SH波在功能梯度压电带中共线双裂纹处的散射

讨论了SH波在功能梯度压电带中共线双裂纹处的散射问题,假定裂纹面上边界条件是电渗透性的,通过建立数学模型并利用Copson方法对问题进行了求解,最后通过数值算例讨论了右裂纹尖端的动应力强度因子与材料梯度参数等因素的关系．     

Moringa oleifera extract enhances sexual performance in stressed rats

Aphrodisiacs are required to improve male sexual function under stressful conditions. Due to the effects of oxidative stress and dopamine on male sexual function, we hypothesized that Moringa oleifera leaves might improve male sexual dysfunction induced by stress. Therefore, the effects on various factors playing important roles in male sexual behavior, such as antioxidant effects, the suppression of monoamine and phosphodiesterase type 5 (PDE-5) activities, serum testosterone and corticosterone levels, and histomorphological changes in the testes, of a hydroethanolic extract of M. oleifera leaves were investigated. Various doses of extract including 10, 50, and 250 mg/kg body weight (BW) were given orally to male Wistar rats before exposure to 12 h-immobilization stress for 7 d. The results demonstrated that the extract showed both antioxidant and monoamine oxidase type B (MAO-B) suppression activities. At 7 d of treatment, the low dose of extract improved sexual performance in stress-exposed rats by decreasing intromission latency and increasing intromission frequency. It also suppressed PDE-5 activity, decreased serum corticosterone level, but increased serum testosterone, numbers of interstitial cells of Leydig and spermatozoa. The increased numbers of interstitial cells of Leydig and spermatozoa might have been due to the antioxidant effect of the extract. The increased sexual performance during the intromission phase might have been due to the suppression of MAO-B and PDE-5 activities and increased testosterone. Therefore, M. oleifera is a potential aphrodisiac, but further research concerning the precise underlying mechanisms is still needed.     

大学生压力应对方式的调查研究

本研究采用“简易应对方式问卷”对北京552名大学生进行调查,结果发现:(1)当前的大学生面临压力时以积极应对方式为主;(2)男生在积极应对因素上显著高于女生;(3)来自城市的大学生在积极应对因素上显著高于来自农村的大学生;(4)经常运动的大学生在积极应对因素上显著高于不经常运动的大学生。     

Relationship between adverse early experiences,stressors, psychosocial resources and wellbeing

The study examined a diathesis stress model of the relationship between adverse child experiences (ACEs), stressors and psychosocial resources to explore their relationship with wellbeing. A cross sectional study was conducted across two mental health and addiction treatment centers. 176 individuals were interviewed using a demographics form, SCID-DSM-IV(First, Spitzer, Gibbon, &Williams, 2002), Child Trauma Questionnaire (Bernstein & Fink, 1998), NEO-Five Factor Inventory (Costa & McCrae, 1992), Trait Emotional Intelligence Questionnaire (Petrides, 2009), The Coping, Inventory for Stressful Situations (CISS) (Endler & Parker, 1990), Recent Life Events Questionnaire (Department of Health, 1985) and perceived social support from family, friends and religion. Multiple, regressions and correlations were used to analyze the data. All early experiences, except physical, abuse and death of a parent in childhood, were significantly correlated with increased number of, stressors and lower wellbeing scores. This is possibly because of sample specific issues. Number of stressors partially mediated the relationship between ACEs and wellbeing. Increased number of ACEs was related to higher neuroticism and emotion-focused coping and lower conscientiousness, agreeableness, trait emotional intelligence and task coping scores. These resources were significantly related to increased stressors and lower wellbeing. Distraction and emotion coping significantly moderated the relationship between number of stressors and wellbeing. These findings support the diathesis stress model and indicate that there are significant relationships between ACEs, psychosocial, resources, stressors and wellbeing. Recommendations to improve wellbeing are discussed.     

瑜伽对大学生血压和压力水平调节影响的研究

本文研究的目标在于探索瑜伽对大学生血压和压力水平的调节。众所周知,影响着学生的生活和生活方式的因素有很多,如生物因素、社会因素和心理因素等,为了促进身体和精神健康,以及疾病的预防,我们所采用的瑜伽练习将会起重要作用。瑜伽在促进健康,预防和治疗疾病方面是非常有效的,该方法已经经过了时间的检验和很多专家的科学论证。我们在深圳大学瑜伽俱乐部采用自愿报名方式选出60名年龄在18-22岁在校大学生,把学生分成两组,30名学生作为实验组,另30名学生作为对照组,在试验前和试验后对分别两组被试进行身体指标的测试和对比分析。本文研究时间的计划是：每天早晨45min,为期60天。60天后再次对两个组的学生进行测试,测试结果显示出瑜伽练习对年龄在18-22岁大学生血压和压力水平的调节具有显著影响,显著系数在0.1水平范围。     

