Background:Most of long-distance migratory raptors suspend moult during migration but detailed information is patchy for most of the Palearctic species.The aim of this research is to verify if active moulting in migra...Background:Most of long-distance migratory raptors suspend moult during migration but detailed information is patchy for most of the Palearctic species.The aim of this research is to verify if active moulting in migrating Western Marsh Harriers occurs and to quantify the extent of moulting along the season focusing on primary feathers.Methods:During a whole post-breeding migration at the Strait of Messina in Southern Italy,we gathered information about symmetrical flight feather moult from 221 adults by taking pictures of raptors passing at close range.Results:We found active moulting primaries during autumn migration in 48.4% of our samples.Slight differences on the extension and timing among sex classes were recorded during the season,with adult females showing a more advanced moult stage than adult males.Conclusion:The finding that the extension of the suspended moult was already defined in migratory individuals might be explained as an adaptation to minimize the energy required for moulting during migration.展开更多
We investigated the water-crossing behavior of Western Marsh Harriers(Circus aeruginosus),mostly adults,and European Honey Buzzards(Pernis apivorus),mostly juveniles,in relation to wind conditions,time of the day,floc...We investigated the water-crossing behavior of Western Marsh Harriers(Circus aeruginosus),mostly adults,and European Honey Buzzards(Pernis apivorus),mostly juveniles,in relation to wind conditions,time of the day,flocking and age classes,at a watchsite in central Italy during the autumn migration en route to Africa.Although European Honey Buzzards are less suited than Western Marsh Harriers to undertake long sea crossings,they were more inclined to leave the coast when migrating in flocks.Few birds of both species chose to fly along the coast.Western Marsh Harriers,such as European Honey Buzzards migrating alone,undertook the water crossing rather than stopping migration(birds roosting at the site or flying back inland) during the absence of wind and vice versa during head winds.Conversely,European Honey Buzzards migrating in flocks were not affected in their decision(crossing or stopping migration) by wind direction.Both species undertook the water crossing rather than stopping migration during mornings and vice versa during afternoons.Finally,in both species,adults and juveniles showed the same behavior in front of a water barrier.This result was expected in the case of the Western Marsh Harrier but not from the European Honey Buzzard since,in this species,the water-crossing tendency is age dependent with adults avoiding sea crossings.Our study confirms that flocking significantly affects the water-crossing behavior of European Honey Buzzards during migration.Moreover,in this species,inexperience of juveniles and presumably younger adults,about the high energetic costs of long powered flight and about the existence of shorter routes over water,might explain the strong water-crossing tendency shown by migrants independently from their age.展开更多
Nd2Zr2O7 is being explored as an alternate thermal barrier coating （TBC） material for operating above 1300 ℃, and great effort has been made to enlarge its thermal expansion coefficient （TEC） and improve its toug...Nd2Zr2O7 is being explored as an alternate thermal barrier coating （TBC） material for operating above 1300 ℃, and great effort has been made to enlarge its thermal expansion coefficient （TEC） and improve its toughness. In this study, Sc203 vvas doped to Nd2Zr2O7. The phase structure, TECs and toughness of （Nd1-xScx）2Zr2O7 （x = 0, 0.025, 0.05, 0.075, 0.1 ） compounds were investigated. （Nd1-xScx）2Zr2O7 （x = 0, 0.025, 0.05, 0,075） exhibited pyrochlore structure, while （Nd0.9Sc0.1）2Zr2O7 consisted of pyrochlore and fluorite phases. With the increase of the Sc203 content, the ordering degree of the pyrochlore in the compounds decreased. In （Nd1-xScx）2Zr2O7 series, （Nd0.925Sc0.075）2Zr2O7 exhibited the largest TEC, while the toughness of the compounds increased with increasing the Sc2O3 content. The related mechanisms were discussed based on the crystal structure analysis. Considering the TEC and toughness, 10 mol% Sc2O3 was sug- gested as the optimal doping content for Nd2Zr2O7 ceramic.展开更多
Background: The Western Marsh Harrier(Circus aeruginosus) is a partial migrant with the populations from Eastern and Northern Europe migrating south to sub-Saharan Africa. During the autumn migration, that is peaking ...Background: The Western Marsh Harrier(Circus aeruginosus) is a partial migrant with the populations from Eastern and Northern Europe migrating south to sub-Saharan Africa. During the autumn migration, that is peaking in Septem ber, harriers move on a broad front heading SW and undertake long sea-crossings en route to their wintering quarters, passing in substantial numbers through Italy and Malta with the highest concentrations recorded at the Strait of Messina. Most of the individuals migrating across the Strait are heading for the wintering quarters in Africa, while fewer spend the winter in Sicily.Methods: In a 5-year study(2011-2015), between 26 August and 30 September, we determined age and sex of autumn migrating harriers through this flyway. In 2014 we determined, by marine radar and optical range finder, the flight altitude of migrating harriers.Results: A total of 10,261 Western Marsh Harriers were counted during the whole study, with an average of 2052 per autumn season. Adults outnumbered juveniles and males outnumbered females. Harriers flew at lower altitudes during the morning while large flocks flew lower than single birds or small flocks.Conclusions: Our observations are consistent with previous surveys and confirm that adult males have a tendency to migrate over a long distance, while substantial numbers of adult females and juveniles do not head for the wintering quarters in Africa. Finally, flight patterns recorded can be explained by a more pronounced flapping flight of Western Marsh Harriers during migration.展开更多
