The Yellow-legged hornet, Vespa velutina , was accidentally introduced in France in 2004, and then spread rapidly through the French territory but also to adjacent European countries (Spain, Portugal, and Belgium). Du...The Yellow-legged hornet, Vespa velutina , was accidentally introduced in France in 2004, and then spread rapidly through the French territory but also to adjacent European countries (Spain, Portugal, and Belgium). During summer and autumn, V. velutina workers hunt domestic honeybees, Apis mellifera, for feeding their larvae. The impact of this alien species is mainly economic, beekeepers experiencing heavy colony losses, but also ecological, V. velutina hunting other pollinators. In their year-round life cycle, nest initiation by single queen during spring is the critical stage. In invaded areas, spring queen trapping using food baits has been promoted by apicultural unions in order to limit V. velutina population expansion. The goals of this work were 1) to evaluate the yield of this method, 2) to identify appropriate sites for trapping, 3) to identify potential optimal climatic windows of capture, and 4) to quantify the impact on local entomofauna. Our results showed that water proximity enhances trapping but not beehives proximity, and that trapping is inefficient if average week temperatures are below 10°C. Although the trapping effect on biodiversity should be studied more carefully, spring queen trapping is highly questionable unless specific attractants could be proposed.展开更多
The perinatal period is critical to survival and performance of many organisms.In birds,rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status,with potential...The perinatal period is critical to survival and performance of many organisms.In birds,rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status,with potentially negative consequences on physiology mediated by oxidative stress.In addition,telomere length(TL)undergoes reduction during birds’early life,partly depending on oxidative status.However,relatively few studies have focused specifically on the changes in oxidative status and TL that occur immediately after hatching.In this study of the yellow-legged gull Larus michahellis,we found that chicks undergo a marked increase in plasma total antioxidant capacity and a marked decrease in the concentration of pro-oxidant molecules during the first days after hatching.In addition,TL in erythrocytes decreased by 1 standard deviation over the 4days post-hatching.Body mass and tarsus length covaried with total antioxidant capacity and concentration of pro-oxidants in a complex way,that partly depended on sex and laying order,suggesting that oxidative status can affect growth.Moreover,TL positively covaried with the concentration of pro-oxidant molecules,possibly because retention of high concentrations of pro-oxidant molecules results from mechanisms of prevention of their negative effects,including reduction in TL.Thus,this study shows that chicks undergo marked variation in oxidative status,which predicts growth and subsequent TL,prompting for more studies of the perinatal changes in the critical posthatching stages.展开更多
针对夜间行人检测任务中存在的检测速度慢、漏检率高、黑夜场景下识别效果差等问题,提出一种改进YOLOv7的夜间行人检测算法。改进算法中,使用YOLOv7-tiny网络作为baseline,以满足准确率的同时兼具较高的检测速度,在网络head部分,使用CSP...针对夜间行人检测任务中存在的检测速度慢、漏检率高、黑夜场景下识别效果差等问题,提出一种改进YOLOv7的夜间行人检测算法。改进算法中,使用YOLOv7-tiny网络作为baseline,以满足准确率的同时兼具较高的检测速度,在网络head部分,使用CSP HorNet模块实现关键特征之间的高阶交互,并引入SimAM注意力机制,在不增加模型复杂度的情况下,使网络聚焦更多重要的特征信息。实验结果表明,改进算法在测试集上准确率(Precision,P)达到91.7%,召回率(Recall,R)达到81.4%,均值平均精度(mean Average Precision,mAP)提升2.9个百分点。改进算法在真实场景检测任务中,有效降低了漏检率及错检率,表现出良好的性能。展开更多
All optical network （AON） is a hot topic in recent studies of optical fiber communications. Key techniques in AON include optical switching/routing, optical cross connection （OXC）, all optical wavelength conversi...All optical network （AON） is a hot topic in recent studies of optical fiber communications. Key techniques in AON include optical switching/routing, optical cross connection （OXC）, all optical wavelength conversion （AOWC）, all optical buffering, etc. Opti- cal switching/routing is in fact wavelength switching/ routing. OXC and wavelength conversion （WC） are introduced into cross nodes so that a virtual wavelength path is established. With WC, communication route is formed only if there is unused wavelength in an individual segment link. The rate wavelength usage is thus greatly increased. The blocking rate of network can be reduced by adding WCs, especially for huge capacity multiple nodes ones. Therefore, WC has attracted much attention in basic research of optical communication and is used in some experimental networks.This dissertation studies all optic wavelength conversion and its application, with the contributions in the following five aspects.展开更多
