Individual Migration Research Articles

Mycobacteria Treatment Inhibits Bladder Cancer Cell Migration, Invasion, and Anchorage-Independent Growth

Bladder cancer (BC) is a highly recurrent and invasive malignancy, with Mycobacterium bovis BCG serving as the primary immunotherapy, particularly for non-muscle-invasive bladder cancer (NMIBC). However, the mechanisms underlying BCG’s antitumor effects and the potential of non-tuberculous mycobacteria like Mycobacterium brumae remain unclear. This study investigates the antitumor effects of M. bovis BCG and M. brumae on BC cell migration, invasion, and anchorage-independent growth. BC cell lines representing different stages of tumor differentiation were treated with either M. bovis BCG or M. brumae. Cell migration was assessed through wound healing and transwell assays, invasiveness by transwell invasion assays, MMP-9 production by gelatin zymography, and anchorage-independent growth via soft agar colony formation. Both mycobacteria inhibited individual cell migration across all BC lines, while collective migration was only reduced in intermediate-grade cells. Both treatments also reduced invasiveness, associated with decreased MMP-9 production. Furthermore, M. brumae inhibited anchorage-independent growth across all BC lines, while M. bovis BCG had a more selective effect, primarily inhibiting growth in high-grade cells. In conclusion, both mycobacteria reduce migration, invasion, and anchorage-independent growth of BC cells, with their effectiveness varying by species and tumor differentiation grade.

Payoff-driven migration promotes the evolution of trust in networked populations

Establishing and maintaining trustworthy behaviors in large populations of self-interested individuals is a significant problem which received extensive attentions from research fields such as evolutionary biology, economics, sociology and engineering. As a well-known model that captures social trust dilemmas, the N-player trust game is adopted to investigate the evolution of trust in groups consisting of investors and trustees. In addition, to model real scenarios in dynamic environments, we introduce a novel migration mechanism, called adaptive environment-benefit-driven migration, which considers the influence of individuals’ payoffs on migration. Through theoretical analysis and Monte Carlo simulations, we demonstrate the effectiveness of the migration mechanism on facilitating trust behaviors in the framework of evolutionary game theory. We find that the population density plays a crucial role in establishing trust. Simulation results reveal that trust can be fostered in a dynamic environment influenced by individual migration with the medium vacancy rate. This work significantly contributes to the understanding of mutual trust behaviors in networked social systems from a more realistic perspective.

The Role of Family Networks in Holocaust Rescue, 1933–1941: The Case of Australia

The article analyses the role family networks in Australia played in Holocaust rescue before and shortly after the outbreak of World War 2. Working with sources from the official archives as well as private documents, I argue that the networks enabled hundreds of Jewish migrants and refugees to escape Europe. Furthermore, they facilitated the arrival of migrants, who otherwise would most likely have been rejected as unsuitable applicants by the Australian government. First, the article analyses the Australian immigration laws before 1941, focusing predominantly on the sponsorship pathway, which allowed Australian residents to apply for the admission of their relatives and friends. In the following parts, the article uses case studies of individual migrants and their families to demonstrate the possibilities but also limitations of the sponsorship program. It concludes that despite the limitations, family networks need to be recognised for their contribution to Holocaust rescue, and this applies also to the case study of Australia, which otherwise was for a long time not considered an ideal destination by Jewish refugees.

Entrepreneurial well-being of expatriate entrepreneurs: self and world

PurposeThis paper explores the Entrepreneurial Well-Being (EWB) of expatriate entrepreneurs in China. Through the analysis of their contextualised lived experience across the entrepreneurial journey, the paper proposes a novel theorisation of EWB.Design/methodology/approachThis study adopts an interpretivist approach of abductive reasoning to analyse the data from 50 in-depth interviews conducted with expatriate entrepreneurs in China. Expatriate entrepreneurs are confronted with enhanced challenges in their host country, leading to particular emotional engagement with the entrepreneurial journey.FindingsFindings show the importance of life situations, emotions and relatedness in the entrepreneurial process and the EWB of expatriate entrepreneurs. Theorising from their lived experiences, the paper presents EWB as a dynamic process. It further theorises this process as a constant, ongoing interaction and integration between the self and world, in an interplay of being and becoming. Such theorisation contributes first to advancements in the EWB literature, with a stronger emphasis on the entrepreneurial aspect. The paper also contributes to discussions on contextualised entrepreneurship by stressing the role of emotions and relatedness in the pursuit of EWB.Originality/valueEntrepreneurship is a global phenomenon, which is often presented as a suitable alternative career path for migrant and expatriate individuals. However, the importance of EWB for entrepreneurs requires further attention from policy-makers, support institutions and entrepreneurs themselves. By theorising EWB as a processual journey of being and becoming and the relation between the self and world, this paper opens avenues for innovative support policies and practices aiming at developing the full potential of individuals in entrepreneurship and promoting both the happiness index and the global index of society.

