Effects of nosocusis, and industrial and gun noise on hearing of U.S. adults.

Hearing losses estimated for exposure to industrial and gun noise and for "typical" nosocusis are applied to the distributions of the hearing levels of adult males and females of the general population of an industrialized society unscreened for exposure to noise or ear disease. Noise exposure and demographic data applicable to the United States, and procedures for predicting noise-induced permanent threshold shift (NIPTS) and nosocusis, were used to account for some 8.7 dB of the 13.4 dB average difference between the hearing levels at high frequencies for otologically and noise screened versus unscreened male ears; (this average difference is for the average of the hearing levels at 3000, 4000, and 6000 Hz, average for the 10th, 50th, and 90th percentiles, and ages 20-65 years). According to the present calculations, this difference is due, in order of importance, to (1) nosocusis, (2) exposure to gun noise, and (3) exposure of workers to industrial noise. For these same frequencies and overall average, adjustments for nosocusis accounts for 2 dB of the 5.9-dB difference between the hearing levels of screened and unscreened female ears. For the average at 500, 1000, and 2000 Hz, the overall differences between the screened and unscreened populations is but 3.4 dB for males and 2.9 dB for females. The adjustment procedures reduced these differences to -0.5 and 0.9 dB, respectively.     

Optimisation of damping treatments based on big bang–big crunch and modal strain energy methods

A cost-effective methodology is needed in various applications in order to optimise damping treatments for structures. Although some methods appear to be applicable for structures with relatively simple geometries, it is still difficult to utilise them for general structures. This paper presents an efficient approach for optimisation of passive damping treatments that can be applied to general structures. First, an optimisation procedure based on big bang–big crunch optimisation method is introduced and its effectiveness for damping optimisation is evaluated. Then, a procedure based on modal strain energy method is presented for the prediction of modal damping levels for structures with damping treatments and its performance is assessed. After that, for validation purposes, the proposed optimisation methodology is used to maximise modal damping for a single mode of a structure whose optimised configurations are known for the individual modes. Finally, the performance of the proposed optimisation procedure is demonstrated for the maximisation of damping levels for multiple modes at the same time and the applicability of the approach for general structures with passive damping treatments is demonstrated.     

Effects of the use of personal music players on amplitude modulation detection and frequency discrimination

Measures of auditory performance were compared for an experimental group who listened regularly to music via personal music players (PMP) and a control group who did not. Absolute thresholds were similar for the two groups for frequencies up to 2 kHz, but the experimental group had slightly but significantly higher thresholds at higher frequencies. Thresholds for the frequency discrimination of pure tones were measured for a sensation level (SL) of 20 dB and center frequencies of 0.25, 0.5, 1, 2, 3, 4, 5, 6, and 8 kHz. Thresholds were significantly higher (worse) for the experimental than for the control group for frequencies from 3 to 8 kHz, but not for lower frequencies. Thresholds for detecting sinusoidal amplitude modulation (AM) were measured for SLs of 10 and 20 dB, using four carrier frequencies 0.5, 3, 4, and 6 kHz, and three modulation frequencies 4, 16, and 50 Hz. Thresholds were significantly lower (better) for the experimental than for the control group for the 4- and 6-kHz carriers, but not for the other carriers. It is concluded that listening to music via PMP can have subtle effects on frequency discrimination and AM detection.     

Fluorescence intensity and anisotropy decays of the DNA stain Hoechst 33342 resulting from one-photon and two-photon excitation

We examined the steady-state and time-resolved fluorescence spectral properties of the DNA stain Hoechst 33342 for one-photon (OPE) and two-photon (TPE) excitation. Hoechst 33342 was found to display a large cross section for two-photon excitation within the fundamental wavelength range of pyridine 2 and rhodamine 6G dye lasers, 690 to 770 and 560 to 630 nm, respectively. The time-resolved measurements show that intensity decays are similar for OPE- and TPE. The anisotropy decay measurements of Hoechst 33342 in ethanol revealed the same correlation times for TPE as observed for OPE. However, the zero-time anisotropies recovered from anisotropy decay measurements are 1.4-fold higher for TPE than for OPE. The anisotropy spectra of Hoechst 33342 were examined in glycerol at ?20°C, revealing limiting values close to the theoretical limits for OPE (0.4) and TPE (0.57). The steady-state anisotropy for OPE decreases in the shorter-wavelength region (R6G dye laser, 280–315 nm), but the two-photon anisotropy for 560 to 630-nm excitation remains as high as in the long-wavelength region (690–770 nm). This result suggests that one-photon absorption is due to two electronic, but only one transition contributes to the two-photon absorption over the wavelength range from 580 to 770 nm. Our demonstration of these favorable two-photon properties for Hoechst 33342, and the high photostability of the dye reported by other laboratories, suggests that this dye will be valuable for time-resolved studies of DNA with TPE and for two-photon fluorescence microscopy.     

