Alternative splicing at NAGNAG acceptors: simply noise or noise and more?
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Alternative Splicing↗
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PSA screening: correlating noise with noise?
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Bias↗
When noise becomes too much noise.
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Journal Article↗
Tachistoscopic detectability of dotted lines in dotted visual noise: signal-to-noise ratio.
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Discrimination, Psychological↗
[Signal to noise ratio and noise characteristics in coded aperture imaging].
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English Abstract↗
[Adjustment of dose-response relationship of industrial impulse noise induced high frequency hearing loss with different exchange rate].
OBJECTIVE: To explore a new method to evaluate the dose-response relationship between the noise exposure and prevalence of noise induced high frequency hearing loss. METHODS: Physical examination and questionnaire survey were conducted among 32 mechanical workers, 12 males and 20 females, aged 35.1 +/- 7.2, exposed to industrial impulse noise (impulse noise group), and 163 textile workers, 82 males and 81 females, aged 31.5 +/- 8.7, exposed continuous noise (continuous noise group). SH-126 dosimeter was used to measure the A weighted equal sound level in continuous eight working hours (L(Aeq.8h)) so as to evaluate the individual noise exposure. Cumulative noise exposure (CNE) was calculated with the values of L(Aeq.8h) and noise working year adjusted by different exchange rates (ERs) for each worker. Hearing threshold was measured by audiometer with routine method and adjusted by age and gender according to GBZ49-2002. High frequency hearing loss was diagnosed based on the GBZ49-2002 for each worker. RESULTS: According to the equal energy rule, with the ER = 3 the CNE of the impulse noise group was [103.2 dB (A).year +/- 4.2dB (A).year], significantly lower than that of the continuous noise group [110.6 +/- 6.0 dB (A).year, P < 0.05]. With the ER = 5.5, the CNE of the impulse noise group was 110.3 +/- 6.6 dB (A).year, not significantly different from that of the continuous noise group [110.6 +/- 6.0 dB (A).year]. The high frequency hearing loss prevalence of the impulse noise group was 68.8%, not significantly different that of the continuous noise group (65%, P > 0.05). Trend chi square test showed significant differences in the relationship between CNE and hearing loss prevalence among the impulse noise group with the ER = 3, the impulse noise group with the ER = 5.5, and continuous noise group (all P < 0.01). With the ER = 3, the high frequency hearing loss prevalence of the impulse noise group with the CNE of 100-104 dB (A).year was 76.9%, significant higher than that of the continuous noise group (30.4%, P < 0.05); and the high frequency hearing loss prevalence of the impulse noise group with the CNE of 105-108 dB (A).year was 90.9%, significantly higher than that of the continuous noise group (50.0%, P < 0.05). With the ER = 5.5, there was no difference in the prevalence of high frequency hearing loss between the continuous noise group and impulse noise group. Logistic regression model showed that with the ER = 3, the dose-response curve of the impulse noise group presented a left shift and with a slope sharper than that of the continuous noise group. With the ER increasing the dose-response curve of the impulse noise group showed a right shift and with a gradually lowering slope. When the ER equaled to 6 in the impulse noise group and equaled to 3 in the continuous noise group, the two dose-response curves were almost superposed. CONCLUSION: Impulse noise causes more serious damage in causing high frequency hearing loss than continuous noise according to equal energy rule. Increasing the ER value in the impulse noise group adjusts the dose-response curve to be close to that of the continuous noise group.
Adult↗
Effects of masker gating for signal detection in unmodulated and modulated bandlimited noise.
