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https://www.readbyqxmd.com/read/28108257/working-memory-load-dependent-spatio-temporal-activity-of-single-trial-p3-response-detected-with-an-adaptive-wavelet-denoiser
#1
Qiushi Zhang, Xueqian Yang, Li Yao, Xiaojie Zhao
Working memory (WM) refers to the holding and manipulation of information during cognitive tasks. Its underlying neural mechanisms have been explored through both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Trial-by-trial coupling of simultaneously collected EEG and fMRI signals has become an important and promising approach to study the spatio-temporal dynamics of such cognitive processes. Previous studies have demonstrated a modulation effect of the WM load on both the BOLD response in certain brain areas and the amplitude of P3...
January 17, 2017: Neuroscience
https://www.readbyqxmd.com/read/28103556/steerable-wavelet-machines-swm-learning-moving-frames-for-texture-classification
#2
Adrien Depeursinge, Zsuzsanna Puspoki, John Paul Ward, Michael Unser
We present texture operators encoding classspecific local organizations of image directions (LOID) in a rotation-invariant fashion. The LOIDs are key for visual understanding, and are at the origin of the success of the popular approaches such as local binary patterns (LBP) and the scaleinvariant feature transform (SIFT). Whereas LBPs and SIFT yield handcrafted image representations, we propose to learn dataspecific representations of the LOIDs in a rotation-invariant fashion. The image operators are based on steerable circular harmonic wavelets (CHW), offering a rich and yet compact initial representation for characterizing natural textures...
January 18, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28103283/orthogonal-procrustes-analysis-for-dictionary-learning-in-sparse-linear-representation
#3
Giuliano Grossi, Raffaella Lanzarotti, Jianyi Lin
In the sparse representation model, the design of overcomplete dictionaries plays a key role for the effectiveness and applicability in different domains. Recent research has produced several dictionary learning approaches, being proven that dictionaries learnt by data examples significantly outperform structured ones, e.g. wavelet transforms. In this context, learning consists in adapting the dictionary atoms to a set of training signals in order to promote a sparse representation that minimizes the reconstruction error...
2017: PloS One
https://www.readbyqxmd.com/read/28100896/investigating-the-effect-of-traditional-persian-music-on-ecg-signals-in-young-women-using-wavelet-transform-and-neural-networks
#4
Behzad Abedi, Ataollah Abbasi, Atefeh Goshvarpour
OBJECTIVE: In the past few decades, several studies have reported the physiological effects of listening to music. The physiological effects of different music types on different people are different. In the present study, we aimed to examine the effects of listening to traditional Persian music on electrocardiogram (ECG) signals in young women. METHODS: Twenty-two healthy females participated in this study. ECG signals were recorded under two conditions: rest and music...
January 17, 2017: Anatolian Journal of Cardiology
https://www.readbyqxmd.com/read/28098797/nonlinear-fusion-of-multispectral-citrus-fruit-image-data-with-information-contents
#5
Peilin Li, Sang-Heon Lee, Hung-Yao Hsu, Jae-Sam Park
The main issue of vison-based automatic harvesting manipulators is the difficulty in the correct fruit identification in the images under natural lighting conditions. Mostly, the solution has been based on a linear combination of color components in the multispectral images. However, the results have not reached a satisfactory level. To overcome this issue, this paper proposes a robust nonlinear fusion method to augment the original color image with the synchronized near infrared image. The two images are fused with Daubechies wavelet transform (DWT) in a multiscale decomposition approach...
January 13, 2017: Sensors
https://www.readbyqxmd.com/read/28097047/quantifying-the-on-and-off-contributions-to-the-flash-erg-with-the-discrete-wavelet-transform
#6
Mathieu Gauvin, Maja Sustar, John M Little, Jelka Brecelj, Jean-Marc Lina, Pierre Lachapelle
PURPOSE: Discrete wavelet transform (DWT) analyses suggest that the 20- and 40-Hz components of the short-flash photopic electroretinogram (ERG) are closely related to the ON and OFF pathways, respectively. With the DWT, we examined how the ERG ON and OFF components are modulated by the stimulus intensity and/or duration. METHODS: Discrete wavelet transform descriptors (20, 40 Hz and 40:20-Hz ratio) were extracted from ERGs evoked to 25 combinations of flash durations (150-5 ms) and strengths (0...
January 2017: Translational Vision Science & Technology
https://www.readbyqxmd.com/read/28095866/improvement-of-displacement-estimation-of-breast-tissue-in-ultrasound-elastography-using-the-monogenic-signal
#7
Taher Slimi, Ines Marzouk Moussa, Tarek Kraiem, Halima Mahjoubi
BACKGROUND: In breast ultrasound elastography, tissues displacements estimation is obtained through a technique that follows the evolution of tissues under stress. However, during the acquisition of B-mode images, tissue displacements are often contaminated with multiplicative noise caused by changes in the speckle pattern in the tissue. Thus, the application of monogenic signal technique on the B-mode image in order to estimate displacement tissue, result in a presence of amplified noise in the deformation tissue image, which severely obscures the useful information...
