Lion populations are declining globally, including in Tanzania, and Africa. However, Katavi National Park is a landscape with potential for a sustainable and healthy population of African lions (Panthera leo), but the...Lion populations are declining globally, including in Tanzania, and Africa. However, Katavi National Park is a landscape with potential for a sustainable and healthy population of African lions (Panthera leo), but there is currently limited reliable data indicating density and population size. This hinders the development of conservation action plans, including population monitoring, for this species. To address this data gap, we assessed lions’ demography and population estimates (population size and density) in the Katavi National Park using a call-back survey method. In addition, we assessed ecological factors that influenced distribution of lions to the call-back stations. Our estimated population size revealed 84 lions (95% CI 53 - 116), with a density of 5/100 km<sup>2</sup> (95% CI 3.14 - 6.86) in the sampled area, representing 38% of the total park. This resulted in an estimated 214 individuals when extrapolated to the whole park. Sixty-seven percent of lions that responded to the stations were female, and ecological factors that significantly influenced their distribution included elevation, land cover, precipitation, temperature, wind speed, and prey abundance. Our results suggest that female lions are more abundant than males in Katavi National Park and that population size and density estimates, as well as understanding prey-lion relations, are important indices for lion monitoring and identifying conservation priorities. Further, our study suggests that the call-back survey method is an effective, rapid, and less costly population assessment method for lions, may be useful for assessing other social species in the Katavi ecosystem and can be a useful tool for community engagement and contributing to scientific monitoring.展开更多
THE Cameroonian players went wild with joywhen the referee blew the final whistle, ending the match against their Egyptian opponents with an unexpected 2-1 win. Thus ended the 31st edition of the African Cup of Natio...THE Cameroonian players went wild with joywhen the referee blew the final whistle, ending the match against their Egyptian opponents with an unexpected 2-1 win. Thus ended the 31st edition of the African Cup of Nations （ACN）, which took place in Gabon from January 14 to February 5, 2017.展开更多
movies, Zamble Serge, a martial arts lover from Cote d＇lvoire, came to the equally legendary Shaolin Temple nestled in the forested Songshan Mountain in central China＇s Henan Province, to perfect his own skills at t...movies, Zamble Serge, a martial arts lover from Cote d＇lvoire, came to the equally legendary Shaolin Temple nestled in the forested Songshan Mountain in central China＇s Henan Province, to perfect his own skills at the Buddhist monastery renowned as a seat of kungfu, the Chinese martial arts.展开更多
Understanding the factors that facilitate the emergence of cooperation among organisms is central to the study of social evolution. Spotted hyenas Crocuta crocuta frequently cooperate to mob lions Panthera leo, approa...Understanding the factors that facilitate the emergence of cooperation among organisms is central to the study of social evolution. Spotted hyenas Crocuta crocuta frequently cooperate to mob lions Panthera leo, approaching the lions as a tightknit group while vocalizing loudly in an attempt to overwhelm them and drive them away. Whereas cooperative mobbing behavior has been well documented in birds and some mammals, to our knowledge it has never been described during interactions between 2 apex predators. Using a 27-year dataset, we characterize lion-hyena encoun- ters, assess rates of mobbing behavior observed during these interactions, and inquire whether mobbing results in successful acquisition of food. Lions and hyenas interacted most often at fresh kills, especially as prey size and the number of hyenas present increased. Possession of food at the beginning of an interaction positively affected retention of that food by each predator species. The presence of male lions increased the probability of an interspecific interaction but decreased the likelihood of hyenas obtaining or retaining possession of the food. Hyena mobbing rates were highest at fresh kills, but lower when adult male lions were present. The occurrence of mobbing was predicted by an increase in the number of hyenas present. Whether or not mobbing resulted in acquisition of food from lions was predicted by an increase in the number of mobs formed by the hyenas present, suggesting that cooperation among hyenas enhances their fitness.展开更多
