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https://www.readbyqxmd.com/read/29223077/multiple-linear-regression-based-congener-profile-correlation-to-estimate-the-toxicity-teq-and-dioxin-concentration-in-atmospheric-emissions
#1
D Palmer, J O Pou, L Gonzalez-Sabaté, J Díaz-Ferrero
The formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) is governed by complex chemical reactions with complex kinetic models. The simulation of Municipal Solid Waste incinerators, or other industrial thermal processes, is a powerful tool that can be used to optimize and control them, and reducing the number of components to simulate is mandatory for a proper use. In this study it has been determined that only the formation of 3 of the 17 main PCDD/F congeners can be considered as linearly independent...
December 6, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29221892/coevolution-of-nonlinear-group-interactions-and-strategies-in-well-mixed-and-structured-populations
#2
Lei Zhou, Aming Li, Long Wang
In microbial populations and human societies, the rule of nonlinear group interactions strongly affects the intraspecific evolutionary dynamics, which leads to the variation of the strategy composition eventually. The consequence of such variation may retroact to the rule of the interactions. This correlation indicates that the rule of nonlinear group interactions may coevolve with individuals' strategies. Here, we develop a model to investigate such coevolution in both well-mixed and structured populations...
December 5, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/29221857/review-of-simulation-training-in-interventional-radiology
#3
REVIEW
Souzan Mirza, Sriharsha Athreya
Simulation training has evolved and is now able to offer numerous training opportunities to supplement the practice of and overcome some of the shortcomings of the traditional Master-Apprentice model currently used in medical training. Simulation training provides new opportunities to practice skills used in clinical procedures, crisis management scenarios, and everyday clinical practice in a risk-free environment. Procedural and nonprocedural skills used in interventional radiology can be taught with the use of simulation devices and technologies...
December 5, 2017: Academic Radiology
https://www.readbyqxmd.com/read/29221408/exploring-a-multi-scale-method-for-molecular-simulation-in-continuum-solvent-model-explicit-simulation-of-continuum-solvent-as-an-incompressible-fluid
#4
Li Xiao, Ray Luo
We explored a multi-scale algorithm for the Poisson-Boltzmann continuum solvent model for more robust simulations of biomolecules. In this method, the continuum solvent/solute interface is explicitly simulated with a numerical fluid dynamics procedure, which is tightly coupled to the solute molecular dynamics simulation. There are multiple benefits to adopt such a strategy as presented below. At this stage of the development, only nonelectrostatic interactions, i.e., van der Waals and hydrophobic interactions, are included in the algorithm to assess the quality of the solvent-solute interface generated by the new method...
December 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29221393/equation-of-state-and-helmholtz-free-energy-for-the-atomic-system-of-the-repulsive-lennard-jones-particles
#5
Ali Mirzaeinia, Farzaneh Feyzi, Seyed Majid Hashemianzadeh
Simple and accurate expressions are presented for the equation of state (EOS) and absolute Helmholtz free energy of a system composed of simple atomic particles interacting through the repulsive Lennard-Jones potential model in the fluid and solid phases. The introduced EOS has 17 and 22 coefficients for fluid and solid phases, respectively, which are regressed to the Monte Carlo (MC) simulation data over the reduced temperature range of 0.6≤T*≤6.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. The average absolute relative percent deviation in fitting the EOS parameters to the MC data is 0...
December 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29220777/scenario-modelling-of-land-use-land-cover-changes-in-munessa-shashemene-landscape-of-the-ethiopian-highlands
#6
Mengistie Kindu, Thomas Schneider, Martin Döllerer, Demel Teketay, Thomas Knoke
Models under a set of scenarios are used to simulate and improve our understanding of land use/land cover (LULC) changes, which is central for sustainable management of a given natural resource. In this study, we simulated and examined the possible future LULC patterns and changes in Munessa-Shashemene landscape of the Ethiopian highlands covering four decades (2012-2050) using a spatially explicit GIS-based model. Both primary and secondary sources were utilized to identify relevant explanatory variables (drivers) and LULC datasets for the model...
December 5, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29220761/climate-change-potential-effects-on-the-hydrological-regime-of-freshwater-springs-in-the-italian-northern-apennines
#7
Federico Cervi, Francesca Petronici, Attilio Castellarin, Marco Marcaccio, Andrea Bertolini, Lisa Borgatti
In large areas of the Italian Northern Apennines, hundreds of low-yield springs provide water for drinking and industrial purposes, with short groundwater flow paths being formed within fractured sedimentary rock units. This hydrogeological setting results in spring water discharges that closely follow meteoric water recharge patterns, leading to low-flow periods concentrated in the summer/early autumn. Therefore, the springs' outflow can be very sensitive to a shortage in water recharge, as it was the case in 2003 and 2017, when a prolonged period of drought caused severe water management issues...
