2,442 research outputs found
Generic Connectivity-Based CGRA Mapping via Integer Linear Programming
Coarse-grained reconfigurable architectures (CGRAs) are programmable logic
devices with large coarse-grained ALU-like logic blocks, and multi-bit
datapath-style routing. CGRAs often have relatively restricted data routing
networks, so they attract CAD mapping tools that use exact methods, such as
Integer Linear Programming (ILP). However, tools that target general
architectures must use large constraint systems to fully describe an
architecture's flexibility, resulting in lengthy run-times. In this paper, we
propose to derive connectivity information from an otherwise generic device
model, and use this to create simpler ILPs, which we combine in an iterative
schedule and retain most of the exactness of a fully-generic ILP approach. This
new approach has a speed-up geometric mean of 5.88x when considering benchmarks
that do not hit a time-limit of 7.5 hours on the fully-generic ILP, and 37.6x
otherwise. This was measured using the set of benchmarks used to originally
evaluate the fully-generic approach and several more benchmarks representing
computation tasks, over three different CGRA architectures. All run-times of
the new approach are less than 20 minutes, with 90th percentile time of 410
seconds. The proposed mapping techniques are integrated into, and evaluated
using the open-source CGRA-ME architecture modelling and exploration framework.Comment: 8 pages of content; 8 figures; 3 tables; to appear in FCCM 2019; Uses
the CGRA-ME framework at http://cgra-me.ece.utoronto.ca
Measuring the slopes of mass profiles for dwarf spheroidals in triaxial CDM potentials
We generate stellar distribution functions (DFs) in triaxial haloes in order
to examine the reliability of slopes inferred by applying mass estimators of the form (i.e. assuming spherical symmetry, where and are
luminous effective radius and global velocity dispersion, respectively) to two
stellar sub-populations independently tracing the same gravitational potential.
The DFs take the form , are dynamically stable, and are generated within
triaxial potentials corresponding directly to subhaloes formed in cosmological
dark-matter-only simulations of Milky Way and galaxy cluster haloes.
Additionally, we consider the effect of different tracer number density
profiles (cuspy and cored) on the inferred slopes of mass profiles. For the
isotropic DFs considered here, we find that halo triaxiality tends to introduce
an anti-correlation between and when estimated for a variety of
viewing angles. The net effect is a negligible contribution to the systematic
error associated with the slope of the mass profile, which continues to be
dominated by a bias toward greater overestimation of masses for
more-concentrated tracer populations. We demonstrate that simple mass estimates
for two distinct tracer populations can give reliable (and cosmologically
meaningful) lower limits for , irrespective of the degree of
triaxiality or shape of the tracer number density profile.Comment: 5 pages, 4 figures, submitted to MNRA
Nocturnal Mnemonics: Sleep and Hippocampal Memory Processing
As critical as waking brain function is to learning and memory, an established literature now describes an equally important yet complementary role for sleep in information processing. This overview examines the specific contribution of sleep to human hippocampal memory processing; both the detriments caused by a lack of sleep, and conversely, the proactive benefits that develop following the presence of sleep. First, a role for sleep before learning is discussed, preparing the hippocampus for initial memory encoding. Second, a role for sleep after learning is considered, modulating the post-encoding consolidation of hippocampal-dependent memory. Third, a model is outlined in which these encoding and consolidation operations are symbiotically accomplished, associated with specific NREM sleep physiological oscillations. As a result, the optimal network outcome is achieved: increasing hippocampal independence and hence overnight consolidation, while restoring next-day sparse hippocampal encoding capacity for renewed learning ability upon awakening. Finally, emerging evidence is considered suggesting that, unlike previous conceptions, sleep does not universally consolidate all information. Instead, and based on explicit as well as saliency cues during initial encoding, sleep executes the discriminatory offline consolidation only of select information. Consequently, sleep promotes the targeted strengthening of some memories while actively forgetting others; a proposal with significant theoretical and clinical ramifications
Sustaining an Organization in the Midst of Chaos
Sustainability is a popular topic that influences almost every area of life and industry. Using the 2008 recession as the crisis examined, we will take a look at how several leaders have handled economic, environmental, and organizational responsibility and sustainability in the midst of chaos. We will then tie those examples together within the realm of systems thinking, highlighting how leaders need to see the interconnected nature of systems in order to effectively respond to crises
Complexity Leadership: The First Two Decades
Complexity leadership, complex adaptive leadership, and adaptive leadership theories are related but separate streams of leadership research dating back four decades. This article reviews the first two decades. The research team searched academic literature within the business discipline for journal articles related to complex adaptive leadership, complexity leadership, and adaptive leadership, resulting in a sample of 778 articles. The researchers used multiple methods to analyze the articles, eventually conducting deductive analysis on a subset of nine articles published between 1982-2002.
