Domestic pigeons (Columba livia) discriminate between photographs of individual pigeons

In two experiments, we examined the discrimination of photographs of individual pigeons by pigeons, using go/no-go discrimination procedures. In Experiments 1A and 1B, the pigeons were trained to discriminate 4 photographs of one pigeon from those of a number of pigeons. The subjects learned the discrimination, but their discriminative behavior did not transfer to new photographs taken from novel perspectives. When the pigeons were trained to discriminate between 20 photographs of five pigeons taken from four perspectives as the S+ and 20 photographs of five different pigeons as the S-, the subjects learned the discrimination, and this discriminative behavior partially transferred to new photographs taken from novel perspectives (Experiments 2A-2C). The results suggest that pigeons are able to discriminate among conspecific individuals, using stationary visual cues. This strengthens the assumption in evolutionary theory that animals can discriminate among individuals and encourages further investigation as to how this ability is used in various behaviors of animals.     

Role of the Embodied Cognition Process in Perspective-Taking Ability During Childhood

This study examined developmental changes in Level-2 visual perspective taking (VPT2) in 90 children aged 4–12 years and tested the role of their ability to mentally simulate changes to their bodily locations (self-motion imagery; SMI). Performance of a mental toy rotation task and a self-motion (SM) task (changing location of children) was superior to that of VPT2 and SMI tasks. Task performance of SMI was better than that of VPT2 before 10;0 (years;months). Furthermore, egocentric responses in VPT2 and SMI tasks were significantly more frequent than those in the mental rotation and SM tasks before 10;3. These findings suggest the involvement of embodied cognitive processes in perspective taking and the advantage of utilizing bodily information by age 10.     

关于南朝贵族地缘性的考察——以对侨郡县的探讨为中心

在对南朝贵族制的研究中,南北人的地缘性,特别是关于北方贵族的地缘性是一个重要的问题.依据近年南京发掘的六朝墓和出土的墓志铭等考古成果,可以克服研究史料的限制,获得有关侨郡县与士族尤其是与北方士族之籍贯、侨寓地、墓地关系的更加充分的认识.如侨置的琅邪郡临沂县以及兰陵郡兰陵县对于琅邪大姓王氏、颜氏以及兰陵萧氏来说,是名实相符的完全的籍贯;而其他士族与原籍侨郡县之间,则没有这样名实相符的关系,不具有实际疆域的侨郡县对于他们来说,充其量不过是登注户籍的地方.据此,被侨置的原籍是名义上的还是现实的,与作为士族的等级上下有着深刻的关系.     

Effects of plyometric training on maximal-intensity exercise and endurance in male and female soccer players

In a randomised controlled trial design, effects of 6 weeks of plyometric training on maximal-intensity exercise and endurance performance were compared in male and female soccer players. Young (age 21.1 ± 2.7 years) players with similar training load and competitive background were assigned to training (women, n = 19; men, n = 21) and control (women, n = 19; men, n = 21) groups. Players were evaluated for lower- and upper-body maximal-intensity exercise, 30 m sprint, change of direction speed and endurance performance before and after 6 weeks of training. After intervention, the control groups did not change, whereas both training groups improved jumps (effect size (ES) = 0.35–1.76), throwing (ES = 0.62–0.78), sprint (ES = 0.86–1.44), change of direction speed (ES = 0.46–0.85) and endurance performance (ES = 0.42–0.62). There were no differences in performance improvements between the plyometric training groups. Both plyometric groups improved more in all performance tests than the controls. The results suggest that adaptations to plyometric training do not differ between men and women.     

The relationship between strength asymmetries and jumping performance in professional volleyball players

Knee peak torque (PT) is associated to jump performance in volleyball players. It is not clear whether muscle strength imbalances of the knee joint can influence jump performance. The purpose of study was to analyse the association between PT and knee muscular imbalances with jump performance in professional volleyball players. Eleven elite male volleyball players (90.3 ± 9.7 kg body mass and 1.94 ± 0.06 m height) were evaluated in an isokinetic dynamometer at speeds of 60, 180 and 300 deg/s. Muscle strength imbalances were obtained through calculation of contralateral deficit between limbs and the conventional ratio (hamstrings/quadriceps). Countermovement jump (CMJ) was performed on a force plate to calculate mechanical power and height. Association was found between knee extensor PT at 180 deg/s with CMJ power (r = 0.610, p = 0.046). Conventional ratio at 300 deg/s showed negative association with CMJ (r = ?0.656, p = 0.029). The optimal ratio between knee extensors PT in relation to the flexors PT is associated with the greater mechanical power in CMJ. Contralateral deficit does not seem to be associated with the CMJ performance. Considering the knee extensor PT is associated with CMJ power, our findings suggest that strength-based training in volleyball athletes should not omit the conventional muscle ratio.     

Heart rate recovery after aerobic and anaerobic tests: is there an influence of anaerobic speed reserve?

The present study assessed if differences in the metabolic profile, inferred from the anaerobic speed reserve (ASR), would influence the dynamics of heart rate recovery (HRR) after two modes of exercise. Thirty-nine physical education students (14 females and 25 males) volunteered for this study. Participants carried out three separate testing sessions to assess maximal sprinting speed (MSS, 1st session), repeated sprint ability (RSA, 2nd session) and maximal aerobic speed (MAS) using the Université of Montreal Track Test (UMTT, 3rd session). ASR was defined as the difference between MSS and MAS. Heart rate was continuously registered throughout the tests and during the 5-min post-test recovery. To evaluate the influence of ASR on post-exercise, HRR comparisons between ASR-based groups [high ASR vs. low ASR] and sex groups (males vs. females) were performed. Significant differences (P < 0.05) were found between high ASR and low ASR groups of the same sex for indices of relative HRR after the RSA and UMTT. In addition, after the RSA test, males from the high ASR group had a significantly slower HRR kinetics compared with the males of the low ASR (P < 0.05) and the females of high ASR (P < 0.05); whereas females of the high ASR groups had a faster HRR kinetics compared with the females of low ASR group (P < 0.05). Our results showed that in males, post-exercise HRR could be related to the ASR, whereas in females, the influence of ASR is less clear.     

Differences in soccer kicking type identified using principal component analysis

Soccer kicks are characterized by segmental and joint rotations in multiple planes, where large discrepancies between two- and three-dimensional analyses for angular measurements of soccer kicks exist. The aim of this study was to clarify the differences in motions of the lower limbs and the pelvis required to achieve a shot without rotations as compared with an instep kick. Kinematic parameters obtained from non-rotational shots and instep kicks were analyzed using principal component analysis (PCA). The results clearly demonstrated that the PCA identified the differences in the instep kick and the non-rotational shot relative to the kinematic motions of the lower limbs and the pelvis. These findings suggest that the key issue for executing the NR shot is achieving a straight-line foot trajectory in the impact phase.