A differential poset is a partially ordered set with raising and lowering operators U and D which satisfy the commutation relation DU−UD = rI for some constant r. This notion may be generalized to deal with the case in which there exist sequences of constants {qn}n≥0 and {rn}n≥0 such that for any poset element x of rank n, DU(x) = qnUD(x)+rnx. Here, we introduce natural raising and lowering ope...

A link between matroid theory and p-branes is discussed. The Schild type action for p-branes and matroid bundle notion provide the two central structures for such a link. We use such a connection to bring the duality concept in matroid theory to p-branes physics. Our analysis may be of particular interest in M-theory and in matroid bundle theory.

A graph G∗ is 1-edge fault-tolerant with respect to a graph G, denoted by 1-EFT(G), if every graph obtained by removing any edge from G∗ contains G. A 1-EFT(G) graph is optimal if it contains the minimum number of edges among all 1-EFT(G) graphs. The kth ladder graph, Lk , is defined to be the cartesian product of the Pk and P2 where Pn is the n-vertex path graph. In this paper, we present seve...

The pattern of well-known states in q 4 spectroscopy is quite different from CE and b 6. Because of the position of the heavy quark thresholds, the JP = lradial excitation ladder is well studied by formation in e+eexperiments and the L = 1 triplets are seen in 7 transitions. In the q p sector, however, the “leading” high-spin multiplets are best known (in both natural and unnatural f) and, sinc...

It has been stated that the male mouse retains both the Whitten effect (control of the oestrous cycle) and the Bruce effect (control of implantation) to some extent after castration (Bruce, 1959, 1960; Parkes & Bruce, 1961). Subsequent observations failed to confirm either of these early claims. Further experiments on the relation between the gonads and pheromones have now been completed. The m...

Cytokinesis involves the formation of a cleavage furrow, followed by abscission, the cutting of the midbody channel, the final bridge between dividing cells. Recently, the midbody ring became known as central for abscission, but its regulation remains enigmatic. Here, we identify BRUCE, a 528 kDa multifunctional protein, which processes ubiquitin-conjugating activity, as a major regulator of ab...

Let G be a connected noncompact simple Hermitian symmetric group with nite center. Let H() denote the geometric realization of an irreducible unitary highest weight representation with highest weight. Then H() consists of vector-valued holomorphic functions on G=K and the action of G on H() is given in terms of a factor of automorphy. For highest weights corresponding to ladder representations,...