6,161 research outputs found
Three-body effects in the Hoyle-state decay
We use a sequential -matrix model to describe the breakup of the Hoyle
state into three particles via the ground state of . It
is shown that even in a sequential picture, features resembling a direct
breakup branch appear in the phase-space distribution of the
particles. We construct a toy model to describe the Coulomb interaction in the
three-body final state and its effects on the decay spectrum are investigated.
The framework is also used to predict the phase-space distribution of the
particles emitted in a direct breakup of the Hoyle state and the
possibility of interference between a direct and sequential branch is
discussed. Our numerical results are compared to the current upper limit on the
direct decay branch determined in recent experiments
Using baseline-dependent window functions for data compression and field-of-interest shaping in radio interferometry
In radio interferometry, observed visibilities are intrinsically sampled at
some interval in time and frequency. Modern interferometers are capable of
producing data at very high time and frequency resolution; practical limits on
storage and computation costs require that some form of data compression be
imposed. The traditional form of compression is a simple averaging of the
visibilities over coarser time and frequency bins. This has an undesired side
effect: the resulting averaged visibilities "decorrelate", and do so
differently depending on the baseline length and averaging interval. This
translates into a non-trivial signature in the image domain known as
"smearing", which manifests itself as an attenuation in amplitude towards
off-centre sources. With the increasing fields of view and/or longer baselines
employed in modern and future instruments, the trade-off between data rate and
smearing becomes increasingly unfavourable. In this work we investigate
alternative approaches to low-loss data compression. We show that averaging of
the visibility data can be treated as a form of convolution by a boxcar-like
window function, and that by employing alternative baseline-dependent window
functions a more optimal interferometer smearing response may be induced. In
particular, we show improved amplitude response over a chosen field of
interest, and better attenuation of sources outside the field of interest. The
main cost of this technique is a reduction in nominal sensitivity; we
investigate the smearing vs. sensitivity trade-off, and show that in certain
regimes a favourable compromise can be achieved. We show the application of
this technique to simulated data from the Karl G. Jansky Very Large Array (VLA)
and the European Very-long-baseline interferometry Network (EVN)
Multi-directional sorting modes in deterministic lateral displacement devices
Deterministic lateral displacement (DLD) devices separate micrometer-scale
particles in solution based on their size using a laminar microfluidic flow in
an array of obstacles. We investigate array geometries with rational row-shift
fractions in DLD devices by use of a simple model including both advection and
diffusion. Our model predicts novel multi-directional sorting modes that could
be experimentally tested in high-throughput DLD devices containing obstacles
that are much smaller than the separation between obstacles
A ddc-type condition beyond the K\"ahler realm
This paper introduces a generalization of the ddc-condition for complex
manifolds. Like the ddc-condition, it admits a diverse collection of
characterizations, and is robust under numerous geometric constructions. Most
notably, it is an open property with respect to small deformations. The
condition is satisfied by a wide range of complex manifolds including all
compact complex surfaces and all compact Vaisman manifolds. These last examples
are studied in detail, where the entire bicomplex structure is determined,
yielding several corollaries of geometric interest.Comment: Comments welcome
Nearest neighbor embedding with different time delays
A nearest neighbor based selection of time delays for phase space
reconstruction is proposed and compared to the standard use of time delayed
mutual information. The possibility of using different time delays for
consecutive dimensions is considered. A case study of numerically generated
solutions of the Lorenz system is used for illustration. The effect of
contamination with various levels of additive Gaussian white noise is
discussed.Comment: 4 pages, 5 figures, updated to final versio
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