Considering cell migration is essential for understanding physiological processes and diseases. The vertical migration of cells in three dimensions is vital, but most previous studies on cell ...migration have only focused on two-dimensional horizontal migration. In this paper, cell migration in the vertical direction was studied. Barriers with a height of 1, 5, 10, and 25 µm with grating and arrows in channels as guiding patterns were fabricated. The effects of barrier height and guiding patterns on the vertical migration of MC3T3 cells were explored. The study revealed that taller barriers hinder vertical migration of MC3T3 cells, whereas grating and arrows in channels promote it. The time-lapse and micrograph images showed that as the barrier height increased, the cell climbing angle along the barrier sidewall decreased, and the time taken to climb over the barrier increased. These results indicate that taller barriers increase the difficulty of vertical migration by MC3T3 cells. To promote the vertical migration of MC3T3 cells, 10 µm tall barriers with 18° and 40° sloped sidewalls were fabricated. For barriers with 18° sloped sidewalls, the probability for MC3T3 cells to climb up and down the 10 µm tall barriers was 40.6% and 20.3%, respectively; this is much higher than the migration probability over vertical barriers. This study shows topographic guidance on the vertical migration of MC3T3 cells and broadens the understanding of cell migration in the vertical direction.
Most freshwater fish need to move freely through rivers to complete their life cycles. Thus, river barriers (e.g. dams, culverts and gauging stations) may delay, hinder or even block their ...longitudinal movements, affecting fish conservation. The most widespread solution to allow upstream fish migration are fishways, whereas downstream migration is basically facilitated through spillways, turbines or specific solutions such as bypass systems.
So far, studies and scientific discussions concerning bidirectional movements through fishways are scarce and focused on large dams and reservoirs, mainly with large migratory species such as salmonids, rather than smaller facilities and lesser known species.
This study investigated bidirectional movements through a small run‐of‐the‐river hydropower plant with a pool‐and‐orifice type fishway, using the Iberian barbel (Luciobarbus bocagei), a potamodromous cyprinid, as the target species. Passive integrated transponder and radio tracking data were collected over 4 years and combined to characterize upstream and downstream movements. The study focused primarily on fish movements through the fishway, but also estimated the multiple associated routes of passage.
The results show diverse fish movements with inter‐ and intra‐annual variability, with several individuals performing bidirectional movements and even some fish returning over the years.
The documented movements and observations indicate that fishways can serve as an effective bidirectional migration corridor for fish, potentially enhancing the conservation efforts for potamodromous species. This study supports the decision to use fishways as an overall mitigation tool to reduce the impact of small hydropower facilities on fish.
The rise of cinema as the predominant American entertainment around the turn of the last century coincided with the migration of hundreds of thousands of African Americans from the South to the urban ..."land of hope" in the North. This richly illustrated book, discussing many early films and illuminating black urban life in this period, is the first detailed look at the numerous early relationships between African Americans and cinema. It investigates African American migrations onto the screen, into the audience, and behind the camera, showing that African American urban populations and cinema shaped each other in powerful ways. Focusing on Black film culture in Chicago during the silent era,Migrating to the Moviesbegins with the earliest cinematic representations of African Americans and concludes with the silent films of Oscar Micheaux and other early "race films" made for Black audiences, discussing some of the extraordinary ways in which African Americans staked their claim in cinema's development as an art and a cultural institution.
Animal migration is a global phenomenon, but few studies have examined the substantial within‐ and between‐species variation in migration distances. We built a global database of 94 land migrations ...of large mammalian herbivore populations ranging from 10 to 1638 km. We examined how resource availability, spatial scale of resource variability and body size affect migration distance among populations. Resource availability measured as normalised difference vegetation index had a strong negative effect, predicting a tenfold difference in migration distances between low‐ and high‐resource areas and explaining 23% of the variation in migration distances. We found a weak, positive effect of the spatial scale of resource variability but no effect of body size. Resource‐poor environments are known to increase the size of mammalian home ranges and territories. Here, we demonstrate that for migratory populations as well, animals living in resource‐poor environments travel farther to fulfil their resource needs.
