bluuebunny/crossref_metadata_2025 huggingface dataset:
Stem–loop oligonucleotides as tools for labelling double‐stranded DNA
Authors: Géron‐Landre Bénédicte , Roulon Thibaut , Escudé Christophe
Published: October 2005

We report on a sequence‐specific double‐stranded DNA labelling strategy in which a stem–loop triplex forming oligonucleotide (TFO) is able to encircle its DNA target. Ligation of this TFO to either a short hairpin oligonucleotide or a long double‐stranded DNA fragment leads to the formation of a topological complex. This process requires the hybridization of both extremities of the TFO to each other on a few base pairs. The effects of different factors on the formation of these complexes have been investigated. Efficient complex formation was observed using both GT or TC TFOs. The stem–loop structure enhances the specificity of the complex. The topologically linked TFO remains associated with its target even under conditions that do not favour triple‐helix formation. This approach is sufficiently sensitive for detection of a 20‐bp target sequence at the subfemtomolar level. This study provides new insights into the mechanics and properties of stem–loop TFOs and their complexes with double‐stranded DNA targets. It emphasizes the interest of such molecules in the development of new tools for the specific labelling of short DNA sequences.
Thermal conductivity of B-C-N and BN nanotubes
Authors: Chang C. W. , Han Wei-Qiang , Zettl A.
Published: October 2005

We have measured the temperature-dependent thermal conductivity κ(T) of boron-carbon-nitride (B-C-N) and boron nitride (BN) nanotube mats. The thermal conductivity of B-C-N nanotubes is phonon dominated and reflects dimensional effect below 70 K. We employ a new analysis method to estimate the intrinsic κ(T) of BN nanotubes converted from B-C-N nanotubes, and find that at room temperature κ(T) of a multiwalled BN nanotube is within 0.04–0.32 times that of a multiwalled carbon nanotube. The lower κ(T) of BN nanotubes than that of carbon nanotubes may be due to the enhanced isotope disorder effect in one dimension.
Effect of film thickness on the ferroelectric properties of Pb(Zr0.2Ti0.8)O3 thin films for nano-data storage applications
Authors: Lee Woo-Sung , Ahn Kyoung-Chan , Yoon Soon-Gil , Kim Chang Soo
Published: October 2005

Epitaxial Pb(Zr0.2Ti0.8)O3 (PZT) films with various thicknesses were prepared on an epitaxial SrRuO3(SRO) bottom electrode grown on SrTiO3 (STO) with atomically flat surface. The PZT films with a rms roughness of 0.2–0.3 nm exhibit a typical square-shaped P-E hysteresis loop, which has the Pr of approximately 60μC∕cm2. The leakage current density of the films increases with decreasing film thickness and the 22-nm-thick PZT films have a leakage current density of approximately 10−5A∕cm2 at −1V.
Effect of high-frequency variation on the etch characteristics of ArF photoresist and silicon nitride layers in dual frequency superimposed capacitively coupled plasma
Authors: Kim D. H. , Lee C. H. , Cho S. H. , Lee N.-E. , Kwon G. C.
Published: October 2005

In this work, the deformation of ArF photoresist (PR) and etch characteristics of the ArF PR and Si3N4 layers were investigated in the dual frequency superimposed capacitively coupled plasmas under different frequency combinations by varying the process parameters such as dc self-bias voltage (Vdc), CF4∕CHF3 flow ratio, and O2 flow rate in the CF4∕CHF3∕O2∕Ar chemistry. Surface roughness measurements and morphological investigation of the line and space patterns after etching by atomic force microscopy and scanning electron microscopy, respectively, showed increased surface roughness and deformation with increasing the Vdc, the high-frequency source frequency (fHF), the CHF3 flow percentage, and the O2 flow rate. The etch rates of the ArF PR and silicon nitride layers were also increased significantly with the Vdc and fHF increased. The Si3N4∕PR etch selectivity was increased most significantly by an increase in the CHF3 flow percentage.
Fabrication and characterization of InGaAlP∕InGaP semiconductor circular ring lasers
Authors: Shih M. C. , Wang S. C. , Liang C. W.
Published: October 2005

We report the fabrication of a semiconductor circular ring lasers based on an InGaAlP∕InGaP graded-index separate confinement heterostructure (GRIN-SCH) which attracted much attention for light sources in optical information processing systems such as a laser printer, compact disk player and optical link system. The dimensions of the circular ring cavity are 100μm–250μm in diameter, 5–10μm width of the ridge waveguide, and a Y junction output coupler of 250μm in length. An ultraviolet (UV) laser-assisted etching process and the two-layer photolithography process were developed for the fabrication of the circular ring cavity. The luminescence-current and spectrum characteristics of laser output showed a single-mode output operating at 698 nm and at threshold current about 60 mA. The reports showed that the pattern definition by the combination of UV laser-assisted etching, and the two-layer photolithography process was capable of complex optoelectronic integrated device processing.
Silver coplanar waveguides as the passive components of choice for microwave integrated circuits
Authors: Levenets Vladislav V. , Amaya Rony E. , Tarr N. Garry , Smy Tom J. , Rogers John W. M.
Published: October 2005

