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1
Gray, S. H., et M. A. Epton. « Multigrid migration : Reducing the migration aperture but not the migrated dips ». GEOPHYSICS 55, no 7 (juillet 1990) : 856–62. http://dx.doi.org/10.1190/1.1442900.
Texte intégralRésumé :
Given a frequency f, CDP interval Δx, and upper‐surface velocity v(0), the spatial Nyquist criterion defines a range of unaliased emergence angles for seismic reflection events. For migration, events outside that range should be discarded beforehand by dip filtering, or the migration operator should be trained to ignore them. In this paper, we express the spatial Nyquist criterion as a limitation on the CDP interval, rather than on emergence angle, which allows Δx to be adjusted as a function of emergence angle, increasing with decreasing emergence angle. We exploit this fact by creating two separate migration grids: a fine grid, with trace spacing Δx, for migrating events with large emergence angles; and a coarse grid, with trace spacing 2Δx, for migrating events with small emergence angles. Combining the two migrations is straightforward. The coarse grid migration, involving one‐half the number of input traces and one‐half the number of output traces, represents a considerable time savings over the small‐emergence‐angle portion of the migration on the original fine grid. The two migrations need not be performed separately, so that overhead associated with migration setup operations need not be paid twice. In fact, a modification of this idea allows the migration to be performed with almost no increase in storage requirements.
2
Thomas, L. A., et K. M. Yamada. « Contact stimulation of cell migration ». Journal of Cell Science 103, no 4 (1 décembre 1992) : 1211–14. http://dx.doi.org/10.1242/jcs.103.4.1211.
Texte intégralRésumé :
Mass migrations of dense cell populations occur periodically during embryonic development. It is known that extracellular matrices, through which the cells migrate, facilitate locomotion. However, this does not explain how cells, such as neural crest, can migrate as a dense cohort of cells in essentially continuous contact with one another. We report here that unique behavioral characteristics of the migrating cells may contribute to cohesive migration. We used time-lapse video microscopy to analyze the migration of quail neural crest cells and of two crest derivatives, human melanoma cells and melanocytes. These cells migrated poorly, if at all, when isolated, but could be stimulated up to 200-fold to travel following contact with migrating cells. This phenomenon, which we have termed “contact-stimulated migration,” appeared to activate and sustain migration of the mass of cells. Cells that became dissociated from the others ceased directional migration, thereby limiting aberrant cell dispersion. Fibroblasts were minimally responsive to this novel phenomenon, which may be crucial for major, mass cell migrations.
3
Larner, Ken, et Craig Beasley. « Cascaded migrations : Improving the accuracy of finite‐difference migration ». GEOPHYSICS 52, no 5 (mai 1987) : 618–43. http://dx.doi.org/10.1190/1.1442331.
Texte intégralRésumé :
The accuracy of time migrations done with finite‐difference schemes deteriorates with increasing reflector dip. Some properties of migration in general, and of finite‐difference approaches in particular, suggest a way of improving the accuracy of finite‐difference schemes for migrating steep dips. First, although data will be undermigrated when too low a velocity is used in migration, a correctly migrated result can be obtained by migrating again, this time with the previously undermigrated result as input. In fact, a sequence of undermigrations will yield the correct result as long as the sum of the squares of the migration velocities used in the different migration stages equals the square of the correct migration velocity. A second property is that the apparent spatial dip of a reflector perceived by the migration process is a function of not only the time dip of the unmigrated reflection, but also the velocity used in the migration. In a sequence of low‐velocity migrations, the apparent spatial dip perceived at each migration stage can be considerably less than the true dip. Thus, because finite‐difference migration is accurate for small spatial dips, the cascaded migrations yield a more accurate result than that of single‐stage migration. Also, because each migration stage is done with low velocity, the depth step can be large; hence, the computational effort need not be. The accuracy of the method is not compromised (in fact, it improves) in media in which velocity increases with depth. Moreover, the cascaded approach suffers no more than other methods of time migration where velocity varies mildly in the lateral direction. In applications of the method to stacked data from the Gulf of Mexico, reflections from near‐vertical flanks of salt domes were migrated with accuracy comparable to that achieved by frequency‐wavenumber domain migration.
4
Goldberg, Amy, Torsten Günther, Noah A. Rosenberg et Mattias Jakobsson. « Ancient X chromosomes reveal contrasting sex bias in Neolithic and Bronze Age Eurasian migrations ». Proceedings of the National Academy of Sciences 114, no 10 (21 février 2017) : 2657–62. http://dx.doi.org/10.1073/pnas.1616392114.
Texte intégralRésumé :
Dramatic events in human prehistory, such as the spread of agriculture to Europe from Anatolia and the late Neolithic/Bronze Age migration from the Pontic-Caspian Steppe, can be investigated using patterns of genetic variation among the people who lived in those times. In particular, studies of differing female and male demographic histories on the basis of ancient genomes can provide information about complexities of social structures and cultural interactions in prehistoric populations. We use a mechanistic admixture model to compare the sex-specifically–inherited X chromosome with the autosomes in 20 early Neolithic and 16 late Neolithic/Bronze Age human remains. Contrary to previous hypotheses suggested by the patrilocality of many agricultural populations, we find no evidence of sex-biased admixture during the migration that spread farming across Europe during the early Neolithic. For later migrations from the Pontic Steppe during the late Neolithic/Bronze Age, however, we estimate a dramatic male bias, with approximately five to 14 migrating males for every migrating female. We find evidence of ongoing, primarily male, migration from the steppe to central Europe over a period of multiple generations, with a level of sex bias that excludes a pulse migration during a single generation. The contrasting patterns of sex-specific migration during these two migrations suggest a view of differing cultural histories in which the Neolithic transition was driven by mass migration of both males and females in roughly equal numbers, perhaps whole families, whereas the later Bronze Age migration and cultural shift were instead driven by male migration, potentially connected to new technology and conquest.
5
Stolt, Robert H. « A prestack residual time migration operator ». GEOPHYSICS 61, no 2 (mars 1996) : 605–7. http://dx.doi.org/10.1190/1.1443987.
Texte intégralRésumé :
Larner and Beasley (1987) present cascaded migration as a way to increase the power and effectiveness of relatively simple migration methods. In particular, f-k migration (Stolt, 1978) can be made to accommodate a depth‐dependent velocity as a cascade of constant‐velocity migrations. The core concept is that data which have been migrated with an approximate velocity can be effectively migrated to their true velocity by migrating with a velocity that is equal to the square root of the difference between the squares of the true and approximate velocities.
6
Hinch, Scott G., et Peter S. Rand. « Swim speeds and energy use of upriver-migrating sockeye salmon (Oncorhynchus nerka) : role of local environment and fish characteristics ». Canadian Journal of Fisheries and Aquatic Sciences 55, no 8 (1 août 1998) : 1821–31. http://dx.doi.org/10.1139/f98-067.
Texte intégralRésumé :
We used electromyogram (EMG) radiotelemetry to assess swimming activity (e.g., swim speeds), behaviour, and migration speeds (e.g., ground speeds) of individual adult sockeye salmon (Oncorhynchus nerka) migrating through several reaches of the Fraser and Nechako rivers in British Columbia. Using a laboratory swim flume and volitionally swimming adult fish carrying EMG transmitters, we developed relationships between EMG pulse intervals and swim speeds. A bioenergetics model was used to estimate reach-specific energy use per metre for each individual based on the average swim speed, migration time, body size, and river temperature. Migration was most energetically efficient (i.e., migration costs per unit distance traveled were relatively low) for females compared with males, large males compared with small males, and 1995 males compared with 1993 males. In all three cases, differences in swim speed patterns were primarily responsible for differences in energy use. For both sexes and in both years, migrations through reaches that contained a constriction (caused by an island, gravel bar, or large rock outcropping) were energetically inefficient compared with that through reaches with no constrictions. The high energetic costs at constrictions seem to result from long travel times probably caused by turbulent flow patterns that may generate confusing migrational cues.
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Pytel, Sławomir Piotr, et Iwona Kiniorska. « The Socioeconomic Status of Polish Pensioners Before and After Migration ». Acta Universitatis Lodziensis. Folia Oeconomica 5, no 344 (30 septembre 2019) : 67–84. http://dx.doi.org/10.18778/0208-6018.344.05.