Routes to nonsequential double ionization

A method is proposed for the calculation of the S matrix for many-electron processes in intense-laser atom physics, in close analogy to the strong-field approximation for one-electron processes. Given a scenario of how some process evolves, corresponding approximations to the classical action are made which allow for the evaluation of the quantum-mechanical S matrix. The method is applied to the distribution of the total electronic momentum in nonsequential double ionization, and the results are compared to recent measurements. Good agreement is obtained for neon for a rescattering scenario. There is no comparable agreement for helium and argon, and possible alternative scenarios are discussed.     

Effects of frequency and duration on psychometric functions for detection of increments and decrements in sinusoids in noise

Psychometric functions for detecting increments or decrements in level of sinusoidal pedestals were measured for increment and decrement durations of 5, 10, 20, 50, 100, and 200 ms and for frequencies of 250, 1000, and 4000 Hz. The sinusoids were presented in background noise intended to mask spectral splatter. A three-interval, three-alternative procedure was used. The results indicated that, for increments, the detectability index d' was approximately proportional to delta I/I. For decrements, d' was approximately proportional to delta L. The slopes of the psychometric functions increased (indicating better performance) with increasing frequency for both increments and decrements. For increments, the slopes increased with increasing increment duration up to 200 ms at 250 and 1000 Hz, but at 4000 Hz they increased only up to 50 ms. For decrements, the slopes increased for durations up to 50 ms, and then remained roughly constant, for all frequencies. For a center frequency of 250 Hz, the slopes of the psychometric functions for increment detection increased with duration more rapidly than predicted by a "multiple-looks" hypothesis, i.e., more rapidly than the square root of duration, for durations up to 50 ms. For center frequencies of 1000 and 4000 Hz, the slopes increased less rapidly than predicted by a multiple-looks hypothesis, for durations greater than about 20 ms. The slopes of the psychometric functions for decrement detection increased with decrement duration at a rate slightly greater than the square root of duration, for durations up to 50 ms, at all three frequencies. For greater durations, the increase in slope was less than proportional to the square root of duration. The results were analyzed using a model incorporating a simulated auditory filter, a compressive nonlinearity, a sliding temporal integrator, and a decision device based on a template mechanism. The model took into account the effects of both the external noise and an assumed internal noise. The model was able to account for the major features of the data for both increment and decrement detection.     

Quasi-wavelet calculations of sound scattering behind barriers

Quasi-wavelets (QWs) are a representation of turbulence consisting of self-similar, eddy-like structures with random orientations and positions in space. They are used in this paper to calculate the scattering, due to turbulent velocity fluctuations, of sound behind noise barriers as a function of the size and spatial location of the eddies. The sound scattering cross-section for QWs of an individual size class (eddy size) is derived and shown to reproduce results for the von Kármán spectrum when the scattered energies from a continuous distribution of QW sizes are combined. A Bragg resonance condition is derived for the eddy size that scatters most strongly for a given acoustic wavenumber and scattering angle. Results for scattering over barriers show that, for typical barrier conditions, most of the scattered energy originates from eddies in the size range of approximately one-half to twice the size of the eddies responsible for maximum scattering. The results also suggest that scattering over the barrier due to eddies with a line of sight to both the source and receiver is generally significant only for frequencies above several kilohertz, for sources and receivers no more than a few meters below the top of the barrier, and for very turbulent atmospheric conditions.     

From workplace air measurement results toward estimates of exposure? Development of a strategy to assess exposure to manufactured nano-objects

In the past few years, an increasing number of studies on workplace air measurements on manufactured nano-materials and -objects have been published. Most of the studies had a more explorative character, so a direct interpretation to workers” exposure for a given exposure situation, activity, or process is not a straight-forward process. In general, the studies use a quite similar package of devices for near real-time monitoring of particle number- and mass concentration in size ranges <100 nm up to 10 μm, and the collection of samples for off-line characterization of air samples. Various approaches for addressing background concentrations and its use to indicate the potential for exposure to nano-objects could be observed. Within the EU-sponsored NANOSH project, a harmonized approach for measurement strategy, data analysis and reporting was developed. In addition to time/activity–concentration profiles as reported by most studies, this approach enables a first step to estimate the potential for exposure to manufactured nano-objects, more quantitatively. The NANOSH data will be collated into a base, which may form the starting point for a harmonized database facilitating overall analysis in near future, to derive estimates for exposure for several exposure situations.     