Thresholds for a 400-ms 1000-Hz pure-tone signal were obtained as a function of masking noise bandwidth for unmodulated and square wave modulated masking noise. Rates of modulation were 10 and 40 Hz. Noise bandwidths were 128 Hz, 387 Hz, 921 Hz, and 1505 Hz. The masking noise was either continuous or gated on and off with the signal. In general, signal thresholds were relatively constant as a function of noise bandwidth in unmodulated noise, and improved as a function of increasing noise bandwidth in modulated noise. Noise gating had little or no effect on signal threshold in unmodulated noise. At the 10-Hz modulation rate, signal thresholds were somewhat higher in gated than in continuous noise at relatively narrow noise bandwidths, but thresholds were similar in gated and continuous noise for relatively wide noise bandwidths. At bandwidths of 387, 921, and 1505 Hz, comodulation masking release (CMR) was calculated as the unmodulated noise threshold minus the modulated noise threshold, corrected by the difference between the unmodulated noise threshold and the modulated noise threshold at the 128-Hz bandwidths. At wide masker bandwidth, CMRs were higher for gated noise than for continuous noise. This was due almost entirely to the threshold gating effect found in the 128-Hz bandwidth condition. These results suggested that there was a within-channel effect for gated noise thresholds to be higher than continuous noise thresholds, but essentially no across-channel effect of gating. At the 40-Hz modulation rate, signal thresholds were similar for gated and continuous noise at all noise bandwidths. There was a very small but significant' effect for the gated noise threshold to be lower than the continuous noise threshold at the widest noise bandwidth. It was speculated that this effect may be related to a decrease in sensitivity to modulation with continuous stimulation. In general, effects of gating appear to be small or absent for across-channel masking release in broadband modulated masking noise.
Adult↗
Additive noise properties of active matrix flat-panel imagers.
A detailed theoretical and empirical investigation of additive noise for indirect detection, active matrix flat-panel imagers (AMFPIs) has been performed. Such imagers comprise a pixelated array, incorporating photodiodes and thin-film transistors (TFTs), and an associated electronic acquisition system. A theoretical model of additive noise, defined as the noise of an imaging system in the absence of radiation, has been developed. This model is based upon an equivalent-noise-circuit representation of an AMFPI. The model contains a number of uncorrelated noise components which have been designated as pixel noise, data line thermal noise, externally coupled noise, preamplifier noise and digitization noise. Pixel noise is further divided into the following components: TFT thermal noise, shot and 1/f noise associated with the TFT and photodiode leakage currents, and TFT transient noise. Measurements of various additive noise components were carried out on a prototype imaging system based on a 508 microm pitch, 26 x 26 cm2 array. Other measurements were performed in the absence of the array, involving discrete components connected to the preamplifier input. Overall, model predictions of total additive noise as well as of pixel, preamplifier, and data line thermal noise components were in agreement with results of their measured counterparts. For the imaging system examined, the model predicts that pixel noise is dominated by shot and 1/f noise components of the photodiode and TFT at frame times above approximately 1 s. As frame time decreases, pixel noise is increasingly dominated by TFT thermal noise. Under these conditions, the reasonable degree of agreement observed between measurements and model predictions provides strong evidence that the role of TFT thermal noise has been properly incorporated into the model. Finally, the role of the resistance and capacitance of array data lines in the model was investigated using discrete component circuits at the preamplifier input. Measurements of preamplifier noise and data line thermal noise components as a function of input capacitance and resistance were found to be in reasonable agreement with model predictions.
Electronics↗
[Effect of intermittent noise on the function of concentration maintenance (TAF) and the brain waves (author's transl)].