Texte intégralRésumé :
The aim of this paper is to describe the socioeconomic status of migrating seniors before and after migration. This analysis will enable us to determine whether the overall effect of their migrations is a positive one or a negative one. In order to determine subjective reasons for migrations, questionnaire surveys are used. An analysis of the responses allows us to compare the migrants’ living conditions before and after migration with a view to confirming or rejecting Wolpert’s (1965) assumptions and to describe the role of migrations in meeting pensioners’ needs. Our study confirms the approach of Wolpert (1965), assuming that the behaviour of migrants, including migrating pensioners, is determined by place utility, i.e. the sum of advantages to be obtained by the migrant. The pensioners who migrated are well‑off, our respondents report that they are able to meet all their needs if spending money prudently.
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Ffrench-Constant, C., et R. O. Hynes. « Patterns of fibronectin gene expression and splicing during cell migration in chicken embryos ». Development 104, no 3 (1 novembre 1988) : 369–82. http://dx.doi.org/10.1242/dev.104.3.369.
Texte intégralRésumé :
A variety of evidence suggests that fibronectin (FN) promotes cell migration during embryogenesis, and it has been suggested that the deposition of FN along migratory pathways may also play a role in cell guidance. In order to investigate such a role for FN, it is important to determine the relative contribution of migrating and pathway-forming cells to the FN in the migratory track, as any synthesis of FN by the migrating cells might be expected to mask guidance cues provided by the exogenous FN from pathway-forming cells. We have therefore used in situ hybridization to determine in developing chicken embryos the distribution and alternative splicing of FN mRNA during three different cell migrations known to occur through FN-rich environments; neural crest cell migration, mesenchymal cell migration in the area vasculosa and endocardial cushion cell migration in the heart. Our results show that trunk neural crest cells do not contain significant FN mRNA during their initial migration. In contrast, migrating mesenchymal cells of the area vasculosa and endocardial cushion cells both contain abundant FN mRNA. Furthermore, the FN mRNA in these migrating mesenchymal and endocardial cells appears to be spliced in a manner identical with that present in the cells adjacent to their pathways. This in vivo evidence for FN synthesis by migrating and pathway cells argues against a generalized role for exogenously produced FN as a guidance mechanism for cell migration.
9
Liu, Xialin, Junsheng Wu, Gang Sha et Shuqin Liu. « Virtual Machine Consolidation with Minimization of Migration Thrashing for Cloud Data Centers ». Mathematical Problems in Engineering 2020 (3 août 2020) : 1–13. http://dx.doi.org/10.1155/2020/7848232.
Texte intégralRésumé :
Cloud data centers consume huge amount of electrical energy bringing about in high operating costs and carbon dioxide emissions. Virtual machine (VM) consolidation utilizes live migration of virtual machines (VMs) to transfer a VM among physical servers in order to improve the utilization of resources and energy efficiency in cloud data centers. Most of the current VM consolidation approaches tend to aggressive-migrate for some types of applications such as large capacity application such as speech recognition, image processing, and decision support systems. These approaches generate a high migration thrashing because VMs are consolidated to servers according to VM’s instant resource usage without considering their overall and long-term utilization. The proposed approach, dynamic consolidation with minimization of migration thrashing (DCMMT) which prioritizes VM with high capacity, significantly reduces migration thrashing and the number of migrations to ensure service-level agreement (SLA) since it keeps VMs likely to suffer from migration thrashing in the same physical servers instead of migrating. We have performed experiments using real workload traces compared to existing aggressive-migration-based solutions; through simulations, we show that our approach improves migration thrashing metric by about 28%, number of migrations metric by about 21%, and SLAV metric by about 19%.
10
Romero, Louis A., Dennis C. Ghiglia, Curtis C. Ober et Scott A. Morton. « Phase encoding of shot records in prestack migration ». GEOPHYSICS 65, no 2 (mars 2000) : 426–36. http://dx.doi.org/10.1190/1.1444737.
Texte intégralRésumé :
Frequency‐domain shot‐record migration can produce higher quality images than Kirchhoff migration but typically at a greater cost. The computing cost of shot‐record migration is the product of the number of shots in the survey and the expense of each individual migration. Many attempts to reduce this cost have focused on the speed of the individual migrations, trying to achieve a better trade‐off between accuracy and speed. Another approach is to reduce the number of migrations. We investigate the simultaneous migration of shot records using frequency‐domain shot‐record migration algorithms. The difficulty with this approach is the production of so‐called crossterms between unrelated shot and receiver wavefields, which generate unwanted artifacts or noise in the final image. To reduce these artifacts and obtain an image comparable in quality to the single‐shot‐per‐migration result, we have introduced a process called phase encoding, which shifts or disperses these crossterms. The process of phase encoding thus allows one to trade S/N ratio for the speed of migrating the entire survey. Several encoding functions and two application strategies have been tested. The first strategy, combining multiple shots per migration and using each shot only once, reduces computation in direct relation to the number of shots combined. The second strategy, performing multiple migrations of all the shots in the survey, provides a means to reduce the crossterm noise by stacking the resulting images. The additional noise in both strategies may be tolerated if it is no stronger than the inherent seismic noise in the migrated image and if the final image is achieved with less cost.
11
Yu, Zhou, George A. McMechan, Phil D. Anno et John F. Ferguson. « Wavelet‐transform‐based prestack multiscale Kirchhoff migration ». GEOPHYSICS 69, no 6 (novembre 2004) : 1505–12. http://dx.doi.org/10.1190/1.1836823.
Texte intégralRésumé :
We propose a Kirchhoff‐style algorithm that migrates coefficients obtained by wavelet decomposition of seismic traces over time. Wavelet‐based prestack multiscale Kirchhoff migration involves four steps: wavelet decomposition of the seismic data, thresholding of the resulting wavelet coefficients, multiscale Kirchhoff migration, and image reconstruction from the multiscale images. The migration procedure applied to each wavelet scale is the same as conventional Kirchhoff migration but operates on wavelet coefficients. Since only the wavelet coefficients are migrated, the cost of wavelet‐based migration is reduced compared to that of conventional Kirchhoff migration. Kirchhoff migration of wavelet‐decomposed data, followed by wavelet reconstruction, is kinematically equivalent to and yields similar migrated signal shapes and amplitudes as conventional Kirchhoff migration when data at all wavelet scales are included. The decimation in the conventional discrete pyramid wavelet decomposition introduces a translation‐variant phase distortion in the wavelet domain. This phase distortion is overcome by using a stationary wavelet‐transform rather than the conventional discrete wavelet‐transform of the data to be migrated. A wavelet reconstruction operator produces a single composite broadband migrated space‐domain image from multiscale images. Multiscale images correspond to responses in different frequency windows, and migrating the data at each scale has a different cost. Migrating some, or only one, of the individual scale data sets considerably reduces the computational cost of the migration. Successful 2D tests are shown for migrations of synthetic data for a point‐diffractor model, a multilayer model, and the Marmousi model.
12
de Diego, I., K. Kyriakopoulou, D. Karagogeos et M. Wassef. « Multiple influences on the migration of precerebellar neurons in the caudal medulla ». Development 129, no 2 (15 janvier 2002) : 297–306. http://dx.doi.org/10.1242/dev.129.2.297.
Texte intégralRésumé :
Neurons destined to form several precerebellar nuclei are generated in the dorsal neuroepithelium (rhombic lip) of caudal hindbrain. They form two ventrally directed migratory streams, which behave differently. While neurons in the superficial migration migrate in a subpial position and cross the midline to settle into the contralateral hindbrain, neurons in the olivary migration travel deeper in the parenchyma and stop ipsilaterally against the floor plate. In the present study, we compared the behavior of the two neuronal populations in an organotypic culture system that preserves several aspects of their in vivo environment. Both migrations occurred in mouse hindbrain explants dissected at E11.5 even when the floor plate was ablated at the onset of the culture period, indicating that they could rely on dorsoventral cues already distributed in the neural tube. Nevertheless, the local constraints necessary for the superficial migration were more specific than for the olivary migration. Distinct chemoattractive and chemorespulsive signal were found to operate on the migrations. The floor plate exhibited a strong chemoattractive influence on both migrations, which deviated from their normal path in the direction of ectopic floor plate fragments. It was also found to produce a short-range stop signal and to induce inferior olive aggregation. The ventral neural tube was also found to inhibit or slow down the migration of olivary neurons. Interestingly, while ectopic sources of netrin were found to influence both migrations, this effect was locally modulated and affected differentially the successive phases of migration. Consistent with this observation, while neurons in the superficial migration expressed the Dcc-netrin receptor, the migrating olivary neurons did not express Dcc before they reached the midline. Our observations provide a clearer picture of the hierarchy of environmental cues that influence the morphogenesis of these precerebellar nuclei.
