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https://www.readbyqxmd.com/read/28444388/apoe%C3%AE%C2%B54-genotype-and-hypertension-modify-8-year-cortical-thinning-five-occasion-evidence-from-the-seattle-longitudinal-study
#1
Philippe Rast, Kristen M Kennedy, Karen M Rodrigue, Paul R A W Robinson, Alden L Gross, Donald G McLaren, Tom Grabowski, K Warner Schaie, Sherry L Willis
We investigated individual differences in longitudinal trajectories of brain aging in cognitively normal healthy adults from the Seattle Longitudinal Study covering 8 years of longitudinal change (across 5 occasions) in cortical thickness in 249 midlife and older adults (52-95 years old). We aimed to understand true brain change; examine the influence of salient risk factors that modify an individual's rate of cortical thinning; and compare cross-sectional age-related differences in cortical thickness to longitudinal within-person cortical thinning...
April 21, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28431306/difference-optimization-automatic-correction-of-relative-frequency-and-phase-for-mean-non-edited-and-edited-gaba-1-h-mega-press-spectra
#2
Marianne Cleve, Martin Krämer, Alexander Gussew, Jürgen R Reichenbach
Phase and frequency corrections of magnetic resonance spectroscopic data are of major importance to obtain reliable and unambiguous metabolite estimates as validated in recent research for single-shot scans with the same spectral fingerprint. However, when using the J-difference editing technique (1)H MEGA-PRESS, misalignment between mean edited (ON‾) and non-edited (OFF‾) spectra that may remain even after correction of the corresponding individual single-shot scans results in subtraction artefacts compromising reliable GABA quantitation...
April 7, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28427188/consumption-of-fruits-and-vegetables-and-risk-of-renal-cell-carcinoma-a-meta-analysis-of-observational-studies
#3
Shaojing Zhang, Zhankui Jia, Zechen Yan, Jinjian Yang
BACKGROUND: There have been inconsistent results about the association between consumption of fruits and vegetables and renal cell carcinoma (RCC) risk. We conducted a meta-analysis of the published observational studies to explore this association. RESULTS: Nineteen observational studies (4 cohort, 1 pooled and 14 case-control studies), involving 10,215 subjects with RCC were part of this meta-analysis. The SRR for the highest vs. the lowest intake of vegetables was 0...
March 2, 2017: Oncotarget
https://www.readbyqxmd.com/read/28418055/application-of-machine-statistical-learning-artificial-intelligence-and-statistical-experimental-design-for-the-modeling-and-optimization-of-methylene-blue-and-cd-ii-removal-from-a-binary-aqueous-solution-by-natural-walnut-carbon
#4
H Mazaheri, M Ghaedi, M H Ahmadi Azqhandi, A Asfaram
Analytical chemists apply statistical methods for both the validation and prediction of proposed models. Methods are required that are adequate for finding the typical features of a dataset, such as nonlinearities and interactions. Boosted regression trees (BRTs), as an ensemble technique, are fundamentally different to other conventional techniques, with the aim to fit a single parsimonious model. In this work, BRT, artificial neural network (ANN) and response surface methodology (RSM) models have been used for the optimization and/or modeling of the stirring time (min), pH, adsorbent mass (mg) and concentrations of MB and Cd(2+) ions (mg L(-1)) in order to develop respective predictive equations for simulation of the efficiency of MB and Cd(2+) adsorption based on the experimental data set...
