443 research outputs found
Wanted: standards for automatic reproducibility of computational experiments
Those seeking to reproduce a computational experiment often need to manually
look at the code to see how to build necessary libraries, configure parameters,
find data, and invoke the experiment; it is not automatic. Automatic
reproducibility is a more stringent goal, but working towards it would benefit
the community. This work discusses a machine-readable language for specifying
how to execute a computational experiment. We invite interested stakeholders to
discuss this language at https://github.com/charmoniumQ/execution-description .Comment: Submitted to SE4RS'23 Portland, O
General Neutralino NLSPs at the Early LHC
Gauge mediated supersymmetry breaking (GMSB) is a theoretically
well-motivated framework with rich and varied collider phenomenology. In this
paper, we study the Tevatron limits and LHC discovery potential for a wide
class of GMSB scenarios in which the next-to-lightest superpartner (NLSP) is a
promptly-decaying neutralino. These scenarios give rise to signatures involving
hard photons, 's, 's, jets and/or higgses, plus missing energy. In order
to characterize these signatures, we define a small number of minimal spectra,
in the context of General Gauge Mediation, which are parameterized by the mass
of the NLSP and the gluino. Using these minimal spectra, we determine the most
promising discovery channels for general neutralino NLSPs. We find that the
2010 dataset can already cover new ground with strong production for all NLSP
types. With the upcoming 2011-2012 dataset, we find that the LHC will also have
sensitivity to direct electroweak production of neutralino NLSPs.Comment: 26 page
An Early & Comprehensive Millimeter and Centimeter Wave and X-ray Study of Supernova 2011dh: A Non-Equipartition Blastwave Expanding into A Massive Stellar Wind
Only a handful of supernovae (SNe) have been studied in multi-wavelength from
radio to X-rays, starting a few days after explosion. The early detection and
classification of the nearby type IIb SN2011dh/PTF11eon in M51 provides a
unique opportunity to conduct such observations. We present detailed data
obtained at the youngest phase ever of a core-collapse supernova (days 3 to 12
after explosion) in the radio, millimeter and X-rays; when combined with
optical data, this allows us to explore the early evolution of the SN blast
wave and its surroundings. Our analysis shows that the expanding supernova
shockwave does not exhibit equipartition (e_e/e_B ~ 1000), and is expanding
into circumstellar material that is consistent with a density profile falling
like R^-2. Within modeling uncertainties we find an average velocity of the
fast parts of the ejecta of 15,000 +/- 1800 km/s, contrary to previous
analysis. This velocity places SN 2011dh in an intermediate blast-wave regime
between the previously defined compact and extended SN IIb subtypes. Our
results highlight the importance of early (~ 1 day) high-frequency observations
of future events. Moreover, we show the importance of combined radio/X-ray
observations for determining the microphysics ratio e_e/e_B.Comment: 9 pages, 5 figures, submitted to Ap
The Spatial Distribution of Coalescing Neutron Star Binaries: Implications for Gamma-Ray Bursts
We find the distribution of coalescence times, birthrates, spatial
velocities, and subsequent radial offsets of coalescing neutron stars (NSs) in
various galactic potentials accounting for large asymmetric kicks introduced
during a supernovae. The birthrates of bound NS-NS binaries are quite sensitive
to the magnitude of the kick velocities but are, nevertheless, similar (~10 per
Galaxy per Myr) to previous population synthesis studies. The distribution of
merger times since zero-age main sequence is, however, relatively insensitive
to the choice of kick velocities. With a median merger time of ~100 Myr, we
find that compact binaries should closely trace the star formation rate in the
Universe.
