Nonparametric estimation of effect heterogeneity in rare events meta-analysis: Bivariate, discrete mixture model

This is the author accepted manuscript. The final version is available from Springer via the DOI in this recordAbstract: Meta-analysis provides an integrated analysis and summary of the effects observed in k independent studies. The conventional analysis proceeds by first calculating a study-specific effect estimate, and then provides further analysis on the basis of the available k independent effect estimates associated with their uncertainty measures. Here we consider a setting where counts of events are available from k independent studies for a treatment and a control group. We suggest to model this situation with a study-specific Poisson regression model, and allow the study-specific parameters of the Poisson model to arise from a nonparametric mixture model. This approach then allows the estimation of the heterogeneity variance of the effect measure of interest in a nonparametric manner. A case study is used to illustrate the methodology throughout the paper

Recent developments in life and social science applications of capture–recapture methods.

Over the last 20 years capture-recapture methods have experienced important developments, in particular in their applications in the life and social sciences. It appears appropriate to take a closer look at some of these developments. A recent conference entitled Recent Developments in Capture-Recapture Methods and their Applications was held in 2007 at The University of Reading. A special issue focusing on applications mainly in the Biological Sciences appeared elsewhere (Böhning 2008), whereas in this special topic we would like to focus more on life and social science applications. The capture-recapture or mark-and-recapture methodology goes back to the Biological/Ecological Sciences with the work of Lincoln and Petersen. About one hundred and ten years ago Petersen (1896) published his landmark paper suggesting what later became known as the Lincoln-Petersen estimator, since it was also independently developed b

Rationality of quotients by linear actions of affine groups

Let G be the (special) affine group, semidirect product of SL_n and C^n. In this paper we study the representation theory of G and in particular the question of rationality for V/G where V is a generically free G-representation. We show that the answer to this question is positive if the dimension of V is sufficiently large and V is indecomposable. We have a more precise theorem if V is a two-step extension 0 -> S -> V -> Q -> 0 with S, Q completely reducible.Comment: 18 pages; dedicated to Fabrizio Catanese on the occasion of his 60th birthda

Predicting replacement of smartphones with mobile app usage

© Springer International Publishing AG 2016. To identify right customers who intend to replace the smart phone can help to perform precision marketing and thus bring significant financial gains to cell phone retailers. In this paper,we provide a study of exploiting mobile app usage for predicting users who will change the phone in the future. We first analyze the characteristics of mobile log data and develop the temporal bag-of-apps model,which can transform the raw data to the app usage vectors. We then formularize the prediction problem,present the hazard based prediction model,and derive the inference procedure. Finally,we evaluate both data model and prediction model on real-world data. The experimental results show that the temporal usage data model can effectively capture the unique characteristics of mobile log data,and the hazard based prediction model is thus much more effective than traditional classification methods. Furthermore,the hazard model is explainable,that is,it can easily show how the replacement of smart phones relate to mobile app usage over time

D-optimal designs via a cocktail algorithm

A fast new algorithm is proposed for numerical computation of (approximate) D-optimal designs. This "cocktail algorithm" extends the well-known vertex direction method (VDM; Fedorov 1972) and the multiplicative algorithm (Silvey, Titterington and Torsney, 1978), and shares their simplicity and monotonic convergence properties. Numerical examples show that the cocktail algorithm can lead to dramatically improved speed, sometimes by orders of magnitude, relative to either the multiplicative algorithm or the vertex exchange method (a variant of VDM). Key to the improved speed is a new nearest neighbor exchange strategy, which acts locally and complements the global effect of the multiplicative algorithm. Possible extensions to related problems such as nonparametric maximum likelihood estimation are mentioned.Comment: A number of changes after accounting for the referees' comments including new examples in Section 4 and more detailed explanations throughou

