Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in large...Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in larger-seeded plants.Size-biased dispersal is evident in many oaks(Quercus)and is true both across and within species.Here,we predict that intraspecifc variation in seed size also influences acorn dispersal by the Blue Jay(Cyanocitta cristata Linnaeus),but in an opposite manner.Blue Jays are gape-limited and selectively disperse smaller acorn species(e.g.pin oaks[Quercus palustris Münchh]),but often carry several acorns in their crop during a single dispersal event.We predict that jays foraging on smaller acorns will load more seeds per trip and disperse seeds to greater distances than when single acorns are carried in the bill.To test this,we presented free-ranging Blue Jays with pin oak acorns of different sizes over a 2-year period.In each of 16 experimental trials,we monitored the birds at a feeding station with remote cameras and determined the number of acorns removed and the distance acorns were dispersed when cached.Jays were significantly more likely to engage in multiple seed loading with smaller seeds in both years of the study.During the second year,these smaller acorns were dispersed farther than larger acorns,and during the first year,larger acorns were dispersed farther,revealing an inconsistent response to seed size during our study.We suggest that in some circumstances,multiple seed loading by Blue Jays may favor dispersal in some plant species.展开更多
为了实现工业相机对动态目标的准确、实时跟踪,提出了基于卡尔曼滤波的算法。通过创建背景模型来估计出当前背景,进而得到前景区域,并对前景区域进行相关处理,最后通过计算补集得到更新后的背景。此方法能根据不同场景信息调整前景与背...为了实现工业相机对动态目标的准确、实时跟踪,提出了基于卡尔曼滤波的算法。通过创建背景模型来估计出当前背景,进而得到前景区域,并对前景区域进行相关处理,最后通过计算补集得到更新后的背景。此方法能根据不同场景信息调整前景与背景阈值,减弱背景区域造成的噪声影响,实时地根据场景变化快速、自动更新背景,并对每一位置的像素进行背景估计。通过在VS2010平台上结合JAI软件开工具包(Software Development Kit,SDK)调用Halcon函数库实现了卡尔曼滤波动态跟踪,其中JAI SDK用于开发千兆网相机,几乎支持所有千兆网相机。实验结果表明,该算法能够实现对目标的实时动态跟踪,实时性强,准确度高。展开更多
We assessed habitat preference and population status of the Sichuan Jay (Perisoreus internigrans),a poorly known Chinese endemic bird,at two sites (Zhuoni and Jiuzhaigou) in the Qinghai-Tibetan plateau between 2001 an...We assessed habitat preference and population status of the Sichuan Jay (Perisoreus internigrans),a poorly known Chinese endemic bird,at two sites (Zhuoni and Jiuzhaigou) in the Qinghai-Tibetan plateau between 2001 and 2004.Mean group size was 3.8 jays.Each group occupied a mean home range of 42.0 ha during the breeding season,and the mean internest distance was 2.7 km.These data indicated that the jays used less than ten percent of the available habitats and occurred at an overall density of only 0.6 jays per km2.Radio-tracked Sichuan Jays had a strong preference for mature montane coniferous forests and avoided areas dominated by shrubs,while the utilization of young conifers,grassland,and human residential habitat types did not differ significantly from the values expected from the home-range availabilities of these habitats generally.展开更多
The Xinjiang Ground Jay (Podoces biddulphi) is a bird species endemic to China. It has a restricted range, living only in the Taklimakan Desert, southern part of Xinjiang. So far, little information has been known of ...The Xinjiang Ground Jay (Podoces biddulphi) is a bird species endemic to China. It has a restricted range, living only in the Taklimakan Desert, southern part of Xinjiang. So far, little information has been known of the status and ecology of the bird in the world. Since 1988, I have been taking field investigations on the distribution, population size and breeding ecology of the Xinjiang Ground Jay in the desert.In this thesis, the desertification in relation to the eastward expansion of the ground jays was discussed.展开更多
