Local Repair Signature Handling for Repairable Memories

2014 ◽  
Author(s):  
Ramesh Tekumalla ◽  
Prakash Krishnamoorthy
Keyword(s):  
Local Repair

scholarly journals Incremental Construction of Generalized Voronoi Diagrams on Pointerless Quadtrees

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Quanjun Yin ◽  
Long Qin ◽  
Xiaocheng Liu ◽  
Yabing Zha
Keyword(s):  
Voronoi Diagrams ◽  
Surrounding Area ◽  
Repair Mechanism ◽  
Local Repair ◽  
Order Of Magnitude ◽  
Generalized Voronoi Diagrams ◽  
Incremental Construction ◽  
Coarse To Fine ◽  
Multiple Granularities ◽  
Magnitude Improvement

In robotics, Generalized Voronoi Diagrams (GVDs) are widely used by mobile robots to represent the spatial topologies of their surrounding area. In this paper we consider the problem of constructing GVDs on discrete environments. Several algorithms that solve this problem exist in the literature, notably the Brushfire algorithm and its improved versions which possess local repair mechanism. However, when the area to be processed is very large or is of high resolution, the size of the metric matrices used by these algorithms to compute GVDs can be prohibitive. To address this issue, we propose an improvement on the current algorithms, using pointerless quadtrees in place of metric matrices to compute and maintain GVDs. Beyond the construction and reconstruction of a GVD, our algorithm further provides a method to approximate roadmaps in multiple granularities from the quadtree based GVD. Simulation tests in representative scenarios demonstrate that, compared with the current algorithms, our algorithm generally makes an order of magnitude improvement regarding memory cost when the area is larger than210×210. We also demonstrate the usefulness of the approximated roadmaps for coarse-to-fine pathfinding tasks.

scholarly journals Robust Gap Repair in the Contractile Ring Ensures Timely Completion of Cytokinesis

2016 ◽  
Author(s):  
AM Silva ◽  
D Osório ◽  
AJ Pereira ◽  
H Maiato ◽  
IM Pinto ◽  
...  
Keyword(s):  
Laser Cutting ◽  
Ring Structure ◽  
Biophysical Properties ◽  
Animal Cells ◽  
Contractile Ring ◽  
Local Repair ◽  
C Elegans ◽  
Timely Completion ◽  
New Material ◽  
Robust Process

AbstractCytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting contractile rings in C. elegans embryos. Laser cutting causes rings to snap open, which is a sign of tension release. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms that is proportional to ring perimeters before cutting, demonstrating that tension along the ring decreases throughout constriction. Severed rings repair their gaps by recruiting new material and subsequently increase constriction rate and complete cytokinesis with the same timing as uncut rings. Rings repair successive cuts and exhibit substantial constriction when gap repair is prevented. Our analysis suggests that cytokinesis is accomplished by contractile modules that assemble and contract autonomously, enabling local repair of the actomyosin network throughout constriction. Consequently, cytokinesis is a highly robust process impervious to discontinuities in contractile ring structure.

scholarly journals Mechanosensitive calcium signaling promotes epithelial tight junction remodeling by activating RhoA

2021 ◽  
Author(s):  
Saranyaraajan Varadarajan ◽  
Rachel E. Stephenson ◽  
Eileen R. Misterovich ◽  
Jessica L. Wu ◽  
Ivan S. Erofeev ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Intracellular Calcium ◽  
Tight Junctions ◽  
Calcium Influx ◽  
Cell Junctions ◽  
Mechanical Stimuli ◽  
Local Repair ◽  
Transient Activation ◽  
Epithelial Tight Junction ◽  
Sense And Respond

Epithelia maintain an effective barrier by remodeling cell-cell junctions in response to mechanical stimuli. Cells often respond to mechanical stress through activating RhoA and remodeling actomyosin. Previously, we found that local leaks in the barrier are rapidly repaired by localized, transient activation of RhoA – ″Rho flares″ – but how Rho flares are initiated remains unknown. Here, we discovered that intracellular calcium flashes occur in Xenopus laevis epithelial cells undergoing Rho flare-mediated remodeling of tight junctions. Calcium flashes originate at the site of barrier leaks and propagate into the cell. Depletion of intracellular calcium or inhibition of mechanosensitive calcium channels (MSC) reduced the amplitude of calcium flashes and diminished the activation of Rho flares. Furthermore, MSC-dependent calcium influx was necessary to maintain global barrier function by regulating local repair of tight junctions through efficient junction contraction. We propose that MSC-dependent calcium flashes are an important mechanism allowing epithelial cells to sense and respond to local leaks induced by mechanical stimuli.

State of the art technology for subsea tie-in and repair systems in the North Sea

2010 ◽  
Vol 50 (2) ◽  
pp. 737
Author(s):  
Per A. Nesje
Keyword(s):  
North Sea ◽  
State Of The Art ◽  
Cost Savings ◽  
Repair System ◽  
Design Phase ◽  
Significant Cost ◽  
Local Repair ◽  
The North ◽  
The North Sea ◽  
Vertical System

The new design of subsea structures such as riser bases (RB), pipeline end terminations (PLET) and pipeline end manifolds (PLEM) has resulted in lighter and more installation-friendly solutions. PLETs and PLEMs can be installed together with the pipeline, avoiding separate installation campaigns. The RB is designed to slide on the seabed, hence it can be connected directly to the pipeline, avoiding the need for expansion spools. If dropped object and/or trawl protection is required, a range of standardised GRP protection covers is available for the protection of structures, inline/hot-tap tees and spools. A new remote controlled tie-in system—THOR—has been developed for general use. The concept offers significant cost savings when measured against the existing conventional tie-in tool based systems. The system will be available for all pipeline sizes and will be independent of connector manufacturer.A vertical system for hot-tapping and tie-in onto a hot-tap tee has been developed and installed on the Ormen Lange field. The system includes a contingency isolation plug for recovery of the isolation valve module.Active pipeline supports (APS) have been introduced to the market and are now installed on several projects. This type of structure will enable the adjustment of pipelines during and after installation, and will therefore ensure more flexibility during the design phase. The pipeline repair system developed for the North Sea has been used for 20 years and is definitively field proven through a large number of repair operations and planned work. Many repair components and their associated installation systems have been made and used over these years. Based on this knowledge we can now better recommend, to a new repair market such as Australia, which type of repair items to purchase for the local repair system. This evaluation will also identify the items or components that should be partly prepared, either on a design level only, or up until storage of forged material or completion of particular long lead items.

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