In the problemMin-DESC, we are given a digraphD and an integer k, and asked whether there exists a set A of at most k arcs inD, such that if we remove the arcs of A, in the resulting digraph every strong component is Eulerian. Min-DESC is NP-hard; Cechlárová and Schlotter (IPEC 2010) asked whether the problem is fixed-parameter tractable when parameterized by k. We consider the subproblem of Mi...

Introduced implicitly by Brualdi and Massey [3] in their work on the strong chromatic index of multigraphs, the arc incidence graph AI(G) of a graph G is defined as the square of the line graph of the incidence graph of G. We describe a linear-time algorithm for recognizing arc incidence graphs and reconstructing a graph with no isolated vertices from its arc incidence graph.

We perform an extensive comparison of relational consistencies along four dimensions: on binary constraints, on non-binary constraints, on encodings of non-binary constraints, and on decomposable non-binary constraints. Our results contain some surprises. For example, on binary constraints, relational path-consistency does not reduce to path-consistency. On non-binary constraints, relational ar...

The present bunch compressor design for the NLC allows control of the final bunch length by way of changes to the horizontal betatron phase advance of the 180ƒ-turnaround arc. This adjustability requirement significantly constrains the design and cost optimization of the system and excludes the possibility of using permanent-magnet quadrupoles in the arc. To relieve this constraint, and to avoi...

Arc is a unique immediate early gene whose expression is induced as synapses are being modified during learning. The uniqueness comes from the fact that newly synthesized Arc mRNA is rapidly transported throughout dendrites where it localizes near synapses that were recently activated. Here, we summarize aspects of Arc mRNA translation in dendrites in vivo, focusing especially on features of it...

Multiple hypothalamic neuronal populations that regulate energy balance have been identified. Although hypothalamic glia exist in abundance and form intimate structural connections with neurons, their roles in energy homeostasis are less known. Here we show that selective Ca2+ activation of glia in the mouse arcuate nucleus (ARC) reversibly induces increased food intake while disruption of Ca2+...

A tournament is a digraph, where there is precisely one arc between every pair of distinct vertices. An arc is pancyclic in a digraph D, if it belongs to a cycle of length l, for all 3 <= l <= |V (D)|. Let p(D) denote the number of pancyclic arcs in a digraph D and let h(D) denote the maximum number of pancyclic arcs belonging to the same Hamilton cycle of D. Note that p(D) >= h(D). Moon showed...

We prove that every digraph of independence number at most 2 and arc-connectivity least has an out-branching B + in-branching − which are arc-disjoint (we call such branchings a good pair). This is best possible in terms the as there infinitely many strong digraphs with arbitrarily high minimum in- out-degrees have no pair. The result settles conjecture by Thomassen for 2. on 6 vertices pair gi...