4,003 research outputs found
Importance of van der Waals interactions for ab initio studies of topological insulators
We investigate the lattice and electronic structures of the bulk and surface
of the prototypical layered topological insulators BiSe and
BiTe using ab initio density functional methods, and systematically
compare the results of different methods of including van der Waals (vdW)
interactions. We show that the methods utilizing semi-empirical energy
corrections yield accurate descriptions of these materials, with the most
precise results obtained by properly accounting for the long-range tail of the
vdW interactions. The bulk lattice constants, distances between quintuple
layers and the Dirac velocity of the topological surface states (TSS) are all
in excellent agreement with experiment. In BiTe, hexagonal warping of
the energy dispersion leads to complex spin textures of the TSS at moderate
energies, while in BiSe these states remain almost perfectly helical
away from the Dirac point, showing appreciable signs of hexagonal warping at
much higher energies, above the minimum of the bulk conduction band. Our
results establish a framework for unified and systematic self-consistent first
principles calculations of topological insulators in bulk, slab and interface
geometries, and provides the necessary first step towards ab initio modeling of
topological heterostructures.Comment: 26 pages, 7 figures. This is the Accepted Manuscript version of an
article accepted for publication in Journal of Physics: Condensed Matter. IOP
Publishing Ltd is not responsible for any errors or omissions in this version
of the manuscript or any version derived from it. The Version of Record is
available online at https://dx.doi.org/10.1088/1361-648X/abbdb
Speciation in the baboon and its relation to gamma-chain heterogeneity and to the response to induction of HbF by 5-azacytidine
In the baboon (Papio species), the two nonallelic gamma-genes produce gamma-chains that differ at a minimum at residue 75, where isoleucine (I gamma-chain) or valine (V gamma) may be present. This situation obtains in baboons that are sometimes designated as Papio anubis, Papio hamadryas, and Papio papio. However, in Papio cynocephalus, although the I gamma-chains are identical with those in the above mentioned types, the V gamma-chains have the substitutions ala----gly at residue 9 and ala----val at residue 23. The V gamma-chains of P. cynocephalus are called V gamma C to distinguish them from the V gamma A-chains of P. anubis, etc. A single cynocephalus animal has been found to have only normal I gamma-chains and I gamma C-chains (that is, glycine in residue 9, valine in 23, and isoleucine in 75). When HbF is produced in response to stress with 5-azacytidine, P. anubis baboons respond with greater production than do P. cynocephalus, and hybrids fall between. Minimal data on P. hamadryas and P. papio suggest an even lower response than P. cynocephalus. As HbF increases under stress, the ratio of I gamma to V gamma-chains changes from the value in the adult or juvenile baboon toward the ratio in the newborn baboon. However, it does not attain the newborn value. The V gamma A and V gamma C-genes respond differently to stress. In hybrids, the production of V gamma A- chains exceeds that of V gamma C-chains. A controlling factor in cis apparently is present and may be responsible for the species-related extent of total HbF production. It may be concluded that the more primitive the cell in the erythroid maturation series that has been subjected to 5-azacytidine, the more active is the I gamma-gene
Community Property
Covers cases on the surrender value of community insurance subject to inheritance tax and on distinguishing community and separate property
Communication Department Heads: An Analysis of Positions Available 1990 through 1994
This article presents an analysis of positions available in 1990 through 1994 as communication department heads in the U.S. It is not surprising that over 75% of the listings for department heads indicated that the doctorate or other terminal degree would be required. The doctorate has become a standard feature associated with positions in higher education, and most certainly for senior-level positions. Nearly 95% (94.34%) of the listings indicated that candidates would be appointed at the rank of associate professor or higher. Such positions require candidates to meet all of the standard qualifications for a tenured appointment, including possession of the doctorate
The Art of Framing: Managing the Language of Leadership, by Gail T. Fairhurst and Robert A. Sarr
a book review of The Art of Framing: Managing the Language of Leadership, by Gail T. Fairhurst and Robert A. Sarr
The Effects of Two Novel Anti-Inflammatory Compounds On Prepulse Inhibition and Neural Microglia Cell Activation in a Rodent Model of Schizophrenia
Recent studies have shown elevated neuroinflammation in a large subset of individuals diagnosed with schizophrenia. A pro-inflammatory cytokine, tumor necrosis factor-alpha (TNFα), has been directly linked to this neuroinflammation. This study examined the effects of two TNFα modulators (PD2024 and PD340) produced by our collaborators at P2D Bioscience, Inc., to alleviate auditory sensorimotor gating deficits and reduce microglial cell activation present in the polyinosinic:polycytidylic (Poly I:C) rodent model of schizophrenia. Auditory sensorimotor gating was assessed using prepulse inhibition and microglial activation was examined and quantified using immunohistochemistry and confocal microscopy, respectively. Both PD2024 and PD340 alleviated auditory sensorimotor gating deficits and reduced microglia activation and thereby demonstrated the ability to treat both the behavioral and neuroinflammatory aspects of the disorder. These results are significant and suggest that neural TNFα is a potential pharmacological target for the treatment of schizophrenia
Paper Session III-A - STS Derivative Cargo Vehicles for the 1990\u27s Decade and Beyond
Currently planned U.S. civil space activities for the late 1990\u27s into the early 2000 time period will require the development of a new earth-to-orbit unmanned cargo vehicle(s). This system will be designed to support an aggressive space activity, including Space Station Freedom and eventually lunar/planetary exploration programs. Primary mission needs include increased cargo weight and volume capability and lower operating costs.
A mid-90\u27s unmannedcargo vehicle (Shuttle C), which utilizes existing space-qualified STS booster elements, is currently being designed for delivery of 100K-150K Ibs to low earth orbit. Variations of this design plus other concepts that offer very large lift capability of 200K-300K Ibs, still utilizing STS booster elements, will be discussed. An evolutionary pathway, based on STS booster elements, is practical for providing heavy lift capabilities of 100K-300K Ibs
Transforming Scholarship Assessed into Scholarship Accessed: Examining the Communication Implications of a Boyer Report
This article presents an overview of the book Scholarship Assessed, by C. E. Glassick et al. The book is an Ernest Boyer project of the Carnegie Foundation for the Advancement of Teaching. The work is clearly designed to extend the original argument made in the book Scholarship Reconsidered, which builds the case for extending the boundaries of what counts as scholarly activity for the nation\u27s faculty at colleges and universities. The text is divided into five chapters that follow Boyer\u27s prologue. In addition, the text attempts to address the concerns raised by Boyer and to develop a general understanding of how all brands of scholarship may be evaluated and assessed in the academy
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