15,929 research outputs found
The most massive galaxies in clusters are already fully grown at
By constructing scaling relations for galaxies in the massive cluster
MACSJ0717.5 at and comparing with those of Coma, we model the
luminosity evolution of the stellar populations and the structural evolution of
the galaxies. We calculate magnitudes, surface brightnesses and effective radii
using HST/ACS images and velocity dispersions using Gemini/GMOS spectra, and
present a catalogue of our measurements for 17 galaxies. We also generate
photometric catalogues for galaxies from the HST imaging. With
these, we construct the colour-magnitude relation, the fundamental plane, the
mass-to-light versus mass relation, the mass-size relation and the
mass-velocity dispersion relation for both clusters. We present a new, coherent
way of modelling these scaling relations simultaneously using a simple physical
model in order to infer the evolution in luminosity, size and velocity
dispersion as a function of redshift, and show that the data can be fully
accounted for with this model. We find that (a) the evolution in size and
velocity dispersion undergone by these galaxies between and is mild, with and , and (b) the stellar populations are old, Gyr,
with a Gyr dispersion in age, and are consistent with evolving purely
passively since with . The implication is that these galaxies formed their stars early and
subsequently grew dissipationlessly so as to have their mass already in place
by , and suggests a dominant role for dry mergers, which may have
accelerated the growth in these high-density cluster environments.Comment: 20 pages; accepted for publication in MNRA
Servitization and operations management : a service-dominant logic approach
Managing organisational performance in sectors such as equipment provision has become increasingly complex as competition has heightened and firms have felt pressure to add value through the provision of services (Baines et al, 2007; Howard and Caldwell, 2011;
Neely et al., 2011). This provision is commonly referred to as the servitization of manufacturing (Vandermerwe & Rada, 1988). By extending the traditional offering of equipment to include service activities however, underlying operational delivery systems and processes have become more complex to manage and co-ordinate. No longer are firms simply making and shipping products; they are now engaged in a more complex world of design and delivery (Neely et al., 2011). This study aims to explore servitization from a value perspective through the lens of Service-Dominant (S-D) logic, and to propose its implications for operations management
The radio emission from the Galaxy at 22 MHz
We present maps of the 22MHz radio emission between declinations -28d and
+80d, covering ~73% of the sky, derived from observations with the 22MHz
radiotelescope at the Dominion Radio Astrophysical Observatory (DRAO). The
resolution of the telescopt (EWxNS) is 1.1d x 1.7d secant(zenith angle). The
maps show the large scale features of the emission from the Galaxy including
the thick non-thermal disk, the North Polar Spur (NPS) and absorption due to
discrete HII regions and to an extended band of thermal electrons within 40d of
the Galactic centre. We give the flux densities of nine extended supernova
remnants shown on the maps
Contextual variety, Internet-of-things and the choice of tailoring over platform : mass customisation strategy in supply chain management
This paper considers the implications for Supply Chain Management from the development of the Internet of Things (IoT) or Internet Connected Objects (ICO). We focus on the opportunities and challenges arising from consumption data as a result of ICO and how this can be translated into a providerâs strategy of offering different varieties of products. In our model, we consider two possible strategies: tailoring strategy and platform strategy. Tailoring strategy implies that a provider produces multiple varieties of a product that meet consumersâ needs. Platform strategy depicts the providerâs actions in offering a flexible and standardised platform which enables consumersâ needs to be met by incorporating personal ICO data onto various customisable applications independently produced by other providers that could be called on in context and on demand. We derive conditions under which each of the strategies may be profitable for the provider through maximising consumersâ value. We conclude by considering the implications for SCM research and practice including an extension of postponement taxonomies to include the customer as the completer of the product
WISE J163940.83-684738.6: A Y Dwarf identified by Methane Imaging
We have used methane imaging techniques to identify the near-infrared
counterpart of the bright WISE source WISEJ163940.83-684738.6. The large proper
motion of this source (around 3.0arcsec/yr) has moved it, since its original
WISE identification, very close to a much brighter background star -- it
currently lies within 1.5" of the J=14.90+-0.04 star 2MASS16394085-6847446.
