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Cederblad, Anna Matilda Helena, Aleksandar Visokomogilski, Søren K. Andersen, Mary-Joan MacLeod y Arash Sahraie. "Conscious awareness modulates processing speed in the redundant signal effect". Experimental Brain Research 239, n.º 6 (17 de abril de 2021): 1877–93. http://dx.doi.org/10.1007/s00221-020-06008-1.
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AbstractEvidence for the influence of unaware signals on behaviour has been reported in both patient groups and healthy observers using the Redundant Signal Effect (RSE). The RSE refers to faster manual reaction times to the onset of multiple simultaneously presented target than those to a single stimulus. These findings are robust and apply to unimodal and multi-modal sensory inputs. A number of studies on neurologically impaired cases have demonstrated that RSE can be found even in the absence of conscious experience of the redundant signals. Here, we investigated behavioural changes associated with awareness in healthy observers by using Continuous Flash Suppression to render observers unaware of redundant targets. Across three experiments, we found an association between reaction times to the onset of a consciously perceived target and the reported level of visual awareness of the redundant target, with higher awareness being associated with faster reaction times. However, in the absence of any awareness of the redundant target, we found no evidence for speeded reaction times and even weak evidence for an inhibitory effect (slowing down of reaction times) on response to the seen target. These findings reveal marked differences between healthy observers and blindsight patients in how aware and unaware information from different locations is integrated in the RSE.
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Yang, Wenxing, Taihong Wu, Shasha Tu, Yuang Qin, Chengchen Shen, Jiangyun Li, Myung-Kyu Choi, Fengyun Duan y Yun Zhang. "Redundant neural circuits regulate olfactory integration". PLOS Genetics 18, n.º 1 (31 de enero de 2022): e1010029. http://dx.doi.org/10.1371/journal.pgen.1010029.
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Olfactory integration is important for survival in a natural habitat. However, how the nervous system processes signals of two odorants present simultaneously to generate a coherent behavioral response is poorly understood. Here, we characterize circuit basis for a form of olfactory integration in Caenorhabditis elegans. We find that the presence of a repulsive odorant, 2-nonanone, that signals threat strongly blocks the attraction of other odorants, such as isoamyl alcohol (IAA) or benzaldehyde, that signal food. Using a forward genetic screen, we found that genes known to regulate the structure and function of sensory neurons, osm-5 and osm-1, played a critical role in the integration process. Loss of these genes mildly reduces the response to the repellent 2-nonanone and disrupts the integration effect. Restoring the function of OSM-5 in either AWB or ASH, two sensory neurons known to mediate 2-nonanone-evoked avoidance, is sufficient to rescue. Sensory neurons AWB and downstream interneurons AVA, AIB, RIM that play critical roles in olfactory sensorimotor response are able to process signals generated by 2-nonanone or IAA or the mixture of the two odorants and contribute to the integration. Thus, our results identify redundant neural circuits that regulate the robust effect of a repulsive odorant to block responses to attractive odorants and uncover the neuronal and cellular basis for this complex olfactory task.
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Schwarz, W. "A new model to explain the redundant-signals effect". Perception & Psychophysics 46, n.º 5 (septiembre de 1989): 498–500. http://dx.doi.org/10.3758/bf03210867.
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Colonius, Hans. "Modeling the redundant signals effect by specifying the hazard function". Perception & Psychophysics 43, n.º 6 (diciembre de 1988): 604–6. http://dx.doi.org/10.3758/bf03207750.
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Li, N., R. Zhou y X. Z. Zhao. "Mechanical faulty signal denoising using a redundant non-linear second-generation wavelet transform". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, n.º 4 (abril de 2011): 799–808. http://dx.doi.org/10.1243/09544062jmes2410.
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Denoising and extraction of the weak signals are crucial to mechanical equipment fault diagnostics, especially for early fault detection, in which cases fault features are very weak and masked by the noise. The wavelet transform has been widely used in mechanical faulty signal denoising due to its extraordinary timefrequency representation capability. However, the mechanical faulty signals are often non-stationary, with the structure varying significantly within each scale. Because a single wavelet filter cannot mimic the signal structure of an entire scale, the traditional wavelet-based signal denoising method cannot achieve an ideal effect, and even worse some faulty information of the raw signal may be lost in the denoising process. To overcome this deficiency, a novel mechanical faulty signal denoising method using a redundant non-linear second generation wavelet transform is proposed. In this method, an optimal prediction operator is selected for each transforming sample according to the selection criterion of minimizing each individual prediction error. Consequently, the selected predictor can always fit the local characteristics of the signals. The signal denoising results from both simulated signals and experimental data are presented and both support the proposed method.
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Akçay, Çağlar y Michael D. Beecher. "Multi-modal communication: song sparrows increase signal redundancy in noise". Biology Letters 15, n.º 10 (octubre de 2019): 20190513. http://dx.doi.org/10.1098/rsbl.2019.0513.
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Although the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has focused on signals in a single modality. Consequently, how multi-modal communication is affected by anthropogenic noise is relatively poorly understood. Here, we ask whether song sparrows ( Melospiza melodia ) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. We test two hypotheses: (i) that song sparrows will shift signalling effort to the visual modality (the multi-modal shift hypothesis) and (ii) that they will increase redundancy of their multi-modal signalling (the back-up signal hypothesis). We presented male song sparrows with song playback and a taxidermic mount with or without a low-frequency acoustic noise from a nearby speaker. We found that males did not switch their signalling effort to visual modality (i.e. wing waves) in response to the noise. However, the correlation between warbled soft songs and wing waves increased in the noise treatment, i.e. signals became more redundant. These results suggest that when faced with anthropogenic noise, song sparrows can increase the redundancy of their multi-modal signals, which may aid in the robustness of the communication system.
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Schröter, Hannes, Anja Fiedler, Jeff Miller y Rolf Ulrich. "Fusion prevents the redundant signals effect: Evidence from stereoscopically presented stimuli." Journal of Experimental Psychology: Human Perception and Performance 37, n.º 5 (2011): 1361–68. http://dx.doi.org/10.1037/a0024280.
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Mishler, Ada y Mark Neider. "Evidence for the Redundant Signals Effect in Detection of Categorical Targets". Journal of Vision 16, n.º 12 (1 de septiembre de 2016): 1024. http://dx.doi.org/10.1167/16.12.1024.
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Töllner, Thomas, Michael Zehetleitner, Joseph Krummenacher y Hermann J. Müller. "Perceptual Basis of Redundancy Gains in Visual Pop-out Search". Journal of Cognitive Neuroscience 23, n.º 1 (enero de 2011): 137–50. http://dx.doi.org/10.1162/jocn.2010.21422.
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The redundant-signals effect (RSE) refers to a speed-up of RT when the response is triggered by two, rather than just one, response-relevant target elements. Although there is agreement that in the visual modality RSEs observed with dimensionally redundant signals originating from the same location are generated by coactive processing architectures, there has been a debate as to the exact stage(s)—preattentive versus postselective—of processing at which coactivation arises. To determine the origin(s) of redundancy gains in visual pop-out search, the present study combined mental chronometry with electrophysiological markers that reflect purely preattentive perceptual (posterior-contralateral negativity [PCN]), preattentive and postselective perceptual plus response selection-related (stimulus-locked lateralized readiness potential [LRP]), or purely response production-related processes (response-locked LRP). As expected, there was an RSE on target detection RTs, with evidence for coactivation. At the electrophysiological level, this pattern was mirrored by an RSE in PCN latencies, whereas stimulus-locked LRP latencies showed no RSE over and above the PCN effect. Also, there was no RSE on the response-locked LRPs. This pattern demonstrates a major contribution of preattentive perceptual processing stages to the RSE in visual pop-out search, consistent with parallel-coactive coding of target signals in multiple visual dimensions [Müller, H. J., Heller, D., & Ziegler, J. Visual search for singleton feature targets within and across feature dimensions. Perception & Psychophysics, 57, 1–17, 1995].
