352 research outputs found
HST/NICMOS Observations of Fast Infrared Flickering in the Microquasar GRS 1915+105
We report infrared observations of the microquasar GRS 1915+105 using the
NICMOS instrument of the Hubble Space Telescope during 9 visits in April-June
2003. During epochs of high X-ray/radio activity near the beginning and end of
this period, we find that the \um infrared flux is generally low ( mJy) and relatively steady. However, during the X-ray/radio ``plateau''
state between these epochs, we find that the infrared flux is significantly
higher ( mJy), and strongly variable. In particular, we find events
with amplitudes % occurring on timescales of s
(e-folding timescales of s). These flickering timescales are several
times faster than any previously-observed infrared variability in GRS 1915+105
and the IR variations exceed corresponding X-ray variations at the same () timescale. These results suggest an entirely new type of infrared
variability from this object. Based on the properties of this flickering, we
conclude that it arises in the plateau-state jet outflow itself, at a distance
AU from the accretion disk. We discuss the implications of this work and
the potential of further flickering observations for understanding jet
formation around black holes.Comment: 19 pages, incl. 4 figures; accepted for publication in Ap
Bringing Rad52 foci into focus
In 2007, we published the results of a genome-wide screen for ORFs that affect the frequency of Rad52 foci in yeast. That paper was published within the constraints of conventional online publishing tools, and it provided only a glimpse into the actual screen data. New tools in the JCB DataViewer now show how these data can—and should—be shared
Genome-wide association of familial late-onset alzheimer's disease replicates BIN1 and CLU and nominates CUGBP2 in interaction with APOE
Late-onset Alzheimer's disease (LOAD) is the most common form of dementia in the elderly. The National Institute of Aging-Late Onset Alzheimer's Disease Family Study and the National Cell Repository for Alzheimer's Disease conducted a joint genome-wide association study (GWAS) of multiplex LOAD families (3,839 affected and unaffected individuals from 992 families plus additional unrelated neurologically evaluated normal subjects) using the 610 IlluminaQuad panel. This cohort represents the largest family-based GWAS of LOAD to date, with analyses limited here to the European-American subjects. SNPs near APOE gave highly significant results (e.g., rs2075650, p = 3.2×10-81), but no other genome-wide significant evidence for association was obtained in the full sample. Analyses that stratified on APOE genotypes identified SNPs on chromosome 10p14 in CUGBP2 with genome-wide significant evidence for association within APOE ε4 homozygotes (e.g., rs201119, p = 1.5×10-8). Association in this gene was replicated in an independent sample consisting of three cohorts. There was evidence of association for recently-reported LOAD risk loci, including BIN1 (rs7561528, p = 0.009 with, and p = 0.03 without, APOE adjustment) and CLU (rs11136000, p = 0.023 with, and p = 0.008 without, APOE adjustment), with weaker support for CR1. However, our results provide strong evidence that association with PICALM (rs3851179, p = 0.69 with, and p = 0.039 without, APOE adjustment) and EXOC3L2 is affected by correlation with APOE, and thus may represent spurious association. Our results indicate that genetic structure coupled with ascertainment bias resulting from the strong APOE association affect genome-wide results and interpretation of some recently reported associations. We show that a locus such as APOE, with large effects and strong association with disease, can lead to samples that require appropriate adjustment for this locus to avoid both false positive and false negative evidence of association. We suggest that similar adjustments may also be needed for many other large multi-site studies. © 2011 Wijsman et al
Association of operative approach with postoperative outcomes in neonates undergoing surgical repair of esophageal atresia and tracheoesophageal fistula
Introduction: Minimally invasive surgery (MIS) is gaining traction as a first-line approach to repair congenital anomalies. This study aims to evaluate outcomes for neonates undergoing open versus MIS repairs for esophageal atresia/tracheoesophageal fistula (EA/TEF).
Methods: Neonates undergoing EA/TEF repair from 2013-2020 were identified using the National Surgical Quality Improvement Program-Pediatric database. Proportions of operative approach (open vs. MIS) over time were analyzed. A propensity score-matched analysis using preoperative characteristics was performed and outcomes were compared including composite morbidity and reintervention rates (overall, major [thoracoscopy, thoracotomy], and minor [chest/feeding tube placement, endoscopy]) between operative approaches. Pearson’s chi-square or Fisher’s exact test were used as appropriate.
Results: We identified 1738 neonates who underwent EA/TEF repair. MIS utilization increased over time (p=0.019). Pre-match, neonates undergoing open repair were more likely premature, lower weight, and higher ASA class. Post-match, the groups were similar and included 183 neonates per group. MIS repair was associated with longer median operative time (206 vs. 180 minutes, p\u3c0.001), increased overall reintervention rates (MIS 9.8% vs. open 3.3%, p=0.011), and increased minor reintervention rates (MIS 7.7% vs. open 2.2%, p=0.016). There were no differences in composite morbidity (MIS 20.2% vs. open 26.8%, p=0.14) or major reinterventions (MIS 2.2% vs. open 1.1%, p=0.41).