Extreme-value modelling of migratory bird arrival dates: Insights from citizen science data

Abstract Citizen science mobilises many observers and gathers huge datasets but often without strict sampling protocols, resulting in observation biases due to heterogeneous sampling effort, which can lead to biased predictions. We develop a spatiotemporal Bayesian hierarchical model for bias-corrected estimation of arrival dates of the first migratory bird individuals at their breeding sites. Higher sampling effort could be correlated with earlier observed dates. We implement data fusion of two citizen-science datasets with fundamentally different protocols (BBS, eBird) and obtain posterior distributions of the latent process, which contains four spatial components endowed with Gaussian process priors: species niche; sampling effort; position and scale parameters of annual first arrival date. The data layer consists of four response variables: counts of observed eBird locations (Poisson); presence-absence at observed eBird locations (Binomial); BBS occurrence counts (Poisson); first arrival dates (Generalised Extreme-Value). We devise a Markov Chain Monte Carlo scheme and check by simulation that the latent process components are identifiable. We apply our model to several migratory bird species in the northeastern United States for 2001−2021 and find that the sampling effort significantly modulates the observed first arrival dates. We exploit this relationship to effectively bias-correct predictions of the true first arrivals.

Partial migration pays off in black-faced cormorants: insights from post-breeding GPS tracking

Seasonal variation in food availability or adverse weather patterns can create challenging conditions for year-round survival. Birds experiencing such fluctuations may migrate to locations with better food availability in the non-breeding period. While some species are obligate migrants, others are facultative migrants where various post-breeding strategies exist within populations. Several cormorant and shag species are facultative migrants with a range of post-breeding movement strategies within populations. Currently, most of the information available on cormorant post-breeding strategies originates from banding studies and little is known about their movements, time budget or habitat use during the non-breeding period. In the present study, Australian endemic black-faced cormorants (Phalacrocorax fuscescens), breeding on Notch Island, Victoria, were tracked with GPS data loggers during the non-breeding period. Different post-breeding strategies were observed. Individuals were either resident (N = 36, 69%), remaining within a short distance of the colony (16.7 ± 2.2 km) or migratory (N = 16, 31%), travelling greater distances (250.7 ± 24.4 km) to establish a new central place foraging location. Data from individuals which covered the entire non-breeding period indicated that, across strategies, individual birds had one area of residency during the non-breeding period. Migratory individuals were found to have lower daily activity levels, spending less time flying and foraging, than resident individuals during the early non-breeding period, possibly indicating that they had access to greater prey resources. Regardless of the post-breeding strategy, individuals utilised foraging locations that were of similar seabed depths year-round suggesting individual specialisation in prey resources or foraging habitats.

A Multi-Scale Species Distribution Model for Migrating and Overwintering Western Monarch Butterflies: Climate Is the Best Predictor

Western Monarch butterflies (Danaus plexippus) migrate from inland breeding ranges to coastal overwintering grounds in California. Given that migratory individuals may make multi-scale habitat selection decisions, we considered a multi-scale species distribution model (SDM) using range-wide climatic and local landscape-level predictors of migratory and overwintering habitat and community-science presence data. The range-wide model output was included as a predictor in the local-scale model, generating multi-scale habitat suitability. The top range-wide predictor was the minimum temperature in December, contributing 83.7% to the model, and was positively associated with presence. At the local scale, the strongest predictors of presence were the range-wide output and percent coverage of low and medium levels of development, contributing > 95%, with 61–63% from the range-wide output, with local-scale suitability coinciding with the California coastal zones. Development’s positive association with overwintering monarch presence was counterintuitive. It is likely that our local-scale model is overfit to these development zones, but it is unclear whether this overfitting resulted from modeler choices, monarchs overwintering close to human development, biased detection near human development, or a combination of these factors. Therefore, alternative approaches to collecting local-scale attribute data are suggested while recognizing the primacy of climate in restricting overwinter sites.

