Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations.Whistle of free-ranging Indo-Pacific humpback dolphins(Sousa chinensis)among the Pearl River Estua...Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations.Whistle of free-ranging Indo-Pacific humpback dolphins(Sousa chinensis)among the Pearl River Estuary(PRE),Leizhou Bei(LZB)and Sanniang Bay(SNB)populations were investigated.A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured.Contrary to SNB,PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types.The generalized linear model analysis showed significant acoustic difference among populations and tonal types.All frequency parameters in SNB were significantly higher than those in PRE and LZB,where no significant variation was observed in most of the parameters either at the population level or within each tonal type.Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB.Compared with previous recordings,recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations,suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis.Dolphin whistle’s geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise.Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB,more effective and proactive conservation actions should be taken to prevent the extinction of small populations.展开更多
【选注者言:春节的爆竹声,连绵不断,甚至延续到半夜,到凌晨。我失眠了,但心情却并不坏。爆竹一声除旧,桃符万户更新!现在是凌晨两点,英语称之为small hours,我披衣起身,打开电脑,在网上浏览起来。读到一篇短文,令我精神抖擞,睡意全消。...【选注者言:春节的爆竹声,连绵不断,甚至延续到半夜,到凌晨。我失眠了,但心情却并不坏。爆竹一声除旧,桃符万户更新!现在是凌晨两点,英语称之为small hours,我披衣起身,打开电脑,在网上浏览起来。读到一篇短文,令我精神抖擞,睡意全消。泰坦尼克巨轮已经沉没87个寒暑了,人们还在银幕上演绎她的故事,观者垂泪;人们还在聆听她的汽笛声,听众伤感。我是一个英语教师,细品本文,觉得本文造句非常讲究,用的大多是“拖泥带水”的长句,作者很懂修辞,这种“欲休还说”的句式不是很好地衬托渲染了今人怀旧时的那种缠绵悱恻的心绪吗?比如下句就很典型,我读之再三: When they were made the whistles weighed 750 pounds(340 kg)and could be heard more than 10 miles(16 km)away, according to the St. Paul Convention and Visitors Bureau, which hosted Saturday's event. 编辑先生,读者同志,不知你们是否同意我的以上分析。如果你们不同意,那么,是不是我过于善感了?】展开更多
The present investigation is conducted to study the year wise (2011to 2018) changes of water hyacinth (Eichhornia crassipes) cover atSantragachi Lake a Wetland under National Wetland ConservationProgramme of India. Fu...The present investigation is conducted to study the year wise (2011to 2018) changes of water hyacinth (Eichhornia crassipes) cover atSantragachi Lake a Wetland under National Wetland ConservationProgramme of India. Further the relationship between water hyacinthcover and the most abundant migratory waterbirds of Satragachi, LesserWhistling Teal (LWT;Dendrocygna javanica) is assessed because this birdspecies is prefer depending on water hyacinth mat for their roosting. Thestudy comprises of eight satellite images procured from Google earth (2011to 2018) to explore this relationship. A marked decline in the number ofLWT at Santragachi wetland is observed in the year of 2017 and 2018. Itis very interesting fact that from 2017-2018, the water hyacinth mat of thiswetland is almost cleared before winter and the result of cluster analysissupports this fact. Significant positive correlation is also observed withinLWT number and water hyacinth cover area (r = 0.7481 at p< 0.05) alongwith the total perimeter (r = 0.8648 at p< 0.05) of the water hyacinthislands at Santragachi wetland. However, open water area is also neededfor diving, swimming, food searching for the LWT and other waterbirds.Therefore, more study is needed to optimize the clearing operations,focused on optimizing the shape and size of water hyacinth islands forproper management of the waterbirds habitat.展开更多
Some 1,500 years ago, people in the Gongbo area invented whistling arrows to enliven their celebration of bumper harvests and major events.Today, China lists shooting whistling arrows among ethnic minority sports even...Some 1,500 years ago, people in the Gongbo area invented whistling arrows to enliven their celebration of bumper harvests and major events.Today, China lists shooting whistling arrows among ethnic minority sports events.Arrow, Bow and TargetThe whistling arrow is 0.6 meter long and is topped with a wooden head that is hollow. Square at the arrowbead,展开更多
