scholarly journals Stimulating electrode Design for Implantable Sub Retina Research Application: A Novel Approach

2018 ◽  
Vol 7 (2.24) ◽  
pp. 570
Author(s):  
T Alavanthar ◽  
V Ellappan
Keyword(s):  
Charge Injection ◽  
Internal Surface ◽  
Initial Step ◽  
Minimal Invasive ◽  
Design Stage ◽  
Electrode Position ◽  
Retinal Implant ◽  
Retinal Tissue ◽  
Novel Approach ◽  
Implant System

This paper aims to study and converse the theoretical model of neural stimulation implant electrodes with the electrochemical aspects of design. The study investigates the practically realizable hypothetical model of minimal invasive retinal implant (miRI) stimulating electrodes for restoring lost sight of patients blinded by degenerative retinal diseases. The basic elemental methods of charge injection by the stimulation electrode to tissue are pointed out.  A prologue on the developments of vision implants and electrode characteristics were presented. We communicated the most important factors considered in this design stage of modeling, such as electrode position, size, impedance, charge injection capability, temperature change of the targeted retinal tissue and it’s surrounding for vision implant system. In this design, a mathematical model is created to investigate for the all above said factors which influence implants positioned at internal surface of the retinal tissue. This investigation gives an initial step in design verification before the fabrication.  

First experience with The IRIS retinal implant system

2009 ◽  
Vol 87 ◽  
pp. 0-0 ◽  
Author(s):  
M VELIKAY-PAREL ◽  
D IVASTINOVIC ◽  
G LANGMANN ◽  
R HORNIG ◽  
T GEORGI ◽  
...  
Keyword(s):  
Retinal Implant ◽  
Implant System

Dynamic Positioning: Early Design, Capability and Offsets—A Novel Approach

2011 ◽  
Author(s):  
R. van ’t Veer ◽  
M. Gachet
Keyword(s):  
Dynamic Environment ◽  
Low Frequency ◽  
Numerical Approach ◽  
Time Variable ◽  
Design Stage ◽  
Dynamic Positioning ◽  
Novel Approach ◽  
Wave Drift Forces ◽  
Variable Wind ◽  
Drift Forces

Many vessels use a Dynamic Positioning (DP) system that automatically controls vessel position and heading with its own propulsion system. The limiting environment in which a vessel can maintain heading and position under DP operation is typically shown in a capability plot. Capability is usually evaluated assuming constant environmental forces — the static DP approach. In this paper we discuss the methodology of how such a capability assessment can be made early in the vessel design stage. The insights obtained in the heading and position variability over time, and the effects of the environmental forces varying with time can be assessed through model tests and time domain simulations: the dynamic DP approach. This implies that the DP system characteristics are modeled. In a numerical approach, the time variable wind load and low-frequency drift forces are included in the assessment. This paper presents a novel approach on how static DP capability calculations can be corrected to account for the time variable wind and wave drift forces. This leads to a DP capability plot that provides a more realistic insight in the actual DP capability of the vessel in the dynamic environment.

Centrifugal Instability of a Geostrophic Jet

2020 ◽  
Author(s):  
Francis Poulin ◽  
Matthew Harris ◽  
Kevin Lamb
Keyword(s):  
Reynolds Number ◽  
Numerical Model ◽  
Linear Theory ◽  
Growth Rates ◽  
Initial Step ◽  
Spatial Structures ◽  
Vortical Structures ◽  
Novel Approach ◽  
Centrifugal Instability ◽  
Fluid Properties

<p>Oceanic and Atmospheric jets with sufficiently strong anticyclonic vorticity are subject to centrifugal instabilities. This mechanism is relatively fast in comparison to barotropic and baroclinic instabilities and require non-conservative forces that mix the fluid properties. In this work, we present a novel approach to compute the linear stability characteristics of both barotropic and baroclinic jets. This enables us to compute the growth rates and spatial structures very accurately and efficiently. Subsequently, by integrating the fully nonlinear, non-hydrostatic dynamics using the spectrally accurate numerical model SPINS, we validate the predictions of the linear theory and then investigate the nonlinear equilibration that results. Depending on the Reynolds number of the flows, there are instances where a secondary instability occurs that eventually produces vortical structures, some of which are themselves subject to centrifugal instabilities. This idealized investigation quantifies the effects of centrifugal instabilities as an initial step to determine how to parameterize them.</p><p> </p>

Pixel Characterization of a Protein-Based Retinal Implant Using a Microfabricated Sensor Array

2017 ◽  
Vol 26 (03) ◽  
pp. 1740012 ◽  
Author(s):  
Jordan A. Greco ◽  
Luis André L. Fernandes ◽  
Nicole L. Wagner ◽  
Mehdi Azadmehr ◽  
Philipp Häfliger ◽  
...  
Keyword(s):  
Ganglion Cells ◽  
Photoreceptor Cells ◽  
Image Sensor ◽  
Subretinal Space ◽  
Retinal Implant ◽  
Retinal Tissue ◽  
Significant Difference ◽  
Retinal Degenerative Diseases ◽  
The Brain

