant which was attributed to nonlinear growth of masking and reduced “effective” signal-to-noise ratio at high speech-shaped masker levels, as indicated by audibility estimates based on the Articulation Index.
Recognition of filtered words in noise at higher-than-normal levels: Decreases in scores with and without increases in masking
Authors: Dubno Judy R. , Horwitz Amy R. , Ahlstrom Jayne B.
Published: August 2005

To examine spectral effects on declines in speech recognition in noise at high levels, word recognition for 18 young adults with normal hearing was assessed for low-pass-filtered speech and speech-shaped maskers or high-pass-filtered speech and speech-shaped maskers at three speech levels (70, 77, and 84 dB SPL) for each of three signal-to-noise ratios (+8, +3, and −2 dB). An additional low-level noise produced equivalent masked thresholds for all subjects. Pure-tone thresholds were measured in quiet and in all maskers. If word recognition was determined entirely by signal-to-noise ratio, and was independent of signal levels and the spectral content of speech and maskers, scores should remain constant with increasing level for both low- and high-frequency speech and maskers. Recognition of low-frequency speech in low-frequency maskers and high-frequency speech in high-frequency maskers decreased significantly with increasing speech level when signal-to-noise ratio was held constant. For low-frequency speech and speech-shaped maskers, the decline was attributed to nonlinear growth of masking which reduced the “effective” signal-to-noise ratio at high levels, similar to previous results for broadband speech and speech-shaped maskers. Masking growth and reduced “effective” signal-to-noise ratio accounted for some but not all the decline in recognition of high-frequency speech in high-frequency maskers.
Combining energetic and informational masking for speech identification
Authors: Kidd Gerald , Mason Christine R. , Gallun Frederick J.
Published: August 2005

This study examined combinations of energetic and informational maskers in speech identification. Speech targets and maskers (speech or noise) were processed and filtered into sets of 15 narrow frequency bands. The target was the sum of eight randomly selected bands. More masking occurred for speech maskers than for spectrally matched noise maskers regardless of whether the masker bands overlapped the target bands. The greater effect of the speech maskers was interpreted as due to informational masking. When the masker was comprised of nonoverlapping bands of speech, the addition of bands of noise overlapping the speech masker, but not the speech target, reduced the overall amount of masking. Surprisingly, presenting the noise to the ear contralateral to the target and masker produced an even greater release from masking. The contralateral noise was apparently sufficient to cause a slight change in the image of the ipsilateral speech masker, possibly pulling it away from the target enough to allow the focus of attention on the target. This finding is consistent with the interpretation that in some conditions small binaural differences may be sufficient to cause, or significantly strengthen, the perceptual segregation of sounds.
Decline of speech understanding and auditory thresholds in the elderly
Authors: Divenyi Pierre L. , Stark Philip B. , Haupt Kara M.
Published: August 2005

A group of 29 elderly subjects between 60.0 and 83.7years of age at the beginning of the study, and whose hearing loss was not greater than moderate, was tested twice, an average of 5.27years apart. The tests measured pure-tone thresholds, word recognition in quiet, and understanding of speech with various types of distortion (low-pass filtering, time compression) or interference (single speaker, babble noise, reverberation). Performance declined consistently and significantly between the two testing phases. In addition, the variability of speech understanding measures increased significantly between testing phases, though the variability of audiometric measurements did not. A right-ear superiority was observed but this lateral asymmetry did not increase between testing phases. Comparison of the elderly subjects with a group of young subjects with normal hearing shows that the decline of speech understanding measures accelerated significantly relative to the decline in audiometric measures in the seventh to ninth decades of life. On the assumption that speech understanding depends linearly on age and audiometric variables, there is evidence that this linear relationship changes with age, suggesting that not only the accuracy but also the nature of speech understanding evolves with age.
Parametrization of acoustic boundary absorption and dispersion properties in time-domain source/receiver reflection measurement
Authors: de Hoop Adrianus T. , Lam Chee-Heun , Kooij Bert Jan
Published: August 2005

Closed-form analytic time-domain expressions are obtained for the acoustic pressure associated with the reflection of a monopole point-source excited impulsive acoustic wave by a planar boundary with absorptive and dispersive properties. The acoustic properties of the boundary are modeled as a local admittance transfer function between the normal component of the particle velocity and the acoustic pressure. The transfer function is to meet the conditions for linear, time-invariant, causal, passive behavior. A parametrization of the admittance function is put forward that has the property of showing up explicitly, and in a relatively simple manner, in the expression for the reflected acoustic pressure. The partial fraction representation of the complex frequency domain admittance is shown to have such a property. The result opens the possibility of constructing inversion algorithms that enable the extraction of the relevant parameters from the measured time traces of the acoustic pressure at different offsets, parallel as well as normal to the boundary, between source and receiver. Illustrative theoretical numerical examples are presented.
Taking the measure of phonetic structure
Authors: Goldstein Louis
Published: August 2005

