Greedy Differencing Edge-Contraction heuristic for the Max-Cut problem

2021 ◽  
Author(s):  
Refael Hassin ◽  
Nikita Leshenko
Keyword(s):  
Edge Contraction ◽  
Max Cut Problem

In vitro and in vivo Effect of Platelet-Rich Plasma-Based Autologous Topical Serum on Cutaneous Wound Healing

2021 ◽  
pp. 1-13
Author(s):  
Eduardo Anitua ◽  
Victoria Muñoz ◽  
Libe Aspe ◽  
Roberto Tierno ◽  
Adrian García-Salvador ◽  
...  
Keyword(s):  
Wound Healing ◽  
Tissue Damage ◽  
Collagen Synthesis ◽  
Dermal Fibroblast ◽  
Platelet Rich Plasma ◽  
Cell Activity ◽  
Cutaneous Wound Healing ◽  
Cutaneous Wound ◽  
Fibroblast Migration ◽  
Edge Contraction

<b><i>Introduction:</i></b> Skin injury and wound healing is an inevitable event during lifetime. However, several complications may hamper the regeneration of the cutaneous tissue and lead to a chronic profile that prolongs patient recovery. Platelet-rich plasma is rising as an effective and safe alternative to the management of wounds. However, this technology presents some limitations such as the need for repeated blood extractions and health-care interventions. <b><i>Objective:</i></b> The aim of this study was to assess the use of an endogenous and storable topical serum (ES) derived from plasma rich in growth factors promoting wound healing, and to obtain preliminary data regarding its clinical and experimental effect over ulcerated skin models and patient care. <b><i>Methods:</i></b> Human dermal fibroblast and 3D organotypic ulcerated skin models were used to assess ES over the main mechanisms of wound healing including cell migration, edge contraction, collagen synthesis, tissue damage, extracellular matrix remodeling, cell death, metabolic activity, and histomorphometry analysis. Additionally, 4 patients suffering from skin wounds were treated and clinically assessed. <b><i>Results:</i></b> ES promoted dermal fibroblast migration, wound edge contraction, and collagen synthesis. When topically applied, ES increased collagen and elastin deposition and reduced tissue damage. The interstitial edema, structural integrity, and cell activity were also maintained, and apoptotic levels were reduced. Patients suffering from hard-to-heal wounds of different etiologies were treated with ES, and the ulcers healed completely within few weeks with no reported adverse events. <b><i>Conclusion:</i></b> This preliminary study suggests that ES might promote cutaneous wound healing and may be useful for accelerating the re-epithelization of skin ulcers.

scholarly journals Delayed improvement local search

2021 ◽  
Author(s):  
Heber F. Amaral ◽  
Sebastián Urrutia ◽  
Lars M. Hvattum
Keyword(s):  
Local Search ◽  
Heuristic Algorithms ◽  
Travelling Salesman Problem ◽  
Computation Time ◽  
The Novel ◽  
Local Optima ◽  
New Strategy ◽  
Max Cut Problem ◽  
Novel Method ◽  
Similar Solutions

AbstractLocal search is a fundamental tool in the development of heuristic algorithms. A neighborhood operator takes a current solution and returns a set of similar solutions, denoted as neighbors. In best improvement local search, the best of the neighboring solutions replaces the current solution in each iteration. On the other hand, in first improvement local search, the neighborhood is only explored until any improving solution is found, which then replaces the current solution. In this work we propose a new strategy for local search that attempts to avoid low-quality local optima by selecting in each iteration the improving neighbor that has the fewest possible attributes in common with local optima. To this end, it uses inequalities previously used as optimality cuts in the context of integer linear programming. The novel method, referred to as delayed improvement local search, is implemented and evaluated using the travelling salesman problem with the 2-opt neighborhood and the max-cut problem with the 1-flip neighborhood as test cases. Computational results show that the new strategy, while slower, obtains better local optima compared to the traditional local search strategies. The comparison is favourable to the new strategy in experiments with fixed computation time or with a fixed target.

Topological features in crystal structures: a quotient graph assisted analysis of underlying nets and their embeddings

2016 ◽  
Vol 72 (3) ◽  
pp. 268-293 ◽  
Author(s):  
Jean-Guillaume Eon
Keyword(s):  
Crystal Structures ◽  
Direct Analysis ◽  
Building Blocks ◽  
Quotient Graph ◽  
Quotient Graphs ◽  
Edge Contraction ◽  
Topological Features ◽  
Structure Decomposition ◽  
Bond Topology ◽  
Ring Analysis

Topological properties of crystal structures may be analysed at different levels, depending on the representation and the topology that has been assigned to the crystal. Considered here is thecombinatorialorbond topologyof the structure, which is independent of its realization in space. Periodic nets representing one-dimensional complexes, or the associated graphs, characterize the skeleton of chemical bonds within the crystal. Since periodic nets can be faithfully represented by their labelled quotient graphs, it may be inferred that their topological features can be recovered by a direct analysis of the labelled quotient graph. Evidence is given for ring analysis and structure decomposition into building units and building networks. An algebraic treatment is developed for ring analysis and thoroughly applied to a description of coesite. Building units can be finite or infinite, corresponding to 1-, 2- or even 3-periodic subnets. The list of infinite units includes linear chains or sheets of corner- or edge-sharing polyhedra. Decomposing periodic nets into their building units relies on graph-theoretical methods classified assurgery techniques. The most relevant operations are edge subdivision, vertex identification, edge contraction and decoration. Instead, these operations can be performed on labelled quotient graphs, evidencing in almost a mechanical way the nature and connection mode of building units in the derived net. Various examples are discussed, ranging from finite building blocks to 3-periodic subnets. Among others, the structures of strontium oxychloride, spinel, lithiophilite and garnet are addressed.

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