Sampling Paradigm Research Articles

Ultra-Low Power Dynamic Knob in Adaptive Compressed Sensing Towards Biosignal Dynamics.

Compressed sensing (CS) is an emerging sampling paradigm in data acquisition. Its integrated analog-to-information structure can perform simultaneous data sensing and compression with low-complexity hardware. To date, most of the existing CS implementations have a fixed architectural setup, which lacks flexibility and adaptivity for efficient dynamic data sensing. In this paper, we propose a dynamic knob (DK) design to effectively reconfigure the CS architecture by recognizing the biosignals. Specifically, the dynamic knob design is a template-based structure that comprises a supervised learning module and a look-up table module. We model the DK performance in a closed analytic form and optimize the design via a dynamic programming formulation. We present the design on a 130 nm process, with a 0.058 mm (2) fingerprint and a 187.88 nJ/event energy-consumption. Furthermore, we benchmark the design performance using a publicly available dataset. Given the energy constraint in wireless sensing, the adaptive CS architecture can consistently improve the signal reconstruction quality by more than 70%, compared with the traditional CS. The experimental results indicate that the ultra-low power dynamic knob can provide an effective adaptivity and improve the signal quality in compressed sensing towards biosignal dynamics.

Description-experience gap in choice deferral.

Facing a large set of alternatives has previously been reported to lead to choice overload, including choice deferral. Recent studies, however, imply that choice deferral is more tightly associated with the difficulty in evaluating alternatives than with set size: when alternatives are difficult to evaluate, people often defer a choice. This implication is examined in the present study, using alternatives with probabilistic payoffs in 2 paradigms: the description paradigm—with full probability and payoff information provided at 1 time—and the sampling paradigm—with search revealing 1 payoff at a time and repeated search required to derive probabilities and payoffs. The results show that in both paradigms, choice deferral is less frequent when set size is large. Also, the difficulty in evaluating alternatives influences choice deferral in the description paradigm but not in the sampling paradigm: when a payoff from an alternative can take many possible values, a choice is more likely deferred in the description paradigm. In the sampling paradigm, in contrast, information search is often insufficient for people to recognize the difficulty in evaluating alternatives. These results point to a description-experience gap in choice deferral.

Precision and cost considerations for two-stage sampling in a panelized forest inventory design

Due to the relatively high cost of measuring sample plots in forest inventories, considerable attention is given to sampling and plot designs during the forest inventory planning phase. A two-stage design can be efficient from a field work perspective as spatially proximate plots are grouped into work zones. A comparison between subsampling with units of unequal size (SUUS) and a simple random sample (SRS) design in a panelized framework assessed the statistical and economic implications of using the SUUS design for a case study in the Northeastern USA. The sampling errors for estimates of forest land area and biomass were approximately 1.5-2.2 times larger with SUUS prior to completion of the inventory cycle. Considerable sampling error reductions were realized by using the zones within a post-stratified sampling paradigm; however, post-stratification of plots in the SRS design always provided smaller sampling errors in comparison. Cost differences between the two designs indicated the SUUS design could reduce the field work expense by 2-7 %. The results also suggest the SUUS design may provide substantial economic advantage for tropical forest inventories, where remote areas, poor access, and lower wages are typically encountered.

Scientific Surveys Based on Incomplete Sampling Frames and High Rates of Nonresponse

Traditional methods of survey research that rely on Neyman’s probability-based sampling paradigm are grounded in a number of fundamental assumptions that are becoming exceedingly difficult to attain in today’s survey research environment. On the one hand, common methods of sampling are subject to coverage issues that may not be fully ameliorated through post-survey weighting adjustments. On the other, response rates continue to deteriorate for all surveys, even when resource-intensive refusal conversion strategies are employed. Add in the growing need for cost containments and it is no wonder why alternative sampling methods are gaining popularity. The authors will review a number of practices that are currently used for developing inferences from samples that do not fully adhere to the statistical machinery that is currently available for probability-based sample surveys. Moreover, a robust weighting methodology will be introduced that can reduce the inherent biases associated with non-probability samples, as well as probability-based sample surveys that suffer from incomplete frames and high rates of nonresponse. The efficacy of the proposed methodology is assessed in light of comparisons of survey estimates to external benchmarks, relying on parallel surveys that were conducted in two states using both probability-based and non-probability samples.