The effect of three different kinds of noise, having equal physical energy but different psychological load, was examined by the TAF-test and the brain waves. Thirty nine healthy male subjects aging from 19 to 34 were exposed to white noise of 80 dB (C) under the following three conditions: (1) continuous noise for ten minutes, (2) regular intermittent noise, consisted of one-minute noise and one-minute rest, for 19 minutes, and (3) irregular intermittent noise, consisted of one-minute noise and irregular rest period, for 19 minutes. In each condition, the duration of noise-exposure totals ten minutes. Before, during and after the noise-exposure, the TAF-test was given to the 23 subjects out of 39, and the brain waves were recorded from the rest 16 subjects. The changes of TAF-L and alpha wave appearance were compared. The results obtained were as follows. 1. All three kinds of noise-exposure caused significant lowering of the function of concentration maintenance, especially in the latter half period of the noise administration. 2 Lowering of the function of concentration maintenance due to the irregular intermittent noise-exposure was greater than that due to the regular intermittent noise-exposure. 3. As to the continuous noise-exposure, appearance of the alpha wave decreased significantly in the 9th to 10th minute of noise administration and in the 1st min. after the exposure, while it increased in the 18th to 22nd min. after the exposure. 4. Exposure to the regular intermittent noise resulted in a significant decrease of the alpha wave appearance at the latter half of the noise administration, which continued after the exposure. 5. Exposure to the irregular intermittent noise caused a significant decrease of the alpha wave appearance after the middle period of noise administration. 6. Comparing the regular intermittent noise and irregular one, the latter brought about stronger alpha-blocking during the noise administration, but earlier restoration after the exposure. These results indicate that the influences of noise as a stressor differ not only by the amount of its physical energy but also by the condition of its generation, and that the differences of on-off effect on the brain activities based on regular or irregular intermittent noise were grasped by the changes of the function of concentration maintenance and the alpha wave appearance.
Adult↗
Noise power fluctuations and the masking of sine signals.
This article is concerned with fluctuations in noise power and with the role that such fluctuations play in the masking of sine signals by noise. Several measures of noise fluctuations are discussed: the fourth moment of the waveform, the fourth moment of the envelope, and the crest factor. Relationships among these quantities are found for cases of equal-amplitude random-phase noise and Rayleigh-distributed-amplitude noise. Of particular interest is a special non-Gaussian noise called low-noise noise in which the fluctuations are small by any of our measures. The results of frozen-noise masking experiments are reported, where the noise waveform was fixed for all stimulus presentations. In separate experiments, equal-amplitude random-phase Gaussian noise, with typical fluctuations, and low-noise noise, with almost no fluctuations were used. The data show that for a noise bandwidth less than the critical bandwidth, the masked threshold is about 5 dB lower for low-noise noise than for Gaussian noise. When the noise bandwidth is larger than the critical bandwidth, the masked threshold is the same for both kinds of noise. It is concluded that noise power fluctuations increase masked threshold by about 5 dB and that filtering by the auditory system reintroduces fluctuations into broadband low-noise noise.
Acoustic Stimulation↗
Spatiotemporal noise covariance estimation from limited empirical magnetoencephalographic data.
The performance of parametric magnetoencephalography (MEG) and electroencephalography (EEG) source localization approaches can be degraded by the use of poor background noise covariance estimates. In general, estimation of the noise covariance for spatiotemporal analysis is difficult mainly due to the limited noise information available. Furthermore, its estimation requires a large amount of storage and a one-time but very large (and sometimes intractable) calculation or its inverse. To overcome these difficulties, noise covariance models consisting of one pair or a sum of multi-pairs of Kronecker products of spatial covariance and temporal covariance have been proposed. However, these approaches cannot be applied when the noise information is very limited, i.e., the amount of noise information is less than the degrees of freedom of the noise covariance models. A common example of this is when only averaged noise data are available for a limited prestimulus region (typically at most a few hundred milliseconds duration). For such cases, a diagonal spatiotemporal noise covariance model consisting of sensor variances with no spatial or temporal correlation has been the common choice for spatiotemporal analysis. In this work, we propose a different noise covariance model which consists of diagonal spatial noise covariance and Toeplitz temporal noise covariance. It can easily be estimated from limited noise information, and no time-consuming optimization and data-processing are required. Thus, it can be used as an alternative choice when one-pair or multi-pair noise covariance models cannot be estimated due to lack of noise information. To verify its capability we used Bayesian inference dipole analysis and a number of simulated and empirical datasets. We compared this covariance model with other existing covariance models such as conventional diagonal covariance, one-pair and multi-pair noise covariance models, when noise information is sufficient to estimate them. We found that our proposed noise covariance model yields better localization performance than a diagonal noise covariance, while it performs slightly worse than one-pair or multi-pair noise covariance models - although these require much more noise information. Finally, we present some localization results on median nerve stimulus empirical MEG data for our proposed noise covariance model.
