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simulation model

Jianeng Xu, Conghui Huang, Xiaoyang Shi, Shengkun Dong, Baoling Yuan, Thanh H Nguyen
PVC pipe loops were constructed to simulate household premise plumbing. These pipe loops were exposed to water treated by physical processes at three water treatment plants in Xiamen, China from August 2016 to June 2017. After the biofilms were allowed to develop inside the pipes, these pipes were deconstructed and exposed to organic-free chlorine solution buffered at pH 6.8 ± 0.2 for 48 h. The decay of chlorine by these biofilms was higher than by the effluent waters that were used to grow the biofilms...
June 13, 2018: Science of the Total Environment
Thomas Hennequin, Hjalte Jomo Danielsen Sørup, Yan Dong, Karsten Arnbjerg-Nielsen
Sustainable flood management is a basic societal need. In this article, life cycle assessment is used to compare two ways to maintain the state of a coastal urban area in a changing climate with increasing flood risk. On one side, the construction of a dike, a hard and proactive scenario, is modelled using a bottom up approach. On the other, the systematic repair of houses flooded by sea surges, a post-disaster measure, is assessed using a Monte Carlo simulation allowing for aleatory uncertainties in predicting future sea level rise and occurrences of extreme events...
June 13, 2018: Science of the Total Environment
H Forehead, N Huynh
Traffic emissions are a complex and variable cocktail of toxic chemicals. They are the major source of atmospheric pollution in the parts of cities where people live, commute and work. Reducing exposure requires information about the distribution and nature of emissions. Spatially and temporally detailed data are required, because both the rate of production and the composition of emissions vary significantly with time of day and with local changes in wind, traffic composition and flow. Increasing computer processing power means that models can accept highly detailed inputs of fleet, fuels and road networks...
June 13, 2018: Environmental Pollution
Alireza Mohammadkarim, Mohammad Tabatabaei, Azim Parandakh, Manijhe Mokhtari-Dizaji, Mohammad Tafazzoli-Shadpour, Mohammad-Mehdi Khani
Radiation therapy has been widely utilized as an effective method to eliminate malignant tumors and cancerous cells. However, subjection of healthy tissues and the related networks of blood vessels adjacent to the tumor area to irradiation is inevitable. The aim of this study was to investigate the consequent effects of fractionation radiotherapy on the mechanical characteristics of human umbilical vein endothelial cells (HUVECs) through alterations in cytoskeleton organization and cell and nucleus morphology...
June 6, 2018: Journal of the Mechanical Behavior of Biomedical Materials
J Sun, Y P Li, P P Gao, C Suo, B C Xia
In this study, a stepwise cluster modeling approach (SCMA) is developed for analyzing urban ecosystem variation via Normalized Difference Vegetation Index (NDVI). NDVI is an indicator of vegetation growth and coverage and useful in reflecting urban ecosystem. SCMA is established on a cluster tree that can characterize the complex relationship between independent and dependent variables. SCMA is applied to the City of Dongguan for simulating the urban NDVI and identifying associated drivers of human activity, topography and meteorology without specific functions...
June 13, 2018: Environmental Research
Francisco Maciá Pérez, Leandro Zambrano Méndez, José Vicente Berná Martínez, Roberto Sepúlveda Lima
This article presents the design of a field programmable gate array (FPGA)-based prototype of a system on chip (SoC) capable of behaving as one of the nerve centres comprising the neuroregulatory system in humans: the cortical-diencephalic nerve centre. The neuroregulatory system is a complex nerve system consisting of a heterogeneous group of nerve centres. These centres are distributed throughout the length of the spinal cord, are autonomous, communicate via interneurons, and govern and regulate the behaviour of multiple organs and systems in the human body...
June 13, 2018: Computers in Biology and Medicine
Daniel P Otto, Melgardt M de Villiers
Improvement of problematic dissolution and solubility properties of a model drug, furosemide, was investigated for poly(amidoamine) (PAMAM) dendrimer complexes of the drug. Full and half generation dendrimers with amino and ester terminals respectively, were studied. In vitro release performance of these complexes was investigated at drug loads ranging 5-60% using simulated gastric fluids. Full generation dendrimers accommodated higher drug loads, outperformed half-generation complexes, and free drug. Pharmacokinetic studies in rats indicated that the dendrimer complexes markedly improved in the bioavailability of the drug compared to the unformulated drug...