Considering a recent proposition on this journal that the endemic Xinjiang Ground Jay (Podoces biddulphi) would be expanding its range to Qinghai and Gansu, a previously overlooked statement has been found in old lite...Considering a recent proposition on this journal that the endemic Xinjiang Ground Jay (Podoces biddulphi) would be expanding its range to Qinghai and Gansu, a previously overlooked statement has been found in old literature suggesting that this species has occurred in Gansu at least since the 19th century. The phreatophytic vegetation this desert bird requires likely constrains its distribution. Therefore, although the desert expansion the current global climate warming is producing may make the Xinjiang Ground Jay expand its range, only well-preserved desert might be colonized. Future research in apparently suitable areas, at present inhabited by the Mongolian Ground Jay (P. hendersoni) instead, might make the ecology of these two mutually exclusive species better understood.展开更多
In evolutionary theory,we generally believe that the evolution of life is from simple to complex,from single to diverse,and from lower to higher.Thus,the idea of evolutionary progress appears obvious.However,in contem...In evolutionary theory,we generally believe that the evolution of life is from simple to complex,from single to diverse,and from lower to higher.Thus,the idea of evolutionary progress appears obvious.However,in contemporary academic circles,some biologists and philosophers challenge this idea.Among them,Gould is the most influential.This paper first describes Gould’s seven arguments against evolutionary progress,i.e.,the human arrogance argument,anthropocentric argument,no inner thrust argument,no biological base argument,extreme contingency argument,statistical error argument,and bacteria(other than human beings)ruling the earth argument.Gould’s arguments against evolutionary progress have great influence in contemporary evolutionary theory.Thus,it is necessary to conduct a careful philosophical analysis of each of Gould’s arguments to reveal his philosophical mistakes.This research contends that Gould’s arguments against evolutionary progress are invalid.展开更多
After a series of comparison between Jay Gatsby——the protagonist of "The Great Gatsby"and Duddy kravitz——the protagonist of "The Apprenticeship of Duddy kravitz",the authorof this essay gets su...After a series of comparison between Jay Gatsby——the protagonist of "The Great Gatsby"and Duddy kravitz——the protagonist of "The Apprenticeship of Duddy kravitz",the authorof this essay gets such a conclusion,that Jay Gatsby was a pure idealist,while Duddykravitz a vulgar materialist.展开更多
犹太籍长住美国纽约摄影家 Jay Maisel 的摄影展使人印象深刻。他利用光线和姿势创造了无数用于广告、杂志和团体报道的难忘形象。他为全体工业界所敬重,他的作品进入了无数教科书,以及成为私人和团体的收藏品。在他因其出色的创作所获...犹太籍长住美国纽约摄影家 Jay Maisel 的摄影展使人印象深刻。他利用光线和姿势创造了无数用于广告、杂志和团体报道的难忘形象。他为全体工业界所敬重,他的作品进入了无数教科书,以及成为私人和团体的收藏品。在他因其出色的创作所获得的奖项中,包括美国媒体摄影家协会与专业摄影家协会颁发的"美国时代成就奖",以及美国媒体摄影家协会的"年度摄影家奖"、国际摄影中心的"无极奖",并且进入了纽约市艺术家俱乐部的"名人堂"。作为职业联合会和耶鲁大学的一员,Jay Maisel展开更多
基金The authors recognize financial support of the US National Science Foundation(DEB-0642434 and DEB-0642504,RS,MS,NL,the Howard Hughes Medical Institute(AB,MS)The Fenner Endowment of the Department of Biology of Wilkes University(AB,MK,MS).
文摘Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in larger-seeded plants.Size-biased dispersal is evident in many oaks(Quercus)and is true both across and within species.Here,we predict that intraspecifc variation in seed size also influences acorn dispersal by the Blue Jay(Cyanocitta cristata Linnaeus),but in an opposite manner.Blue Jays are gape-limited and selectively disperse smaller acorn species(e.g.pin oaks[Quercus palustris Münchh]),but often carry several acorns in their crop during a single dispersal event.We predict that jays foraging on smaller acorns will load more seeds per trip and disperse seeds to greater distances than when single acorns are carried in the bill.To test this,we presented free-ranging Blue Jays with pin oak acorns of different sizes over a 2-year period.In each of 16 experimental trials,we monitored the birds at a feeding station with remote cameras and determined the number of acorns removed and the distance acorns were dispersed when cached.Jays were significantly more likely to engage in multiple seed loading with smaller seeds in both years of the study.During the second year,these smaller acorns were dispersed farther than larger acorns,and during the first year,larger acorns were dispersed farther,revealing an inconsistent response to seed size during our study.We suggest that in some circumstances,multiple seed loading by Blue Jays may favor dispersal in some plant species.