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Comert, Gurcan, Jacquan Pollard, David M. Nicol, Kartik Palani y Babu Vignesh. "Modeling Cyber Attacks at Intelligent Traffic Signals". Transportation Research Record: Journal of the Transportation Research Board 2672, n.º 1 (30 de julio de 2018): 76–89. http://dx.doi.org/10.1177/0361198118784378.
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Transportation networks are considered one of the critical physical infrastructures for resilient cities (cyber-physical systems). In efforts to minimize adverse effects that come with the advancement of vehicular technologies, various governmental agencies, such as the U.S. Department of Homeland Security and the National Highway Traffic Safety Administration (NHTSA), work together. This paper develops belief-network-based attack modeling at signalized traffic networks under connected vehicle and intelligent signals frameworks. For different types of cyber attacks, defined in the literature, risk areas and impacts of attacks are evaluated. Vulnerability scores, technically based on the selected metrics, are calculated for signal controllers. In addition, the effect of having redundant traffic sensing systems on intersection performance measures is demonstrated in terms of average queue length differences.
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Miller, Jeff, Rolf Ulrich y Yves Lamarre. "Locus of the redundant-signals effect in bimodal divided attention: A neurophysiological analysis". Perception & Psychophysics 63, n.º 3 (abril de 2001): 555–62. http://dx.doi.org/10.3758/bf03194420.
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Miller, Jeff. "Statistical facilitation and the redundant signals effect: What are race and coactivation models?" Attention, Perception, & Psychophysics 78, n.º 2 (10 de noviembre de 2015): 516–19. http://dx.doi.org/10.3758/s13414-015-1017-z.
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Schwarz, Wolfgang y Anja Ischebeck. "Coactivation and Statistical Facilitation in the Detection of Lines". Perception 23, n.º 2 (febrero de 1994): 157–68. http://dx.doi.org/10.1068/p230157.
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The redundant-signals effect describes the general phenomenon that simple reaction times to two simultaneously presented signals are typically faster than the corresponding reaction times to each of the signals presented alone. Recent studies (eg Miller 1982, 1986) indicate that models of probability summation in which an independent detection of both signals is assumed cannot completely account for the observed shortening of the reaction times. Therefore, models in which some kind of coactivation is assumed are often considered as an alternative explanation. In the present study simple reaction times to parallel lines are compared with those to orthogonal lines and single lines. Our first hypothesis is that because of the redundant-signals effect, the reaction time to configurations consisting of two lines (either parallel or orthogonal) will generally be faster than the reaction time to a single line. Furthermore, line detection can be related to orientation-specific line detectors. Therefore, parallel lines may be thought to activate similar line detectors and, by coactivation, facilitate detection. As our second hypothesis we thus expect that the reaction time to parallel lines will be shorter than the reaction time to orthogonal lines. To test these hypotheses, we conducted a simple reaction-time experiment in which signal onset asynchronies ranging from 0 to ±56 ms for the orthogonal lines were used. In addition, reaction times to parallel lines and single lines were measured. Both hypotheses are supported by our data. We formulate a stochastic model which is able to explain both statistical facilitation and coactivation in a physiologically plausible way.
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Enokihara, Akira, Tadashi Kawai y Tetsuya Kawanishi. "Optical two-tone generation and SSB modulation using electro-optic modulator with suppressing redundant spectrum components". International Journal of Microwave and Wireless Technologies 3, n.º 3 (27 de abril de 2011): 295–300. http://dx.doi.org/10.1017/s175907871100047x.
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Doubled frequency optical two-tone generation and optical single sideband (SSB) modulation by the dual-electrode-type electro-optic (EO) modulator with a single Mach–Zehnder (MZ) interferometer were considered. We theoretically showed that redundant spectrum components in the modulated optical signals, which are caused by the imbalance of light splitting ratio between the two arms of the interferometer, are significantly suppressed by controlling the input power ratio of RF modulation signals applied to each electrode. This effect was confirmed by the experiment, where an optical two-tone with the redundant components 49.8 dB lower than the primary two-tone components in intensity level was obtained. This method is also valid for suppression of undesired frequency components of RF signals that are generated at a photo detector from the optical two-tone waves propagated through a dispersive optical fiber.
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Tibbetts, Elizabeth A., Ming Liu, Emily C. Laub y Sheng-Feng Shen. "Complex signals alter recognition accuracy and conspecific acceptance thresholds". Philosophical Transactions of the Royal Society B: Biological Sciences 375, n.º 1802 (18 de mayo de 2020): 20190482. http://dx.doi.org/10.1098/rstb.2019.0482.
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Many aspects of behaviour depend on recognition, but accurate recognition is difficult because the traits used for recognition often overlap. For example, brood parasitic birds mimic host eggs, so it is challenging for hosts to discriminate between their own eggs and parasitic eggs. Complex signals that occur in multiple sensory modalities or involve multiple signal components are thought to facilitate accurate recognition. However, we lack models that explore the effect of complex signals on the evolution of recognition systems. Here, we use individual-based models with a genetic algorithm to test how complex signals influence recognition thresholds, signaller phenotypes and receiver responses. The model has three main results. First, complex signals lead to more accurate recognition than simple signals. Second, when two signals provide different amounts of information, receivers will rely on the more informative signal to make recognition decisions and may ignore the less informative signal. As a result, the particular traits used for recognition change over evolutionary time as sender and receiver phenotypes evolve. Third, complex signals are more likely to evolve when recognition errors are high cost than when errors are low cost. Overall, redundant, complex signals are an evolutionarily stable mechanism to reduce recognition errors. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.
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Ijaz, Salman, Mirza Tariq Hamayun, Lin Yan, Hamdoon Ijaz y Cun Shi. "Adaptive fault tolerant control of dissimilar redundant actuation system of civil aircraft based on integral sliding mode control strategy". Transactions of the Institute of Measurement and Control 41, n.º 13 (6 de mayo de 2019): 3756–68. http://dx.doi.org/10.1177/0142331219835589.
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In modern aircraft, the dissimilar redundant actuation system is used to resolve the actuator failure issues due to the common cause, thus increasing the system reliability. This paper proposes an adaptive integral sliding mode fault tolerant control strategy to deal with actuator fault/failure in the dissimilar redundant actuation system of civil aircraft. To cope with the unknown actuator faults, the adaptive integral sliding mode controller is designed where the modulation gain is made adaptive to the fault. To deal with the complete failure of certain actuator, the integral sliding mode control is integrated with control allocation scheme and distribute the control input signals to the redundant actuators. The performance of the proposed scheme is tested on the nonlinear model of dissimilar redundant actuation system, where the effect of external airload is accounted during simulations. The effectiveness of the proposed scheme is validated by comparing the simulations with the existing literature.
