Flight feathers of birds interact with the air flow during flight.How the observed low drag and high lift values at wind speeds from 9.0 to 19.8 m/s can be achieved due to the feather aerodynamics remains unknown.In t...Flight feathers of birds interact with the air flow during flight.How the observed low drag and high lift values at wind speeds from 9.0 to 19.8 m/s can be achieved due to the feather aerodynamics remains unknown.In the present paper,we tested and compared morphological changes,drag reduction and flow visualization results of intact,damaged,and artificial feathers at different wind speeds in a wind tunnel.Through the analysis of the drag force and resultant force angle,we proved that the integrity of feathers,whose barbs are usually closely interconnected,played an important role in the drag,which potentially triggers excellent drag reduction performance.The wind tunnel tests indicated that intact secondary feathers had a surprisingly high maximum drag reduction property at v?=?9 m/s compared with the feathers,where the integrity of barbs was damaged.The hook cascades facilitated elasticity under pressure and suitable permeability in an intact feather,when the hooks were interlocked.It was indicated that the suitable permeability of intact feathers would prevent flow separation and reduce drag force at low wind speed;at high wind speed,elasticity under pressure and suitable permeability in an intact feather would facilitate strong squeezing effect,helping feathers withstand larger aerodynamic forces to which they might be subjected during flight.It was revealed that the intact secondary feather is a compromise between strong lift generation and drag reduction,which has a great significance for the bird’s flight.展开更多
We explored the morphological organization of the skull within Crocodylidae,analyzing functional and phylogenetic interactions between its 2 constituent functional modules:the rostrum and the postrostrum.We used...We explored the morphological organization of the skull within Crocodylidae,analyzing functional and phylogenetic interactions between its 2 constituent functional modules:the rostrum and the postrostrum.We used geometric morphometrics to identify localized shape changes,focusing on the differences between the major clades of the crown-group Crocodylia:Alligatoridae and Crocodylidae.We used published bite performance data to correlate rostral function with postrostral morphology.The skull modules appear more integrated within Alligatoridae than within Crocodyliade.Phylogenetic effects on shape variation are more evident in Alligatoridae than in Crocodylidae,where functional parameters concerning the rostral morphology are proportionally more important than phylogeny.Long-snouted species are characterized by low structural performance,which is significantly associated with a reduction of the pterygoid-quadrate cranial nipper,suggesting that the nipper is important for the ingestion of large food items in generalist species.This functional association is coupled with a significant evolutionary allometry at the clade level,while Alligatoridae and Crocodylidae show different degrees of evolutionary allometry for their entire shape and rostrum.The postrostrum is more conservative than the rostrum in terms of morphospace occupation,evolutionary allometry and phylogenetic signal.展开更多
This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by ...This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by using CASA-Mot and CASA-Morph system and principal component (PC) analysis. For motility, eight kinematic parameters were evaluated, which were reduced to PC1, related to linear variables, and PC2, related to oscillatory movement. The whole population was divided into three independent subpopulations: SP1, fast cells with linear movement; SP2, slow cells and nonoscillatory motility; and SP3, medium speed cells and oscillatory movement. In almost all cases, the subpopulation distribution by animal was significantly different. Head morphology analysis generated four size and four shape parameters, which were reduced to PC 1, related to size, and PC2, related to shape of the cells. Three morphometric subpopulations existed. SPI: large oval cells; SP2: medium size elongated cells; and SP3. small and short cells. The subpopulation distribution differed between animals. Combining the kinematic and morphometric datasets produced PC1, related to morphometric parameters, and PC2, related to kinematics, which generated four sperm subpopulations - SPI.. high oscillatory motility, large and short heads; SP2; medium velocity with small and short heads; SP3. slow motion small and elongated cells; and SP4. high linear speed and large elongated cells. Subpopulation distribution was different in all animals. The establishment of sperm subpopulations from kinematic, morphometric, and combined variables not only improves the well-defined fox semen characteristics and offers a good conceptual basis for fertility and sperm preservation techniques in this species, but also opens the door to use this approach in other species, included humans.展开更多
基金This work was supported by the Chinesisch-Deutsches Zentrumfur Wissenschaftsforderung to SNG and ZDD(Grant No.GZl154)the National Natural Science Foundation of China(Grant Nos.51875281,51861135306)。
文摘Flight feathers of birds interact with the air flow during flight.How the observed low drag and high lift values at wind speeds from 9.0 to 19.8 m/s can be achieved due to the feather aerodynamics remains unknown.In the present paper,we tested and compared morphological changes,drag reduction and flow visualization results of intact,damaged,and artificial feathers at different wind speeds in a wind tunnel.Through the analysis of the drag force and resultant force angle,we proved that the integrity of feathers,whose barbs are usually closely interconnected,played an important role in the drag,which potentially triggers excellent drag reduction performance.The wind tunnel tests indicated that intact secondary feathers had a surprisingly high maximum drag reduction property at v?=?9 m/s compared with the feathers,where the integrity of barbs was damaged.The hook cascades facilitated elasticity under pressure and suitable permeability in an intact feather,when the hooks were interlocked.It was indicated that the suitable permeability of intact feathers would prevent flow separation and reduce drag force at low wind speed;at high wind speed,elasticity under pressure and suitable permeability in an intact feather would facilitate strong squeezing effect,helping feathers withstand larger aerodynamic forces to which they might be subjected during flight.It was revealed that the intact secondary feather is a compromise between strong lift generation and drag reduction,which has a great significance for the bird’s flight.
