1,276 research outputs found
European colonization, not Polynesian arrival, impacted population size and genetic diversity in the critically endangered New Zealand KÄkÄpĆ.
Island endemic species are often vulnerable to decline and extinction following human settlement, and the genetic study of historical museum specimens can be useful in understanding these processes. The kÄkÄpĆ (Strigops habroptilus) is a critically endangered New Zealand parrot that was formerly widespread and abundant. It is well established that both Polynesian and European colonization of New Zealand impacted the native avifauna, but the timeframe and severity of impacts have differed depending on species. Here, we investigated the relative importance of the 2 waves of human settlement on kÄkÄpĆ decline, using microsatellites and mitochondrial DNA (mtDNA) to characterize recent kÄkÄpĆ genetic and demographic history. We analyzed samples from 49 contemporary individuals and 54 museum specimens dating from 1884 to 1985. Genetic diversity decreased significantly between historical and contemporary kÄkÄpĆ, with a decline in mean number of microsatellite alleles from 6.15 to 3.08 and in number of mtDNA haplotypes from 17 to 3. Modeling of demographic history indicated a recent population bottleneck linked to the period of European colonization (approximately 5 generations ago) but did not support a major decline linked to Polynesian settlement. Effective population size estimates were also larger for historical than contemporary kÄkÄpĆ. Our findings inform contemporary kÄkÄpĆ management by indicating the timeframe and possible cause of the bottleneck, which has implications for the management of extant genetic diversity. We demonstrate the broader utility of a historical perspective in understanding causes of decline and managing extinction risk in contemporary endangered species
Reconstituted high-density lipoproteins promote wound repair and blood flow recovery in response to ischemia in aged mice
Background: The average population age is increasing and the incidence of age-related vascular complications is rising in parallel. Impaired wound healing and disordered ischemia-mediated angiogenesis are key contributors to age-impaired vascular complications that can lead to amputation. High-density lipoproteins (HDL) have vasculo-protective properties and augment ischemia-driven angiogenesis in young animals. We aimed to determine the effect of reconstituted HDL (rHDL) on aged mice in a murine wound healing model and the hindlimb ischemia (HLI) model. Methods: Murine wound healing modelâ24-month-old aged mice received topical application of rHDL (50 ÎŒg/wound/ day) or PBS (vehicle control) for 10 days following wounding. Murine HLI modelâFemoral artery ligation was performed on 24-month-old mice. Mice received rHDL (40 mg/kg) or PBS, intravenously, on alternate days, 1 week pre-surgery and up to 21 days post ligation. For both models, blood flow perfusion was determined using laser Doppler perfusion imaging. Mice were sacrificed at 10 (wound healing) or 21 (HLI) days post-surgery and tissues were collected for histological and gene analyses. Results: Daily topical application of rHDL increased the rate of wound closure by Day 7 post-wounding (25 %, p < 0.05). Wound blood perfusion, a marker of angiogenesis, was elevated in rHDL treated wounds (Days 4â10 by 22â25 %, p < 0. 05). In addition, rHDL increased wound capillary density by 52.6 %. In the HLI model, rHDL infusions augmented blood flow recovery in ischemic limbs (Day 18 by 50 % and Day 21 by 88 %, p < 0.05) and prevented tissue necrosis and toe loss. Assessment of capillary density in ischemic hindlimb sections found a 90 % increase in rHDL infused animals. In vitro studies in fibroblasts isolated from aged mice found that incubation with rHDL was able to significantly increase the key pro-angiogenic mediator vascular endothelial growth factor (VEGF) protein (25 %, p < 0.05). Conclusion: rHDL can promote wound healing and wound angiogenesis, and blood flow recovery in response to ischemia in aged mice. Mechanistically, this is likely to be via an increase in VEGF. This highlights a potential role for HDL in the therapeutic modulation of age-impaired vascular complications
Modifiable factors influencing relativesâ decision to offer organ donation: systematic review
Objective To identify modifiable factors that influence relativesâ decision to allow organ donation
Miniaturized data loggers and computer programming improve seabird risk and damage assessments for marine oil spills in Atlantic Canada
Obtaining useful information on marine birds that can aid in oil spill (and other hydrocarbon release) risk and damage assessments in offshore environments is challenging. Technological innovations in miniaturization have allowed archival data loggers to be deployed successfully on marine birds vulnerable to hydrocarbons on water. A number of species, including murres (both Common, Uria aalge, and Thick-billed, U. lomvia) have been tracked using geolocation