January 17, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28092536/improved-denoising-via-poisson-mixture-modeling-of-image-sensor-noise
#8
Jiachao Zhang, Keigo Hirakawa
This paper describes a study aimed at comparing the real image sensor noise distribution to the models of noise often assumed in image denoising designs. Quantile analysis in pixel, wavelet transform, and variance stabilization domains reveal that the tails of Poisson, signal-dependent Gaussian, and Poisson-Gaussian models are too short to capture real sensor noise behavior. A new Poisson mixture noise model is proposed to correct the mismatch of tail behavior. Based on the fact that noise model mismatch results in image denoising that undersmoothes real sensor data, we propose a mixture of Poisson denoising method to remove the denoising artifacts without affecting image details such as edge and textures...
January 10, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28092514/a-multivariate-approach-for-patient-specific-eeg-seizure-detection-using-empirical-wavelet-transform
#9
Abhijit Bhattacharyya, Ram Bilas Pachori
OBJECTIVE: This paper investigates the multivariate oscillatory nature of electroencephalogram (EEG) signals in adaptive frequency scales for epileptic seizure detection. METHODS: The empirical wavelet transform (EWT) has been explored for the multivariate signals in order to determine the joint instantaneous amplitudes and frequencies in signal adaptive frequency scales. The proposed multivariate extension of EWT has been studied on multivariate multi-component synthetic signal, as well as on multivariate EEG signals of CHB-MIT scalp EEG database...
January 9, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28091915/wavelet-analysis-of-cerebral-microcirculation-in-hypovolemic-shock
#10
V V Aleksandrin, A A Kubatiev
Hypovolemic shock leads to severe cerebral ischemia and increases spectral amplitudes of cerebral blood flow oscillations in respiratory frequency range.
January 2017: Bulletin of Experimental Biology and Medicine
https://www.readbyqxmd.com/read/28091395/a-novel-onset-detection-technique-for-brain-computer-interfaces-using-sound-production-related-cognitive-tasks-in-simulated-online-system
#11
YoungJae Song, Francisco Sepulveda
OBJECTIVE: Self-paced EEG-based BCIs (SP-BCIs) have traditionally been avoided due to two sources of uncertainty: (1) precisely when an intentional command is sent by the brain, i.e., the command onset detection problem, and (2) how different the intentional command is when compared to non-specific (or idle) states. Performance evaluation is also a problem and there are no suitable standard metrics available. In this paper we attempted to tackle these issues. APPROACH: Self-paced covert sound-production cognitive tasks (i...
February 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28087436/functional-connectivity-analysis-using-fnirs-in-healthy-subjects-during-prolonged-simulated-driving
#12
Liwei Xu, Bitian Wang, Gongcheng Xu, Wei Wang, Zhian Liu, Zengyong Li
Noninvasive and accurate assessment of driving fatigue in relation to brain activity during long-term driving can contribute to traffic safety and accident prevention. This study evaluated functional connectivity (FC) in relevant brain regions. Synergistic mechanisms in different brain regions were detected by a novel simulator, which combined semi-immersive virtual reality technology and functional near-infrared spectroscopy. Each subject was instructed to complete driving tasks coupled with a mental calculation task...
January 10, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28086909/fast-detection-and-data-compensation-for-electrodes-disconnection-in-long-term-monitoring-of-dynamic-brain-electrical-impedance-tomography
#13
Ge Zhang, Meng Dai, Lin Yang, Weichen Li, Haoting Li, Canhua Xu, Xuetao Shi, Xiuzhen Dong, Feng Fu
BACKGROUND: Electrode disconnection is a common occurrence during long-term monitoring of brain electrical impedance tomography (EIT) in clinical settings. The data acquisition system suffers remarkable data loss which results in image reconstruction failure. The aim of this study was to: (1) detect disconnected electrodes and (2) account for invalid data. METHODS: Weighted correlation coefficient for each electrode was calculated based on the measurement differences between well-connected and disconnected electrodes...
January 7, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28079524/spatial-heterogeneity-in-the-time-and-frequency-properties-of-skin-perfusion
#14
Michele Sorelli, Zlatka Stoyneva, Irina Mizeva, Leonardo Bocchi
Pathological alterations of the microcirculatory system can be identified by measuring the temporal and spectral properties of Laser Doppler Flowmetry (LDF) signals acquired on the skin, and their changes following physiological stimulation. A wide range of stimulation protocols and measurement locations are observed in literature. Researchers often use non-invasive stimulation techniques, such as post-occlusive hyperaemia, cold tests, and local heating. As concerns the stimulation/recording sites, the forearm, fingers, and toes are typically selected to conduct microcirculation studies...
