46,706 research outputs found
Topological Anderson Insulator
Disorder plays an important role in two dimensions, and is responsible for
striking phenomena such as metal insulator transition and the integral and
fractional quantum Hall effects. In this paper, we investigate the role of
disorder in the context of the recently discovered topological insulator, which
possesses a pair of helical edge states with opposing spins moving in opposite
directions and exhibits the phenomenon of quantum spin Hall effect. We predict
an unexpected and nontrivial quantum phase termed "topological Anderson
insulator," which is obtained by introducing impurities in a two-dimensional
metal; here disorder not only causes metal insulator transition, as
anticipated, but is fundamentally responsible for creating extended edge
states. We determine the phase diagram of the topological Anderson insulator
and outline its experimental consequences.Comment: 4 pages, 4 figure
Effect of stoichiometry on oxygen incorporation in MgB2 thin films
The amount of oxygen incorporated into MgB2 thin films upon exposure to
atmospheric gasses is found to depend strongly on the material's stoichiometry.
Rutherford backscattering spectroscopy was used to monitor changes in oxygen
incorporation resulting from exposure to: (a) ambient atmosphere, (b) humid
atmospheres, (c) anneals in air and (d) anneals in oxygen. The study
investigated thin-film samples with compositions that were systematically
varied from Mg0.9B2 to Mg1.1B2. A significant surface oxygen contamination was
observed in all of these films. The oxygen content in the bulk of the film, on
the other hand, increased significantly only in Mg rich films and in films
exposed to humid atmospheres.Comment: 10 pages, 6 figures, 1 tabl
Complete relativistic equation of state for neutron stars
We construct the equation of state (EOS) in a wide density range for neutron
stars using the relativistic mean field theory. The properties of neutron star
matter with both uniform and non-uniform distributions are studied
consistently. The inclusion of hyperons considerably softens the EOS at high
densities. The Thomas-Fermi approximation is used to describe the non-uniform
matter, which is composed of a lattice of heavy nuclei. The phase transition
from uniform matter to non-uniform matter occurs around ,
and the free neutrons drip out of nuclei at about $2.4 \times 10^{-4}\
\rm{fm^{-3}}$. We apply the resulting EOS to investigate the neutron star
properties such as maximum mass and composition of neutron stars.Comment: 23 pages, REVTeX, 9 ps figures, to appear in Phys. Rev.
Rhabdomyosarcoma: Advances in Molecular and Cellular Biology.
Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in childhood and adolescence. The two major histological subtypes of RMS are alveolar RMS, driven by the fusion protein PAX3-FKHR or PAX7-FKHR, and embryonic RMS, which is usually genetically heterogeneous. The prognosis of RMS has improved in the past several decades due to multidisciplinary care. However, in recent years, the treatment of patients with metastatic or refractory RMS has reached a plateau. Thus, to improve the survival rate of RMS patients and their overall well-being, further understanding of the molecular and cellular biology of RMS and identification of novel therapeutic targets are imperative. In this review, we describe the most recent discoveries in the molecular and cellular biology of RMS, including alterations in oncogenic pathways, miRNA (miR), in vivo models, stem cells, and important signal transduction cascades implicated in the development and progression of RMS. Furthermore, we discuss novel potential targeted therapies that may improve the current treatment of RMS
Anti-correlation and subsector structure in financial systems
With the random matrix theory, we study the spatial structure of the Chinese
stock market, American stock market and global market indices. After taking
into account the signs of the components in the eigenvectors of the
cross-correlation matrix, we detect the subsector structure of the financial
systems. The positive and negative subsectors are anti-correlated each other in
the corresponding eigenmode. The subsector structure is strong in the Chinese
stock market, while somewhat weaker in the American stock market and global
market indices. Characteristics of the subsector structures in different
markets are revealed.Comment: 6 pages, 2 figures, 4 table
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