High quality broadband passive components are needed for MMIC/MIC in silicon. Coplanar waveguides (CPW) provide an effective way to implement passives in microwave ICs. Silver “fat” wires in the back end interconnects, used for CPW fabrication, will reduce the bulk resistive loss in metallization to the lowest possible level, which is vital to minimize noise. Electromigration, electrochemical migration, and agglomeration issues are not a problem for silver microwave passive components, because of their coarse dimensions and the low current densities encountered in these structures. In this work Ag and Cu CPWs were designed, fabricated, and tested. Silver CPWs showed a 2–3Ω∕cm improvement in resistance over copper devices at 20GHz.
Tunable all epitaxial semimetal-semiconductor Schottky diode system: ErAs on InAlGaAs
Authors: Zimmerman Jeramy D. , Brown Elliott R. , Gossard Arthur C.
Published: October 2005

We report the growth, fabrication, and electrical properties of a fully epitaxial semimetal-semiconductor Schottky diode materials system: ErAs on InAlGaAs. The coherent, thermodynamically stable, lattice-matched interface eliminates oxide and interfacial third phases, making the Schottky barrier height and associated electrical parameters dependent on the fundamental molecular bonding (e.g., interface dipoles) rather than unintentional extrinsic effects. ErAs:InAlGaAs diodes thus have highly tunable properties; by adjusting composition, doping, and interface type, the Schottky barrier height is tunable from ∼100meVto∼620meV, short circuit responsivity is tunable from 0.5to19A∕W, differential resistance is tunable from 103to1010Ωμm2, and capacitance is tunable from 0.4to2fF∕μm2. Rectification of a rf source has been demonstrated up to 20GHz. ErAs:InAlGaAs is thus a very promising materials system for design of an upper mm-wave, zero-bias, square-law detector with a significantly reduced noise floor.
Density of electron-beam-induced amorphous carbon deposits
Authors: Nishio Mitsumasa , Sawaya Shintaro , Akita Seiji , Nakayama Yoshikazu
Published: October 2005

We have measured the density of amorphous carbon (a-C) prepared using electron-beam-induced deposition with a nanotube cantilever. The a-C mass was proportional to the deposition time for all experimental conditions. The measured density ranged from 0.29to0.88g∕cm3 depending on the electron-beam conditions. Density increased with increasing acceleration voltage and beam current. This phenomenon is discussed in terms of the effects of acceleration voltage and beam current on the temperature of the growing surface and the lifetime of the precursor.
In situ chemical sensing in AlGaN∕GaN metal organic chemical vapor deposition process for precision film thickness metrology and real-time advanced process control
Authors: Cho Soon , Janiak Daniel S. , Rubloff Gary W. , Aumer Michael E. , Thomson Darren B. , Partlow Deborah P.
Published: October 2005

In situ mass spectrometry is implemented in AlGaN∕GaN∕AlN metalorganic chemical vapor deposition processes on SiC substrates as a real-time process- and wafer-state metrology tool. Dynamic chemical sensing through the process cycle, carried out downstream from the wafer, revealed generation of methane and ethane reaction by-products as well as other residual gas species. The methane and ethane by-products are believed to reflect the two parallel chemical reaction pathways leading to GaN-based materials growth, namely the gas phase adduct formation route and the direct surface decomposition of the metalorganic precursor, respectively. Having detected both types of by-products as evidence for the presence of both paths, we monitored and integrated the methane and ethane signals to derive a real-time film thickness metric. Integrating the sum of the two by-product signals in this manner through the AlGaN growth period (∼1min or less) enabled us to predict the AlGaN cap layer thickness (∼20nm) to within ∼1% or ∼0.2nm precision. This was verified by postprocess x-ray reflectance measurement, which produced a thickness map over the 2in. wafer and yielded an average thickness for the AlGaN cap layer for comparison to the real-time mass spectrometry. These results demonstrate an opportunity for advanced process control based on real-time in situ chemical sensing, with the promise of major benefit in reproducibility and cost reduction in AlGaN∕GaN-based semiconductor manufacturing.
Pressure dependent Parylene-N pore sealant penetration in porous low-κ dielectrics
Authors: Juneja Jasbir S. , Ten Eyck Gregory A. , Bakhru H. , Lu T.-M.
Published: October 2005

The introduction of porosity in dielectrics is desirable to reduce the dielectric constant; but it causes integration problems such as CVD∕ALD precursor penetration for barrier layer∕seed layer deposition. CVD Parylene-N has been shown to work as a pore sealant for porous low-κ materials but penetrates itself slightly into porous dielectric. The depth profile of Parylene-N in porous MSQ can be obtained using the Nuclear Reaction Analysis (NRA) of C12. The penetration of Parylene-N can be controlled by deposition at higher pressure where the deposition rate is also high. High deposition rate can also be attained by adding a carrier gas which also shows low Parylene-N penetration. The experimentally measured dielectric constants, after pore sealing, are compared to those calculated using the NRA data of Parylene-N penetration.
Impurity redistribution due to recrystallization of preamorphized silicon
Authors: Duffy R. , Venezia V. C. , van der Tak K. , Hopstaken M. J. P. , Maas G. C. J. , Roozeboom F. , Tamminga Y. , Dao T.
Published: October 2005

