The authors reassessed the taxonomic distinction of Iteravis huchzermeyeri and Gansus zheni,which are two species of Ornithuromorpha based on specimens from the same locality in western Liaoning and derive from the Je...The authors reassessed the taxonomic distinction of Iteravis huchzermeyeri and Gansus zheni,which are two species of Ornithuromorpha based on specimens from the same locality in western Liaoning and derive from the Jehol Biota.The detailed comparisons of the holotype and referred specimens of both species,reveal no anatomical features that distinguish these taxa as separate species.Some minor differences are considered to relate to ontogenetic or interspecific differences.The stratigraphic occurrence for both specimens is the Lower Cretaceous Jiufotang Formation.Accordingly,the authors conclude that Iteravis huchzermeyeri has priority,by 15 days,for this taxon and that Gansus zheni is a junior synonym.The diagnosis of Iteravis huchzermeyeri is revised based on further study on all specimens referred to this species.Its generic distinction from Gansus is maintained thereby removing a potential genus-level correlation linking Xiagou Formation in Gansu Province with the Jiufotang Formation in Liaoning Province.展开更多
In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet t...In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet the limit only when the measurement time is much longer than the relaxation time of the pendulum. By using the maximum likelihood estimation and the equation-of-motion filter operator, we propose an optimal(minimum variance, unbiased) amplitude estimation method without limitation of the measurement time, where thermal fluctuation is the leading noise. While processing the experimental data tests of the Newtonian gravitational inverse square law, the variance of our method has been improved than before and the measurement time of determining the amplitude with this method has been reduced about half than before for the same uncertainty. These results are significant for the torsion experiment when the measurement time is limited.展开更多
基金This work was supported by projects from the National Natural Science Foundation of China(41872018,41672019)the China Geological Survey(DD20190602)awarded to Xu-ri Wang.
文摘The authors reassessed the taxonomic distinction of Iteravis huchzermeyeri and Gansus zheni,which are two species of Ornithuromorpha based on specimens from the same locality in western Liaoning and derive from the Jehol Biota.The detailed comparisons of the holotype and referred specimens of both species,reveal no anatomical features that distinguish these taxa as separate species.Some minor differences are considered to relate to ontogenetic or interspecific differences.The stratigraphic occurrence for both specimens is the Lower Cretaceous Jiufotang Formation.Accordingly,the authors conclude that Iteravis huchzermeyeri has priority,by 15 days,for this taxon and that Gansus zheni is a junior synonym.The diagnosis of Iteravis huchzermeyeri is revised based on further study on all specimens referred to this species.Its generic distinction from Gansus is maintained thereby removing a potential genus-level correlation linking Xiagou Formation in Gansu Province with the Jiufotang Formation in Liaoning Province.
基金Project supported by the National Natural Science Foundation of China(Grant No.11575160)
文摘In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet the limit only when the measurement time is much longer than the relaxation time of the pendulum. By using the maximum likelihood estimation and the equation-of-motion filter operator, we propose an optimal(minimum variance, unbiased) amplitude estimation method without limitation of the measurement time, where thermal fluctuation is the leading noise. While processing the experimental data tests of the Newtonian gravitational inverse square law, the variance of our method has been improved than before and the measurement time of determining the amplitude with this method has been reduced about half than before for the same uncertainty. These results are significant for the torsion experiment when the measurement time is limited.
