A simple cornea deformation model

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tobias Kehrer ◽  
Samuel Arba Mosquera
Keyword(s):  
Simple Model ◽  
Quantitative Comparison ◽  
Neutral Axis ◽  
Deformation Model ◽  
Corneal Tissue ◽  
Two Dimensional ◽  
Compressible Material ◽  
Real Patient ◽  
Reasonable Range ◽  
Lenticule Extraction

Abstract In this paper, we present a cornea deformation model based on the idea of extending the ‘neutral axis’ model to two-dimensional deformations. Considering this simple model, assuming the corneal tissue to behave like a continuous, isotropic and non-compressible material, we are able to partially describe, e.g., the observed deviation in refractive power after lenticule extraction treatments. The model provides many input parameters of the patient and the treatment itself, leading to an individual compensation ansatz for different setups. The model is analyzed for a reasonable range of various parameters. A semi-quantitative comparison to real patient data is performed.

scholarly journals EXPERIMENTS ON BEACH PROFILE CHANGE WITH A LARGE WAVE FLUME

1982 ◽  
Vol 1 (18) ◽  
pp. 85 ◽  
Author(s):  
Ryoichi Kajima ◽  
Takao Shimizu ◽  
Kohki Maruyama ◽  
Shozo Saito
Keyword(s):  
Simple Model ◽  
Transport Rate ◽  
Sand Transport ◽  
Two Dimensional ◽  
Beach Profile ◽  
Large Wave ◽  
Wave Flume ◽  
Grain Sizes ◽  
Profile Changes ◽  
Profile Change

Two-dimensional beach profile changes were investigated with a newly constructed prototype-scale wave flume. The flume is 205 m long, 3.4 m wide and 6 m deep. Sand of two grain sizes was used in the experiments. Analysis of the results was made through use of the parameter C, introduced by Sunamura and Horikawa (1974) to classify beaches as either erosional and accretionary. Beach profile changes obtained in the flume were similar to those in the prototype (field). Net sand transport rate distributions were classified into five types, two of which do not seem to have been observed in laboratory (smallscale) experiments. A simple model describing the five types was developed for evaluating two-dimensional beach profile changes.

scholarly journals Decellularized Human Stromal Lenticules Combine with Corneal Epithelial-Like Cells: A New Resource for Corneal Tissue Engineering

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Shuai Qin ◽  
Shuai Zheng ◽  
Bing Qi ◽  
Rui Guo ◽  
Guanghui Hou
Keyword(s):  
Tissue Engineering ◽  
Induction Medium ◽  
Nuclear Materials ◽  
Corneal Tissue ◽  
Corneal Epithelial ◽  
Human Ipscs ◽  
Immunological Rejection ◽  
Lenticule Extraction ◽  
Induced Pluripotent

The lack of donor corneal tissue or the immunological rejection remains a challenge for individuals with limbal stem cell deficiency (LSCD) who are treated with keratoplasty. Numerous lenticules which were extracted by small incision lenticule extraction (SMILE) appear to be useful materials for keratoplasty. In order to reduce the incidence of allograft rejection, lenticules would be decellularized. Lenticules which were treated with liquid nitrogen and nucleases had no cellular and nuclear materials remained. Human induced pluripotent stem cells (iPSCs) can be generated from the patient who requires keratoplasty, offering an autologous alternative and eliminating the risk of graft rejection. We found that BMP-4, RA, N-2 supplement, hEGF, B27, decellularized human stromal lenticules, conditioned medium, or induction medium promoted the differentiation of human iPSCs with high purity. The results showed that human iPSCs cultured for 4 days in differentiation medium A, 14 days in condition medium, and 1 week in induction medium on decellularized human stromal lenticules developed markedly higher expression of the markers P63, CK3, and CK12 than did those in the other methods. The level of gene expression of the epithelial and pluripotency markers and analysis by scanning electron microscopy and immunohistochemistry also showed successful differentiation. After inducing differentiation in vitro, corneal epithelial-like cells were induced. In the study, we investigated the possibility of a new resource for corneal tissue engineering.

Compacted dimensions and singular plasmonic surfaces

Science ◽  
2017 ◽  
Vol 358 (6365) ◽  
pp. 915-917 ◽  
Author(s):  
J. B. Pendry ◽  
Paloma Arroyo Huidobro ◽  
Yu Luo ◽  
Emanuele Galiffi
Keyword(s):  
Field Theory ◽  
Simple Model ◽  
Surface Plasmon ◽  
Graphene Layer ◽  
Field Theories ◽  
Two Dimensional ◽  
Experimental Realization ◽  
Four Dimensions ◽  
Metal Grating ◽  
Doped Graphene

In advanced field theories, there can be more than four dimensions to space, the excess dimensions described as compacted and unobservable on everyday length scales. We report a simple model, unconnected to field theory, for a compacted dimension realized in a metallic metasurface periodically structured in the form of a grating comprising a series of singularities. An extra dimension of the grating is hidden, and the surface plasmon excitations, though localized at the surface, are characterized by three wave vectors rather than the two of typical two-dimensional metal grating. We propose an experimental realization in a doped graphene layer.

Simple model designed to generate new crystal structures derived from a mother phase; application to molecular compounds

2002 ◽  
Vol 58 (4) ◽  
pp. 662-672 ◽  
Author(s):  
Claire Gervais ◽  
Gérard Coquerel
Keyword(s):  
Crystal Structure ◽  
Simple Model ◽  
Three Dimensional ◽  
Second Step ◽  
Two Dimensional ◽  
Basic Principles ◽  
Space Groups ◽  
Step Procedure ◽  
Symmetry Operators ◽  
Molecular Compounds

The basic principles of a model predicting new lattices from a known crystal structure are described. The first of the two-step procedure consists of extracting one- or two-dimensional periodic fragments (PF) from the mother structure. In the second step, symmetry operators are added to the PFs in order to generate one or several new three-dimensional lattices consistent with the 230 space groups. Most of the examples are related to polymorphism, but relationships between racemic compounds and enantiomers, twinning and lamellar epitaxy phenomena are also exemplified.

The Effect of a Turbulent Wake on the Stagnation Point: Part I — Skin Friction Results

1990 ◽  
Author(s):  
Dennis E. Wilson ◽  
Anthony J. Hanford
Keyword(s):  
Boundary Layer ◽  
Simple Model ◽  
Stagnation Point ◽  
Turbulent Wake ◽  
Incoming Flow ◽  
Two Dimensional ◽  
Unsteady Boundary Layer ◽  
Characteristic Parameters ◽  
Stagnation Region ◽  
Boundary Layer Edge

The response of a boundary layer in the stagnation region of a two-dimensional body to fluctuations in the freestream is examined. The analysis is restricted to laminar incompressible flow. The assumed form of the velocity distribution at the edge of the boundary layer represents both a pulsation of the incoming flow, and an oscillation of the stagnation point streamline. Both features are essential in accurately representing the effect which freestream spatial and temporal nonuniformities have upon the unsteady boundary layer. Finally, a simple model is proposed which relates the characteristic parameters in a turbulent wake to the unsteady boundary-layer edge velocity. Numerical results are presented for both an arbitrary two-dimensional geometry and a circular cylinder.

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