441 research outputs found
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Ecological Complexity of Coral Recruitment Processes: Effects of Invertebrate Herbivores on Coral Recruitment and Growth Depends Upon Substratum Properties and Coral Species
Sarah W. Davies, Mikhail V. Matz, Integrative Biology Section, The University of Texas at Austin, Austin, Texas, United States of AmericaSarah W. Davies, Peter D. Vize, Department of Biological Sciences, University of Calgary, Calgary, Alberta, CanadaBackground: The transition from planktonic planula to sessile adult corals occurs at low frequencies and post settlement mortality is extremely high. Herbivores promote settlement by reducing algal competition. This study investigates whether invertebrate herbivory might be modulated by other ecological factors such as substrata variations and coral species identity. Methodology/Principal Findings: The experiment was conducted at the Flower Garden Banks, one of the few Atlantic reefs not experiencing considerable degradation. Tiles of differing texture and orientation were kept in bins surrounded by reef (24 m). Controls contained no herbivores while treatment bins contained urchins (Diadema antillarum) or herbivorous gastropods (Cerithium litteratum). Juvenile corals settling naturally were monitored by photography for 14 months to evaluate the effects of invertebrate herbivory and substratum properties. Herbivory reduced algae cover in urchin treatments. Two genera of brooding coral juveniles were observed, Agaricia and Porites, both of which are common but not dominant on adjacent reef. No broadcast spawning corals were observed on tiles. Overall, juveniles were more abundant in urchin treatments and on vertical, rough textured surfaces. Although more abundant, Agaricia juveniles were smaller in urchin treatments, presumably due to destructive overgrazing. Still, Agaricia growth increased with herbivory and substrata texture-orientation interactions were observed with reduced growth on rough tiles in control treatments and increased growth on vertical tiles in herbivore treatments. In contrast to Agaricia, Porites juveniles were larger on horizontal tiles, irrespective of herbivore treatment. Mortality was affected by substrata orientation with vertical surfaces increasing coral survival. Conclusions/Significance: We further substantiate that invertebrate herbivores play major roles in early settlement processes of corals and highlight the need for deeper understanding of ecological interactions modulating these effects. The absence of broadcast-spawning corals, even on a reef with consistently high coral cover, continues to expose the recruitment failure of these reef-building corals throughout the Caribbean.Natural Sciences and Engineering Research Council of Canada (NSERC) PGS-M to SWD; ACCESS Funding from the University of Calgary to SWD; National Science Foundation grant DEB-1054766 to MVM. Boat time provided by FGBNMS under permit# FGBNMS-2007-006. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Biological Sciences, School ofIntegrative BiologyEmail: [email protected]
Freedom is a Leaky System: Living Together in the Mess
Litter is upsetting.
People upset by litter often misunderstand its sources. Those for whom state power has worked look for simple solutions that seek to surveil, fine, and punish culprits.
Reality is messy.
The path of trash from hand to landfill requires a series of successful transfers between receptacles and responsibility. Wind, accidents, and spills in automated systems complicate trash’s path from here to away. Out of this complexity, leaks accumulate—visible issues without clear causes or responsibility.
Leaks are unavoidable.
There is an irreducible gap between the world as it is and our models of it. In this mismatch, systems leak.
The choice lies in how we respond.
The Department of Strange Beauty engages people struggling with the mess. DSB is not here to stop the leaks, but to help people understand and respond to complexity. Working between institutions, DSB approaches waste management and other leaky systems with reimagined tools and strategies.
Faced with the mess, we invite you: pick it up or let it go
Henri Temianka (Concert Programs)
This collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_ephemera/1092/thumbnail.jp
Moderated Online Communities and User-Generated Content
Online communities provide a social sphere for people to share
information and knowledge. While information sharing is becoming a
ubiquitous online phenomenon, how to ensure information quality or
induce quality content, however, remains a challenge due to the
anonymity of commentators. This paper introduces moderation into
reputation systems. We show that moderation directly impacts strategic
commentators incentive to generate useful information, and moderation is
generally desirable to improve information quality. Interestingly, we
find that when being moderated with different probabilities based on
their reputations, commentators may display a pattern of reputation
oscillation, in which they generate useful content to build up high
reputation and then exploit their reputation. As a result, the expected
performance from high-reputation commentators can be inferior to that
from low-reputation ones (reversed reputation). We then investigate the
optimal moderation resource allocation, and conclude that the seemingly
abnormal reversed reputation could arise as an optimal result. The paper
concludes with a discussion of the development of a scientific
moderation system with application to academic publishing
The Effectiveness of Revenue-Neutral Carbon Taxes
This paper investigates the effectiveness of carbon taxes in the manufacturing sector by examining British Columbia’s revenue-neutral carbon tax. We theoretically demonstrate that the magnitude of plants’ exposure to the policy monotonically increases with its emission intensity. Using detailed confidential plant-level data, we directly exploit the variations in plants’ emission intensity to isolate the emission effect of the policy. We find that the carbon tax lowers emission by 2 percent. Furthermore, we find that the policy had a positive output effect, suggesting that the carbon tax encouraged plants to produce more with less energies. These findings are possibly due to the revenue neutrality of the policy, especially through the reduction of the corporate income taxes. It incentivized plants to invest in both energy-saving and productivity-enhancing technologies.JEL Classification Codes: H23, Q5, L6Yamazaki acknowledges generous financial support from the Policy Research Center at the National Graduate Institutefor Policy Studies (GRIPS).http://www.grips.ac.jp/list/jp/facultyinfo/yamazaki-akio
