1,276 research outputs found
Logarithmic Corrections in Dynamic Isotropic Percolation
Based on the field theoretic formulation of the general epidemic process we
study logarithmic corrections to scaling in dynamic isotropic percolation at
the upper critical dimension d=6. Employing renormalization group methods we
determine these corrections for some of the most interesting time dependent
observables in dynamic percolation at the critical point up to and including
the next to leading correction. For clusters emanating from a local seed at the
origin we calculate the number of active sites, the survival probability as
well as the radius of gyration.Comment: 9 pages, 3 figures, version to appear in Phys. Rev.
The changing landscape of conservation science funding in the United States
To understand the changing role of funding sources in shaping conservation science in the United States, we analyzed acknowledgments from published studies, trends in research funding, and survey responses from conservation scientists. Although the U.S. federal government was the most frequently acknowledged source of support overall, U.S. foundations and NGOs were the predominant sources for tropical and socioeconomic research. Acknowledgments of foundation support for conservation research increased over the last two decades, while recognition of federal funds declined. Concordant trends in funding and acknowledgments indicated a changing landscape for conservation science, in which federal support has not kept pace with the growth in conservation research efforts or needs. Survey responses from conservation scientists about their funding sources were consistent with acknowledgment data, and most (64%) indicated that shifts in funding sources and amounts affected the type of research they conduct. Ongoing changes in the funding landscape shape the direction of conservation research and may make conservation science more vulnerable to economic recessions
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Nitrogen isotopic analysis of carbonate-bound organic matter in modern and fossil fish otoliths
The nitrogen isotopic composition (δ^(15)N) of otolith-bound organic matter (OM) is a potential source of information on dietary history of bony fishes. In contrast to the δ^(15)N of white muscle tissue, the most commonly used tissue for ecological studies, the δ^(15)N of otolith-bound OM (δ^(15)N_(oto)) provides a record of whole life history. More importantly, δ^(15)N_(oto) can be measured in contexts where tissue is not available, for example, in otolith archives and sedimentary deposits. The utility and robustness of otolith δ^(15)N analysis was heretofore limited by the low N content of otoliths, which precluded the routine measurement of individual otoliths as well as the thorough cleaning of otolith material prior to analysis. Here, we introduce a new method based on oxidation to nitrate followed by bacterial conversion to N_2O. The method requires 200-fold less N compared to traditional combustion approaches, allowing for thorough pre-cleaning and replicated analysis of individual otoliths of nearly any size. Long term precision of δ^(15)N_(oto) is 0.3â°. Using an internal standard of Atlantic cod (Gadus morhua) otoliths, we examine the parameters of the oxidative cleaning step with regard to oxidant (potassium persulfate and sodium hypochlorite), temperature, and time. We also report initial results that verify the usefulness of δ^(15)N_(oto) for ecological studies. For three salmonid species, left and right otoliths from the same fish are indistinguishable. We find that the δ^(15)N_(oto) of pink salmon (Oncorhynchus gorbuscha) is related to the size of the fish for this species. We find that intra-cohort δ^(15)N_(oto) standard deviation for wild pink salmon, farmed brown trout (Salmo trutta), and farmed rainbow trout (Oncorhynchus mykiss) are all 0.4â° or less, suggesting that δ^(15)N_(oto) will be valuable for population-level studies. Lastly, our protocol yields reproducible data for both δ^(15)N_(oto) and otolith N content in 17th century Atlantic cod otoliths. We find that 17th century cod are approximately 2 â° higher than modern cod, arguably consistent with either the larger size of the otoliths (and thus inferred for the fish) or with changes in baseline (primary producer) δ^(15)N in the modern coastal ocean compared to the past. All told, the results of this study bode well for the utility of otolith-bound δ15N for investigating the environment and ecology of modern and past fish