Discussion: MIS is gaining traction as a first-line approach for neonates with EA/TEF but appears to be associated with a higher rate of reinterventions. Further studies evaluating MIS approaches for the repair of EA/TEF are needed to better define short and long-term outcomes to optimize patient selection
Localized Fermions and Anomaly Inflow via Deconstruction
We study fermion localization in gauge theory space. We consider four
dimensional product gauge groups in which light chiral fermions transform under
different gauge factors of the product group. This construction provides a
suppression of higher dimensional operators. For example, it can be used to
suppress dangerous proton decay operators. The anomalies associated with the
light chiral fermions are compensated by Wess-Zumino terms, which in the
continuum limit reproduce the five dimensional Chern-Simons term.Comment: 12 pages, minor changes to section
A comparative framework: how broadly applicable is a 'rigorous' critical junctures framework?
The paper tests Hogan and Doyle's (2007, 2008) framework for examining critical junctures. This framework sought to incorporate the concept of ideational change in understanding critical junctures. Until its development, frameworks utilized in identifying critical junctures were subjective, seeking only to identify crisis, and subsequent policy changes, arguing that one invariably led to the other, as both occurred around the same time. Hogan and Doyle (2007, 2008) hypothesized ideational change as an intermediating variable in their framework, determining if, and when, a crisis leads to radical policy change. Here we test this framework on cases similar to, but different from, those employed in developing the exemplar. This will enable us determine whether the framework's relegation of ideational change to a condition of crisis holds, or, if ideational change has more importance than is ascribed to it by this framework. This will also enable us determined if the framework itself is robust, and fit for the purposes it was designed to perform — identifying the nature of policy change
The Inertio-Elastic Planar Entry Flow of Low-Viscosity Elastic Fluids in Micro-fabricated Geometries
The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through
microfabricated planar abrupt contraction-expansions is investigated. The contraction
geometries are fabricated from a high-resolution chrome mask and cross-linked PDMS
gels using the tools of soft-lithography. The small length scales and high deformation
rates in the contraction throat lead to significant extensional flow effects even with dilute polymer solutions having time constants on the order of milliseconds. The dimensionless
extra pressure drop across the contraction increases by more than 200% and is
accompanied by significant upstream vortex growth. Streak photography and videomicroscopy
using epifluorescent particles shows that the flow ultimately becomes
unstable and three-dimensional. The moderate Reynolds numbers (0.03 ⤠Re ⤠44)
associated with these high Deborah number (0 ⤠De ⤠600) microfluidic flows results in
the exploration of new regions of the Re-De parameter space in which the effects of both
elasticity and inertia can be observed. Understanding such interactions will be
increasingly important in microfluidic applications involving complex fluids and can best
be interpreted in terms of the elasticity number, El = De/Re, which is independent of the
flow kinematics and depends only on the fluid rheology and the characteristic size of the
device.NS
The Discovery Potential of a Super B Factory
The Proceedings of the 2003 SLAC Workshops on flavor physics with a high
luminosity asymmetric e+e- collider. The sensitivity of flavor physics to
physics beyond the Standard Model is addressed in detail, in the context of the
improvement of experimental measurements and theoretical calculations.Comment: 476 pages. Printed copies may be obtained by request to
[email protected] . arXiv admin note: v2 appears to be identical to v
Should UI Eligibility Be Expanded to Low-Earning Workers? Evidence on Employment, Transfer Receipt, and Income from Administrative Data
Recent efforts to expand unemployment insurance (UI) eligibility are expected to increase low-earning workers’ access to UI. Although the expansion’s aim is to smooth the income and consumption of previously ineligible workers, it is possible that UI benefits simply displace other sources of income. Standard economic models predict that UI delays reemployment, thereby reducing wage income. Additionally, low-earning workers are often eligible for benefits from means-tested programs, which may decrease with UI benefits. In this paper, we estimate the impact of UI eligibility on employment, means-tested program participation, and income after job loss using a unique individual-level administrative data set from the state of Michigan. To identify a causal effect, we implement a fuzzy regression discontinuity design around the minimum earnings threshold for UI eligibility. Our main finding is that while UI eligibility increases jobless durations by up to 25 percent and temporarily lowers receipt of cash assistance (TANF) by 63 percent, the net impact on total income is still positive and large. In the quarter immediately following job loss, UI-eligible workers have 46-61 percent higher incomes than ineligibles
- …