Non-Gaussian elasticity and charge density-dependent swelling of strong polyelectrolyte poly(N-isopropylacrylamide-co-sodium acrylate) hydrogels

Soft Matter ◽  
2017 ◽  
Vol 13 (47) ◽  
pp. 9046-9059
Author(s):  
Nermin Orakdogen ◽  
Talin Boyacı
Keyword(s):  
Elastic Modulus ◽  
Charge Density ◽  
Density Dependence ◽  
Sodium Acrylate ◽  
Density Dependent ◽  
Volume Dependence ◽  
Non Gaussian

The charge density dependence of swelling and volume dependence of the elastic modulus were investigated with a predicted course of non-Gaussian elasticity ofN-isopropylacrylamide-based hydrogels.

Hysteresis in thermal expansion of the quasi 1-dimensional conductor TaS3: Coupling of the underlying and the electronic crystals

2002 ◽  
Vol 12 (9) ◽  
pp. 287-287
Author(s):  
V. Ya. Pokrovskii ◽  
A. V. Golovnya ◽  
P. M. Shadrin
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
Charge Density ◽  
Hysteresis Loop ◽  
Charge Density Waves ◽  
Small Sample ◽  
Temperature Hysteresis ◽  
Static Regime ◽  
Peierls Transition ◽  
Sample Elongation

An interferometer-based setup for measurements of length of needle-like samples is developed, and thermal expansion of o-TaS3 crystals is studied. Below the Peierls transition the temperature hysteresis of length L is observed, the width of the hysteresis loop $\delta L/L$ being up to $5\times 10^{-5}$. Curiously, $L(T)$ changes so that it is in front of its equilibrium value. The hysteresis loop couples with that of conductivity. With lowering T the charge-density waves' (CDW) elastic modulus grows and at 100 K becomes comparable with that of the lattice Yl. The results justify the assumption about the strain dependence of the CDW wave vector and clarify the nature of the anomalies of Yl which occur on the CDW depinning. In particular, Yl, is expected to show a strong drop in the static regime, if measured at sufficiently small sample elongation $(\delta L/L < 10^{ -5}) $.

Charge-Density-Dependent Partitioning of Cs+and K+into Nickel Hexacyanoferrate Matrixes

Langmuir ◽  
2002 ◽  
Vol 18 (9) ◽  
pp. 3620-3625 ◽  
Author(s):  
Kavita M. Jeerage ◽  
William A. Steen ◽  
Daniel T. Schwartz
Keyword(s):  
Charge Density ◽  
Nickel Hexacyanoferrate ◽  
Density Dependent

scholarly journals Conspecific negative density dependence and why its study should not be abandoned

2020 ◽  
Author(s):  
Joseph A. LaManna ◽  
Scott A. Mangan ◽  
Jonathan A. Myers
Keyword(s):  
Density Dependence ◽  
Latitudinal Gradient ◽  
Null Model ◽  
Statistical Bias ◽  
Fitness Components ◽  
Density Dependent ◽  
Statistical Errors ◽  
Negative Density Dependence ◽  
Model Approach

AbstractRecent studies showing bias in the measurement of density dependence have the potential to sow confusion in the field of ecology. We provide clarity by elucidating key conceptual and statistical errors with the null-model approach used in Detto et al. (2019). We show that neither their null model nor a more biologically-appropriate null model reproduces differences in density-dependent recruitment between forests, indicating that the latitudinal gradient in negative density dependence is not an artefact of statistical bias. Finally, we suggest a path forward that combines observational comparisons of density dependence in multiple fitness components across localities with mechanistic and geographically-replicated experiments.

Anadromous Sturgeons: Habitats, Threats, and Management

2007 ◽  
Keyword(s):  
Density Dependence ◽  
Simulation Study ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Snake River ◽  
Spawning Habitat ◽  
Density Dependent ◽  
Hydrologic Conditions ◽  
Genetic Results ◽  
New Alleles

<em>Abstract.</em>— This paper describes a simulation study of reconnection options for white sturgeon <em>Acipenser transmontanus</em> subpopulations in adjacent river segments above and below CJ Strike Dam on the Snake River, Idaho, USA. In contrast to the downstream river segment, the upstream river segment is long and has areas that are suitable for spawning during normal and wet hydrologic conditions. We evaluated demographic and genetic consequences of upstream and downstream passage using different model assumptions about trashrack spacing and density-dependent effects on the spawning interval. Our genetic results predict that, although reconnection would introduce new alleles to the upstream subpopulation, it would also preserve alleles from the downstream subpopulation by propagating them in the larger subpopulation above the dam. Our demographic results predict that halving the space between trashracks would have large and unequivocal benefits, whereas the predicted effects of reconnection were smaller and more sensitive to model assumptions. Simulated upstream passage tended to benefit both subpopulations only in the absence of density-dependent limitation. In the presence of density dependence, the combination of halved trashrack spacing and upstream and downstream passage produced the best results. Narrower trashracks kept spawning adults in the upstream segment with spawning habitat, while allowing their progeny to migrate downstream. Screening appears to be the best option for such a species in this configuration of a long river segment acting as a demographic source above a short one acting as a demographic sink.

