15,079 research outputs found
Quantitative Measurements in the Transmission in Solid Acoustic Wave Filters with Varying Physical Dimensions
The object of these experiments was to test the transmission of solid acoustic wave filters with the view to the establishment of empirical formulas to be used in future designs. The length of sections, the conductivity into the branch lines, and the volume of the branch lines were altered in the case of low-frequency-pass-filters. In all cases the variations produced effects that are analogous to those found with acoustic wave filters in fluids. But more than this, so far as a test has been made, the cut-off frequency is in agreement with the Stewart theory for fluids. This means that the phenomena is caused almost exclusively by the longitudinal waves. Moreover, recurring bands were found in high frequencies and these seemed to be in accord with the more extended theory of Stewart concerning the presence of such additional bands. The conclusion in that the acoustic wave filters in solids can be designated on the basis of the formulas obtained for fluids
Investigation of kilovolt ion sputtering Quarterly progress report, May - Jul. 1966
Aluminum sputtering, and neutron activation analysis after cesium ion bombardmen
The burrowing beetles of the genus Mycotrupes (Coleoptera: Scarabaeidae: Geotrupinae)
http://deepblue.lib.umich.edu/bitstream/2027.42/56329/1/MP084.pd
Nonequilibrium Approach to Bloch-Peierls-Berry Dynamics
We examine the Bloch-Peierls-Berry dynamics under a classical nonequilibrium
dynamical formulation. In this formulation all coordinates in phase space
formed by the position and crystal momentum space are treated on equal footing.
Explicitly demonstrations of the no (naive) Liouville theorem and of the
validity of Darboux theorem are given. The explicit equilibrium distribution
function is obtained. The similarities and differences to previous approaches
are discussed. Our results confirm the richness of the Bloch-Peierls-Berry
dynamics
Direct observation of particle-hole mixing in the superconducting state by angle-resolved photoemission
Particle-hole (p-h) mixing is a fundamental consequence of the existence of a
pair condensate. We present direct experimental evidence for p-h mixing in the
angle-resolved photoemission (ARPES) spectra in the superconducting state of
Bi_2Sr_2CaCu_2O_{8+\delta}. In addition to its pedagogical importance, this
establishes unambiguously that the gap observed in ARPES is associated with
superconductivity.Comment: 3 pages, revtex, 4 postscript figure
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Canagliflozin lowers blood sugar, but does it also lower cardiovascular risk? Maybe not
For the last 25 years it has been widely accepted that diabetes mellitus is associated with a twofold or greater risk of clinical atherosclerotic disease. Long-standing elevated blood sugar levels, as measured by the hemoglobin A1c level, have been shown to be independent of major cardiovascular risk factors including age, body mass index, systolic blood pressure, serum cholesterol, cigarette smoking, or history of cardiovascular disease
Superconducting Fluxon Pumps and Lenses
We study stochastic transport of fluxons in superconductors by alternating
current (AC) rectification. Our simulated system provides a fluxon pump,
"lens", or fluxon "rectifier" because the applied electrical AC is transformed
into a net DC motion of fluxons. Thermal fluctuations and the asymmetry of the
ratchet channel walls induce this "diode" effect, which can have important
applications in devices, like SQUID magnetometers, and for fluxon optics,
including convex and concave fluxon lenses. Certain features are unique to this
novel two-dimensional (2D) geometric pump, and different from the previously
studied 1D ratchets.Comment: Phys. Rev. Lett. 83, in press (1999); 4 pages, 5 .gif figures;
figures also available at http://www-personal.engin.umich.edu/~nori/ratche
A System for Accessible Artificial Intelligence
While artificial intelligence (AI) has become widespread, many commercial AI
systems are not yet accessible to individual researchers nor the general public
due to the deep knowledge of the systems required to use them. We believe that
AI has matured to the point where it should be an accessible technology for
everyone. We present an ongoing project whose ultimate goal is to deliver an
open source, user-friendly AI system that is specialized for machine learning
analysis of complex data in the biomedical and health care domains. We discuss
how genetic programming can aid in this endeavor, and highlight specific
examples where genetic programming has automated machine learning analyses in
previous projects.Comment: 14 pages, 5 figures, submitted to Genetic Programming Theory and
Practice 2017 worksho
Formation of cosmological mass condensation within a FRW universe: exact general relativistic solutions
Within the framework of an exact general relativistic formulation of gluing
manifolds, we consider the problem of matching an inhomogeneous overdense
region to a Friedmann-Robertson-Walker background universe in the general
spherical symmetric case of pressure-free models. It is shown that, in general,
the matching is only possible through a thin shell, a fact ignored in the
literature. In addition to this, in subhorizon cases where the matching is
possible, an intermediate underdense region will necessarily arise.Comment: 6 page
Hall of Mirrors Scattering from an Impurity in a Quantum Wire
This paper develops a scattering theory to examine how point impurities
affect transport through quantum wires. While some of our new results apply
specifically to hard-walled wires, others--for example, an effective optical
theorem for two-dimensional waveguides--are more general. We apply the method
of images to the hard-walled guide, explicitly showing how scattering from an
impurity affects the wire's conductance. We express the effective cross section
of a confined scatterer entirely in terms of the empty waveguide's Green's
function, suggesting a way in which to use semiclassical methods to understand
transport properties of smooth wires. In addition to predicting some new
phenomena, our approach provides a simple physical picture for previously
observed effects such as conductance dips and confinement-induced resonances.Comment: 19 pages, 8 figures. Accepted for publication in Physical Review B.
Minor additions to text, added reference
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