We have studied impurity redistribution due to low-temperature crystallization of amorphous silicon. Many impurities move ahead of the amorphous-crystalline interface and relocate closer to the surface. In general, redistribution is more likely at high impurity concentrations. By investigating a wide range of concentrations for indium, lead, and antimony, we demonstrate the direct correlation between the magnitude of this redistribution effect and the impurity metastable solubility limit in crystalline silicon. At low concentrations, it is less likely for impurities to redistribute. However, in this regime we show that indium experiences concentration-independent segregation, and that boron profiles are also affected by the crystallization process.
Time dependence of wet oxidized AlGaAs∕GaAs distributed Bragg reflectors
Authors: Li R. Y. , Wang Z. G. , Xu B. , Jin P. , Guo X. , Chen M.
Published: October 2005

The time dependence of wet oxidized AlGaAs∕GaAs in a distributed Bragg reflector (DBR) structure has been studied by mean of transmission electron microscopy and Raman spectroscopy. The wet oxidized AlGaAs transforms from an initial amorphous hydroxide phase to the polycrystalline γ-Al2O3 phase with the extension of oxidation time. The thickness of oxide layers will contract due to the different volume per Al atom in AlGaAs and in the oxides. In the samples oxidized for 10 and 20 min, there are some fissures along the AlGaAs∕GaAs interfaces. In the samples oxidized longer, although no such fissures are present along the interfaces, the whole oxidized DBR delaminates from the buffer.
Effect of mask thickness on the nanoscale sidewall roughness and optical scattering losses of deep-etched InP∕InGaAsP high mesa waveguides
Authors: Zhao W. , Bae J. W. , Adesida I. , Jang J. H.
Published: October 2005

Deep-etched mesa waveguide in InP∕InGaAsP heterostructures were fabricated using different thicknesses of NiCr etching mask in an inductively coupled plasma reactive ion etching system with Cl2-based plasmas. An atomic force microscope (AFM) loaded with a carbon nanotube tip was utilized to measure the sidewall roughness of the etched structures. The root-mean-square (rms) roughness values were calculated separately for the horizontal and vertical directions of the waveguide sidewall. As the NiCr mask thickness increased from 10 nm to 150 nm, the rms roughness value in the vertical direction of the waveguide sidewall decreased from 19.5 nm to 2.8 nm. On the other hand, the rms roughness value in the horizontal waveguiding direction increased from 2.5 nm to 4.0 nm. The correlation lengths along the horizontal direction for the etched waveguide structures were also extracted from the AFM roughness data. The rms roughness values and correlation lengths were used as parameters in three-dimensional beam propagation method to calculate the optical scattering loss. The calculated optical losses ranged from 1.2dB∕cm to 2.5dB∕cm.
Fundamental study of the removal mechanisms of nano-sized particles using brush scrubber cleaning
Authors: Xu K. , Vos R. , Vereecke G. , Doumen G. , Fyen W. , Mertens P. W. , Heyns M. M. , Vinckier C. , Fransaer J. , Kovacs F.
Published: October 2005

To ensure high device yields, wafer surface contamination and defects must be monitored and controlled during the entire process of semiconductor manufacturing. Particle surface concentrations on the wafers, mostly related to chemical mechanical polishing (CMP) processes, must be kept at the lowest possible levels. Brush scrubber cleaning has the potential to achieve this goal. However, the particle removal mechanisms are still under discussion especially the removal of nano-sized particles. This paper investigates the interactions between the particle, the brush and the wafer surface and explores the potential and limitations of the brush scrubbing technique. Furthermore the effect of the various brush/wafer parameters on the particle removal efficiency (PRE) is studied. From a mechanistic viewpoint it is shown that brush scrubbing acts in a mixed lubrication regime. From an extensive analysis of the relevant forces and moments it can be concluded that in the hydrodynamic lubrication regime, particles are removed by rolling under the dominant hydrodynamic drag force. In the boundary lubrication regime, particles can be removed by both rolling and lifting, mainly by the brush/particle van der Waals forces. The pH and the ionic strength of the cleaning fluid can influence the PRE. The chemical composition determines the electrostatic interactions of the particle once it is “kicked off ” from the wafer surface: either the surface of the particles and the wafer carry the same charge and the particles remain in solution or the surface of the particles and the wafer has an opposite charge resulting in redeposition.
Application of the finite element method to the vibrations of quartz plates
Authors: Cowdrey D. R. , Willis J. R.
Published: October 2005

The differential equations governing the motion of an anisotropic plate are dealt with using Cauchy's power series expansion to approximate the displacement of a point. These equations are not solved explicitly; the method of Rayleigh-Ritz is followed using finite elements. Digital computation delivers eigenvalues and eigenvectors related to the various modes of vibration. The possibility of deducing theoretical admittance curves is discussed, and an example is worked out and compared with experimental data.
Spectrum of rotor noise caused by atmospheric turbulence
Authors: Hanson Donald B.
Published: October 2005

