555 research outputs found
Flesh on the Bones: Animal Bodies in Atlantic Roundhouses
This volume presents the state of research across Europe to illustrate how comparable interpretative frameworks are used by archaeologists working with both prehistoric and historical societies
Dynamical segregation of galaxies in groups and clusters
We have performed a systematic analysis of the dynamics of different galaxy
populations in galaxy groups from the 2dFGRS. For this purpose we have combined
all the groups into a single system, where velocities v and radius r are
expressed adimensionally. We have used several methods to compare the
distributions of relative velocities of galaxies with respect to the group
centre for samples selected according to their spectral type (as defined by
Madgwick et al., 2002), bj band luminosity and B-R colour index. We have found
strong segregation effects: spectral type I objects show a statistically
narrower velocity distribution than that of galaxies with a substantial star
formation activity (type II-IV). Similarly, the same behavior is observed for
galaxies with colour index B-R>1 compared to galaxies with B-R<1. Bright
(Mb-19) galaxies show the same segregation. It is not
important once the sample is restricted to a given spectral type. These effects
are particularly important in the central region (Rp<Rvirial/2) and do not have
a strong dependence on the mass of the parent group. These trends show a strong
correlation between the dynamics of galaxies in groups and star formation rate
reflected both by spectral type and by colour index.Comment: 7 pages, 8 figures. Accepted for publication in MNRA
The Spectroscopic Age of 47 Tuc
High signal-to-noise integrated spectra of the metal-rich globular cluster 47
Tuc, spanning the H-gamma(HR) and Fe4668 line indices, have been obtained. The
combination of these indices has been suggested (Jones & Worthey 1995, ApJ,
446, L31) as the best available mechanism for cleanly separating the
age-metallicity degeneracy which hampers the dating of distant, unresolved,
elliptical galaxies. For the first time, we apply this technique to a nearby
spheroidal system, 47 Tuc, for which independent ages, based upon more
established methods, exist. Such an independent test of the technique's
suitability has not been attempted before, but is an essential one before its
application to more distant, unresolved, stellar populations can be considered
valid. Because of its weak series of Balmer lines, relative to model spectra,
our results imply a spectroscopic ``age'' for 47 Tuc well in excess of 20 Gyr,
at odds with the colour-magnitude diagram age of 14+/-1 Gyr. The derived metal
abundance, however, is consistent with the known value. Emission ``fill-in'' of
the H-gamma line as the source of the discrepancy cannot be entirely excluded
by existing data, although the observational constraints are restrictive.Comment: 17 pages, 4 figures, LaTeX, accepted for publication in The
Astronomical Journal, also available at
http://casa.colorado.edu/~bgibson/publications.htm
Galaxy Pairs in the 2dF Survey I. Effects of Interactions in the Field
We study galaxy pairs in the field selected from the 100 K public release of
the 2dF galaxy redshift survey. Our analysis provides a well defined sample of
1258 galaxy pairs, a large database suitable for statistical studies of galaxy
interactions in the local universe, . Galaxy pairs where selected by
radial velocity () and projected separation () criteria
determined by analyzing the star formation activity within neighbours
(abridged). The ratio between the fractions of star forming galaxies in pairs
and in isolation is a useful tools to unveil the effects of having a close
companion. We found that about fifty percent of galaxy pairs do not show signs
of important star formation activity (independently of their luminosities)
supporting the hypothesis that the internal properties of the galaxies play a
crucial role in the triggering of star formation by interactions.Comment: 9 pages, 11 Postscript figures. Submitted to MNRAS. Revised versio
New Supernova Candidates from SDSS-DR7 of Spectral Survey
The letter presents 25 discovered supernova candidates from SDSS-DR7 with our
dedicated method, called Sample Decrease, and 10 of them were confirmed by
other research groups, and listed in this letter. Another 15 are first
discovered including 14 type Ia and one type II based on Supernova
Identification (SNID) analysis. The results proved that our method is reliable,
and the description of the method and some detailed spectra analysis procedures
were also presented in this letter.Comment: 6 pages, 3 figure
Sun safety in construction: a profiling and intervention study
Background: Construction workers spend a large proportion of their work time outdoors, placing them at increased risk for skin cancer. To date, no large-scale studies have examined occupational sun safety knowledge, attitudes, and practices within this group in the UK context. Given the high incidence of skin cancer attributable to sun exposure in construction relative to other occupational groups, interventions to promote sun safety in the UK construction sector are warranted.
Aims: The current investigation has two aims. First, to describe the occupational sun safety knowledge, attitudes, and practices of a large and nationally representative sample of construction workers in the UK. Second, to evaluate change in sun safety knowledge and practices among construction workers in response to an educational intervention.
