In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environm...In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments （enriched, social and isolated conditions）. After 8 weeks, fear conditioning （characterized by percentage of freezing） was observed and analyzed, and rats＇ weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that： （1） Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; （2） Enriched and isolated conditions influenced rat＇s weight significantly; （3） Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.展开更多
An algorithm for solving the satisfiability problem is presented. It isproceed that this algorithm solves 2-SAT and Horn-SAT in linear time and k-positiveSAT (in which every clause contains at most k positive literals...An algorithm for solving the satisfiability problem is presented. It isproceed that this algorithm solves 2-SAT and Horn-SAT in linear time and k-positiveSAT (in which every clause contains at most k positive literals) ill time O(F.),where F is the length of input F, n is the number of atoms occurring in F, and k isthe greatest real number satisfying the equation x = 2-. Compared with previousresults, this nontrivial upper bound on time complexity could only be obtained fork-SAT, which is a subproblem of k-positive SAT.展开更多
基金National Natural Science Foundation of China(30770689)Scientific Research Fund of Hunan Provincial Education Department (05B045)National Basic Research Program of China (2002CB410803-04)
文摘In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments （enriched, social and isolated conditions）. After 8 weeks, fear conditioning （characterized by percentage of freezing） was observed and analyzed, and rats＇ weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that： （1） Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; （2） Enriched and isolated conditions influenced rat＇s weight significantly; （3） Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.
文摘An algorithm for solving the satisfiability problem is presented. It isproceed that this algorithm solves 2-SAT and Horn-SAT in linear time and k-positiveSAT (in which every clause contains at most k positive literals) ill time O(F.),where F is the length of input F, n is the number of atoms occurring in F, and k isthe greatest real number satisfying the equation x = 2-. Compared with previousresults, this nontrivial upper bound on time complexity could only be obtained fork-SAT, which is a subproblem of k-positive SAT.