Nucleus-nucleus collisions: Intrinsic motion with external correlations

A consistent treatment of the relative and intrinsic motion which goes beyond the mean-field approach allows to include the fluctuations of the time-dependent mean field for the intrinsic as well as for the relative motion. Starting with the v. Neumann equation for the total density matrix, we derive a modified equation for the intrinsic many-body density matrix. This equation is used to obtain the quantum kinetic equations for the one-body density matrix and the two-body correlator. In the time-dependent single-particle basis, the occupation numbers change in time due to a collision term originating from residual two-body interactions which account for equilibration, and due to the fluctuations of the external mean field. The relations to TDHF with collision term are discussed. Special attention is paid to the conditions for a diabatic evolution of the single-particle states and to finite size effects which play an important role to make two-body collisions operative in finite nuclei.     

Transient propagation in media with classical or power-law loss

This paper addresses the problem of small-signal transient wave propagation in media whose absorption coefficient obeys power-law frequency dependence, i.e., alpha infinity omega n. Our approach makes use of previously derived relations between the absorption and dispersion based on the Kramers-Kronig relations. This, combined with a recently obtained solution to a causal convolution wave equation enable expressions to be obtained for one-dimensional transient propagation when n is in the range 0 < n < 3. For n = 2, corresponding to no dispersion, straightforward analytical expressions are obtained for a delta-function and a sinusoidal step function sources and these are shown to correspond to relations previously derived. For other values of n, the effects of dispersion are accounted for by using Fourier transforms. Examples are used to illustrate the results for normal and anomalous dispersive media and to examine the question as to the conditions under which the effects of dispersion should be accounted for, especially for wideband ultrasound pulses of the type used in B-mode tissue imaging. It is shown that the product of the attenuation and total propagation path can be used as a criterion for judging whether dispersion needs to be accounted for.     

Factors affecting vowel formant discrimination by hearing-impaired listeners

The goal of this study was to measure the ability of adult hearing-impaired listeners to discriminate formant frequency for vowels in isolation, syllables, and sentences. Vowel formant discrimination for F1 and F2 for the vowels /I epsilon ae / was measured. Four experimental factors were manipulated including linguistic context (isolated vowels, syllables, and sentences), signal level (70 and 95 dB SPL), formant frequency, and cognitive load. A complex identification task was added to the formant discrimination task only for sentences to assess effects of cognitive load. Results showed significant elevation in formant thresholds as formant frequency and linguistic context increased. Higher signal level also elevated formant thresholds primarily for F2. However, no effect of the additional identification task on the formant discrimination was observed. In comparable conditions, these hearing-impaired listeners had elevated thresholds for formant discrimination compared to young normal-hearing listeners primarily for F2. Altogether, poorer performance for formant discrimination for these adult hearing-impaired listeners was mainly caused by hearing loss rather than cognitive difficulty for tasks implemented in this study.     

Interpretation of measured spectral line shapes using a square-well potential: The absorption lines of cesium broadened by rare gases

A simple square-well potential is used as an aid in understanding the complicated evolution of the absorption lines and their associated satellites for cesium perturbed by the rare gases. New experimental halfwidth data for cesium perturved by Xe, Ar, and He are presented. In the case of Xe, data for the second, third and fourth members are presented to 30, 7, 1 rd (relative density), respectively. For Ar, data are presented for the third through the ninth member. The pressure range for the third and fourth members is from 0 to 20 rd. For the other members, it ranges to 8 rd for the fifth and to 2 rd for the ninth. Third and fourth member helium data are presented to about 20 and 8 rd, respectively. Several theoretical computer profiles are used to illustrate the evolution of the line and satellites with foreign gas pressure and these are compared with the experimental data.     

Relativity of the metric

Although the form of the metric is invariant for arbitrary coordinate transformations, the magnitudes of the elements of the metric are not invariant. For Cartesian coordinates these elements are equal to one and are on the diagonal. Such a unitary metric can also apply to arbitrary coordinates, but only for a coordinate system inhabitant (CSI), to whom these coordinates would appear to be Cartesian. The meaning for a non-Euclidean metric consequently appears to be a simple coordinate system transformation for the appropriate CSI. The conversion of arbitrary coordinates to the flat Cartesian ones can be accomplished by a sequence of isomorphic mappings linking the arbitrary coordinates to the flat Cartesian ones. This is shown for two, three, and four-dimensional spaces. It is also applied to toroidal metrics and fluidfilled spaces for toroidal vortices that are discontinuous, half-wavelength, electromagnetic dipole field distributions. A number of other applications are discussed.     