The spectra of noise and blade loading caused by interference of a propeller, helicopter rotor, or fan rotor with inlet turbulence are studied experimentally and theoretically. One test with hot-wire anemometers in a static inlet and another test with pressure transducers on the blades of a fan rotor reveal inlet turbulence to be highly anisotropic. The intensity of the transverse velocity component was found to be 2.5% of the mean flow and the streamwise component was 0.9% with ambient winds of about 1 mph. The transverse integral scale of the turbulence is a fraction of an inlet diameter, while the streamwise scale is over 100 diameters. Evidence indicates the source of these disturbances is atmospheric turbulence. The associated-noise is partially coherent, with spectrum peaks which are so narrow as to be difficult to distinguish from true harmonics. Theoretical spectrum predictions, performed with methods from random pulse modulation theory, indicate for the test fan that the peak at blade passing frequency and the high-frequency broad-band noise are due to inflow turbulence. It appears that this narrow-band random mechanism explains spectrum peaks which have previously been described as harmonic noise due to fixed inflow distortion.
Identification of temporal order in three-tone sequences
Authors: Divenyi P. L. , Hirsh I. J.
Published: October 2005

Well-trained subjects identified with remarkable accuracy the temporal order of three contiguous pure tones of different frequencies, presented as a single sequence. For a given set of three frequencies covering a one-octave span, the minimum duration of each component tone necessary for absolute identification of a sequence was 2–7 msec on the average. A total frequency range narrower than 1/3–2/3 octave depressed the identifiability of temporal order, whereas increasing the frequency range beyond this limit had no appreciable effect. Simple harmonic relation between the three components was associated with higher identification performace than was a complex harmonic relation. In general, those temporal orders in which the frequency change was unidirectional were more easily identified than the others. Also, the highest and the lowest of the three tones in final position were recognized more often than any of the sequences and were, most probably, used by the observers as cues for the identification of sequences.
Dynamic theory of sound-source localization
Authors: Lambert Robert M.
Published: October 2005

Under idealizations about the nature of the path taken by sounds to each of a listener's two ears, and the shape of the listener's head, it is shown that both the azimuth and the range of a sound source can be expressed in terms of the rate at which certain sound stimulus parameters change when sound-source azimuth varies. It is further shown that these rates of change can be approximated by a listener if he rotates his head on its vertical axis in ways, and to extents, that are appropriate. The conclusion, then, is that a listener can calculate the azimuth and range of a sound source wholly on the basis of his interaction with the sound stimulus, without any prior knowledge of the sound source. The problem of localization error is discussed, particularly in relation to the extent to which our idealizations depart from reality, and our results are briefly related to those of other researchers in the field of sound-source localization.
Upper limit to stapes displacement: implications for hearing loss
Authors: Price G. Richard
Published: October 2005

Based on calculations from existing data, the human middle ear appears to have a displacement limit of about 30 μ peak to peak and becomes nonlinear at about 10 μ peak to peak. This nonlinearity begins at free-field SPLs of 110 to 120 dB in the midrange of frequencies. The presence of an absolute limit to stapes displacements indicates that at high SPLs there is a high-frequency bias in the conducting mechanism which may in part be responsible for the high-frequency hearing loss commonly seen following industrial and/or impulsive noise exposure.
Auditory frequency discrimination in vertebrates
Authors: Fay Richard R.
Published: October 2005

Pure-tone frequency discrimination threshold values for 13 vertebrate species were taken from the experimental literature and presented graphically as a summary of the extent of the existing data in this area.
Sensorimotor dominance and the right-ear advantage in mandibular-auditory tracking
Authors: Sussman Harvey M. , MacNeilage Peter F. , Lumbley Jack
Published: October 2005

Subjects attempted to match a continually varying computer-generated tone presented to one ear with another jaw-generated or right-hand-generated tone presented to the other ear. There was a significant right-ear advantage for the jaw-generated tone only, replicating and extending an earlier study with the tongue. Results are interpreted as showing a speech-related sensorimotor laterality which is independent of dichotic right-ear advantage effects on speech perception in the same subjects.
Naturally occurring atmospheric acoustical signals
Authors: McDonald John A.
Published: October 2005

Atmospheric disturbances located close to microbarograph arrays in north Texas are assumed to be caused by sources of acoustic-gravity waves and/or infrasound. The sources studied are large storms, hurricanes, tornadoes, and frontal systems. The large-amplitude long-period acoustic-gravity waves are readily found, but detection of infrasound presents problems which are indicated and some possible solutions are suggested.
Normal-mode theory of underwater sound propagation from directional multipole sources
Authors: Haug Anton , Graves Ronald D. , Überall H.
Published: October 2005

Normal-mode theory of underwater sound propagation, which so far has been established only for omnidirectional point sources, is developed here for the case of sources with arbitrary spatial extent and directionality. This is accomplished by expanding the source in a series of spherical multipole distributions. From the Green's function representation, the sound field is then obtained for arbitrary multipolarity of the source, and it simplifies considerably for a point multipole source. Our results are illustrated by a calculation of range-focusing effects in a channel with parabolic velocity profile using a dipole source.
Closed-form solutions for SOFAR ray caustics in media with bilinear sound-speed profiles
Authors: Raphael David Towns
Published: October 2005