June 13, 2018: International Journal of Pharmaceutics
Paola Mura, Serena Orlandini, Marzia Cirri, Francesca Maestrelli, Natascia Mennini, Giada Casella, Sandra Furlanetto
The work was aimed at developing an in vitro method able to provide rapid and reliable evaluation of drug absorption through buccal mucosa. Absorption simulator apparatus endowed with an artificial membrane was purposely developed by experimental design. The apparent permeation coefficient (Papp ) through excised porcine buccal mucosa of naproxen, selected as model drug, was the target value to obtain with the artificial membrane. The multivariate approach enabled systematic evaluation of the effect on the response (Papp ) of simultaneous variations of the variables (kind of lipid components for support impregnation and relative amounts)...
June 13, 2018: International Journal of Pharmaceutics
Jay Smith, Håkan Alfredson, Lorenzo Masci, Jacob L Sellon, Charonn D Woods
BACKGROUND: The plantaris tendon (PT) has been implicated in the pathogenesis of symptoms in a subset of patients with Achilles region pain syndromes and has been traditionally managed via open surgical resection. Although the PT can be visualized on ultrasound, a minimally invasive technique for sonographically guided PT release has not been formally described. OBJECTIVE: To validate a technique to perform sonographically guided PT release in an unembalmed cadaveric model...
June 13, 2018: PM & R: the Journal of Injury, Function, and Rehabilitation
Junyi Xin, Haiyan Chu, Shuai Ben, Yuqiu Ge, Wei Shao, Yang Zhao, Yongyue Wei, Gaoxiang Ma, Shuwei Li, Dongying Gu, Zhengdong Zhang, Mulong Du, Meilin Wang
Currently, genetic risk score (GRS) model has been a widely used method to evaluate the genetic effect of cancer risk prediction, but seldom studies investigated their discriminatory power, especially for colorectal cancer (CRC) risk prediction. In this study, we applied both simulation and real data to comprehensively compare the discriminability of different GRS models. The GRS models were fitted by logistic regression with three scenarios, including simple count GRS (SC-GRS), logistic regression weighted GRS (LR-GRS, including DL-GRS and OR-GRS) and explained variance weighted GRS (EV-GRS, including EV_DL-GRS and EV_OR-GRS) models...
June 13, 2018: Gene
Yuanfeng Pan, Jingchun Wang, PingxiongCai, Huining Xiao
In this work, the stepwise synthesis of interpenetrating polymer network (IPN) strategy was developed in an attempt to fabricate novel hydrogels consisting of sugarcane bagasse cellulose (SBC), carboxymethylcellulose (CMC) and poly (N-isopropylacrylamide) (PNIPAm) as a dual-responsive drug carrier. The pretreated and dissolved SBC was pre-crosslinked using epichlorohydrin in the presence of CMC, followed by in-situ free-radical polymerization of NIPAm in the presence of N,N'-Methylene-bis(acrylamide) as a crosslinking agent...
June 13, 2018: International Journal of Biological Macromolecules
Axel Ekman, Venera Weinhardt, Jian-Hua Chen, Gerry McDermott, Mark A Le Gros, Carolyn Larabell
In this manuscript, we introduce a linear approximation of the forward model of soft x-ray tomography (SXT), such that the reconstruction is solvable by standard iterative schemes. This linear model takes into account the three-dimensional point spread function (PSF) of the optical system, which consequently enhances the reconstruction data. The feasibility of the model is demonstrated on both simulated and experimental data, based on theoretically estimated and experimentally measured PSFs.
June 13, 2018: Journal of Structural Biology
Subhas Khajanchi, Sandip Banerjee
We present a mathematical model which describes the growth of malignant gliomas in presence of immune responses by considering the role of immunotherapeutic agent T11 target structure (T11TS). The model consider five populations, namely, glioma cells, macrophages, cytotoxic T-lymphocytes, TGF - β and IFN - γ. The model system has highly nonlinear terms with four discrete time lags, but remains tractable. The goal of this work is to better understand the effect of multiple delays on the interaction between gliomas and immune components in conjunction with an administration of T11 target structure...
