scholarly journals Analysis of diversity-dependent species evolution using concepts in population genetics

2021 ◽  
Vol 82 (4) ◽  
Author(s):  
Ingemar Kaj ◽  
Sylvain Glémin ◽  
Daniah Tahir ◽  
Martin Lascoux
Keyword(s):  
Population Genetics ◽  
Analytical Framework ◽  
Transition Rates ◽  
Evolutionary Time ◽  
Modeling Tools ◽  
Approximation Techniques ◽  
Conceptual Background ◽  
Species Dynamics ◽  
Species Evolution

AbstractIn this work, we consider a two-type species model with trait-dependent speciation, extinction and transition rates under an evolutionary time scale. The scaling approach and the diffusion approximation techniques which are widely used in mathematical population genetics provide modeling tools and conceptual background to assist in the study of species dynamics, and help exploring the analogy between trait-dependent species diversification and the evolution of allele frequencies in the population genetics setting. The analytical framework specified is then applied to models incorporating diversity-dependence, in order to infer effective results from processes in which the net diversification of species depends on the total number of species. In particular, the long term fate of a rare trait may be analyzed under a partly symmetric scenario, using a time-change transform technique.

Low-Carbon Russia: Prospects after the Crisis

2009 ◽  
pp. 107-120 ◽  
Author(s):  
I. Bashmakov
Keyword(s):  
Economic Growth ◽  
Potential Energy ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Low Carbon ◽  
Modeling Tools ◽  
Gas Emissions ◽  
Scenario Approach

On the eve of the worldwide negotiations of a new climate agreement in December 2009 in Copenhagen it is important to clearly understand what Russia can do to mitigate energy-related greenhouse gas emissions in the medium (until 2020) and in the long term (until 2050). The paper investigates this issue using modeling tools and scenario approach. It concludes that transition to the "Low-Carbon Russia" scenarios must be accomplished in 2020—2030 or sooner, not only to mitigate emissions, but to block potential energy shortages and its costliness which can hinder economic growth.

scholarly journals Biogeochemical Controls on the Redox Evolution of Earth’s Oceans and Atmosphere

Elements ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Christopher T. Reinhard ◽  
Noah J. Planavsky
Keyword(s):  
Redox State ◽  
Modeling Tools ◽  
Evolutionary Trajectory ◽  
Geochemical Tracers ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
Dramatic Shift ◽  
Redox Evolution

The redox state of Earth’s atmosphere has undergone a dramatic shift over geologic time from reducing to strongly oxidizing, and this shift has been coupled with changes in ocean redox structure and the size and activity of Earth’s biosphere. Delineating this evolutionary trajectory remains a major problem in Earth system science. Significant insights have emerged through the application of redox-sensitive geochemical systems. Existing and emerging biogeochemical modeling tools are pushing the limits of the quantitative constraints on ocean–atmosphere redox that can be extracted from geochemical tracers. This work is honing our understanding of the central role of Earth’s biosphere in shaping the long-term redox evolution of the ocean–atmosphere system.

scholarly journals Adopt, adapt, or abandon technology-supported person-centred care initiatives: healthcare providers’ beliefs matter

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kari Dyb ◽  
Gro Rosvold Berntsen ◽  
Lisbeth Kvam
Keyword(s):  
Information Technologies ◽  
Scale Up ◽  
Healthcare Providers ◽  
Healthcare Services ◽  
Analytical Framework ◽  
Development Project ◽  
Technology Support ◽  
Care Needs ◽  
Term Care