The Alarming Exodus of Nigerian Professionals: The Devastating Consequences of Human Capital Flight and Migration on Nigeria's Economic Development

Purpose: This study rigorously investigates the phenomenon of human capital flight and migration in Nigeria, emphasizing the alarming exodus of skilled professionals and its profound implications for the nation's economic development. By contextualizing brain drain within the broader landscape of labour mobility, this work seeks to elucidate the factors driving the migration of educated individuals, particularly in critical sectors such as healthcare, education, and technology. Materials and Methods: Utilizing a mixed-methods approach, this research synthesizes qualitative data from academic literature, policy documents, and empirical studies, alongside quantitative analysis drawn from migration statistics and socioeconomic metrics. This robust methodological framework supports a comprehensive exploration of the interplay between migration, brain drain, and national development, facilitating a deeper understanding of the ramifications of skilled labour loss. Findings: The findings indicate that Nigeria's alarming exodus of professionals is intricately linked to a confluence of factors, including systemic corruption, deteriorating infrastructure, and limited employment prospects. This human capital flight significantly undermines the quality and accessibility of essential services in critical sectors, leading to substantial socio-economic disparities. Consequently, the loss of skilled labour constrains Nigeria's competitive edge and stunts its economic resilience and growth potential. Implications to Theory, Practice and Policy: This inquiry extends beyond descriptive analysis to propose a nuanced framework for understanding the theoretical implications of human capital flight and migration in developing economies. It underscores the urgent need for policymakers to undertake comprehensive strategies that address the root causes of this phenomenon, fostering a conducive environment that retains talent while enhancing human capital investment and innovation capacity.

Contested categories in the context of international migration: introduction to the special issue

ABSTRACT In this introduction to the special issue Contested Categories in the Context of International Migration, we argue for the importance of critically engaging with state-created categories and classification systems. We advocate doing so in the particularly convoluted context of international migration, where states use categories to manage migrants’ entry, reception, and residence, making categorisation extremely consequential for individual migrants, even though bureaucratic documentation and everyday understandings of categories often differ greatly between migrants’ home countries and receiving states. We outline some of the scholarship on categorisation that has inspired our thinking, discuss why migration is such an important and generative site for examining categories and processes of categorisation, and finally consider how the contributions in this special issue attest to this.

Men (but not women) prefer to live in economically equal societies when it comes to mating: A five-study investigation

It is generally believed that people prefer societies with economic equality. No studies thus far have systematically examined sex differences in this preference specifically concerning mating—an important life stage. Building upon theoretical frameworks of mating strategies (i.e., hypergyny), we hypothesized that men, in comparison to women, are less inclined to prefer and reside in a highly unequal society when it comes to mating. This could be because economically unequal environments lead men to expect poorer life quality after marriage than women. These hypotheses were confirmed across five studies using a mixed-method approach. In particular, we first provided evidence by focusing on fertile age populations and employing the panel data across 50 states of the USA from 2006 to 2019 (Study 1A), the most recent cross-sectional data at the county level of the USA (Study 1B), and a large-scale survey data on the individual migration records of American residents (N = 4,746,718, Study 2). In addition, we conducted two controlled experiments by manipulating mating motivation (Study 3) and economic inequality level (high versus low, Studies 3 and 4, N = 812, N = 418). Our studies, employing both archival data high in ecological validity and experimental evidence allowing causal inferences, show that men exhibit a stronger aversion than women toward economic inequality. Our findings contribute to a deeper understanding of how evolutionary mating strategies and sex differences jointly influence the economic inequality preference.

Introduction: Exile and Innovation☆

AbstractThe early modern period was an age marked by the forced migration and displacement of social groups and individuals around the world. Huguenots, conversos, Catholics, cavaliers, Jacobites, and French emigrés alike fled or were expelled from their homes and communities. Yet, exile is still usually considered only within the context of broader religious or political events by scholars working in sub‐fields rather than as a phenomenon worthy of study in its own right. Foregrounding displacement as a major facet of early modern society and culture, this special issue explores the experience, perception, and poetics of exile from 1500 to 1800 through the prism of innovation. It encompasses displaced individuals and communities, as well as writings that treat the theme of exile, to consider how forced migration shaped the social, cultural, political, and intellectual contours of the era – and thus led to innovative practices and ideas.

