1,060 research outputs found
Open systems storage platforms
The building blocks for an open storage system includes a system platform, a selection of storage devices and interfaces, system software, and storage applications CONVEX storage systems are based on the DS Series Data Server systems. These systems are a variant of the C3200 supercomputer with expanded I/O capabilities. These systems support a variety of medium and high speed interfaces to networks and peripherals. System software is provided in the form of ConvexOS, a POSIX compliant derivative of 4.3BSD UNIX. Storage applications include products such as UNITREE and EMASS. With the DS Series of storage systems, Convex has developed a set of products which provide open system solutions for storage management applications. The systems are highly modular, assembled from off the shelf components with industry standard interfaces. The C Series system architecture provides a stable base, with the performance and reliability of a general purpose platform. This combination of a proven system architecture with a variety of choices in peripherals and application software allows wide flexibility in configurations, and delivers the benefits of open systems to the mass storage world
On the parabolic equation method in internal wave propagation
A parabolic equation for the propagation of periodic internal waves over
varying bottom topography is derived using the multiple-scale perturbation
method. Some computational aspects of the numerical implementation are
discussed. The results of numerical experiments on propagation of an incident
plane wave over a circular-type shoal are presented in comparison with the
analytical result, based on Born approximation.Comment: Submitted to Coastal Engineering. 16 pages, 5 figures. One figure was
excluded from article because of size problem
COMPARING THE OBSERVABLE PROPERTIES OF DWARF GALAXIES ON AND OFF THE ANDROMEDA PLANE
The thin, extended planes of satellite galaxies detected around both the
Milky Way and Andromeda are not a natural prediction of the LCDM paradigm.
Galaxies in these distinct planes may have formed and evolved in a different
way (e.g., tidally) to their off-plane neighbours. If this were the case, one
would expect the on- and off-plane dwarf galaxies in Andromeda to have
experienced different evolutionary histories, which should be reflected by the
chemistries, dynamics, and star formation histories of the two populations. In
this work, we present new, robust kinematic observations for 2 on-plane M31
dSphs (And XVI and XVII) and compile and compare all available observational
metrics for the on- and off-plane dwarfs to search for a signal that would
corroborate such a hypothesis. We find that, barring their spatial alignment,
the on- and off-plane Andromeda dwarf galaxies are indistinguishable from one
another, arguing against vastly different formative and evolutionary histories
for these two populations.Comment: 7 pages, 3 figures, accepted for publication in ApJ Letter
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Mothers behaving badly: chaotic hedonism and the crisis of neoliberal social reproduction
This article focuses on the significance of the plethora of representations of mothers ‘behaving badly’ in contemporary anglophone media texts, including the films Bad Moms, Fun Mom Dinner and Bad Mom’s Christmas, the book and online cartoons Hurrah for Gin and the recent TV comedy dramas Motherland, The Let Down and Catastrophe. All these media texts include representations of, first, mothers in the midst of highly chaotic everyday spaces where any smooth routine of domesticity is conspicuous by its absence; and second, mothers behaving hedonistically, usually through drinking and partying, behaviour that is more conventionally associated with men or women without children. After identifying the social type of the mother behaving badly (MBB), the article locates and analyses it in relation to several different social and cultural contexts. These contexts are: a neoliberal crisis in social reproduction marked by inequality and overwork; the continual if contested role of women as ‘foundation parents’; and the negotiation of longer-term discourses of female hedonism. The title gestures towards a popular British sitcom of the 1990s, Men Behaving Badly, which popularized the idea of the ‘new lad’; and this article suggests that the new lad’s counterpart, the ladette, is mutating into the mother behaving badly, or the ‘lad mom’. Asking what work this figure does now, in a later neoliberal context, it argues that the mother behaving badly is simultaneously indicative of a widening and liberating range of maternal subject positions and symptomatic of a profound contemporary crisis in social reproduction. By focusing on the classed and racialised dynamics of the MBB – by examining who exactly is permitted to be hedonistic, and how – and by considering the MBB’s limited and partial imagining of progressive social change, the article concludes by emphasizing the urgency of creating more connections between such discourses and ‘parents behaving politically’
Thinking about growth : a cognitive mapping approach to understanding small business development
School of Managemen
Satellite Survival in Highly Resolved Milky Way Class Halos
Surprisingly little is known about the origin and evolution of the Milky
Way's satellite galaxy companions. UV photoionisation, supernova feedback and
interactions with the larger host halo are all thought to play a role in
shaping the population of satellites that we observe today, but there is still
no consensus as to which of these effects, if any, dominates. In this paper, we
revisit the issue by re-simulating a Milky Way class dark matter (DM) halo with
unprecedented resolution. Our set of cosmological hydrodynamic Adaptive Mesh
Refinement (AMR) simulations, called the Nut suite, allows us to investigate
the effect of supernova feedback and UV photoionisation at high redshift with
sub-parsec resolution. We subsequently follow the effect of interactions with
the Milky Way-like halo using a lower spatial resolution (50pc) version of the
simulation down to z=0. This latter produces a population of simulated
satellites that we compare to the observed satellites of the Milky Way and M31.
