scholarly journals Behavioural movement strategies in cyclic models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Moura ◽  
J. Menezes
Keyword(s):  
Local Environment ◽  
Stochastic Simulations ◽  
Behavioural Strategy ◽  
Specific Direction ◽  
Directional Movement ◽  
Movement Strategies ◽  
Spatial Pattern Formation ◽  
Defence Strategy ◽  
Cyclic Models ◽  
Different Levels

AbstractThe spatial segregation of species is fundamental to ecosystem formation and stability. Behavioural strategies may determine where species are located and how their interactions change the local environment arrangement. In response to stimuli in the environment, individuals may move in a specific direction instead of walking randomly. This behaviour can be innate or learned from experience, and allow the individuals to conquer or the maintain territory, foraging or taking refuge. We study a generalisation of the spatial rock-paper-scissors model where individuals of one out of the species may perform directional movement tactics. Running a series of stochastic simulations, we investigate the effects of the behavioural tactics on the spatial pattern formation and the maintenance of the species diversity. We also explore a more realistic scenario, where not all individuals are conditioned to perform the behavioural strategy or have different levels of neighbourhood perception. Our outcomes show that self-preservation behaviour is more profitable in terms of territorial dominance, with the best result being achieved when all individuals are conditioned and have a long-range vicinity perception. On the other hand, invading is more advantageous if part of individuals is conditioned and if they have short-range neighbourhood perception. Finally, our findings reveal that the self-defence strategy is the least jeopardising to biodiversity which can help biologists to understand population dynamics in a setting where individuals may move strategically.

scholarly journals Behavioural Strategies in Cyclic Models: The Effects of Directional Movement Tactics

2020 ◽  
Author(s):  
Beatriz Moura ◽  
Josinaldo Menezes da Silva
Keyword(s):  
Population Growth ◽  
Conditioned Response ◽  
The Other ◽  
Stochastic Simulations ◽  
Spatial Density ◽  
Behavioural Strategy ◽  
Directional Movement ◽  
Cyclic Models ◽  
Different Levels ◽  
Behavioural Strategies

Abstract We investigate behavioural strategies in stochastic simulations of systems with cyclic nonhierarchical dominance, as ageneralisation of the rock-paper-scissors game. We introduce directional movement tactics to one out of the species, whose individuals move according to an innate or a conditioned response to a stimulus; individuals of the other species move randomly. The directional movement tactics allow the individuals to conquer or maintain territory, either attacking or anticipating or Safeguarding themselves. We study the effects of the behavioural strategies for individuals with different levels of perception of the neighbourhood. Besides, we investigate the case where not all individuals are conditioned to perform the behavioural strategy or where individuals that do not use the tactic for every move. We found that self-preservation behaviour is more profitable in terms of population growth, where the best result is achieved for individuals with large perception radius that always move according to the movement tactic. Our findings show that the attack tactics is more gainful for short perception radius and if the individuals alternate the tactic with random movement. For anticipation, the best result is achieved for individuals with long-range perception using the tactics rarely. Finally, we calculated the coexistence probability and found that, in addition to providing a greater spatial density for the species, the Safeguarding tactic is the least jeopardising to biodiversity. Our results may be useful for experimental and theoretical biologists to understand systems of species whose individuals behave strategically, and how coexistence is maintained in an uneven scenario.

scholarly journals Responses and Indicators of Composition, Diversity, and Productivity of Plant Communities at Different Levels of Disturbance in a Wetland Ecosystem

Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 252
Author(s):  
Tingting Duan ◽  
Jing Zhang ◽  
Zhengjun Wang
Keyword(s):  
Plant Community ◽  
Plant Communities ◽  
Leisure Activity ◽  
Local Environment ◽  
Diversity Indices ◽  
Soil Parameters ◽  
Grazing Tolerance ◽  
Organic Matter Concentration ◽  
Drought Tolerant ◽  
Different Levels

