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Hsiao-Feng Hu, Hsin Hsiu, Ciao-Jyuan Sung, Chien-Hsing Lee
We aimed to identify the microcirculatory regulatory mechanisms in diabetic and prediabetic humans using a noninvasive method combining spectral analysis with laser-Doppler flowmetry (LDF) measurements on the skin surface. LDF signals were measured by a moorVMS-LDF device to measure the microcirculatory blood flow flux with a time constant of 0.001 s, a cutoff frequency of 14.9 kHz, and a sampling frequency of 40 Hz. The laser operating wavelength and output power were 400-700 nm and 6 mW, respectively...
December 7, 2016: Lasers in Medical Science
Shiqi Huang, Wenzhun Huang, Ting Zhang
The most distinctive characteristic of synthetic aperture radar (SAR) is that it can acquire data under all weather conditions and at all times. However, its coherent imaging mechanism introduces a great deal of speckle noise into SAR images, which makes the segmentation of target and shadow regions in SAR images very difficult. This paper proposes a new SAR image segmentation method based on wavelet decomposition and a constant false alarm rate (WD-CFAR). The WD-CFAR algorithm not only is insensitive to the speckle noise in SAR images but also can segment target and shadow regions simultaneously, and it is also able to effectively segment SAR images with a low signal-to-clutter ratio (SCR)...
December 7, 2016: Scientific Reports
Jiangdian Song, Zaiyi Liu, Wenzhao Zhong, Yanqi Huang, Zelan Ma, Di Dong, Changhong Liang, Jie Tian
This was a retrospective study to investigate the predictive and prognostic ability of quantitative computed tomography phenotypic features in patients with non-small cell lung cancer (NSCLC). 661 patients with pathological confirmed as NSCLC were enrolled between 2007 and 2014. 592 phenotypic descriptors was automatically extracted on the pre-therapy CT images. Firstly, support vector machine (SVM) was used to evaluate the predictive value of each feature for pathology and TNM clinical stage. Secondly, Cox proportional hazards model was used to evaluate the prognostic value of these imaging signatures selected by SVM which subjected to a primary cohort of 138 patients, and an external independent validation of 61 patients...
December 6, 2016: Scientific Reports
Vincent Pichot, Frédéric Roche, Sébastien Celle, Jean-Claude Barthélémy, Florian Chouchou
Since the pioneering studies of the 1960s, heart rate variability (HRV) has become an increasingly used non-invasive tool for examining cardiac autonomic functions and dysfunctions in various populations and conditions. Many calculation methods have been developed to address these issues, each with their strengths and weaknesses. Although, its interpretation may remain difficult, this technique provides, from a non-invasive approach, reliable physiological information that was previously inaccessible, in many fields including death and health prediction, training and overtraining, cardiac and respiratory rehabilitation, sleep-disordered breathing, large cohort follow-ups, children's autonomic status, anesthesia, or neurophysiological studies...
2016: Frontiers in Physiology
Huile Xu, Jinyi Liu, Haibo Hu, Yi Zhang
Wearable sensors-based human activity recognition introduces many useful applications and services in health care, rehabilitation training, elderly monitoring and many other areas of human interaction. Existing works in this field mainly focus on recognizing activities by using traditional features extracted from Fourier transform (FT) or wavelet transform (WT). However, these signal processing approaches are suitable for a linear signal but not for a nonlinear signal. In this paper, we investigate the characteristics of the Hilbert-Huang transform (HHT) for dealing with activity data with properties such as nonlinearity and non-stationarity...
December 2, 2016: Sensors
Dongqing Wang, Xu Zhang, Xiaoping Gao, Xiang Chen, Ping Zhou
This study presents wavelet packet feature assessment of neural control information in paretic upper limb muscles of stroke survivors for myoelectric pattern recognition, taking advantage of high-resolution time-frequency representations of surface electromyogram (EMG) signals. On this basis, a novel channel selection method was developed by combining the Fisher's class separability index and the sequential feedforward selection analyses, in order to determine a small number of appropriate EMG channels from original high-density EMG electrode array...
