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Tahereh Kamali, Daniel Stashuk
OBJECTIVE: Robust and accurate segmentation of brain white matter (WM) fiber bundles assists in diagnosing and assessing progression or remission of neuropsychiatric diseases such as schizophrenia, autism and depression. Supervised segmentation methods are infeasible in most applications since generating gold standards is too costly. Hence, there is a growing interest in designing unsupervised methods. However, most conventional unsupervised methods require the number of clusters be known in advance which is not possible in most applications...
October 2016: Artificial Intelligence in Medicine
Ludovico Lami, Christoph Hirche, Gerardo Adesso, Andreas Winter
We derive fundamental constraints for the Schur complement of positive matrices, which provide an operator strengthening to recently established information inequalities for quantum covariance matrices, including strong subadditivity. This allows us to prove general results on the monogamy of entanglement and steering quantifiers in continuous variable systems with an arbitrary number of modes per party. A powerful hierarchical relation for correlation measures based on the log-determinant of covariance matrices is further established for all Gaussian states, which has no counterpart among quantities based on the conventional von Neumann entropy...
November 25, 2016: Physical Review Letters
Akira R Kinjo
The multiple sequence alignment (MSA) of a protein family provides a wealth of information in terms of the conservation pattern of amino acid residues not only at each alignment site but also between distant sites. In order to statistically model the MSA incorporating both short-range and long-range correlations as well as insertions, I have derived a lattice gas model of the MSA based on the principle of maximum entropy. The partition function, obtained by the transfer matrix method with a mean-field approximation, accounts for all possible alignments with all possible sequences...
2016: Biophysics and Physicobiology
Serghei Malkov, John A Shepherd, Christopher G Scott, Rulla M Tamimi, Lin Ma, Kimberly A Bertrand, Fergus Couch, Matthew R Jensen, Amir P Mahmoudzadeh, Bo Fan, Aaron Norman, Kathleen R Brandt, V Shane Pankratz, Celine M Vachon, Karla Kerlikowske
BACKGROUND: Several studies have shown that mammographic texture features are associated with breast cancer risk independent of the contribution of breast density. Thus, texture features may provide novel information for risk stratification. We examined the association of a set of established texture features with breast cancer risk by tumor type and estrogen receptor (ER) status, accounting for breast density. METHODS: This study combines five case-control studies including 1171 breast cancer cases and 1659 controls matched for age, date of mammogram, and study...
December 6, 2016: Breast Cancer Research: BCR
Natascia Giuliano, Maria Laura Annunziata, Francesca Giovanna Esposito, Salvatore Tagliaferri, Andrea Di Lieto, Giovanni Magenes, Maria Gabriella Signorini, Marta Campanile, Domenico Arduini
We selected 4012 cCTG records (one trace for each patient) performed in healthy pregnancies from 30th to 42nd gestational week using foetal heart rate (FHR), short-term variability (STV), long-term irregularity (LTI), Delta, approximate entropy (ApEn), spectral components as low frequency (LF), median frequency (MF), high frequency (HF) and LF/(HF + MF) ratio were analysed. Reference nomograms were created and sensitivity and specificity for the prediction of foetal compromise were calculated which were 90% and 89%, respectively...
December 6, 2016: Journal of Obstetrics and Gynaecology: the Journal of the Institute of Obstetrics and Gynaecology
Sheila López-Rosa, Moyocoyani Molina-Espíritu, Rodolfo O Esquivel, Catalina Soriano-Correa, Jésus S Dehesa
The relative structural location of a selected group of 27 sulfonamide-like molecules in a chemical space defined by three information theory quantities (Shannon entropy, Fisher information, and disequilibrium) is discussed. This group is composed of 15 active bacteriostatic molecules, 11 theoretically designed ones, and para-aminobenzoic acid. This endeavor allows molecules that share common chemical properties through the molecular backbone, but with significant differences in the identity of the chemical substituents, which might result in bacteriostatic activity, to be structurally classified and characterized...
December 5, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Clayton Stanley, Michael D Byrne
The growth of social media and user-created content on online sites provides unique opportunities to study models of human declarative memory. By framing the task of choosing a hashtag for a tweet and tagging a post on Stack Overflow as a declarative memory retrieval problem, 2 cognitively plausible declarative memory models were applied to millions of posts and tweets and evaluated on how accurately they predict a user's chosen tags. An ACT-R based Bayesian model and a random permutation vector-based model were tested on the large data sets...
