9,575 research outputs found
On the domain of the assembly map in algebraic K-theory
We compare the domain of the assembly map in algebraic K-theory with respect
to the family of finite subgroups with the domain of the assembly map with
respect to the family of virtually cyclic subgroups and prove that the former
is a direct summand of the later.Comment: Published by Algebraic and Geometric Topology at
http://www.maths.warwick.ac.uk/agt/AGTVol3/agt-3-35.abs.htm
Silicon solar cell development for low temperature and low illumination intensity operation, volume 1 Analysis report, 30 Jun. 1969 - 30 Apr. 1970
Operational performance of solar cell at low temperatures and under low illumination intensit
Offset frequency dynamics and phase noise properties of a self-referenced 10 GHz Ti:sapphire frequency comb
This paper shows the experimental details of the stabilization scheme that
allows full control of the repetition rate and the carrier-envelope offset
frequency of a 10 GHz frequency comb based on a femtosecond Ti:sapphire laser.
Octave-spanning spectra are produced in nonlinear microstructured optical
fiber, in spite of the reduced peak power associated with the 10 GHz repetition
rate. Improved stability of the broadened spectrum is obtained by
temperature-stabilization of the nonlinear optical fiber. The carrier-envelope
offset frequency and the repetition rate are simultaneously frequency
stabilized, and their short- and long-term stabilities are characterized. We
also measure the transfer of amplitude noise of the pump source to phase noise
on the offset frequency and verify an increased sensitivity of the offset
frequency to pump power modulation compared to systems with lower repetition
rate. Finally, we discuss merits of this 10 GHz system for the generation of
low-phase-noise microwaves
Bayesian Model Comparison and Analysis of the Galactic Disk Population of Gamma-Ray Millisecond Pulsars
Pulsed emission from almost one hundred millisecond pulsars (MSPs) has been
detected in -rays by the Fermi Large-Area Telescope. The global
properties of this population remain relatively unconstrained despite many
attempts to model their spatial and luminosity distributions. We perform here a
self-consistent Bayesian analysis of both the spatial distribution and
luminosity function simultaneously. Distance uncertainties, arising from errors
in the parallax measurement or Galactic electron-density model, are
marginalized over. We provide a public Python package for calculating distance
uncertainties to pulsars derived using the dispersion measure by accounting for
the uncertainties in Galactic electron-density model YMW16. Finally, we use
multiple parameterizations for the MSP population and perform Bayesian model
comparison, finding that a broken power law luminosity function with Lorimer
spatial profile are preferred over multiple other parameterizations used in the
past. The best-fit spatial distribution and number of -ray MSPs is
consistent with results for the radio population of MSPs.Comment: 13 pages, 8 figures, 3 tables + Appendix. Public code and source list
available from http://github.com/tedwards2412/MSPDis
The Role of Allelopathy on the Vegetational Composition of Disturbed Sites on the Samuel H. Ordway Memorial Prairie
The presence of large numbers of cattle in prairie sites can lead to the trampling and destruction of native vegetation in some areas. These damaged, or disturbed sites are typically invaded by a variety of undesirable alien plant species. Many of the alien plant species possess allopathic mechanisms. These allopathic mechanisms enable the alien species to dominate the disturbed sites, and prevent the re-establishment of native plant species. Attempts are currently underway to preserve remaining tracts of native prairie in South Dakota. The Samuel H. Ordway, Jr. Memorial Prairie in McPherson county is one such tract, and is the research site of this study. The tall and mid-grass prairies of the eastern Dakotas were historically maintained by grazing pressure and periodic fires. The primary management tool used at Ordway Prairie is limited grazing with cattle to simulate native herbivore grazing pressures. Burning is not currently a significant management tool. This research was conducted to identify the presence and distribution of allelopathic alien species in disturbed sites resulting from overgrazing by cattle Ordway Prairie. Recommendations will be made regarding management techniques designed to reduce the dominance of disturbed sites by alien species
Probabilistic Linear Solvers: A Unifying View
Several recent works have developed a new, probabilistic interpretation for
numerical algorithms solving linear systems in which the solution is inferred
in a Bayesian framework, either directly or by inferring the unknown action of
the matrix inverse. These approaches have typically focused on replicating the
behavior of the conjugate gradient method as a prototypical iterative method.
In this work surprisingly general conditions for equivalence of these disparate
methods are presented. We also describe connections between probabilistic
linear solvers and projection methods for linear systems, providing a
probabilistic interpretation of a far more general class of iterative methods.
In particular, this provides such an interpretation of the generalised minimum
residual method. A probabilistic view of preconditioning is also introduced.
These developments unify the literature on probabilistic linear solvers, and
provide foundational connections to the literature on iterative solvers for
linear systems
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