In this paper, we study the precise large deviations for the prospectiveloss process with consistently varying tails. The obtained results improve some related known ones.
随者互联网时代的到来,如何提升互联网应用的交互性能逐渐成为时下的研究热点;而在当今的互联网环境中,网络带宽已经不是瓶颈,网络时延成为影响应用交互性能的关键因素.作为互联网时代的主要应用,Web应用的网络时延受到TCP尾部丢包现象...随者互联网时代的到来,如何提升互联网应用的交互性能逐渐成为时下的研究热点;而在当今的互联网环境中,网络带宽已经不是瓶颈,网络时延成为影响应用交互性能的关键因素.作为互联网时代的主要应用,Web应用的网络时延受到TCP尾部丢包现象的严重影响.Tail Loss Probe算法是一种通过发送探针包来触发恢复的高效易部署的TCP尾部丢包恢复算法,但其需要修改现有的TCP加速机制,存在影响互联网稳定性的风险.针对Tail Loss Probe算法存在的不足,提出一种Double Tail Loss Probe算法,该算法对不同的尾部丢包模式进行细化处理且在适当时机下发送两个探针包以加速恢复并实现与现有TCP机制的友好兼容,从而保证互联网数据流通的稳定性.实验表明,在不同的丢包粒度和传播时延下,Double Tail Loss Probe算法都展现出更快的恢复速度;尤其在丢包粒度较大时,相比Tail Loss Probe,该算法取得了约20%的性能提升.展开更多
In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performa...In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performance that may affectfitness.Scorpions of the genus Ananteris autotomize the“tail”,which in fact corresponds to the last abdominal segments.After autotomy,individuals lose nearly 25%of their body mass and the last portion of the digestive tract,including the anus,which prevents defecation and leads to constipation,because regeneration does not occur.Here,we experimentally investigated the short-and long-term effects of tail loss on the locomotor performance of Ananteris balzani.In a short-term experiment,the maximum running speed(MRS)of males and females did not change after autotomy.Moreover,the relative mass of the lost tail did not affect the change in MRS after autotomy.In a long-term experiment,autotomy had a negative effect on the MRS of males,but not of females.Autotomized over-fed individuals suffered from severe constipation but were not slower than autotomized normally fed individuals.In conclusion,tail loss has no immediate effect on the locomotor performance of scorpions.The long-term decrease in the locomotor performance of autotomized males may impair mate searching.However,because death by constipation takes several months,males have a long time tofind mates and reproduce.Thus,the prolonged period between autotomy and death by constipation is crucial for understanding the evolution of one of the most extreme cases of autotomy in nature.展开更多
文摘In this paper, we study the precise large deviations for the prospectiveloss process with consistently varying tails. The obtained results improve some related known ones.
文摘随者互联网时代的到来,如何提升互联网应用的交互性能逐渐成为时下的研究热点;而在当今的互联网环境中,网络带宽已经不是瓶颈,网络时延成为影响应用交互性能的关键因素.作为互联网时代的主要应用,Web应用的网络时延受到TCP尾部丢包现象的严重影响.Tail Loss Probe算法是一种通过发送探针包来触发恢复的高效易部署的TCP尾部丢包恢复算法,但其需要修改现有的TCP加速机制,存在影响互联网稳定性的风险.针对Tail Loss Probe算法存在的不足,提出一种Double Tail Loss Probe算法,该算法对不同的尾部丢包模式进行细化处理且在适当时机下发送两个探针包以加速恢复并实现与现有TCP机制的友好兼容,从而保证互联网数据流通的稳定性.实验表明,在不同的丢包粒度和传播时延下,Double Tail Loss Probe算法都展现出更快的恢复速度;尤其在丢包粒度较大时,相比Tail Loss Probe,该算法取得了约20%的性能提升.
基金Supported by Natural Science Foundation of China(31370845)National Basic Research Program of China(2011CB710903)+1 种基金New Century Excellent Talents in University(NCET-12-0469)National Natural Science Foundation of China(31400725)
基金supported by grants of the Fundação de AmparoàPesquisa do Estado de São Paulo(2015/10448-4 to GM,2017/05283-1 to SGH)Conselho Nacional de Desenvolvimento Científico e Tecnológico(306550/2014-8 to GM).
文摘In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performance that may affectfitness.Scorpions of the genus Ananteris autotomize the“tail”,which in fact corresponds to the last abdominal segments.After autotomy,individuals lose nearly 25%of their body mass and the last portion of the digestive tract,including the anus,which prevents defecation and leads to constipation,because regeneration does not occur.Here,we experimentally investigated the short-and long-term effects of tail loss on the locomotor performance of Ananteris balzani.In a short-term experiment,the maximum running speed(MRS)of males and females did not change after autotomy.Moreover,the relative mass of the lost tail did not affect the change in MRS after autotomy.In a long-term experiment,autotomy had a negative effect on the MRS of males,but not of females.Autotomized over-fed individuals suffered from severe constipation but were not slower than autotomized normally fed individuals.In conclusion,tail loss has no immediate effect on the locomotor performance of scorpions.The long-term decrease in the locomotor performance of autotomized males may impair mate searching.However,because death by constipation takes several months,males have a long time tofind mates and reproduce.Thus,the prolonged period between autotomy and death by constipation is crucial for understanding the evolution of one of the most extreme cases of autotomy in nature.