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Schröter, Hannes, Luisa S. Frei, Rolf Ulrich y Jeff Miller. "The auditory redundant signals effect: An influence of number of stimuli or number of percepts?" Attention, Perception, & Psychophysics 71, n.º 6 (agosto de 2009): 1375–84. http://dx.doi.org/10.3758/app.71.6.1375.
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Mordkoff, J. Toby. "Testing models of the redundant-signals effect: A warning concerning the combination-rule regression analysis". Perception & Psychophysics 52, n.º 5 (septiembre de 1992): 589–94. http://dx.doi.org/10.3758/bf03206721.
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Diederich, Adele y Hans Colonius. "A further test of the superposition model for the redundant-signals effect in bimodal detection". Perception & Psychophysics 50, n.º 1 (enero de 1991): 83–86. http://dx.doi.org/10.3758/bf03212207.
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Mishler, Ada D. y Mark B. Neider. "Absence of distracting information explains the redundant signals effect for a centrally presented categorization task". Acta Psychologica 181 (noviembre de 2017): 18–26. http://dx.doi.org/10.1016/j.actpsy.2017.10.002.
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Fiedler, Anja, Hannes Schröter, Verena C. Seibold y Rolf Ulrich. "The influence of dichotical fusion on the redundant signals effect, localization performance, and the mismatch negativity". Cognitive, Affective, & Behavioral Neuroscience 11, n.º 1 (16 de noviembre de 2010): 68–84. http://dx.doi.org/10.3758/s13415-010-0013-y.
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Wang, Weihao, Lixin Lu y Wang Wei. "A Novel Supervised Filter Feature Selection Method Based on Gaussian Probability Density for Fault Diagnosis of Permanent Magnet DC Motors". Sensors 22, n.º 19 (20 de septiembre de 2022): 7121. http://dx.doi.org/10.3390/s22197121.
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For permanent magnet DC motors (PMDCMs), the amplitude of the current signals gradually decreases after the motor starts. In this work, the time domain features and time-frequency-domain features extracted from several successive segments of current signals make up a feature vector, which is adopted for fault diagnosis of PMDCMs. Many redundant features will lead to a decrease in diagnosis efficiency and increase the computation cost, so it is necessary to eliminate redundant features and features that have negative effects. This paper presents a novel supervised filter feature selection method for reducing data dimension by employing the Gaussian probability density function (GPDF) and named Gaussian vote feature selection (GVFS). To evaluate the effectiveness of the proposed GVFS, we compared it with the other five filter feature selection methods by utilizing the PMDCM’s data. Additionally, Gaussian naive Bayes (GNB), k-nearest neighbor algorithm (k-NN), and support vector machine (SVM) are utilized for the construction of fault diagnosis models. Experimental results show that the proposed GVFS has a better diagnostic effect than the other five feature selection methods, and the average accuracy of fault diagnosis improves from 97.89% to 99.44%. This paper lays the foundation of fault diagnosis for PMDCMs and provides a novel filter feature selection method.
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Gui, Renzhou, Tongjie Chen y Han Nie. "Classification of Task-State fMRI Data Based on Circle-EMD and Machine Learning". Computational Intelligence and Neuroscience 2020 (1 de agosto de 2020): 1–10. http://dx.doi.org/10.1155/2020/7691294.
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In the research work of the brain-computer interface and the function of human brain work, the state classification of multitask state fMRI data is a problem. The fMRI signal of the human brain is a nonstationary signal with many noise effects and interference. Based on the commonly used nonstationary signal analysis method, Hilbert–Huang transform (HHT), we propose an improved circle-EMD algorithm to suppress the end effect. The algorithm can extract different intrinsic mode functions (IMFs), decompose the fMRI data to filter out low frequency and other redundant noise signals, and more accurately reflect the true characteristics of the original signal. For the filtered fMRI signal, we use three existing different machine learning methods: logistic regression (LR), support vector machine (SVM), and deep neural network (DNN) to achieve effective classification of different task states. The experiment compares the results of these machine learning methods and confirms that the deep neural network has the highest accuracy for task-state fMRI data classification and the effectiveness of the improved circle-EMD algorithm.
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Cederblad, Anna Matilda Helena, Juho Äijälä, Søren Krogh Andersen, Mary Joan MacLeod y Arash Sahraie. "Phasic Alertness and Multisensory Integration Contribute to Visual Awareness of Weak Visual Targets in Audio-Visual Stimulation under Continuous Flash Suppression". Vision 6, n.º 2 (3 de junio de 2022): 31. http://dx.doi.org/10.3390/vision6020031.
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Multisensory stimulation is associated with behavioural benefits, including faster processing speed, higher detection accuracy, and increased subjective awareness. These effects are most likely explained by multisensory integration, alertness, or a combination of the two. To examine changes in subjective awareness under multisensory stimulation, we conducted three experiments in which we used Continuous Flash Suppression to mask subthreshold visual targets for healthy observers. Using the Perceptual Awareness Scale, participants reported their level of awareness of the visual target on a trial-by-trial basis. The first experiment had an audio-visual Redundant Signal Effect paradigm, in which we found faster reaction times in the audio-visual condition compared to responses to auditory or visual signals alone. In two following experiments, we separated the auditory and visual signals, first spatially (experiment 2) and then temporally (experiment 3), to test whether the behavioural benefits in our multisensory stimulation paradigm could best be explained by multisensory integration or increased phasic alerting. Based on the findings, we conclude that the largest contributing factor to increased awareness of visual stimuli accompanied by auditory tones is a rise in phasic alertness and a reduction in temporal uncertainty with a small but significant contribution of multisensory integration.
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Lanman, Adam E. y Jonathan C. Pober. "Fundamental uncertainty levels of 21 cm power spectra from a delay analysis". Monthly Notices of the Royal Astronomical Society 487, n.º 4 (12 de junio de 2019): 5840–53. http://dx.doi.org/10.1093/mnras/stz1639.
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Abstract Several experimental efforts are underway to measure the power spectrum of 21 cm fluctuations from the epoch of reionization (EoR) using low-frequency radio interferometers. Experiments like the Hydrogen Epoch of Reionization Array (HERA) and Murchison Widefield Array Phase II (MWA) feature highly redundant antenna layouts, building sensitivity through redundant measurements of the same angular Fourier modes, at the expense of diminished UV coverage. This strategy limits the numbers of independent samples of each power spectrum mode, thereby increasing the effect of sample variance on the final power spectrum uncertainty. To better quantify this effect, we measure the sample variance of a delay-transform based power spectrum estimator, using both analytic calculations and simulations of flat-spectrum EoR-like signals. We find that for the shortest baselines in HERA, the sample variance can reach as high as 20 per cent, and up to 30 per cent for the wider fields of view of the MWA. Combining estimates from all the baselines in a HERA- or MWA-like 37 element redundant hexagonal array can lower the variance to 1−3 per cent for some Fourier modes. These results have important implications for observing and analysis strategies, and suggest that sample variance can be non-negligible when constraining EoR model parameters from upcoming 21 cm data.
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Aubin, Thierry y Pierre Jouventin. "Localisation of an acoustic signal in a noisy environment: the display call of the king penguin Aptenodytes patagonicus". Journal of Experimental Biology 205, n.º 24 (15 de diciembre de 2002): 3793–98. http://dx.doi.org/10.1242/jeb.205.24.3793.
