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"Validation" simulation model

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https://www.readbyqxmd.com/read/28728324/the-chicken-thigh-adductor-profundus-free-muscle-flap-a-novel-validated-non-living-microsurgery-simulation-training-model
#1
Georgios Pafitanis, Yasmine Serrar, Maria Raveendran, Ali Ghanem, Simon Myers
BACKGROUND: Simulation training is becoming an increasingly important component of skills acquisition in surgical specialties, including Plastic Surgery. Non-living simulation models have an established place in Plastic Surgical microsurgery training, and support the principles of replacement, reduction and refinement of animal use. A more sophisticated version of the basic chicken thigh microsurgery model has been developed to include dissection of a type 1-muscle flap and is described and validated here...
July 2017: Archives of Plastic Surgery
https://www.readbyqxmd.com/read/28728129/a-finite-element-model-development-for-simulation-of-the-impact-of-slab-thickness-joints-and-membranes-on-indoor-radon-concentration
#2
E Muñoz, B Frutos, M Olaya, J Sánchez
The focus of this study is broadly to define the physics involved in radon generation and transport through the soil and other materials using different parameter-estimation tools from the literature. The effect of moisture in the soil and radon transport via water in the pore space was accounted for with the application of a porosity correction coefficient. A 2D finite element model is created, which reproduces the diffusion and advection mechanisms resulting from specified boundary conditions. A comparison between the model and several analytical and numerical solutions obtained from the literature and field studies validates the model...
July 17, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28726698/experimental-study-and-artificial-neural-network-modeling-of-tartrazine-removal-by-photocatalytic-process-under-solar-light
#3
Aicha Sebti, Fatiha Souahi, Faroudja Mohellebi, Sadek Igoud
This research focuses on the application of an artificial neural network (ANN) to predict the removal efficiency of tartrazine from simulated wastewater using a photocatalytic process under solar illumination. A program is developed in Matlab software to optimize the neural network architecture and select the suitable combination of training algorithm, activation function and hidden neurons number. The experimental results of a batch reactor operated under different conditions of pH, TiO2 concentration, initial organic pollutant concentration and solar radiation intensity are used to train, validate and test the networks...
July 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28724095/modeling-the-effects-of-onsite-wastewater-treatment-systems-on-nitrate-loads-using-swat-in-an-urban-watershed-of-metropolitan-atlanta
#4
Nahal Hoghooghi, David E Radcliffe, Mussie Y Habteselassie, Jaehak Jeong
Onsite wastewater treatment systems (OWTSs) can be a source of nitrogen (N) pollution in both surface and ground waters. In metropolitan Atlanta, GA, >26% of homes are on OWTSs. In a previous article, we used the Soil Water Assessment Tool to model the effect of OWTSs on stream flow in the Big Haynes Creek Watershed in metropolitan Atlanta. The objective of this study was to estimate the effect of OWTSs, including failing systems, on nitrate as N (NO-N) load in the same watershed. Big Haynes Creek has a drainage area of 44 km with mainly urban land use (67%), and most of the homes use OWTSs...
May 2017: Journal of Environmental Quality
https://www.readbyqxmd.com/read/28723106/proteins-breaking-bad-a-free-energy-perspective
#5
Jessica Valle-Orero, Rafael Tapia-Rojo, Edward C Eckels, Jaime Andres Rivas-Pardo, Ionel Popa, Julio M Fernandez
Protein ageing may manifest as a mechanical disease that compromises tissue elasticity. As proved recently, while proteins respond to changes in force with an instantaneous elastic recoil followed by a folding contraction, aged proteins break bad, becoming unstructured polymers. Here, we explain this phenomenon in the context of a free energy model, predicting the changes in the folding landscape of proteins upon oxidative ageing. Our findings validate that protein folding under force is constituted by two separable components, polymer properties and hydrophobic collapse, and demonstrate that the latter becomes irreversibly blocked by oxidative damage...
July 19, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28722824/local-equilibrium-and-retardation-revisited
#6
Scott K Hansen, Velimir V Vesselinov
In modeling solute transport with mobile-immobile mass transfer (MIMT), it is common to use an advection-dispersion equation (ADE) with a retardation factor, or retarded ADE. This is commonly referred to as making the local equilibrium assumption (LEA). Assuming local equilibrium, Eulerian textbook treatments derive the retarded ADE, ostensibly exactly. However, other authors have presented rigorous mathematical derivations of the dispersive effect of MIMT, applicable even in the case of arbitrarily fast mass transfer...
July 19, 2017: Ground Water
https://www.readbyqxmd.com/read/28722471/simulated-annealing-molecular-dynamics-and-ligand-receptor-contacts-analysis-for-pharmacophore-modeling
#7
Ma'mon M Hatmal, Mutasem O Taha
AIM: Ligand-based pharmacophore modeling requires long list of inhibitors, while pharmacophores based on single ligand-receptor crystallographic structure can be too restricted or promiscuous. METHODOLOGY: This prompted us to combine simulated annealing molecular dynamics (SAMD) with ligand-receptor contacts analysis as means to construct pharmacophore model(s) from single ligand-receptor complex. Ligand-receptor contacts that survive numerous heating-cooling SAMD cycles are considered critical and are used to guide pharmacophore development...
