keyword
MENU ▼
Read by QxMD icon Read
search

Monte Carlo simulation

keyword
https://www.readbyqxmd.com/read/28936989/diffusion-of-interstitials-in-metallic-systems-illustration-of-a-complex-study-case-aluminum
#1
Matthieu David, Damien Connetable
While diffusion mechanisms of interstitial elements in fcc systems are generally well-known, especially in the case of H atoms, we show in this work that even in the case of a simple metallic system (aluminum), the diffusion of interstitials exhibits a wide variety of paths and mechanisms that depend on the specie. We used an approach based on first-principles calculations associated with kinetic Monte-Carlo simulations and a multi-state diffusion formalism to compute the diffusion coefficients of five interstitial elements: hydrogen, boron, carbon, nitrogen and oxygen...
September 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28934616/a-model-based-bayesian-solution-for-characterization-of-complex-damage-scenarios-in-aerospace-composite-structures
#2
H Reed, Cara A C Leckey, A Dick, G Harvey, J Dobson
Ultrasonic damage detection and characterization is commonly used in nondestructive evaluation (NDE) of aerospace composite components. In recent years there has been an increased development of guided wave based methods. In real materials and structures, these dispersive waves result in complicated behavior in the presence of complex damage scenarios. Model-based characterization methods utilize accurate three dimensional finite element models (FEMs) of guided wave interaction with realistic damage scenarios to aid in defect identification and classification...
September 5, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28934548/controlling-styrene-maleic-acid-lipid-particles-through-raft
#3
Anton A A Smith, Henriette Elisabeth Autzen, Tomas Laursen, Vincent Wu, Max Yen, Aaron Hall, Scott D Hansen, Yifan Cheng, Ting Xu
The ability of styrene maleic acid copolymers to dissolve lipid membranes into nanosized lipid particles is a facile method of obtaining membrane proteins in solubilized lipid discs while conserving part of its native lipid environment. While the currently used copolymers can readily extract membrane proteins in native nanodiscs, their highly disperse composition is likely to influence the dispersity of the discs as well as the extraction efficiency. In this study, reversible addition fragmentation chain transfer was used to control the polymer architecture and dispersity of molecular weights with a high-precision...
September 21, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28934465/regulation-of-chromatin-folding-by-conformational-variations-of-nucleosome-linker-dna
#4
Jenna M Buckwalter, Davood Norouzi, Anna Harutyunyan, Victor B Zhurkin, Sergei A Grigoryev
Linker DNA conformational variability has been proposed to direct nucleosome array folding into more or less compact chromatin fibers but direct experimental evidence for such models are lacking. Here, we tested this hypothesis by designing nucleosome arrays with A-tracts at specific locations in the nucleosome linkers to induce inward (AT-IN) and outward (AT-OUT) bending of the linker DNA. Using electron microscopy and analytical centrifugation techniques, we observed spontaneous folding of AT-IN nucleosome arrays into highly compact structures, comparable to those induced by linker histone H1...
September 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28934254/deep-reconstruction-model-for-dynamic-pet-images
#5
Jianan Cui, Xin Liu, Yile Wang, Huafeng Liu
Accurate and robust tomographic reconstruction from dynamic positron emission tomography (PET) acquired data is a difficult problem. Conventional methods, such as the maximum likelihood expectation maximization (MLEM) algorithm for reconstructing the activity distribution-based on individual frames, may lead to inaccurate results due to the checkerboard effect and limitation of photon counts. In this paper, we propose a stacked sparse auto-encoder based reconstruction framework for dynamic PET imaging. The dynamic reconstruction problem is formulated in a deep learning representation, where the encoding layers extract the prototype features, such as edges, so that, in the decoding layers, the reconstructed results are obtained through a combination of those features...
