ipmr: flexible implementation of integral projection models in R

1. Integral projection models (IPMs) are an important tool for studying the dynamics of populations structured by one or more continuous traits (e.g. size, height, body mass). Researchers use IPMs to investigate questions ranging from linking drivers to population dynamics, planning conservation and management strategies, and quantifying selective pressures in natural populations. The popularity of stage-structured population models has been supported by R scripts and packages (e.g. IPMpack, popbio, popdemo, lefko3) aimed at ecologists, which have introduced a broad repertoire of functionality and outputs. However, pressing ecological, evolutionary and conservation biology topics require developing more complex IPMs, and considerably more expertise to implement them. Here, we introduce ipmr, a flexible R package for building, analysing and interpreting IPMs. 2. The ipmr framework relies on the mathematical notation of the models to express them in code format. Additionally, this package decouples the model parameterization step from the model implementation step. The latter point substantially increases ipmr's flexibility to model complex life cycles and demographic processes. 3. ipmr can handle a wide variety of models, including those that incorporate density dependence, discretely and continuously varying stochastic environments, and multiple continuous and/or discrete traits. ipmr can accommodate models with individuals cross-classified by age and size. Furthermore, the package provides methods for demographic analyses (e.g. asymptotic and stochastic growth rates) and visualization (e.g. kernel plotting). 4. ipmr is a flexible R package for integral projection models. The package substantially reduces the amount of time required to implement general IPMs. We also provide extensive documentation with six vignettes and help files, accessible from an R session and online

Nernst Effect and Anomalous Transport in Cuprates: A Preformed-Pair Alternative to the Vortex Scenario

We address those puzzling experiments in underdoped high $T_c$ superconductors which have been associated with normal state "vortices" and show these data can be understood as deriving from preformed pairs with onset temperature $T^* > T_c$. For uncorrelated bosons in small magnetic fields, and arbitrary $T^*/T_c$, we present the exact contribution to \textit{all} transport coefficients. In the overdoped regime our results reduce to those of standard fluctuation theories ($T^*\approx T_c$). Semi-quantitative agreement with Nernst, ac conductivity and diamagnetic measurements is quite reasonable.Comment: 9 pages, 4 figures; Title, abstract and contents modified, new references added, figures changed, one more figure added; to be published on PR

Theory of Neutron Scattering in the Normal and Superconducting State of YBCO

We analyze neutron experiments on \ybco at various stoichiometries in the superconducting state, within the context of a bi-layer theory which yields good agreement with the normal state Cu-NMR and neutron data as a function of \omega, q and T. A d-wave superconducting state exhibits peaks at q = ( \pi , \pi , \pi ) and sharp maxima as a function of \omega, at twice the gap frequency. This behavior may have been observed experimentally. The counterpart behavior for other choices of order parameter symmetry is discussed.Comment: uuencoded postscript file for the entire paper enclose

Global analysis reveals complex demographic responses of mammals to climate change

Approximately 25 % of mammals are threatened globally with extinction, a risk that is amplified under climate change1. Persistence under climate change is determined by the combined effects of climatic factors on multiple demographic rates (survival, development, reproduction), and hence, on population dynamics2. Thus, to quantify which species and places on Earth are most vulnerable to climate-driven extinction, a global understanding of how demographic rates respond to climate is needed3. We synthesise information on such responses in terrestrial mammals, where extensive demographic data are available4. Given the importance of assessing the full spectrum of responses, we focus on studies that quantitatively link climate to multiple demographic rates. We identify 106 such studies, corresponding to 86 mammal species. We reveal a strong mismatch between the locations of demographic studies and the regions and taxa currently recognised as most vulnerable to climate change5,6. Moreover, we show that the effects of climate change on mammals will operate via complex demographic mechanisms: a vast majority of mammal populations display projected increases in some demographic rates but declines in others. Assessments of population viability under climate change therefore need to account for multiple demographic responses. We advocate to prioritise coordinated actions to assess mammal demography holistically for effective conservation worldwide

Herbaceous perennial plants with short generation time have stronger responses to climate anomalies than those with longer generation time

There is an urgent need to synthesize the state of our knowledge on plant responses to climate. The availability of open-access data provide opportunities to examine quantitative generalizations regarding which biomes and species are most responsive to climate drivers. Here, we synthesize time series of structured population models from 162 populations of 62 plants, mostly herbaceous species from temperate biomes, to link plant population growth rates (λ) to precipitation and temperature drivers. We expect: (1) more pronounced demographic responses to precipitation than temperature, especially in arid biomes; and (2) a higher climate sensitivity in short-lived rather than long-lived species. We find that precipitation anomalies have a nearly three-fold larger effect on λ than temperature. Species with shorter generation time have much stronger absolute responses to climate anomalies. We conclude that key species-level traits can predict plant population responses to climate, and discuss the relevance of this generalization for conservation planning