13
Corkeron, Peter, et Miranda Brown. « Pod Characteristics of Migrating Humpback Whales (Megaptera Novaeangliae) Off the East Australian Coast ». Behaviour 132, no 3-4 (1995) : 163–79. http://dx.doi.org/10.1163/156853995x00676.
Texte intégralRésumé :
AbstractThe size and sex composition of migrating humpback whale pods were investigated off the east Australian coast. Two hundred and thirty one singletons, 257 pairs, 63 trios, 7 quads and 4 pods containing more than 5 individuals were observed during two land-based surveys carried out throughout the northward migration in 1991 and 1993. Generally humpback whales migrated northward towards the breeding area in pods of I or 2 individuals. In 1992, a biopsy study was carried out throughout the northward and southward migrations. Pods migrating southward (mean = 2.59, SE = 0.19) towards the feeding areas were significantly larger than those travelling north (mean = 1.75, SE = 0.03). The sex of 134 individuals in 63 complete pods was determined by molecular analysis of skin biopsies. Male humpback whales were found in larger pods than females. The most common pod type observed was the male-female pair, which is suggestive of either mating on migration and/or mate-guarding. Males were found associated together frequently. Competitive behaviour was observed during both the northward and southward migrations. The sexing of all individuals within 8 competitive pods indicated that not all contained a female. Although competitive behaviour was observed during the migration, most male-male associations were charactcrised by non-agonistic and occasionally cooperative interactions. We suggest there is a behavioural continuum on migration between the feeding and breeding grounds which is not governed solely by spatial proximity to the terminus. The pod characteristics of humpback whales on their return migration to the feeding grounds showed greatest similarity to those observed on breeding grounds elsewhere. In conclusion, our study showed that the migration of humpback whales is more
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Torrence, S. A. « Positional cues governing cell migration in leech neurogenesis ». Development 111, no 4 (1 avril 1991) : 993–1005. http://dx.doi.org/10.1242/dev.111.4.993.
Texte intégralRésumé :
The stereotyped distribution of identified neurons and glial cells in the leech nervous system is the product of stereotyped cell migrations and rearrangements during embryogenesis. To examine the dependence of long-distance cell migrations on positional cues provided by other tissues, embryos of Theromyzon rude were examined for the effects of selective ablation of various embryonic cell lines on the migration and final distribution of neural and glial precursor cells descended from the bilaterally paired ectodermal cell lines designated q bandlets. The results suggest that neither the commitment of q-bandlet cells to migrate nor the general lateral-to-medial direction of their migration depend on interactions with any other cell line. However, the ability of the migrating cells to follow their normal pathways and to find their normal destinations does depend on interactions with cells of the mesodermal cell line, which appears to provide positional cues that specify the migration pathways.
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McMillan, M. N., C. Huveneers, J. M. Semmens et B. M. Gillanders. « Partial female migration and cool-water migration pathways in an overfished shark ». ICES Journal of Marine Science 76, no 4 (5 décembre 2018) : 1083–93. http://dx.doi.org/10.1093/icesjms/fsy181.
Texte intégralRésumé :
Abstract Knowledge about reproductive movements can be of important conservation value for over-exploited species that are vulnerable when moving between and within key reproductive habitats. Lack of knowledge persists around such movements in the overfished school shark Galeorhinus galeus in Australia. Management assumes all pregnant females migrate between adult aggregations in the Great Australian Bight, South Australia, and nursery areas around Bass Strait and Tasmania. We tracked 14 late-term pregnant females tagged in South Australia using satellite-linked pop-up archival tags to investigate extent, timing, and routes of migrations. We found partial migration, with some females (n = 7) remaining near aggregating areas throughout the pupping season, some migrating to known nursery areas (n = 3), and one migrating ∼3 000 km to New Zealand. We conclude female movements and pupping habitats are less spatially constrained than assumed and propose females use cool-water routes along the shelf break to reduce energy costs of migration. Migrating females using these routes faced greater fishing pressure than sharks in inshore areas and were not protected by inshore shark fishing closures designed to protect them. This study demonstrates the complexity of reproductive movements that can occur in wide-ranging species and highlights the value of explicit movement data.
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Castillo Ramírez, Guillermo. « Autonomía de las migraciones : de la producción política de fronteras a las luchas migrantes ». Migraciones internacionales 14 (15 avril 2023) : 0. http://dx.doi.org/10.33679/rmi.v1i1.2573.
Texte intégralRésumé :
Within a global context, the increase in migrations in different regions of the world during this century has led to an increase in academic production on migration. The aim of this article is to analyze the autonomy of migration from the approaches of two of its greatest exponents, Mezzadra and De Genova, who investigate migration’s political condition, addressing the relationships of mutual influence between migrants, borders, and the State. The contribution of this paper is to show how this theoretical approach focuses on two fundamental processes to understand migration. On the one hand, it refers to the actions, strategies, and practices of those involved in shaping cross-border migration. On the other hand, it considers the role of States and borders as legal-political and historical constructs in shaping international (often irregular) migratory flows.
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Thomer, Andrea K., Alexandria Jane Rayburn et Allison R. B. Tyler. « Three approaches to documenting database migrations ». International Journal of Digital Curation 15, no 1 (6 août 2020) : 5. http://dx.doi.org/10.2218/ijdc.v15i1.726.
Texte intégralRésumé :
Database migration is a crucial aspect of digital collections management, yet there are few best practices to guide practitioners in this work. There is also limited research on the patterns of use and processes motivating database migrations. In the “Migrating Research Data Collections” project, we are developing these best practices through a multi-case study of database and digital collections migration. We find that a first and fundamental problem faced by collection staff is a sheer lack of documentation about past database migrations. We contribute a discussion of ways information professionals can reconstruct missing documentation, and some three approaches that others might take for documenting migrations going forward.
[This paper is a conference pre-print presented at IDCC 2020 after lightweight peer review.]
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Barriteau, Violet Eudine. « Meditations on Migrations of Gender, Mobility, and Movement from the Commonwealth Caribbean ». Frontiers : A Journal of Women Studies 45, no 2 (2024) : 45–78. http://dx.doi.org/10.1353/fro.2024.a935656.
Texte intégralRésumé :
Abstract: This article constitutes a multilayered feminist analysis of the intertwining of gender, mobility, and migration in the post-emancipation, Commonwealth Caribbean. In interrogating the nexus of gender and migration the article exposes how migration narratives have become misgendered through a linear equation of gender in migration with the physical presence of migrating women in receiving countries or with migration policies overtly encouraging women's migration. This results in an incorrect knowledge claim that gender became a factor in Caribbean migration in the post–World War II period, thus ignoring centuries long formations of gendered migrations. The article demonstrates that both the concept of the social relations of gender and embodied beings known as women have always migrated, have always traveled through historical and contemporary migration flows and studies. What changes and acquires new manifestations is the social relations of gender, seemingly appearing and disappearing, but instead is ever present since Columbus's Caribbean intrusion. I theorize and define two new feminist concepts—the misgendering of migration and mobilized sexual autonomy . I examine the enduring longing for belonging, the search for "home" that haunts Caribbean migrants and their expanding diasporas. I conclude by observing that Caribbean people must come to terms with our unending search for home by coming home to who we are, wherever we are.
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Thilagavathi, N., D. Divya Dharani, R. Sasilekha, Vasundhara Suruliandi et V. Rhymend Uthariaraj. « Energy Efficient Load Balancing in Cloud Data Center Using Clustering Technique ». International Journal of Intelligent Information Technologies 15, no 1 (janvier 2019) : 84–100. http://dx.doi.org/10.4018/ijiit.2019010104.
Texte intégralRésumé :
Cloud computing has seen tremendous growth in recent days. As a result of this, there has been a great increase in the growth of data centers all over the world. These data centers consume a lot of energy, resulting in high operating costs. The imbalance in load distribution among the servers in the data center results in increased energy consumption. Server consolidation can be handled by migrating all virtual machines in those underutilized servers. Migration causes performance degradation of the job, based on the migration time and number of migrations. Considering these aspects, the proposed clustering agent-based model improves energy saving by efficient allocation of the VMs to the hosting servers, which reduces the response time for initial allocation. Middle VM migration (MVM) strategy for server consolidation minimizes the number of VM migrations. Further, randomization of extra resource requirement done to cater to real-time scenarios needs more resource requirements than the initial requirement. Simulation results show that the proposed approach reduces the number of migrations and response time for user request and improves energy saving in the cloud environment.