January 12, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28070749/an-automated-microemboli-detection-and-classification-system-using-backscatter-rf-signals-and-differential-evolution
#15
Karim Ferroudji, Nabil Benoudjit, Ayache Bouakaz
Embolic phenomena, whether air or particulate emboli, can induce immediate damages like heart attack or ischemic stroke. Embolus composition (gaseous or particulate matter) is vital in predicting clinically significant complications. Embolus detection using Doppler methods have shown their limits to differentiate solid and gaseous embolus. Radio-frequency (RF) ultrasound signals backscattered by the emboli contain additional information on the embolus in comparison to the traditionally used Doppler signals...
January 9, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28066844/tight-graph-framelets-for-sparse-diffusion-mri-q-space-representation
#16
Pew-Thian Yap, Bin Dong, Yong Zhang, Dinggang Shen
In diffusion MRI, the outcome of estimation problems can often be improved by taking into account the correlation of diffusion-weighted images scanned with neighboring wavevectors in q-space. For this purpose, we propose in this paper to employ tight wavelet frames constructed on non-flat domains for multi-scale sparse representation of diffusion signals. This representation is well suited for signals sampled regularly or irregularly, such as on a grid or on multiple shells, in q-space. Using spectral graph theory, the frames are constructed based on quasi-affine systems (i...
October 2016: Medical Image Computing and Computer-assisted Intervention: MICCAI ..
https://www.readbyqxmd.com/read/28066840/task-based-design-of-fluence-field-modulation-in-ct-for-model-based-iterative-reconstruction
#17
Grace J Gang, Jeffrey H Siewerdsen, J Webster Stayman
A task-driven imaging framework for prospective fluence field modulation (FFM) is developed in this paper. The design approach uses a system model that includes a parameterized FFM acquisition and model-based iterative reconstruction (MBIR) for image formation. Using prior anatomical knowledge (e.g. from a low-dose 3D scout image), accurate predictions of spatial resolution and noise as a function of FFM are integrated into a task-based objective function. Specifically, detectability index (d'), a common metric for task-based image quality assessment, is computed for a specific formulation of the imaging task...
July 2016: Conference Proceedings of International Conference on Image Formation in X-Ray Computed Tomography
https://www.readbyqxmd.com/read/28066810/dynamic-susceptibility-contrast-mri-quantification-software-tool-development-and-evaluation
#18
Panagiotis Korfiatis, Timothy L Kline, Zachary S Kelm, Rickey E Carter, Leland S Hu, Bradley J Erickson
Relative cerebral blood volume (rCBV) is a magnetic resonance imaging biomarker that is used to differentiate progression from pseudoprogression in patients with glioblastoma multiforme, the most common primary brain tumor. However, calculated rCBV depends considerably on the software used. Automating all steps required for rCBV calculation is important, as user interaction can lead to increased variability and possible inaccuracies in clinical decision-making. Here, we present an automated tool for computing rCBV from dynamic susceptibility contrast-magnetic resonance imaging that includes leakage correction...
December 2016: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/28065673/spectral-analysis-of-reflex-cutaneous-vasodilatation-during-passive-heat-stress
#19
Matthew M Mallette, Gary J Hodges, Gregory W McGarr, David A Gabriel, Stephen S Cheung
Previous work has demonstrated that spectral analysis is a useful tool to non-invasively ascertain the mechanisms of control of the cutaneous circulation. The majority of work using spectral analysis has focused on local control mechanisms, with none examining reflex control. Skin blood flow was analysed using spectral analysis on the dorsal aspect of the forearm of 7 males and 7 females during passive heat stress, with mean forearm and local temperature at the site of measurement maintained at thermoneutral (33°C) to minimize the effect of local control mechanisms...
January 5, 2017: Microvascular Research
https://www.readbyqxmd.com/read/28063666/development-of-a-clinical-applicable-graphical-user-interface-to-automatically-detect-exercise-oscillatory-ventilation-the-vodex-tool
#20
Justien Cornelis, Tim Denis, Paul Beckers, Christiaan Vrints, Dirk Vissers, Maggy Goossens
BACKGROUND: Cardiopulmonary exercise testing (CPET) gained importance in the prognostic assessment of especially patients with heart failure (HF). A meaningful prognostic parameter for early mortality in HF is exercise oscillatory ventilation (EOV). This abnormal respiratory pattern is recognized by hypo- and hyperventilation during CPET. Up until now, assessment of EOV is mainly done upon visual agreement or manual calculation. The purpose of this research was to automate the interpretation of EOV so this prognostic parameter could be readily investigated during CPET...
December 29, 2016: International Journal of Cardiology
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