Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Jap...Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Japanese Tits(Parus minor) can alter the calling rate and number and combination of notes in response to predators. We previously found the combinations of note types in Japanese Tit alarm calls to be significantly different in response to the Sparrowhawk(Accipiter nisus) and Common Cuckoo(Cuculus canorus).Methods: Through playback experiments, we tested whether the note strings in Japanese Tit alarm calls to the Common Cuckoo have different functions in conveying information. The note strings of selected alarm calls were divided into the categories of C and D, and different calls were then constructed separately based on the two note string categories. Original alarm calls(C–D), C calls and D calls were played back to male Japanese Tits during the incubation period.Results: Male Japanese Tits had a significantly stronger response to C calls than to C–D calls, and they showed a significantly stronger response to both C and C–D calls than to D calls, suggesting that Japanese Tits discriminated between the C and D calls.Conclusions: Our study demonstrated that the C-and D-category note strings of Japanese Tit alarm calls to the Common Cuckoo have different functions, which supports the previous finding that different note strings in an alarm call can provide different information to receivers. However, the exact meanings of these note strings are not yet known, and further investigation is therefore required.展开更多
Begging brings benefits and costs for nestling birds:it can indicate their needs to their parents,but it can also be a cue used by predators to find the nest.The costs,like many variables related to nest predation,can...Begging brings benefits and costs for nestling birds:it can indicate their needs to their parents,but it can also be a cue used by predators to find the nest.The costs,like many variables related to nest predation,can be specific to what kinds of predators are present and their auditory capabilities.These costs and benefits could also be affected by human noise,as noise could disrupt communication to parents and eavesdropping by predators,although human-produced noise might be easily ignored if predators can hear high-frequency components of the begging.We studied nest predation on a generalist bird,the Red-whiskered Bulbul(Pycnonotus jocosus),in a tropical forest in which there are many kinds of nest predators,including birds,mammals and reptiles.In 20 natural nests in which artificial eggs were placed,and subsequently in 140 artificial nests,we broadcast recordings of begging nestlings,with and without traffic noise,at two volume levels.We hypothesized that playback would increase predation relative to a silent control,and that mixing in traffic noise with the begging would decrease predation,as the begging signal was masked.However,we hypothesized that some predators,particularly small mammals with sensitive high-frequency hearing,might ignore the traffic noise.We found that predation was lowest for the control treatment,and lower for treatments mixed with traffic noise than for those without it.Small mammals,however,showed an unexpected pattern,displaying less nest predation in the treatments with traffic noise.Our results demonstrate the human-associated noise can disturb nest predators and influence which kinds of predators use begging to locate nests.展开更多
Background:Generally speaking,playbacks were often ineffective to determine the group sizes of birds since mainly males from leks responded.This limitation has not been tested properly for flocking birds such as Crest...Background:Generally speaking,playbacks were often ineffective to determine the group sizes of birds since mainly males from leks responded.This limitation has not been tested properly for flocking birds such as Crested Guineafowl(Guttera edouardi) with the view to use it as a counting method.The aims of the study reported in this paper were(1) to describe the cal s of Crested Guineafowl in a social context;(2) to interpret cal s in an evolutionary context;and(3) to demonstrate that playbacks can be used to locate and count Crested Guineafowl in smal isolated forests.Methods:The vocal behavior of Crested Guineafowl was observed during a survey conducted in the Umhlanga Lagoon Nature Reserve(Kwa Zulu-Natal,South Africa) from November 2010 to June 2012.Transect line observations and sound playback methods were used.Results:The behavioral context and structure of cal s were described.The eight cal s described for Crested Guineafowl were produced mainly to unite flock members in the dense understory,where visibility was poor,and to repel intruders.When not disturbed,Crested Guineafowl were quiet and only made soft contact calls.Conclusions:The high rate of call back and the fact that flocks invariably approach the source of the call en masse,shows that field researchers are able to assess the population size of Crested Guineafowl with sound playbacks along a transect.The value of playbacks as a conservation tool is assessed.展开更多