制氢装置中容器封头应力腐蚀裂纹的检测与分析

制氢装置在实际生产过程中,由于氢气和氧气的析出使得不锈钢设备的特殊部位积聚一定量碱液形成应力腐蚀（SCC）,从而导致应力腐蚀破裂,发生安全事故。文中针对1Cr18Ni9Ti材质的压力容器的应力腐蚀现象进行了合金成分分析、硬度测定和金相检验。测试分析结果表明,系统中的0H^-和封头部位的焊接接头结构形式引起碱液浓缩是造成奥氏体不锈钢产生应力腐蚀破裂的主要原因。对此文中从压力容器的结构设计、合理选材和最大限度地消除焊接残余应力等几方面提出了一些预防措施。     

泥浆泵缸套失效分析

本文介绍了泥浆泵设计过程中基本参数的确定、关键机构的受力分析,分析了缸套的实际工况和受力情况,得出缸套失效的主要原因是泥浆的腐蚀和磨粒磨损。进而继续详细分析冲蚀拉槽;磨料磨损拉槽;外径均匀磨损增大而丧失密封功能;疲劳磨损和气蚀磨损这几种主要磨损的失效形式。又因为现阶段各大油田普遍用复合性双金属缸套,就这种缸套的热镶装工艺过程复杂和生产效率低的问题进行了探讨,进而提出表面强化技术方面的方案,使其工作寿命进一步提高。     

A process-oriented analysis of parent acculturation,parent socio-cultural stress,family processes,and Latina/o youth smoking and depressive symptoms

Latina/o youth in the U.S. are often characterized by elevated rates of cigarette smoking and depressive symptoms, and these rates appear to vary by youth acculturation and socio-cultural stress. Scholars suggest that parents’ cultural experiences may be important determinants of youth smoking and depressive symptoms. However, few studies have examined the influence of parent acculturation and related stressors on Latina/o youth smoking and depressive symptoms. To address this gap in the literature, in the current study we investigated how parent-reported acculturation, perceived discrimination, and negative context of reception affect youth smoking and depressive symptoms through parent reports of familism values and parenting. The longitudinal (4 waves) sample consisted of 302 Latina/o parent-adolescent dyads from Los Angeles (N = 150) and Miami (N = 152). Forty-seven percent of the adolescent sample was female (M age = 14.5 years), and 70% of the parents were mothers (M age = 41.10 years). Parents completed measures of acculturation, perceived discrimination, negative context of reception, familism values, and parenting. Youth completed measures regarding their smoking and symptoms of depression. Structural equation modeling suggested that parents’ collectivistic values (Time 1) and perceived discrimination (Time 1) predicted higher parental familism (Time 2), which in turn, predicted higher levels of positive/involved parenting (Time 3). Positive/involved parenting (Time 3), in turn, inversely predicted youth smoking (Time 4). These findings indicate that parents’ cultural experiences play important roles in their parenting, which in turn appears to influence Latino/a youth smoking. This study highlights the need for preventive interventions to attend to parents’ cultural experiences in the family (collectivistic values, familism values, and parenting) and the community (perceived discrimination).     

Discrimination and multicultural identity configurations: The mediating role of stress

The present research examines perceived discrimination as a predictor of how multicultural individuals negotiate and configure their different cultural identities within the self. We focused on three multicultural identity configurations: having one predominant identity (categorization), compartmentalizing one’s different identities, and integrating one’s identities. Since discrimination is related to intraindividual discordance and is stressful, we examined the mediating role of stress in the associations between discrimination and the identity configurations in 259 multicultural individuals. Mediation analyses revealed that greater discrimination predicted compartmentalization through greater stress, while lower discrimination predicted greater identity integration through lower stress. Categorization was not predicted by discrimination or by stress. Discrimination and stress appear to have damaging and depleting roles that hamper multiculturals’ capacity to reconcile their identities into a cohesive whole.     

The organizational impact of university labor unions

The current review presents both postulated and empirically tested consequences of university unionization and labor strikes on the North American institution’s administration, faculty, and students. The review explores the impact of collective bargaining on employee working conditions including job security, academic freedom, university governance, and due process. More importantly, this review examines the much neglected issue of organizational work relationships in a unionized academic environment. The relationships discussed include those between faculty members, between the faculty and administration, between the faculty and the university as an institution, and between the faculty and their union. The threat of unionization and labor strikes to the professor–student or mentor–mentee relationship has been a central concern of those opposed to graduate student unions, and this issue is also addressed here. The text concludes with the identification of potential areas for future research.