基金Paolo Piras had access to the collections of the Natural History Museum in London,the Institut Royal des Sciences Naturelles in Bruxelles and the Museum d’Histoire Naturelle in Paris thanks to the SYNTHESYS program,and to the collection of the Field Museum in Chicago thanks to the Visiting Scholarship Program.Funds from the Geological Science Department of‘Roma Tre’University made possible the visit to the American Museum of Natural History,New York.Part of this research was conducted during a postdoctoral visit by Paolo Piras,supervised by Jorge Cubo,to the UniversitéPierre et Marie Curie.Funds were also provided by Project CGL-2009-11838 from the Spanish Ministerio de Ciencia e Innovacion Cientifica,Spain.
文摘We explored the morphological organization of the skull within Crocodylidae,analyzing functional and phylogenetic interactions between its 2 constituent functional modules:the rostrum and the postrostrum.We used geometric morphometrics to identify localized shape changes,focusing on the differences between the major clades of the crown-group Crocodylia:Alligatoridae and Crocodylidae.We used published bite performance data to correlate rostral function with postrostral morphology.The skull modules appear more integrated within Alligatoridae than within Crocodyliade.Phylogenetic effects on shape variation are more evident in Alligatoridae than in Crocodylidae,where functional parameters concerning the rostral morphology are proportionally more important than phylogeny.Long-snouted species are characterized by low structural performance,which is significantly associated with a reduction of the pterygoid-quadrate cranial nipper,suggesting that the nipper is important for the ingestion of large food items in generalist species.This functional association is coupled with a significant evolutionary allometry at the clade level,while Alligatoridae and Crocodylidae show different degrees of evolutionary allometry for their entire shape and rostrum.The postrostrum is more conservative than the rostrum in terms of morphospace occupation,evolutionary allometry and phylogenetic signal.
文摘This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by using CASA-Mot and CASA-Morph system and principal component (PC) analysis. For motility, eight kinematic parameters were evaluated, which were reduced to PC1, related to linear variables, and PC2, related to oscillatory movement. The whole population was divided into three independent subpopulations: SP1, fast cells with linear movement; SP2, slow cells and nonoscillatory motility; and SP3, medium speed cells and oscillatory movement. In almost all cases, the subpopulation distribution by animal was significantly different. Head morphology analysis generated four size and four shape parameters, which were reduced to PC 1, related to size, and PC2, related to shape of the cells. Three morphometric subpopulations existed. SPI: large oval cells; SP2: medium size elongated cells; and SP3. small and short cells. The subpopulation distribution differed between animals. Combining the kinematic and morphometric datasets produced PC1, related to morphometric parameters, and PC2, related to kinematics, which generated four sperm subpopulations - SPI.. high oscillatory motility, large and short heads; SP2; medium velocity with small and short heads; SP3. slow motion small and elongated cells; and SP4. high linear speed and large elongated cells. Subpopulation distribution was different in all animals. The establishment of sperm subpopulations from kinematic, morphometric, and combined variables not only improves the well-defined fox semen characteristics and offers a good conceptual basis for fertility and sperm preservation techniques in this species, but also opens the door to use this approach in other species, included humans.