5,476 research outputs found
The measurement of training opportunities course outcomes: an effective policy tool?
Training Opportunities is an active labour market policy initiative, and part of a response to the entrenched problems of unemployment in Aotearoa New Zealand. The funding and implementation of Training Opportunities are determined in part by a particular system for measuring course outcomes. This paper argues that this measuring system should not be used for policy development, due to measurement errors and problems assigning causality to the intervention. Consequently, various disincentives arise that contradict the objectives of Training Opportunities. While accountability is important, the over-reliance on the narrowly defined Training Opportunities outcomes undermines the ability of providers to assist the unemployed, and thereby contribute to the policy goals of reducing unemployment and labour market disadvantage in New Zealand
Framing Social Values:\ud An Experimental Study of Culture and Cognition
How and why does a given social value come to shape the way an individual thinks, feels,and acts in a specific social situation? This study links ideas from Goffmanâs frame analysis to other lines of research, proposing that dramatic narratives of variable content, vividness,and language-in-use produce variation in the accessibility of schematic, internal cultural frameworks, and, thereby, variation in the social value frames that gain situational primacy. Hypotheses derived from the argument are experimentally supported, and results encourage further research on the process of social value framing, which operates as a person crosses oundaries in the complex subcultural mosaic
Internal dynamics and membership of the NGC 3603 Young Cluster from microarcsecond astrometry
We have analyzed two epochs of HST/WFPC2 observations of the young Galactic
starburst cluster in NGC 3603 with the aim to study its internal dynamics and
stellar population. Relative proper motions measured over 10.15 yrs of more
than 800 stars enable us to distinguish cluster members from field stars. The
best-fitting isochrone yields Av=4.6-4.7 mag, a distance of 6.6-6.9 kpc, and an
age of 1 Myr for NGC 3603 Young Cluster (NYC). We identify
pre-main-sequence/main-sequence transition stars located in the short-lived
radiative-convective gap, which in the NYC occurs in the mass range 3.5-3.8
Msun. We also identify a sparse population of stars with an age of 4 Myr, which
appear to be the lower mass counterparts to previously discovered blue
supergiants located in the giant HII region NGC 3603. For the first time, we
are able to measure the internal velocity dispersion of a starburst cluster
from 234 stars with I < 18.5 mag to {\sigma}_pm1D=141+/-27 {\mu}as/yr
(4.5+/-0.8 km/s at a distance of 6.75 kpc). As stars with masses between 1.7
and 9 Msun all exhibit the same velocity dispersion, the cluster stars have not
yet reached equipartition of kinetic energy (i.e., the cluster is not in virial
equilibrium). The results highlight the power of combining high-precision
astrometry and photometry, and emphasize the role of NYC as a benchmark object
for testing stellar evolution models and dynamical models for young clusters
and as a template for extragalactic starburst clusters.Comment: 5 pages, 2 figure
Reconstructing the Arches I: Constraining the Initial Conditions
We have performed a series of N-body simulations to model the Arches cluster.
