43 research outputs found
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Primary epidural lymphocyte-depleted Hodgkinâs lymphoma of the thoracic spine â presentation of a rare disease variant
Background: Lymphocyte-depleted Hodgkinâs lymphoma is the rarest form of classical Hodgkinâs lymphoma, accounting for < 1% of all cases. Patients often have advanced-stage disease at the time of presentation with an aggressive clinical course. Even more uncommon is primary extranodal disease and rarely it will be presenting with spinal cord compression. Case presentation: An 88-year-old Caucasian female presented with a history of upper back pain for several months and new onset bilateral leg numbness and weakness. MRI of the spine showed a dorsal epidural lesion with cord compression at T1-T4 with involvement of the paraspinal muscles. The patient received urgent surgical decompression, with final histopathology showing a lymphocyte-depleted Hodgkinâs lymphoma. Systemic work-up did not show evidence of nodal disease. Following surgery, she received a course of radiotherapy with good outcome. Conclusion: To the best of our knowledge, this is the first reported case of primary lymphocyte-depleted Hodgkin lymphoma presenting as epidural spinal cord compression. Our report, in conjunction with a review of the literature, suggests that surgical intervention is clearly indicated in de novo disease followed by radiotherapy
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
The Second APOKASC Catalog: The Empirical Approach
We present a catalog of stellar properties for a large sample of 6676 evolved
stars with APOGEE spectroscopic parameters and \textit{Kepler} asteroseismic
data analyzed using five independent techniques. Our data includes evolutionary
state, surface gravity, mean density, mass, radius, age, and the spectroscopic
and asteroseismic measurements used to derive them. We employ a new empirical
approach for combining asteroseismic measurements from different methods,
calibrating the inferred stellar parameters, and estimating uncertainties. With
high statistical significance, we find that asteroseismic parameters inferred
from the different pipelines have systematic offsets that are not removed by
accounting for differences in their solar reference values. We include
theoretically motivated corrections to the large frequency spacing () scaling relation, and we calibrate the zero point of the frequency of
maximum power () relation to be consistent with masses and radii
for members of star clusters. For most targets, the parameters returned by
different pipelines are in much better agreement than would be expected from
the pipeline-predicted random errors, but 22\% of them had at least one method
not return a result and a much larger measurement dispersion. This supports the
usage of multiple analysis techniques for asteroseismic stellar population
studies. The measured dispersion in mass estimates for fundamental calibrators
is consistent with our error model, which yields median random and systematic
mass uncertainties for RGB stars of order 4\%. Median random and systematic
mass uncertainties are at the 9\% and 8\% level respectively for RC stars.Comment: 29 pages, 26 figures. Submitted ApJSupp. Comments welcome. For access
to the main data table (Table 5) use
https://www.dropbox.com/s/k33td8ukefwy5tv/APOKASC2_Table5.txt?dl=0; for
access to the individual pipeline values (Table 6) use
https://www.dropbox.com/s/vl9s2p3obftrv8m/APOKASC2_Table6.txt?dl=
Nonequilibrium Dynamics of Symmetry Breaking in Lambda Phi^4 Field Theory
The time evolution of O(N) symmetric lambda Phi^4 scalar field theory is
studied in the large N limit. In this limit the mean field and two-point
correlation function evolve together as a self-consistent closed
Hamiltonian system, characterized by a Gaussian density matrix. The static part
of the effective Hamiltonian defines the True Effective Potential U_eff for
configurations far from thermal equilibrium. Numerically solving the time
evolution equations for energy densities corresponding to a quench in the
unstable spinodal region, we find results quite different from what might be
inferred from the equilibrium free energy ``effective'' potential F. Typical
time evolutions show effectively irreversible energy flow from the coherent
mean fields to the quantum fluctuating modes, due to the creation of massless
Goldstone bosons near threshold. The plasma frequency and collisionless damping
rate of the mean fields are calculated in terms of the particle number density
by a linear response analysis and compared with the numerical results.
Dephasing of the fluctuations leads also to the growth of an effective entropy
and the transition from quantum to classical behavior of the ensemble. In
addition to casting some light on fundamental issues of nonequilibrium quantum
statistical mechanics, the general framework presented in this work may be
applied to a study of the dynamics of second order phase transitions in a wide
variety of Landau-Ginsburg systems described by a scalar order parameter.Comment: 32 pages (21 figures), RevTeX (plus macro), uses eps
The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe
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The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library
Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 Julyâ2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGAâwe release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020â2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data
Fundamental relations for the velocity dispersion of stars in the Milky Way
We explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way, from combined studies of complementary surveys including GALAH, LAMOST, APOGEE, the NASA Kepler and K2 missions, and Gaia DR2. We find that different stellar samples, even though they target different tracer populations and employ a variety of age estimation techniques, follow the same set of fundamental relations. We provide the clearest evidence to date that, in addition to the well-known dependence on stellar age, the velocity dispersions of stars depend on orbital angular momentum Lz, metallicity and height above the plane |z|, and are well described by a multiplicatively separable functional form. The dispersions have a power-law dependence on age with exponents of 0.441±0.007 and 0.251±0.006 for Ïz and ÏR respectively, and the power law is valid even for the oldest stars. For the solar neighborhood stars, the apparent break in the power law for older stars, as seen in previous studies, is due to the anti-correlation of Lz with age. The dispersions decrease with increasing Lz until we reach the Sun's orbital angular momentum, after which Ïz increases (implying flaring in the outer disc) while ÏR flattens. For a given age, the dispersions increase with decreasing metallicity, suggesting that the dispersions increase with birth radius. The dispersions also increase linearly with |z|. The same set of relations that work in the solar neighborhood also work for stars between 3 < R/kpc < 20. Finally, the high-[α/Fe] stars follow the same relations as the low-[α/Fe] stars