2017: PloS One
https://www.readbyqxmd.com/read/28934005/risk-assessment-of-dietary-exposure-to-phytosterol-oxidation-products-from-baked-food-in-china
#6
Yinzhou Hu, Mengmeng Wang, Weisu Huang, Guoliang Yang, Tiantian Lou, Shiyun Lai, Baiyi Lu, Lufei Zheng
Phytosterols are nutritional phytochemicals that may undergo oxidation and be transformed into phytosterol oxidation products (POPs), thus inducing pathological and toxic effects. This work investigated 4 main phytosterols and 28 POPs in 104 kinds of commercial baked food by using gas chromatography-mass spectrometry. The dietary exposure and hazard index values (HI) associated with POPs from baked food consumption in China were estimated by using Monte Carlo simulation. Concentrations of the total phytosterols were between 3...
September 21, 2017: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
https://www.readbyqxmd.com/read/28933351/dosimetric-effects-of-polyethylene-glycol-surface-coatings-on-gold-nanoparticle-radiosensitization
#7
Brandon Koger, Charles Kirkby
One of the main appeals of using gold nanoparticles (GNPs) as radiosensitizers is that their surface coatings can be altered to manipulate their pharmacokinetic properties. However, Monte Carlo studies of GNP dosimetry tend to neglect these coatings, potentially changing the dosimetric results. This study quantifies the dosimetric effects of including a polyethylene glycol (PEG) surface coating on GNPs over both nanoscopic and microscopic ranges. Two dosimetric scales were explored using PENELOPE Monte Carlo simulations...
September 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28933200/infrared-extinction-performance-of-randomly-oriented-microbial-clustered-agglomerate-materials
#8
Le Li, Yihua Hu, Youlin Gu, Xinying Zhao, Shilong Xu, Lei Yu, Zhi Ming Zheng, Peng Wang
In this study, the spatial structure of randomly distributed clusters of fungi An0429 spores was simulated using a cluster aggregation (CCA) model, and the single scattering parameters of fungi An0429 spores were calculated using the discrete dipole approximation (DDA) method. The transmittance of 10.6 µm infrared (IR) light in the aggregated fungi An0429 spores swarm is simulated by using the Monte Carlo method. Several parameters that affect the transmittance of 10.6 µm IR light, such as the number and radius of original fungi An0429 spores, porosity of aggregated fungi An0429 spores, and density of aggregated fungi An0429 spores of the formation aerosol area were discussed...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28931873/characterization-of-methane-excess-and-absolute-adsorption-in-various-clay-nanopores-from-molecular-simulation
#9
Yuanyuan Tian, Changhui Yan, Zhehui Jin
In this work, we use grand canonical Monte Carlo (GCMC) simulation to study methane adsorption in various clay nanopores and analyze different approaches to characterize the absolute adsorption. As an important constituent of shale, clay minerals can have significant amount of nanopores, which greatly contribute to the gas-in-place in shale. In previous works, absolute adsorption is often calculated from the excess adsorption and bulk liquid phase density of absorbate. We find that methane adsorbed phase density keeps increasing with pressure up to 80 MPa...
September 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28931691/vertical-transmission-of-hepatitis-c-virus-variable-transmission-bottleneck-and-evidence-of-mid-gestation-in-utero-infection
#10
Sébastien Fauteux-Daniel, Ariane Larouche, Virginie Calderon, Jonathan Boulais, Chanel Béland, Doris G Ransy, Marc Boucher, Valérie Lamarre, Normand Lapointe, Isabelle Boucoiran, Armelle Le Campion, Hugo Soudeyns
Hepatitis C virus (HCV) can be transmitted from mother to child during pregnancy and childbirth. However, the timing and precise biologic mechanisms that are involved in this process are incompletely understood, as are the determinants that influence transmission of particular HCV variants. Here we report results of a longitudinal assessment of HCV quasispecies diversity and composition in 5 cases of vertical HCV transmission, including 3 women coinfected with HIV-1. The population structure of HCV variant spectra based on E2 envelope gene sequences (nucleotide positions 1491-1787), including hypervariable regions 1 and 2, was characterized using next-generation sequencing and median joining network analysis...
