Search results for "complexi"
showing 10 items of 1116 documents
The facilitative effect of gestures on the neural processing of semantic complexity in a continuous narrative
2019
© 2019 Elsevier Inc. Gestures are elemental components of social communication and aid comprehension of verbal messages; however, little is known about the potential role of gestures in facilitating processing of semantic complexity in an ecologically valid setting. The goal of this study was to investigate whether cognitive load, as indexed by semantic complexity, is modulated by the presentation of gestures accompanying speech. Twenty healthy participants watched 16 video clips of a short narrative while instructed to carefully listen to and watch the narrator while functional magnetic resonance imaging (fMRI) data were acquired. The videos contained passages with and without various co-s…
Instantaneous Transfer Entropy for the Study of Cardiovascular and Cardio-Respiratory Nonstationary Dynamics
2017
Objective: Measures of transfer entropy (TE) quantify the direction and strength of coupling between two complex systems. Standard approaches assume stationarity of the observations, and therefore are unable to track time-varying changes in nonlinear information transfer with high temporal resolution. In this study, we aim to define and validate novel instantaneous measures of TE to provide an improved assessment of complex nonstationary cardiorespiratory interactions. Methods: We here propose a novel instantaneous point-process TE (ipTE) and validate its assessment as applied to cardiovascular and cardiorespiratory dynamics. In particular, heartbeat and respiratory dynamics are characteriz…
Differences in sensory processing of German vowels and physically matched non-speech sounds as revealed by the mismatch negativity (MMN) of the human…
2014
We compared processing of speech and non-speech by means of the mismatch negativity (MMN). For this purpose, the MMN elicited by vowels was compared to those elicited by two non-speech stimulus types: spectrally rotated vowels, having the same stimulus complexity as the speech stimuli, and sounds based on the bands of formants of the vowels, representing non-speech stimuli of lower complexity as compared to the other stimulus types. This design allows controlling for effects of stimulus complexity when comparing neural correlates of processing speech to non-speech. Deviants within a modified multi-feature design differed either in duration or spectral property. Moreover, the difficulty to d…
Nursing staff interactions during the older residents' transition into long-term care facility in a nursing home in rural Norway: an ethnographic stu…
2015
Background: Future challenges in many countries are the recruitment of competent staff in long-term care facilities, and the use of unlicensed staff. Our study describes and explores staff interactions in a long-term care facility, which may facilitate or impede healthy transition processes for older residents in transition. Methods: An ethnographic study based on fieldwork following ten older residents admission day and their initial week in the long-term care facility, seventeen individual semi-structured interviews with different nursing staff categories and the leader of the institution, and reading of relevant documents. Results: The interaction among all staff categories influenced th…
Clinical features, disease progression and use of healthcare resources in a large sample of 866 patients from 24 headache centers: A real-life perspe…
2021
Objective: To develop a dedicated Italian chronic migraine (CM) database (IRON project) to overcome disease misconceptions, improve clinical administration, reduce patients' burden, and rationalize economic resource allotment.Background: Proper CM management requires a comprehensive appraisal of its full clinical, social, and economic complexity.Methods: In this cross-sectional study, CM patients were screened in 24 certified headache centers with face-to-face interviews. Information on sociodemographic factors, medical history, characteristics of CM, and of prior episodic migraine (EM), and healthcare resource use was gathered using a semistructured web-based questionnaire.Results: A total…
Quantifying changes in EEG complexity induced by photic stimulation.
2009
Summary Objectives: This study aims to characterize EEG complexity, measured as the prediction error resulting from nonlinear prediction, in healthy humans during photic stimulation. Methods: EEGs were recorded from 15 subjects with eyes closed (EC) and eyes open (EO), during the baseline condition and during stroboscopic photic stimulation (PS) at 5, 10, and 15 Hz. The mean squared prediction error (MSPE) resulting from nearest neighbor local linear prediction was taken as complexity index. Complexity maps were generated interpolating the MSPE index over a schematic scalp representation. Results: Statistical analysis revealed that: i) EEG shows good predictability in all conditions and see…
Time-Varying Surrogate Data to Assess Nonlinearity in Nonstationary Time Series: Application to Heart Rate Variability
2009
We propose a method to extend to time-varying (TV) systems the procedure for generating typical surrogate time series, in order to test the presence of nonlinear dynamics in potentially nonstationary signals. The method is based on fitting a TV autoregressive (AR) model to the original series and then regressing the model coefficients with random replacements of the model residuals to generate TV AR surrogate series. The proposed surrogate series were used in combination with a TV sample entropy (SE) discriminating statistic to assess nonlinearity in both simulated and experimental time series, in comparison with traditional time-invariant (TIV) surrogates combined with the TIV SE discrimin…
Cardiovascular Benefits of Group Sport Interventions: Importance of Improved Fitness in Risk Reduction
2018
BACKGROUND: Physical inactivity is a leading risk factor for cardiovascular disease worldwide. Group sport participation offers a unique, engaging approach for delivering physical activity interventions, but its overall effect on cardiometabolic risk factors is unclear. OBJECTIVE: To estimate the pooled effects of community-based, recreational-level group sports on cardiometabolic risk factors and fitness parameters among adults. METHODS AND RESULTS: We systematically searched electronic databases for English articles reporting the effectiveness of recreational-level group sports, published between January 1, 1965 and January 17, 2017. We extracted baseline and end of intervention means for…
Design Issues and Sample Size when Exposure Measurement is Inaccurate
2001
AbstractMeasurement error often leads to biased estimates and incorrect tests in epidemiological studies. These problems can be corrected by design modifications which allow for refined statistical models, or in some situations by adjusted sample sizes to compensate a power reduction. The design options are mainly an additional replication or internal validation study. Sample size calculations for these designs are more complex, since usually there is no unique design solution to obtain a prespecified power. Thus, additionally to a power requirement, an optimal design should also fulfill the criteria of minimizing overall costs. In this review corresponding strategies and formulae are descr…
A simplified framework to optimize MRI contrast preparation
2018
PURPOSE This article proposes a rigorous optimal control framework for the design of preparation schemes that optimize MRI contrast based on relaxation time differences. METHODS Compared to previous optimal contrast preparation schemes, a drastic reduction of the optimization parameter number is performed. The preparation scheme is defined as a combination of several block pulses whose flip angles, phase terms and inter-pulse delays are optimized to control the magnetization evolution. RESULTS The proposed approach reduces the computation time of B 0 -robust preparation schemes to around a minute (whereas several hours were required with previous schemes), with negligible performance loss. …