478 research outputs found
The contested rescaling of economic governance in East Asia: a special issue
The special issue this article opens engages with an apparent conundrum that has often puzzled observers of East Asian politicsâwhy, despite the region's considerable economic integration, multilateral economic governance institutions remain largely underdeveloped. The authors argue that this âregionalism problĂ©matiqueâ has led to the neglect of prior and more important questions pertaining to how patterns of economic governance, beyond the national scale, are emerging in East Asia and why. In this special issue, the contributors shift analytic focus onto social and political struggles over the scale and instruments of economic governance in East Asia. The contributions identify and explain the emergence of a wide variety of regional modes of economic governance often neglected by the scholarship or erroneously viewed as stepping stones towards âdeeperâ multilateralism
Toward detailed prominence seismology - II. Charting the continuous magnetohydrodynamic spectrum
Starting from accurate MHD flux rope equilibria containing prominence
condensations, we initiate a systematic survey of their linear
eigenoscillations. To quantify the full spectrum of linear MHD eigenmodes, we
require knowledge of all flux-surface localized modes, charting out the
continuous parts of the MHD spectrum. We combine analytical and numerical
findings for the continuous spectrum for realistic prominence configurations.
The equations governing all eigenmodes for translationally symmetric,
gravitating equilibria containing an axial shear flow, are analyzed, along with
their flux-surface localized limit. The analysis is valid for general 2.5D
equilibria, where either density, entropy, or temperature vary from one flux
surface to another. We analyze the mode couplings caused by the poloidal
variation in the flux rope equilibria, by performing a small gravity parameter
expansion. We contrast the analytical results with continuous spectra obtained
numerically. For equilibria where the density is a flux function, we show that
continuum modes can be overstable, and we present the stability criterion for
these convective continuum instabilities. Furthermore, for all equilibria, a
four-mode coupling scheme between an Alfvenic mode of poloidal mode number m
and three neighboring (m-1, m, m+1) slow modes is identified, occurring in the
vicinity of rational flux surfaces. For realistically prominence equilibria,
this coupling is shown to play an important role, from weak to stronger gravity
parameter g values. The analytic predictions for small g are compared with
numerical spectra, and progressive deviations for larger g are identified. The
unstable continuum modes could be relevant for short-lived prominence
configurations. The gaps created by poloidal mode coupling in the continuous
spectrum need further analysis, as they form preferred frequency ranges for
global eigenoscillations.Comment: Accepted by Astronmy & Astrophysics, 21 pages, 15 figure
Rising Powers and State Transformation: The Case of China
Abstract This paper explores how the transformation of contemporary statehood is conditioning the "rise" of emerging powers, in terms of their internal policy formation and execution, and in terms of how their policies spur transformations of statehood beyond their borders. Many accounts of rising powers assume a timeless logic of rising and falling states. Comparisons drawn between Bismarck's Germany and today's China suggest these states are functionally identical and will thus behave similarly. This overlooks radical transformations in the nature of statehood since the nineteenth century, notably the emergence of regulatory states, decentralisation and multilevel and transnational modes of governance. We explore how these changes are conditioning the "rise" of China. Internal transformation leads to multiagency, multilevel contestation over policy, resulting in incoherent and externally provocative behaviour that is often misinterpreted as "Chinese aggression". Meanwhile, powerful forces within the Chinese state are increasingly promoting the transformation of other states in order to secure their transnational interests, notably in neighbouring areas of Asia
State Transformation and Chinaâs Engagement in Global Governance:The Case of Nuclear Technologies
Debates over the implications of Chinaâs rise for global governance have reached an impasse, since evidence exists to support both ârevisionistâ and âstatus-quoâ intentions. This means that neither is strictly falsifiable and hence the debate, as currently structured, is irresolvable. However, contradictions are explicable if we recognise that China is not a unitary state. Since the beginning of the reform era, its international engagements have been shaped by the uneven transformation â fragmentation, decentralisation and internationalisation â of state apparatuses. Contradictory international actions thus may reflect not top-down strategic direction, but conflicts, disagreements and coordination problems within Chinaâs transformed party-state. Our state transformation approach directs us away from evaluating Chinaâs approach to global governance in toto â whether it is overall a revisionist or status quo power â towards a detailed analysis of particular policy domains. This is because in each issue-area we find different constellations of actors and interests, and varying degrees of party-state transformation. We demonstrate the centrality of state transformation analysis for explaining the co-existence of revisionist and status quo behaviours through the apparently hard test case of nuclear technologies. Even in this âhigh politicsâ domain, state transformation dynamics help explain Chinaâs inconsistent international behaviours
Toward detailed prominence seismology - I. Computing accurate 2.5D magnetohydrodynamic equilibria
Context. Prominence seismology exploits our knowledge of the linear
eigenoscillations for representative magnetohydro- dynamic models of filaments.
