153 research outputs found
Les sables de Fontainebleau: a natural quartz reference sample and its characterisation
Fundamental studies on luminescence production
in natural quartz require samples
which can be studied by groups of laboratories
using complementary methods. In the framework
of a European collaboration studying
quartz luminescence, a sample originating
from the Fontainebleau Sandstone Formation
in France was selected for characterisation
and distribution to establish a starting point
for interlaboratory work. Here we report on
the preparation and characterisation work
undertaken before distribution with the aim
of ensuring that each laboratory received
comparable material. Material was purified to
enrich the quartz concentration, followed by
mineralogical screening by SEM and ICP-MS
analyses. Luminescence screening measurements
were undertaken at a single laboratory
(SUERC) to verify the suitability of the sample
for use within the study, and to establish the
level of homogeneity of subsamples prepared
for distribution. The sample underwent minimal
non-chemical pre-treatment by multiple
cycles of magnetic separation and annealing.
SEM analysis showed that the sample
consists mainly of SiO2. The luminescence
characterisation confirmed a dose sensitivity
of ca. 22,000–160,000 cts K−1 Gy−1 per 260–
290 grains for the 110◦C UV TL peak, well
developed low (here: 100–300◦C) temperature
(pre-dose) TL signals and high OSL sensitivities.
The grain to grain OSL response varies by
more than one order of magnitude. No significant
IRSL signal was observed. In summary,
the results from luminescence characterisation
confirm the suitability of the sample for the
luminescence experiments envisaged and have
established a basis for comparability in studies
conducted by a network of laboratories
Effect of Haemophilus influenzae type b vaccination without a booster dose on invasive H influenzae type b disease, nasopharyngeal carriage, and population immunity in Kilifi, Kenya: a 15-year regional surveillance study
Background Haemophilus infl uenzae type b (Hib) conjugate vaccine, delivered as a three-dose series without a booster,
was introduced into the childhood vaccination programme in Kenya in 2001. The duration of protection and need for
a booster dose are unknown. We aimed to assess vaccine eff ectiveness, the impact of the vaccine on nasopharyngeal
carriage, and population immunity after introduction of conjugate Hib vaccine in infancy without a booster dose
in Kenya.
Methods This study took place in the Kilifi Health and Demographic Surveillance System (KHDSS), an area of Kenya
that has been monitored for vital events and migration every 4 months since 2000. We analysed sterile site cultures
for H infl uenzae type b from children (aged ≤12 years) admitted to the Kilifi County Hospital (KCH) from Jan 1, 2000,
through to Dec 31, 2014. We determined the prevalence of nasopharyngeal carriage by undertaking cross-sectional
surveys in random samples of KHDSS residents (of all ages) once every year from 2009 to 2012, and measured Hib
antibody concentrations in fi ve cross-sectional samples of children (aged ≤12 years) within the KHDSS (in 1998, 2000,
2004–05, 2007, and 2009). We calculated incidence rate ratios between the prevaccine era (2000–01) and the routineuse
era (2004–14) and defi ned vaccine eff ectiveness as 1 minus the incidence rate ratio, expressed as a percentage.
Findings 40 482 children younger than 13 years resident in KHDSS were admitted to KCH between 2000 and 2014,
38 206 (94%) of whom had their blood cultured. The incidence of invasive H infl uenzae type b disease in children
younger than 5 years declined from 62·6 (95% CI 46·0–83·3) per 100 000 in 2000–01 to 4·5 (2·5–7·5) per 100 000 in
2004–14, giving a vaccine eff ectiveness of 93% (95% CI 87–96). In the fi nal 5 years of observation (2010–14), only one
case of invasive H infl uenzae type b disease was detected in a child younger than 5 years. Nasopharyngeal H infl uenzae
type b carriage was detected in one (0·2%) of 623 children younger than 5 years between 2009 and 2012. In the 2009
serosurvey, 92 (79%; 95% CI 70–86) of 117 children aged 4–35 months had long-term protective antibody
concentrations.