Density-Dependent Population Growth

2020 ◽  
pp. 29-46
Author(s):  
Michael J. Fogarty ◽  
Jeremy S. Collie
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Density Dependence ◽  
Multiple Equilibria ◽  
Dynamical Behavior ◽  
Logistic Growth ◽  
Density Dependent ◽  
Per Capita ◽  
Discrete Time Models ◽  
Complex Dynamical Behavior

The observation that no population can grow indefinitely and that most populations persist on ecological timescales implies that mechanisms of population regulation exist. Feedback mechanisms include competition for limited resources, cannibalism, and predation rates that vary with density. Density dependence occurs when per capita birth or death rates depend on population density. Density dependence is compensatory when the population growth rate decreases with population density and depensatory when it increases. The logistic model incorporates density dependence as a simple linear function. A population exhibiting logistic growth will reach a stable population size. Non-linear density-dependent terms can give rise to multiple equilibria. With discrete time models or time delays in density-dependent regulation, the approach to equilibrium may not be smooth—complex dynamical behavior is possible. Density-dependent feedback processes can compensate, up to a point, for natural and anthropogenic disturbances; beyond this point a population will collapse.

scholarly journals Territorial landscapes: incorporating density-dependence into wolf habitat selection studies

2019 ◽  
Vol 6 (11) ◽  
pp. 190282 ◽  
Author(s):  
Shawn T. O'Neil ◽  
Dean E. Beyer ◽  
Joseph K. Bump
Keyword(s):  
Habitat Selection ◽  
Density Dependence ◽  
Temporal Dynamics ◽  
Wildlife Habitat ◽  
Population Increase ◽  
Habitat Availability ◽  
Functional Responses ◽  
Model Framework ◽  
Selection Probability ◽  
Density Dependent

Habitat selection is a process that spans space, time and individual life histories. Ecological analyses of animal distributions and preferences are most accurate when they account for inherent dynamics of the habitat selection process. Strong territoriality can constrain perception of habitat availability by individual animals or groups attempting to colonize or establish new territory. Because habitat selection is a function of habitat availability, broad-scale changes in habitat availability or occupancy can drive density-dependent habitat functional responses. We investigated density-dependent habitat selection over a 19-year period of grey wolf ( Canis lupus ) recovery in Michigan, USA, using a generalized linear mixed model framework to develop a resource selection probability function (RSPF) with habitat coefficients conditioned on random effects for wolf packs and random year intercepts. In addition, we allowed habitat coefficients to vary as interactions with increasing wolf density over space and time. Results indicated that pack presence was driven by factors representing topography, human development, winter prey availability, forest structure, roads, streams and snow. Importantly, responses to many of these predictors were density-dependent. Spatio-temporal dynamics and population changes can cause considerable variation in wildlife–habitat relationships, possibly confounding interpretation of conventional habitat selection models. By incorporating territoriality into an RSPF analysis, we determined that wolves' habitat use in Michigan shifted over time, for example, exhibiting declining responses to winter prey indices and switching from positive to negative responses with respect to stream densities. We consider this an important example of a habitat functional response in wolves, driven by colonization, density-dependence and changes in occupancy during a time period of range expansion and population increase.

Stability and Hopf Bifurcation of a Delayed Density-Dependent Predator–Prey System with Beddington–DeAngelis Functional Response

2016 ◽  
Vol 26 (10) ◽  
pp. 1650165 ◽  
Author(s):  
Haiyin Li ◽  
Gang Meng ◽  
Zhikun She
Keyword(s):  
Hopf Bifurcation ◽  
Density Dependence ◽  
Functional Response ◽  
Positive Equilibrium ◽  
Stability Switches ◽  
Predator Prey ◽  
Geometric Criterion ◽  
Density Dependent ◽  
Prey System ◽  
The Stability

In this paper, we investigate the stability and Hopf bifurcation of a delayed density-dependent predator–prey system with Beddington–DeAngelis functional response, where not only the prey density dependence but also the predator density dependence are considered such that the studied predator–prey system conforms to the realistically biological environment. We start with the geometric criterion introduced by Beretta and Kuang [2002] and then investigate the stability of the positive equilibrium and the stability switches of the system with respect to the delay parameter [Formula: see text]. Especially, we generalize the geometric criterion in [Beretta & Kuang, 2002] by introducing the condition [Formula: see text] which can be assured by the condition [Formula: see text], and adopting the technique of lifting to define the function [Formula: see text] for alternatively determining stability switches at the zeroes of [Formula: see text]s. Afterwards, by the Poincaré normal form for Hopf bifurcation in [Kuznetsov, 1998] and the bifurcation formulae in [Hassard et al., 1981], we qualitatively analyze the properties for the occurring Hopf bifurcations of the system (3). Finally, an example with numerical simulations is given to illustrate the obtained results.

CHARGE DENSITY INFLUENCE ON MACROSCOPIC DEFORMATION ENERGY

2010 ◽  
Vol 19 (07) ◽  
pp. 1411-1423
Author(s):  
R. A. GHERGHESCU ◽  
D. N. POENARU ◽  
M. RAPORTARU ◽  
B. POPOVICI ◽  
W. GREINER
Keyword(s):  
Potential Energy ◽  
Charge Density ◽  
Density Dependence ◽  
Exponential Model ◽  
Deformation Energy ◽  
Proton Density ◽  
Macroscopic Deformation

A formula describing the proton density dependence on macroscopic deformation energy for different fusion-like shape configurations is derived. As a consequence, the influence of intermediary atomic numbers of fusioning nuclei on the macroscopic deformation-dependent terms of the potential energy in the Yukawa-plus-exponential model is studied. For the same target–projectile pair, at the same distance between their centers, macroscopic fusion barriers differ by energy amounts up to 5 MeV.

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