Interspecific interactions are key drivers of individual and population-level fitness in a wide range of animals.However,in marine ecosystems,it is relatively unknown which biotic and abiotic factors impact behavioral...Interspecific interactions are key drivers of individual and population-level fitness in a wide range of animals.However,in marine ecosystems,it is relatively unknown which biotic and abiotic factors impact behavioral interactions between competing species.We assessed the impact of weather,marine productivity,and population structure on the behavioral agonistic interactions between South American fur seals(SAFSs),Arctocephalus australis,and South American sea lions(SASLs),Otaria byronia,in a breeding colony of SAFS.We hypothesized that agonistic interactions between SAFSs and SASLs respond to biotic and abiotic factors such as SAFS population structure,marine productivity,and weather.We found that SASL and SAFS interactions almost always resulted in negative impacts on the social structure or reproductive success of the SAFS colony.SASL adult males initiated stampedes of SAFS and/or abducted and predated SAFS pups.Adult SAFS males abundance and severe weather events were negatively correlated with agonistic interactions between species.However,proxies for lower marine productivity such as higher sea surface temperature and lower catches of demerso-pelagic fish were the most important predictors of more frequent agonistic interactions between SAFS and SASL.Under the current scenario of decline in marine biomass due to global climate change and overfishing,agonistic interactions between competing marine predators could increase and exacerbate the negative impacts of environmental change in these species.展开更多
Neurological signs like ataxia and hind limb paresis have often been reported in cheetahs (Acinonyx jubatus), lions (Panthera leo) and snow leopards (Panthera unica). As a cause, copper and Vitamin A deficiencies have...Neurological signs like ataxia and hind limb paresis have often been reported in cheetahs (Acinonyx jubatus), lions (Panthera leo) and snow leopards (Panthera unica). As a cause, copper and Vitamin A deficiencies have been discussed. Many cases were seen in cheetahs and lions in the United Arab Emirates (UAE) within the last years. The aim of this study was to find correlations between nutrition, serum, and tissue levels, focusing on copper and Vitamin A. Blood and tissue samples of affected and unaffected animals were analyzed at the Central Veterinary Research Laboratory in Dubai, UAE. Animals were split into three different groups (A, B and C) according to their diets. Minerals were determined in serum, tissue, food and water samples, and serum was additionally analyzed for Vitamin A and E. Liver, kidney and spinal cord samples were taken for histopathological investigations. Mean serum copper and liver copper levels of animals fed pure chicken muscle meat without supplements were significantly lower (0.41 ± 0.71 μM/L;2.16 ± 0.95 ppm wet weight) than in animals fed a whole carcass prey diet (12.16 ± 3.42 μM/L;16.01 ± 17.51 ppm wet weight) (p < 0.05). Serum Vitamin A and E levels were highest in animals fed whole carcass prey diets (1.85 ± 0.68;27.31 ± 5.69 μM/L). Liver zinc concentrations were highest in animals fed pure chicken meat only (43.75 ± 16.48 ppm wet weight). In histopathology, demyelination of the spinal cord was found in all of the affected animals and most commonly when fed a diet based on poultry without supplements.展开更多
