297 research outputs found
Putting the Democracy in Democracy and Distrust: The Coherentist Case for Representation Reinforcement
A Search for Fluctuation-Dissipation Theorem Violations in Spin-Glasses from Susceptibility Data
We propose an indirect way of studying the fluctuation-dissipation relation
in spin-glasses that only uses available susceptibility data. It is based on a
dynamic extension of the Parisi-Toulouse approximation and a Curie-Weiss
treatment of the average magnetic couplings. We present the results of the
analysis of several sets of experimental data obtained from various samples.Comment: 7 pages, 4 figure
Reconstructing World Politics: Norms, Discourse, and Community
This Article argues that the conventional (rationalist) approach to world politics characterized by political bargain cannot fully capture the new social reality under the contemporary global ambience where ideational factors such as ideas, values, culture, and norms have become more salient and influential not only in explaining but also in prescribing state behaviors. After bringing rationalismâs paradigmatic limitations into relief, the Article offers a sociological framework that highlights a reflective, intersubjective communication among states and consequent norm-building process. Under this new paradigm, one can understand an international organization as a âcommunityâ (Gemeinschaft), not as a mere contractual instrument of its contracting parties (Gesellschaft). The Article applies the new paradigm to the World Trade Organization (WTO) as it describes the WTOâs institutional evolution from a power-oriented, tariff-reducing contract to a norm-oriented world trade community
Response properties in a model for granular matter
We investigate the response properties of granular media in the framework of
the so-called {\em Random Tetris Model}. We monitor, for different driving
procedures, several quantities: the evolution of the density and of the density
profiles, the ageing properties through the two-times correlation functions and
the two-times mean-square distance between the potential energies, the response
function defined in terms of the difference in the potential energies of two
replica driven in two slightly different ways. We focus in particular on the
role played by the spatial inhomogeneities (structures) spontaneously emerging
during the compaction process, the history of the sample and the driving
procedure. It turns out that none of these ingredients can be neglected for the
correct interpretation of the experimental or numerical data. We discuss the
problem of the optimization of the compaction process and we comment on the
validity of our results for the description of granular materials in a
thermodynamic framework.Comment: 22 pages, 35 eps files (21 figures
Real-time electron nanoscopy of photovoltaic absorber formation from kesterite nanoparticles
Cu2ZnSnS4 nanocrystals are annealed in a Se-rich atmosphere inside a transmission electron microscope. During the heating phase, a complete S-Se exchange reaction occurs while the cation sublattice and morphology of the nanocrystals are preserved. At the annealing temperature, growth of large Cu2ZnSnSe4 grains with increased cation ordering is observed in real-time. Thisyields an annealing protocol which is transferred to an industrially-similar solar cell fabrication process resulting in a 33% increase in the device open circuit voltage. The approach can be applied to improve the performance of any photovoltaic technology that requires annealing because of the criticality of the process step
Understanding the role of crystallographic shear on the electrochemical behavior of niobium oxyfluorides
The effects of shear planes in perovskite materials have been studied in order to identify their role in the electrochemical behavior of Liâș intercalation hosts. These planes modulate the structural stability and ionic transport pathways and therefore play an intimate role in the characteristics and performance of shear compounds. Herein, two Nb-based compounds, NbOâF and NbâOâF, were chosen as representative perovskite and shear derivatives respectively to investigate the role of crystallographic shear. A series of operando measurements, including X-ray diffraction and X-ray absorption spectroscopy, in conjunction with structural analysis, Raman spectroscopy, and detailed electrochemical studies identified the effect of shear planes. It was found that shear planes led to increased structural stability during Liâș (de)intercalation with shear layers being maintained, while perovskite layers were seen to degrade rapidly. However, disordering in the shear plane stacking introduced during delithiation ultimately led to poor capacity retention despite structural maintenance as Liâș diffusion channels are disrupted
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