Migratory Chains Research Articles

An Empirical Investigation on the Determinants of International Migration

Abstract Are differences in per capita income between countries really the main cause of migratory flows? Mainstream economic thinking would give an affirmative answer. In the light of the heterodox literature, in this article, the authors critically evaluate this view and then they conduct an empirical test (applying panel and dynamic panel models) on data relating to the stocks of migrants on 232 countries from 1990 to 2019, trying to explain migration trends based on social-political, cultural, demographic and economic variables (obtained by integrating 4 official datasets). The results reveal a non-unique influence of differences in per capita income on migratory flows: up to a certain threshold (around $27,000) migration appears to be directly related to per capita GDP of migrants’ country of origin. Furthermore, the pre-existing stock of migrants in the country of destination takes on an important role, in line with the findings of the literature on migratory chains. These empirical findings could contribute to improve migration policies.

Doublecortin-Expressing Neurons in Human Cerebral Cortex Layer II and Amygdala from Infancy to 100 Years Old.

A cohort of morphologically heterogenous doublecortin immunoreactive (DCX +) "immature neurons" has been identified in the cerebral cortex largely around layer II and the amygdala largely in the paralaminar nucleus (PLN) among various mammals. To gain a wide spatiotemporal view on these neurons in humans, we examined layer II and amygdalar DCX + neurons in the brains of infants to 100-year-old individuals. Layer II DCX + neurons occurred throughout the cerebrum in the infants/toddlers, mainly in the temporal lobe in the adolescents and adults, and only in the temporal cortex surrounding the amygdala in the elderly. Amygdalar DCX + neurons occurred in all age groups, localized primarily to the PLN, and reduced in number with age. The small-sized DCX + neurons were unipolar or bipolar, and formed migratory chains extending tangentially, obliquely, and inwardly in layers I-III in the cortex, and from the PLN to other nuclei in the amygdala. Morphologically mature-looking neurons had a relatively larger soma and weaker DCX reactivity. In contrast to the above, DCX + neurons in the hippocampal dentate gyrus were only detected in the infant cases in parallelly processed cerebral sections. The present study reveals a broader regional distribution of the cortical layer II DCX + neurons than previously documented in human cerebrum, especially during childhood and adolescence, while both layer II and amygdalar DCX + neurons persist in the temporal lobe lifelong. Layer II and amygdalar DCX + neurons may serve as an essential immature neuronal system to support functional network plasticity in human cerebrum in an age/region-dependent manner.

The conditioning of social networking sites in the formation of migratory chains of unaccompanied foreign minors

The relational uprooting faced by young unaccompanied minors, when they undertake a migratory process, it places them in a situation of extreme vulnerability. Timeshare in the Center for Minors offered relationships between themselves, which are later maintained and reflected on social networking sites. The content that can be shared on social networking sites could condition the subsequent migratory itinerary travel and the migratory chains that are formed. In this study, the profiles on social networking sites of 51 unaccompanied minors were analyzed one year after having passed through a Center for Minors located in Malaga (Spain). Through social networks analysis, netnography and certain algorithms for community detection, cohesion and emotion analysis, the connectedness and interaction patterns shown by these young people on social networking sites (Facebook) will be analyzed, identifying leaderships and detecting communities that influence the formation of migratory chains. The results show how the patterns of connectedness, interaction and leadership reflect migratory chains.

Cadenas migratorias en la diáspora de las travestis/trans sudamericanas residentesdel Área Metropolitana de Buenos Aires

The article analyzes the migratory chains that constitute South American transvestites and trans women who reside in the Buenos Aires Metropolitan Area during the period 2017-2019, paying special attention to the role of godmothers. The migratory projects of these people are produced becauseof the hostility and vulnerability they experience in their surroundings and have different instances. One of them is the migratory chains that refer to the social capital necessary to be able to leave the sending society and settle in the receiving society. In this way, South American transvestites/trans women constitute diverse migratory chains that can be characterized as horizontal and vertical, being the godmothers key actors in their diasporas. The focus of the article is qualitative and the method used is grounded theory. According to a theoretical sample consisting of 41 interviews, the information was analyzed usingAtlas.Ti.

Characterization of the canine rostral ventricular-subventricular zone: Morphological, immunohistochemical, ultrastructural, and neurosphere assay studies.