April 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28415265/comparative-statistics-of-selected-subgrid-scale-models-in-large-eddy-simulations-of-decaying-supersonic-magnetohydrodynamic-turbulence
#5
Philipp Grete, Dimitar G Vlaykov, Wolfram Schmidt, Dominik R G Schleicher
Large-eddy simulations (LES) are a powerful tool in understanding processes that are inaccessible by direct simulations due to their complexity, for example, in the highly turbulent regime. However, their accuracy and success depends on a proper subgrid-scale (SGS) model that accounts for the unresolved scales in the simulation. We evaluate the applicability of two traditional SGS models, namely the eddy-viscosity (EV) and the scale-similarity (SS) models, and one recently proposed nonlinear (NL) SGS model in the realm of compressible magnetohydrodynamic (MHD) turbulence...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28404988/laser-frequency-noise-in-coherent-optical-systems-spectral-regimes-and-impairments
#6
Aditya Kakkar, Jaime Rodrigo Navarro, Richard Schatz, Xiaodan Pang, Oskars Ozolins, Aleksejs Udalcovs, Hadrien Louchet, Sergei Popov, Gunnar Jacobsen
Coherent communication networks are based on the ability to use multiple dimensions of the lightwave together with electrical domain compensation of transmission impairments. Electrical-domain dispersion compensation (EDC) provides many advantages such as network flexibility and enhanced fiber nonlinearity tolerance, but makes the system more susceptible to laser frequency noise (FN), e.g. to the local oscillator FN in systems with post-reception EDC. Although this problem has been extensively studied, statistically, for links assuming lasers with white-FN, many questions remain unanswered...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28402369/structural-studies-of-the-bond-orientational-order-and-hexatic-smectic-transition-in-liquid-crystals-of-various-compositions
#7
I A Zaluzhnyy, R P Kurta, E A Sulyanova, O Yu Gorobtsov, A G Shabalin, A V Zozulya, A P Menushenkov, M Sprung, A Krówczyński, E Górecka, B I Ostrovskii, I A Vartanyants
We report on the X-ray studies of freely suspended hexatic films of three different liquid crystal compounds. By applying angular X-ray cross-correlation analysis (XCCA) to the measured diffraction patterns the parameters of the bond-orientational (BO) order in the hexatic phase were directly determined. The temperature evolution of the BO order parameters was analyzed on the basis of the multicritical scaling theory (MCST). Our results confirmed the validity of the MCST in the whole temperature range of the existence of the hexatic phase for all three compounds...
April 12, 2017: Soft Matter
https://www.readbyqxmd.com/read/28364740/noise-constrained-switching-times-for-heteroclinic-computing
#8
Fabio Schittler Neves, Maximilian Voit, Marc Timme
Heteroclinic computing offers a novel paradigm for universal computation by collective system dynamics. In such a paradigm, input signals are encoded as complex periodic orbits approaching specific sequences of saddle states. Without inputs, the relevant states together with the heteroclinic connections between them form a network of states-the heteroclinic network. Systems of pulse-coupled oscillators or spiking neurons naturally exhibit such heteroclinic networks of saddles, thereby providing a substrate for general analog computations...
March 2017: Chaos
https://www.readbyqxmd.com/read/28358674/embedding-based-on-function-approximation-for-large-scale-image-search
#9
Thanh-Toan Do, Ngai-Man Cheung
The objective of this paper is to design an embedding method that maps local features describing an image (e.g. SIFT) to a higher dimensional representation useful for the image retrieval problem. First, motivated by the relationship between the linear approximation of a nonlinear function in high dimensional space and the stateof- the-art feature representation used in image retrieval, i.e., VLAD, we propose a new approach for the approximation. The embedded vectors resulted by the function approximation process are then aggregated to form a single representation for image retrieval...
March 23, 2017: IEEE Transactions on Pattern Analysis and Machine Intelligence
https://www.readbyqxmd.com/read/28345879/vibrational-probes-from-small-molecule-solvatochromism-theory-and-experiments-to-applications-in-complex-systems
#10
Bartosz Błasiak, Casey H Londergan, Lauren J Webb, Minhaeng Cho
The vibrational frequency of a chosen normal mode is one of the most accurately measurable spectroscopic properties of molecules in condensed phases. Accordingly, infrared absorption and Raman scattering spectroscopy have provided valuable information on both distributions and ensemble-average values of molecular vibrational frequencies, and these frequencies are now routinely used to investigate structure, conformation, and even absolute configuration of chemical and biological molecules of interest. Recent advancements in coherent time-domain nonlinear vibrational spectroscopy have allowed the study of heterogeneous distributions of local structures and thermally driven ultrafast fluctuations of vibrational frequencies...
