221 research outputs found
Galactic star formation in parsec-scale resolution simulations
The interstellar medium (ISM) in galaxies is multiphase and cloudy, with
stars forming in the very dense, cold gas found in Giant Molecular Clouds
(GMCs). Simulating the evolution of an entire galaxy, however, is a
computational problem which covers many orders of magnitude, so many
simulations cannot reach densities high enough or temperatures low enough to
resolve this multiphase nature. Therefore, the formation of GMCs is not
captured and the resulting gas distribution is smooth, contrary to
observations. We investigate how star formation (SF) proceeds in simulated
galaxies when we obtain parsec-scale resolution and more successfully capture
the multiphase ISM. Both major mergers and the accretion of cold gas via
filaments are dominant contributors to a galaxy's total stellar budget and we
examine SF at high resolution in both of these contexts.Comment: 4 pages, 4 figures. To appear in the proceedings for IAU Symposium
270: Computational Star Formation (eds. Alves, Elmegreen, Girart, Trimble
An MDE-based framework to support the development of Mixed Interactive Systems
International audienceIn the domain of Human Computer Interaction (HCI), recent advances in sensors, communication technologies, miniaturization and computing capabilities have led to new and advanced forms of interaction. Among them, Mixed Interactive Systems (MIS), form a class of interactive systems that comprises augmented reality, tangible interfaces and ambient computing; MIS aim to take advantage of physical and digital worlds to promote a more transparent integration of interactive systems with the user's environment. Due to the constant change of technologies and the multiplicity of these interaction forms, specific development approaches have been developed. As a result, numerous taxonomies, frameworks, API and models have emerged, each one covering a specific and limited aspect of the development of MIS. To support a coherent use of these multiple development resources and contribute to the increasing popularity of MIS, we have developed a framework based on Model-Driven Engineering. The goal is to take advantage of Model-Driven Engineering (MDE) standards, methodology and tools to support the manipulation of complementary Domain Specific Languages (DSL), to organize and link the use of different design and implementation resources, and to ensure a rationalized implementation based on design choices. In this paper, we first summarize existing uses of MDE in HCI before focusing on five major benefits MDE can provide in a MIS development context. We then detail which MDE tools and resources support these benefits and thus form the pillars of the success of an MDE-based MIS development approach. Based on this analysis, we introduce our framework, called Guide-Me, and illustrate its use through a case study. This framework includes two design models. Model transformations are also included to link one model to another; as a result the frameworks coverage extends from the earliest design step to a software component-based prototyping platform. A toolset based on Eclipse Modeling Framework (EMF) that supports the use of the framework is also presented. We finally assess our MDE-based development process for MIS based on the five major MDE benefits for MIS
Computing Necessary Conditions for Near-Optimality in Capacity Expansion Planning Problems
peer reviewedIn power systems, large-scale optimisation problems are extensively used to plan for capacity expansion at the supranational level. However, their cost-optimal solutions are often not exploitable by decision-makers who are preferably looking for features of solutions that can accommodate their different requirements. This paper proposes a generic framework for addressing this problem. It is based on the concept of the epsilon-optimal feasible space of a given optimisation problem and the identification of necessary conditions over this space. This framework has been developed in a generic case, and an approach for solving this problem is subsequently described for a specific
case where conditions are constrained sums of variables. The approach is tested on a case study about capacity expansion planning of the European electricity network to determine necessary conditions on the minimal investments in transmission, storage and generation capacity.7. Affordable and clean energ
DynEmo: A video database of natural facial expressions of emotions.
International audienceDynEmo is a database available to the scientific community (https://DynEmo.liglab.fr/). It contains dynamic and natural emotional facial expressions (EFEs) displaying subjective affective states rated by both the expresser and observers. Methodological and contextual information is provided for each expression. This multimodal corpus meets psychological, ethical, and technical criteria. It is quite large, containing two sets of 233 and 125 recordings of EFE of ordinary Caucasian people (ages 25 to 65, 182 females and 176 males) filmed in natural but standardized conditions. In the Set 1, EFE recordings are associated with the affective state of the expresser (self-reported after the emotion inducing task, using dimensional, action readiness, and emotional labels items). In the Set 2, EFE recordings are both associated with the affective state of the expresser and with the time line (continuous annotations) of observers' ratings of the emotions displayed throughout the recording. The time line allows any researcher interested in analysing non-verbal human behavior to segment the expressions into emotions
Swirling around filaments: are large-scale structure vortices spinning up dark halos?
The kinematic analysis of dark matter and hydrodynamical simulations suggests
that the vorticity in large-scale structure is mostly confined to, and
predominantly aligned with their filaments, with an excess of probability of 20
per cent to have the angle between vorticity and filaments direction lower than
60 degrees relative to random orientations. The cross sections of these
filaments are typically partitioned into four quadrants with opposite vorticity
sign, arising from multiple flows, originating from neighbouring walls. The
spins of halos embedded within these filaments are consistently aligned with
this vorticity for any halo mass, with a stronger alignment for the most
massive structures up to an excess of probability of 165 per cent. On large
scales, adiabatic/cooling hydrodynamical simulations display the same vorticity
in the gas as in the dark matter. The global geometry of the flow within the
cosmic web is therefore qualitatively consistent with a spin acquisition for
smaller halos induced by this large-scale coherence, as argued in Codis et al.