An efficient option pricing method based on Fourier-cosine expansions was presented by Fang and Oosterlee for European options in 2008, and later, this method was also used by them to price early-exercise options and ...An efficient option pricing method based on Fourier-cosine expansions was presented by Fang and Oosterlee for European options in 2008, and later, this method was also used by them to price early-exercise options and barrier options respectively, in 2009. In this paper, this method is applied to price discretely American barrier options in which the monitored dates are many times more than the exercise dates. The corresponding algorithm is presented to practical option pricing. Numerical experiments show that this algorithm works very well and efficiently for different exponential Levy asset models.展开更多
Background: Circus cyaneus is a medium-sized bird of prey that is widely distributed across the Northern Hemisphere. There are two currently recognized forms, the Palearctic form C. c. cyaneus(Hen Harrier), and the Ne...Background: Circus cyaneus is a medium-sized bird of prey that is widely distributed across the Northern Hemisphere. There are two currently recognized forms, the Palearctic form C. c. cyaneus(Hen Harrier), and the Nearctic form C. c. hudsonius(Northern Harrier). The forms have recently been split by the British Ornithologists' Union but the American Ornithologists' Union and some other taxonomic committees have not yet made any change. Here we examine the phylogenetic relationship between the two forms using sequence data from multiple nuclear and mitochondrial genes and examine breeding biology, body size, morphology, dispersal and other behaviors.Methods: In order to fully compare cyaneus and hudsonius, we carried out a full literature review, measured museum skins and carried out phylogenetic analysis using a number of different mitochondrial genes and compare our findings to other recent work.Results: We find that these two allopatric taxa form reciprocally monophyletic groups, show substantial mt DNA sequence divergence, and further differ significantly with respect to body size, plumage characters, breeding biology, dispersal and other behavioral traits.Conclusions: Based on an array of consistently divergent characteristics, it is suggested that the two forms are best regarded as separate species, Hen Harrier(Circus cyaneus) and Northern Harrier(Circus hudsonius).展开更多
Modern day VTOL fixed-wing aircraft based on quadplane design is relative<span style="font-family:Verdana;">ly simple and reliable due to lack of complex mechanical components</span><span styl...Modern day VTOL fixed-wing aircraft based on quadplane design is relative<span style="font-family:Verdana;">ly simple and reliable due to lack of complex mechanical components</span><span style="font-family:Verdana;"> com</span><span style="font-family:Verdana;">pared to tilt-wings or tilt-rotors in the pre-80’s era. Radio-controlled </span><span style="font-family:Verdana;">aerobatic airplanes have thrust-to-weight ratio of greater than unity and are capable of performing a range of impressive maneuvers including the so-called harrier maneuver. We hereby present a new maneuver known as the retarded harrier </span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">that is applicable to un/manned fixed-wing aircraft for achieving VTOL flight with a better forward flight performance than a quadplane in terms of weight, speed and esthetics.</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> An airplane with tandem roto-stabilizers is also presented as an efficient airframe to achieve VTOL via retarded harrier maneuver, and detailed analysis is given for hovering at 45° and 60° and comparison is made against the widely adopted quadplane. This work also includes experimental demonstration of retarded harrier maneuver using a small remotely pilot airplane of wingspan 650 mm.</span></span></span>展开更多
文摘Background:Most of long-distance migratory raptors suspend moult during migration but detailed information is patchy for most of the Palearctic species.The aim of this research is to verify if active moulting in migrating Western Marsh Harriers occurs and to quantify the extent of moulting along the season focusing on primary feathers.Methods:During a whole post-breeding migration at the Strait of Messina in Southern Italy,we gathered information about symmetrical flight feather moult from 221 adults by taking pictures of raptors passing at close range.Results:We found active moulting primaries during autumn migration in 48.4% of our samples.Slight differences on the extension and timing among sex classes were recorded during the season,with adult females showing a more advanced moult stage than adult males.Conclusion:The finding that the extension of the suspended moult was already defined in migratory individuals might be explained as an adaptation to minimize the energy required for moulting during migration.