In an unbounded medium with a bilinear sound-speed profile composed of two constant-gradient layers separated by an interface at the depth of minimum sound speed, SOFAR rays are generated which are continuously refracted towards the channel axis. The existence conditions for real roots of the acquiring-ray cubic and quartic equations treated herein facilitate the determination of the caustic equations. When the condition is imposed that the discriminant of the cubic or quartic equation be zero valued, the caustic equation emerges as the boundary line along which repeated roots occur. Two general cases are examined: (a) receiver and source in same layer, and (b) receiver and source in different layers. Explicit, closed-form solutions are obtained for most of the caustics by exploitation of reciprocity considerations and by reduction-to-single reflection or crossing arguments. Only rays which cross the interface without undergoing either a surface or bottom reflection are treated.
Transient response of multidegree-of-freedom linear systems to forcing functions with inequality constraints
Authors: Michalopoulos C. D.
Published: October 2005

Optimal control theory is employed to analyze the transient response of discrete, linear systems to forcing functions, whose dependence on time is not known, but which lie within specified bound. Attention is focused on the complete determination of the forcing function which will induce (a) maximum displacement of any specified mass element, (b) maximum relative displacement of any two adjacent masses, and (c) maximum acceleration of a given mass. Linear mechanical systems with an arbitrary number of degrees of freedom are considered, wherein only a single forcing function acts. In general, the desired forcing function is found to be a bang-bang-type function; that is, a function which switches from the upper to the lower bound and vice-versa at certain instants of time. The general procedure for finding these switching times is presented.
Judged acceptability of noise exposure during television viewing
Authors: Langdon Lawrence E. , Gabriel Richard F. , Creamer Lyle R.
Published: October 2005

Noise masking of television audio signals by flyovers is the most frequently mentioned problem of airport neighbors. This problem was studied in the laboratory using artificial noise. Three studies varied the intensity, duration, and rate (noises per hour) of the noises. Acceptability was found to approximate a logarithmic function of noise energy for changes in intensity, duration, and rate. Thus, the equal-energy principle, which has been generally observed in abstract psychometric experiments, was confirmed in this more realistic and representative task. A fourth study showed aircraft-flyover recordings to be more acceptable than artificial noises even though they had equivalent peak levels and masking durations. This difference can also be explained by the equal-energy principle, since the flyovers had lower average (or integrated) energy.
Jet engine exhaust noise due to rough combustion and nonsteady aerodynamic sources
Authors: Plett Edelbert G. , Summerfield Martin
Published: October 2005

Internal sources are accounted for in terms of fluctuations in mass and momentum at the nozzle exit plane. Detailed laboratory scale data are used in conjunction with the analysis to determine effective scaling parameters linking physically measurable quantities to the mathematical model used. The resulting model is used to predict contributions from various sources in a typical jet engine exhaust. Mass-flow fluctuations generated at the exit plane by combustion-driven acoustic-resonant-type fluctuations inside the engine are found to be dominant up to jet Mach numbers around 0.45, after which mass-flow fluctuations at nozzle-dominated frequencies become most dominant. The jet contribution, or exit plane momentum fluctuations, are not found significant below Mach 1, for the conditions considered.
Recursive algorithm for estimating the spatial density of acoustic point scatterers
Authors: Ehrenberg John E.
Published: October 2005

A recursive algorithm for estimating the spatial density of acoustic point scatterers is derived. This algorithm, which is based on the stochastic approximation estimation technique, is shown to be equivalent to an echo counter for low densities and to an energy detector or echo integrator for high densities. The problem of estimating fish density from a scattered acoustic signal is considered in detail The recursive algorithm is shown to have a mean-squared error that is a factor of 6 lower than either an echo integrator or an echo counter in the medium density region.
Ranke revisited—a simple short-wave cochlear model
Authors: Siebert William M.
Published: October 2005

An integral equation for the pressure difference across the cochlear partition is derived from the classical assumptions. This equation can be solved to any desired precision by the numerical method of Lesser and Berkley. Alternately, making the usual long-wave assumption, it can be reduced to the second-order differential equation studied by Zwislocki and many others. Although many aspects of this solution agree with observations, the long-wave assumption is of doubtful validity for many interesting frequencies and locations, and the behavior is more sensitive to the size of the scalae than experimental results suggest. A third approach is to make the short-wave assumption proposed by Otto Ranke. The integral equation then can be transformed into a pair of first-order differential equations which can easily be solved in closed form. The resulting simple formulas can be fit to most of the observations of Békésy and others. In addition, the short-wave theory leads to simple explanations of “paradoxical motion” and the effects of bone conduction. The phase characteristics of the theory, however, show major deviations from the experiment—a failure which, it is believed, is due not to the short-wave approximation per se, but rather to the basic physical simplifications common to virtually all cochlear theories.
Pass-fail ratios in identification audiometry as a function of audiometer rise time
Authors: Walton Wendel K. , Wilson Wesley R.
Published: October 2005

