4,356 research outputs found
Prediction of Giant Spin Motive Force due to Rashba Spin-Orbit Coupling
Magnetization dynamics in a ferromagnet can induce a spin-dependent electric
field through spin motive force. Spin current generated by the spin-dependent
electric field can in turn modify the magnetization dynamics through
spin-transfer torque. While this feedback effect is usually weak and thus
ignored, we predict that in Rashba spin-orbit coupling systems with large
Rashba parameter , the coupling generates the spin-dependent
electric field [\pm(\alpha_{\rm R}m_e/e\hbar) (\vhat{z}\times \partial
\vec{m}/\partial t)], which can be large enough to modify the magnetization
dynamics significantly. This effect should be relevant for device applications
based on ultrathin magnetic layers with strong Rashba spin-orbit coupling.Comment: 4+ pages, 2 figure
RISK-SHARING AS A LONG-TERM MOTIVATION TO FRANCHISE: ROLE OF FRANCHISING EXPERIENCE
This study aimed to examine a long-term motivation for franchising by considering the influence of experience franchisors gain through conducting the franchising strategy. The study mainly investigates the moderating effect of franchising experience on the relationship between three main motivations for franchising (derived from agency theory, resource scarcity theory, and risk-sharing theory) and firms’ degree of franchising in the restaurant context. Dynamic panel data model was employed and the findings suggest that not only do restaurant companies’ franchising experience positively affect firms’ degree of franchising, but also that those experiences positively moderate the relationship between risk sharing motivation and the degree of franchising. The findings lead to theoretical and practical implications and suggestions for future research
Collapse or Swelling Dynamics of Homopolymer Rings: Self-consistent Hartree approach
We investigate by the use of the Martin - Siggia - Rose generating functional
technique and the self - consistent Hartree approximation, the dynamics of the
ring homopolymer collapse (swelling) following an instantaneous change into a
poor (good) solvent conditions.The equation of motion for the time dependent
monomer - to - monomer correlation function is systematically derived. It is
argued that for describing of the coarse - graining process (which neglects the
capillary instability and the coalescence of ``pearls'') the Rouse mode
representation is very helpful, so that the resulting equations of motion can
be simply solved numerically. In the case of the collapse this solution is
analyzed in the framework of the hierarchically crumpled fractal picture, with
crumples of successively growing scale along the chain. The presented numerical
results are in line with the corresponding simple scaling argumentation which
in particular shows that the characteristic collapse time of a segment of
length scales as (where is a bare
friction coefficient and is a depth of quench). In contrast to the
collapse the globule swelling can be seen (in the case that topological effects
are neglected) as a homogeneous expansion of the globule interior. The swelling
of each Rouse mode as well as gyration radius is discussed.Comment: 20 pages, 7 figures, submitted to Phys. Rev.
Chiral magnetoresistance in Pt/Co/Pt zigzag wires
The Rashba effect leads to a chiral precession of the spins of moving
electrons while the Dzyaloshinskii-Moriya interaction (DMI) generates
preference towards a chiral profile of local spins. We predict that the
exchange interaction between these two spin systems results in a 'chiral'
magnetoresistance depending on the chirality of the local spin texture. We
observe this magnetoresistance by measuring the domain wall (DW) resistance in
a uniquely designed Pt/Co/Pt zigzag wire, and by changing the chirality of the
DW with applying an in-plane magnetic field. A chirality-dependent DW
resistance is found, and a quantitative analysis shows a good agreement with a
theory based on the Rashba model. Moreover, the DW resistance measurement
allows us to independently determine the strength of the Rashba effect and the
DMI simultaneously, and the result implies a possible correlation between the
Rashba effect, the DMI, and the symmetric Heisenberg exchange
Void and beyond : reading between the void structures
Thesis (M.Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2002.Includes bibliographical references (p. 66-68).At present, most cities confront similar issues that result from mass production, individualism, automobile-dependency and the advancement of democratic ownership. These issues have pushed our cities in a somewhat undesirable direction. Self-addressing buildings are everywhere disguised in a distorted framework of aesthetic knowledge. They are uncommunicative both to nature and their surroundings. This is the predominant feature of current cities. Considering the aforementioned issues, this thesis proposes a building that defines an edge of architecture by the various void structures it faces. Unlike the design method based on a particular program and solid dimensions of an object, it focuses primarily on the outer forces of the site, which is called 'void structures' . Void structures can be divided into three categories: Void structure in nature, void structure in human settlement, and the movement pattern of people. These undefined formal relationships between the void structures - the void created by the topography, human settlement, movement pattern of people and architectural elements - are the major consideration in defining architectural configuration. By relating these voids, physical and psychological boundaries are eliminated, and the architecture becomes the connector between nature and people. Architectural investigation of this thesis is divided into four elements: First, the earth is perfected by seeking a proper foundation. Second, formation of water body is sought as a means of connection to a natural void. Third , the roof is manipulated to turn an ecological void into a spatial void to produce aesthetic pleasure. Fourth, openings are studied to strengthen the relationship between void structures.by Kyung-A Lee.M.Arch
J/psi hadron interaction in vacuum and in QGP
Motivated by the recent lattice data that will survive up to
1.6, we calculate the thermal width of at finite temperature in
perturbative QCD. The inputs of the calculation are the parton quarkonium
dissociation cross sections at the NLO in QCD, which were previously obtained
by Song and Lee, and a gaussian charmonium wave function, whose size were
fitted to an estimate by Wong by solving the schrodinger equation for
charmonium in a potential extracted from the lattice at finite temperature. We
find that the total thermal width above 1.4 becomes larger than 100 to 200
MeV, depending on the effective thermal masses of the quark and gluon, which we
take it to vary from 600 to 400 MeV.Comment: 4 pages, Talk at Quark Matter 200
- …