scholarly journals Exact separation phenomenon for the eigenvalues of large Information-Plus-Noise type matrices. Application to spiked models

2014 ◽  
Vol 63 (6) ◽  
pp. 1875-1910 ◽  
Author(s):  
Mireille Capitaine
Keyword(s):  
Noise Type ◽  
Exact Separation ◽  
Spiked Models

Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC

2004 ◽  
Vol 286 (5) ◽  
pp. C1109-C1117 ◽  
Author(s):  
Liang Guo ◽  
Dawn Pietkiewicz ◽  
Evgeny V. Pavlov ◽  
Sergey M. Grigoriev ◽  
John J. Kasianowicz ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Outer Membrane ◽  
Cell Types ◽  
Rnase A ◽  
Mitochondrial Outer Membrane ◽  
Dependent Manner ◽  
Mitochondrial Apoptosis ◽  
Noise Type ◽  
Voltage Dependent

Recent studies indicate that cytochrome c is released early in apoptosis without loss of integrity of the mitochondrial outer membrane in some cell types. The high-conductance mitochondrial apoptosis-induced channel (MAC) forms in the outer membrane early in apoptosis of FL5.12 cells. Physiological (micromolar) levels of cytochrome c alter MAC activity, and these effects are referred to as types 1 and 2. Type 1 effects are consistent with a partitioning of cytochrome c into the pore of MAC and include a modest decrease in conductance that is dose and voltage dependent, reversible, and has an increase in noise. Type 2 effects may correspond to “plugging” of the pore or destabilization of the open state. Type 2 effects are a dose-dependent, voltage-independent, and irreversible decrease in conductance. MAC is a heterogeneous channel with variable conductance. Cytochrome c affects MAC in a pore size-dependent manner, with maximal effects of cytochrome c on MAC with conductance of 1.9–5.4 nS. The effects of cytochrome c, RNase A, and high salt on MAC indicate that size, rather than charge, is crucial. The effects of dextran molecules of various sizes indicate that the pore diameter of MAC is slightly larger than that of 17-kDa dextran, which should be sufficient to allow the passage of 12-kDa cytochrome c. These findings are consistent with the notion that MAC is the pore through which cytochrome c is released from mitochondria during apoptosis.

Working Memory Capacity May Influence Perceived Effort during Aided Speech Recognition in Noise

2012 ◽  
Vol 23 (08) ◽  
pp. 577-589 ◽  
Author(s):  
Mary Rudner ◽  
Thomas Lunner ◽  
Thomas Behrens ◽  
Elisabet Sundewall Thorén ◽  
Jerker Rönnberg
Keyword(s):  
Working Memory ◽  
Hearing Loss ◽  
Speech Recognition ◽  
Hearing Aid ◽  
Recognition Performance ◽  
Cognitive Capacity ◽  
Subjective Ratings ◽  
Perceived Effort ◽  
Noise Type ◽  
Speech Recognition In Noise

Background: Recently there has been interest in using subjective ratings as a measure of perceived effort during speech recognition in noise. Perceived effort may be an indicator of cognitive load. Thus, subjective effort ratings during speech recognition in noise may covary both with signal-to-noise ratio (SNR) and individual cognitive capacity. Purpose: The present study investigated the relation between subjective ratings of the effort involved in listening to speech in noise, speech recognition performance, and individual working memory (WM) capacity in hearing impaired hearing aid users. Research Design: In two experiments, participants with hearing loss rated perceived effort during aided speech perception in noise. Noise type and SNR were manipulated in both experiments, and in the second experiment hearing aid compression release settings were also manipulated. Speech recognition performance was measured along with WM capacity. Study Sample: There were 46 participants in all with bilateral mild to moderate sloping hearing loss. In Experiment 1 there were 16 native Danish speakers (eight women and eight men) with a mean age of 63.5 yr (SD = 12.1) and average pure tone (PT) threshold of 47. 6 dB (SD = 9.8). In Experiment 2 there were 30 native Swedish speakers (19 women and 11 men) with a mean age of 70 yr (SD = 7.8) and average PT threshold of 45.8 dB (SD = 6.6). Data Collection and Analysis: A visual analog scale (VAS) was used for effort rating in both experiments. In Experiment 1, effort was rated at individually adapted SNRs while in Experiment 2 it was rated at fixed SNRs. Speech recognition in noise performance was measured using adaptive procedures in both experiments with Dantale II sentences in Experiment 1 and Hagerman sentences in Experiment 2. WM capacity was measured using a letter-monitoring task in Experiment 1 and the reading span task in Experiment 2. Results: In both experiments, there was a strong and significant relation between rated effort and SNR that was independent of individual WM capacity, whereas the relation between rated effort and noise type seemed to be influenced by individual WM capacity. Experiment 2 showed that hearing aid compression setting influenced rated effort. Conclusions: Subjective ratings of the effort involved in speech recognition in noise reflect SNRs, and individual cognitive capacity seems to influence relative rating of noise type.

