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 H2_2CO Masers in Star-forming Regions

We present results of a multi-epoch monitoring program on variability of 6$\,$cm formaldehyde (H$_2$CO) masers in the massive star forming region NGC$\,$7538$\,$IRS$\,$1 from 2008 to 2015 conducted with the GBT, WSRT, and VLA. We found that the similar variability behaviors of the two formaldehyde maser velocity components in NGC$\,$7538$\,$IRS$\,$1 (which was pointed out by Araya and collaborators in 2007) have continued. The possibility that the variability is caused by changes in the maser amplification path in regions with similar morphology and kinematics is discussed. We also observed 12.2$\,$GHz methanol and 22.2$\,$GHz water masers toward NGC$\,$7538$\,$IRS$\,$1. The brightest maser components of CH$_3$OH and H$_2$O species show a decrease in flux density as a function of time. The brightest H$_2$CO maser component also shows a decrease in flux density and has a similar LSR velocity to the brightest H$_2$O and 12.2$\,$GHz CH$_3$OH masers. The line parameters of radio recombination lines and the 20.17 and 20.97$\,$GHz CH$_3$OH transitions in NGC$\,$7538$\,$IRS$\,$1 are also reported. In addition, we observed five other 6$\,$cm formaldehyde maser regions. We found no evidence of significant variability of the 6$\,$cm masers in these regions with respect to previous observations, the only possible exception being the maser in G29.96$-$0.02. All six sources were also observed in the H$_2^{13}$CO isotopologue transition of the 6$\,$cm H$_2$CO line; H$_2^{13}$CO absorption was detected in five of the sources. Estimated column density ratios [H$_2^{12}$CO]/[H$_2^{13}$CO] 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/