Algorithms↗
Noise analysis of a digital radiography system.
The sources of noise in a digital video subtraction angiography system were identified and analyzed. Signal-to-noise ratios of digital radiography systems were measured using the digital image data recorded in the computer. The major sources of noise include quantum noise, TV camera electronic noise, quantization noise from the analog-to-digital converter, time jitter, structure noise in the image intensifier, and video recorder electronic noise. A new noise source was identified, which results from the interplay of fixed pattern noise and the lack of image registration. This type of noise may result from image-intensifier structure noise in combination with TV camera time jitter or recorder time jitter. A similar noise source is generated from the interplay of patient absorption inhomogeneities and patient motion or image re-registration. Signal-to-noise ratios were measured for a variety of experimental conditions using subtracted digital images. The measured signal-to-noise ratios were found to fluctuate on repeat trials with about a 10% standard deviation. Averaging of video frames was found to reduce the noise level by the expected square root N relation, where N is the number of frames averaged. Image-intensifier structure noise was shown to be a dominant noise source in unsubtracted images at medium to high radiation exposure levels. A total-system signal-to-noise ratio (SNR) of 750:1 was measured for an input exposure of 1 mR/frame at the image intensifier input. The effect of scattered radiation on subtracted image SNR was found to be greater than previously reported. The detail SNR was found to vary approximately as one plus the scatter degradation factor. Quantization error noise with 8-bit image processors (signal-to-noise ratio of 890:1) was shown to be of increased importance after recent improvements in TV cameras. The results of the analysis are useful both in the design of future digital radiography systems and the selection of optimum clinical techniques.
Angiography↗
Physiological responses induced by 555-min exposure to intermittent noise.
Normal medical college students were exposed to noise for 555 min, while the Temporary Threshold Shift (TTS) and changes in the circulatory system were measured. The exposure noise employed was the so-called pink noise of a trapezoidal form. There were two time patterns, A(I) with 1 s of rise-decay time and 1 s of peak level, and A(II) with 500 ms of rise-decay time and 3.5 s of peak level. Thirteen exposure conditions were examined. The noise exposure time of all experiments was 555 min. The following results were obtained. 1. TTS Growth. Significant TTs increases were obtained following exposure to intermittent noise of 85 dB(A), intermittent noise of 80 dB(A), and steady state noise of various intensities. The TTS growth observed with steady state noise at 80 dB(A) was significantly greater than that of intermittent noise exposure at 85 dB(A). Moreover, TTS growth observed with steady noise at 82 dB(A) was significantly greater than that with intermittent noise exposure of 85 dB(A). However, the levels of TTS growth observed with steady state noise of 75 dB(A) and steady state noise at 77 dB(A) were almost equal to those of 6 s trapezoidal noise at 80 dB(A) (the "on fraction" being 33%), and 8 s trapezoidal noise at 80 dB(d) (the "on fraction' being 50%). In the above-mentioned experiments, significant increases of TTS growth were observed with various cycle times of trapezoidal noise with peak levels of 85 dB(A) and 80 dB(A), and with four exposure noise conditions of steady state. Under exposure conditions of 75 dB(A), trapezoidal noise with a 6 s cycle time (the "on fraction" being 33%) did not show a significant increase in TTS growth. 2. Changes in the Circulatory System. There were no significant differences in systolic and diastolic pressure or pulse rate among the three exposure conditions. The findings on ECG were as follows. Under intermittent noise exposure, decrease in the height of the T wave was observed in all examinees with a depression of the ST segments also being observed in two cases. On exposure to steady state noise, however, slight decrease in the height of the T wave was induced in only two cases, and under control conditions in only one case.