文摘为了实现工业相机对动态目标的准确、实时跟踪,提出了基于卡尔曼滤波的算法。通过创建背景模型来估计出当前背景,进而得到前景区域,并对前景区域进行相关处理,最后通过计算补集得到更新后的背景。此方法能根据不同场景信息调整前景与背景阈值,减弱背景区域造成的噪声影响,实时地根据场景变化快速、自动更新背景,并对每一位置的像素进行背景估计。通过在VS2010平台上结合JAI软件开工具包(Software Development Kit,SDK)调用Halcon函数库实现了卡尔曼滤波动态跟踪,其中JAI SDK用于开发千兆网相机,几乎支持所有千兆网相机。实验结果表明,该算法能够实现对目标的实时动态跟踪,实时性强,准确度高。
基金supported by grants of the National Natural Science Foundation of China(30270202,39870103)Chinese Academy of Sciences(kscx2-yw-z-1021)
文摘We assessed habitat preference and population status of the Sichuan Jay (Perisoreus internigrans),a poorly known Chinese endemic bird,at two sites (Zhuoni and Jiuzhaigou) in the Qinghai-Tibetan plateau between 2001 and 2004.Mean group size was 3.8 jays.Each group occupied a mean home range of 42.0 ha during the breeding season,and the mean internest distance was 2.7 km.These data indicated that the jays used less than ten percent of the available habitats and occurred at an overall density of only 0.6 jays per km2.Radio-tracked Sichuan Jays had a strong preference for mature montane coniferous forests and avoided areas dominated by shrubs,while the utilization of young conifers,grassland,and human residential habitat types did not differ significantly from the values expected from the home-range availabilities of these habitats generally.
基金supported by the Science Supporting Project of National Ministry of Science and Technology(2008BAC39B04)the National Natural Science Foundation of China(30270211,30470262,30970340)
文摘The Xinjiang Ground Jay (Podoces biddulphi) is a bird species endemic to China. It has a restricted range, living only in the Taklimakan Desert, southern part of Xinjiang. So far, little information has been known of the status and ecology of the bird in the world. Since 1988, I have been taking field investigations on the distribution, population size and breeding ecology of the Xinjiang Ground Jay in the desert.In this thesis, the desertification in relation to the eastward expansion of the ground jays was discussed.
文摘Considering a recent proposition on this journal that the endemic Xinjiang Ground Jay (Podoces biddulphi) would be expanding its range to Qinghai and Gansu, a previously overlooked statement has been found in old literature suggesting that this species has occurred in Gansu at least since the 19th century. The phreatophytic vegetation this desert bird requires likely constrains its distribution. Therefore, although the desert expansion the current global climate warming is producing may make the Xinjiang Ground Jay expand its range, only well-preserved desert might be colonized. Future research in apparently suitable areas, at present inhabited by the Mongolian Ground Jay (P. hendersoni) instead, might make the ecology of these two mutually exclusive species better understood.
文摘In evolutionary theory,we generally believe that the evolution of life is from simple to complex,from single to diverse,and from lower to higher.Thus,the idea of evolutionary progress appears obvious.However,in contemporary academic circles,some biologists and philosophers challenge this idea.Among them,Gould is the most influential.This paper first describes Gould’s seven arguments against evolutionary progress,i.e.,the human arrogance argument,anthropocentric argument,no inner thrust argument,no biological base argument,extreme contingency argument,statistical error argument,and bacteria(other than human beings)ruling the earth argument.Gould’s arguments against evolutionary progress have great influence in contemporary evolutionary theory.Thus,it is necessary to conduct a careful philosophical analysis of each of Gould’s arguments to reveal his philosophical mistakes.This research contends that Gould’s arguments against evolutionary progress are invalid.
文摘After a series of comparison between Jay Gatsby——the protagonist of "The Great Gatsby"and Duddy kravitz——the protagonist of "The Apprenticeship of Duddy kravitz",the authorof this essay gets such a conclusion,that Jay Gatsby was a pure idealist,while Duddykravitz a vulgar materialist.
文摘犹太籍长住美国纽约摄影家 Jay Maisel 的摄影展使人印象深刻。他利用光线和姿势创造了无数用于广告、杂志和团体报道的难忘形象。他为全体工业界所敬重,他的作品进入了无数教科书,以及成为私人和团体的收藏品。在他因其出色的创作所获得的奖项中,包括美国媒体摄影家协会与专业摄影家协会颁发的"美国时代成就奖",以及美国媒体摄影家协会的"年度摄影家奖"、国际摄影中心的"无极奖",并且进入了纽约市艺术家俱乐部的"名人堂"。作为职业联合会和耶鲁大学的一员,Jay Maisel