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Mueller, Thomas, Robert B. O’Hara, Sarah J. Converse, Richard P. Urbanek et William F. Fagan. « Social Learning of Migratory Performance ». Science 341, no 6149 (29 août 2013) : 999–1002. http://dx.doi.org/10.1126/science.1237139.
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Successful bird migration can depend on individual learning, social learning, and innate navigation programs. Using 8 years of data on migrating whooping cranes, we were able to partition genetic and socially learned aspects of migration. Specifically, we analyzed data from a reintroduced population wherein all birds were captive bred and artificially trained by ultralight aircraft on their first lifetime migration. For subsequent migrations, in which birds fly individually or in groups but without ultralight escort, we found evidence of long-term social learning, but no effect of genetic relatedness on migratory performance. Social learning from older birds reduced deviations from a straight-line path, with 7 years of experience yielding a 38% improvement in migratory accuracy.
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Fuchs, Philip X., Mojca Doupona, Kinga Varga, Marta Bon, Cristina Cortis, Andrea Fusco, Loriana Castellani et al. « Multi-national perceptions on challenges, opportunities, and support structures for Dual Career migrations in European student-athletes ». PLOS ONE 16, no 6 (25 juin 2021) : e0253333. http://dx.doi.org/10.1371/journal.pone.0253333.
Texte intégralRésumé :
Despite Dual Careers (sports and education) and mobility of students being priorities in the funding policies of the European Commission, migrating student-athletes report severe challenges and decreased performance or dropouts at sport and academic levels. The objective of this study was to depict and assess the perceptions on challenges, support services, and their effectiveness in consideration of specific characteristics of participants and migrations. Based on a meta-synthesis and previous findings, a 50-items questionnaire was developed and completed by 245 student-athletes in 5 European countries. Participants with Dual Careers migration experience (n = 140) were considered for analyses of qualitative and quantitative (ordinal 5pt-Likert-scaled and metric) data on the Dual Career status, migration characteristics, received services, and outcomes. Chi-square-tests were conducted for differences between countries and genders at a significance level of p < .05. Country-related differences were found for experiences and intentions to migrate (X2(12) = 50.52, p<0.001), duration of the migration (X2(16) = 38.20, p = 0.001), financial support (X2(8) = 29.87, p<0.001), and decreased performances in academics (X2(16) = 56.12, p<0.001) and sports (X2(16) = 31.79, p = 0.01). Gender-related difference emerged in financial support (X2(4) = 10.68, p = 0.03), duration of the migration (X2(4) = 14.56, p = 0.01), and decreased academic performance (X2(4) = 10.57, p = 0.03). Tutoring and counselling support was ranked as the most effective support, especially when received from the academic field (4.0±1.0 pt) and others (4.1±0.8 pt), followed by online services from sport and academic sectors (both: 3.9±0.9 pt). Considering the pervasive globalization of sport and education, Dual Career migration can contribute to the development of a European sport culture. The high ratio of migrating student-athletes underlines the relevance of migrations in the field of Dual Careers. This study contributes to the literature by adding insights on practices, challenges, supports, and outcomes perceived by student-athletes migrating in Europe. Moreover, country- and gender-related differences support the consideration of specific characteristics and reveal critical factors in specific target groups. The findings contribute to identifying requirements and effective support measures in Dual Career migrations and can be used to improve support services.
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Kim, Sarah Hyun Ji, et Daniel A. Hammer. « Integrin crosstalk allows CD4+ T lymphocytes to continue migrating in the upstream direction after flow ». Integrative Biology 11, no 10 (octobre 2019) : 384–93. http://dx.doi.org/10.1093/intbio/zyz034.
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Abstract In order to perform critical immune functions at sites of inflammation, circulatory T lymphocytes must be able to arrest, adhere, migrate and transmigrate on the endothelial surface. This progression of steps is coordinated by cellular adhesion molecules (CAMs), chemokines, and selectins presented on the endothelium. Two important interactions are between Lymphocyte Function-associated Antigen-1 (LFA-1) and Intracellular Adhesion Molecule-1 (ICAM-1) and also between Very Late Antigen-4 (VLA-4) and Vascular Cell Adhesion Molecule-1 (VCAM-1). Recent studies have shown that T lymphocytes and other cell types can migrate upstream (against the direction) of flow through the binding of LFA-1 to ICAM-1. Since upstream migration of T cells depends on a specific adhesive pathway, we hypothesized that mechanotransduction is critical to migration, and that signals might allow T-cells to remember their direction of migration after the flow is terminated. Cells on ICAM-1 surfaces migrate against the shear flow, but the upstream migration reverts to random migration after the flow is stopped. Cells on VCAM-1 migrate with the direction of flow. However, on surfaces that combine ICAM-1 and VCAM-1, cells crawl upstream at a shear rate of 800 s−1 and continue migrating in the upstream direction for at least 30 minutes after the flow is terminated—we call this ‘migrational memory’. Post-flow upstream migration on VCAM-1/ICAM-1 surfaces is reversed upon the inhibition of PI3K, but conserved with cdc42 and Arp2/3 inhibitors. Using an antibody against VLA-4, we can block migrational memory on VCAM-1/ICAM-1 surfaces. Using a soluble ligand for VLA-4 (sVCAM-1), we can promote migrational memory on ICAM-1 surfaces. These results indicate that, while upstream migration under flow requires LFA-1 binding to immobilized ICAM-1, signaling from VLA-4 and PI3K activity is required for the migrational memory of CD4+ T cells. These results indicate that crosstalk between integrins potentiates the signal of upstream migration.
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Cambois, Guillaume. « A proof for the convergence of 15‐degree cascaded migration ». GEOPHYSICS 56, no 12 (décembre 1991) : 2110–13. http://dx.doi.org/10.1190/1.1443024.
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Larner and Beasley (1987) introduced cascaded migrations and showed, without proving it rigorously, that iterating a 15-degree migration with proper choice of migration velocity was equivalent to a 90-degree migration. In this paper, I will give a proof based on a power series expansion that makes it possible to compare this method with other migration methods. This analysis shows, for example, that cascaded 45-degree migrations yield higher accuracy than cascaded 15-degree migrations with fewer iterations.
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Baranov, Evgeny Yurievich. « Migration of population in Ural in the XX century : problems of modern historiography ». Genesis : исторические исследования, no 11 (novembre 2019) : 11–28. http://dx.doi.org/10.25136/2409-868x.2019.11.31467.
Texte intégralRésumé :
The goal of this research lies in identification of the key problems of modern historiography with regards to the history of population migration in Ural in the XX century. The author analyzes the results of study of migration history in the region, determines the range of questions within the problematic field of the research, as well as the leading vectors of research. An attempt is made to shape future prospects of research work on the topic of migrations in Ural. The relevance of the article is substantiated by the possibilities of fundamental understanding of the historical and modern trends of population migration and scientific conceptualization of the history of migrations in the XX century. The migration of population in Ural in the centenary historical retrospective have not been previously been an independent subject of historiographical analysis. The conducted study demonstrates that the scholars determined the migration, its key factors and directions; suggested the variations of periodization of the history of migration in Ural; studied the role of migrations in demographic development of the Ural regions at different historical periods. The article highlights the main problems of historiography: exodus, evacuation and re-evacuation, migration policy, “migration transition”, migrations of urban and rural population, roles of migration in urbanization processes, formation of regional population, ethnic specificities of migration. It is established that significant attention of the historians is dedicated to the study of migrations in the 1920’s – 1930’s, as well as the years of the Great Patriotic War. The research carries fragmentary character. Its prospects are associated with the detailed examination of migrations in the Ural regions, and fundamental generalization aimed at identification of patterns and mechanism of the transformation of migrations, as well as the formation of their coherent picture in Ural in the XX century.
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Lipowska, Dorota, et Adam Lipowski. « Evolution towards Linguistic Coherence in Naming Game with Migrating Agents ». Entropy 23, no 3 (28 février 2021) : 299. http://dx.doi.org/10.3390/e23030299.
