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Marcelo E Guerin, Guillaume Stirnemann, David Giganti
An immense repertoire of protein chemical modifications catalyzed by enzymes is available as proteomics data. Quantifying the impact of the conformational dynamics of the modified peptide remains challenging to understand the decisive kinetics and amino acid sequence specificity of these enzymatic reactions in vivo, because the target peptide must be disordered to accommodate the specific enzyme-binding site. Here, we were able to control the conformation of a single-molecule peptide chain by applying mechanical force to activate and monitor its specific cleavage by a model protease...
October 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
Mercedeh Jahanseir, Seyed Kamaledin Setarehdan, Sirous Momenzadeh
Many of the surgeries performed under general anesthesia are aided by electroencephalogram (EEG) monitoring. With increased focus on detecting the anesthesia states of patients in the course of surgery, more attention has been paid to analyzing the power spectra and entropy measures of EEG signal during anesthesia. In this paper, by using the relative power of EEG frequency bands and the EEG entropy measures, a new method for detecting the depth of anesthesia states has been presented based on the least squares support vector machine (LS-SVM) classifiers...
October 18, 2018: Australasian Physical & Engineering Sciences in Medicine
Philip H Handle, Francesco Sciortino
We report a numerical test of the Adam-Gibbs relation for the TIP4P/2005 model of water. The configurational entropy is here evaluated as the logarithm of the number of different basins in the potential energy landscape sampled in equilibrium conditions. Despite the non-monotonic behaviour which characterise the density dependence of the diffusion coefficient, the Adam-Gibbs relation is satisfied within the numerical precision in a wide range of densities and temperatures. We also show that expressions based on the excess entropy (the logarithm of the number of sampled microstates in phase space) fail in the region of densities where a tetrahedral hydrogen bond network develops...
2018: Molecular Physics
Yanwei Li, Huibin Jia, Dongchuan Yu
A novel analysis of the spatial complexity of functional connectivity (SCFC) was proposed to investigate the spatial complexity of multiple dynamic functional connectivity series in an fNIRS study, using an approach combining principal component analysis and normalized entropy. The analysis was designed to describe the complex spatial features of phase synchrony based dynamic functional connectivity (dFC), which are unexplained in traditional approaches. The feasibility and validity of this method were verified in a sample of young patients with autism spectrum disorders (ASD)...
August 1, 2018: Biomedical Optics Express
M Wang, H Li, J Wang, S Gao
OBJECTIVE: X-ray diffraction-enhanced imaging (DEI) method was used to image hepatic fibrous samples, and the texture measurements based on DEI images were calculated and analyzed for investigating the feasibility of diagnosing fibrosis quantitatively. METHODS: Hepatic fibrosis of different severity in ICR mice was induced by injecting with carbon tetrachloride (CCl₄) olive oil solution for 21 d, 42 d and 84 d, respectively. The excised liver tissues were then imaged at the 4W1A Topography & Imaging Station of Beijing Synchrotron Radiation Facility (BSRF)...
October 18, 2018: Beijing da Xue Xue Bao. Yi Xue Ban, Journal of Peking University. Health Sciences
Pengfei Li, Xiangyu Jia, Xiaoliang Pan, Yihan Shao, Ye Mei
Free energy profile (FE Profile) is an essential quantity for the estimation of reaction rate and the validation of reaction mechanism. For chemical reactions in condensed phase or enzymatic reactions, the computation of FE profile at ab initio ( ai) quantum mechanical/molecular mechanics (QM/MM) level is still far too expensive. Although semiempirical (SE) method can be hundreds or thousands of times faster than the ai methods, the accuracy of SE methods is often unsatisfactory, due to the approximations that have been adopted in these methods...
October 18, 2018: Journal of Chemical Theory and Computation
Juan Zeng, Zunnan Huang
BACKGROUND: The rapidly increasing number of known protein sequences calls for more efficient methods to predict the three-dimensional (3D) structures of proteins, thus providing basic knowledge for rational drug design. Understanding the folding mechanism of proteins is valuable for predicting their 3D structures and for designing proteins with new functions and medicinal applications. Levinthal's paradox is that although the astronomical number of conformations possible even for proteins as small as 100 residues cannot be fully sampled, proteins in nature normally fold into the native state within timescales ranging from microseconds to hours...
