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The main purpose of this work is to demonstrate that bursting oscillations not only occur in slow-fast systems, which have been presented in many publications, but also may take place in periodic excited systems with order gap between the excited frequency and natural frequency. Furthermore, a typical procedure to analyze the bifurcation mechanism of the bursting oscillations in periodic excited dynamical systems is presented, in which the conceptions of generalized autonomous system (GAS) and transformed phase portrait are introduced. For the periodic external excited dynamo oscillator, different types of bursting phenomena can be obtained, the mechanism of which is presented based on the bifurcation analysis of the corresponding GAS. From the evolution of the dynamics with the variation of the parameters, it is found that different forms of bifurcations, occurring at the transitions between the quiescent state and spiking state, may cause different patterns of bursting oscillations. [ABSTRACT FROM AUTHOR]

Semisolid rheoforming (SSR) is a promising technology for the production of Mg wrought alloy in foundry settings. In order to realize SSR, it is necessary to characterize the grain structure evolution during slurry preparation. In this paper, slurry of AZ31 alloy was produced by a novel rheocast process known as self-inoculation method (SIM). Interrupted quenching technology was applied to investigate the primary a-Mg evolution during continuous cooling and isothermal holding. Results indicate that the initial microstructure of slurry produced by SIM is a mixture of irregular grains, which becomes ideally globular when the slurry slowly cools to 620 °C and isothermally held for at least 30 s. The local solute diffusion leads to dendritic fragmentation and forms separated particles. During prolonged holding, the particle surface gradually becomes smooth because of protuberance melting and groove advancement. Coarsening of a-Mg grains in isothermal holding was analyzed using Lifshitz-Slyozov-Wagner theory. Results suggest that coalescence is most likely the dominant coarsening mechanism in the early stage while Ostwald ripening tends to be the principal one later. The EDS results indicate that a longer holding time leads to Al solute element segregation at the grain boundaries, but Zn distribution within liquid matrix has no obvious change. [ABSTRACT FROM AUTHOR]

Performance metrics and evaluation criteria are used to develop a novel taxonomy that classifies barrier mechanisms into categories ranging from simple Static-Binding Idle-Tasking methods to robust Dynamic-Binding Any-Tasking methods. Such capabilities include support for multiple barriers, reconfigurable and reusable synchronization resources, and provisions for dynamic process binding. Based on these features, the existing software-based approaches, dedicated-hardware mechanisms, and hybrid hardware/software techniques for synchronization are assessed in order of increasing complexity. Any barrier synchronization algorithm can be readily classified using this taxonomy to understand resource requirements and performance tradeoffs. [ABSTRACT FROM AUTHOR]

Cultured pig aortic smooth muscle cells maintain a viable, quiescent state in a chemically defined medium that contains 10 M insulin, 5 µg/ml transferrin, and 0.2 m M ascorbate. DNA synthesis and DNA content were determined by measuring tritiated thymidine incorporation and DNA-binding to the fluorescent probe 4′,6-diamidino-2-phenylindole, respectively. The majority of the population of cells in defined medium cultures were diploid. Tritiated thymidine uptake in cells in defined medium was one-tenth that observed in cells in fetal bovine serum-containing medium. The study of cellular cyclic AMP level in response to extracellular adenosine stimulation in dividing cells and quiescent cells showed that cells in defined medium had a lower extent of response to adenosine compared to cells cultured in serum-containing medium. Both the cell growth index and the response to adenosine of cells cultured in defined medium were reversible after replacing the medium with 10% fetal bovine serum-containing medium, which suggests that the cells in defined medium were healthy and were capable of modulating cellular metabolism depending on culture conditions. [ABSTRACT FROM AUTHOR]