Increasing toughness by promoting discontinuous precipitation in Cu–Ni–Si alloys

The influence of precipitation morphology, including continuous precipitation (CP) and discontinuous precipitation (DP), on the mechanical behaviour of Cu–Ni–Si alloys was studied. The Cu–6Ni–1.5Si (in wt%) alloy was solution heat treated at 980 °C for 2 h and aged at 500 °C for 0.5 and 3 h to produce CP and DP structures. The DP specimen showed an abnormal increase in tensile ductility with increasing strain rate, unlike the CP counterpart. The impact toughness of the DP specimen was 1.6 times greater than that of CP specimen. The fracture mode in DP specimen was mostly dimpled rupture, while the mixed mode of cleavage fracture and dimpled rupture was noted on the CP specimen.     

Maternal participant experience in a South African birth cohort study enrolling healthy pregnant women and their infants

Background

Critical to conducting high quality research is the ability to attract and retain participants, especially for longitudinal studies. Understanding participant experiences and motivators or barriers to participating in clinical research is crucial. There are limited data on healthy participant experiences in longitudinal research, particularly in low- and middle-income countries. This study aims to investigate quantitatively participant experiences in a South African birth cohort study.

Methods

Maternal participant experience was evaluated by a self-administered survey in the Drakenstein Child Health Study, a longitudinal birth cohort study investigating the early life determinants of child health. Pregnant mothers, enrolled during the second trimester, were followed through childbirth and the early childhood years. Satisfaction scores were derived from the participant experience survey and quantitatively analyzed; associations between satisfaction scores and sociodemographic variables were then investigated using a linear regression model.

Results

Data were included from 585 pregnant mothers (median age 26.6 years), who had participated in the study for a median time of 16 months. Overall participant satisfaction was high (median score 51/60) and associated with increased attendance of study visits. Reasons for participating were a belief that involvement would improve their health, their child’s health or the health of family and friends. Potential reasons for leaving the study were inconvenience, not receiving clinical or study results, and unexpected changes in study visits or procedures. Variables associated with higher overall satisfaction scores were no prior participation in research, higher socioeconomic status, less intensive follow-up schedules and having experienced stressful life events in the past year.

Conclusions

Satisfaction scores were high and associated with increased visit attendance. Participants’ perceived benefits of study participation, most notably the potential for an improvement in the health of their child, were a significant motivator to enroll and remain in the study. The consistent theme of perceived health benefits as a motivator to join and remain in the study raises the question of whether participation in research results in actual improvements in health.

     

Body Image: A Study in a Tri-Ethnic Sample of Low Income Women

This study was designed to examine the evaluative, affective, and behavioral components of body image among 1,217 low-income European American, African American, and Latina women. Participants completed a multidimensional body image questionnaire while awaiting an outpatient clinic appointment. Body mass index (BMI) was determined by medical chart review. Nearly all normal weight and a number of overweight and obese African Americans characterized their weight as normal. In contrast, nearly all overweight and obese European Americans and Latinas regarded themselves as overweight as did over 30% of those of normal weight. European Americans and Latinas with higher BMIs reported more appearance shame than their lower BMI peers did; this pattern was not observed among African Americans. Among Latinas, body image was influenced by length of residency in the U.S. Dr. Berenson is supported by Grant Number K24HD043659, a Midcareer Investigator Award in Patient-Oriented Research, from the National Institute of Child Health and Human Development. Heather Littleton is now at Sam Houston State University.     

Establishing standards for the assessment of suicide risk among callers to the national suicide prevention lifeline

The National Suicide Prevention Lifeline was launched in January 2005. Lifeline, supported by a federal grant from the Substance Abuse and Mental Health Services Administration, consists of a network of more than 120 crisis centers located in communities across the country that are committed to suicide prevention. Lifeline's Certification and Training Subcommittee conducted an extensive review of research and field practices that yielded the Lifeline's Suicide Risk Assessment Standards. The authors of the current paper provide the background on the need for these standards; describe the process that produced them; summarize the research and rationale supporting the standards; review how these standard assessment principles and their subcomponents can be weighted in relation to one another so as to effectively guide crisis hotline workers in their everyday assessments of callers to Lifeline; and discuss the implementation process that will be provided by Lifeline.     

Arousal at encoding,arousal at retrieval,interviewer support,and children's memory for a mild stressor

The relations among children's physiological arousal at encoding and retrieval, interviewer‐provided social support and children's memory for a mild stressor were examined in 109 five‐ and six‐year‐olds. The children came to a research laboratory and watched a fear eliciting video clip. A week later, their memory for the video clip was tested by either a supportive or nonsupportive interviewer. While watching the video and completing the memory interview, children's heart rate was monitored. Increased heart rate at encoding was associated with fewer incorrect responses. In contrast, increased heart rate at retrieval was associated with poorer memory, but only when the interviewer was nonsupportive. Heart rate was unrelated to memory when the interviewer was supportive. Results suggest that arousal at encoding and retrieval have different implications for children's memory for a mild stressor, particularly in nonsupportive interview contexts. Copyright © 2006 John Wiley & Sons, Ltd.     

Why egalitarianism might be good for your health: physiological thriving during stressful intergroup encounters

We compared how evaluations by out-group members and evaluations by in-group members affected participants' stress responses--their neuroendocrine reactivity, cognitive appraisals, and observed anxiety--and how participants' implicit racial bias moderated these responses. Specifically, White participants completed measures of racial bias prior to the experiment. During the experiment, participants performed speech and serial subtraction tasks in front of White or Black interviewers. Several saliva samples were obtained, and they were assayed for catabolic ("breaking down") and anabolic ("building up") hormones. Interviewers' race and participants' racial bias interacted in predicting stress responses. When interviewers were Black, lower racial bias was linked with more salutary stress responses: lower threat appraisals, less anxiety, and increased levels of anabolic hormones. When interviewers were White, no effect was found for threat appraisals or anabolic hormones, and the reverse effect was observed for anxiety. Egalitarianism may have physical and psychological benefits for people living in a diverse society.     

小学生创造性数学问题提出能力的发展研究

运用实验的方法,对371名小学生创造性数学问题提出能力的发展进行了研究。结果表明:1)小学生创造性数学问题提出能力整体呈现波浪式上升的趋势;2)男女生在创造性数学问题提出能力上不存在显著差异;3)城乡小学生创造性数学问题提出能力的发展差异显著,城市小学学生发展比乡村小学学生发展早一年。     

Anxious and nonanxious children's recall of a repeated or unique event

The current study examined 4- and 5-year-olds' memory for an event that was experienced once or was the first in a sequence of four similar events. The event was private swimming lessons for beginners that, because of natural variation in fear of water, were experienced as stressful for some children and not stressful for others. Consistent with much previous research, there was evidence that repeat-event children remembered less than did single-event children. There was some evidence for a beneficial influence of stress on resistance to suggestions. No other effects of stress were found in either the single- or repeat-event children. Implications for the debate on the influence of stress on memory and for children's testimony are discussed.