We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space f...We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space focus point and decelerated right after the mass gate, were then crossed by a laser beam for dissociation. The daughter ions and surviving parent ions were re-accelerated and analyzed by the reflectron time-of-flight mass spectrometer. Compared to the designs reported by other research groups, our selection-deceleration-dissociation-reacceleration approach has better daughter-parent-ions-separation, easier laser timing, and better overlapping between the ion beam and laser beam. We also conducted detailed cal- culations on the parent ion and daughter ion flight times, and provided a simplified formula for the calibration of daughter ion mass.展开更多
Birds and other animals are frequently killed by cars,causing the death of many million individuals per year.Why some species are killed more often than others has never been investigated.In this work hypothesized tha...Birds and other animals are frequently killed by cars,causing the death of many million individuals per year.Why some species are killed more often than others has never been investigated.In this work hypothesized that risk taking behavior may affect the probability of certain kinds of individuals being killed disproportionately often.Furthermore,behavior of individuals on roads,abundance,habitat preferences,breeding sociality,and health status may all potentially affect the risk of being killed on roads.We used information on the abundance of road kills and the abundance in the surrounding environment of 50 species of birds obtained during regular censuses in 2001 2006 in a rural site in Denmark to test these predictions.The frequency of road kills increased linearly with abundance,while the proportion of individuals sitting on the road or flying low across the road only explained little additional variation in frequency of road casualties.After having accounted for abundance,we found that species with a short flight distance and hence taking greater risks when approached by a potential cause of danger were killed disproportionately often.In addition,solitary species,species with a high prevalence of Plasmodium infection,and species with a large bursa of Fabricius for their body size had a high susceptibility to being killed by cars.These findings suggest that a range of different factors indicative of risk-taking behavior,visual acuity and health status cause certain bird species to be susceptible to casualties due to cars.展开更多
Predators efficiently learn to avoid one type of warning signal rather than several, making colour polymorphisms un- expected. Aposematic wood tiger moth males Parasemia plantaginis have either white or yellow hindwin...Predators efficiently learn to avoid one type of warning signal rather than several, making colour polymorphisms un- expected. Aposematic wood tiger moth males Parasemia plantaginis have either white or yellow hindwing coloration across Eu- rope. Previous studies indicate that yellow males are better defended from predators, while white males have a positively frequency-dependent mating advantage. However, the potential frequency-dependent behavioural differences in flight between the morphs, as well as the role of male-male interactions in inducing flying activity, have not been previously considered. We ran an outdoor cage experiment where proportions of both male morphs were manipulated to test whether flying activity was frequency- dependent and differed between morphs. The white morph was significantly more active than the yellow one across all treatments, and sustained activity for longer. Overall activity for both morphs was considerably lower in the yellow-biased environment, suggesting that higher proportions of yellow males in a population may lead to overall reduced flying activity. The activity of the yellow morph also followed a steeper, narrower curve than that of the white morph during peak female calling activity. We sug- gest that white males, with their presumably less costly defences, have more resources to invest in flight for predator escape and finding mates. Yellow males, which are better protected but less sexually selected, may instead compensate their lower flight ac- tivity by ＇flying smart＇ during the peak female-calling periods. Thus, both morphs may be able to behaviourally balance the trade-off between warning signal selection and sexual selection. Our results emphasize the greater need to investigate animal behaviour and colour polymorphisms in natural or semi-natural environments [Current Zoology 61 （4）： 765-772, 2015].展开更多
基金V. ACKNOWLEDGMENTS This work supported by the National Natural Science Foundation of China （No.20853001）. We thank Professor Qi-he Zhu and Professor Zhen Gao for valuable discussions.
文摘We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space focus point and decelerated right after the mass gate, were then crossed by a laser beam for dissociation. The daughter ions and surviving parent ions were re-accelerated and analyzed by the reflectron time-of-flight mass spectrometer. Compared to the designs reported by other research groups, our selection-deceleration-dissociation-reacceleration approach has better daughter-parent-ions-separation, easier laser timing, and better overlapping between the ion beam and laser beam. We also conducted detailed cal- culations on the parent ion and daughter ion flight times, and provided a simplified formula for the calibration of daughter ion mass.
文摘Birds and other animals are frequently killed by cars,causing the death of many million individuals per year.Why some species are killed more often than others has never been investigated.In this work hypothesized that risk taking behavior may affect the probability of certain kinds of individuals being killed disproportionately often.Furthermore,behavior of individuals on roads,abundance,habitat preferences,breeding sociality,and health status may all potentially affect the risk of being killed on roads.We used information on the abundance of road kills and the abundance in the surrounding environment of 50 species of birds obtained during regular censuses in 2001 2006 in a rural site in Denmark to test these predictions.The frequency of road kills increased linearly with abundance,while the proportion of individuals sitting on the road or flying low across the road only explained little additional variation in frequency of road casualties.After having accounted for abundance,we found that species with a short flight distance and hence taking greater risks when approached by a potential cause of danger were killed disproportionately often.In addition,solitary species,species with a high prevalence of Plasmodium infection,and species with a large bursa of Fabricius for their body size had a high susceptibility to being killed by cars.These findings suggest that a range of different factors indicative of risk-taking behavior,visual acuity and health status cause certain bird species to be susceptible to casualties due to cars.
文摘Predators efficiently learn to avoid one type of warning signal rather than several, making colour polymorphisms un- expected. Aposematic wood tiger moth males Parasemia plantaginis have either white or yellow hindwing coloration across Eu- rope. Previous studies indicate that yellow males are better defended from predators, while white males have a positively frequency-dependent mating advantage. However, the potential frequency-dependent behavioural differences in flight between the morphs, as well as the role of male-male interactions in inducing flying activity, have not been previously considered. We ran an outdoor cage experiment where proportions of both male morphs were manipulated to test whether flying activity was frequency- dependent and differed between morphs. The white morph was significantly more active than the yellow one across all treatments, and sustained activity for longer. Overall activity for both morphs was considerably lower in the yellow-biased environment, suggesting that higher proportions of yellow males in a population may lead to overall reduced flying activity. The activity of the yellow morph also followed a steeper, narrower curve than that of the white morph during peak female calling activity. We sug- gest that white males, with their presumably less costly defences, have more resources to invest in flight for predator escape and finding mates. Yellow males, which are better protected but less sexually selected, may instead compensate their lower flight ac- tivity by ＇flying smart＇ during the peak female-calling periods. Thus, both morphs may be able to behaviourally balance the trade-off between warning signal selection and sexual selection. Our results emphasize the greater need to investigate animal behaviour and colour polymorphisms in natural or semi-natural environments [Current Zoology 61 （4）： 765-772, 2015].
