Let K be an arbitrary field of characteristic p > 0 and D(Pn) be the ring of differential operators on a polynomial algebra Pn in n variables. A long anticipated analogue of the inequality of Bernstein is proved for the ring D(Pn). In fact, three different proofs are given of this inequality (two of which are essentially characteristic free): the first one is based on the concept of the filter ...

In this paper, we show that the domination number D of a random graph enjoys as sharp a concentration as does its chromatic number χ. We first prove this fact for the sequence of graphs {G(n, pn}, n → ∞, where a two point concentration is obtained with high probability for pn = p (fixed) or for a sequence pn that approaches zero sufficiently slowly. We then consider the infinite graph G(Z+, p),...

Let hom(G,H) denote the number of homomorphisms from a graph G to a graph H. In this paper we study the number of homomorphisms of trees into a path, and prove that hom(Pm, Pn) ≤ hom(Tm, Pn) ≤ hom(Sm, Pn), where Tm is any tree on m vertices, and Pm and Sm denote the path and star on m vertices, respectively. This completes the study of extremal problems concerning the number of homomorphisms be...

Phase noise (PN) can cause severe link performance degradation in orthogonal frequency division multiplexing (OFDM) systems. In this work, we propose an efficient PN mitigation algorithm where the PN statistics are used to obtain more accurate channel estimates. As opposed to prior PN mitigation schemes that assume perfect channel information and/or require abundant reference symbols, the propo...

OBJECTIVE We describe a new strategy to promote axonal regeneration after subacute or chronic spinal cord injury consisting of intramedullary implantation of chitosan guidance channels containing peripheral nerve (PN) grafts. METHODS Chitosan channels filled with PN grafts harvested from green fluorescent protein rats were implanted in the cavity 1 week (subacute) or 4 weeks (chronic) after 5...

Addition to Lemma 81. In [1], § 4, there is a variant of the matrix formula (64) for the simple continued fraction of a real number. Given integers a0, a1, . . . with ai > 0 for i ≥ 1 and writing, for n ≥ 0, as usual, pn/qn = [a0, a1, . . . , an], one checks, by induction on n, the two formulae ( 1 a0 0 1 )( 1 0 a1 1 ) · · · ( 1 an 0 1 ) = ( pn−1 pn qn−1 qn ) if n is even ( 1 a0 0 1 )( 1 0 a1 1...

We classify, up to homeomorphism, all closed manifolds having the homotopy type of a connected sum of two copies of real projective n-space. 1. Statement of results Let P = Pn(R) be real projective n-space. López de Medrano [LdM71] and C.T.C. Wall [Wal68, Wal99] classified, up to PL homeomorphism, all closed PL manifolds homotopy equivalent to P when n > 4. This was extended to the topological ...

OBJECTIVE Few tests of functional motor behavior are useful for rapidly screening people for lower extremity peripheral neuropathy. The goal of this study was to improve the widely used tandem walking (TW) test. METHODS We tested "normal" (control) adult and ambulatory patients with peripheral neuropathy (PN) with their eyes open and eyes closed while they performed TW on industrial carpeting...