Glass-Like Heat Conduction in High-Mobility Crystalline Semiconductors

The thermal conductivity of polycrystalline semiconductors with type-I clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr and/or Eu) exhibit lattice thermal conductivities typical of amorphous materials. Remarkably, this behavior occurs in spite of the well-defined crystalline structure and relatively high electron mobility ($\sim 100 cm^2/Vs$). The dynamics of dopant ions and their interaction with the polyhedral cages of the structure are a likely source of the strong phonon scattering.Comment: 4 pages, 3 postscript figures, to be published, Phys. Rev. Let

Hopf-type intermediate-scale bifurcation in single-stage power-factor-correction power supplies

Author name used in this publication: Chi K. TseRefereed conference paper2006-2007 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Slow-scale instability of single-stage power-factor-correction power supplies

Author name used in this publication: Chi K. Tse2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Doming Modes and Dynamics of Model Heme Compounds

Synchrotron far-IR spectroscopy and density-functional calculations are used to characterize the low-frequency dynamics of model heme FeCO compounds. The “doming” vibrational mode in which the iron atom moves out of the porphyrin plane while the periphery of this ring moves in the opposite direction determines the reactivity of oxygen with this type of molecule in biological systems. Calculations of frequencies and absorption intensities and the measured pressure dependence of vibrational modes in the model compounds are used to identify the doming and related normal modes

Controlled DNA compaction within chromatin: the tail-bridging effect

We study the mechanism underlying the attraction between nucleosomes, the fundamental packaging units of DNA inside the chromatin complex. We introduce a simple model of the nucleosome, the eight-tail colloid, consisting of a charged sphere with eight oppositely charged, flexible, grafted chains that represent the terminal histone tails. We demonstrate that our complexes are attracted via the formation of chain bridges and that this attraction can be tuned by changing the fraction of charged monomers on the tails. This suggests a physical mechanism of chromatin compaction where the degree of DNA condensation can be controlled via biochemical means, namely the acetylation and deacetylation of lysines in the histone tails.Comment: 4 pages, 5 figures, submitte

Why People Gamble: A Qualitative Study of Four New Zealand Ethnic Groups

In multicultural countries such as New Zealand, it is particularly important that gambling research take into account possible cultural differences. Many New Zealanders come from cultures that do not have a history of gambling, including the Mäori (New Zealand indigenous people), Pacific Islanders, and recent migrants. Little research has examined the reasons why people start and continue to gamble, especially among different ethnic groups. This research project thus aimed to develop a framework to explain how environmental, cultural, and social factors interact with personal attributes to determine gambling behaviors. In a qualitative study, 131 people broadly representative of Mäori, Pacific, Asian, and Päkehä/New Zealand European groups residing in New Zealand were interviewed individually or in focus groups. They included social and problem gamblers, families of problem gamblers, and professionals. Different personal, socioeconomic, environmental, and cultural factors were identified, summarized in a developmental framework, and compared to factors found for ethnic groups in other countries. Public health policy issues were raised, including greater control of gambling promotion. © 2012 The Author(s).published_or_final_versionSpringer Open Choice, 28 May 201

Wireless communication with chaos

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