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"Validation" simulation model

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https://www.readbyqxmd.com/read/29045491/monte-carlo-simulation-of-secondary-neutron-dose-for-scanning-proton-therapy-using-fluka
#1
Chaeyeong Lee, Sangmin Lee, Seung-Jae Lee, Hankyeol Song, Dae-Hyun Kim, Sungkoo Cho, Kwanghyun Jo, Youngyih Han, Yong Hyun Chung, Jin Sung Kim
Proton therapy is a rapidly progressing field for cancer treatment. Globally, many proton therapy facilities are being commissioned or under construction. Secondary neutrons are an important issue during the commissioning process of a proton therapy facility. The purpose of this study is to model and validate scanning nozzles of proton therapy at Samsung Medical Center (SMC) by Monte Carlo simulation for beam commissioning. After the commissioning, a secondary neutron ambient dose from proton scanning nozzle (Gantry 1) was simulated and measured...
2017: PloS One
https://www.readbyqxmd.com/read/29043794/dynamic-transition-from-%C3%AE-helices-to-%C3%AE-sheets-in-polypeptide-coiled-coil-motifs
#2
Kirill A Minin, Artem Zhmurov, Kenneth A Marx, Prashant K Purohit, Valeri Barsegov
We carried out dynamic force manipulations in silico on a variety of coiled-coil protein fragments from myosin, chemotaxis receptor, vimentin, fibrin, and phenylalanine zippers that vary in size and topology of their α-helical packing. When stretched along the superhelical axis, all superhelices show elastic, plastic, and inelastic elongation regimes, and undergo a dynamic transition from the α-helices to the β-sheets, which marks the onset of plastic deformation. Using Abeyaratne-Knowles formulation of phase transitions, we developed a new theoretical methodology to model mechanical and kinetic properties of protein coiled-coils under mechanical non-equilibrium conditions and to map out their energy landscapes...
October 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29043776/art-advancing-science-filmmaking-leads-to-molecular-insights-at-the-nanoscale
#3
Charles Reilly, Donald E Ingber
Many have recognized the potential value of facilitating activities that span the art-science interface for the benefit of society; however, there are few examples that demonstrate how pursuit of an artistic agenda can lead to scientific insights. Here, we describe how we set out to produce an entertaining short film depicting the fertilization of the egg by sperm as a parody of a preview for another Star Wars movie to excite the public about science, but ended up developing a simulation tool for multiscale modeling...
October 18, 2017: ACS Nano
https://www.readbyqxmd.com/read/29042467/variability-in-heart-to-mediastinum-ratio-from-planar-123-i-mibg-images-of-a-thorax-phantom-for-6-common-gamma-camera-models
#4
Rikard Owenius, Michelle Zanette, Patrick Cella
A heart-to-mediastinum (H/M) ratio ≥1.6 on planar Iobenguane (123)I ((123)I-mIBG; AdreView) images identifies heart failure patients at low risk of experiencing an adverse cardiac event. This phase 4 study used standardized phantoms to assess the inter-camera, intra-camera, and inter-head variability in H/M ratio determinations from planar cardiac (123)I-mIBG imaging using commercially-available, dual-head gamma cameras. Methods: A fillable thorax phantom was developed to simulate the typical uptake of (123)I-mIBG...
October 17, 2017: Journal of Nuclear Medicine Technology
https://www.readbyqxmd.com/read/29042149/egsnrc-calculation-of-activity-calibration-factors-for-the-vinten-ionization-chamber
#5
R Townson, F Tessier, R Galea
The National Physical Laboratory Vinten 671 chamber was selected as a proving ground for a new radionuclide source model in the EGSnrc software. The computational Vinten model is validated against measurements of radionuclide artifacts whose activities were determined by absolute methods. The response of the Vinten chamber is first calculated as a function of gamma energy, but more strikingly, an explicit simulation of radionuclide decay was implemented and now permits the direct determination of a calibration factor, including additional effects due to all decay paths of the radionuclide...