Inspired by cooperative hunting of lionesses,this paper presents a Lions Group Algorithm for cooperative hunting tasks involving multiple AUVs(autonomous underwater vehicles).The lions group algorithm is developed aro...Inspired by cooperative hunting of lionesses,this paper presents a Lions Group Algorithm for cooperative hunting tasks involving multiple AUVs(autonomous underwater vehicles).The lions group algorithm is developed around two core relationships:the dynamic game relationship between the hunters and the target and the cooperative relationship between hunters.In this paper,the lions group algorithm is divided into three stages.In each stage,the dynamic game model between the hunters and the target is constructed,and the cooperation model between the hunters is constructed.At the same time,in these three phases,a dynamic allocationmechanism for the roles and tasks of hunterswas established.The simulation experiment revealed the hunting effect.The results show that the path planning and obstacle avoidance strategy of the hunters,the target’s escape strategy,the complexity of the environment,and the speed relationship between the hunter and the target affect the hunting effect.展开更多
As 1.5 million wildebeest pierce the dawn mist of the East African Rift Valley and the roar of lions merges with the cry of zebras beneath sprawling acacia trees,this land unveils life at its rawest-majestic and achin...As 1.5 million wildebeest pierce the dawn mist of the East African Rift Valley and the roar of lions merges with the cry of zebras beneath sprawling acacia trees,this land unveils life at its rawest-majestic and achingly fragile.展开更多
I.请根据录音,填写单词或把单词补充完整。II.听对话,选择正确的答案。1.What is Emily’s favorite animal?A.Dolphins.B.Lions.C.Elephants.D.Tigers.2.How fast can dolphins swim?A.10 miles per hour.B.20 miles per hour.C.30 mil...I.请根据录音,填写单词或把单词补充完整。II.听对话,选择正确的答案。1.What is Emily’s favorite animal?A.Dolphins.B.Lions.C.Elephants.D.Tigers.2.How fast can dolphins swim?A.10 miles per hour.B.20 miles per hour.C.30 miles per hour.D.40 miles per hour.展开更多
LION(evoLedv sIng mOmeNumt)是Google公司通过启发式程序搜索的方式发现的优化器,是一种独特的基于学习的优化算法。LION算法通过在上步动量和本步梯度之间维持两个不同的插值,并有效结合了解耦的权重衰减技术,实现了超越传统符号梯度...LION(evoLedv sIng mOmeNumt)是Google公司通过启发式程序搜索的方式发现的优化器,是一种独特的基于学习的优化算法。LION算法通过在上步动量和本步梯度之间维持两个不同的插值,并有效结合了解耦的权重衰减技术,实现了超越传统符号梯度下降类算法的性能。LION算法在许多大规模深度学习问题中展现了较强的优势,得到了广泛的应用。然而,尽管已有工作已经证明了LION的收敛性,但尚未有研究给出一个全面的收敛速度分析。已有研究证明,LION能够解决一类特定的盒约束优化问题,本文着重证明了,在?1范数度量下,LION收敛到这类问题的Karush-Kuhn-Tucker(KKT)点的速度为(Q√dK^(-1/4)),其中d为问题维度,K为算法的迭代步数。更进一步,我们移除了约束条件,证明LION在一般无约束问题上以相同的速度收敛至目标函数的驻点。与已有研究工作相比,本文证明的收敛速度达到了关于问题维度d的最优依赖关系;关于迭代步数K,这一速度还达到了非凸优化问题中随机梯度类算法能实现的最优理论下界。此外,这一理论下界以梯度的?2范数度量,而LION所属的符号梯度下降类算法通常度量的是更大的?1范数。由于在不同的梯度范数度量下关于问题维度d得到的收敛速度结果会有所差异,为了验证本文证明的收敛速度关于维度d同样是最优的,我们在多种深度学习任务上设计了全面的实验,不仅证明了LION与同样匹配理论下界的随机梯度下降法相比具有更低的训练损失和更强的性能,而且还验证了LION算法在迭代过程中梯度的ℓ_(1)/ℓ_(2)范数比始终处于Q(√d)的量级,从而在经验上说明了本文证明的收敛速度同样匹配关于d的最优下界。展开更多
Let ? be a bounded and connected open subset of R^N with a Lipschitzcontinuous boundary,the set ? being locally on the same side of ??.A vector version of a fundamental lemma of J.L.Lions,due to C.Amrouche,the first a...Let ? be a bounded and connected open subset of R^N with a Lipschitzcontinuous boundary,the set ? being locally on the same side of ??.A vector version of a fundamental lemma of J.L.Lions,due to C.Amrouche,the first author,L.Gratie and S.Kesavan,asserts that any vector field v =(vi) ∈(D′(?))~N,such that all the components 1/2(?_jv_i + ?_iv_j),1 ≤ i,j ≤ N,of its symmetrized gradient matrix field are in the space H^(-1)(?),is in effect in the space(L^2(?))~N.The objective of this paper is to show that this vector version of J.L.Lions lemma is equivalent to a certain number of other properties of interest by themselves.These include in particular a vector version of a well-known inequality due to J.Neˇcas,weak versions of the classical Donati and Saint-Venant compatibility conditions for a matrix field to be the symmetrized gradient matrix field of a vector field,or a natural vector version of a fundamental surjectivity property of the divergence operator.展开更多