Grassland tourism is a very popular leisure activity in many parts of the world. However, the presence of people in these areas causes disturbance to the local environment and grassland resources. This study analyzes the composition, diversity, and productivity under different levels of disturbance of the plant communities in the Kangxi Grassland Tourist Area and the Yeyahu Wetland Nature Reserve of Beijing, China. It aims to identify indicators of plant communities and their responses to different levels of disturbance. Our analysis shows that the plant community density and coverage have a certain compensatory increase under disturbed conditions. With the increase in disturbances, more drought-tolerant species have appeared (increased by 5.7%), some of which have become the grazing-tolerance indicator species in the trampled grazed area (TGA). For plant community productivity, biomass and height are good indicators for distinguishing different disturbances (p < 0.05). In addition, several diversity indices reveal the change of plant communities from different perspectives (three of the four indices were significant at the p < 0.05 level). For soil parameters, soil water content and organic matter concentration help to indicate different disturbance levels (the former has a 64% change). Moreover, the standard deviation of the plant community and soil parameters is also a good indicator of their spatial variability and disturbance levels, especially for the TGA. Our analysis confirms that the indicators of productivity, diversity, and soil parameters can indicate the disturbance level in each subarea from different perspectives. However, under disturbed conditions, a comprehensive analysis of these indicators is needed before we can accurately understand the state of health of the plant community.

Development of a two-dimensional piezoelectric traveling-wave generator

2020 ◽  
pp. 1045389X2094394
Author(s):  
Yu-Min Lin ◽  
Yu-Hsiang Hsu ◽  
Wen-Chun Su ◽  
Yuan-Ting Kao ◽  
Chih-Kung Lee
Keyword(s):  
Traveling Waves ◽  
New Method ◽  
Two Dimensional ◽  
Resonant Frequencies ◽  
Specific Direction ◽  
Directional Movement ◽  
Bending Mode ◽  
Wave Generator ◽  
Bending Modes ◽  
Four Electrodes

In this article, we present a new method to control the direction of traveling waves in either an x-direction or y-direction on a two-dimensional square plate. The core structure was composed of a piezoelectric serial bimorph with four electrodes. Each electrode was spatially designed to activate one of the bending modes and which included the ability to reduce adjacent modes and minimize interference. Our new method differs from other reported methods in that the four electrodes were driven at designated resonant frequencies. In our wave generator, different driving amplitudes and phases were applied to induce the traveling waves to propagate in a specific direction. To design the directional movement and to better understand the pattern of induced traveling waves, an analytical solution was derived to assist in the design of the four driving electrodes. Using our newly developed analytical method, traveling waves can be controlled to travel in either the x-direction or y-direction using two different sets of electrodes, where each electrode can be driven at a specific but different bending mode. We found that both the voltage ratio and phase difference between the two driving electrodes are important factors for optimization.

scholarly journals Devil in the details: Mechanistic variations impact information transfer across models of transcriptional cascades

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245094
Author(s):  
Michael A. Rowland ◽  
Kevin R. Pilkiewicz ◽  
Michael L. Mayo
Keyword(s):  
Transcription Factor ◽  
Data Processing ◽  
Information Transfer ◽  
Internal State ◽  
Local Environment ◽  
Stochastic Simulations ◽  
Nonlinear Kinetics ◽  
Network Information ◽  
Transmitted Information ◽  
Protein Binding Kinetics

The transcriptional network determines a cell’s internal state by regulating protein expression in response to changes in the local environment. Due to the interconnected nature of this network, information encoded in the abundance of various proteins will often propagate across chains of noisy intermediate signaling events. The data-processing inequality (DPI) leads us to expect that this intracellular game of “telephone” should degrade this type of signal, with longer chains losing successively more information to noise. However, a previous modeling effort predicted that because the steps of these signaling cascades do not truly represent independent stages of data processing, the limits of the DPI could seemingly be surpassed, and the amount of transmitted information could actually increase with chain length. What that work did not examine was whether this regime of growing information transmission was attainable by a signaling system constrained by the mechanistic details of more complex protein-binding kinetics. Here we address this knowledge gap through the lens of information theory by examining a model that explicitly accounts for the binding of each transcription factor to DNA. We analyze this model by comparing stochastic simulations of the fully nonlinear kinetics to simulations constrained by the linear response approximations that displayed a regime of growing information. Our simulations show that even when molecular binding is considered, there remains a regime wherein the transmitted information can grow with cascade length, but ends after a critical number of links determined by the kinetic parameter values. This inflection point marks where correlations decay in response to an oversaturation of binding sites, screening informative transcription factor fluctuations from further propagation down the chain where they eventually become indistinguishable from the surrounding levels of noise.