From his earliest work, Peter Ladefoged has insisted that phonetic dimensions and categories (e.g., vowel charts, IPA symbols, features) must be measurable if they are to provide an adequate basis for a universal phonetic representation. This view has led him to two questions, the pursuit of which has been enormously informative and has set the agenda for much contemporary phonetic research. (1) What are the appropriate reference frames in which to make these measurements? The debate triggered by Ladefoged as to the correct choice of reference frame is a key component of current theoretical discussion in phonetics. While the empirical data yield tantalizing hints, their interpretation is far from unambiguous, as can be seen even in some of Ladefoged’s earliest work. (2) Are there universal fixed phonetic categories within these reference frames from which individual languages choose (and if so, what are they)? Here, Ladefoged’s research has been at the leading edge of a growing consensus that there are, in fact, no fixed categories and that the division of continua into categories in particular languages is largely a random process, constrained by the nature of speech production and perception. [Work supported by NIH.]
High-intensity ultrasound radiation at over 10 MHz using hydrothermal polycrystalline lead zirconate titanate (PZT) thick film transducer
Authors: Ishikawa Mutsuo , Kurosawa Minoru , Hasegawa Tomohito , Endoh Akito , Takeuchi Shinichi
Published: August 2005

High intensity at over 10-MHz ultrasonic transducer was fabricated by hydrothermal deposition technique of lead zirconate titanate polycrystalline thick film (HPTF-PZT). The HPTF-PZT ultrasonic transducer had a 0.05-mm-thick PZT layer on a 0.05-mm-thick titanium substrate in an active area of 8 mm ∼ 8 mm. The PZT thick film was deposited on a titanium substrate in an autoclave by solution including ions of Pb, Zr and Ti at 160°C. A sound-pressure generation at thickness mode of the HPTF-PZT ultrasonic transducer was investigated in degassed water. This HPTF-PZT ultrasonic transducer could radiate sound pressures of 110 and 30 kPa at 20 and 10 MHz of ten sine waves, respectively. Cavitations and an acoustic streaming were generated when driving signal was 20-MHz continuous sine waves. Additionally, this ultrasonic transducer has the wide frequency response. Consequently, when driving signal was 10 MHz of 10-cycle rectangular waves from an odd order harmonics, the generated sound pressure was 54 kPa higher than 30 kPa at 10 MHz of 10-cycle sine waves. In fact, the HPTF-PZT ultrasonic transducer allows one to radiate high-intensity ultrasound at varied wave form of over 10 MHz.
Fire safety of acoustical materials
Authors: Kleinschmidt Klaus
Published: August 2005

Recent deadly fires in overcrowded nightclubs used open cell foam material for sound absorption. The rapid progression of fire and release of opaque smoke contributed to the inability of some of the patrons to escape the fire. Suggestions for limiting the use of such materials in places of assembly are provided. Illogical use of such sound-absorbing materials to reduce sound transmission to adjoining spaces or outdoors are discussed.
Inhibition of Translational Initiation by Let-7 MicroRNA in Human Cells
Authors: Pillai Ramesh S. , Bhattacharyya Suvendra N. , Artus Caroline G. , Zoller Tabea , Cougot Nicolas , Basyuk Eugenia , Bertrand Edouard , Filipowicz Witold
Published: August 2005

MicroRNAs (miRNAs) are ∼21-nucleotide-long RNA molecules regulating gene expression in multicellular eukaryotes. In metazoa, miRNAs act by imperfectly base-pairing with the 3′ untranslated region of target messenger RNAs (mRNAs) and repressing protein accumulation by an unknown mechanism. We demonstrate that endogenous let-7 microribonucleoproteins (miRNPs) or the tethering of Argonaute (Ago) proteins to reporter mRNAs in human cells inhibit translation initiation. M
7
G-cap-independent translation is not subject to repression, suggesting that miRNPs interfere with recognition of the cap. Repressed mRNAs, Ago proteins, and miRNAs were all found to accumulate in processing bodies. We propose that localization of mRNAs to these structures is a consequence of translational repression.
Integration of Signals through Crc and PtsN in Catabolite Repression of
Pseudomonas putida
TOL Plasmid pWW0
Authors: Aranda-Olmedo Isabel , Ramos Juan L. , Marqués Silvia
Published: August 2005

Toluene degradation in
Pseudomonas putida
KT2440 pWW0 plasmid is subjected to catabolite repression. Pu and P
S1
promoters of the pWW0 TOL plasmid are down-regulated in vivo during exponential growth in rich medium. In cells growing on minimal medium, yeast extract (YE) addition mimics exponential-phase rich medium repression of these promoters. We have constructed and tested mutants in a series of global regulators described in
Pseudomonas
. We describe that a mutant in
crc
(
c
atabolite
r
epression
c
ontrol) partially relieves YE repression. Macroarray experiments show that
crc
transcription is strongly increased in the presence of YE, inversely correlated with TOL pathway expression. On the other hand, we have found that induced levels of expression from Pu and P
S
in the presence of YE are partially derepressed in a
ptsN
mutant of
P. putida
. PtsN but not Crc seems to directly interfere with XylR activation at target promoters. The effect of the double mutation in
ptsN
and
crc
is not the sum of the effects of each independent mutation and suggests that both regulators are elements of a common regulatory pathway. Basal expression levels from these promoters in the absence of inducer are still XylR dependent and are also repressed in the presence of yeast extract. Neither
crc
nor
ptsN
could relieve this repression.
Characterization of an Unusual Cold-Active β-Glucosidase Belonging to Family 3 of the Glycoside Hydrolases from the Psychrophilic Isolate
Paenibacillus
sp. Strain C7
Authors: Shipkowski Stephanie , Brenchley Jean E.
Published: August 2005