Diffusion of paramagnetically labeled proteins in cartilage: enhancement of the 1-D NMR imaging technique

Quantifying the diffusive transport of large molecules in avascular cartilage tissue is important both for planning potential pharamacological treatments and for gaining insight into the molecular-scale structure of cartilage. In this work, the diffusion coefficients of gadolinium-DTPA and Gd-labeled versions of four proteins-lysozyme, trypsinogen, ovalbumin, and bovine serum albumin (BSA) with molecular weights of 14,300, 24,000, 45,000, and 67,000, respectively-have been measured in healthy and degraded calf cartilage. The experimental technique relies on the effect of the paramagnetic on the relaxation properties of the surrounding water, combined with the time course of a 1-dimensional spatial profile of the water signal in the cartilage sample. The enhanced technique presented here does not require a prior measurement of the relaxivity of the paramagnetic compound in the sample of interest. The data are expressed as the ratio of the diffusion coefficient of a compound in cartilage to its diffusion coefficient in water. For healthy cartilage, this ratio was 0.34 +/- 0.07 for Gd-DTPA, the smallest compound, and fell to 0.3 +/- 0.1 for Gd-lysozyme, 0.08 +/- 0.04 for Gd-trypsinogen, and 0.07 +/- 0.04 for Gd-ovalbumin. Gd-BSA did not appear to enter healthy cartilage tissue beyond a surface layer. After the cartilage had been degraded by 24-h trypsinization, these ratios were 0.60 +/- 0.03 for Gd-DTPA, 0.40 +/- 0.08 for Gd-lysozyme, 0.42 +/- 0.09 for Gd-trypsinogen, 0.16 +/- 0.14 for Gd-ovalbumin, and 0.11 +/- 0.05 for Gd-BSA. Thus, degradation of the cartilage led to increases in the diffusion coefficient of up to fivefold for the Gd-labeled proteins. These basic transport parameters yield insights on the nature of pore sizes and chemical-matrix interactions in the cartilage tissue and may prove diagnostically useful for identifying the degree and nature of damage to cartilage.     

Pitch estimation by early-deafened subjects using a multiple-electrode cochlear implant

Numerical estimates of pitch for stimulation of electrodes along the 22-electrode array of the Cochlear Limited cochlear implant were obtained from 18 subjects who became deaf very early in life. Examined were the relationships between subject differences in pitch estimation, subject variables related to auditory deprivation and experience, and speech-perception scores for closed-set monosyllabic words and open-set Bamford-Kowal-Bench (BKB) sentences. Reliability in the estimation procedure was examined by comparing subject performance in pitch estimation with that for loudness estimation for current levels between hearing threshold and comfortable listening level. For 56% of subjects, a tonotopic order of pitch percepts for electrodes on the array was found. A deviant but reliable order of pitch percepts was found for 22% of subjects, and essentially no pitch order was found for the remaining 22% of subjects. Subject differences in pitch estimation were significantly related to the duration of auditory deprivation prior to implantation, with the poorest performance for subjects who had a longer duration of deafness and a later age at implantation. Subjects with no tonotopic order of pitch percepts had the lowest scores for the BKB sentence test, but there were no differences across subjects for monosyllabic words. Performance in pitch estimation for electrodes did not appear to be related to performance in the estimation procedure, as all subjects were successful in loudness estimation for current level.     

Chapman–Enskog solutions to arbitrary order in Sonine polynomials I: Simple,rigid-sphere gas

The Chapman–Enskog solutions of the Boltzmann equations provide a basis for the computation of important transport coefficients for both simple gases and gas mixtures. These coefficients include the viscosities, the thermal conductivities, and diffusion coefficients. The Chapman–Enskog solutions are also useful for computation of the associated slip and jump coefficients near surfaces. Generally, these solutions are expressed in terms of Sonine polynomial expansions. While it has been found that relatively, low-order expansions (of order 4) can provide reasonable precision in the computation of the transport coefficients (to about 1 part in 1000), the adequacy of the low-order expansions for computation of the slip and jump coefficients still needs to be explored. Also of importance is the fact that such low-order expansions do not provide good convergence (in velocity space) for the actual Chapman–Enskog solutions even though the transport coefficients derived from these solutions appear to be reasonable. Thus, it is of some interest to explore Sonine polynomial expansions to higher orders. It is our purpose in this paper to report the results of our investigation of high-order, standard, Sonine polynomial expansions for the viscosity and the thermal conductivity related Chapman–Enskog solutions for a simple, rigid-sphere gas where we have carried out our calculations using expansions to order 150 and where our reported values for the transport coefficients have been demonstrated to converge to at least 25 significant digits. We note that, for a rigid-sphere gas, all of the relevant integrals needed for these solutions are evaluated analytically as pure fractions and, thus, results to any desired precision may be obtained. This work also indicates how results may be obtained in a similar fashion for realistic intermolecular potential models, and how gas-mixture problems may also be addressed with some additional effort.     

