185 research outputs found
A linear programming-based method for job shop scheduling
We present a decomposition heuristic for a large class of job shop scheduling problems. This heuristic utilizes information from the linear programming formulation of the associated optimal timing problem to solve subproblems, can be used for any objective function whose associated optimal timing problem can be expressed as a linear program (LP), and is particularly effective for objectives that include a component that is a function of individual operation
completion times. Using the proposed heuristic framework, we address job shop scheduling problems with a variety of objectives where intermediate holding costs need to be explicitly considered. In computational testing, we demonstrate the performance of our proposed solution approach
The Evolution of the Intracluster Medium Metallicity in Sunyaev-Zel'dovich-Selected Galaxy Clusters at 0 < z < 1.5
We present the results of an X-ray spectral analysis of 153 galaxy clusters
observed with the Chandra, XMM-Newton, and Suzaku space telescopes. These
clusters, which span 0 < z < 1.5, were drawn from a larger, mass-selected
sample of galaxy clusters discovered in the 2500 square degree South Pole
Telescope Sunyaev Zel'dovich (SPT-SZ) survey. With a total combined exposure
time of 9.1 Ms, these data yield the strongest constraints to date on the
evolution of the metal content of the intracluster medium (ICM). We find no
evidence for strong evolution in the global (r<R500) ICM metallicity (dZ/dz =
-0.06 +/- 0.04 Zsun), with a mean value at z=0.6 of = 0.23 +/- 0.01 Zsun
and a scatter of 0.08 +/- 0.01 Zsun. These results imply that >60% of the
metals in the ICM were already in place at z=1 (at 95% confidence), consistent
with the picture of an early (z>1) enrichment. We find, in agreement with
previous works, a significantly higher mean value for the metallicity in the
centers of cool core clusters versus non-cool core clusters. We find weak
evidence for evolution in the central metallicity of cool core clusters (dZ/dz
= -0.21 +/- 0.11 Zsun), which is sufficient to account for this enhanced
central metallicity over the past ~10 Gyr. We find no evidence for metallicity
evolution outside of the core (dZ/dz = -0.03 +/- 0.06 Zsun), and no significant
difference in the core-excised metallicity between cool core and non-cool core
clusters. This suggests that strong radio-mode AGN feedback does not
significantly alter the distribution of metals at r>0.15R500. Given the
limitations of current-generation X-ray telescopes in constraining the ICM
metallicity at z>1, significant improvements on this work will likely require
next-generation X-ray missions.Comment: 11 pages, 8 figures, 2 tables. Submitted to ApJ. Comments welcome
In vitro studies on antibacterial, antifungal, and cytotoxic properties of Leucas aspera
The leaves of the plant Leucas aspera belonging to the family Lamiaceae was studied to determine the in vitro antibacterial, antifungal, and cytotoxic properties. All extracts showed remarkable antibacterial activity against all of the studied organisms except Escherichia coli. Methanol extract showed stronger activity compared to ethyl acetate and petroleum ether extracts. It showed highest activity against Pseudomonas aeruginosa with zone of inhibition of 15 mm. The standard chloramphenicol did not show any activity against Shigella sonnei. But all the extracts showed moderate activity against this pathogen with zone of inhibition ranging from 10 to 13 mm. None of the extracts has shown any significant antifungal activity against the fungi. Incase of brine shrimp lethality bioassay, methanol extract showed the strongest cytotoxic effect with LC50 value of 4.28 μg/ml which is followed by ethyl acetate extract with LC50 value of 5.36 μg/ml. Thus it can be inferred that this plant may be a potential source of novel bioactive compounds
Embedded Commissioning for Building Design
Building Commissioning has a broad scope that extends to all phases of building delivery. We view commissioning
as a building delivery embedded process that persistently verifies and validates design intent throughout the building lifecycle process.
In the building lifecycle approach, buildings are considered to have cradle-to-grave life spans. They are modeled through a variety
of different developmental phases. In this research project, we intend to build the necessary theory and tools to support the
embedded commissioning process as a co-function of building lifecycle
The eROSITA Final Equatorial-Depth Survey (eFEDS): X-ray properties of Subaru optically-selected clusters
We present the results of a systematic X-ray analysis of optically rich
galaxy clusters detected by the Subaru HSC survey in the eROSITA eFEDS field.
