Discriminant Analysis Using Mixed Continuous,Dichotomous, and Ordered Categorical Variables

This article proposes an intuitive approach for predictive discriminant analysis with mixed continuous, dichotomous, and ordered categorical variables that are defined via an underlying multivariate normal distribution with a threshold specification. The classification rule is based on the comparison of the observed data logarithm probability density functions. To reduce the computational burden, the analysis is conducted in the context of a confirmatory factor analysis model with independent error measurements. Identification of the dichotomous and ordered categorical variables is discussed. Results are obtained by implementations of a Monte Carlo expectation maximization (MCEM)algorithm and a path sampling procedure. Probabilities of misclassification are estimated via the idea of the “jackknife” method. A real example is given to illustrate the proposed method.     

Myelin breakdown mediates age-related slowing in cognitive processing speed in healthy elderly men

Background

To assess the hypothesis that in a sample of very healthy elderly men selected to minimize risk for Alzheimer’s disease (AD) and cerebrovascular disease, myelin breakdown in late-myelinating regions mediates age-related slowing in cognitive processing speed (CPS).

Materials and methods

The prefrontal lobe white matter and the genu of the corpus callosum myelinate later in brain development (late-myelinating white matter; LMWM) and are more vulnerable to breakdown due to the effects of normal aging. An in vivo MRI biomarker of myelin integrity (transverse relaxation rates; R₂) of LMWM was obtained for 38 very healthy elderly adult men (mean age = 66.3 years; SD = 6.0; range = 55–76). To evaluate regional specificity, we also assessed a contrasting early-myelinating region (splenium of the corpus callosum; SWM), which primarily contains axons involved in visual processing. CPS was assessed using the Trail Making Test.

Results

LMWM R₂ and CPS measures were significantly correlated (r = .515, p = .0009), but no significant association between R₂ and CPS was detected in the splenium (p = .409). LMWM R₂, but not SWM R₂, was a significant mediator of the relationship between age and CPS (p = .037).

Conclusions

In this very healthy elderly sample, age-related slowing in CPS is mediated by myelin breakdown in highly vulnerable late-myelinating regions but not in the splenium.     

Microstructures and tensile properties of 304 steel with dual nanocrystalline and microcrystalline austenite content prepared by aluminothermic reaction casting

The microstructures of 304 stainless steels with different amounts of nanocrystalline and microcrystalline austenite prepared by an aluminothermic reaction casting, without and with annealing at 1073?K for 8?h, have been investigated by X-ray diffraction, an electron probe micro-analyser, a transmission electron microscope and a scanning electron microscope. The steels, both without and with annealing, consisted of different dual nanocrystalline and microcrystalline austenite combinations and a little nanocrystalline δ ferrite, while the average grain size of the nanocrystalline austenite increased from 19 to 26?nm and volume fraction of the microcrystalline austenite increased from 17 to 30% after annealing. The tensile strength of the steel was dramatically increased from 500 to 1000?MPa and the tensile elongation ratio increased from 8 to 12% after annealing. However, the tensile strength was decreased to 600?MPa and the tensile elongation ratio increased from 12 to 22% after an annealing at 1273?K. The combination of dual nanocrystalline and microcrystalline austenite obtained after the annealing at 1073?K results in the best tensile properties.     

Nanoindentation-induced elastic–plastic transition and size effect in α-Al2O3(0001)

The mechanical properties of α-Al₂O₃(0001) have been investigated using the technique of nanoindentation with a Berkovich indenter. Coupled with the Hertzian contact theory, a theoretical shear strength of 28?±?2?GPa was determined from the onset of pop-in events on load–displacement curves during loading, and the intrinsic hardness 30?±?3?GPa was obtained by analysis of the so-called indentation size effect, based on the concept of geometrically necessary dislocations. The predicted values of the shear strength, hardness and elastic modulus are in good agreement with available experimental data. The importance of experimentally calibrating the area function over the contact depth range prior to nanoindentation tests is emphasized.     