In this paper,we consider the equivalent conditions with L^(p)-version(1<p<∞)of the J.L.Lions lemma.As applications,we first derive the existence of a weak solution to the Maxwell-Stokes type problem and then w...In this paper,we consider the equivalent conditions with L^(p)-version(1<p<∞)of the J.L.Lions lemma.As applications,we first derive the existence of a weak solution to the Maxwell-Stokes type problem and then we consider the Korn inequality.Furthermore,we consider the relation to other fundamental results.展开更多
文摘Lion populations are declining globally, including in Tanzania, and Africa. However, Katavi National Park is a landscape with potential for a sustainable and healthy population of African lions (Panthera leo), but there is currently limited reliable data indicating density and population size. This hinders the development of conservation action plans, including population monitoring, for this species. To address this data gap, we assessed lions’ demography and population estimates (population size and density) in the Katavi National Park using a call-back survey method. In addition, we assessed ecological factors that influenced distribution of lions to the call-back stations. Our estimated population size revealed 84 lions (95% CI 53 - 116), with a density of 5/100 km<sup>2</sup> (95% CI 3.14 - 6.86) in the sampled area, representing 38% of the total park. This resulted in an estimated 214 individuals when extrapolated to the whole park. Sixty-seven percent of lions that responded to the stations were female, and ecological factors that significantly influenced their distribution included elevation, land cover, precipitation, temperature, wind speed, and prey abundance. Our results suggest that female lions are more abundant than males in Katavi National Park and that population size and density estimates, as well as understanding prey-lion relations, are important indices for lion monitoring and identifying conservation priorities. Further, our study suggests that the call-back survey method is an effective, rapid, and less costly population assessment method for lions, may be useful for assessing other social species in the Katavi ecosystem and can be a useful tool for community engagement and contributing to scientific monitoring.
文摘THE Cameroonian players went wild with joywhen the referee blew the final whistle, ending the match against their Egyptian opponents with an unexpected 2-1 win. Thus ended the 31st edition of the African Cup of Nations （ACN）, which took place in Gabon from January 14 to February 5, 2017.
文摘movies, Zamble Serge, a martial arts lover from Cote d＇lvoire, came to the equally legendary Shaolin Temple nestled in the forested Songshan Mountain in central China＇s Henan Province, to perfect his own skills at the Buddhist monastery renowned as a seat of kungfu, the Chinese martial arts.
文摘Understanding the factors that facilitate the emergence of cooperation among organisms is central to the study of social evolution. Spotted hyenas Crocuta crocuta frequently cooperate to mob lions Panthera leo, approaching the lions as a tightknit group while vocalizing loudly in an attempt to overwhelm them and drive them away. Whereas cooperative mobbing behavior has been well documented in birds and some mammals, to our knowledge it has never been described during interactions between 2 apex predators. Using a 27-year dataset, we characterize lion-hyena encoun- ters, assess rates of mobbing behavior observed during these interactions, and inquire whether mobbing results in successful acquisition of food. Lions and hyenas interacted most often at fresh kills, especially as prey size and the number of hyenas present increased. Possession of food at the beginning of an interaction positively affected retention of that food by each predator species. The presence of male lions increased the probability of an interspecific interaction but decreased the likelihood of hyenas obtaining or retaining possession of the food. Hyena mobbing rates were highest at fresh kills, but lower when adult male lions were present. The occurrence of mobbing was predicted by an increase in the number of hyenas present. Whether or not mobbing resulted in acquisition of food from lions was predicted by an increase in the number of mobs formed by the hyenas present, suggesting that cooperation among hyenas enhances their fitness.
