Search results for "knot"
showing 10 items of 156 documents
Conway irreducible hyperbolic knots with two common covers
2005
International audience; For each pair of coprime integers n > m ≥ 2 we construct pairs of non equivalent Conway irreducible hyperbolic knots with the same n-fold and m-fold cyclic branched covers.
A cubic defining algebra for the Links-Gould polynomial
2012
We define a finite-dimensional cubic quotient of the group algebra of the braid group, endowed with a (essentially unique) Markov trace which affords the Links-Grould invariant of knots and links. We investigate several of its properties, and state several conjectures about its structure.
Demonstration of a reef knot microfiber resonator.
2009
We propose a new way to realize a microfiber optical resonator by implementing the topology of a reef knot using two microfibers. We describe how this structure, which includes 4 ports and can serve as an add-drop filter, can be fabricated. Resonances in an all-silica reef knot are measured and good fits are obtained from a simple resonator model. We also show the feasibility of assembling a hybrid silica-chalcogenide reef knot structure.
Mapping onto ideal chains overestimates self-entanglements in polymer melts
2017
In polymer physics it is typically assumed that excluded volume interactions are effectively screened in polymer melts. Hence, chains could be described by an effective random walk without excluded volume interactions. In this letter, we show that this mapping is problematic by analyzing the occurrence of knots, their spectrum and sizes in polymer melts, corresponding random walks and chains in dilute solution. The effective random walk severely overrates the occurrence of knots and their complexity, particularly when compared to melts of flexible chains, indicating that non-trivial effects due to remnants of self-avoidance still play a significant role for the chain lengths considered in t…
Scaling behavior of topologically constrained polymer rings in a melt
2014
Large scale molecular dynamics simulations on graphic processing units (GPUs) are employed to study the scaling behavior of ring polymers with various topological constraints in melts. Typical sizes of rings containing $3_1$, $5_1$ knots and catenanes made up of two unknotted rings scale like $N^{1/3}$ in the limit of large ring sizes $N$. This is consistent with the crumpled globule model and similar findings for unknotted rings. For small ring lengths knots occupy a significant fraction of the ring. The scaling of typical ring sizes for small $N$ thus depends on the particular knot type and the exponent is generally larger than 0.4.
Influence of chain stiffness on knottedness in single polymers.
2013
In the present article, we investigate and review the influence of chain stiffness on self-entanglements and knots in a single polymer chain with Monte Carlo simulations spanning good solvent, theta and globular phases. The last-named are of particular importance as a model system for DNA in viral capsids. Intriguingly, the dependence of knot occurrence and complexity with increasing stiffness is non-trivial, but can be understood with a few simple concepts outlined in the present article.
Towards a "fingerprint" of paper network; separating forgeries from genuine by the properties of fibre structure
2014
A novel method is introduced for distinguishing counterfeit banknotes from genuine samples. The method is based on analyzing differences in the networks of paper fibers. The main tool is a curvelet-based algorithm for measuring the distribution of overall fiber orientation and quantifying its anisotropy. The use of a couple or more appropriate parameters makes it possible to distinguish forgeries from genuine samples as concentrated point clouds in a two- or three-dimensional parameter space. Furthermore, the techniques of making watermarks is investigated by comparing genuine and counterfeit e50 banknotes. In addition, the so-called wire markings are shown to differ significantly from each…
Naudas zīmju viltojumu atpazīšana specifiskā lāzeru apgaismojumā
2018
Bakalaura darba mērķis ir noskaidrot, vai naudas zīmju apstarošanas metode specifiskā – trihromātiskā – lāzeru apgaismojumā var tikt pielietota eiro valūtas viltojumu atpazīšanai. Izmantojot speciālu ar viedtālruni aprīkotu iekārtu, oriģinālās un viltotās eiro naudas zīmes tika apgaismotas vienlaicīgi ar trīs viļņu garumu lāzeriem (473nm, 532nm un 659nm), un ar viedtālrunī iebūvēto RGB kameru tika uzņemti attēli. Izmantojot RGB pārklāšanās korekcijas algoritmu, iegūtie attēli Matlab vidē tika sadalīti trijos līdz kameras sensoram nonākušās gaismas intensitāti raksturojošos attēlos – pie katra no lāzeriem viens attēls. Šo attēlu masīvu vērtības tika izmantotas parametrisku attēlu iegūšanai. …
Witkaco-Gombrowiczowskie tęsknoty i pragnienia, czyli od metafizyki do estetyki : interpretacje Jerzego Jarockiego
2016
Artykuł prezentuje sylwetki dwóch fascynujących twórców dwudziestowiecznego polskiego dramatu, opisanych na przykładzie Grzebania1 i Błądzenia2 - spektakli Jerzego Jarockiego. Opowiada o tęsknotach, pragnieniach, fobiach Stanisława Ignacego Witkiewicza i Witolda Gombrowicza, z których pierwszy uporczywie dążył do formy, a drugi - od formy pragnął się wyzwolić. „Palę, piję i nic mi to nie szkodzi” - pisał Witkacy w przedmowie do swoich Narkotyków. Z kolei Gombrowicz ustawicznie pisał o sobie, czyniąc z siebie samego bohatera własnych utworów. Jako punkt wyjścia dla moich rozważań wybrałam odmienne sposoby poszukiwania i zaspokajania pragnień duchowych oraz cielesnych.
A real-time PCR quantitative detection assay for Pseudomonas savastanoi pv. nerii in Nerium oleander
2008
A real-time PCR assay based on TaqMan chemistry was developed for the detection of Pseudomonas savastanoi pathovars that cause bacterial knot disease on different plant species. Primers and probe sequences were based on the iaaL gene coding for (indole-3-acetyl)-L-lysine synthetase and previously used in conventional PCR tests. Assay specificity was tested with an extended range of strains of P. savastanoi from eight hosts, with 13 other Pseudomonas spp., and with other microorganisms naturally occurring on or in oleander plants. A pure culture cell suspension was quantifi ed over a seven log concentration range (108 to 102 cfu ml-1 ). Different protocols were developed for the detection an…