The stability of nanoscale devices is directly related to elasticity and the effect of temperature on the elasticity of thin films and nanocrystals. The elastic instability induced by rising temperature will cause the failure of integrated circuits and other microelectronic devices in service. The temperature effect on the elastic modulus of thin films and nanocrystals is unclear although the temperature dependence of the modulus of bulk materials has been studied for over half a century. In this paper, a theoretical model (...) of the temperature-dependent elastic modulus of thin films and nanocrystals is developed based on the physical definition of the modulus by considering the size effect of the related cohesive energy and the thermal expansion coefficient. Moreover, the temperature effect on the modulus of Cu thin films is simulated by the molecular dynamics method. The results indicate that the elastic modulus decreases with increasing temperature and the rate of the modulus decrease increases with reducing thickness of thin films. The theoretical predictions based on the model are consistent with the results of computational simulations, semi-continuum calculations and the experimental measurements for Cu, Si thin films and Pd nanocrystals. (shrink)
A major controversy in the study of the "Analects" has been over the relation between two central concepts, ren (humanity, human excellence) and li (rites, rituals of propriety). Confucius seems to have said inconsistent things about this relation. Some passages appear to suggest that ren is more fundamental than li, while others seem to imply the contrary. It is therefore not surprising that there have been different interpretations and characterizations of this relation. Using the analogy of language grammar and mastery (...) of a language, it is proposed here that we should understand li as a cultural grammar and ren as the mastery of a culture. In this account, society cultivates its members through li toward the goal of ren, and persons of ren manifest their human excellence through their practice of li. (shrink)
Model RB is a model of random constraint satisfaction problems, which exhibits exact satisfiability phase transition and many hard instances, both experimentally and theoretically. Benchmarks based on Model RB have been successfully used by various international algorithm competitions and many research papers. In a previous work, Xu and Li defined two notions called i-constraint assignment tuple and flawed i-constraint assignment tuple to show an exponential resolution complexity of Model RB. These two notions are similar to some kind of consistency in (...) constraint satisfaction problems, but seem different from all kinds of consistency so far known in literatures. In this paper, we explicitly define this kind of consistency, called variable-centered consistency, and show an upper bound on a parameter in Model RB, such that up to this bound the typical instances of Model RB are variable-centered consistent. (shrink)
Adherence to ethical principles in clinical research and practice is becoming topical issue in China, where the prevalence of mental illness is rising, but treatment facilities remain underdeveloped. This paper reports on a study aiming to understand the ethical knowledge and attitudes of Chinese mental health professionals in relation to the process of diagnosis and treatment, informed consent, and privacy protection in clinical trials.