DNA helicases catalyze the essential process of unwinding duplex DNA to form the single-stranded DNA intermediates required for DNA metabolic processes including replication, recombination, and repair. Most cells, possibly all, encode multiple helicases that function selectively in different processes, although some helicases can complement each other in vivo. Thus, although Escherichia coli ca...

Developing B lymphocytes undergo V(D)J recombination to assemble germ-line V, D, and J gene segments into exons that encode the antigen-binding variable region of Ig heavy (H) and light (L) chains. IgH and IgL chains associate to form the B-cell receptor (BCR), which, upon antigen binding, activates B cells to secrete BCR as an antibody. Each of the huge number of clonally independent B cells e...

Let G be a countably infinite group and (X,μ) a standard non-atomic probability space. We denote by A(G,X, μ) the space of measure preserving actions of G on (X,μ) with the weak topology. If a,b ∈ A(G,X, μ), we say that a is weakly contained in b, in symbols a b, if a is in the closure of the set of isomorphic copies of b (i.e., it is in the closure of the orbit of b under the action of the aut...

This paper introduces a new b-rep (boundary representation) data structure, called AIF (Adjacency and Incidence Framework). It is concise and enables fast access to topological information. Its conciseness results from the fact that it is an orientable, but not an oriented, data structure, i.e. an orientation can be topologically induced as necessary in many applications. It is an optimal 9 4 C...

We present a novel integrated approach to reverse engineering point clouds by producing fully editable feature-based Boundary Representation (B-rep) models. We use point cloud morphology analysis techniques to extract features from a 3D point cloud. We then reconstruct the boundary contours of features using a fast and efficient fitting approach employing a sequence of piecewise rational Bezier...

Up to face extrusion (UTFE) is an effective operation to extrude the profile from a sketch plane to a selected face. An up to face extrusion algorithm is presented in this paper. The algorithm first generates the trimmed extrusion through a simple body-surface Boolean operation method, and then generates the resultant solid through a regularized Boolean operation between the original solid and ...

S-reps are form of skeletal representation that capture the interior of an object in a way that a) provides an object-related coordinate system for the points in the object interior and near exterior; b) supports statistics on object geometry. This document teaches 1) What the s-rep computer representation is. 2) How to prepare object descriptions implying an object boundary for being fit by an...