162 research outputs found
Measuring Thread Timing to Assess the Feasibility of Early-bird Message Delivery
Early-bird communication is a communication/computation overlap technique
that combines fine-grained communication with partitioned communication to
improve application run-time. Communication is divided among the compute
threads such that each individual thread can initiate transmission of its
portion of the data as soon as it is complete rather than waiting for all of
the threads. However, the benefit of early-bird communication depends on the
completion timing of the individual threads. In this paper, we measure and
evaluate the potential overlap, the idle time each thread experiences between
finishing their computation and the final thread finishing. These measurements
help us understand whether a given application could benefit from early-bird
communication. We present our technique for gathering this data and evaluate
data collected from three proxy applications: MiniFE, MiniMD, and MiniQMC. To
characterize the behavior of these workloads, we study the thread timings at
both a macro level, i.e., across all threads across all runs of an application,
and a micro level, i.e., within a single process of a single run. We observe
that these applications exhibit significantly different behavior. While MiniFE
and MiniQMC appear to be well-suited for early-bird communication because of
their wider thread distribution and more frequent laggard threads, the behavior
of MiniMD may limit its ability to leverage early-bird communication
The adenovirus E4-ORF3 protein stimulates SUMOylation of general transcription factor TFII-I to direct proteasomal degradation
Modulation of host cell transcription, translation, and posttranslational modification processes is critical for the ability of many viruses to replicate efficiently within host cells. The human adenovirus (Ad) early region 4 open reading frame 3 (E4-ORF3) protein forms unique inclusions throughout the nuclei of infected cells and inhibits the antiviral Mre11-Rad50-Nbs1 DNA repair complex through relocalization. E4-ORF3 also induces SUMOylation of Mre11 and Nbs1. We recently identified additional cellular targets of E4-ORF3 and found that E4-ORF3 stimulates ubiquitin-like modification of 41 cellular proteins involved in a wide variety of processes. Among the proteins most abundantly modified in an E4-ORF3-dependent manner was the general transcription factor IIâI (TFII-I). Analysis of Ad-infected cells revealed that E4-ORF3 induces TFII-I relocalization and SUMOylation early during infection. In the present study, we explored the relationship between E4-ORF3 and TFII-I. We found that Ad infection or ectopic E4-ORF3 expression leads to SUMOylation of TFII-I that precedes a rapid decline in TFII-I protein levels. We also show that E4-ORF3 is required for ubiquitination of TFII-I and subsequent proteasomal degradation. This is the first evidence that E4-ORF3 regulates ubiquitination. Interestingly, we found that E4-ORF3 modulation of TFII-I occurs in diverse cell types but only E4-ORF3 of Ad species C regulates TFII-I, providing critical insight into the mechanism by which E4-ORF3 targets TFII-I. Finally, we show that E4-ORF3 stimulates the activity of a TFII-I-repressed viral promoter during infection. Our results characterize a novel mechanism of TFII-I regulation by Ad and highlight how a viral protein can modulate a critical cellular transcription factor during infection
Recommended from our members
An examination of content similarity within the memory of HPC applications.
Memory content similarity has been e ectively exploited for more than a decade to reduce memory consumption. By consolidating duplicate and similar pages in the address space of an application, we can reduce the amount of memory it consumes without negatively a ecting the application's perception of the memory resources available to it. In addition to memory de-duplication, there may be many other ways that we can exploit memory content similarity to improve system characteristics. In this paper, we examine the memory content similarity of several HPC applications. By characterizing the memory contents of these applications, we hope to provide a basis for ef- forts to e ectively exploit memory content similarity to improve system performance beyond memory deduplication. We show that several applications exhibit signi cant similarity and consider the source of the similarity
Discovery of a Probable CH Star in the Globular Cluster M14 and Implications for the Evolution of Binaries in Clusters
We report the discovery of a probable CH star in the core of the Galactic
globular cluster M14, identified from an integrated-light spectrum of the
cluster obtained with the MOS spectrograph on the CFHT. From a high- resolution
echelle spectrum of the same star obtained with the Hydra fiber positioner and
bench spectrograph on the WIYN telescope, we measure a radial velocity of
km s. Although this velocity is inconsistent with
published estimates of the systemic radial velocity of M14 (eg, km s), we use high-precision Hydra velocities for 20 stars
in the central 2.6 arcminutes of M14 to calculate improved values for the
cluster mean velocity and one-dimensional velocity dispersion: km
s and km s, respectively. Both the star's location
near the tip of the red giant branch in the cluster color magnitude diagram and
its radial velocity therefore argue for membership in M14. Since the
intermediate-resolution MOS spectrum shows not only enhanced CH absorption but
also strong Swan bands of C, M14 joins Omega Cen as the only globular
clusters known to contain classical CH stars. Although evidence for its
duplicity must await additional radial velocity measurements, the CH star in
M14 is probably, like all field CH stars, a spectroscopic binary with a
degenerate (white dwarf) secondary. The candidate and confirmed CH stars in M14
and Omega Cen, and in a number of Galactic dSph galaxies, may then owe their
existence to the long timescales for the shrinking and coalescence of hard
binaries in low-concentration environments.Comment: Accepted to the Astrophysical Journal Letters. 13 pages, AAS LaTeX
and three postscript figures (numbers 2,3,4). Entire paper (including Figure
1) available at http://www.hia.nrc.ca/DAO/SCIENCE/science.htm
Dynamics of the Globular Cluster System Associated with M87 (NGC 4486). II. Analysis
We present a dynamical analysis of the globular cluster system associated
with M87 (= NGC 4486), the cD galaxy near the dynamical center of the Virgo
cluster. The analysis utilizes a new spectroscopic and photometric database
which is described in a companion paper (Hanes et al. 2001). Using a sample of
278 globular clusters with measured radial velocities and metallicities, and
new surface density profiles based on wide-field Washington photometry, we
study the dynamics of the M87 globular cluster system both globally --- for the
entire cluster sample --- and separately --- for the metal-rich and metal-poor
globular cluster samples. This constitutes the largest sample of radial
velocities for pure Population II tracers yet assembled for any galaxy. We
discuss the implications of our findings for models for the formation of giant
elliptical galaxies, globular cluster systems, and the Virgo cluster.
