Infanticide by males is a common phenomenon in mammals, especially primates, as lactation lasts much longer than gestation in many species. Usually, infanticidal episodes occur soon after group takeovers, and are trad...Infanticide by males is a common phenomenon in mammals, especially primates, as lactation lasts much longer than gestation in many species. Usually, infanticidal episodes occur soon after group takeovers, and are traditionally considered a male reproductive strategy （i.e., support the sexual selection hypothesis, Hrdy, 1974）. To verify the validity of this conception, we observed one group of Franqois＇ langurs in the Nonggang Nature Reserve, China, between August 2003 and July 2004. During the study period, a Francois＇ langur female with the youngest infant in the group was attacked three times by immigrating males, and later disappeared by the third day after the final attack. We suggest that these attacks on the female-infant dyad represent infanticide attempts by males, and may be the cause of the adult female and her infant＇s disappearance. Presumably, that female dispersed with her infant to avoid infanticide and was not killed. Though these observations do not completely verify the sexual selection hypothesis, they are not inconsistent with it.展开更多
In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a ...In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split Hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.展开更多
Previous studies on the relationship between exPosure to televised violence and viewers＇ aggressive behaviours have produced mixed results. Some studies have found significant effect sizes while others have found low...Previous studies on the relationship between exPosure to televised violence and viewers＇ aggressive behaviours have produced mixed results. Some studies have found significant effect sizes while others have found low and non-significant effect sizes. Television effects scholars have postulated that these mixed results are caused by the inconsistencies of research methodology employed and the inability to control major mediating variables in the studies. The present study is designed with the objectives to overcome these shortcomings. The respondents for this study were 514 students aged between 13 and 18 from 10 schools in the State of Perak, Malaysia. Exploratory data analyses provided evidence that the employed instruments achieved sound psychometric properties. Hypotheses testing suggested that exposure to the Contents of Television Violence （TVCN） did not have a direct relationship with adolescents＇ aggressive behaviours; instead, Contextual Features of Television Violence （TVCX） totally mediated this relationship. Some other mediating variables then mediated totally and some mediated partially the relationship between TVCX and adolescents＇ aggressive behaviours. To conclude, this study provides valuable information for parents, the television industry, and the policy makers in recognizing pro-violent and anti-violent features of television violence programmes for Malaysian school-going adolescents. It also provides a new perspective for future studies of television violence in Malaysia.展开更多
Circular patterns, or eyespots, are common anti-predator features in a variety of animals. Two defensive functions have been documented： large eyespots may intimidate predators, whereas smaller marginal eyespots may ...Circular patterns, or eyespots, are common anti-predator features in a variety of animals. Two defensive functions have been documented： large eyespots may intimidate predators, whereas smaller marginal eyespots may divert attacks. However, a given eyespot potentially serves both functions, possibly depending on the predator＇s size and/or experience. Naive predators are potentially more likely to misdirect their attacks towards eyespots; alternatively, their typically smaller size would make them more intimidated by the same eyespots. Here we test how juvenile and sub-adult naive chickens respond to a single eyespot on a butterfly＇s wing. We presented the birds with dead wall brown butterflies, Lasiommata megera, that had their apical eyespot visible or painted over. We assessed the birds＇ responses＇ by （i） scoring their intimidation reaction, （ii） whether they uttered alarm calls and, （iii） if they attacked the butterfly and where they targeted their attacks. Results show that both age categories received higher intimidation scores when offered a butterfly with a visible eyespot. Juveniles were more intimidated by the butterfly than the sub-adults： they received higher intimidation scores and were more prone to utter alarm calls. Moreover, only sub-adults at- tacked and did so by preferentially attacking the butterfly＇s anterior. We demonstrate an intimidating effect of the type of eyespot that has previously been shown only to divert attacks. We suggest that one and the same eyespot may serve two functions relative to different predators; however, further experiments are needed to disentangle the role of predator identity and its link to size, on- togeny and experience [Current Zoology 61 （4）： 749-757, 2015].展开更多
基金supported by National Nature Science Foundation of China (31172122)Guangxi Nature Science Foundation (2012GXNSFAA053039)
文摘Infanticide by males is a common phenomenon in mammals, especially primates, as lactation lasts much longer than gestation in many species. Usually, infanticidal episodes occur soon after group takeovers, and are traditionally considered a male reproductive strategy （i.e., support the sexual selection hypothesis, Hrdy, 1974）. To verify the validity of this conception, we observed one group of Franqois＇ langurs in the Nonggang Nature Reserve, China, between August 2003 and July 2004. During the study period, a Francois＇ langur female with the youngest infant in the group was attacked three times by immigrating males, and later disappeared by the third day after the final attack. We suggest that these attacks on the female-infant dyad represent infanticide attempts by males, and may be the cause of the adult female and her infant＇s disappearance. Presumably, that female dispersed with her infant to avoid infanticide and was not killed. Though these observations do not completely verify the sexual selection hypothesis, they are not inconsistent with it.
基金Project(2010CB732004)supported by National Basic Research Program of ChinaProject(50934006)supported by the National Natural Science Foundation of China
文摘In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split Hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.
文摘Previous studies on the relationship between exPosure to televised violence and viewers＇ aggressive behaviours have produced mixed results. Some studies have found significant effect sizes while others have found low and non-significant effect sizes. Television effects scholars have postulated that these mixed results are caused by the inconsistencies of research methodology employed and the inability to control major mediating variables in the studies. The present study is designed with the objectives to overcome these shortcomings. The respondents for this study were 514 students aged between 13 and 18 from 10 schools in the State of Perak, Malaysia. Exploratory data analyses provided evidence that the employed instruments achieved sound psychometric properties. Hypotheses testing suggested that exposure to the Contents of Television Violence （TVCN） did not have a direct relationship with adolescents＇ aggressive behaviours; instead, Contextual Features of Television Violence （TVCX） totally mediated this relationship. Some other mediating variables then mediated totally and some mediated partially the relationship between TVCX and adolescents＇ aggressive behaviours. To conclude, this study provides valuable information for parents, the television industry, and the policy makers in recognizing pro-violent and anti-violent features of television violence programmes for Malaysian school-going adolescents. It also provides a new perspective for future studies of television violence in Malaysia.
文摘Circular patterns, or eyespots, are common anti-predator features in a variety of animals. Two defensive functions have been documented： large eyespots may intimidate predators, whereas smaller marginal eyespots may divert attacks. However, a given eyespot potentially serves both functions, possibly depending on the predator＇s size and/or experience. Naive predators are potentially more likely to misdirect their attacks towards eyespots; alternatively, their typically smaller size would make them more intimidated by the same eyespots. Here we test how juvenile and sub-adult naive chickens respond to a single eyespot on a butterfly＇s wing. We presented the birds with dead wall brown butterflies, Lasiommata megera, that had their apical eyespot visible or painted over. We assessed the birds＇ responses＇ by （i） scoring their intimidation reaction, （ii） whether they uttered alarm calls and, （iii） if they attacked the butterfly and where they targeted their attacks. Results show that both age categories received higher intimidation scores when offered a butterfly with a visible eyespot. Juveniles were more intimidated by the butterfly than the sub-adults： they received higher intimidation scores and were more prone to utter alarm calls. Moreover, only sub-adults at- tacked and did so by preferentially attacking the butterfly＇s anterior. We demonstrate an intimidating effect of the type of eyespot that has previously been shown only to divert attacks. We suggest that one and the same eyespot may serve two functions relative to different predators; however, further experiments are needed to disentangle the role of predator identity and its link to size, on- togeny and experience [Current Zoology 61 （4）： 749-757, 2015].