Mind Wandering and the Incubation Effect in Insight Problem Solving

Although many anecdotes suggest that creative insights often arise during mind wandering, empirical research is still sparse. In this study, the number reduction task (NRT) was used to assess whether insightful solutions were related to mind wandering during the incubation stage of the creative process. An experience sampling paradigm was used to provide an online measure of mind wandering while participants performed a sustained attention response task (SART). Participants were 91 Chinese college students. The results showed that participants who gained insights of the hidden regularity in the NRT (or the solvers) reported significantly more mind wandering during incubation than those who did not gain insights (or the non-solvers). Moreover, the solvers also rated themselves higher in overall creativity on the Exercise in Divergent Feeling (Williams, 1979) than did the nonsolvers. The two groups, however, did not differ in other characteristics, such as working memory capacity and motivation. These results suggest that mind wandering may play an important role in solving insight problems.

A normative inference approach for optimal sample sizes in decisions from experience.

“Decisions from experience” (DFE) refers to a body of work that emerged in research on behavioral decision making over the last decade. One of the major experimental paradigms employed to study experience-based choice is the “sampling paradigm,” which serves as a model of decision making under limited knowledge about the statistical structure of the world. In this paradigm respondents are presented with two payoff distributions, which, in contrast to standard approaches in behavioral economics, are specified not in terms of explicit outcome-probability information, but by the opportunity to sample outcomes from each distribution without economic consequences. Participants are encouraged to explore the distributions until they feel confident enough to decide from which they would prefer to draw from in a final trial involving real monetary payoffs. One commonly employed measure to characterize the behavior of participants in the sampling paradigm is the sample size, that is, the number of outcome draws which participants choose to obtain from each distribution prior to terminating sampling. A natural question that arises in this context concerns the “optimal” sample size, which could be used as a normative benchmark to evaluate human sampling behavior in DFE. In this theoretical study, we relate the DFE sampling paradigm to the classical statistical decision theoretic literature and, under a probabilistic inference assumption, evaluate optimal sample sizes for DFE. In our treatment we go beyond analytically established results by showing how the classical statistical decision theoretic framework can be used to derive optimal sample sizes under arbitrary, but numerically evaluable, constraints. Finally, we critically evaluate the value of deriving optimal sample sizes under this framework as testable predictions for the experimental study of sampling behavior in DFE.

Abstract 3967: miRNA reference samples for interlaboratory study

Abstract The biomarkers of interest in this study are microRNA (miRNA), small non-coding RNAs involved in the regulation of gene expression. Currently, over 1000 human miRNAs have been identified. Several laboratories within the Early Detection Research Network are currently profiling miRNA as potential biomarkers. The reference sample paradigm presented and evaluated here is designed to provide measurement assurance in the earliest phases of a cancer biomarker development pipeline. Three commercially available samples of human total RNA (brain, liver, and placenta) were selected for detectable differences in miRNA expression based upon previously reported miRNA microarray experiments. For each round of this study, replicate samples of each tissue were aliquoted, blinded, and distributed to participating laboratories. The samples were then profiled using the standard workflows of each laboratory. This was repeated over multiple rounds of measurement. Raw data were processed in pair-wise comparisons between tissue types. Log2 transformed ratios were calculated for each detectable miRNA. For each of these miRNA ratios, the results among laboratories were compared to the consensus value to provide a measure of concordance and help identify laboratories that might need to make adjustments to their process. Results demonstrated repeatability within labs and reproducibility among labs with respect to direction and magnitude of differential miRNA expression between tissues for a set of miRNAs of interest (MOI). For the first round, 79% of reported results for all log2 ratio combinations and MOI were in agreement with the consensus values. Subsequent rounds demonstrated increased concordance, with 91 and 100% agreement, respectively. The data from the nine “neat” tissue total RNA samples were also used for in silico modeling to predict the values for two complex mixtures based on three components. The two mixture designs provide a pair of reference samples with designed-in reciprocal ratios of 2:1 for brain and placenta, as well as a shared 1:1 liver component. For two brain-selective and two placenta-selective MOI, 91% of reported values were in close agreement with the target values. Overall, measurement results were harmonious for a set of miRNAs of interest measured by all participants, both within rounds and between rounds. The laboratories were also able to demonstrate the ability to resolve the 2-fold differences created with complex mixtures. These results suggest that endogenous miRNAs present within total RNA may be suitable as QA/QC process controls. Citation Format: P. Scott Pine, Lynn R. Sorbara, Sudhir Srivastava, Marc Salit. miRNA reference samples for interlaboratory study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3967. doi:10.1158/1538-7445.AM2015-3967

