Analysis of the relation between structure and the superconducting transition in YBa2 Cu3 O∼7

Abstract

It is shown that in the high-T_c YBa₂ Cu₃ O_～7 superconductor the critical temperature is a function of the orthorhombic distortion (b–a)/a of the unit cell. From the extrapolation of the (b - a)/a ratio against T_c , a maximum critical temperature of 66 K for the tetragonal phase of YBa₂ Cu₃ O_～7 was predicted. From the correlation between the transition width δT_c and the orthorhombic distortion there was deduced an upper limit for T_c , in the orthorhombic phase of YBa₂ Cu₃ O_～7 of 94·5K.     

Determination of glass-forming ability of Ge1− x Sn x Se2.5 (0 ≤ x ≤ 0.5) alloys using differential scanning calorimetry

The glass-forming ability of Ge_{1? x} Sn _x Se_2.5 (0 ≤ x ≤ 0.5) alloys was studied using differential scanning calorimetry. Samples were scanned at different heating rates under non-isothermal conditions. Various simple quantitative methods were employed to assess the stability of the glassy materials in the above-mentioned system. All of these methods are based on characteristic temperatures, such as the glass-transition temperature, T _g, the onset-of-crystallization temperature, T _c, and the peak crystallization temperature, T _p. A crystallization rate factor, K, has also been used as a measure of the thermal stability of the glasses. It was found that Ge_0.7Sn_0.3Se_2.5 was the least stable among all the samples.     

Phenomenological model of variant change during magnetization of martensite

The present study deals with the straining of ferromagnetic martensite in a magnetizing field. A phenomenological model of the movement of the interface between martensitic variants is developed for calculation of the strength of the magnetic field required for a variant change. The effect of uniaxial stress on interface movement is also examined. The results are applied to the martensite phases of NiMnGa and FePd ferromagnetic shape-memory alloys.     

Interpersonal perception in cross-group interactions: Challenges and potential solutions

This review provides a framework for theorising about the processes that give rise to interpersonal perception during encounters between two individuals who belong to different groups. Consistent with a dyadic approach, interpersonal perception is considered a function of the unique and combined effects of the perceptions and behaviours of both partners involved in the interaction. A model is presented in which negative expectancies give rise to feelings of anxiety and behavioural displays of anxiety, both of which in turn influence interpersonal judgements. Factors that vary at the level of the perceiver, target, and the interaction are examined as moderators of interpersonal perception. Lastly, given that the study of interpersonal perception within cross-group dyadic encounters is relatively new, several strategies that show promise for improving interpersonal perception are discussed. Turning towards the future this article concludes by discussing how research and theory outside the domain of intergroup relations can be used to develop innovative methods for improving perception processes.     

Parenting Attitudes and the Self-Esteem of Young Children

Second-, third-, fifth-, and sixth-grade children evaluated relationship qualities of a self-nominated friend and a self-nominated very best friend over a 6-month school year period. Results demonstrated that 76% of the friend relationships and 50% of the very best friend relationships were maintained over the course of the study. Children in maintained friendships evaluated their relationships more positively and also reported having larger friendship networks in general compared with children whose friendships did not endure over time. Thus those with unstable relationships are having difficulty initiating new friendships as well. For very best friends, positive relationship qualities (e.g., caring) did not change over time for children in maintained relationships, while positive relationship qualities decreased over time for children in nonmaintained relationships. Further, no differences emerged between children in maintained and nonmaintained very best friendships on perceptions of negative relationship qualities (e.g., conflict).     

Energetic Cost and Stability during Human Walking at the Preferred Stride Frequency

The possibility that preferred modes of locomotion emerge from dynamical and optimality constraints and the energetic and dynamical constraints on preferred and predicted walking frequency are explored in this article. Participants were required to walk on a treadmill at their preferred frequency, at a frequency predicted as the resonance of a hybrid pendulum-spring model of the legs, and at frequencies ±15%, ±25%, ±35% of the predicted frequency. Walking at the preferred and predicted frequencies resulted in minimal metabolic costs and maximal stability of the head and joint actions. Mechanical energy conservation was constant across conditions. The head was more stable than the joints. The joints appeared to be in service of the head in maintaining a stable trajectory. The major findings of this study suggest a complementary relationship between energetic (physiological) and stability constraints in the adoption of a preferred frequency of walking. Multiple subsystems may be involved in constraining observed macroscopic behavior in intact biological systems. The approach and results of the study imply that a useful tack in understanding how dynamical control structures arise is to study the potential criteria that serve to act as constraints on skilled movement patterns in unimpaired and impaired populations.     