The effect of rise-time variation on identification audiometry results was determined by screening 2564 children in grades K through 5. Each child received two tests—one on an audiometer calibrated to ANSI S3.6-1969 specifications, and the other on an audiometer meeting the same specifications except for rise time which deliberately was set too fast (median 6 msec). Significantly more children passed the screening test accomplished with the FAST- as compared to the ANSI-RISE audiometers. No grade-level (age) effect was noted; however, a test-frequency effect was found.
Response of the Doppler echolocation system in the bat, Rhinolophus ferrumequinum
Authors: Simmons James A.
Published: October 2005

An electronic target simulator was used to produce artificial echoes for the echolocating bat, Rhinolophus ferrumequinum. When the bat was presented with Doppler-shifted echoes, it changed the frequency of the constant-frequency (CF) portions of its outgoing orientation sounds to restore the CF portions of returning echoes to the bat's preferred frequency, approximately 83 kHz. The data confirm previous observations of the Doppler-compensating response in bats that use long-duration CF signals. Theoretically, Rhinolophus could detect target velocity changes of 0.05 to 0.1 m/sec, and the bat actually detects changes in the velocity of a simulated target as small as 0.1 m/sec. The Doppler-compensating response adapts the bat's frequency-modulated (FM) echolocation system to prevailing target velocities, perhaps to stabilize echo images against perceptual distortions of target range that occur as a result of an interaction between FM sweeps and Doppler shift. The velocity-sensitive sonar presumably allows the bat to detect moving prey against background of fixed objects.
Free vibrations of shallow spherical shells
Authors: Kunukkasseril V. X. , Palaninathan R.
Published: October 2005

Normal modes of the shallow spherical shells have been developed for the real and complex roots of the auxilliary equation. Frequency spectrums are presented for symmetric and asymmetric motions of clamped and supported shells. First four axisymmetric modes are presented for the illustration of the edge effects on deformation.
Masking with narrow-band FM noise
Authors: Margolis Robert H. , Small Arnold M.
Published: October 2005

Masked thresholds were measured for signal frequencies below, within, and above two 190-Hz noise bands centered arithmetically at 1125 Hz. One noise band was computer synthesized and had amplitude fluctuations characteristic of analog noise bands typically used in masking experiments. The other noise band, matched in spectrum and level to the synthesized noise band, was generated by a frequency modulation (FM) process. The resulting waveform was free of envelope fluctuations. Masked thresholds in the FM noise were 5–10 dB lower than in the synthetic noise in the flat portions of the spectra. Synthesized noise resulted in trapezoidal appearing audiograms. The FM noise audiogram tended to be unimodal. Results are discussed with reference to envelope detection hypotheses.
Preliminary study of certain timing relationships in the speech of stutterers
Authors: Di Simoni Frank G.
Published: October 2005

Stutterers' duration control in repeated production of syllables indicates that timing relationships are appropriate only in initial speech attempts.
Sound diffusion in enclosures
Authors: Waterhouse Richard
Published: October 2005

The effect on sound diffusion of enclosure shape and a moving diffuser are discussed, and some points are made about normal and damped modes, and the space variance in a diffuse sound field
Effects of noise on people
Authors: Miller James D.
Published: October 2005

An overview of the effects of noise on people as can be determined from the scientific literature is presented. Only audible noise is considered and no attempt is made to describe the extent of the noise problem in terms of the number of people affected or in terms of social and economic costs. Rather, emphasis is placed on describing and classifying the adverse effects and relating them in a general way to the intensive and temporal properties of audible noise. For simplicity, the intensive dimension of the noise is usually given as the A-weighted sound level and detailed descriptions and evaluations of various acoustical measurements are for the most part avoided. The effects of noise are classified as auditory, general psychological, and sociological, or as general physiological. A summary is included.
Sound waves in two-dimensional ducts with sinusoidal walls
Authors: Nayfeh Ali Hasan
Published: October 2005

The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.
Cylindrical nearfield calibration array
Authors: Van Buren A. L.
Published: October 2005

The planar nearfield calibration array (NFCA) has previously been used to determine the farfield radiation of underwater transducers from nearfield measurements. We consider here a cylindrical NFCA constructed from a single line of suitably shaded reciprocal hydrophones. The transducer to be calibrated is rotated within a volume V near the line about an axis parallel to the line. The response of the line, both amplitude and phase, is measured at 30 angular positions equally spaced over 360°. In this way a virtual cylindrical array of 30 lines is created. The azimuthal farfield pattern of the transducer is then obtained by computer processing the 30 responses together with a set of complex shading coefficients. These coefficients are designed so that the entire virtual array, if driven as a source, would produce a nearly uniform plane wave over the volume V. Alternatively, the calibration can be accomplished without mechanical rotation by use of a real cylindrical array of 30 lines. Experimental results were obtained for a large piston transducer. The computed farfield patterns are in good agreement with directly obtained farfield patterns.
Vibrational relaxation and sound absorption in O2/H2O mixtures
Authors: Bass H. E. , Shields F. D.
Published: October 2005

