4,721 research outputs found
Impacts of colonial waterbirds on vegetation and potential restoration of island habitats
Colonial waterbirds have impacted forested island ecosystems throughout their breeding range, changing vegetation, and soil characteristics and bird communities. Our objectives were to (1) determine effects of three levels of colonial waterbird exclusion on overall vegetation diversity and growth, and survival of a candidate restoration species (black elderberry; Sambucus nigra canadensis); (2) investigate effects of different planting techniques on survival and growth of black elderberry; and (3) determine effects of waterbird colonization on soil chemistry. In 2012, we investigated effects of three levels of waterbird exclusion (none control plots [CON]; partial, which excluded waterbirds larger than gulls [PEX]; and full which excluded all waterbirds [FEX]) on bird use, existing vegetation growth and diversity, and survival of planted black elderberry on three islands in Door County, WI, Lake Michigan. In 2013, we evaluated survival of black elderberry established with four planting treatments within three waterbird exclusion treatments on two islands in 2013.We also compared soil chemistry characteristics between islands with and without nesting waterbirds for 2 years. Overall plant growth was greater in exclosures, but elderberry survival was similar among treatments. Soil replacement and weed suppression planting treatments did not affect survival, but generally increased overall elderberry biomass. Soil from nesting islands was more acidic and had greater nutrient concentrations than reference islands. Exclusion or removal of colonial nesting waterbirds from islands may improve overall vegetation growth, but successful restoration of woody vegetation may require significant soil manipulation and planting
X-ray Limits on the Progenitor System of the Type Ia Supernova 2017ejb
We present deep X-ray limits on the presence of a pre-explosion counterpart
to the low-luminosity Type Ia supernova (SN Ia) 2017ejb. SN 2017ejb was
discovered in NGC 4696, a well-studied elliptical galaxy in the Centaurus
cluster with 894 ks of Chandra imaging between 14 and 3 years before SN 2017ejb
was discovered. Using post-explosion photometry and spectroscopy of SN 2017ejb,
we demonstrate that SN 2017ejb is most consistent with low-luminosity SNe Ia
such as SN 1986G and SN 1991bg. Analyzing the location of SN 2017ejb in
pre-explosion images, we do not detect a pre-explosion X-ray source. We use
these data to place upper limits on the presence of any unobscured supersoft
X-ray source (SSS). SSS systems are known to consist of white dwarfs accreting
from a non-degenerate companion star. We rule out any source similar to known
SSS systems with eV and as well as models of stably-accreting
Chandrasekhar-mass WDs with accretion rates
. These findings suggest that
low-luminosity SNe Ia similar to SN 2017ejb explode from WDs that are low-mass,
have low pre-explosion accretion rates, or accrete very soon before explosion.
Based on the limits from SN 2017ejb and other nearby SNe Ia, we infer that
47% of SNe Ia explode in stably-accreting Chandrasekhar-mass SSS systems.Comment: 10 pages, 4 figures, submitted to MNRA
Development of a Personalized Shared Decision-Making Tool for Knee Osteoarthritis and User-Testing With African American and Latina Women
BACKGROUND: Patients with chronic knee pain are often unaware of treatment options and likely outcomes-information that is critical to decision-making. A consistent framework for communicating patient-personalized information enables clinicians to provide consistent, targeted, and relevant information. Our objective was to user-test a shared decision-making (SDM) tool for chronic knee pain.
METHODS: A cross-functional team developed a Markov-based health economics model and tested the model outputs with patient panels, patient and clinician focus groups, and clinical specialists. The resulting SDM tool was user-tested in a parallel-designed, randomized controlled study with 52 African American and 52 Latina women from geographically representative areas of the US. Participants were randomized to counseling with or without the SDM tool. Feedback was collected at intervention and at 1 month after intervention and analyzed with Student\u27s t-tests and Chi-squared analyses (alpha = 0.05).
RESULTS: Qualitative results indicated patients understood the material, rated the overall experience highly, and were likely to recommend the physician. The SDM group reported high satisfaction with the tool. A greater proportion of the SDM group (56%) reported increased physical activity over baseline at 1 month compared with the control group (33%) (
CONCLUSION: Use of this innovative SDM tool was associated with high satisfaction and a significant increase in self-reported physical activity level at 1 month. The SDM tool may elicit behavioral changes to promote musculoskeletal health
Use of contingency management incentives to improve completion of hepatitis B vaccination in people undergoing treatment for heroin dependence: a cluster randomised trial
Background: Poor adherence to treatment diminishes its individual and public health benefit. Financial incentives, provided on the condition of treatment attendance, could address this problem. Injecting drug users are a high-risk group for hepatitis B virus (HBV) infection and transmission, but adherence to vaccination programmes is poor. We aimed to assess whether contingency management delivered in routine clinical practice increased the completion of HBV vaccination in individuals receiving opioid substitution therapy.