Analysis from the sample revealed frustration by some leadership scholars over the ability of leadership theory to address practical leadership problems. Therefore, scholars called for and began to develop novel approaches beyond concepts of leader-follower influence. Scholars turned their attention to understanding the role of leadership within VUCA contexts. They began to conceive of organizations as open systems and to describe characteristics that leaders would need to be successful in complex adaptive systems. These early attempts set the stage for scholars to apply complexity theory to the study of leadership
The autism-linked UBE3A T485A mutant E3 ubiquitin ligase activates the Wnt/β-catenin pathway by inhibiting the proteasome
Sleep-Dependent Facilitation of Episodic Memory Details
While a role for sleep in declarative memory processing is established, the qualitative nature of this consolidation benefit, and the physiological mechanisms mediating it, remain debated. Here, we investigate the impact of sleep physiology on characteristics of episodic memory using an item- (memory elements) and context- (contextual details associated with those elements) learning paradigm; the latter being especially dependent on the hippocampus. Following back-to-back encoding of two word lists, each associated with a different context, participants were assigned to either a Nap-group, who obtained a 120-min nap, or a No Nap-group. Six hours post-encoding, participants performed a recognition test involving item-memory and context-memory judgments. In contrast to item-memory, which demonstrated no between-group differences, a significant benefit in context-memory developed in the Nap-group, the extent of which correlated both with the amount of stage-2 NREM sleep and frontal fast sleep-spindles. Furthermore, a difference was observed on the basis of word-list order, with the sleep benefit and associated physiological correlations being selective for the second word-list, learned last (most proximal to sleep). These findings suggest that sleep may preferentially benefit contextual (hippocampal-dependent) aspects of memory, supported by sleep-spindle oscillations, and that the temporal order of initial learning differentially determines subsequent offline consolidation
Space Motions of the Dwarf Spheroidal Galaxies Draco and Sculptor based on HST Proper Motions with ~10-year Time Baseline
We present new proper motion (PM) measurements of the dwarf spheroidal
galaxies (dSphs) Draco and Sculptor using multi-epoch images obtained with the
Hubble Space Telescope ACS/WFC. Our PM results have uncertainties far lower
than previous measurements, even made with the same instrument. The PM results
for Draco and Sculptor are (mu_W,mu_N)_Dra =
(-0.0562+/-0.0099,-0.1765+/-0.0100) mas/yr and (mu_W,mu_N)_Scl =
(-0.0296+/-0.0209,-0.1358 +/-0.0214) mas/yr. The implied Galactocentric
velocity vectors for Draco and Sculptor have radial and tangential components:
(V_rad,V_tan)_Dra = (-88.6,161.4) +/- (4.4,5.6) km/s; and (V_rad,V_tan)_Scl =
(72.6,200.2) +/- (1.3,10.8) km/s. We study the detailed orbital history of both
Draco and Sculptor via numerical orbit integrations. Orbital periods of Draco
and Sculptor are found to be 1-2 and 2-5 Gyrs, respectively, accounting for
uncertainties in the MW mass. We also study the influence of the Large
Magellanic Cloud (LMC) on the orbits of Draco and Sculptor. Overall, the
inclusion of the LMC increases the scatter in the orbital results. Based on our
calculations, Draco shows a rather wide range of orbital parameters depending
on the MW mass and inclusion/exclusion of the LMC, but Sculptor's orbit is very
well constrained with its most recent pericentric approach to the MW being
0.3-0.4 Gyr ago. Our new PMs imply that the orbital trajectories of both Draco
and Sculptor are confined within the Disk of Satellites (DoS), better so than
implied by earlier PM measurements, and likely rule out the possibility that
these two galaxies were accreted together as part of a tightly bound group.Comment: 17 pages, 8 figures, 6 tables. Accepted for publication in Ap
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