55,385 research outputs found
Semantic Squirrels
We argue that data should be acquired now. Every day that goes by data is lost. We propose Semantic Squirrels, a community-enabled low technology solution to data acquisition to achieve this data acquisition, while other more difficult problems wait to be resolved
Scaling behaviour in random non-commutative geometries
Random non-commutative geometries are a novel approach to taking a
non-perturbative path integral over geometries. They were introduced in
arxiv.org/abs/1510.01377, where a first examination was performed. During this
examination we found that some geometries show indications of a phase
transition. In this article we explore this phase transition further for
geometries of type , , and . We determine the pseudo
critical points of these geometries and explore how some of the observables
scale with the system size. We also undertake first steps towards understanding
the critical behaviour through correlations and in determining critical
exponents of the system.Comment: 16 pages, 16 figures (v2: updated after review
Results and Perspectives of the Auger Engineering Radio Array
The Auger Engineering Radio Array (AERA) is an extension of the Pierre Auger
Cosmic-Ray Observatory. It is used to detect radio emission from extensive air
showers with energies beyond eV in the MHz frequency band.
After three phases of deployment, AERA now consists of more than 150 autonomous
radio stations with different spacings, covering an area of about km.
It is located at the same site as other Auger low-energy detector extensions
enabling combinations with various other measurement techniques. The radio
array allows different technical schemes to be explored as well as
cross-calibration of our measurements with the established baseline detectors
of the Auger Observatory. We report on the most recent technological
developments and give an overview of the experimental results obtained with
AERA. In particular, we will present the measurement of the radiation energy,
i.e., the amount of energy that is emitted by the air shower in the form of
radio emission, and its dependence on the cosmic-ray energy by comparing with
the measurement of the the well-calibrated Auger surface detector. Furthermore,
we outline the relevance of this result for the absolute calibration of the
energy scale of cosmic-ray observatories.Comment: To be published in the Proceedings of the ARENA2016 conference,
Groningen, The Netherland
Observing observatories: web observatories should use linked data
Web Observatories are a major international scientific collaboration concerned with data sources of a heterogeneous nature, and often quite large. Of course, they are not the first such collaboration; the Web itself was born as a response to a similar scientific endeavor. It is therefore appropriate to look at other col-laborative activities, and try to learn and use the lessons they have learnt.We argue that Web Observatories should build in interoperability using current best practices right from the start. We also argue that Linked Data is a best practice, and can provide the basis for a research environment that will deliver the vision of a large group of cooperating Observatories, sharing data and re-search results to the benefit of all. In addition, we argue that the activity should not start with a major standardization process, but should grow around appro-priate standards as required
ARIANNA: Measurement of cosmic rays with a radio neutrino detector in Antarctica
The ARIANNA detector aims to detect neutrinos with energies above
\SI{e16}{eV} by instrumenting 0.5 Teratons of ice with a surface array of a
thousand independent radio detector stations in Antarctica. The Antarctic ice
is transparent to the radio signals caused by the Askaryan effect which allows
for a cost-effective instrumentation of large volumes. Several pilot stations
are currently operating successfully at the Moore's Bay site (Ross Ice Shelf)
and at the South Pole. As the ARIANNA detector stations are positioned at the
surface, the more abundant cosmic-ray air showers are also measured and serve
as a direct way to prove the capabilities of the detector. We will present
measured cosmic rays and will show how the incoming direction, polarization and
electric field of the cosmic-ray pulse can be reconstructed from single
detector stations comprising 4 upward and 4 downward facing LPDA antennas.Comment: Proceedings of the 8th International Conference on Acoustic and Radio
EeV Neutrino Detection Activities, ARENA 201
Boundary of Quantum Evolution under Decoherence
Relaxation effects impose fundamental limitations on our ability to
coherently control quantum mechanical phenomena. In this letter, we establish
physical limits on how closely can a quantum mechanical system be steered to a
desired target state in the presence of relaxation. In particular, we
explicitly compute the maximum coherence or polarization that can be
transferred between coupled nuclear spins in the presence of very general
decoherence mechanisms that include cross-correlated relaxation. We give
analytical expressions for the control laws (pulse sequences) which achieve
these physical limits and provide supporting experimental evidence.
Exploitation of cross-correlation effects has recently led to the development
of powerful methods in NMR spectroscopy to study very large biomolecules in
solution. We demonstrate with experiments that the optimal pulse sequences
provide significant gains over these state of the art methods, opening new
avenues for spectroscopy of much larger proteins. Surprisingly, in spite of
very large relaxation rates, optimal control can transfer coherence without any
loss when cross-correlated relaxation rates are tuned to auto-correlated
relaxation rates
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