Nitrogen isotopic analysis of carbonate-bound organic matter in modern and fossil fish otoliths
The nitrogen isotopic composition (δ^(15)N) of otolith-bound organic matter (OM) is a potential source of information on dietary history of bony fishes. In contrast to the δ^(15)N of white muscle tissue, the most commonly used tissue for ecological studies, the δ^(15)N of otolith-bound OM (δ^(15)N_(oto)) provides a record of whole life history. More importantly, δ^(15)N_(oto) can be measured in contexts where tissue is not available, for example, in otolith archives and sedimentary deposits. The utility and robustness of otolith δ^(15)N analysis was heretofore limited by the low N content of otoliths, which precluded the routine measurement of individual otoliths as well as the thorough cleaning of otolith material prior to analysis. Here, we introduce a new method based on oxidation to nitrate followed by bacterial conversion to N_2O. The method requires 200-fold less N compared to traditional combustion approaches, allowing for thorough pre-cleaning and replicated analysis of individual otoliths of nearly any size. Long term precision of δ^(15)N_(oto) is 0.3â°. Using an internal standard of Atlantic cod (Gadus morhua) otoliths, we examine the parameters of the oxidative cleaning step with regard to oxidant (potassium persulfate and sodium hypochlorite), temperature, and time. We also report initial results that verify the usefulness of δ^(15)N_(oto) for ecological studies. For three salmonid species, left and right otoliths from the same fish are indistinguishable. We find that the δ^(15)N_(oto) of pink salmon (Oncorhynchus gorbuscha) is related to the size of the fish for this species. We find that intra-cohort δ^(15)N_(oto) standard deviation for wild pink salmon, farmed brown trout (Salmo trutta), and farmed rainbow trout (Oncorhynchus mykiss) are all 0.4â° or less, suggesting that δ^(15)N_(oto) will be valuable for population-level studies. Lastly, our protocol yields reproducible data for both δ^(15)N_(oto) and otolith N content in 17th century Atlantic cod otoliths. We find that 17th century cod are approximately 2 â° higher than modern cod, arguably consistent with either the larger size of the otoliths (and thus inferred for the fish) or with changes in baseline (primary producer) δ^(15)N in the modern coastal ocean compared to the past. All told, the results of this study bode well for the utility of otolith-bound δ15N for investigating the environment and ecology of modern and past fish
Agents intervening against delirium in the intensive care unit trial-Protocol for a secondary Bayesian analysis
Background Delirium is highly prevalent in the intensive care unit (ICU) and is associated with high morbidity and mortality. The antipsychotic haloperidol is the most frequently used agent to treat delirium although this is not supported by solid evidence. The agents intervening against delirium in the intensive care unit (AID-ICU) trial investigates the effects of haloperidol versus placebo for the treatment of delirium in adult ICU patients. Methods This protocol describes the secondary, pre-planned Bayesian analyses of the primary and secondary outcomes up to day 90 of the AID-ICU trial. We will use Bayesian linear regression models for all count outcomes and Bayesian logistic regression models for all dichotomous outcomes. We will adjust for stratification variables (site and delirium subtype) and use weakly informative priors supplemented with sensitivity analyses using sceptical priors. We will present results as absolute differences (mean differences and risk differences) and relative differences (ratios of means and relative risks). Posteriors will be summarised using median values as point estimates and percentile-based 95% credibility intervals. Probabilities of any benefit/harm, clinically important benefit/harm and clinically unimportant differences will be presented for all outcomes. Discussion The results of this secondary, pre-planned Bayesian analysis will complement the primary frequentist analysis of the AID-ICU trial and facilitate a nuanced and probabilistic interpretation of the trial results.Peer reviewe