March 27, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28343123/estimation-of-red-light-running-frequency-using-high-resolution-traffic-and-signal-data
#11
Peng Chen, Guizhen Yu, Xinkai Wu, Yilong Ren, Yueguang Li
Red-light-running (RLR) emerges as a major cause that may lead to intersection-related crashes and endanger intersection safety. To reduce RLR violations, it's critical to identify the influential factors associated with RLR and estimate RLR frequency. Without resorting to video camera recordings, this study investigates this important issue by utilizing high-resolution traffic and signal event data collected from loop detectors at five intersections on Trunk Highway 55, Minneapolis, MN. First, a simple method is proposed to identify RLR by fully utilizing the information obtained from stop bar detectors, downstream entrance detectors and advance detectors...
March 23, 2017: Accident; Analysis and Prevention
https://www.readbyqxmd.com/read/28339277/turbulence-nonlinearities-shed-light-on-geometric-asymmetry-in-tokamak-confinement-transitions
#12
I Cziegler, A E Hubbard, J W Hughes, J L Terry, G R Tynan
A comprehensive study of fully frequency-resolved nonlinear kinetic energy transfer has been performed for the first time in a diverted tokamak, providing new insight into the parametric dependences of edge turbulence transitions. Measurements using gas puff imaging in the turbulent L-mode state illuminate the source of the long known but as yet unexplained "favorable-unfavorable" geometric asymmetry of the power threshold for transition to the turbulence-suppressed H mode. Results from the recently discovered I mode point to a competition between zonal flow (ZF) and geodesic-acoustic modes (GAM) for turbulent energy, while showing new evidence that the I-to-H transition is still dominated by ZFs...
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28323359/atomimetic-mechanical-structures-with-nonlinear-topological-domain-evolution-kinetics
#13
Michael J Frazier, Dennis M Kochmann
A mechanical metamaterial, a simple, periodic mechanical structure, is reported, which reproduces the nonlinear dynamic behavior of materials undergoing phase transitions and domain switching at the structural level. Tunable multistability is exploited to produce switching and transition phenomena whose kinetics are governed by the same Allen-Cahn law commonly used to describe material-level, structural-transition processes. The reported purely elastic mechanical system displays several key features commonly found in atomic- or mesoscale physics of solids...
March 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28318603/rupture-risk-in-abdominal-aortic-aneurysms-a-realistic-assessment-of-the-explicit-gpu-approach
#14
V Strbac, D M Pierce, B Rodriguez-Vila, J Vander Sloten, N Famaey
Accurate estimation of peak wall stress (PWS) is the crux of biomechanically motivated rupture risk assessment for abdominal aortic aneurysms aimed to improve clinical outcomes. Such assessments often use the finite element (FE) method to obtain PWS, albeit at a high computational cost, motivating simplifications in material or element formulations. These simplifications, while useful, come at a cost of reliability and accuracy. We achieve research-standard accuracy and maintain clinically applicable speeds by using novel computational technologies...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28298702/fixed-versus-mixed-rsa-%C3%A2-explaining-visual-representations-by-fixed-and-mixed-feature-sets-from-shallow-and-deep-computational-models
#15
Seyed-Mahdi Khaligh-Razavi, Linda Henriksson, Kendrick Kay, Nikolaus Kriegeskorte
Studies of the primate visual system have begun to test a wide range of complex computational object-vision models. Realistic models have many parameters, which in practice cannot be fitted using the limited amounts of brain-activity data typically available. Task performance optimization (e.g. using backpropagation to train neural networks) provides major constraints for fitting parameters and discovering nonlinear representational features appropriate for the task (e.g. object classification). Model representations can be compared to brain representations in terms of the representational dissimilarities they predict for an image set...