Fisher explores the process of migration chronologically and at levels varying from the migration of an individual community, to larger patterns of the collective movements of major ethnic groups, to ...the more abstract study of emigration, migration, and immigration. By highlighting an exemplary migration for each of the six chapters, the volume considers how technology, environment, and politics have shaped the diverse history of human migration.
This volume focuses on coalitions and collaborations formed by refugees from Nazi Germany in their host countries, connecting the NS-exile to other forms of displacement and persecution and locating ...it within the ruptures of civilization dominant in the twentieth and twenty-first centuries.
In many species, the spatial ecology of early age classes can differ significantly from adults. Adult Western Rattlesnakes (Crotalus oreganus Holbrook, 1840) at the northern extent of their range ...undertake small-scale but important seasonal migrations between communal hibernacula and summer foraging and mating grounds. Mature snakes also show annual fidelity to their migratory paths, providing a useful system to examine the development of migratory behaviour. We examined and compared spring outbound migratory movements of juveniles and adults at a site in southern British Columbia, Canada, using radiotelemetry data collected between 2011 and 2016 (adult snakes) and in 2021 (juvenile snakes). We found that compared with adult rattlesnakes, juveniles displayed similar directional orientation, direction of vertical migration, and path sinuosity, but initiated spring migrations later and exhibited shorter movements in terms of distances and rates. For example, juvenile straight-line migration distance (262 + or - 90 m) was significantly shorter than that for adults (1069 + or - 134 m; P < 0.001). We provide a starting point in attempting to understand an important question in migration--how individuals early on in their lives adopt different tactics--while contributing to our growing understanding of the complexity of patterns and variation in the movement ecology of a far-ranging snake.
Linked foraging and bioenergetics models allow for increased understanding of fish growth potential and behavior by incorporating prey availability coupled to environmental conditions including ...temperature and prey visibility. To inform our understanding of growth and vertical migration patterns of Chinook salmon (Oncorhynchus tshawytscha) inhabiting lentic ecosystems, we linked foraging and bioenergetics models to create GrowChinook (
http://growchinook.fw.oregonstate.edu/
). This multimodel design and optimization routine has broad applications in examining growth potential and predicting habitat use in stratified environments. We demonstrate the use of GrowChinook for the spring–summer rearing period in three Willamette River basin reservoirs, Oregon, USA. These reservoirs support juvenile spring Chinook salmon that exhibit a novel reservoir-reared life history that includes larger juvenile fish compared with nearby stream-reared subyearlings. Model outputs of predicted growth and depth use patterns based on observed prey distributions and environmental conditions were corroborated by observed empirical size and growth data from other years. Our simulations support diel vertical migration as a tactic that increases growth potential and contribute to understanding juvenile Chinook salmon growth in stratified systems.
La gestion migratoire est un imaginaire qui préconise l’ouverture régulée face aux migrations internationales. Il réduit leur complexité pour les rendre intelligibles, les gouverner d’une manière ...dépolitisée et technocratique, et pour perpétuer les flux de la mondialisation. Mais en l’absence d’un régime international de la migration, la gestion migratoire est concurrencée par les imaginaires de la sécurisation et de la libéralisation des migrations. Sa sédimentation durable dépend alors de la construction matérielle de ses interprétations à travers des institutions. Pour comprendre cette évolution de la gestion migratoire de l’interprétation à la construction, cet ouvrage retrace les trois moments de son émergence, de sa sélection et de son maintien au sein de l’Organisation internationale pour la migration (OIM). Cette institution clé de la gouvernance migratoire a été marquée du début des années 2000 à 2018 par l’extension de son rôle et de ses activités à l’aune de la gestion migratoire. Cet ouvrage mobilise une approche qui mêle économie politique culturelle et analyse critique du discours pour examiner l’évolution d’un imaginaire à partir de l’interaction entre production de sens, capacité d’action des acteurs sociaux, structuration du contexte institutionnel, et technologies gouvernementales. Fort de l’analyse de réunions et documents de l’OIM, l’ouvrage révèle comment divers fonctionnaires internationaux, diplomates et experts ont formulé, diffusé, matérialisé ou encore contesté la gestion migratoire. L’étude de cet imaginaire permet de comprendre la transformation de l’OIM et son rôle dans la constitution d’une nouvelle gouvernance migratoire suite à l’adoption en 2018 du Pacte mondial pour les migrations.
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