5,245 research outputs found
Ablaze with love: a video documentary to sensitize the Church of the Nazarene to its heritage of gender mutuality in ministry
https://place.asburyseminary.edu/ecommonsatsdissertations/1636/thumbnail.jp
Spatiotemporal dynamics of quantum jumps with Rydberg atoms
We study the nonequilibrium dynamics of quantum jumps in a one-dimensional
chain of atoms. Each atom is driven on a strong transition to a short-lived
state and on a weak transition to a metastable state. We choose the metastable
state to be a Rydberg state so that when an atom jumps to the Rydberg state, it
inhibits or enhances jumps in the neighboring atoms. This leads to rich
spatiotemporal dynamics that are visible in the fluorescence of the strong
transition.Comment: 10 page
Coulomb crystallization in expanding laser-cooled neutral plasmas
We present long-time simulations of expanding ultracold neutral plasmas,
including a full treatment of the strongly coupled ion dynamics. Thereby, the
relaxation dynamics of the expanding laser-cooled plasma is studied, taking
into account elastic as well as inelastic collisions. It is demonstrated that,
depending on the initial conditions, the ionic component of the plasma may
exhibit short-range order or even a superimposed long-range order resulting in
concentric ion shells. In contrast to ionic plasmas confined in traps, the
shell structures are built up from the center of the plasma cloud rather than
from the periphery
Borromean rays and hyperplanes
Three disjoint rays in euclidean 3-space form Borromean rays provided their
union is knotted, but the union of any two components is unknotted. We
construct infinitely many Borromean rays, uncountably many of which are
pairwise inequivalent. We obtain uncountably many Borromean hyperplanes.Comment: 41 pages, 30 figures (19 with captions, 11 inline
Nonlinear force-free modelling: influence of inaccuracies in the measured magnetic vector
Context: Solar magnetic fields are regularly extrapolated into the corona
starting from photospheric magnetic measurements that can suffer from
significant uncertainties. Aims: Here we study how inaccuracies introduced into
the maps of the photospheric magnetic vector from the inversion of ideal and
noisy Stokes parameters influence the extrapolation of nonlinear force-free
magnetic fields. Methods: We compute nonlinear force-free magnetic fields based
on simulated vector magnetograms, which have been produced by the inversion of
Stokes profiles, computed froma 3-D radiation MHD simulation snapshot. These
extrapolations are compared with extrapolations starting directly from the
field in the MHD simulations, which is our reference. We investigate how line
formation and instrumental effects such as noise, limited spatial resolution
and the effect of employing a filter instrument influence the resulting
magnetic field structure. The comparison is done qualitatively by visual
inspection of the magnetic field distribution and quantitatively by different
metrics. Results: The reconstructed field is most accurate if ideal Stokes data
are inverted and becomes less accurate if instrumental effects and noise are
included. The results demonstrate that the non-linear force-free field
extrapolation method tested here is relatively insensitive to the effects of
noise in measured polarization spectra at levels consistent with present-day
instruments. Conclusions heading: Our results show that we can reconstruct the
coronal magnetic field as a nonlinear force-free field from realistic
photospheric measurements with an accuracy of a few percent, at least in the
absence of sunspots.Comment: A&A, accepted, 9 Pages, 4 Figure
Two-Level Systems in Evaporated Amorphous Silicon
In -beam evaporated amorphous silicon (-Si), the densities of two-level
systems (TLS), and , determined from specific heat
and internal friction measurements, respectively, have been shown to
vary by over three orders of magnitude. Here we show that and
are proportional to each other with a constant of
proportionality that is consistent with the measurement time dependence
proposed by Black and Halperin and does not require the introduction of
additional anomalous TLS. However, and depend strongly
on the atomic density of the film () which depends on both film
thickness and growth temperature suggesting that the -Si structure is
heterogeneous with nanovoids or other lower density regions forming in a dense
amorphous network. A review of literature data shows that this atomic density
dependence is not unique to -Si. These findings suggest that TLS are not
intrinsic to an amorphous network but require a heterogeneous structure to
form
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