324,486 research outputs found
Domain wall propagation due to the synchronization with circularly polarized microwaves
Finding a new control parameter for magnetic domain wall (DW) motion in
magnetic nanostructures is important in general and in particular for the
spintronics applications. Here, we show that a circularly polarized magnetic
field (CPMF) at GHz frequency (microwave) can efficiently drive a DW to
propagate along a magnetic nanowire. Two motion modes are identified: rigid-DW
propagation at low frequency and oscillatory propagation at high frequency.
Moreover, DW motion under a CPMF is equivalent to the DW motion under a uniform
spin current in the current perpendicular to the plane magnetic configuration
proposed recently by Khvalkovskiy et al. [Phys. Rev. Lett. 102, 067206 (2009)],
and the CPMF frequency plays the role of the current
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Valuation of cash flows under random rates of interest: A linear algebraic approach
This paper reformulates the classical problem of cash flow valuation under stochastic discount factors into a system of linear equations with random perturbations. Using convergence results, a sequence of uniform approximations is developed. The new formulation leads to a general framework for deriving approximate statistics of cash flows for a broad class of models of stochastic interest rate process. We show applications of the proposed method by pricing default-free and defaultable cash flows. The methodology developed in this paper is applicable to a variety of uncertain cash flow analysis problems
Detecting and diagnosing faults in dynamic stochastic distributions using a rational b-splines approximation to output PDFs
Describes the process of detecting and diagnosing faults in dynamic stochastic distributions using a rational b-splines approximation to output PDFs
A wind tunnel investigation of the shape of uncharged raindrops in the presence of an external, electric field
Results of a wind tunnel experiment in which electrically uncharged water drops of 500 to 3000 microns equivalent radius are freely suspended in the vertical air stream of the UCLA cloud tunnel are presented. During this suspension the drops were exposed to external vertical electric fields of 500 to 8,000 volts/cm. The change in drop shape with drop size and electric field strength was noted and is discussed in the light of theoretical work cited in the literature which unfortunately does not take into account the effects of air flow past the drop. The wind tunnel study is documented by stills from a 16 mm film record that demonstrates the shape of water drops in response to both hydrodynamic and electric forces
Optimal time-dependent polarized current pattern for fast domain wall propagation in nanowires: Exact solutions for biaxial and uniaxial anisotropies
One of the important issues in nanomagnetism is to lower the current needed
for a technologically useful domain wall (DW) propagation speed. Based on the
modified Landau-Lifshitz-Gilbert (LLG) equation with both Slonczewski
spin-transfer torque and the field-like torque, we derive the optimal spin
current pattern for fast DW propagation along nanowires. Under such conditions,
the DW velocity in biaxial wires can be enhanced as much as ten times compared
to the velocities achieved in experiments so far. Moreover, the fast variation
of spin polarization can help DW depinning. Possible experimental realizations
are discussed.Comment: 4 pages, 1 figur
Macroporous materials: microfluidic fabrication, functionalization and applications
This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields
Optical spectroscopy study of the collapsed tetragonal phase of CaFe(AsP) single crystals
We present an optical spectroscopy study on P-doped CaFeAs which
experiences a structural phase transition from tetragonal to collapsed
tetragonal (cT) phase near 75 K. The measurement reveals a sudden reduction of
low frequency spectral weight and emergence of a new feature near 3200 \cm (0.4
eV) in optical conductivity across the transition, indicating an abrupt
reconstruction of band structure. The appearance of new feature is related to
the interband transition arising from the sinking of hole bands near
point below Fermi level in the cT phase, as expected from the density function
theory calculations in combination with the dynamical mean field theory.
However, the reduction of Drude spectral weight is at variance with those
calculations. The measurement also indicates an absence of the abnormal
spectral weight transfer at high energy (near 0.5-0.7 eV) in the cT phase,
suggesting a suppression of electron correlation effect.Comment: 6 pages, 4 figure
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A linear algebraic method for pricing temporary life annuities and insurance policies
We recast the valuation of annuities and life insurance contracts under mortality and interest rates, both of which are stochastic, as a problem of solving a system of linear equations with random perturbations. A sequence of uniform approximations is developed which allows for fast and accurate computation of expected values. Our reformulation of the valuation problem provides a general framework which can be employed to find insurance premiums and annuity values covering a wide class of stochastic models for mortality and interest rate processes. The proposed approach provides a computationally efficient alternative to Monte Carlo based valuation in pricing mortality-linked contingent claims
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