620 research outputs found
A study on the relations between the topological parameter and entanglement
In this paper, some relations between the topological parameter and
concurrences of the projective entangled states have been presented. It is
shown that for the case with , all the projective entangled states of two
-dimensional quantum systems are the maximally entangled states (i.e.
). And for another case with , both approach when
for and . Then we study the thermal
entanglement and the entanglement sudden death (ESD) for a kind of Yang-Baxter
Hamiltonian. It is found that the parameter not only influences the
critical temperature , but also can influence the maximum entanglement
value at which the system can arrive at. And we also find that the parameter
has a great influence on the ESD.Comment: 8 pages, 5 figure
Method of constructing braid group representation and entanglement in a Yang-Baxter sysytem
In this paper we present reducible representation of the braid group
representation which is constructed on the tensor product of n-dimensional
spaces. By some combining methods we can construct more arbitrary
dimensional braiding matrix S which satisfy the braid relations, and we get
some useful braiding matrix S. By Yang-Baxteraition approach, we derive a unitary according to a braiding S-matrix
we have constructed. The entanglement properties of -matrix is
investigated, and the arbitrary degree of entanglement for two-qutrit entangled
states can be generated via -matrix
acting on the standard basis.Comment: 9 page
Fractionation statistics
<p>Abstract</p> <p>Background</p> <p>Paralog reduction, the loss of duplicate genes after whole genome duplication (WGD) is a pervasive process. Whether this loss proceeds gene by gene or through deletion of multi-gene DNA segments is controversial, as is the question of fractionation bias, namely whether one homeologous chromosome is more vulnerable to gene deletion than the other.</p> <p>Results</p> <p>As a null hypothesis, we first assume deletion events, on one homeolog only, excise a geometrically distributed number of genes with unknown mean <it>µ</it>, and these events combine to produce deleted runs of length l, distributed approximately as a negative binomial with unknown parameter <it>r</it>, itself a random variable with distribution <it>π</it>(·). A more realistic model requires deletion events on both homeologs distributed as a truncated geometric. We simulate the distribution of run lengths <it>l</it> in both models, as well as the underlying <it>π</it>(<it>r</it>), as a function of <it>µ</it>, and show how sampling <it>l</it> allows us to estimate <it>µ</it>. We apply this to data on a total of 15 genomes descended from 6 distinct WGD events and show how to correct the bias towards shorter runs caused by genome rearrangements. Because of the difficulty in deriving <it>π</it>(·) analytically, we develop a deterministic recurrence to calculate each <it>π</it>(<it>r</it>) as a function of <it>µ</it> and the proportion of unreduced paralog pairs.</p> <p>Conclusions</p> <p>The parameter <it>µ</it> can be estimated based on run lengths of single-copy regions. Estimates of <it>µ</it> in real data do not exclude the possibility that duplicate gene deletion is largely gene by gene, although it may sometimes involve longer segments.</p
Sufficient conditions for super k-restricted edge connectivity in graphs of diameter 2
AbstractFor a connected graph G=(V,E), an edge set S⊆E is a k-restricted edge cut if G−S is disconnected and every component of G−S has at least k vertices. The k-restricted edge connectivity of G, denoted by λk(G), is defined as the cardinality of a minimum k-restricted edge cut. Let ξk(G)=min{|[X,X¯]|:|X|=k,G[X]is connected}. G is λk-optimal if λk(G)=ξk(G). Moreover, G is super-λk if every minimum k-restricted edge cut of G isolates one connected subgraph of order k. In this paper, we prove that if |NG(u)∩NG(v)|≥2k−1 for all pairs u, v of nonadjacent vertices, then G is λk-optimal; and if |NG(u)∩NG(v)|≥2k for all pairs u, v of nonadjacent vertices, then G is either super-λk or in a special class of graphs. In addition, for k-isoperimetric edge connectivity, which is closely related with the concept of k-restricted edge connectivity, we show similar results
- …