October 17, 2018: Current Medicinal Chemistry
Jinling Zhao, Chengquan Zhou, Linsheng Huang, Xiaodong Yang, Bo Xu, Dong Liang
To obtain fine and potential features, a highly informative fused image created by merging multiple images is usually required. In our study, a novel fusion algorithm called JSKF-NSCT is proposed for fusing panchromatic (PAN) and hyperspectral (HS) images by combining the joint skewness-kurtosis figure (JSKF) and the non-subsampled contourlet transform (NSCT). The JSKF model is used first to derive the three most sensitive bands from the original HS image according to the product of the skewness and the kurtosis coefficients of each band...
October 15, 2018: Sensors
Christopher B Anderson
Background: Biogeographers assess how species distributions and abundances affect the structure, function, and composition of ecosystems. Yet we face a major challenge: it is difficult to precisely map species across landscapes. Novel Earth observations could overcome this challenge for vegetation mapping. Airborne imaging spectrometers measure plant functional traits at high resolution, and these measurements can be used to identify tree species. In this paper, I describe a trait-based approach to species identification with imaging spectroscopy, the Center for Conservation Biology species identification (CCB-ID) method, which was developed as part of an ecological data science evaluation competition...
2018: PeerJ
Laura Päeske, Maie Bachmann, Toomas Põld, Sara Pereira Mendes de Oliveira, Jaanus Lass, Jaan Raik, Hiie Hinrikus
The aim of the study is to clarify the impact of the strong cyclic signal component on the results of surrogate data method in the case of resting electroencephalographic (EEG) signals. In addition, the impact of segment length is analyzed. Different non-linear measures (fractality, complexity, etc.) of neural signals have been demonstrated to be useful to infer the non-linearity of brain functioning from EEG. The surrogate data method is often applied to test whether or not the non-linear structure can be captured from the data...
2018: Frontiers in Physiology
Da Chang, Jian Zhang, Wei Peng, Zhuowen Shen, Xin Gao, Youhong Du, Qiu Ge, Donghui Song, Yuanqi Shang, Ze Wang
Chronic smoking impairs brain functions in the prefrontal cortex and the projecting meso-cortical limbic system. The purpose of this pilot study is to examine whether modulating the frontal brain activity using high-frequency repetitive transcranial magnetic stimulation (rTMS) can improve smoking cessation and to explore the changing pattern of the brain activity after treatment. Fourteen treatment-seeking smokers were offered a program involving 10 days of rTMS treatment with a follow-up for another 25 days...
2018: Frontiers in Human Neuroscience
Ian M McDonough, Jonathan T Siegel
Brain structure has been proposed to facilitate as well as constrain functional interactions within brain networks. Simulation models suggest that integrity of white matter (WM) microstructure should be positively related to the complexity of BOLD signal - a measure of network interactions. Using 121 young adults from the Human Connectome Project, we empirically tested whether greater WM integrity would be associated with greater complexity of the BOLD signal during rest via multiscale entropy. Multiscale entropy measures the lack of predictability within a given time series across varying time scales, thus being able to estimate fluctuating signal dynamics within brain networks...
2018: Frontiers in Integrative Neuroscience
German G Miroshnichenko, Alexander Yu Meigal, Irina V Saenko, Liudmila I Gerasimova-Meigal, Liudmila A Chernikova, Natalia S Subbotina, Saara M Rissanen, Pasi A Karjalainen
Dry immersion (DI) is acknowledged as a reliable space flight analog condition. At DI, subject is immersed in water being wrapped in a waterproof film to imitate microgravity (μG). Microgravity is known to decrease muscle tone due to deprivation of the sensory stimuli that activate the reflexes that keep up the muscle tone. In contrary, parkinsonian patients are characterized by elevated muscle tone, or rigidity, along with rest tremor and akinesia. We hypothesized that DI can diminish the elevated muscle tone and/or the tremor in parkinsonian patients...
2018: Frontiers in Neuroscience
Masafumi Terada, Megan Beard, Sara Carey, Kate Pfile, Brian Pietrosimone, Elizabeth Rullestad, Heather Whitaker, Phillip Gribble
This study aimed to compare time-to-boundary and sample entropy during a single-leg balance task between individuals with chronic ankle instability (CAI), lateral ankle sprain copers, and healthy controls. Twenty-two participants with CAI, 20 lateral ankle sprain copers, and 24 healthy controls performed a single-leg balance task during an eyes-closed condition. Participants with CAI exhibited lower time-to-boundary values compared with lateral ankle sprain copers and healthy controls. However, we did not find differences in sample entropy variables between cohorts...