Conventionally, P2P video is regarded as CBR traffic. However, our measurements have shown that the rate reset cannot be neglected in a practical IPTV system because each rate reset often leads to performance degradat...Conventionally, P2P video is regarded as CBR traffic. However, our measurements have shown that the rate reset cannot be neglected in a practical IPTV system because each rate reset often leads to performance degradation. Thus, addressing the problem of inferring playback rate and rate reset in a P2P video system is significant. In this article, an algorithm termed piecewise linear envelope approximation （PLEA） is proposed, in which a follow-up time is introduced to smooth rate fluctuations in a small time scale and to adapt rate jumps in a large time scale automatically. With the PLEA algorithm, discontinuity introduced by blind segmentations adopted by current methods is avoided. Furthermore, unlike existing algorithms in which both segmentation and combinations are performed in multiple runs, only a single computation path is involved in the PLEA algorithm. This makes PLEA algorithm amenable to implementation of low complexity by either software or hardware. Both theoretical analysis and experiment based on measured data show that the PLEA outperforms existing algorithms based on segmentation.展开更多
We propose a high-speed playback method for the spatiotemporal division multiplexing electroholographic three-dimensional(3D)video stored in a solid-state drive(SSD)using a digital micromirror device.The spatiotempora...We propose a high-speed playback method for the spatiotemporal division multiplexing electroholographic three-dimensional(3D)video stored in a solid-state drive(SSD)using a digital micromirror device.The spatiotemporal division multiplexing electroholography prevents deterioration in the reconstructed 3D video from a 3D object comprising many object points.In the proposed method,the stored data is remarkably reduced using the packing technique,and the computer-generated holograms are played back at high speed.Consequently,we successfully reconstructed a clear 3D video of a 3D object comprising approximately 1,100,000 points at 60 frames per second by reducing the reading time of the stored data from an SSD.展开更多
基金supported by the National Natural Science Foundation of China(31272331 and 31470458 to HW,31472013 and 31772453 to WL)the Fundamental Research Funds for the Central Universities(2412016KJ043)the Open Project Program of Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization(130028685)
文摘Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Japanese Tits(Parus minor) can alter the calling rate and number and combination of notes in response to predators. We previously found the combinations of note types in Japanese Tit alarm calls to be significantly different in response to the Sparrowhawk(Accipiter nisus) and Common Cuckoo(Cuculus canorus).Methods: Through playback experiments, we tested whether the note strings in Japanese Tit alarm calls to the Common Cuckoo have different functions in conveying information. The note strings of selected alarm calls were divided into the categories of C and D, and different calls were then constructed separately based on the two note string categories. Original alarm calls(C–D), C calls and D calls were played back to male Japanese Tits during the incubation period.Results: Male Japanese Tits had a significantly stronger response to C calls than to C–D calls, and they showed a significantly stronger response to both C and C–D calls than to D calls, suggesting that Japanese Tits discriminated between the C and D calls.Conclusions: Our study demonstrated that the C-and D-category note strings of Japanese Tit alarm calls to the Common Cuckoo have different functions, which supports the previous finding that different note strings in an alarm call can provide different information to receivers. However, the exact meanings of these note strings are not yet known, and further investigation is therefore required.
