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161.
The microstructure and crystallization behaviour of melt-spun Al88Ni9Ce2Fe1 amorphous alloy and nanophase composites have been studied by means of X-ray diffraction, transmission electron microscopy and scanning and isothermal calorimetry. The diffraction patterns from Al88Ni9Ce2Fe1 amorphous alloys are diffuse, indicating a basically amorphous structure but contain two rings presumed to be associated with quenched-in nuclei. In the cases of Al88Ni9Ce2Fe1 nanophase composites, nanoscale precipitated particles are homogeneously dispersed in an amorphous matrix, and the crystallite diameter and volume fraction are sensitive to quenching conditions. During thermal crystallization, a two-step phase transformation occurs in the amorphous alloy and nanocomposites, which is characterized by a diffusion-controlled precipitation of nanoscale Al particles and the growth of a Al3(Ni, Fe) nanophase prior to a Al11Ce3 nanophase. This study gives insight into structure-control for obtaining nanophases dispersed in an amorphous matrix by rapid quenching. 相似文献
162.
It is shown that initially sharp interface in AB diffusion couple, above the ordering temperature, can shift with anomalous kinetics, i.e. deviations from the parabolic growth kinetics are possible. The initial slopes of the shift versus time functions can be even unity for large diffusion asymmetry (the ratio of diffusion coefficients of the parent materials in orders of magnitude) and gradually decrease to 0.5 at larger distances (longer times). This is in accordance with earlier results obtained in phase separating systems. It is shown that from the results of simulations the crossover thickness, X*, between the linear and parabolic regimes can also be calculated, and the applicability of the linear–parabolic law is confirmed. Furthermore, it is illustrated that the crossover thickness depends exponentially on the diffusion asymmetry parameter, with the exponent close to the value obtained from analytical estimations. 相似文献
163.
José Z. Abramson Victoria Hernández-Lloreda Josep Call Fernando Colmenares 《Animal cognition》2013,16(1):11-22
Comparative experimental studies of imitative learning have focused mainly on primates and birds. However, cetaceans are promising candidates to display imitative learning as they have evolved in socioecological settings that have selected for large brains, complex sociality, and coordinated predatory tactics. Here we tested imitative learning in killer whales, Orcinus orca. We used a ‘do-as-other-does’ paradigm in which 3 subjects witnessed a conspecific demonstrator’s performance that included 15 familiar and 4 novel behaviours. The three subjects (1) learned the copy command signal ‘Do that’ very quickly, that is, 20 trials on average; (2) copied 100 % of the demonstrator’s familiar and novel actions; (3) achieved full matches in the first attempt for 8–13 familiar behaviours (out of 15) and for the 2 novel behaviours (out of 2) in one subject; and (4) took no longer than 8 trials to accurately copy any familiar behaviour, and no longer than 16 trials to copy any novel behaviour. This study provides experimental evidence for body imitation, including production imitation, in killer whales that is comparable to that observed in dolphins tested under similar conditions. These findings suggest that imitative learning may underpin some of the group-specific traditions reported in killer whales in the field. 相似文献
164.
Limor Rosenberg Orit Bart Navah Z. Ratzon Tal Jarus 《Journal of child and family studies》2013,22(5):658-671
Enhancing participation in age-related activities is a key goal in the education and rehabilitation of children with diverse disabilities. The aim of this study was to explore a multidimensional and ecological model of participation for young children. Seventy eight children with mild developmental disabilities (MDD, such as motor and visual-motor difficulties), and 110 children without disabilities, between the ages 4 and 6 years old, participated in the study together with their parents. Data were collected using standardized assessments for child capacities and newly developed questionnaires for child participation and for human and physical environmental factors. Associations were found between personal and environmental factors and the participation dimensions amongst young children, thus supporting the validity of the proposed model of participation. Moreover, the study results outline different pathways for the participation of children with and without MDD. Child factors (e.g. process skills) were found to be crucial predictors of participation particularly for children with MDD, whereas human environmental factor (e.g. maternal self-efficacy beliefs) was associated with higher participation scores especially for children without disabilities. These findings may facilitate the development of effective intervention programs which focus on environmental factors as well as on child factors. 相似文献
165.