2016: Frontiers in Neurology
Xikun Hu, Tian Jin
The radar sensor described realizes healthcare monitoring capable of detecting subject chest-wall movement caused by cardiopulmonary activities and wirelessly estimating the respiration and heartbeat rates of the subject without attaching any devices to the body. Conventional single-tone Doppler radar can only capture Doppler signatures because of a lack of bandwidth information with noncontact sensors. In contrast, we take full advantage of impulse radio ultra-wideband (IR-UWB) radar to achieve low power consumption and convenient portability, with a flexible detection range and desirable accuracy...
November 30, 2016: Sensors
Jie Qin, Zhan Gao, Xu Wang, Shanwei Yang
A speckle interferometer which can measure whole field three-dimensional displacements continuously and dynamically has been built. Three different wavelength lasers are used to produce the speckle interferograms of the two in-plane displacements (displacements in the x- and y-direction) and one out-of-plane displacement (displacement in the z-direction), respectively. One color CCD camera is employed to collect these mixed speckle interferograms simultaneously. The mixed interferograms are separated by the Red, Green and Blue channels of the color CCD camera, and then are processed by the wavelet transform technique to extract the phase information of the measured object...
November 29, 2016: Sensors
Davide Bianchi, Claudia Lenauer, Gerhard Betz, András Vernes
Continuous ultra-mild wear quantification using radioactive isotopes involves measuring very low amounts of activity in limited time intervals. This results in gamma spectra with poor signal-to-noise ratio and hence very scattered wear data, especially during running-in, where wear is intrinsically low. Therefore, advanced filtering methods reducing the wear data scattering and making the calculation of the main peak area more accurate are mandatory. An energy-time dependent threshold for wavelet detail coefficients based on Poisson statistics and using a combined Barwell law for the estimation of the average photon counting rate is then introduced...
November 26, 2016: Applied Radiation and Isotopes
Guang Deng
Edge-aware smoothing has been extensively studied due to its wide range of applications in computer vision and graphics.Most published works have been focused on formulating the smoothing problem in the spatial domain. In this paper, we propose a new edge-aware smoothing framework called guided wavelet shrinkage (GWS) which is formulated in the wavelet domain as a maximum a posterior estimation problem. We impose a number of desirable properties on the statistical models and the associated parameters in order to derive an effective and computationally efficient algorithm...
December 1, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Paul Hill, Mohammed Ebrahim Al-Mualla, David Bull
A perceptual image fusion method is proposed that employs explicit luminance and contrast masking models. These models are combined to give the perceptual importance of each coefficient produced by the Dual-Tree Complex Wavelet Transform of each input image. This combined model of perceptual importance is used to select which coefficients are retained and furthermore to determine how to present the retained information in the most effective way. This work is the first to give a principled approach to image fusion from a perceptual perspective...
December 1, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Sirui Fu, Shuting Chen, Changhong Liang, Zaiyi Liu, Yanjie Zhu, Yong Li, Ligong Lu
Transcatheter arterial chemoembolization (TACE) and sorafenib combination treatment for unselected hepatocellular carcinoma (HCC) is controversial. We explored the potential of texture analysis for appropriate patient selection. There were 261 HCCs included (TACE group: n = 197; TACE plus sorafenib (TACE+Sorafenib) group n = 64). We applied a Gabor filter and wavelet transform with 3 band-width responses (filter 0, 1.0, and 1.5) to portal-phase computed tomography (CT) images of the TACE group. Twenty-one textural parameters per filter were extracted from the region of interests delineated around tumor outline...
November 29, 2016: Oncotarget
S Ohdachi
A new type of wavelet-based analysis for the magnetic fluctuations by which toroidal mode number can be resolved is proposed. By using a wavelet, having a different phase toroidally, a spectrogram with a specific toroidal mode number can be obtained. When this analysis is applied to the measurement of the fluctuations observed in the large helical device, MHD activities having similar frequency in the laboratory frame can be separated from the difference of the toroidal mode number. It is useful for the non-stationary MHD activity...