The mammalian ventricular-subventricular zone (V-SVZ) presents the highest neurogenic potential in the brain of the adult individual. In rodents, it is mainly composed of chains of neuroblasts. In humans, it is organized in layers where neuroblasts do not form chains. The aim of this study is to describe the cytoarchitecture of canine V-SVZ (cV-SVZ), to assess its neurogenic potential, and to compare our results with those previously described in other species. We have studied by histology, immunohistochemistry (IHC), electron microscopy and neurosphere assay the morphology, cytoarchitecture and neurogenic potential of cV-SVZ. Age groups of animals were performed. Histological and ultrastructural studies indicated that the cV-SVZ is organized in layers as in humans, but including migratory chains as in rodents. Neural progenitors were organized in niches in the subependymal area and a decline in their number was observed with age. Adult-young dogs contained migratory cells capable to expand and differentiate in vitro according with previous results obtained in rodents, primates, humans, pigs, and dogs. Some adult animals presented perivascular niches outside the V-SVZ. Our observations evidence a great similarity between canine and human V-SVZ indicating that the dog may be better representative of neurogenic events in humans, compared with rodents. Accordingly with our results, we conclude that dogs are a valuable animal model of adult neurogenesis in comparative and preclinical studies.

A PRESENÇA DOS MIGRANTES HAITIANOS EM TERRITÓRIO MARINGAENSE

O acordo entre Brasil e Haiti, concedendo vistos humanitários, trouxe para o Brasil uma nova corrente migratória. Assim, em 2010, chegaram os primeiros haitianos no município de Maringá e arredores, no Paraná. Esse fluxo abriu caminhos para outros grupos migratórios como os dominicanos, os senegaleses e os bengaleses. Em 2014, já eram 4 mil haitianos residindo na Região Metropolitana de Maringá. No ano de 2016, com a mudança econômica local e nacional, parte expressiva dos haitianos de Maringá migraram principalmente para o Chile. Esses homens foram mobilizados para trabalhar, sobretudo, nos frigoríficos da região, e em menor participação, em outras indústrias de grande porte, além do setor de comércio e serviços. Nosso propósito, neste texto, é discutir a presença dos migrantes haitianos na região metropolitana de Maringá, suas formas de inserção, e os obstáculos por eles encontrados, identificando as barreiras para sua integração na sociedade. Nesse quadro de mobilidade humana, apoiamo-nos em Jean Paul Gaudemar (1977), que estudou a produção e a circulação da força de trabalho; com o respaldo de Marx e Foucault, esse autor traça um paralelo do poder nas microesferas e o domínio do capital sobre os homens.

Ancient animal migration: a case study of eyeless, dimorphic Devonian trilobites from Poland

AbstractWe report evidence of one of the oldest known animal migratory episodes in the form of queues of the eyeless trilobite Trimerocephalus chopini Kin & Błażejowski, from the Late Devonian (Famennian) of central Poland. In addition, there is evidence for two morphs in this population, one with nine segments and the other with ten. We infer that these queues represent mass migratory chains coordinated by chemotaxis, comparable to those observed in modern crustaceans such as spiny lobsters, and further suggest that the two forms, which occur in an approximately 1:1 ratio, may be dimorphs. These ancient arthropods may have migrated periodically to shallow marine areas for mass mating and spawning. The sudden death of the trilobites in the queues may have been caused by excess carbon dioxide and hydrogen sulphide introduced into the bottom water by distal storm disturbance of anoxic sediments. This study demonstrates the potential for further research on the evolution and ecology of aggregative behaviour in marine arthropods.

Early farmers from across Europe directly descended from Neolithic Aegeans

Farming and sedentism first appeared in southwestern Asia during the early Holocene and later spread to neighboring regions, including Europe, along multiple dispersal routes. Conspicuous uncertainties remain about the relative roles of migration, cultural diffusion, and admixture with local foragers in the early Neolithization of Europe. Here we present paleogenomic data for five Neolithic individuals from northern Greece and northwestern Turkey spanning the time and region of the earliest spread of farming into Europe. We use a novel approach to recalibrate raw reads and call genotypes from ancient DNA and observe striking genetic similarity both among Aegean early farmers and with those from across Europe. Our study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia.

