551 research outputs found
Continuous Centrifuge Decelerator for Polar Molecules
Producing large samples of slow molecules from thermal-velocity ensembles is
a formidable challenge. Here we employ a centrifugal force to produce a
continuous molecular beam with a high flux at near-zero velocities. We
demonstrate deceleration of three electrically guided molecular species,
CHF, CFH, and CFCCH, with input velocities of up to
to obtain beams with velocities below
and intensities of several .
The centrifuge decelerator is easy to operate and can, in principle, slow down
any guidable particle. It has the potential to become a standard technique for
continuous deceleration of molecules.Comment: 5 pages, 4 figures; version accepted for publication in PR
Fast solutions for the first-passage distribution of diffusion models with space-time-dependent drift functions and time-dependent boundaries
Efficient numerical approximation of a non-regular Fokker–Planck equation associated with first-passage time distributions
Efficient numerical approximation of a non-regular Fokker–Planck equation associated with first-passage time distributions
Why Do Only Some Galaxy Clusters Have Cool Cores?
Flux-limited X-ray samples indicate that about half of rich galaxy clusters
have cool cores. Why do only some clusters have cool cores while others do not?
In this paper, cosmological N-body + Eulerian hydrodynamic simulations,
including radiative cooling and heating, are used to address this question as
we examine the formation and evolution of cool core (CC) and non-cool core
(NCC) clusters. These adaptive mesh refinement simulations produce both CC and
NCC clusters in the same volume. They have a peak resolution of 15.6 h^{-1} kpc
within a (256 h^{-1} Mpc)^3 box. Our simulations suggest that there are
important evolutionary differences between CC clusters and their NCC
counterparts. Many of the numerical CC clusters accreted mass more slowly over
time and grew enhanced cool cores via hierarchical mergers; when late major
mergers occurred, the CC's survived the collisions. By contrast, NCC clusters
experienced major mergers early in their evolution that destroyed embryonic
cool cores and produced conditions that prevented CC re-formation. As a result,
our simulations predict observationally testable distinctions in the properties
of CC and NCC beyond the core regions in clusters. In particular, we find
differences between CC versus NCC clusters in the shapes of X-ray surface
brightness profiles, between the temperatures and hardness ratios beyond the
cores, between the distribution of masses, and between their supercluster
environs. It also appears that CC clusters are no closer to hydrostatic
equilibrium than NCC clusters, an issue important for precision cosmology
measurements.Comment: 17 emulateapj pages, 17 figures, replaced with version accepted to
Ap
Application of quasi-Monte Carlo methods to PDEs with random coefficients -- an overview and tutorial
This article provides a high-level overview of some recent works on the
application of quasi-Monte Carlo (QMC) methods to PDEs with random
coefficients. It is based on an in-depth survey of a similar title by the same
authors, with an accompanying software package which is also briefly discussed
here. Embedded in this article is a step-by-step tutorial of the required
analysis for the setting known as the uniform case with first order QMC rules.
The aim of this article is to provide an easy entry point for QMC experts
wanting to start research in this direction and for PDE analysts and
practitioners wanting to tap into contemporary QMC theory and methods.Comment: arXiv admin note: text overlap with arXiv:1606.0661
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