Abstract Background Technology support and person-centred care are the new mantra for healthcare programmes in Western societies. While few argue with the overarching philosophy of person-centred care or the potential of information technologies, there is less agreement on how to make them a reality in everyday clinical practice. In this paper, we investigate how individual healthcare providers at four innovation arenas in Scandinavia experienced the implementation of technology-supported person-centred care for people with long-term care needs by using the new analytical framework nonadoption, abandonment, and challenges to the scale-up, spread, and sustainability (NASSS) of health and care technologies. We also discuss the usability and sensitivity of the NASSS framework for those seeking to plan, implement, and evaluate technology-supported healthcare programmes. This study is part of an interdisciplinary research and development project called Patients and Professionals in Partnership (2016–2020). It originates at one of ten work packages in this project. Method The main data consist of ethnographic field observations at the four innovation arenas and 29 interviews with involved healthcare providers. To ensure continuous updates and status on work in the four innovation arenas, we have also participated in a total of six annual network meetings arranged by the project. Results While the NASSS framework is very useful for identifying and communicating challenges with the adoption and spread of technology-supported person-centred care initiatives, we found it less sensitive towards capturing the dedication, enthusiasm, and passion for care transformation that we found among the healthcare providers in our study. When it comes to technology-supported person-centred care, the point of no return has passed for the involved healthcare providers. To them, it is already a definite part of the future of healthcare services. How to overcome barriers and obstacles is pragmatically approached. Conclusion Increased knowledge about healthcare providers and their visions as potential assets for care transformation might be critical for those seeking to plan, implement, and evaluate technology-supported healthcare programmes.

scholarly journals Modeling cesium migration through Opalinus clay: a benchmark for single- and multi-species sorption-diffusion models

2021 ◽  
Author(s):  
Jesús F. Águila ◽  
Vanessa Montoya ◽  
Javier Samper ◽  
Luis Montenegro ◽  
Georg Kosakowski ◽  
...  
Keyword(s):  
Time Discretization ◽  
Single Species ◽  
Opalinus Clay ◽  
Sorption Behavior ◽  
Diffusion Experiment ◽  
Modeling Tools ◽  
Cesium Sorption ◽  
Code Performance ◽  
Good Agreement

AbstractSophisticated modeling of the migration of sorbing radionuclides in compacted claystones is needed for supporting the safety analysis of deep geological repositories for radioactive waste, which requires robust modeling tools/codes. Here, a benchmark related to a long term laboratory scale diffusion experiment of cesium, a moderately sorbing radionuclide, through Opalinus clay is presented. The benchmark was performed with the following codes: CORE2DV5, Flotran, COMSOL Multiphysics, OpenGeoSys-GEM, MCOTAC and PHREEQC v.3. The migration setup was solved with two different conceptual models, i) a single-species model by using a look-up table for a cesium sorption isotherm and ii) a multi-species diffusion model including a complex mechanistic cesium sorption model. The calculations were performed for three different cesium boundary concentrations (10−3, 10−5, 10−7 mol / L) to investigate the models/codes capabilities taking into account the nonlinear sorption behavior of cesium. Generally, good agreement for both single- and multi-species benchmark concepts could be achieved, however, some discrepancies have been identified, especially near the boundaries, where code specific spatial (and time) discretization had to be improved to achieve better agreement at the expense of longer computation times. In addition, the benchmark exercise yielded useful information on code performance, setup options, input and output data management, and post processing options. Finally, the comparison of single-species and multi-species model concepts showed that the single-species approach yielded generally earlier breakthrough, because this approach accounts neither for cation exchange of Cs+ with K+ and Na+, nor K+ and Na+ diffusion in the pore water.

scholarly journals Branching processes with interactions: subcritical cooperative regime

2021 ◽  
Vol 53 (1) ◽  
pp. 251-278
Author(s):  
Adrián González Casanova ◽  
Juan Carlos Pardo ◽  
José Luis Pérez
Keyword(s):  
Population Genetics ◽  
Branching Processes ◽  
Jump Diffusion ◽  
Pairwise Interaction ◽  
Pairwise Interactions ◽  
Different Types ◽  
Interesting Object ◽  
The Moment ◽  
Dynamics Of Populations