Using Genetic Data to Determine Origin for Out-Migrating Smolt and Returning Adult Steelhead Trout (Oncorhynchus mykiss) in a Southeast Alaska Drainage.

Oncorhynchus mykiss is a partially migratory salmonid species, and many migratory populations (known as steelhead) have declined in recent decades in the western United States and Canada. Closely related resident populations (known as rainbow trout) may be an effective resource in the recovery of these declining migratory populations. However, the extent to which different populations of resident rainbow trout produce migratory individuals and how likely these individuals are to return as adults to spawn remains unknown. One limitation to answering these questions is the identification of loci that accurately segregate between migratory and resident populations. To address this limitation, we used existing genomic data from a well-studied population of O. mykiss from Southeastern Alaska (Sashin Creek) to identify loci that segregate between phenotypes. We then utilized Double Mismatch Allele-Specific qPCR (DMAS-qPCR) to genotype 233 smolts out-migrating from Sashin Creek and 99 returning adult steelhead trout across a five-year period to determine (a) the origin of out-migrating smolts and returning adults and (b) to quantify the extent to which the resident population contributes to the migratory population. Our results show that 37.3% of out-migrating smolts were produced from resident parents, whereas 19.3% of returning adults had resident parents. Ultimately, these results demonstrate that resident populations of rainbow trout produce migrant offspring that successfully complete their migration and return to spawn, increasing population sizes and likely improving genetic diversity. Therefore, conservation efforts should consider landlocked resident populations for producing smolts when developing recovery plans for migratory steelhead populations.

SPATIAL ANALYSIS BETWEEN YOUTH AND ADULT EDUCATION AND LABOR MARKET REMUNERATION

This study analyzes the spatial distribution of migration from traditional high school to Youth and Adult Education (YAE) and its relationship with formal work remuneration. For this, the Exploratory Spatial Data Analysis (ESDA) technique was used through global and local analyses. The results of the global analysis indicate a negative spatial autocorrelation between migration from regular secondary education to YAE and formal work remuneration. The local analysis indicated that the Northeast had the highest proportion of municipalities in the cluster with high migration of individuals in the YAE and higher remuneration in the formal market, while the South region had the highest concentration of municipalities with a low proportion of municipalities in the cluster with low migration of individuals in the YAE and high remuneration in the formal job market. Therefore, it is concluded that the low quality of YAE teaching leads individuals to enter the formal job market with a lower pay.

Notch-1 regulates collective breast cancer cell migration by controlling intercellular junction and cytoskeletal organization.

Pathological observations show that cancer cells frequently invade the surrounding normal tissue in collective rather than individual cell migration. However, general principles governing collective cell migration remain to be discovered. Different from individual cell migration, we demonstrated that the Notch-1-activation reduced collective cells speed and distances. In particular, Notch-1-activation induced cellular cytoskeletal remodelling, strengthened the intercellular junctions and cell-matrix adhesions. Mechanistically, Notch-1 activation prevented the phosphorylation of GSK-3β and the translocation of cytoplasmic free β-catenin to the nucleus, which increased E-cadherin expression and tight intercellular junctions. Moreover, Notch-1 signalling also activated the RhoA/ROCK pathway, promoting reorganization of F-actin and contractile forces produced by myosin. Further, Notch-1 activation increased cell adhesion to the extracellular substrate, which inhibited collective cell migration. These findings highlight that cell adhesions and cell-cell junctions contribute to collective cell migration and provide new insights into mechanisms of the modulation of Notch-1 signalling pathway on cancer cell malignancy.

