建立以丝素量为基础的蚕丝质量考核体系探讨

分析了现行蚕丝质量考核体系存在的不足,探讨了将丝素含量纳入蚕丝质量考核体系的必要性和可行性,提出了将丝素含量纳入蚕丝质量考核体系的方法。     

Adults' response to Massachusetts anti-tobacco television advertisements: impact of viewer and advertisement characteristics

OBJECTIVE: To assess adults' receptivity to the Massachusetts television anti-tobacco campaign. Reactions were examined as a function of respondents' demographics, baseline tobacco control attitudes, changes in smoking status during the campaign, and advertisements' affective qualities. DESIGN: A random digit dial telephone survey in 1993 at the start of the media campaign and re-interview in 1996 of respondents to the baseline survey. PARTICIPANTS: Respondents were 1544 adults who completed the baseline and follow up interview. INTERVENTION: By the time the follow up survey was completed, approximately $49 million had been spent on the media campaign. Approximately 66 spots had been aired. MAIN OUTCOME MEASURES: Reported exposure to television advertisements; perceived effectiveness of nine specific advertisements each. RESULTS: 56% of respondents reported seeing anti-tobacco advertisements at least once a week during the preceding three years. The average effectiveness rating for all advertisements recalled on a 0-10 scale was 7.29, and did not differ by smoking status group. Advertisements eliciting strong negative emotions (sadness and fear) were rated most effective by quitters, non-smokers, and by smokers who at baseline were planning to quit soon. Humorous, entertaining advertisements were seen as ineffective by all groups. CONCLUSION: The Massachusetts anti-tobacco campaign achieved high levels of penetration into the population and was well received by both smokers and non-smokers. The results suggest that advertisements depicting suffering as a result of tobacco use may be instrumental in promoting cessation or reinforcing the decision to quit. Further research is needed to lend additional support to the link between perceived effectiveness and smoking behaviour change.     

Ingestion of tall larkspur by cattle

Tall larkspur (Delphinium spp.) is a palatable but toxic poisonous plant in the western United States. The toxins in tall larkspur are diterpenoid alkaloids. We examined the influences of food flavor and postingestive consequences on consumption of a 33% larkspur pellet during 30-min feeding periods for five days using esophageally fistulated cattle that were sham-fed larkspur pellets. Consumption by the sham-fed group was compared to a control group fed alfalfa pellets, and a larkspur group fed only larkspur pellets. Sham-fed cattle did not decrease (P > 0.1) feed consumption compared to controls, indicating no significant difference in food flavor. The larkspur group decreased (P < 0.05) feed consumption by 41% relative to controls and by 31% relative to sham-fed animals (P = 0.08). This reduction in feed consumption indicates the adverse postingestive consequences of tall larkspur ingestion, as the larkspur group apparently developed a conditioned taste aversion to the larkspur pellet. Even though these animals were averted to the pellets, they showed none of the classical signs of intoxication from ingestion of tall larkspur.This research was supported in part by the Utah Agricultural Experiment Station, Utah State University, Logan, Utah 84322. Approved as journal article No. 3846.     

基于Skinner操作条件反射的两轮机器人自平衡控制

针对两轮自平衡机器人的运动平衡控制问题,采用了基于Skinner操作条件反射理论的自回归神经网络学习算法作为机器人的学习机制,利用自回归神经网络对评价函数进行逼近,以实现对行为决策的优化,从而使机器人能够在无需外部环境模型的情况下,通过学习和训练,获得像人或动物一样的自主学习技能,解决了两轮机器人的运动平衡控制问题.最后分别在无扰动和有扰动的两种状态下设计了仿真实验并进行了比较.结果表明,该操作条件反射学习机制具有较快的自主平衡控制技能和较好的鲁棒性能,体现了较高的理论研究意义和工程应用价值.     

Associative Olfactory Learning of Honeybees to Differential Rewards in Multiple Contexts—Effect of Odor Component and Mixture Similarity

Discrimination among differentially rewarding flowers allows honeybees to maximize their foraging efficiency. We studied how honeybees are able to relate to differential positive rewards when the odor representations are either structurally dissimilar, structurally similar (or form a substrate–product duo in planta), or form a binary mixture sharing a common constituent. Bees were tested both in conditioning of the proboscis-extension response (PER) and in a free-flying context. Our results point to honeybees using olfactory associative learning to differentiate between two positively rewarded odors. In PER, subjects discriminated best between dissimilar odors; they initially generalized between similar odors, but eventually learned to discriminate between them. The discrimination between mixtures sharing a common constituent remained poor. Likewise, the difference in visits to low- and high-rewarding flowers of free-flying bees was greater for dissimilar odors than for binary mixtures sharing a common constituent. Consequences of the operant conditioning nature of the free-flying context are discussed.