How short- and long-run aspirations impact search and choice in decisions from experience

To what extent do people adapt their information search policies and subsequent decisions to the long- and short-run consequences of choice environments? To address this question, we investigated exploration and exploitation policies in choice environments that involved single or multiple plays. We further compared behavior in these environments with behavior in the standard sampling paradigm. Frequently used in research on decision from experience, this paradigm does not explicitly implement the choice in terms of the short or long run. Results showed that people searched more in the multi-play environment than in the single-play environment. Moreover, the substantial search effort in the multi-play environment was conducive to choices consistent with expected value maximization, whereas the lesser search effort in the single-play environment was compatible with the goal of maximizing the chance of winning something. Furthermore, choice and search behaviors in the sampling paradigm predominantly echoed those observed in the single-play environment. This suggests that, when not instructed otherwise, participants in the sampling paradigm appear to favor search and choice strategies that embody short-run aspirations. Finally, the present findings challenge the revealed preference approach in decisions from experience, while also suggesting that information search may be an important and potentially even better signal of preference or aspirations than choice.

Experience‐Based Decisions Favor Riskier Alternatives in Large Sets

AbstractResearch on risky choice has been predominantly based on studies of choices between two alternatives, but their findings are often generalized to environments with more than two alternatives. One prominent claim of this research is that choices differ with respect to risk when alternatives are described (the description paradigm) as opposed to sampled (the sampling paradigm). Here, we demonstrate that the difference in choices is sensitive to the number of alternatives in a choice set: with a growth in set size, alternatives with rare payoffs become more likely to be chosen in the sampling paradigm. This increased risk‐taking is due to the statistical property of payoffs: with a growth in set size, at least one riskier alternative becomes much more likely to deliver an attractive sample payoff at a higher frequency than its underlying probability. The increased risk‐taking eventually diminishes the difference between the description and the sampling paradigms in the gain domain. Further, we show that the increase in risk‐taking is difficult to avoid, even if each alternative is thoroughly sampled. Copyright © 2015 John Wiley & Sons, Ltd.

The role of cognitive abilities in decisions from experience: Age differences emerge as a function of choice set size

People seldom enjoy access to summarized information about risky options before making a decision. Instead, they may search for information and learn about environmental contingencies—thus making decisions from experience. Aging is associated with notable deficits in learning and memory—but do these translate into poorer decisions from experience? We report three studies that used a sampling paradigm to investigate younger (M=24years) and older (M=71years) adults’ decisions from experience. In Study 1 (N=121) participants made 12 decisions between pairs of payoff distributions in the lab. Study 2 (N=70) implemented the same paradigm using portable devices, collecting 84 decisions per individual over a week. Study 3 (N=84) extended the sampling paradigm by asking participants to make 12 decisions between two, four, and eight payoff distributions (in the lab). Overall, the behavioral results suggest that younger and older adults are relatively similar in how they search and what they choose when facing two payoff distributions (Studies 1 and 2). With an increasing number of payoff distributions, however, age differences emerged (Study 3). A modeling analysis on the level of individual participants showed that a simple delta-learning rule model best described the learning processes of most participants. To the extent that ongoing updating processes unfold relatively automatically and effortlessly, older adults may be liberated from the detrimental consequences of cognitive aging in the case of decisions from experience with few decision options. We discuss implications for research on decisions from experience and choice performance over the lifespan.

