Phonon spectra and thermodynamic properties of rare gas solids based on empirical and semi-empirical (ab initio) two-body potentials : a comparative study /

We study the phonon dispersion, cohesive and thermal properties of raxe gas solids Ne, Ar, Kr, and Xe, using a variety of potentials obtained from different approaches; such as, fitting to crystal properties, purely ab initio calculations for molecules and dimers or ab initio calculations for solid crystalline phase, a combination of ab initio calculations and fitting to either gas phase data or sohd state properties. We explore whether potentials derived with a certain approaxih have any obvious benefit over the others in reproducing the solid state properties. In particular, we study phonon dispersion, isothermal ajid adiabatic bulk moduli, thermal expansion, and elastic (shear) constants as a function of temperatiue. Anharmonic effects on thermal expansion, specific heat, and bulk moduli have been studied using A^ perturbation theory in the high temperature limit using the neaxest-neighbor central force (nncf) model as developed by Shukla and MacDonald [4]. In our study, we find that potentials based on fitting to the crystal properties have some advantage, particularly for Kr and Xe, in terms of reproducing the thermodynamic properties over an extended range of temperatiures, but agreement with the phonon frequencies with the measured values is not guaranteed. For the lighter element Ne, the LJ potential which is based on fitting to the gas phase data produces best results for the thermodynamic properties; however, the Eggenberger potential for Ne, where the potential is based on combining ab initio quantum chemical calculations and molecular dynamics simulations, produces results that have better agreement with the measured dispersion, and elastic (shear) values. For At, the Morse-type potential, which is based on M0ller-Plesset perturbation theory to fourth order (MP4) ab initio calculations, yields the best results for the thermodynamic properties, elastic (shear) constants, and the phonon dispersion curves.

An application of cell-cluster theory to a rare gas crystal /|n[by] K. Westera. - 260 St. Catharines [Ont.] : Dept. of Physics, Brock University,

The Lennard-Jones Devonshire 1 (LJD) single particle theory for liquids is extended and applied to the anharmonic solid in a high temperature limit. The exact free energy for the crystal is expressed as a convergent series of terms involving larger and larger sets of contiguous particles called cell-clusters. The motions of all the particles within cell-clusters are correlated to each other and lead to non-trivial integrals of orders 3, 6, 9, ... 3N. For the first time the six dimensional integral has been calculated to high accuracy using a Lennard-Jones (6-12) pair interaction between nearest neighbours only for the f.c.c. lattice. The thermodynamic properties predicted by this model agree well with experimental results for solid Xenon.

Application of [Lambda] to the fourth perturbation theory in calculating the equation of state of rare gas solids and fcc metals

We have calculated the thermodynamic properties of monatomic fcc crystals from the high temperature limit of the Helmholtz free energy. This equation of state included the static and vibrational energy components. The latter contribution was calculated to order A4 of perturbation theory, for a range of crystal volumes, in which a nearest neighbour central force model was used. We have calculated the lattice constant, the coefficient of volume expansion, the specific heat at constant volume and at constant pressure, the adiabatic and the isothermal bulk modulus, and the Gruneisen parameter, for two of the rare gas solids, Xe and Kr, and for the fcc metals Cu, Ag, Au, Al, and Pb. The LennardJones and the Morse potential were each used to represent the atomic interactions for the rare gas solids, and only the Morse potential was used for the fcc metals. The thermodynamic properties obtained from the A4 equation of state with the Lennard-Jones potential, seem to be in reasonable agreement with experiment for temperatures up to about threequarters of the melting temperature. However, for the higher temperatures, the results are less than satisfactory. For Xe and Kr, the thermodynamic properties calculated from the A2 equation of state with the Morse potential, are qualitatively similar to the A 2 results obtained with the Lennard-Jones potential, however, the properties obtained from the A4 equation of state are in good agreement with experiment, since the contribution from the A4 terms seem to be small. The lattice contribution to the thermal properties of the fcc metals was calculated from the A4 equation of state, and these results produced a slight improvement over the properties calculated from the A2 equation of state. In order to compare the calculated specific heats and bulk moduli results with experiment~ the electronic contribution to thermal properties was taken into account~ by using the free electron model. We found that the results varied significantly with the value chosen for the number of free electrons per atom.