Background: The banning of fisheries discards by imposing an obligation to land unwanted catch constitutes a key point of the Common Fishery Policy reform proposed by the European Commission. The effect of such a ban ...Background: The banning of fisheries discards by imposing an obligation to land unwanted catch constitutes a key point of the Common Fishery Policy reform proposed by the European Commission. The effect of such a ban on discards on top marine predators such as seabirds is largely unknown, especially in oligotrophic systems of the Medi?terranean. The current study investigates the presence of scavenging seabirds around fishing trawlers as well as the exploitation of discards produced by bottom trawlers in the eastern Ionian Sea.Methods: On?board observations were randomly conducted in May and December 2014, in order to record the presence and use of fishery discards by two common seabird species, namely, Scopoli's Shearwater(Calonectris diomedea) and the Yellow?legged Gull(Larus michahellis).Results: A total of 3400 seabirds were counted during May of which 2190 individuals were Scopoli's Shearwaters and 1210 were Yellow?legged Gulls. The latter species was the only scavenger observed during winter and in total, 768 individuals were counted. Differences in species abundance in the study area are related to breeding phenology and migratory movements. The number of seabirds attending bottom trawler operations during morning and afternoon hours showed no significant differences for both seabird species. Both scavenging seabirds extensively exploited fishery discards, which were mainly demersal fish, and consumed 70–80% of the total fishery discards biomass; how?ever, they appeared to avoid poisonous species and/or large?sized fish. Yellow?legged Gulls displayed kleptoparasitic behaviour on Scopoli's Shearwater during feeding experiments. The number of such incidents depended on the number of gulls around the fishing vessel, with more than 90% success rates.Conclusions: Considering the average annual biomass of discards estimations and the consumption rate found in this work, 106.1–117.9 t may be offered as a food subsidy to scavenging seabirds in the study area and should support a substantial part of local populations. Our results constitute baseline information on the annual amount of fishery discards and their exploitation rate by seabirds in the Ionian Sea, and suggest further work for a complete understand?ing of the potential impacts of the discards reform bill on seabirds.展开更多
文摘The Yellow-legged hornet, Vespa velutina , was accidentally introduced in France in 2004, and then spread rapidly through the French territory but also to adjacent European countries (Spain, Portugal, and Belgium). During summer and autumn, V. velutina workers hunt domestic honeybees, Apis mellifera, for feeding their larvae. The impact of this alien species is mainly economic, beekeepers experiencing heavy colony losses, but also ecological, V. velutina hunting other pollinators. In their year-round life cycle, nest initiation by single queen during spring is the critical stage. In invaded areas, spring queen trapping using food baits has been promoted by apicultural unions in order to limit V. velutina population expansion. The goals of this work were 1) to evaluate the yield of this method, 2) to identify appropriate sites for trapping, 3) to identify potential optimal climatic windows of capture, and 4) to quantify the impact on local entomofauna. Our results showed that water proximity enhances trapping but not beehives proximity, and that trapping is inefficient if average week temperatures are below 10°C. Although the trapping effect on biodiversity should be studied more carefully, spring queen trapping is highly questionable unless specific attractants could be proposed.
文摘The perinatal period is critical to survival and performance of many organisms.In birds,rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status,with potentially negative consequences on physiology mediated by oxidative stress.In addition,telomere length(TL)undergoes reduction during birds’early life,partly depending on oxidative status.However,relatively few studies have focused specifically on the changes in oxidative status and TL that occur immediately after hatching.In this study of the yellow-legged gull Larus michahellis,we found that chicks undergo a marked increase in plasma total antioxidant capacity and a marked decrease in the concentration of pro-oxidant molecules during the first days after hatching.In addition,TL in erythrocytes decreased by 1 standard deviation over the 4days post-hatching.Body mass and tarsus length covaried with total antioxidant capacity and concentration of pro-oxidants in a complex way,that partly depended on sex and laying order,suggesting that oxidative status can affect growth.Moreover,TL positively covaried with the concentration of pro-oxidant molecules,possibly because retention of high concentrations of pro-oxidant molecules results from mechanisms of prevention of their negative effects,including reduction in TL.Thus,this study shows that chicks undergo marked variation in oxidative status,which predicts growth and subsequent TL,prompting for more studies of the perinatal changes in the critical posthatching stages.