Numerous studies have confirmed that electromagnetic disturbances before earthquakes can be observed by satellites.In this study,we use the C-value method that includes the acoustic whistle signature;pre-seismic ionos...Numerous studies have confirmed that electromagnetic disturbances before earthquakes can be observed by satellites.In this study,we use the C-value method that includes the acoustic whistle signature;pre-seismic ionospheric electromagnetic disturbance signals were acquired based on the CSES-01 satellite electric field data,and the maximum value of C in the earthquake preparation zones increased continuously from 2.0 three days before the earthquake and reached a maximum weight of 3.0 on the day of the earthquake,after the earthquake,it gradually decreased and recovered to about 2.0;its the C values fluctuated between-2 and 3,it is different from the C values range-2–12 of the previous seismic case study using the DEMETER satellite,which may be related to the orbital altitude and revisit period of the satellite.Then,the C values were normalized,and the time series analysis of the obtained θ values were done,and the results showed that:In the pregnant zone,the background variation of the disturbance amplitude θ is within 2σ,and the maximum disturbance amplitude of θ starts to increase gradually from the seventh period(one period of 5 days,i.e.,35–39 days before the earthquake),it reached 2σ by the fourth preseismic cycle(20–24 days before the earthquake),and then dropped sharply to about 1.5σ in the third pre-seismic cycle(15–19days before the earthquake),after two cycles of increase,the θ over the epicenter reached a maximum of 2.1σ at the time of the earthquake(combining the time of the earthquake and the satellite flight characteristics,the epicenter period is defined as January25-January 29,2020,and this defines the study time period line),and the θ decreases to within 2 times the standard range after the earthquake;The negative value of the disturbance amplitude θ in the central region of the pregnant seismic zone during the earthquake shows the transient energy release process.Through comparison,the θ values obtained by normalization based on the C-value method takes into account the variation of the background field,and the result can better reflect the energy change of the ionospheric field before the earthquakes.展开更多
Recently,bionic signals have been used to achieve covert underwater acoustic communication(UWAC)with high signal-to-noise ratios(SNRs)over transmission systems.A high SNR allows the attackers to proceed with their mis...Recently,bionic signals have been used to achieve covert underwater acoustic communication(UWAC)with high signal-to-noise ratios(SNRs)over transmission systems.A high SNR allows the attackers to proceed with their mischievous goals and makes transmission systems vulnerable against malicious attacks.In this paper we propose an improved Merkle hash tree based secure scheme that can resist current underwater attacks,i.e.,replay attack,fabricated message attack,message-altering attack,and analyst attack.Security analysis is performed to prove that the proposed scheme can resist these types of attacks.Performance evaluations show that the proposed scheme can meet UWAC limitations due to its efficiency regarding energy consumption,communication overhead,and computation cost.展开更多
基金This research was supported by grants from the National Natural Science Foundation of China(Grant No.41806197)Ocean Park Conservation Foundation of Hong Kong(AW011920)Chinese white dolphin monitoring program of Guangzhou harbor deepwater navigation channel widening project(Grant No.HTYXJC)to Zhitao Wang.
文摘Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations.Whistle of free-ranging Indo-Pacific humpback dolphins(Sousa chinensis)among the Pearl River Estuary(PRE),Leizhou Bei(LZB)and Sanniang Bay(SNB)populations were investigated.A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured.Contrary to SNB,PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types.The generalized linear model analysis showed significant acoustic difference among populations and tonal types.All frequency parameters in SNB were significantly higher than those in PRE and LZB,where no significant variation was observed in most of the parameters either at the population level or within each tonal type.Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB.Compared with previous recordings,recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations,suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis.Dolphin whistle’s geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise.Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB,more effective and proactive conservation actions should be taken to prevent the extinction of small populations.
