Nucleation of recrystallization in fine-grained materials: an extension of the Bailey–Hirsch criterion

Abstract

A new criterion for nucleation in the case of dynamic recrystallization is proposed in order to include the contribution of the grain boundary energy stored in the microstructure in the energy balance. Due to the nucleation events, the total surface area of pre-existing grain boundaries decreases, leading to a nucleus size smaller than expected by conventional nucleation criteria. The new model provides a better prediction of the nucleus size during recrystallization of pure copper compared with the conventional nucleation criterion.     

Personality determinants of the commitment to the profession of art

The model of commitment presented in the present report postulates personality to be the crucial element in the development and maintenance of commitment to the profession of art. The objectives of the research reported here were to (a) demonstrate the typicality of the artist personality and (b) identify the traits which characterize committed and uncommitted artists. Three groups of artists were compared: mature established artists described as committed over a lifetime, committed art students, and uncommitted art students. The instrument used to evaluate personality was the Adjective Check List (ACL; Gough 8c Heilbrun, 1983). Both committed and uncommitted artists presented a typical personality structure; but in contrast to the committed, the uncommitted were characterized by low self‐esteem, a negative self‐image, impaired motivation, low staying power, and an inability to find a clear direction. Both art students and mature artists agreed about the order of importance of 11 factors considered to be determinants of committment. They both placed particular emphasis on autonomy, possibility to experiment, ease of inspiration, and early identification with the profession.     

Age-Correlated Incremental Consideration of Velocity Information in Relative Time-to-Arrival Judgments

One hundred fifty-one children and 43 adults judged which of 2 cartoon birds would be the first to arrive at a common finish line. Objects moved unidirectionally along parallel trajectories, either at the same or different speeds, and disappeared at different distances from the goal. Overall, 9–10-year-old children performed as well as adults, but 4–5- and 6–8-year-olds erred significantly more often. On trials for which distance to goal at disappearance was a valid cue, 4–5-year-olds scored 80% correct, and no differences were seen between 6–10-year-olds and adults. On the opposite type of trials, where the trailing bird would win the race, only adults retained their level of performance, and all age groups differed markedly. Findings suggest a gradual developmental transition from a distance-based to a time-based understanding of the task.     

Living in a multicultural world: Intergroup ideologies and the societal context of intergroup relations

In a relatively short time span, issues of ethnic, cultural, and religious diversity have become central topics of discussion in various nations. As a result, the role of broad ideologies that frame and structure relations between groups has received increasing attention by social psychologists. Of particular concern has been the role of these intergroup ideologies in promoting intergroup harmony and reducing prejudice. In this article, we appraise the evidence related to three main intergroup ideologies, assimilation, colourblindness, and multiculturalism. We argue that research in this area has paid insufficient attention to the social and political context. Intergroup ideologies have been studied and conceptualised as being located solely within individual minds. We suggest that the potentially vital aspect of these ideologies is that they are sometimes widely shared by members of a social group. Integrating sociological and political analyses, we discuss the fact that intergroup ideologies are institutionalised as policies and that, as such, they often vary across countries and across time. We present a series of studies to illustrate the theoretical implications of studying the shared nature of these intergroup ideologies, providing insights into the question of when and why national policies can shape individuals’ intergroup attitudes and beliefs and improve intergroup relations.     

Why We Walk the Way We Do

By using inverse dynamics and forceplate recordings, this study established the principle of oscillating systems and the influence of gravity and body parameters on the programming of the gait parameters, step frequency and length. Calculation of the ratio of the amplitude of the center of mass (CM) and the center of foot pressure (CP) oscillations yielded an equation and established a biomechanical constant, the natural body frequency (NBF). NBF appears to be an absolute invariant parameter, specific to human standing posture and gait in terrestrial gravity, which influences the relative positions of CM and CP and whose value separates the frequency bands of standing posture from those for gait. This equation was tested by using the experimental paradigm of stepping in place and then used in calculating the magnitude of CM oscillations during gait. The biomechanical analysis of the experimental observations allows one to establish the relationships between body parameters and gravity and the central programming of locomotor parameters.     