Interpretation In this region of Kenya, use of a three-dose primary series of Hib vaccine without a booster dose has
resulted in a signifi cant and sustained reduction in invasive H infl uenzae type b disease. The prevalence of
nasopharyngeal carriage is low and the profi le of Hib antibodies suggests that protection wanes only after the age at
greatest risk of disease. Although continued surveillance is important to determine whether eff ective control persists,
these fi ndings suggest that a booster dose is not currently required in Kenya
Compact groups in theory and practice - I. The spatial properties of compact groups
We use a mock galaxy catalogue based upon the Millennium Run simulation to
investigate the intrinsic spatial properties of compact groups of galaxies. We
find that approximately 30% of galaxy associations identified in our mock
catalogue are physically dense systems of four or more galaxies with no
interlopers, approximately half are close associations of 2, 3 or 4 galaxies
with one or more interlopers, and the remainder are not physically dense.
Genuine compact groups are preferentially brighter and more isolated than those
with interlopers; by increasing the required minimum surface brightness of a
group from the canonical value of 26mags/arcsec^2 to 22mags/arcsec^2, we can
increase the proportion of genuinely compact systems identified with no
interlopers from 29% to 75%. Of the genuine compact groups identified, more
than half consist of a single dark matter halo with all the member galaxies
deeply embedded within it. In some cases, there are other galaxies which share
the same halo (typically with mass ~ 10^13 h^{-1} M_\odot) but which are not
identified as being members of the compact group. This implies that compact
groups are associated with group environments, some or all members of which are
in the compact group. For those compact groups where all galaxies are in the
same halo, the three-dimensional velocity dispersion of the compact group
correlates broadly with the virial velocity of the dark matter halo. However,
the scale-size of the group - and hence the fraction of the halo mass which the
group samples - is completely uncorrelated with the properties of the dark
matter halo. This means that masses derived under the simple assumption of
virial equilibrium using the observed velocity dispersions and sizes of compact
groups give incorrect estimates of the true mass of the underlying dark matter.Comment: 12 pages, 9 figures. Accepted for publication in MNRA
Metrics of progress in the understanding and management of threats to Australian birds
Although evidence‐based approaches have become commonplace for determining the success of conservation measures for the management of threatened taxa, there are no standard metrics for assessing progress in research or management. We developed 5 metrics to meet this need for threatened taxa and to quantify the need for further action and effective alleviation of threats. These metrics (research need, research achievement, management need, management achievement, and percent threat reduction) can be aggregated to examine trends for an individual taxon or for threats across multiple taxa. We tested the utility of these metrics by applying them to Australian threatened birds, which appears to be the first time that progress in research and management of threats has been assessed for all threatened taxa in a faunal group at a continental scale. Some research has been conducted on nearly three‐quarters of known threats to taxa, and there is a clear understanding of how to alleviate nearly half of the threats with the highest impact. Some management has been attempted on nearly half the threats. Management outcomes ranged from successful trials to complete mitigation of the threat, including for one‐third of high‐impact threats. Progress in both research and management tended to be greater for taxa that were monitored or occurred on oceanic islands. Predation by cats had the highest potential threat score. However, there has been some success reducing the impact of cat predation, so climate change (particularly drought), now poses the greatest threat to Australian threatened birds. Our results demonstrate the potential for the proposed metrics to encapsulate the major trends in research and management of both threats and threatened taxa and provide a basis for international comparisons of evidence‐based conservation science
IRAS 06562-0337, The Iron Clad Nebula: A New Young Star Cluster
IRAS 06562-0337 has been the recent subject of a classic debate:
proto-planetary nebula or young stellar object? We present the first 2 micron
image of IRAS 06562-0337, which reveals an extended diffuse nebula containing
approximately 70 stars inside a 30 arcsec radius around a bright, possibly
resolved, central object. The derived stellar luminosity function is consistent
with that expected from a single coeval population, and the brightness of the
nebulosity is consistent with the predicted flux of unresolved low-mass stars.
The stars and nebulosity are spatially coincident with strong CO line emission.