December 5, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29220728/assessment-of-long-term-exposure-to-airborne-dioxin-and-cadmium-concentrations-in-the-lyon-metropolitan-area-france
#8
T Coudon, H Hourani, C Nguyen, E Faure, F R Mancini, B Fervers, P Salizzoni
Identifying the long-term effects of airborne pollutants requires the computation of the spatial and temporal variability of their concentration in air to estimate the exposure of the population. To estimate exposure levels of individuals in a breast cancer case control study nested in a national prospective cohort, we determine here the differential impact of a variety of cadmium and dioxin sources on urban air over a large urban area and over a period of almost 20years. To that end, we couple an emission model, to estimate dioxin and cadmium atmospheric annual releases, with an urban dispersion model in order to compute pollutant concentration fields at a fine temporal (1h) and spatial (25m) resolution...
December 5, 2017: Environment International
https://www.readbyqxmd.com/read/29220351/driver-fatigue-detection-through-multiple-entropy-fusion-analysis-in-an-eeg-based-system
#9
Jianliang Min, Ping Wang, Jianfeng Hu
Driver fatigue is an important contributor to road accidents, and fatigue detection has major implications for transportation safety. The aim of this research is to analyze the multiple entropy fusion method and evaluate several channel regions to effectively detect a driver's fatigue state based on electroencephalogram (EEG) records. First, we fused multiple entropies, i.e., spectral entropy, approximate entropy, sample entropy and fuzzy entropy, as features compared with autoregressive (AR) modeling by four classifiers...
2017: PloS One
https://www.readbyqxmd.com/read/29218940/-studying-on-purification-technology-of-resina-draconis-phenol-extracts-based-on-design-space-method
#10
Jian Zhang, Xin Zhang, Yu-An Bi, Gui-Hong Xu, Wen-Zhe Huang, Zhen-Zhong Wang, Wei Xiao
The "design space" method was used to optimize the purification process of Resina Draconis phenol extracts by using the concept of "quality derived from design" (QbD). The content and transfer rate of laurin B and 7,4'-dihydroxyflavone and yield of extract were selected as the critical quality attributes (CQA). Plackett-Burman design showed that the critical process parameters (CPP) were concentration of alkali, the amount of alkali and the temperature of alkali dissolution. Then the Box-Behnken design was used to establish the mathematical model between CQA and CPP...
September 2017: Zhongguo Zhong Yao za Zhi, Zhongguo Zhongyao Zazhi, China Journal of Chinese Materia Medica
https://www.readbyqxmd.com/read/29218908/analyzing-metabolomics-data-for-association-with-genotypes-using-two-component-gaussian-mixture-distributions
#11
Jason Westra, Nicholas Hartman, Bethany Lake, Gregory Shearer, Nathan Tintle
Standard approaches to evaluate the impact of single nucleotide polymorphisms (SNP) on quantitative phenotypes use linear models. However, these normal-based approaches may not optimally model phenotypes which are better represented by Gaussian mixture distributions (e.g., some metabolomics data). We develop a likelihood ratio test on the mixing proportions of two-component Gaussian mixture distributions and consider more restrictive models to increase power in light of a priori biological knowledge. Data were simulated to validate the improved power of the likelihood ratio test and the restricted likelihood ratio test over a linear model and a log transformed linear model...
2018: Pacific Symposium on Biocomputing
https://www.readbyqxmd.com/read/29218591/model-based-phenotypic-signatures-governing-the-dynamics-of-the-stem-and-semi-differentiated-cell-populations-in-dysplastic-colonic-crypts
#12
Svetoslav Nikolov, Guido Santos, Olaf Wolkenhauer, Julio Vera
Mathematical modeling of cell differentiated in colonic crypts can contribute to a better understanding of basic mechanisms underlying colonic tissue organization, but also its deregulation during carcinogenesis and tumor progression. Here, we combined bifurcation analysis to assess the effect that time delay has in the complex interplay of stem cells and semi-differentiated cells at the niche of colonic crypts, and systematic model perturbation and simulation to find model-based phenotypes linked to cancer progression...
December 7, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/29217474/effect-of-particle-size-polydispersity-and-polymer-degradation-on-progesterone-release-from-plga-microparticles-experimental-and-mathematical-modeling
#13
Carlos Busatto, Juan Pesoa, Ignacio Helbling, Julio Luna, Diana Estenoz
Poly(lactic-co-glycolic acid) (PLGA) microparticles containing progesterone were prepared by the solvent extraction/evaporation and microfluidic techniques. Microparticles were characterized by their size distribution, encapsulation efficiency, morphology and thermal properties. The effect of particle size, polydispersity and polymer degradation on the in vitro release of the hormone was studied. A triphasic release profile was observed for larger microparticles, while smaller microspheres showed a biphasic release profile...