文摘We investigated the water-crossing behavior of Western Marsh Harriers(Circus aeruginosus),mostly adults,and European Honey Buzzards(Pernis apivorus),mostly juveniles,in relation to wind conditions,time of the day,flocking and age classes,at a watchsite in central Italy during the autumn migration en route to Africa.Although European Honey Buzzards are less suited than Western Marsh Harriers to undertake long sea crossings,they were more inclined to leave the coast when migrating in flocks.Few birds of both species chose to fly along the coast.Western Marsh Harriers,such as European Honey Buzzards migrating alone,undertook the water crossing rather than stopping migration(birds roosting at the site or flying back inland) during the absence of wind and vice versa during head winds.Conversely,European Honey Buzzards migrating in flocks were not affected in their decision(crossing or stopping migration) by wind direction.Both species undertook the water crossing rather than stopping migration during mornings and vice versa during afternoons.Finally,in both species,adults and juveniles showed the same behavior in front of a water barrier.This result was expected in the case of the Western Marsh Harrier but not from the European Honey Buzzard since,in this species,the water-crossing tendency is age dependent with adults avoiding sea crossings.Our study confirms that flocking significantly affects the water-crossing behavior of European Honey Buzzards during migration.Moreover,in this species,inexperience of juveniles and presumably younger adults,about the high energetic costs of long powered flight and about the existence of shorter routes over water,might explain the strong water-crossing tendency shown by migrants independently from their age.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51501127 and 51375332)the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20120032110031)
文摘Nd2Zr2O7 is being explored as an alternate thermal barrier coating （TBC） material for operating above 1300 ℃, and great effort has been made to enlarge its thermal expansion coefficient （TEC） and improve its toughness. In this study, Sc203 vvas doped to Nd2Zr2O7. The phase structure, TECs and toughness of （Nd1-xScx）2Zr2O7 （x = 0, 0.025, 0.05, 0.075, 0.1 ） compounds were investigated. （Nd1-xScx）2Zr2O7 （x = 0, 0.025, 0.05, 0,075） exhibited pyrochlore structure, while （Nd0.9Sc0.1）2Zr2O7 consisted of pyrochlore and fluorite phases. With the increase of the Sc203 content, the ordering degree of the pyrochlore in the compounds decreased. In （Nd1-xScx）2Zr2O7 series, （Nd0.925Sc0.075）2Zr2O7 exhibited the largest TEC, while the toughness of the compounds increased with increasing the Sc2O3 content. The related mechanisms were discussed based on the crystal structure analysis. Considering the TEC and toughness, 10 mol% Sc2O3 was sug- gested as the optimal doping content for Nd2Zr2O7 ceramic.