Response properties of units in the dorsal cochlear nucleus of unanesthetized decerebrate gerbil

1996 ◽  
Vol 75 (4) ◽  
pp. 1411-1431 ◽  
Author(s):  
K. A. Davis ◽  
J. Ding ◽  
T. E. Benson ◽  
H. F. Voigt
Keyword(s):  
Dorsal Cochlear Nucleus ◽  
Type I ◽  
Type Ii ◽  
Decerebrate Cat ◽  
Excitatory Response ◽  
Type Iii ◽  
Type Iv ◽  
Noise Type ◽  
Rate Versus ◽  
Excitatory Responses

1. The electrophysiological responses of single units in the dorsal cochlear nucleus of unanesthetized decerebrate Mongolian gerbil (Meriones unguiculatus) were recorded. Units were classified according to the response map scheme of Evans and Nelson as modified by Young and Brownell, Young and Voigt, and Shofner and Young. Type II units have a V-shaped excitatory response map similar to typical auditory nerve tuning curves but little or no spontaneous activity (SpAc < 2.5 spikes/s) and little or no response to noise. Type I/III units also have a V-shaped excitatory map and SpAc < 2.5 spikes/s, but have an excitatory response to noise. Type III units have a V-shaped excitatory map with inhibitory sidebands, SpAc > 2.5 spikes/s, and an excitatory response to noise. Type IV-T units typically also have a V-shaped excitatory map with inhibitory sidebands, but have a highly nonmonotonic rate versus level response to best frequency (BF) tones like type IV units, SpAc > 2.5 spikes/s, and an excitatory response to noise. Type IV units have a predominantly inhibitory response map above an island of excitation of BF, SpAc > 2.5 spikes/s, and an excitatory response to noise. We present results for 133 units recorded with glass micropipette electrodes. The purpose of this study was to establish a normative response map data base in this species for ongoing structure/function and correlation studies. 2. The major types of units (type II, type I/III, type III, type IV-T, and type IV) found in decerebrate cat are found in decerebrate gerbil. However, the percentage of type II (7.5%) and type IV (11.3%) units encountered are smaller and the percentage of type III (62.4%) units is larger in decerebrate gerbil than in decerebrate cat. In comparison, Shofner and Young found 18.5% type II units, 30.6% type IV units, and 23.1% type III units using metal electrodes. 3. Two new unit subtypes are described in gerbil: type III-i and type IV-i units. Type III-i units are similar to type III units except that type III-i units are inhibited by low levels of noise and excited by high levels of noise whereas type III units have strictly excitatory responses to noise. Type IV-i units are similar to type IV units except that type IV-i units are excited by low levels of noise and become inhibited by high levels of noise whereas type IV units have strictly excitatory responses to noise. Type III-i units are approximately 30% of the type III population and type IV-i units are approximately 50% of the type IV population. 4. On the basis of the paucity of classic type II units and the reciprocal responses to broadband noise of type III-i and type IV-i units, we postulate that some gerbil type III-i units are the same cell type and have similar synaptic connections as cat type II units. 5. Type II and type I/III units are distinguished from one another on the basis of both their relative noise response, rho, and the normalized slope of the BF tone rate versus level functions beyond the first maximum. Previously, type II units were defined to be those nonspontaneously active units with rho values < 0.3 where rho is defined as the ratio of the maximum noise response minus spontaneous rate to the maximum BF tone response minus spontaneous rate. In the gerbil, the average rho value for type II units is 0.25, although a few values are > 0.3, and the rate-level curves are consistently nonmonotonic with normalized slopes steeper than than -0.007/dB. The average rho value for type I/III units is 0.54, although a few values are < 0.3, and the rate-level curves tend to saturate with slopes shallower than -0.006/dB. In general, the response properties of type II units recorded in gerbil are similar to those recorded in decerebrate cat. 6. In comparison to decerebrate cat, the lower percentage of type IV units recorded in decerebrate gerbil may be due to a species difference (a reduced number of type II units in gerbil) or an electrode bias.