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SUMMARY King penguin chicks identify their parents by an acoustic signal, the display call. This call consists of a succession of similar syllables. Each syllable has two harmonic series, strongly modulated in frequency and amplitude, with added beats of varying amplitude generated by a two-voice system. Previous work showed that only one syllable of the call is needed for the chick to identify the calling adult. Both the frequency modulation pattern of the syllable and the two-voice system play a role in the call identification. The syllabic organisation of the call, the harmonic structure and the amplitude modulations of the syllables apparently do not contribute to individual recognition. Are these acoustic features useless? To answer to this question, playback experiments were conducted using three categories of experimental signals: (i) signal with only the fundamental frequencies of the natural call, (ii) signal with the amplitude of each syllable kept at a constant level and (iii) signals with only one syllable, repeated or not. The responses of chicks to these experimental signals were compared to those obtained with the calls of their natural parents. We found that these acoustic features, while not directly implicated in the individual recognition process,help the chicks to better localise the signal of their parents. In addition,the redundant syllabic organisation of the call is a means of counteracting the masking effect of the background noise of the colony.
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Yiakopoulos, C. T. y I. A. Antoniadis. "Wavelet Based Demodulation of Vibration Signals Generated by Defects in Rolling Element Bearings". Shock and Vibration 9, n.º 6 (2002): 293–306. http://dx.doi.org/10.1155/2002/592436.
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Vibration signals resulting from roller bearing defects, present a rich content of physical information, the appropriate analysis of which can lead to the clear identification of the nature of the fault. The envelope detection or demodulation methods have been established as the dominant analysis methods for this purpose, since they can separate the useful part of the signal from its redundant contents. The paper proposes a new effective demodulation method, based on the wavelet transform. The method fully exploits the underlying physical concepts of the modulation mechanism, present in the vibration response of faulty bearings, using the excellent time-frequency localization properties of the wavelet analysis. The choice of the specific wavelet family is marginal to their overall effect, while the necessary number of wavelet levels is quite limited. Experimental results and industrial measurements for three different types of bearing faults confirm the validity of the overall approach.
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Otto, Thomas U., Brice Dassy y Pascal Mamassian. "Principles of multisensory behavior". Seeing and Perceiving 25 (2012): 4. http://dx.doi.org/10.1163/187847612x646271.
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The combined use of multisensory signals is often beneficial. Based on single cell recordings in the superior colliculius of cats, three basic rules were formulated to describe the effectiveness of multisensory integration: The enhancement of neuronal responses in multi- compared to uni-sensory conditions is largest when signals are presented at the same time (‘temporal rule’), occur at the same location (‘spatial rule’), and when signals are rather weak (‘principle of inverse effectiveness’). These rules are also considered to describe multisensory benefits as observed with behavioral measures, but do they capture these benefits best? To uncover the principles that rule multisensory behavior, we investigated the classical redundant signals effect, i.e., the speed-up of response times in multi- as compared to uni-sensory conditions. In a detection task, we presented both auditory and visual signals at three levels of signal strength and determined the speed-up for all nine combinations of signals. Based on a systematic analysis of empirical response time distributions as well as simulations using probability summation, we propose that two alternative rules apply. First, the ‘principle of equal effectiveness’ states that the benefit with multisensory signals (here the speed-up of reaction times) is largest when performance in the two uni-sensory conditions is similar. Second, the ‘variability rule’ states that the benefit is largest when performance in the uni-sensory conditions is variable. The generality of these rules is discussed with respect to experiments on accuracy and when maximum likelihood estimation instead of probability summation is considered as combination rule.
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Schwarz, Wolf. "On the relationship between the redundant signals effect and temporal order judgments: Parametric data and a new model." Journal of Experimental Psychology: Human Perception and Performance 32, n.º 3 (2006): 558–73. http://dx.doi.org/10.1037/0096-1523.32.3.558.
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Minakata, Katsumi y Matthias Gondan. "Differential coactivation in a redundant signals task with weak and strong go/no-go stimuli". Quarterly Journal of Experimental Psychology 72, n.º 4 (4 de mayo de 2018): 922–29. http://dx.doi.org/10.1177/1747021818772033.
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When participants respond to stimuli of two sources, response times (RTs) are often faster when both stimuli are presented together relative to the RTs obtained when presented separately (redundant signals effect [RSE]). Race models and coactivation models can explain the RSE. In race models, separate channels process the two stimulus components, and the faster processing time determines the overall RT. In audiovisual experiments, the RSE is often higher than predicted by race models, and coactivation models have been proposed that assume integrated processing of the two stimuli. Where does coactivation occur? We implemented a go/no-go task with randomly intermixed weak and strong auditory, visual, and audiovisual stimuli. In one experimental session, participants had to respond to strong stimuli and withhold their response to weak stimuli. In the other session, these roles were reversed. Interestingly, coactivation was only observed in the experimental session in which participants had to respond to strong stimuli. If weak stimuli served as targets, results were widely consistent with the race model prediction. The pattern of results contradicts the inverse effectiveness law. We present two models that explain the result in terms of absolute and relative thresholds.
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Bailey, Hudson Diggs, Aidan B. Mullaney, Kyla D. Gibney y Leslie Dowell Kwakye. "Audiovisual Integration Varies With Target and Environment Richness in Immersive Virtual Reality". Multisensory Research 31, n.º 7 (2018): 689–713. http://dx.doi.org/10.1163/22134808-20181301.
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Abstract We are continually bombarded by information arriving to each of our senses; however, the brain seems to effortlessly integrate this separate information into a unified percept. Although multisensory integration has been researched extensively using simple computer tasks and stimuli, much less is known about how multisensory integration functions in real-world contexts. Additionally, several recent studies have demonstrated that multisensory integration varies tremendously across naturalistic stimuli. Virtual reality can be used to study multisensory integration in realistic settings because it combines realism with precise control over the environment and stimulus presentation. In the current study, we investigated whether multisensory integration as measured by the redundant signals effects (RSE) is observable in naturalistic environments using virtual reality and whether it differs as a function of target and/or environment cue-richness. Participants detected auditory, visual, and audiovisual targets which varied in cue-richness within three distinct virtual worlds that also varied in cue-richness. We demonstrated integrative effects in each environment-by-target pairing and further showed a modest effect on multisensory integration as a function of target cue-richness but only in the cue-rich environment. Our study is the first to definitively show that minimal and more naturalistic tasks elicit comparable redundant signals effects. Our results also suggest that multisensory integration may function differently depending on the features of the environment. The results of this study have important implications in the design of virtual multisensory environments that are currently being used for training, educational, and entertainment purposes.
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Otto, Thomas U. y Pascal Mamassian. "Multisensory Decisions: the Test of a Race Model, Its Logic, and Power". Multisensory Research 30, n.º 1 (2017): 1–24. http://dx.doi.org/10.1163/22134808-00002541.