基金This work was partially funded by“Rufford Small Grants Foundation”(grant number 18815-1)Morris Animal Foundation(grant number D16ZO-413).
文摘Interspecific interactions are key drivers of individual and population-level fitness in a wide range of animals.However,in marine ecosystems,it is relatively unknown which biotic and abiotic factors impact behavioral interactions between competing species.We assessed the impact of weather,marine productivity,and population structure on the behavioral agonistic interactions between South American fur seals(SAFSs),Arctocephalus australis,and South American sea lions(SASLs),Otaria byronia,in a breeding colony of SAFS.We hypothesized that agonistic interactions between SAFSs and SASLs respond to biotic and abiotic factors such as SAFS population structure,marine productivity,and weather.We found that SASL and SAFS interactions almost always resulted in negative impacts on the social structure or reproductive success of the SAFS colony.SASL adult males initiated stampedes of SAFS and/or abducted and predated SAFS pups.Adult SAFS males abundance and severe weather events were negatively correlated with agonistic interactions between species.However,proxies for lower marine productivity such as higher sea surface temperature and lower catches of demerso-pelagic fish were the most important predictors of more frequent agonistic interactions between SAFS and SASL.Under the current scenario of decline in marine biomass due to global climate change and overfishing,agonistic interactions between competing marine predators could increase and exacerbate the negative impacts of environmental change in these species.
文摘Neurological signs like ataxia and hind limb paresis have often been reported in cheetahs (Acinonyx jubatus), lions (Panthera leo) and snow leopards (Panthera unica). As a cause, copper and Vitamin A deficiencies have been discussed. Many cases were seen in cheetahs and lions in the United Arab Emirates (UAE) within the last years. The aim of this study was to find correlations between nutrition, serum, and tissue levels, focusing on copper and Vitamin A. Blood and tissue samples of affected and unaffected animals were analyzed at the Central Veterinary Research Laboratory in Dubai, UAE. Animals were split into three different groups (A, B and C) according to their diets. Minerals were determined in serum, tissue, food and water samples, and serum was additionally analyzed for Vitamin A and E. Liver, kidney and spinal cord samples were taken for histopathological investigations. Mean serum copper and liver copper levels of animals fed pure chicken muscle meat without supplements were significantly lower (0.41 ± 0.71 μM/L;2.16 ± 0.95 ppm wet weight) than in animals fed a whole carcass prey diet (12.16 ± 3.42 μM/L;16.01 ± 17.51 ppm wet weight) (p < 0.05). Serum Vitamin A and E levels were highest in animals fed whole carcass prey diets (1.85 ± 0.68;27.31 ± 5.69 μM/L). Liver zinc concentrations were highest in animals fed pure chicken meat only (43.75 ± 16.48 ppm wet weight). In histopathology, demyelination of the spinal cord was found in all of the affected animals and most commonly when fed a diet based on poultry without supplements.
文摘Inspired by cooperative hunting of lionesses,this paper presents a Lions Group Algorithm for cooperative hunting tasks involving multiple AUVs(autonomous underwater vehicles).The lions group algorithm is developed around two core relationships:the dynamic game relationship between the hunters and the target and the cooperative relationship between hunters.In this paper,the lions group algorithm is divided into three stages.In each stage,the dynamic game model between the hunters and the target is constructed,and the cooperation model between the hunters is constructed.At the same time,in these three phases,a dynamic allocationmechanism for the roles and tasks of hunterswas established.The simulation experiment revealed the hunting effect.The results show that the path planning and obstacle avoidance strategy of the hunters,the target’s escape strategy,the complexity of the environment,and the speed relationship between the hunter and the target affect the hunting effect.