October 13, 2018: Motor Control
Bhawna Dhruv, Neetu Mittal, Megha Modi
Medical field has highly evolved with advancements in the technologies which prove to be beneficial for radiologists and patients for better diagnosis. The era of medical science provides best healthcare solutions with the help of medical images. Till now, 2D MRIs played a prominent role in early detection of disease but with latest technologies taking over the charge, 3D MRIs are highly effective and great in demand now-a-days. With the aid of advanced techniques such as edge detection, segmentation and texture analysis on these images the disease detection may become much easier...
October 12, 2018: International Journal of Neuroscience
Leonardo Wanderley Lopes, Vinícius Jefferson Dias Vieira, Silvana Luciene do Nascimento Cunha Costa, Suzete Élida Nóbrega Correia, Mara Behlau
The objective of this study was to analyze the accuracy of recurrence quantification measurements (RQMs) in discriminating between individuals with and without voice disorders. This study consisted of a total of 541 recorded voice samples from normal and dysphonic subjects. All subjects recorded a sustained vowel /Ɛ/ and underwent a laryngoscopic examination of the larynx. Twelve RQMs and three parameters related to the topology of the phonatory system were extracted from the samples, for a total of 15 measures...
October 5, 2018: Journal of Voice: Official Journal of the Voice Foundation
Elie Fiogbé, Verena Vassimon-Barroso, Aparecida Maria Catai, Ruth Caldeira de Melo, Robison José Quitério, Alberto Porta, Anielle Cristhine de Medeiros Takahashi
Fiogbé, E, Vassimon-Barroso, V, Catai, AM, de Melo, RC, Quitério, RJ, Porta, A, and Takahashi, ACdM. Complexity of knee extensor torque: effect of aging and contraction intensity. J Strength Cond Res XX(X): 000-000, 2018-Assessing the knee extensors' torque complexity in old adults is relevant because these muscles are among the most involved in functional daily activities. This study aimed to investigate the effects of aging and isometric contraction intensity on knee extensor torque complexity. Eight young (24 ± 2...
October 4, 2018: Journal of Strength and Conditioning Research
S Kauppinen, S S Karhula, J Thevenot, T Ylitalo, L Rieppo, I Kestilä, M Haapea, I Hadjab, M A Finnilä, E Quenneville, M Garon, H K Gahunia, K P H Pritzker, M D Buschmann, S Saarakkala, H J Nieminen
OBJECTIVE: Our aim is to establish methods for quantifying morphometric properties of calcified cartilage (CC) from micro-computed tomography (μCT). Furthermore, we evaluated the feasibility of these methods in investigating relationships between osteoarthritis (OA), tidemark surface morphology and open subchondral channels (OSCCs). METHOD: Samples (n = 15) used in this study were harvested from human lateral tibial plateau (n = 8). Conventional roughness and parameters assessing local 3-dimensional (3D) surface variations were used to quantify the surface morphology of the CC...
October 1, 2018: Osteoarthritis and Cartilage
Marjola Thanaj, Andrew J Chipperfield, Geraldine F Clough
OBJECTIVE: This study investigates the feasibility of the use of nonlinear complexity methods as a tool to identify altered microvascular function often associated with pathological conditions. We evaluate the efficacy of multiscale nonlinear complexity methods to account for the multiple time-scales of processes modulating microvascular network perfusion. METHODS: Microvascular blood flux (BF) and oxygenation (OXY: oxyHb, deoxyHb, totalHb and SO2 %) signals were recorded simultaneously at the same site, from the skin of 15 healthy young male volunteers using combined laser Doppler fluximetry (LDF) and white light spectroscopy...
September 26, 2018: Computers in Biology and Medicine
Hans Jonas Meyer, Leonard Leifels, Gordian Hamerla, Anne Kathrin Höhn, Alexey Surov
PURPOSE: To analyze associations between histogram analysis parameters derived from conventional magnetic resonance imaging (MRI) and different histopathological features in head and neck squamous cell carcinoma (HNSCC). PROCEDURES: Thirty-four patients with histologically proven primary HNSCC were prospectively acquired. Histogram analysis was derived from pre-contrast T1-weighted (T1w) and T2-weighted (T2w) images. In all cases, expression of HIF-1α, VEGF, EGFR, p53, Ki67, and p16 as well as tumor cell count was analyzed...
October 3, 2018: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
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