December 2016: Psychological Methods
Guang Yang, Chongshi Gu, Tengfei Bao, Zhenming Cui, Kan Kan
Warning indicators of the dam body's temperature are required for the real-time monitoring of the service conditions of concrete dams to ensure safety and normal operations. Warnings theories are traditionally targeted at a single point which have limitations, and the scientific warning theories on global behavior of the temperature field are non-existent. In this paper, first, in 3D space, the behavior of temperature field has regional dissimilarity. Through the Ward spatial clustering method, the temperature field was divided into regions...
2016: SpringerPlus
Thierry Mora, Aleksandra M Walczak, Lorenzo Del Castello, Francesco Ginelli, Stefania Melillo, Leonardo Parisi, Massimiliano Viale, Andrea Cavagna, Irene Giardina
The correlated motion of flocks is an instance of global order emerging from local interactions. An essential difference with analogous ferromagnetic systems is that flocks are active: animals move relative to each other, dynamically rearranging their interaction network. The effect of this off-equilibrium element is well studied theoretically, but its impact on actual biological groups deserves more experimental attention. Here, we introduce a novel dynamical inference technique, based on the principle of maximum entropy, which accodomates network rearrangements and overcomes the problem of slow experimental sampling rates...
December 2016: Nature Physics
Samira Boroumand, Mansour Arab Chamjangali, Ghadamali Bagherian
A simple and sensitive double injection/single detector flow injection analysis (FIA) method is proposed for the simultaneous kinetic determination of ascorbic acid (AA) and uric acid (UA). This method is based upon the difference between the rates of the AA and UA reactions with Fe(3+) in the presence of 1, 10-phenanthroline (phen). The absorbance of Fe(2+)/1, 10-phenanthroline (Fe-phen) complex obtained as the product was measured spectrophotometrically at 510nm. To reach a good accuracy in the differential kinetic determination via the mathematical manipulations of the transient signals, different criteria were considered in the selection of the optimum conditions...
November 20, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Sachin Nayyar, Pawel Kuklik, Anand N Ganesan, Thomas R Sullivan, Lauren Wilson, Glenn D Young, Prashanthan Sanders, Kurt C Roberts-Thomson
BACKGROUND: In ventricular scar, impulse spread is slow because it traverses split and zigzag channels of surviving muscle. We aimed to evaluate scar electrograms to determine their local delay (activation time) and inequality in voltage splitting (entropy), and their relationship to channels. We reasoned that unlike innocuous channels, which are often short with multiple side branches, ventricular tachycardia (VT) supporting channels have very slow impulse spread and possess low entropy because of their longer protected length and relative lack of side-branching...
December 2016: Circulation. Arrhythmia and Electrophysiology
Zhenzhen Hu, Yonggang Wen, Jianfeng Wang, Meng Wang, Richang Hong, Shuicheng Yan
Age estimation based on the human face remains a significant problem in computer vision and pattern recognition. In order to estimate an accurate age or age group of a facial image, most of the existing algorithms require a huge face data set attached with age labels. This imposes a constraint on the utilization of the immensely unlabeled or weakly labeled training data, e.g. the huge amount of human photos in the social networks. These images may provide no age label, but it is easily to derive the age difference for an image pair of the same person...
December 1, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Shuangyan Liu, Jing Teng, Xianghua Qi, Shoushui Wei, Chengyu Liu
BACKGROUND: The usefulness of heart rate variability (HRV) in the clinical research has been verified in numerous studies. However, it is controversy that using pulse rate variability (PRV) as a surrogate of HRV in different clinical applications. OBJECTIVE: We aimed to investigate whether PRV extracted from finger pulse photoplethysmography (Pleth) signal could substitute HRV from ECG signal during different sleep stages by analyzing the common time-domain, frequency-domain and non-linear indices...