(2012). In effect, secondary anisotropic infall (originating from the
vortex-rich filament within which these lower-mass halos form) dominates the
angular momentum budget of these halos. The transition mass from alignment to
orthogonality is related to the size of a given multi-flow region with a given
polarity. This transition may be reconciled with the standard tidal torque
theory if the latter is augmented so as to account for the larger scale
anisotropic environment of walls and filaments.Comment: 17 pages, 19 figures, 3 tables. accepted for publication in MNRA
The impact of ISM turbulence, clustered star formation and feedback on galaxy mass assembly through cold flows and mergers
Two of the dominant channels for galaxy mass assembly are cold flows (cold
gas supplied via the filaments of the cosmic web) and mergers. How these
processes combine in a cosmological setting, at both low and high redshift, to
produce the whole zoo of galaxies we observe is largely unknown. Indeed there
is still much to understand about the detailed physics of each process in
isolation. While these formation channels have been studied using
hydrodynamical simulations, here we study their impact on gas properties and
star formation (SF) with some of the first simulations that capture the
multiphase, cloudy nature of the interstellar medium (ISM), by virtue of their
high spatial resolution (and corresponding low temperature threshold). In this
regime, we examine the competition between cold flows and a
supernovae(SNe)-driven outflow in a very high-redshift galaxy (z {\approx} 9)
and study the evolution of equal-mass galaxy mergers at low and high redshift,
focusing on the induced SF. We find that SNe-driven outflows cannot reduce the
cold accretion at z {\approx} 9 and that SF is actually enhanced due to the
ensuing metal enrichment. We demonstrate how several recent observational
results on galaxy populations (e.g. enhanced HCN/CO ratios in ULIRGs, a
separate Kennicutt Schmidt (KS) sequence for starbursts and the population of
compact early type galaxies (ETGs) at high redshift) can be explained with
mechanisms captured in galaxy merger simulations, provided that the multiphase
nature of the ISM is resolved.Comment: To appear in the proceedings of IAUS 277, 'Tracing the ancestry of
galaxies', eds Carignan, Freeman & Combes. 4 pages, 2 figure
Cardiac metaiodobenzylguanidine uptake in patients with moderate chronic heart failure: relationship with peak oxygen uptake and prognosis
AbstractOBJECTIVESThis prospective study was undertaken to correlate early and late metaiodobenzylguanidine (MIBG) cardiac uptake with cardiac hemodynamics and exercise capacity in patients with heart failure and to compare their prognostic values with that of peak oxygen uptake (VO2).BACKGROUNDThe cardiac fixation of MIBG reflects presynaptic uptake and is reduced in heart failure. Whether it is related to exercise capacity and has better prognostic value than peak VO2is unknown.METHODSNinety-three patients with heart failure (ejection fraction <45%) were studied with planar MIBG imaging, cardiopulmonary exercise tests and hemodynamics (n = 44). Early (20 min) and late (4 h) MIBG acquisition, as well as their ratio (washout, WO) were determined. Prognostic value was assessed by survival curves (Kaplan–Meier method) and uni- and multivariate Cox analyses.RESULTSLate cardiac MIBG uptake was reduced (131 ± 20%, normal values 192 ± 42%) and correlated with ejection fraction (r = 0.49), cardiac index (r = 0.40) and pulmonary wedge pressure (r = −0.35). There was a significant correlation between peak VO2and MIBG uptake (r = 0.41, p < 0.0001). With a mean follow-up of 10 ± 8 months, both late MIBG uptake (p = 0.04) and peak VO2(p < 0.0001) were predictive of death or heart transplantation, but only peak VO2emerged by multivariate analysis. Neither early MIBG uptake nor WO yielded significant insights beyond those provided by late MIBG uptake.CONCLUSIONSMetaiodobenzylguanidine uptake has prognostic value in patients with wide ranges of heart failure, but peak VO2remains the most powerful prognostic index
Role Clarification Processes for Better Integration of Nurse Practitioners into Primary Healthcare Teams: A Multiple-Case Study
Cet article s'intéresse aux processus de clarification des rôles professionnels lors de l'intégration d'une infirmière praticienne spécialisée dans les équipes de première ligne au Québec.Role clarity is a crucial issue for effective interprofessional collaboration. Poorly defined roles can become a source of conflict
in clinical teams and reduce the effectiveness of care and services delivered to the population. Our objective in this paper is to
outline processes for clarifying professional roles when a new role is introduced into clinical teams, that of the primary healthcare
nurse practitioner (PHCNP). To support our empirical analysis we used the Canadian National Interprofessional Competency
Framework, which defines the essential components for role clarification among professionals. A qualitative multiple-case study
was conducted on six cases in which the PHCNP role was introduced into primary care teams. Data collection included 34
semistructured interviews with key informants involved in the implementation of the PHCNP role. Our results revealed that the
best performing primary care teams were those that used a variety of organizational and individual strategies to carry out role
clarification processes. From this study, we conclude that role clarification is both an organizational process to be developed and a
competency that each member of the primary care team must mobilize to ensure effective interprofessional collaboration.IRSC, MSS
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