scholarly journals BORDER COLLISION BIFURCATIONS IN THE EVOLUTION OF MUTUALISTIC INTERACTIONS

2005 ◽  
Vol 15 (07) ◽  
pp. 2179-2190 ◽  
Author(s):  
FABIO DERCOLE
Keyword(s):  
Evolutionary Dynamics ◽  
Point Of View ◽  
Flowering Plant ◽  
Physiological Cost ◽  
Border Collision Bifurcations ◽  
Insect Pollinator ◽  
Biological Interest ◽  
Slow Evolution ◽  
Two Parameters ◽  
Trait Space

The paper describes the slow evolution of two adaptive traits that regulate the interactions between two mutualistic populations (e.g. a flowering plant and its insect pollinator). For frozen values of the traits, the two populations can either coexist or go extinct. The values of the traits for which populations extinction is guaranteed are therefore of no interest from an evolutionary point of view. In other words, the evolutionary dynamics must be studied only in a viable subset of trait space, which is bounded due to the physiological cost of extreme trait values. Thus, evolutionary dynamics experience so-called border collision bifurcations, when a system invariant in trait space hits the border of the viable subset. The unfolding of standard and border collision bifurcations with respect to two parameters of biological interest is presented. The algebraic and boundary-value problems characterizing the border collision bifurcations are described together with some details concerning their computation.

scholarly journals The Genomic Ecosystem of Transposable Elements in Maize

2019 ◽  
Author(s):  
Michelle C. Stitzer ◽  
Sarah N. Anderson ◽  
Nathan M. Springer ◽  
Jeffrey Ross-Ibarra
Keyword(s):  
Transposable Elements ◽  
Evolutionary Dynamics ◽  
Phenotypic Diversity ◽  
Flowering Plant ◽  
Genome Wide ◽  
Family Level ◽  
Genomic Environment ◽  
Single Category ◽  
The Impact

Transposable elements (TEs) constitute the majority of flowering plant DNA, reflecting their tremendous success in subverting, avoiding, and surviving the defenses of their host genomes to ensure their selfish replication. More than 85% of the sequence of the maize genome can be ascribed to past transposition, providing a major contribution to the structure of the genome. Evidence from individual loci has informed our understanding of how transposition has shaped the genome, and a number of individual TE insertions have been causally linked to dramatic phenotypic changes. But genome-wide analyses in maize and other taxa have frequently represented TEs as a relatively homogeneous class of fragmentary relics of past transposition, obscuring their evolutionary history and interaction with their host genome. Using an updated annotation of structurally intact TEs in the maize reference genome, we investigate the family-level ecological and evolutionary dynamics of TEs in maize. Integrating a variety of data, from descriptors of individual TEs like coding capacity, expression, and methylation, as well as similar features of the sequence they inserted into, we model the relationship between these attributes of the genomic environment and the survival of TE copies and families. Our analyses reveal a diversity of ecological strategies of TE families, each representing the evolution of a distinct ecological niche allowing survival of the TE family. In contrast to the wholesale relegation of all TEs to a single category of junk DNA, these differences generate a rich ecology of the genome, suggesting families of TEs that coexist in time and space compete and cooperate with each other. We conclude that while the impact of transposition is highly family- and context-dependent, a family-level understanding of the ecology of TEs in the genome can refine our ability to predict the role of TEs in generating genetic and phenotypic diversity.‘Lumping our beautiful collection of transposons into a single category is a crime’-Michael R. Freeling, Mar. 10, 2017

scholarly journals Ecological and evolutionary dynamics of interconnectedness and modularity

2018 ◽  
Vol 115 (4) ◽  
pp. 750-755 ◽  
Author(s):  
Jan M. Nordbotten ◽  
Simon A. Levin ◽  
Eörs Szathmáry ◽  
Nils C. Stenseth
Keyword(s):  
Population Dynamics ◽  
Natural Selection ◽  
Evolution Equation ◽  
Evolutionary Dynamics ◽  
Population Distribution ◽  
Theoretical Framework ◽  
Ecological System ◽  
Macro Level ◽  
Population Distributions ◽  
Trait Space

