2,258 research outputs found
On the location of spectral edges in -periodic media
Periodic nd order ordinary differential operators on are known to
have the edges of their spectra to occur only at the spectra of periodic and
antiperiodic boundary value problems. The multi-dimensional analog of this
property is false, as was shown in a 2007 paper by some of the authors of this
article. However, one sometimes encounters the claims that in the case of a
single periodicity (i.e., with respect to the lattice ), the
property still holds, and spectral edges occur at the periodic and
anti-periodic spectra only. In this work we show that even in the simplest case
of quantum graphs this is not true. It is shown that this is true if the graph
consists of a chain of finite graphs connected by single edges, while if
the connections are formed by at least two edges, the spectral edges can
already occur away from the periodic and anti-periodic spectra.Comment: 9 pages, 5 figure
Online Court Records: Balancing Judicial Accountability and Privacy in an Age of Electronic Information
This Article examines the traditional balance courts have reached between the disclosure of information generated by the judicial process and the need at times to limit the disclosure of that information. The Article then examines how this traditional balance is upset when judicial information is placed online. The Article argues that as courts adapt to a world of electronic information, new rules and practices must be established to maintain the policies underlying the traditional balance. While there must continue to be a presumption of openness, courts must limit the disclosure of judicial information when it threatens the effective administration of justice and when necessary in order to protect the safety and privacy of individuals participating in the judicial process
AESTRA: Deep Learning for Precise Radial Velocity Estimation in the Presence of Stellar Activity
Stellar activity interferes with precise radial velocity measurements and
limits our ability to detect and characterize planets, particularly Earth-like
planets. We introduce \aestra (Auto-Encoding STellar Radial-velocity and
Activity), a deep learning method for precise radial velocity measurements. It
combines a spectrum auto-encoder, which learns to create realistic models of
the star's rest-frame spectrum, and a radial-velocity estimator, which learns
to identify true Doppler shifts in the presence of spurious shifts due to
line-profile variations. Being self-supervised, \aestra does not need "ground
truth" radial velocities for training, making it applicable to exoplanet host
stars for which the truth is unknown. In tests involving 1,000 simulated
spectra, \aestra can detect planetary signals as low as 0.1 m/s even in the
presence of 3 m/s of activity-induced noise and 0.3 m/s of photon noise per
spectrum.Comment: 14 pages, 12 figures. Accepted for publication in The Astronomical
Journa
On the location of spectral edges in Z-periodic media
Periodic second-order ordinary differential operators on R are known to have
the edges of their spectra to occur only at the spectra of periodic and antiperiodic
boundary value problems. The multi-dimensional analog of this
property is false, as was shown in a 2007 paper by some of the authors of
this paper. However, one sometimes encounters the claims that in the case of
a single periodicity (i.e., with respect to the lattice Z), the 1D property still
holds, and spectral edges occur at the periodic and anti-periodic spectra only.
In this work, we show that even in the simplest case of quantum graphs this is
not true. It is shown that this is true if the graph consists of a 1D chain of finite
graphs connected by single edges, while if the connections are formed by at
least two edges, the spectral edges can already occur away from the periodic
and anti-periodic spectra
Resolving the Surfaces of Extrasolar Planets With Secondary Eclipse Light Curves
We present a method that employs the secondary eclipse light curves of
transiting extrasolar planets to probe the spatial variation of their thermal
emission. This technique permits an observer to resolve the surface of the
planet without the need to spatially resolve its central star. We evaluate the
feasibility of this technique for the HD 209458 system [..]. We consider two
representations of the planetary thermal emission; a simple model parameterized
by a sinusoidal dependence on longitude and latitude, as well as the results of
a three-dimensional dynamical simulation of the planetary atmosphere previously
published by Cooper & Showman. We find that observations of the secondary
eclipse light curve are most sensitive to a longitudinal offset in the
geometric and photometric centroids of the hemisphere of the planet visible
near opposition. To quantify this signal, we define a new parameter, the
``uniform time offset,'' which measures the time lag between the observed
secondary eclipse and that predicted by a planet with a uniform surface flux
distribution. We compare the predicted amplitude of this parameter for HD
209458 with the precision with which it could be measured with IRAC. We find
that IRAC observations at 3.6um a single secondary eclipse should permit
sufficient precision to confirm or reject the Cooper & Showman model of the
surface flux distribution for this planet. We quantify the signal-to-noise
ratio for this offset in the remaining IRAC bands (4.5um, 5.8um, and 8.0um),
and find that a modest improvement in photometric precision (as might be
realized through observations of several eclipse events) should permit a
similarly robust detection.Comment: AASTeX 5.2, 24 pages, 5 figures, accepted for publication in ApJ; v2:
clarifications, updated to version accepted by ApJ; v3: try to reduce spacin
Cost-Utility Analysis of Cancer Prevention, Treatment, and Control
Substantial innovation related to cancer prevention and treatment has occurred in recent decades. However, these innovations have often come at a significant cost. Cost-utility analysis provides a useful framework to assess if the benefits from innovation are worth the additional cost. This systematic review on published cost-utility analyses related to cancer care is from 1988 through 2013. Analyses were conducted in 2013–2015
Collaborative Cloud Computing Framework for Health Data with Open Source Technologies
The proliferation of sensor technologies and advancements in data collection
methods have enabled the accumulation of very large amounts of data.
Increasingly, these datasets are considered for scientific research. However,
the design of the system architecture to achieve high performance in terms of
parallelization, query processing time, aggregation of heterogeneous data types
(e.g., time series, images, structured data, among others), and difficulty in
reproducing scientific research remain a major challenge. This is specifically
true for health sciences research, where the systems must be i) easy to use
with the flexibility to manipulate data at the most granular level, ii)
agnostic of programming language kernel, iii) scalable, and iv) compliant with
the HIPAA privacy law. In this paper, we review the existing literature for
such big data systems for scientific research in health sciences and identify
the gaps of the current system landscape. We propose a novel architecture for
software-hardware-data ecosystem using open source technologies such as Apache
Hadoop, Kubernetes and JupyterHub in a distributed environment. We also
evaluate the system using a large clinical data set of 69M patients.Comment: This paper is accepted in ACM-BCB 202
Coupled evolutions of the stellar obliquity, orbital distance, and planet's radius due to the Ohmic dissipation induced in a diamagnetic hot Jupiter around a magnetic T Tauri star
We revisit the calculation of the Ohmic dissipation in a hot Jupiter
presented in Laine et al. (2008) by considering more realistic interior
structures, stellar obliquity, and the resulting orbital evolution. In this
simplified approach, the young hot Jupiter of one Jupiter mass is modelled as a
diamagnetic sphere with a finite resistivity, orbiting across tilted stellar
magnetic dipole fields in vacuum. Since the induced Ohmic dissipation occurs
mostly near the planet's surface, we find that the dissipation is unable to
significantly expand the young hot Jupiter. Nevertheless, the planet inside a
small co-rotation orbital radius can undergo orbital decay by the dissipation
torque and finally overfill its Roche lobe during the T Tauri star phase. The
stellar obliquity can evolve significantly if the magnetic dipole is
parallel/anti-parallel to the stellar spin. Our results are validated by the
general torque-dissipation relation in the presence of the stellar obliquity.
We also run the fiducial model in Laine et al. (2008) and find that the
planet's radius is sustained at a nearly constant value by the Ohmic heating,
rather than being thermally expanded to the Roche radius as suggested by the
authors.Comment: about 40 pages, 10 figures, Accepted for publication in The
Astrophysical Journa
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