Does dog-ownership influence seasonal patterns of neighbourhood-based walking among adults? A longitudinal study
<p>Abstract</p> <p>Background</p> <p>In general dog-owners are more physically active than non-owners, however; it is not known whether dog-ownership can influence seasonal fluctuations in physical activity. This study examines whether dog-ownership influences summer and winter patterns of neighbourhood-based walking among adults living in Calgary, Canada.</p> <p>Methods</p> <p>A cohort of adults, randomly sampled from the Calgary metropolitan area, completed postal surveys in winter and summer 2008. Both winter and summer versions of the survey included questions on dog-ownership, walking for recreation, and walking for transportation in residential neighbourhoods. <b>Participation </b>in neighbourhood-based walking was compared, among dog-owners and non-owners, and in summer and winter, using general linear modeling. <b>Stability </b>of participation in neighbourhood-based walking across summer and winter among dog-owners and non-owners was also assessed, using logistic regression.</p> <p>Results</p> <p>A total of 428 participants participated in the study, of whom 115 indicated owning dogs at the time of both surveys. Dog-owners reported more walking for recreation in their neighbourhoods than did non-owners, both in summer and in winter. Dog-owners were also more likely than non-owners to report participation in walking for recreation in their neighbourhoods, in summer as well as in winter. Dog-owners and non-owners did not differ in the amount of walking that they reported for transportation, either in summer or in winter.</p> <p>Conclusions</p> <p>By acting as cues for physical activity, dogs may help their owners remain active across seasons. Policies and programs related to dog-ownership and dog-walking, such as dog-supportive housing and dog-supportive parks, may assist in enhancing population health by promoting physical activity.</p
Binary and Millisecond Pulsars at the New Millennium
We review the properties and applications of binary and millisecond pulsars.
Our knowledge of these exciting objects has greatly increased in recent years,
mainly due to successful surveys which have brought the known pulsar population
to over 1300. There are now 56 binary and millisecond pulsars in the Galactic
disk and a further 47 in globular clusters. This review is concerned primarily
with the results and spin-offs from these surveys which are of particular
interest to the relativity community.Comment: 59 pages, 26 figures, 5 tables. Accepted for publication in Living
Reviews in Relativity (http://www.livingreviews.org
Time of day and outcomes of nonurgent percutaneous coronary intervention performed during working hours
Progesterone for the prevention of preterm birth in women with multiple pregnancies: the AMPHIA trial
Contains fulltext :
53264.pdf (publisher's version ) (Open Access)BACKGROUND: 15% of multiple pregnancies ends in a preterm delivery, which can lead to mortality and severe long term neonatal morbidity. At present, no generally accepted strategy for the prevention of preterm birth in multiple pregnancies exists. Prophylactic administration of 17-alpha hydroxyprogesterone caproate (17OHPC) has proven to be effective in the prevention of preterm birth in women with singleton pregnancies with a previous preterm delivery. At present, there are no data on the effectiveness of progesterone in the prevention of preterm birth in multiple pregnancies. METHODS/DESIGN: We aim to investigate the hypothesis that 17OHPC will reduce the incidence of the composite neonatal morbidity of neonates by reducing the early preterm birth rate in multiple pregnancies. Women with a multiple pregnancy at a gestational age between 15 and 20 weeks of gestation will be entered in a placebo-controlled, double blinded randomised study comparing weekly 250 mg 17OHPC intramuscular injections from 16-20 weeks up to 36 weeks of gestation versus placebo. At study entry, cervical length will be measured. The primary outcome is composite bad neonatal condition (perinatal death or severe morbidity). Secondary outcome measures are time to delivery, preterm birth rate before 32 and 37 weeks, days of admission in neonatal intensive care unit, maternal morbidity, maternal admission days for preterm labour and costs. We need to include 660 women to indicate a reduction in bad neonatal outcome from 15% to 8%. Analysis will be by intention to treat. We will also analyse whether the treatment effect is dependent on cervical length. DISCUSSION: This trial will provide evidence as to whether or not 17OHPC-treatment is an effective means of preventing bad neonatal outcome due to preterm birth in multiple pregnancies. TRIAL REGISTRATION: Current Controlled Trials ISRCTN40512715
Networks and social capital: a relational approach to primary healthcare reform
Collaboration among health care providers and across systems is proposed as a strategy to improve health care delivery the world over. Over the past two decades, health care providers have been encouraged to work in partnership and build interdisciplinary teams. More recently, the notion of networks has entered this discourse but the lack of consensus and understanding about what is meant by adopting a network approach in health services limits its use. Also crucial to this discussion is the work of distinguishing the nature and extent of the impact of social relationships – generally referred to as social capital. In this paper, we review the rationale for collaboration in health care systems; provide an overview and synthesis of key concepts; dispel some common misconceptions of networks; and apply the theory to an example of primary healthcare network reform in Alberta (Canada). Our central thesis is that a relational approach to systems change, one based on a synthesis of network theory and social capital can provide the fodation for a multi-focal approach to primary healthcare reform. Action strategies are recommended to move from an awareness of 'networks' to fully translating knowledge from existing theory to guide planning and practice innovations. Decision-makers are encouraged to consider a multi-focal approach that effectively incorporates a network and social capital approach in planning and evaluating primary healthcare reform
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