Our aim is to find the best fitting model for the Arches cluster by comparing
our simulations with observational data and to constrain the parameters for the
initial conditions of the cluster. By neglecting the Galactic potential and
stellar evolution, we are able to efficiently search through a large parameter
space to determine e.g. the IMF, size, and mass of the cluster. We find, that
the cluster's observed present-day mass function can be well explained with an
initial Salpeter IMF. The lower mass-limit of the IMF cannot be well
constrained from our models. In our best models, the total mass and the virial
radius of the cluster are initially (5.1 +/- 0.8) 10^4 Msun and 0.76 +/- 0.12
pc, respectively. The concentration parameter of the initial King model is w0 =
3-5.Comment: 12 pages, 14 Figures, revised and accepted for publication in MNRA
No evidence for mass segregation in massive young clusters
Aims. We investigate the validity of the mass segregation indicators commonly
used in analysing young stellar clusters. Methods. We simulate observations by
constructing synthetic seeing-limited images of a 1000 massive clusters (10^4
Msun) with a standard IMF and a King-density distribution function. Results. We
find that commonly used indicators are highly sensitive to sample
incompleteness in observational data and that radial completeness
determinations do not provide satisfactory corrections, rendering the studies
of radial properties highly uncertain. On the other hand, we find that, under
certain conditions, the global completeness can be estimated accurately,
allowing for the correction of the global luminosity and mass functions of the
cluster. Conclusions. We argue that there is currently no observational
evidence of mass segregation in young compact clusters since there is no robust
way to differentiate between true mass segregation and sample incompleteness
effects. Caution should then be exercised when interpreting results from
observations as evidence of mass segregation.Comment: 10 pages, 12 figures, typos corrected. Download a high-resolution
version at http://www.astro.up.pt/~jascenso/mseg_v2.pdf (1 MB
Model Predictive Control Based Trajectory Generation for Autonomous Vehicles - An Architectural Approach
Research in the field of automated driving has created promising results in
the last years. Some research groups have shown perception systems which are
able to capture even complicated urban scenarios in great detail. Yet, what is
often missing are general-purpose path- or trajectory planners which are not
designed for a specific purpose. In this paper we look at path- and trajectory
planning from an architectural point of view and show how model predictive
frameworks can contribute to generalized path- and trajectory generation
approaches for generating safe trajectories even in cases of system failures.Comment: Presented at IEEE Intelligent Vehicles Symposium 2017, Los Angeles,
CA, US
Galactic Halo substructure in the Sloan Digital Sky Survey: the ancient tidal stream from the Sagittarius dwarf galaxy
Two studies have recently reported the discovery of pronounced Halo
substructure in the Sloan Digital Sky Survey (SDSS) commissioning data. Here we
show that this Halo substructure is almost in its entirety due to the expected
tidal stream torn off the Sagittarius dwarf galaxy during the course of its
many close encounters with the Milky Way. This interpretation makes strong
predictions on the kinematics and distances of these stream stars. Comparison
of the structure in old horizontal branch stars, detected by the SDSS team,
with the carbon star structure discovered in our own survey, indicates that
this halo stream is of comparable age to the Milky Way. It would appear that
the Milky Way and the Sagittarius dwarf galaxy have been a strongly interacting
system for most of their existence. Once complete, the SDSS will provide a
unique dataset with which to constrain the dynamical evolution of the
Sagittarius dwarf galaxy, it will also strongly constrain the mass distribution
of the outer Milky Way.Comment: 7 pages, 3 figures (1 color figure chunky due to PS compression),
minor revisions,accepted by ApJ
Disks in the Arches cluster -- survival in a starburst environment
Deep Keck/NIRC2 HK'L' observations of the Arches cluster near the Galactic
center reveal a significant population of near-infrared excess sources. We
combine the L'-band excess observations with K'-band proper motions, to confirm
cluster membership of excess sources in a starburst cluster for the first time.
The robust removal of field contamination provides a reliable disk fraction
down to our completeness limit of H=19 mag, or about 5 Msun at the distance of
the Arches. Of the 24 identified sources with K'-L' > 2.0 mag, 21 have reliable
proper motion measurements, all of which are proper motion members of the
Arches cluster. VLT/SINFONI K'-band spectroscopy of three excess sources
reveals strong CO bandhead emission, which we interpret as the signature of
dense circumstellar disks. The detection of strong disk emission from the
Arches stars is surprising in view of the high mass of the B-type main sequence
host stars of the disks and the intense starburst environment. We find a disk
fraction of 6 +/- 2% among B-type stars in the Arches cluster. A radial
increase in the disk fraction from 3 to 10% suggests rapid disk destruction in
the immediate vicinity of numerous O-type stars in the cluster core. A
comparison between the Arches and other high- and low-mass star-forming regions
provides strong indication that disk depletion is significantly more rapid in
compact starburst clusters than in moderate star-forming environments.Comment: 51 pages preprint2 style, 22 figures, accepted by Ap
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