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Social interactions are a significant factor that influence the decision-making of species ranging from humans to bacteria. In the context of animal migration, social interactions may lead to improved decision-making, greater ability to respond to environmental cues, and the cultural transmission of optimal routes. Despite their significance, the precise nature of social interactions in migrating species remains largely unknown. Here we deploy unmanned aerial systems to collect aerial footage of caribou as they undertake their migration from Victoria Island to mainland Canada. Through a Bayesian analysis of trajectories we reveal the fine-scale interaction rules of migrating caribou and show they are attracted to one another and copy directional choices of neighbours, but do not interact through clearly defined metric or topological interaction ranges. By explicitly considering the role of social information on movement decisions we construct a map of near neighbour influence that quantifies the nature of information flow in these herds. These results will inform more realistic, mechanism-based models of migration in caribou and other social ungulates, leading to better predictions of spatial use patterns and responses to changing environmental conditions. Moreover, we anticipate that the protocol we developed here will be broadly applicable to study social behaviour in a wide range of migratory and non-migratory taxa. This article is part of the theme issue ‘Collective movement ecology’.

AimDespite the recent improvements made in species distribution models (SDMs), assessing species' ability to migrate fast enough to track their climate optimum remains a challenge. This study achieves this goal and demonstrates the reliability of a process‐based SDM to provide accurate projections by simulating the post‐glacial colonization of European beech.LocationEurope.MethodsWe simulated the post‐glacial colonization of European beech over the last 12,000 years by coupling a process‐based SDM (PHENOFIT) and a new migration model based on Gibbs point processes, both parameterized with modern ecological data. Simulations were compared with palaeoarchives and phylogeographic data on European beech.ResultsModel predictions are consistent with palaeoarchives and phylogeographic data over the Holocene. The results suggest that post‐glacial expansion of European beech was limited by climate on its north‐eastern leading edge, while limited by its migration abilities on its north‐western leading edge. The results show a mean migration rate of beech varying from 270 m yr −1 to 280 m yr−1 and a maximum migration rate varying from 560 m yr−1 to 630 m yr−1, when limited and not limited by climate, respectively. They also highlight the relative contribution of known and suspected glacial refugia in present beech distribution and confirm the results of phylogeographic studies.Main conclusionsFor the first time, we were able to reproduce accurately the colonization dynamics of European beech during the last 12 kyr using a process‐based SDM and a migration model, both parameterized with modern ecological data. Our methodology has allowed us to identify the different factors that affected European beech migration during its post‐glaciation expansion in different parts of its range. This method shows great potential to help palaeobotanists and phylogeographers locate putative glacial refugia, and to provide accurate projections of beech distribution change in the future.

In this study, the Laplace Adomian decomposition technique (LADT) is employed to analyse a numerical study with the SDIQR mathematical model of COVID-19 for infected migrants in Odisha. The analytical power series and LADT are applied to the Covid-19 model to estimate the solution profiles of the dynamical variables. We proposed a mathematical model that incorporates both the resistive class and the quarantine class of COVID-19. We also introduce a procedure to evaluate and control the infectious disease of COVID-19 through the SDIQR pandemic model. Five compartments like susceptible ( S ), diagnosed ( D ), infected ( I ), quarantined ( Q ) and recovered ( R ) population are found in our model. The model can only be solved approximately rather than analytically as it contains a system of nonlinear differential equations with reaction rates. To demonstrate and validate our model, the numerical simulations for infected migrants are plotted with suitable parameters.

Internal migration is one of the influential factors of urban growth. This phenomenon needs to be well understood for urban planning decision making, in order to avoid a shortfall or inefficiency in urban development. Consequently, by the multiple factors of migration decision-selectivity in terms of spatial-economic factors, spatial-social factors and personal factors make this phenomenon difficult to estimate. This paper utilises the capability of a GIS-based multi-criteria decision analysis (MCDA) approach in formulating a spatial migration model so-called migration potential model (MGP model) for modelling the distribution of potential migrants in urban areas. The model incorporates the migration decision-selectivity factors identified from a migration behavioural survey on households in the Klang Valley region into an environment of GIS-based MCDA. For this attempt, the land suitability model-based weighted linear combination so-called spatial AHP (Analytic Hierarchy Process) technique was selected as a base model for the MGP formulation. The paper concludes the integration of GIS with MCDA would contribute towards an advanced methodology of migration analysis for urban planning purposes.

Polyethylene terephthalate (PET) is one of the most widely used food contact materials due to its excellent mechanical properties and recyclability. Migration of substances from PET and assessment of compliance are usually determined by experimental testing, which can be challenging depending on the migrants of interest. Low concentrations and missing reference standards, among other factors, have led to inadequate investigation of the migration potential of PET oligomers. Migration modeling can overcome such limitations and is therefore a suitable starting point for exposure and risk assessment. In this study, the activation energy-based (EA) model and the AP model were used to systematically evaluate the migration potential of 52 PET oligomers for 12 different application scenarios. Modeling parameters and conditions were evaluated to investigate their impact and relevance on the assessment of realistic exposures. Obtained results were compared with safety thresholds known from the concept of toxicological thresholds of concern. This allowed the evaluation and identification of oligomers and/or applications where migration or exposure levels may be associated with a potential risk because they exceed these safety thresholds. Overall, this study demonstrated that migration modeling can be a high-throughput, fast, flexible, and suitable approach for comprehensive exposure assessment.