Observations in good seeing conditions using methane sensitive filters in the
near-infrared J-band with the FourStar instrument on the Magellan 6.5m Baade
telescope, however, have enabled us to detect a near-infrared counterpart. We
have defined a photometric system for use with the FourStar J2 and J3 filters,
and this photometry indicates strong methane absorption, which unequivocally
identifies it as the source of the WISE flux. Using these imaging observations
we were then able to steer this object down the slit of the FIRE spectrograph
on a night of 0.6" seeing, and so obtain near-infrared spectroscopy confirming
a Y0-Y0.5 spectral type. This is in line with the object's
near-infrared-to-WISE J3--W2 colour. Preliminary astrometry using both WISE and
FourStar data indicates a distance of 5.0+-0.5pc and a substantial tangential
velocity of 73+-8km/s. WISEJ163940.83-684738.6 is the brightest confirmed Y
dwarf in the WISE W2 passband and its distance measurement places it amongst
the lowest luminosity sources detected to date.Comment: Accepted for publication in The Astrophysical Journal, 20 September
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Micro-CT Image-Derived Metrics Quantify Arterial Wall Distensibility Reduction in a Rat Model of Pulmonary Hypertension
We developed methods to quantify arterial structural and mechanical properties in excised rat lungs and applied them to investigate the distensibility decrease accompanying chronic hypoxia-induced pulmonary hypertension. Lungs of control and hypertensive (three weeks 11% O2) animals were excised and a contrast agent introduced before micro-CT imaging with a special purpose scanner. For each lung, four 3D image data sets were obtained, each at a different intra-arterial contrast agent pressure. Vessel segment diameters and lengths were measured at all levels in the arterial tree hierarchy, and these data used to generate features sensitive to distensibility changes. Results indicate that measurements obtained from 3D micro-CT images can be used to quantify vessel biomechanical properties in this rat model of pulmonary hypertension and that distensibility is reduced by exposure to chronic hypoxia. Mechanical properties can be assessed in a localized fashion and quantified in a spatially-resolved way or as a single parameter describing the tree as a whole. Micro-CT is a nondestructive way to rapidly assess structural and mechanical properties of arteries in small animal organs maintained in a physiological state. Quantitative features measured by this method may provide valuable insights into the mechanisms causing the elevated pressures in pulmonary hypertension of differing etiologies and should become increasingly valuable tools in the study of complex phenotypes in small-animal models of important diseases such as hypertension
Unique Education and Workforce Development for NASA Engineers
NASA engineers are some of the world's best-educated graduates, responsible for technically complex, highly significant scientific programs. Even though these professionals are highly proficient in traditional analytical competencies, there is a unique opportunity to offer continuing education that further enhances their overall scientific minds. With a goal of maintaining the Agency's passionate, "best in class" engineering workforce, the NASA Academy of Program/Project & Engineering Leadership (APPEL) provides educational resources encouraging foundational learning, professional development, and knowledge sharing. NASA APPEL is currently partnering with the scientific community's most respected subject matter experts to expand its engineering curriculum beyond the analytics and specialized subsystems in the areas of: understanding NASA's overall vision and its fundamental basis, and the Agency initiatives supporting them; sharing NASA's vast reservoir of engineering experience, wisdom, and lessons learned; and innovatively designing hardware for manufacturability, assembly, and servicing. It takes collaboration and innovation to educate an organization that possesses such a rich and important history~and a future that is of great global interest. NASA APPEL strives to intellectually nurture the Agency's technical professionals, build its capacity for future performance, and exemplify its core values~alJ to better enable NASA to meet its strategic vision~and beyond
Putting Muscle Into The M In An MIS Program
Rapid technological changes put pressure on MIS programs in the nation to modify their course offerings. Limited budgets and increased demands on faculty mean that these faculty have to be highly innovative in obtaining resources to support their programs. The authors provide insight into how such limitations can be overcome. They also recommend that teaching theoretical concepts and methodologies should take precedence over merely training students on specific software tools. Flexibility in MIS programs must ensure that MIS graduates join the marketplace with relevant skills-both technical and sof
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