Photoconvertible markers for study individual myoblast migration into the macrophage's colony

The success of myoblasts transplantation for regeneration in ischemic heart disease is largely determined by their interactions with resident macrophages. Studying their complex, contradictory, and poorly understood interactions requires the development of effective and reliable approaches for labeling and tracking myoblasts. Here, we present a useful approach for studying myoblast migration into macrophage colonies using cell-internalizable thermally treated polyelectrolyte microcapsules containing Rhodamine B (average size is approximately 3.2 ± 0.8 μm). The presented capsules exhibited fluorescence photoconversion properties, allowing for individual fluorescence coding of myoblast cells based on the number of converted and unconverted microcapsules when several capsules were internalized simultaneously. More than 70 % of C2C12 cells internalized the capsules (74 % of which contained more than two). The metabolic activity did not decrease to below 80 %, and proliferation and mobility did not change significantly. The initial cell density during the incubation with the capsules had a significant effect on the uptake efficiency. We tracked the migration of individually labeled myoblasts and their daughter cells into a macrophage colony (Raw 264.7) over 96 h. The marked cells purposefully moved with other myoblasts towards the macrophage colony, while the macrophages did not shorten the distance, despite their ability to migrate. This proposed approach may provide valuable insights for future research into the role and interaction of macrophages and myoblasts in cardiac muscle repair and regeneration.

Behavioral adaptation to seasonal resource scarcity by Caribou (Rangifer tarandus) and its role in partial migration

Abstract Animals living in seasonal environments have adopted a wide array of tactics used to deal with seasonal resource scarcity. Many species migrate between habitats to reach areas where food resources are more plentiful as an attempt to address energetic demands through foraging. We assessed the winter behavioral adaptations of Caribou (Rangifer tarandus), a large ungulate inhabiting Arctic and sub-Arctic regions known for seasonal resource scarcity. Movement rates of Caribou are the lowest of the year during winter, revealing 1 mechanism individuals use to reduce energy expenditures. However, migratory individuals moved nearly twice as much as nonmigratory individuals during winter, suggesting that migratory individuals rely more upon income (forage), whereas nonmigratory individuals rely more upon capital (bodily reserves). Lichens are the primary winter forage for large, migratory herds of Caribou, and migratory individuals experienced more than 2.5 times greater lichen cover than nonmigratory individuals. We documented that both groups slowed their movement in areas of greater lichen cover, suggesting increased foraging time in these areas. Movement rates were greater near villages, which may be suggestive of disturbance, but the effect was weak. Overall energy saved by reduced movement rates was modest. However, energy savings were 11% of daily body energy lost or 47% of the demands of early pregnancy, which potentially could affect individual condition and/or fetal growth if not offset by increases in forage intake.

Exploring Gendered Identity Crisis in Diasporic Space In the Works of Jhumpa Lahiri and Bharati Mukherjee

Research on diasporic and female studies is a significant and intriguing focus within contemporary literary studies. Diasporic literature has its origins in the migration of less privileged individuals to new and promising lands such as America, Britain, Canada, Trinidad, and others. Migration is often seen in countries with a colonial past. The newly independent individuals moved to foreign countries to escape poverty and seek a brighter future. The new lands were a fertile ground for material success, but they also had a negative impact on the mental well-being of these immigrants. The newcomers found a pre-existing culture, traditions, and rules in the new lands. The recently relocated individuals discovered themselves in a dilemma between their familiar history, the unfamiliar current situation, and the uncertain days ahead. Their minds became permanently ensnared in the complex network of historical and geographical factors.

Individual timing consistency across long-distance songbird migrations.

Migration timing in long-distance migratory birds plays an essential role in individual survival and fitness and is thought to be driven by circannual routines cued by photoperiod with some plasticity to environmental conditions. We examined the individual order of migration timing in purple martins (Progne subis), a neotropical migratory songbird that travels between breeding sites throughout eastern North America and nonbreeding sites in Brazil. Migration timing data were collected for 295 different individual purple martins over 9 years using light-level geolocators deployed at breeding sites across the range. We used linear mixed-effect models to examine the influence of the rank order of individual departure dates in one season on the rank order of four subsequent migration events while controlling for the effects of breeding latitude, sex, and age. Overall, we found evidence for consistent individual timing that can extend across 8 months and 12,000-24,000 km of migration. Individual rank order of migration timing in purple martins was generally conserved across migrations with consistent timings between fall departure dates from, and spring arrival dates to the breeding site the following year (0.28 ± 0.03, 95% CI 0.22-0.34), as well as at a finer scale across fall migration (0.33 ± 0.05, 95% CI 0.23-0.43), over the stationary nonbreeding period (0.39 ± 0.04, 95% CI 0.31-0.47), and across spring migration (0.03 ± 0.001, 95% CI 0.028-0.032). These results demonstrate that purple martins exhibit consistency in individual migration timing throughout the annual cycle that is likely driven by inherent individual circannual schedules. We additionally found that migration distance played a significant role, as the consistency of individual timing lessened over longer distances. Understanding how individual birds time migrations and if individuals are consistent between events can provide insight into how birds respond to shifts in their environment with climate change.