The Patterns and Impacts of Turkish Immigration to the European Union

Since the early 1960s, Turkish nationals have immigrated to the European Union in large numbers. Germany, the Netherlands, and Belgium have the highest Turkish populations in the European Union and have managed differing models of incorporation. A number of motivating factors have contributed to the unflagging numbers of Turks such as the implementation of guest-worker programs, the reunification of families, and microstructures within migratory chains. Though the likelihood of Turkey gaining membership to the European Union has dimmed as of late, the mere possibility of its joining warrants the analysis of Turkish immigration to the EU, as it could shed light on the social and economic changes that could occur with Turkish membership to the EU. This analytical paper will detail the impacts of the varying methods of incorporation employed by the receiving countries and examine the historical patterns and impacts of Turkish immigration in the European Union.

Los frutos de la movilidad. La emigración norteña peninsular en Madrid y el Imperio (siglos XVII y XVIII)

El Setecientos verá el impacto popular e histórico de los intensos procesos migratorios de jóvenes provincianos norteños en busca de futuro. Todos hidalgos norteños que protegían su idiosincrasia jurídica junto a los intereses de las autoridades de sus lugares de origen. Muchos de ellos sin ayuda de cadenas migratorias o viejas redes clientelares. Madrid, Cádiz o México vieron surgir centros de ayuda al emigrante por criterios de origen o naturaleza. Hospitales, cofradías o congregaciones fueron los tres prototipos asociativos de esta corriente migratoria norteña. Tal movilidad y el surgir de estas “comunidades emocionales” (en los centros políticos, culturales, administrativos y económicos del Imperio español) se concentra en tiempos de Felipe V y Fernando VI. Estas agencias de colocación y espacios de representación cultural y política muestran la organización conferida por las autoridades del norte de España para resolver algunos peligros derivados de los procesos migratorios de sus jóvenes.http://dx.doi.org/10.15304/ohm.24.2708

Family, Social Capital and Internal Migration in Italy: The Case of the People of Tramonti

Abstract Beginning with an outline of internal migration in Italy between the 1950s and the 1970s, the article aims to articulate a critical reflection on the role played by social capital in the development of Italian small firms. These issues are explored through an ethno-historical analysis of the experiences of a group of migrants from Tramonti, a little town in Southern Italy, whose success in the restaurant business provides the case study at the core of the paper. Since the 1950s, thousands of people have moved from Tramonti to Northern Italy, and many of them have joined the business of pizza restaurants. Although migration from this little town is just a small part of the substantial internal migration which took place in Italy in the second half of the 20th century, this case study allows us to explore some interesting questions pertaining to the study of both migration and small firms. After providing a brief historical description of the migration from Tramonti, the article attempts to explain and understand the success of this group of migrants by focusing on the key factor represented by social capital, while also offering a critical approach to the concept of social capital itself. This historical analysis shows how migratory chains consisting of family, kin and community ties have been transformed into strong social capital of prime importance to the business strategies of the Tramonti pizza-makers. This particular social capital was marked by strong family ties and values and worked through a “segmentary” logic of solidarity and fission. Indeed, this “entrepreneurial familism” was the main factor behind the success of the pizza makers (pizzaioli). The case study suggests, then, that familism is not necessarily an obstacle to economic improvement; instead, it is an essential component of the social capital, it can propel business success if it operates within the right social-economic context, like that of Northern Italy between the 1950s and 1970s.

Emigración y actividad empresarial canaria en Cuba, 1850-1950

Los emprendedores canarios contribuyeron a la construcción del tejido empresarial cubano mediante la creación y desarrollo de una gran variedad de empresas: pequeños propietarios agrícolas del tabaco, comerciantes internacionales, titanes del sector financiero y propietarios de centrales azucareros; otros terminaron especializándose en pequeñas empresas de servicios urbanos como la distribución de leche. En este artículo se analizan, en primer lugar, las migraciones canarias en el contexto de las cadenas migratorias atlánticas; en segundo lugar, se exponen los aspectos más importantes del desarrollo empresarial protagonizado por los emigrantes isleños en Cuba.

Migration and the Search for a Better Way of Life: A Critical Exploration of Lifestyle Migration

For the past few years, the term ‘lifestyle migration’ has been used to refer to an increasing number of people who take the decision to migrate based on their belief that there is a more fulfilling way of life available to them elsewhere. Lifestyle migration is thus a growing, disparate phenomenon, with important but little understood implications for both societies and individuals. This article outlines and explores in detail a series of mobilities that have in common relative affluence and this search for a better lifestyle. We attempt to define the limits of the term lifestyle migration, the characteristics of the lifestyle sought, and the place of this form of migration in the contemporary world. In this manner, we map the various migrations that can be considered under this broad rubric, recognising the similarities and differences in their migration trajectories. Further to this, drawing on the sociological literature on lifestyle, we provide an initial theoretical conceptualisation of this phenomenon, attempting to explain its recent escalation in various guises, and investigating the historical, sociological, and individualised conditions that inspire this migration. This article is thus the first step in defining a broader programme for the study of lifestyle migration. We contend that the study of this migration is especially important in the current era given the impact such moves have on places and people at both ends of the migratory chain.

