6,166 research outputs found
An explicit KO-degree map and applications
The goal of this note is to study the analog in unstable -homotopy theory of the unit map from the motivic sphere spectrum to the
Hermitian K-theory spectrum, i.e., the degree map in Hermitian K-theory. We
show that "Suslin matrices", which are explicit maps from odd dimensional split
smooth affine quadrics to geometric models of the spaces appearing in Bott
periodicity in Hermitian K-theory, stabilize in a suitable sense to the unit
map. As applications, we deduce that for ,
which can be thought of as an extension of Matsumoto's celebrated theorem
describing of a field. These results provide the first step in a program
aimed at computing the sheaf for .Comment: 36 Pages, Final version, to appear Journal of Topolog
Non-perturbative results for the spectrum of surface-disordered waveguides
We calculated the spectrum of normal scalar waves in a planar waveguide with
absolutely soft randomly rough boundaries beyond the perturbation theories in
the roughness heights and slopes, basing on the exact boundary scattering
potential. The spectrum is proved to be a nearly real non-analytic function of
the dispersion of the roughness heights (with square-root
singularity) as . The opposite case of large boundary defects is
summarized.Comment: REVTEX 3, OSA style, 9 pages, no figures. Submitted to Optics Letter
Ultraviolet atomic emission detector
A device and method are provided for performing qualitative and quantitative elemental analysis through the utilization of a vacuum UV chromatographic detector. The method involves the use of a carrier gas at low pressure. The gas carries a sample to a gas chromatograph column; the column output is directed to a microwave cavity. In this cavity, a low pressure microwave discharge produces fragmentation of the compounds present and generates intense atomic emissions in the vacuum ultraviolet. These emissions are isolated by a monochromator and measured by photometer to establish absolute concentration for the elements
An absorption spectrum amplifier for determining gas composition
Compositions of gas samples are frequently studied by laser absorption spectroscopy. Sensitivity is improved by two orders of magnitude when absorption cell is placed inside an organic-dye laser cavity
Beat-wave generation of plasmons in semiconductor plasmas
It is shown that in semiconductor plasmas, it is possible to generate large
amplitude plasma waves by the beating of two laser beams with frequency
difference close to the plasma frequency. For narrow gap semiconductors (for
example n-type InSb), the system can simulate the physics underlying beat wave
generation in relativistic gaseous plasmas.Comment: 11 pages, LaTex, no figures, no macro
Discrimination between two mechanisms of surface-scattering in a single-mode waveguide
Transport properties of a single-mode waveguide with rough boundary are
studied by discrimination between two mechanisms of surface scattering, the
amplitude and square-gradient ones. Although these mechanisms are generically
mixed, we show that for some profiles they can separately operate within
non-overlapping intervals of wave numbers of scattering waves. This effect may
be important in realistic situations due to inevitable long-range correlations
in scattering profiles.Comment: 5 pages, 3 figure
Spin transfer and current-induced switching in antiferromagnets
We present theoretical description of the precessional switching processes
induced by simultaneous application of spin-polarized current and external
magnetic field to antiferromagnetic component of the "pinned" layer. We found
stability ranges of different static and dynamic regimes. We showed the
possibility of steady current-induced precession of antiferromagnetic vector
with frequency that linearly depends on the bias current. Furthermore, we found
an optimal duration of current pulse required for switching between different
orientations of antiferromagnetic vector and current and field dependence of
switching time. Our results reveal the difference between dynamics of ferro-
and antiferromagnets subjected to spin transfer torques.Comment: 7 pages, 4 figure
Sensitivity of Ag/Al Interface Specific Resistances to Interfacial Intermixing
We have measured an Ag/Al interface specific resistance, 2AR(Ag/Al)(111) =
1.4 fOhm-m^2, that is twice that predicted for a perfect interface, 50% larger
than for a 2 ML 50%-50% alloy, and even larger than our newly predicted 1.3
fOhmm^2 for a 4 ML 50%-50% alloy. Such a large value of 2ARAg/Al(111) confirms
a predicted sensitivity to interfacial disorder and suggests an interface
greater than or equal to 4 ML thick. From our calculations, a predicted
anisotropy ratio, 2AR(Ag/Al)(001)/2AR(Ag/Al)(111), of more then 4 for a perfect
interface, should be reduced to less than 2 for a 4 ML interface, making it
harder to detect any such anisotropy.Comment: 3 pages, 2 figures, 1 table. In Press: Journal of Applied Physic
Trust Model Measurements for the Energy Grid of Things
Information security is essential for the reliable operation of an Energy Grid of Things (EGoT). In addition to basic information security protocols as defined by published standards, there is a need for a monitoring function that measures the trustworthiness of the various actors participating in an EGoT. We describe in this paper the implementation and evaluation of a Distributed Trust Model that was developed specifically for monitoring communication within an EGoT. We then show how the model parameters are set using statistical measures for hypothesis testing
Stationary distributions for diffusions with inert drift
Consider reflecting Brownian motion in a bounded domain in that acquires drift in proportion to the amount of local time spent on the boundary of the domain. We show that the stationary distribution for the joint law of the position of the reflecting Brownian motion and the value of the drift vector has a product form. Moreover, the first component is uniformly distributed on the domain, and the second component has a Gaussian distribution. We also consider more general reflecting diffusions with inert drift as well as processes where the drift is given in terms of the gradient of a potential
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