Interactions between interfacial dislocations and γ/γ′ interface during high temperature – low stress creep in nickel-based single crystal superalloy

ABSTRACT

The interaction between interfacial dislocations and γ/γ′ interface is critical to the high temperature creep properties of single crystal superalloys. However, only a few studies have paid attention to the detailed structure such as local interfacial morphologies and the elemental distribution around interfacial dislocations. In this paper, the interfacial protrusions and related dislocations in a single crystal superalloy after creep at high temperature – low stress have been investigated in detail. It is found that the morphology and size of the interfacial protrusions remain almost the same during the early and middle stages of high temperature creep, which indicates a local equilibrium at the interfacial protrusions. Steps at different height are formed at the γ/γ′ interface at the initial stage of high temperature creep since dislocations could move along the γ/γ′ interface, which indicates that dislocation motion at different creep stage may affect the morphology of γ/γ′ interface.     

Effects of maternal depression in the Still-Face Paradigm: A meta-analysis

The Still-Face Paradigm (SFP) enables researchers to examine the quality of mother-infant interactions. In typical infants, a classic still-face effect (SFE) has been confirmed whereby infants demonstrate reduced positive affect (PA), reduced gaze (GA), and increased negative affect (NA). Recently, the SFP has been used to examine the effect of maternal depression upon infant behaviour. However, the nature and consistency of the behavioural responses of infants of depressed mothers during the SFP remains unclear. In the current meta-analysis, we examined whether or not infants of depressed mothers demonstrate the classic SFE, as well as whether or not these infants display the same levels of PA, NA, and GA as their counterparts with non-depressed mothers. Results revealed that infants of depressed mothers display the classic SFE like infants of their non-depressed counterparts. However, infants of depressed mothers also demonstrated significantly higher levels of PA during the still-face episode. One potential interpretation of this finding is that infants prior experience of similar, depressed interactions with their mothers, encourages them to amplify their positive attachment signals in order to engage maternal attention and response. Alternatively, or additionally, infants of depressed mothers could be using PA in order to regulate their own NA.     

Scaling of stacking fault energy and deformation temperature on strain hardening of FCC metals and alloys

The strain-hardening behaviour of metals and alloys are significantly affected by the dynamic recovery process, the rate of which can be increased by increases in deformation temperature and/or stacking fault energy (SFE). In the present work, the decay slope of the strain-hardening rate with flow stress as a function of both temperature and stacking fault energy is quantitatively evaluated for several face-centered cubic metals and alloys. A universal and quantitative approach to the scaling of the effects of temperature and stacking fault energy on strain-hardening behaviour is developed, which could be useful for predicting deformation behaviour or for material design.     

Harm inflation: Making sense of concept creep

ABSTRACT

“Concept creep” is the gradual semantic expansion of harm-related concepts such as bullying, mental disorder, prejudice, and trauma. This review presents a synopsis of relevant theoretical advances and empirical research findings on the phenomenon. It addresses three fundamental questions. First, it clarifies the characterisation of concept creep by refining its theoretical and historical dimensions and presenting studies investigating the change in harm-related concepts using computational linguistics. Second, it examines factors that have caused concept creep, including cultural shifts in sensitivity to harm, societal changes in the prevalence of harm, and intentional meaning changes engineered for political ends. Third, the paper develops an account of the consequences of concept creep, including social conflict, political polarisation, speech restrictions, victim identities, and progressive social change. This extended analysis of concept creep helps to understand its mixed implications and sets a multi-pronged agenda for future research on the topic.     

Evaluation of the threshold stress for creep deformation in a 3 mol% Y 2 O 3 -stabilized tetragonal ZrO 2 polycrystal

The origin of the increase in the stress exponent from n , 2.0 to with decreasing stress in 3 mol% Y 2 O 3 -stabilized tetragonal ZrO 2 has been examined. The present data show that the increase in the n value arises from the existence of a threshold stress that depends on the grain size and temperature. Careful examination of earlier creep data confirms that evaluation of the threshold stress is sensitive to the accuracy of the creep data and the value of n chosen for the compensation of the data. Inspection of the present results and some recent observations of the deformed microstructure suggests that the threshold stress is associated with intragranular dislocation motion.     