基金supported by TERNA Rete Italia S.p.A.Parco Nazionale dell’Aspromontesupport provided by COST-European Cooperation in Science and Technology through the Action ES1305“European Network for the Radar Surveillance of Animal Movement”(ENRAM)
文摘Background: The Western Marsh Harrier(Circus aeruginosus) is a partial migrant with the populations from Eastern and Northern Europe migrating south to sub-Saharan Africa. During the autumn migration, that is peaking in Septem ber, harriers move on a broad front heading SW and undertake long sea-crossings en route to their wintering quarters, passing in substantial numbers through Italy and Malta with the highest concentrations recorded at the Strait of Messina. Most of the individuals migrating across the Strait are heading for the wintering quarters in Africa, while fewer spend the winter in Sicily.Methods: In a 5-year study(2011-2015), between 26 August and 30 September, we determined age and sex of autumn migrating harriers through this flyway. In 2014 we determined, by marine radar and optical range finder, the flight altitude of migrating harriers.Results: A total of 10,261 Western Marsh Harriers were counted during the whole study, with an average of 2052 per autumn season. Adults outnumbered juveniles and males outnumbered females. Harriers flew at lower altitudes during the morning while large flocks flew lower than single birds or small flocks.Conclusions: Our observations are consistent with previous surveys and confirm that adult males have a tendency to migrate over a long distance, while substantial numbers of adult females and juveniles do not head for the wintering quarters in Africa. Finally, flight patterns recorded can be explained by a more pronounced flapping flight of Western Marsh Harriers during migration.
基金supported by the research grants (UL020/08-Y4/MAT/JXQ01/FST and MYRG136(Y1-L2)-FST11-DD) from University of Macao
文摘An efficient option pricing method based on Fourier-cosine expansions was presented by Fang and Oosterlee for European options in 2008, and later, this method was also used by them to price early-exercise options and barrier options respectively, in 2009. In this paper, this method is applied to price discretely American barrier options in which the monitored dates are many times more than the exercise dates. The corresponding algorithm is presented to practical option pricing. Numerical experiments show that this algorithm works very well and efficiently for different exponential Levy asset models.
基金The costs for the Cytochrome b sequencing and sample procurement was provided by the Museum of Vertebrate Zoology,UC Berkeley.Transport costs for museum visits were met by GJE
文摘Background: Circus cyaneus is a medium-sized bird of prey that is widely distributed across the Northern Hemisphere. There are two currently recognized forms, the Palearctic form C. c. cyaneus(Hen Harrier), and the Nearctic form C. c. hudsonius(Northern Harrier). The forms have recently been split by the British Ornithologists' Union but the American Ornithologists' Union and some other taxonomic committees have not yet made any change. Here we examine the phylogenetic relationship between the two forms using sequence data from multiple nuclear and mitochondrial genes and examine breeding biology, body size, morphology, dispersal and other behaviors.Methods: In order to fully compare cyaneus and hudsonius, we carried out a full literature review, measured museum skins and carried out phylogenetic analysis using a number of different mitochondrial genes and compare our findings to other recent work.Results: We find that these two allopatric taxa form reciprocally monophyletic groups, show substantial mt DNA sequence divergence, and further differ significantly with respect to body size, plumage characters, breeding biology, dispersal and other behavioral traits.Conclusions: Based on an array of consistently divergent characteristics, it is suggested that the two forms are best regarded as separate species, Hen Harrier(Circus cyaneus) and Northern Harrier(Circus hudsonius).
文摘Modern day VTOL fixed-wing aircraft based on quadplane design is relative<span style="font-family:Verdana;">ly simple and reliable due to lack of complex mechanical components</span><span style="font-family:Verdana;"> com</span><span style="font-family:Verdana;">pared to tilt-wings or tilt-rotors in the pre-80’s era. Radio-controlled </span><span style="font-family:Verdana;">aerobatic airplanes have thrust-to-weight ratio of greater than unity and are capable of performing a range of impressive maneuvers including the so-called harrier maneuver. We hereby present a new maneuver known as the retarded harrier </span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">that is applicable to un/manned fixed-wing aircraft for achieving VTOL flight with a better forward flight performance than a quadplane in terms of weight, speed and esthetics.</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> An airplane with tandem roto-stabilizers is also presented as an efficient airframe to achieve VTOL via retarded harrier maneuver, and detailed analysis is given for hovering at 45° and 60° and comparison is made against the widely adopted quadplane. This work also includes experimental demonstration of retarded harrier maneuver using a small remotely pilot airplane of wingspan 650 mm.</span></span></span>