November 25, 2016: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
Can Wang, Jianxin Peng, Lijuan Song, Xiaowen Zhang
Obstructive sleep apnea hypopnea syndrome (OSAHS) is a serious respiratory disorder. Snoring is the most intuitively characteristic symptom of OSAHS. Recently, many studies have attempted to develop snore analysis technology for diagnosing OSAHS. The preliminary and essential step in such diagnosis is to automatically segment snoring sounds from original sleep sounds. This study presents an automatic snoring detection algorithm that detects potential snoring episodes using an adaptive effective-value threshold method, linear and nonlinear feature extraction using maximum power ratio, sum of positive/negative amplitudes, 500 Hz power ratio, spectral entropy (SE) and sample entropy (SampEn), and automatic snore/nonsnore classification using a support vector machine...
December 1, 2016: Australasian Physical & Engineering Sciences in Medicine
Rainer G Hanselmann, Cornelius Welter
Cells are open, highly ordered systems that are far away from equilibrium. For this reason, the first function of any cell is to prevent the permanent threat of disintegration that is described by thermodynamic laws and to preserve highly ordered cell characteristics such as structures, the cell cycle, or metabolism. In this context, three basic categories play a central role: energy, information, and matter. Each of these three categories is equally important to the cell and they are reciprocally dependent...
2016: Frontiers in Cell and Developmental Biology
Fan Xie, Shengxiang Gong, Wei Zhang, Jinhong Wu, Zhengwu Wang
In this study, we extracted lignin from Canna edulis ker residue. Its chemical structure, inhibitory activity on α-d-glucosidase, and kinetics as well as interaction mechanism were investigated by using spectrum analysis and docking simulation. The isolated lignin was composed by guaiacyl and syringal units, and exhibited stronger inhibition on α-d-glucosidase than acarbose with the half maximal inhibitory concentration at 5.3±0.3μM. It was a non-competitive inhibitior with Km and Ki values of 0.53±0.02mM and 0...
November 28, 2016: International Journal of Biological Macromolecules
N A Kuznetsov, O S Fedorova
The methodology of determination of the thermodynamic parameters of fast stages of recognition and cleavage of DNA substrates is described for the enzymatic processes catalyzed by DNA glycosylases Fpg and hOGG1 and AP endonuclease APE1 during base excision repair (BER) pathway. For this purpose, stopped-flow pre-steady-state kinetic analysis of tryptophan fluorescence intensity changes in proteins and fluorophores in DNA substrates was performed at various temperatures. This approach made it possible to determine the changes of standard Gibbs free energy, enthalpy, and entropy of sequential steps of DNA-substrate binding, as well as activation enthalpy and entropy for the transition complex formation of the catalytic stage...
October 2016: Biochemistry. Biokhimii︠a︡
Alicia Rae Welden, Alexander A Rusakov, Dominika Zgid
Including finite-temperature effects from the electronic degrees of freedom in electronic structure calculations of semiconductors and metals is desired; however, in practice it remains exceedingly difficult when using zero-temperature methods, since these methods require an explicit evaluation of multiple excited states in order to account for any finite-temperature effects. Using a Matsubara Green's function formalism remains a viable alternative, since in this formalism it is easier to include thermal effects and to connect the dynamic quantities such as the self-energy with static thermodynamic quantities such as the Helmholtz energy, entropy, and internal energy...
November 28, 2016: Journal of Chemical Physics
Caroline Desgranges, Jerome Delhommelle
Using the entropy S as a reaction coordinate, we determine the free energy barrier associated with the formation of a liquid droplet from a supersaturated vapor for atomic and molecular fluids. For this purpose, we develop the μVT-S simulation method that combines the advantages of the grand-canonical ensemble, that allows for a direct evaluation of the entropy, and of the umbrella sampling method, that is well suited to the study of an activated process like nucleation. Applying this approach to an atomic system such as Ar allows us to test the method...
November 28, 2016: Journal of Chemical Physics
Mark N Joswiak, Ryan Do, Michael F Doherty, Baron Peters
The surface free energy of a droplet is approximately γ(R)=γ(∞)(1-2δ/R), with R being the droplet radius and δ being the Tolman length. Here we use the mitosis method to compute δ=-0.56±0.1Å at 300 K for mW water, indicating that γ(R) increases as the droplet size decreases. The computed Tolman length agrees quite well with a previous study of TIP4P/2005 water. We also decompose the size-dependent surface free energy into energetic and entropic contributions for the mW and TIP4P/2005 force fields...
November 28, 2016: Journal of Chemical Physics
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