33,717 research outputs found
Predicting Intermediate Storage Performance for Workflow Applications
Configuring a storage system to better serve an application is a challenging
task complicated by a multidimensional, discrete configuration space and the
high cost of space exploration (e.g., by running the application with different
storage configurations). To enable selecting the best configuration in a
reasonable time, we design an end-to-end performance prediction mechanism that
estimates the turn-around time of an application using storage system under a
given configuration. This approach focuses on a generic object-based storage
system design, supports exploring the impact of optimizations targeting
workflow applications (e.g., various data placement schemes) in addition to
other, more traditional, configuration knobs (e.g., stripe size or replication
level), and models the system operation at data-chunk and control message
level.
This paper presents our experience to date with designing and using this
prediction mechanism. We evaluate this mechanism using micro- as well as
synthetic benchmarks mimicking real workflow applications, and a real
application.. A preliminary evaluation shows that we are on a good track to
meet our objectives: it can scale to model a workflow application run on an
entire cluster while offering an over 200x speedup factor (normalized by
resource) compared to running the actual application, and can achieve, in the
limited number of scenarios we study, a prediction accuracy that enables
identifying the best storage system configuration
Transport properties of a two impurity system: a theoretical approach
A system of two interacting cobalt atoms, at varying distances, was studied
in a recent scanning tunneling microscope experiment by Bork et. al.[Nature
Phys. 7, 901 (2011)]. We propose a microscopic model that explains, for all
experimentally analyzed interatomic distances, the physics observed in these
experiments. Our proposal is based on the two-impurity Anderson model, with the
inclusion of a two-path geometry for charge transport. This many-body system is
treated in the finite-U slave boson mean-field approximation and the
logarithmic-discretization embedded-cluster approximation. We physically
characterize the different charge transport regimes of this system at various
interatomic distances and show that, as in the experiments, the features
observed in the transport properties depend on the presence of two impurities
but also on the existence of two conducting channels for electron transport. We
interpret the splitting observed in the conductance as the result of the
hybridization of the two Kondo resonances associated with each impurity.Comment: 5 pages, 5 figure
Transthyretin familial amyloid polyneuropathy impact on health-related quality of life
info:eu-repo/semantics/publishedVersio
Beyond open access: open discourse, the next great equalizer
The internet is expanding the realm of scientific publishing to include free and open public debate of published papers. Journals are beginning to support web posting of comments on their published articles and independent organizations are providing centralized web sites for posting comments about any published article. The trend promises to give one and all access to read and contribute to cutting edge scientific criticism and debate
Long-term Variability of HCO Masers in Star-forming Regions
We present results of a multi-epoch monitoring program on variability of
6cm formaldehyde (HCO) masers in the massive star forming region
NGC7538IRS1 from 2008 to 2015 conducted with the GBT, WSRT, and
VLA. We found that the similar variability behaviors of the two formaldehyde
maser velocity components in NGC7538IRS1 (which was pointed out by
Araya and collaborators in 2007) have continued. The possibility that the
variability is caused by changes in the maser amplification path in regions
with similar morphology and kinematics is discussed. We also observed
12.2GHz methanol and 22.2GHz water masers toward
NGC7538IRS1. The brightest maser components of CHOH and HO
species show a decrease in flux density as a function of time. The brightest
HCO maser component also shows a decrease in flux density and has a similar
LSR velocity to the brightest HO and 12.2GHz CHOH masers. The line
parameters of radio recombination lines and the 20.17 and 20.97GHz CHOH
transitions in NGC7538IRS1 are also reported. In addition, we
observed five other 6cm formaldehyde maser regions. We found no evidence of
significant variability of the 6cm masers in these regions with respect to
previous observations, the only possible exception being the maser in
G29.960.02. All six sources were also observed in the HCO
isotopologue transition of the 6cm HCO line; HCO absorption
was detected in five of the sources. Estimated column density ratios
[HCO]/[HCO] are reported.Comment: 29 pages, 9 figure
Knowledge and attitude towards the gradual reduction of salt in bread – an online survey
Aim: Assess knowledge and attitude towards the gradual reduction of salt
in bread and the potential impact on eating habits of children (6-18 years)
and their families, as part as a Health Impact Assessment pilot study.N/
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