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Finite growth models

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https://www.readbyqxmd.com/read/28724145/tense-marking-in-the-english-narrative-retells-of-dual-language-preschoolers
#1
Svenja Gusewski, Raúl Rojas
Purpose: This longitudinal study investigated the emergence of English tense marking in young (Spanish-English) dual language learners (DLLs) over 4 consecutive academic semesters, addressing the need for longitudinal data on typical acquisition trajectories of English in DLL preschoolers. Method: Language sample analysis was conducted on 139 English narrative retells elicited from 39 preschool-age (Spanish-English) DLLs (range = 39-65 months). Growth curve models captured within- and between-individual change in tense-marking accuracy over time...
July 19, 2017: Language, Speech, and Hearing Services in Schools
https://www.readbyqxmd.com/read/28718989/formation-of-stone-wales-edge-multistep-reconstruction-and-growth-mechanisms-of-zigzag-nanographene
#2
Jing-Shuang Dang, Wei-Wei Wang, Jia-Jia Zheng, Shigeru Nagase, Xiang Zhao
Although the existence of Stone-Wales (5-7) defect at graphene edge has been clarified experimentally, theoretical study on the formation mechanism is still imperfect. In particular, the regioselectivity of multistep reactions at edge (self-reconstruction and growth with foreign carbon feedstock) is essential to understand the kinetic behavior of reactive boundaries but investigations are still lacking. Herein, by using finite-sized models, multistep reconstructions and carbon dimer additions of a bared zigzag edge are introduced using density functional theory calculations...
July 18, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28705446/a-novel-sax-stent-method-in-treatment-of-ascending-aorta-and-aortic-arch-aneurysms-evaluated-by-finite-element-simulations
#3
M C Arokiaraj, M De Beule, G De Santis
OBJECTIVES: A novel stent method to simplify treatment of proximal ascending aorta and aortic arch aneurysms was developed and investigated by finite element analysis. Therapy of ascending aortic and aortic arch aneurysms is difficult and challenging and is associated with various complications. METHODS: A 55mm wide×120mm long stent was designed without the stent graft and the stent was deployed by an endovascular method in a virtual patient-specific aneurysm model...
February 2017: J Med Vasc
https://www.readbyqxmd.com/read/28698087/computational-fluid-dynamics-simulation-of-hemodynamic-alterations-in-sigmoid-sinus-diverticulum-and-ipsilateral-upstream-sinus-stenosis-after-stent-implantation-in-patients-with-pulsatile-tinnitus
#4
Yanjing Han, Qingqing Yang, Zeran Yang, Jun Xia, Tianhao Su, Long Jin, Aike Qiao, Jianan Yu
OBJECTIVE: To investigate the relationships between upstream venous sinus stenosis and pulsatile tinnitus (PT), and to assess the correlation with diverticulum growth and the effectiveness of stent implantation METHODS: A patient-specific geometric models were constructed using computed tomography venography images from a patient with PT with sigmoid sinus diverticulum(SSD) and upstream transverse sinus stenosis, in whom stenting of the upstream sinus stenosis alone achieved complete remission of PT...
July 8, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28690042/the-impact-of-subchondral-bone-cysts-on-local-bone-stresses-in-the-medial-femoral-condyle-of-the-equine-stifle-joint
#5
Lance L Frazer, Elizabeth M Santschi, Kenneth J Fischer
Subchondral lucency (SCL), also referred to as subchondral bone cysts, can cause clinical problems in horses and humans. In humans, SCLs occur in youths and adolescents [1] due to mechanical factors (often related to athletics) and in skeletally mature individuals secondary to osteoarthritis (OA). In horses, SCL most commonly occurs in the medial femoral condyle (MFC) of growing horses (without OA), and causes lameness. The cause of equine SCL is debated, but bone trauma due to overload is the likely mechanism...