文摘As 1.5 million wildebeest pierce the dawn mist of the East African Rift Valley and the roar of lions merges with the cry of zebras beneath sprawling acacia trees,this land unveils life at its rawest-majestic and achingly fragile.
文摘I.请根据录音,填写单词或把单词补充完整。II.听对话,选择正确的答案。1.What is Emily’s favorite animal?A.Dolphins.B.Lions.C.Elephants.D.Tigers.2.How fast can dolphins swim?A.10 miles per hour.B.20 miles per hour.C.30 miles per hour.D.40 miles per hour.
文摘LION(evoLedv sIng mOmeNumt)是Google公司通过启发式程序搜索的方式发现的优化器,是一种独特的基于学习的优化算法。LION算法通过在上步动量和本步梯度之间维持两个不同的插值,并有效结合了解耦的权重衰减技术,实现了超越传统符号梯度下降类算法的性能。LION算法在许多大规模深度学习问题中展现了较强的优势,得到了广泛的应用。然而,尽管已有工作已经证明了LION的收敛性,但尚未有研究给出一个全面的收敛速度分析。已有研究证明,LION能够解决一类特定的盒约束优化问题,本文着重证明了,在?1范数度量下,LION收敛到这类问题的Karush-Kuhn-Tucker(KKT)点的速度为(Q√dK^(-1/4)),其中d为问题维度,K为算法的迭代步数。更进一步,我们移除了约束条件,证明LION在一般无约束问题上以相同的速度收敛至目标函数的驻点。与已有研究工作相比,本文证明的收敛速度达到了关于问题维度d的最优依赖关系;关于迭代步数K,这一速度还达到了非凸优化问题中随机梯度类算法能实现的最优理论下界。此外,这一理论下界以梯度的?2范数度量,而LION所属的符号梯度下降类算法通常度量的是更大的?1范数。由于在不同的梯度范数度量下关于问题维度d得到的收敛速度结果会有所差异,为了验证本文证明的收敛速度关于维度d同样是最优的,我们在多种深度学习任务上设计了全面的实验,不仅证明了LION与同样匹配理论下界的随机梯度下降法相比具有更低的训练损失和更强的性能,而且还验证了LION算法在迭代过程中梯度的ℓ_(1)/ℓ_(2)范数比始终处于Q(√d)的量级,从而在经验上说明了本文证明的收敛速度同样匹配关于d的最优下界。
基金supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(No.9041738-CityU 100612)
文摘Let ? be a bounded and connected open subset of R^N with a Lipschitzcontinuous boundary,the set ? being locally on the same side of ??.A vector version of a fundamental lemma of J.L.Lions,due to C.Amrouche,the first author,L.Gratie and S.Kesavan,asserts that any vector field v =(vi) ∈(D′(?))~N,such that all the components 1/2(?_jv_i + ?_iv_j),1 ≤ i,j ≤ N,of its symmetrized gradient matrix field are in the space H^(-1)(?),is in effect in the space(L^2(?))~N.The objective of this paper is to show that this vector version of J.L.Lions lemma is equivalent to a certain number of other properties of interest by themselves.These include in particular a vector version of a well-known inequality due to J.Neˇcas,weak versions of the classical Donati and Saint-Venant compatibility conditions for a matrix field to be the symmetrized gradient matrix field of a vector field,or a natural vector version of a fundamental surjectivity property of the divergence operator.
文摘In this paper,we consider the equivalent conditions with L^(p)-version(1<p<∞)of the J.L.Lions lemma.As applications,we first derive the existence of a weak solution to the Maxwell-Stokes type problem and then we consider the Korn inequality.Furthermore,we consider the relation to other fundamental results.