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The use of separate multisensory signals is often beneficial. A prominent example is the speed-up of responses to two redundant signals relative to the components, which is known as the redundant signals effect (RSE). A convenient explanation for the effect is statistical facilitation, which is inherent in the basic architecture of race models (Raab, 1962,Trans. N. Y. Acad. Sci.24, 574–590). However, this class of models has been largely rejected in multisensory research, which we think results from an ambiguity in definitions and misinterpretations of the influential race model test (Miller, 1982,Cogn. Psychol.14, 247–279). To resolve these issues, we here discuss four main items. First, we clarify definitions and ask how successful models of perceptual decision making can be extended from uni- to multisensory decisions. Second, we review the race model test and emphasize elements leading to confusion with its interpretation. Third, we introduce a new approach to study the RSE. As a major change of direction, our working hypothesis is that the basic race model architecture is correct even if the race model test seems to suggest otherwise. Based on this approach, we argue that understanding the variability of responses is the key to understand the RSE. Finally, we highlight the critical role of model testability to advance research on multisensory decisions. Despite being largely rejected, it should be recognized that race models, as part of a broader class of parallel decision models, demonstrate, in fact, a convincing explanatory power in a range of experimental paradigms. To improve research consistency in the future, we conclude with a short checklist for RSE studies.
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Saha, B., D. M. Harlan, K. P. Lee, C. H. June y R. Abe. "Protection against lethal toxic shock by targeted disruption of the CD28 gene." Journal of Experimental Medicine 183, n.º 6 (1 de junio de 1996): 2675–80. http://dx.doi.org/10.1084/jem.183.6.2675.
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Toxic shock syndrome (TSS) is a multi system disorder resulting from superantigen-mediated cytokine production. Nearly 90% of the clinical cases of TSS arise due to an exotoxin, toxic shock syndrome toxin-1 (TSST-1), elaborated by toxigenic strains of Staphylococcus aureus. It is clearly established that besides antigen-specific signals a variety of costimulatory signals are required for full T cell activation. However, the nature and potential redundancy of costimulatory signals are incompletely understood, particularly with regards to superantigen-mediated T cell activation in vivo. Here we report that CD28-deficient mice (CD28-/-) are completely resistant to TSST-1-induced lethal TSS while CD28 (+/-) littermate mice were partially resistant to TSST-1. The mechanism for the resistance of the CD28 (-/-) mice was a complete abrogation of TNF-alpha accumulation in the serum and a nearly complete (90%) impairment of IFN-gamma secretion in response to TSST-1 injection. In contrast, the serum level of IL-2 was only moderately influenced by the variation of CD28 expression. CD28 (-/-) mice retained sensitivity to TNF-alpha as demonstrated by equivalent lethality after cytokine injection. These findings establish an essential requirement for CD28 costimulatory signals in TSST-1-induced TSS. The hierarchy of TSST-1 resistance among CD28 wild-type (CD28+/+), CD28 heterozygous (CD28+/-), and CD28-/- mice suggests a gene-dose effect, implying that the levels of T cell surface CD28 expression critically regulate superantigen-mediated costimulation. Finally, as these results demonstrate the primary and non-redundant role of CD28 receptors in the initiation of the in vivo cytokine cascade, they suggest therapeutic approaches for superantigen-mediated immunopathology.
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Chen, Zhuo. "Signal Recognition for English Speech Translation Based on Improved Wavelet Denoising Method". Advances in Mathematical Physics 2021 (18 de septiembre de 2021): 1–9. http://dx.doi.org/10.1155/2021/6811192.
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The signal corresponding to English speech contains a lot of redundant information and environmental interference information, which will produce a lot of distortion in the process of English speech translation signal recognition. Based on this, a large number of studies focus on encoding and processing English speech, so as to achieve high-precision speech recognition. The traditional wavelet denoising algorithm plays an obvious role in the recognition of English speech translation signals, which mainly depends on the excellent local time-frequency domain characteristics of the wavelet signal algorithm, but the traditional wavelet signal algorithm is still difficult to select the recognition threshold, and the recognition accuracy is easy to be affected. Based on this, this paper will improve the traditional wavelet denoising algorithm, abandon the single-threshold judgment of the original traditional algorithm, innovatively adopt the combination of soft threshold and hard threshold, further solve the distortion problem of the denoising algorithm in the process of English speech translation signal recognition, improve the signal-to-noise ratio of English speech recognition, and further reduce the root mean square error of the signal. Good noise reduction effect is realized, and the accuracy of speech recognition is improved. In the experiment, the algorithm is compared with the traditional algorithm based on MATLAB simulation software. The simulation results are consistent with the actual theoretical results. At the same time, the algorithm proposed in this paper has obvious advantages in the recognition accuracy of English speech translation signals, which reflects the superiority and practical value of the algorithm.
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Ma, Lihua, Guoxiang Ai y Ting Kong. "Physical Augmentation Factor of Precision in Gnss". Artificial Satellites 57, n.º 3 (1 de septiembre de 2022): 185–93. http://dx.doi.org/10.2478/arsa-2022-0009.
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Abstract The dilution of precision (DOP) in satellite navigation system provides a simple characterization of the user–satellite geometry and a quantitative assessment of the positioning constellation configuration. The essential idea of physical augmentation factor of precision (PAFP) proposed in this work, is that navigation signals are transmitted at multiple frequencies from each visible satellite in the positioning constellation, while users measure the corresponding multiple pseudoranges of satellites to achieve high precision code positioning. As the multiple pseudoranges of one satellite are measured independently by the corresponding navigation signals at different frequencies, it is reasonable to treat the measurement errors due to the satellite clock and ephemeris, the atmospheric propagation as uncorrelated, random, and identically distributed. The multipath effects and receiver noise are also processed with some empirical models. By measuring user–satellite code pseudoranges at different frequencies, the PAFP offers a scheme that produces the same effect as that of the redundant-overlapping constellation, thus equivalently improving the geometric DOP. It can effectively improve code positioning precision of satellite navigation system.
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Foroozand, Hossein y Steven V. Weijs. "Objective functions for information-theoretical monitoring network design: what is “optimal”?" Hydrology and Earth System Sciences 25, n.º 2 (19 de febrero de 2021): 831–50. http://dx.doi.org/10.5194/hess-25-831-2021.
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Abstract. This paper concerns the problem of optimal monitoring network layout using information-theoretical methods. Numerous different objectives based on information measures have been proposed in recent literature, often focusing simultaneously on maximum information and minimum dependence between the chosen locations for data collection stations. We discuss these objective functions and conclude that a single-objective optimization of joint entropy suffices to maximize the collection of information for a given number of stations. We argue that the widespread notion of minimizing redundancy, or dependence between monitored signals, as a secondary objective is not desirable and has no intrinsic justification. The negative effect of redundancy on total collected information is already accounted for in joint entropy, which measures total information net of any redundancies. In fact, for two networks of equal joint entropy, the one with a higher amount of redundant information should be preferred for reasons of robustness against failure. In attaining the maximum joint entropy objective, we investigate exhaustive optimization, a more computationally tractable greedy approach that adds one station at a time, and we introduce the “greedy drop” approach, where the full set of stations is reduced one at a time. We show that no greedy approach can exist that is guaranteed to reach the global optimum.
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Swinkels, Lieke M. J., Harm Veling y Hein T. van Schie. "The Redundant Signals Effect and the Full Body Illusion: not Multisensory, but Unisensory Tactile Stimuli Are Affected by the Illusion". Multisensory Research 34, n.º 6 (9 de abril de 2021): 553–85. http://dx.doi.org/10.1163/22134808-bja10046.