Can biodiversity of preexisting and created salt marshes match across scales? An assessment from microbes to predators
Coastal wetlands are rapidly disappearing worldwide due to a variety of processes, including climate change and flood control. The rate of loss in the Mississippi River Delta is among the highest in the world and billions of dollars have been allocated to build and restore coastal wetlands. A key question guiding assessment is whether created coastal salt marshes have similar biodiversity to preexisting, reference marshes. However, the numerous biodiversity metrics used to make these determinations are typically scale dependent and often conflicting. Here, we applied ecological theory to compare the diversity of different assemblages (surface and below-surface soil microbes, plants, macroinfauna, spiders, and on-marsh and off-marsh nekton) between two created marshes (4â6 years old) and four reference marshes. We also quantified the scale-dependent effects of species abundance distribution, aggregation, and density on richness differences and explored differences in species composition. Total, between-sample, and within-sample diversity (Îł, β, and Îą, respectively) were not consistently lower at created marshes. Richness decomposition varied greatly among assemblages and marshes (e.g., soil microbes showed high equitability and Îą diversity, but plant diversity was restricted to a few dominant species with high aggregation). However, species abundance distribution, aggregation, and density patterns were not directly associated with differences between created and reference marshes. One exception was considerably lower density for macroinfauna at one of the created marshes, which was drier because of being at a higher elevation and having coarser substrate compared with the other marshes. The community compositions of created marshes were more dissimilar than reference marshes for microbe and macroinfauna assemblages. However, differences were small, particularly for microbes. Together, our results suggest generally similar taxonomic diversity and composition between created and reference marshes. This provides support for the creation of marsh habitat as tools for the maintenance and restoration of coastal biodiversity. However, caution is needed when creating marshes because specific building and restoration plans may lead to different colonization patterns
Agents intervening against delirium in the intensive care unit (AID-ICU) - Protocol for a randomised placebo-controlled trial of haloperidol in patients with delirium in the ICU
Background
Delirium among patients in the intensive care unit (ICU) is a common condition associated with increased morbidity and mortality. Haloperidol is the most frequently used pharmacologic intervention, but its use is not supported by firm evidence. Therefore, we are conducting Agents Intervening against Delirium in the Intensive Care Unit (AIDâICU) trial to assess the benefits and harms of haloperidol for the treatment of ICUâacquired delirium.
Methods
AIDâICU is an investigatorâinitiated, pragmatic, international, randomised, blinded, parallelâgroup, trial allocating adult ICU patients with manifest delirium 1:1 to haloperidol or placebo. Trial participants will receive intravenous 2.5 mg haloperidol three times daily or matching placebo (isotonic saline 0.9%) if they are delirious. If needed, a maximum of 20 mg/daily haloperidol/placebo is given. An escape protocol, not including haloperidol, is part of the trial protocol. The primary outcome is days alive out of the hospital within 90 days postârandomisation. Secondary outcomes are number of days without delirium or coma, serious adverse reactions to haloperidol, usage of escape medication, number of days alive without mechanical ventilation; mortality, healthârelated qualityâofâlife and cognitive function at 1âyear followâup. A sample size of 1000 patients is required to detect a 7âday improvement or worsening of the mean days alive out of the hospital, type 1 error risk of 5% and power 90%.
