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Investigation the Link involving Nicotine gum Illnesses and also Alzheimer's: A Systematic Review.
This article uses a normal mode approach to predict atmospheric sound propagation over a locally reacting impedance plane. The semi-analytic finite element method is used to compute the normal modes, which enables the exact governing wave equation for a moving fluid to be solved in two dimensions. PF-06650833 ic50 A locally reacting surface is added using the general Ingard-Myers boundary condition, and the transmission loss is obtained for cylindrical and spherical spreading for range independent problems. The approach developed in this article will, in principle, converge toward the exact solution and so has the potential to provide benchmark predictions for complex, range independent, outdoor sound propagation problems. Predictions are shown to provide good agreement with benchmark solutions available in the literature, including those with a logarithmic wind velocity profile. Results are also reported for a combination of a logarithmic wind velocity profile and a temperature inversion for ranges of up to 5 km. Finally, transmission loss predictions are reported for a relatively wide frequency range, and it is concluded that finite elements can provide an alternative approach for computing range independent outdoor sound propagation that converges to the exact solution.The Reflections series takes a look back on historical articles from The Journal of the Acoustical Society of America that have had a significant impact on the science and practice of acoustics.Real-time accurate channel estimation has been an ongoing challenge because of diverse oceanic events that cause rapid fluctuations of high-energy multipath activity across the delay spread. This work leverages current compressed sensing and sparse optimization techniques with topological signal processing to improve estimation time and localize channel estimation to salient parts of the delay spread. This work improves the estimation time by tracking the channel as a union of overlapping multipath and other scattering events, which are modeled as "feature braids" in the delay-time domain. A channel feature braid may be intuitively visualized as the topologically connected trajectory of a group of channel delay taps, which represent the support of dominant or persistent scattering events, e.g., surface bounce multipath scattering. We present algorithms that harness support-constrained mixed norm optimization techniques to track the evolving support of channel feature braids. We validate our channel feature tracking algorithm independently in experimental field data as well as BELLHOP channel simulations across a diversity of oceanic conditions. This work shows that braiding used in estimation can improve estimation time and track high-energy events that develop within the delay vs time channel representation.This paper introduces and evaluates a speech signal manipulation scheme that generates transient speech induced binaural beats (SBBs). These SBBs can only be perceived when different signals are presented dichotically (to both ears). Event-related potentials were recorded in 22 normal-hearing subjects. Dichotic stimulus presentation reliably evoked auditory late responses (ALRs) in all subjects using such manipulated signals. As control measurements, diotic stimulation modalities were presented to confirm that the ALRs were not evoked by the speech signal itself or that the signal manipulation scheme created audible artifacts. Since diotic measurements evoked no ALRs, responses from dichotic stimulation are a pure correlate of binaural interaction. While there are several auditory stimuli (mostly modulated sinusoids or noise) that share this characteristic, none of them are based on running speech. Because SBBs can be added to any arbitrary speech signal, they could easily be combined with psychoacoustic tests, for example speech reception thresholds, adding an objective measure of binaural interaction.Numerical simulation of an acoustically driven gas bubble is usually achieved by solving a Rayleigh-Plesset-type equation, in which the time-dependent pressure of the gas inside the bubble needs to be appropriately modeled. This is done in most existing methods by assuming a polytropic relation between the gas pressure and the bubble volume, which sometimes oversimplifies the thermal interaction between the bubble and the ambient liquid. In this paper, a model is developed aiming to perform an accurate and efficient calculation of the pressure variation in the bubble. The approach is different from that in the recent paper by the author and his collaborator which used a combination of an integral and a collocation method to solve the energy equation in the gas [Zhou and Prosperetti (2020). J. Fluid Mech. 901, R3]. The starting point of the proposed method in this paper is the gas continuity equation which is manipulated to lead to three ordinary differential equations. In this way, the thermal behavior of an oscillating gas bubble is captured at a modest coding and computational cost.Auditory nerve responses to electrical stimulation exhibit aberrantly synchronous response latencies to low-rate pulse trains, nevertheless, cochlear implant users generally have elevated inter-aural timing difference detection thresholds. These findings present an apparent paradox in which single units are unusually precise but downstream within the auditory pathway access to this precision is lost. Auditory nerves innervating a region of cochlea exhibit natural heterogeneity in their diameter, myelination, and other structural properties; a key question is whether this diversity may contribute to the loss of temporal fidelity. In this work, responses of simulated auditory neuron populations with realistic intrinsic diameter and myelination heterogeneity to low-rate pulse trains were produced. By performing a receiver operating characteristic analysis on response latency distributions, ideal-observer interaural timing difference (ITD) detection limits were produced for each population. Fiber heterogeneity produced dispersion of inter-fiber latencies that produced ITD thresholds like that observed in the best performing cochlear implant users. Incorporation of myelin loss into these populations further increased inter-fiber latency variance and elevated ITD detection limits. These findings suggest that the interaction of applied currents with fibers' specific intrinsic properties may introduce fundamental limits on presentation of fine temporal structure in electrical stimulation.
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