Measurements of the sound absorption in O2/H2O mixtures have been made at 400° and 500°K. The results have been compared with measurements made by others at room temperature and analyzed by the Bauer, Shields, and Bass method to determine values and limits of errors for the rate constants. The v-t deexcitation rate in H2O/H2O collisions was found to vary from 1.0 to 0.75 × 109/sec-atm and the v-v rate between O2 and H2O was found to vary from 3.8 to 1.5 × 107/sec-atm as the temperature increased from 300° to 500°K.
Ultrasonic spectroscopy of a fluid-filled cavity in an elastic solid
Authors: Sachse Wolfgang
Published: October 2005

The scattering of wide-band ultrasonic pulses from a circular, cylindrical, fluid-filled cavity in an elastic solid is investigated with a digital ultrasonic-spectroscopy technique. Based on the data from three sizes of cavities (1/32-in., 1/16-in., and 1/8-in. diameter), each being filled with five different fluids, we find that either the diameter of the cavity or the wave speed of the fluid contained in it can be determined from the time history of the scattered pulses. From the spectral analysis, an empirical formula is established relating the incremental spectral frequencies (the intervals between successive frequency maxima or minima of the spectra) to the diameter of the cavity and the wave speed of the fluid contained in it.
On perceptual integration of dichotically alternated pulse trains
Authors: Huggins A. W. F.
Published: October 2005

Subjects adjusted the rate of a binaural pulse train so that it matched the perceived rate of a dichotically alternated pulse train, in which successive pulses were heard in the left and right ears alternately. At low rates, subjects matched the total rate of pulses-into-the-head. At high rates, they matched the rate of pulses in one of their ears. The crossover was quite sharp, and took place when the interpulse interval in one ear was about 100–200 msec. The results are discussed in relation to results with alternated and temporally segmented speech, and to acoustic short-term memory.
Time-variant spectra of violin tones
Authors: Beauchamp James W.
Published: October 2005

Several violin tones were digitized and processed by a Fourier analysis computer program and the resulting time-variant harmonic spectra were stored on digital magnetic tape. The data were plotted according to a number of formats in order to facilitate different interpretations of the data. Sets of graphs of harmonic levels and relative phases versus time were found to be the most useful data presentations for interpretation of transients. It was found that attack and decay rates (in decibels per second) vary considerably from harmonic to harmonic and that vibrato affects both the phase and level curves. The phase-locked behavior of all partials during the steady state and the inharmonicity of the partials during the attack and decay intervals are clearly visible in the phase graphs. It is believed that the unusually large level and phase fluctuations which appear for certain harmonics in the steady state are due to the presence of strong resonances near their respective frequencies. Three other data presentations were found useful for depicting formant behavior: (1) line spectrum movie, (2) computer printout spectrogram, and (3) superimposed average spectra of many tones.
Long-period fluctuations of CW signals in deep and shallow water
Authors: Clark John G. , Kronengold Morton
Published: October 2005

In July 1972, as part of the cooperative studies between the Miami and Michigan Project MIMI research groups, continuous fixed-system underwater sound propagation tests at 406 Hz were commenced between a sound source off Eleuthera, Bahamas, and receivers at Bermuda, a distance of 1250 km, and at positions intermediate in range with respect to the 1250-km path. Preliminary studies of long-period CW transmission fluctuations at Bermuda and at one intermediate position have been completed. The long-period phase and amplitude fluctuations are qualitatively quite similar to those observed in the Straits of Florida and in other relatively shallow water locations. Phase fluctuations associated with the ocean tides are a marked feature of the data. With averages taken over two-day time spans, significant variations in the statistical properties of transmission loss have been observed over a five-month time period. Shorter-period fluctuations in acoustic phase (time scale of a few minutes to a few hours) have similar characteristics in the deep and shallow water propagation ranges. [The research was supported by Code 412 of the Office of Naval Research.]
Mean of the field for cylindrically spreading waves in a random medium
Authors: Fitelson Michael M.
Published: October 2005

The mean value of the field for cylindrically spreading waves in a random medium is obtained when forward scattering is dominant. In addition, the region of validity of the solution is obtained. These results are identical to the corresponding results for plane waves, except for cylindrical spreading loss.
Noise generation by gas jets in a turbulent wake
Authors: Gavigan J. J. , Watson E. E. , King W. F.
Published: October 2005

Radiated noise is generated when gas discharges from an underwater orifice into a turbulent wake. Few quantitative studies under controlled conditions have been reported, however, and the mechanism of this noise generation is not well understood. This paper presents measurements of noise radiated by gas jets exhausting into a turbulent wake under controlled conditions in the test section of a 48-in. diam water tunnel. Acoustic-measurements in the frequency range 6–45 kHz were made with a directional hydrophone mounted in a water-filled tank attached to one side of the tunnel test section. A turbulent wake was generated by a water speed of 9.1 m/sec flowing past a strut-mounted cigar-shaped body. Nitrogen gas was discharged at various flow rates into the turbulence through two different nozzle plates attached to the aft end of the wake-generating body. For the range of parameters used in these experiments, results indicate that radiated noise is primarily a function of orifice radius and the turbulence parameters, and only secondarily of gas flow rates. One possible mechanism for the generation of this noise may be related to a critical Weber number.
Acoustic slow waveguide antenna
Authors: Rogers Peter H. , Trott W. James
Published: October 2005