In this contribution, we develop a theoretical framework for linking microprocesses (i.e., population dynamics and evolution through natural selection) with macrophenomena (such as interconnectedness and modularity within an ecological system). This is achieved by developing a measure of interconnectedness for population distributions defined on a trait space (generalizing the notion of modularity on graphs), in combination with an evolution equation for the population distribution. With this contribution, we provide a platform for understanding under what environmental, ecological, and evolutionary conditions ecosystems evolve toward being more or less modular. A major contribution of this work is that we are able to decompose the overall driver of changes at the macro level (such as interconnectedness) into three components: (i) ecologically driven change, (ii) evolutionarily driven change, and (iii) environmentally driven change.

Development of a new empirical method for Tunnel Squeezing Classification (TSC)

2020 ◽  
Vol 53 (4) ◽  
pp. 655-660 ◽  
Author(s):  
Hadi Farhadian ◽  
Arash Nikvar-Hassani
Keyword(s):  
Quality Index ◽  
Empirical Method ◽  
Point Of View ◽  
Geological Hazard ◽  
Case Histories ◽  
Proposed Model ◽  
Two Parameters ◽  
Classification Tool ◽  
Selection Of

The characterization of squeezing phenomena as a geological hazard is of great importance because squeezing has a crucial role in the selection of the route and type of tunnels and in the characteristics of the excavation device. Tunnel squeezing is also the basis for the designation and construction of tunnelling-related structures. We present a new tunnel squeezing classification tool to predict tunnel squeezing based on two parameters: Q, the tunnelling quality index; and H, the depth of the tunnel. We used data collected from published papers to train the model; these data included 225 case histories from different countries, including Andorra, India, Iran, Japan, Nepal, Spain, Turkey and Venezuela. Validation of the model indicated that our tunnel squeezing classification tool is more accurate than the speculative and analytical methods currently in use. The proposed model will help tunnelling experts to classify tunnelling media from the point of view of squeezing hazards.

scholarly journals Evolution of nutrient acquisition: when adaptation fills the gap between contrasting ecological theories

2010 ◽  
Vol 278 (1704) ◽  
pp. 449-457 ◽  
Author(s):  
S. Boudsocq ◽  
S. Barot ◽  
N. Loeuille
Keyword(s):  
Evolutionary Dynamics ◽  
Plant Biomass ◽  
Adaptive Dynamics ◽  
Ecosystem Model ◽  
Point Of View ◽  
Mineral Nutrient ◽  
Trade Off ◽  
Ecosystem Properties ◽  
Ecological Theories ◽  
Limiting Nutrient

Although plant strategies for acquiring nutrients have been widely studied from a functional point of view, their evolution is still not well understood. In this study, we investigate the evolutionary dynamics of these strategies and determine how they influence ecosystem properties. To do so, we use a simple nutrient-limited ecosystem model in which plant ability to take up nutrients is subject to adaptive dynamics. We postulate the existence of a trade-off between this ability and mortality. We show that contrasting strategies are possible as evolutionary outcomes, depending on the shape of the trade-off and, when nitrogen is considered as the limiting nutrient, on the intensity of symbiotic fixation. Our model enables us to bridge these evolutionary outcomes to classical ecological theories such as Hardin's tragedy of the commons and Tilman's rule of R *. Evolution does not systematically maximize plant biomass or primary productivity. On the other hand, each evolutionary outcome leads to a decrease in the availability of the limiting mineral nutrient, supporting the work of Tilman on competition between plants for a single resource. Our model shows that evolution can be used to link different classical ecological results and that adaptation may influence ecosystem properties in contrasted ways.

scholarly journals A Technical, Economic, and Environmental Performance of Grid-Connected Hybrid (Photovoltaic-Wind) Power System in Algeria