July 6, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28685857/biomechanical-simulations-of-costo-vertebral-and-anterior-vertebral-body-tethers-for-the-fusionless-treatment-of-pediatric-scoliosis
#6
Carl-Éric Aubin, Julien Clin, Jeremy Rawlinson
Compression-based fusionless tethers are an alternative to conventional surgical treatments of pediatric scoliosis. Anterior approaches place an anterior (ANT) tether on the anterolateral convexity of the deformed spine to modify growth. Posterior, or costo-vertebral (CV), approaches have not been assessed for biomechanical and corrective effectiveness. The objective was to biomechanically assess CV and ANT tethers using six patient-specific, finite element models of adolescent scoliotic patients (11.9 ± 0...
July 7, 2017: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
https://www.readbyqxmd.com/read/28685434/computational-simulation-of-tumor-hypoxia-based-on-in-vivo-microvasculature-assessed-in-a-dorsal-skin-window-chamber
#7
Lina Xu, Peter Vaupel, Siwei Bai, Bjoern Menze, Kuangyu Shi
Malignant growth usually leads to the depletion of oxygen (O2) supply in most solid tumors. Hypoxia can cause resistance to standard radiotherapy, some chemotherapy and immunotherapy. Furthermore, it can also trigger malignant progression by modulating gene expression and inducing genetic instability. The relationship between microvasculature, perfusion and tumor hypoxia has been intensively studied and many computational simulations have been developed to model tissue O2 transport. Usually simplified 2D phantoms are used to investigate tumor hypoxia and it is assumed that vessels are perpendicular to the region of interest and randomly distributed across the domain...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28678541/mechanical-role-of-a-growing-solid-tumor-on-cortical-folding
#8
Mir Jalil Razavi, Mary Reeves, Xianqiao Wang
Cortical folding, or convolution of the brain, is a vital process in mammals that causes the brain to have a wrinkled appearance. The existence of different types of prenatal solid tumors may alter this complex phenomenon and cause severe brain disorders. Here we interpret the effects of a growing solid tumor on the cortical folding in the fetal brain by virtue of theoretical analyses and computational modeling. The developing fetal brain is modeled as a simple, double-layered, and soft structure with an outer cortex and an inner core, in combination with a circular tumor model imbedded in the structure to investigate the developmental mechanism of cortical convolution...
July 5, 2017: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/28675848/the-micro-damage-process-zone-during-transverse-cortical-bone-fracture-no-ears-at-crack-growth-initiation
#9
Thomas Willett, David Josey, Rick Xing Ze Lu, Gagan Minhas, John Montesano
OBJECTIVE: Apply high-resolution benchtop micro-computed tomography (micro-CT) to gain greater understanding and knowledge of the formation of the micro-damage process zone formed during traverse fracture of cortical bone. METHODS: Bovine cortical bone was cut into single edge notch (bending) fracture testing specimens with the crack on the transverse plane and oriented to grow in the circumferential direction. We used a multi-specimen technique and deformed the specimens to various individual secant modulus loss levels (P-values) up to and including maximum load (Pmax)...
June 24, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28669882/tumor-growth-model-of-ductal-carcinoma-from-in-situ-phase-to-stroma-invasion
#10
Olivier Gallinato, Thierry Colin, Olivier Saut, Clair Poignard
This paper aims at modeling breast cancer transition from the in situ stage -when the tumor is confined to the duct- to the invasive phase. Such a transition occurs thanks to the degradation of the duct membrane under the action of specific enzymes so-called matrix metalloproteinases (MMPs). The model consists of advection-reaction equations that hold in the duct and in the surrounding tissue, in order to describe the proliferation and the necrosis of the cancer cells in each subdomain. The divergence of the velocity is given by the increase of the cell densities...
