3,730 research outputs found
Synthetic Quantum Systems
So far proposed quantum computers use fragile and environmentally sensitive
natural quantum systems. Here we explore the new notion that synthetic quantum
systems suitable for quantum computation may be fabricated from smart
nanostructures using topological excitations of a stochastic neural-type
network that can mimic natural quantum systems. These developments are a
technological application of process physics which is an information theory of
reality in which space and quantum phenomena are emergent, and so indicates the
deep origins of quantum phenomena. Analogous complex stochastic dynamical
systems have recently been proposed within neurobiology to deal with the
emergent complexity of biosystems, particularly the biodynamics of higher brain
function. The reasons for analogous discoveries in fundamental physics and
neurobiology are discussed.Comment: 16 pages, Latex, 1 eps figure fil
Diquarks: condensation without bound states
We employ a bispinor gap equation to study superfluidity at nonzero chemical
potential: mu .neq. 0, in two- and three-colour QCD. The two-colour theory,
QC2D, is an excellent exemplar: the order of truncation of the quark-quark
scattering kernel: K, has no qualitative impact, which allows a straightforward
elucidation of the effects of mu when the coupling is strong. In rainbow-ladder
truncation, diquark bound states appear in the spectrum of the three-colour
theory, a defect that is eliminated by an improvement of K. The corrected gap
equation describes a superfluid phase that is semi-quantitatively similar to
that obtained using the rainbow truncation. A model study suggests that the
width of the superfluid gap and the transition point in QC2D provide reliable
quantitative estimates of those quantities in QCD.Comment: 7 pages, 3 figures, REVTEX, epsfi
Wind turbine generator rotor blade concepts with low cost potential
Four processed for producing blades are examined. Two use filament winding techniques and two involve filling a mold or form to produce all or part of a blade. The processes are described and a comparison is made of cost, material properties, design and free vibration characteristics. Conclusions are made regarding the feasibility of each process to produce low cost, structurally adequate blades
Glass-Like Heat Conduction in High-Mobility Crystalline Semiconductors
The thermal conductivity of polycrystalline semiconductors with type-I
clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr
and/or Eu) exhibit lattice thermal conductivities typical of amorphous
materials. Remarkably, this behavior occurs in spite of the well-defined
crystalline structure and relatively high electron mobility (). The dynamics of dopant ions and their interaction with the
polyhedral cages of the structure are a likely source of the strong phonon
scattering.Comment: 4 pages, 3 postscript figures, to be published, Phys. Rev. Let
Feasibility study of the transonic biplane concept for transport aircraft application
Investigations were conducted to evaluate the feasibility of a transonic biplane consisting of a forward-mounted swept-back lower wing, a rear-mounted swept-forward upper wing, and a vertical fin connecting the wings at their tips. This wing arrangement results in significant reductions in induced drag relative to a monoplane designed with the same span, and it allows for a constant-section fuselage shape while closely matching an ideal area distribution curve for M = 0.95 cruise. However, no significant reductions in ramp weight were achieved for the biplane relative to a monoplane with the same mission capability. Flutter analyses of the biplane revealed both symmetric and antisymmetric instabilities that occur well below the required flutter speed. Further studies will be required to determine if acceptable flutter speeds can be achieved through the elimination of the instabilities by passive means or by active controls. Configurations designed for other missions, especially those with lower Mach numbers and lower dynamic pressures, should be examined since the geometries suitable for those design constraints might avoid the weight penalties and flutter instabilities which prevent exploitation of induced drag benefits for the configuration studied
Temperature mapping of stacked silicon dies from x-ray diffraction intensities
Increasing power densities in integrated circuits has led to an increased
prevalence of thermal hotspots in integrated circuits. Tracking these thermal
hotspots is imperative to prevent circuit failures. In 3D integrated circuits,
conventional surface techniques like infrared thermometry are unable to measure
3D temperature distribution and optical and magnetic resonance techniques are
difficult to apply due to the presence of metals and large current densities.
X-rays offer high penetration depth and can be used to probe 3D structures. We
report a method utilizing the temperature dependence of x-rays diffraction
intensity via the Debye-Waller factor to simultaneously map the temperature of
an individual silicon die that is a part of a stack of dies. Utilizing beamline
1-ID-E at the Advanced Photon Source (Argonne), we demonstrate for each
individual silicon die, a temperature resolution of 3 K, a spatial resolution
of 100 um x 400 um and a temporal resolution of 20 s. Utilizing a sufficiently
high intensity laboratory source, e.g., from a liquid anode source, this method
can be scaled down to laboratories for non-invasive temperature mapping of 3D
integrated circuits
The Calculation of Vacuum Properties from the Global Color Symmetry Model
A modified method for calculating the non-perturbative quark vacuum
condensates from the global color symmetry model is derived. Within this
approach it is shown that the vacuum condensates are free of ultraviolet
divergence which is different from previous studies. As a special, the
two-quark condensate and the mixed quark-gluon condensate are calculated. A
comparision with the results of the other nonperturbative QCD approaches is
given.Comment: 17 page
Racial Discrimination in Life Insurance
We examine the historical and statistical relationship between race and life insurance. Life insurance can play a central role in households’ financial security. Race has played an important and changing role in the provision of life insurance in the U.S. from slave insurance before the Civil War, to “Scientific Racism” continuing into the 20th century, to policies that do not explicitly mention race in recent decades. In empirical work using new data, we confirm earlier work showing that Black individuals have higher life insurance coverage rates than white individuals, controlling for observable characteristics. We find no difference in the likelihood of purchasing coverage—for Black individuals versus white individuals—in states with strong versus weak anti-discrimination laws. We also find that the presence of strong anti-discrimination laws tends to reduce overall life insurance coverage – by about 3 percentage points. We present some evidence that this finding is due to a generally stronger regulatory stance in the state rather than the specific impact of the anti-discrimination life insurance law. This analysis bears on the presence of discrimination in the current life insurance industry as well as related issues like the financial status of minority households
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