Karen Z. H. Li Mervin Blair Virginia S. M. Chow 《Neuropsychology, development, and cognition. Section B, Aging, neuropsychology and cognition》2013,20(3):270-295
ABSTRACT Two experiments were conducted to examine possible sources of age-related decline in sequential performance: age differences in sequence representation, retrieval of sequence elements, and efficiency of inhibitory processes. Healthy young and older participants learned a sequence of eight animal drawings in fixed order, then monitored for these targets within trials of mis-ordered stimuli, responding only when targets were shown in the correct order. Responses were slower for odd numbered targets, suggesting that participants spontaneously organized the sequence in two-element chunks. Perseverations (responses to previously relevant targets) served as an index of inhibitory inefficiency. Efficiency of chunk retrieval and self-inhibition were lower for older than for younger adults. Increasing environmental support in Experiment 2 through overt articulation of current chunk elements showed a pattern of results similar to Experiment 1, with particular benefit for older adults. The findings suggest an underlying susceptibility to interference in old age. 相似文献
166.
Previous research has demonstrated electroencephalogram (EEG) changes in response to low-odor concentrations, resulting in near-chance detection. Such findings have been taken as evidence for olfaction without awareness. We replicated and extended previous work by examining EEG responses to water-water control, 0.0001, 0. 001, 0.01, and 1 ppm isoamyl acetate (IAA) in water paired with water only. Detection was above chance (>50%) for.001 and above, and alpha decreased only to those concentrations, suggesting that EEG changes corresponded to IAA awareness. However, when correct trial EEGs were compared to incorrect trial EEGs during.001 ppm, right posterior/central alpha decreased during incorrect trials and alpha decreased more globally (including frontal sites) during correct trials. These data may not reflect awareness or unawareness per se. Instead, results are discussed regarding activation of perceptual systems in the posterior region during incorrect trials and the activation of frontal action systems during a subset of correct trials. 相似文献
167.
Han Z. Li 《European journal of social psychology》2002,32(1):93-104
Founded upon the theories of Independent–Interdependent Self‐Construal and I–C, the main goal of this study was to test, via an adapted IOS Scale, whether Anglo‐Canadians were more independent than Mainland Chinese in construing their relationship with family members and friends. Strong cultural differences were found in self–family connectedness, but not in self–friends connectedness. Chinese were closer to their family members than Canadians, but Canadians were as close to their friends as Chinese. In both samples, gender difference was found in self–friends connectedness, but not in self–family connectedness. In the Canadian sample, females were closer to their friends than males, while in the Chinese sample, males were closer to their friends than females. In conclusion, this study contributes to the field in three ways. First, the finding that Canadians are as connected as Chinese to their close friends unprecedentedly contests one fundamental assumption of the theories of independent‐interdependent self‐construal (Markus & Kitayama, 1991 ) and I–C (Hofstede, 1980 ; Triandis, Bontempo, Villareal, Asia & Lucca, 1988 ) that individualists (e.g. Anglo‐Canadians) are more independent than collectivists (e.g. Chinese) on all dimensions of human relations. Second, the proposition (Cross & Madson, 1997 ) that Western males and females differ in the same way individualists and collectivists differ in their self‐construal is not supported. Finally, the adaptation of the IOS Scale proposes a refreshing direction in cross‐cultural research. Graphic representations may be less susceptible to cross‐cultural misconstrual than verbal statements since the former involves little or no translation from one language to another. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
168.
Sherry A. Span Mitchell Earleywine Thomas Z. Strybel 《Journal of psychopathology and behavioral assessment》2002,24(2):129-136
Three separate models have been proposed to describe the factor structure of attention deficit hyperactivity disorder (ADHD) in the past 20 years. The Diagnostic and Statistical Manual of Mental Disorders-III (DSM-III, 1980) proposed 3 separate factors of inattention, hyperactivity, and impulsivity. The DSM-III-R (1987) proposed a single factor. The DSM-IV (1994) described the disorder as having 2 factors: hyperactivity/impulsivity and inattention. The following 2 studies employed confirmatory factor analysis to compare each of these models and 3 alternative models. University students completed questionnaires that assessed each of the 18 symptoms listed in the DSM-IV for ADHD. The 3-factor model fit the data significantly better than each of the other models in both studies. These findings suggest that a 3-factor model of inattention, hyperactivity, and impulsivity describes adult ADHD symptoms better than current alternatives. 相似文献
169.
David Z. Hambrick 《Applied cognitive psychology》2002,16(2):234-235
170.