3,215 research outputs found
COMMUNITY CHOICES AND HOUSING DECISIONS: A SPATIAL ANALYSIS OF THE SOUTHERN APPALACHIAN HIGHLANDS
This paper examines land development using an integrated approach that combines residential decisions about choices of community in the Southern Appalachian region with the application of the GIS (Geographical Information System). The empirical model infers a distinctive heterogeneity in the characteristics of community choices. The results also indicate that socioeconomic motives strongly affect urban housing decisions while environmental amenities affect those of rural housing.Public Economics,
Skyrmion Generation by Current
Skyrmions, once a hypothesized field-theoretical object believed to describe
the nature of elementary particles, became common sightings in recent years
among several non-centrosymmetric metallic ferromagnets. For more practical
applications of Skyrmionic matter as carriers of information, thus realizing
the prospect of "Skyrmionics", it is necessary to have the means to create and
manipulate Skyrmions individually. We show through extensive simulation of the
Landau-Lifshitz-Gilbert equation that a circulating current imparted to the
metallic chiral ferromagnetic system can create isolated Skyrmionic spin
texture without the aid of external magnetic field.Comment: 8 pages, 5 figures, submitted to PR
Isospin particle on with arbitrary number of supersymmetries
We study the supersymmetric quantum mechanics of an isospin particle in the
background of spherically symmetric Yang-Mills gauge field. We show that on
the number of supersymmetries can be made arbitrarily large for a
specific choice of the spherically symmetric SU(2) gauge field. However, the
symmetry algebra containing the supercharges becomes nonlinear if the number of
fermions is greater than two. We present the exact energy spectra and
eigenfunctions, which can be written as the product of monopole harmonics and a
certain isospin state. We also find that the supersymmetry is spontaneously
broken if the number of supersymmetries is even.Comment: 6 page
Interplay between Fermi surface topology and ordering in URuSi revealed through abrupt Hall coefficient changes in strong magnetic fields
Temperature- and field-dependent measurements of the Hall effect of pure and
4 % Rh-doped URuSi reveal low density (0.03 hole/U) high mobility
carriers to be unique to the `hidden order' phase and consistent with an
itinerant density-wave order parameter. The Fermi surface undergoes a series of
abrupt changes as the magnetic field is increased. When combined with existing
de Haas-van Alphen data, the Hall data expose a strong interplay between the
stability of the `hidden order,' the degree of polarization of the Fermi liquid
and the Fermi surface topology.Comment: 4 pages, 4 figures, Accepted to Phys. Rev. Let
Staggered Currents in the Vortex Core
We study the electronic structure of the vortex core in the cuprates using
the U(1) slave-boson mean-field wavefunctions and their Gutzwiller projection.
We conclude that there exists local orbital antiferromagnetic order in the core
near optimal doping. We compare the results with that of BCS theory and analyze
the spatial dependence of the local tunneling density of states.Comment: 4 pages, 3 figure
Skyrmion Lattice in Two-Dimensional Chiral Magnet
We develop a theory of the magnetic field-induced formation of Skyrmion
crystal state in chiral magnets in two spatial dimensions, motivated by the
recent discovery of the Skyrmionic phase of magnetization in thin film of
FeCoSi and in the A-phase of MnSi. Ginzburg-Landau functional
of the chiral magnet re-written in the CP representation is shown to be a
convenient framework for the analysis of the Skyrmion states. Phase diagram of
the model at zero temperature gives a sequence of ground states, helical spin
Skyrme crystal ferromagnet, as the external field
increases, in good accord with the thin-film experiment. In close analogy
with Abrikosov's derivation of the vortex lattice solution in type-II
superconductor, the CP mean-field equation is solved and shown to reproduce
the Skyrmion crystal state.Comment: 10 pages, 7 figure
Leader Readiness in a Volatile, Uncertain, Complex, and Ambiguous Business Environment
Organizational leaders in the 21st century face relentless changes in the business environments in which they operate. The diversity, intensity, and rapidity of these changes create volatility, uncertainty, complexity, and ambiguity (VUCA), which challenge leaders on ways to lead effectively as existing methods prove inadequate. The problem in this study was that of inadequate leader preparedness to lead and win in VUCA environments. The purpose of this hermeneutic phenomenological study was to explore the lived experiences of 15 Nigerian corporate executives about their VUCA business environment and the strategies they employed for VUCA-readiness and success using open-ended interview questions. The conceptual framework guiding this study was a combination of chaos theory and complexity leadership theory. Through Ricoeur’s theory of interpretation, member checking, and contextual triangulation, 11 key themes emerged to highlight key coping and readiness strategies for leaders operating in turbulent environments. The key recommendations for practice are to inculcate VUCA-readiness and organizational resilience principles in line with this study’s findings. The study findings may contribute to positive social change in providing strategies for organizational sustainability, firm success, business readiness, responsive leadership, and enhanced employee well-being
Endothelial function in migraine: a cross-sectional study
ABSTRACT: BACKGROUND: Migraine has been associated with cardiovascular disorders. Endothelial dysfunction may be a mechanism underlying this association. The present study tested the hypothesis that endothelium-dependent vasodilation, basal endothelial nitric oxide release and endothelial fibrinolytic capacity are impaired in migraine patients. METHODS: Graded doses of sodium nitroprusside (SNP, 0.2 to 0.8 microg.min 1.dL-1 forearm), substance P (0.2 to 0.8 pmol.min-1.dL-1 forearm) and NG monomethyl-L-arginine (L-NMMA, 0.1 to 0.4 micromol.min-1.dL-1 forearm) were infused into the brachial artery of 16 migraine patients with or without aura during a headache-free interval and 16 age- and sex-matched subjects without a history of migraine. Forearm blood flow (FBF) was measured by strain-gauge venous occlusion plethysmography. Local forearm release of tissue plasminogen activator (t-PA) in response to substance P infusion was assessed using the arteriovenous plasma concentration gradient. Responses to infused drugs were compared between patients and matched controls by analysis of variance. RESULTS: In both migraine patients and control subjects, SNP and substance P caused a dose-dependent increase, and L NMMA a dose-dependent decrease in FBF (P < 0.001 for all responses). In both groups, substance P caused an increase in t-PA release (P < 0.001). FBF responses and t-PA release were comparable between migraine patients and control subjects. CONCLUSIONS: The absence of differences in endothelium-dependent vasodilation, basal endothelial nitric oxide production and stimulated t-PA release between migraine patients and healthy control subjects argues against the presence of endothelial dysfunction in forearm resistance vessels of migraine patients.status: publishe
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