Methods: In our cluster randomised controlled trial, we enrolled participants at 12 National Health Service drug treatment services in the UK that provided opioid substitution therapy and nurse-led HBV vaccination with a super-accelerated schedule (vaccination days 0, 7, and 21). Clusters were randomly allocated 1:1:1 to provide vaccination without incentive (treatment as usual), with fixed value contingency management (three £10 vouchers), or escalating value contingency management (£5, £10, and £15 vouchers). Both contingency management schedules rewarded
on-time attendance at appointments. The primary outcome was completion of clinically appropriate HBV vaccination within 28 days. We also did sensitivity analyses that examined vaccination completion with full adherence to appointment times and within a 3 month window. The trial is registered with Current Controlled Trials, number ISRCTN72794493.
Findings: Between March 16, 2011, and April 26, 2012, we enrolled 210 eligible participants. Compared with six (9%) of 67 participants treated as usual, 35 (45%) of 78 participants in the fixed value contingency management group met the primary outcome measure (odds ratio 12·1, 95% CI 3·7–39·9; p<0·0001), as did 32 (49%) of 65 participants in the escalating value contingency management group (14·0, 4·2–46·2; p<0·0001). These differences remained significant with sensitivity analyses.
Interpretation: Modest financial incentives delivered in routine clinical practice significantly improve adherence to, and completion of, HBV vaccination programmes in patients receiving opioid substitution therapy. Achievement of this improvement in routine clinical practice should now prompt actual implementation. Drug treatment providers should employ contingency management to promote adherence to vaccination programmes. The effectiveness of
routine use of contingency management to achieve long-term behaviour change remains unknown
Clustering of childhood mortality in the Kintampo Health and Demographic Surveillance System in Ghana
Background: Childhood mortality in Ghana has generally declined in the last four decades. However, estimates tend to conceal substantial variability among regions and districts. The lack of population-based data in Ghana, as in other less developed countries, has hindered the development of effective programmes targeted specifically at clusters where mortality levels are significantly higher. Objective: This paper seeks to test for the existence of statistically significant clusters of childhood mortality within the Kintampo Health and Demographic Surveillance System (KHDSS) between 2005 and 2007. Design: In this study, mortality rates were generated using mortality data extracted from the health and demographic surveillance database of the KHDSS and exported into STATA. The spatial and spatio-temporal scan statistic by Kulldorff was used to identify significant clusters of childhood mortality within the KHDSS. Results: A significant cluster of villages with high under-five mortality in the south-eastern part of the KHDSS in 2006 was identified. This is a remote location where poverty levels are relatively higher, health facilities are more sparse and these are compounded by poor transport services in case of emergencies. Conclusion: This study highlights the potential of the surveillance platform to demonstrate the spatial dimensions of childhood mortality clustering. It is apparent, though, that further studies need to be carried out in order to explore the underlying risk factors for potential mortality clusters that could emerge later
Evidence for weathering and volcanism during the PETM from Arctic Ocean and Peri-Tethys osmium isotope records
Sudden global warming during the Paleocene–Eocene Thermal Maximum (PETM, 55.9 Ma) occurred because of the rapid release of several thousand gigatonnes of isotopically light carbon into the oceans and atmosphere; however, the cause of this release is not well understood. Some studies have linked carbon injection to volcanic activity associated with the North Atlantic Igneous Province (NAIP), while others have emphasised carbon cycle feedbacks associated with orbital forcing. This study presents the osmium isotope compositions of mudrocks that were deposited during the PETM at four locations (one from the Arctic Ocean, and three from the Peri-Tethys). The Os-isotope records all exhibit a shift of similar magnitude towards relatively radiogenic values across the PETM. This observation confirms that there was a transient, global increase in the flux of radiogenic Os from the weathering of continental rocks in response to elevated temperatures at that time. The tectonic effects of NAIP volcanic emplacement near the onset of the PETM is recorded by anomalously radiogenic Os-isotope compositions of PETM-age Arctic Ocean samples, which indicate an interval of hydrographic restriction that can be linked tectonic uplift due to hotspot volcanism in the North Atlantic seaway. The Peri-Tethys data also document a transient, higher flux of unradiogenic osmium into the ocean near the beginning of the PETM, most likely from the weathering of young mafic rocks associated with the NAIP. These observations support the hypothesis that volcanism played a major role in triggering the cascade of environmental changes during the PETM, and highlight the influence of paleogeography on the Os isotope characteristics of marine water masses
Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems
Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution
of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the
associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local
management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef
fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions
and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the
1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites
and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure,
diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale
integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales,
with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas
still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance.
This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should
be integrated into existing management frameworks and combined with policies to improve system-wide resilience to
climate variation and change
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