Characterization of PLZT ceramics modified by isovalent (Ba,Sr), donor (Nb) and acceptor (Zn) dopants for piezoelectric applications

This article describes the influence of microstructure on the dielectric and piezoelectric properties of isovalent- donor- and acceptor-modified lead lanthanum zirconium titanate (PLZT) ceramics. The ceramic compositions, with formula: [Pb_0.954La_0.016Ba_0.01Sr_0.02][Zr_0.525Ti_0.475]_{0.981?( m /2)}Nb_0.012Zn _m O₃ where m =?0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol% Zn, were synthesized via a solid-state reaction method. X-ray diffraction studies are supported by tolerance factor and electronegativity difference measurements. Scanning electron microscopy studies reveal grain growth enhancement with increase of Zn concentration. As the Zn concentration increased from 0 to 0.8 mol%, the room-temperature dielectric constant increased while the Curie temperature decreased continuously. An increase in the Zn content had the most significant effect on the piezoelectric properties. The optimum piezoelectric properties were observed for 1 mol% Zn composition.     

Voices of African Traditional Healers: Cultural Context and Implications for the Practice of Counselling in Sub-Saharan Africa

The healing paradigm implicit in many sub-Saharan African cultures is embedded in African cosmology, and thus the recognition of this is essential for understanding Traditional African Healing practices and implementing collaborative counselling practices. To this end, this article focuses on the cultural importance, or voice, of traditional healers in sub-Saharan Africa. The current article uses an ethnographic approach to analyse systematically the cultural context of indigenous healing practices in sub-Saharan Africa. The anthropological importance of Traditional Healing practitioners, the context of healing, and the changing legal and ethical status of Traditional Healers are addressed as pivotal in furthering the development of this crucial, yet under utilized resource. The authors propose that such cultural understanding is highly relevant to the work of professional counselors.     

Addressing Urgent Community Mental Health Needs in Rwanda: Culturally Sensitive Training Interventions

Rwandan leaders in the health and educational sectors have begun to discuss the necessity for establishing culturally appropriate community-based mental health counselling services in Rwanda, especially trauma counselling. The need for a community psychology approach is anchored in the lingering effects of the genocide and the continuing post-traumatic stress symptoms suffered by many in the population. Capacity building in an effort like this would require the design of multi-level counselling curricula that are sensitive to the social structures within Rwandan culture. These curricular endeavours call for the development of a National Counselling Centre to serve as a structural mechanism for organizing community-based counselling initiatives. We consider the community health services needs in Rwanda here, along with associated challenges and strategies for effective mental health services in a country with a recent history of genocide. A community psychology approach to mental health would benefit Rwandan society by making trauma counselling and recovery services available and accessible to citizens throughout the country.     

Cross-cultural similarities in category structure

Categories, as mental structures, are more than simply sums of property frequencies. A number of recent studies have supported the view that the properties of categories may be organised along functional lines and possibly dependency structures more generally. The study presented here investigates whether earlier findings reflect something unique in the English language/North American culture or whether the functional structuring of categories is a more universal phenomenon. A population of English-speaking Americans was compared to a population of Cantonese-speaking Hong Kong Chinese. The findings clearly support the view that functional influences on category centrality are universal (or at least common to Cantonese-speaking Hong Kong Chinese and English-speaking Americans), albeit with specific cross-cultural/cross-linguistic group differences in the particular properties that are considered central to categories.     

Towards an Understanding of Nurturing and Restraining Relational Patterns in School Communities

This study aimed to understand the nature of nurturing and restraining relationships in a school communiy. The inquiry entailed a single instrumental case study of a selected school community in a semi-urban context in South Africa. Participants were learners (n=720), teachers (n=33) and administrative and terrain staff members (N=8) as well as two parents. Data on participants' perceptions of relationships in the school community were collected using work sessions/nominal group techniques, visual representations, and focus group interviews. Thematic analysis of the data revealed connectedness, respect, care and transparent communication as aspects that nurture relationships. Limited connectedness between people, the abuse of power, shifting of responsibility and disrespect for one another were revealed as aspects that restrain relationships.     