Vacancy-decomposition-induced lattice instability and its correlation with the kinetic stability limit of crystals

Vacancy decomposition kinetics in crystals at elevated temperatures is analysed. It is found that lattice instability is induced by a significantly enhanced vacancy decomposition at a critical temperature (T?*). The critical temperature coincides with the kinetic instability limit (kinetic limit of superheating) of crystals in a variety of metals determined from the homogeneous nucleation catastrophe model.     

Qualitative Exploration of Acculturation and Life‐Span Issues of Elderly Asian Americans

Awareness of aging issues across diverse populations begins the journey toward counselors becoming culturally competent across client life spans. Understanding the life‐span experiences of cultural groups is important for helping professionals. The purpose of this research was to gain insight into the qualitative experiences of Asian American elders. The authors conducted semistructured interviews with 8 participants between September 2010 and March 2011 and analyzed the data using the Consensual Qualitative Research method. Findings indicate unique patterns in life‐span development with this population.     

Speaking to the trained ear: musical expertise enhances the recognition of emotions in speech prosody

Language and music are closely related in our minds. Does musical expertise enhance the recognition of emotions in speech prosody? Forty highly trained musicians were compared with 40 musically untrained adults (controls) in the recognition of emotional prosody. For purposes of generalization, the participants were from two age groups, young (18-30 years) and middle adulthood (40-60 years). They were presented with short sentences expressing six emotions-anger, disgust, fear, happiness, sadness, surprise-and neutrality, by prosody alone. In each trial, they performed a forced-choice identification of the expressed emotion (reaction times, RTs, were collected) and an intensity judgment. General intelligence, cognitive control, and personality traits were also assessed. A robust effect of expertise was found: musicians were more accurate than controls, similarly across emotions and age groups. This effect cannot be attributed to socioeducational background, general cognitive or personality characteristics, because these did not differ between musicians and controls; perceived intensity and RTs were also similar in both groups. Furthermore, basic acoustic properties of the stimuli like fundamental frequency and duration were predictive of the participants' responses, and musicians and controls were similarly efficient in using them. Musical expertise was thus associated with cross-domain benefits to emotional prosody. These results indicate that emotional processing in music and in language engages shared resources.     

Family mastery enhances work engagement in Chinese nurses: A cross-lagged analysis

Based on Greenhaus and Powell's (2006) theory of work–family enrichment and the job demands-resources (JD-R) model of work engagement (Bakker & Demerouti, 2008), this study focused on the family-to-work enrichment process by investigating the effect of family mastery on work engagement in a Chinese context. A sample of 279 Chinese female nurses completed questionnaires in a two-wave longitudinal survey. With a cross–lagged analysis, the results indicated that family mastery at Time 1 had a significant positive effect on work engagement at Time 2. Furthermore, the relationship between family mastery and work engagement was stronger in a context of high (vs. low) job demand. These findings suggested that resource generated in family could directly help people stay engaged in the workplace, particularly under stressful working conditions. Our findings have expanded the JD-R model of work engagement and bridged it with theory of work–family enrichment. Implications for theory and practices are discussed.     

Attracting Minority Applicants to Malaysian Organizations: The Effect of Race Composition

This study aims to investigate the effect of race composition of organizational representatives on perceived similarity, organizational attractiveness, and perceived opportunities for advancement. Two hundred and twenty four Malaysian Chinese university students participated in the study. The findings showed that race composition was significantly related to the participant’s perception of similarity to the representatives, attraction to the organization, and perception of advancement opportunities in the organization. Minority Chinese participants gave higher ratings on all three outcome variables when they were presented with an organization featuring a homogenous group of Chinese representatives or a racially diverse group of representatives, than an organization featuring a homogenous group of Malay representatives in recruitment advertising. In summary, the inclusion of minority representatives in recruitment advertising is beneficial in attracting minority applicants.