To date, highly idealized models for prominences have been used, especially
with respect to the overall magnetic configurations.
Aims. We initiate a more systematic survey of filament wave modes, where we
consider full multi-dimensional models with twisted magnetic fields
representative of the surrounding magnetic flux rope. This requires the ability
to compute accurate 2.5 dimensional magnetohydrodynamic equilibria that balance
Lorentz forces, gravity, and pressure gradients, while containing density
enhancements (static or in motion).
Methods. The governing extended Grad-Shafranov equation is discussed, along
with an analytic prediction for circular flux ropes for the Shafranov shift of
the central magnetic axis due to gravity. Numerical equilibria are computed
with a finite element-based code, demonstrating fourth order accuracy on an
explicitly known, non-trivial test case.
Results. The code is then used to construct more realistic prominence
equilibria, for all three possible choices of a free flux-function. We quantify
the influence of gravity, and generate cool condensations in hot cavities, as
well as multi- layered prominences.
Conclusions. The internal flux rope equilibria computed here have the
prerequisite numerical accuracy to allow a yet more advanced analysis of the
complete spectrum of linear magnetohydrodynamic perturbations, as will be
demonstrated in the companion paper.Comment: Accepted by Astronomy & Astrophysics, 15 pages, 15 figure
Magnetic Reynolds number dependence of reconnection rate and flow structure of the self-similar evolution model of fast magnetic reconnection
This paper investigates Magnetic Reynolds number dependence of the
``self-similar evolution model'' (Nitta et al. 2001) of fast magnetic
reconnection. I focused my attention on the flow structure inside and around
the reconnection outflow, which is essential to determine the entire
reconnection system (Nitta et al. 2002). The outflow is consist of several
regions divided by discontinuities, e.g., shocks, and it can be treated by a
shock-tube approximation (Nitta 2004). By solving the junction conditions
(e.g., Rankine-Hugoniot condition), the structure of the reconnection outflow
is obtained. Magnetic reconnection in most astrophysical problems is
characterized by a huge dynamic range of its expansion ( for typical
solar flares) in a free space which is free from any influence of external
circumstances. Such evolution results in a spontaneous self-similar expansion
which is controlled by two intrinsic parameters: the plasma- and the
magnetic Reynolds number. The plasma- dependence had been investigated in
our previous paper. This paper newly clarifies the relation between the
reconnection rate and the inflow structure just outside the Petschek-like slow
shock: As the magnetic Reynolds number increases, strongly converging inflow
toward the Petschek-like slow shock forms, and it significantly reduces the
reconnection rate.Comment: 16 pages. to appear in ApJ (2006 Jan. 20 issue
Novel Hybrid Electrode Using Transparent Conductive Oxide and Silver Nanoparticle Mesh for Silicon Solar Cell Applications
AbstractTransparent conductive oxides (TCOs) have been widely used as the front electrodes for various solar cell structures, including heterojunction silicon wafer solar cells and the vast majority of thin-film solar cells. For heterojunction silicon wafer solar cells, the front TCO layer not only serves as a top electrode (by enhancing the lateral conductance of the underlying amorphous silicon film), but also as an antireflection coating. These requirements make it difficult to simultaneously achieve excellent conductivity and transparency, and thus only high-quality indium tin oxide (ITO) has as yet found its way into industrial heterojunction silicon wafer solar cells. For thin-film solar cells, in order to provide efficient lateral conductance of the charge carriers, normally a TCO layer of a few hundred nanometers thickness is used which impedes the optical transparency due to the enhanced free carrier absorption. To reduce the conflict between conductivity and transparency, and to separately engineer the electrical and optical properties, a hybrid electrode is proposed and fabricated by us which consists of a TCO layer (optical layer) and a silver nanoparticle mesh (electrical layer). This hybrid electrode is demonstrated to have a 10 times higher lateral conductance compared to a single TCO layer, while maintaining high light transmission in a wide wavelength range. Due to the excellent performance of the hybrid electrode, it is demonstrated that such an electrode is suitable for various solar cell structures
- âŠ