We report evidence for a strongly geometry-dependent substituent effect. The rate constants for H-D exchange of the R-hydrogens, (kexch)OR, in a set of 19 !-alkoxy sulfones of known, fixed (or strongly preferred) H-CR-C!-OR torsion angles have been measured. Those of corresponding model compounds lacking the alkoxy group, (kexch)model, were also measured, thereby providing the ratio, kN ) (kexc...

Entanglement in fixed fishing gear affects whales worldwide. In the United States, deaths of North Atlantic right (Eubalaena glacialis) and humpback whales (Megaptera novaeangliae) have exceeded management limits for decades. We examined live and dead whales entangled in fishing gear along the U.S. East Coast and the Canadian Maritimes from 1994 to 2010. We recorded whale species, age, and inju...

Learning to avoid threats in the environment is highly adaptive. However, sometimes a dysregulation of fear memories processing may underlie fear-related disorders. Despite recent advances, a major question of how to effectively attenuate persistent fear memories in a safe manner remains unresolved. Here we show experiments employing a behavioural tool to target a specific time window after tra...

This paper presents an O(1.2738 + kn)-time polynomialspace parameterized algorithm for Vertex Cover improving the previous O(1.286+kn)-time polynomial-space upper bound by Chen, Kanj, and Jia. The algorithm also improves the O(1.2745k+kn)-time exponentialspace upper bound for the problem by Chandran and Grandoni.

We construct a uniform covering of 2-paths by 4-paths in Kn for all n 2:: 5, i.e., we construct a set S of 4-paths in Kn having the property that each 2-path in Kn lies in exactly one 4-path in S for all 11, 2:: 5.

The prime and primitive spectra of Oq(k), the multiparameter quantized coordinate ring of affine n-space over an algebraically closed field k, are shown to be topological quotients of the corresponding classical spectra, specO(kn) and maxO(kn) ≈ kn, provided the multiplicative group generated by the entries of q avoids −1.