文摘【选注者言:春节的爆竹声,连绵不断,甚至延续到半夜,到凌晨。我失眠了,但心情却并不坏。爆竹一声除旧,桃符万户更新!现在是凌晨两点,英语称之为small hours,我披衣起身,打开电脑,在网上浏览起来。读到一篇短文,令我精神抖擞,睡意全消。泰坦尼克巨轮已经沉没87个寒暑了,人们还在银幕上演绎她的故事,观者垂泪;人们还在聆听她的汽笛声,听众伤感。我是一个英语教师,细品本文,觉得本文造句非常讲究,用的大多是“拖泥带水”的长句,作者很懂修辞,这种“欲休还说”的句式不是很好地衬托渲染了今人怀旧时的那种缠绵悱恻的心绪吗?比如下句就很典型,我读之再三: When they were made the whistles weighed 750 pounds(340 kg)and could be heard more than 10 miles(16 km)away, according to the St. Paul Convention and Visitors Bureau, which hosted Saturday's event. 编辑先生,读者同志,不知你们是否同意我的以上分析。如果你们不同意,那么,是不是我过于善感了?】
文摘The present investigation is conducted to study the year wise (2011to 2018) changes of water hyacinth (Eichhornia crassipes) cover atSantragachi Lake a Wetland under National Wetland ConservationProgramme of India. Further the relationship between water hyacinthcover and the most abundant migratory waterbirds of Satragachi, LesserWhistling Teal (LWT;Dendrocygna javanica) is assessed because this birdspecies is prefer depending on water hyacinth mat for their roosting. Thestudy comprises of eight satellite images procured from Google earth (2011to 2018) to explore this relationship. A marked decline in the number ofLWT at Santragachi wetland is observed in the year of 2017 and 2018. Itis very interesting fact that from 2017-2018, the water hyacinth mat of thiswetland is almost cleared before winter and the result of cluster analysissupports this fact. Significant positive correlation is also observed withinLWT number and water hyacinth cover area (r = 0.7481 at p< 0.05) alongwith the total perimeter (r = 0.8648 at p< 0.05) of the water hyacinthislands at Santragachi wetland. However, open water area is also neededfor diving, swimming, food searching for the LWT and other waterbirds.Therefore, more study is needed to optimize the clearing operations,focused on optimizing the shape and size of water hyacinth islands forproper management of the waterbirds habitat.
文摘Some 1,500 years ago, people in the Gongbo area invented whistling arrows to enliven their celebration of bumper harvests and major events.Today, China lists shooting whistling arrows among ethnic minority sports events.Arrow, Bow and TargetThe whistling arrow is 0.6 meter long and is topped with a wooden head that is hollow. Square at the arrowbead,
基金supported by the National Natural Science Foundation of China (Grant No. 42104159)the APSCO Earthquake Project (Phase Ⅱ)+1 种基金ISSI-BJ International Team (Grant No. 2019-33)Dragon 5 Cooperation Proposal (Grant No. #59308)。
文摘Numerous studies have confirmed that electromagnetic disturbances before earthquakes can be observed by satellites.In this study,we use the C-value method that includes the acoustic whistle signature;pre-seismic ionospheric electromagnetic disturbance signals were acquired based on the CSES-01 satellite electric field data,and the maximum value of C in the earthquake preparation zones increased continuously from 2.0 three days before the earthquake and reached a maximum weight of 3.0 on the day of the earthquake,after the earthquake,it gradually decreased and recovered to about 2.0;its the C values fluctuated between-2 and 3,it is different from the C values range-2–12 of the previous seismic case study using the DEMETER satellite,which may be related to the orbital altitude and revisit period of the satellite.Then,the C values were normalized,and the time series analysis of the obtained θ values were done,and the results showed that:In the pregnant zone,the background variation of the disturbance amplitude θ is within 2σ,and the maximum disturbance amplitude of θ starts to increase gradually from the seventh period(one period of 5 days,i.e.,35–39 days before the earthquake),it reached 2σ by the fourth preseismic cycle(20–24 days before the earthquake),and then dropped sharply to about 1.5σ in the third pre-seismic cycle(15–19days before the earthquake),after two cycles of increase,the θ over the epicenter reached a maximum of 2.1σ at the time of the earthquake(combining the time of the earthquake and the satellite flight characteristics,the epicenter period is defined as January25-January 29,2020,and this defines the study time period line),and the θ decreases to within 2 times the standard range after the earthquake;The negative value of the disturbance amplitude θ in the central region of the pregnant seismic zone during the earthquake shows the transient energy release process.Through comparison,the θ values obtained by normalization based on the C-value method takes into account the variation of the background field,and the result can better reflect the energy change of the ionospheric field before the earthquakes.
文摘Recently,bionic signals have been used to achieve covert underwater acoustic communication(UWAC)with high signal-to-noise ratios(SNRs)over transmission systems.A high SNR allows the attackers to proceed with their mischievous goals and makes transmission systems vulnerable against malicious attacks.In this paper we propose an improved Merkle hash tree based secure scheme that can resist current underwater attacks,i.e.,replay attack,fabricated message attack,message-altering attack,and analyst attack.Security analysis is performed to prove that the proposed scheme can resist these types of attacks.Performance evaluations show that the proposed scheme can meet UWAC limitations due to its efficiency regarding energy consumption,communication overhead,and computation cost.