Multiple and iterated contraction reduced to single-step single-sentence contraction

Multiple contraction (simultaneous contraction by several sentences) and iterated contraction are investigated in the framework of specified meet contraction (s.m.c.) that is extended for this purpose. Multiple contraction is axiomatized, and so is finitely multiple contraction (contraction by a finite set of sentences). Two ways to reduce finitely multiple contraction to contraction by single sentences are introduced. The reduced operations are axiomatically characterized and their properties are investigated. Furthermore, it is shown how iterated contraction can be reduced to single-step, single-sentence contraction. However, in this framework the outcome of iterated contraction depends unavoidably on the order in which the inputs are received. This order-dependence makes it impossible to treat two inputs on an equal footing. Therefore it is often preferable to perform changes involving several pieces of information as multiple rather than iterated change.     

Can false memories prime alternative solutions to ambiguous problems?

Research has demonstrated that false memories are capable of priming and facilitating insight-based problem-solving tasks by increasing solution rates and decreasing solution times. The present research extended this finding by investigating whether false memories could be used to bias ambiguous insight-based problem-solving tasks in a similar manner. Compound remote associate task (CRAT) problems with two possible correct answers, a dominant and a non-dominant solution, were created and normed (Experiment 1). In Experiment 2, participants were asked to solve these CRAT problems after they were given Deese/Roediger-McDermott lists whose critical lures were also the non-dominant solution to half of the corresponding CRATs. As predicted, when false memories served as primes, solution rates were higher and solution times were faster for non-dominant than dominant CRAT solutions. This biasing effect was only found when participants falsely recalled the critical lure, and was not found when participants did not falsely recall the critical lure, or when they were not primed. Results are discussed with regard to spreading activation models of solution competition in problem-solving tasks and current theories of false memory priming effects.     

First-time experience of critical range situations in BEV use and the positive effect of coping information

A frequently discussed phenomenon in the context of limited range as a usage barrier for battery electric vehicles (BEVs) is range anxiety (i.e., range stress). The objective of the present research was (1) to examine if the effect of first-time experience of a critical range situation on inexperienced BEV drivers’ range experience (e.g., range stress) is rather positive or negative, (2) to examine if providing minimal coping information can enhance this effect and (3) if a positive adaptation effect can be found under different criticality levels regarding the available range. A field experiment was conducted, in which 74 participants drove a BEV in a critical range situation (i.e., experience of a small range safety buffer) on an unaccompanied 94 km round trip. Results indicate that the first-time experience of a critical range situation has a moderate positive effect on range stress (i.e., reduced range stress after the trip compared to range stress before the trip), that coping information can partly enhance range experience and that these positive effects can be found under both examined criticality levels (critical vs. highly critical range situation). The results can be useful to inform strategies aimed at reducing the experience of range stress in the early period of BEV usage.     

Work-related stress, the blind men and the elephant

Progress in understanding and developing effective responses to work-related stress has been elusive, patchy, and inconsistent. The reasons for this are reviewed, and the inadequacy of traditional stress management techniques and organisational interventions to tackle it are examined. Although necessary, clinical responses to distressed individuals and organisations in isolation can never deal effectively with the overall increasing levels of stress found. Neither can attempts to 'fit' individuals to cope with ever more demanding work patterns and practices. The reviewed evidence suggests that an integrated approach that acknowledges how social, economic, political, and organisational factors impact on individual needs and values is needed. This integrated approach is described, with its required input from communities and politicians, as well as occupational health specialists. The article concludes that work-related stress is the result of complex psychosocial interactions that simply cannot be effectively understood or treated by any one professional group or theoretical approach.     

Testing an extended theory of planned behavior to predict young people's intentions to join a bone marrow donor registry

An extended theory of planned behavior (TPB) was used to understand the factors, particularly control perceptions and affective reactions, given conflicting findings in previous research, informing younger people's intentions to join a bone marrow registry. Participants (N = 174) completed attitude, subjective norm, perceived behavioral control (PBC), moral norm, anticipated regret, self‐identity, and intention items for registering. The extended TPB (except PBC) explained 67.2% of variance in intention. Further testing is needed as to the volitional nature of registering. Moral norm, anticipated regret, and self‐identity are likely intervention targets for increasing younger people's bone marrow registry participation.     