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Abstract During a full body illusion (FBI), participants experience a change in self-location towards a body that they see in front of them from a third-person perspective and experience touch to originate from this body. Multisensory integration is thought to underlie this illusion. In the present study we tested the redundant signals effect (RSE) as a new objective measure of the illusion that was designed to directly tap into the multisensory integration underlying the illusion. The illusion was induced by an experimenter who stroked and tapped the participant’s shoulder and underarm, while participants perceived the touch on the virtual body in front of them via a head-mounted display. Participants performed a speeded detection task, responding to visual stimuli on the virtual body, to tactile stimuli on the real body and to combined (multisensory) visual and tactile stimuli. Analysis of the RSE with a race model inequality test indicated that multisensory integration took place in both the synchronous and the asynchronous condition. This surprising finding suggests that simultaneous bodily stimuli from different (visual and tactile) modalities will be transiently integrated into a multisensory representation even when no illusion is induced. Furthermore, this finding suggests that the RSE is not a suitable objective measure of body illusions. Interestingly however, responses to the unisensory tactile stimuli in the speeded detection task were found to be slower and had a larger variance in the asynchronous condition than in the synchronous condition. The implications of this finding for the literature on body representations are discussed.
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Zhao, Le Fa, Shahin Siahpour, Mohammad Reza Haeri Yazdi, Moosa Ayati y Tian Yu Zhao. "Intelligent Monitoring System Based on Noise-Assisted Multivariate Empirical Mode Decomposition Feature Extraction and Neural Networks". Computational Intelligence and Neuroscience 2022 (25 de abril de 2022): 1–14. http://dx.doi.org/10.1155/2022/2698498.
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Because of the nonlinearity and nonstationarity in the vibration signals of some rotating machinery, the analysis of these signals using conventional time- or frequency-domain methods has some drawbacks, and the results can be misleading. In this paper, a couple of features derived from multivariate empirical mode decomposition (MEMD) are introduced, which overcomes the shortcomings of the traditional features. A wind turbine gearbox and its bearings are investigated as rotating machinery. In this method, two types of feature structures are extracted from the decomposed signals resulting from the MEMD algorithm, called intrinsic mode function (IMF). The first type of feature vector element is the energy moment of effective IMFs. The other type of vector elements is amplitudes of a signal spectrum at the characteristic frequencies. A correlation factor is used to detect effective IMFs and eliminate the redundant IMFs. Since the basic MEMD algorithm is sensitive to noise, a noise-assisted extension of MEMD, NA-MEMD, is exploited to reduce the effect of noise on the output results. The capability of the proposed feature vector in health condition monitoring of the system is evaluated and compared with traditional features by using a discrimination factor. The proposed feature vector is utilized in the input layer of the classical three-layer backpropagation neural network. The results confirm that these features are appropriate for intelligent fault detection of complex rotating machinery and can diagnose the occurrence of early faults.
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Zhao, Le Fa, Shahin Siahpour, Mohammad Reza Haeri Yazdi, Moosa Ayati y Tian Yu Zhao. "Intelligent Monitoring System Based on Noise-Assisted Multivariate Empirical Mode Decomposition Feature Extraction and Neural Networks". Computational Intelligence and Neuroscience 2022 (25 de abril de 2022): 1–14. http://dx.doi.org/10.1155/2022/2698498.
Texto completoResumen
Because of the nonlinearity and nonstationarity in the vibration signals of some rotating machinery, the analysis of these signals using conventional time- or frequency-domain methods has some drawbacks, and the results can be misleading. In this paper, a couple of features derived from multivariate empirical mode decomposition (MEMD) are introduced, which overcomes the shortcomings of the traditional features. A wind turbine gearbox and its bearings are investigated as rotating machinery. In this method, two types of feature structures are extracted from the decomposed signals resulting from the MEMD algorithm, called intrinsic mode function (IMF). The first type of feature vector element is the energy moment of effective IMFs. The other type of vector elements is amplitudes of a signal spectrum at the characteristic frequencies. A correlation factor is used to detect effective IMFs and eliminate the redundant IMFs. Since the basic MEMD algorithm is sensitive to noise, a noise-assisted extension of MEMD, NA-MEMD, is exploited to reduce the effect of noise on the output results. The capability of the proposed feature vector in health condition monitoring of the system is evaluated and compared with traditional features by using a discrimination factor. The proposed feature vector is utilized in the input layer of the classical three-layer backpropagation neural network. The results confirm that these features are appropriate for intelligent fault detection of complex rotating machinery and can diagnose the occurrence of early faults.
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Strelnikov, Kuzma, Mario Hervault, Lidwine Laurent y Pascal Barone. "When two is worse than one: The deleterious impact of multisensory stimulation on response inhibition". PLOS ONE 16, n.º 5 (20 de mayo de 2021): e0251739. http://dx.doi.org/10.1371/journal.pone.0251739.
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Multisensory facilitation is known to improve the perceptual performances and reaction times of participants in a wide range of tasks, from detection and discrimination to memorization. We asked whether a multimodal signal can similarly improve action inhibition using the stop–signal paradigm. Indeed, consistent with a crossmodal redundant signal effect that relies on multisensory neuronal integration, the threshold for initiating behavioral responses is known for being reached faster with multisensory stimuli. To evaluate whether this phenomenon also occurs for inhibition, we compared stop signals in unimodal (human faces or voices) versus audiovisual modalities in natural or degraded conditions. In contrast to the expected multisensory facilitation, we observed poorer inhibition efficiency in the audiovisual modality compared with the visual and auditory modalities. This result was corroborated by both response probabilities and stop–signal reaction times. The visual modality (faces) was the most effective. This is the first demonstration of an audiovisual impairment in the domain of perception and action. It suggests that when individuals are engaged in a high–level decisional conflict, bimodal stimulation is not processed as a simple multisensory object improving the performance but is perceived as concurrent visual and auditory information. This absence of unity increases task demand and thus impairs the ability to revise the response.
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Ding, Jian-Hua, Xiang-Yang Zhong, Jonathan C. Hagopian, Marissa M. Cruz, Gourisankar Ghosh, James Feramisco, Joseph A. Adams y Xiang-Dong Fu. "Regulated Cellular Partitioning of SR Protein-specific Kinases in Mammalian Cells". Molecular Biology of the Cell 17, n.º 2 (febrero de 2006): 876–85. http://dx.doi.org/10.1091/mbc.e05-10-0963.
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Reversible phosphorylation of the SR family of splicing factors plays an important role in pre-mRNA processing in the nucleus. Interestingly, the SRPK family of kinases specific for SR proteins is localized in the cytoplasm, which is critical for nuclear import of SR proteins in a phosphorylation-dependent manner. Here, we report molecular dissection of the mechanism involved in partitioning SRPKs in the cytoplasm. Common among all SRPKs, the bipartite kinase catalytic core is separated by a unique spacer sequence. The spacers in mammalian SRPK1 and SRPK2 share little sequence homology, but they function interchangeably in restricting the kinases in the cytoplasm. Removal of the spacer in SRPK1 had little effect on the kinase activity, but it caused a quantitative translocation of the kinase to the nucleus and consequently induced aggregation of splicing factors in the nucleus. Rather than carrying a nuclear export signal as suggested previously, we found multiple redundant signals in the spacer that act together to anchor the kinase in the cytoplasm. Interestingly, a cell cycle signal induced nuclear translocation of the kinase at the G2/M boundary. These findings suggest that SRPKs may play an important role in linking signaling to RNA metabolism in higher eukaryotic cells.