Parental Monitoring,Association with Externalized Behavior,and Academic Outcomes in Urban African‐American Youth: A Moderated Mediation Analysis

African‐American adolescents exposed to neighborhood disadvantage are at increased risk for engaging in problem behavior and academic underachievement. It is critical to identify the mechanisms that reduce problem behavior and promote better academic outcomes in this population. Based on social disorganization and socioecological theories, the current prospective study examined pathways from parental monitoring to academic outcomes via externalizing behavior at different levels of neighborhood disadvantage. A moderated mediation model employing maximum likelihood was conducted on 339 African‐American students from 9th to 11th grade (49.3% females) with a mean age of 14.8 years (SD ± 0.35). The results indicated that parental monitoring predicted low externalizing behavior, and low externalizing behavior predicted better academic outcomes after controlling for externalizing behavior in 9th grade, intervention status, and gender. Mediation was supported, as the index of mediation was significant. Conversely, neighborhood disadvantage did not moderate the path from parental monitoring to externalizing behavior. Implications for intervention at both community and individual levels and study limitations are discussed.     

Association between Sexual Victimization History,Posttraumatic Stress Symptoms,and Women’s Decision Making in Risky Social Situations: the Moderating Effect of Ethnicity

This study evaluated the association between sexual victimization history, posttraumatic stress symptoms, and women’s decision making in social situations, and whether ethnicity moderated these associations. Participants were 334 undergraduate women between ages 18 and 24. The sample was diverse ethnically (Non-Hispanic white, n = 177; Hispanic, n = 157) and composed primarily of freshman, single women. Stimuli were written vignettes describing social situations that varied in their degree of victimization risk. Participants completed tasks that assessed their ability to generate and select responses to the situations, as well as their perceived efficacy in executing responses. They then completed the Sexual Experiences Survey to quantify the severity of victimization experiences and the PTSD Checklist – Civilian Version to measure symptoms of posttraumatic stress. Structural equation modeling (SEM) of women’s decision making revealed that more severe victimization history and greater posttraumatic stress symptoms were associated with less effective response generation, and greater posttraumatic stress symptoms was associated with reduced perceived efficacy in executing effective responses. Ethnicity also moderated the effect of victimization history on perceived efficacy. For Non-Hispanic White women, more severe victimization history was related to less effective response generation and perceived efficacy when considering responses, while for Hispanic women, victimization history was unrelated to both decision making processes. This study emphasizes the importance of decision making as it relates to women’s victimization risk. These processes, as well as the influence of ethnicity on women’s decision making, appear relevant to consider when developing preventative interventions for college women.     

The fate of unattended stimuli and emotional habituation: Behavioral interference and cortical changes

The interference produced by the viewing of emotional distractors has been interpreted as evidence that emotional cues are processed in a fairly mandatory fashion, and that they divert attention from the primary ongoing task. However, few studies have examined how behavioral emotional interference varies with repeated presentation of the same emotional distractors. In two experiments, while participants were engaged in a parity judgment task, we investigated the effects of repetition of task-irrelevant emotional pictures, as reflected in both behavioral interference (Experiments 1 and 2) and neural activity (Experiment 2). Both experiments showed that the slowing of reaction times that was observed when viewing emotional, compared to neutral, scenes disappeared after only a few repetitions, suggesting diminished attention allocation to repeated emotional pictures. Conversely, in Experiment 2, neural correlates of picture processing revealed that the late positive potential (LPP) amplitude continued to be enhanced for emotional, compared to neutral, distractors despite picture repetition and the presence of a concurrent task. Altogether, these findings suggest that while evaluative processes are mandatory, and continue to engage cortico-limbic appetitive and defensive systems even after massive repetition, as suggested by the affective modulation of the LPP, attentional processes are not necessary after several repetitions of the same stimulus, as indicated by the rapid decline of behavioral emotional interference.