Methods: The first aim was addressed through the administration of a self-report questionnaire in the summer of 2012. The second aim was addressed through the subsequent administration of a bespoke sector-specific DVD-based intervention. The effectiveness of the intervention was evaluated via the administration of a further questionnaire at 12-month follow-up.
Results: A total of 1,279 workers from 22 organizations completed a baseline (pre-intervention) self-report questionnaire. Findings indicated poor knowledge on the topic and of the measures available to reduce levels of solar ultraviolet radiation exposure. The findings at this stage of the project confirmed the imperative for a tailored, targeted, and evaluable educational intervention that could help to enhance sun safety knowledge, attitudes and behavior in the sector. In relation to the second aim, analyses were conducted on a sample of 120 workers (intervention group, n = 70; comparison group, n = 50). At follow-up the proportion of intervention group participants that reported correct sun safety knowledge was not significantly greater than at baseline. However, the intervention group demonstrated significant positive change on nine out of ten behavioural measures, the greatest change being use of a shade/cover when working in the sun followed by regularly checking skin for moles or unusual changes.
Conclusions: The profiling exercise indicated that there is a need to raise the profile of occupational skin cancer among this population and increase the priority given to occupational sun safety policies alongside targeted, tailored, and evaluable interventions. Exposure to this intervention was linked to some specific positive changes in construction workers’ self-reported sun safety practices. These findings highlight the potential for educational interventions to contribute to tackling skin cancer in the UK construction sector. The findings support the development of bespoke educational interventions for other high-risk outdoor worker groups
Superclusters of galaxies in the 2dF redshift survey. III. The properties of galaxies in superclusters
We use catalogues of superclusters of galaxies from the 2dF Galaxy Redshift
Survey to study the properties of galaxies in superclusters. We compare the
properties of galaxies in high and low density regions of rich superclusters,
in poor superclusters and in the field, as well as in groups, and of isolated
galaxies in superclusters of various richness. We show that in rich
superclusters the values of the luminosity density smoothed on a scale of 8
\Mpc are higher than in poor superclusters: the median density in rich
superclusters is , in poor superclusters . Rich superclusters contain high density cores with densities while in poor superclusters such high density cores are absent. The
properties of galaxies in rich and poor superclusters and in the field are
different: the fraction of early type, passive galaxies in rich superclusters
is slightly larger than in poor superclusters, and is the smallest among the
field galaxies. Most importantly, in high density cores of rich superclusters
() there is an excess of early type, passive galaxies in groups
and clusters, as well as among those which do not belong to groups or clusters.
The main galaxies of superclusters have a rather limited range of absolute
magnitudes. The main galaxies of rich superclusters have larger luminosities
than those of poor superclusters and of groups in the field. Our results show
that both the local (group/cluster) environments and global (supercluster)
environments influence galaxy morphologies and their star formation activity.Comment: 13 pages, 10 figures, submitted to Astronomy and Astrophysic
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Measuring motion with kinematically redundant accelerometer arrays: theory, simulation and implementation
This work presents two schemes of measuring the linear and angular kinematics of a rigid body using a kinematically redundant array of triple-axis accelerometers with potential applications in biomechanics. A novel angular velocity estimation algorithm is proposed and evaluated that can compensate for angular velocity errors using measurements of the direction of gravity. Analysis and discussion of optimal sensor array characteristics are provided. A damped 2 axis pendulum was used to excite all 6 DoF of the a suspended accelerometer array through determined complex motion and is the basis of both simulation and experimental studies. The relationship between accuracy and sensor redundancy is investigated for arrays of up to 100 triple axis (300 accelerometer axes) accelerometers in simulation and 10 equivalent sensors (30 accelerometer axes) in the laboratory test rig. The paper also reports on the sensor calibration techniques and hardware implementation
A veritable confusion: use and abuse of isotope analysis in archaeology
The expansion of isotope analyses has transformed the study of past migration and mobility, sometimes providing unexpected and intriguing results. This has, in turn, led to media attention (and concomitant misrepresentation) and scepticism from some archaeologists. Such scepticism is healthy and not always without foundation. Isotope analysis is yet to reach full maturity and challenging issues remain, concerning diagenesis, biosphere mapping resolution and knowledge of the drivers of variation. Bold and over-simplistic interpretations have been presented, especially when relying on single isotope proxies, and researchers have at times been accused of following specific agendas. It is therefore vital to integrate archaeological and environmental evidence to support interpretation. Most importantly, the use of multiple isotope proxies is key: isotope analysis is an exclusive approach and therefore single analyses provide only limited resolution. The growth in isotope research has led to a growth in rebuttals and counter-narratives. Such rebuttals warrant the same critical appraisal that is applied to original research, both of evidence for their assertions and the potential for underlying agendas. This paper takes a case study-based approach focusing on pig movements to Neolithic henge complexes to explore the dangers encountered in secondary use of isotope data
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