(ABRIDGED)Comment: 28 pages, 19 postscript figures, 1 jpeg image. See
http://www.physics.rutgers.edu/ast/ast-rap.html to download the manuscript
with higher quality figures. Accepted for publication in the Astrophysical
Journa
Hubble Space Telescope Observations of cD Galaxies and their Globular Cluster Systems
We have used WFPC2 on the Hubble Space Telescope to obtain F450W and F814W
images of four cD galaxies (NGC 541 in Abell 194, NGC 2832 in Abell 779, NGC
4839 in Abell 1656 and NGC 7768 in Abell 2666) in the range 5400 < cz < 8100 km
s^{-1}. For NGC 541, the HST data are supplemented by ground-based B and I
images obtained with the FORS1 on the VLT. We present surface brightness and
color profiles for each of the four galaxies, confirming their classification
as cD galaxies. Isophotal analyses reveal the presence of subarcsecond-scale
dust disks in the nuclei of NGC 541 and NGC 7768. Despite the extreme nature of
these galaxies in terms of spatial extent and luminosity, our analysis of their
globular cluster systems reveals no anomalies in terms of specific frequencies,
metallicity gradients, average metallicities, or the metallicity offset between
the globulars and the host galaxy. We show that the latter offset appears
roughly constant at \Delta [Fe/H] ~ 0.8 dex for early-type galaxies spanning a
luminosity range of roughly four orders of magnitude. We combine the globular
cluster metallicity distributions with an empirical technique described in a
series of earlier papers to investigate the form of the protogalactic mass
spectrum in these cD galaxies. We find that the observed GC metallicity
distributions are consistent with those expected if cD galaxies form through
the cannibalism of numerous galaxies and protogalactic fragments which formed
their stars and globular clusters before capture and disruption. However, the
properties of their GC systems suggest that dynamical friction is not the
primary mechanism by which these galaxies are assembled. We argue that cDs
instead form rapidly, via hierarchical merging, prior to cluster virialization.Comment: 36 pages, 20 postscript figures, uses emulateapj. Accepted for
publication in the Astronomical Journa
The SuperCam Remote Sensing Instrument Suite for Mars 2020
International audienceThe Mars 2020 rover, essentially a structural twin of MSL, is being built to a) characterize the geology and history of a new landing site on Mars, b) find and characterize ancient habitable environments, c) cache samples for eventual return to Earth, and d) demonstrate in-situ production of oxygen needed for human exploration. Remote-sensing instrumentation is needed to support the first three of these goals [1]. The SuperCam instrument meets these needs with a range of instrumentation including the highest-resolution remote imaging on the rover, two different techniques for determining mineralogy , and one technique to provide elemental compositions. All of these techniques are co-boresighted, providing rapid comprehensive characterization. In addition, for targets within 7 meters of the rover the laser shock waves brush away the dust, providing cleaner surfaces for analysis. SuperCam will use an advanced version of the AEGIS robotic target selection software
Towards standardized measurement of adverse events in spine surgery: conceptual model and pilot evaluation
BACKGROUND: Independent of efficacy, information on safety of surgical procedures is essential for informed choices. We seek to develop standardized methodology for describing the safety of spinal operations and apply these methods to study lumbar surgery. We present a conceptual model for evaluating the safety of spine surgery and describe development of tools to measure principal components of this model: (1) specifying outcome by explicit criteria for adverse event definition, mode of ascertainment, cause, severity, or preventability, and (2) quantitatively measuring predictors such as patient factors, comorbidity, severity of degenerative spine disease, and invasiveness of spine surgery. METHODS: We created operational definitions for 176 adverse occurrences and established multiple mechanisms for reporting them. We developed new methods to quantify the severity of adverse occurrences, degeneration of lumbar spine, and invasiveness of spinal procedures. Using kappa statistics and intra-class correlation coefficients, we assessed agreement for the following: four reviewers independently coding etiology, preventability, and severity for 141 adverse occurrences, two observers coding lumbar spine degenerative changes in 10 selected cases, and two researchers coding invasiveness of surgery for 50 initial cases. RESULTS: During the first six months of prospective surveillance, rigorous daily medical record reviews identified 92.6% of the adverse occurrences we recorded, and voluntary reports by providers identified 38.5% (surgeons reported 18.3%, inpatient rounding team reported 23.1%, and conferences discussed 6.1%). Trained observers had fair agreement in classifying etiology of 141 adverse occurrences into 18 categories (kappa = 0.35), but agreement was substantial (kappa â„ 0.61) for 4 specific categories: technical error, failure in communication, systems failure, and no error. Preventability assessment had moderate agreement (mean weighted kappa = 0.44). Adverse occurrence severity rating had fair agreement (mean weighted kappa = 0.33) when using a scale based on the JCAHO Sentinel Event Policy, but agreement was substantial for severity ratings on a new 11-point numerical severity scale (ICC = 0.74). There was excellent inter-rater agreement for a lumbar degenerative disease severity score (ICC = 0.98) and an index of surgery invasiveness (ICC = 0.99). CONCLUSION: Composite measures of disease severity and surgery invasiveness may allow development of risk-adjusted predictive models for adverse events in spine surgery. Standard measures of adverse events and risk adjustment may also facilitate post-marketing surveillance of spinal devices, effectiveness research, and quality improvement
- âŠ