文摘针对夜间行人检测任务中存在的检测速度慢、漏检率高、黑夜场景下识别效果差等问题,提出一种改进YOLOv7的夜间行人检测算法。改进算法中,使用YOLOv7-tiny网络作为baseline,以满足准确率的同时兼具较高的检测速度,在网络head部分,使用CSP HorNet模块实现关键特征之间的高阶交互,并引入SimAM注意力机制,在不增加模型复杂度的情况下,使网络聚焦更多重要的特征信息。实验结果表明,改进算法在测试集上准确率(Precision,P)达到91.7%,召回率(Recall,R)达到81.4%,均值平均精度(mean Average Precision,mAP)提升2.9个百分点。改进算法在真实场景检测任务中,有效降低了漏检率及错检率,表现出良好的性能。
文摘All optical network （AON） is a hot topic in recent studies of optical fiber communications. Key techniques in AON include optical switching/routing, optical cross connection （OXC）, all optical wavelength conversion （AOWC）, all optical buffering, etc. Opti- cal switching/routing is in fact wavelength switching/ routing. OXC and wavelength conversion （WC） are introduced into cross nodes so that a virtual wavelength path is established. With WC, communication route is formed only if there is unused wavelength in an individual segment link. The rate wavelength usage is thus greatly increased. The blocking rate of network can be reduced by adding WCs, especially for huge capacity multiple nodes ones. Therefore, WC has attracted much attention in basic research of optical communication and is used in some experimental networks.This dissertation studies all optic wavelength conversion and its application, with the contributions in the following five aspects.
基金performed within the framework of the ECODISC project,entitled“ECOsystem effect of fisheries DISCards”,partially funded by the NSRF 2007-2013 Operational Programme“Education and Lifelong Learning”,which is cofinanced by Greece and the European UnionFisheries data were collected within the framework of the 2014 Greek National Fisheries Data Collection Programme(EPSAD)funded by the Greek Government and the European Union under Regulation 199/2008/EU
文摘Background: The banning of fisheries discards by imposing an obligation to land unwanted catch constitutes a key point of the Common Fishery Policy reform proposed by the European Commission. The effect of such a ban on discards on top marine predators such as seabirds is largely unknown, especially in oligotrophic systems of the Medi?terranean. The current study investigates the presence of scavenging seabirds around fishing trawlers as well as the exploitation of discards produced by bottom trawlers in the eastern Ionian Sea.Methods: On?board observations were randomly conducted in May and December 2014, in order to record the presence and use of fishery discards by two common seabird species, namely, Scopoli's Shearwater(Calonectris diomedea) and the Yellow?legged Gull(Larus michahellis).Results: A total of 3400 seabirds were counted during May of which 2190 individuals were Scopoli's Shearwaters and 1210 were Yellow?legged Gulls. The latter species was the only scavenger observed during winter and in total, 768 individuals were counted. Differences in species abundance in the study area are related to breeding phenology and migratory movements. The number of seabirds attending bottom trawler operations during morning and afternoon hours showed no significant differences for both seabird species. Both scavenging seabirds extensively exploited fishery discards, which were mainly demersal fish, and consumed 70–80% of the total fishery discards biomass; how?ever, they appeared to avoid poisonous species and/or large?sized fish. Yellow?legged Gulls displayed kleptoparasitic behaviour on Scopoli's Shearwater during feeding experiments. The number of such incidents depended on the number of gulls around the fishing vessel, with more than 90% success rates.Conclusions: Considering the average annual biomass of discards estimations and the consumption rate found in this work, 106.1–117.9 t may be offered as a food subsidy to scavenging seabirds in the study area and should support a substantial part of local populations. Our results constitute baseline information on the annual amount of fishery discards and their exploitation rate by seabirds in the Ionian Sea, and suggest further work for a complete understand?ing of the potential impacts of the discards reform bill on seabirds.
