4,103 research outputs found
Competing states for the fractional quantum Hall effect in the 1/3-filled second Landau level
In this work, we investigate the nature of the fractional quantum Hall state
in the 1/3-filled second Landau level (SLL) at filling factor (and
8/3 in the presence of the particle-hole symmetry) via exact diagonalization in
both torus and spherical geometries. Specifically, we compute the overlap
between the exact 7/3 ground state and various competing states including (i)
the Laughlin state, (ii) the fermionic Haffnian state, (iii) the
antisymmetrized product state of two composite fermion seas at 1/6 filling, and
(iv) the particle-hole (PH) conjugate of the parafermion state. All these
trial states are constructed according to a guiding principle called the
bilayer mapping approach, where a trial state is obtained as the
antisymmetrized projection of a bilayer quantum Hall state with interlayer
distance as a variational parameter. Under the proper understanding of the
ground-state degeneracy in the torus geometry, the parafermion state can
be obtained as the antisymmetrized projection of the Halperin (330) state.
Similarly, it is proved in this work that the fermionic Haffnian state can be
obtained as the antisymmetrized projection of the Halperin (551) state. It is
shown that, while extremely accurate at sufficiently large positive Haldane
pseudopotential variation , the Laughlin state loses its
overlap with the exact 7/3 ground state significantly at . At slightly negative , it is shown that the
PH-conjugated parafermion state has a substantial overlap with the exact
7/3 ground state, which is the highest among the above four trial states.Comment: 22 pages, 5 figure
Notes on word order variation in Korean
This article aims to develop an analysis of scrambling or word order variation in Korean from a pragmatic/cognitive perspective. Although extensive research has been carried out on this issue, most extant research attempts to provide analyses of the phenomenon by identifying grammatical features posited for syntactic operations. Unlike the previous research, we demonstrate that word order variation needs to be understood with respect to its communicative function; it is motivated by the speaker’s intention to convey information more effectively. It is emphasized that understanding the association between information structure and word order variation should be an essential task for the analysis of the latter phenomenon. We further discuss five conversational strategies that motivate non-canonical word orders, which include juxtaposition, backmasking, right dislocation, add-on, and floated quantifier strategies
Theory of magnetic field-induced metaelectric critical end point in BiMnO
A recent experiment on the multiferroic BiMnO compound under a strong
applied magnetic field revealed a rich phase diagram driven by the coupling of
magnetic and charge (dipolar) degrees of freedom. Based on the
exchange-striction mechanism, we propose here a theoretical model with the
intent to capture the interplay of the spin and dipolar moments in the presence
of a magnetic field in BiMnO. Experimentally observed behavior of the
dielectric constants, magnetic susceptibility, and the polarization is, for the
most part, reproduced by our model. The critical behavior observed near the
polarization reversal point in the phase diagram is interpreted as
arising from the proximity to the critical end point.Comment: Theory; relevant experiment uploaded as arXiv:0810.190
BH3-only Protein Noxa Is a Mediator of Hypoxic Cell Death Induced by Hypoxia-inducible Factor 1α
Hypoxia is a common cause of cell death and is implicated in many disease processes including stroke and chronic degenerative disorders. In response to hypoxia, cells express a variety of genes, which allow adaptation to altered metabolic demands, decreased oxygen demands, and the removal of irreversibly damaged cells. Using polymerase chain reaction–based suppression subtractive hybridization to find genes that are differentially expressed in hypoxia, we identified the BH3-only Bcl-2 family protein Noxa. Noxa is a candidate molecule mediating p53-induced apoptosis. We show that Noxa promoter responds directly to hypoxia via hypoxia-inducible factor (HIF)-1α. Suppression of Noxa expression by antisense oligonucleotides rescued cells from hypoxia-induced cell death and decreased infarction volumes in an animal model of ischemia. Further, we show that reactive oxygen species and resultant cytochrome c release participate in Noxa-mediated hypoxic cell death. Altogether, our results show that Noxa is induced by HIF-1α and mediates hypoxic cell death
Cloning and high-level production of a chitinase from Chromobacterium sp. and the role of conserved or nonconserved residues on its catalytic activity
A gene encoding an alkaline (pI of 8.67) chitinase was cloned and sequenced from Chromobacterium sp. strain C-61. The gene was composed of 1,611 nucleotides and encoded a signal sequence of 26N-terminal amino acids and a mature protein of 510 amino acids. Two chitinases of 54 and 52kDa from both recombinant Escherichia coli and C-61 were detected on SDS-PAGE. Maximum chitinase activity was obtained in the culture supernatant of recombinant E. coli when cultivated in TB medium for 6days at 37°C and was about fourfold higher than that from C-61. Chi54 from the culture supernatants could be purified by a single step based on isoelectric point. The purified Chi54 had about twofold higher binding affinity to chitin than to cellulose. The chi54 encoded a protein that included a type 3 chitin-binding domain belonging to group A and a family 18 catalytic domain belonging to subfamily A. In the catalytic domain, mutation of perfectly conserved residues and highly conserved residues resulted in loss of nearly all activity, while mutation of nonconserved residues resulted in enzymes that retained activity. In this process, a mutant (T218S) was obtained that had about 133% of the activity of the wild type, based on comparison of K cat value
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