The acoustic analog of the dielectric rod antenna for electromagnetic radiation is investigated both theoretically and experimentally. In acoustics, a cylinder of silicone rubber (whose bulk sound speed is about two-thirds that of water) is analogous to the dielectric rod. An acoustic wave in the direction parallel to the axis of the waveguide is concentrated within the guide by progressive refraction. A hydrophone (whose free-field sensitivity is omnidirectional) is attached near one end of the waveguide and detects this concentrated radiation as a gain in signal for this direction relative to any other direction. Similarly, if the slow waveguide is attached to an acoustic source, it will enhance the source level in the direction of the waveguide. The antenna is mathematically modeled by coupling the surface Helmholtz integral equation appropriate to the region within the silicone waveguide to a similar equation for the water region exterior to the cylinder (which includes the point hydrophone) by requiring continuity of acoustic pressure and normal velocity on the common surface. The coupled integral equations are solved numerically. Predicted beam patterns and directivity gains are in excellent agreement with experiment. Broad-band directivity gains of over 9 dB are both predicted and observed for two test antennas.
Technique for investigating the sensitivity of ray theory to small changes in environmental data
Authors: Solomon Louis P. , Merx William C.
Published: October 2005

In order to effectively use a ray tracing model, it is advisable to determine its sensitivity to small perturbations in the velocity of sound. A model to compute transmission loss based on ray theory and using cubic splines for the sound velocity profile (SVP) is presented and its sensitivity is examined. The SVP is perturbed randomly and the mean and standard deviation of the transmission loss is computed.
Rectified heat transfer
Authors: Wang Tunglu
Published: October 2005

A theory of rectified heat transfer is developed based on the result of evaporation effect on an oscillating bubble [T. Wang, Div. Appl. Math., Brown U. Tech. Rep. GK-22569/2 (May, 1972)]. The net heat transfer is expressed in terms of the exponential integral function with complex argument. As a corollary, the solution of rectified diffusion of mass for a gas bubble is obtained for all frequency ranges. In particular, for isothermal oscillation in the thin diffusion layer approximation, the result of Hsieh-Plesset is recovered.
Ultrasonic attenuation in para hydrogen
Authors: Weinberg Michael
Published: October 2005

The ultrasonic attenuation and sound-velocity dispersion from para hydrogen are calculated employing the translational hydrodynamic equations developed by Desai and Kapral. The results are compared with experiment and with several alternative methods of calculating these quantities. In addition, some of the similarities and differences between the interpretation of a light-scattering experiment and an ultrasonic experiment from this system are discussed.
Piezoelectric trapped energy resonators vibrating in thickness-twist modes
Authors: de Jong G.
Published: October 2005

In the present paper we investigate theoretically the phenomenon of energy trapping in piezoelectric devices, operating in thickness-twist modes. For a single resonator we have computed the input impedance as a function of both the frequency and the width of the electrode. In addition, we have obtained the fundamental resonant frequency of the device as a function of the width of the electrode and the mass-loading. This is achieved by employing the integral equation formulation of piezoelectric diffraction problems. For a resonator with massless electrodes, the resonant frequency of the fundamental lateral mode and the lowest two inharmonic overtones have been computed as a function of the width of the electrodes. Also the influence of the mass-loading on the resonant frequency of the fundamental lateral mode has been studied. When considering a coupled resonator system, the first resonator is connected with an electric generator, while the second is connected with a load impedance. For this configuration the transfer function has been computed. Next, the second resonator is short-circuited and the input impedance of the first resonator is determined. Finally, the resonant frequency of both the even and the odd lateral mode of the resonator assembly is computed as a function of the spacing between the two resonators. As piezoelectric material we have taken the piezoelectric ceramic PZT-4.
Subjective judgment of artificial reverberation processes
Authors: Kotschy A. , Tarnoczy T. , Vicsi K.
Published: October 2005

Subjective comparisons were made of simulated reverberation curves of various shapes. The curves consist of one or two segments having different decay rates. A third parameter is background noise, which establishes the total duration of the decay. The results are rather complex: In longer processes subjects judged the length of reverberation in terms of total length, but in shorter processes the initial decay rate seemed to govern.
High-frequency masking-level differences with narrow-band noise signals
Authors: McFadden Dennis , Pasanen Edward G.
Published: October 2005

Masking-level differences (MLDs) were investigated at several frequencies using a method that permits control of the type, and magnitude, of the binaural information available for processing. 50-Hz bands of noise with center frequencies of 250, 500, 1000, 2000, and 4000 Hz served as the masker-signals. Detection performance was measured for two MLD and two non-MLD conditions with each noise band. In one MLD condition there was only an interaural difference in cycle-by-cycle time; in the other, only an interaural difference in level. When the sole binaural cue was an interaural level difference, large MLDs (6–12 dB) were obtained at the frequencies of greatest interest—2000 Hz and 4000 Hz. When the sole binaural cue was a cycle-by-cycle time difference, performance at these high frequencies was essentially identical to that in the comparable non-MLD condition.