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As an integral part of our culture and way of life, language is intricately related to the migrations of people. To understand whether and how migration shapes language formation processes, we examine the dynamics of the naming game with migrating agents. (i) When all agents may migrate, the dynamics generates effective surface tension that drives the coarsening. Such behaviour is very robust and appears for a wide range of densities of agents and their migration rates. (ii) However, when only multilingual agents are allowed to migrate, monolingual islands are typically formed. In such a case, when the migration rate is sufficiently large, the majority of agents acquire a common language that spontaneously emerges with no indication of surface-tension-driven coarsening. Relatively slow coarsening that takes place in a dense static population is very fragile, and an arbitrarily small migration rate can most likely divert the system towards the quick formation of monolingual islands. Our work shows that migration influences language formation processes, but additional details such as density or mobility of agents are needed to more precisely specify this influence.
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Petelska, Michalina. « Migration Museums : A Proposed Typology ». Muzeológia a kultúrne dedičstvo 10, no 4 (2022) : 27–45. http://dx.doi.org/10.46284/mkd.2022.10.4.2.
Texte intégralRésumé :
The aim of this article is to propose the perception of migration museums as a coherent group. Migration museums are perceived by some professionals as specialised, thematic historical or ethnographic museums, whereas this paper organises the diversity of historical and contemporary migratory movements in connection with the current dynamic development of museums. Among the migration museums, the following types were grouped and distinguished: migration museums which comprehensively address the subject of various migrations, migration museums in the historical migration infrastructure, open-air migration museums, migration museums dedicated to specific events, migration museums established by immigrant communities and virtual migration museums. The importance of addressing the topic of migration in other types of museums, such as maritime, ethnographic, historical and art museums, is also highlighted. Covering the global network of migration museums allows us to search for answers to the question of the role of museums at a time when refugees and climate migrations will be among the greatest challenges for humanity.
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Sirkeci, Ibrahim, Jeffrey H. Cohen et Elli Heikkila. « Editorial : Migration and Migration Letters ». MIGRATION LETTERS 5, no 2 (28 octobre 2008) : 107–10. http://dx.doi.org/10.33182/ml.v5i2.46.
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Migration is a dynamic and changing phenomenon so too is migration scholarship and research. While we understand that migration experience has always been responsive to political and economic environments we continue to search for new approaches and statements about migration’s triggers. Speedy progress in information and communication systems helped people in making informed decisions; improvements in transportation have both increased the number of potential destinations and origin areas contributing to migration. In policy and research papers, we have seen more and more mention of temporary migration, circular migration, and short term migration and so on. Chinese and Indian economic growth, the attraction of the EU and USA to job seekers everywhere, food crisis, environmental hazards as well as large or small scale wars and conflicts will continue to displace people internally and internationally.
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Mulpuri, Gowtham. « Migrating Legacy Systems : Successes in Migrating Legacy Systems to Modern Technologies, Migration to Self - Hosted Artifactory ». International Journal of Science and Research (IJSR) 13, no 3 (5 mars 2024) : 942–45. http://dx.doi.org/10.21275/sr24314142922.
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Rahman, Afzalur. « A Study on Irregular Migration from Bangladesh to Malaysia through the Bay of Bengal and the Andaman Sea ». Otoritas : Jurnal Ilmu Pemerintahan 10, no 2 (30 octobre 2020) : 120–31. http://dx.doi.org/10.26618/ojip.v10i2.4640.
Texte intégralRésumé :
Irregular migration is an issue of great concern for today’s world. There are various factors which are responsible for this conundrum. These are overpopulation, natural disaster, poverty, illiteracy, lack of employment opportunities, for a better life etc. Thus, irregular migration has been a livelihood strategy for the millions of people worldwide for the long time. Bangladesh is one of the top countries of the world in terms of sending labor migrants. Every year thousands of Bangladeshis are migrating overseas either legally or by illegal means for a better livelihood. However, in the last couple of years, total remittance flow was not satisfactory because of the diplomatic tension between Bangladesh and major migrants receiving countries. In addition, the new migrations policies of the Middle-Eastern countries which is the main destination points for Bangladeshi migrants in terms of single regions also have shrunk the scope. As a result, the number of irregular migrations from Bangladesh to Malaysia has increased. This paper attempts to unveil the key causes of irregular migration through the risky Bay of Bengal and the Andaman Sea by analysing the field data. It will focus on the case studies of the trafficking victims and their family members with focusing on why they took this dangerous path of irregular migration. It also argues for an effective mechanism to monitor the whole process of irregular migration from Bangladesh to Malaysia on an urgent basis.
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Schneeweiss, Hermann. « Exit Taxation after Cartesio : The European Fundamental Freedom’s Impact on Taxing Migrating Companies ». Intertax 37, Issue 6/7 (1 juin 2009) : 363–74. http://dx.doi.org/10.54648/taxi2009038.
Texte intégralRésumé :
At first sight, the European Court of Justice (ECJ)’s judgment in Cartesio looks like a victory for the European Union Member States collecting exit taxes from migrating companies. A closer look reveals that Cartesio is applicable only to a small portion of possible migration scenarios. As a result, exit taxation of the majority of company migration scenarios is likely to infringe the European fundamental freedoms. The author arrives at this conclusion by analyzing the ECJ’s case law on exit taxation of individuals, elaborating on its correlation with Daily Mail and Cartesio, and applying the deducted principles to different scenarios of company migrations.
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Shapiro-Phim, Toni. « Cambodia's Seasons of Migration ». Dance Research Journal 40, no 2 (2008) : 56–73. http://dx.doi.org/10.1017/s0149767700000383.
Texte intégralRésumé :
In classical Khmer dance dramas, the fluidity of gestural and choreographic movement is complemented by the seamlessness with which mythical figures move between the realms of sky, earth, and sea. Such mythical migrations have been the subject of Khmer dance dramas for centuries. In this essay I explore the recent development and performance of one specific danced story of migration and the performers' social realities that complicate their relationship to their art and to this story in particular. I discuss transnational migration's impact on current and future possibilities for Khmer classical dance, and the lessons Cambodia's female dancers take from the fluidity, adaptability, and flexibility required of Khmer choreography as they negotiate their immediate social, cultural, and political upheavals.
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Young, Jeffery L., Scott G. Hinch, Steven J. Cooke, Glenn T. Crossin, David A. Patterson, Anthony P. Farrell, Glen Van Der Kraak et al. « Physiological and energetic correlates of en route mortality for abnormally early migrating adult sockeye salmon (Oncorhynchus nerka) in the Thompson River, British Columbia ». Canadian Journal of Fisheries and Aquatic Sciences 63, no 5 (1 mai 2006) : 1067–77. http://dx.doi.org/10.1139/f06-014.
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Since 1995, large segments of the late-run sockeye salmon (Oncorhynchus nerka) stock complex from the Fraser River, British Columbia, Canada, have been initiating spawning migrations several weeks earlier than normal. Most aberrant migrants die before spawning. To evaluate the mechanisms underlying the mortality, we intercepted late-run sockeye salmon of the AdamsShuswap stock complex halfway along their freshwater migration (i.e., in the Thompson River Canyon situated 270 km from the Fraser estuary), nonlethally assessed physiological and energetic status, and tracked individuals using gastrically inserted radio transmitters. Aberrant migrants that resumed their migration but failed to reach the spawning grounds had lower gross somatic energy, higher average migration ground speeds, higher plasma osmolality, and higher levels of plasma reproductive hormones than those that reached the spawning grounds. Fish surgically fitted with electromyogram radio transmitters did not continue their migration and fell downstream. These fish displayed excessive bleeding during transmitter implantation, an unusual phenomenon that likely contributed to the fish's inability to resume migration. Blood clotting time decreased steadily throughout the migration period. Collectively, these data implicate a combination of energy depletion, premature reproductive development, and blood loss from wounds as potential contributors to mortality in early migrating late-run sockeye.
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Khadka, Rajendra. « City Centric Migration and Security Concern in Nepal ». Journal of APF Command and Staff College 2, no 1 (16 décembre 2019) : 89–96. http://dx.doi.org/10.3126/japfcsc.v2i1.26748.