October 6, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29041720/robust-and-efficient-multi-frequency-temporal-phase-unwrapping-optimal-fringe-frequency-and-pattern-sequence-selection
#6
Minliang Zhang, Qian Chen, Tianyang Tao, Shijie Feng, Yan Hu, Hui Li, Chao Zuo
Temporal phase unwrapping (TPU) is an essential algorithm in fringe projection profilometry (FPP), especially when measuring complex objects with discontinuities and isolated surfaces. Among others, the multi-frequency TPU has been proven to be the most reliable algorithm in the presence of noise. For a practical FPP system, in order to achieve an accurate, efficient, and reliable measurement, one needs to make wise choices about three key experimental parameters: the highest fringe frequency, the phase-shifting steps, and the fringe pattern sequence...
August 21, 2017: Optics Express
https://www.readbyqxmd.com/read/29041602/virtual-ellipsometry-on-layered-micro-facet-surfaces
#7
Chi Wang, Alexander Wilkie, Petr Harcuba, Lukas Novosad
Microfacet-based BRDF models are a common tool to describe light scattering from glossy surfaces. Apart from their wide-ranging applications in optics, such models also play a significant role in computer graphics for photorealistic rendering purposes. In this paper, we mainly investigate the computer graphics aspect of this technology, and present a polarisation-aware brute force simulation of light interaction with both single and multiple layered micro-facet surfaces. Such surface models are commonly used in computer graphics, but the resulting BRDF is ultimately often only approximated...
September 18, 2017: Optics Express
https://www.readbyqxmd.com/read/29041578/fluid-jet-array-parallel-machining-of-optical-microstructure-array-surfaces
#8
Chunjin Wang, Chi Fai Cheung, Mingyu Liu, Wing Bun Lee
Optical microstructure array surfaces such as micro-lens array surface, micro-groove array surface etc., are being used in more and more optical products, depending on its ability to produce a unique or particular performance. The geometrical complexity of the optical microstructures array surfaces makes them difficult to be fabricated. In this paper, a novel method named fluid jet-array parallel machining (FJAPM) is proposed to provide a new way to generate the microstructure array surfaces with high productivity...
September 18, 2017: Optics Express
https://www.readbyqxmd.com/read/29041501/measurement-of-spectacle-lenses-using-wavefront-aberration-in-real-view-condition
#9
Zhigang Jia, Kai Xu, Fengzhou Fang
A wavefront aberration analysis method for measuring spectacle lenses in real-view condition is proposed and verified using experimental apparatus based on the eye-rotation model. Two strategies-feedback positioning and posture adjustment of incident beams and Hartmann-Shack wavefront-aberration sensor calibration at each measurement subarea-are applied to improve measurement accuracy. By simulating the real-view condition, wavefront aberration and user power on the vertex sphere can be obtained. Comparison experiments demonstrate the validity and accuracy of the proposed method and experimental apparatus...
September 4, 2017: Optics Express
https://www.readbyqxmd.com/read/29041185/measurement-based-meshing-basis-selection-and-prior-assignment-in-chemical-species-tomography
#10
Samuel J Grauer, Paul J Hadwin, Timothy A Sipkens, Kyle J Daun
Gas distributions imaged by chemical species tomography (CST) vary in quality due to the discretization scheme, arrangement of optical paths, errors in the measurement model, and prior information included in reconstruction. There is currently no mathematically-rigorous framework for comparing the finite bases available to discretize a CST domain. Following from the Bayesian formulation of tomographic inversion, we show that Bayesian model selection can identify the mesh density, mode of interpolation, and prior information best-suited to reconstruct a set of measurement data...