December 4, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/29216252/global-computational-mutagenesis-provides-a-critical-stability-framework-in-protein-structures
#14
Caitlyn L McCafferty, Yuri V Sergeev
A protein's amino acid sequence dictates the folds and final structure the macromolecule will form. We propose that by identifying critical residues in a protein's atomic structure, we can select a critical stability framework within the protein structure essential to proper protein folding. We use global computational mutagenesis based on the unfolding mutation screen to test the effect of every possible missense mutation on the protein structure to identify the residues that cannot tolerate a substitution without causing protein misfolding...
2017: PloS One
https://www.readbyqxmd.com/read/29216231/a-computational-model-to-investigate-the-effect-of-pennation-angle-on-surface-electromyogram-of-tibialis-anterior
#15
Diptasree Maitra Ghosh, Dinesh Kumar, Sridhar Poosapadi Arjunan, Ariba Siddiqi, Ramakrishnan Swaminathan
This study has described and experimentally validated the differential electrodes surface electromyography (sEMG) model for tibialis anterior muscles during isometric contraction. This model has investigated the effect of pennation angle on the simulated sEMG signal. The results show that there is no significant effect of pennation angle in the range 0° to 20° to the single fibre action potential shape recorded on the skin surface. However, the changes with respect to pennation angle are observed in sEMG amplitude, frequency and fractal dimension...
2017: PloS One
https://www.readbyqxmd.com/read/29216215/accelerating-cross-validation-with-total-variation-and-its-application-to-super-resolution-imaging
#16
Tomoyuki Obuchi, Shiro Ikeda, Kazunori Akiyama, Yoshiyuki Kabashima
We develop an approximation formula for the cross-validation error (CVE) of a sparse linear regression penalized by ℓ1-norm and total variation terms, which is based on a perturbative expansion utilizing the largeness of both the data dimensionality and the model. The developed formula allows us to reduce the necessary computational cost of the CVE evaluation significantly. The practicality of the formula is tested through application to simulated black-hole image reconstruction on the event-horizon scale with super resolution...
2017: PloS One
https://www.readbyqxmd.com/read/29216113/scaled-model-guidelines-for-solar-coronagraphs-external-occulters-with-an-optimized-shape
#17
Federico Landini, Cristian Baccani, Hagen Schweitzer, Daniel Asoubar, Marco Romoli, Matteo Taccola, Mauro Focardi, Maurizio Pancrazzi, Silvano Fineschi
One of the major challenges faced by externally occulted solar coronagraphs is the suppression of the light diffracted by the occulter edge. It is a contribution to the stray light that overwhelms the coronal signal on the focal plane and must be reduced by modifying the geometrical shape of the occulter. There is a rich literature, mostly experimental, on the appropriate choice of the most suitable shape. The problem arises when huge coronagraphs, such as those in formation flight, shall be tested in a laboratory...
December 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/29216099/analysis-of-weighted-subspace-fitting-and-subspace-based-eigenvector-techniques-for-frequency-estimation-for-the-coherent-doppler-lidar
#18
Yanwei Wu, Pan Guo, Siying Chen, He Chen, Yinchao Zhang, Xunbao Rui
Since the periodogram maximum (PM) algorithm fails to provide consistent estimates, more robust techniques are developed, especially in a low signal-to-noise ratio (SNR) regime. The methods are formulated in a subspace fitting-based framework, such as the eigenvector (EV) method and the proposed weighted subspace fitting (WSF) method by introducing an optimal weighting matrix, which exploits the low-rank properties of the covariance matrix of the coherent Doppler lidar echo data. Simulation results reveal that the number of the reliable estimates by the WSF method is more than the other two methods, and the standard deviation is the smallest...
November 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29216084/reduction-of-the-effects-of-angle-errors-for-a-channeled-spectropolarimeter
#19
Xueping Ju, Bin Yang, Junqiang Zhang, Changxiang Yan
Angle errors of high-order retarders will decrease the accuracy of a channeled spectropolarimeter. This paper presents an easily implemented and widely applicable method for reducing the effects of the angle errors. First, we theoretically derive a modified reconstruction model to express and analyze the effects of the angle errors. Based on the modified reconstruction model and current reference beam calibration technique, we put forward the modified reference beam calibration technique to reduce the effects of the angle errors...
November 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29216048/deformation-of-a-prestressed-liquid-lens-membrane
#20
Petr Pokorný, Filip Šmejkal, Pavel Kulmon, Pavel Novák, Jiří Novák, Antonín Mikš, Martin Horák, Milan Jirásek
This paper presents a complete model for analysis of the deformed shape of a prestressed circular axisymmetric membrane of a liquid lens. The governing equations are derived using the exact relation between displacements and the Green-Lagrange strains combined with the Saint Venant-Kirchhoff material law, which postulates a linear relation between the Green-Lagrange strains and the second Piola-Kirchoff stresses. A numerical solution based on minimization of potential energy is illustrated by an example, and the dependence of the maximum membrane deflection on material properties and initial prestress is analyzed...
December 1, 2017: Applied Optics
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