10,379 research outputs found
Graded Lie algebras with finite polydepth
If A is a graded connected algebra then we define a new invariant, polydepth
A, which is finite if for some A-module M of at most
polynomial growth. Theorem 1: If f : X \to Y is a continuous map of finite
category, and if the orbits of H_*(\Omega Y) acting in the homology of the
homotopy fibre grow at most polynomially, then H_*(\Omega Y) has finite
polydepth. Theorem 2: If L is a graded Lie algebra and polydepth UL is finite
then either L is solvable and UL grows at most polynomially or else for some
integer d and all r, , some
Political Competition and Mirrleesian Income Taxation: A First Pass
We study Downsian competition in a Mirrleesian model of income taxation. The competing politicians may differ in competence. If politicians engage in vote-share maximization, the less competent politician’s policy proposals are attractive to the minority of rich agents, whereas those of the competent politician are attractive to the majority of poor agents. The less competent politician wins with positive probability, which gives rise to a political failure in the sense of Besley and Coate (1998). Political failures are avoided if politicians maximize winning probabilities. Nevertheless, the two equilibria cannot be Pareto-ranked, the minority may be better off under vote-share maximization.electoral competition, non-linear income taxation, candidate quality
What is the Shell Around R Coronae Borealis?
The hydrogen-deficient, carbon-rich R Coronae Borealis (RCB) stars are known
for being prolific producers of dust which causes their large iconic declines
in brightness. Several RCB stars, including R CrB, itself, have large extended
dust shells seen in the far-infrared. The origin of these shells is uncertain
but they may give us clues to the evolution of the RCB stars. The shells could
form in three possible ways. 1) they are fossil Planetary Nebula (PN) shells,
which would exist if RCB stars are the result of a final, helium-shell flash,
2) they are material left over from a white-dwarf merger event which formed the
RCB stars, or 3) they are material lost from the star during the RCB phase.
Arecibo 21-cm observations establish an upper limit on the column density of H
I in the R CrB shell implying a maximum shell mass of 0.3
M. A low-mass fossil PN shell is still a possible source of the shell
although it may not contain enough dust. The mass of gas lost during a
white-dwarf merger event will not condense enough dust to produce the observed
shell, assuming a reasonable gas-to-dust ratio. The third scenario where the
shell around R CrB has been produced during the star's RCB phase seems most
likely to produce the observed mass of dust and the observed size of the shell.
But this means that R CrB has been in its RCB phase for 10 yr.Comment: 5 pages, 2 figures, 2 tables, Accepted for publication in A
Dirichlet-Neumann and Neumann-Neumann Waveform Relaxation for the Wave Equation
We present a Waveform Relaxation (WR) version of the Dirichlet-Neumann and
Neumann-Neumann algorithms for the wave equation in space time. Each method is
based on a non-overlapping spatial domain decomposition, and the iteration
involves subdomain solves in space time with corresponding interface condition,
followed by a correction step. Using a Laplace transform argument, for a
particular relaxation parameter, we prove convergence of both algorithms in a
finite number of steps for finite time intervals. The number of steps depends
on the size of the subdomains and the time window length on which the
algorithms are employed. We illustrate the performance of the algorithms with
numerical results, and also show a comparison with classical and optimized
Schwarz WR methods.Comment: 8 pages, 6 figures, presented in 22nd International conference on
Domain Decomposition Methods, to appear in Domain Decomposition in Science
and Engineering XXII, LNCSE, Springer-Verlag 201
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A Universal Live Cell Barcoding-Platform for Multiplexed Human Single Cell Analysis.
Single-cell barcoding enables the combined processing and acquisition of multiple individual samples as one. This maximizes assay efficiency and eliminates technical variability in both sample preparation and analysis. Remaining challenges are the barcoding of live, unprocessed cells to increase downstream assay performance combined with the flexibility of the approach towards a broad range of cell types. To that end, we developed a novel antibody-based platform that allows the robust barcoding of live human cells for mass cytometry (CyTOF). By targeting both the MHC class I complex (beta-2-microglobulin) and a broadly expressed sodium-potassium ATPase-subunit (CD298) with platinum-conjugated antibodies, human immune cells, stem cells as well as tumor cells could be multiplexed in the same single-cell assay. In addition, we present a novel palladium-based covalent viability reagent compatible with this barcoding strategy. Altogether, this platform enables mass cytometry-based, live-cell barcoding across a multitude of human sample types and provides a scheme for multiplexed barcoding of human single-cell assays in general
Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly-doped silicon substrates
In this study we investigate magnetic properties, surface morphology and
crystal structure in iron nanoclusters electrodeposited on lightly-doped (100)
n-type silicon substrates. Our goal is to investigate the spin injection and
detection in the Fe/Si lateral structures. The samples obtained under electric
percolation were characterized by magnetoresistive and magnetic resonance
measurements with cycling the sweeping applied field in order to understand the
spin dynamics in the as-produced samples. The observed hysteresis in the
magnetic resonance spectra, plus the presence of a broad peak in the
non-saturated regime confirming the low field microwave absorption (LFMA), were
correlated to the peaks and slopes found in the magnetoresistance curves. The
results suggest long range spin injection and detection in low resistive
silicon and the magnetic resonance technique is herein introduced as a
promising tool for analysis of electric contactless magnetoresistive samples.Comment: 12 pages, 5 figure
Supermodes of Hexagonal Lattice Waveguide Arrays
We present a semi-analytical formulation for calculating the supermodes and
corresponding Bloch factors of light in hexagonal lattice photonic crystal
waveguide arrays. We then use this formulation to easily calculate dispersion
curves and predict propagation in systems too large to calculate using standard
numerical methods.Comment: Accepted by J. Opt. Soc. Am. B, DocID:160522.
http://www.opticsinfobase.org/abstract.cfm?msid=16052
Optimal stochastic modelling with unitary quantum dynamics
Identifying and extracting the past information relevant to the future
behaviour of stochastic processes is a central task in the quantitative
sciences. Quantum models offer a promising approach to this, allowing for
accurate simulation of future trajectories whilst using less past information
than any classical counterpart. Here we introduce a class of phase-enhanced
quantum models, representing the most general means of causal simulation with a
unitary quantum circuit. We show that the resulting constructions can display
advantages over previous state-of-art methods - both in the amount of
information they need to store about the past, and in the minimal memory
dimension they require to store this information. Moreover, we find that these
two features are generally competing factors in optimisation - leading to an
ambiguity in what constitutes the optimal model - a phenomenon that does not
manifest classically. Our results thus simultaneously offer new quantum
advantages for stochastic simulation, and illustrate further qualitative
differences in behaviour between classical and quantum notions of complexity.Comment: 9 pages, 5 figure
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