July 19, 2017: Future Medicinal Chemistry
https://www.readbyqxmd.com/read/28719062/immersive-virtual-reality-as-a-teaching-tool-for-neuroanatomy
#8
Katelyn Stepan, Joshua Zeiger, Stephanie Hanchuk, Anthony Del Signore, Raj Shrivastava, Satish Govindaraj, Alfred Iloreta
BACKGROUND: Three-dimensional (3D) computer modeling and interactive virtual reality (VR) simulation are validated teaching techniques used throughout medical disciplines. Little objective data exists supporting its use in teaching clinical anatomy. Learner motivation is thought to limit the rate of utilization of such novel technologies. The purpose of this study is to evaluate the effectiveness, satisfaction, and motivation associated with immersive VR simulation in teaching medical students neuroanatomy...
July 18, 2017: International Forum of Allergy & Rhinology
https://www.readbyqxmd.com/read/28718770/benchmarking-gate-geant4-for-sup-16-sup-o-ion-beam-therapy
#9
Andreas Franz Resch, Hermann Fuchs, Dietmar Georg
Oxygen (<sup>16</sup>O) ions are a potential alternative to carbon ions in ion beam therapy. Their enhanced linear energy transfer indicates a higher relative biological effectiveness and a reduced oxygen enhancement ratio. Due to the limited availability of <sup>16</sup>O ion beams, Monte Carlo (MC) transport codes are important research tools to investigate their potential. The purpose of this study was to validate GATE/Geant4 for <sup>16</sup>O ion beam therapy on experimental data from literature...
July 18, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28717554/toward-on-line-parameter-estimation-of-concentric-tube-robots-using-a-mechanics-based-kinematic-model
#10
Cheongjae Jang, Junhyoung Ha, Pierre E Dupont, Frank Chongwoo Park
Although existing mechanics-based models of concentric tube robots have been experimentally demonstrated to approximate the actual kinematics, determining accurate estimates of model parameters remains difficult due to the complex relationship between the parameters and available measurements. Further, because the mechanics-based models neglect some phenomena like friction, nonlinear elasticity, and cross section deformation, it is also not clear if model error is due to model simplification or to parameter estimation errors...
October 2016: Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems
https://www.readbyqxmd.com/read/28716931/combining-experimental-and-simulation-data-of-molecular-processes-via-augmented-markov-models
#11
Simon Olsson, Hao Wu, Fabian Paul, Cecilia Clementi, Frank Noé
Accurate mechanistic description of structural changes in biomolecules is an increasingly important topic in structural and chemical biology. Markov models have emerged as a powerful way to approximate the molecular kinetics of large biomolecules while keeping full structural resolution in a divide-and-conquer fashion. However, the accuracy of these models is limited by that of the force fields used to generate the underlying molecular dynamics (MD) simulation data. Whereas the quality of classical MD force fields has improved significantly in recent years, remaining errors in the Boltzmann weights are still on the order of a few [Formula: see text], which may lead to significant discrepancies when comparing to experimentally measured rates or state populations...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28716541/development-and-validation-of-an-accurate-gate-model-for-neuropet-scanner
#12
Peyman Sheikhzadeh, Hamid Sabet, Hossein Ghadiri, Parham Geramifar, Hojjat Mahani, Pardis Ghafarian, Mohammad Reza Ay
NeuroPET is a cylindrical full ring mobile PET/CT scanner for brain imaging that was developed by Photo Diagnostic Systems, Inc. The scanner has 7 modules, each with 3×4 detector blocks. The detectors have two layers of scintillator arrays with a half pixel pitch offset to realize two levels of depth of interaction. In this study, we evaluated the NeuroPET scanner modeled in the GATE simulation tool and analyzed the acquired data to better understand the contribution of inter-detector scattering (IDS). The results show that the average difference between simulated and measured data for a point-like source is 2...
July 14, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28716030/modeling-de-novo-granulation-of-anaerobic-sludge
#13
Anna Doloman, Honey Varghese, Charles D Miller, Nicholas S Flann
BACKGROUND: A unique combination of mechanical, physiochemical and biological forces influences granulation during processes of anaerobic digestion. Understanding this process requires a systems biology approach due to the need to consider not just single-cell metabolic processes, but also the multicellular organization and development of the granule. RESULTS: In this computational experiment, we address the role that physiochemical and biological processes play in granulation and provide a literature-validated working model of anaerobic granule de novo formation...
July 17, 2017: BMC Systems Biology
https://www.readbyqxmd.com/read/28715855/assessing-long-term-impact-of-land-use-change-on-hydrological-ecosystem-functions-in-a-mediterranean-upland-agro-forestry-catchment
#14
Paolo Nasta, Mario Palladino, Nadia Ursino, Antonio Saracino, Angelo Sommella, Nunzio Romano
During the second half of the 20th century farming systems in hilly and mountainous areas of Mediterranean Europe were progressively abandoned and the forest cover subsequently re-expanded. This paper investigates the environmental impacts of land-use/land-cover (LULC) changes on hydrological ecosystem functions (HEFs) in the Upper Alento River Catchment (UARC) in southern Italy. We document the human-driven post-war landscape in 1955 with its maximum expansion of pasture and crops. By 1998 forest cover had doubled and cropland had roughly halved due to decades of land abandonment and reduction in human pressure...