Cell migration is a complex, tightly regulated multistep process in which cytoskeletal reorganization and focal adhesion redistribution play a central role. Core to both individual and collective migration is the persistent random walk, which is characterized by random force generation and resistance to directional change. We first discuss a model that describes the stochastic movement of ECs and characterizes EC persistence in wound healing. To that end, we pharmacologically disrupted cytoskeletal dynamics, cytochalasin D for actin and nocodazole for tubulin, to understand its contributions to cell morphology, stiffness, and motility. As such, the use of Atomic Force Microscopy (AFM) enabled us to probe the topography and stiffness of ECs, while time lapse microscopy provided observations in wound healing models. Our results suggest that actin and tubulin dynamics contribute to EC shape, compressive moduli, and directional organization in collective migration. Insights from the model and time lapse experiment suggest that EC speed and persistence are directionally organized in wound healing. Pharmacological disruptions suggest that actin and tubulin dynamics play a role in collective migration. Current insights from both the model and experiment represent an important step in understanding the biomechanics of EC migration as a therapeutic target.

The aim of the paper is to present Bayesian forecasts of immigration for seven European countries to 2025, based on quantitative data and qualitative knowledge elicited from country-specific migration experts in a two-round Delphi survey. In line with earlier results, most of the immigration processes under study were found to be barely predictable in the long run, exhibiting non-stationary features. This outcome was obtained largely irrespectively of the expert knowledge input, which nevertheless was found useful in describing the predictive uncertainty, especially in the short term. It is argued that, under the non-stationarity of migration processes, too long forecasts horizons are inadequate, which is a serious challenge for population forecasts in general.

A methodology is developed to estimate comparable international migration flows between a set of countries. International migration flow data may be missing, reported by the sending country, reported by the receiving country or reported by both the sending and the receiving countries. For the last situation, reported counts rarely match owing to differences in definitions and data collection systems. We report counts harmonized by using correction factors estimated from a constrained optimization procedure. Factors are applied to scale data that are known to be of a reliable standard, creating an incomplete migration flow table of harmonized values. Cells for which no reliable reported flows exist are then estimated from a negative binomial regression model fitted by using an expectation-maximization (EM) type of algorithm. Covariate information for this model is drawn from international migration theory. Finally, measures of precision for all missing cell estimates are derived by using the supplemented EM algorithm. Recent data on international migration between countries in Europe are used to illustrate the methodology. The results represent a complete table of comparable flows which can be used by regional policy makers and social scientists to understand population behaviour and change better.

Bisphenol A (BPA) is a known substance that is found in food contact materials as an intentionally added as well as a non-intentionally added substance. Traces of BPA were found as a non-intentionally added substance in recycled PET (rPET). In 2023, the EFSA proposed a new TDI of 0.0002 µg/kg bw/d, which is lower than the previous (temporary) TDI of 4 µg/kg bw/d by a factor of 20,000. The TDI of 0.0002 µg/kg bw/d would translate for a default 60 kg person eating one kilogram of food into a migration limit of 0.012 µg/kg in the food. This very low migration limit is a challenge to measuring BPA levels in food. A solution is to use migration modeling to establish maximum concentrations in rPET for different food contact applications. Precise diffusion coefficients for BPA in PET were determined within this study by use of migration kinetics. In June 2024, the European Commission proposed a new migration threshold limit for BPA of 1 µg/kg, which should be understood as a detection limit. From the results of this study, it can be concluded that a BPA concentration in the PET bottle wall of 297 mg/kg (3% acetic acid), 255 mg/kg (10% ethanol), and 192 mg/kg (20% ethanol) after storage for 365 d at 25 °C is in compliance with the migration threshold limit of 1 µg/kg. These maximum concentrations are far above the measured BPA concentrations on rPET bottles in Europe between 2019 and 2023. Therefore, the new proposed migration threshold limit for BPA cannot be exceeded.

Flexible crystal(水晶) structures, which exhibit(展览) single-crystal(水晶)-to-single-crystal(水晶) (SCSC) transformations(转型), are attracting attention(注意) in many applied aspects: magnetic(磁) switches, catalysis, ferroelectrics and sorption. Acid treatment(治疗) for titanosilicate material(材料) AM-4 and natural(自然) compounds with the same structures led to SCSC transformation(转型) by loss(损失) Na+, Li+ and Zn2+ cations with large structural(结构) changes (20% of the unit(单位)-cell(细胞) volume(体积)). The conservation(保育) of crystallinity through complex(复杂) transformation(转型) is possible due(由于) to the formation(形成) of a strong hydrogen bonding(债券) system(系统). The mechanism(机制) of transformation(转型) has been characterized using single-crystal(水晶) X-ray(射线) diffraction analysis(分析), powder(粉) diffraction, Rietvield refinement, Raman spectroscopy and electron microscopy. The low migration(迁移) energy(能源) of cations in the considered materials(材料) is confirmed using bond(债券)-valence and density(密度) functional(功能) theory(理论) calculations, and the ion conductivity of the AM-4 family’s materials(材料) has been experimentally verified.