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This article tends to focus on the trend of internal migration and its security concern in Nepal. There are different social and security concerns of migration which are not taken seriously. The repercussion might be in different fields and effects can be seen after short or long epoch. Migration and its linkage with the security are varied. It is the subject of interest for people who want to develop and make their birth land, village or cities prosperous. Current tendency of migration in Nepal indicates that the extensive outmigration of people to foreign countries is either for job or to study. Effects on migrants and communities they leave, rural to urban migration, differ according to the type of migrants, the volume of migration, and the nature of the places involved. The volume is increasing in recent days that people are migrating from rural to urban part of country even in district level. Migrants leaving rural areas are not generally replaced by other migrants. This loss of population in the rural areas and their potential contributions affects the dependency ratio, rates of unemployment and underemployment, levels of human capital, and potential for innovation. This article examines the pattern of migration and also it tries to explore the push and pull factors of migration. The security concerns of migrationऽ which involves different forms like human security, physical security, environmental security etc are analyzed in this article.
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SURINA, Iryna. « Youth migration in the context of overall European migration ». Scientific Papers of Silesian University of Technology. Organization and Management Series 2019, no 134 (2019) : 267–83. http://dx.doi.org/10.29119/1641-3466.2019.134.21.
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Adavally, Shashank, Mahzabeen Islam et Krishna Kavi. « Dynamically Adapting Page Migration Policies Based on Applications’ Memory Access Behaviors ». ACM Journal on Emerging Technologies in Computing Systems 17, no 2 (avril 2021) : 1–24. http://dx.doi.org/10.1145/3444750.
Texte intégralRésumé :
There have been numerous studies on heterogeneous memory systems comprised of faster DRAM (e.g., 3D stacked HBM or HMC) and slower non-volatile memories (e.g., PCM, STT-RAM). However, most of these studies focused on static policies for managing data placement and migration among the different memory devices. These policies are based on the average behavior across a range of applications. Results show that these techniques do not always result in higher performance when compared to systems that do not migrate data across the devices: some applications show performance gains, but other applications show performance losses. It is possible to utilize offline analyses to identify which applications benefit from page migration (migration friendly) and use page migration only with those applications. However, we observed that several applications exhibit both migration friendly and migration unfriendly behaviors during different phases of execution supporting a need for adaptive page migration techniques. We introduce and evaluate techniques that dynamically adapt to the behavior of applications and either reduce or increase migrations, or even halt migrations. Our adaptive techniques show performance gains for both migration friendly (on average of 81% over no migrations) and unfriendly workloads (by an average of 3%): it should be remembered that previous migration techniques resulted in performance losses for unfriendly workloads.
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Tian, Pengxin, Guannan Si, Zhaoliang An, Jianxin Li et Fengyu Zhou. « Service Migration Strategy Based on Multi-Attribute MDP in Mobile Edge Computing ». Electronics 11, no 24 (7 décembre 2022) : 4070. http://dx.doi.org/10.3390/electronics11244070.
Texte intégralRésumé :
In order to solve the problem of service interruption caused by user movement and the limited service range of edge nodes, a service migration algorithm based on the multi-attribute Markov decision process was proposed for mobile edge computing. By performing service migration, the distance between the user and the service is always kept to a small range. In addition, in order to prevent the service quality from being affected by the frequent migration of users, the return function of the model was defined by comprehensively considering the service quality, the resource demand of the service, the migration cost, and the movement income of users in each node, and on the premise of taking into account the migration cost and resource conditions, which did not only make up the deficiency of the service migration scheme based solely on distance. The number of migrations is also reduced, and a single migration target server is no longer used. The candidate server set was constructed based on the user’s motion trajectory, and the Q-Learning algorithm was used to solve the problem. Simulation results show that the proposed algorithm can reduce the number of migrations and ensure the balance between the number of migrations and the cost of migrations.
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Kostrzewa, Zofia, Lucyna Nowak, Dorota Szałtys et Janusz Witkowski. « Kierunki doskonalenia statystyki migracji zagranicznych ludności ». Wiadomości Statystyczne. The Polish Statistician 2010, no 5 (28 mai 2010) : 1–25. http://dx.doi.org/10.59139/ws.2010.05.1.
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Main improvements of external migration statistics in EU are presented in the article. On the base of papers presented during the 95th DGINS Conference, experiences of some EU-countries as well as their activities to improve the statistical data quality concerning external migrations are discussed. The statistical system of external migrations in Poland is presented in this context. These very statistics should deliver both data on streams and migration resources. Polish migration statistics use three types of data sources as follows: the administrative system, statistical surveys, foreign data sources. An estimation methodology of migration sizes is an important factor. Some activities, i.e. a spectrum extension of existing as well as a search for new data sources and improvement of current surveys as well as developing international cooperation and wider using results of scientific researches, and intensification of cooperation with government administration as well as units using information on migrations or responsible for migration politics, were implemented to improve the Polish statistical system of external migrations.
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Ordeix, Marc, et Frederic Casals. « Why and when do freshwater fish migrate ? Observations of migration patterns of the native fishes from the Iberian Peninsula (SW Europe) ». Limnetica 43, no 1 (21 mars 2024) : 1. http://dx.doi.org/10.23818/limn.43.02.
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We reviewed information on Iberian freshwater fish to characterize their migratory status and identify migration reasons and periods. Most species migrate (87.3 %; 62 species from 15 families). A large number are potamodromous species (45 species from 6 families) but diadromous species (17 species from 11 families) also exist, including anadromous (9 species) and cata¬dromous (8 species). The spawning period is a primary driver of fish migration but feeding and refuge-associated migrations also take place. Sexual maturity is the most important cue triggering fish migration, and other important factors include water temperature, river flow, currents, salinity and photoperiod. Spawning and migrating periods are in general prolonged and vary among years, as a response to the environmental variability of Mediterranean river systems, which are the most frequent in the Iberian Peninsula. Migratory movements of the various native species of each site cover almost the whole or the whole year. Therefore, to allow fish migration, Iberian freshwaters should always be connected, or their fish passes should be permanently, or practically always, in operation.
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Rahman, Momotazur, Bishnu Bahadur Thapa, Christopher Santostefano, Pedro Gozalo, Ulrike Muench, Cyrus M. Kosar, Hyesung Oh, Elizabeth White et Vincent Mor. « Patterns of Migration Following Dementia Diagnosis ». JAMA Network Open 7, no 10 (14 octobre 2024) : e2439499. http://dx.doi.org/10.1001/jamanetworkopen.2024.39499.
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ImportanceDiseases have historically prompted individual relocations to mitigate the risk of disease acquisition or improve access to care. As dementia prevalence increases, comprehending the migration patterns of affected individuals is vital for public policy.ObjectiveTo quantify the association of dementia diagnosis with migration patterns by examining the proportion of individuals with dementia who relocate, the timing of their moves relative to diagnosis, and the nature of their new living arrangements, whether in institutional settings or different households.Design, Setting, and ParticipantsThis cohort study leveraged a comprehensive dataset of national Medicare claims and assessments spanning from 2012 to 2020, including Medicare Beneficiary Summary File and nursing home administrative datasets. The study focused on beneficiaries who received diagnoses in 2016 of dementia, myocardial infarction, chronic obstructive pulmonary disease, or colon cancer. Analyses were performed from March 2023 to August 2024.Main Outcomes and MeasuresThe primary outcome was migration, defined as change in county or state. The analysis distinguished between migrations with and without a nursing home stay. By tracking patients’ residential county for 4 years before and after diagnosis, a difference-in-differences approach was used to contrast migration tendencies associated with dementia against the other 3 conditions.ResultsThe sample included 1 626 127 Medicare beneficiaries (mean [SD] age, 80.1 [8.0] years; 922 194 women [56.7%]) who received diagnoses of the 4 conditions in 2016. In total, 818 862 had a new dementia diagnosis (age, 82.0 [7.8] years; 492 146 women [60.1%]). Comparing between the prediagnosis and postdiagnosis months, the proportion migrating to a different county increased by 8.5 percentage points (95% CI, 7.6-9.4 percentage points) for individuals with dementia and between 4.2 to 5.8 percentage points among those with myocardial infarction, chronic obstructive pulmonary disease, or colon cancer. The difference-in-difference estimates indicated a 3.9 percentage point (95% CI, 3.7-4.0 percentage points) increase in intercounty migration and a 1.9 percentage point (95% CI, 1.8-2.0 percentage points) increase in interstate migration for patients with dementia, effectively doubling the likelihood of migration compared with the other conditions. Of the excess migrations resulting from dementia diagnosis, 55% occurred in community settings, and 45% occurred in institutional settings.Conclusions and RelevanceIn this retrospective cohort study of Medicare fee-for-service beneficiaries, dementia was associated with a marked increase in migration rates over other major illnesses. This finding underscores the need to understand the factors associated with these distinct migration behaviors.