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Djohra Saheb-Koussa ◽  
Mustapha Koussa ◽  
Nourredine Said
Keyword(s):  
Power Systems ◽  
Wind Power ◽  
Weather Conditions ◽  
Energy System ◽  
Point Of View ◽  
Environmental Study ◽  
Economic Point ◽  
Wind Power Systems ◽  
Greenhouse Effects ◽  
Two Parameters

This paper studies the technical, economic, and environmental analysis of wind and photovoltaic power systems connected to a conventional grid. The main interest in such systems is on-site consumption of the produced energy, system hybridization, pooling of resources, and contribution to the environment protection. To ensure a better management of system energy, models have been used for determining the power that the constituting subsystems can deliver under specific weather conditions. Simulation is performed using MATLAB-SIMULINK. While, the economic and environmental study is performed using HOMER software. From an economic point of view, this allows to compare the financial constraints on each part of the system for the case of Adrar site which is located to the northern part of the south of Algeria. It also permits to optimally size and select the system presenting the best features on the basis of two parameters, that is, cost and effectiveness. From an environmental point of view, this study allows highlighting the role of renewable energy in reducing gas emissions related to greenhouse effects. In addition, through a set of sensitivity analysis, it is found that the wind speed has more effects on the environmental and economic performances of grid-connected hybrid (photovoltaic-wind) power systems.

scholarly journals Antibacterial Efficiency of Stainless-Steel Grids Coated with Cu-Ag by Thermionic Vacuum Arc Method

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 322
Author(s):  
P. Dinca ◽  
B. Butoi ◽  
M. Lungu ◽  
C. Porosnicu ◽  
I. Jepu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Natural Ventilation ◽  
High Surface ◽  
Conventional Mechanical Ventilation ◽  
Point Of View ◽  
Vacuum Arc ◽  
Filtering Efficiency ◽  
Thermionic Vacuum Arc ◽  
Two Parameters ◽  
Ventilation Systems

Autonomous smart natural ventilation systems (SVS) attached to the glass façade of living quarters and office buildings can help reducing the carbon footprint of city buildings in the future, especially during warm seasons and can represent an alternative to the conventional mechanical ventilation systems. The work performed in this manuscript focuses on the investigation of bacteria trapping and killing efficiency of stainless steel grids coated with a mixed layer of Cu-Ag. These grids are to be employed as decontamination filters for a smart natural ventilation prototype that we are currently building in our laboratory. The tested grids were coated with a mixed Cu-Ag layer using thermionic vacuum arc plasma processing technology. The fixed deposition geometry allowed the variation of Cu and Ag atomic concentration in coated layers as a function of substrate position in relation to plasma sources. The test conducted with air contaminated with a pathogen strain of staphylococcus aureus indicated that the filtering efficiency is influenced by two parameters: the pore size dimension and the coating layer composition. The results show that the highest filtering efficiency of 100% was obtained for fine pore (0.5 × 0.5 mm) grids coated with a mixed metallic layer composed of 65 at% Cu and 35 at% Ag. The second test performed only on reference grids and Cu-Ag (65–35 at%) under working conditions, confirm a similar filtering efficiency for the relevant microbiological markers. This particular sample was investigated from morphological, structural, and compositional point of view. The results show that the layer has a high surface roughness with good wear resistance and adhesion to the substrate. The depth profiles presented a uniform composition of Cu and Ag in the layer with small variations caused by changes in deposition rates during the coating process. Identification of the two metallic phases of the Cu and Ag in the layers evidences their crystalline nature. The calculated grain size of the nanocrystalline was in the range 14–21 nm.

scholarly journals “Carrefour Louisiane”

2014 ◽  
Vol 7 (1) ◽  
pp. 124-153 ◽  
Author(s):  
Ingrid Neumann-Holzschuh
Keyword(s):  
Language Contact ◽  
Language Change ◽  
Evolutionary Dynamics ◽  
Point Of View ◽  
New Variety ◽  
Dialect Contact ◽  
Cajun French ◽  
Louisiana French ◽  
History Of ◽  
Linguistic Behavior

