Search results for "TOPOLOGY"

The number of contacts in random fibre networks

2012

There is a wide range of materials that can be considered as nonwoven random networks of fibres. Such materials include glass-fibre mats, filters, various paper products and structural components of cells and tissues. The mechanical properties of these kinds of networks have been studied extensively for many decades. As many of such networks form more or less two-dimensional structures, they can, to a good approximation, be considered to consist of randomly distributed fibres or filaments connected at their crossings points. Recent development of the resolution of X-ray computed tomography have enabled imaging of the three dimensional structure of such materials with a resolution sufficient…

Drugs Repurposing for Coronavirus Treatment: Computational Study Based On Molecular Topology

2020

The present communication illustrates the results of a computational study based on molecular topology, focused on the repositioning of drugs to treat the SARS-CoV-2 virus, better known as coronavirus, responsible for the COVID-19 disease. Using lopinavir, a well-known viral protease inhibitor as the reference drug, a mathematical pattern is found allowing the screening of the market drugs, searching for potential candidates to inhibit the said enzyme. This way new possible therapeutic alternatives to fight the coronavirus are found. Results indicate that antivirals such as brecanavir, as well as various groups of drugs, among which are antibiotics of the macrolide family (azithromycin, cla…

Prediction of quinolone activity against Mycobacterium avium by molecular topology and virtual computational screening.

2000

ABSTRACT We conducted a quantitative structure-activity relationship study using a database of 158 quinolones previously tested against Mycobacterium avium-M. intracellulare complex in order to develop a model capable of predicting the activity of new quinolones against the M. avium-M. intracellulare complex in vitro. Topological indices were used as structural descriptors and were related to anti- M. avium-M. intracellulare complex activity by using the linear discriminant analysis (LDA) statistical technique. The discriminant equation thus obtained correctly classified 137 of the 158 quinolones, including 37 of a test group of 44 randomly chosen compounds. This model was then applied to 2…

Dynamic tuning of the director field in liquid crystal shells using block copolymers

2020

When an orientationally ordered system, like a nematic liquid crystal (LC), is confined on a self-closing spherical shell, topological constraints arise with intriguing consequences that depend critically on how the LC is aligned in the shell. We demonstrate reversible dynamic tuning of the alignment, and thereby the topology, of nematic LC shells stabilized by the nonionic amphiphilic block copolymer Pluronic F127. Deep in the nematic phase, the director (the average molecule orientation) is tangential to the interface, but upon approaching the temperature TNI of the nematic– isotropic transition, the director realigns to normal. We link this to a delicate interplay between an interfacial …

4-Manifold topology II: Dwyer's filtration and surgery kernels

1995

Even when the fundamental group is intractable (i.e. not "good") many interesting 4-dimensional surgery problems have topological solutions. We unify and extend the known examples and show how they compare to the (presumed) counterexamples by reference to Dwyer's filtration on second homology. The development brings together many basic results on the nilpotent theory of links. As a special case, a class of links only slightly smaller than "homotopically trivial links" is shown to have (free) slices on their Whitehead doubles.

Transcatheter Vs. Surgical Closure of Atrial Septal Defects in Adults

2018

Abstract Percutaneous transcatheter device closure of secundum atrial septal defects (ASD) has now largely replaced surgical closure in most centres. The aim of this study was to compare results of transcatheter and surgical ASD closure in adults in Latvia during the years 2002–2014 and to analyse long-term outcomes of transcatheter closure. We analysed data from 334 patients with secundum ASD who underwent ASD closure in Pauls Stradiņš Clinical University Hospital. Patients were included into device or surgical closure groups. In the device group, three follow-ups were made 1, 6, and 12 months after the procedure. No follow-up data were available for surgical arm patients beyond their hosp…

Percutaneous puncture of an aorto‐bifemoral bypass graft and successful closure with MANTA ® device in transfemoral TAVR

2021

Transfemoral aortic valve replacement (TAVR) has become a standard therapeutic option for patients with symptomatic severe aortic stenosis. Special anatomies can pose distinct challenges for vascular access and later closure of the access site, for example, in preoperated patients. Here, we elucidate a case of transfemoral TAVR with vascular access by direct puncture of an aorto-bifemoral bypass graft and illustrate the feasibility of vascular closure by an anchored collagen-plug vascular closure device (Teleflex MANTA® ).

Models and Model Transformations Within Web Applications

2016

Unlike traditional single-user desktop applications, web applications have separated memory and computational resources (the client and the server side) and have to deal with multiple user accounts. This complicates the development process. Is there some approach of creating web applications without thinking about web-specific aspects, as if we are developing stand-alone desktop applications? We say, “yes”, and that is where models and model transformations come in handy. The proposed model-driven approach simplifies the development of web applications and makes it possible to use a single code base for deploying both desktop and web-based versions of the software.

Surgical Closure of Atrial and Ventricular Septal Defects

2010

Assistive Technologies and Autism Spectrum Disorders

2015

This chapter discusses assistive technologies applied in people with autism spectrum disorders and how these technologies promote their adaptation. We analyzed different technological application areas such as detection, assessment, diagnosis, intervention, training, learning, environment control, communication, mobility, and access. In recent years there has been a notable increase of publications and works related to the use of assistive technologies applied to Autism Spectrum Disorders. While most of the publications present novel systems, devices, and applications (smartphones, tablets, robots, avatars, etc.), general evaluation of the results is insufficient. Future lines of research a…