Abrupt motion tracking via nearest neighbor field driven stochastic sampling

Stochastic sampling based trackers have shown good performance for abrupt motion tracking so that they have gained popularity in recent years. However, conventional methods tend to use a two-stage sampling paradigm in which the search space needs to be uniformly explored with an inefficient preliminary sampling phase. In this paper, we propose a novel sampling-based method in the Bayesian filtering framework to address the problem. Within the framework, nearest neighbor field estimation is utilized to compute the importance proposal probabilities, which guide the Markov chain search towards promising regions and thus enhance the sampling efficiency; given the motion priors, a smoothing stochastic sampling Monte Carlo algorithm is proposed to approximate the posterior distribution through a smoothing weight-updating scheme. Moreover, to track the abrupt and the smooth motions simultaneously, we develop an abrupt-motion detection scheme which can discover the presence of abrupt motions during online tracking. Extensive experiments on challenging image sequences demonstrate the effectiveness and the robustness of our algorithm in handling the abrupt motions.

Neural responses to heartbeats dissociate the self as the subject and the self as the object during spontaneous thoughts

Event Abstract Back to Event Neural responses to heartbeats dissociate the self as the subject and the self as the object during spontaneous thoughts Mariana Babo-Rebelo1*, Craig Richter2 and Catherine Tallon-Baudry2 1 Laboratoire de Neurosciences Cognitives / Ecole Normale Superieure, Institut d'Etudes Cognitives, Ecole Normale Superieure, France 2 Laboratoire de Neurosciences Cognitives, Institut d'Etudes Cognitives, Ecole Normale Superieure, France The most fundamental sense of self is represented in the first-person perspective. This sense of self known as the 'I' is distinct from the 'Me', the most often studied form of self which relates to explicit reflection about oneself. Here, we propose and test the hypothesis that the neural implementation of the 'I' is rooted in bodily signal monitoring by the central nervous system. We developed a new thought sampling paradigm in which subjects evaluated how much they were thinking as the subject ('I') and as the object ('Me'). In practice, 20 subjects fixated the screen and mind-wandered until a warning stimulus occurred at random interval. Subjects would then rate the thought that was interrupted by the warning according to 4 continuous scales: self as subject, self as object, time and valence. Magnetoencephalographic data and cardiac activity were recorded simultaneously. We measured neural responses to heartbeats preceding warning onset to test whether the amplitude of neural responses to heartbeats could predict subjects' ratings on the 'I' scale. We tested the difference in heart-evoked responses between high and low scores for each scale using a cluster-based permutation t-test. We found a significant cluster for the 'I' dimension, over posterior magnetometers between 300 and 328ms after the T-peak (Monte-Carlo, p=0.024). The 'Me' dimension was associated with a significant frontal cluster, between 120 and 155ms after the T-peak (p=0.026). A General Linear Model approach is currently being developed to test to what extent activity in these clusters is specific to each dimension of the self. This would confirm that neural responses to heartbeats reference thoughts to the self and distinguish between 'I' and 'Me'. Keywords: Magnetoencephalography, Psychophysiology, self, resting state, mind-wandering, brain-body interactions Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Attention Citation: Babo-Rebelo M, Richter C and Tallon-Baudry C (2015). Neural responses to heartbeats dissociate the self as the subject and the self as the object during spontaneous thoughts. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00017 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Mrs. Mariana Babo-Rebelo, Laboratoire de Neurosciences Cognitives / Ecole Normale Superieure, Institut d'Etudes Cognitives, Ecole Normale Superieure, Paris, France, mariana.b.rebelo@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Mariana Babo-Rebelo Craig Richter Catherine Tallon-Baudry Google Mariana Babo-Rebelo Craig Richter Catherine Tallon-Baudry Google Scholar Mariana Babo-Rebelo Craig Richter Catherine Tallon-Baudry PubMed Mariana Babo-Rebelo Craig Richter Catherine Tallon-Baudry Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The Decoupled Mind: Mind-wandering Disrupts Cortical Phase-locking to Perceptual Events