Modified statistical methods to calculate rare gas interaction potentials

New density functionals representing the exchange and correlation energies (per electron) are employed, based on the electron gas model, to calculate interaction potentials of noble gas systems X2 and XY, where X (and Y) are He,Ne,Ar and Kr, and of hydrogen atomrare gas systems H-X. The exchange energy density functional is that recommended by Handler and the correlation energy density functional is a rational function involving two parameters which were optimized to reproduce the correlation energy of He atom. Application of the two parameter function to other rare gas atoms shows that it is "universal"; i. e. ,accurate for the systems considered. The potentials obtained in this work compare well with recent experimental results and are a significant improvement over those from competing statistical modelS.

Molecular dynamics calculation of mean square displacement in alkali metals and rare gas solids and comparison with lattice dynamics

Molec ul ar dynamics calculations of the mean sq ua re displacement have been carried out for the alkali metals Na, K and Cs and for an fcc nearest neighbour Lennard-Jones model applicable to rare gas solids. The computations for the alkalis were done for several temperatures for temperature vol ume a swell as for the the ze r 0 pressure ze ro zero pressure volume corresponding to each temperature. In the fcc case, results were obtained for a wide range of both the temperature and density. Lattice dynamics calculations of the harmonic and the lowe s t order anharmonic (cubic and quartic) contributions to the mean square displacement were performed for the same potential models as in the molecular dynamics calculations. The Brillouin zone sums arising in the harmonic and the quartic terms were computed for very large numbers of points in q-space, and were extrapolated to obtain results ful converged with respect to the number of points in the Brillouin zone.An excellent agreement between the lattice dynamics results was observed molecular dynamics and in the case of all the alkali metals, e~ept for the zero pressure case of CSt where the difference is about 15 % near the melting temperature. It was concluded that for the alkalis, the lowest order perturbation theory works well even at temperat ures close to the melting temperat ure. For the fcc nearest neighbour model it was found that the number of particles (256) used for the molecular dynamics calculations, produces a result which is somewhere between 10 and 20 % smaller than the value converged with respect to the number of particles. However, the general temperature dependence of the mean square displacement is the same in molecular dynamics and lattice dynamics for all temperatures at the highest densities examined, while at higher volumes and high temperatures the results diverge. This indicates the importance of the higher order (eg. ~* ) perturbation theory contributions in these cases.

Exploring Chinese-Canadians' perspectives on health : a quantitative study

Chinese have unique perspectives on health and illness, which is mostly umecognized by western medicine. Immigration may contribute to problems with health consultations, inconvenience, and dissatisfaction. As the largest visible minority in Canada, Chinese- Canadians' perspectives on health should be studied in order to help Chinese immigrants adapt to a new health-care and health-promotion system, and keep them healthy. A quantitative questionnaire was designed based on the findings from a pilot study and previous literature. A hundred participants were recruited from Toronto, Vancouver, Halifax, and St. Catharines. Descriptive analysis and correlation analysis were used to investigate the structure of the variables. Findings indicated that most oftheir attitudes and corresponding practices to the different health aspects were positive. The relation between dietary practices and attitude was only found in small cities. Their attitudes were impacted by their length of stay in Canada. Their attitudes to regularly timed meals and psychological consultation were related to their acculturation level, as was the regularity of their practice of dental flossing. Their self-evaluated general health levels were also found to be affected by their medical history, education level, feeling to talk about • sexual health, and smoking, particularly in the male subjects of the study. In conclusion, they realized that each health aspect w~s important to their health. However, their practices did not bear a strong relation to their beliefs. Traditional thoughts about health reseeded with time. Acculturation level did not affect most of their attitudes or practices. Under pressure, the priority of the daily health practices decreased. Older persons, those with low incomes, lower education levels or families under stress need to pay more attention to their health level. In-depth future research was recommended.