September 20, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28930158/a-method-for-medical-diagnosis-based-on-optical-fluence-rate-distribution-at-tissue-surface
#11
Omnia Hamdy, Jala El-Azab, Tarek A Al-Saeed, Mahmoud F Hassan, Nahed H Solouma
Optical differentiation is a promising tool in biomedical diagnosis mainly because of its safety. The optical parameters' values of biological tissues differ according to the histopathology of the tissue and hence could be used for differentiation. The optical fluence rate distribution on tissue boundaries depends on the optical parameters. So, providing image displays of such distributions can provide a visual means of biomedical diagnosis. In this work, an experimental setup was implemented to measure the spatially-resolved steady state diffuse reflectance and transmittance of native and coagulated chicken liver and native and boiled breast chicken skin at 635 and 808 nm wavelengths laser irradiation...
September 20, 2017: Materials
https://www.readbyqxmd.com/read/28929501/accommodating-the-ecological-fallacy-in-disease-mapping-in-the-absence-of-individual-exposures
#12
Feifei Wang, Jian Wang, Alan Gelfand, Fan Li
In health exposure modeling, in particular, disease mapping, the ecological fallacy arises because the relationship between aggregated disease incidence on areal units and average exposure on those units differs from the relationship between the event of individual incidence and the associated individual exposure. This article presents a novel modeling approach to address the ecological fallacy in the least informative data setting. We assume the known population at risk with an observed incidence for a collection of areal units and, separately, environmental exposure recorded during the period of incidence at a collection of monitoring stations...
September 19, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28928795/sensitivity-analysis-of-the-integral-quality-monitoring-system%C3%A2-using-monte-carlo-simulation
#13
Oluwaseyi M Oderinde, F C P du Plessis
The Integral Quality Monitoring (IQM) System is a real-time beam output verifying system that validates the integrity and accuracy of patient treatment plan (TP) data during radiation treatment. The purpose of this study was to evaluate the sensitivity of the IQM to errors in segment using EGSnrc/BEAMnrc Monte Carlo (MC) codes. Sensitivity analysis (SA) techniques were applied to study the significance of small alterations of field sizes (segments) on the IQM signal response. One hundred and eighty multileaf segments were analyzed with methods that include scatter plots (SP), brute force, variance-based (VAR), and standard regression coefficient SA...
2017: Computational and Mathematical Methods in Medicine
https://www.readbyqxmd.com/read/28928691/class-enumeration-and-parameter-recovery-of-growth-mixture-modeling-and-second-order-growth-mixture-modeling-in-the-presence-of-measurement-noninvariance-between-latent-classes
#14
Eun Sook Kim, Yan Wang
Population heterogeneity in growth trajectories can be detected with growth mixture modeling (GMM). It is common that researchers compute composite scores of repeated measures and use them as multiple indicators of growth factors (baseline performance and growth) assuming measurement invariance between latent classes. Considering that the assumption of measurement invariance does not always hold, we investigate the impact of measurement noninvariance on class enumeration and parameter recovery in GMM through a Monte Carlo simulation study (Study 1)...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28927668/societal-costs-in-displaced-transverse-olecranon-fractures-using-decision-analysis-tools-to-find-the-most-cost-effective-strategy-between-tension-band-wiring-and-locked-plating
#15
Tittu Francis, Travis Washington, Karan Srivastava, Vasilios Moutzouros, Eric C Makhni, William Hakeos
BACKGROUND: Tension band wiring (TBW) and locked plating are common treatment options for Mayo IIA olecranon fractures. Clinical trials have shown excellent functional outcomes with both techniques. Although TBW implants are significantly less expensive than a locked olecranon plate, TBW often requires an additional operation for implant removal. To choose the most cost-effective treatment strategy, surgeons must understand how implant costs and return to the operating room influence the most cost-effective strategy...