The mind flows in a "stream of consciousness," which often neglects immediate sensory input in favor of focusing on intrinsic, self-generated thoughts or images. Although considerable research has documented the disruptive influences of task-unrelated thought for perceptual processing and task performance, the brain dynamics associated with these phenomena are not well understood. Here we investigate the possibility, suggested by several convergent lines of research, that task-unrelated thought is associated with a reduction in the trial-to-trial phase consistency of the oscillatory neural signal in response to perceptual input. Using an experience sampling paradigm coupled with continuous high-density electroencephalography, we observed that task-unrelated thought was associated with a reduction of the P1 ERP, replicating prior observations that mind-wandering is accompanied by a reduction of the brain-evoked response to sensory input. Time-frequency analysis of the oscillatory neural response revealed a decrease in theta-band cortical phase-locking, which peaked over parietal scalp regions. Furthermore, we observed that task-unrelated thought impacted the oscillatory mode of the brain during the initiation of a task-relevant action, such that more cortical processing was required to meet task demands. Together, these findings document that the attenuation of perceptual processing that occurs during task-unrelated thought is associated with a reduction in the temporal fidelity with which the brain responds to a stimulus and suggest that increased neural processing may be required to recouple attention to a task. More generally, these data provide novel confirmatory evidence for the mechanisms through which attentional states facilitate the neural processing of sensory input.

Effects of a Saffron Alcoholic Extract on Visual Short-Term Memory in Humans: a Psychophysical Study

The effects of an extract from saffron (Crocus sativus L.) on visual short-term memory (STM) were examined in 20 volunteers. The extract was obtained from saffron petals using 100% ethylic alcohol, concentrated by vacuum evaporation, dried, and encapsulated (30 mg per capsula). Ten participants received the extract each day for three weeks, while other 10 subjects received encapsulated placebo. Then, the contrast sensitivity of a subject was estimated; sinusoidal grating patches with different contrast levels (0 – 100%) were used (experiment 1). In experiment 2, the retention of STM was assessed in two-force choice tests, using a delayed match to sample paradigm. In experiment 3, the n-back memory test with different interstimulus intervals (up to 14 sec) was used. It was found that subjects after medication with the saffron extract demonstrated better correct memorizing of the preceding visual stimuli (from two to five). At the same time, extract medication somewhat improved retention of visual STM, but only for several intermediate interstimulus intervals, and the effect was not very remarkable. Our findings emphasize the expedience to research the effects of physiologically active dietary constituents in humans.

On Stability of Distance Measures for Event Sequences Induced by Level-Crossing Sampling

While Shannon's paradigm of sampling is based on equidistant points in time, triggered by a clock, level-crossing sampling schemes are based on the evaluation of the input signal's amplitude. Three types of level-crossing concepts are considered: a) absolute level-crossings, b) absolute level-crossings with hysteretic quantization, that ignores repeated crossings, and c) thresholding changes. The latter is also referred to as send-on-delta. Such event-driven sampling principles are encountered in asynchronous event-based data acquisition of wireless sensor networks in order to reduce the amount of data transfer and energy consumption, in event-based imaging in order to realize high-dynamic range image acquisition or in biology in terms of neuronal spike trains. The paper addresses the similarity between the event sequences which encode the quantized signals resulting from such event-based sampling concepts. It is shown that such event-driven sampling principles induce instability effects when using dissimilarity measures which are state-of-the-art in this context. As an alternative metric, Hermann Weyl's discrepancy norm is introduced, by which such instability effects can be avoided.