AbstractIn this paper, we introduce a family of processes with values on the nonnegative integers that describes the dynamics of populations where individuals are allowed to have different types of interactions. The types of interactions that we consider include pairwise interactions, such as competition, annihilation, and cooperation; and interactions among several individuals that can be viewed as catastrophes. We call such families of processes branching processes with interactions. Our aim is to study their long-term behaviour under a specific regime of the pairwise interaction parameters that we introduce as the subcritical cooperative regime. Under such a regime, we prove that a process in this class comes down from infinity and has a moment dual which turns out to be a jump-diffusion that can be thought as the evolution of the frequency of a trait or phenotype, and whose parameters have a classical interpretation in terms of population genetics. The moment dual is an important tool for characterizing the stationary distribution of branching processes with interactions whenever such a distribution exists; it is also an interesting object in its own right.

scholarly journals Slavery and Its Transformations: Prolegomena for a Global and Comparative Research Agenda

2021 ◽  
Vol 63 (3) ◽  
pp. 566-598
Author(s):  
Matthias van Rossum
Keyword(s):  
Comparative Research ◽  
Research Agenda ◽  
Analytical Framework ◽  
The Body ◽  
Indonesian Archipelago ◽  
Research Perspectives ◽  
History Of ◽  
The Indian Ocean ◽  
Contemporary Development

AbstractThis article argues that we need to move beyond the “Atlantic” and “formal” bias in our understanding of the history of slavery. It explores ways forward toward developing a better understanding of the long-term global transformations of slavery. Firstly, it claims we should revisit the historical and contemporary development of slavery by adopting a wider scope that accounts for the adaptable and persistent character of different forms of slavery. Secondly, it stresses the importance of substantially expanding the body of empirical observations on trajectories of slavery regimes, especially outside the Atlantic, and most notable in the Indian Ocean and Indonesian Archipelago worlds, where different slavery regimes existed and developed in interaction. Thirdly, it proposes an integrated analytical framework that will overcome the current fragmentation of research perspectives and allow for a more comparative analysis of the trajectories of slavery regimes in their highly diverse formal and especially informal manifestations. Fourth, the article shows how an integrated framework will enable a collaborative research agenda that focuses not only on comparisons, but also on connections and interactions. It calls for a closer integration of the histories of informal slavery regimes into the wider body of existing scholarship on slavery and its transformations in the Atlantic and other more intensely studied formal slavery regimes. In this way, we can renew and extend our understandings of slavery's long-term, global transformations.

scholarly journals Comets (Existing Populations)

1994 ◽  
Vol 160 ◽  
pp. 77-94
Author(s):  
Ľ. Kresák
Keyword(s):  
Kuiper Belt ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
Survival Times ◽  
Evolutionary Time ◽  
Origin And Evolution ◽  
History Of ◽  
The Individual ◽  
Evolutionary Paths

The definition, population, extent, origin and evolution of the individual subsystems of comets and transitions between them are discussed, together with presentation of the relevant statistical data and their changes with time. The largest outer subsystems are unobservable, but their existence is documented by the necessity of progressive replenishment of the observable populations, with limited survival times. There is persuasive evidence for two different evolutionary paths, one from the Oort cloud and another from the Kuiper belt. While the extent and accuracy of the data available is increasing rapidly, the Jupiter family of comets is the only one for which the evolutionary time scales do not exceed by many orders of magnitude the history of astronomical observations. The individual comet populations differ from one another not only by the distribution of orbits, but also by the size distribution and aging rate of their members. Their dynamical evolution is coupled with disintegration processes, which make it questionable whether the present state can be interpreted as a long-term average.

scholarly journals An analytical framework for strategic delta planning: negotiating consent for long-term sustainable delta development

2016 ◽  
Vol 60 (8) ◽  
pp. 1485-1509 ◽  
Author(s):  
C. Seijger ◽  
W. Douven ◽  
G. van Halsema ◽  
L. Hermans ◽  
J. Evers ◽  
...  
Keyword(s):  
Analytical Framework

