Relation between self-reported affect and drug urges and cravings in continuing and withdrawing smokers.

Investigated, in 2 experiments, the effects of withdrawal and stress on the affective correlates of urges to smoke. In both, habitual cigarette smokers were divided into continuing and withdrawing smoker groups. In the 1st study, 44 adults reported current mood, urge, and expectations over a 24-hr period. In the 2nd, a controlled laboratory study, urge, affect, and physiological data were obtained from continuing and withdrawing groups (N?=?64) exposed to high- or low-stress conditions. Urges among withdrawing smokers were positively associated with negative affect and negatively associated with positive affect; continuing smokers reported urges that were directly associated with positive affect and unrelated to negative affect. Stress and withdrawal produced urge and self-reports that were related to negative affect. Moreover, Ss who smoked after exposure to withdrawal and stress reported greater pleasure and arousal than did other Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Linear-time algorithms for eliminating claws in graphs

Since many -complete graph problems are polynomial-time solvable when restricted to claw-free graphs, we study the problem of determining the distance of a given graph to a claw-free graph, considering vertex elimination a measure. Claw-free Vertex Deletion (CFVD) consists of determining the minimum number of vertices to be removed from a graph such that the resulting graph is claw-free. Although CFVD is -hard in general and recognizing claw-free graphs is still a challenge, where the current best deterministic algorithm for a graph G consists of performing executions of the best algorithm for matrix multiplication, we present linear-time algorithms for CFVD on weighted block graphs and weighted graphs with bounded treewidth. Furthermore, we show that this problem on forests can be solved in linear time by a simpler algorithm, and we determine the exact values for full k-ary trees. On the other hand, we show that CFVD is -hard even when the input graph is a split graph. We also show that the problem is hard to be approximated within any constant factor better than 2, assuming the unique games conjecture.