Doublecortin-expressing cells persist in the associate cerebral cortex and amygdala in aged nonhuman primates

A novel population of cells that express typical immature neuronal markers including doublecortin (DCX+) has been recently identified throughout the adult cerebral cortex of relatively large mammals (guinea pig, rabbit, cat, monkey and human). These cells are more common in the associative relative to primary cortical areas and appear to develop into interneurons including type II nitrinergic neurons. Here we further describe these cells in the cerebral cortex and amygdala, in comparison with DCX+ cells in the hippocampal dentate gyrus, in three age groups of rhesus monkeys: young adult (12.3 ± 0.2 years, n = 3), mid-age (21.2 ± 1.9 years, n = 3) and aged (31.3 ± 1.8 years, n = 4). DCX+ cells with a heterogeneous morphology persisted in layers II/III primarily over the associative cortex and amygdala in all groups (including in two old animals with cerebral amyloid pathology), showing a parallel decline in cell density with age across regions. In contrast to the cortex and amygdala, DCX+ cells in the subgranular zone diminished in the mid-age and aged groups. DCX+ cortical cells might arrange as long tangential migratory chains in the mid-age and aged animals, with apparently distorted cell clusters seen in the aged group. Cortical DCX+ cells colocalized commonly with polysialylated neural cell adhesion molecule and partially with neuron-specific nuclear protein and γ-aminobutyric acid, suggesting a potential differentiation of these cells into interneuron phenotype. These data suggest a life-long role for immature interneuron-like cells in the associative cerebral cortex and amygdala in nonhuman primates.

Glial Chain Migration Requires Pioneer Cells

The migration of glial chains along the nerve entails directional and coordinated movement. Despite its importance in the formation of the nervous system, this process remains poorly understood, because of the difficulty of manipulating identified cells. Using confocal time-lapse and cell ablation in the whole animal, we provide direct evidence for a discrete number of Drosophila peripheral glial cells acting as pioneers and guiding the rest of the migratory chain. These cells are in direct contact with several follower cells through a very long and stable cytoplasmic extension. The presence of pioneer cells and homotypic interactions at the tip of the chain allows coordinated movement and the formation of a continuous sheath around the nerve. These in vivo data open novel perspectives for understanding the cellular bases of vertebrate glial migration in physiological and pathological conditions.

Thrombospondin-1 binds to ApoER2 and VLDL receptor and functions in postnatal neuronal migration

Apolipoprotein E receptor 2 (ApoER2), very low-density lipoprotein receptor (VLDLR), and Dab1 are the main components of the Reelin signalling cascade. Reelin is the sole ligand defined so far in signalling through this pathway. Postnatal migration of neuronal precursors from the subventricular zone (SVZ) to the olfactory bulb (OB), however, depends on ApoER2 and Dab1, but functions independently of Reelin. Here, we show that thrombospondin-1 (THBS-1) is a novel physiological ligand for ApoER2 and VLDLR. THBS-1 is present in the SVZ and along the entire rostral migratory stream (RMS). It binds to ApoER2 and VLDLR and induces phosphorylation of Dab1. In contrast to Reelin, it does not induce Dab1 degradation or Akt phosphorylation, but stabilizes neuronal precursor chains derived from subventricular explants. Lack of THBS-1 results in anatomical abnormalities of the RMS and leads to a reduction of postnatal neuronal precursors entering the OB.

Impaired Migration in the Rostral Migratory Stream But Spared Olfactory Function after the Elimination of Programmed Cell Death in Bax Knock-Out Mice