Adult↗
A comparison between the impact of noise from aircraft, road traffic and trains on long-term recall and recognition of a text in children aged 12-14 years.
A total of 417 students in the seventh grade, 12-14 old, took part in three 15 min learning sessions in their ordinary class-rooms. Their task was to read a text, and they were tested one week later with difficult recall questions and less difficult recognition items on the text. The first session was a pretest for their learning abilities. This session was run in ambient noise conditions and all the students read the very same text. The scores from this session were employed to split the pupils along the median into two groups of learning ability. Sessions two and three were counterbalanced as a noise condition or an ambient noise condition. In these sessions two other texts were employed, and they appeared equally often under the noise and ambient conditions, as well as under the two different presentation orders. Three subgroups of the pupils were exposed to aircraft noise, train noise and road-traffic noise. The noise types were of the same equivalent level (66 dB(A) Leq) in all subgroups. The design of the study permitted two different analyses of long-term learning. First, in a within subject analysis, the difference scores between the noise and ambient noise conditions in session 2 and 3 were calculated, and crossed with learning ability (high and low) and type of noise. In a second between subject analysis, the difference scores in session 1 and 2 were crossed with the group factor whether they had noise or ambient conditions in session 2, and the ability and noise type factors. Both analyses yielded the same results. Noise impaired long-term recall of the difficult items. Degree of impairment on the recall items did not interact with noise source or learning ability. The average impairment due to aircraft and road traffic noise was around 23% of the scores. Train noise had no effect. For the easy recognition items there were no effects of noise exposure, nor of its interaction with noise source and learning ability. Since the number of pages read did not differ between noise and ambient conditions, an explanation in terms of distraction is ruled out. The results are discussed in terms of arousal and cognitive overload.
Adolescent↗
Directional tuning of cells in area 18 of the feline visual cortex for visual noise, bar and spot stimuli: a comparison with area 17.
Directional tuning for visual noise, bar and single spot stimuli was compared over a wide range of velocities in cells from areas 17 and 18 of the visual cortex in lightly-anaesthetized cats. In each area, S-cells were predominantly insensitive to motion of a field of visual noise. C-cells were more sensitive to noise motion than B-cells, but showed heterogeneity in noise sensitivity, which was associated with other response properties: strongly noise-sensitive C-cells had relatively high spontaneous activity and broad directional tuning, and were predominantly direction-selective and binocularly-driven. Frequently, directional tuning for noise was unimodal at low velocity, but became progressively more bimodal as velocity was increased: a trough of depressed response corresponding to the peak in tuning for the bar separated two progressively more widely disparate preferred directions. In area 18, cells with velocity tuned (VT) functions for bar motion developed bimodal tuning for noise well below the optimum velocity for bar or for noise motion, while velocity high-pass (VHP) cells became progressively more bimodally tuned for noise over a wide range of velocities, in parallel with a steep increase in response to bar and noise motion. A high proportion of VT and VHP cells was bimodally tuned for noise at all velocities, one VHP cell showing two discrete lobes of tuning for noise below the threshold velocity for bar motion. Among cells which remained unimodally tuned for noise, VT and VHP cells in area 18 had radically dissimilar preferred directions for noise and bar motion at all velocities. With the exception of VHP cells, velocity bandpass was higher for noise than for bar motion. These results, together with other novel observations on the modality of tuning for noise in preferred and opposite directions of motion, demonstrate that bimodality of tuning for noise cannot simply be an effect of upper cut-off velocity for bar motion (Movshon et al. 1980; Orban 1984). It is argued that the trough between the lobes of tuning arises through laterally-directed inhibitory convergence from superficial- and deep-layer, large basket cells. In 40% of noise-sensitive cells, tuning for bar motion was broader on the flank closest to the preferred direction for noise and for a moving sport, while some 25% of cells showed variations in tuning for bar motion with velocity, which were associated with velocity-dependent changes in tuning for noise.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
The effect of noise check size and shape on grating detectability.