Challenges for Diadromous Fishes in a Dynamic Global Environment

2009 ◽  
Keyword(s):  
Life Cycle ◽  
Life Histories ◽  
Life Cycles ◽  
Partial Migration ◽  
Environmental Stochasticity ◽  
Species Dynamics ◽  
Life Cycle Pattern ◽  
Aquatic Sciences ◽  
Diversity Of Life

<em>Abstract</em>.-In the study of species life histories and the structure of diadromous populations, an emerging trend is the prevalence of life cycle diversity-that is, individuals within populations that do not conform to a single life cycle pattern. A rapid rise in publications documenting within-population variability in life cycles has resulted in the use of numerous terms and phrases. We argue that myriad terms specific to taxa, ecosystem types, and applications are in fact describing the same phenomenon-life cycle diversity. This phenomenon has been obscured by the use of multiple terms across applications, but also by the overuse of typologies (i.e., anadromy, catadromy) that fail to convey the extent of life cycle variations that underlay population, metapopulation, and species dynamics. To illustrate this, we review migration and habitat-use terms that have been used to describe life cycles and life cycle variation. Using a citation index (Cambridge Scientific Abstracts © Aquatic Sciences and Fisheries Abstracts), terms were tallied across taxonomic family, ecosystem, type of application, analytical approach, and country of study. Studies on life cycle diversity have increased threefold during the past 15 years, with a total of 336 papers identified in this review. Most of the 40 terms we identified described either sedentary or migratory lifetime behaviors. The sedentary-migratory dichotomy fits well with the phenomenon of partial migration, which has been commonly reported for birds and Salmonidae and is postulated to be the result of early life thresholds (switch-points). On the other hand, the lexicon supports alternate modes of migration, beyond the simple sedentary-migratory dichotomy. Here more elaborate causal mechanisms such as the entrainment hypothesis may have application. Diversity of life cycles in fish populations, whether due to partial migration, entrainment, or other mechanisms, is increasingly recognized as having the effect of offsetting environmental stochasticity and contributing to long-term persistence.

Validation of Reanalysis-Based Offshore Wind Resource Characterization Using Lidar Buoy Observations

2020 ◽  
Vol 54 (6) ◽  
pp. 44-61
Author(s):  
Lindsay M. Sheridan ◽  
Raghavendra Krishnamurthy ◽  
Alicia M. Gorton ◽  
Will J. Shaw ◽  
Rob K. Newsom
Keyword(s):  
Pacific Northwest ◽  
National Laboratory ◽  
Pacific Northwest National Laboratory ◽  
The United States ◽  
Department Of Energy ◽  
Offshore Wind ◽  
Approximation Techniques ◽  
The North ◽  
Wind Resource

AbstractThe offshore wind industry in the United States is gaining strong momentum to achieve sustainable energy goals, and the need for observations to provide resource characterization and model validation is greater than ever. Pacific Northwest National Laboratory (PNNL) operates two lidar buoys for the U.S. Department of Energy (DOE) in order to collect hub height wind data and associated meteorological and oceanographic information near the surface in areas of interest for offshore wind development. This work evaluates the performance of commonly used reanalysis products and spatial approximation techniques using lidar buoy observations off the coast of New Jersey and Virginia, USA. Reanalysis products are essential tools for setting performance expectations and quantifying the wind resource variability at a given site. Long-term accurate observations at typical wind turbine hub heights have been lacking at offshore locations. Using wind speed observations from both lidar buoy deployments, biases and degrees of correspondence for the Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA-2), the North American Regional Reanalysis (NARR), ERA5, and the analysis system of the Rapid Refresh (RAP) are examined both at hub height and near the surface. Results provide insights on the performance and uncertainty of using reanalysis products for long-term wind resource characterization. A slow bias is seen across the reanalyses at both deployment sites. Bias magnitudes near the surface are on the order of 0.5 m s−1 greater than their hub height counterparts. RAP and ERA5 produce the highest correlations with the observations, around 0.9, followed by MERRA-2 and NARR.

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