Through a joint analysis of SRG/eROSITA and Subaru/HSC surveys, we aim to study
the dynamical status of the optically selected clusters and derive the cluster
scaling relations. The sample consists of 43 optically selected galaxy clusters
with a richness in . We systematically analyzed the X-ray
images and spectra using the eROSITA data. We identified the BCG using the
optical and far-infrared databases. We evaluated the cluster's dynamical status
by measuring the offset between the X-ray peak and BCG position, the gas
concentration, and the number of galaxy-density peaks. We studied the
luminosity-temperature and mass-luminosity relations based on eROSITA X-ray
spectra and HSC weak-lensing data analyses. Based on the these measurements,
the fraction of relaxed clusters is %, which is smaller than that of
the X-ray-selected cluster samples. After correcting for a selection bias due
to the richness cut, we obtained a shallow slope of , which is
consistent with the predictions of the self-similar model and the baseline
model incorporating a mass-concentration relation. The slope of
agrees with the above theoretical models and that of the
shear-selected clusters in the eFEDs field. Our analysis of high-richness
optical clusters yields a small fraction of relaxed clusters and a shallow
slope for the luminosity-temperature relation. This suggests that the average
X-ray properties of the optical clusters are likely to be different from those
observed in the X-ray samples. Thus, the joint eROSITA and HSC observations are
a powerful tool in extending the analysis to a larger sample and understanding
the selection effect with a view to establish cluster scaling relations.Comment: 12 pages, 4 figures, A&A accepted, minor correctio
Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395
The pre-merging system of galaxy clusters Abell 3391-Abell 3395 located at a
mean redshift of 0.053 has been observed at 1 GHz in an ASKAP/EMU Early Science
observation as well as in X-rays with eROSITA. The projected separation of the
X-ray peaks of the two clusters is 50 or 3.1 Mpc. Here we
present an inventory of interesting radio sources in this field around this
cluster merger. While the eROSITA observations provide clear indications of a
bridge of thermal gas between the clusters, neither ASKAP nor MWA observations
show any diffuse radio emission coinciding with the X-ray bridge. We derive an
upper limit on the radio emissivity in the bridge region of . A non-detection of diffuse radio emission in the X-ray bridge between
these two clusters has implications for particle-acceleration mechanisms in
cosmological large-scale structure. We also report extended or otherwise
noteworthy radio sources in the 30 deg field around Abell 3391-Abell 3395.
We identified 20 Giant Radio Galaxies, plus 7 candidates, with linear projected
sizes greater than 1 Mpc. The sky density of field radio galaxies with largest
linear sizes of Mpc is deg, three times higher than
previously reported. We find no evidence for a cosmological evolution of the
population of Giant Radio Galaxies. Moreover, we find seven candidates for
cluster radio relics and radio halos.Comment: Astronomy & Astrophysics, in pres
The eROSITA Final Equatorial Depth Survey (eFEDS) X-ray catalogue
Context. The eROSITA X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) observatory combines a large field of view and a large collecting area in the energy range between similar to 0.2 and similar to 8.0 keV. This gives the telescope the capability to perform uniform scanning observations of large sky areas. Aims. SRG/eROSITA performed scanning observations of the similar to 140 square degree eROSITA Final Equatorial Depth Survey field (the eFEDS field) as part of its performance verification phase ahead of the planned four years of all-sky scanning operations. The observing time of eFEDS was chosen to slightly exceed the depth expected in an equatorial field after the completion of the all-sky survey. While verifying the capability of eROSITA to perform large-area uniform surveys and serving as a test and training dataset to establish calibration and data analysis procedures, the eFEDS survey also constitutes the largest contiguous soft X-ray survey at this depth to date, supporting a range of early eROSITA survey science investigations. Here we (i) present a catalogue of detected X-ray sources in the eFEDS field providing information about source positions and extent, as well as fluxes in multiple energy bands, and (ii) document the suite of tools and procedures developed for eROSITA data processing and analysis, which were validated and optimised by the eFEDS work. Methods. The data were fed through a standard data processing pipeline, which applies X-ray event calibration and provides a set of standard calibrated data products. A multi-stage source detection procedure, building in part on experience from XMM-Newton, was optimised and calibrated by performing realistic simulations of the eROSITA eFEDS observations. Source fluxes were computed in multiple standard energy bands by forced point source fitting and aperture photometry. We cross-matched the eROSITA eFEDS source catalogue with previous XMM-ATLAS observations, which confirmed the excellent agreement of the eROSITA and XMM-ATLAS source fluxes. Astrometric corrections were performed by cross-matching the eROSITA source positions with an optical reference catalogue of quasars. Results. We present a primary catalogue of 27 910 X-ray sources (542 of which are significantly spatially extended) detected in the 0.2-2.3 keV energy range with detection likelihoods >= 6, corresponding to a (point source) flux limit of 6.5 x 10(-15) erg cm(-2 )s(-1) in the 0.5-2.0 keV energy band (80% completeness). A supplementary catalogue contains 4774 low-significance source candidates with detection likelihoods between 5 and 6. In addition, a hard-band sample of 246 sources detected in the energy range 2.3-5.0 keV above a detection likelihood of 10 is provided. In an appendix, we finally describe the dedicated data analysis software package, the eROSITA calibration database, and the standard calibrated data products.Peer reviewe
Understanding Dwarf Galaxies in order to Understand Dark Matter
Much progress has been made in recent years by the galaxy simulation
community in making realistic galaxies, mostly by more accurately capturing the
effects of baryons on the structural evolution of dark matter halos at high
resolutions. This progress has altered theoretical expectations for galaxy
evolution within a Cold Dark Matter (CDM) model, reconciling many earlier
discrepancies between theory and observations. Despite this reconciliation, CDM
may not be an accurate model for our Universe. Much more work must be done to
understand the predictions for galaxy formation within alternative dark matter
models.Comment: Refereed contribution to the Proceedings of the Simons Symposium on
Illuminating Dark Matter, to be published by Springe
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