基金supported by the National Natural Science Foundation of China(grant 31870370)Guangxi 1000 Young and Middle-Aged College and University Backbone Teachers Cultivation Program(2019.5)。
文摘Begging brings benefits and costs for nestling birds:it can indicate their needs to their parents,but it can also be a cue used by predators to find the nest.The costs,like many variables related to nest predation,can be specific to what kinds of predators are present and their auditory capabilities.These costs and benefits could also be affected by human noise,as noise could disrupt communication to parents and eavesdropping by predators,although human-produced noise might be easily ignored if predators can hear high-frequency components of the begging.We studied nest predation on a generalist bird,the Red-whiskered Bulbul(Pycnonotus jocosus),in a tropical forest in which there are many kinds of nest predators,including birds,mammals and reptiles.In 20 natural nests in which artificial eggs were placed,and subsequently in 140 artificial nests,we broadcast recordings of begging nestlings,with and without traffic noise,at two volume levels.We hypothesized that playback would increase predation relative to a silent control,and that mixing in traffic noise with the begging would decrease predation,as the begging signal was masked.However,we hypothesized that some predators,particularly small mammals with sensitive high-frequency hearing,might ignore the traffic noise.We found that predation was lowest for the control treatment,and lower for treatments mixed with traffic noise than for those without it.Small mammals,however,showed an unexpected pattern,displaying less nest predation in the treatments with traffic noise.Our results demonstrate the human-associated noise can disturb nest predators and influence which kinds of predators use begging to locate nests.
文摘Background:Generally speaking,playbacks were often ineffective to determine the group sizes of birds since mainly males from leks responded.This limitation has not been tested properly for flocking birds such as Crested Guineafowl(Guttera edouardi) with the view to use it as a counting method.The aims of the study reported in this paper were(1) to describe the cal s of Crested Guineafowl in a social context;(2) to interpret cal s in an evolutionary context;and(3) to demonstrate that playbacks can be used to locate and count Crested Guineafowl in smal isolated forests.Methods:The vocal behavior of Crested Guineafowl was observed during a survey conducted in the Umhlanga Lagoon Nature Reserve(Kwa Zulu-Natal,South Africa) from November 2010 to June 2012.Transect line observations and sound playback methods were used.Results:The behavioral context and structure of cal s were described.The eight cal s described for Crested Guineafowl were produced mainly to unite flock members in the dense understory,where visibility was poor,and to repel intruders.When not disturbed,Crested Guineafowl were quiet and only made soft contact calls.Conclusions:The high rate of call back and the fact that flocks invariably approach the source of the call en masse,shows that field researchers are able to assess the population size of Crested Guineafowl with sound playbacks along a transect.The value of playbacks as a conservation tool is assessed.
基金supported by the National Natural Science Foundation of China(60672069,60772043)the National Basic Research Program of China(2007CB307101)
文摘Conventionally, P2P video is regarded as CBR traffic. However, our measurements have shown that the rate reset cannot be neglected in a practical IPTV system because each rate reset often leads to performance degradation. Thus, addressing the problem of inferring playback rate and rate reset in a P2P video system is significant. In this article, an algorithm termed piecewise linear envelope approximation （PLEA） is proposed, in which a follow-up time is introduced to smooth rate fluctuations in a small time scale and to adapt rate jumps in a large time scale automatically. With the PLEA algorithm, discontinuity introduced by blind segmentations adopted by current methods is avoided. Furthermore, unlike existing algorithms in which both segmentation and combinations are performed in multiple runs, only a single computation path is involved in the PLEA algorithm. This makes PLEA algorithm amenable to implementation of low complexity by either software or hardware. Both theoretical analysis and experiment based on measured data show that the PLEA outperforms existing algorithms based on segmentation.
基金This work was partially supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI(No.18K11399)and I-O DATA Foundation.
文摘We propose a high-speed playback method for the spatiotemporal division multiplexing electroholographic three-dimensional(3D)video stored in a solid-state drive(SSD)using a digital micromirror device.The spatiotemporal division multiplexing electroholography prevents deterioration in the reconstructed 3D video from a 3D object comprising many object points.In the proposed method,the stored data is remarkably reduced using the packing technique,and the computer-generated holograms are played back at high speed.Consequently,we successfully reconstructed a clear 3D video of a 3D object comprising approximately 1,100,000 points at 60 frames per second by reducing the reading time of the stored data from an SSD.