June 13, 2018: Mathematical Biosciences
Lone Hoffmann, Markus Alber, Matthias Söhn, Ulrik Vindelev Elstrøm
PURPOSE: The two distinct dose computation paradigms of Boltzmann Equation Solvers and Monte Carlo simulation both promise in principle maximum accuracy. In practice, clinically acceptable calculation times demand approximations and numerical short-cuts on one hand, and modelling the beam characteristics of a real linear accelerator to the required accuracy on the other. A thorough benchmark of both algorithm types therefore needs to start with beam modelling, and needs to include a number of clinically challenging treatment plans...
June 16, 2018: Medical Physics
Ilaria Cinelli, Michel Destrade, Peter McHugh, Maeve Duffy
OBJECTIVE: We confirm that alteration of a neuron structure can induce abnormalities in signal propagation for nervous systems, as observed in brain damage. Here, we investigate the effects of geometrical changes and damage of a neuron structure in two scaled nerve bundle models, made of myelinated nerve fibres or unmyelinated nerve fibres. METHODS: We propose a 3D finite element model of nerve bundles, combining a real-time full electro-mechanical coupling, a modulated threshold for spiking activation and independent alteration of the electrical properties for each fibre...
June 16, 2018: International Journal for Numerical Methods in Biomedical Engineering
R Philip Chalmers
This paper proposes a model-based family of detection and quantification statistics to evaluate response bias in item bundles of any size. Compensatory (CDRF) and non-compensatory (NCDRF) response bias measures are proposed, along with their sample realizations and large-sample variability when models are fitted using multiple-group estimation. Based on the underlying connection to item response theory estimation methodology, it is argued that these new statistics provide a powerful and flexible approach to studying response bias for categorical response data over and above methods that have previously appeared in the literature...
June 15, 2018: Psychometrika
Rotem Ben-Shachar, Katia Koelle
An extensive body of theory addresses the topic of pathogen virulence evolution, yet few studies have empirically demonstrated the presence of fitness trade-offs that would select for intermediate virulence. Here we show the presence of transmission-clearance trade-offs in dengue virus using viremia measurements. By fitting a within-host model to these data, we further find that the interaction between dengue and the host immune response can account for the observed trade-offs. Finally, we consider dengue virulence evolution when selection acts on the virus's production rate...
June 15, 2018: Nature Communications
R Larrainzar-Garijo, C Cifuentes de la Portilla, B Gutiérrez-Narvarte, E Díez-Nicolás, J Bayod
Medializing calcaneal osteotomy forms part of the treatment options for adult acquired flat foot. The structural correction that is achieved is widely known. However, the effect of this procedure on the soft tissues that support the plantar arch has been little studied, since it is not possible to quantify experimentally the tension and deformation variations generated. Therefore, the objective of this study was to evaluate the effect of medializing calcaneal osteotomy on the soft tissue that supports the plantar arch, using a computational model of the human foot designed with a clinical approach...
June 12, 2018: Revista Española de Cirugía Ortopédica y Traumatología
Utku Gülan, Christelle Calen, Firat Duru, Markus Holzner
An aortic aneurysm is defined as a balloon-shaped bulging of all three histologic components of the aortic vessel walls (intima, media and adventitia). This dilation results from vessel weakening owing to remodeling, i.e. due to cystic degeneration of the Tunica media (Marfan), progression of atherosclerosis or presence of a bicuspid aortic valve. The growth rate of the aortic diameter varies from patient to patient and may progress until the aneurysm ultimately ruptures. The role of hemodynamics, i.e. blood flow patterns, and shear stresses that are supposed to intensify during aneurysm growth are not yet fully understood, but thought to play a key role in the enlargement process...
June 8, 2018: Journal of Biomechanics
Cristiana Gomes de Oliveira Dal'Molin, Lake-Ee Quek, Pedro A Saa, Robin Palfreyman, Lars Keld Nielsen
The compartmentalization of C4 plants increases photosynthetic efficiency, while constraining how material and energy must flow in leaf tissues. To capture this metabolic phenomenon, a generic plant metabolic reconstruction was replicated into four connected spatiotemporal compartments, namely bundle sheath (B) and mesophyll (M) across the day and night cycle. The C4 leaf model was used to explore how amenable polyhydroxybutyrate (PHB) production is with these four compartments working cooperatively. A strategic pattern of metabolite conversion and exchange emerged from a systems-level network that has very few constraints imposed; mainly the sequential two-step carbon capture in mesophyll, then bundle sheath and photosynthesis during the day only...
August 2018: Plant Science: An International Journal of Experimental Plant Biology
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