Bifurcation and Patterns Analysis for a Spatiotemporal Discrete Gierer-Meinhardt System

The Gierer-Meinhardt system is one of the prototypical pattern formation models. The bifurcation and pattern dynamics of a spatiotemporal discrete Gierer-Meinhardt system are investigated via the couple map lattice model (CML) method in this paper. The linear stability of the fixed points to such spatiotemporal discrete system is analyzed by stability theory. By using the bifurcation theory, the center manifold theory and the Turing instability theory, the Turing instability conditions in flip bifurcation and Neimark–Sacker bifurcation are considered, respectively. To illustrate the above theoretical results, numerical simulations are carried out, such as bifurcation diagram, maximum Lyapunov exponents, phase orbits, and pattern formations.

Spatial pattern dynamics of Cyclobalanopsis myrsinifolia in mixed broad-leaved forests on Tianmu Mountain, eastern China, 1996–2012

Studies of the spatial patterns of dominant plant species may provide significant insights into processes and mechanisms that maintain stand stability. This study was performed in a permanent 1 ha plot in evergreen and deciduous broad-leaved mixed forests on Tianmu Mountain. Based on two surveys (1996 and 2012), the dynamics of the spatial distribution pattern of the dominant population ( (Blume) Oersted) and the intra- and interspecific relationships between and other dominant species populations were analyzed using Ripley’s () function. We identified the importance value of a species in a community, which is the sum of the relative density, relative frequency, and relative dominance. The drivers of spatial distribution variation and the maintenance mechanisms of the forest were discussed. The results showed that the importance value of within the community decreased over the past 16 years. The population exhibited a significantly aggregated distribution within a spatial scale of 0–25 m in 1996 whereas it changed to a random distribution at scales larger than 5.5 m in 2012. From 1996 to 2012, the spatial distribution patterns between and (Batal.) Iljinsk. and between and (Lamb.) Hook did not change significantly. In 1996, and Miq. were positively associated at the scale of 0–25 m; this relationship was strongly significant at the scale of 6–10 m. However, there was no association between the populations of two species in terms of the spatial distribution at the scale of 0–25 m in 2012. Our findings indicate that the drivers of variation in the spatial distribution of the population were intra- and interspecific mutual relationships as well the seed-spreading mechanism of this species.Cyclobalanopsis myrsinifoliaC. myrsinifoliaKrC. myrsinifoliaC. myrsinifoliaC. myrsinifoliaCyclocarya paliurusC. myrsinifoliaCunninghamia lanceolataC. myrsinifoliaDaphniphyllum macropodumC. myrsinifolia

SATELLITE IMAGERY DRIVEN ASSESSMENT OF LAND USE LAND COVER, URBANIZATION AND SURFACE TEMPERATURE PATTERN DYNAMICS OVER TROPICAL MEGACITIES

In most of the developing nations, fast paced urbanisation is going on. This has changed the spatial patterns of Land Use Land Cover (LULC) and Land Surface Temperature (LST) over time. Continual studies are required in this context to know these phenomena more clearly. This study is carried out to analyse the spatio-temporal changes in LULC, urbanisation and LST in the metropolitan cities of India namely Delhi and Bengaluru. Landsat images of TM and OLI sensors are taken for the years 2001, 2010 and 2020. The LULC layer is obtained through supervised image classification. Concentric circles at the interval of 2 km are drawn from the centroid of the study areas which are used to compute Shannon's entropy through zonal analysis of the reclassified LULC layer. The thermal band of the Landsat is used for the computation of LST. The results of both the study areas revealed 1) decline in the open land, vegetation and water body; 2) rampant growth of built-up and urban area which become more compact over the years; and 3) spread of the higher LST zones.

Delay-Induced Self-Organization Dynamics in a Prey-Predator Network with Diffusion

Time delays can induce the loss of stability and degradation of performance. In this paper, the pattern dynamics of a prey-predator network with diffusion and delay are investigated, where the inhomogeneous distribution of species in space can be viewed as a random network, and delay can affect the stability of the network system. Our results show that time delay can induce the emergence of Hopf and Turing bifurcations, which are independent of the network, and the conditions of bifurcation are derived by linear stability analysis. Moreover, we find that the Turing pattern can be related to the network connection probability. The Turing instability region involving delay and network connection probability is obtained. Finally, the numerical simulation verifies our results.