July 10, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28715676/modelling-the-impacts-of-altered-management-practices-land-use-and-climate-changes-on-the-water-quality-of-the-millbrook-catchment-reservoir-system-in-south-australia
#15
Hong Hanh Nguyen, Friedrich Recknagel, Wayne Meyer, Jacqueline Frizenschaf, Manoj Kumar Shrestha
Sustainable management of drinking water reservoirs requires taking into account the potential effects of their catchments' development. This study is an attempt to estimate the daily patterns of nutrients transport in the catchment - reservoir systems through the application of the ensemble of complementary models SWAT-SALMO. SWAT quantifies flow, nitrate and phosphate loadings originating in catchments before entering downstream reservoirs meanwhile SALMO determines phosphate, nitrate, and chlorophyll-a concentrations within the reservoirs...
July 14, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28715429/a-microscopic-simulation-model-for-pedestrian-pedestrian-and-pedestrian-vehicle-interactions-at-crosswalks
#16
Manxia Liu, Weiliang Zeng, Peng Chen, Xuyi Wu
This study aims to develop a microscopic pedestrian behavior model considering various interactions on pedestrian dynamics at crosswalks. Particularly, we take into account the evasion behavior with counter-flow pedestrians, the following behavior with leader pedestrians, and the collision avoidance behavior with vehicles. Aerial video data at one intersection in Beijing, China are extracted for model calibration. A microscopic calibration approach based on maximum likelihood estimation is applied to estimate the parameters of a modified social force model...
2017: PloS One
https://www.readbyqxmd.com/read/28715130/average-glandular-dose-coefficients-for-pendant-geometry-breast-ct-using-realistic-breast-phantoms
#17
Andrew M Hernandez, John M Boone
PURPOSE: To design volume-specific breast phantoms from breast CT (bCT) data sets and estimate the associated normalized mean glandular dose coefficients for breast CT using Monte Carlo methods. METHODS: A large cohort of bCT data sets (N=215) was used to evaluate breast volume into quintiles (plus the top 5%). The average radius profile was then determined for each of the six volume-specific groups and used to both fabricate physical phantoms and generate mathematical phantoms (V1-V6; "V" denotes classification by volume)...
July 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28714064/assessing-the-validity-of-the-approximation-of-diffusion-weighted-mri-signals-from-crossing-fascicles-by-sums-of-signals-from-single-fascicles
#18
Gaëtan Rensonnet, Benoît Scherrer, Simon K Warfield, Benoît Macq, Maxime Taquet
PURPOSE: To assess the validity of the superposition approximation for crossing fascicles, i.e., the assumption that the total diffusion-weighted MRI signal is the sum of the signals arising from each fascicle independently, even when the fascicles intermingle in a voxel. METHODS: Monte Carlo simulations were used to study the impact of the approximation on the diffusion-weighted MRI signal and to assess whether this approximate model allows microstructural features of interwoven fascicles to be accurately estimated, despite signal differences...
July 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28713828/the-effect-of-small-sample-size-on-measurement-equivalence-of-psychometric-questionnaires-in-mimic-model-a-simulation-study
#19
Jamshid Jamali, Seyyed Mohammad Taghi Ayatollahi, Peyman Jafari
Evaluating measurement equivalence (also known as differential item functioning (DIF)) is an important part of the process of validating psychometric questionnaires. This study aimed at evaluating the multiple indicators multiple causes (MIMIC) model for DIF detection when latent construct distribution is nonnormal and the focal group sample size is small. In this simulation-based study, Type I error rates and power of MIMIC model for detecting uniform-DIF were investigated under different combinations of reference to focal group sample size ratio, magnitude of the uniform-DIF effect, scale length, the number of response categories, and latent trait distribution...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28712950/predictors-of-laparoscopic-simulation-performance-among-practicing-obstetrician-gynecologists
#20
Shyama Mathews, Michael Brodman, Debra D'Angelo, Scott Chudnoff, Peter Mcgovern, Tamara Kolev, Giti Bensinger, Santosh Mudiraj, Andreea Nemes, David Feldman, Patricia Kischak, Charles Ascher-Walsh
BACKGROUND: To determine if parameters of performance for validated laparoscopic virtual simulation tasks correlate with surgical volume and characteristics of practicing obstetricians and gynecologists. STUDY DESIGN: All gynecologists with laparoscopic privileges (n= 347) from five academic medical centers in New York City were required to complete a laparoscopic surgery simulation assessment. The physicians took a pre-simulation survey gathering physician self-reported characteristics and then performed 3 basic skills tasks (enforced peg transfer (PT), lifting & grasping (LG), and cutting (CT)) on the Surgical Science LapSim(®)virtual reality laparoscopic simulator...
July 13, 2017: American Journal of Obstetrics and Gynecology
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