October 16, 2017: Optics Express
https://www.readbyqxmd.com/read/29040720/genome-wide-prediction-of-minor-groove-electrostatic-potential-enables-biophysical-modeling-of-protein-dna-binding
#11
Tsu-Pei Chiu, Satyanarayan Rao, Richard S Mann, Barry Honig, Remo Rohs
Protein-DNA binding is a fundamental component of gene regulatory processes, but it is still not completely understood how proteins recognize their target sites in the genome. Besides hydrogen bonding in the major groove (base readout), proteins recognize minor-groove geometry using positively charged amino acids (shape readout). The underlying mechanism of DNA shape readout involves the correlation between minor-groove width and electrostatic potential (EP). To probe this biophysical effect directly, rather than using minor-groove width as an indirect measure for shape readout, we developed a methodology, DNAphi, for predicting EP in the minor groove and confirmed the direct role of EP in protein-DNA binding using massive sequencing data...
October 11, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29040294/towards-social-autonomous-vehicles-efficient-collision-avoidance-scheme-using-richardson-s-arms-race-model
#12
Faisal Riaz, Muaz A Niazi
This paper presents the concept of a social autonomous agent to conceptualize such Autonomous Vehicles (AVs), which interacts with other AVs using social manners similar to human behavior. The presented AVs also have the capability of predicting intentions, i.e. mentalizing and copying the actions of each other, i.e. mirroring. Exploratory Agent Based Modeling (EABM) level of the Cognitive Agent Based Computing (CABC) framework has been utilized to design the proposed social agent. Furthermore, to emulate the functionality of mentalizing and mirroring modules of proposed social agent, a tailored mathematical model of the Richardson's arms race model has also been presented...
2017: PloS One
https://www.readbyqxmd.com/read/29040063/validation-of-the-six-sigma-z-score-for-the-quality-assessment-of-clinical-laboratory-timeliness
#13
Cristiano Ialongo, Sergio Bernardini
BACKGROUND: The International Federation of Clinical Chemistry and Laboratory Medicine has introduced in recent times the turnaround time (TAT) as mandatory quality indicator for the postanalytical phase. Classic TAT indicators, namely, average, median, 90th percentile and proportion of acceptable test (PAT), are in use since almost 40 years and to date represent the mainstay for gauging the laboratory timeliness. In this study, we investigated the performance of the Six Sigma Z-score, which was previously introduced as a device for the quantitative assessment of timeliness...
October 17, 2017: Clinical Chemistry and Laboratory Medicine: CCLM
https://www.readbyqxmd.com/read/29039771/integrated-process-modeling-a-process-validation-life-cycle-companion
#14
Thomas Zahel, Stefan Hauer, Eric M Mueller, Patrick Murphy, Sandra Abad, Elena Vasilieva, Daniel Maurer, Cécile Brocard, Daniela Reinisch, Patrick Sagmeister, Christoph Herwig
During the regulatory requested process validation of pharmaceutical manufacturing processes, companies aim to identify, control, and continuously monitor process variation and its impact on critical quality attributes (CQAs) of the final product. It is difficult to directly connect the impact of single process parameters (PPs) to final product CQAs, especially in biopharmaceutical process development and production, where multiple unit operations are stacked together and interact with each other. Therefore, we want to present the application of Monte Carlo (MC) simulation using an integrated process model (IPM) that enables estimation of process capability even in early stages of process validation...
October 17, 2017: Bioengineering
https://www.readbyqxmd.com/read/29039750/modeling-of-body-weight-metrics-for-effective-and-cost-efficient-conventional-factor-viii-dosing-in-hemophilia-a-prophylaxis
#15
Alanna McEneny-King, Pierre Chelle, Severine Henrard, Cedric Hermans, Alfonso Iorio, Andrea N Edginton
The total body weight-based dosing strategy currently used in the prophylactic treatment of hemophilia A may not be appropriate for all populations. The assumptions that guide weight-based dosing are not valid in overweight and obese populations, resulting in overdosing and ineffective resource utilization. We explored different weight metrics including lean body weight, ideal body weight, and adjusted body weight to determine an alternative dosing strategy that is both safe and resource-efficient in normal and overweight/obese adult patients...