Postural Requirements and Progression Velocity in Young Walkers

This article describes developmental changes in gait velocity and relates these changes to gait parameters that index postural stability (step width and lateral acceleration) and two components of velocity (cadence and step length).

Five children were observed longitudinally over a 2-year period after onset of independent walking. Their range of speed increased threefold in the first 6 months of independent walking and then remained constant. In contrast, step width decreased approximately twofold. Whereas in adults, cadence and step length contribute approximately equally to speed, when infants first begin to walk independently, increase in velocity is due mostly to increased step length. After 5 months of independent walking, the pattern reverses, and increase in velocity is due primarly to increased cadence. The pattern remains constant over the next 18 months. From a developmental point of view, the data lead us to interpret early walking (the first 5 months) as a process of integration of postural constraints into the dynamic necessities of gait movement. A second phase, beginning after 4 to 5 months of independent walking, is considered to be a tuning phase characterized by a more precise adjustment of the gait parameters.     

Coordination Dynamics of the Bipedal Galloping Pattern

A motion equation in relative phase was developed that incorporates the spatial-temporal pattern of the bipedal gallop along with the more commonplace patterns of the bipedal jump and walk-run. In 3 experiments, human participants (N = 6 per experiment) simulated the bipedal gait patterns through the rhythmic motions of hand-held pendulums. Predictions of the motion equation for coordination equilibria and their respective degrees of stability were confirmed. In particular, the gallop pattern was less stable than the fundamental in-phase and antiphase patterns but changed in qualitatively similar ways to those gaits as a function of limb asymmetry and movement frequency. The relation between the modeled coordination dynamics and the kinematic characteristics of real bipedal galloping is discussed.     

Longitudinal predictors of changes in the morningness–eveningness personality among Norwegian nurses

The aim of this cohort study was to investigate factors that might cause a shift in morningness–eveningness personality. A large sample of Norwegian nurses (n = 1144) participated in a longitudinal survey study about life- and work factors, symptoms of anxiety and depression, and habits such as smoking, caffeine- and alcohol consumption. A hierarchical regression analysis was employed to determine if these variables had predictive value concerning changes in morningness assessed with the Diurnal Type Scale (DTS) over a 24-month interval. The results showed that percentage of full time equivalent, having children (or having children move in), and female gender all predicted higher scores on the morningness scale over time. Also, factors such as number of night shifts during the past two years, whether the subject had started smoking and higher alcohol consumption by the subject all predicted lower scores on the morningness scale over time.     

Entrevista con Jean-Paul Bronckart

RESUMEN

Bronckart comienza revisando su trayectoria científica y explicando cuáles son sus dos enfoques básicos: el análisis del contexto o de situaciones y el análisis del lenguaje en función de sus operaciones subyacentes definidas en el marco de las teorías de la enunciación. Seguidamente justifica su renuncia a posiciones estructuralistas porque no tienen en cuenta el problema de las relaciones funcionales ni prestan atención al contexto. El autor relaciona las operaciones psicológicas con universales funcionales diferenciándolos de los estructurales de Chomsky y del enfoque de Searle, defendiendo su interés por la lingüística comparativa. Seguidamente aborda el tema de análisis de textos en ambientes escolares, sugiriendo que hay que sensibilizar a los educadores sobre el hecho de que constantemente estamos en situaciones de comunicación que van cambiando y crear instrumentos para que puedan analizar su propia práctica. Con relación al aspecto cognitivo del lenguaje, enfatiza la proliferación excesiva de los enfoques representativos y seguidamente desarrolla qué entiende por especificidad de la naturaleza del lenguaje y de su carácter comunicativo. Esta entrevista aborda, además, cuestiones tales como el fenómeno presuposicional, las aportaciones de Vygotsky o las experiencias de enseñar lenguaje a chimpancés, y finaliza planteando algunos aspectos de la teoría de Culioli.