36 research outputs found
Construction of weaving and polycatenane motifs from periodic tilings of the plane
Doubly periodic weaves and polycatenanes embedded in the thickened Euclidean
plane are three-dimensional complex entangled structures whose topological
properties can be encoded in any generating cell of its infinite planar
representation. Such a periodic cell, called motif, is a specific type of link
diagram embedded on a torus consisting of essential simple closed curves for
weaves, or null-homotopic for polycatenanes. In this paper, we introduce a
methodology to construct such motifs using the concept of polygonal link
transformations. This approach generalizes to the Euclidean plane existing
methods to construct polyhedral links in the three-dimensional space. Then, we
will state our main result which allows one to predict the type of motif that
can be built from a given planar periodic tiling and a chosen polygonal link
method.Comment: 21 pages, 11 figure
Stable configurations of entangled graphs and weaves with repulsive interactions
Entangled objects such as entangled graphs and weaves are often seen in
nature. In the present article, two identical graphs entangled, and weaves with
two different color threads are studied. A method to identify stable
configurations in the three dimensional space of a given topological entangled
structure, a planar graph with crossing information, is proposed by analyzing
the steepest descent flow of the energy functional with repulsive interactions.
The existence and uniqueness of a solution in the entangled case. In the
untangled case, a weave has a unique tangle decomposition with height order,
whose components are moving away each other in the order as time
goes to the infinity.Comment: 37 pages, 4 figure
A Large X-ray Flare from a Single Weak-lined T Tauri Star TWA-7 Detected with MAXI GSC
We present a large X-ray flare from a nearby weak-lined T Tauri star TWA-7
detected with the Gas Slit Camera (GSC) on the Monitor of All-sky X-ray Image
(MAXI). The GSC captured X-ray flaring from TWA-7 with a flux of
ergs cm s in 2--20 keV band during the scan
transit starting at UT 2010-09-07 18:24:30.The estimated X-ray luminosity at
the scan in the energy band is 3 ergs s,indicating that
the event is among the largest X-ray flares fromT Tauri stars.Since MAXI GSC
monitors a target only during a scan transit of about a minute per 92 min
orbital cycle, the luminosity at the flare peak might have been higher than
that detected. At the scan transit, we observed a high X-ray-to-bolometric
luminosity ratio, log = ; i.e., the
X-ray luminosity is comparable to the bolometric luminosity. Since TWA-7 has
neither an accreting disk nor a binary companion, the observed event implies
that none of those are essential to generate such big flares in T Tauri stars.Comment: 4 pages, 2 figures, 1 table accepted for publication in PAS