We find that supernova feedback reduces star formation in the least massive
satellites but enhances it in the more massive ones. Photoionisation appears to
play a very minor role in suppressing star and galaxy formation in all
progenitors of satellite halos. By far the largest effect on the satellite
population is found to be the mass of the host and whether gas cooling is
included in the simulation or not. Indeed, inclusion of gas cooling
dramatically reduces the number of satellites captured at high redshift which
survive down to z=0.Comment: 22 pages, 16 figures, accepted for publication in MNRA
The Hubble Space Telescope Survey of M31 Satellite Galaxies. III. Calibrating the Horizontal Branch as an Age Indicator for Nearby Galaxies
We present a new method for measuring the mean age of old/intermediate
stellar populations in resolved, metal-poor () galaxies using only the morphology of the horizontal branch (HB) and an
estimate of the average metallicity. We calculate the ratio of blue-to-red HB
stars and the mass-weighted mean ages of 27 M31 satellite galaxies that have
star formation histories (SFHs) measured from Hubble Space Telescope-based
color-magnitude diagrams (CMDs) that include the oldest Main Sequence Turn-off
(MSTO) ages. We find a strong correlation between mean age, metallicity, and HB
morphology, for stellar populations older than ~Gyr. The correlation
allows us to predict a galaxy's mean age from its HB morphology to a precision
of ~Gyr. We validate our method by recovering the correct ages of
Local Group galaxies that have robust MSTO-based ages and are not in our
calibration sample. We also use our technique to measure the mean ages of
isolated field galaxies KKR25 (~Gyr) and VV124
(~Gyr), which indicate that their main star formation
episodes may have lasted several Gyr and support the picture that they achieved
their early-type characteristics (e.g., low gas content, low star formation
activity) in isolation and not through environment. Because the HB is
brighter than the oldest MSTO, our method can provide precise
characteristic ages of predominantly old galaxies at distances times
farther. We provide our calibrations in commonly used HST/ACS filters.Comment: 21 pages, 13 figures, 5 tables, submitted to Ap
Bridging the gap between low and high mass dwarf galaxies
While the dark matter content within the most massive giant and smallest
dwarf galaxies has been probed -- spanning a range of over one million in mass
-- an important observational gap remains for galaxies of intermediate mass.
This gap covers K band magnitudes of approximately -16 > M_K > -18 (for which
dwarf galaxies have B--K ~ 2). On the high mass side of the gap are dwarf
elliptical (dE) galaxies, that are dominated by stars in their inner regions.
While the low mass side includes dwarf spheroidal (dSph) galaxies that are dark
matter-dominated and ultra compact dwarf (UCD) objects that are star-dominated.
Evolutionary pathways across the gap have been suggested but remain largely
untested because the `gap' galaxies are faint, making dynamical measurements
very challenging. With long exposures on the Keck telescope using the ESI
instrument we have succeeded in bridging this gap by measuring the dynamical
mass for five dwarf galaxies with M_K ~ -17.5 (M_B ~ --15.5). With the
exception of our brightest dwarf galaxy, they possess relatively flat velocity
dispersion profiles of around 20 km/s. By examining their 2D scaling relations
and 3D fundamental manifold, we found that the sizes and velocity dispersions
of these gap galaxies reveal continuous trends from dE to dSph galaxies. We
conclude that low-luminosity dwarf elliptical galaxies are dominated by stars,
not by dark matter, within their half light radii. This finding can be
understood if internal feedback processes are operating most efficiently in gap
galaxies, gravitationally heating the centrally-located dark matter to larger
radii. Whereas external environmental processes, which can strip away stars,
have a greater influence on dSph galaxies resulting in their higher dark matter
fractions. Abridged.Comment: 20 pages, includes 12 figures, accepted for publication in MNRA
A Keck/DEIMOS spectroscopic survey of the faint M31 satellites And IX, And XI, And XII, and And XIII
We present the first spectroscopic analysis of the faint M31 satellite
galaxies, AndXI and AndXIII, and a reanalysis of existing spectroscopic data
for two further faint companions, And IX and AndXII. By combining data obtained
using the DEIMOS spectrograph mounted on the Keck II telescope with deep
photometry from the Suprime-Cam instrument on Subaru, we have calculated global
properties for the dwarfs, such as systemic velocities, metallicites and
half-light radii.We find each dwarf to be very metal poor ([Fe/H] -2 both
photometrically and spectroscopically, from their stacked spectrum), and as
such, they continue to follow the luminosity-metallicity relationship
established with brighter dwarfs. We are unable to resolve a dispersion for And
XI due to small sample size and low S/N, but we set a one sigma upper limit of
sigma-v <5 km/s. For And IX, And XII and And XIII we resolve velocity
dispersions of v=4.5 (+3.4,-3.2), 2.6(+5.1,-2.6) and 9.7(+8.9,-4.5) km/s, and
derive masses within the half light radii of 6.2(+5.3,-5.1)x10^6 Msun, 2.4
(+6.5,-2.4)x10^6 Msun and 1.1(+1.4,-0.7)x10^7 Msun respectively. We discuss
each satellite in the context of the Mateo relations for dwarf spheroidal
galaxies, and the Universal halo profiles established for Milky Way dwarfs
(Walker et al. 2009). For both galaxies, this sees them fall below the
Universal halo profiles of Walker et al. (2009). When combined with the
findings of McConnachie & Irwin (2006a), which reveal that the M31 satellites
are twice as extended (in terms of both half-light and tidal radii) as their
Milky Way counterparts, these results suggest that the satellite population of
the Andromeda system could inhabit halos that are significantly different from
those of the Milky Way in terms of their central densities (abridged).Comment: 26 pages, 18 figures, MNRAS submitte
Neurotoxic Effects of Tetrahydroisoquinolines and Underlying Mechanisms
Tetrahydropapaveroline (THP), a neurotoxic tetrahydroisoquinoline alkaloid formed by condensation between dopamine and dopaldehyde, has been speculated to cause Parkinson's disease and also to contribute to alcohol dependence. Having two catechol moieties, THP may readily undergo oxidation to form an o-quinone intermediate with concomitant production of reactive oxygen species, which can cause neuronal cell death and DNA damage. This review will deal with the current knowledge of neurotoxic effects of this endogenous alkaloid and underlying biochemical mechanisms
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