When noise checks are small, spatial noise mimics the effect of white noise in grating detection in the sense that contrast energy threshold is directly proportional to the spectral density of noise and the physical signal-to-noise ratio at threshold thus remains constant. We investigated how the size and shape of noise checks affect the masking properties of noise by using vertical and polar-circular gratings embedded in the spatial noise. The noise check shape and area was varied in both horizontal and vertical dimensions. For polar-circular gratings, noise mimicked the effect of white noise when both the noise check width and height were below a critical size. For vertical gratings there was a critical noise check width, but not critical noise check height. Thus, when the noise check side length was at or below the critical size across the grating bars, and at or below the stimulus size along the grating bars, contrast energy threshold was proportional to the spectral density of noise, calculated by multiplying the noise check area by the r.m.s contrast of noise squared both for one- and two-dimensional check noises.
Adult↗
Emergence of homeostasis and "noise imprinting" in an evolution model.
Homeostasis, the creation of a stabilized internal milieu, is ubiquitous in biological evolution, despite the entropic cost of excluding noise information from a region. The advantages of stability seem self evident, but the alternatives are not so clear. This issue was studied by means of numerical experiments on a simple evolution model: a population of Boolean network "organisms" selected for performance of a curve-fitting task while subjected to noise. During evolution, noise sensitivity increased with fitness. Noise exclusion evolved spontaneously, but only if the noise was sufficiently unpredictable. Noise that was limited to one or a few stereotyped patterns caused symmetry breaking that prevented noise exclusion. Instead, the organisms incorporated the noise into their function at little cost in ultimate fitness and became totally noise dependent. This "noise imprinting" suggests caution when interpreting apparent adaptations seen in nature. If the noise was totally random from generation to generation, noise exclusion evolved reliably and irreversibly, but if the noise was correlated over several generations, maladaptive selection of noise-dependent traits could reverse noise exclusion, with catastrophic effect on population fitness. Noise entering the selection process rather than the organism had a different effect: adaptive evolution was totally abolished above a critical noise amplitude, in a manner resembling a thermodynamic phase transition. Evolutionary adaptation to noise involves the creation of a subsystem screened from noise information but increasingly vulnerable to its effects. Similar considerations may apply to information channeling in human cultural evolution.
Algorithms↗
Protection efficiency of hearing protectors against military noise from handheld weapons and vehicles.
Noise attenuation against military noises has been measured in several cases under practical field conditions. Commercial and military versions of earmuff noise attenuation were measured against rifle noise. All the tested earmuffs attenuated the C-weighted peak level to less than 135 dB, which is less than the proposed recommendation value. Combat and shooting exercises create a risk of hearing damage, reaching a peak level of 180 dB. Measurements were done during attack exercises with blank and normal cartridges and during a defence exercise with normal cartridges. The noise exposure levels were relatively moderate (outside the ear 95-97 dB, in ear canal 82-85 dB) for military exercises. Peak levels of 110-120 dB for military trainers were measured in the ear canal during the conscript use of small-bore weapons. Combat vehicles and tanks are noisy, and for noise control during their use headgear with communication properties is worn. Noise inside such headgear was found to reach up to 120 dB, and the noise doses varied between 90 and 105 dB. Noise was also measured for aviation pilots in Finnish jet fighters. The cockpit values averaged 96 dB - 100 dB over the flight, whereas noise in the ear canal averaged 88 dB - 95 dB. The analyses indicated that radio noise is 4-10 dB higher inside the helmet than the background noise is, when measured as equivalent noise. The technicians on the ground were exposed to noise levels varying from 93 to 97 dB over the day. In practice, hearing protectors attenuate noise by 10-30 dB, depending on the frequency content of the noise sources. However, the difference when measured outside and inside hearing protectors varies by 5-10 dB because communication increases the noise level at the entrance of ear the canal. Currently the best protection for soldiers seems to be active noise cancellation ear muffs that are equipped for communication purposes and worn during the entire military exercise.
Ear Protective Devices↗