71,907 research outputs found
NMR Probing Spin Excitations in the Ring-Like Structure of a Two-Subband System
Resistively detected nuclear magnetic resonance (NMR) is observed inside the
ring-like structure, with a quantized Hall conductance of 6e^2/h, in the phase
diagram of a two subband electron system. The NMR signal persists up to 400 mK
and is absent in other states with the same quantized Hall conductance. The
nuclear spin-lattice relaxation time, T1, is found to decrease rapidly towards
the ring center. These observations are consistent with the assertion of the
ring-like region being a ferromagnetic state that is accompanied by collective
spin excitations.Comment: 4 pages, 4 figure
The unique chemical reactivity of a graphene nanoribbon's zigzag edge
The zigzag edge of a graphene nanoribbon possesses a unique electronic state
that is near the Fermi level and localized at the edge carbon atoms. We
investigate the chemical reactivity of these zigzag edge sites by examining
their reaction energetics with common radicals from first principles. A
"partial radical" concept for the edge carbon atoms is introduced to
characterize their chemical reactivity, and the validity of this concept is
verified by comparing the dissociation energies of edge-radical bonds with
similar bonds in molecules. In addition, the uniqueness of the zigzag-edged
graphene nanoribbon is further demonstrated by comparing it with other forms of
sp2 carbons, including a graphene sheet, nanotubes, and an armchair-edged
graphene nanoribbon.Comment: 24 pages, 9 figure
Phenomenological Implications of Supersymmetric Family Non-universal U(1)-prime Models
We construct a class of anomaly-free supersymmetric U(1)' models that are
characterized by family non-universal U(1)' charges motivated from E_6
embeddings. The family non-universality arises from an interchange of the
standard roles of the two SU(5) 5* representations within the 27 of E_6 for the
third generation. We analyze U(1)' and electroweak symmetry breaking and
present the particle mass spectrum. The models, which include additional Higgs
multiplets and exotic quarks at the TeV scale, result in specific patterns of
flavor-changing neutral currents in the b to s transitions that can accommodate
the presently observed deviations inthis sector from the SM predictions.Comment: 25 pages, 3 figure
Corporate governance and bank performance in China
This paper examines the effects of corporate governance on bank performance in China over the period 1995-2008. Bank performance has improved significantly and the mean profit efficiency level is estimated at 61 per cent. The results suggest that differences in corporate governance have significant impacts on bank performance: banks with majority foreign ownership are most profitable while banks with majority state ownership are most unprofitable. We find no evidence that foreign minority ownership in domestic banks improves performance. Banks with more dispersed ownership are found to be more profit efficient
Bank ownership, privatization, and performance: evidence from a transition country
This paper combines the static effect of ownership and the dynamic effect of privatization on bank performance in China over 1995-2010, reporting a significantly higher performance by private intermediaries – joint stock commercial banks and city commercial banks – relative to state-owned commercial banks. However, publicly traded banks, subject to multiple monitoring and vetting in capital markets, perform better regardless of ownership status. The privatization of banks has improved performance with respect to revenue inflow and efficiency gains in the short- or long-run (initial public offerings). The positive long-run effect is more relevant and significant for banking institutions with minority foreign ownership. Moreover, this paper innovatively estimates interest income efficiency and non-interest income efficiency at the same time. The results suggest that Chinese banks are much more efficient in generating interest income than raising non-interest revenue, although the latter aspect has improved significantly during the sample period
- …