Living between two cultures : personality and adaptation in Chinese immigrant youth /

The aim of the present study was to examine the relationship between shyness and acculturation modes of Chinese immigrant youth in Canada and whether shyness moderates the relationship between acculturation and adaptation. In addition, I examined whether shyness, in conjunction with sociability, moderates the relationship between acculturation and adaptation. Ninety-nine young Chinese immigrants (42 men), ranging in age from 16 to 26 years old, completed a questionnaire that assessed their demographic information, acculturation modes, shyness, sociability, psychological adaptation Oife satisfaction, self-esteem, and depression), and socio-cultural adaptation. Results showed that Chinese orientation was significantly and negatively correlated with age, generation status, English proficiency, and length of residence in Canada. In contrast, Canadian orientation was significantly and positively correlated with generation status, English proficiency, and length of residence in Canada. Canadian orientation was also significantly and negatively correlated with shyness and positively correlated with sociability and psychological and socio-cultural adaptation. Participants who were shyer were more likely to have poorer psychological and socio-cultural adaptation, and to report lower life satisfaction and self-esteem and higher depression. Results from hierarchical multiple regression analyses indicated that Chinese immigrant youth who were separated had higher scores on shyness than those who were integrated and assimilated. There were no significant differences in shyness between youth who were separated and youth who were marginalized, nor were there differences between youth who were integrated and those who were assimilated. Furthermore, integrated Chinese youth reported significantly higher scores in sociability than those who were separated and marginalized but not significantly higher than those who were assimilated.' Shyness did not moderate the relationship between acculturation modes and psychological and socio-cultural adaptation. Unfortunately, the hypothesis to examine if shyness, in combination with sociability, moderated the relationship between acculturation and psychological adaptation could not be tested in the present study because of limitations in cell sizes. The findings suggested that how Chinese immigrant youth acculturate in the receiving country might not be the crucial factor in determining their adaptation. Instead, other factors, such as personality characteristics and nature of the acculturating group, may playa more crucial role. Shyness may have important ramifications for the acculturation and adaptation of young Chinese immigrants to a new society.

Sex Talk: A Multiple Case Study to Explore and Understand Parent-Child Sexual Health Communication in Chinese Immigrant Families

Parent-child sexual health communication can be beneficial. Many factors affect such communication in Chinese immigrant families. This qualitative study explored the influences of acculturation, parenting, and parental participation in the Raising Sexually Healthy Children Program (RSHC) on such communication. With a hermeneutic framework, the purpose was to develop understanding based on the topic, context, and researcher interpretations. Twelve interviews elicited data from six parent-child dyads, three from the RSHC. Analysis involved coding processes; data were compared repeatedly and organized into themes. Perceived personality differences between generations were confounded with cultural communicative differences. Parents used implicitness observed in Chinese culture to establish "open" communication; children expected explicitness observed in Western culture. Post- RSHC, parents perceived themselves as more open to talking about sex; children did not perceive such parental changes. Future research should include joint interviews and longitudinal program evaluation. Future practice should focus on cross-cultural communication and involving children in RSHC.

Integrating Media Education Into the Curriculum: What Chinese Educators Can Learn from Ontario Education

This study sought to determine if and how the Ontario approach to integrating media education into the curriculum can be applied to Chinese education. The study used thematic analyses to identify the Ontario curriculum‘s attributes and approach to teaching media literacy, and to investigate relevant policies and national curriculum standards in Chinese compulsory education to reveal the status quo of Chinese media education. Finally, the study explored the feasibility of applying the Ontario media education model in China. Findings indicate that the Ontario model can be employed in the Chinese context, but only partly so, because current Chinese media education is limited by protectionism and restrictive policies corresponding to the use of media merely as research tools.

Autonomy and Relatedness in Mainland Chinese Adolescents: Social or Personal? Accommodation or Distinctiveness?