June 30, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28657628/tracking-the-dissolution-of-calcite-single-crystals-in-acid-waters-a-simple-method-for-measuring-fast-surface-kinetics
#11
Maria Adobes-Vidal, Harriet Pearce, Patrick R Unwin
Although the dissolution kinetics of calcite in acid waters has been studied for more than a century, the process is not fully understood, and for particles and microcrystals the process is often assumed to be diffusion-controlled. Herein, the dissolution kinetics of calcite single microcrystals in aqueous solution (pH ca. 3) has been investigated for the first time by a combination of real-time optical microscopy coupled with numerical simulations. The small size and well-defined geometry of rhombohedral calcite single crystals enables the measurement of the dissolution rates of the individual crystal faces exposed to the solvent and an assessment of the relative importance of corners and edges compared to the {104} faces...
July 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28621284/comparison-of-platform-switched-and-sloping-shoulder-implants-on-stress-reduction-in-various-bone-densities-finite-element-analysis
#12
Joji Markose, S Suresh, Shruthi Eshwar, K Rekha, Vipin Jain, Supriya Manvi
INTRODUCTION: Comparison of platform switched (PS), sloping shoulder, and regular implants on stress reduction in various bone densities with finite element analysis. MATERIALS AND METHODS: A total of 12 three-dimensional finite element models were built to analyze the stress distribution model. Nobel Biocare 4.3 × 8 mm regular platform replace select implant with matching diameter easy abutment, Nobel Biocare 4.3 × 8 mm replace select implant PS with 3.5 mm diameter easy abutment, Bicon 4 × 8 mm implant with 4 mm diameter sloping shoulder abutments were created virtually in compact bone density using software...
June 1, 2017: Journal of Contemporary Dental Practice
https://www.readbyqxmd.com/read/28618602/finite-thickness-effects-on-the-rayleigh-taylor-instability-in-accelerated-elastic-solids
#13
S A Piriz, A R Piriz, N A Tahir
A physical model has been developed for the linear Rayleigh-Taylor instability of a finite-thickness elastic slab laying on top of a semi-infinite ideal fluid. The model includes the nonideal effects of elasticity as boundary conditions at the top and bottom interfaces of the slab and also takes into account the finite transit time of the elastic waves across the slab thickness. For Atwood number A_{T}=1, the asymptotic growth rate is found to be in excellent agreement with the exact solution [Plohr and Sharp, Z...
May 2017: Physical Review. E
https://www.readbyqxmd.com/read/28614573/finite-element-modeling-of-avascular-tumor-growth-using-a-stress-driven-model
#14
Faezeh Iranmanesh, Mohammad Ali Nazari
Tumor growth being a multi-stage process has been investigated from different aspects. In the present study, an attempt is made to represent a constitutive-structure based model of avascular tumor growth in which the effects of tensile stresses caused by collagen fibers are considered. Collagen fibers as a source of anisotropy in the structure of tissue, is taken into account using a continuous fiber distribution formulation. To this end, a finite element modeling is implemented in which a neo-Hookean hyperelastic material is assigned to the tumor and its surrounding host...
June 14, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28614278/patient-specific-distraction-regimen-to-avoid-growth-rod-failure
#15
Aakash Agarwal, Arvind Jayaswal, Anand K Agarwal, Vijay K Goel
STUDY DESIGN: A finite element study to establish the relationship between patient's curve flexibility (determined using curve correction under gravity) in juvenile idiopathic scoliosis and the required distraction frequency to avoid growth rod fracture, as a function of time. OBJECTIVE: To perform a parametric analysis using a juvenile scoliotic spine model (single mid-thoracic curve with the apex at the eighth thoracic vertebra) and establish the relationship between curve flexibility (determined using curve correction under gravity) and the distraction interval that allows a higher factor of safety for the growth rods...