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Deryugina, E. I., et M. A. Bourdon. « Tenascin mediates human glioma cell migration and modulates cell migration on fibronectin ». Journal of Cell Science 109, no 3 (1 mars 1996) : 643–52. http://dx.doi.org/10.1242/jcs.109.3.643.
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The role of tenascin in mediating tumor cell migration was studied using two cell migration models. In migration/invasion Transwell assays U251.3 glioma cells rapidly migrated through the 8 mu m pore size membranes onto tenascin- and fibronectin-coated surfaces. In this assay the number of cells migrating onto tenascin was 52.2 +/- 9.6% greater than on fibronectin within 4 hours. To assess cell migration rates and cell morphology, U251.3 migration was examined in a two-dimension spheroid outgrowth assay. The radial distance migrated by U251.3 cells from tumor spheroids was found to be 53.8 +/- 4.9% greater on tenascin than on fibronectin. Cells migrating on tenascin display a very motile appearance, while cells migrating on fibronectin spread and maintain close intercellular contacts. Cell migration in the presence of integrin blocking antibodies demonstrated that migration on tenascin and fibronectin is mediated by distinct integrins, alpha2beta1 and alphavbeta5/alphavbeta3, respectively. Since tenascin is coexpressed in malignant tumor matrices with fibronectin, we assessed the effects of tenascin on U251.3 cell migration mediated by fibronectin. Tenascin was found to provide a positive effect on fibronectin-mediated migration by altering cell morphology and enhancing cell motility. These effects of tenascin on fibronectin-mediated cell migration were inhibited by blocking beta1 and alpha2beta1 integrins. The results suggest that tenascin may play a significant role in promoting tumor cell migration and invasiveness by modulating cell responses to normal matrix components.
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Feng, Shiqian, Shuai Shi, Farman Ullah, Xueyan Zhang, Yiting Yin, Shuang Li, John Huria Nderitu et al. « Intercontinental Migration Facilitates Continuous Occurrence of the Desert Locust Schistocerca gregaria (Forsk., 1775) in Africa and Asia ». Agronomy 14, no 7 (18 juillet 2024) : 1567. http://dx.doi.org/10.3390/agronomy14071567.
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The desert locust, Schistocerca gregaria (Forsk., 1775), stands as one of the most pervasive pests globally, inflicting extensive damage across Asia and Africa. Facilitated by intercontinental migration, the desert locust engages in population exchange between different source areas, perpetuating its widespread proliferation. Despite the wind being recognized as a key factor during migration events, elucidating its precise influence on intercontinental migration has remained elusive. In this study, we scrutinized monitoring data sourced from the FAO monitoring system, pinpointing 13 desert locust events featuring intercontinental migrations since 1967. From these events, four migration routes were summarized, traversing the Red Sea (RS-WE and RS-EW) and the northern Indian Ocean (IO-WE and IO-EW). Typically, RS-WE and IO-EW migrations occurred between December and March, whereas RS-EW and IO-WE migrations were observed from May to June and April to July, respectively. Our examination of wind field data spanning the past 15 years revealed that wind direction and speed facilitated intercontinental migrations. Furthermore, migration trajectory modeling indicated that desert locusts might exhibit migratory behavior both during the day and at night in the cases of RS-WE and RS-EW, with cross-oceanic migration potentially lasting for a week for IO-WE and IO-EW. In summary, our study identifies four migration routes for the intercontinental migration of the desert locust, providing crucial support for the scientific prediction of its occurrence and contributing to international food security efforts.
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Ma, Z., K.-L. Liaw et Y. Zeng. « Migrations in the Urban—Rural Hierarchy of China : Insights from the Microdata of the 1987 National Survey ». Environment and Planning A : Economy and Space 29, no 4 (avril 1997) : 707–30. http://dx.doi.org/10.1068/a290707.
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After presenting a brief account of the societal context of China, the authors use the microdata of the 1987 National Population Survey to study the migration behaviors of Chinese people in the mid-1980s. The authors' main concern is with the effects of the government migration policy, and the focus is on the migrations in the city/town/rural hierarchy. There are two main findings. First, although the migration policy resulted in a very low migration level and systematic distortions in migration schedules, its encouragement of downward migrations was very ineffective, whereas its control on rural-to-urban migrations was partially weakened by the strong upward aspiration of rural families awakened by recent economic reform. Consequently, net in-migration contributed substantially to the growth both of city and of town populations. Second, although the level of education had a strong positive effect on the migration propensities both of males and of females in general, it had a strong negative effect on the migration propensities of females at the time of marriage, a finding which suggests that the families at subsistence income level tended to marry their daughters to grooms in other communities in order to reduce the risk of familial income shortfalls.
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Lysenko, Alexander, et Igor Kononenko. « SPECIFICS AND COMPLEXITY OF THIRD-PARTY LIBRARY MIGRATIONS IN IT-PROJECTS ». Bulletin of NTU "KhPI". Series : Strategic management, portfolio, program and project management, no 1(8) (23 juin 2024) : 26–32. http://dx.doi.org/10.20998/2413-3000.2024.8.4.
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An analysis has been conducted on the relevance of the problem of migrating third-party tools in IT projects, which is characterized by regularity and presents challenges for developers in terms of decision-making. The analysis shows that the migration of third-party tools requires developers not only to have technical knowledge and skills but also a deep understanding of migration management strategies, risk assessment methods, and the ability to integrate new tools into existing projects without negatively impacting the workflow. The necessity of migrating third-party tools in the IT field, which is a crucial aspect for ensuring the relevance, efficiency, and innovation of software in a rapidly changing technological landscape, is directly considered. Main attention is given to the review of modern research and methodologies aimed at simplifying the process of tool migration, reducing development and support costs, and enhancing software security. Proposals regarding comprehensive approaches to managing migrations are considered, including the use of automated systems for analyzing large volumes of data about the history of changes in projects, risk assessment, and effective communication among all project participants. The justification for the significance of migrating third-party tools to ensure the sustainable development of software in a dynamically changing technological environment is discussed. The need for further research in this field is highlighted, aimed at developing new tools and methodologies to optimize the migration process, with the goal of enhancing developer productivity and ensuring the high quality of final software products. The importance of a systematic and comprehensive approach to migrating third-party tools, based on detailed data analysis, a deep understanding of risks, effective communication, and the application of modern technological solutions, is emphasized.
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McKeown, Adam. « Regionalizing World Migration ». International Review of Social History 52, no 1 (9 mars 2007) : 134–42. http://dx.doi.org/10.1017/s0020859006002859.
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An insistence on the broad similarities and structural linkages of migrations across the globe since the 1840s is important because it can clear the ground for more effective comparisons. Only after questioning the a priori distinction that privileges “modern” transatlantic migrations as categorically distinct from those in the rest of the world can we begin to understand each migrant and migrant flow as emerging from a distinct nexus of global, regional, local, and historical processes. I think I am in agreement with all of the participants in this forum on this basic point. Rather than quibble over numbers and definitions, all of the contributions have attempted to refine our historical comparisons and question some of the interpretive frameworks that are rooted in depictions of the Atlantic migrations as a norm. Once this global foundation is established, we can engage in the detailed empirical and conceptual work that will better address the sticky problems of numbers and categories. Who and what is actually being counted and not counted? When and why should we distinguish between long and short distance, or between international and domestic migration? How should we deal with return and repeat migrations? What is revealed or obscured by taking individuals, families or more extended networks as the basic units of migration? What is the practical or discursive significance of “free” migration?
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Tyagi, Tushar, et Sanjay Kumar Bhardwaj. « Magnetic Compass Orientation in a Palaearctic–Indian Night Migrant, the Red-Headed Bunting ». Animals 11, no 6 (25 mai 2021) : 1541. http://dx.doi.org/10.3390/ani11061541.
