Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncer...Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncertain.Beyond timing,procedural choices in PGT-A must balance diagnostic yield against potential harm from additional handling(e.g.,repeat TE biopsy or cryopreservation steps),as underscored by a recent systematic review and meta-analysis[1].展开更多
针对单频地基增强系统(Ground Based Augmentation System,GBAS)中电离层异常时Hatch滤波器平滑精度降低问题,系统分析了电离层延时对Hatch滤波器平滑精度的影响,提出一种改进自适应Hatch滤波算法。根据卫星信号计算码载偏离度,并利用...针对单频地基增强系统(Ground Based Augmentation System,GBAS)中电离层异常时Hatch滤波器平滑精度降低问题,系统分析了电离层延时对Hatch滤波器平滑精度的影响,提出一种改进自适应Hatch滤波算法。根据卫星信号计算码载偏离度,并利用二阶线性时不变低通滤波器抑制码载偏离度高频信号,以实现电离层异常实时检测;建立平滑后伪距误差均方根与电离层延时变化率、伪距测量噪声标准差以及平滑时间三者之间的函数模型,并由此确定出Hatch滤波器最优平滑时间。利用GBAS原理样机进行验证实验,结果表明:自适应Hatch滤波算法能够根据卫星信号电离层延时变化率确定滤波器最优平滑时间,且当电离层异常时,自适应Hatch滤波器机载位置误差最大由1.15 m减小为0.43 m,从而验证了所提算法的有效性。展开更多
Flexible-shelled eggs of the lizards Phrynocephalus przewalskii and P. versicolor were incubated under different thermal and hydric conditions to elicit the effects of incubation environment on hatching success, embry...Flexible-shelled eggs of the lizards Phrynocephalus przewalskii and P. versicolor were incubated under different thermal and hydric conditions to elicit the effects of incubation environment on hatching success, embryonic development and duration as well as hatchling phenotypes. Embryogenesis of the two species was not sensitive to changes in the hydric environment except P. przewalskii incubated in 30°C group. Temperature significantly altered the duration of embryogenesis, with cooler temperatures leading to a longer incubation period. Hatching success was greater at 26 and 30°C than at 34°C. The hatchlings incubated at 26 and 30°C had longer snout-vent length, larger body mass, and better locomotor performance than those incubated at 34°C. Compared to P. przewalskii, P. versicolor had a shorter incubation period and yielded smaller hatchlings, which then had a higher survival rate in cooler and drier habitats. We conclude that an incubation temperature of 30°C would produce the best balance among developmental rate, hatching success, and post-hatching performance. We speculate that the upper temperature limit for incubation of P. versicolor eggs may be slightly higher than 34°C.展开更多
In order to investigate the effect of temperature on hatching result of fertilized peacock eggs, they were hatched under conditions of varying temperature and constant temperature respectively. The result shows that t...In order to investigate the effect of temperature on hatching result of fertilized peacock eggs, they were hatched under conditions of varying temperature and constant temperature respectively. The result shows that the hatching rate in the varying temperature treatment group （Group Ⅰ） is higher than that in the constant temperature treatment group （Group Ⅱ）. It suggests that the varying temperature treatment （high temperature in the early period, medium temperature in the middle period, slightly lower temperature in the late period, and slightly higher temperature in the hulling period） is in line with the optimum temperature variation in the hatching of fertilized peacock eggs, contributing the hatching of fertilized peacock eggs.展开更多
Background: Accurately assigning hatchlings to the eggs from which they hatched is a prerequisite to understanding how the composition and environment of eggs affect the growth and survival of nestlings. Correctly ass...Background: Accurately assigning hatchlings to the eggs from which they hatched is a prerequisite to understanding how the composition and environment of eggs affect the growth and survival of nestlings. Correctly assigning hatchlings to their eggs can be a challenging endeavor, however, because multiple eggs within the same clutch can hatch at essentially the same time. Egg and hatchling mass are highly correlated in most bird species, and thus assigning eggs to hatchlings using their relative mass(e.g., matching the heaviest hatchling to the heaviest candidate egg) could prove extremely useful.Methods: To assess its potential utility, I applied relative mass assignment(RMA) retrospectively to a dataset of 133 Common Grackle(Quiscalus quiscula) nests in which all egg-hatchling dyads were determined unequivocally.Results: I found that RMA correctly assigned approximately 90% of hatchlings to their eggs when 2-4 hatchlings were present between checks. The number of nests in which hatchlings could not be assigned to their egg, however, increased monotonically from 13 to 46 to 78% for nests containing 2, 3, and 4 hatchlings, respectively, due to the greater likelihood that the mass of hatchlings or their candidate eggs was identical.Conclusions: Although RMA correctly identified the vast majority of egg-hatchling dyads, researchers should use this method with caution, because it will always inflate positive egg-size effects and thus could potentially result in erroneously reporting significant effects.展开更多
文摘Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncertain.Beyond timing,procedural choices in PGT-A must balance diagnostic yield against potential harm from additional handling(e.g.,repeat TE biopsy or cryopreservation steps),as underscored by a recent systematic review and meta-analysis[1].