devices in eastern Canada, increasing our knowledge of the seasonality and colony-specific nature of their susceptibility to oil on water in offshore hydrocarbon production areas and major shipping lanes. Archival data tags are starting to resolve questions around behaviour of vulnerable seabirds at small spatial scales relevant to oil spill impact modelling, specifically to determine the duration and frequency at which birds fly at sea. Advances in data capture methods using voice activated software have eased the burden on seabird observers who are collecting
increasingly more detailed information on seabirds during ship-board and aerial transects. Computer programs that integrate seabird density and bird behaviour have been constructed, all with a goal of creating more credible seabird oil spill risk and damage assessments. In this paper, we discuss how each of these technological and computing innovations can help define critical inputs into seabird risk and damage assessments, and when combined, can provide a more realistic understanding of the impacts to seabirds from any hydrocarbon release
Radio Sources in Galaxy Clusters at 28.5 GHz
We present serendipitous detections of radio sources at 28.5 GHz (1 cm),
which resulted from our program to image thermal Sunyaev-Zeldovich (SZ) effect
in 56 galaxy clusters. We find 64 radio sources with fluxes down to 0.4 mJy,
and within 250 arcseconds from the pointing centers. The spectral indices (S ~
\nu^-\alpha) of 54 sources with published low frequency flux densities range
from -0.6 to 2 with a mean of 0.77, and a median of 0.84. Extending low
frequency surveys of radio sources towards galaxy clusters CL 0016+16, Abell
665, and Abell 2218 to 28.5 GHz, and selecting sources with 1.4 GHz flux
density greater than 7 mJy to form an unbiased sample, we find a mean spectral
index of 0.71 and a median of 0.71. We find 4 to 7 times more sources predicted
from a low frequency survey in areas without galaxy clusters. This excess
cannot be accounted for by gravitational lensing of a background radio
population by cluster potentials, indicating most of the detected sources are
associated with galaxy clusters. For the cluster Abell 2218, the presence of
unsubtracted radio sources with 28.5 GHz flux densities less than 0.5 mJy, can
only contribute to temperature fluctuations at a level of 10 to 25 \muK. The
corresponding error due to radio point source contamination in the Hubble
constant derived through a combined analysis of 28.5 GHz SZ images and X-ray
emission observations ranges from 1% to 6%.Comment: 18 pages, 8 figures, to appear in April 1998 issue of A
The Athenian Calendar of Sacrifices: A New Fragment from the Athenian Agora
Presented here is the editio princeps of a new fragment of the late-5th-century b.c. Athenian calendar of sacrifices. The fragment, Agora 17577, was discovered during excavations conducted in the Athenian Agora by the American School of Classical Studies. Inscribed on both faces (Face A: 403-399 b.c., Face B: 410-404 b.c.), it is associated with, but does not join, the group of fragments of Athenian legal inscriptions often referred to as the Law Code of Nikomachos. The text provides important additional evidence for the form of the calendar and the manner of its publication, and casts new light on broader issues of Athenian cult and topography
Feedback and the Structure of Simulated Galaxies at redshift z=2
We study the properties of simulated high-redshift galaxies using
cosmological N-body/gasdynamical runs from the OverWhelmingly Large Simulations
(OWLS) project. The runs contrast several feedback implementations of varying
effectiveness: from no-feedback, to supernova-driven winds to powerful
AGN-driven outflows. These different feedback models result in large variations
in the abundance and structural properties of bright galaxies at z=2. We find
that feedback affects the baryonic mass of a galaxy much more severely than its
spin, which is on average roughly half that of its surrounding dark matter halo
in our runs. Feedback induces strong correlations between angular momentum
content and galaxy mass that leave their imprint on galaxy scaling relations
and morphologies. Encouragingly, we find that galaxy disks are common in
moderate-feedback runs, making up typically ~50% of all galaxies at the centers
of haloes with virial mass exceeding 1e11 M_sun. The size, stellar masses, and
circular speeds of simulated galaxies formed in such runs have properties that
straddle those of large star-forming disks and of compact early-type galaxies
at z=2. Once the detailed abundance and structural properties of these rare
objects are well established it may be possible to use them to gauge the
overall efficacy of feedback in the formation of high redshift galaxies.Comment: 16 pages, 12 figures. Accepted for publication in MNRAS. Minor
changes to match published versio
Household-based cash transfer targeting strategies in Zimbabwe: are we reaching the most vulnerable children?