Fewer COVID-19 neurological complications with dexamethasone and remdesivir

OBJECTIVE: To assess the impact of treatment with dexamethasone, remdesivir or both on neurological complications in acute COVID-19. METHODS: We used observational data from the International Severe Acute and emerging Respiratory Infection Consortium (ISARIC) WHO Clinical Characterisation Protocol UK (CCP-UK). Hospital inpatients aged ≥18 years with laboratory-confirmed SARS-CoV-2 infection admitted between 31 January 2020 and 29 June 2021 were included. Treatment allocation was non-blinded and performed by reporting clinicians. A propensity scoring methodology was used to minimize confounding. Treatment with remdesivir, dexamethasone or both was assessed against standard of care. The primary outcome was a neurological complication occurring at the point of death, discharge, or resolution of the COVID-19 clinical episode. RESULTS: Out of 89,297 hospital inpatients, 64,088 had severe COVID-19 and 25,209 had non-hypoxic COVID-19. Neurological complications developed in 4.8% and 4.5% respectively. In both groups, neurological complications associated with increased mortality, ICU admission, worse self-care on discharge and time to recovery. In severe COVID-19, treatment with dexamethasone (n=21,129), remdesivir (n=1,428) and both combined (n=10,846) associated with a lower frequency of neurological complications: OR=0.76 (95% CI=0.69-0.83), OR 0.69 (95% CI=0.51-0.90) and OR=0.54, (95% CI=0.47-0.61) respectively. In non-hypoxic COVID-19, dexamethasone (n=2,580) associated with less neurological complications (OR=0.78, 95% CI 0.62-0.97), while the dexamethasone/remdesivir combination (n=460) showed a similar trend (OR=0.63, 95% CI=0.31-1.15). INTERPRETATION: Treatment with dexamethasone, remdesivir or both in patients hospitalised with COVID-19 associated with a lower frequency of neurological complications in an additive manner, such that the greatest benefit was observed in patients who received both drugs together. This article is protected by copyright. All rights reserved

Avian seed dispersal may be insufficient for plants to track future temperature change on tropical mountains

AIM: Climate change causes shifts in species ranges globally. Terrestrial plant species often lag behind temperature shifts, and it is unclear to what extent animal-dispersed plants can track climate change. Here, we estimate the ability of bird-dispersed plant species to track future temperature change on a tropical mountain. LOCATION: Tropical elevational gradient (500–3500 m.a.s.l.) in the Manú biosphere reserve, Peru. TIME PERIOD: From 1960–1990 to 2061–2080. TAXA: Fleshy-fruited plants and avian frugivores. METHODS: Using simulations based on the functional traits of avian frugivores and fruiting plants, we quantified the number of long-distance dispersal (LDD) events that woody plant species would require to track projected temperature shifts on a tropical mountain by the year 2070 under different greenhouse gas emission scenarios [representative concentration pathway (RCP) 2.6, 4.5 and 8.5]. We applied this approach to 343 bird-dispersed woody plant species. RESULTS: Our simulations revealed that bird-dispersed plants differed in their climate-tracking ability, with large-fruited and canopy plants exhibiting a higher climate-tracking ability. Our simulations also suggested that even under scenarios of strong and intermediate mitigation of greenhouse gas emissions (RCP 2.6 and 4.5), sufficient upslope dispersal would require several LDD events by 2070, which is unlikely for the majority of woody plant species. Furthermore, the ability of plant species to track future changes in temperature increased in simulations with a low degree of trait matching between plants and birds, suggesting that plants in generalized seed-dispersal systems might be more resilient to climate change. MAIN CONCLUSION: Our study illustrates how the functional traits of plants and animals can inform predictive models of species dispersal and range shifts under climate change and suggests that the biodiversity of tropical mountain ecosystems is highly vulnerable to future warming. The increasing availability of functional trait data for plants and animals globally will allow parameterization of similar models for many other seed-dispersal systems

Similar composition of functional roles in Andean seed-dispersal networks, despite high species and interaction turnover