ALTERED TRANSFER OF MOMENTARY MENTAL STATES (ATOMS) AS THE BASIC UNIT OF PSYCHOSIS LIABILITY IN INTERACTION WITH ENVIRONMENT AND EMOTIONS

Psychotic disorders are thought to represent altered neural function. However, research has failed to map diagnostic categories to alterations in neural networks. It is proposed that the basic unit of psychotic psychopathology is the momentto-moment expression of subtle anomalous experiences of subclinical psychosis, and particularly its tendency to persist from moment-to-moment in daily life, under the influence of familial, environmental, emotional and cognitive factors. In a general population twin sample (n = 579) and in a study of patients with psychotic disorder (n = 57), their non-psychotic siblings (n = 59) and unrelated controls (n = 75), the experience sampling paradigm (ESM; repetitive, random sampling of momentary mental states and context) was applied. We analysed, in a within-person prospective design, (i) transfer of momentary anomalous experience at time point (t–1) to time point (t) in daily life, and (ii) moderating effects of negative affect, positive affect, daily stressors, IQ and childhood trauma. Additionally, (iii) familial associations between persistence of momentary anomalous experience and psychotic symptomatology were investigated. Higher level of schizotypy in the twins (but not higher level of psychotic symptoms in patients) predicted more persistence of momentary anomalous experience in daily life, both within subjects and across relatives. Persistence of momentary anomalous experience was highest in patients, intermediate in their siblings and lowest in controls. In both studies, persistence of momentary anomalous experience was moderated by higher levels of negative affect, daily stressors and childhood trauma (only in twins), and by lower levels of positive affect. The study of alterations in the moment-to-moment transfer of subtle anomalous experience of psychosis, resulting in their persistence, helps to explain why psychotic and emotional dysregulation tend to cluster in a single phenotype such as schizophrenia, and how familial and environmental risks increase the risk of expression of psychosis from, first, subtle momentary anomalous experience to, second, observable clinical symptoms. Citation: Wigman JTW, Collip D, Wichers M, Delespaul P, Derom C, et al. (2013) Altered Transfer of Momentary Mental States (ATOMS) as the Basic Unit of Psychosis Liability in Interaction with Environment and Emotions. PLoS ONE 8(2): e54653. doi:10.1371/journal.pone.0054653 Editor: James G. Scott, The University of Queensland, Australia Received May 21, 2012; Accepted December 17, 2012; Published February 15, 2013 Copyright: 2013 Wigman et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The TWIN study has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit association for Scientific Research in Multiple Births (Belgium). The infrastructure for the GROUP study is funded by grant 10-000-1002 from the Geestkracht program of the Netherlands Organization for Health Research and Development (ZonMw) and matching funds from participating universities and mental health care organizations (Site Amsterdam: Academic Psychiatric Centre AMC, Ingeest, Arkin, Dijk en Duin, Rivierduinen, Erasmus MC, GGZ Noord Holland Noord; Site Utrecht: University Medical Centre Utrecht, Altrecht, Symfora, Meerkanten, Riagg Amersfoort, Delta; Site Groningen: University Medical Center Groningen, Lentis, GGZ Friesland, GGZ Drenthe, Dimence, Mediant, GGZ De Grote Rivieren, and Parnassia Psychomedical Centre; Site Maastricht: Maastricht University Medical Center, GGZ Eindhoven, GGZ Midden-Brabant, GGZ Oost-Brabant, GGZ Noord-Midden Limburg, Mondriaan Zorggroep, Prins Clauscentrum Sittard, RIAGG Roermond, Universitair Centrum SintJozef Kortenberg, CAPRI University of Antwerp, PC Ziekeren Sint-Truiden, PZ Sancta Maria Sint-Truiden, GGZ Overpelt, OPZ Rekem). Supported by the European Community’s Seventh Framework Program under grant agreement No. HEALTH-F2-2009-241909 (Project EU-GEI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have the following interest. Prof van Os conducts other studies, not related to the study that is the subject of the authors’ submission and approved by the standing ethics committee, that are in part supported by unrestricted grants from Janssen-Cilag, Eli Lilly and Co, AstraZeneca, and Lundbeck. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: j.vanos@maastrichtuniversity.nl . These authors contributed equally to this work. PLOS ONE | www.plosone.org 1 February 2013 | Volume 8 | Issue 2 | e54653