October 17, 2017: Pharmaceutics
https://www.readbyqxmd.com/read/29038943/a-lower-limb-pelvis-finite-element-model-with-3d-active-muscles
#16
Fuhao Mo, Fan Li, Michel Behr, Zhi Xiao, Guanjun Zhang, Xianping Du
A lower limb-pelvis finite element (FE) model with active three-dimensional (3D) muscles was developed in this study for biomechanical analysis of human body. The model geometry was mainly reconstructed from a male volunteer close to the anthropometry of a 50th percentile Chinese male. Tissue materials and structural features were established based on the literature and new implemented experimental tests. In particular, the muscle was modeled with a combination of truss and hexahedral elements to define its passive and active properties as well as to follow the detailed anatomy structure...
October 16, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/29038589/estimation-of-the-age-of-human-bloodstains-under-the-simulated-indoor-and-outdoor-crime-scene-conditions-by-atr-ftir-spectroscopy
#17
Hancheng Lin, Yinming Zhang, Qi Wang, Bing Li, Ping Huang, Zhenyuan Wang
Estimation of the age of human bloodstains is of great importance in forensic practices, but it is a challenging task because of the lack of a well-accepted, reliable, and established method. Here, the attenuated total reflection (ATR)-Fourier transform infrared (FTIR) technique combined with advanced chemometric methods was utilized to determine the age of indoor and outdoor bloodstains up to 107 days. The bloodstain storage conditions mimicked crime scene scenarios as closely as possible. Two partial least squares regression models-indoor and outdoor models with 7-85 days-exhibited good performance for external validation, with low values of predictive root mean squared error (5...
October 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29038273/pharmacokinetic-modelling-of-voriconazole-to-develop-an-alternative-dosing-regimen-in-children
#18
Silke Gastine, Thomas Lehrnbecher, Carsten Müller, Fedja Farowski, Peter Bader, Judith Ullmann-Moskovits, Oliver A Cornely, Andreas H Groll, Georg Hempel
Background. The pharmacokinetic variability of voriconazole in immunocompromised children is high and adequate exposure, particularly in the first days of therapy, is uncertain.Methods A population pharmacokinetic model was developed to explore VCZ exposure in plasma after alternative dosing regimens. Concentration data were obtained from a pediatric phase II study. Non-linear mixed effects modelling was used to develop the model. Monte Carlo simulations were performed to test an array of three times daily (TID) intravenous dosing regimens in children 2 to 12 years of age...
October 16, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/29037463/in-vivo-bone-strain-and-finite-element-modeling-of-a-rhesus-macaque-mandible-during-mastication
#19
Olga Panagiotopoulou, José Iriarte-Diaz, Simon Wilshin, Paul C Dechow, Andrea B Taylor, Hyab Mehari Abraha, Sharifah F Aljunid, Callum F Ross
Finite element analysis (FEA) is a commonly used tool in musculoskeletal biomechanics and vertebrate paleontology. The accuracy and precision of finite element models (FEMs) are reliant on accurate data on bone geometry, muscle forces, boundary conditions and tissue material properties. Simplified modeling assumptions, due to lack of in vivo experimental data on material properties and muscle activation patterns, may introduce analytical errors in analyses where quantitative accuracy is critical for obtaining rigorous results...
September 1, 2017: Zoology: Analysis of Complex Systems, ZACS
https://www.readbyqxmd.com/read/29037403/analytical-expressions-for-estimating-endurance-time-and-glove-thermal-resistance-related-to-human-finger-in-cold-conditions
#20
Amir Fallahi, Mohammad Reza Salimpour, Ebrahim Shirani
Frostbite is considered the severest form of cold injury and can lead to necrosis and loss of peripheral appendages. Therefore, prediction of endurance time of limb's tissue in cold condition is not only necessary but also crucial to estimate cold injury intensity and to choose appropriate clothing. According to the previous work which applied a 3-D thermal model for human finger to analyze cold stress, in this study, an expression is presented for endurance time in cold conditions to prevent cold injury. A formula is also recommended to select a proper glove with specific thermal resistance based on the ambient situation and cold exposure time...
October 2017: Journal of Thermal Biology
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