Methods of proof

Although the annotation of the complete genome sequence ofMycoplasma pneumoniaedid not reveal a bacterial type I signal peptidase (SPase I) we showed experimentally that such an activity must exist in this bacterium, by determining the N-terminus of the N-terminal gene product P40 of MPN142, formerly called ORF6 gene. Combining mass spectrometry with a method for sulfonating specifically the free amino terminal group of proteins, the cleavage site for a typical signal peptide was located between amino acids 25 and 26 of the P40 precursor protein. ...

0p awards 06-04-2013 48 3   Download

The goal of this paper is to describe all closed, aspherical Riemannian manifolds M whose universal covers M have a nontrivial amount of symmetry. By this we mean that Isom(M ) is not discrete. By the well-known theorem of Myers-Steenrod [MS], this condition is equivalent to [Isom(M ) : π1 (M )] = ∞. Also note that if any cover of M has a nondiscrete isometry group, then so does its universal cover M . Our description of such M is given in Theorem 1.2 below. The proof of this theorem uses methods from Lie theory, harmonic maps,...

27p dontetvui 17-01-2013 54 7   Download

We study the large scale geometry of the mapping class group, MCG(S). Our main result is that for any asymptotic cone of MCG(S), the maximal dimension of locally compact subsets coincides with the maximal rank of free abelian subgroups of MCG(S). An application is a proof of Brock-Farb’s Rank Conjecture which asserts that MCG(S) has quasi-flats of dimension N if and only if it has a rank N free abelian subgroup. (Hamenstadt has also given a proof of this conjecture, using different methods.

24p dontetvui 17-01-2013 69 7   Download

We study the integral points on surfaces by means of a new method, relying on the Schmidt Subspace Theorem. This method was recently introduced in [CZ] for the case of curves, leading to a new proof of Siegel’s celebrated theorem that any affine algebraic curve defined over a number field has only finitely many S-integral points, unless it has genus zero and not more than two points at infinity. Here, under certain conditions involving the intersection matrix of the divisors at infinity, we shall conclude that the integral points on a surface all lie on a curve. We shall...

23p tuanloccuoi 04-01-2013 53 6   Download

Dedicated to the memory of Barry Johnson, 1937–2002 Abstract The main result of this paper is that the k th continuous Hochschild cohomology groups H k (M, M) and H k (M, B(H)) of a von Neumann factor M ⊆ B(H) of type II1 with property Γ are zero for all positive integers k. The method of proof involves the construction of hyperfinite subfactors with special properties and a new inequality of Grothendieck type for multilinear maps. We prove joint continuity in the · 2 -norm of separately ultraweakly continuous multilinear maps, and combine these results to reduce to...

26p tuanloccuoi 04-01-2013 45 6   Download

MULTIPLICITY RESULTS FOR A CLASS OF ASYMMETRIC WEAKLY COUPLED SYSTEMS OF SECOND-ORDER ORDINARY DIFFERENTIAL EQUATIONS FRANCESCA DALBONO AND P. J. MCKENNA Received 1 November 2004 We prove the existence and multiplicity of solutions to a two-point boundary value problem associated to a weakly coupled system of asymmetric second-order equations. Applying a classical change of variables, we transform the initial problem into an equivalent problem whose solutions can be characterized by their nodal properties.

23p sting12 10-03-2012 40 7   Download

A combinatorial bijection between k-edge colored trees and colored Pr¨ufer codes for labelled trees is established. This bijection gives a simple combinatorial proof for the number k(n − 2)!nk−n n−2
of k-edge colored trees with n vertices.A k-edge colored tree is a labelled tree whose edges are colored from a set of k colors such that any two edges with a common vertex have different colors

7p thulanh5 12-09-2011 84 7   Download