November 2016: Review of Scientific Instruments
Seong-Heon Seo, Dong Keun Oh
Scalogram is widely used to measure instantaneous frequencies of non-stationary signals. However, the basic property of the scalogram is observed only for stationary sinusoidal functions. A property of the scalogram for non-stationary signal is analytically derived in this paper. Based on the property, a new frequency measurement algorithm is proposed. In addition, a filter that can separate two similar frequency signals is developed based on the wavelet transform.
November 2016: Review of Scientific Instruments
Shiwan Chen, Chunhe Yang, Guibin Wang, Wei Liu
In conventional AE source localization acoustic emission (AE) signals are applied directly to localize the source without any waveform identification or quality evaluation, which always leads to large errors in source localization. To improve the reliability and accuracy of acoustic emission source localization, an identification procedure is developed to assess the similarity of AE signals to select signals with high quality to localize the AE source. Magnitude square coherence (MSC), wavelet coherence and dynamic timing warping (DTW) are successively applied for similarity assessment...
November 14, 2016: Ultrasonics
Unni V S, Deepak Mishra, G R K S Subrahmanyam
The need for image fusion in current image processing systems is increasing mainly due to the increased number and variety of image acquisition techniques. Image fusion is the process of combining substantial information from several sensors using mathematical techniques in order to create a single composite image that will be more comprehensive and thus more useful for a human operator or other computer vision tasks. This paper presents a new approach to multifocus image fusion based on sparse signal representation...
December 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Yair Rivenson, Yichen Wu, Hongda Wang, Yibo Zhang, Alborz Feizi, Aydogan Ozcan
High-resolution imaging of densely connected samples such as pathology slides using digital in-line holographic microscopy requires the acquisition of several holograms, e.g., at >6-8 different sample-to-sensor distances, to achieve robust phase recovery and coherent imaging of specimen. Reducing the number of these holographic measurements would normally result in reconstruction artifacts and loss of image quality, which would be detrimental especially for biomedical and diagnostics-related applications...
November 30, 2016: Scientific Reports
Tianhua Xu, Guang Wang, Haifeng Wang, Tangming Yuan, Zhiwang Zhong
A point machine's gap is an important indication of its healthy status. An edge detection algorithm is proposed to measure and calculate a point machine's gap from the gap image captured by CCD plane arrays. This algorithm integrates adaptive wavelet-based image denoising, locally adaptive image binarization, and mathematical morphology technologies. The adaptive wavelet-based image denoising obtains not only an optimal denoising threshold, but also unblurred edges. Locally adaptive image binarization has the advantage of overcoming the local intensity variation in gap images...
November 26, 2016: Sensors
Takefumi Ohki, Atsuko Gunji, Yuichi Takei, Hidetoshi Takahashi, Yuu Kaneko, Yosuke Kita, Naruhito Hironaga, Shozo Tobimatsu, Yoko Kamio, Takashi Hanakawa, Masumi Inagaki, Kazuo Hiraki
Though recent studies have elucidated the earliest mechanisms of processing in multisensory integration, our understanding of how multisensory integration of more sustained and complicated stimuli is implemented in higher-level association cortices is lacking. In this study, we used magnetoencephalography (MEG) to determine how neural oscillations alter local and global connectivity during multisensory integration processing. We acquired MEG data from 15 healthy volunteers performing an audio-visual speech matching task...
November 29, 2016: Scientific Reports
Zhaoli Wang, Jun Li, Chengguang Lai, Zhaoyang Zeng, Ruida Zhong, Xiaohong Chen, Xiaowen Zhou, Mingyuan Wang
In recent decades, the occurrence and severity of drought in China has had devastating impact on social and economic development. The increase in drought has been attributed to global warming. We used the high-accuracy self-calibrating Palmer Drought Severity Index (scPDSI) to investigate the variation in drought in China between 1961 and 2009 using the Mann-Kendall (MK), continuous wavelet transform (CWT) and the rotated empirical orthogonal function (REOF) methods. We also analyzed the relationship between the rotated principal component time series (RPCs) and 74 circulation indices...
November 25, 2016: Science of the Total Environment
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