29,756 research outputs found
Improved sparse approximation over quasi-incoherent dictionaries
This paper discusses a new greedy algorithm for solving the sparse approximation problem over quasi-incoherent dictionaries. These dictionaries consist of waveforms that are uncorrelated "on average," and they provide a natural generalization of incoherent dictionaries. The algorithm provides strong guarantees on the quality of the approximations it produces, unlike most other methods for sparse approximation. Moreover, very efficient implementations are possible via approximate nearest-neighbor data structure
Condensation cyclization reactions of electron deficient aromatics. 4: Tricyclic nitropropene nitronates from the reaction of phloroglucinol and cycloalkanones with sym-trinitrobenzene
Interesting similarities have been shown between the reactions of sym-trinitrobenzene with cycloalkanones, and with phloroglucinol. Previously unsuspected common intermediates have been shown to intervene. The structurally similar products in each case are tricyclic nitropropene nitronates. Protonation of these yields the corresponding nitronic acids in certain instances
Dynamics of few-body states in a medium
Strongly interacting matter such as nuclear or quark matter leads to few-body
bound states and correlations of the constituents. As a consequence quantum
chromodynamics has a rich phase structure with spontaneous symmetry breaking,
superconductivity, condensates of different kinds. All this appears in many
astrophysical scenarios. Among them is the formation of hadrns during the early
stage of the Universe, the structure of a neutron star, the formation of nuclei
during a supernova explosion. Some of these extreme conditions can be simulated
in heavy ion colliders. To treat such a hot and dense system we use the Green
function formalism of many-body theory. It turns out that a systematic Dyson
expansion of the Green functions leads to modified few-body equations that are
capable to describe phase transitions, condensates, cluster formation and more.
These equations include self energy corrections and Pauli blocking. We apply
this method to nonrelativistic and relativistic matter. The latter one is
treated on the light front. Because of the medium and the inevitable truncation
of space, the few-body dynamics and states depend on the thermodynamic
parameters of the medium.Comment: 3 pages, 2 figures, talk presented at the 19th European Conference on
Few-Body System
Shellflow. I. The Convergence of the Velocity Field at 6000 km/s
We present the first results from the Shellflow program, an all-sky
Tully-Fisher (TF) peculiar velocity survey of 276 Sb-Sc galaxies with redshifts
between 4500 and 7000 km/s. Shellflow was designed to minimize systematic
errors between observing runs and between telescopes, thereby removing the
possibility of a spurious bulk flow caused by data inhomogeneity. A fit to the
data yields a bulk flow amplitude V_bulk = 70{+100}{-70} km/s (1 sigma error)
with respect to the Cosmic Microwave Background, i.e., consistent with being at
rest. At the 95% confidence level, the flow amplitude is < 300 km/s. Our
results are insensitive to which Galactic extinction maps we use, and to the
parameterization of the TF relation. The larger bulk motion found in analyses
of the Mark III peculiar velocity catalog are thus likely to be due to
non-uniformities between the subsamples making up Mark III. The absence of bulk
flow is consistent with the study of Giovanelli and collaborators and flow
field predictions from the observed distribution of IRAS galaxies.Comment: Accepted version for publication in ApJ. Includes an epitaph for
Jeffrey Alan Willick (Oct 8, 1959 - Jun 18, 2000
124-Color Super-resolution Imaging by Engineering DNA-PAINT Blinking Kinetics
Optical super-resolution techniques reach unprecedented spatial resolution down to a few nanometers. However, efficient multiplexing strategies for the simultaneous detection of hundreds of molecular species are still elusive. Here, we introduce an entirely new approach to multiplexed super-resolution microscopy by designing the blinking behavior of targets with engineered binding frequency and duration in DNA-PAINT. We assay this kinetic barcoding approach in silico and in vitro using DNA origami structures, show the applicability for multiplexed RNA and protein detection in cells, and finally experimentally demonstrate 124-plex super-resolution imaging within minutes.We thank Martin Spitaler and the imaging facility of the MPI of Biochemistry for confocal imaging support
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