The species composition of local communities varies in space, and its similarity generally decreases with increasing geographic distance between communities, a phenomenon known as distance decay of similarity. It is, however, not known how changes in local species composition affect ecological processes, that is, whether they lead to differences in the local composition of species' functional roles. We studied eight seed-dispersal networks along the South American Andes and compared them with regard to their species composition and their composition of functional roles. We tested (1) if changes in bird species composition lead to changes in the composition of bird functional roles, and (2) if the similarity in species composition and functional-role composition decreased with increasing geographic distance between the networks. We also used cluster analysis to (3) identify bird species with similar roles across all networks based on the similarity in the plants they consume, (i) considering only the species identity of the plants and (ii) considering the functional traits of the plants. Despite strong changes in species composition, the networks along the Andes showed similar composition of functional roles. (1) Changes in species composition generally did not lead to changes in the composition of functional roles. (2) Similarity in species composition, but not functional-role composition, decreased with increasing geographic distance between the networks. (3) The cluster analysis considering the functional traits of plants identified bird species with similar functional roles across all networks. The similarity in functional roles despite the high species turnover suggests that the ecological process of seed dispersal is organized similarly along the Andes, with similar functional roles fulfilled locally by different sets of species. The high species turnover, relative to functional turnover, also indicates that a large number of bird species are needed to maintain the seed-dispersal process along the Andes.Fil: Dehling, D. Matthias. University of Canterbury; Nueva ZelandaFil: Peralta, Guadalupe. University of Canterbury; Nueva ZelandaFil: Bender, Irene Maria Antoinetta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Böhning Gaese, Katrin. Goethe Universitat Frankfurt; AlemaniaFil: Muñoz, Marcia C.. Universidad de la Salle; ColombiaFil: Neuschulz, Eike Lena. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Quitián, Marta. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Saavedra, Francisco. Universidad Mayor de San Andrés; BoliviaFil: Santillán, Vinicio. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Schleuning, Matthias. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Stouffer, Daniel B.. University of Canterbury; Nueva Zeland

Avian seed dispersal may be insufficient for plants to track future temperature change on tropical mountains

[Aim] Climate change causes shifts in species ranges globally. Terrestrial plant species often lag behind temperature shifts, and it is unclear to what extent animal-dispersed plants can track climate change. Here, we estimate the ability of bird-dispersed plant species to track future temperature change on a tropical mountain.[Location] Tropical elevational gradient (500–3500 m.a.s.l.) in the Manú biosphere reserve, Peru. [Time period] From 1960–1990 to 2061–2080. [Taxa] Fleshy-fruited plants and avian frugivores. [Methods] Using simulations based on the functional traits of avian frugivores and fruiting plants, we quantified the number of long-distance dispersal (LDD) events that woody plant species would require to track projected temperature shifts on a tropical mountain by the year 2070 under different greenhouse gas emission scenarios [representative concentration pathway (RCP) 2.6, 4.5 and 8.5]. We applied this approach to 343 bird-dispersed woody plant species. [Results] Our simulations revealed that bird-dispersed plants differed in their climate-tracking ability, with large-fruited and canopy plants exhibiting a higher climate-tracking ability. Our simulations also suggested that even under scenarios of strong and intermediate mitigation of greenhouse gas emissions (RCP 2.6 and 4.5), sufficient upslope dispersal would require several LDD events by 2070, which is unlikely for the majority of woody plant species. Furthermore, the ability of plant species to track future changes in temperature increased in simulations with a low degree of trait matching between plants and birds, suggesting that plants in generalized seed-dispersal systems might be more resilient to climate change. [Main conclusion] Our study illustrates how the functional traits of plants and animals can inform predictive models of species dispersal and range shifts under climate change and suggests that the biodiversity of tropical mountain ecosystems is highly vulnerable to future warming. The increasing availability of functional trait data for plants and animals globally will allow parameterization of similar models for many other seed-dispersal systems.Fieldwork at Manú was conducted under the permits 041-2010-AG-DGFFSDGEFFS, 008-2011-AG-DGFFS-DGEFFS, 01-C/C-2010SERNANP-JPNM and 01-2011-SERNANP-PNM-JEF and supported by a scholarship from the German Academic Exchange Service to D.M.D. D.M.D. acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant number 787638) and the Swiss National Science Foundation (grant number 173342), both awarded to C. H. Graham. W.D.K. acknowledges a Global Ecology grant from the University of Amsterdam Faculty Research Cluster. I.D. was funded by the Alexander von Humboldt Foundation and is now supported by the Balearic Government. S.A.F. was funded by the German Research Foundation (DFG; FR 3246/2-2) and the Leibniz Competition of the Leibniz Association (P52/2017)