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Kim, Honggeun, Bang D. Nhan, Jacqueline N. Hewitt, Nicholas S. Kern, Joshua S. Dillon, Eloy de Lera Acedo, Scott B. C. Dynes, Nivedita Mahesh, Nicolas Fagnoni y David R. DeBoer. "The Impact of Beam Variations on Power Spectrum Estimation for 21 cm Cosmology. I. Simulations of Foreground Contamination for HERA". Astrophysical Journal 941, n.º 2 (1 de diciembre de 2022): 207. http://dx.doi.org/10.3847/1538-4357/ac9eaf.
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Abstract Detecting cosmological signals from the Epoch of Reionization (EoR) requires high-precision calibration to isolate the cosmological signals from foreground emission. In radio interferometry, the perturbed primary beams of antenna elements can disrupt the precise calibration, which results in the contamination of the foreground-free region, or the EoR window, in the cylindrically averaged power spectrum. For the Hydrogen Epoch of Reionization Array (HERA), we simulate and characterize the perturbed primary beams that are induced by feed motions, such as axial, lateral, and tilting motions, above the 14 m dish. To understand the effect of the perturbed beams, visibility measurements are modeled with two different foreground components, point sources and diffuse sources, and we find that different feed motions present a different reaction to each type of sky source. HERA’s redundant baseline calibration in the presence of nonredundant antenna beams due to feed motions introduces chromatic errors in the gain solutions, producing foreground power leakage into the EoR window. The observed leakage from the vertical feed motions comes predominantly from point sources around the zenith. Furthermore, the observed leakage from the horizontal and tilting feed motions comes predominantly from the diffuse components near the horizon. Mitigation of the chromatic gain errors will be necessary for robust detections of the EoR signals with minimal foreground bias, and this will be discussed in a subsequent paper.
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Lee, Se-Jin, Adam Lehar, Yewei Liu, Chi Hai Ly, Quynh-Mai Pham, Michael Michaud, Renata Rydzik et al. "Functional redundancy of type I and type II receptors in the regulation of skeletal muscle growth by myostatin and activin A". Proceedings of the National Academy of Sciences 117, n.º 49 (20 de noviembre de 2020): 30907–17. http://dx.doi.org/10.1073/pnas.2019263117.
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Myostatin (MSTN) is a transforming growth factor-β (TGF-β) family member that normally acts to limit muscle growth. The function of MSTN is partially redundant with that of another TGF-β family member, activin A. MSTN and activin A are capable of signaling through a complex of type II and type I receptors. Here, we investigated the roles of two type II receptors (ACVR2 and ACVR2B) and two type I receptors (ALK4 and ALK5) in the regulation of muscle mass by these ligands by genetically targeting these receptors either alone or in combination specifically in myofibers in mice. We show that targeting signaling in myofibers is sufficient to cause significant increases in muscle mass, showing that myofibers are the direct target for signaling by these ligands in the regulation of muscle growth. Moreover, we show that there is functional redundancy between the two type II receptors as well as between the two type I receptors and that all four type II/type I receptor combinations are utilized in vivo. Targeting signaling specifically in myofibers also led to reductions in overall body fat content and improved glucose metabolism in mice fed either regular chow or a high-fat diet, demonstrating that these metabolic effects are the result of enhanced muscling. We observed no effect, however, on either bone density or muscle regeneration in mice in which signaling was targeted in myofibers. The latter finding implies that MSTN likely signals to other cells, such as satellite cells, in addition to myofibers to regulate muscle homeostasis.
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Evans, Christopher S. y Linda Evans. "Representational signalling in birds". Biology Letters 3, n.º 1 (14 de noviembre de 2006): 8–11. http://dx.doi.org/10.1098/rsbl.2006.0561.
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Some animals give specific calls when they discover food or detect a particular type of predator. Companions respond with food-searching behaviour or by adopting appropriate escape responses. These signals thus seem to denote objects in the environment, but this specific mechanism has only been demonstrated for monkey alarm calls. We manipulated whether fowl ( Gallus gallus ) had recently found a small quantity of preferred food and then tested for a specific interaction between this event and their subsequent response to playback of food calls. In one treatment, food calls thus potentially provided information about the immediate environment, while in the other the putative message was redundant with individual experience. Food calls evoked substrate searching, but only if the hens had not recently discovered food. An identical manipulation had no effect on responses to an acoustically matched control call. These results show that chicken food calls are representational signals: they stimulate retrieval of information about a class of external events. This is the first such demonstration for any non-primate species. Representational signalling is hence more taxonomically widespread than has previously been thought, suggesting that it may be the product of common social factors, rather than an attribute of a particular phylogenetic lineage.
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Kelly, Lisa, Silvia Morales, Brenda K. Smith y Hans-Rudolf Berthoud. "Capsaicin-treated rats permanently overingest low- but not high-concentration sucrose solutions". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 279, n.º 5 (1 de noviembre de 2000): R1805—R1812. http://dx.doi.org/10.1152/ajpregu.2000.279.5.r1805.
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The effect of capsaicin-induced chemical ablation of visceral afferents on 1-h liquid sucrose consumption was investigated in food-deprived rats. We first show that although 10% sucrose is permanently overconsumed by capsaicin-treated (CAPs) compared with vehicle-treated (VEHs) control rats, 40% sucrose is only overconsumed during the first but not subsequent 1-h exposures. Furthermore, one group of CAPs lost the overconsumption response at 20% when exposed to progressively increasing sucrose concentrations of 10–40%, and another group recovered the overconsumption response at 10% when exposed to a series of decreasing concentrations. Control rats ingested relatively constant volumes of sucrose over the range of 10, 15, and 20%, resulting in significantly different energy intakes. In contrast, CAPs generally showed a concentration-dependent decrease in volume intake, resulting in relatively constant energy intake. These results suggest that capsaicin-sensitive visceral afferents, likely from gastric distension and other preabsorptive sensors, provide major control over volume ingested. In the absence of these signals, rats initially overconsume, but rapidly learn to use other signals from capsaicin-resistant preabsorptive or postabsorptive sites, to control future intake. This redundant satiety system appears to be sensitive to the osmotic value or caloric content of the unfamiliar food, but only if this is above a threshold of about 15% sucrose.
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Vicente, Natalin S. "Headbob displays signal sex, social context and species identity in a Liolaemus lizard". Amphibia-Reptilia 39, n.º 2 (2018): 203–18. http://dx.doi.org/10.1163/15685381-17000163.
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Abstract Animal communication has a key role in animals and identifying the signals’ function is crucial. Most lizards communicate with each other through visual signals with headbob displays, which are up-and-down movements of the head or the anterior part of the body. In the present work, I described and analysed the headbob displays of Liolaemus pacha lizards in their natural habitat. Specifically, the objectives were to describe the form of headbobs, to analyse their structure and to compare between sexes and social contexts. Adult lizards were video-recorded, registering the sex and the social context, classified as broadcast, same-sex and female-male interactions. The form and structure of sequences and headbobs were obtained. To evaluate the effect of sex and social context on the structure of headbob sequences and on headbob bouts, generalized linear mixed models were made. Intersexual differences were found in headbob display frequency and in the structure of headbob sequences. Lizards in same-sex context made sequences with more bouts, shorter intervals, headbob bouts of longer duration and higher amplitude than broadcast and female-male context. Presence of concurring behaviour such as lateral compression, gular expansion, and back arching occurred simultaneously with headbobs in same-sex context. Liolaemus pacha made four different headbob bout forms, and males were characterised by using bouts A and B, whereas females used bouts D more frequent. Sex and social context influenced only the structure of bouts A and B. The results showed that bouts A and B might be multi-component signals and non-redundant.
