337,291 research outputs found
Dimensional Reduction via Noncommutative Spacetime: Bootstrap and Holography
Unlike noncommutative space, when space and time are noncommutative, it seems
necessary to modify the usual scheme of quantum mechanics. We propose in this
paper a simple generalization of the time evolution equation in quantum
mechanics to incorporate the feature of a noncommutative spacetime. This
equation is much more constraining than the usual Schr\"odinger equation in
that the spatial dimension noncommuting with time is effectively reduced to a
point in low energy. We thus call the new evolution equation the spacetime
bootstrap equation, the dimensional reduction called for by this evolution
seems close to what is required by the holographic principle. We will discuss
several examples to demonstrate this point.Comment: 15 pages, harvmac. v2: typos corrected and some changes mad
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Flow measurement inside a zinc-nickel flow cell battery using FBG based sensor system
Downloading of the abstract is permitted for personal use only. A detailed knowledge of the internal flow distribution inside a zinc-nickel flow battery is of critical importance to ensure smooth flow of the electrolyte through the battery cell and better operation of the device. Information of this type can be used as a useful means of early detection of zinc deposition and dendrite formation inside the cell, negative factors which affect the flow and thus which can lead to internal short circuiting, this being a primary failure mode of these types of batteries. This deposition occurs at low pH levels when zinc reacts with the electrolyte to form solid zinc oxide hydroxides. Traditionally, manual inspection is conducted, but this is time consuming and costly, only providing what are often inaccurate results-overall it is an impractical solution especially with the wider use of batteries in the very near future. Fibre Bragg grating (FBG) sensors integrated inside the flow cell offer the advantage of measuring flow changes at multiple locations using a single fibre and that then can be used as an indicator of the correlation between the internal flow distribution and the deposition characteristics. This work presents an initial study, where two networks of FBGs have been installed and used for flow change detection in an active zinc-nickel flow battery. Data have been obtained from the sensor networks and information of battery performance completed and summarized in this paper. The approach shows promising results and thus scope for the future research into the development of this type of sensor system
Interdot Coulomb repulsion effect on the charge transport of parallel double single electron transistors
The charge transport behaviors of parallel double single electron transistors
(SETs) are investigated by the Anderson model with two impurity levels. The
nonequilibrium Keldysh Green's technique is used to calculate the
current-voltage characteristics of system. For SETs implemented by quantum dots
(QDs) embedded into a thin layer, the interdot Coulomb repulsion is
more important than the interdot electron hopping as a result of high potential
barrier height between QDs and . We found that the interdot Coulomb
repulsion not onlyleads to new resonant levels, but also creates negative
differential conductances.Comment: 12 pages, 7 figure
Thiadizoloquinoxaline-Based Low-Bandgap Conjugated Polymers as Ambipolar Semiconductors for Organic Field Effect Transistors
Millet agriculture dispersed from Northeast China to the Russian Far East: integrating archaeology, genetics, and linguistics
Broomcorn and foxtail millets were being cultivated in the West Liao River basin in Northeast China by at least the sixth millennium BCE. However, when and how millet agriculture spread from there to the north and east remains poorly understood. Here, we trace the dispersal of millet agriculture from Northeast China to the Russian Far East and weigh demic against cultural diffusion as mechanisms for that dispersal. We compare two routes for the spread of millet into the Russian Far East discussed in previous research—an inland route across Manchuria, and a coastal/inland route initially following the Liaodong Peninsula and Yalu River—using an archaeological dataset including millet remains, pottery, stone tools, spindle whorls, jade and figurines. We then integrate the archaeological evidence with linguistic and genetic findings in an approach we term ‘triangulation’. We conclude that an expansion of agricultural societies in Northeast China during the Middle to Late Hongshan (4000–3000 BCE) coincided with the arrival of millet cultivation in eastern Heilongjiang and the Primorye province of the Russian Far East. Our findings support the inland, Manchuria route for the dispersal of millet to the Primorye and suggest that, as well as long-distance cultural exchange, demic diffusion was also involved. Our results are broadly compatible with the farming/language dispersal hypothesis and consistent with a link between the spread of millet farming and proto-Tungusic, the language ancestral to the contemporary Tungusic languages, in late Neolithic Northeast Asia. © 2020 The Author
Sensitivity of the eigenfunctions and the level curvature distribution in quantum billiards
In searching for the manifestations of sensitivity of the eigenfunctions in
quantum billiards (with Dirichlet boundary conditions) with respect to the
boundary data (the normal derivative) we have performed instead various
numerical tests for the Robnik billiard (quadratic conformal map of the unit
disk) for 600 shape parameter values, where we look at the sensitivity of the
energy levels with respect to the shape parameter. We show the energy level
flow diagrams for three stretches of fifty consecutive (odd) eigenstates each
with index 1,000 to 2,000. In particular, we have calculated the (unfolded and
normalized) level curvature distribution and found that it continuously changes
from a delta distribution for the integrable case (circle) to a broad
distribution in the classically ergodic regime. For some shape parameters the
agreement with the GOE von Oppen formula is very good, whereas we have also
cases where the deviation from GOE is significant and of physical origin. In
the intermediate case of mixed classical dynamics we have a semiclassical
formula in the spirit of the Berry-Robnik (1984) surmise. Here the agreement
with theory is not good, partially due to the localization phenomena which are
expected to disappear in the semiclassical limit. We stress that even for
classically ergodic systems there is no global universality for the curvature
distribution, not even in the semiclassical limit.Comment: 19 pages, file in plain LaTeX, 15 figures available upon request
Submitted to J. Phys. A: Math. Ge
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