Retinal degenerative diseases are characterized by the loss of photoreceptor cells within the retina and affect 30-50 million people worldwide. Despite the availability of treatments that slow the progression of degeneration, affected patients will go blind. Thus, there is a significant need for a prosthetic that is capable of restoring functional vision for these patients. The protein-based retinal implant offers a high-resolution option for replacing the function of diseased photoreceptor cells by interfacing with the underlying retinal tissue, stimulating the remaining neural network, and transmitting this signal to the brain. The retinal implant uses the photoactive protein, bacteriorhodopsin, to generate an ion gradient in the subretinal space that is capable of activating the remaining bipolar and ganglion cells within the retina. Bacteriorhodopsin can also be photochemically driven to an active (bR) or inactive (Q) state, and we aim to exploit this photochemistry to mediate the activity of pixels within the retinal implant. In this study, we made use of a novel retinomorphic foveated image sensor to characterize the formation of active and inactive pixels within a protein-based retinal implant, and have measured a significant difference between the output frequencies associated with the bR and Q states.

scholarly journals K-mer clustering algorithm using a MapReduce framework: application to the parallelization of the Inchworm module of Trinity

2017 ◽  
Author(s):  
Chang Sik Kim ◽  
Martyn D. Winn ◽  
Vipin Sachdeva ◽  
Kirk E. Jordan
Keyword(s):  
Clustering Algorithm ◽  
De Novo ◽  
Transcriptome Assembly ◽  
Initial Step ◽  
Computer Hardware ◽  
Model Organisms ◽  
De Bruijn Graph ◽  
Memory Representation ◽  
Novel Approach ◽  
Sequencing Problems

AbstractBackgroundDe novo transcriptome assembly is an important technique for understanding gene expression in non-model organisms. Many de novo assemblers using the de Bruijn graph of a set of the RNA sequences rely on in-memory representation of this graph. However, current methods analyse the complete set of read-derived k-mer sequence at once, resulting in the need for computer hardware with large shared memory.ResultsWe introduce a novel approach that clusters k-mers as the first step. The clusters correspond to small sets of gene products, which can be processed quickly to give candidate transcripts. We implement the clustering step using the MapReduce approach for parallelising the analysis of large datasets, which enables the use of compute clusters. The computational task is distributed across the compute system, and no specialised hardware is required. Using this approach, we have re-implemented the Inchworm module from the widely used Trinity pipeline, and tested the method in the context of the full Trinity pipeline. Validation tests on a range of real datasets show large reductions in the runtime and per-node memory requirements, when making use of a compute cluster.ConclusionsOur study shows that MapReduce-based clustering has great potential for distributing challenging sequencing problems, without loss of accuracy. Although we have focussed on the Trinity package, we propose that such clustering is a useful initial step for other assembly pipelines.

Structural Acoustic Design

1995 ◽  
Author(s):  
Jean Nicolas ◽  
Noureddine Atalla ◽  
Olivier Foin ◽  
Alain Berry
Keyword(s):  
Acoustic Radiation ◽  
Basic Structure ◽  
Wide Frequency Range ◽  
Design Stage ◽  
Constrained Layer Damping ◽  
Damping Force ◽  
Modal Shape ◽  
Acoustic Design ◽  
Aspect Ratios ◽  
Novel Approach

Abstract Nowadays, acoustic quietening of manufactured products is gaining importance. Due to cost, severe weight and operational constraints, classical noise control techniques, although still usable, are becoming less attractive. Nowadays, engineers follow essentially two major approaches (i) reduce noise by passive means, design modifications of structures and systems (ii) reduce noise by active sound and vibration control. This paper is devoted to the structural acoustic design approach for which there are either some simple rules of thumb either huge numerical codes. The main objective of this paper is to bridge the gap between these two extremes. For the vibration response, the approach is based on a variational method. The basic structure is a plate with several degrees of complexity: added local or distributed masses, added local or distributed stiffeners, added stiffeners, added damping and constrained layer damping, force and moment type of excitations. The general trend has been to model an equivalent plate with two objectives in mind: (i) numerical calculations may be performed on a P.C., (ii) results are as close as possible to the exact solution. For the acoustic radiation, a novel approach has been used based on Berry’s idea (Berry, 1994) to develop the Green function in terms of a Taylor expansion. Analytical impedance functions may then be calculated for various aspect ratios and then extracted directly from files which allow considerable atime gains over any other rigorous approaches. The A.D.N.R. (Acoustic Design Noise Reduction) code has been validated through several experimental steps and agreement is revealed to be quite good. Not only is A.D.N.R. precise, but it also covers a wide frequency range (low, medium and high frequencies) which is really an advantage. The output data are diversified and among them we may cite: modal shape, operating deflection shape, quadratic velocity, radiation factor and overall sound power. In practice, A.D.N.R. revealed itself to be a great tool at the pre-design stage, when clear and quick trends are needed.

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