The myriad of complex demographic responses of terrestrial mammals to climate change and gaps of knowledge : a global analysis

1. Approximately 25% of mammals are currently threatened with extinction, a risk that is amplified under climate change. Species persistence under climate change is determined by the combined effects of climatic factors on multiple demographic rates (survival, development and reproduction), and hence, population dynamics. Thus, to quantify which species and regions on Earth are most vulnerable to climate-driven extinction, a global understanding of how different demographic rates respond to climate is urgently needed. 2. Here, we perform a systematic review of literature on demographic responses to climate, focusing on terrestrial mammals, for which extensive demographic data are available. 3. To assess the full spectrum of responses, we synthesize information from studies that quantitatively link climate to multiple demographic rates. We find only 106 such studies, corresponding to 87 mammal species. These 87 species constitute <1% of all terrestrial mammals. 4. Our synthesis reveals a strong mismatch between the locations of demographic studies and the regions and taxa currently recognized as most vulnerable to climate change. Surprisingly, for most mammals and regions sensitive to climate change, holistic demographic responses to climate remain unknown. At the same time, we reveal that filling this knowledge gap is critical as the effects of climate change will operate via complex demographic mechanisms: a vast majority of mammal populations display projected increases in some demographic rates but declines in others, often depending on the specific environmental context, complicating simple projections of population fates. 5. Assessments of population viability under climate change are in critical need to gather data that account for multiple demographic responses, and coordinated actions to assess demography holistically should be prioritized for mammals and other taxa

Rpadrino : an R package to access and use PADRINO, an open access database of Integral Projection Models

Discrete time structured population projection models are an important tool for studying population dynamics. Within this field, Integral Projection Models (IPMs) have become a popular method for studying populations structured by continuously distributed traits (e.g. height, weight). Databases of discrete time, discrete state structured population models, for example DATLife (life tables) and COMPADRE & COMADRE (matrix population models), have made quantitative syntheses straightforward to implement. These efforts allow researchers to address questions in both basic and applied ecology and evolutionary biology. Since their introduction in 2000, over 300 works containing IPMs have been published, offering opportunities for ecological synthesis too. We describe a novel framework to quickly reconstruct these models for subsequent analyses using Rpadrino R package, which serves as an interface to PADRINO, a new database of IPMs. We introduce an R package, Rpadrino, which enables users to download, subset, reconstruct, and extend published IPMs. Rpadrino makes use of recently created software, ipmr, to provide an engine to reconstruct a wide array of IPMs from their symbolic representations and conduct subsequent analyses. Rpadrino and ipmr are extensively documented to help users learn their usage. Rpadrino currently enables users to reconstruct 280 IPMs from 40 publications that describe the demography of 14 animal and 26 plant species. All of these IPMs are tested to ensure they reproduce published estimates. Rpadrino provides an interface to augment PADRINO with external data and modify parameter values, creating a platform to extend models beyond their original purpose while retaining full reproducibility. PADRINO and Rpadrino provide a toolbox for asking new questions and conducting syntheses with peer-reviewed published IPMs. Rpadrino provides a user-friendly interface so researchers do not need to worry about the database structure or syntax, and can focus on their research questions and analyses. Additionally, Rpadrino is thoroughly documented, and provides numerous examples of how to perform analyses which are not included in the package’s functionality

Leadership and trust: Their effect on knowledge sharing and team performance

Team leaders who facilitate knowledge sharing and engender trust contribute to team effectiveness. While the separate effects of leadership, trust and knowledge sharing on team performance are well documented, few scholars have investigated the specific links between these factors. This study examines the relationship between the leader as the knowledge builder, trust in the leader and in the team, knowledge sharing and team performance. Surveys were collected from 34 engineering project teams (n=166 team members, 30 team leaders) and 18 managers in a large automotive organization. The results indicate that by building the team's expertise, leaders enhance team members' willingness to rely on and disclose information in the team, which in turn increases team knowledge sharing. Team knowledge sharing significantly predicted leaders' and managers' ratings of team performance. The theoretical and practical implications of the findings are discussed

Trust and Consequences: A Visual Perspective

Abstract. User interface (UI) composition and information presentation can impact human trust behavior. Trust is a complex concept studied by disciplines like psychology, sociology, economics, and computer science. Definitions of trust vary depending on the context, but are typically based on the core concept of “reliance on another person or entity”. Trust is a critical concept since the presence or absence of the right level of trust can affect user behavior, and ultimately, the overall system performance. In this paper, we look across four studies to explore the relationship between UI elements and human trust behavior. Results indicate that UI composition and information presentation can impact human trust behavior. While further research is required to corroborate and generalize these results, we hope that this paper will provide a reference point for future studies by identifying UI elements that are likely to influence human trust