The dimensional structure of people's fears,threats, and concerns and their relationship with right‐wing authoritarianism and social dominance orientation

Most theories addressing the topic have proposed that threat and fear underlie right‐wing authoritarianism (RWA), and many empirical findings have been consistent with this proposition. Important questions, however, remain unanswered, such as whether RWA is associated with fear and threat in general or only specific kinds of fear and threat. Theories of RWA generate markedly different predictions on this issue, particularly with respect to social or personal fears, and whether the association would also hold for the closely related construct of social dominance orientation (SDO). We investigated the issue by asking 463 undergraduate students to rate their feelings of fear, concern, and anxiety to a comprehensive 93‐item list of potential fears and threats, which were formulated as either personal or social. Exploratory factors analysis identified five distinct fear–threat factors: Harm to Self, Child, or Country; Personal and Relationship Failures; Environmental and Economic Fears; Political and Personal Uncertainties; and Threats to Ingroup. All the fear–threat factors were correlated with RWA, with the strongest correlations being for Threats to Ingroup, and with stronger effects for social than for personal fears. None of the fear factors correlated with SDO. These relationships were not affected by controlling for Social Desirability or Emotional Stability (EMS). When the intercorrelations between fear factors and EMS were controlled using ridge regression, only Threats to Ingroup predicted RWA. Structural equation modeling indicated good fit for a model in which low levels of EMS had a significant path to Threats to Ingroup, which in turn had a significant path to RWA, and EMS having a significant though weak indirect (fully mediated) inverse effect on RWA. Implications of these findings for theories of authoritarianism and future research are discussed.     

Relationships among Negative Emotionality,Responsive Parenting and Early Socio‐cognitive Development in Korean Children

The present study examined the interplay among negative emotionality, responsive parenting and socio‐cognitive developmental outcomes (i.e., communication, personal‐social and problem‐solving outcomes) in about 1620 Korean children using three waves of longitudinal data spanning the first 2 years of their life. Results from the Structural Equation Modeling (SEM) demonstrated that there were moderate to low degrees of stability in negative emotionality, responsive parenting and socio‐cognitive developmental outcomes from infancy to toddlerhood. Evidence for reciprocity in the parent–child relationship was found; responsive parenting predicted higher levels of subsequent child communication (in infancy and toddlerhood), and infants' higher problem‐solving ability predicted higher responsive parenting in toddlerhood. Overall, the cross‐age associations among the variables were similar between boys and girls, but some different patterns were observed: when controlling for family contextual factors and the within‐time correlations, negative emotionality at an earlier point significantly predicted lower responsive parenting at a later point and vice versa only in girls during infancy, but neither in boys nor in toddlerhood. The implications of these findings are discussed. Copyright © 2016 John Wiley & Sons, Ltd.     

Do historic threats to the group diminish identity fusion and its correlates?

We examined the reactions of Spanish participants to three negative historic events: a corruption scandal involving the Royal Family and two separatist efforts by a prosperous region of Spain. Although average fusion scores declined following these events, these declines were limited to sentiments toward the group category – collective ties-; they did not tarnish sentiments toward individual group members – relational ties. Moreover, strongly fused persons continued committed to remain in the group and act agentically by fighting and dying for it. Finally, rank orderings of fusion scores remained stable. These findings demonstrate that negative events weaken some aspects of alignment with the group, including collective ties and fusion, but not other aspects, such as relational ties and endorsement of pro-group behaviors.     

Critical factors governing the thermal stability of austenite in an ultra-fined grained Medium-Mn steel

The time-evolution of retained austenite at 650 °C is shown to be a fair indicator of the factors governing the austenite stability. The grain size contribution to austenite stability is evidenced and a martensite start temperature (M_s) law applicable to medium-Mn steels and including both the chemical and size effects is determined.