We selected for spore-forming psychrophilic bacteria able to use lactose as a carbon source and one isolate, designated
Paenibacillus
sp. strain C7, that was phylogenetically related to, but distinct from both
Paenibacillus macquariensis
and
Paenibacillus antarcticus
. Some
Escherichia coli
transformants obtained with genomic DNA from this isolate hydrolyzed X-Gal (5-bromo-4-chloro-3-indoyl-β-
d
-galactopyranoside) only below 30°C, an indication of cold-active β-galactosidase activity. Sequencing of the cloned insert revealed an open reading frame encoding a 756-amino acid protein that, rather than belonging to a family typically known for β-galactosidase activity, belonged to glycoside hydrolase family 3, a family of β-glucosidases. Because of this unusual placement, the recombinant enzyme (BglY) was purified and characterized. Consistent with its classification, the enzyme had seven times greater activity with the glucoside substrate ONPGlu (
o
-nitrophenyl-β-
d
-glucopyranoside) than with the galactoside substrate ONPGal (
o
-nitrophenyl-β-
d
-galactopyranoside). In addition, the enzyme had, with ONPGlu, a thermal optimum around 30 to 35°C, activity over a broad pH range (5.5 to 10.9), and an especially low

K
m

(<0.003 mM). Further examination of substrate preference showed that the BglY enzyme also hydrolyzed other aryl-β-glucosides such as helicin, MUG (4-methylumbelliferyl-β-
d
-glucopyranoside), esculin, indoxyl-β-
d
-glucoside (a natural indigo precursor), and salicin, but had no activity with glucosidic disaccharides or lactose. These characteristics and substrate preferences make the BglY enzyme unique among the family 3 β-glucosidases. The hydrolysis of a variety of aryl-β-glucosides suggests that the enzyme may allow the organism to use these substrates in the environment and that its low

K
m

on indoxyl-β-
d
-glucoside may make it useful for producing indigo.
Naturally Occurring DNA Transfer System Associated with Membrane Vesicles in Cellulolytic
Ruminococcus
spp. of Ruminal Origin
Authors: Klieve Athol V. , Yokoyama Melvin T. , Forster Robert J. , Ouwerkerk Diane , Bain Peter A. , Mawhinney Erin L.
Published: August 2005

A genetic transformation system with similarities to those reported for gram-negative bacteria was found to be associated with membrane vesicles of the ruminal cellulolytic genus
Ruminococcus.
Double-stranded DNA was recovered from the subcellular particulate fraction of all the cellulolytic ruminococci examined. Electron microscopy revealed that the only particles present resembled membrane vesicles. The likelihood that the DNA was associated with membrane vesicles (also known to contain cellulosomes) was further supported by the adherence of the particles associated with the subcellular DNA to cellulose powder added to culture filtrates. The particle-associated DNA comprised a population of linear molecules ranging in size from <20 kb to 49 kb (
Ruminococcus
sp. strain YE73) and from 23 kb to 90 kb (
Ruminococcus albus
AR67). Particle-associated DNA from
R. albus
AR67 represented DNA derived from genomic DNA of the host bacterium having an almost identical HindIII digestion pattern and an identical 16S rRNA gene. Paradoxically, particle-associated DNA was refractory to digestion with EcoRI, while the genomic DNA was susceptible to extensive digestion, suggesting that there is differential restriction modification of genomic DNA and DNA exported from the cell. Transformation using the vesicle-containing fraction of culture supernatant of
Ruminococcus
sp. strain YE71 was able to restore the ability to degrade crystalline cellulose to two mutants that were otherwise unable to do so. The ability was heritable and transferred to subsequent generations. It appears that membrane-associated transformation plays a role in lateral gene transfer in complex microbial ecosystems, such as the rumen.
Diel Infection of a Cyanobacterium by a Contractile Bacteriophage
Authors: Kao C. Cheng , Green Susan , Stein Barry , Golden Susan S.
Published: August 2005

Light was found to strongly influence the infection of a freshwater cyanobacterium (
Synechococcus elongatus
PCC 7942) by a contractile DNA phage named AS-1. Phage progeny production was correlated with the amount of light in the laboratory and occurred in a diel pattern under natural light. At least one effect of light on AS-1 infection is at the level of adsorption.