Rats and mice exhibit neurogenesis of olfactory bulb (OB) interneurons throughout adulthood. To homeostatically maintain stable neuron numbers, it is necessary to continuously remove a subset of OB neurons by programmed cell death (PCD). Here we demonstrate that Bax is critical for the elimination of OB neurons by showing that Bax-KO mice exhibit greatly reduced PCD in the OB. Despite the reduction of PCD, however, proliferation of progenitors and the size of the OB were virtually unaffected in Bax-knock-out (KO) mice. However, reducing PCD by Bax deletion affected the migration of a subset of adult-produced neurons by the disruption of glial tube formation as well as by premature detachment of neuroblasts from the migratory chain. Rescued cells aberrantly remained in the subventricular zone (SVZ)-rostral migratory stream (RMS), in which they differentiated into calretinin+ or GABA-expressing interneurons. Because of the migratory deficit, OB cell homeostasis involving new cell entry and PCD (neuronal turnover) was virtually absent in adult Bax-KO mice. Despite this, Bax-KO mice exhibited normal olfactory behaviors such as odor discrimination and olfactory memory which are thought to be influenced by adult neurogenesis. These results demonstrate that PCD is involved in the regulation of RMS migration and differentiation after OB neurogenesis, but that animals maintain normal olfactory function in the absence of PCD.

O impacto da imigração no sistema familiar: o caso dos ucranianos de Antonio Olinto, PR

Several studies that analyze process connected to emigration suggest that the abandonment of homeland would be followed by the firm intention of building a new reality. In special, the migratory chains from the second half of century XIX would have this hope strongly based on the search of social mobility. What expelled them from Europe, mostly, were economic factors and, thus, would be implicit that the participants of that migratory adventure had a firm belief on the strength of the compensatory mechanisms that could assure them other conditions and social status. This article intends to verify how this idea applies and, therefore, presents a discussion based on the familiar system of Ukrainian immigrants that settled in Parana in 1895. The discussion is guided by the presuppose that a familiar system expresses a collective option and so shows a strong cultural side whose stability not necessarily is threatened by immigration. Key words: familiar system, Ukrainians, immigration.

Enriched Environment Increases Neural Stem/Progenitor Cell Proliferation and Neurogenesis in the Subventricular Zone of Stroke-Lesioned Adult Rats

The subventricular zone in the adult brain is identified as an endogenous resource of neuronal precursors that can be recruited to adjacent lesioned areas. The hypothesis was tested that postischemic environmental enrichment might enhance subventricular zone cell genesis. A cortical infarct was induced in adult spontaneously hypertensive rats by ligating the middle cerebral artery distal to the striatal branches, after which animals were housed in either standard or enriched environment and allowed to survive for 5 weeks. The thymidine analogue bromodeoxyuridine was administered during the first postischemic week. The generation of neural stem/progenitor cells and neuronal precursors in the subventricular zone were studied with cell specific markers such as Ki67 and phosphorylated histone H3 (cell proliferation), Sox-2 (neural stem/progenitor cells), bromodeoxyuridine (slowly cycling, nonmigratory putative neural stem cells), and doublecortin (newborn immature neurons). Proliferating cells in the subventricular zone were identified as chiefly neural progenitors but also putative neural stem cells and neuronal precursors. Five weeks after stroke, proliferation in the subventricular zone was lower in stroke-lesioned rats housed in standard environment compared with nonlesioned rats. Postischemic environmental enrichment normalized cell proliferation levels, increased the numbers of putative neural stem cells as assessed with bromodeoxyuridine, and increased doublecortin-positive neuroblasts, which extended in migratory chains toward the infarct. Enriched environment increased the neural stem/progenitor cell pool and neurogenesis in the adult subventricular zone 5 weeks after a cortical stroke. This might be of potential importance for tissue regeneration.

The role of the underground economy in irregular migration to Italy: Cause or effect?

As three mass legalisations have revealed, migrants in Italy were predominantly staying on without a permit and without being entitled to pursue regular work. It was further uncovered that many legal migrants carried out unregistered work in agriculture, building, housekeeping, street trading, small manufacturing firms and within urban services. The huge involvement of migrant workers in the underground economy is often seen as an indicator of an oversupply of migrants. The underground economy, however, has been well established in Italy for a considerable period and migrants cannot be said to have brought it about, although they have doubtless contributed towards its continuation. Most migrants are employed in occupations which are at risk of being priced out of the market because of their high labour intensity and low growth in productivity. The only means of reducing the labour costs is to employ workers on an irregular basis. Northern regions are close to full employment and in the southern areas most job seekers are educated youths living with parents who can support their wait for a suitable opportunity. The national supply of labour power amenable to giving up the guarantees of regular jobs thus exhausted, the demand was for immigration. Migratory chains transmit an image of Italy being a country where it is easy to stay and to earn an income, even in the absence of a permit to stay and the presence of a significant underground economy means that Italy exerts a particular pull effect on those migrants more prone to accepting irregular conditions.