16,047 research outputs found
Quantum Hall Ferromagnets: Induced Topological term and electromagnetic interactions
The quantum Hall ground state in materials like GaAs is well known
to be ferromagnetic in nature. The exchange part of the Coulomb interaction
provides the necessary attractive force to align the electron spins
spontaneously. The gapless Goldstone modes are the angular deviations of the
magnetisation vector from its fixed ground state orientation. Furthermore, the
system is known to support electrically charged spin skyrmion configurations.
It has been claimed in the literature that these skyrmions are fermionic owing
to an induced topological Hopf term in the effective action governing the
Goldstone modes. However, objections have been raised against the method by
which this term has been obtained from the microscopics of the system. In this
article, we use the technique of the derivative expansion to derive, in an
unambiguous manner, the effective action of the angular degrees of freedom,
including the Hopf term. Furthermore, we have coupled perturbative
electromagnetic fields to the microscopic fermionic system in order to study
their effect on the spin excitations. We have obtained an elegant expression
for the electromagnetic coupling of the angular variables describing these spin
excitations.Comment: 23 pages, Plain TeX, no figure
Low-velocity anisotropic Dirac fermions on the side surface of topological insulators
We report anisotropic Dirac-cone surface bands on a side-surface geometry of
the topological insulator BiSe revealed by first-principles
density-functional calculations. We find that the electron velocity in the
side-surface Dirac cone is anisotropically reduced from that in the
(111)-surface Dirac cone, and the velocity is not in parallel with the wave
vector {\bf k} except for {\bf k} in high-symmetry directions. The size of the
electron spin depends on the direction of {\bf k} due to anisotropic variation
of the noncollinearity of the electron state. Low-energy effective Hamiltonian
is proposed for side-surface Dirac fermions, and its implications are presented
including refractive transport phenomena occurring at the edges of tological
insulators where different surfaces meet.Comment: 4 pages, 2 columns, 4 figure
The Penobscot Exchange
The Penobscot Exchange Hotel on Exchange Street in Bangor, built in 1827 and remodeled a number of times, was a popular hotel in Bangor\u27s history. Its proximity to Eastern Railway Station on the Bangor waterfront appealed to travelers. Fred G. Moon and James W. Cratty were the proprietors beginning in 1897 (according to the 1897-98 Bangor City Directory). This pamphlet is not dated, but date is estimated to be between 1897-1910 (Bangor city directories for this period indicate Moon & Cratty as proprietors). The pamphlet describes the accommodations offered and has several pictures of the rooms.https://digicom.bpl.lib.me.us/books_pubs/1260/thumbnail.jp
Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5 Transition Metal Oxides SrIrO (=1, 2, and )
We investigated the electronic structures of the 5 Ruddlesden-Popper
series SrIrO (=1, 2, and ) using optical
spectroscopy and first-principles calculations. As 5 orbitals are spatially
more extended than 3 or 4 orbitals, it has been widely accepted that
correlation effects are minimal in 5 compounds. However, we observed a
bandwidth-controlled transition from a Mott insulator to a metal as we
increased . In addition, the artificially synthesized perovskite SrIrO
showed a very large mass enhancement of about 6, indicating that it was in a
correlated metallic state
Integration in the Classroom: Ten Teaching Strategies
Teaching integration involves engaging students as active participants in the unfolding relationship of psychology and Christianity, with a particular focus on integration. Ten specific teaching strategies are offered to help students enter into the challenges and opportunities of integration. The teaching strategies are organized according to Moon\u27s (1997) four directions for integration: practical, personal, classic, and contemporary
Evolution of thin-wall configurations of texture matter
We consider the free matter of global textures within the framework of the
perfect fluid approximation in general relativity. We examine thermodynamical
properties of texture matter in comparison with radiation fluid and bubble
matter. Then we study dynamics of thin-wall selfgravitating texture objects,
and show that classical motion can be elliptical (finite), parabolical or
hyperbolical. It is shown that total gravitational mass of neutral textures in
equilibrium equals to zero as was expected. Finally, we perform the
Wheeler-DeWitt's minisuperspace quantization of the theory, obtain exact wave
functions and discrete spectra of bound states with provision for spatial
topology.Comment: intermediate research on nature of dual-radiation matter; LaTeX, 12
pages, 1 figure and epsfig style file included; slightly shortened version
was published in December issue of GR
Influence of compressing pressure on macro void formation of carbon monolith for methane adsorption
Carbon monoliths for adsorbed natural gas (ANG) storage were prepared from Mongolian anthracite-based activated carbons using carboxy-methyl cellulose as a binder under different compressing pressures. Nitrogen adsorption/desorption experiments were carried out to obtain the specific surface area, pore volume, and pore size distribution of the monoliths. Methane adsorption experiments on the carbon monoliths were conducted at different temperatures and pressures up to around 3.5 MPa in a high pressure volumetric adsorption apparatus. As expected, adsorption results indicated that the methane adsorption capacity of the carbon monoliths increased with increasing specific surface area and packing density. The maximum volumetric adsorption of methane was observed as 163 V/V at 293 K and 3.5 MPa on a carbon monolith sample, PMAC1/2-3-65, that does not have the highest specific surface area but relatively high packing density comparing with other monoliths, which implies that two physical properties contribute contradictorily to the methane adsorption capacity. Based on experimental results, the carbon monoliths prepared from Mongolian anthracite-based activated carbons can be promising media for ANG storage application
Retraction notice: Influence of compressing pressure on macro void formation carbon monolith for methane adsorption
RETRACTION NOTICEOn 21rd February 2019, the Editorial Board of the Mongolian Journal of Chemistry decided to retract this article entitled "Influence of compressing pressure on macro void formation of carbon monolith for methane adsorption" because of an authorship dispute. The article was originally published in Vol.18 No.44 2017 pp.24-35. doi: https://doi.org/10.5564/mjc.v18i44.93
Micro-processes of translation in the transfer of practices from MNE headquarters to foreign subsidiaries: the role of subsidiary translators
Recent research has increasingly emphasized the micro-foundations of knowledge transformation in multi-national enterprises (MNEs). Although the literature has provided ample evidence of the enablers of and barriers to the translation of practices, less is known about the activities and efforts of translators that lead to specific types of translation in the context of the transfer of practices initiated at a MNEâs headquarters (HQ) to foreign subsidiaries. We apply a Scandinavian institutionalist approach to examine the translation of corporate social responsibility reporting, an HQ-initiated practice that is transferred to five foreign subsidiaries of a UK-based MNE. Our paper builds from a preliminary framework based on extant research to develop an extended framework of the micro-processes of translation. By theorizing the sequence of the micro-processes undertaken by translators, identifying the conditions under which they occur, and connecting them to the three types of translation, we provide a deep understanding of the micro-foundations of translation when transferring practices from HQ to subsidiaries. Our paper shows that translation is an evolving phenomenon and illuminates the importance of attending to the social, spatial, and temporal situatedness of translators. It also brings insights into the individual experience of institutional distance and its effects on translation
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