The event-driven paradigm for control, communication and optimization

The event-driven paradigm offers an alternative to the time-driven paradigm for modelling, sampling, estimation, control and optimization. This has come about largely as a consequence of systems being increasingly networked, wireless and consisting of distributed communicating components. The key idea is that control actions need not be dictated by time steps taken by a “clock”; rather, an action should be triggered by an “event” which may be a well-defined condition on the system state, including the possibility of a simple time step, or a random state transition. We provide an overview of recent developments in event-driven approaches and focus on two areas to illustrate their value. First, in distributed systems, we describe how event-driven, rather than synchronous, communication can guarantee convergence in cooperative distributed optimization while provably maintaining optimality. Second, in hybrid systems where events naturally decompose state trajectories into different discrete states (modes), we review the theory of infinitesimal perturbation analysis (IPA) which offers an event-driven “IPA calculus” for evaluating (or estimating in the case of stochastic systems) gradients of performance metrics, thus facilitating the solution of a large class of control and optimization problems.

Compressive sensing: From theory to applications, a survey

Compressive sensing (CS) is a novel sampling paradigm that samples signals in a much more efficient way than the established Nyquist sampling theorem. CS has recently gained a lot of attention due to its exploitation of signal sparsity. Sparsity, an inherent characteristic of many natural signals, enables the signal to be stored in few samples and subsequently be recovered accurately, courtesy of CS. This article gives a brief background on the origins of this idea, reviews the basic mathematical foundation of the theory and then goes on to highlight different areas of its application with a major emphasis on communications and network domain. Finally, the survey concludes by identifying new areas of research where CS could be beneficial.

Double‐level binary tree Bayesian compressed sensing for block structured sparse signals

Sparsity is one of the key points in the compressed sensing (CS) theory, which provides a sub-Nyquist sampling paradigm. Nevertheless, apart from sparsity, structures on the sparse patterns such as block structures and tree structures can also be exploited to improve the reconstruction performance and further reduce the sampling rate in CS framework. Based on the fact that the block structure is also sparse for a widely studied block sparse signal, in this study, a double-level binary tree (DBT) hierarchical Bayesian model is proposed under the Bayesian CS (BCS) framework. The authors exploit a recovery algorithm with the proposed DBT structured model, and the block clustering in the proposed algorithm can be achieved fastly and correctly using the Markov Chain Monte Carlo method. The experimental results demonstrate that, compared with most existing CS algorithms for block sparse signals, our proposed DBT-based BCS algorithm can obtain good recovery results with less time consuming.

Do not throw out the baby with the bath water: choosing an effective baseline for a functional localizer of speech processing

Speech processing engages multiple cortical regions in the temporal, parietal, and frontal lobes. Isolating speech-sensitive cortex in individual participants is of major clinical and scientific importance. This task is complicated by the fact that responses to sensory and linguistic aspects of speech are tightly packed within the posterior superior temporal cortex. In functional magnetic resonance imaging (fMRI), various baseline conditions are typically used in order to isolate speech-specific from basic auditory responses. Using a short, continuous sampling paradigm, we show that reversed (“backward”) speech, a commonly used auditory baseline for speech processing, removes much of the speech responses in frontal and temporal language regions of adult individuals. On the other hand, signal correlated noise (SCN) serves as an effective baseline for removing primary auditory responses while maintaining strong signals in the same language regions. We show that the response to reversed speech in left inferior frontal gyrus decays significantly faster than the response to speech, thus suggesting that this response reflects bottom-up activation of speech analysis followed up by top-down attenuation once the signal is classified as nonspeech. The results overall favor SCN as an auditory baseline for speech processing.