认知固执导致持续应激的认知与神经机制

认知固执(Perseverative Cognition, PC)是一种重复或长期的消极认知表征,既能够使用量表测量,也可以通过实验诱发。认知固执会导致持续应激反应,进而影响个体的身心健康。其导致持续应激反应的认知机制体现在个体难以识别安全信号,高认知固执个体会表现出低心率变异性的显著特征;在脑机制方面主要表现为前额叶的抑制控制功能失调、杏仁核与前扣带回的病理性改变以及前额叶-杏仁核的连接减弱。未来研究应深入探讨认知固执的影响因素以及干预措施,同时需要进一步分析内隐认知固执的测量方式及其对个体的影响。     

Creep of micron-sized aluminium columns

Micron-sized aluminium columns, produced by focused-ion beam milling, were subjected to compressive creep in a nanoindentation machine using a flat-ended tip to study their time-dependent deformation behaviour at room temperature. At constant load, their strain increased almost linearly with time, with sporadic but large strain bursts superimposed. This represents a form of creep behaviour not known beforehand for aluminium. Strain bursts were also observed to occur during reloading at stresses higher than the first yield stress during initial loading.     

Effects of instructions and biofeedback on EEG-alpha production and the effects of EEG-alpha biofeedback training for controlling arousal in a subsequent stressful situation

In Phase One, 44 subjects participated in a 2 (instructions to increase alpha, no instructions to increase alpha) × 2 (alpha biofeedback, no alpha biofeedback) factorial experiment. Results indicated that increases in alpha production were due to instructions to increase alpha and that biofeedback had no effect on alpha production. In Phase Two, the 44 subjects from Phase One were exposed to a threat of shock whereas 11 additional subjects in a control condition were not. The design employed in Phase Two was a 2 (previous instructions and stress, no previous instructions and stress) × 2 (previous biofeedback and stress, no previous biofeedback and stress) plus 1 (no previous instructions/no previous biofeedback, no stress). Results indicated that the threat of shock was effective in increasing arousal (as measured by heart rate and skin resistance) but previous EEG-alpha biofeedback training was not effective in helping subjects decrease arousal while in the stressful situation. The results indicate that it is the instructions (and related information concerning alpha) rather than the biofeedback that is critical in alpha biofeedback training and that this training does not appear to have utility for controlling arousal under stress.     

Some boundary conditions for a word superiority effect

A word superiority effect was obtained using a fixed stimulus set, positional certainty of the critical letter, mixed trial type, and instructions to fixate the critical letter. Control experiments established that this effect was not due to lateral masking. Further experiments extended the finding of a fixed-set word superiority effect to other stimulus sets, and to lowercase and mixed-case stimuli. The mixed-case word superiority effect is inconsistent with supraletter feature models of word recognition and, instead, lends support to hierarchical codes models. It was demonstrated that an unusually wide spacing of letters can disrupt the formation of word-level codes, and that wide visual angles are not necessarily disruptive as long as normal spacing is maintained.     

Sensorimotor coordination generates extended agency

When we synchronize finger tapping with a visual metronome, we experience a strikingly robust phenomenon of extended agency known as Spizzo’s effect. This effect is the compelling sense that we are controlling the metronome. The effect arises even though the agent knows that the metronome operates autonomously. We propose that the extended agency here established over metronome pulses results from sensorimotor coordination. To test this hypothesis, we operationalize sensorimotor coordination in terms of the correlation structures in series of asynchronies or reaction times from two finger-tapping tasks. Analyses reveal that, whereas correlation structures vary across individuals and show a systematic drift towards nonstationarity with increasing metronome frequency conditions, the presence of correlation structure is co-extensive with Spizzo’s effect. We interpret this result as supporting the view that extended agency relies on sensorimotor coordination. Sensorimotor coordination, we suggest, may induce the effect by integrating the perception of visual pulses and the agency over tapping into a synesthetic experience.     