Analysis of 4G/LTE Network Performance in North-Central Nigeria: A Comprehensive Drive Test Approach

The proliferation of mobile devices and escalating demand for data services have resulted in a substantial increase in data traffic across Nigeria, especially in the North Central region due to heavy migration of individuals and organizations towards Abuja, the federal capital. However, despite the growing adoption of 4G/LTE networks in North Central Nigeria, users encounter persistent challenges in accessing high-speed internet and poor service network. This study investigates the performance of 4G/LTE networks in North-Central Nigeria using a comprehensive drive test methodology carried out in Abuja, Lafia and Makurdi. It covered a duration of 3hrs (12.00noon to 15.00pm) for 3days (3rd - 6th January, 2024). For each test day, drive tests covered a period of data measurements divided into 3,600 time-steps, with each time-step sized at 1sec; and scaled to 1:150 units. Key metrics including network speed, latency, uptime, coverage, and signal power were evaluated across major Mobile Network Operators. Result shows that D-NGN has the highest mean speed (9.543Mbps), packet loss (2.007%), uplink percentage (97.714%), and Network coverage (87.514%). It has the least latency (25.921) but high packet loss (2.007%). However, C-NGN shows lowest mean speed (6.638Mbps), uplink percentage (38.706%) and Signal power (-78.057dBm) but lowest mean packet loss (0.121%). A-NGN has the highest mean signal power (-61.867dBm) while B-NGN has highest latency (44.070ms) and lowest Network coverage (60.731%). This reveals that D-NGN has dominance in network performance, outperforming A-NGN, B-NGN, and C-NGN. It is recommended that MNOs in North-Central Nigeria should strategically enhance their network infrastructure to improve service delivery, particularly in suburban and rural areas where performance lags. D-NGN, the frontrunner in network speed and coverage, could further solidify its market leadership by addressing identified latency and packet loss issues especially in Makurdi. Moreover, MNOs with lower performance metrics could invest in expanding coverage and optimizing network configurations to meet user demands, thereby increasing competitiveness and customer satisfaction across the region.

Migratory-derived resources induce elongated food chains through middle-up food web effects

BackgroundSeasonal movements of animals often result in the transfer of large amounts of energy and nutrients across ecosystem boundaries, which may have large consequences on local food webs through various pathways. While this is known for both terrestrial- and aquatic organisms, quantitative estimates on its effects on food web structure and identification of key pathways are scarce, due to the difficulty in obtaining replication on ecosystem level with negative control, i.e. comparable systems without migration.MethodsIn this study, we estimate the impact of Arctic charr (Salvelinus alpinus) migration on riverine ecosystem structure, by comparing multiple streams with strictly resident populations above natural migration barriers with streams below those barriers harboring partially migratory populations. We compared density estimates and size structure between above and below populations. Diet differences were examined through the analysis of stomach contents, changes in trophic position were examined by using stable isotopes. To infer growth rate of resident individuals, back-growth calculation was performed using otoliths.ResultsWe find higher densities of small juveniles in partially migratory populations, where juvenile Arctic charr show initially lower growth, likely due to higher intraspecific competition. After reaching a size, where they can start feeding on eggs and smaller juveniles, which are both more frequent in partially migratory populations, growth surpasses that of resident populations. Cannibalism induced by high juvenile densities occurred almost exclusively in populations with migration and represents an altered energy pathway to the food web. The presence of large cannibalistic charr feeding on smaller ones that have a similar trophic level as charr from strictly resident populations (based on stomach content) coupled with steeper δ15N-size regression slopes illustrate the general increase of food chain length in systems with migration.ConclusionsOur results thus suggest that the consumption of migration-derived resources may result in longer food chains through middle-up rather than bottom-up effects. Furthermore, by occupying the apex of the food chain and feeding on juvenile conspecifics, resident individuals experience reduced competition with their young counterparts, which potentially balances their fitness with migratory individuals.