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Ur Rehman, Naveed, Lei Zhang, Muhammad Zahid Hammad y Emmanuel Anania Mwangosi. "ICI Cancellation in OFDM Systems by Frequency Offset Reduction". Applied Mechanics and Materials 513-517 (febrero de 2014): 3987–91. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.3987.
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The rapid growth within the field of digital communication during the recent years expanded the need for high-speed data transmission to support a wide range of services such as: video, data and voice in wireless communication systems, etc. Orthogonal frequency division multiplexing (OFDM) and a multicarrier modulation scheme are employed to achieve the high data rates. Since OFDM is very much sensitive to carrier frequency offsets, which cause the Inter-carrier Interference (ICI) leads to mitigation of this ICI is necessary. The objectives of this paper are to, proposed an efficient ICI self-cancellation scheme to mitigate the effect of ICI on OFDM systems. For this purpose, a redundant data is transmitted onto adjacent sub-carriers such that the ICI between adjacent sub-carriers cancels out at the receiver side. One data symbol is modulated into a group of adjacent sub carriers with a group of weighting coefficients. At the receiver side, the received signals are linearly combined on these sub carriers with proposed coefficients. The residual ICI contained in the received signals can then be further reduced. This study provides significant carrier-to-interference power ratio (CIR) improvement, which has been studied theoretically and supported by simulations. Since no channel equalization is required to reduce ICI, so the proposed scheme doesnt increase the system complexity.
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Hodge, Paul D. y Nigel D. Stow. "Effects of Mutations within the Herpes Simplex Virus Type 1 DNA Encapsidation Signal on Packaging Efficiency". Journal of Virology 75, n.º 19 (1 de octubre de 2001): 8977–86. http://dx.doi.org/10.1128/jvi.75.19.8977-8986.2001.
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ABSTRACT The cis-acting signals required for cleavage and encapsidation of the herpes simplex virus type 1 genome lie within the terminally redundant region or a sequence. Thea sequence is flanked by short direct repeats (DR1) containing the site of cleavage, and quasi-unique regions, Uc and Ub, occupy positions adjacent to the genomic L and S termini, respectively, such that a novel fragment, Uc-DR1-Ub, is generated upon ligation of the genomic ends. The Uc-DR1-Ub fragment can function as a minimal packaging signal, and motifs have been identified within Uc and Ub that are conserved near the ends of other herpesvirus genomes (pac2 and pac1, respectively). We have introduced deletion and substitution mutations within thepac regions of the Uc-DR1-Ub fragment and assessed their effects on DNA packaging in an amplicon-based transient transfection assay. Within pac2, mutations affecting the T tract had the greatest inhibitory effect, but deletion of sequences on either side of this element also reduced packaging, suggesting that its position relative to other sequences within the Uc-DR1-Ub fragment is likely to be important. No single region essential for DNA packaging was detected within pac1. However, mutants lacking the G tracts on either side of the pac1 T-rich motif exhibited a reduced efficiency of serial propagation, and alteration of the sequences between DR1 and the pac1 T element also resulted in defective generation of Ub-containing terminal fragments. The data are consistent with a model in which initiation and termination of packaging are specified by sequences within Uc and Ub, respectively.
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Laughlin, S. B. "The role of sensory adaptation in the retina". Journal of Experimental Biology 146, n.º 1 (1 de septiembre de 1989): 39–62. http://dx.doi.org/10.1242/jeb.146.1.39.
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Adaptation, a change in response to a sustained stimulus, is a widespread property of sensory systems, occurring at many stages, from the most peripheral energy-gathering structures to neural networks. Adaptation is also implemented at many levels of biological organization, from the molecule to the organ. Despite adaptation's diversity, it is fruitful to extract some unifying principles by considering well-characterized components of the insect visual system. A major function of adaptation is to increase the amount of sensory information an organism uses. The amount of information available to an organism is ultimately defined by its environment and its size. The amount of information collected depends upon the ways in which an organism samples and transduces signals. The amount of information that is used is further limited by internal losses during transmission and processing. Adaptation can increase information capture and reduce internal losses by minimizing the effects of physical and biophysical constraints. Optical adaptation mechanisms in compound eyes illustrate a common trade-off between energy (quantum catch) and acuity (sensitivity to changes in the distribution of energy). This trade-off can be carefully regulated to maximize the information gathered (i.e. the number of pictures an eye can reconstruct). Similar trade-offs can be performed neurally by area summation mechanisms. Light adaptation in photoreceptors introduces the roles played by cellular constraints in limiting the available information. Adaptation mechanisms prevent saturation and, by trading gain for temporal acuity, increase the rate of information uptake. By minimizing the constraint of nonlinear summation (imposed by membrane conductance mechanisms) a cell's sensitivity follows the Weber-Fechner law. Thus, a computationally advantageous transformation is generated in response to a cellular constraint. The synaptic transfer of signals from photoreceptors to second-order neurones emphasizes that the cellular constraints of nonlinearity, noise and dynamic range limit the transmission of information from cell to cell. Synaptic amplification is increased to reduce the effects of noise but this resurrects the constraint of dynamic range. Adaptation mechanisms, both confined to single synapses and distributed in networks, remove spatially and temporally redundant signal components to help accommodate more information within a single cell. The net effect is a computationally advantageous removal of the background signal. Again, the cellular constraints on information transfer have dictated a computationally advantageous operation.
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Brassarote, Gabriela De Oliveira Nascimento, Eniuce Menezes de Souza y João Francisco Galera Monico. "Multiscale Analysis of GPS Time Series from Non-decimated Wavelet to Investigate the Effects of Ionospheric Scintillation". TEMA (São Carlos) 16, n.º 2 (7 de septiembre de 2015): 119. http://dx.doi.org/10.5540/tema.2015.016.02.0119.
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Due to the numerous application possibilities, the theory of wavelets has been applied in several areas of research. The Discrete Wavelet Transform is the most known version. However, the downsampling required for its calculation makes it sensitive to the origin, what is not ideal for some applications,mainly in time series. On the other hand, the Non-Decimated Discrete Wavelet Transform (or Maximum Overlap Discrete Wavelet Transform, Stationary Wavelet Transform, Shift-invariant Discrete Wavelet Transform, Redundant Discrete Wavelet Transform) is shift invariant, because it considers all the elements of the sample, by eliminating the downsampling and, consequently, represents a time series with the same number of coefficients at each scale. In the present paper, the objective is to present the theorical aspects of the a multiscale/multiresolution analysis of non-stationary time series from non-decimated wavelets in terms of its implementation using the same pyramidal algorithm of the decimated wavelet transform. An application with real time series of the effect of the ionospheric scintillation on artificial satellite signals is investigated. With this analysis some information and hidden patterns which can not be detected in the time domain, may therefore be explained in the space-frequency domain.