Consequences of Agricultural Labour Scarcity on Cropping Pattern Dynamics in Tamil Nadu, India

Cropping Pattern is a complicated process that is influenced by a variety of socioeconomic, agro-climatic, and ecological factors. Even though India has the second-largest manpower in the world, all sectors of the economy have been affected by the scarcity of labour, the impact being felt more in the agricultural sector. The acute scarcity of agricultural labourers in the India has resulted in crop establishment delays, poor crop growth, no or late weeding, inappropriate fertilizer use, insufficient irrigation water, and other factors that have pushed Indian farmers to switching from farming to non-farm occupations. The present study was undertaken to analyze the dynamics of cropping patterns in the state, Tamil Nadu. Tiruchirappalli and Pudukkottai districts were selected purposively to represent the high and low crop diversity cropping system respectively. The study was based on both primary and secondary data for the period of 10 years from 2010-11 to 2019-20 to analyze the decadal change. Tabular Analysis, Compound Growth Rate and Markov chain analysis were used to analyze the data. The study results revealed that there are marginal changes in cropping pattern, increases towards the commercial crops such as sugarcane, tapioca, cotton and banana. The total fallow land share has increased continuously leaving a lesser area for cropping. The reported dynamics change the agricultural productivity and increased mechanization, which might be due to growth in the labour scarcity. The results showed that farmers were shifting from high labour intensive crops such as paddy, sugarcane, cotton to low labor-intensive crops such as groundnut, black gram over the years. Due to the higher requirement of laborers for cultivating crops, crop retention probability was lesser which means the crops have become less and less stable. It is therefore recommended that the district, state, and country's agricultural extension systems must be geared up to curbing the shifting farmers away from traditional farming practices and educate them on the use of available labor-saving equipment and technology.

Accumulation of Tetrahymena pyriformis on Interfaces

The behavior of ciliates has been studied for many years through environmental biology and the ethology of microorganisms, and recent hydrodynamic studies of microswimmers have greatly advanced our understanding of the behavioral dynamics at the single-cell level. However, the association between single-cell dynamics captured by microscopic observation and pattern dynamics obtained by macroscopic observation is not always obvious. Hence, to bridge the gap between the two, there is a need for experimental results on swarming dynamics at the mesoscopic scale. In this study, we investigated the spatial population dynamics of the ciliate, Tetrahymena pyriformis, based on quantitative data analysis. We combined the image processing of 3D micrographs and machine learning to obtain the positional data of individual cells of T. pyriformis and examined their statistical properties based on spatio-temporal data. According to the 3D spatial distribution of cells and their temporal evolution, cells accumulated both on the solid wall at the bottom surface and underneath the air–liquid interface at the top. Furthermore, we quantitatively clarified the difference in accumulation levels between the bulk and the interface by creating a simple behavioral model that incorporated quantitative accumulation coefficients in its solution. The accumulation coefficients can be compared under different conditions and between different species.

Differences in Dynamics of Lung Computed Tomography Patterns between Survivors and Deceased Adult Patients with COVID-19

