Comparative Analysis of Non-thermal Emissions and Study of Electron Transport in a Solar Flare

We study the non-thermal emissions in a solar flare occurring on 2003 May 29 by using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This flare shows several typical behaviors of the HXR and microwave emissions: time delay of microwave peaks relative to HXR peaks, loop-top microwave and footpoint HXR sources, and a harder electron energy distribution inferred from the microwave spectrum than from the HXR spectrum. In addition, we found that the time profile of the spectral index of the higher-energy (\gsim 100 keV) HXRs is similar to that of the microwaves, and is delayed from that of the lower-energy (\lsim 100 keV) HXRs. We interpret these observations in terms of an electron transport model called {\TPP}. We numerically solved the spatially-homogeneous {\FP} equation to determine electron evolution in energy and pitch-angle space. By comparing the behaviors of the HXR and microwave emissions predicted by the model with the observations, we discuss the pitch-angle distribution of the electrons injected into the flare site. We found that the observed spectral variations can qualitatively be explained if the injected electrons have a pitch-angle distribution concentrated perpendicular to the magnetic field lines rather than isotropic distribution.Comment: 32 pages, 12 figures, accepted for publication in The Astronomical Journa

Relating cultural change to strategic adaptation: an interpretation of modern Chinese management

Research into Chinese management has investigated foreign direct investment, organisational structures, and the implications of Western management influences on Chinese domestic practices. The recent entry of China into the World Trade Organisation has increased the demand for Western business knowledge by Chinese managers. This thesis extends present research with an investigation of change and adaptation in the national cultural values and strategic decision making of the individual Chinese manager. In particular, it researches the effects at a boundary of British and Chinese cultures, studying Chinese managers working or training in the UK. A national group of managers has distinct decision making and problem solving characteristics. Such characteristics result from tendencies to prefer certain `ways of doing things' over others, identified through national cultural values. At the interface of Western and Chinese national cultures there is unresolved academic debate whether Chinese value systems are diverging, converging or crossverging - moving from, or closer to, the Western `way of doing things' or creating a unique set of Chinese cultural controls. Change in cultural characteristics and associated networks would dynamically reflect in the governing, control system criteria over Chinese strategic decision making. To interpret change in Chinese problem solving criteria, this thesis links Western strategic theory with Chinese cultural characteristics. Relevant research in the Chinese and Western literature is reviewed and the characteristics of Chinese management values identified. An empirical data set on Chinese values and networking (guanxi) provides quantitative and qualitative evidence that adaptation in Chinese management strategy can be interpreted using cross-cultural research techniques and economic concepts. Methodological limitations in cross-cultural research are discussed and a mixed method research approach, and pragmatic research design, is deployed. Chinese management characteristics are mapped with unified Western transaction cost, resource base and real option theories related to economic exchange. This thesis concludes that there is a determinable relationship between Chinese cultural characteristics, strategic decision making and Western economic and strategic theory. An explanatory, relevant and practical schema is theorised from the relationship. Flexible strategic problem solving by modem Chinese management infers an expansion of market governance in a low context, less hierarchical environment whilst retaining high context, guanxi relational governance for complex economic exchange. Strategic adaptation, domestically responsive but also internationally integrative, is reflected through change in the traditional way things are done -a transvergent adaptation

Weiss oscillations in the electronic structure of modulated graphene

We present a theoretical study of the electronic structure of modulated graphene in the presence of a perpendicular magnetic field. The density of states and the bandwidth for the Dirac electrons in this system are determined. The appearance of unusual Weiss oscillations in the bandwidth and density of states is the main focus of this work.Comment: 8 pages, 2 figures, accepted in J. Phys.: Conden. mat

Doing evolution in economic geography

Evolutionary approaches in economic geography face questions about the relationships between their concepts, theories, methods, politics, and policy implications. Amidst the growing but unsettled consensus that evolutionary approaches should employ plural methodologies, the aims here are, first, to identify some of the difficult issues confronting those working with different frameworks. The concerns comprise specifying and connecting research objects, subjects, and levels; handling agency and context; engaging and integrating the quantitative and the qualitative; comparing cases; and, considering politics, policy, and praxis. Second, the purpose is to articulate a distinctive geographical political economy approach, methods, and illustrative examples in addressing these issues. Bringing different views of evolution in economic geography into dialogue and disagreement renders methodological pluralism a means toward improved understanding and explanation rather than an end in itself. Confronting such thorny matters needs to be embedded in our research practices and supported by greater openness; more and better substantiation of our conceptual, theoretical, and empirical claims; enhanced critical reflection; and deeper engagement with politics, policy, and praxis

Temporal evolution of an energetic electron population in an inhomogeneous medium: Application to solar hard X-ray bursts

Energetic electrons accelerated during solar flares can be studied through the hard X-ray emission they produce when interacting with the solar ambient atmosphere. In the case of the non thermal hard X-ray emission, the instanteous X-ray flux emitted at one point of the atmosphere is related to the instantaneous fast electron spectrum at that point. A hard X-ray source model then requires the understanding of the evolution in space and time of the fast particle distribution. The physical processes involved here are energy losses due to Coulomb collisions and pitch angle scattering due to both collisions and magnetic field gradients