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441.
In humans, as in nonhuman primates, the digits of the hands are similar in length during early fetal development. Subsequently, differentiation leads to a patter of unequal finger lengths, described by George as the finger-length pattern. Recent work by Manning and colleagues suggested that digit length patterns are due to early influences of sex hormones. Most importantly for psychology, such patterns might also relate to cognitive activities that are influenced by early organizing actions of sex hormones. The exciting possibility of having an easily measurable indicator of early action of sex hormones that relates to behavior led us to examine the universality of digit length patterns. With samples from Brazil, Canada, India, Turkey, and Korea, we showed that patterns of distal extent of finger tips are similar across different human populations. Consistent sex differences were found across the samples, showing that the index finger in males extends less far distally relative to the middle finger than is the case for females and that the difference in distal extent between index and ring fingers, relative to the middle finger, is smaller in females than in males. 相似文献
442.
Cassandra Nan Jan Piek Claire Warner Diane Mellers Ruth Elisabeth Krone Timothy Barrett Maurice P. Zeegers 《Infant behavior & development》2013
Background
Low birth weight and low 5-min Apgar scores have been associated with developmental delay, while older maternal age is a protective factor. Little is known about trajectories and predictors of developmental skills in infant twins, who are generally born with lower birth weights, lower Apgar scores and to older mothers.Methods
Developmental skills were assessed at 3, 6, 9, 12, 18 and 24 months using the Ages and Stages Questionnaires in 152 twins from the Birmingham Registry for Twin and Heritability Studies. Multilevel spline and linear regression models (adjusted for gestational age, gender, maternal age) were used to estimate developmental trajectories and the associations between birth weight, maternal age and Apgar scores on developmental skills.Results
Twins performed worse than singletons on communication, gross motor, fine motor, problem solving and personal-social skills (p < 0.001). Twins caught up around 6 months (score within −1 standard deviation of norm), except on gross motor skills, which did not catch up until after the age of 12 months. A one-year increase in maternal age was significantly associated with decreases in gross motor and personal–social z-scores of up to −0.09, whereas one unit increases in Apgar score increased z-scores up to 0.90 (p < 0.01).Conclusions
Healthy twins should be considered at a higher risk for developmental delay. Whether these results are comparable to preterm singletons, or whether there are twin-specific issues involved, should be further investigated in a study that uses a matched singleton control group. 相似文献443.
Jidong Kang Raja K. Mishra David S. Wilkinson Odd S. Hopperstad 《Philosophical Magazine Letters》2013,93(11):647-655
Experimental measurements of stress drops and band strains in type-B Portevin–Le Chatelier (PLC) bands were carried out for 5xxx series Al–Mg sheets with Mg content between 1.8 and 4.5?wt%. While the stress drops increase with global strain, the band strain values in all the samples follow a common linear relationship with global strain. The results indicate that the type-B PLC band strain is independent of solute content at given strain rate. 相似文献
444.
Second language (L2) instruction programs often ask learners to repeat aloud words spoken by a native speaker. However, recent research on retrieval practice has suggested that imitating native pronunciation might be less effective than drill instruction, wherein the learner is required to produce the L2 words from memory (and given feedback). We contrasted the effectiveness of imitation and retrieval practice drills on learning L2 spoken vocabulary. Learners viewed pictures of objects and heard their names; in the imitation condition, they heard and then repeated aloud each name, whereas in the retrieval practice condition, they tried to produce the name before hearing it. On a final test administered either immediately after training (Exp. 1) or after a 2-day delay (Exp. 2), retrieval practice produced better comprehension of the L2 words, better ability to produce the L2 words, and no loss of pronunciation quality. 相似文献
445.
Nan Wu 《Journal of cognition and development》2013,14(2):302-313
Individual social differences have been addressed in recent studies, and the oxytocin receptor gene (OXTR) is the major candidate in explaining various social phenotypes. To study the association between a well-known haplotype (rs53576) of OXTR and children's prosocial behavior and its relationship with theory of mind (ToM) ability, 87 children (aged 3 to 5 years old) participated in 3 prosocial tasks and ToM performance experiments. Participants who were homozygous for the G allele (GG) exhibited more prosocial behaviors than did those with 1 or 2 copies of the A allele (AA), and GG carriers also displayed better ToM ability than did AA individuals. Further tests showed differences between genotypes in helping and comforting, albeit not in sharing. The results demonstrated that OXTR rs53576 was related to individual differences in ToM and was associated with prosocial behavior. 相似文献
446.
药物成瘾会导致相关神经环路的结构和功能长期改变.大量新的研究证据表明,在DNA序列不变的情况下,药物成瘾可通过影响不同亚型DNA甲基转移酶(DNMTs)的表达,使脑内多个相关核团发生DNA甲基化以及基因表达的改变,进而导致神经元功能的可塑性变化.因此,DNA甲基化被视作导致成瘾行为长期存在的可能机制之一.结合近几年来的重要发现,本文将重点讨论相关脑区的DNA甲基化在成瘾行为发生发展过程中的作用,以及成瘾药物影响DNA甲基化水平的可能机制,并试图提出可深入的研究展望. 相似文献
447.
448.
本文主要研究Erdos-Moser定理。在简单介绍了反推数学的一些基础知识后,首先研究了Erdos-Moser定理的证明论强度:存在一个可计算的二元二染色函数使得任何无穷∑20集合都不是该函数的传递集,同时存在一个可计算的二元二染色函数使得每一个该函数的无穷传递集都是超免疫的。其次,我们进一步考虑了稳定性Erdos—Moser定理,证明了在二阶算术子系统RCA0下稳定性Erdos-Moser定理是不可证的并且对每一个可计算的稳定性二色二阶函数,我们构造了一个Ф’可计算的无穷传递集。 相似文献
449.
450.
C. Brian Harvey Zhu Manshu Kang Ching Biao Zhang FU Jue 《The Journal of genetic psychology》2013,174(4):457-464
Four-, five-, and six-year-old Chinese and Canadian boys and girls were presented a series of 11 graphic models and were asked to draw them. Supporting Piaget's theory, the data indicated that drawing performance on the topological dimension was better than the performance on the Euclidean dimension, and that there were neither gender nor cultural differences in performance. The research offers strong support for a main effect of biological or maturational factors as the foundation for the developmental influences in the acquisition of spatial conceptions. 相似文献