Three studies comprised the current research program, in which the major goals were to propose and validate empirically the proposed two-level (universal and culture-specific) model of both autonomy and relatedness, as well as to develop reliable and valid measures for these two constructs. In Study 1, 143 mainland Chinese adolescents were asked open-ended questions about their understanding of autonomy and relatedness in three social contexts (peer, family, school). Chinese youth’s responses captured universal and culturally distinctive forms of autonomy (personal vs. social) and relatedness (accommodation vs. distinctiveness), according to a priori criteria based on the theoretical frameworks. Also, scenarios designed to reflect culture-specific forms of autonomy and relatedness suggested their relevance to Chinese adolescents. With a second sample of 201 mainland Chinese youth, in Study 2, the obtained autonomy and relatedness descriptors were formulated into scale items. Those items were subject to refinement analyses to examine their psychometric properties and centrality to Chinese youth. The findings of Study 1 scenarios were replicated in Study 2. The primary goal of Study 3 was to test empirically the proposed two-level (universal and culture-specific) models of both autonomy and relatedness, using the measures derived from Studies 1 and 2. A third sample of 465 mainland Chinese youth completed a questionnaire booklet consisting of autonomy and relatedness scales and scenarios and achievement motivation orientations measures. A series of confirmatory factor analysis (CFA) autonomy and relatedness measurement models (first-order and second-order), as well as structural models linking culture-specific forms of autonomy and relatedness and achievement motivation orientations, were conducted. The first-order measurement models based on scale and scenario scores consistently confirmed the distinction between personal autonomy and social autonomy, and that of accommodation and distinctiveness. Although the construct validity of the two culture-specific forms of autonomy gained additional support from the structural models, the associations between the two culture-specific forms of relatedness and achievement motivation orientations were relatively weak. In general, the two-level models of autonomy and relatedness were supported in two ways: conceptual analysis of scale items and second-order measurement models. In addition, across the three studies, I explored potential contextual and sex differences in Chinese youth’s endorsement of the diverse forms of autonomy and relatedness. Overall, no substantial contextual variability or sex differences were found. The current research makes an important theoretical contribution to the field of developmental psychology in general, and autonomy and relatedness in particular, by proposing and testing empirically both universal and culture-specific parts of autonomy and relatedness. The current findings have implications for the measurement of autonomy and relatedness across social contexts, as well as for socialization and education practice.

Receipt from Burrill, McEwen and Co. for Chinese clock

Receipt from Burrill, McEwen and Co. for Chinese clock, Oct. 12, 1876.

The association between maternity insurance, residence status and selected perinatal outcomes among Chinese women

Objective: To investigate the impact of maternity insurance and maternal residence on birth outcomes in a Chinese population. Methods: Secondary data was analyzed from a perinatal cohort study conducted in the Beichen District of the city of Tianjin, China. A total of 2364 pregnant women participated in this study at approximately 12-week gestation upon registration for receiving prenatal care services. After accounting for missing information for relevant variables, a total of 2309 women with single birth were included in this analysis. Results: A total of 1190 (51.5%) women reported having maternity insurance, and 629 (27.2%) were rural residents. The abnormal birth outcomes were small for gestational age (SGA, n=217 (9.4%)), large for gestational age (LGA, n=248 (10.7%)), birth defect (n=48 (2.1%)) including congenital heart defect (n=32 (1.4%)). In urban areas, having maternal insurance increased the odds of SGA infants (1.32, 95%CI (0.85, 2.04), NS), but decreased the odds of LGA infants (0.92, 95%CI (0.62, 1.36), NS); also decreased the odds of birth defect (0.93, 95%CI (0.37, 2.33), NS), and congenital heart defect (0.65, 95%CI (0.21, 1.99), NS) after adjustment for covariates. In contrast to urban areas, having maternal insurance in rural areas reduced the odds of SGA infants (0.60, 95%CI (0.13, 2.73), NS); but increased the odds of LGA infants (2.16, 95%CI (0.92, 5.04), NS), birth defects (2.48, 95% CI (0.70, 8.80), NS), and congenital heart defect (2.18, 95%CI (0.48, 10.00), NS) after adjustment for the same covariates. Similar results were obtained from Bootstrap methods except that the odds ratio of LGA infants in rural areas for maternal insurance was significant (95%CI (1.13, 4.37)); urban residence was significantly related with lower odds of birth defect (95%CI (0.23, 0.89)) and congenital heart defect (95%CI (0.19, 0.91)). Conclusions: whether having maternal insurance did have an impact on perinatal outcomes, but the impact of maternal insurance on the perinatal outcomes showed differently between women with urban residence and women with rural residence status. However, it is not clear what are the reason causing the observed differences. Thus, more studies are needed.