June 13, 2017: Spine
https://www.readbyqxmd.com/read/28604803/impact-of-tumor-position-conductivity-distribution-and-tissue-homogeneity-on-the-distribution-of-tumor-treating-fields-in-a-human-brain-a-computer-modeling-study
#16
Anders Rosendal Korshoej, Frederik Lundgaard Hansen, Axel Thielscher, Gorm Burckhardt von Oettingen, Jens Christian Hedemann Sørensen
BACKGROUND: Tumor treating fields (TTFields) are increasingly used in the treatment of glioblastoma. TTFields inhibit cancer growth through induction of alternating electrical fields. To optimize TTFields efficacy, it is necessary to understand the factors determining the strength and distribution of TTFields. In this study, we provide simple guiding principles for clinicians to assess the distribution and the local efficacy of TTFields in various clinical scenarios. METHODS: We calculated the TTFields distribution using finite element methods applied to a realistic head model...
2017: PloS One
https://www.readbyqxmd.com/read/28566701/mathematical-analysis-of-glioma-growth-in-a-murine-model
#17
Erica M Rutter, Tracy L Stepien, Barrett J Anderies, Jonathan D Plasencia, Eric C Woolf, Adrienne C Scheck, Gregory H Turner, Qingwei Liu, David Frakes, Vikram Kodibagkar, Yang Kuang, Mark C Preul, Eric J Kostelich
Five immunocompetent C57BL/6-cBrd/cBrd/Cr (albino C57BL/6) mice were injected with GL261-luc2 cells, a cell line sharing characteristics of human glioblastoma multiforme (GBM). The mice were imaged using magnetic resonance (MR) at five separate time points to characterize growth and development of the tumor. After 25 days, the final tumor volumes of the mice varied from 12 mm(3) to 62 mm(3), even though mice were inoculated from the same tumor cell line under carefully controlled conditions. We generated hypotheses to explore large variances in final tumor size and tested them with our simple reaction-diffusion model in both a 3-dimensional (3D) finite difference method and a 2-dimensional (2D) level set method...
May 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28566514/modelling-human-skull-growth-a-validated-computational-model
#18
Joseph Libby, Arsalan Marghoub, David Johnson, Roman H Khonsari, Michael J Fagan, Mehran Moazen
During the first year of life, the brain grows rapidly and the neurocranium increases to about 65% of its adult size. Our understanding of the relationship between the biomechanical forces, especially from the growing brain, the craniofacial soft tissue structures and the individual bone plates of the skull vault is still limited. This basic knowledge could help in the future planning of craniofacial surgical operations. The aim of this study was to develop a validated computational model of skull growth, based on the finite-element (FE) method, to help understand the biomechanics of skull growth...
May 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28536534/a-bio-realistic-finite-element-model-to-evaluate-the-effect-of-masticatory-loadings-on-mouse-mandible-related-tissues
#19
Alexander Tsouknidas, Lucia Jimenez-Rojo, Evangelos Karatsis, Nikolaos Michailidis, Thimios A Mitsiadis
Mice are arguably the dominant model organisms for studies investigating the effect of genetic traits on the pathways to mammalian skull and teeth development, thus being integral in exploring craniofacial and dental evolution. The aim of this study is to analyse the functional significance of masticatory loads on the mouse mandible and identify critical stress accumulations that could trigger phenotypic and/or growth alterations in mandible-related structures. To achieve this, a 3D model of mouse skulls was reconstructed based on Micro Computed Tomography measurements...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28534795/choroid-neovascularization-growth-prediction-with-treatment-based-on-reaction-diffusion-model-in-3d-oct-images
#20
Shuxia Zhu, Fei Shi, Dehui Xiang, Weifang Zhu, Haoyu Chen, Xinjian Chen
Choroid neovascularization (CNV) is caused by new blood vessels growing in the choroid and penetrating the Bruch membrane. It is the major cause of vision disability in many retinal diseases. Though anti-vascular endothelial growth factor (VEGF) injection has proved to be effective for treating CNV, treatment planning is essential to ensure the efficacy while reducing the risk. For this purpose, we propose a CNV growth model based on longitudinal Optical Coherence Tomography (OCT) images. The reaction-diffusion model is applied to simulate the growth and shrinkage of CNV volumes, and is solved by using finite element method (FEM)...
May 16, 2017: IEEE Journal of Biomedical and Health Informatics
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