基金funded by the National Natural Science Foundation of China(NSFC 31071918)
文摘Flexible-shelled eggs of the lizards Phrynocephalus przewalskii and P. versicolor were incubated under different thermal and hydric conditions to elicit the effects of incubation environment on hatching success, embryonic development and duration as well as hatchling phenotypes. Embryogenesis of the two species was not sensitive to changes in the hydric environment except P. przewalskii incubated in 30°C group. Temperature significantly altered the duration of embryogenesis, with cooler temperatures leading to a longer incubation period. Hatching success was greater at 26 and 30°C than at 34°C. The hatchlings incubated at 26 and 30°C had longer snout-vent length, larger body mass, and better locomotor performance than those incubated at 34°C. Compared to P. przewalskii, P. versicolor had a shorter incubation period and yielded smaller hatchlings, which then had a higher survival rate in cooler and drier habitats. We conclude that an incubation temperature of 30°C would produce the best balance among developmental rate, hatching success, and post-hatching performance. We speculate that the upper temperature limit for incubation of P. versicolor eggs may be slightly higher than 34°C.
基金Supported by Scientific and Technological Development General Program of Beijing Municipal Education Commission(KM201412448004)~~
文摘In order to investigate the effect of temperature on hatching result of fertilized peacock eggs, they were hatched under conditions of varying temperature and constant temperature respectively. The result shows that the hatching rate in the varying temperature treatment group （Group Ⅰ） is higher than that in the constant temperature treatment group （Group Ⅱ）. It suggests that the varying temperature treatment （high temperature in the early period, medium temperature in the middle period, slightly lower temperature in the late period, and slightly higher temperature in the hulling period） is in line with the optimum temperature variation in the hatching of fertilized peacock eggs, contributing the hatching of fertilized peacock eggs.
基金Funding was provided by the University of Illinois,Program in Ecology,Evolution and Conservationthe American Ornithologists’Union Research Award.L.S.Johnson provided useful comments on an earlier version of the manuscriptsupported by an NSF International Fellowship OISE-1159178
文摘Background: Accurately assigning hatchlings to the eggs from which they hatched is a prerequisite to understanding how the composition and environment of eggs affect the growth and survival of nestlings. Correctly assigning hatchlings to their eggs can be a challenging endeavor, however, because multiple eggs within the same clutch can hatch at essentially the same time. Egg and hatchling mass are highly correlated in most bird species, and thus assigning eggs to hatchlings using their relative mass(e.g., matching the heaviest hatchling to the heaviest candidate egg) could prove extremely useful.Methods: To assess its potential utility, I applied relative mass assignment(RMA) retrospectively to a dataset of 133 Common Grackle(Quiscalus quiscula) nests in which all egg-hatchling dyads were determined unequivocally.Results: I found that RMA correctly assigned approximately 90% of hatchlings to their eggs when 2-4 hatchlings were present between checks. The number of nests in which hatchlings could not be assigned to their egg, however, increased monotonically from 13 to 46 to 78% for nests containing 2, 3, and 4 hatchlings, respectively, due to the greater likelihood that the mass of hatchlings or their candidate eggs was identical.Conclusions: Although RMA correctly identified the vast majority of egg-hatchling dyads, researchers should use this method with caution, because it will always inflate positive egg-size effects and thus could potentially result in erroneously reporting significant effects.