Localization of Sound Sources in Normal Hearing and in Hearing Impaired People

2011 ◽  
Vol 36 (4) ◽  
pp. 683-694 ◽  
Author(s):  
Marek Niewiarowicz ◽  
Tomasz Kaczmarek
Keyword(s):  
Traffic Noise ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Directional Hearing ◽  
Sound Sources ◽  
Hearing Ability ◽  
Modified Method ◽  
Noise Type ◽  
Impaired People ◽  
New System

Abstract This article presents results of investigations of the angle of directional hearing acuity (ADHA) as a measure of the spatial hearing ability with a special emphasis on people with hearing impairments. A modified method proposed by Zakrzewski has been used - ADHA values have been determined for 8 azimuths in the horizontal plane at the height of the listeners' head. The two-alternative-forced-choice method (2AFC), based on a new system of listeners' responses (left - right instead of no difference - difference in location of sound sources) was the procedure used in the experiment. Investigations were carried out for two groups of subjects: normal hearing people (9 persons) and hearing impaired people (sensorineural hearing loss and tinnitus - 9 persons). In the experiment different acoustic signals were used: sinusoidal signals (pure tones), 1/3 octave noise, amplitude modulated 1/3 octave noise, CCITT speech and traffic noises and signals corresponding to personal character of tinnitus for individual subjects. The results obtained in the investigations showed, in general, a better localization of the sound source for noise type signals than those for tonal signals. Inessential differences exist in ADHA values for particular signals between the two groups of subjects. On the other hand, significant differences for tinnitus signals and traffic noise signals were stated. A new system of listeners' responses was used and appeared efficient (less dispersion of results compared to the standard system).

scholarly journals Exact separation of radial and angular correlation energies in two-electron atoms

2019 ◽  
Vol 720 ◽  
pp. 93-96
Author(s):  
Anjana R. Kammath ◽  
Raghunathan Ramakrishnan
Keyword(s):  
Angular Correlation ◽  
Exact Separation

scholarly journals Digital methods for measuring grain size parameters of aggregate–binder mixtures.

2013 ◽  
Vol 47 (4) ◽  
pp. 1834
Author(s):  
E. Profitis ◽  
D. Kapatos ◽  
E. Chatzitheodoridis ◽  
D. Xirouchakis ◽  
C. Loupasakis
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
Geometrical Parameters ◽  
Bituminous Mixtures ◽  
Dimensional Measurements ◽  
Digital Methods ◽  
Significant Cost Reduction ◽  
Future Work ◽  
Grain Size Parameters ◽  
Exact Separation

Geometrical parameters of natural and crushed aggregates such as grain length, perimeter, area, etc., underline the shape and flakiness indices definition. The latter indices have a measurable effect on the mechanical properties of aggregates–binder mixtures, e.g. concrete, mortar, bituminous mixtures. In this work, digital methods were developed with the mathematical software Matlab, by applying a statistical method called k-means clustering for the exact separation between background and aggregates to compute the aforementioned properties. The overall code can be applied in real time by analysing quickly a large volume of data with accuracy and significant cost reduction. Currently, only the two dimensions of the grains could be measured. Future work will focus on full three-dimensional measurements by comparing paired images taken from different angles but also aggregate segmentation in case of touching particles.

scholarly journals Testing RNN-LSTM Forecasting with Simulated Astronomical Lightcurves

2019 ◽  
Author(s):  
Nachiketa Chakraborty
Keyword(s):  
Time Series ◽  
Short Term Memory ◽  
Flicker Noise ◽  
Temporal Structure ◽  
Batch Size ◽  
Electromagnetic Spectrum ◽  
X Rays ◽  
Optimal Test ◽  
Noise Type ◽  
Lstm Network

With an explosion of data in the near future, from observatories spanning from radio to gamma-rays, we have entered the era of time domain astronomy. Historically, this field has been limited to modeling the temporal structure with time-series simulations limited to energy ranges blessed with excellent statistics as in X-rays. In addition to ever increasing volumes and variety of astronomical lightcurves, there's a plethora of different types of transients detected not only across the electromagnetic spectrum, but indeed across multiple messengers like counterparts for neutrino and gravitational wave sources. As a result, precise, fast forecasting and modeling the lightcurves or time-series will play a crucial role in both understanding the physical processes as well as coordinating multiwavelength and multimessenger campaigns. In this regard, deep learning algorithms such as recurrent neural networks (RNNs) should prove extremely powerful for forecasting as it has in several other domains. Here we test the performance of a very successful class of RNNs, the Long Short Term Memory (LSTM) algorithms with simulated lightcurves. We focus on univariate forecasting of types of lightcurves typically found in active galactic nuclei (AGN) observations. Specifically, we explore the sensitivity of training and test losses to key parameters of the LSTM network and data characteristics namely gaps and complexity measured in terms of number of Fourier components. We find that typically, the performances of LSTMs are better for pink or flicker noise type sources. The key parameters on which performance is dependent are batch size for LSTM and the gap percentage of the lightcurves. While a batch size of $10-30$ seems optimal, the most optimal test and train losses are under $10 \%$ of missing data for both periodic and random gaps in pink noise. The performance is far worse for red noise. This compromises detectability of transients. The performance gets monotonically worse for data complexity measured in terms of number of Fourier components which is especially relevant in the context of complicated quasi-periodic signals buried under noise. Thus, we show that time-series simulations are excellent guides for use of RNN-LSTMs in forecasting.

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