Nanoindentation study of size effects in nickel–graphene nanocomposites

Metal–graphene nanocomposites find applications in nanoscale devices, as functional materials and can serve as a test bed to gain insight into fundamental deformation mechanisms of metals under geometric confinement. Here, we report full atomistic nanoindentation simulations for nickel–graphene nanocomposites with varied numbers of layers of graphene sheets to investigate the size effects on the hardness, and to understand how emerging dislocation loops interact with the nickel–graphene interface under varied geometric confinements. A detailed analysis of the plastic deformation mechanism shows that as dislocation loops reach the nickel–graphene interface, the local bending of the graphene sheet is altered and further dislocation propagation is blocked. An increase in the number of graphene layers decreases the hardness, but increases the maximum elastic deformation of the nickel–graphene nanocomposites. These findings indicate that the mechanical properties of nickel–graphene nanocomposites can be engineered by controlling the thickness of nickel and graphene layers, respectively.     

3-D eye movement analysis

This paper presents a novel three-dimensional (3-D) eye movement analysis algorithm for binocular eye tracking within virtualreality (VR). The user’s gaze direction, head position, and orientation are tracked in order to allow recording of the user’s fixations within the environment. Although the linear signal analysis approach is itself not new, its application to eye movement analysis in three dimensions advances traditional two-dimensional approaches, since it takes into account the six degrees of freedom of head movements and is resolution independent. Results indicate that the 3-D eye movement analysis algorithm can successfully be used for analysis of visual process measures in VR. Process measures not only can corroborate performance measures, but also can lead to discoveries of the reasons for performance improvements. In particular, analysis of users’ eye movements in VR can potentially lead to further insights into the underlying cognitive processes of VR subjects.     

Depressive symptoms, cortisol, and cognition during human aging: the role of negative aging perceptions

Depressive symptoms and memory impairments are associated with heightened stress hormone levels during aging. A factor that is related to memory deficits during aging is internalized negative aging stereotypes; the idea people have about the process of aging. In this study, we assessed the associations between internalized negative aging stereotypes, depressive symptoms, subjective and objective memory assessments, and cortisol concentration among older adults. Forty older adults aged between 58 and 85 years (18 females and 22 males; mean age?±?SD: 71.25?±?8.80 years) were assessed in this study. Measures of internalized negative aging stereotypes, depressive symptoms, and both subjective and objective memory performance were assessed. Salivary samples were obtained for measurement of cortisol concentration. Stepwise linear regressions were executed in our main analyses. Internalized negative aging stereotypes were associated with increased depressive symptoms and subjective memory complaints. No significant differences were observed for objective memory performance, or cortisol concentration. Internalized negative aging stereotypes are associated with increased depressive symptomatology and subjective complaints of memory; however, they do not predict increased cortisol concentration nor objective memory performance during aging. These results indicate that the mechanism underlying the association between internalized negative aging stereotypes and cognitive impairments may not be related to dysregulations of cortisol secretion among older adults.     

Activation of number facts in bilinguals

Two experiments examined the effect of the presentation format of numbers—digits versus word format in the first and in the second languages of bilinguals—on mental arithmetic. Speed of number-fact retrieval and the presence of interference produced by numbers that were either numerically close to or associatively related to the correct answers of stored arithmetic problems (e.g., 2+5 and 7×8) were compared across formats. The verification of true problems was increasingly slower and less accurate from the digit condition to the second-language condition. Interference was produced by both types of incorrect answers in the digit and first-language conditions, whereas in the second-language condition, it was constrained to answers that were numerically close to correct answers. Together, the results suggest that the retrieval of arithmetic facts and the automatic spreading of activation within the network of numerical facts are not only language-sensitive, but format-sensitive in general.     

Mental Health Issues of Breast Cancer Patients: The Kerala Context

The present study was a qualitative enquiry into the mental health issues of breast cancer patients in Kerala. The sample consisted of thirty mastectomy inpatients in the age range 20–60 years, undergoing chemotherapy/radiation therapy for the past 6 months to 1 year. The interview data were thematically analysed, and the major emergent themes elicited were psychopharmacological and socio-economic in nature. Treatment-related issues included dizziness and fatigue, whereas fear of death, fear of recurrence, discrimination, inability to take care of their children, and the escalating cost of treatment were the main psychological concerns.     

Facial expressions are more easily produced on the upper-lower compared to the right-left hemiface

Clinical research has concentrated on differences in intensity of expression between the right and left hemiface as a means to assess hemispheric differences in motor control. However, observations by social psychologists suggest that control of facial expression may be organized predominantly across the upper-lower hemiface because during social interactions individuals may produce brief facial blends of emotions, in which the upper and lower face display a different emotion. Full facial versus upper/lower and right/left facial blends of emotion were posed by 20 subjects, 10 men and 10 women ranging in age from 20 to 37 years. The subjects rated the difficulty of each pose on a 5-point Likert scale. Digital photographs of the poses were taken and the full and half-facial poses were shown in random order to four judges who indicated what pose was being performed. The results were very robust and confirmed that facial blends of emotion are more easily and accurately posed on the upper-lower than on the right-left hemiface. Our results are consistent with recent anatomical studies showing separate cortical areas for motor control of the upper versus lower face in primates. Based on recent research exploring hemispheric differences in perceiving facial blends of emotion, the left hemisphere may be more involved with modulating lower facial expressions and the right hemisphere more involved with modulating upper facial expressions.     

Methodological issues in the use of the concurrent activities paradigm

This paper presents a critical analysis of one type of dual-task procedure, the lateralized concurrent activities paradigm. Extrinsic and intrinsic factors that may influence the interpretation of results obtained with this paradigm are isolated and methodological refinements in experimental design and analysis are suggested.     

Differential cerebral involvement in the cognitive functioning of bilinguals

The cognitive processing strategies of two groups of French-English bilinguals were studied by means of an auditory Stroop test designed to evaluate cerebral hemispheric involvement. An “early bilingual” group were bilingual before the age of 5, and a “late bilingual” group were bilingual after the age of 10. Stimuli were words uttered in pitches that were related to word meanings either congruently (as in the word “high” uttered in a high pitch) or incongruently (the word “haute” uttered in a low pitch). In one condition, subjects were to differentiate low from high pitches, disregarding meaning, while in a second condition, they were to disregard pitch and respond to word meanings. Measures of field independence were also taken. Results of data analyses suggest that male early bilinguals—the most field independent subgroup—process meaning efficiently in both cerebral hemispheres, but process pitch better in the right hemisphere. However, male late bilinguals and female bilinguals, both early and late, process meaning more rapidly in the right cerebral hemisphere and pitch equally rapidly in both hemispheres. The findings are interpreted as reflecting hemisphere-based strategy and sex differences in information-processing by the two bilingual groups.