September 15, 2017: Journal of Shoulder and Elbow Surgery
https://www.readbyqxmd.com/read/28926766/protonation-of-%C3%AE-lactoglobulin-in-the-presence-of-strong-polyelectrolyte-chains-a-study-using-monte-carlo-simulation
#16
Paola Torres, Luciano Bojanich, Fabricio Sanchez-Varretti, Antonio Jose Ramirez-Pastor, Evelina Quiroga, Valeria Boeris, Claudio F Narambuena
In this work, the molecular interaction between the protein β-lactoglobulin and strong polyelectrolyte chains was studied using Monte Carlo simulations. Different coarse-grained models were used to represent the system components. Both net charge and protonation of the isolated dimeric protein were analyzed as a function of pH. The acid-base equilibrium of each titratable group was distinctively modified by the presence of polyanion or polycation chains. The complexation on the wrong side of pI was more evident with the polycation than with the polyanion...
September 8, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28926734/a-quality-by-design-based-approach-to-a-capillary-electrokinetic-assay-for-the-determination-of-dextromepromazine-and-levomepromazine-sulfoxide-as-impurities-of-levomepromazine
#17
Stephan Niedermeier, Gerhard K E Scriba
Using a quality by design approach, a capillary electrophoresis method for the simultaneous determination of dextromepromazine and the oxidation product levomepromazine sulfoxide in levomepromazine was developed. The analytical target profile was defined that the method should be able to quantify 0.1% of both impurities with a precision of  ≤10%. Hydroxypropyl-γ-cyclodextrin was used as chiral selector. The critical process parameters cyclodextrin concentration, buffer pH and concentration as well as temperature and applied voltage were studied using a fractional factorial resolution V+ design for defining the knowledge space...
September 8, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28926253/understanding-the-role-of-dna-topology-in-target-search-dynamics-of-proteins
#18
Anupam Mondal, Arnab Bhattacherjee
A wide range of cellular processes initiates upon recognising and binding of proteins to specific DNA sites. Typically, the recognition process is incredibly fast owing to a complex mechanism that combines different 3D and 1D modes of translocation of the protein. While few studies performed on selected DNA topologies suggested that the DNA topology might alter the balance between these two modes and therefore the target search kinetics, its detail role in target search mechanism remains unclear. Here, we present a discrete-state stochastic approach that allows us to incorporate the topological information of DNA molecule explicitly and predict its role during the process when proteins search for their specific binding sites on DNA...
September 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28925682/role-of-proton-diffusion-in-the-nonexponential-kinetics-of-proton-coupled-electron-transfer-from-photoreduced-zno-nanocrystals
#19
Soumya Ghosh, Alexander V Soudackov, Sharon Hammes-Schiffer
Experiments have suggested that photoreduced ZnO nanocrystals transfer an electron and a proton to organic radicals through a concerted proton-coupled electron transfer (PCET) mechanism. The kinetics of this process was studied by monitoring the decay of the absorbance that reflects the concentration of electrons in the conduction bands of the nanocrystals. Interestingly, this absorbance exhibited nonexponential decay kinetics that could not be explained by heterogeneities of the nanoparticles or electron content...
September 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28925088/comparison-of-a-quantum-random-number-generator-with-pseudorandom-number-generators-for-their-use-in-molecular-monte-carlo-simulations
#20
Dario Ghersi, Abhishek Parakh, Mihaly Mezei
Four pseudorandom number generators were compared with a physical, quantum-based random number generator using the NIST suite of statistical tests, which only the quantum-based random number generator could successfully pass. We then measured the effect of the five random number generators on various calculated properties in different Markov-chain Monte Carlo simulations. Two types of systems were tested: conformational sampling of a small molecule in aqueous solution and liquid methanol under constant temperature and pressure...
September 18, 2017: Journal of Computational Chemistry
keyword
keyword
70738
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"