Coping with a threat to life: A longitudinal study of self-concept,social support,and psychological distress

The relationship of self-concept (self-esteem and mastery) and social support to psychological distress was studied among 68 Israeli women immediately prior to undergoing biopsy for suspected cancer (acute stress) and 3 months later for the noncancer group (everyday stress). It was predicted that women with stronger self-concepts and more social support would experience less state depression and state anxiety during the acute crisis than women with weaker self-concepts and less social support. It was further predicted that self-concept would be more critical than social support due to the acute nature of the event. Finally, self-concept was predicted to be related to psychological distress both during the acute and everyday stress situations (a direct effect), while social support was predicted to be related to psychological distress only during the acute stress situation (a buffering effect). The hypotheses were generally confirmed. However, self-concept and social support were seen as complexly related to psychological distress during the acute phase, one not necessarily being more critical than the other. The selective employment of available resistance resources to fit the situation and implications for preventive intervention were discussed.     

Very high temperature creep behavior of a single crystal Ni-based superalloy under complex thermal cycling conditions

Very high temperature thermal cycling has been performed on the single crystal superalloy MC2 to evaluate the effect of periodic overheating on creep behavior. The experiments consist of alternately performing 1 min dwell time at 1100°C and 1150°C for every 15 min during creep test at 1050°C/120 MPa. Both thermal cycling and prior γ′-rafting appear to be deleterious to the cyclic creep properties. The observed non-isothermal creep behavior is correlated with γ′-dissolution/coalescence processes, especially during overheatings where γ′ micro-rafts seem to play a significant role.     

Stress-induced relapse to drug seeking in the rat: role of the bed nucleus of the stria terminalis and amygdala

There is growing interest in the role that the bed nucleus of the stria terminalis (BNST) and central nucleus of the amygdala (CeA), components of the extended amygdala, play in drug addiction. Within the BNST and CeA, there is an extensive system of intrinsic, primarily GABAergic, interconnections known to synthesize a variety of neuropeptides, including corticotrophin-releasing factor (CRF). The actions of CRF at extrahypothalamic sites,including the BNST and CeA, have been implicated in stress responses and in the aversive effects of withdrawal from drugs of abuse. Most recently, we have shown a critical role for extrahypothalamic CRF in stress-induced reinstatement of drug seeking in rats. In attempting to determine which brain circuitry mediates the effect of stress on relapse and, more specifically, where in the brain CRF acts to initiate the behaviours involved in relapse, we focused on the BNST and CeA. In the present paper, we summarize studies we have conducted that explore the role of these brain sites in stress-induced relapse to heroin and cocaine seeking, and then consider how our findings can be understood within the more general context of what is known about the role of the BNST and CeA in stress-related and general approach behaviours, such as drug seeking.     

Mindfulness-Based Stress Reduction in Medical Settings

Meditation, as a psychological intervention, has become of increasing interest to psychologists who conduct clinical research with or provide clinical services to medical populations. Mindfulness-based stress reduction (MBSR) is a manualized program which teaches a variety of meditation techniques and has frequently been used in medical settings with mixed medical populations. The following is a review of the literature, which provides preliminary support for the effectiveness of MBSR in specific medical populations, including persons with chronic pain, cancer and heart disease. Despite these encouraging findings, experts agree that continued research is needed, especially controlled studies with more rigorous methodology.     

Parentification,Stress, and Problem Behavior of Adolescents who have a Parent with Mental Health Problems

When adolescents live with a parent with mental illness, they often partly take over the parental role. Little is known about the consequences of this so‐called parentification on the adolescents' internalizing and externalizing problems. This survey study examined this effect cross‐sectionally and longitudinally in a sample of 118 adolescents living with a parent suffering from mental health problems. In addition, the study examined a possible indirect effect via perceived stress. Path analyses were used to examine the direct associations between parentification and problem behavior as well as the indirect relations via perceived stress. The results showed that parentification was associated with both internalizing and externalizing problems cross‐sectionally, but it predicted only internalizing problems 1 year later. An indirect effect of parentification on adolescent internalizing and externalizing problems via perceived stress was found, albeit only cross‐sectionally. These findings imply that parentification can be stressful for adolescents who live with a parent with mental health problems, and that a greater awareness of parentification is needed to prevent adolescents from developing internalizing problems.