This study’s aim was to investigate CT (computed tomography) pattern dynamics differences within surviving and deceased adult patients with COVID-19, revealing new prognostic factors and reproducing already known data with our patients’ cohort: 635 hospitalized patients (55.3% of them were men, 44.7%—women), of which 87.3% had a positive result of RT-PCR (reverse transcription-polymerase chain reaction) at admission. The number of deaths was 53 people (69.8% of them were men and 30.2% were women). In total, more than 1500 CT examinations were performed on patients, using a GE Optima CT 660 computed tomography (General Electric Healthcare, USA). The study was performed at hospital admission, the frequency of repetitive scans further varied based on clinical need. The interpretation of the imaging data was carried out by 11 radiologists with filling in individual registration cards that take into account the scale of the lesion, the location, contours, and shape of the foci, the dominating types of changes, as well as the presence of additional findings and the dynamics of the process—a total of 45 parameters. Statistical analysis was performed using the software packages SPSS Statistics version 23.0 (IBM, Armonk, NY, USA) and R software version 3.3.2. For comparisons in pattern dynamics across hospitalization we used repeated measures general linear model with outcome and disease phase as factors. The crazy paving pattern, which is more common and has a greater contribution to the overall CT picture in different phases of the disease in deceased patients, has isolated prognostic significance and is probably a reflection of faster dynamics of the process with a long phase of progression of pulmonary parenchyma damage with an identical trend of changes in the scale of the lesion (as recovered) in this group of patients. Already known data on typical pulmonological CT manifestations of infection, frequency of occurrence, and the prognostic significance of the scale of the lesion were reproduced, new differences in the dynamics of the process between recovered and deceased adult patients were also found that may have prognostic significance and can be reflected in clinical practice.

Chemophoresis Engine: Universal Principle of ATPase-driven Cargo Transport

Cell polarity regulates the orientation of the cytoskeleton members that directs intracellular transport for cargo-like organelles, using chemical gradients sustained by ATP or GTP hydrolysis. However, how cargo transports are directly mediated by chemical gradients remains unknown. We previously proposed a physical mechanism that enables directed movement of cargos, referred to as chemophoresis. According to the mechanism, a cargo with reaction sites is subjected to a chemophoresis force in the direction of the increased concentration. Based on this, we introduce an extended model, the chemophoresis engine, as a general mechanism of cargo motion, which transforms chemical free energy into directed motion through the catalytic ATP hydrolysis. We applied the engine to plasmid motion in a parABS system to demonstrate the the self-organization system for directed plasmid movement and pattern dynamics of ParA-ATP concentration, thereby explaining plasmid equi-positioning and pole-to-pole oscillation observed in bacterial cells and in vitro experiments. We mathematically show the existence and stability of the plasmid-surfing pattern, which allows the cargo-directed motion through the symmetry-breaking transition of the ParA- ATP spatiotemporal pattern. Finally, based on its generality, we discuss the chemophoresis engine as a universal principle of hydrolysis-driven intracellular transport.

The use of traffic data from automatic monitoring systems to obtain day-to-day time series of vehicle traffic volumes and origin-destination flows in urban networks

The understanding of travel pattern dynamics in the urban environment is essential for the transportation systems planning and operation. Recently, the increasing availability of massive traffic data from traffic monitoring systems, including automatic number plate recognition systems (TMS-ANPR), can allow an understanding of the day-to-day variability of traffic flows in large urban network systems. However, to enhance the data quality for analysis, it is essential to carry out a previous data treatment. This work presents a method for treatment of TMS-ANPR data. The main product of this data treatment are the day-to-day time series of traffic volumes and OD flows for different periods of a typical day, allowing the analysis of the multiday dynamic of travel behavior and of the model assumptions stated in the literature about such dynamic behavior. The proposed method, which can be applied to any type of TMS-ANPR, was applied to generate time series data from the TMS-ANPR of Fortaleza city, contributing to identify suspicious and atypical data, to define representative patterns of vehicular traffic and to estimate series of OD flows.

Pattern Dynamics of Vegetation Growth With Saturated Water Absorption

Regular pattern is a typical feature of vegetation distribution and thus it is important to study the law of vegetation evolution in the fields of desertification and environment conservation. The saturated water absorption effect between the soil water and vegetation plays an crucial role in the vegetation patterns in semi-arid regions, yet its influence on vegetation dynamics is largely ignored. In this paper, we pose a vegetation-water model with saturated water absorption effect of vegetation. Our results show that the parameter 1/P, which is conversion coefficient of water absorption, has a great impact on pattern formation of vegetation: with the increase of P, the density of vegetation decrease, and meanwhile it can induce the transition of different patterns structures. In addition, we find that the increase of appropriate precipitation can postpone the time on the phase transition of the vegetation pattern. The obtained results systematically reveal the effect of saturated water absorption on vegetation systems which well enrich the findings in vegetation dynamics and thus may provide some new insights for vegetation protection.