February 2017: Journal of Mathematical Psychology
https://www.readbyqxmd.com/read/28293137/nonlinear-information-fusion-algorithms-for-data-efficient-multi-fidelity-modelling
#16
P Perdikaris, M Raissi, A Damianou, N D Lawrence, G E Karniadakis
Multi-fidelity modelling enables accurate inference of quantities of interest by synergistically combining realizations of low-cost/low-fidelity models with a small set of high-fidelity observations. This is particularly effective when the low- and high-fidelity models exhibit strong correlations, and can lead to significant computational gains over approaches that solely rely on high-fidelity models. However, in many cases of practical interest, low-fidelity models can only be well correlated to their high-fidelity counterparts for a specific range of input parameters, and potentially return wrong trends and erroneous predictions if probed outside of their validity regime...
February 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28283354/effect-of-gradient-field-nonlinearity-distortions-in-mri-based-attenuation-maps-for-pet-reconstruction
#17
Josef A Lundman, Adam Johansson, Jörgen Olofsson, Jan Axelsson, Anne Larsson, Tufve Nyholm
PURPOSE: Attenuation correction is a requirement for quantification of the activity distribution in PET. The need to base attenuation correction on MRI instead of CT has arisen with the introduction of integrated PET/MRI systems. The aim was to describe the effect of residual gradient field nonlinearity distortions on PET attenuation correction. METHODS: MRI distortions caused by gradient field nonlinearity were simulated in CT images used for attenuation correction in PET reconstructions...
March 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28269502/brain-heart-linear-and-nonlinear-dynamics-during-visual-emotional-elicitation-in-healthy-subjects
#18
G Valenza, A Greco, C Gentili, A Lanata, N Toschi, R Barbieri, L Sebastiani, D Menicucci, A Gemignani, E P Scilingo
This study investigates brain-heart dynamics during visual emotional elicitation in healthy subjects through linear and nonlinear coupling measures of EEG spectrogram and instantaneous heart rate estimates. To this extent, affective pictures including different combinations of arousal and valence levels, gathered from the International Affective Picture System, were administered to twenty-two healthy subjects. Time-varying maps of cortical activation were obtained through EEG spectral analysis, whereas the associated instantaneous heartbeat dynamics was estimated using inhomogeneous point-process linear models...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28261328/label-free-data-standardization-for-clinical-metabolomics
#19
Petr G Lokhov, Dmitri L Maslov, Oleg N Kharibin, Elena E Balashova, Alexander I Archakov
BACKGROUND: In metabolomics, thousands of substances can be detected in a single assay. This capacity motivates the development of metabolomics testing, which is currently a very promising option for improving laboratory diagnostics. However, the simultaneous measurement of an enormous number of substances leads to metabolomics data often representing concentrations only in conditional units, while laboratory diagnostics generally require actual concentrations. To convert metabolomics data to actual concentrations, calibration curves need to be generated for each substance, and this process represents a significant challenge due to the number of substances that are present in the metabolomics data...
2017: BioData Mining
https://www.readbyqxmd.com/read/28261167/discovery-and-characterization-of-diazenylaryl-sulfonic-acids-as-inhibitors-of-viral-and-bacterial-neuraminidases
#20
Anja Hoffmann, Martina Richter, Susanne von Grafenstein, Elisabeth Walther, Zhongli Xu, Lilia Schumann, Ulrike Grienke, Christina E Mair, Christian Kramer, Judith M Rollinger, Klaus R Liedl, Michaela Schmidtke, Johannes Kirchmair
Viral neuraminidases are an established drug target to combat influenza. Severe complications observed in influenza patients are primarily caused by secondary infections with e.g., Streptococcus pneumoniae. These bacteria engage in a lethal synergism with influenza A viruses (IAVs) and also express neuraminidases. Therefore, inhibitors with dual activity on viral and bacterial neuraminidases are expected to be advantageous for the treatment of influenza infections. Here we report on the discovery and characterization of diazenylaryl sulfonic acids as dual inhibitors of viral and Streptococcus pneumoniae neuraminidase...
2017: Frontiers in Microbiology
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