Perspective
The AIDâICU trial is based on gold standard methodology applied to a large sample of clinically representative patients and will provide pivotal highâquality data on the benefits and harms of haloperidol for the treatment ICUâacquired delirium
Effective fisheries management instrumental in improving fish stock status
Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported globalmarine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.Fil: Hilborn, Ray. University of Washington; Estados UnidosFil: Amoroso, Ricardo Oscar. University of Washington; Estados UnidosFil: Anderson, Christopher M.. University of Washington; Estados UnidosFil: Baum, Julia K.. University of Victoria; CanadĂĄFil: Branch, Trevor A.. University of Washington; Estados UnidosFil: Costello, Christopher. University of California at Santa Barbara; Estados UnidosFil: de Moor, Carryn L.. University of Cape Town; SudĂĄfricaFil: Faraj, Abdelmalek. Einstitut National de Recherche Halieutique; MarruecosFil: Hively, Daniel. University of Washington; Estados UnidosFil: Jensen, Olaf P.. Rutgers University; Estados UnidosFil: Kurota, Hiroyuki. Japan Fisheries Research and Education Agency; JapĂłnFil: Little, L. Richard. Csiro Oceans and Atmosphere; AustraliaFil: Mace, Pamela. Ministry for Primary Industries; Nueva ZelandaFil: McClanahan, Tim. Wildlife Conservation Society; Estados UnidosFil: Melnychuk, Michael C.. University of Washington; Estados UnidosFil: Minto, CĂłilĂn. Galway-Mayo Institute of Technology; IrlandaFil: Osio, Giacomo Chato. Joint Research Centre (JRC); Italia. DG Maritime Affairs and Fisheries, European Commission; BĂŠlgicaFil: Pons, Maite. University of Washington; Estados UnidosFil: Parma, Ana MarĂa. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico TecnolĂłgico Conicet - Centro Nacional PatagĂłnico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Segurado, Susana. Sustainable Fisheries Partnership; Estados UnidosFil: Szuwalski, Cody S.. University of California at Santa Barbara; Estados UnidosFil: Wilson, Jono R.. University of California at Santa Barbara; Estados Unidos. The Nature Conservancy; Estados UnidosFil: Ye, Yimin. Food and Agriculture Organization of the United Nations; Itali
Robotic-based carbon ion therapy and patient positioning in 6 degrees of freedom: setup accuracy of two standard immobilization devices used in carbon ion therapy and IMRT
Progression of atypical parkinsonian syndromes: PROSPECT-M-UK study implications for clinical trials
The advent of clinical trials of disease-modifying agents for neurodegenerative disease highlights the need for evidence-based endpoint selection. Here we report the longitudinal PROSPECT-M-UK study of progressive supranuclear palsy, corticobasal syndrome, multiple system atrophy and related disorders, to compare candidate clinical trial endpoints. In this multicentre United Kingdom study, participants were assessed with serial questionnaires, motor examination, neuropsychiatric and magnetic resonance imaging assessments at baseline, six and twelve-months. Participants were classified by diagnosis at baseline and study end, into Richardson syndrome, progressive supranuclear palsy-subcortical (progressive supranuclear palsy-parkinsonism and progressive gait freezing subtypes), progressive supranuclear palsy-cortical (progressive supranuclear palsy-frontal, progressive supranuclear palsy-speech-and-language, and progressive supranuclear palsy-corticobasal syndrome subtypes), multiple system atrophy-parkinsonism, multiple system atrophy-cerebellar, corticobasal syndrome with and without evidence of Alzheimerâs disease pathology and indeterminate syndromes. We calculated annual rate of change, with linear mixed modelling, and sample sizes for clinical trials of disease modifying agents, according to group and assessment type. Two hundred forty-three people were recruited (117 progressive supranuclear palsy, 68 corticobasal syndrome, 42 multiple system atrophy and 16 indeterminate; 138 [56.8%] male; age at recruitment 68.7âÂąâ8.61 years). One hundred fifty-nine completed six-month assessment (82 progressive supranuclear palsy, 27 corticobasal syndrome, 40 multiple system atrophy and 10 indeterminate) and 153 completed twelve-month assessment (80 progressive supranuclear palsy, 29 corticobasal syndrome, 35 multiple system atrophy and 9 indeterminate). Questionnaire, motor examination, neuropsychiatric and neuroimaging measures declined in all groups, with differences in longitudinal change between groups. Neuroimaging metrics would enable lower sample sizes to achieve equivalent power for clinical trials than cognitive and functional measures, often achieving Nâ<â100 required for one-year two-arm trials (with 80% power to detect 50% slowing). However, optimal outcome measures were disease specific. In conclusion, phenotypic variance within progressive supranuclear palsy, corticobasal syndrome and multiple system atrophy is a major challenge to clinical trial design. Our findings provide an evidence base for selection of clinical trial endpoints, from potential functional, cognitive, clinical or neuroimaging measures of disease progression
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