In a range of plausible galactic potentials (M_galaxy > 3 x 10^10 M_solar)
the median radial offset of a NS-NS mergers is less than 10 kpc. At a redshift
of z=1 (with H_0 = 65 km/s/Mpc and Omega = 0.2), this means that half the
coalescences should occur within ~1.3 arcsec from the host galaxy. In all but
the most shallow potentials, ninety percent of NS-NS binaries merge within 30
kpc of the host. We find that although the spatial distribution of coalescing
neutron star binaries is consistent with the close spatial association of known
optical afterglows of gamma-ray bursts (GRBs) with faint galaxies, a
non-negligible fraction (~15 percent) of GRBs should occur well outside (>30
kpc) dwarf galaxy hosts. Extinction due to dust in the host, projection of
offsets, and a range in interstellar medium densities confound the true
distribution of NS-NS mergers around galaxies with an observable set of optical
transients/galaxy offsets.Comment: Accepted to MNRAS (12 Jan 1999
A Stealth Supersymmetry Sampler
The LHC has strongly constrained models of supersymmetry with traditional
missing energy signatures. We present a variety of models that realize the
concept of Stealth Supersymmetry, i.e. models with R-parity in which one or
more nearly-supersymmetric particles (a "stealth sector") lead to collider
signatures with only a small amount of missing energy. The simplest realization
involves low-scale supersymmetry breaking, with an R-odd particle decaying to
its superpartner and a soft gravitino. We clarify the stealth mechanism and its
differences from compressed supersymmetry and explain the requirements for
stealth models with high-scale supersymmetry breaking, in which the soft
invisible particle is not a gravitino. We also discuss new and distinctive
classes of stealth models that couple through a baryon portal or Z' gauge
interactions. Finally, we present updated limits on stealth supersymmetry in
light of current LHC searches.Comment: 45 pages, 16 figure
Decaying into the Hidden Sector
The existence of light hidden sectors is an exciting possibility that may be
tested in the near future. If DM is allowed to decay into such a hidden sector
through GUT suppressed operators, it can accommodate the recent cosmic ray
observations without over-producing antiprotons or interfering with the
attractive features of the thermal WIMP. Models of this kind are simple to
construct, generic and evade all astrophysical bounds. We provide tools for
constructing such models and present several distinct examples. The light
hidden spectrum and DM couplings can be probed in the near future, by measuring
astrophysical photon and neutrino fluxes. These indirect signatures are
complimentary to the direct production signals, such as lepton jets, predicted
by these models.Comment: 40 pages, 5 figure
A Significantly off-center Ni56 Distribution for the Low-Luminosity Type Ia Supernova SN 2016brx from the 100IAS survey
We present nebular-phase spectra of the Type Ia supernova (SN Ia) 2016brx, a
member of the 1991bg-like subclass that lies at the faint end of the SN Ia
luminosity function. Nebular spectra are available for only three other
1991bg-like SNe, and their Co line centers are all within <~ 500 km/s of each
other. In contrast, the nebular Co line center of SN 2016brx is blue-shifted by
>1500 km/s compared to them and by ~1200 km/s compared to the rest frame. This
is a significant shift relative to the narrow nebular line velocity dispersion
of <~ 2000 km/s of these SNe. The large range of nebular line shifts implies
that the Ni56 in the ejecta of SN 1991bg-like events is off-center by ~1000
km/s rather than universally centrally confined as previously suggested. With
the addition of SN 2016brx, the Co nebular line shapes of 1991bg-like objects
appear to connect with the brighter SNe Ia that show double-peak profiles,
hinting at a continuous distribution of line profiles among SNe Ia. One class
of models to produce both off-center and bi-modal Ni56 distributions is
collisions of white dwarfs with unequal and equal masses.Comment: Minor Changes. Accepted by MNRAS Lette
The Reproducibility of a Kinematically-Derived Axis of the Knee versus Digitized Anatomical Landmarks using a Knee Navigation System
Component position is critical to longevity of knee arthroplasties. Femoral component rotation is typically referenced from the transepicondylar axis (TEA), the anterior-posterior (AP) axis or the posterior condylar axis. Other studies have shown high variability in locating the TEA while proposing digitization of other landmarks such as the AP axis as a less-variable reference. This study uses a navigation system to compare the reproducibility of computing a kinematically-derived, navigated knee axis (NKA) to digitizing the TEA and AP axis. Twelve knees from unembalmed cadavers were tested. Four arthroplasty surgeons digitized the femoral epicondyles and the AP axis direction as well as flexed and extended the knee repeatedly to allow for NKA determination. The variance of the NKA axis determined under neutral loading conditions was smaller than the variance of the TEA axis when the kinematics were measured in the closed surgical condition (P<0.001). However, varus, valgus, and internal loading of the leg increased the variability of the NKA. Distraction of the leg during knee flexion and extension preserved the low variability of the NKA. In conclusion, a kinematically-derived NKA under neutral or distraction loading is more reproducible than the TEA and AP axis determined by digitization
American Thoracic Society 2019 Pediatric Core Curriculum
The American Thoracic Society Pediatric Core Curriculum updates clinicians annually in pediatric pulmonary disease in a 3 to 4 year recurring cycle of topics. The 2019 course was presented in May during the Annual International Conference. An American Board of Pediatrics Maintenance of Certification module and a continuing medical education exercise covering the contents of the Core Curriculum can be accessed online at www.thoracic.org.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152541/1/ppul24482_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152541/2/ppul24482.pd
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