We therefore identify IRAS 06562-0337 as a new young star cluster embedded in
its placental molecular cloud. The central object is likely a Herbig Be star, M
approx 20 M_sun, which may be seen in reflection. We present medium resolution,
high S/N, 1997 epoch optical spectra of the central object. Comparison with
previously published spectra shows new evidence for time variable permitted and
forbidden line emission, including SiII, FeII, [FeII], and [OI]. We suggest the
origin is a dynamic stellar wind in the extended, stratified atmosphere of the
massive central star in IRAS 06562-0337.Comment: 25 pages (4 figures) using aaspp4.sty. Accepted for publication in A
Early-type galaxies in the SDSS. I. The sample
A sample of nearly 9000 early-type galaxies, in the redshift range 0.01 < z <
0.3, was selected from the Sloan Digital Sky Survey using morphological and
spectral criteria. This paper describes how the sample was selected, presents
examples of images and seeing corrected fits to the observed surface brightness
profiles, describes our method for estimating K-corrections, and shows that the
SDSS spectra are of sufficiently high quality to measure velocity dispersions
accurately. It also provides catalogs of the measured photometric and
spectroscopic parameters. In related papers, these data are used to study how
early-type galaxy observables, including luminosity, effective radius, surface
brightness, color, and velocity dispersion, are correlated with one another.Comment: 63 pages, 21 figures. Accepted by AJ (scheduled for April 2003). This
paper is part I of a revised version of astro-ph/0110344. The full version of
Tables 2 and 3, i.e. the tables listing the photometric and spectroscopic
parameters of ~ 9000 galaxies, are available at
http://astrophysics.phys.cmu.edu/~bernardi/SDSS/Etypes/TABLE
The effectiveness and cost of camera traps for surveying small reptiles and critical weight range mammals: a comparison with labour-intensive complementary methods
Sterile neutrinos and supernova nucleosynthesis
A light sterile neutrino species has been introduced to explain
simultaneously the solar and atmospheric neutrino puzzles and the results of
the LSND experiment, while providing for a hot component of dark matter.
Employing this scheme of neutrino masses and mixings, we show how
matter-enhanced active-sterile neutrino transformation followed by
active-active neutrino transformation can solve robustly the neutron deficit
problem encountered by models of r-process nucleosynthesis associated with
neutrino-heated supernova ejecta.Comment: 29 pages, 3 postscript figures, submitted to Phys. Rev.
The conservation impacts of ecological disturbance : time-bound estimates of population loss and recovery for fauna affected by the 2019–2020 Australian megafires
Aim: After environmental disasters, species with large population losses may need urgent protection to prevent extinction and support recovery. Following the 2019–2020 Australian megafires, we estimated population losses and recovery in fire-affected fauna, to inform conservation status assessments and management. Location: Temperate and subtropical Australia. Time period: 2019–2030 and beyond. Major taxa: Australian terrestrial and freshwater vertebrates; one invertebrate group. Methods: From > 1,050 fire-affected taxa, we selected 173 whose distributions substantially overlapped the fire extent. We estimated the proportion of each taxon’s distribution affected by fires, using fire severity and aquatic impact mapping, and new distribution mapping. Using expert elicitation informed by evidence of responses to previous wildfires, we estimated local population responses to fires of varying severity. We combined the spatial and elicitation data to estimate overall population loss and recovery trajectories, and thus indicate potential eligibility for listing as threatened, or uplisting, under Australian legislation. Results: We estimate that the 2019–2020 Australian megafires caused, or contributed to, population declines that make 70–82 taxa eligible for listing as threatened; and another 21–27 taxa eligible for uplisting. If so-listed, this represents a 22–26% increase in Australian statutory lists of threatened terrestrial and freshwater vertebrates and spiny crayfish, and uplisting for 8–10% of threatened taxa. Such changes would cause an abrupt worsening of underlying trajectories in vertebrates, as measured by Red List Indices. We predict that 54–88% of 173 assessed taxa will not recover to pre-fire population size within 10 years/three generations. Main conclusions: We suggest the 2019–2020 Australian megafires have worsened the conservation prospects for many species. Of the 91 taxa recommended for listing/uplisting consideration, 84 are now under formal review through national processes. Improving predictions about taxon vulnerability with empirical data on population responses, reducing the likelihood of future catastrophic events and mitigating their impacts on biodiversity, are critical. © 2022 The Authors. Global Ecology and Biogeography published by John Wiley & Sons Ltd. **Please note that there are multiple authors for this article therefore only the name of the first 30 including Federation University Australia affiliate “Diana Kuchinke” is provided in this record*
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