The history of Louisiana French (LF) is closely related to Louisiana’s particular societal and linguistic ecosystem, characterized by a mixed society where new forms of societal organization emerged and were reflected in new forms of linguistic patterns and linguistic behavior. From the beginning, language contact has been of crucial importance for the emergence, evolution and gradual decline of Louisiana French (“Cajun French”). In colonial times, contact between related French lects resulted in the formation of a new variety of regional French in North America with its own features and its own evolutionary dynamics. The continuing contact with English, however, which takes place in an entirely different ecological frame, results in the ongoing attrition of the minority language. The first part of the article deals with early stages of dialect contact in Louisiana; it will be shown that from a diachronic point of view Louisiana French has to be seen as a product of language mixing and dialect leveling. In the second part two specific aspects of current English-French language contact will be discussed. Both aspects serve to illustrate particularities of the linguistic situation in Louisiana now and then as well as the importance of certain universal mechanisms of contact-induced language change.

A Geometric Approach to a Quantum Counterpart of a Saddle-Node Bifurcation in a 1:1 Resonant Perturbed Oscillator

1998 ◽  
Vol 08 (05) ◽  
pp. 941-950 ◽  
Author(s):  
Yoshio Uwano
Keyword(s):  
Energy Levels ◽  
Geometric Approach ◽  
Pitchfork Bifurcation ◽  
Point Of View ◽  
Saddle Node Bifurcation ◽  
Bifurcation Set ◽  
Saddle Node ◽  
Geometric Point ◽  
Two Parameters ◽  
Quantum Counterpart

In previous papers [Uwano, 1994, 1995], it was shown that a degeneracy of energy levels is a quantum counterpart of a Hamiltonian pitchfork bifurcation of periodic trajectories of a certain 1:1 resonant oscillator with two parameters. As a continuation of those papers, a quantum study is made from a geometric point of view in order to find a quantum counterpart of a saddle-node bifurcation taking place in a certain 1:1 resonant perturbed oscillator with three parameters. The torus quantization method is applied to the perturbed oscillator to show that a degeneracy of energy levels is a quantum counterpart of that bifurcation: The bifurcation set for the saddle-node bifurcation in classical theory is viewed as a "bifurcation set" for the degeneracy of energy levels in quantum theory.

scholarly journals L’uso della toponomastica come indicatore di insediamenti e strutture fortificate: il caso toscano

X ◽  
2020 ◽  
Author(s):  
Camillo Berti ◽  
Massimiliano Grava
Keyword(s):  
Nineteenth Century ◽  
Geographical Information Systems ◽  
Evolutionary Dynamics ◽  
Time Span ◽  
Point Of View ◽  
Geographical Information ◽  
Place Names ◽  
Scientific Contribution ◽  
Different Types ◽  
Diachronic Analysis

The use of toponymy as an indicator of settlements and fortified structures: the Tuscan caseThe purpose of this contribution is to analyze the spatial distribution of the place names referred to the Tuscan territory, to fortified structures and settlements, through the study of the place names recorded geodatabase RE.TO.RE. (Regional Toponymic Repertory) created by the Tuscany Region with the scientific contribution of the Universities of Pisa, Florence and Siena. The Tuscan toponyms has been the object of both a synchronic study within each of the cartographic sources that make up the geographical database, and a diachronic analysis between the temporal thresholds in which the archive is articulated. The database, extrapolated from cartographic supports, in fact covers a time span between the first decades of the nineteenth century (nineteenth century land registries) and the most recent information series produced in the regional context (Carta Tecnica Regionale). In the contribution, the place names related in various ways to different types of structures and fortified settlements, such as castle, fort, tower, fortress, has been analyzed both in relation to the distribution and spatial aspects, and in reference to their evolutionary dynamics (persistence, disappearance, transformation), with the aim of identifying possible relationships between the territory and the distribution in time and space of the different types of fortifications. From a methodological point of view, the study has been carried out, in addition to the traditional tools of the topomastic survey, especially taking advantage of the potential of spatial analysis functions typical of geographical information systems.

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