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Red-headed buntings (Emberiza bruniceps) perform long-distance migrations within their southerly overwintering grounds and breeding areas in the northern hemisphere. Long-distance migration demands essential orientation mechanisms. The earth’s magnetic field, celestial cues, and memorization of geographical cues en route provide birds with compass knowledge during migration. Birds were tested during spring migration for orientation under natural clear skies, simulated overcast skies at natural day length and temperature, simulated overcast at 22 °C and 38 °C temperatures, and in the deflected (−120°) magnetic field. Under clear skies, the red-headed buntings were oriented NNW (north–northwest); simulated overcast testing resulted in a northerly mean direction at local temperatures as well as at 22 °C and 38 °C. The buntings reacted strongly in favor of the rotated magnetic field under the simulated overcast sky, demonstrating the use of a magnetic compass for migrating in a specific direction.
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Hidayati, Inayah. « The Process of Migration and Communication Technology Roles among Labor Migrants in Batam - Indonesia ». Society 7, no 2 (31 décembre 2019) : 173–84. http://dx.doi.org/10.33019/society.v7i2.99.
Texte intégralRésumé :
This research explains the roles of communication technology on the migration process of labor migrants in Batam, Indonesia. Differences between places are strong reasons for people to migrate. The advances in communication technology have freed up opportunities for people to migrate. Technology has made it more accessible for migrants to raise links to their next destination through the internet. Interactions within communication technology make migration easier by decreasing the expenses and risks of moving. The explanations in this study are to understand the communication technology for the migrating process and calculate the social networks of migrants. This research applied mixed methods to explore the migration process with data collected included quantitative data from a survey with 500 respondents and supported by qualitative data from in-depth interviews. The results: 1) Communication technology helps migrants in the migration process, especially for searching for information about the destination area. 2) The migrant who uses communication technology has a strong social network and less risk of migration. The role of communication technology in the migration's processes is as a tool to maintain social ties of migrants, migrant uses their social media to make contact and gain information about their destination. This study related to SDGs' target number 10.7 which facilitates orderly, safe, regular and responsible migration and mobility of people, including through the implementation of planned and well-managed migration policies, communications technology facilitate safe and well-managed migration.
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Jha, Chandan Kumar, Vijaya Gupta, Utpal Chattopadhyay et Binilkumar Amarayil Sreeraman. « Migration as adaptation strategy to cope with climate change ». International Journal of Climate Change Strategies and Management 10, no 1 (8 janvier 2018) : 121–41. http://dx.doi.org/10.1108/ijccsm-03-2017-0059.
Texte intégralRésumé :
Purpose This study aims to evaluate the link between climate/weather change and farmer migration in Bihar, India. The influence of cognitive conditions and climate-related stress on farmer migration decisions and the socioeconomic characteristics of migrating and non-migrating farm households are analysed. The focus is the role of migration in access to climate and agricultural extension services and the contribution of migration to enhanced farmer coping capacity. Design/methodology/approach A primary survey was conducted of farm households in seven districts of Bihar, India. Farmer perceptions of climate change were analysed using the mental map technique. The role of socioeconomic characteristics in farm household migration was evaluated using binary logistic regression, and the influence of migration on access to climate and agricultural extension services and the adaptive capacity of migrating households was investigated using descriptive statistics. Findings Climate-induced livelihood risk factors are one of the major drivers of farmer’s migration. The farmers’ perception on climate change influences migration along with the socioeconomic characteristics. There is a significant difference between migrating and non-migrating farm households in the utilization of instructions, knowledge and technology based climate and agriculture extension services. Benefits from receipt of remittance, knowledge and social networks from the host region enhances migrating households’ adaptive capacity. Originality/value This study provides micro-evidence of the contribution of migration to farmer adaptive capacity and access to climate and agricultural extension services, which will benefit analyses of climate-induced migration in other developing countries with higher agricultural dependence. In addition, valuable insights are delivered on policy requirements to reduce farmer vulnerability to climate change.
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Dong, Zejun, Xuan Feng, Haoqiu Zhou, Lilong Zou et Motoyuki Sato. « 3D Migration Depth Focus Velocity Analysis of Hand-Held Ground Penetrating Radar ». Geosciences 12, no 4 (16 avril 2022) : 178. http://dx.doi.org/10.3390/geosciences12040178.
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Hand-held ground penetrating radar (GPR) systems have been widely applied to landmine detections during recent decades. The accuracy of an imaging result by migration for a hand-held GPR is strongly related to the accuracy of subsurface velocity distribution obtained from multi offset data. For shallow targets like landmines, the hyperbolas are usually not distinct in 2D slices and are masked by the surface reflections. In this article, we propose a 3D migration depth focus velocity analysis method for hand-held GPRs to estimate the background velocity of the subsurface. This method is performed based on the images generated by migrations. The objective function is defined as the proportion of the target on the depth slice containing the target. After migrating a GPR radargram with different velocities, the background velocity, which minimizes the objective function, can be determined by comparing the imaging results by migration using different velocities. To test the proposed method, we apply this procedure to experimental GPR data collected with an advanced landmine imaging system (ALIS) in the laboratory. Subsequently, the velocity of the background is obtained, 3D diffraction migration with the obtained velocity achieves subsurface imaging with high quality. The accurate position and depth of the target are obtained from the optimal migration image.
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Maida, Jared R., Christine A. Bishop et Karl W. Larsen. « Migration and disturbance : impact of fencing and development on Western Rattlesnake (Crotalus oreganus) spring movements in British Columbia ». Canadian Journal of Zoology 98, no 1 (janvier 2020) : 1–12. http://dx.doi.org/10.1139/cjz-2019-0110.
Texte intégralRésumé :
Due to increasing anthropogenic pressures, including land-use transformation globally, the natural process of animal migration is undergoing alterations across many taxa. Small-scale migrants provide useful systems at workable scales for investigating the influence of disturbance and landscape barriers on natural movement patterns and migrations. The Western Rattlesnake (Crotalus oreganus Holbrook, 1840) in British Columbia, Canada, is a small, migrant predator that undertakes seasonal spring movements from its communal hibernaculum to summer hunting and mating grounds and reverses its movements in autumn. From 2011 to 2016, we examined changes to spring migration movements in 27 male Western Rattlesnakes encountering both mitigative fencing barriers and disturbed habitats. Individuals moving through disturbed habitats or intercepted by mitigative fencing demonstrated shorter migration distances and reduced spring path sinuosity compared with individuals migrating in undisturbed habitats. Specifically, individuals encountering a fence during spring movements completed shorter total spring migration path lengths and occupied smaller home ranges over the course of the entire active season. Total spring migration distance also was strongly associated with the distance that individuals traveled until they first encountered human disturbance. This study contributes significantly to our knowledge of how fencing barriers may impact normal behavioural patterns in smaller vertebrates.
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Islam, Mohayeminul, Ajay Kumar Jha, Ildar Akhmetov et Sarah Nadi. « Characterizing Python Library Migrations ». Proceedings of the ACM on Software Engineering 1, FSE (12 juillet 2024) : 92–114. http://dx.doi.org/10.1145/3643731.
Texte intégralRésumé :
Developers heavily rely on Application Programming Interfaces (APIs) from libraries to build their software. As software evolves, developers may need to replace the used libraries with alternate libraries, a process known as library migration. Doing this manually can be tedious, time-consuming, and prone to errors. Automated migration techniques can help alleviate some of this burden. However, designing effective automated migration techniques requires understanding the types of code changes required to transform client code that used the old library to the new library. This paper contributes an empirical study that provides a holistic view of Python library migrations, both in terms of the code changes required in a migration and the typical development effort involved. We manually label 3,096 migration-related code changes in 335 Python library migrations from 311 client repositories spanning 141 library pairs from 35 domains. Based on our labeled data, we derive a taxonomy for describing migration-related code changes, PyMigTax. Leveraging PyMigTax and our labeled data, we investigate various characteristics of Python library migrations, such as the types of program elements and properties of API mappings, the combinations of types of migration-related code changes in a migration, and the typical development effort required for a migration. Our findings highlight various potential shortcomings of current library migration tools. For example, we find that 40% of library pairs have API mappings that involve non-function program elements, while most library migration techniques typically assume that function calls from the source library will map into (one or more) function calls from the target library. As an approximation for the development effort involved, we find that, on average, a developer needs to learn about 4 APIs and 2 API mappings to perform a migration and change 8 lines of code. However, we also found cases of migrations that involve up to 43 unique APIs, 22 API mappings, and 758 lines of code, making them harder to manually implement. Overall, our contributions provide the necessary knowledge and foundations for developing automated Python library migration techniques. We make all data and scripts related to this study publicly available at https://doi.org/10.6084/m9.figshare.24216858.v2.