Perceptual-motor performance in young people with visual impairment is related to visual acuity across different movement skills

2019 ◽  
Author(s):  
ALANNAH Mary SAVAGE ◽  
Peter Lock ◽  
Martin Walls ◽  
Matthew Rodger
Keyword(s):  
Young People ◽  
Visual Impairment ◽  
Motor Development ◽  
Visual Impairments ◽  
Visual Status ◽  
Movement Strategies ◽  
Perceptual Motor Performance ◽  
The Impact ◽  
Different Levels ◽  
Ball Skills

Vision is important for development of action and coordination, but the impact of visual impairments on perceptual-motor development is not well understood due to mixed findings and limited research. To compare the performance of young people (aged 5-18) with different levels of visual impairment (VI) at different perceptual-motor (ball) skills, in comparison to sighted young people either using vision or blindfolded. Participants performed different ball skills: interception; bounce and catch; throwing. They were grouped for comparison by visual status: Sighted; Sighted Blindfolded; VI with Negligible Acuity (1/60 or below); VI with Residual Acuity (above 1/60). Task performance and motion capture analysis showed that across the different tasks, the Sighted group and Residual Acuity group produced the highest levels of performance, the Sighted Blindfolded group slightly lower, while the Negligible Acuity group produced the lowest performance and also adopted different movement strategies to the other three groups. Perceptual-motor development appeared to be substantially impacted in participants with severe visual impairments, whereas those with more moderate visual impairments were able to perform within the range of young people with full vision. This implies a complex relationship between visual impairments and perceptual-motor development.

scholarly journals How fast are cells dividing: Probabilistic model of continuous labeling assays

2019 ◽  
Author(s):  
Julian Rode ◽  
Torsten Goerke ◽  
Lutz Brusch ◽  
Fabian Rost
Keyword(s):  
Cell Cycle ◽  
Probabilistic Model ◽  
Tissue Sample ◽  
Estimation Method ◽  
Proliferation Rate ◽  
Stochastic Simulations ◽  
Biological Variability ◽  
The Mean ◽  
Different Levels

AbstractCorrect estimates of cell proliferation rates are crucial for quantitative models of the development, maintenance and regeneration of tissues. Continuous labeling assays are used to infer proliferation rates in vivo. So far, the experimental and theoretical study of continuous labeling assays focused on the dynamics of the mean labeling-fraction but neglected stochastic effects. To study the dynamics of the labeling-fraction in detail and fully exploit the information hidden in fluctuations, we developed a probabilistic model of continuous labeling assays which incorporates biological variability at different levels, between cells within a tissue sample but also between multiple tissue samples. Using stochastic simulations, we find systematic shifts of the mean-labeling fraction due to variability in cell cycle lengths. Using simulated data as ground truth, we show that current inference methods can give biased proliferation rate estimates with an error of up to 40 %. We derive the analytical solution for the Likelihood of our probabilistic model. We use this solution to infer unbiased proliferation rate estimates in a parameter recovery study. Furthermore, we show that the biological variability on different levels can be disentangled from the fluctuations in the labeling data. We implemented our model and the unbiased parameter estimation method as an open source Python tool and provide an easy to use web service for cell cycle length estimation from continuous labeling assays (https://imc.zih.tu-dresden.de/cellcycle).

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Residual Gas Reaction in the Electron Microscope: II The Design of a Gas-Control Chamber for Quantitative Observations

1969 ◽  
Vol 27 ◽  
pp. 82-83
Author(s):  
Chester J. Calbick ◽  
Richard E. Hartman
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Local Environment ◽  
Chamber Pressure ◽  
Objective Lens ◽  
Ion Pump ◽  
Quantitative Studies ◽  
Precise Knowledge ◽  
Differential Pumping ◽  
And Control

Quantitative studies of the phenomenon associated with reactions induced by the electron beam between specimens and gases present in the electron microscope require precise knowledge and control of the local environment experienced by the portion of the specimen in the electron beam. Because of outgassing phenomena, the environment at the irradiated portion of the specimen is very different from that in any place where gas pressures and compositions can be measured. We have found that differential pumping of the specimen chamber by a 4" Orb-Ion pump, following roughing by a zeolite sorption pump, can produce a specimen-chamber pressure 100- to 1000-fold less than that in the region below the objective lens.

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

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