Internal charging: a preliminary environmental specification forsatellites

Internal charging has been indicated as the cause of many satellite anomalies. In some cases, it has been argued that internal charging has caused satellite system failures. It may be possible to predict the occurrence of an internal charging threat in the future but that does not remove the necessity to know what the environmental threat may be. The existence, for many years now, of energetic electron and internal charging measurements in the inner magnetosphere provides the ability to identify the threat levels and generate internal charging specifications. The specifications must embody the worst-case environments that can be expected from magnetic storms and extreme solar/interplanetary conditions. Internal-charging environment specifications are needed by satellite manufacturers for setting design requirements for their systems. The specifications are also required for defining the worst-case energetic electron flux levels and total fluence levels from events. These are used for electron beam testing to verify that critical systems are immune to internal charging, for performing tests on subsystems, and for use in anomaly investigation programs. Data from the GOES, LANL, and CRRES satellites were used to develop preliminary internal-charging environment specifications for some commonly used orbits such as geosynchronous and Molniya or high earth orbits (HEO), and they are discussed. A specification is also given for a highly elliptical equatorial orbit that is used for lunar-transfer orbital maneuvers. The preliminary environments were used to estimate the shielding required to reduce worst-case electron fluxes to safe levels for these orbits     

HL-2M装置放电管理平台研制

HL-2M装置放电管理平台的主要功能是为装置运行人员提供一个运行时序系、PLC逻辑保护系统和反馈控制系统的平台.在放电间歇,它在历史数据的基础上预置下一次放电的各种控制波形、配置各个技术子系统的运行模式和运行参数.其基于反射内存的通讯机制主要负责将控制参数和预设波形以有效的、可靠的方式传递到其它子系统中.与各相关子系统...     

Electronic structure of CrAs and FeAs

As in a recent study for MnAs a two centre tight binding model consisting of itinerant metal d-states hybridizing with non-metal p-states was applied for CrAs and FeAs to calculate unpolarized and spin polarized local densities of states, ferromagnetic moments and band energies. The factor for the change of the d-band width relative to MnAs was estimated to be 1.3 for CrAs and 0.8 for FeAs. The self-consistent separation of the p- and d-band centres amounts to -1.3 eV for CrAs and -0.5 eV for FeAs providing a charge transfer of 0.8 and 0.6 electrons from the metal to the As atoms, correspondingly. One B8₁ structure and two B31 structures according to low and high temperature phases were studied for each compound. For CrAs self-consistent magnetic moments of 1.58 and 1.2μ_B were obtained, respectively. For FeAs no ferromagnetic moment could be stabilized unless the d-band width was substantially reduced. The results are discussed with respect to MnAs. The model is able to reproduce the increase and breakdown of the magnetic moment for the series CrAs-MnAs-FeAs. Furthermore, the correct structural trend B31-B8₁-B31 is obtained if the band energy differences are corrected by a constant of 0.3 eV. This correction is attributed to the failure of the model to provide absolute differences of total energies.     

Chiral Ag and Au Nanomaterials Based Optical Approaches for Analytical Applications

Sensing of chiral compounds has gained great attentions for many decades. Chiral nanomaterials with a greater surface area, optical properties, and stability have however not been well realized in this field. Herein, strategies for the preparation of chiral Ag and Au nanomaterials are focused upon, including Ag and Au nanoparticles conjugated with chiral molecules with/without containing fluorophores, chiral nanoassemblies of Ag and Au nanoparticles, and chiral Ag and Au nanoclusters. The chirality of nanomaterials originates from their core and/or ligand, meanwhile that for nanoassemblies results from their complex spatial configuration. An emphasis is given to circular dichroism, colorimetry/UV–vis absorption, and fluorescence detection modes for sensing enantiomers and achiral analytes using the chiral Ag and Au nanomaterials. Several interesting examples for quantitation of DNA, proteins, peptides, drugs, and pollutants are provided to highlight their potential as sensitive and selective nanomaterials for enantiomer recognition and sensing of achiral analytes. Several important issues to be solved when using chiral nanomaterials for chiral recognition are specified. Some strategies for improving the sensitivity and selectivity of chiral nanomaterials for chiral recognition are suggested. The aim is to bring more attention to the potential of chiral nanomaterials for sensing important analytes such as chiral drugs.