Census data, collected in July 2009, from 27,672 children were used to compare the effectiveness, coverage and efficacy of three household-based methods for targeting cash transfers to vulnerable children in eastern Zimbabwe: targeting the poorest households using a wealth index; targeting HIVaffected households using socio-demographic information (households caring for orphans, chronicallyill or disabled members; child-headed households); and targeting labour-constrained households using dependency ratios. All three methods failed to identify large numbers of children with poor social and educational outcomes. The wealth index approach was the most efficient at reaching children with poor outcomes whilst socio-demographic targeting reached more vulnerable children but was less efficient.publishedVersio
Comparison of mortality hazard ratios associated with health behaviours in Canada and the United States:a population-based linked health survey study
Background Modern health surveillance and planning requires an understanding of how preventable risk factors impact population health, and how these effects vary between populations. In this study, we compare how smoking, alcohol consumption, diet and physical activity are associated with all-cause mortality in Canada and the United States using comparable individual-level, linked population health survey data and identical model specifications. Methods The Canadian Community Health Survey (CCHS) (2003â2007) and the United States National Health Interview Survey (NHIS) (2000, 2005) linked to individual-level mortality outcomes with follow up to December 31, 2011 were used. Consistent variable definitions were used to estimate country-specific mortality hazard ratios with sex-specific Cox proportional hazard models, including smoking, alcohol, diet and physical activity, sociodemographic indicators and proximal factors including disease history. Results A total of 296,407 respondents and 1,813,884 million person-years of follow-up from the CCHS and 58,232 respondents and 497,909 person-years from the NHIS were included. Absolute mortality risk among those with a âhealthy profileâ was higher in the United States compared to Canada, especially among women. Adjusted mortality hazard ratios associated with health behaviours were generally of similar magnitude and direction but often stronger in Canada. Conclusion Even when methodological and population differences are minimal, the association of health behaviours and mortality can vary across populations. It is therefore important to be cautious of between-study variation when aggregating relative effect estimates from differing populations, and when using external effect estimates for population health research and policy development
International population-based health surveys linked to outcome data:A new resource for public health and epidemiology
Background: National health surveys linked to vital statistics and health care information provide a growing source of individual-level population health data. Pooling linked surveys across jurisdictions would create comprehensive datasets that are larger than most existing cohort studies, and that have a unique international and population perspective. This paperâs objectives are to examine the feasibility of pooling linked population health surveys from three countries, facilitate the examination of health behaviours, and present useful information to assist in the planning of international population health surveillance and research studies.
Methods: The design, methodologies and content of the Canadian Community Health Survey (2003 to 2008), the United States National Health Interview Survey (2000, 2005) and the Scottish Health Survey (SHeS) (2003, 2008 to 2010) were examined for comparability and consistency. The feasibility of creating common variables for measuring smoking, alcohol consumption, physical activity and diet was assessed. Sample size and estimated mortality events were collected.
Results: The surveys have comparable purposes, designs, sampling and administration methodologies, target populations, exclusions, and content. Similar health behaviour questions allow for comparable variables to be created across the surveys. However, the SHeS uses a more detailed risk factor evaluation for alcohol consumption and diet data. Therefore, comparisons of alcohol consumption and diet data between the SHeS and the other two surveys should be performed with caution. Pooling these linked surveys would create a dataset with over 350,000 participants, 28,424 deaths and over 2.4 million person-years of follow-up.
Conclusions: Pooling linked national population health surveys could improve population health research and surveillance. Innovative methodologies must be used to account for survey dissimilarities, and further discussion is needed on how to best access and analyze data across jurisdictions
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